bluuebunny/crossref_metadata_2025 huggingface dataset:
The Secant Modulus of Elasticity of Stay Cables Stiffened by Secondary Steel Cables
Authors: Mura Igino
Published: November 2008

Provided herein is the expression for calculation of the secant modulus of elasticity E*HS for stay cables stiffened with the application of elastic stiffening cables. The solution obtained is compared with the formulation of the tangent modulus of elasticity EiH proposed by Tschemmernegg and Obholzer. The general validity of the formula obtained is shown, as are the significant limitations inherent in the use of the tangent expression for finite tensional ranges in the stays for purposes of comparison. It is found that vertical cables are more effective than inclined ones, although their use implies greater limitations because of fatigue phenomena and the danger of unloading.
Transient Operation Analysis of a Cogenerating Micro-Gas Turbine
Authors: Bozza Fabio , Tuccillo Raffaele
Published: November 2008

A cogenerating micro gas turbine, operating with a partially recuperated thermal cycle based on a by-pass option towards the heat recovery boiler, is examined under the point of view of the transient developments. The latter are induced by variations in both electrical and thermal loads and are strongly affected by the fuel supply law and by the response delay of the rotating and stationary components. Several unsteady cases are investigated, by comparing different time changes in the fuel flow rate under constant or variable speed operating conditions. These examples allow identification of the most efficient fuel control laws, together with some possible critical conditions induced by either instabilities in the rotating components or by unreliable fuel/air ratios during the transient development.
Evaluating the Performances of Advanced Powertrains
Authors: Feola Massimo , Martini Fabrizio , Ubertini Stefano
Published: November 2008

Over the last few decades a tremendous effort has been made to reduce road vehicles engines contribution to air pollution and fuel consumption. Due to the more stringent limits imposed by governments, various manufactures started working in the incorporation of alternative powertrain configurations, such as pure electric vehicles (EV), hybrid electric vehicles (HEV) and fuel cell vehicles (FCV), in the automotive consumer market. In order to appreciate the advantages and disadvantages of these new vehicles over conventional vehicles a comparison must be performed in terms of efficiency and pollutant emissions. However, hybrid vehicles comprise many components with at least two different energy conversion devices (i.e. internal combustion engine and electric machine) drawing energy from at least two different energy storage devices (i.e. fuel tank and battery). In recent times, many hybrid propulsion system configurations have emerged and many others can be imagined comprising multiple reversible and irreversible energy paths. Therefore, considering that in a hybrid vehicle at least two different forms of energy (i.e. fuel chemical energy and electricity) are consumed, fuel consumption alone is no more sufficient to give a measure of the effectiveness of a hybrid propulsion system. This paper presents a first attempt to give a general mathematical form of the traction energy, the global efficiency and the specific fuel consumption of a hybrid electric vehicle that recovers as particular cases the thermal vehicle and the series hybrid electric vehicle. To evaluate the efficiency of the generic propulsion system the complete process from fuel energy and electricity to power available at the wheels is considered. The introduced concept of equivalent fuel consumption can be the basis for the comparison between road vehicles whatever the powertrain is pure thermal or hybrid. In order to get a better understanding of the mathematical analysis and its potential effectiveness some numerical simulations of hybrid vehicles virtual prototypes are performed through a suitable simulation model. The aim of the present analysis is to provide an instrument that allow a quick evaluation of the performances of hybrid electric vehicles.
Hybrid EDM and Grinding Hard Materials Using a Metal Matrix Composite Electrode
Authors: Shu Kuen Ming , Shih Hung Rung , Lin Wen Feng , Tu G. C.
Published: November 2008

Electrical discharge machining (EDM) has been shown to be a versatile method for machining difficult-to-work materials including heated-treated steels, tungsten carbides and various conductive ceramics. However, low machining efficiency is one of the main EDM disadvantages. The topic of how to reduce machining time and maintains reasonable accuracy has always been of research interest. The main object of the present work was to develop an electrical discharge machining and grinding (EDMG) methodology to remove the re-solidified layer through the grinding induced by a metal matrix composite electrode prior to the re-solidified layer solidification. A metal matrix composite (Cu/SiCp) electrode, with an electroless pretreatment of Cu coating on SiCp to enhance bonding status between Cu and SiCp, with a rotating device was made and employed to study the EDMG technology. Machinabilities of mold material, HPM50 mold steel and P20 WC/Co, were investigated by the combined technologies of EDMG. The machined surfaces of these materials were examined by scanning electron microscopy (SEM) and their surface roughness measured by a profile meter. From the experimental results, it was found that higher material removal rate and lower surface roughness can be achieved when suitable electrode rotating speed, SiCp size and working current are chosen. In addition, the surface roughness of both materials could be improved as compared with that following the EDM process.
An Investigation on Velocity Triangle Applied to Fluid Particle at Rotating Flow Passage of Impeller Blade in Centrifugal Pump
Authors: Tanaka Takaharu , Liu Chao
Published: November 2008

