bluuebunny/crossref_metadata_2025 huggingface dataset:
A Component-Based Human Machine Interface System for Automotive Manufacturing Machines
Authors: Mellor Edward W. , Harrison R. , West Andy A.
Published: November 2008

This paper presents a novel approach for the configuration and runtime usage of user interfaces or Human Machine Interface (HMI) systems based on research being conducted at the Distributed Systems Group, Loughborough University. This research is investigating the replacement of conventional PLC/PC systems with a Component Based control approach suitable for the automotive engine manufacturing industry. HMI (operator interface) systems for production machines must effectively fully support an increasingly complex machine lifecycle involving engineering input from many globally distributed engineering partners. Current HMI Systems are standalone offering poor connectivity and requiring highly specialist skilled personnel to develop and maintain the systems. The goal of Component Based (C-B) systems is to compose machines from modular units with embedded intelligence. The “intelligence” has different functional domains, e.g. sequencing and interlocking logic, 3D virtual modeling, visualization, diagnostics, service and operating interfaces, etc. The underlying framework of the C-B paradigm is a common model system repository where all components are stored. This facilitates visibility of the system common model to all the globally distributed engineering partners involved in a given project. Within the C-B framework, HMI systems are composed from instances of reusable software templates that are targeted at specific user types. User targeted operator interfaces offer a common look and feel that improves usability. The machine’s configuration is achieved by populating a series of HMI templates to produce a complete machine HMI system. A thin-client architecture is used based on server/ client internet technologies that allow the machine HMI to be executed on any internet enabled computer using a standard web browser. It is possible to drive both the real machine and a simulated 3D virtual machine model via the HMI, enabling engineers to be trained on the operation of the HMI prior to the real machine being completed.
High-Pressure Gas-Oil Two-Phase Flow Visualisation Using Electrical Capacitance Tomography
Authors: Gamio Carlos , Castro Juan , Garcia-Nocetti Fabian , Aguilar Luis , Rivera Leonardo , Balleza Humberto E.
Published: November 2008

Electrical capacitance tomography (ECT) was used to image various two-phase gas-oil flows in a 3-inch pressurized test loop. ECT is a novel non-invasive technique for imaging mixtures of electrically non-conducting substances. One of its most promising applications is the visualization of gas-oil flows. This work presents a series imaging experiments using a pressure-resistant ECT sensor. Varying the oil and gas flow rates, different flow regimes were established in the test loop. ECT images were obtained for each case and compared with (a) the flow observed through a transparent section in the loop and (b) the prediction of the Taitel-Duckler flow map. The results confirm the suitability of ECT for imaging gas-oil flows.
Measurement Signal Effects on the Normal-Incidence Absorption Coefficient
Authors: Tsuei Kuang-Yih , Jiang Wen-Wang , Kuo Shu-Fen
Published: November 2008

This paper will demonstrate the signal effects on the normal-incidence absorption coefficient. The test method covers two microphones located in impedance tube to measure this coefficient. It should analyze the measurement procedure and formulae theoretically, furthermore to propose the coherence function as the criteria for measurement results. Experimentally, different signals, generated by a sound source, input to the loudspeaker in impedance tube to produce the plane wave and two microphones can measure the sound pressures. Through different time weightings and average times on the two microphone signals, and after analyzing results of the frequency response, the coherence function and the normal-incidence absorption coefficient, the coherence function is a major factor to check the normal-incidence absorption coefficient reliable, even the test system stable or not.
Time Optimal Transfer Function of a Mechanism
Authors: Goun A. A. , Sliva O. K. , Murzin Vyacheslav
Published: November 2008

A variety of optimization problems in theoretical mechanics are related to the problem of finding the quickest operating mechanism among all possible mechanisms. It can be formulated in the following way. Let us consider a mechanical system with one degree of freedom consisting of leading and lagging links with masses M1 and M2 respectively. Source of mechanical energy is attached to the leading link and its potential energy is known as a function of the position of the leading link. Positions of the leading - x and lagging links - y are related through the position function. Now the optimization problem can be formulated in the following way: find the position function such that the lagging link is transferred from initial position to the final position in the shortest time. We have obtained an analytic solution to this problem using variational calculus methods in the case then dissipative forces acting on the system can be neglected. We have shown that this problem is analogous to the classical brachistochtone problem. The qualitative feature of this result is that the optical mechanical system tends to accelerate the leading link first in order to maximize the power being extracted from the mechanical energy source. Analytical solution is applied for the optimization of the fast acting electric switch design. Leading link load and operating time reductions with the use of the optimal transfer function is demonstrated. This approach can be generalized for a variety of mechanisms where the operating time is critical.
Weld Contour Measurement of Fillet Weld by Reverse Engineering Technique
Authors: Chang Chia-Lung , Chen Yen-Hung
Published: November 2008

