bluuebunny/crossref_metadata_2025 huggingface dataset:
A Means of Generating Polyethylene Wear Particles With Desired Size and Shape for Biological Studies of Osteolysis
Authors: Mosleh Mohsen , John Vijay T.
Published: November 2008

Metallic and ceramic counterfaces with artificial surface textures were rubbed against ultra high molecular weight polyethylene (UHMWPE) pins in water-lubricated wear tests and the characteristics of wear debris were studied. Two types of surface textures were utilized. In the first type, an array of wedge shaped features was created on silicon wafers by microfabrication. It was found that the mean size of UHMWPE wear particles strongly depended on the length of the cutting edge of the wedge. For instance, for wedges with a cutting edge length of 55 μm, 15 μm, and 7 μm, it was found that more than 75% of wear particles had a mean length of 30–60 μm, 6–15 μm, and 4–10 μm, respectively. In the second type of textured surfaces, unidirectional patterns were created on the stainless steel discs. These unidirectional patterns consisted of long, parallel edges and grooves and were created by abrading the discs by different grits of sand papers. The length of the majority of unidirectional edges was found to be approximately equal to the dominant size of elongated wear debris. The narrowly distributed wear debris produced in this investigation can be used in the biological study of the effects of size and shape of UHMWPE wear particles in total joint replacements on osteolysis.
Influence of Geometrical Design and Flow Conditions on the Performance of a Microatomiser
Authors: Kong L. X. , Gao W. M. , Evans A. M. , Wang B. , Milne R. W.
Published: November 2008

There are many domestic applications where a small amount of liquid needs to be applied to a defined small area under strict conditions. In some cases, the sprayed materials are toxic and expensive, and excessive spray will lead to potential damage to other materials and harm to human beings. A controlled micro atomizer is designed by integrating an electronic and mechanical system with adjustable capability to tune the volume. The geometrical dimension of the atomizer is optimized to deliver a right amount of liquid to a predetermined area. To study the influence of atomizer design and air velocity, the sprays issuing from different atomizers of various dimensions are investigated theoretically and computationally under various external flow conditions. It is found that a controlled atomizer can be developed by optimizing the nozzle design.
Vibration Control Under Fast Motion of a Golf Swing Robot
Authors: Hoshino Yohei , Kobayashi Yukinori
Published: November 2008

Golf swing robots can be thought as a kind of fast motion manipulators with a flexible link. Robot manipulators are affected strongly from Corioli’s and centrifugal forces in fast motion. It is said that these forces make the performance of feedback control worse. In the same way, ordinal state observers for the linear system cannot estimate the accurate states of those systems. Nonlinear observers estimate the states more accurately than the linear one. However, these cost more computing time and need the exact model of the system. Thus we use a state observer that considers disturbances such as dynamics not modeled, uncertainties and external disturbances to improve the performance of state estimation and the feedback control. The structure of this observer is a combined system of a full-order observer and a type 1 digital servo system. It can estimate not only the state variables of the system accurately but also disturbances in spite of simple algorithm.
Free Convection in an Inclined Square Cavity With Partial Partitions on a Wavy Hot Wall
Authors: Belkadi M. , Azzi A. , Imine O. , Adjlout L. , Aounallah M. , Sabeur-Bendehina A.
Published: November 2008

In the present investigation, a numerical study of the effect of the hot wavy wall with partial partitions on free convection in an inclined square cavity, differentially heated, was undertaken. This problem is solved by using the partial differential equations which are the equation of mass, momentum, and energy. The tests were performed for different inclination angles, partition lenghts and Rayleigh numbers while the Prandtl number was kept constant. A configuration with three undulations and three partitions has been tested. The results obtained show that the hot wall geometry with partions affects the heat transfer rate in the cavity. The mean Nusselt number decreases notably compared with the heat transfer in the square undulated cavity without partitions.
Nonlinear System Identification Using Interpolated Short Time Fourier Transform
Authors: Shi D. F. , Dimitriadis G.
Published: November 2008