Although impeller blades rotational speed is kept constant for the change in flow rate, fluid particles rotating speed varies by the flow rate. Fluid particles circularly forward tangential velocity becomes zero at the maximum flow rate and the maximum at the flow rate zero. While fluid particles fundamental straightly forward tangential velocity normal to rotational radius becomes the maximum at the maximum flow rate and zero at flow rate zero.
Requirements of Air-Conditioning Systems’ Developments in Hospitals and Critical Healthcare Facilities
Authors: Khalil Essam E. , Kameel Ramiz
Published: November 2008

The balance between thermal comfort and air quality in healthcare facilities to optimize the Indoor Air Quality (IAQ) is the main aim of this paper. The present paper will present this balance from the viewpoint of the air conditioning design. It was found that the design of the HVAC airside systems plays an important role for achieving the optimum air quality beside the optimum comfort level. This paper highlights the importance of the proper airside design on the IAQ. The present paper introduces some recommendations for airside designs to facilitate the development of optimum HVAC systems. This paper also stresses on the factors that improve the thermal comfort and air quality for the already existed systems (for maintenance procedure). To design an optimum HVAC airside system that provides comfort and air quality in the air-conditioned spaces with efficient energy consumption is a great challenge. The present paper defines the current status, future requirements, and expectations. Based on this analysis and the vast progress of computers and associated software, the artificial intelligent technique will be a competitor candidate to the experimental and numerical techniques. Finally, the researches that relate between the different designs of the HVAC systems and energy consumption should concern with the optimization of airside design as the expected target to enhance the indoor environment. The present paper reviews the results of recent advances that are concerned with the HVAC design engineering in the healthcare applications. The following requirements are necessary for Health and hygiene considerations: • Air movements are to be restricted in and between the various hospital departments (no cross movement). • Appropriate ventilation and filtration is used to dilute and reduce contamination in the form of odour, air-borne micro organisms, viruses, hazardous chemical and radioactive substances. • Temperature and relative humidity are to be regulated and attained for various medical areas. • Environmental compliance conditions should be maintained, accurately controlled and monitored.
Mechanical Properties Measurement of Electroactive Polymers
Authors: Han L. H. , Lu T. J.
Published: November 2008

Electroactive polymers (EAPs), such as piezoelectric polymer, polyelectrolyte gels, dielectric elastomer and conducting polymer etc., are emerging as a new type of actuation materials for a broad range of actuator and transducer applications, because of their higher strain, higher response and higher efficiency. Acrylic elastomer films have demonstrated higher specific energy density (0.4J/g) and more than 100% actuated strains, and have been recommended for the artificial muscle actuators. Much research has been carried out to investigate the actuation properties of EAP films, however, little information is available for the mechanical properties of EAP films, which are crucial for designing EAP actuators. This work focuses on developing a means of characterizing the mechanical properties of EAP thin film materials, describing the mechanical behavior with the suitable constitutive models and determining the material parameters for the development of actuators. To measure the mechanical properties of EAP films, a uniaxial testing system is developed, which consists of a small-scale force transducer, a CCD camera, a National Instruments card and a laser displacement transducer. The loading and unloading cycles on film specimens are controlled by an Instron Machine. The applied force and the total are stored in the computer by the National Instrument card. A sequence of 2D images are recorded by the CCD camera to capture the deformation process of the film sample. Then, the displacements of the marks on the film surface vertical to the thickness plane are calculated from the sequential images by image analysis techniques. There are several well-known models available to describe the mechanical behaviors of the EAP films, such as Neo-Hookean, Mooney-Rivlin and Ogden models etc. To determine the most suitable constitutive models and corresponding material constants, a generalized method based on finite element analysis is proposed and implemented by interfacing with ABAQUS finite element package. The kernel of the method is to minimize the difference between the measured displacement field and the computed displacement field. A global optimisation algorithm, simulated annealing (SA), is used to minimize the objective. The experimental investigation on the mechanical properties of the dielectric elastomer film (VHB4910) is presented as an example to demonstrate the functions of the testing system and the developed method. The developed testing system and method can also be used for characterizing the mechanical properties of other EAP film materials.
Blank Shape Design Based on Inverse Finite Element Method Using Ideal Forming Theory and a Modified Kinematics Formulation
Authors: Habibi Parsa Mohammad , Pournia Payam
Published: November 2008

