ASME Conference Presenter Attendance Policy and Archival Proceedings

2012;():i. doi:10.1115/ESDA2012-NS2.

This online compilation of papers from the ASME 2012 11th Biennial Conference on Engineering Systems Design and Analysis (ESDA2012) represents the archival version of the Conference Proceedings. According to ASME’s conference presenter attendance policy, if a paper is not presented at the Conference, the paper will not be published in the official archival Proceedings, which are registered with the Library of Congress and are submitted for abstracting and indexing. The paper also will not be published in The ASME Digital Collection and may not be cited as a published paper.

Commentary by Dr. Valentin Fuster

Applied Fluid Mechanics

2012;():1-10. doi:10.1115/ESDA2012-82022.

The open sump is a typical inlet passage for small to middle-sized pumping station. It is important for the efficiency and safe operation of pumps that the open sump has an optimum design. The flow through the sump and into the pump is calculated using CFD. The incompressible N-S equations are solved by the finite volume method. The RNG k-ε turbulence model and the SIMPLEC algorithm for pressure-velocity coupling are used. Many different designs for the open sump are considered, the results of which are compared based on common criteria to evaluate the sump performance. Design values for the width, the depth of submergence and the bellmouth shape are derived.

Commentary by Dr. Valentin Fuster
2012;():11-19. doi:10.1115/ESDA2012-82028.

For a town with complex orography and frequently varying winds, like Genova on the Italian Northern coast, the need for a simulation environment to predict the pollutant evolution according to a given traffic load, would be of utmost importance. A simulation approach based on 3D CFD has been developed keeping in mind the final application: it use for decision making. Several meshes have been set up and their effects on the solution evaluated in order to strike a balance between the quality of physical modelling and the computational resources required to handle it. The aim is that of getting useful results in a short timescale (one/two days). The evolution of the 3D flow and the pollutants has been simulated for two reference days with a time resolution of one hour. The effect of the daily evolution of the wind, heat release and pollution emission (traffic) over 24 hours is highlighted and discussed.

Commentary by Dr. Valentin Fuster
2012;():21-27. doi:10.1115/ESDA2012-82054.

In this article we study the return to axi-symmetry for a flow generated after fractal plates in a circular wind tunnel. We consider two sets of plates: one orifice-like and one perforated-like. The mean velocity profiles are presented at different distances from the plate and we study the convergence of a flow rate based on these profiles. The return to axi-symmetry depends on how far was the original plate from an axi-symmetric design. It also depends on the level of iteration of the fractal pattern. In line with results for other flow properties [1, 2] It seems that there is not much to be gained by manufacturing fractal plates with more than three iteration levels.

Topics: Fractals , Orifices
Commentary by Dr. Valentin Fuster
2012;():29-36. doi:10.1115/ESDA2012-82059.

Based on FLUENT software, the standard k–ε turbulence model is adopted to simulate 3D-flow field in the forebay of a combined sluice-pump station. Flow field of the diffusion channel and suction passage is obtained after numerical simulation. Results show that flow in the fore-bay appears side-direction and vortexes exist in it and inlet of the suction passage. According to the results, optimum measures such as changing the wing wall form, extending the sluice pier, adding tri-prisms are conducted on the basis of original design. The vortexes are eliminated finally. Flow in diffusion channel appears front inflow and is improved effectively.

Commentary by Dr. Valentin Fuster
2012;():37-41. doi:10.1115/ESDA2012-82093.

An injection pump is one of the simplest mechanics devices imaginable with no moving parts and a very simple geometry. We examine the device performance for steam injectors using primarily a control volume analysis and consider to what extent this simplified analysis represents optimal performance. We seek the rationale for performing CFD studies and develop optimization scenarios.

Topics: Pumps
Commentary by Dr. Valentin Fuster
2012;():43-50. doi:10.1115/ESDA2012-82119.

Because of the increasing panel size, the difficulty on delivering the glass substrate has been enhanced dramatically and become a critical problem in the LCD manufacturing industry. Nowadays, most of panel fabrication factory utilize the fully-automated delivering technology instead of the traditional labor delivery for diminishing the possibility of polluted particles on the LCD board. Thus, this study investigates the flow patterns on maintaining the air quality inside the delivering facility with a moving elevator. Also, influence on the moving pattern of the elevator via numerical technique is the focus of this investigation. Firstly, CFD code Fluent is used to execute the CFD simulation and evaluate the flow patterns inside this delivery equipment. It is found that the inferior air is generated mainly by the increasing vortex inside the delivery equipment for an upward-moving elevator. On the contrary, the flow field becomes very smooth without obvious vortex phenomenon, and thus induces a better air quality when the elevator moves downward. However, a better uniform flow field occurred when the elevator is moving upward. In addition, the airflow uniformity is not effectively improved by reducing the elevator velocity and increasing the FFU airflow velocity. It is not evident for improving the pollute exclusion by reducing elevator moving velocity which slows down the transporting efficiency, so it is suggested that the moving speed of elevator should maintain at 0.16m/s. On another way, it is useful to enhance the capability of pollute exclusion by increasing the FFU’s air velocity, thus it is proposed to raise FFU velocity to 0.71m/s. Consequently, it is concluded that the moving pattern of elevator has an essential impact and can be utilized to improve the air quality inside the LCD delivery facility.

Topics: Elevators
Commentary by Dr. Valentin Fuster
2012;():51-62. doi:10.1115/ESDA2012-82205.

The identification of the water cavitation regime is an important issue in a wide range of machines, as hydraulic machines and internal combustion engine. In the present work several experiments on a water cavitating flow were conducted in order to investigate the influence of pressures and temperature on flow regime transition. In some cases, as the injection of hot fluid or the cryogenic cavitation, the thermal effects could be important. The cavitating flow pattern was analyzed by the images acquired by the high-speed camera and by the pressure signals. Four water cavitation regimes were individuated by the visualizations: no-cavitation, developing, super and jet cavitation. As by image analysis, also by the frequency analysis of the pressure signals, different flow behaviours were identified at the different operating conditions. A useful approach to predict and on-line monitoring the cavitating flow and to investigate the influence of the different parameters on the phenomenon is the application of Artificial Neural Network (ANN). In the present study a three-layer Elman neural network was designed, using as inputs the power spectral density distributions of dynamic differential pressure fluctuations, recorded downstream and upstream the restricted area of the orifice. Results show that the designed neural networks predict the cavitation patterns successfully comparing with the cavitation pattern by visual observation. The Artificial Neural Network underlines also the impact that each input has in the training process, so it is possible to identify the frequency ranges that more influence the different cavitation regimes and the impact of the temperature. A theoretical analysis has been also performed to justify the results of the experimental observations. In this approach the nonlinear dynamics of the bubbles growth have been used on an homogenous vapor-liquid mixture model, so to couple the effects of the internal dynamic bubble with the other flow parameters.

Commentary by Dr. Valentin Fuster
2012;():63-72. doi:10.1115/ESDA2012-82300.

Pressure losses in the suction and discharge components of a reciprocating compressor are the main irreversibilities that affect the global system efficiency; their prediction is a critical issue for the evaluation of the absorbed power.

Flow coefficients for automatic valves are often derived from experimental data obtained on a dedicated test bench. Conversely, there is a lack of information concerning the flow behavior in the other components along the gas path and their losses are often taken into account by correcting the valve’s flow coefficient by means of an empirical correlation.

CFD simulation of the entirety of the suction and discharge systems is a viable alternative for the prediction of the global pressure losses, although these simulations are very demanding in terms of computational resources.

This paper presents an approach to reducing the computational effort required to perform the CFD analysis of a reciprocating compressor.

A set of CFD simulations with different suction system geometry configurations has been performed in order to evaluate the dependence of a component pressure loss on the losses of the upstream components. The losses along the suction system can then be evaluated separately from the valve loss by neglecting the presence of the valve itself. The valve can be replaced by an equivalent porous region that straightens the outgoing flow. This approach leads to a decrease in both the mesh size and complexity, and an increase in general applicability.

Commentary by Dr. Valentin Fuster
2012;():73-82. doi:10.1115/ESDA2012-82332.

The dynamics of very low aspect ratio wings (or strakes) vortices in slender bodies are complex due to the interaction of the shed vortex sheet and the body vortex. For missiles at supersonic speeds these interactions are not easily predicted using engineering level tools. To shed some new light onto this problem, an experimental study in a water channel for moderate Reynolds number (Re = 1000) was performed for a 19D body and strake configuration with strakes having a span to body diameter ratio of 1.25. Comparisons to numerical simulations in supersonic flow are also performed. Flow visualisation has been carried out to characterize the vortex dynamics at different angles of attack; these being 11°, 16°, 22° and 27°. The comparison between a slender body without strakes and the body-strake configuration has given some key indicators in relation to the vortex position of the core. Furthermore, unsteady wing-body interference has been observed at angles of attack above 20° for both experimental and numerical simulations. Consequently, the average position of the vortex core is located at larger distances from the missile in comparison to the body without strakes. The numerical simulations show good correlation with the experimental tests even though the dynamic convective interactions between the body vortex and strake vortex sheet are not predicted.

Topics: Wings
Commentary by Dr. Valentin Fuster
2012;():83-89. doi:10.1115/ESDA2012-82337.

Large eddy simulation is used to study the flow over a backward-facing step interacting with a periodic array of streamwise microjets emenating from the step at a 45° angle to the step face. Averaged streamwise velocity profiles are in good agreement with experimental data. A well defined turbulent inlet profile for the microjet is found to be important to obtain correct streamwise normal fluctuations near the step. To simulate cases as per the experimental setup a microjet inlet pipe section is necessary for the simulations. The studies with passive scalars need to be conducted to quantify scalar mixing. The monotonicity problem of simulating passive scalar can be overcome by simply clipping the unbounded values. This technique works because the volume occupied by overshoot values of passive scalar are small compared to the total volume of the backward-facing step geometry.

Topics: Flow (Dynamics)
Commentary by Dr. Valentin Fuster
2012;():91-100. doi:10.1115/ESDA2012-82365.

In this paper, the use of computational fluid dynamics is evaluated as a design tool to investigate the indoor climate of a confined greenhouse. The finite volume method using polyhedral cells is used to solve the governing mass, momentum and energy equations. Natural convection in a cavity corresponding to a mono-span venlo-type greenhouse is numerically investigated using Computational Fluid Dynamics. The CFD model is designed so as to simulate the climate above a plant canopy in an actual multi-span greenhouse heated by solar radiation. The aim of this paper is to investigate the influence of various design parameters such as pitch angle and roof asymmetry and on the velocity and temperature patterns inside a confined single span greenhouse heated from below. In the study reported in this paper a two-dimensional CFD model was generated for the mono-span venlo-type greenhouse, and a mesh sensitivity analysis was conducted to determine the mesh independence of the solution. Similar two-dimensional flow patterns were observed in the obtained CFD results as the experimental results reported by Lamrani et al [2]. The CFD model was then modified and used to explore the effect of roof pitch angle and roof asymmetry at floor level on the development of the flow and temperature patterns inside the cavity for various Rayleigh numbers. Results are presented in the form of vector and contour plots. It was found that considerable temperature and velocity gradients were observed in the centre of the greenhouse for each case in the first 40mm above the ground, as well as in the last 24mm close to the roof. Results also indicated that the Rayleigh number did not have a significant impact on the flow and temperature patterns inside the greenhouse, although roof angle and asymmetry did. The current results demonstrate the importance of CFD as a design tool in the case of greenhouse design.

Commentary by Dr. Valentin Fuster
2012;():101-110. doi:10.1115/ESDA2012-82370.

The simulation of multiphase compressible flows through high pressure nozzles is presented. The study uses the developed numerical approach. There are many important engineering applications which are concerned with multiphase flows and convergent-divergent nozzles. This work presents the developed extension of the model and numerical algorithm based on the so called parent model earlier introduced by Saurel and Abgrall [Saurel, R. and Abgrall, R., A Multiphase Godunov Method for Compressible Multifluid and Multiphase Flows, J. Comput. Phys. 150 (1999), 425–467]. This model which consists of conservation laws for each phase complemented with the volume fraction evolution equation is modified by adding a source term to simulate area variation. The model is strictly hyperbolic and non-conservative due to the existence of non-conservative terms. The model is able to deal with compressible and incompressible flows. Moreover, it can deal with mixtures and pure fluids, where each fluid has its own pressure and velocity. The presence of velocity and pressure relaxation terms in the governing equations has made the velocity and pressure relaxation processes essential to tackle the boundary conditions at the interface. The interface separating phases is considered as a numerical diffusion zone in this method. The model is solved using an efficient Eulerian numerical method. A second order Godunov-type scheme with approximate Riemann solver is used to enable capturing of a physical interface by the resolution of the Riemann problem. The solution is obtained by splitting the hyperbolic part and source terms parts in the numerical algorithm. The source terms, including relaxation parts of the model, are tackled in succession using Strang splitting technique. The governing equations are solved at each computational cell using the same numerical algorithm for the whole domain including the interface. The main aim of this work has been to study different flow regimes with respect to pressure boundary conditions through the numerical solutions of single and multiphase flows. The performance of the programme has been verified via well established benchmark test problems for multiphase flows.

Commentary by Dr. Valentin Fuster
2012;():111-127. doi:10.1115/ESDA2012-82418.

Air flow management in a Data-center is a critical problem when designing HVAC (Heating, Ventilation and Air-Conditioning) system. Providing a sufficient cooling air volume at a designed temperature to all the informatics equipments, avoiding recirculation phenomenon, optimizing the installations in order to minimize the temperature difference between air exiting the CRAC (Computer Room Air Conditioning) and the air at the intake of the servers are parts of the multiples target that have to be reached in order to have the most efficient ventilation system.

In most of today’s data center, the IT (Information Technology) equipment dissipates between 12kW of heat for regular material, to up to 32kW for the recent high density server’s rack. Such a power release has to be cooled by efficient cooling system.