The external geometry of the fillet weld plays an important role in the strength of the weld. Two factors that influence the external geometry of the fillet weld are weld size and profile. The fillet weld must be made to the weld size and profile as specified in the welding code. Unacceptable profile not only is a defect of the weld but also produces stress risers that reduce the fatigue strength. Insufficient weld that reduces the cross sectional area of weld throat may cause premature failure. Visual inspection and weld gages are two most widely used simple tools to provide a rapid assessment of the external geometry of the fillet weld. In this study, the reverse engineering technique, which a laser scanning system integrates with CAD software, is used to provide a more accurate measurement of the weld contour. The weld samples were made of low-carbon steel plates with T-joint using CO2 welding. The weld volume, weld size and convexity were determined from CAD model to evaluate the weld quality. The reverse engineering technique provides a more accurate and efficient method to inspect the external geometry of fillet weld.
Numerical Simulation of Joule Heating Effect on Electroosmotic Flow and Electrokinetic Mass Transport in Microchannels
Authors: Tang Gongyue , Yang Chun , Chai Cheekiong , Gong Haiqing
Published: November 2008

This study presents a numerical simulation of Joule heating effect on electroosmotic flow and mass species transport in microchannels, which has direct applications in the capillary electrophoresis based Biochip technology. The proposed model includes the Poisson-Boltzmann equation, the modified Navier-Stokes equations, the conjugate energy equation, and the mass species transport equation. The numerical predictions show that the time development for both the electroosmotic flow field and the Joule heating induced temperature field are less than 1 second. The Joule heating induced temperature field is strongly dependent on channel size, electrolyte concentration, and applied electric field strength. The simulations reveal that the presence of Joule heating can result in significantly different characteristics of the electroosmotic flow and electrokinetic mass transport in microchannels.
Non-Intrusive Measurement of Volume and Mass Using Electrical Capacitance Tomography
Authors: Hunt Andrew , Pendleton John , Byars Malcolm
Published: November 2008

Electrical capacitance tomography (ECT) has been used for some years to measure the concentration distribution within multiphase flows and processes. ECT is a relatively low resolution measurement, but it has many advantages, including being non-intrusive and fast. Recent developments of twin-plane systems have enabled measurements to be made of velocity as well as concentration. We have developed techniques to establish from these measurements the volume, mass and velocity of flow structures in two-component flows, and in particular the mass and velocity of large individual particles and groups of particles in solids/gas flow systems. Results are presented in the paper for simple gravity-drop flows of partly-filled plastic spheres, plastic beads, and also for the conveying of granular material in a pilot plant. We show that resolution of mass to within a few grams is possible on objects of individual mass of between 2g and 35g. We also show measurements of flow structure volumes in vertical solids conveying pipes of approximately 50mm diameter. General comparisons are made with high-speed video photography of some of the flows, and the in the case of gravity-drop flows the accuracy of the mass measurement is established using weighing.
A Corotational Elastoplastic Formulation With Subloading Surface Model for Hardening Materials
Authors: Saidi Ali Reza , Hashiguchi Koichi
Published: November 2008

In this paper a corotational constitutive model for the large elastoplastic deformation of hardening materials using subloading surface model is formulated. This formulation is obtained by refining the large deformation theory of Naghdabadi and Saidi (2002) adopting the corotational logarithmic (Hencky) strain rate tensor and incorporating it into the subloading surface model of Hashiguchi (1980, 2003) falling within the framework of the unconventional plasticity. As an application of the proposed constitutive model, the large Elastoplastic deformation of simple shear example has been solved and the results have been compared with classical elasto-plastic model using the Hencky strain tensor. Also the effect of the choice of corotational rates on stress components has been studied.
Identification and Model Updating of a Non-Stationary Vibrating System
Authors: Dimitriadis G. , Fassois S. D. , Poulimenos A. G. , Shi D.
Published: November 2008

Non-stationary systems, which are commonly encountered in many fields of science, are characterized by time-varying features and require time-frequency methods for their analysis. This study considers the problem of identification and model updating of a non-stationary vibrating system. In particular, a number of identification methods and a model updating procedure are evaluated and compared through application to a time-varying “bridge-like” laboratory structure. The identification approaches include Frequency Response Function based parameter estimation techniques, Subspace Identification and Functional Series modelling. All methods are applied to both output-only and input-out-put data. Model updating is based upon a theoretical model of the structure obtained using a Rayleigh-Ritz methodology, which is updated to account for time-dependence and nonlinearity via the identification results. Interesting comparisons, among both identification and model updating results, are performed. The results of the study demonstrate high modelling accuracy, illustrating the effectiveness of model updating techniques in non-stationary vibration modelling.
Robot Trajectory Planning Using Rational Frenet-Serret Curves
Authors: Ravani Reza , Meghdari Ali
Published: November 2008