For stamping of sheet metals and converting them to specific product shapes without failure, the initial blanks should be correctly designed. Otherwise, final products will not be sound. So initial blank design is a critical step in stamping design procedure. In the present paper for calculating the total deformation gradient and its relation to each step’s deformation gradient tensor (F), a modified kinematics formulation will be introduced. This formulation has been used in connection with the ideal forming theory for predicting the initial blank shape of the specified products with defined blank thickness. In the ideal forming theory, each material element is prescribed to deform in a minimum plastic work path and ideal process is obtained when the deformations are most evenly distributed in the final products. The later has been assumed for developing a FEM code to predict the blank shape and size in one step, which has been applied for three different kinds of stampings, cylindrical, square and clover shape cups. The results show the capability of the new algorithm in designing the initial blank shape for stamping products.
Control of Two-Link Flexible Structures
Authors: Wagner-Nachshoni Clarice , Halevi Yoram
Published: November 2008

A method of noncollocated controller design for non-uniform flexible structures, governed by the wave equation, is proposed. An exact, infinite dimensional, transfer function, relating the actuation and measurement points, with general boundary conditions, is derived for the multi-link case. Three modeling methods are presented and discussed. A key element of the model is the existence of time delays, due to the wave motion, which play a major role in the controller design. The design consists of two stages. First an inner rate loop is closed in order to improve the system dynamic behavior. It leads to a finite dimensional plus delay inner closed loop, which is the equivalent plant for the outer loop. In the second stage an outer noncollocated position loop is closed. It has the structure of an observer–predictor control scheme to compensate for the response delay. The resulting overall transfer function is second order, with arbitrarily assigned dynamics, plus delay.
Flow Instabilities in a Czochralski Convective System
Authors: Rahal Samir , Azuma Hisao
Published: November 2008

The aim of this study is to recognize the flow states and the transition mechanisms between them in a simulated Czochralski convective system. We considered the influence of the crystal rotation effects (up to Reynolds number, Re = 3.9×103) and the buoyancy (up to Rayleigh number, Ra = 7.2×107) on the flow. Using velocity fields, obtained by an ultrasonic method, the corresponding 2D Fourier spectra and a correlation function; steady, quasi-periodic and turbulent states were recognized as the Reynolds number was increased. The orthogonal decomposition method was applied to these velocity fields. The numbers of modes involved in the dynamics of turbulent states were calculated. From these results, we have concluded that the rotation effects tend to stabilize the flow, and the thermal gradients play a destabilizing role.
The Study of the Effects of Gas Turbine Inlet Air Cooling on the Heat Recovery Boiler Performance
Authors: Ameri Mohammad , Shahbaziyan Hamidreza , Hosseinzadeh Hadi
Published: November 2008

Heat recovery steam generators (HRSG) are widely used in industrial processes and combined cycle power plants. The quantity and the state of the produced steam depend on the flue gas temperature and its mass flow rate. Two key factors, which affect those parameters, are the ambient temperature and the load of the gas turbines. The output power of the gas turbines degrades considerably in hot days of summer. The use of the inlet air cooling system to eliminate this problem is rapidly increasing. One of the effective methods is cooling the inlet air to the compressor by Evaporative Coolers. The purpose of this paper is to study the effects of the evaporative inlet air cooling system on the performance of a heat recovery boiler in a combined cycle power plant. The heat and mass balance of a typical HRSG and its components including the superheaters, evaporators and economizers were calculated. To analyze the effects of the changes in ambient temperature and the flue gas flow, a numerical software has been used. The results have shown that using the evaporative cooler will increase the flue gas mass flow rate to the HRSG. Nevertheless, the exhaust gas temperature control system holds this temperature almost constant. Also, the results show that the produced steam temperature remains almost constant. However, the steam mass flow rate increases. Therefore the output power of the steam turbine of the combined cycle will increase. The effect of the increase in the humidity ratio is shown to be insignificant. In fact, it has negligible effect on the produced steam flow rate and the sulfuric acid dew point.
Hybrid Simulation-Emulation Model: AGVS Example
Authors: Hasnan Khalid , Perera Terrence
Published: November 2008

Simulation and emulation have several salient contrasting functions and features. They include different aims, levels of details, execution time and integration of models. In many cases, a project will require both a simulation model for initial analysis and development, as well as an emulation model for testing a control system. If this is the case, a copy of the simulation model can be used as a starting point for developing the emulation model. Hybrid simulation-emulation model, one that is used for both purposes should have a facility to switch off/on certain elements from the model as necessary. There is much published work in simulation and a dearth of work in emulation. To date there has been no work published in converting a simulation into emulation model. This paper describes a novel approach, which combines both attributes, and is illustrated using a case study based on an Automated Guided Vehicle System (AGVS).
Web-Based Occupant Feedback for Building Energy Management Systems Using Fuzzy Logic
Authors: Khoo Ivan , Cook Mark
Published: November 2008

