bluuebunny/crossref_metadata_2025 huggingface dataset:
Transfer Matrix Computation for Wave Action Simulation in an Internal Combustion Engine
Authors: Mezher Haitham , Chalet David , Chessé Pascal , Migaud Jérôme , Raimbault Vincent
Published: December 2013

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.
Analysis of the Oil Squeezing Power Losses of a Spur Gear Pair by Mean of CFD Simulations
Authors: Concli Franco , Gorla Carlo
Published: December 2013

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.
Virtual Reality Interfaces Applied to Web-Based 3D E-Commerce
Authors: Elordi Unai , Segura Alvaro , Goenetxea Jon , Moreno Aitor , Arambarri Jon
Published: December 2013

E-commerce is well established on today’s Internet and has created its own set of techniques for performing and optimizing sales. Traditional shops on the other hand provide a physical space in which decoration and space are relevant. In this paper we present innovative interfaces that join the concepts of real shops and on-line e-commerce in a Web-based virtual reality platform.

The idea involves making the e-shopping experience more intuitive, closer to the experience of visiting a real shop, and providing on-line 3D interfaces for the entire process from shop design and product placement to customer experience analysis. We researched traditional marketing and sales techniques and the way they can be transferred to 3D virtual reality environments. Web 3D technologies allow us to implement interactive virtual worlds on the Web, accessible for everyone over different platforms and without special applications or plug-ins.
Energy of Vibroacoustic Signal as Parameter of Logistics Model of the Tooth’s Crack Development
Authors: Radkowski Stanisław , Gumiński Robert
Published: December 2013

The paper takes on the issue of uncertainty in statistical methods of cracks propagation. The goal of the paper was to develop a method, which would enable use of diagnostic information in assessment of fatigue damage process.

Particular attention was paid to the possibility of forecasting the occurrence of damage due to fatigue while relying on the analysis of the structure of a vibroacoustic signal. The difficulty in this case is that the set of parameters containing diagnostic information may change as defects develop. This fact confirms the necessity of examining the evolution of probability distribution and defining the periods of an object’s operation, carried out while taking into account the actual technical condition as well as the associated identification of defect development phases. The study presents the following issue: developing the method of diagnosing the early stages of defect development while analyzing energy of vibroacoustics signal as parameter of logistics model of cracks development.
Improving the Performance of Resonant Controls for Vibration Suppression Using a Negative Derivative Feedback
Authors: Cazzulani Gabriele , Resta Ferruccio , Ripamonti Francesco
Published: December 2013

The paper presents a resonant control technique called Negative Derivative Feedback (NDF), suitable for vibration suppression in mechanical flexible structures. Resonant controllers calculate the control action through a feedback compensator. For NDF this compensator works as a band-pass filter, allowing to reduce some problems typically arising with resonant controllers like, for example control spillover. The proposed control logic is compared with different state of the art resonant controllers, such as Independent Modal Space Control, Positive Position Feedback and Active Modal Tuned Mass Damper, showing better performances both theoretically and experimentally.
A Real-Time Algorithm for Fault Detection in Construction Machinery
Authors: Cazzulani G. , Moschini S. , Ripamonti F. , Resta F.
Published: December 2013

The laws concerning safety on worksite have become more strict year on year being that topic always more important. The main causes of injuries are workers unawareness and structural failures of machineries, i.e. cranes, or scaffolds. In order to prevent injuries, an accurate maintenance is mandatory. During the last years a new trend in maintenance has arisen in opposition to programmed maintenance. Monitoring the system, the condition based maintenance may prevent accidents avoiding unnecessary stops of the machineries and the corresponding reduced returns.

In this paper a health monitoring algorithm for a typology of construction machinery (the concrete displacing booms) is proposed. The proposed algorithm is based on the knowledge of geometrical and dynamical parameters of the boom, estimated through a stand-alone self-learning procedure. This feature makes the developed diagnostics system predisposed to be easily extended to other machineries or work fields. The common failure conditions, such as an overload or a crack propagation, are readily signaled.