The aim of this paper is to demonstrate that the techniques of Computer Aided Geometric Design such as spatial rational curves and surfaces could be applied to Kinematics, Computer Animation and Robotics. For this purpose we represent a method which utilizes a special class of rational curves called Rational Frenet-Serret (RF) [8] curves for robot trajectory planning. RF curves distinguished by the property that the motion of their Frenet-Serret frame is rational. We describe an algorithm for interpolation of positions by a rational Frenet-Serret motion. Further more we provide an analysis on spatial frames (Frenet-Serret frame and Rotation Minimizing frame) for smooth robot arm motion and investigate their applications in sweep surface modeling.
A Novel Optimization Algorithm for the Estimation of ARMAX Models
Authors: Koulocheris Dimitris , Dertimanis Vasilis , Spentzas Constantinos
Published: November 2008

This paper introduces a hybrid optimization algorithm, followed by a corresponding estimation technique, for the estimation of ARMAX models. The hybrid algorithm consists of a stochastic component and a deterministic counterpart and aims at combining high convergence rate together with reliability in the search for global optimum. The estimation procedure is slit in two phases, due to the mixed linear-nonlinear relationship between the residuals and the parameter vector, and results in stable and invertible models. The proposed methodology is implemented in the estimation of a half-car suspension model of a road vehicle, using noise-corrupted observations, and the results yield very stable performance of the hybrid algorithm, reduced computational cost, in comparison to conventional stochastic optimization algorithms, and ability to describe satisfactory system’s dynamics.
Optimum Positioning of Tank Mountings in a Fixed Tank Vehicle
Authors: Koulocheris Dimitris , Dertimanis Vasilis , Spentzas Constantinos
Published: November 2008

This paper aims at optimizing some critical characteristics of a fixed-tank biaxial vehicle, with respect to the lateral performance of the installed tank. For the description of the fixed-tank vehicle, a linear half car model with six degrees of freedom is implemented, subject to many types of road irregularities. The relative position of the tank mountings, with respect to the vehicle frame, as well as their corresponding stiffness and damping characteristics are optimized, such that the maximum values of vertical and rotational acceleration of the tank are minimized, under the geometrical constraints of the vehicle. For the optimization tasks, the BFGS quasi-Newton and the (μ+λ)-Evolution Strategy methods have been implemented. The former outperforms conventional Newton’s methods, due to the secant approximation of the Hessian, while the latter has been shown to perform better in many engineering applications, compared to other categories of EA.
Improvement of the Assemblability of Products in the Single- and Small Batch Assembly
Authors: Wuenscher Thomas , Feldmann Dierk Goetz
Published: November 2008

In this paper we present a methodology which is being developed at the Institute for Mechanical Engineering Design. The aim of this methodology is to improve the assemblability of existing and future products. The key characteristic is that these improvements are based on the experience of the employees, who are involved in the assembly. Not only information about failures is used to improve the products but also the improvement potential within the current assembly system and products. This methodology is especially being developed for the manual single- and small batch assembly of big mechanical systems, which are designed with 3D-CAD. The methodology is based on current research activities in the field of design for assembly and a case study in a huge company, with the above mentioned constraints.
Development of Automated Alignment Techniques for Coupling of Fiber Optic Components
Authors: Hsieh Min-Fu , Lo Kuang-Yao , Sun Chia-Yang , Tsai Mi-Ching
Published: November 2008

This paper presents the automated alignment techniques for coupling of fiber optic components (e.g., fiber-to-fiber). Common alignment devices are often operated manually, which requires well-trained operators working and tuning on submicron scale stages and is hence time-consuming and costly. Recently there have been more and more automated couplers brought onto the market. However, most of them employ fixed paths/patterns for light detection until optimal alignment is reached, which can further be improved for shorter time spent and better coupling efficiency. Therefore, four intelligent algorithms are presented and compared in this paper. Simulation and experimental studies are both conducted, and the results show that some algorithms developed are capable of accomplishing fast alignment and high optical coupling efficiency.
Compressor Driven Metal Hydride Cooling Systems: Simulation and System Dynamics
Authors: Mazumdar S. , Bhattacharyya S. , Gopal M. Ram
Published: November 2008

A comprehensive mathematical model to study the performance parameters of compressor driven metal hydride systems is presented. The dynamics of the compressor and the conditioned space has been taken into account. The model also accommodates the transient nature of the external fins. The effect of size and geometry of the heat exchanger has been given due importance while calculating the external heat transfer coefficient of the metal hydride reactors. A 1 TR system is designed using MmNi4.5Al0.5 as the metal hydride and its operating characteristics are studied. The average COP and SP power obtained are around 3.1 and 125 W/kg respectively. It is seen that compressor remains idle for 30% of the time during stable cycling. The problem of large initial compressor loads during cut-in as is encountered in vapour compression systems are not faced in such systems. Moreover the compressor is not overloaded during sudden load changes.
A Systems Approach to Identification of Best Manufacturing Practices
Authors: Dani Shilpa S. , Harding J. A. , Champion Donna , Shahbaz M.
Published: November 2008