For the purpose of constructing the backbone of nonlinear systems, the Interpolated Short Time Fourier Transform (ISTFT) is proposed as a means to improve the estimation accuracy of the instantaneous amplitudes and frequencies of response signals. It is shown that the backbone curves estimated by the ISTFT agree with theoretical backbone curves very well. Additionally, the restoring force can be reconstructed to specify the type of nonlinear stiffness. A curve-fitting technique is introduced to estimate the parameters of nonlinear systems on the basis of theoretical backbone curves. It is shown that a number of typical nonlinear stiffness functions such as cubic, bilinear and pre-compressed springs can be identified accurately using this new method.
Deformation and Fatigue Analysis of Micro Thermal-Electrostatic Actuator Devices
Authors: Hung Jeng-Nan , Lin Meng-Ju , Hwan Chung-Li
Published: November 2008

Micro thermal-electrostatic actuator devices are widely used in MEMS. However, the effect of structure sizes on deformation and fatigue is seldom discussed. In this work, the effect of structure sizes on deformation and fatigue is investigated. In this device, two beams called hot and cold arms with different width under applied voltage will have different elongation for there different width and the structure will cause the structure laterally bent. Theoretical solutions of deformation and stresses are derived. And numerical methods of finite element are used to analyze for details. The stresses obtained from the finite element are used in fatigue analysis. In the fatigue analysis, high-cycle fatigue model is used as the load in the elastic regime. Considering the accumulation of damage by fatigue being linear, Miner theory is used to estimate the life of the thermal-electrostatic devices under high-cycle fatigue. The result shows with the same length and flexible beam length connecting the hot and cold arms, the large width will cause larger displacement and stresses. However, the difference is not significant. It is also found that as the applied voltage increasing, the displacement and stresses will increase nonlinearly. With the same width and flexible beam length, the larger length will cause larger stresses and small displacement. For fatigue analysis, as the gap increasing and the length and width decreasing, the fatigue cycle increases. It shows when the length and gap are 220 and 5 μm, the fatigue cycle of 50 μm width is more than ten times of 90 μm width. When the width and gap are 50 and 5 μm, the fatigue cycle of 220 μm length is more than ten times of 260 μm length. When the length and width are 220 and 50 fatigue cycles of 50 μm width are more than ten times of 90 μm width, the difference of fatigue cycle between gap 9 and 5 μm is more than 10 times. However, the most significant effect on fatigue is the applied voltage. It shows the fatigue cycle decays very fast as the applied voltage increasing. When the applied voltages are 2 and 8 volts, the fatigue cycles will decrease from 1018 to less than 108. As the applied voltage being 25 volt, the fatigue cycle near zero. Therefore, the limit applied voltage is about 25 volt.
Numerical Study of Conduction and Convection Between Immersed Object and Gas Fluidized Bed
Authors: Gao W. M. , Kong L. X. , Hodgson P. D. , Wang B.
Published: November 2008

To analyze the heat transfer mechanism between fluidised beds and surfaces of an immersed object, the heat transfer and gas flow was numerically simulated for different particle systems based on a double particle-layer and porous medium model. It is fund that the conductive heat transfer occurs in the stifling regions between particle and the immersed surface, which have different temperature. The diameter of the circular conduction region, dc, is a function of particle diameter, dp, and can be given by dc/dp = 0.245dp−0.3. In other areas, the heat transfer between the dense gas-solid phase and the immersed object surface is dominated by convection from the moving gas in the tunnel formed by the first-layer particles and the immersed surfaces. The average dimensionless gas velocity, εmfU/Umf, in the tunnel is a constant of about 4.6. The virtual gas temperature at the free stream conditions can be given by the surface temperature of the first-layer particles. The heat transfer coefficient on the conductive region is about 6∼10 times of that on the convection region. The Nusselt numbers for calculating the instantaneous conductive and convective heat-transfer coefficients were theoretically analysed respectively.
Design and Analysis of Hemispherical Electrostatic Micro Deformable Focusing Mirror
Authors: Tsai Shang-Wei , Lin Meng-Ju
Published: November 2008