The algorithm has been numerically and experimentally validated on a specific test rig which reproduces a reduced scale concrete displacing boom. The results, referred to the detection of two simulated common failure conditions, are presented and discussed.
View-Dependent Rendering to Enhance Natural Perception for Augmented Reality Workstations
Authors: Radkowski Rafael , Oliver James
Published: December 2013

This paper presents a novel method for view-dependent rendering for monitor-based Augmented Reality (AR) applications that enhances natural visual perception. A typical monitor-based AR workstation incorporates a large monitor that acts as a window to the physical workspace in front of it. Although these workstations are often used in industrial AR applications, they unfortunately do not provide natural visual perception. This research focuses on the development of AR system and a novel method for real-time rendering of the augmented scene that incorporates the user’s point of view. Thus, the user gets the impression of natural visual perception while moving in front of the monitor. This paper introduces the hardware setup, geometric registration to determine the correct view, and image processing. A sequence of images is presented that demonstrates the advantages of this method.
A CFD Simulation of a Ducted Wind Turbine With Ejector Assist
Authors: Georgiou Demos P. , Milidonis Kypros F. , Theodoropoulos Nikolaos G.
Published: December 2013

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.
Optimal Plant Configuration for the Nearly Ideal Processes of an OTEC Concept Driven by the Sea–Air Temperature Difference
Authors: Georgiou Demos P. , Milidonis Kypros F. , Theodoropoulos Nikolaos G.
Published: December 2013

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.
Using Welding Simulation and Ultrasonic Method to Evaluate Residual Stress in Stainless Steel Welded Plates
Authors: Javadi Yashar , Raeisi Mohammadreza Hadizadeh , Pirzaman Hamed Salimi , Najafabadi Mehdi Ahmadi
Published: December 2013

When a material is under mechanical load, the stresses change the velocity of acoustic waves because of acoustoelastic effect. This property can be employed for stress measurement in the material itself when the stress concerns the surface of the material, or in the bulk material. This technique involves with critically refracted longitudinal waves that propagate parallel to the surface, i. e. LCR waves. This paper presents a three dimensional thermo-mechanical analysis to evaluate welding residual stresses in plate-plate joint of AISI stainless steel 304L. After finite element simulation, the residual stresses were evaluated by LCR ultrasonic waves. This paper introduces a combination of “Finite Element Welding Simulation” and “Ultrasonic Stress Measurement using the LCR Wave” which is called as “FELcr”. The capabilities of FELCR in residual stress measurement are confirmed here. It has been shown that predicted residual stress from three dimensional FE analyses is in reasonable agreement with measured residual stress from LCR method.
Human Perceptions of Nonverbal Behavior Presented Using Synthetic Humans
Authors: Gallimore Jennie J. , Ward Blake , Johnson Adrian , Leard Bobbie , Lewis Jeremy , Preuss Kyle , Skipper Julie
Published: December 2013

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).
Ecological Interface Design for a Water Monitoring Decision Aid
Authors: Kan Kevin C. , Jamieson Greg A.
Published: December 2013

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.
Performance Improvement of a Centrifugal Compressor Using a Developed 3D Inverse Design Method
Authors: Nili-Ahmadabadi Mahdi , Poursadegh Farzad , Shahhosseini Majid R.
Published: December 2013

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.
Simulation Technology of Self-Induced Vibration in a Metal Pushing V-Belt CVT
Authors: Saito Toshihiro
Published: December 2013

Noise and vibration are factors affecting the marketability of automobiles. It is required for the drivetain design not to transmit unpleasant noise and vibration to the passengers when driving. As for continuous variable transmission (CVT), noise that is considered to be generated from the metal pushing V-belt has been studied. A research project on this matter reported an estimated mechanism that attributes the noise to self-inducing vibration between the metal pushing V-belt and the pulleys. The self-induced vibration occurs when dynamic friction characteristics exhibit a negative gradient in relation to the sliding speed. However, the effect of the gradient on frequency spectrum of the noise has not been quantitatively elucidated in a consistent manner.

In this research, noise at the vehicle start-up phase was studied based on the already reported prediction technology for metal pushing V-belt behavior. In other words, this study focuses on the effect of the friction characteristic gradient between the metal pushing V-belt and the pulleys on each element’s behavior and frequency components of belt pushing force.

The results revealed that self-induced vibration on the element V-surface at the exit of the drive pulley excites high-order string vibration at the belt string, generating noise via the transmission case. In addition, it was also found that acoustic energy that excites the high-order string noise is affected by the change in belt pitch diameter at the exit of the pulley, and this determines the magnitude of frequency spectrum of the noise.