If a company is to maintain its success in any market, it is necessary that its processes are among the best available. A best practice is a practice “that will lead to the superior performance of the company”. However, it should be noted that “best” is a moving target in today’s world, and it is also situation specific. Thus, it is important to identify the best practices in a particular organisation but at the same time it is vital to have knowledge of the environment in which the practice is “best”. Improvement in business and manufacturing practices should affect not only the processes themselves, but also the knowledge needed for the process, and the configuration of this knowledge alongside the process. This paper proposes a data mining based methodology to identify the effective process for manufacturing design. The methodology proposes an approach where the effective, good or best manufacturing practices are identified and the knowledge about these practices is stored for future reuse.
Design, Modeling and Kinematics Analysis of a Novel Serial/Parallel Pole Climbing and Manipulating Robot
Authors: Vossoughi G. R. , Bagheri S. , Tavakoli M. , Zakerzadeh M. R. , Hosseinzadeh M.
Published: November 2008

This paper introduces a multi-task 4 DOF pole climbing/manipulating robotic mechanism. A hybrid serial/parallel mechanism, providing 2 translations and 2 rotations, have been designed as the main part of the mechanism. This robotic mechanism can travel along tubular structures with bends, branches and step changes in cross section. It is also able to perform manipulation, repair and maintenance tasks after reaching the target point on the structure. After introducing the mechanism, a kinematics model and the forward and inverse kinematics as well as the workspace analysis of the mechanism are presented.
Capacitively and Inductively Coupled Plasma for MEMS Applications
Authors: Lozano-Parada Jaime H. , Zimmerman William B. J.
Published: November 2008

We consider the development of capacitively and inductively coupled microplasma reactors for detection, control and chemical transformation in microelectromechanical (mems) applications. Current progress in fabrication techniques, including hot embossing, soft and laser lithography is reviewed. Numerical simulations of the interaction of electromagnetic fields with plasma flows in which the plasma flow is at right angles with the electric and magnetic field are analyzed. Two cases in which the electromagnetic fields induce lorentz forces that control the flow are presented. In the first case, the lorentz forces act along the flow direction and produce and increase in the axial pressure that accelerates the flow (micropump configuration). In the second case, the lorentz forces act against the flow by causing a drop in the axial pressure that slows down the flow (microbrake configuration).
Modelling Transport Limited Heterogeneous Chemistry in Microchannel Reactors
Authors: Zimmerman William B.
Published: November 2008

Enchancing radial mixing in microchannel processing of two phase flows for is important so that this feature can be exploited to simplify the design of heterogeneous reaction schemes in microchannel processing. The asymptotic analysis here extends the concept of the Thiele modulus to be the controlling variable in non-uniform systems. We argue that a generalization of a Thiele modulus is the ratio of the time scale for the limiting transport step to the time scale for surface reaction. If the intrinsic kinetics are fast and the reaction nearly irreversible, the latter is actually controlled by mass transfer to the reacting phase. Our analysis methodology naturally identifies the Thiele moduli and reduces the order of the system so that analytic, closed form estimates of the reaction dynamics are found. For parametric optimization, such a form is a good guide. The applicability of this general methodology is argued for microchannel processing and supported by several published studies and experiments.
Sliding Mode Control of Electromagnetic System Based on Fuzzy Clustering Estimation: An Experimental Study
Authors: Alasti Aria , Salarieh Hassan , Shabani Rasool
Published: November 2008

Using the combination of fuzzy clustering estimation and sliding mode control, a technique for controlling the magnetic levitation (ML) systems is introduced. This technique is applied to an experimental setup of an ML system for investigating the method derived. The system considered, is a symmetric rotor supported by a cantilever load cell beam and excited by only one electromagnet of a 4-pole magnetic bearing setup. After demonstrating the experimental setup instruction and the specifications of its parts, the clustering, and the sliding mode control methods are explained briefly, then the quality of implementing the techniques to the setup is described step by step. Finally, the results of exercising this method to the setup are illustrated, and they show the good performance of this approach for tracking the desired paths.
Mathematical Modelling and Design and of MR Dampers
Authors: Chooi Weng W. , Oyadiji S. Olutunde
Published: November 2008