This paper describes the development and validation of a novel web-based interface for the gathering of feedback from building occupants about their environmental discomfort including signs of Sick Building Syndrome (SBS). The gathering of such feedback may enable better targeting of environmental discomfort down to the individual as well as the early detection and subsequently resolution by building services of more complex issues such as SBS. The occupant’s discomfort is interpreted and converted to air-conditioning system set points using Fuzzy Logic. Experimental results from a multi-zone air-conditioning test rig have been included in this paper.
Visual Feedback Control of a Three-Dimensional Overhead Crane
Authors: Yoshida Yasuo
Published: November 2008

Overhead cranes are used widely in various industrial fields. Crane transportation load must be transported for the work efficiency and safety to the destination without swinging. As a demand of highly precise and safety rises, automation is thought about as a method corresponding to lack of operator of mastery of skills. A transportation load of an overhead crane swings by a traveling acceleration change while doing up-and-down motion of a rope length change. It is necessary to measure this three-dimensional motion for swing suppression control. When it is installed in an overhead crane, a measurement sensor becomes complicated. In this paper, the trial stereovision device is manufactured which is a non-contact sensor, not an installation sensor and tried to control the overhead crane by vision feedback. The vision sensor is a stereovision device of four degree of freedom for tracking and gazing with two CCD cameras. A position measurement of a transportation load and an experiment of tracking control were done. The three-dimensional position of the transportation load is provided with CCD image data of two cameras, the focus distance, and four-vision device drive angles and is used for crane control. The vision device drive target angles that a point of intersection of two camera optical axes seems to always accord with the transportation load center is obtained using inverse kinematics. With these target angles, the control of tracking and gazing about the transportation load can be done. On the other hand, in an overhead crane model, using measured three-dimensional coordinate values, positioning and vibration suppression control of the transportation load was done. The overhead crane model consists of a trolley running on two perpendicular slide guide rails and a hoisting device of the transportation load. The overhead crane model has five degree of freedom, and they are x, y direction displacements of a trolley, a rope length, a swing angle, a swing direction angle. The variable rope length, the swing angle and the swing direction angle are calculated using the load position measured by the vision sensor. Variable digital gains of the trolley in consideration of the rope length change were pursued by this information, and overhead crane control was done. The experiment result of overhead crane control by vision feedback showed that the used control system was effective.
Research on Nonlinear Damping Characteristics of Damping Alloy With Uniform Stress Field
Authors: Liu Hongzhao , Wu Ziying , Liu Lilan , Yuan Daning , Zhang Zhongming
Published: November 2008

For the high damping metal material like damping alloy, the damping capacity usually changes with the strain amplitude and frequency nonlinearly. First, to extract the pattern of the internal damping versus strain, two time-domain calculation methods are presented in this paper. One is the moving exponent method (MEM for short) based on FFT (MEM+FFT) and the other is the moving autoregressive model method (MARM). The computing accuracy of the two methods has been compared through numerical simulations. The nonlinear relation curve of loss factor versus strain is achieved by the impulse excitation experiment employing uniform stress field. Then, to extract the pattern of the internal damping versus vibrating frequency, the sine sweep-frequency excitation experiment based on the half-power bandwidth method is carried out. The resulting curve indicates that the internal damping is also a nonlinear function of frequency.
Vehicle Entry and Egress in Pregnancy: A Systems Approach
Authors: Acar B. Serpil , Weekes Alix M.
Published: November 2008

Women experience a range of physical and emotional changes in pregnancy, which can impact upon their car travel. A major problem is vehicle entry and egress. This paper presents the systems approach used to gain insight into getting in and out of the car during the gestation period. The systems approach involves defining the system in terms of its objectives, subsystems, environment and interactions. A model of a vehicle system is used to interpret the problems and experiences of entry and egress reported by pregnant women. The analysis is based upon a questionnaire and anthropometric measurements. Understanding the vehicle system helps to identify both how the changed attributes of pregnant women can affect the interactions of the system, and the influence of the system environment. The systems approach is used to present an analysis of vehicle entry and egress so that automotive designers can make informed design decisions.
Analytical and Experimental Free Vibration Analysis of Uniform Cracked Thick Beam on Two-Parameter Elastic Partial Foundation
Authors: Bahc¸ıvan Ali , Karadag˘ Vedat
Published: November 2008