During this process the airflow temperature can increase by over 10K, and the air velocity can vary from 0.09m/s to more than 5m/s. Considering these large gradient of temperature and air speed several phenomenon must be taken into account, including turbulent natural convection.

To achieve these goals, we will use a CFD software to predict the airflow behaviour inside the Data-center. Therefore, the code must be able to accurately model turbulent airflow and heat transfers. We used the software (http/www.thetis.enscbp.fr) to simulate a 2D turbulent natural convection in a square cavity. The k-ε equations were solved to predict turbulent effects. The obtained results were compared to an experimental benchmark and are presented in the document.

In the last part of the paper we present the results of a 2D simulation representing a working server in a computer room cooled by a CRAC (Computer Room Air Conditioning) unit.

The airflow characteristics in the whole domain were determined using various dimensionless numbers in order to select the right physical and mathematical objects. Finally the results of a 3D simulation are presented and the cooling system performances are estimated.

Commentary by Dr. Valentin Fuster
2012;():129-136. doi:10.1115/ESDA2012-82446.

This work deals with the complete stability analysis in the case of two dimensional fluid flows searching for steady and Hopf bifurcations.

The stability analysis starts with the computation of steady bifurcations. It is realized by first considering the monitoring of an indicator which is a scalar function. The indicator is computed via a perturbation method: the Asymptotic Numerical Method. Steady bifurcation point corresponds to the zero of this indicator. From this singular point, all the steady bifurcated branches are computed by using the perturbation method.

Then the stability analysis is pursued with the computation of Hopf bifurcations by a hybrid method. This latter consists in coupling a continuation method with a direct Newton solver.

The continuation method allows the bifurcation indicator to be determined using alternating reduced order and full size steps resolution. The quantities coming from the bifurcation indicator are used as initial approximations for the direct method iterations.

Then an augmented system whose solutions are Hopf bifurcation is solved by a direct method of Newton kind.

The examples of the one side and two sides lid driven cavities show the reliability and the efficiency of the proposed numerical tools.

Commentary by Dr. Valentin Fuster
2012;():137-146. doi:10.1115/ESDA2012-82462.

Fluid-Structure Interactions are present in a large number of systems of nuclear power plants and nuclear on-board stoke-holds. Particularly in steam generators, where tube bundles are submitted to cross-flow which can lead to structure vibrations. We know that numerical studies of such a complex mechanism is very costly, that is why we propose the use of reduced-order methods in order to reduce calculation times and to make easier parametric studies for such problems.

We use the multiphase-POD approach, initially proposed by Liberge (E. Liberge; POD-Galerkin Reduction Models for Fluid-Structure Interaction Problems, PhD Thesis, Universite de La Rochelle, 2008). This method is an adaptation of the classical POD approach to the case of a moving structure in a flow, considering the whole system (fluid and structure) as a multiphase domain. We are interested in the case of large displacements of a structure moving in a fluid, in order to observe the ability of the multiphase-POD technique to give a satisfying solution reconstruction. We obtain very interesting results for the case of a single circular cylinder in cross-flow (lock-in phenomenon). Then we present the application of the method to a case of confined cylinders in large displacements too. Here again, results are encouraging.

Finally, we propose to go further presenting a first step in parametric studies with POD-Galerkin approach. We only consider a flowing-fluid around a fixed structure and the Burgers’ equation. A future work will consist in applications to fluid-structure interactions.

Commentary by Dr. Valentin Fuster
2012;():147-156. doi:10.1115/ESDA2012-82529.

Despite constantly improving computer capabilities, classical numerical methods (DNS, LES,…) are still out of reach in fluid flow control strategies. To make this problem tractable almost in real-time, reduced-order models are used here. The spatial basis is obtained by POD (Proper Orthogonal Decomposition), which is the most commonly used technique in fluid mechanics. The advantage of the POD basis is its energetic optimality: few modes contain almost the totality of energy. The ROM is achieved with the recent developed optimal projection [1], unlike classical methods which use Galerkin projection. This projection method is based on the minimization of the residual equations in order to have a stabilizing effect. It enables moreover to access pressure field. Here, the projection method is slightly different from [1]: a formulation without the Poisson equation is proposed and developed. Then, the ROM obtained by optimal projection is introduced within an optimal control loop. The flow control strategy is illustrated on an isothermal square lid-driven cavity and an anisothermal square ventilated cavity. The aim is to reach a target temperature (or target pollutant concentration) in the cavity, with an interior initial temperature (or initial pollutant concentration), by adjusting the inlet fluid flow rate.

Topics: Flow control
Commentary by Dr. Valentin Fuster
2012;():157-166. doi:10.1115/ESDA2012-82565.

This work presents the development and application of a new optimal design methodology for Turgo impulse hydro turbines. The numerical modelling of the complex, unsteady, free surface flow evolved during the jet-runner interaction is carried out by a new Lagrangian particle method, which tracks a number of representative flow elements and accounts for the various hydraulic losses and pressure effects through special adjustable terms introduced in the particle motion equations. In this way, the simulation of a full periodic interval of the flow field in the runner is completed in negligible computer time compared to the corresponding needs of modern CFD software. Consequently, the numerical design optimization of runner geometry becomes feasible even in a personal computer and affordable by small and local manufacturers. The bucket shape of a 70 kW Turgo model is properly parameterized and numerically optimized using a stochastic optimization software to maximize the hydraulic efficiency of the runner. The optimal runner and the rest turbine parts are then manufactured and installed in the Lab for testing. Detailed performance measurements are conducted and the results show satisfactory agreement with the numerical predictions, thus validating the reliability and effectiveness of the new methodology.

Commentary by Dr. Valentin Fuster
2012;():167-175. doi:10.1115/ESDA2012-82579.

A new technique for simulating engine pressure waves consisting of linking pressure response and mass flow rate excitation in the frequency domain has been presented. This is achieved on the so-called “dynamic flow bench”. With this new approach, precise, fast and robust results can be obtained while taking into account all the phenomena inherent to compressible unsteady flows. The method exhibited promising results when it was incorporated in a GT-Power/Simulink coupled simulation of a naturally aspirated engine.

However, today’s downsized turbocharged engines come with more stringent simulation necessities, where discontinuities such as the charge air cooler (CAC) must be correctly modeled. Simulating such engines with the transfer function methodology is quite difficult because it requires mounting the entire intake line on the bench. Modeling wave action for these engines requires an understanding in the frequency domain of the flow’s characteristics through the different elements that make up the intake line. This leads us to study the acoustic transfer matrices.

In order to split the intake line into separate elements, a straight duct of 185mm length is chosen as a first reference. It is mounted on the dynamic flow bench and pressure response is measured after an impulse mass flow excitation. Transfer functions of relative pressure and mass flow rate are then identified at given points upstream and downstream of this reference tube. These functions produce the desired transfer matrix poles.

The resulting matrix is validated by inserting the tube in the intake lines of two four-cylinder engines which are modeled in GT-Power. Pressure and mass flow are registered at the measurement points of the tube from the simulation. The time series data upstream of the tube is treated in the frequency domain and the transfer matrix is used to calculate the corresponding downstream values. Measured values from the native simulation and those calculated using the transfer matrix propagation are then compared.

Finally, the experimental technique for identifying transfer matrices of more complex elements using two versions of the previous tube is presented.

Commentary by Dr. Valentin Fuster
2012;():177-184. doi:10.1115/ESDA2012-82591.

Efficiency is becoming more and more a main concern in the design of power transmissions and the demand for high efficiency gearboxes is continuously increasing. Also the new restrictive euro standards for the reduction of pollutant emissions from light vehicles impose to improve the efficiency of the engines but also of the gear transmissions. For this reason the resources dedicated to this goal are continuously increasing.

The first step to improve efficiency is to have appropriate models to compare different design solutions. Even if the efficiency of transmissions is quit high if compared to the efficiency of the engines and appropriate models to predict the power losses due to gear meshing, to bearings and to seals already exist, in order to have a further improvement, some aspects like the power losses related to the oil churning, oil squeezing and windage are still to be investigated. These losses rise from the interaction between the moving or rotating elements of the transmission and the lubricant. In previous papers [39, 40, 41 43, 44], the authors have investigated the churning losses of planetary speed reducers (in which there is a relative motion between the “planets + planet carrier” and the lubricant). This report is focused on the oil squeezing power losses. This kind of losses is associated with the pumping of the oil at the gear mesh, where there is a contraction of the volume between the mating gears due to the rotation of them and a consequent overpressure. This overpressure implies a fluid flow primarily in the axial direction and this, for viscous fluids, means additional power losses and a decrease of the efficiency. In this work this phenomena has been studied by means of some CFD (computational fluid dynamic) simulations with a VOF (volume of fluid) approach. The influence of some operating conditions like the rotational speed and the lubricant temperature have been studied.

The results of this study have been included in a model to predict the efficiency of the whole transmission.

Commentary by Dr. Valentin Fuster
2012;():185-191. doi:10.1115/ESDA2012-82616.

Ducted Wind Turbines have been the subject of numerous studies in the past (both analytic and experimental), but the concept has not found commercial use so far, mainly due to the poor performance of the tested configurations. Our analytical studies, however, have shown that an optimized configuration of a Ducted Wind Turbine with ejector type assist for the exhaust may generated Power Coefficients of the order of CP = 6. This corresponds to the output of nearly 15 conventional un-ducted wind Turbines (with a typical CP = 0.4). The present study simulates the Two Dimensional simplification of such a Wind Turbine Plant by employing the commercial code FLUENT and compares its performance against the case of an open (no turbine) duct.

Commentary by Dr. Valentin Fuster
2012;():193-199. doi:10.1115/ESDA2012-82645.

An oscillatory, zero-net-mass flux actuator system, Jet and Vortex Actuator (JaVA), is implemented on the step wall of a backward facing step. JaVA is shown previously both experimentally and numerically that it can energize the boundary layer by creating jets or vortices thus it may delay flow separation when used properly. The main part of JaVA is a rectangular cavity with a moving actuator plate. The actuator plate is mounted asymmetrically inside the cavity of the JaVA box, such that there are one narrow and one wide gap between the plate and the box. The main governing parameters are the actuator plate’s width (b), the amplitude (a) and the operating frequency (f). The main target of the control with active jets on the step wall is to influence directly the main recirculation zone, thus as the actuator plate or the step’s vertical wall moves periodically in horizontal direction, a jet emerges into the recirculation zone. Non-dimensional numbers such as the scaled amplitude (Sa = 2πa/b) and the jet Reynolds number (ReJ = 4abf/ν) as well as the maximum cross flow velocity characterize the JaVA-induced flow types and effects on the recirculation zone. One period consists of one blowing and one suction phase into the recirculation zone. The actuator plate has a sinusoidal motion determined by the amplitude and the operating frequency. Time-averaged flow fields and boundary layer profiles for actuated and not actuated cases at various operating frequencies indicate the effect of active flow control. The control effectiveness is given by the ratio of the jet Reynolds number to the Reynolds number of the incoming flow (r = ReJ/Re). A transient finite-volume-based laminar, incompressible Navier-Stokes solver (Fluent) has been used to study the flow fields generated by JaVA. The computational domain consists of a moving zone along the channel and the motion of the actuator plate is generated by a moving grid imposing appropriate boundary conditions with User-Defined-Functions (UDF). Numerical simulations reveal the JaVA-boundary layer interaction in the narrow channel for various governing parameters such as frequencies (jet Reynolds numbers) and channel flow velocities (Reynolds numbers, Re = 200, 400 and 800). The proposed control method based on suction and blowing with an oscillating backward facing step (OsBFS) seems to be effective in shortening the recirculation zone length and delaying the flow separation downstream of the backward facing step.

Topics: Flow control
Commentary by Dr. Valentin Fuster
2012;():201-210. doi:10.1115/ESDA2012-82658.

This paper is concerned with performance improvement of a centrifugal compressor by evolution of an inverse design method for 3D design approaches. The design procedure encompasses two major steps. Firstly, using the BSA inverse design algorithm on the meridional plane of the impellers, the meridional geometries for impellers are defined based on modified pressure distribution. Furthermore, an original and progressive algorithm is developed for 3D design of angular coordinates of the impellers on the blade to blade planes of them based on blades loading improvements. Full 3D analysis of the designed compressor using Reynolds Average Navier-Stokes equations, and its comparison with the analysis results of the current compressor, shows that the total pressure ratio of the designed compressor at the same operation condition is enhanced more than 5 percent.

Commentary by Dr. Valentin Fuster
2012;():211-222. doi:10.1115/ESDA2012-82710.

The depletion of global crude oil reserves, increases in fossil fuel prices and environmental issues have encouraged the search for and study of bio-derived fuels. For years, fatty acid methyl esters (FAME) have already been used successfully. High-quality hydrogenated vegetable oil and Fischer-Tropsch biofuels have also been developed.

Fuel refining processes, however, consume energy increasing CO2 emissions. For profitability reasons, large-scale industrial production is also required. Several distributed energy producers are instead willing to utilize various local waste materials as fuel feedstock. The target is local fuel production without any complicated manufacturing processes.

Crude bio-oils are therefore also interesting fuel options, in particular for medium-speed diesel engines capable of burning such bio-oils without any major problems. Nevertheless, waste-derived crude bio-oils have also been studied in Finland in high-speed non-road diesel engines. One option has been mustard seed oil (MSO). Mustard has been cultivated in fallow fields. Non-food mustard seeds have been used for fuel manufacturing.

In the performed studies with MSO, the exhaust smoke and HC emissions decreased, NOx remained approximately constant, and the thermal efficiency was competitive compared with operation on ordinary diesel fuel oil (DFO). The number of exhaust particles tended, however, to increase and deposits were formed in the combustion chamber, particularly if the engine was also run at low loads with MSO. On the whole, the results were so promising that deeper analyses of engine operation with MSO were considered reasonable.