Most magnetorheological (MR) fluid devices are fixed-pole valve mode devices where the fluid flows through a magnetically active valve. Controlling the strength of the magnetic field inside the valve allows the rheological properties of the MR fluid to be varied. Upon the application of a magnetic field, MR fluids develop a yield stress, which must be overcome before any flow is possible. This behavior can be represented mathematically by models of fluid with a yield stress like the Bingham plastic model. MR dampers have utilized this property of the MR fluids to provide controllable, semi-active vibration control. The most effective and widely used configuration of MR dampers incorporates an annular gap through which the MR fluid is force to flow. This paper presents a solution for annulus flows, derived from fundamental equations of fluid mechanics, of any general model of fluid with a yield stress. An example of the application of the general analytical expressions using the Herschel-Buckley model is given, and the limitations of the parallel plate approximation is illustrated for configurations whereby the size of the annular gap relative to the mean radius is large. Finally, the flow solution is incorporated into the mathematical model of an MR damper designed at the University of Manchester, and simulation results incorporating the effects of compressibility in the modeling procedure are presented. It was shown that this model can describe the major characteristics of such a device — nonlinear, asymmetric and hysteretic behaviors — successfully.
Aeroelastic Stability of a Transport Aircraft With Wing Mounted Store Suspension: Part II — Flight Test
Authors: Kayran Altan
Published: November 2008

This study outlines the work performed for the flight test verification of the aeroelastic stability of a transport aircraft modified with the installation of an external store to the outer wing. The purpose of the flight test phase was to demonstrate that the aircraft with wing mounted external store suspension was free from flutter within the flight envelope up to the dive speed of the aircraft. Based on the flutter analysis results of the previous study, the most critical two mass configurations were selected for the flutter flight test. The impact of sound flutter analyses on the reduction of the number of flights, and the selection criteria of the flight test configurations of the aircraft was highlighted. After the final evaluation of the flutter analysis results, a six sorty of flight test was planned to be executed with an instrumented aircraft for flutter testing of the modified aircraft for two different mass and CG configurations, and envelope expansion is achieved up to the dive speed of the basic aircraft. Analysis of the damping data of the flight test phase indicate that overall damping of the wing vibration modes stay above the minimum 3% aerodynamic plus structural damping, required by the flutter regulation MIL-A-8870C, for the wing structure modes up to about 10 Hz which is a typical frequency range that can be excited by control surface kicks. The lowest damping values were identified to be associated with the external store-wing structural interface and improvement recommendations for the store-wing interface were given.
Semi-Closed CCGT Cycle With High Temperature Reactants Combustion
Authors: Camporeale S. M. , Casalini F. , Saponaro A.
Published: November 2008

In the last years many research studies have been focused on the features of MILD combustion that is a stable form of combustion, obtained with high temperature reactants and high exhaust gas recirculation and characterized by low flame temperature and, consequently, low Nox emissions. This form of combustion is also characterized by low light emissions (for this reason it is also called “flameless” combustion) and a large range of stable operation. MILD combustion has been already applied in industrial furnaces where ceramic regenerators provide to raise the temperature of the entering diluted air, the main advantages being high efficiency and low emissions. The introduction of MILD combustion in power plants would allow for increasing the temperature of the entering reactants beyond the self-ignition temperature without increasing the NOx emission. The main goals of this technique are low combustion exergy losses, large range of stable combustion, and low NOx emissions. Some experiments have shown that the flameless conditions can be obtained using diluted reactants, even using heavy fuel oil. Good results in terms of NOx emissions and soot formation have been obtained for heavy oil combustion in a 10% oxygen concentration of reactants and combustion chamber inlet temperature of about 900K. In order to meet these conditions, a semiclosed CCGT cycle with high recirculation ratio, suitable for the use of heavy fuel oil, is proposed here, assuming state-of-the-art technologies for gas turbine and steam plant and steam cooling of the turbine blades. The thermodynamic analysis shows that the overall plant efficiency of the new scheme is close to 60% that is about the efficiency that can be obtained in modern CCGT power plant fuelling natural gas.
Performance Evaluation of the Optimal Control of a Gantry Crane
Authors: Wang Zhonghua , Surgenor Brian
Published: November 2008

For a gantry crane, optimal control of the crane motion requires that the speed of the cart be maximized, and the swing of the hanging payload be minimized. The problem lends itself naturally to optimal linear quadratic (LQ) controllers. This paper examines the performance of four different approaches to the design of an LQ controller, including two optimization approaches as based on: 1) minimal energy of cart and payload and 2) integrated absolute error of payload angle. Both simulation and experimental results are presented. A demonstration is also given as to how the results taken from laboratory scale gantry crane experiments must be treated with caution. Laboratory based studies have generally worked with systems where the moving cart mass is much larger than the suspended payload mass. In the case of industrial scale gantry cranes, the reverse can be true. This has implications with respective to the robustness of the controller. In the case where the cart mass is much greater than the payload mass, the effect of the payload on the cart is correctly neglected. However, there are stability implications if this is not the case. The implications with respect to the tuning of LQ controllers for this application are discussed.
Analysis of the Damping of Beams With Discontinuous Viscoelastic Damping Layer Using Integral Finite Elements
Authors: Liang T. , Chen Qian , Oyadiji S. Olutunde , Leung Andrew
Published: November 2008