In this study, the analytical and experimental free vibration analysis of rectangular cross-section uniform cracked thick beam on two-parameter vibration and noise isolating elastic foundation, considering shear deformation and rotatory inertia is made by the finite element method. The beam element in our study is a recently introduced 4 degrees of freedom thick beam element and has two nodes with two degrees of freedom at each node such as transverse displacements and cross-section rotations. Two kinds of end conditions, i.e. clamped-clamped and clamped-free ends are considered in this study. Axial displacement of the beam is also considered. For axial displacement of the beam, linear finite elements are used. The elastic foundation is idealized as a constant two-parameter model characterized by two moduli, i.e. the Winkler foundation modulus k and the shear foundation modulus kG. In the case kG = 0, this model reduces to the Winkler model, i.e. the elastic foundation is idealized as a constant one-parameter model. The effects of foundation stiffness parameters, partial elastic foundation and crack changing its depth on the natural frequencies of the beam are examined. The effect of partial elastic foundation on the natural frequencies of the beam is examined for only half of the beam length. The crack is in the middle of the beam and only on one side of the beam having a form of open crack. In the analytical analysis, the spring coefficients of the crack are calculated in the computer program and then directly added to the stiffness matrix. The crack model used in this study is mentioned as a linear spring model in the literature. The crack modeled is in the middle of the beam and the related spring constants of rotational and extensional springs, which will be used, are added to the global matrix in the process. In the experimental analysis, steel and hard plastic beam are used as the beam material. Moreover, sponge and glass wool, which are manufactured by Petkim Ltd., are used as the isolating elastic foundation material. The results obtained from the analytical and experimental studies are presented by showing in tables and graphs and their importance in design is discussed. The analytical and experimental results and comparisons show the efficiency and effectiveness of the proposed method.
Development of Bone Graft Using Wire Mesh Solids
Authors: Wang B. , Kong L. X.
Published: November 2008

Bone graft is often used to restore instability of lumber spines following a surgical removal due to tumour growth or other diseases. The application of a newly developed, low cost wire mesh is examined as a potential candidate for graft. Mechanical properties of the mesh block were tested and finite element analyses were conducted to calculate stress distribution in the vertebra, with a number of parameters examined, including cross-sectional size, position, and stiffness of a graft. It is found that the intra-vertebra stress is most influenced by the graft position, followed by the cross-sectional size of the graft, while the stiffness of the graft material has the least effect.
Response Surface Method for Updating Dynamic Finite Element Models
Authors: Chen Kun-Nan , Chang Cheng-Tien
Published: November 2008

A finite element model of a structure can be updated as certain criteria based on experimental data are satisfied. The updated FE model is considered a better model for future studies in dynamic response prediction, structural modification, and damage identification. A finite element model updating technique incorporating the concept of response surface approximation (RSA) requires no sensitivity calculations and is much easier to implement with a general-purpose finite element code. The proposed updating method was incorporated with MSC. Nastran to solve the updating problem for an H-shaped frame structure. The updated results show that the predicted and experimental modes are correlated well with high MAC values and with a maximum frequency difference of 1.5%. Moreover, the updated parameters provide a physical insight to the modeling of bolted and welded joints of the H-frame structure.
How Extreme Locking of Intramedullary Nails Affects the Overall Biomechanics of Intramedullary Nail Systems
Authors: Shepherd Duncan E. T. , Johnstone Alan J.
Published: November 2008

Intramedullary nails are tube-like implantable medical devices that are commonly used to treat long bone fractures. Interlocking screws, that pass from one side of the bone to the other, through holes at either end of the nail, provide additional stability. Newer designs of intramedullary nails have screws placed more extremely. The aim of this study was to use mechanics to analytically investigate how extreme locking of intramedullary nails affects the overall biomechanics of intramedullary nail systems. The nail was modelled as a tube of various sizes. The deflection of the nail from axial compression, bending and torsion was determined as the working length of the nail was varied. The screw was modelled as a simple beam, built-in at both ends. The deflection of the screw was determined as the medullary width was varied. Placing interlocking screws more extremely in intramedullary nails increases the working length of the nail and leads to the use of longer screws, since at the bone extremities, the width of the medullary cavity increases. An increased working length leads to increased rotation of the nail. The use of longer screws leads to increased deflection of the screw and an increased bending moment that has to be resisted by the bone cortex. Extreme locking of intramedullary nails changes the biomechanics of the nail system, and may well have clinical implications in terms of fracture healing.
Behavior Based Robot Navigation: Resolving Behavior Conflicts Using Fuzzy Inference System
Authors: Parasuraman S. , Ganapathy V. , Shirinzadeh Bijan
Published: November 2008

Conflict resolution is the control decision process, which should be taken as a result of the firing among several fuzzy behavior rules. In the Behavior-based Robot Navigation System, control of a robot is shared between a set of perception-action units, called behaviors selection. In other words, the behavior selection is the way that an agent selects the most appropriate or the most relevant next action to take at a particular moment, when facing a particular problem. Based on selective sensory information, each behavior produces immediate reaction to control the robot with respect to a particular objective, i.e., a narrow aspect of the robot’s overall task such as obstacle avoidance or goal seek. Behaviors with different and possibly incommensurable objectives may produce conflicting actions that are seemingly irreconcilable. The main issue in the design of behavior based robot control systems is the formulation of effective mechanism to coordinate the behavior’s activities without any behavior conflicts during navigation. This paper presents the techniques to design the behaviors and resolve the behaviors conflicts, which are based on the Situation Context of Applicability (SCA) of the environments.
An Optical Method for the Study of Aerosol Generation in Dry Powder Inhalers
Authors: Versteeg Henk K. , Wildman Ricky D.
Published: November 2008