The kinematic viscosity of crude bio-oils is much higher than that of FAMEs or DFO. Consequently, the injection pressure tends to increase especially at the injection pump side of an in-line injection pump system. The flow characteristics of crude bio-oil also differ from those of DFO in the high-pressure pipe. With bio-oil, the flow seems to be laminar. The bulk modulus of bio-oils is also different from that of DFO affecting the rate of the injection pressure rise.

In the present study, a turbocharged, inter-cooled direct-injection non-road diesel engine was driven with a mixture of MSO (95%) and rape seed methyl ester (RME, 5%), and standard DFO. The engine was equipped with an in-line injection pump.

First, the injection pressures at pump and injector ends of the high-pressure injection pipe were measured for both fuels as a function of crank angle. Furthermore, a model was created for the injection system based on the method of characteristics.

Free software called Scilab was adopted for numerical simulation of the model. Despite a few limitations in the built model, the results showed clear trends and the model can be used to predict changes in the fuel injection process when the fuel is changed.

Commentary by Dr. Valentin Fuster
2012;():223-230. doi:10.1115/ESDA2012-82781.

Numerical test and eigenvalue analysis for a two-phase channel flows for energy conversion systems like fuel cells or water electrolysers with flow regime transitions are performed by using the well-posed system of equation that takes into account the pressure jump at the phasic interface. The interfacial pressure jump terms derived from the definition of surface tension which is based on the surface physics make the conventional two-fluid model hyperbolic without any additive terms, i.e., virtual mass or artificial viscosity terms. The four-equation system has three sets of eigenvalues; each of them has an analytical form of real eigenvalues relevant to the sonic speeds with phasic velocities of three typical flow regimes such as dispersed, slug, and separated flows. Further, the eigenvalues for the flow transition regions can also be obtained numerically for smooth calculation of flow regime transitions. The sonic speeds agree well not only with the earlier experimental data but also with those of an analytical model. Owing to the hyperbolicity of this model, we can adopt an upwind method, which is one of the well-known Godunov type upwind methods. A typical example of two-phase flows shows that the present model can simulate the phase separation caused by density difference of two-phase fluids.

Commentary by Dr. Valentin Fuster
2012;():231-240. doi:10.1115/ESDA2012-82817.

This paper presents the development of two classes of sensors based on microthermocouples with different wire diameters (from 7.6 μm to 25.4 μm). The first one uses the pulsed-wire technique for the couple velocity/temperature measurement. These sensors are used with three different techniques we developed in our laboratory: the time of flight method, the oscillation frequency method and the phase method. Because the purpose of this kind of sensor is to be introduced in different microdevices, it is realized with two thermocouple wires and does not use the micromachining technologies. Its working principle is close to that of the hot wire anemometer and it presents the same advantages such as very small dimensions and weak response time. The sensor is developed in order to measure flows and temperatures in microsystems like small channels (width < 500 μm), microtubes (diameter < 53 μm) and small structures (volume < 100 μm3). The second class of sensors are based on the multi-wire thermocouple technique. In this paper we present a probe using two wires of same nature but different in diameter located close together at the measurement point. This probe is used to measure simultaneously the temperature and the velocity of flowing gas. Results will focus on oscillating flows of gas.

Commentary by Dr. Valentin Fuster

Electromechanical Systems and Mechatronics

2012;():241-249. doi:10.1115/ESDA2012-82024.

Magnetorheological (MR) brakes provide variable friction torque by electronically changing the viscosity of a magnetic fluid inside the actuator. The MR-brakes have many desirable characteristics, such as high torque-to-volume ratio, inherent stability and ease of control. However, the design process of such an actuator is complex and time consuming due to many parameters involved in the design, including geometric and physical factors and their interactions.

The first contribution of this research is a new optimization approach where we combined the Taguchi optimization method with parameterized magnetic finite element analysis. Unlike other optimization techniques, this method can identify the dominant parameters of the design and investigate their interactions with the design output while reducing the search space and the design time. The second contribution is the design optimization of a novel MR-brake, which incorporates a serpentine flux path and a permanent magnet. To the best of our knowledge, this is the first such MR-brake. The new MR-brake design provides a fail-safe feature while reducing the volume by decreasing the number of coil turns required. Results showed that some of the geometric parameters and the current have the most significant effect on the torque output out of the 12 design parameters.

Commentary by Dr. Valentin Fuster
2012;():251-260. doi:10.1115/ESDA2012-82048.

This paper proposes to use a non-linear observer to build the state and the external force of flexible manipulator robots during their machining (composite materials) processes or Friction Stir Welding (FSW) processes. These two different processes have a problem in common: the flexibility of the robot can not be neglected, that is to say, the errors due to the deformation of the links should be taken into account. However, in most industrial robots, the real positions and velocities of each link are not measured, so in this study, an observer is proposed to reconstruct the real angular positions and velocities of links by using the measured angular positions and the velocities of actuators. A simulation by Matlab/Simulink has been carried out with a 2 axis Robot during its machining processes: the proposed observer showed great performances in estimating the state of the robot (position and velocity). Then, in order to improve the tracking accuracy in the tool frame, the state of the external force along the forward direction (x) and its normal direction (y) are required, while they are also not measured by our robot. A disturbance observer has been added to reconstruct the processing force. A good precision during the proposed processes have been obtained using the latter. This study contributes to solve the problem from the point of view of accuracies during the machining processes.

Commentary by Dr. Valentin Fuster
2012;():261-264. doi:10.1115/ESDA2012-82100.

This study presents a viscosity sensor that converts the vibration amplitude at the resonance frequency of a needle immersed in viscous fluid, into electric current. The goal of this work is to provide a dedicated numerical tool for the sensor design, that couples fluid, structure and magnetism.

Topics: Fluids
Commentary by Dr. Valentin Fuster
2012;():265-274. doi:10.1115/ESDA2012-82127.

In haptics applications actuators with compact volume and high force output are desired for stable and stiff interfaces. Magnetorheological (MR) brakes are viable options since they have large force-to-volume ratios. However, linear MR-brakes available on the market have limited stroke due to the piston-cylinder design and show viscous damping behavior where the force output highly depends on the velocity of the actuator resulting in a high off-state friction force. Another problem is the inherent magnetic hysteresis, which requires complex control systems.

In this research, we focused on the development and control of a linear MR-brake with infinite stroke and minimal off-state friction. The common piston-cylinder arrangement was removed from the design to address the limited stroke and high off-state-friction issues. The serpentine flux path methodology was followed to achieve compact geometry. Three control strategies namely, open-loop control, force feedback control, and current feedback with Preisach model, were implemented on the developed prototype. The results using Preisach model showed that the hysteresis could be reduced significantly without the need for an expensive force sensor in the control loop.

Our new device has a 3% ratio of the off-state friction force to the maximum force output in comparison to more than 10% for most MR-damper devices in the literature. At the same time, our prototype is about half the size of a commercially available product.

Topics: Brakes
Commentary by Dr. Valentin Fuster
2012;():275-280. doi:10.1115/ESDA2012-82147.

The global stabilization of the classical ball & beam has been approached in the literature through saturated control which imposes restrictions on the reactivity of the closed loop. In this work a modified design for the classical ball & beam system is presented. The beam is driven by two actuators (see figure 1). In comparison to the classical system, this design offers an additional degree of freedom which is the vertical motion of the beam. We show that the new design offers the possibility to get rid of the closed loop low reactivity restriction. We propose two nonlinear controllers to steer the trajectories of the system towards a final desired position. The first controller adapts, to the new design, existing controllers from the literature for the classical ball & beam. The second controller uses the additional degree of freedom to provide a faster stabilization.

Commentary by Dr. Valentin Fuster
2012;():281-289. doi:10.1115/ESDA2012-82150.

Composing of models and simulation of statics, steady state conditions and dynamic responses of an electro-hydraulic servovalve is considered in the paper. The observed servovalve contains an electro-mechanical transducer (as a torque motor), a nozzle-and-flapper valve and a sliding spool in sleeve with elastic position feedback from spool to flapper. For composing mathematical models of the servovalve multi-pole models of functional elements are used. For representing relations between inner variables oriented graphs are used.

Results of the current work will be used in modeling and simulation of electro-hydraulic servo-systems.

Commentary by Dr. Valentin Fuster
2012;():291-299. doi:10.1115/ESDA2012-82167.

An electro-magneto-mechanical system, composed of the electromagnet, having an iron core with a coil and a movable yoke, is analyzed in the paper. Exposing the yoke to mechanical motion, the variation of the magnetic flux due to change of the air gap height induces alternating voltage at the coil terminals. If the electrical circuit is closed, the so generated electrical power is dissipated via the internal coil losses, treated in this paper. Thanks to the interaction between the electrical and mechanical system (i.e. via magnetic force), the power dissipation in electrical circuit influences the dynamical response of the mechanical system. And so the mechanical vibrations can be controlled by these means.

The mathematical model of the simplified dynamical system, which describes behavior of the experimental set-up, is derived using a lumped parameter approach.

The aim of the article is to identify parameters of the derived mathematical model, focused mainly on electrical circuit. Based on measured experimental data, the static constants as well as dynamic losses were analyzed.

Commentary by Dr. Valentin Fuster
2012;():301-310. doi:10.1115/ESDA2012-82212.

This paper deals with the fast modeling and fast multiobjective optimal design of mechatronic systems. To solve this problem, the object-oriented modeling language Modelica and object-oriented programming language Java have been used to build an innovate software platform. This platform has been designed to allow multidisciplinary design optimization of complex systems using a free platform. This platform only contains open-source tools and frameworks and was validated on an optimization application: the stabilization of a quarter-car system.

Commentary by Dr. Valentin Fuster
2012;():311-321. doi:10.1115/ESDA2012-82230.

As the design of mechatronic systems relies on different technical and scientific disciplines, it is often difficult to anticipate, at the earliest, the consequences of design choices on the final product. The role of the evaluation process is to support designers each time engineering choices must be made or justified. Being able to estimate the impact of design decisions on key technical performance indicators is one objective of our research. After having presented the activities of the evaluation process, we propose a meta-model of the data required by evaluation in the context of the Systems Engineering framework. Then we investigate how the top down and bottom up tracing of technical requirements through Block Systems and between systems engineering layers of the ‘onion model’ may help designers analyze the consequences of design decisions on the final product. The research is illustrated through the development of a wheelchair with electrical assistance so as to allow reduced mobility people to move and work outside with less tiredness.

Topics: Design , Mechatronics
Commentary by Dr. Valentin Fuster
2012;():323-331. doi:10.1115/ESDA2012-82312.

A digital electromagnetic actuator having two displacement directions and four discrete positions is presented. These discrete positions are located at each corner of a closed square bracket where a mobile magnet moves due to Lorentz force generated with a driving current through a wire. An optimized design of this actuator is presented, modeled and tested. At first, plane displacements are presented which proves the ability of the actuator to realize this type of displacement. Second, comparisons between the experimental and modeled displacements are carried out which show a good agreement from dynamic point of view and finally, the measured positioning repeatability errors in discrete position are given.

Commentary by Dr. Valentin Fuster
2012;():333-342. doi:10.1115/ESDA2012-82392.

“Flying machining” represents synchronization of an axis (slave) with a master axis in motion. One of the most important aspects of the design of “flying machining” operation is the choice of the proper law of motion of the slave axis. In literature, technical reports and papers can be found concerning this subject, but they deal with specific problems and the solutions or suggestions proposed are specific as well, suitable for those cases. In order to try to overcome this limitation, in this paper we analyze the subject of the flying machining operations from a wider point of view. We propose a unified design procedure with general validity, suitable for the choice of the slave axis’ law of motion for whatever “flying machining” operation. Furthermore methodologies for the selection of the drive system will be proposed. The procedure is described applying it on a cross sealing operation, typical of wrapping machine.

Topics: Machining , Design
Commentary by Dr. Valentin Fuster
2012;():343-350. doi:10.1115/ESDA2012-82422.

This paper presents a fluid-dynamic analysis of the hydraulic circuit of a shaking table for seismic tests; the model was developed adopting a commercial code. The aim of the study is to provide useful indications for the design of a new optimized control system. The model was developed taking into account all the components of the hydraulic circuit that is made of by the following main items: the axial piston pump, the pressure relief valve, the main control valve, the accumulators, the hydraulic cylinder with variable displacement and all the connecting pipes. Particular attention was given to the modelling of internal resistance of the hydraulic system, that can greatly affect the performance of the shaking table. It has also been accurately modelled the main valve dead zone to highlight its influence on the system dynamics. The results of numerical simulations obtained for different operational conditions are reported and compared with experimental data to show the validation and the performances of the developed model.

Commentary by Dr. Valentin Fuster
2012;():351-357. doi:10.1115/ESDA2012-82454.

Nowadays, the integration of micro-actuators in the micro-systems poses a significant problem due to the complex designs as well as due to the contact power supply systems (e.g., via micro-batteries or via wires). A way to overcome this problem is to provide remote power supply and control to the bistable micro-actuators. It is mainly done by RF (radio-frequency) or optical means. As a consequence, the stability of the two positions of this kind of micro-actuators and the switching time evolution between them have to be studied to determine the robustness of the contactless bistable micro-actuators.

In this work, these system parameters were analysed by the ANOVA (Analysis Of Variance) method during a longlife test for 8 different configurations (Design of Experiments) of bistable micro-actuators controlled by laser. Transient and permanent regimes were observed for the stability of the positions, for the standard deviation around the positions and for the switching time as well. In each case, the transient regime represented only 3% of the total duration of the longlife test. A very good stabilisation was observed in the permanent regime whereas a decrease of the stroke was observed in the transient regime. As a consequence, during this regime, the switching time was reduced compared with the regular values (few seconds, optical power dependent). In the permanent regime, a progressive increase of this factor was noted that indicated the progressive fatigue of the bistable micro-actuator. A second indicator of the micro-actuator fatigue was given by the increase of the standard deviation of the stable position after cycle number 9000. Above this point, the micro-actuator was vibrating during the functioning even if the stability remained acceptable.

Topics: Microactuators
Commentary by Dr. Valentin Fuster
2012;():359-370. doi:10.1115/ESDA2012-82461.