The damping performance of discontinuous constrained viscoelastic damping layer using Integral Finite Elements (IFE) are investigated in this paper. The IFE involves the dynamic analysis of Elastic-Viscoelastic Composite (EVC) structures with frequency-dependant material properties. EVC structures, which incorporate constrained viscoelastic damping treatment, are modelled using IFE’s and conventional FE’s together to deal with the discontinuous treatment of the constraint damping layers. This approach dramatically reduces the number of degrees of freedom of the FE model compared with conventional FE models. By using specialised algorithms developed for EVC structural dynamics analysis, IFE makes the estimation of the dynamic properties of the EVC structures an easy task similar to the structural dynamics analysis using conventional finite element method. Using an IFE model and the special algorithms, the damping performance of various designs of viscoelastic damping treatments are investigated at extremely low computational costs compared with the use of current commercial FE software packages. A guideline is introduced based on the results of the damping performance analysis for the structural design of viscoelastic damping treatments.
Heat Transfer in a Rotating Square-Sectioned Channel Fitted With In-Line Ribs
Authors: Lees A. W. , Khamaj J. M. J. , Morris W. D. , Chang S. W.
Published: November 2008

This investigation studies convective heat transfer in a square-sectioned duct that rotates about an axis perpendicular to the central axis of the duct. The leading and trailing sides of the duct are fitted with in-line ribs aligned at 45° to the central axis of the duct. The leading and trailing edges are heated and the two remaining sidewalls of the duct are adiabatic. Air is the coolant used and the direction of flow is in the radial outward direction. The duct simulates the flow and heat transfer that occurs in the passages of cooled turbine rotor blades. The presentation of results is in itself a non-trivial task as the heat transfer is a function of three independent parameters. It is shown how the performance of the section may be expressed in terms of a reduced temperature parameter and that this approach offers additional insight as compared to the conventional Nusselt number approach (which may be obtained by a simple transformation. The investigation has produced a range of experimental data to aid the validation of CFD codes designed to predict heat transfer in this class of rotating duct. Additionally empirical correlations for heat transfer on the leading and trailing edges are proposed that uncouple the individual effects of Coriolis forces and centripetal buoyancy.
Regular and Irregular Vibrations of a Non-Ideal Autoparametric System
Authors: Sado Danuta , Kot Maciej
Published: November 2008

This paper studies the regular and irregular vibrations of two degrees of freedom autoparametrical system, when the excitation is made by an electric motor (with unbalanced mass), which works with limited power supply. The investigated system consists of a pendulum of the length l and mass m, and a body of mass M suspended on the flexible element. It was assumed that the damping force acting on the body of mass M and resistive moment acting on the pedulum are non-linear. In this case, the excitation has to be expressed as an equation describing how the energy source supplies the energy to the system. The non-ideal source of power adds one degree of freedom, and then the system has three degrees of freedom. The system has been researched for known characteristic of the energy source (DC motor). The equations of motion have been solved numerically what permit to enrich the investigations and to examine not only small and steady state oscillations but also large-amplitude oscillations in transient states. The influence of motor’s speed on the phenomenon of energy transfer has been researched. Near the internal and external resonance region, except different kind of periodic vibration, the chaotic vibration has been observed. For characterizing an irregular chaotic response bifurcation diagrams and time histories, power spectral densities, Poincare´ maps and maximal exponents of Lyapunov have been constructed.
A Comparison of Homogenization and Direct Techniques for the Treatment of Roughness in Non-Newtonian-Modified Reynolds Equation: Numerical Results
Authors: Kane Malal , Bousaid Benyebka
Published: November 2008

This article is concerned with the simulation of a lubricated contact in severe running conditions considering the fluid as Non-Newtonian of Maxwell type. To overcome some limitations that become apparent at very small film thickness, notably when the roughness is two-dimensional, Jai in 1995 introduced a new technique based on a rigorous homogenization theory in the case of compressible fluid flow. This procedure was mathematically developed by Jai [1] and Buscaglia and Jai [2], and applied to tribological problems by Jai and Bou-Sai¨d [3]. The theoretical developments have been presented and discussed elsewhere [6] of this work and we present here some numerical results obtained from the homogenized technique. The obtained results were discussed and compared with the direct methods of calculation, and seem to us valid for a definitive validation of this method said about homogenization. These results have been compared to the exact solution obtained from a numerical simulation. By direct inspection it is clear that the symmetry predicted by the homogenization method is not present in the exact solution which qualitatively agrees with the homogenized solution.
Nonlinear Vibration and Comfort Analysis of High-Speed Trains Moving Over Railway Bridges
Authors: Kargarnovin M. H. , Younesian D. , Thompson D. J. , Jones C. J. C.
Published: November 2008