Dry powder inhalers (DPIs) are portable, breath-actuated devices used for respiratory drug delivery. They have been the subject of intense research and development activity over the last 15 years, however, no systematic study of the effects of geometry on aerosol generation in DPIs has been reported in the literature. In particular, the first stage process — powder fluidisation — has hardly been studied in the context of DPI applications. The short time scales and the complexities of the air/powder interactions during the conversion of a powder bed into an aerosol present a challenging environment for experimental study. This paper reports an optical technique for the study of powder fluidisation inside a simplified, optically transparent DPI metering chamber geometry. We describe a system based on digital image analysis of high-speed video recordings of the transient powder-airflow interactions. Using diffuse backlighting we have generated black-on-white images of the interaction of frictional, cohesionless particles with an air jet flow. Image-processing techniques were subsequently applied to determine several aspects of the time-dependent properties that describe the development of the bed during the aeration of the powder. The paper concludes by pointing out how the proposed method could be used to improve understanding of the limitations associated with current DPI metering chamber configurations and help forward design of improved DPIs.
An Endoscopic Grasper Tool With Integrated Tactile Sensors for Use in Minimally Invasive Surgery
Authors: Dargahi Javad , Najarian Siamak
Published: November 2008

In this paper, we report on the design, testing, fabrication, and modeling of a semiconductor-based microstrain gauge endoscopic tactile sensor. This sensor is capable of measuring both the magnitude and the position of an applied load on a commercial endoscopic grasper tool. It consists of two microstrain gauge sensors, placed on the prototype endoscopic grasper. A light emitting diode device is used to visually see the intensity of the applied force. In total, 20 different force magnitudes for 7 different locations on the endoscopic grasper are tested experimentally. The range of force magnitude changes in the domain of 0.5 N to 10 N. The in-house electrical amplification system for the microstrain gauges is also designed, fabricated, and tested. The sensor is insulated and can operate safely in wet environments. The designed sensor assembly exhibits high force sensitivity, good linearity, and large dynamic range. A three-dimensional finite element modeling (FEM) is employed to predict the behavior of the designed system. Based on FEM results, there is a good agreement between these data the results obtained experimentally.
The Need for a Condition Monitoring Database Management System
Authors: El-Shtewi Houssein F. , Li Yuhua , Gu Fengshou , Ball Andrew D.
Published: November 2008

This paper describes the growing need for a novel approach to a Condition Monitoring Database Management System (CMDBMS). Through the study of a condition monitoring case and the examination of commonly used maintenance management systems, the needs of this system have been identified. From the case study, it has been found that to obtain maintenance information a CMDBMS requires capabilities including data organization, data processing and data collection information. However, existing systems, which are used in the maintenance community only have some of the capabilities and hence provide limited assistance for maintenance activity. Therefore, a novel approach to a CMDBMS has been suggested to meet the needs of condition monitoring data management.
Modal Analysis Based Structural Damage Localisation Under Varying Operating Conditions
Authors: Parloo Eli , Vanlanduit Steve , Verboven Peter , Guillaume Patrick
Published: November 2008

A variation in the operating condition of a structural health monitored system can have a very bad influence on the performance of modal based techniques. The modal parameter changes caused by, for instance, uncontrolled temperature fluctuations can easily mask small changes in these parameters that are caused by structural defects. In this contribution, a method is proposed for compensating the effect of unknown global variations in the natural frequencies of a test structure: e.g. uniform coatings and/or uniform (environmental) temperature changes. Unlike other methods, the compensated results are used for localising as well as detecting structural damage.
Design and Implementation of a Control System for a Flexible Planar Manipulator
Authors: Biason Adriano , Gasparetto Alessandro , Giovagnoni Marco , Trevisani Alberto , Zanotto Vanni
Published: November 2008

The need for light and flexible robots is greatly increasing in the industrial engineering environment. This paper presents the design and the implementation of a PID controller for a flexible planar manipulator. The controller synthesis and tuning is based on a very accurate dynamic model of the system and is applied to a significant test case, namely a five-bar closed-chain mechanism, driven by two electric motors. The chosen PID controller is described, and the experimental results are presented and discussed. The approach followed proves the practical usefulness of the dynamic model proposed even when applied to a complex test case.
A Combined Genetic Algorithm-Fuzzy Logic Method (GA-FL) to Design a 6 Bars Planar Mechanism
Authors: Laribi M. A. , Romdhane L. , Mlika A. , Zeghloul S.
Published: November 2008