This paper adapts an Ant Colony intelligent Optimization algorithm (ACO) to four design problems important in Mechatronics applications: (1) Stress- and volume minimization of a helical compression spring subject to a set of geometrical and stress constraints for material volume minimization, (2) tuning the gains of a PID-controller for a second-order plant with a transport lag, (3) design of a planetary gear leg of a walking machine for a desired straight line trajectory and driving actuator torque, and (4) synthesis of four-bar mechanisms. A brief overview of the ACO algorithm is first presented and its adaptation to each design problem is explained and demonstrated by way of examples that have been solved by other optimization techniques for comparison. In all four examples, the ACO algorithm produced better results in terms of cost-function values while satisfying all necessary constraints.

Commentary by Dr. Valentin Fuster
2012;():371-376. doi:10.1115/ESDA2012-82468.

Carbon fiber structures have become widespread in civil and mechanical field since they are claimed to offer several advantages such as contained mass and high stiffness. However, these structures are characterized by a very low mechanical damping and, therefore, they are easily subjected to potentially dangerous vibratory phenomenon. Active control techniques have been widely developed to suppress vibration and great progresses have been achieved. On the other hand the research on sensors and actuators to be used is still a research field of interest. The paper discusses the opportunity to use piezoelectric actuators (PZT) and Fiber Bragg Grating sensors (FBGs) to realize a smart structure including in itself both the sensing and the actuating devices. Such a structure is able to measure its state of excitation and to reduce the amplitude of vibration using the embedded actuators.

Commentary by Dr. Valentin Fuster
2012;():377-380. doi:10.1115/ESDA2012-82492.

In this paper a moderate technique has been developed to improve an electromagnetic actuation principle for pumping systems, thus obtaining pulsating flow. This work consists of two parts, namely, a numerical part, in which ANSYS software is adopted to simulate the pumping process, while the experimental part consists of the fabrication and testing of the computer controlled electromagnetic pumping system. The objective of this work is to enhance both flow rate and outlet pressure. This was achieved via two main parameters, namely, the electromagnetic pulse duration and the width of each electromagnet. Results show that flow rate and outlet pressure increase with decreasing the pulse duration and with increasing each electromagnet width.

Commentary by Dr. Valentin Fuster
2012;():381-390. doi:10.1115/ESDA2012-82498.

The dynamic performance of automotive vehicles is influenced by the suspension system design. Suspensions owing damping elements with a wide range of non-linear behaviour can provide higher mobility and better ride comfort performances. Pneumatic suspensions due to their inherent nonlinear behaviour can provide high mobility performance while suspensions with MR dampers can provide this nonlinearity through the controllable damping force produced by the control of the MR fluid. The pneumatic and MR suspension models are usually developed from experimental force-displacement and force-velocity characteristics.

The purpose of this paper is to measure and compare the dynamic characteristics of pneumatic, magnetorheological, and hydraulic shock absorbers. The study is carried out through measuring the characteristics of the different types of dampers at different frequencies and amplitudes using an Electro-Servo Hydraulic (ESH) testing machine. The shock absorber is subjected to sinusoidal excitation of frequency varying from 0 to 10 Hz, and amplitude varying from 0 to 10 mm. In the case of the MR damper, the tests are also done at different current levels of between 0 and 2 amp. The input displacement and acceleration to the shock absorber were measured using an LVDT (Linear Voltage Displacement Transducer) and an accelerometer, respectively while the input velocity was derived from the measured displacement and acceleration. This dual identification of the input velocity was done in order to ensure accurate representation of the velocity. The output force response of the shock absorber was measured by means of a force transducer. The force-displacement and force-velocity characteristics of each shock absorber were subsequently derived from the measured data. The results show the tunability of the MR damper characteristics in comparison to those of the pneumatic and hydraulic dampers.

Topics: Water hammer
Commentary by Dr. Valentin Fuster
2012;():391-397. doi:10.1115/ESDA2012-82528.

The objective of this work is to design and to make a part of a humanoid robot, named HYDROÏD. The keynote is a development of a self-sufficient robot by minimizing energy inputs required for its activity. Currently humanoid robots have a power/weight ratio lower than human, as a consequence a limited autonomy. In this work we propose an innovative knee structure in order to reduce friction, and as a result, increase energy efficiency. In classic knee architectures, the rolling elements are balls in bearings with relatively small curvature radii. Here, the idea is to increase this curvature radius to minimize rolling friction. This new joint is realized by rolling between two pieces (femur and tibia) linked by ligaments, and thus get an architecture similar to that of a human knee. As such, the contact is made by rolling movement without sliding between two cylindrical surfaces with circular section, and for which we need find an innovative actuation mechanism. To take advantage of energy savings achieved, we must optimize the mass distribution so as to achieve the smallest global inertia of the mechanical system. In this work we propose various technological solutions for actuation mechanisms. A comparative study is performed between the different technological choices for actuator (cylinder or rotary actuator) and for transmission (connecting crank arm, belt, gearing, etc.). Of course, this new structure must be in accordance with specifications for the knee about size and weight, as well as amplitude and speed rotation of joint. In this work, our choice is to use electric actuators. These different solutions are evaluated according several criteria such as inertial characteristic (mass and inertia matrix), overall size, energy efficiency and the complexity of the system (number of used pieces). Initially, solutions with pulley and belt or rotary actuators and cables seem to have best performance those other systems with connecting crank arm or gearing. Results should be confirmed from a more accurate determination of transmission efficiency. For prospect, the future works will be about optimization of pieces geometry, and in particular as study the gain due to using curvilinear surfaces with elliptic section. Calculation of stresses in the materials by finite elements will provide more information about optimization of dimensions and shapes. Ultimately, energetic gains obtained with this architecture should be confirm through experimental tests.

Commentary by Dr. Valentin Fuster
2012;():399-408. doi:10.1115/ESDA2012-82536.

The objective of this paper is to present the Spectral Element Method (SEM) as an accurate and efficient design tool for static and dynamic simulations of cantilever based MEMS devices. The microcantilever under consideration is modeled as a Timoshenko beam and discretized using the spectral element formulation that accounts for fringing field and the nonlinearity arising from the electrostatic driving force. The static analysis has been carried out using Picard’s iteration method and the static pull-in displacement and voltage have been calculated. An eigenvalue analysis of this beam is also carried out to determine its natural frequencies. In addition, the dynamics of this cantilever is studied using the explicit Newmark predictor-corrector method to generate the time history. In all cases, the results have been compared to the one-dimensional Finite Element Method and three-dimensional finite element method (implemented through the commercial package COMSOL Multiphysics) to examine the accuracy and computational speed of the proposed SEM. The results of the simulations were also compared to those obtained by experiments in the existing scientific literature.

These comparisons lead to the inference that the SEM is able to reproduce the static and dynamic response of the beam to a high degree of accuracy. It was also found that several numerical features inherent in the SEM lead to a significantly faster computation than the corresponding finite element method for equivalent degrees of freedom. This advantage was verified by using the SEM to carry out static and dynamic simulations of variable width microcantilevers.

We therefore propose that the SEM is a viable tool for the MEMS community to accurately and quickly determine the static and dynamic pull-in parameters, frequency eigenvalues, and static and dynamic behavior at the design stage.

Commentary by Dr. Valentin Fuster
2012;():409-417. doi:10.1115/ESDA2012-82547.

This work is focused on the analysis of the parameter named “accelerating factor” and on its use in choosing the correct electric brushless motor and gearbox in automation field. The “accelerating factor” is analyzed from a phenomenological point of view, analyzing data available on catalogs of motor manufacturers, and from the point of view of the design of such devices, trying to find a relationship between the accelerating factor and the construction parameters of a brushless motor.

The result achieved in this paper is the definition of a specific value of the accelerating factor allowing a better comparison between different motors and helping the designer in the choice of the best motor for a given application.

Commentary by Dr. Valentin Fuster
2012;():419-428. doi:10.1115/ESDA2012-82559.

Roboticists are faced with new challenges in robotic-based manufacturing. Up to now manufacturing operations that require both high stiffness and accuracy have been mainly realized by using computer numerical control machine tools. This paper aims to show that manufacturing finishing tasks can be performed with robotic cells knowing the process cutting phenomena and the robot stiffness throughout its Cartesian workspace.

It makes sense that the finishing task of large parts would be cheaper with robots. However, machining robots have not been adapted for such operations yet. As a consequence, this paper introduces a methodology that aims to determine the best placement of the workpiece to be machined knowing the cutting forces exerted on the tool and the elastostatic model of the robot. In this vein, a machining quality criterion is proposed and an optimization problem is formulated. The KUKA KR270-2 robot is used as an illustrative example throughout the paper.

Commentary by Dr. Valentin Fuster
2012;():429-435. doi:10.1115/ESDA2012-82567.

A MEMS RF switch is expected to undergo 10 billion switching cycles before failure. Until complete physical explanation for these failure modes that include contact adhesion, damping effects, stiction, increases in resistance with time, dielectric breakdown, and electron trapping is fully established, the technology’s numerous advantages cannot be harvested reliably and efficiently. This paper investigates prospective solutions to problems in switch designs by proposing a new design for the switch. We consider the new design from different perspectives: dynamic, electric, fluidic, etc. It is billed to overcome the difficulties and involves the implementation of liquid metal contact electrostatically actuated to ensure the same switching performance, with prolonged life span, and robust switching speed.

Commentary by Dr. Valentin Fuster
2012;():437-444. doi:10.1115/ESDA2012-83005.

Modeling of dynamic properties of machine tools has a significant influence on improvement of its construction. This process is extremely important when a new construction of machine tool is under development. Experimental modal analysis provides information about frequency bandwidths with significant amplitudes of resonances, damping values and mode shapes. This information can be used in FEM model updating, stability prediction or finding weak elements of the machine tool structure as well.

In the paper the modal model of prototype of the micro machining center is presented. Polymax algorithm was used to estimate the poles (frequency, damping) of modal model and modal shapes. Modal model was built on the basis of the impact test results. Methodology of conducted experimental test is presented. Tested machine tool was made of different materials (steel, aluminum, stone and others) which causes difficulties during experimental investigations. In the construction different types of guideways were implemented — rolling, slide and pneumatic ones. Maximum rotational speed of the tool is about 100 000 rev/min, so the frequency range where poles of modal model are estimated is wide (high frequencies of excitation during machining). Weight of sensors used during testing is an important issue due to a low mass of the structure. Also the excitation of the structure is troublesome because of vulnerability of precise guideways and forces sensors used in machine tool construction.

Validation of the modal model is also presented in the paper and practical problems of modal testing are discussed.

Commentary by Dr. Valentin Fuster
2012;():445-450. doi:10.1115/ESDA2012-83011.

The article deals with active noise control and presents a silencer made of tunable acoustic resonators to reduce variable tonal noises. The silencer is composed of baffles with acoustic resonators made of two superposed and identically perforated plates associated with cavities. One of the plates is mobile and its displacement is controlled by an electromechanical system, allowing changing the internal shapes of the holes of the perforated layers. Consequently the impedance of the resonators and their resonance frequencies can be controlled. These tunable resonators can be used for noise control of variable tonal noises such as those generated by fans for example. The advantages of the proposed system are the simplicity of the actuation and the compactness of the system.

Commentary by Dr. Valentin Fuster

Advanced Energy Systems

2012;():451-458. doi:10.1115/ESDA2012-82033.

Palm oil methyl ester (POME) produced from crude palm oil have some excellent properties which makes it a feasible alternative to diesel fuel. However, its higher oxygen content makes it nitrogen oxide emission prone when burned in diesel engines. This problem can be resolved by emulsifying POME with distilled water in the presence of suitable surfactant. Two phase water in oil emulsion is prepared by using ultrasonic bath sonication. SPAN 80, a lipophilic surfactant is used for 1% by volume to prepare the emulsion. Water quantity in the emulsion is varied by 5% and 10% by volume and stability study is performed. It is found that emulsion with 5% water is more stable. Thereafter, POME emulsion samples are prepared with 5% water and tested in a variable compression ratio diesel engine. The performance and emission characteristics are investigated for a set of loads and compression ratios (CR). The experimental observations show that 5% water in POME produce 3.5% lower brake thermal efficiency and 11% higher brake specific fuel consumption as compared to baseline diesel. Furthermore, the exhaust gas temperature and other emissions like oxides of carbon, oxides of nitrogen and hydrocarbon for the emulsified POME are found to be lower than the baseline diesel.

Commentary by Dr. Valentin Fuster
2012;():459-464. doi:10.1115/ESDA2012-82193.

The paper describes a new kind of solar tracker intended to satisfy the precision requirements of high concentration photovoltaic systems. The tracker is designed according to a Delta type parallel kinematic schematics. The paper describes the kinematic schematics, the sensor chain and the control algorithm. Finally results obtained in functional tests are shown.

Commentary by Dr. Valentin Fuster
2012;():465-476. doi:10.1115/ESDA2012-82285.

The diagnosis of soft faults in vapor compression cooling systems is a crucial activity, since malfunctions may provoke heavy degradation in plant performance and increase the power consumption for space cooling. Among the various Faults Detection and Diagnosis techniques developed over the last two decades, thermoeconomic diagnosis has been playing only a marginal role due to the difficulties encountered when applying the conventional thermoeconomic approaches to vapor compression refrigeration plants. In this paper a critical analysis on capabilities and limits of thermoeconomic diagnosis of refrigeration systems is proposed. The reference plant assumed for this study is a 116 kWc air-condensed rooftop systems charged with R407C as refrigerant. A reliable 1-D steady-state simulator is used to calculate thermodynamic and performance data in “off-design” operating conditions; since the simulator has no specific capabilities to simulate faulty systems, literature-derived results were used to adjust the input settings for each specific fault simulated. Among the most common faults in rooftop air conditioners, four different malfunctions are examined: fouling at condenser, fouling at evaporator, refrigerant undercharge (either due to leakage or erroneous charging during service) and extra-superheating along the suction line; the faults are imposed both individually and simultaneously. The thermoeconomic diagnosis is performed basing on the “fuel impact” approach; the need to split physical exergy into its thermal and mechanical fractions and the presence of dissipative components suggested us to formulate some methodological premises, discussed in detail in the paper. The results testify that the adopted conventional approach is not very reliable; although some faults are properly identified, in fact, false fault signals and erroneous causalization eventually resulted, due to the presence of system-level faults (i.e. faults not strictly associated with any specific plant component, like refrigerant undercharge), the subjective assumptions made as concerns the cost allocation of residues and some controversial aspects concerning the productive structure.