The ride comfort of high-speed trains passing over railway bridges is studied in this paper. The effects of some nonlinear parameters in a carriage-track-bridge system are investigated such as the load-stiffening characteristics of the rail-pad and the ballast, rubber elements in the primary and secondary suspensions systems. The influence of the track irregularity and train speed on two comfort indicators, namely Sperling’s comfort index and the maximum acceleration level, are also studied. Timoshenko beam theory is used for modelling the rail and bridge and two layers of parallel damped springs in conjunction with a layer of mass are used to model the rail-pads, sleepers and ballast. A randomly irregular vertical track profile is modelled, characterised by a power spectral density (PSD). The ‘roughness’ is generated for three classes of tracks. Nonlinear Hertz theory is used for modelling the wheel-rail contact.
Development of Advanced Alloying Process Using Micro-EDM Deposition Process
Authors: Ori Ricardo Itiro , Itoigawa Fumihiro , Hayakawa Shinya , Nakamura Takashi , Tanaka Shun-Ichiro
Published: November 2008

The development of an advanced alloying process using Micro-Electrical Discharge Machining Deposition is described in the present paper. The new process uses a micro-sized bimetal tool electrode, which is composed of two halves; each part made of a different metal. The alloying process of the two metals occurs during the deposition process previously proposed by the authors, which can create 3-dimensional micro-sized objects. The quality of alloyed metal was verified using X-ray analysis. In the present experiment the two metals used are YNi-1 (nickel alloy used in TIG welding) and S45C (medium carbon steel). EPMA results of the obtained deposit show that the nickel and iron distribution in the deposit is uniform when the tool electrode spins during the deposition process. Also, it was found that the chemical composition of the main metal in the deposited object is proportional to the cross sectional area in the bi-metal electrode section. Therefore, not only the deposition process takes place but also the chemical composition of the deposit can be simultaneously controlled using this process.
A Finite Element Investigation of a Functional Spine Unit in Conjunction With a Multi-Body Model of the Lumbar Spine for Impact Dynamics
Authors: Esat Volkan , Acar Memis
Published: November 2008

In this study, the finite element (FE) technique was used in conjunction with multi-body modelling to simulate and analyse the dynamic behaviour of the spinal segments in order to investigate the effects of impact loadings on the lumbar spine. A 3-D multi-body model of the lumbar spine and an FE model of the L2-L3 motion segment were developed. Both models were validated for flexion and compression loadings, showing good agreements with a previously validated lumbar spine model. The predictions of the multi-body model under dynamic impact loading conditions such as reaction forces at lumbar motion segments were employed as force boundary conditions for the finite element model of the selected functional spine unit (FSU). Stress and pressure in the intervertebral disc element and the reaction force at a specific vertebral level were presented. This approach has the potential to more realistically simulate the dynamics of spinal segments and whole spine, and study the effects on spinal elements.
Fault Diagnosis of a Centrifugal Pump by Vibration Analysis
Authors: Behzad M. , Bastami A. R. , Maassoumian M.
Published: November 2008

This paper gives the final Solution for vibration reduction in a centrifugal pump. Vibration measurement in different conditions has been carried out in order to find the main reason for excessive vibration of the pumps. In the first stage several parameters including cavitation, not working in the pump design condition and mechanical and electrical faults assumed to be the reason for the pump vibration. By vibration analysis it is found that the major reason for the pump vibration is working in off design conditions. More over dissolved air in the suction fluid can possibly cause two-phase flow leading to the pump vibration. For solving both problems considering pump performance curves it has been suggested to use a speed controller to reduce pump speed.
Structural, Electrical Transport and Magnetoresistive Studies of Pr and Nd Substituted on La2/3Ba1/3MnO3 Perovskite
Authors: Huda A. , Halim S. A. , Lim K. P. , Kabashi K. K. , Elias S. , Sidek A. A. , Hishamuddin Z.
Published: November 2008