It was concluded from the above findings that the change in the pitch diameter can be suppressed by narrowing the radial clearance between the shaft and the movable pulley and this measure is effective in reducing noise.
Modeling and Optimization of Heat Exchangers Within Gas Turbine Systems
Authors: Tirca-Dragomirescu Georgiana , Costea Monica , Feidt Michel , McGovern Jim , Dobrovicescu Alexandru , Tutica Diana , Kheiri Abdelhamid
Published: December 2013

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.
Optimized Control Strategy Based on the Driving Cycle Type for a Hydraulic Hybrid Bus
Authors: Safaei Ali , Esfahanian Vahid , Ha’iri-Yazdi Mohammad Reza , Esfahanian Mohsen , Tehrani Masood Masih , Nehzati Hassan
Published: December 2013

Using hybrid powertrains is an attractive idea to reduce the fuel consumption in vehicles. Control strategy is the most challenging subject in designing of a hybrid powertrain. In this paper, an optimized control strategy based on the driving cycle type designed for a hydraulic hybrid bus has been presented. Because of considering the type of the driving cycle, the proposed control strategy can be named as an intelligent one. In this controller, at first, four standard driving cycles have been defined as the reference clusters. Then the optimized control strategy for each cluster has been derived using a dynamic programming algorithm. In addition, several multi-layered perceptron networks are modeled in order to use the output of each optimized control strategy. After that a clustering method with a feature selection algorithm has been implemented to assign degree of similarity to each cluster for the unknown driving cycle. Finally, a linear combination of four optimized control strategy outputs has been used for generating final output of the intelligent control strategy. In this combination, each output is weighted by the corresponding degree of similarity. Here, the hydraulic hybrid bus model is a feed forward one and has been simulated using a compound driving cycle. The compound driving cycle consists of six distinct 100s long portions of the Nuremburg driving cycle. The simulation results show that by using the intelligent control strategy, the fuel consumption of the hybrid bus has been reduced by almost 12% in comparison with the results of a rule-based control strategy.
Experimental Investigation of High Density Polyethylene Yield Surface Under Biaxial Loading
Authors: Hachour Kamel , Aberkane Meziane , Ferhoum Rabah
Published: December 2013

A series of biaxial experiments are performed to investigate the yield envelope of high-density polyethylene (HDPE). An Arcan apparatus is achieved in order to load a newly-designed flat specimen “butterfly specimen” to various combinations of tensile/compressive and shear loading. It subjected a central section of the specimen to a uniform state of plane stress. The stresses have local maxima at the central section, thus ensuring that yielding occurs there. The yield stresses are determined from the load-displacement curves and plotted in two-dimensional principal stress. The experimental results are compared with a predicted yield envelope based upon a pressure modified von Mises criterion, which accounts for the difference in tensile and compressive yield stress; additionally the hydrostatic pressure on yielding is also considered. Good agreement is found.
Simulation of Noise Attenuation Using One and Two Degree of Freedom Helmholtz Resonators in Pipelines
Authors: Farooqui Maaz , Mekid Samir
Published: December 2013

Helmholtz resonators are known to be efficient resonators for ducts if they are properly designed. A design procedure is suggested in this paper to identify the size of the resonators in one and two degrees of freedom. The procedure is supported by a through numerical simulation of acoustic wave propagation that is presented and is verified using published experimental results. The overall procedure shows achievable great attenuation of noise in pipeline.
A Tentative Model for Analysis of Human-Automation Interaction in Control Rooms
Authors: Andersson Jonas
Published: December 2013

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.
Geometry Effects on the Noise Reduction of Helmholtz Resonators
Authors: Farooqui M. , Alhamoud A. , Aliuddin A. , Mekid S.
Published: December 2013

In this paper the effect of geometry shape of the Helmholtz resonator on its resonant frequency and on its noise attenuation capability is discussed. The theory of resonant frequency depending on the shape of the vessel of the resonator is verified analytical and numerically using COMSOL for one and two degrees of freedom. The simulation was validated experimentally and has shown very good agreements. Various shapes of the resonators were compared in arrays. A better understanding of the shape effect is shown through simulations.
Comparison Between Numerical and Experimental Gas Side Heat Transfer and Pressure Drop of a Tube Bank With Solid and Segmented Circular I-Fins
Authors: Hofmann Rene , Walter Heimo
Published: December 2013

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 k–ε 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.
Control Strategy for the Optimal Operation of a Solar Cooling Installation
Authors: Verda Vittorio , Baccino Giorgia , Pizzuti Stefano
Published: December 2013

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.
Modelling the Heat During the Injection Stretch Blowing Moulding: Infrared Heating and Blowing Modelling
Authors: Luo Yun Mei , Chevalier Luc , Utheza Françoise
Published: December 2013

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.
Efficiency of Implicit Symplectic Finite-Difference Time-Domain Method for Near-Field Optics
Authors: Saitoh Ikuo , Naruse Makoto
Published: December 2013

We proposed a new method, implicit symplectic finite difference time domain (FDTD) method) which inherits the good properties from the conventional FDTD method, simplecticity and the conservation of energy. The proposed method is free from the Courant-Friedrics-Lewy condition at the same time.