Commentary by Dr. Valentin Fuster
2012;():477-487. doi:10.1115/ESDA2012-82302.

On the road transportation sector, considering its deep involvement with many social expectations, assumed such proportions to become one of the major source of air pollution, mainly in urban highly congested areas.

The use of reciprocating internal combustion engines (ICE) dominates the sector and the environmental dimension of the problem is under a strong attention of Governments. European Community, for instance, through sequences of regulations (EURO) reduced the emission allowed of primary pollutants; more recently, the Community added limits to climate-altering gases which directly refer to fuel consumption reduction. These limits today appear the new driver of the future engine and vehicle technological evolution. Similar efforts are under commitment by other developed countries (USA, Japan, etc,…) as well as also by the other Countries whose economic importance will dominate the markets in a very near future (BRICS Countries).

The need to fulfill these issues and to keep the traditional engine expectations (torque, speed, fun to drive, etc..) triggered, especially in recent decades, a virtuous cycle whose result will be a new engine and vehicle era. The evolution till had today has been driven by the EURO limits and it demonstrated surprisingly that emission reduction and engine performances can be matched without compromises in both sides. Today, adding severe limits on equivalent CO2, emissions, it appears very difficult to predict how future engines (and vehicles) will be improved; new technologies are entering to further improve the traditional thermal powertrain but the way to a massive and more convinced electrification seems to be definitely opened.

The two aspects will match in the sector of energy recovery which appears one of the most powerful tools for fuel consumption saving and CO2 reduction.

When the recovery is done on exhaust gases it has an additional interest, having a moderate cost per unit of CO2 saved. The potentiality of this recovery is huge: 30%–35% of the chemical energy provided by the fuel is lost with the flue gases. For different reasons engines for passengers cars or goods transportation (light and heavy unit engines) as well those used for electricity generation (gen-set) are interested to this recovery: the first sector for the CO2 reduction, the second for the increasing value of electrical energy on the market. This wide interest is increasing the probability to have in a near future a reliable technology, being different actors pushing in this direction.

In recent years the literature focused the attention to this recovery through a working fluid (organic type) on which the thermal energy is recovered by increasing its enthalpy. Thanks to a sequence of thermodynamic transformations (Rankine or Hirn cycle), mechanical work is produced. Both concept (Organic working fluid used and Rankine Cycle) are addressed as ORC technology. This overall technology has an evident complexity and doesn’t match with the need to keep reduced costs: it needs an energy recovery system at the gas side, an expander, a condenser and a pump. The space required by these components represents a limiting aspect. The variation of the flow rate and temperature of the gas (typical in ICE), as well as that at the condenser, represents additional critical aspect and call for suitable control strategies not yet exploited.

In this paper the Authors studied an energy recovery method integrated with the turbocharging system, which does not require a working fluid making the recovery directly on the gas leaving the cylinders. Considering that the enthalpy drop across the turbine is usually higher than that requested by the compressor to boost the intake air, the concept was to consider an additional turbine which operates in parallel to the existing one. Room for recovery is guaranteed if one considers that a correct matching between turbine and compressor is actually done bypassing part of the exhaust gas from the turbine (waste gate) or using a variable geometry turbine (VGT) which, in any case, represents an energy loss. An additional positive feature is that this recovery does not impact on engine performances and the main components which realizes the recovery (valves & turbine) are technologically proven.

In order to evaluate the potentiality of such recovery, the Authors developed a theoretical activity which represents the matching between turbocharger and engine. Thanks to an experimental characterization done on an IVECO F1C 16v JTD engine, an overall virtual platform was set up. The result produced a very satisfactory representation of the cited engine in terms of mechanical engine performances, relevant engine flow rates, pressures and temperatures. The ECU functions were represented too, such as boost pressure, EGR rates, rack control of VGT, etc…

Two new direct recovery configurations have been conceived and implemented in the engine virtual platform.

Commentary by Dr. Valentin Fuster
2012;():489-496. doi:10.1115/ESDA2012-82306.

In consequence of the increasing awareness on the future scarcity of fossil energy sources and the global warming impact of energy conversion processes, the European Union has been planning several actions to enhance the efficiency of energy use and reduce the environmental impact. The declared goals of EU actions are synthetized in the 20-20-20 formula, consisting of an expected 20% increase of energy efficiency, a 20% contribution to the total energy supply by renewable sources and a 20% abatement of pollutant emissions. Applications of cogeneration in process industry can significantly contribute to achieve these targets. In this paper a reciprocate engine-based Combined Heat and Power (CHP) plant is presented, serving a pasta factory located in Sicily and installed by an Energy Service COmpany (ESCO) within the context of a national implementation scheme of Energy Saving Certificates (or “white certificates”). The CHP plant, with a 650 kWe capacity, currently covers a relevant fraction of the electric and high-temperature heat loads during peak hours, while it is switched off during off-peak hours because of the much lower electricity price. Heat content of flue gases is recovered by two cascaded gas-diathermic oil and diathermic oil-water heat exchangers; the superheated water obtained is then supplied to the pasta dryers. The first part of the paper provides a detailed plant description and an energetic analysis of historical performance data collected along the last two years of operation. Both the critical analysis of the lay-out and the evaluation of energy saving indicators reveal the current scheme to represent a sub-optimal solution for the particular application. In the second part of the paper a modified solution is simulated, consisting of the same CHP unit equipped with additional heat exchangers for heat recovery from the cooling water jacket circuit. The marginal energetic and economic benefits compared to the current plant setup are calculated; the results are presented in analytic and graphical form, coherently with the provisions of Directive 2004/8/EC and accounting separately for the different cost and revenues (fuel for the CHP unit and the supplementary boilers, electricity purchased from or supplied to the grid, taxes, etc.). The improved solution, designed to increase the thermal efficiency of the CHP unit by allowing a full exploitation of heat cascades, resulted to provide evident benefits and to make the CHP unit to comply with all the current legislative provisions for the assessment of highly efficient CHP plants. Margins for further improvements are also briefly discussed.

Commentary by Dr. Valentin Fuster
2012;():497-506. doi:10.1115/ESDA2012-82323.

Heat transfer enhancement technology covers a very important role in designing efficient heating and cooling equipments. This goal can be achieved by means of different techniques. Convective heat transfer can be improved actively or passively, for example, by adopting special surfaces or by increasing the thermal conductivity of the working fluids. Thus, the use of suspended solid nanoparticles in the working fluids can be taken into account. In this paper a numerical investigation on laminar mixed convection with Al2O3/water based nanofluids in a triangular channel is presented. A uniform and constant heat flux on the channel surfaces is assumed and the single-phase model approach has been employed in order to describe the nanofluid behaviour. The analysis has been performed in the steady state regime for particle size in nanofluids equal to 30 nm. The CFD code Fluent has been employed in order to solve the three-dimensional numerical model and different Richardson number values and nanoparticle volume fractions have been considered. Results are presented for the fully developed regime flow. The increase of average convective heat transfer coefficients and Nusselt number values for increasing values of Richardson number and particle concentration is observed by analyzing the obtained results. However, also wall shear stress and required pumping power profiles increase as expected.

Commentary by Dr. Valentin Fuster
2012;():507-512. doi:10.1115/ESDA2012-82427.

This investigation is focused on the dynamic response of some commercially available piezoelectric materials which will be incorporated into textile materials for vibration control with a view of sports brassiere. Ceramic-based piezoelectric fiber composites (PFC), piezoelectric fiber composite bimorph (PFCB) and polymer-based polyvinylidene fluoride (PVDF) of various thicknesses have been chosen for this investigation. In a typical experiment, one end of each of the piezoelectric strips is fixed to the vibration table of an electrodynamic exciter while the other end is terminated at the cross-beam of a very stiff frame. The strip is placed under tension and made to undergo base excitation using pseudo-random signal from (0–2000) Hz using the electrodynamic shaker. The force output response is obtained using force transducers. The characterization of these piezoelectric materials will determine their behavior when embedded in the textile material for sports brassiere application.

Commentary by Dr. Valentin Fuster
2012;():513-523. doi:10.1115/ESDA2012-82442.

This paper presents the results of an analysis that proposes a combined path for the gases distribution in a PEMFC. The combination takes into account two of the most common flow fields currently in use: serpentine and interdigitated. The objective of the study is to determine the optimal conditions related with the way of distributing the hydrogen with the aim to increase the fuel cell performance. Therefore the paper centers in modifying the geometry of the anode while keeping a conventional serpentine geometry for the geometry. The analysis shows the current density distribution, the pressure drop, and the power generated by a PEM operating under the proposed gas flow field. In order to compare the results, a conventional commercial geometry was also analyzed and then both geometries were compared via polarization and power curves. The model adopted for the analysis takes into account the effects of the electrochemical reactions that occur in the fuel cell, in this case, the electrons and protons movement, the species consumption, the water vapour production in the catalysts and the water transport through the membrane (electro-osmotic effect). The results show that the proposed geometry leads to an excellent species distribution allowing a more uniform current distribution and a good power generation.

Commentary by Dr. Valentin Fuster
2012;():525-533. doi:10.1115/ESDA2012-82618.

Exploitation of the oceans thermal energy has been proposed several times in the past. Most research activity is focused on the temperature difference between the upper (warm) and bottom (cold) layers of water and that is what drives the power producing cycle. Consequently this kind of technology offers great possibilities in the tropical regions where the temperature difference is ranging from 10 °C to 25 °C. In enclosed seas like the Mediterranean, the available temperature differences are much smaller. Here however there exists a different potential, i.e. the temperature difference between the atmosphere and the sea water. This implies that there are two enormous reservoirs providing the heat source and the heat sink required for a heat engine. This study examines the merits of the temperature difference between the atmospheric air and the bottom of the sea, which is comparable to that of the tropical region sea waters and discusses the optimal plant configuration for the limit of the nearly ideal processes of such a plant.

Commentary by Dr. Valentin Fuster
2012;():535-542. doi:10.1115/ESDA2012-82718.

In this paper, a solar cooling installation is analyzed with the aim of optimizing its performances. The system consists of vacuum solar collectors, which supply hot water to a LiBr absorption chiller. A boiler can be used to supply an additional amount of hot water in the case of insufficient solar radiation. In addition, a vapor compression chiller operates as a backup system and integrates the solar driven system in the case of large cooling request. Such system gives multiple operating options, especially at partial load. A model of the system is presented and applied to the real plant. It is shown that if a multi-objective optimization is performed, considering minimum primary energy consumption from fossil fuel and maximum utilization of the absorption system, a Pareto front is obtained. This occurs because the two objective functions are competing. A control strategy based on the use of neural networks is presented. Input variables are the solar radiation, ambient temperature and the cooling request. In this work the control strategy is adjusted in order to reach the minimum fossil energy consumption, but the same approach can be applied with other objective functions.

Topics: Cooling , Solar energy
Commentary by Dr. Valentin Fuster
2012;():543-551. doi:10.1115/ESDA2012-82720.

The present paper describes the application of computational fluid-dynamics (CFD) for the analysis of the melting process in a single vertical shell-and-tube heat exchanger. The computations are based on a 2D axial-symmetric model that takes in account the phase change phenomenon by means of the enthalpy method. The numerical studies aimed at clarifying the importance of the different heat transfer mechanisms with a particular focus on natural convection demonstrating its fundamental importance on the phase change process by enhancing the heat transfer between HTF and solid PCM. the paper discusses the effect of two different common performance enhancement techniques: dispersion of high conductive nano-particles in the PCM and the introduction of radial fins. An extensive thermo-fluid dynamic study has been undertaken exploring the effect on the thermal performance enhancement of particle volume fraction and fins. The analysis shows that in comparison to the standard design, the performances of the LHTS unit in terms of charging time could be improved by up to 40 % for nano-particle enhancement. When fins are considered charging time can be reduced to one-third of its original value. Significant improvements are also achieved during the solidification process: discharge time is reduced of 33% with fins enhancement.

Commentary by Dr. Valentin Fuster
2012;():553-563. doi:10.1115/ESDA2012-82792.

The electrical efficiency and reliability of photovoltaic (PV) modules are severely limited by elevated cell operating temperature in high solar irradiation and ambient air temperature environments, such as in the Middle East. In this study the potential of water-cooling to improve the electrical performance of stationary south facing and sun-tracked flat-type PV modules is experimentally investigated for application at oil and gas facilities in the Persian Gulf. The cooling design is based on gravity-assisted water trickling over the module active surface. In parallel with measurements of PV module electrical characteristics, global solar irradiation, ambient air and cooling water temperatures are also recorded.

From the results obtained, the following initial guidelines are derived for the operation of PV modules in late winter to early spring conditions (G ≈ 485–900 W/m2, T∞ ≈ 26–40°C) in the United Arab Emirates (24.43°N, 54.45°E), which would correspond to summer at for example mid European latitudes: i) vertical single-axis sun tracking improves module peak electrical power output by 6% to 10% compared to operation in stationary, geographical south facing orientation, for both passively- or water-cooled modules; ii) for cooling water temperatures ranging from 26 to 33°C, water-cooling enhances the power output of stationary south facing and sun-tracked modules for a significant portion of the day, up to 19.8 W (21%) at solar noon; iii) the integration of water-cooling and sun-tracking increases power output by 22 W (26%) at for example 10:30 a.m. relative to a stationary, passively-cooled module. For the latitude and seasonal conditions considered, water-cooling a stationary PV module is 9 to 15% more effective than sun-tracking a passively-cooled module in terms of peak power output. Higher performance improvements could be obtained using either chilled or underground water at a temperature below ambient air temperature, particularly in Middle East summer conditions.