This work deals with solution methods of optimal synthesis of planar mechanisms. A searching procedure presents a combined genetic algorithm–fuzzy logic method to solve the problem of path generation in mechanism synthesis. Previous works, dealing with the same problem and using the genetic algorithm method, suffered from the lack of precision, especially for large domain problems. The proposed method is made of a classical genetic algorithm coupled with a fuzzy logic controller (GA-FL). This controller monitors the variation of the design variables during the first run of the genetic algorithm and modifies the initial bounding intervals to restart a second round of the genetic algorithm. For both of these runs, we limited the number of generations to roughly half of the number found in the literature, without reducing the accuracy of the final solution. Compared to previous works on the same problem, our method proved to be more efficient in finding the optimal mechanism. The effectiveness of the proposed method has been demonstrated on a six bars synthesis example.
Path Guidance and Attitude Control of a Vectored Thruster AUV
Authors: Cavallo Emanuele , Michelini Rinaldo C. , Filaretov Vladimir F. , Ukymets Dimitri A.
Published: November 2008

The study deals with developing small and cheap autonomous underwater vehicles, AUV, entrusted of extended manoeuvrability for surveying and docking missions, with accurate of path tracking and attitude keeping, capable of travelling at low speed, down to proper depth, to carry out the given tasks with proper autonomy and without relevant impact on the surroundings. The to day available AUVs, generally, make use of several propellers, distributed around the body, to achieve the desired mobility with full attitude control. The solution requires the closure of multiple loops between sensors and actuators, highly cross-coupled and dependent on dynamics non-linearity and marine surroundings disturbances. The prospected solution considers a properly shaped vehicle, to grant minimal drag for lowering power consumption. A single rear propeller has in charge propulsion and manoeuvring. The propeller can be oriented around two axes, say, pitch (for heaving) and yaw (for veering); the screw (hydrodynamic) torque is balanced by variable tilt fins, either, by counter-rotating vanes. A three degrees of freedom parallel kinematics robotic wrist provides joint path-and-attitude selection and twist compensation, by driving the propeller assembly through three independent actuations. The build-up makes use of a duct-restricted propeller, with externally driven pitch-and-yaw bending and twist to counteract the screw torque by reactive fins, either, continuous rotation. The balancing wile assures best performance, in the reactive mode, during steady surveying missions, while the local hover or docking is better accomplished by active counter-rotation. The paper discusses the basic design steps by example manoeuvres carried with virtual checks on a digital mock-up.
Neural Network Modelling Applied for Model-Based Fault Detection
Authors: Shi Zhanqun , Fan Yibo , Gu Fengshou , Ali Abdul-Hannan , Ball Andrew
Published: November 2008

This paper aims to combine neural network modelling with model-based fault detection. An accurate and robust model is critical in model-based fault detection. However, the development of such a model is the most difficult task especially when a non-linear system is involved. The problem comes not only from the lack of concerned information about model parameters, but also from the inevitable linearization. In order to solve this problem, neural networks are introduced in this paper. Instead of using conventional neural network modelling, the neural network is only used to approximate the non-linear part of the system, leaving the linear part to be represented by a mathematical model. This new scheme of integration between neural network and mathematical model (NNMM) allows the compensation of the error from conventional modelling methods. Simultaneously, it keeps the residual signatures physically interpretable.
Optimized Cooling System for PEM Fuel Cell Stack Based on Entropy Generation Minimization
Authors: Saidi M. H. , Mozafari A. A. , Sharifian L.
Published: November 2008

Cell temperature in fuel cells is an important parameter which highly affects fuel cell stack efficiency. A suitable cooling system should satisfy an acceptable temperature range. In this research a relevant cooling system for a specified PEM fuel cell stack has been proposed complying with the criteria and cooling requirements of the fuel cell. The effect of various parameters on the entropy generation and temperature distribution in the cooling plates are surveyed. The number of cooling plates, the number of channels in each cooling plate and the channel width is determined. Two flow regimes namely laminar and turbulent flows of the cooling fluid in channels are analyzed and a design methodology is proposed for each regime of flow. The proposed design methodology in turbulent flow will be optimized while the work destruction is minimized. However, the proposed design in laminar flow is not the optimum one but the most efficient between different configurations. The comparison between these two proposed designs show that the turbulent flow has a lower entropy generation. In addition to entropy generation minimization, to have a desirable optimum cooling system, other parameters such as the size of the cooling plates and temperature uniformity inside cooling system have been investigated in this analysis.
ANFIS Active Vibration Control of Flexible Beam Structures
Authors: Mohd. Hashim S. Z. , Tokhi M. O.
Published: November 2008