Colossal magnetoresistance (CMR), as the name implies, is the phenomenon of dramatic changes in resistance attendant upon application of a magnetic field. The typical CMR material is derived from perovskite manganites with the chemical formula Ln1−xAxMnO3, where Ln is the rare earth (Ln = La, Pr, Nd, Sm) and A is the divalent metal (A = Ca, Ba, Sr). The objective of this paper is to study the effects of the doping Nd and Pr at La site on La-Ba-Mn-O ceramics using solid state reaction. The characteristics and magnetotransport properties of CMR materials are investigated. Polycrystalline (La1−xPrx)0.67Ba0.33MnO3 (x = 0, 1/6, 1/3, 1/2, 2/3, 5/6, 1) and (La1−xPrx)0.67Ba0.33MnO3 (x = 0, 1/6, 1/3, 1/2, 2/3, 5/6, 1), are doped with Pr and Nd site based manganites, calcined at 900°C for 12 hours, pelletized and sintered at 1300°C for 24 hours have been synthesized and investigated. The magnetoresistance (MR) effects are measured using the four point probe technique. The magnetoresistance defined as MR% = (Ro−RH)/RH × 100 was measured at a magnetic field of H ≤ 1T at room temperature. The MR values were increased from 7.9–12.7% and from 7.9–12.3% for doping with Nd (x = 0.17) and Pr (x = 0.33) respectively. The electrical property, Tp was determined by using standard four-point probe resistivity measurement in a temperature range of 20 K to 300 K. The result shows that Pr and Nd dopants shift the value of TP to a lower temperature. In this paper the structural pattern and microstructure property of bulk samples have been investigated via XRD, AFM and SEM. XRD patterns show that these systems are in single-phase with orthorhombic distorted perovskite structures. The rms roughness for the AFM images has obtained for undoped and doped samples. SEM micrographs have shown that undoped samples are observed to be more compact than the doped samples doped due to the existence of pores. The potential of this research is to produce magnetoresistive read head such as read/write heads in computer disc-drives, position sensor, magnetoresistive random access memory (MRAM), biomagnetic sensor and magnetic accelerometers.
Shiraz Solar Power Plant Simulation With Variable Heat Exchanger Performance
Authors: Yaghoubi M. , Azizian K. , Salim Shirazy M. , Kanan P.
Published: November 2008

There are many applications for solar energy from which the solar thermal utilization has received great consideration in the past decades. Among various solar systems, electricity generation is studied and several commercial plants around the world have been installed. In Iran for the first time an investigation is made to find possible applications of solar energy to construct the first 250 kW solar power plant in Shiraz. The plant is designed to generate electricity continuously to be feed to the national grid. For such plant a hybride-Rankine system which contains two cycles of hot oil and steam is selected. The collectors used are parabolic trough 25 m length, 3.4 m wide with 0.88 m focal length. Previous studies of the oil cycle and steam cycle is carried out for certain design conditions. Based on the limitation of construction, it was found that a new simulation is needed to find out the effect of heat exchangers performances on the overall power plant electricity generation rate. Regarding new conditions, the daily and yearly performance of the power plant is determined and results are compared with initial analysis. It is found that the system performances can be improved with new set point design conditions.
Harmonic Analysis to Determine Contact Characteristics of Concentrated Counterformal Contacts
Authors: Teodorescu M. , Rahnejat H. , Gohar R.
Published: November 2008

Contact mechanics of solids of revolution is characterised by their deformation behaviour under load. This is strongly influenced by their geometry and elastic properties. These parameters and the applied load determine the deformation of the contiguous solids, giving rise to contact pressure distribution and sub-surface stress fields, which are necessary to determine fatigue spalling performance. Load bearing surfaces are usually lubricated and the deformation of contiguous solids is often crucial in providing a gap for lubricant film formation and avoidance of asperity interactions on adjacent surfaces and the ensuing wear. Therefore, determination of contact deformation is essential in prediction of contact conditions. This usually requires the solution of the elasticity integral in the form of elliptic functions, which are discretised and achieved through time intensive numerical methods. In lubricated counterformal contacts under high loads and with materials of high elastic moduli, this amounts for the major computing resource requirement within any form of analysis, such as the usual elastohydrodynamic lubrication. The paper shows that any arbitrary pressure distribution over a given contact area may be represented by a harmonic series. The response of the elastic solids to the application of such a harmonic series leads to the evaluation of their contact deformation and sub-surface stress field of also a harmonic nature. The repercussion of this approach is that for a given applied contact load, harmonic analysis may be employed in order to analytically obtain the same predictions as those with much more time consuming numerical analysis. The paper proves the analytical approach by comparison with the case of an infinite line contact, or a one-dimensional contact, for which analytic solution based on the Hertzian theory exists as a classical case. Then, the conformance of the methodology to deviations of surface friction. An advantage of the method over those reported in literature is the simultaneous evaluation of the local contact deformation, as well as the sub-surface stress field. This approach can be extended to the case of rough surfaces, where the harmonic analysis may be used as an approximation.
Computation Platform of SPT Dynamic Characteristics Based on Simulink
Authors: Bao Wen , Wu Xiaoling , Yu Daren , Li Songjing
Published: November 2008

In order to study the low frequency oscillations in a stationary plasma thruster (SPT), a two-dimensional hydrodynamic model of the atom and ion dynamics in an SPT is constructed. At the same time, a new simulation technic using Matlab Simulink is developed to simulate the performance both in space and time dimension. The dynamic simulation of SPT can be made by establishing the dynamic model in Simulink using difference scheme. The scheme is continuous in time and discrete in space. Initializing the parameters of the system, using the stiff arithmetic ode23t with alterative time steps which can accelerate the simulation speed, ultimately the dynamic simulation can be implemented. This process of simulation provides reasonable estimates of the plasma properties and is able to give a clear picture of the low frequency oscillations, qualitatively close to the experimental observations. The simulation results show that the Simulink method is an effective way to simulate the dynamic characteristics of SPT.