Commentary by Dr. Valentin Fuster
2012;():565-574. doi:10.1115/ESDA2012-82828.

The Stirling engine, as an external combustion engine, can be powered using a variety of heat sources including the continuous combustion process thus achieving significantly reduced emissions. Energy systems powered by a Stirling engines meet the needs of various applications not only in the domestic and industrial sections but in military and space gadgets as well. Stirling engines can also be used as cryocoolers in medical applications where they are called to achieve very low temperatures. Each energy system using Stirling Engine optimizes its performance in specific operating conditions. The system capacity depends on the geometric and structural characteristics, the design of the unit, the environment in which the engine is allowed to it works as well as the size of the load. In order to study the function and the efficiency of Stirling energy systems a CHP SOLO 161V -ALPHA TYPE STIRLING ENGINE was installed in the Laboratory of Applied Thermodynamics of NTUA. A thermodynamic analysis has been conducted using appropriate computing codes. The effect of each independent variable on the system performance was investigated. The study was divided into distinct levels of detail, bringing out each variable. Initially, the performance of the heat engine was examined assuming an ideal regenerator. Then, the effectiveness of the regenerator was evaluated as well as its effect on the engine performance, while the effect of the pressure drop and the energy dissipation on the engine efficiency was also investigated. Measurements were conducted using different operational conditions concerning the heating load of the engine. The effect of the geometrical characteristics of the regenerator on power output and engine performance was examined based on the results of a simulation analysis. Moreover, the power output and the efficiency of the machine in relation to the thermal load of the unit and the average pressure of the working medium were investigated. Major performance input characters affecting geometrical and operational parameters of the unit were identified leading to unit optimization with specific combinations leading to increased system performance. Simulation results were validated by comparison to corresponding values obtained by relative experiments conducted with the SOLO unit. Finally, a sensitivity analysis was performed in order to investigate the effect of the operating conditions on the performance of an alpha type Stirling Engine.

Commentary by Dr. Valentin Fuster
2012;():575-581. doi:10.1115/ESDA2012-82846.

The work developed in this paper is realized within the ecoDriver EU FP7 project that is shortly presented in the first part of the paper. Among the several main objectives underlined by this project, one consists in developing a vehicle and energy consumption model to be validated and then used to help the driver to better drive in terms of consumption and safety, advised by a HMI (Human-Machine Interface) module. Several experimental results are shown to illustrate the obtained energy saving with such an EDAS and the legal speed respect.

Commentary by Dr. Valentin Fuster
2012;():583-588. doi:10.1115/ESDA2012-82851.

This paper proposes a structure of energy harvester that is used to scavenge environment energy to power wireless sensor nodes. The ambient energy usually is from sunlight, wind, vibration, and so on. As the size of a sensor node is limited, the energy converted is normally small and has a prodigious random fluctuation. In order to improve the conversion efficiency of energy harvester, the paper proposes a power conversion circuit to collect rapidly paroxysmal energy generated by external environment. The circuit, as a power conditioner, bridges between energy transducers and the load of a wireless sensor node, and the power output of transducers are either AC or DC. The power conditioner implements AC-DC conversion, voltage adjusting and energy storage. A design model is developed to describe the dynamic behavior of the power conditioner under the different excitation from ambient energy sources, and energy conversion efficiency can be evaluated with the model. The proposed system architecture can be applied in the design of solar, wind or stochastic vibration energy harvesters.

Commentary by Dr. Valentin Fuster
2012;():589-597. doi:10.1115/ESDA2012-82917.

It is well known that the main overpotentials during the operation of a fuel cell are activation, ohmic and concentration overpotentials. In order to operate more efficiently these devices that convert the chemical energy of the fuel into electrical energy, it is necessary to reduce as much as possible the overpotentials aforementioned. Some of the components of a fuel cell are the so called current collectors. These components affect the fuel cell performance mainly by means of two overpotentials, the ohmic and concentration overpotentials. The second one, is however, affected indirectly by the current collector design, since it may only help to distribute more uniformly the gases over the electrodes. The activation overpotential is basically not affected because it is mainly related with the electrode properties such as the exchange current density. In this work, the effect of the current collectors design on the performance of planar Solid Oxide Fuel Cells (SOFCs) is assessed by means of fully three-dimensional numerical simulations by comparing the V-I and power density curves of a planar cell. The goal of this study is not to find the optimal design of the current collectors but a way in which the overpotentials relate with their design in order to propose some helpful recommendations during the design process of these fuel cell components. These recommendations may lead to design an improved or optimal flow distributor.

Commentary by Dr. Valentin Fuster
2012;():599-609. doi:10.1115/ESDA2012-82986.

Waste heat recovery (WHR) has the potential to significantly improve the efficiency of process industries such as in the oil and gas sector, and reduce their environmental impact. The design of an effective WHR strategy requires a comprehensive plant energy audit, but examples of such information are lacking in the published literature. In this paper a detailed energy audit is presented for a major natural gas (NG) processing facility in the Middle East, to identify sources of waste heat and evaluate their potential for on-site recovery. Waste heat sources are quantified and evaluated in terms of grade (i.e., temperature), rate, accessibility (i.e., proximity to potential on-site WHR applications), and impact of potential WHR on the performance and safety of existing facilities. Based on the audit undertaken, conceptual WHR strategies are proposed, focusing on utilities enhancement, i.e., process cooling/heating, electrical/mechanical power generation, and steam production. In addition, to permit the techno-economic feasibility evaluation of the proposed WHR strategies in modeling work undertaken in parallel with this study, the operating parameters of waste heat producing equipment are compiled, along with the cooling/heating loads and electric power/fuel consumption of WHR-enhanced processes.

A total of 689 MW of waste heat is identified in the plant, which consists of 526 MW gas turbine (GT) and 56 MW gas generator exhaust gases, 10 MW flared gases, 5 MW excess process steam, 88 MW process gas air-cooler heat dissipation, 2 MW furnace exhaust gases, and 1 MW steam turbine outlet steam. Waste energy in the form of excess propane cooling capacity is also identified. The total amount of waste heat meeting the rate, grade, accessibility and minimal performance-and-safety-impact criteria defined for potential WHR in this study is of approximately 547 MW, most of which is produced by GTs. Only 174 MW of GT waste heat is presently re-utilized, in addition to excess propane cooling capacity. Novel absorption refrigeration-based WHR strategies are proposed to recover the available GT waste heat. These strategies were found to be thermodynamically and economically feasible in an accompanying study, and to lead to substantial energy and cost savings for the plant.

Commentary by Dr. Valentin Fuster

Thermal Engineering

2012;():611-618. doi:10.1115/ESDA2012-82134.

Injection molding is the most used process for thermoplastic part manufacturing. This process is commonly divided into four steps: injection, packing, cooling and ejection. During the packing step, an amount of material gets into the mold cavity to compensate for shrinkage of the polymer mainly due to the crystallization. Once the gate is frozen, polymer is subjected to isochoric cooling while the pressure of the polymer is higher than atmospheric pressure. Improving the quality of the injected part requires prediction of the shrinkage, warpage and residual stress and pressure impacts deeply on the morphology and consequently on the shape of the final part. The pressure decrease during the isochoric phase also determines the ejection time. However, description of the behavior of the polymer during packing and isochoric steps needs an accurate model that considers coupling between heat transfer and crystallization and also a good knowledge of the behavior (specific volume and crystallization kinetics) of the polymer under high pressure. Some studies have already underlined the influence of shear rate on the kinetics of crystallization. Here, based on a pressure analysis and an experimental-numerical comparison, we confirm crystallization is strongly coupled to flow history.

Topics: Pressure , Cavities
Commentary by Dr. Valentin Fuster
2012;():619-625. doi:10.1115/ESDA2012-82203.

Injection is one of the most used processes to manufacture thermoplastic parts. The design of the cooling channels in this process is of great importance during the mould design. Indeed, an inappropriate cooling will lead to defects in the part and a low production rate. In this paper, a new approach for the design of the cooling channels is assessed. Based on morphological concepts, the idea of regulation by cooling surface is introduced. The thermal behaviour of the mould can be restricted on the spatial domain delimited by the cooling surface on which a spatial temperature distribution is imposed. The first step of the methodology leads to the optimal determination of the fluid temperature distribution along the cooling surface in order to minimize a cost function composed of two terms linked to the quality of the part and the productivity of the process. The conjugate gradient algorithm coupled with a Lagrangian technique is implemented for the determination of fluid temperature parameters. However, the obtained solution is not workable in practice. The second step consists then in building real channels from this optimal distribution. The shape, location and fluid temperature level of these channels are determined a posteriori from the thermal analysis of the temperature field in the mould domain located between the plastic part and the cooling surface. Channels are builded by using the contours of isotherms in the thermal steady-state area of the mould. It becomes then possible to design the cooling channels with no a priori on the numbers, the location of these channels and on the temperature of the coolant fluid. The methodology is first illustrated with a 2D part. Results are compared with literature.

Commentary by Dr. Valentin Fuster
2012;():627-638. doi:10.1115/ESDA2012-82336.

Liquid desiccant air conditioning systems have recently been attracting attention due to their capability of handling the latent load without super-cooling and then reheating the air, as happens in a conventional compression-type air conditioning system. This paper presents the results from a study of the performance of an internally cooled liquid desiccant dehumidifier. A plate heat exchanger is proposed as the internally cooled element of the dehumidifier and water as the cooling fluid. The desiccant solution is sprayed into the internally cooled dehumidifier from the top and flows down by gravity. At the same time, fresh humid air is blown from the bottom or top, counter-flowing or co-flowing with the desiccant solution. The desiccant is in direct contact with the air, allowing for heat and mass transfer. The cooling water, flowing inside the plates of the dehumidifier, carries out the heat of the crossed air and solution. A heat and mass transfer theoretical model has been developed, based on the Runge-Kutta fixed step method, to predict the performance of the device under various operating conditions. Experimental data from previous literature have been used to validate the model. Excellent agreement has been found between experimental tests and the theoretical model, with the deviation not exceeding ±4.1% for outlet air temperature and ±4.0% for outlet humidity ratio. Following the validation of the mathematical model, the dominating effects on the absorption process have been discussed in detail. Namely, effects of flow configuration, air inlet temperature, humidity and flow rate, as well as desiccant inlet temperature, concentration and flow rate have been investigated against the dehumidification rate and the cooling efficiency. The two most commonly used liquid desiccant solutions, namely LiCl and LiBr have been also evaluated against each other. The results suggested that high dehumidification mass rate can be achieved under counter flow between air and solution, low air mass flow rates, low cooling water temperature, low desiccant temperature and LiCl as the desiccant solution.

Topics: Dehumidifiers
Commentary by Dr. Valentin Fuster
2012;():639-647. doi:10.1115/ESDA2012-82361.

In roads building, classical asphalt mix manufacturing commonly requires the heating (at 160°C) and the complete drying of aggregates. The induced energy cost has opened the way to develop alternatives processes and materials with low energy/carbon materials such as Warm Mix Asphalt (WMA). In warm mixes processes, aggregates manufacturing temperatures are different and lower than the Hot Mix ones. However, manufacturing temperature reduction can locally lead to poor bonding between bitumen and aggregate during the mixing step, due to the bitumen viscosity increasing, although bonding quality measurement remained a challenge. The aim of our study was to presents two thermal inverse methods for bonding quality assessment. These methods are based on Thermal Contact Resistance (TCR) assessment between bitumen and aggregate, during asphalt mix manufacturing. The experimental test principle consisted of heating both bitumen and cylindrical aggregate to their manufacturing temperatures (over 100°C) and to put them into contact thanks to a special experimental device. According to initial samples temperatures, heat transfer occurs from the bitumen to the aggregate. Two variants of the sequential Beck’s method were used to solve the inverse heat conduction problem. The first one consisted of determining the TCR from heat flux and temperatures and the second one consisted of identifying directly the TCR. The TCR values were interpreted as bonding quality criteria.

Results showed low sensitivity to temperature measurement noise in the second variant of the inverse method. Moreover our study showed that bonding quality depends on bitumen and aggregate temperatures. The higher the component’s temperatures, the lower the TCR values and better is the bonding quality.

Commentary by Dr. Valentin Fuster
2012;():649-657. doi:10.1115/ESDA2012-82421.

The use of dimensional analysis and dimensionless parameters is very common in the field of heat transfer; nevertheless the concept of non-dimensional finite element formulation has been applied to a limited type of thermo-fluid problems. The non-dimensional finite element method should provide the dimensionless solution for a given problem. The aim of present work is to develop a non-dimensional thermal finite element for getting dimensionless solution of the problems that do not have a closed form solution. An example is a fin (or extended surface) design. Fin efficiency is a performance characteristic that can be used as design criterion; thus closed form dimensionless solutions for fin efficiency are available in the literature. The results are for different geometry, single material fins. In case, if the fin problem has some geometric and/or material complexities then closed form solutions are not available and finite element approach can be used. However, the obtained finite element solution would not be in dimensionless form. For example, no closed form solutions are available for variable thickness composite fins (i.e. a fin having a base material with a coating over its surface), and the literature shows that finite element solution has been used to study thermal performance of the variable thickness composite fins. Therefore, non-dimensional finite element approach can be applied to directly obtain the dimensionless solution for the problem. The current work consists of presenting a non-dimensional finite element formulation for thermal problems. The element formulation is first validated by solving a test case study that has known closed form solution. The objective is to demonstrate the usefulness of the non-dimensional finite element approach by obtaining dimensionless finite element solutions for some applied problems that do not have a closed form solution.

Commentary by Dr. Valentin Fuster
2012;():659-667. doi:10.1115/ESDA2012-82428.