In this paper, we show our method is more efficient than the conventional FDTD method using a typical problem, a polarization control in optical near and far fields of the designing the shape of a metal nanostructure.
Experimental Analysis and Simulation of the Dynamic Response of a Propeller Pitch Change Actuator
Authors: Leclercq Maxime , Malburet François , Veron Philippe
Published: December 2013

This paper focuses specifically on the control of the propeller pitch change mechanisms and their associated dynamics. The subject of this article is restricted to the mechanisms using a hydraulic single acting actuator. They function asymmetrically and are subject to important varying external loads under the full flight envelope. This phenomenon has an impact on their dynamic response.

The question of the dynamics of these systems is rarely dealt with because, usually for aircraft applications, there is no real requirement for propeller pitch dynamic control. But, in the case of some applications, such as the Eurocopter X3, this dynamic control aspect and the safety aspect of the propeller pitch change mechanism are particularly important, because this mechanism is fully involved in aircraft safety, control and handling qualities.

Firstly, this paper gives an explanation of the phenomena applied to the propeller pitch change mechanism and their contributions to its dynamic response. Then, a model of the dynamic response is proposed. Finally, an experimental identification of the pitch change mechanism dynamics concludes this article.
Computational Models for Resistance Spot Welding
Authors: Mollicone Pierluigi , Muscat Martin , Said Matthew
Published: December 2013

Spot welding is a very important joining process for many industries. Structural integrity of a spot welded joint is however compromised by the formation of residual stress fields, which arise due to the thermal loadings imposed on the material during this welding process. Experimental investigation of these effects is possible but often costly, especially in complex and large-scale applications. Computational models, through the application of advanced Finite Element Analysis (FEA) techniques, are hence of interest for the prediction, analysis and assessment of these effects. The computational modelling required to assess these effects is however relatively complex due to the interaction of thermal and structural solution fields. It follows that many decisions must be taken with regards to the modelling technique to adopt in these scenarios.

This work presents a modelling technique for the prediction of spot welding induced residual stresses, validated with experimental measurements for the temperature and residual stress fields. The simulations, carried out in ANSYS, are aimed at using a general-purpose solver to predict residual stresses whilst the validation is carried out through transient thermocouple measurements and residual stress measurements done using the hole drilling method. Comparison of experimental and FEA model results highlight which parts and assumptions of the computational model are to be considered valid and hence its boundary for use in industry.
Effect of Changing Atmospheric and Operating Conditions on the Thermal Stresses in PV Modules
Authors: Siddiqui M. U. , Arif A. F. M.
Published: December 2013

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).
Lifetime Prediction of Rocket Combustion Chamber Wall by Means of Viscoplasticity Coupled With Ductile Isotropic Damage
Authors: Tini Vivian , Vladimirov Ivaylo N. , Reese Stefanie
Published: December 2013

This paper presents the application of a viscoplastic damage model for the lifetime prediction of a typical rocket combustion chamber structure. The material modeling is motivated by extension of the classical rheological model for elastoplasticity with Armstrong-Frederick kinematic hardening into a viscoplastic model. The coupling with damage is performed using the concept of effective stress and the principle of strain equivalence. The material parameters are identified based on experimental results for the high temperature copper alloy NARloy-Z, which is one of the typical combustion chamber wall materials. Finally the applicability of the model will be shown by means of sequentially coupled thermomechanical analyses.
Modeling Patients for Optimized Port Placement in Robot-Assisted Surgery
Authors: Bañez Jose , Caro Stéphane , Schwaitzberg Steven , Classe Jean-Marc , Cao Caroline G. L.
Published: December 2013

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.
Finite Strain Constitutive Model of Evolving Elastic and Plastic Anisotropy by Means of Structure Tensors
Authors: Vladimirov Ivaylo N. , Reese Stefanie
Published: December 2013

In this paper, a finite strain constitutive model for evolving elastic and plastic anisotropy combining nonlinear isotropic and kinematic hardening is presented. The evolution of elastic anisotropy is described by defining the Helmholtz free energy as an isotropic function of a family of evolving structure tensors. In addition, plastic anisotropy is modelled via the dependence of the yield surface on the same family of structure tensors. Exploiting the Clausius-Duhem inequality leads to the interesting result that all tensor-valued internal variables are symmetric. Thus, the integration of the evolution equations can be efficiently performed by means of an implicit algorithm that automatically retains the symmetry of the internal variables in every time step. The material model is used as a user material subroutine UMAT infinite element package ABAQUS/Standard, by means of which the occurrence of earing during cylindrical deep drawing is simulated.
A 3D-GIS Updating Method With Interaction in an Urban Environment
Authors: Liu Ruijun , Servières Myriam , Moreau Guillaume
Published: December 2013