This paper presents the development of an adaptive neuro-fuzzy inference system (ANFIS) controller for vibration control of flexible beam structures. ANFIS constructs a fuzzy inference system (FIS) whose membership function parameters are tuned (adjusted) using the backpropagation algorithm and least squares method. This allows the fuzzy system to learn from the data modeling. To allow the non-linear dynamics of the system be incorporated within the design, a pseudo random binary signal (PRBS) covering the dynamic range of interest of the system is used to train the ANFIS model, which gives good output prediction. Simulation results showing the performance of the developed control scheme in vibration suppression of flexible beam structures, with changes in the excitation signal, are presented and discussed.
Remote Model-Based Condition Monitoring Applied to a Mechatronic Control System
Authors: Shi Zhanqun , Gu Fengshou , Pietruszkiewicz Robert , Ball Andrew
Published: November 2008

The integration of control and monitoring systems often restricts more advanced monitoring algorithms to be used because of the limitation of hardware resource. This paper proposed a remote on-line model-based monitoring scheme, in which the monitoring and the control are implemented in different stations but synchronised through a Fieldbus network. Moreover, the synchronism period is adjustable so that it allows implementation of various monitoring tasks of different monitoring accuracy. This approach is demonstrated by applying it to a mechatronic control system. The implementation details are presented and the benefits of the approach are highlighted.
Dynamic Buckling Analysis of Axi-Symmetric Shells
Authors: Gholipour Yaghob
Published: November 2008

In the field of dynamic buckling analysis of shell structures, the effect of vibration on buckling load and the effect of axial loads on vibration are very interesting phenomena. In this work the finite element method has been applied for dynamic buckling analysis of axi-symmetric shell. The degenerated axi-symmetric shell element and subspace iteration technique has been used to carry out the analysis. The stiffness matrix is stored in band form to have efficient memory management and the 3 × 3 gauss quadrature has been used for calculation of element stiffness matrix and consistent load vector. An attempt is made to study the effect of static in-plane edge loads on the fundamental frequency of axi-symmetric shells. The effect of vibration at a prescribed frequency on the buckling behavior of shell is also investigated. From the limited analysis carried out, it is found that the presence of static in-plane edge loads considerably affects the natural frequency and hence necessitates the evaluation of appropriate natural frequency and mode shapes for use in realistically carrying out the dynamic response analysis of structures subjected to forced vibration by mode superposition method.
A Survey on Condition Monitoring Systems in Industry
Authors: Higgs Philip A. , Parkin Rob , Jackson Mike , Al-Habaibeh Amin , Zorriassatine Farbod , Coy Jo
Published: November 2008

Advances in networking technologies are opening integration opportunities for Condition Based Monitoring (CBM) systems, presenting further possibilities for increasing CBM system functionality. This paper presents the results of a CBM Survey designed to determine present applications of CBM system within industry. Understanding how industry applies practices such as CBM in the work place offers valuable research results for CBM system providers, consultants and business users alike. The survey acts as a CBM application indicator for 2004. It targets 6 key areas: 1) Respondents’ company information, 2) The type of CBM technique/s applied by the respondents’ company, 3) Incentives that led the respondents’ company to implement their CBM system, 4) Technological and integration issues associated with respondents’ application of CBM, 5) Implementation issues associated with the respondents’ CBM system, and 6) Reliability and consequential maintenance awareness issues following implementation. An international response shows CBM to be a globally accepted maintenance practice. In addition to the survey results, the paper discusses developments in remote CBM systems using the Internet, with particular regard for developing suitable user interface designs.
A Review of the Condition Monitoring of Mechanical Seals
Authors: Fan Yibo Edward , Gu Fengshou , Ball Andrew
Published: November 2008

Mechanical seals are the most widely used types of dynamic seal. Although its reliability has been improved by employing advanced technologies in design and manufacture in the last 40 years, premature failures of mechanical seals are still very common. The review of the failure of mechanical seal shows that the failure follows early and random distribution. Condition monitoring is then needed to predict the failures at their early stage to prevent additional loses. Possible methods for condition monitoring of mechanical seal are surveyed which include operation parameter monitoring, acoustic emission, ultrasonic wave, dynamic behaviour measurement, and air-born acoustic noise.
Hybrid Learning Control With Input Shaping for Input Tracking and Vibration Suppression of a Flexible Manipulator
Authors: Md Zain M. Z. , Tokhi M. O. , Mohamed Z.
Published: November 2008

The objective of the work reported in this paper is to investigate the development of hybrid iterative learning control with input shaping for input tracking and end-point vibration suppression of a flexible manipulator. The dynamic model of the system is derived using the finite element method. Initially, a collocated proportional-derivative (PD) controller utilizing hub-angle and hub-velocity feedback is developed for control of rigid-body motion of the system. This is then extended to incorporate iterative learning control and a feedforward controller based on input shaping techniques for control of vibration (flexible motion) of the system. Simulation results of the response of the manipulator with the controllers are presented in the time and frequency domains. The performance of the hybrid learning control with input shaping scheme is assessed in terms of input tracking and level of vibration reduction. The effectives of the control schemes in handling various payloads are also studied.