In this study flow field inside a square channel with a two-stage electrohydrodynamic (EHD) gas pump has been critically examined by experimental measurement and numerical simulation. The EHD gas pump with 28 emitting electrodes in each stage is tested for a wide range of operating voltages starting from the corona threshold voltage up to 28 kV for further improvement in its performance over that of a single-stage. It has been shown that the two-stage EHD gas pump can produce and sustain gas flows with a maximum velocity of 5 m/s. Its maximum performance of 34 L/s/W is better than that of conventional cooling fans used in personal computers. The implication for its application in thermal management and heat transfer enhancement has also been discussed.

Commentary by Dr. Valentin Fuster
2012;():669-675. doi:10.1115/ESDA2012-82479.

Sintered diamonds are used in grinding because they offer better mechanical properties than conventional materials (mineral or silicon carbide abrasives) and yield high grinding speed and long life. In addition, because of their thermal performance, they contribute to cooling the workpiece, avoiding excessive temperatures. Thus in order to choose the best material for the worktool, one often must know the thermal conductivity of sintered diamond. In this work, the thermal conductivity of sintered diamond is evaluated as a function of the volume fraction of diamond in the composite and for two types of metallic binders: hard and soft. The measurement technique is based on the flash method that associates heating and measurement devices without sample contact and on parameter estimation using a three-layer thermal model. With a hard metallic binder, the thermal conductivity of sintered diamond was found to increase up to 64% for diamond volume fraction increasing from 0 to 25%. The increase is much smaller for the soft binder: 35% for diamond volume reaching 25%. In addition, experimental data were found far below the value predicted by conventional analytical models for effective thermal conductivity. A possible explanation is that the thermal conductivity of such composites is affected by poor heat transfer at the diamond/binder interface, the thermal contact resistance between matrix and diamond particles being estimated at between 0.75 and 1.25 10−6 m2K.W−1.

Commentary by Dr. Valentin Fuster
2012;():677-681. doi:10.1115/ESDA2012-82485.

An experimental study was performed to investigate the heat transfer characteristics of the pulsation flow through a rectangular air duct with aspect ratio of 10. The test section was designed to have a constant heat flux. For pulsating flows, the surface temperatures, the temperature of air at the inlet and at the outlet of the test section, maximum velocity and minimum velocity of air in the test section and the frequencies of pulsation flow were measured and averaged local Nusselt numbers and averaged Nusselt numbers were calculated. The effect of pulsation amplitudes and pulsation frequencies on heat transfer were analyzed.

Commentary by Dr. Valentin Fuster
2012;():683-692. doi:10.1115/ESDA2012-82590.

The two-stage stretch-blow moulding process has been established for the large scale production of high quality PET containers with excellent mechanical and optical properties. Thermoforming is the process of choice for manufacturing thin-gauge or large-area parts for packaging or technical applications. Both processes allow lightweight thermoplastic parts to be produced rapidly and economically.

In both processes thermoplastic semi-finished products are formed by pressurised air under the influence of heat. To enable forming of the thermoplastic materials, the semi-finished products need to be transferred into a thermoelastic state. IR-heating is widely used due to short heating times.

From a cost perspective, about 7 % of the total production costs of a stretch-blow moulded bottle are spent for energy in order to heat and form the preform to the later bottle. Depending on machine, semi-finished product type and cycle time, energy costs in thermoforming account for around 1–5 % of the total production costs. Modern roll-fed automatic thermoforming machines use about 22 % of the energy consumption for the heating step and around 70 % for the production of pressurised air. Due to this significant share and due to increasing energy costs during recent years, the packaging industry is interested in increasing the energy efficiency of these processes.

The most important quality criterion for both processes is a uniform wall thickness distribution. The production of high-quality parts requires optimised temperature profiles of the semi-finished product depending on the particular product geometry. Simulation is an approved tool for the prediction of the influence of the heater setting on the temperature profile.

Over the last decade IKV has developed an integrative three-dimensional process simulation which models the complete path of a preform through a stretch-blow moulding machine. An essential first step is the heating simulation where the temperature profile of the preform is computed. Based on this data the temperature-dependent material behaviour of PET can be considered during the inflation simulation.

This work shows the influence of a thoughtful temperature profile on the wall thickness distribution in stretch-blow moulding. The focus is on modelling the reheat phase of the stretch-blow moulding process in FEA. Beyond that, a purposeful heating offers the possibility to cut down energy waste.

Topics: Molding , Modeling , Heating
Commentary by Dr. Valentin Fuster
2012;():693-698. doi:10.1115/ESDA2012-82599.

This work presents a numerical study of the thermal and hydrodynamic behavior of a pin-fin heat sink where deflectors are placed along the flow of the coolant air; the effect of the arrangement of the fins and deflectors in the global performance of the heat sink is investigated. The fin geometry analyzed is rectangular, and the arrangement of the fins is inline. The heat sink is placed in a channel in which air flows, and a constant heat flux is applied at the bottom wall of the heat sink with values equivalent to the heat fluxes generated by current electronic devices. Deflectors are placed in the top of the channel in order to drive the air flow into the front and end of the heat sink. The results for the Nusselt number and for the pressure drop along the heat sink are reported. The best dimension of deflectors and pitch for the arrangement based on the thermal and hydraulic performance is attained.

Topics: Heat sinks
Commentary by Dr. Valentin Fuster
2012;():699-708. doi:10.1115/ESDA2012-82672.

The paper presents an analysis of a recuperative gas turbine system used for micro-cogeneration based on energetic and exergetic principles. The system is composed of two compressors (one for the fuel, the other for air), a combustion chamber, a gas turbine, a recuperator used to preheat the air before entering the combustion chamber and a heat exchanger for heating water. The analysis compares three different configurations obtained by placing the recuperator upstream of, downstream of, or in parallel with the water heater. It is subject to the following assumptions: the fuel is injected steadily and ideally (without irreversibility), the air is a perfect gas, the heat exchangers are adiabatically isolated from the surroundings and the compressors and the turbine are adiabatic. A detailed analysis of the thermal and mechanical irreversibilities of the cycle is also presented. The optimization goal is to minimize the entropy generation or to maximize the useful exergy output of the system. With this approach the best configuration for a specified operating regime of micro-cogeneration can be determined.

Commentary by Dr. Valentin Fuster
2012;():709-720. doi:10.1115/ESDA2012-82713.

In the present work, a comparison between numerical and experimental gas side heat transfer and pressure drop for a tube bundle with solid and segmented circular finned tubes in a staggered arrangement is investigated. For the numerical simulations a three dimensional model of the finned tube are applied. Renormalization group theory (RNG) based kε turbulence model was used to calculate the turbulent flow. Experiments have been carried out to validate the numerical predictions. The numerical results for the Nu-number and pressure drop coefficient show a good agreement with the data from measurement. A comparison between solid and segmented finned tubes from the global calculation of the Nu-numbers within the analyzed Re-range shows an enhancement by applying segmented finned tubes rather than finned tubes with solid fins.

Commentary by Dr. Valentin Fuster
2012;():721-727. doi:10.1115/ESDA2012-82725.

Effects of temperature: initial heating conditions or self heating during the process, are very important during the injection stretch blow moulding (ISBM) process of PET bottles. The mechanical characteristics of the final products, which are mainly controlled by the final thickness and the orientation of the molecular chains, depend strongly on the process temperature. Modelling the heat transfer during the ISBM process is therefore necessary. In the first part of this paper, an experimental study is presented in order to measure the initial temperature distribution and to identify the thermal properties of the PET. An infrared camera has been used to determine the surface temperature distribution of the PET sheets which are heated by infrared (IR) lamps. The Monte Carlo method is used to identify the parameters best fit from the temperature evolution. In the second part, a thermo-viscohyperelastic model is used to predict the PET behaviour, taking into account the strain rate and temperature dependence. A finite element approach implemented in matlab is used to achieve the numerical simulation.

Topics: Heat , Molding , Modeling , Heating
Commentary by Dr. Valentin Fuster
2012;():729-739. doi:10.1115/ESDA2012-82740.

Photovoltaic (PV) technology provides a direct method to convert solar energy into electricity. In recent years, the use of PV systems has increased greatly with many applications of PV devices in systems as small as battery chargers to large scale electricity generation systems and satellite power systems. An important factor that influences the reliability of photovoltaic modules is their ability to withstand high thermal stresses which develop in PV modules due to the different coefficients of thermal expansion of the different module materials. PV modules also experience thermal cycles which can lead to failure of the module. In the present work, three dimensional numerical thermal and structural models of a PV module were developed and sequentially coupled together to calculate the temperature distribution in the PV module and the thermal stresses developing in it. The model is also capable of simulating PV module cooling. Using the model, a study was conducted to evaluate the thermal and structural performance of the module with and without cooling and the variation in thermal stress magnitudes with changing environmental conditions (solar radiation and ambient temperature) and operating conditions (heat exchanger inlet temperature and velocity).

Commentary by Dr. Valentin Fuster
2012;():741-747. doi:10.1115/ESDA2012-82969.

In the hot stamping process, the temperature evolution drives the metallurgy, as well as the metallurgical transformation influences the temperature evolution through the exothermic nature of the austenite to martensite transformation. This heat release has already been highlighted by previous experimental work. This heat release leads to a source term in the heat equation in the blank. This source term must be quantified in order to accurately predict blank temperature evolution. Moreover, the end of the heat release corresponds to the end of the metallurgical transformation. It allows the determination of the minimum quenching time, relevant information for industry to minimize the process time.

This paper presents a method to quantify the heat released by the metallurgical transformation during the hot stamping of Usibor 1500P® ArcelorMittal steel, solving inverse conduction problems. It allows the determination of this heat release as a function of temperature or time. Then, integrating it, the latent heat of the transformation can be estimated. This can be done for different contact pressures between tool and blank. Finally, it can be linked to the martensite proportion to estimate it as a function of time or temperature and determine the Koistinen-Marburger model parameters. These results should improve the accuracy of numerical simulations of the hot stamping process.

Commentary by Dr. Valentin Fuster

Human Factors and Cognitive Engineering

2012;():749-753. doi:10.1115/ESDA2012-82265.

This paper illustrates that a method for identification of pick up noise and an analysis the cause of pick up noise by substituting components of a laser printer. The operating sound radiated from a laser printer includes the tonal noise components caused by the rotating mechanical components such as gear, shaft, motor, fan, etc. A sound operated by laser printers has become important competitiveness in printer industries as the demand of laser printers increases. Especially, a noise between a friction pad and a paper in the process of printing has become an essential issue in an aspect of quality evaluation. However the existing criteria for determining the above noise have solely relied on human’s subjective judgments; which highlights the requirement to objectify these criteria.

In this paper, the standard of existing pick up noise is established by finding the tonality, which is a psychoacoustic parameter, of noticeable limit sound level. Based on the findings of the method, the study has found factors which cause pick-up noise and suggests the substitution of following components of printers such as: spring constants, spring force, and the quality of friction pads.

As a result, it is confirmed that the proposed pick up noise index has usefulness to classify whether existence of pick up noise with an objective evaluation and not to occur the noise based on design optimized combination of laser printer components.

Topics: Lasers , Noise (Sound)
Commentary by Dr. Valentin Fuster
2012;():755-761. doi:10.1115/ESDA2012-82481.

This paper presents a framework allowing emblematic gestures detection, segmentation and their recognition for human-robots interaction purposes. This framework is based on a new coding of arms’ kinematics reflecting both the muscular activity of the performer and the appearance of arm seen by the recipient when a gesture is performed. Following that, gestures can be seen as sequences of torques activations leading arm’s parts to express a comprehensive meaning. In addition, these sequences have very stable topologies and shapes regardless to performers. This facilitates the generalization of the recognition process with a minimalistic learning effort for online usages. Promising results were obtained for a set of 5 classes of gestures performed by 19 different persons.

Commentary by Dr. Valentin Fuster
2012;():763-772. doi:10.1115/ESDA2012-82486.

The measurement and understanding of user emotions elicited by product appearance are critical elements of the product development process and have been interesting design challenges for many years. This paper proposes an original emotion measurement method, called Auditory Parameter Method. It is a non-verbal technique, which uses sounds and association tests for evaluating a set of products (given by their pictures). It provides an assessment of these products according to a series of emotional dimensions. We present a methodological framework to build the links between user’s emotional responses and geometrical features of product, by using a glasses frame 3D model as application case. Analysis of Variance techniques are employed to examine how various shape factors influence users’ emotional responses to 3D model. To demonstrate the effectiveness of our protocol, we compare the proposed method with the conventional Semantic Differential using Principal Component Analysis and Generalized Procrustes Analysis. The new protocol demonstrates interesting qualities to collect the intuitive emotions of user.

Topics: Design
Commentary by Dr. Valentin Fuster
2012;():773-780. doi:10.1115/ESDA2012-82511.

This paper investigates the possibility of using objective indicators to predict the subjective evaluation of a driver in a simulator. Situations of loss of adherence (LOA) were controlled and modulated in intensity and duration on a static and on a dynamic simulator (with and without a motion base). Multiple regression analyses were performed using the subjective evaluation of participants as the dependent variable, and the objective physical variables of the interaction driver/vehicle as the independent variables. The results assigned the most contributive variables to the accuracy of the model’s prediction for each subjective item, lateral acceleration and yaw rate for “control feeling” for instance. They also underlined the consistency of our approach and the influence of motion rendering on the perception of LOA intensity. A similar method could be used to evaluate the perception of various configurations of electronic stability control (ESC) systems.

Commentary by Dr. Valentin Fuster
2012;():781-790. doi:10.1115/ESDA2012-82641.

Synthetic humans are computer-generated characters that are designed to behave like humans for the purpose of training or entertainment. The purpose of this study was to evaluate the perceptions of subjects interacting with synthetic humans to determine their responses to nonverbal behaviors, realism, and character personality. This study was part of a research program to develop a virtual game to train awareness of nonverbal communication for cross-cultural competency (3C).