This paper presents a method for reconstructing 3D buildings and updating Geographic Information System (GIS) data from video. We use 2D-GIS data and a ground-based video sequence as inputs. The main approach consists of three parts. In the first part, the data is captured and analyzed: besides the 2D-GIS data, we capture a video from a street view; then we can obtain thousands of3D feature points by our extracting algorithm and design a noise filter to remove outliers. In the second part, we present a generation process, which contains the footprint extraction and basic facades reconstruction. The last part is the correction and updating process: after correcting the footprint and computing the height of the building, our method will update the data into GIS. In addition, we use some user knowledge to make the results much more accurate. In the filtering and the correcting process, our method can deal with several interactive operations.
Some New Theoretical Results for Orthotropic Inflatable Beams
Authors: Nguyen Quang Tung , Thomas Jean-Christophe , Le Van Anh
Published: December 2013

A so-called inflatable beam is a membrane tube which gains its stiffness only by a prescribed internal pressure. Such lightweight structures are useful in inflatable buildings and particularly in space industry, whenever rapidly deployable and easily transportable structures are required.

An inflatable beam may look like a standard beam, but its mechanism is quite different and a specific mechanical study is necessary in order to establish its governing equations. The only way to correctly take account of the internal pressure — which is a follower load — is to carry out a complete nonlinear analysis before any possible linearization.

This work aims to extend the analytical results for isotropic inflatable beams to the practical situation when the beam is made of an orthotropic fabric. It will be shown that the Timoshenko beam model combined with the finite rotation kinematics enables one to correctly account for all the nonlinear terms in the governing equations. A linearization will then be performed to study deformations about the pre-stressed reference configuration. Furthermore, it will be shown how to precisely compute the radius and the length of the inflated tube in the reference state, a very significant issue which is overlooked so far in the literature. All the proposed analytical results will be compared with the numerical ones obtained from a nonlinear 3D finite element code.
Adaptive Second Order Sliding Mode Control: Application to Position and Force Control of Electro-Pneumatic Actuators
Authors: Taleb Mohammed , Plestan Franck
Published: December 2013

This paper presents an application of adaptive 2nd order sliding mode control. This control is based on twisting algorithm and ensures a finite time convergence to the sliding manifold σ = σ̇ = 0, σ being the sliding variable and defined from the control objectives. The control solution required a limited information about the uncertainties and the disturbances acting on the system. This control strategy is applied to an electropneumatic set-up. This bench consists of two rod coupled pneumatic cylinders: one cylinder is controlled on position and perturbed by the second cylinder which is force-controlled. The efficacy of this strategy is evaluated through some simulations.
Towards Delayed Teleoperation With Pneumatic Master and Slave for MRI
Authors: Leleve Arnaud , Pham Minh Tu , Tavakoli Mahdi , Moreau Richard
Published: December 2013

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.
Sensitivity Analysis of a Solar Cooling System
Authors: Letexier Blaise , Marc Olivier , Praene Jean-Philippe , Lucas Franck
Published: December 2013

The aim of this paper is the optimization of Solar Absorption Cooling (SAC) system’s performances. Over the past decade the electricity consumption has significantly increased in Reunion Island during the summer months, which is mainly due to the use of standard air conditioning systems. SAC systems present a good alternative for reducing this consumption. Solar cooling systems are environmentally friendly as they use water and lithium bromide solution as the working fluid.

The purpose of this work is to undertake a sensitivity analysis to identify parameters which have a significant influence on the SAC systems performances. The sensitivity analysis has been carried out on numerical models developed at the PIMENT laboratory and validated using RAFSOL experimental data (experimental plant is set up at the IUT in St-Pierre). The results of the sensitivity analysis are used to establish the design and create the control rules to allow for the optimization and ensure the performance of future SAC systems.

Firstly, this paper presents the modelization of the SAC system and the sensitivity analysis method used. Secondly, it displays the results from the sensitivity analysis that has been applied to all main components of the plant separately (solar collector field, solar loop and absorption chiller) and to the entire system. Finally, the results are analyzed and discussed.

Two types of influential parameters have been distinguished: variables factors and geometrical properties of the plant. This study highlights that the compactness of the installation, the quality of the solar collector, and the control of the temperature at the output of the distribution loop are essential.
Enhancing the Performance of Photovoltaic Solar Modules by Active Thermal Management
Authors: Rodgers Peter , Eveloy Valerie , Bojanampati Shrinivas
Published: December 2013

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.