Three synthetic humans were created with different levels of realism with respect to their facial movements and skin textures. Low realism characters were defined as models purchased from the company Evolver, with additional facial action units (FAU) added to the character’s face. High realism characters were created based on a model of a real person’s head using 3D imaging cameras and a digital video camera. The same FAUs available in the Evolver characters were also coded into the high realism character as well as more realistic skin texture. During a virtual scenario the subject was asked to interview three characters in the U.S. Army. The subject interviewed each character one-on-one. The three computer characters included two white males, and one black female.

The results of this study showed that it is possible to create synthetic humans that include nonverbal behaviors and personalities that are perceived by subjects, and that the subject’s own personal lens affected how they perceive the character. For example, the character Brent was rated similarly by most subjects with respect to personality traits as defined by the Big Five Factor Model. However, half the subjects indicated they liked him (friendly and confident), while about half the subjects did not like him (too confident as to be arrogant).

Commentary by Dr. Valentin Fuster
2012;():791-802. doi:10.1115/ESDA2012-82648.

In joint human-automation systems, operators must often supervise the automation and adapt their reliance upon it based on judgments of its context-specific reliability. For this to occur, operators should trust the automation appropriately. In the design of a water monitoring decision aid’s display, Ecological Interface Design was used to satisfy design guidelines for supporting appropriate trust. Display evaluation focused on a graphic form that made the aid’s use of the Dempster-Shafer theory directly perceptible. The display was evaluated using a signal detection theory-based approach that measured reliance on automation. Results indicated that the ecological display yielded less appropriate reliance and poorer performance than a conventional display for a highly reliable decision aid. However, the experimental task prevented participants from adapting to the aid’s context-specific reliabilities, reducing the degree to which reliance behaviour could be studied. A subsequent study is proposed to further study the effects of ecological displays on automation reliance.

Topics: Design , Water
Commentary by Dr. Valentin Fuster
2012;():803-811. doi:10.1115/ESDA2012-82675.

One of the most challenging factors in the development of autonomous vehicles and advanced driver assistance systems is the imitation of an expert driver system which is the observer and interpreter of the technical system in the related driving scenario. To achieve an expert human-like situational understanding and decision making may be an important feature to fulfill the necessary active safety requirements. In this paper, an exploratory study on a multimodal adaptive driver assistance system is presented. The main goal is to determine the human driver’s attention and authority level in a cognitive model and to trigger the timely warnings according to his/her driving intents and driving skills with respect to the possible driving situation and hazard scenarios. In the previous studies, a fairly restrictive vision-based driver assistance system has been deployed to detect lane departure, blind-spot and to monitor following distance, headway time. This vision-based driver assistance system considers the driver’s driving performance metric sampled during the longitudinal and lateral vehicle control tasks as well as the processed information about the surrounding traffic environment consisting of the interactions with the other vehicles and the road situations. The presented active safety system models the driving task in a cognitive architecture and assesses the cognition of the human driver by modeling the situation awareness of the driver by using fuzzy sets. Each fuzzy set simply represents the expert driver’s perception in both of the longitudinal and lateral traffic. The presented system evaluates the driver’s driving skills and attention level by comparing the expert and human driver’s reactions suited in a finite set of decision and maneuvering task. In case of hazard analysis, the system triggers timely warnings pointing the driver’s attention at the lateral or longitudinal maneuvering tasks depending on the interpreted situation. Introductory experiments are performed with a limited number of participants, the test driving data including the driver’s perception and reaction to the surrounding vehicles and traffic situations are collected by the use of a vehicle simulator. And the presented multimodal adaptive driver assistance system is evaluated by the simulator. The preliminary results seem to be promising.

Topics: Vehicles
Commentary by Dr. Valentin Fuster
2012;():813-820. doi:10.1115/ESDA2012-82696.

This paper describes a tentative model to analyze work in joint human-automation systems. The tentative model is used to represent known human-automation related problems in a unified way. The out-of-the-loop problem is used as an example in the paper.

The present paper has three main objectives; (I) present a tentative model that can characterize work in joint human-automation systems, (II) show how the tentative model can be used to describe examples of human-automation related problems (III) discuss how the tentative model can be used as a viable tool to understand human-automation interaction.

The paper reports an evaluation made by using empirical data from an interview study on turbine automation operation in the nuclear power domain where human-automation related problems were identified.

The evaluations show that the tentative model provide useful explanations to how specific automation related problems emerge. These explanations could potentially be generalized into human-automation interface design guidance. Further, it is discussed how the tentative model can be developed into a viable tool for industrial use where limited resources are available for extensive analysis of human-automation interaction.

Commentary by Dr. Valentin Fuster
2012;():821-826. doi:10.1115/ESDA2012-82754.

Robot-assisted laparoscopic surgery is gaining popularity because it has been shown to improve accuracy, reduce errors, and assists surgeons in performing more difficult procedures. However, positioning the ports and posing the robot arms to be able to perform the intervention while avoiding tool or arm collisions can be a lengthy and difficult process. The aim of this project was to design a decision aid for patient-specific, optimal port placement in pre-operative planning. This paper presents the analysis and design methods, including the building of separate patient and robot models. Based on a requirements analysis, a symbolic model of the robot was created based on the da Vinci Si Surgical System using the modified Denavit-Hartenberg (DH) parameters to define its work volume. Data from anthropometric tables and patients undergoing laparoscopic procedures were collected to create a library of realistic patient models. These two models, combined in a 3D interactive virtual environment, allow selection of suitable port locations, and a pose and position plan for the robotic arms with unrestricted access to the target area while avoiding collisions between instruments and other objects in the operating room. A simple and elegant protocol was then designed to collect actual patient data for validation of the models. Once validated, this model can be used for any robotic procedure within the abdomen.

Topics: Robots , Modeling , Surgery
Commentary by Dr. Valentin Fuster
2012;():827-836. doi:10.1115/ESDA2012-82771.

This work addresses the design of a preference based system that suggests relevant products to customers. It aims at helping them with their purchase decision (on electronic commerce websites). A use case that consists in making spontaneous recommendations to the customers, on the basis of their previous ratings is described. The product considered to illustrate the approach is a comic. This paper is focused on two recommender approaches. The first approach, “the traditional” approach, is based on the collaborative filtering while the second approach, is based on a new proposed algorithm. Collaborative filtering is a technique to making recommendations by matching people with the same preferences (preferential similarity). The second approach which is proposed is a combination of the traditional collaborative filtering and the perceptual similarities approach between customers (perceptual similarity). Perceptive data include emotional, sensory and semantic ratings of the products. The purpose of this paper is to evaluate the performance of the proposed approach and to compare it with the traditional approach. A test procedure is thus implemented. It consists in simulating customers’ behavior according to a set of products, and to compute a performance criterion of the recommender system, measuring the relevance of the proposed products. The performance of the proposed algorithm is compared with that of the traditional one. The results show that the consideration of perceptual assessments of products by customers generally helps in the relevance of the propositions of the system.

Topics: Design
Commentary by Dr. Valentin Fuster
2012;():837-846. doi:10.1115/ESDA2012-82782.

Over the last 50 years, master-slave teleoperation has become a widespread and successful field of research. This discipline explores how to perform tasks using a robot on an environment with haptic feedback about robot-environment interaction being provided to the human operator. Most of the master and slave manipulators used in teleoperation are electrically actuated. However, in some particular applications such as inside an MRI for image-guided surgery, ferromagnetic materials including electrical wiring is prohibited. Thus, non-ferromagnetic actuators like pneumatic or hydraulic actuators are a solution to this problem. This specific application also requires teleoperation in the sense of “tele-actuation” because of the lack of space inside the MRI chamber to put the robot’s actuators and the presence of electrical components in pneumatic servovalves.

In this paper, we study the case of a teleoperation system composed of two identical pneumatic cylinders (as the master and the slave) equipped with servovalves, making a symmetric teleoperation system. This serves as a one-degree-of-freedom system to outline the design and analysis in terms of teleoperation transparency and stability. Simulation and experimental results check the validity of the theory without and with classical transmission delays.

Commentary by Dr. Valentin Fuster
2012;():847-854. doi:10.1115/ESDA2012-82804.

Robots are increasingly being incorporated into the clinical environment. In minimally invasive surgery, robots are used to hold the tools and camera at the operating table while the surgeon performs surgery at a console away from the rest of the surgical team, reducing the opportunity for face-to-face communication. As surgery is a team-oriented process in which surgeons, nurses, and anesthesiologists collaborate to achieve the common goal of delivering care to a patient, any barrier to communication can inhibit the team process required in surgery. This study examined surgeon-nurse spatial communication in a collaborative surgical task in a controlled experiment. It was hypothesized that providing a spatial communication aid would improve performance time and reduce the amount of communication needed for the task. Fifteen dyads of surgeons or novices completed a simulated organ manipulation task using a laparoscopic trainer box in two viewing conditions: aligned (0°) and rotated (90°) camera view. Subjects were divided into 3 experimental groups: control, cardinal directional aid, and grid directional aid. Results show that experts were faster than novices, and the directional aids significantly facilitated task performance. While the volume of communication was not different across the three groups, there was a shift toward a more collaborative style of communication in the cardinal directions and grid conditions. The findings suggest that spatial communication aids can improve performance and promote collaboration in the robotic operating room.

Topics: Design , Robotics , Surgery
Commentary by Dr. Valentin Fuster
2012;():855-860. doi:10.1115/ESDA2012-82869.

This study investigates how the technical and perceptual skills in laparoscopic surgery, typically acquired separately in the initial learning phases, can be trained together. A task analysis and cognitive task analysis were conducted using a cholecystectomy procedure and a fundoplication procedure. An experiment was conducted to examine the interaction of technical and perceptual skill learning. Subjects were divided into three groups based on order of skills training: 1) technical-perceptual-combined skills training order, 2) perceptual-technical-combined skills training order, and 3) combined skills training. After the training sessions, performance was evaluated using the combined skill. Preliminary results indicate that performance of the group trained in the combined skills condition performed equally quickly as those who trained the technical and perceptual skills separately first. In addition, the number of technical errors and perceptual errors committed were lower. This suggests that surgical skills training may be more efficient if perceptual learning is combined with motor skills during the initial phases of training. This has implications for the design of surgical training simulators and surgical education in general.

Topics: Design , Surgery
Commentary by Dr. Valentin Fuster
2012;():861-869. doi:10.1115/ESDA2012-82874.

This study deals with behavior identification of Electric-Powered Wheelchair (EPW) drivers. User’s actions on the joystick determine this behavior. We assume that a driver evaluation can be performed using reference behaviors which are determined a priori. This study was carried out with two valid populations. The first one includes eight experimented subjects. The second includes six novice subjects. We propose to implement the Fuzzy C-Means (FCM) classification to separate different behaviors. The FCM was applied on the experimented population in order to determine reference’s behaviors. This shows that there were basically two different behaviors. An evaluation is performed on novice users by comparing their behaviors with respect to the reference ones. The results show that this population has an erratic behavior during the learning phase. Subsequently, users converge to one of the identified reference behaviors. We also evaluated a subject who suffers from muscular dystrophy and uses an EPW in everyday life. The results show a steady driving behavior.

Topics: Wheelchairs
Commentary by Dr. Valentin Fuster
2012;():871-880. doi:10.1115/ESDA2012-82892.

Human-automation interaction in complex systems is common, yet design for this interaction is often conducted without explicit consideration of the role of the human operator. Fortunately, there are a number of modeling frameworks proposed for supporting this design activity. However, the frameworks are often adapted from other purposes, usually applied to a limited range of problems, sometimes not fully described in the open literature, and rarely critically reviewed in a manner acceptable to proponents and critics alike. The present paper introduces a panel session wherein these proponents (and reportedly one or two critics) can engage one another on several agreed questions about such frameworks. The goal is to aid non-aligned practitioners in choosing between alternative frameworks for their human-automation interaction design challenges.

Topics: Design
Commentary by Dr. Valentin Fuster
2012;():881-888. doi:10.1115/ESDA2012-82974.

Using the ecological interface design approach, a graphical user interface was developed to show how different factors (e.g., LDL, HDL, triglycerides, systolic blood pressure) contribute to cardiac health. The display is based on an epidemiological model derived from the Framingham study and additional treatment guidelines in the medical literature. This interactive display allows physicians and patients to see how different factors contribute to overall cardiac health and to see the impact of interventions on reducing risk. The display also graphically associates the state of the patient with treatment categories to help physicians to select the best treatment method based on empirical models. It also has the potential to enrich the dialogue between physician and patient through interactive ‘experiments’ that illustrate the potential benefits of various treatment options.

Commentary by Dr. Valentin Fuster
2012;():889-896. doi:10.1115/ESDA2012-82977.

Changes in Air Traffic Management, exemplified by the NextGen and SESAR projects, intend to achieve ATM systems with a higher capacity and also higher efficiency, through more direct routing. At the same time, air traffic safety should continue to increase. An important step in this process can be the partial or full transfer of responsibility for separation to the flight deck, using Airborne Separation Assurance Systems (ASAS). This paper discusses the development of interfaces for ASAS operations using Ecological Interface Design. Rather than focusing on the development and testing of the displays themselves, it addresses the parallels and differences between EID in the process control domain (from which EID originated) and EID in the air traffic domain.

Topics: Design , Aircraft
Commentary by Dr. Valentin Fuster
2012;():897-905. doi:10.1115/ESDA2012-83015.

A fundamental challenge in the design of any cognitive system is to support productive thinking and efficient control. Research shows that human problem solving can be greatly enhanced using representations that reflect the deep structure of problems. Further, research on human action shows that selectively constraining degrees of freedom can improve both speed and accuracy of performance. This talk will discuss how these two insights from the basic research literature can be incorporated into work analysis and interface design to enhance performance of cognitive systems. The goal is to design interfaces so that the deep structure of the problem is well mapped to the opportunities for action. A major challenge is to operationalize the basic constructs of deep structure and smart mechanism in terms of specific work domains. Examples from the medical and aviation domains will be used to illustrate how this challenge is being met.

Topics: Design
Commentary by Dr. Valentin Fuster

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