For uniform deformation, based on bulk microfabrication with isotropic etching, two types of hemispherical electrostatic micro deformable focusing mirror are designed. One of the focusing mirrors is center-anchored, and the other is circular clamped. Using theory of shells, theoretical solution of deformation under uniform electrostatic force is derived. For more detail analysis of the electrostatic and elastic forces coupling problem, finite element is used to analyze the deformation of the mirror structure. Applying electrostatic force, the profile of micro focusing mirror will be not the spherical and change to become a curve like parabolic surface. Using least square method, the curve is fitted as a parabolic curve and the focal lengths of the focusing micro mirror are obtained. The result shows the focal length without applying electrostatic force can be determined by different micro mirror radius and isotropic etching depth. When the electrostatic forces are applied, the deformation and the focal length change differently between the two types of focusing mirror. For circular clamped micro mirror, the deformation is larger near circular clamped region and uniform in the center regime. Therefore, the relation of focal length and applying voltage is a concave curve with minimum values. That is, the focusing length decreasing as the applying voltage increasing and reaches a limit values. When the applying voltage continues increasing after reaching the minimum value, the focal length increases fast. It also shows the thicker structure layer needs larger applied voltage. But the focal length changes in larger stroke. The pull-in voltage is about 100 volt when the structure layer are both 2 μm. However, the pull-in voltage increases nonlinearly as gap increasing. When the gap increases to 4 μm, the pull-in voltage is about 300 volt. The result shows center-anchored micro mirror has better performance. The deformation is more uniform and the focal length increases nonlinearly as applied voltage increasing. It is found the stroke of focal length is larger and the applied voltage is less. The results shows even when the gap and structure layer is 4 and 2 μm, the pull-in voltage is about 62 volts. However, the stoke changes from 990 to about 1320 μm when applying voltage is from 0 to 60 volts. Therefore, with low applied voltage and large focal length stoke, the center-anchored micro mirror has good performance.
A Novel Approach to Product Innovation Profiling Assessment: The I-DSM Tool
Authors: Maravelakis Emmanuel , Bilalis Nicholas , Antoniadis Aristomenis , Moustakis Vassilis
Published: November 2008

Innovation is a major driving force for the economic growth and expansion of companies and the need to innovate has become clear by now. The quality of the decisions during the design phase of a product development process is strongly connected with the assessment of the product, process and organisational innovation dimensions. The developed methodology addresses these three axes, using 30 innovation attributes, in order to obtain a product innovation profile through an innovation survey. This way a range of industry standard Innovation scores called PIP-SCORES (Product Innovation Profile scores -or innovation benchmarks) have been established. So far more than 600 companies coming from a range of industrial sectors that include creative industries, electrical/electronic, fire and safety, footwear, plastics, ceramics and textiles, have participated in this survey and their innovation profiles have been included in the database. The proposed tool benchmarks the product innovation profile of a company with the corresponding innovation scores from companies coming from the same sector. Next, the tool utilises a Design Structure Matrix, for mapping the dependencies between the Innovation Attributes. Furthermore an Innovation Improvement Impact Value for each Attribute is introduced. In order to improve the innovative profile of a company, a considerable amount of resources is needed. Provided that resources are usually limited to most companies, an optimal improvement strategy, based on the Innovation Improvement Impact values is proposed. The proposed tool (I-DSM, Innovation - Design Structure Matrix) aims at improving the innovative performance of a company, by minimizing the product development cycle and by improving the performance of the product development process.
An Industrial Robot and a Laser Scanner as a Flexible Solution Towards an Automatic System for Reverse Engineering of Unknown Objects
Authors: Larsson So¨ren , Kjellander J. A. P.
Published: November 2008

Reverse Engineering (RE) is concerned with the problem of creating CAD-models of real objects by measuring point data from their surfaces. Current solutions either require manual interaction or expect the nature of the objects to be known. In order to create a fully automatic system for Reverse Engineering of unknown objects the software that creates the CAD-model must be able to control the operation of the measuring system. This paper presents a real implementation of a measuring system suited for that purpose. The experimental setup is based on an industrial robot with a laser scanner mounted at the tool-mounting flange. The key component of the system is a programable CAD-system. The CAD system is used to simulate and control the movement of the robot, as well as collecting the data acquired from both the laser scanner and from the robot’s positional system.
On the Asymptotic Stability of Linear Discrete Time Delay Systems
Authors: Stojanovic S. B. , Debeljkovic D. Lj.
Published: November 2008

This paper extends some of the basic results in the area of Lyapunov (asymptotic) to linear, discrete, time invariant time-delay systems. These results are given in the form of only sufficient conditions and represent other generalisation of some previous ones or completely new results. In the latter case it is easy to show that, in the most cases, these results are less conservative then those in existing literature. A numerical example has been working out to show the applicability of results derived. To the best knowledge of the authors, such results have not yet been reported.
Saturation and Its Application in the Vibration Control of Nonlinear Systems
Authors: Shoeybi Mohammad , Ghorashi Mehrdaad
Published: November 2008

An investigation on the nonlinear vibrations of a system with two degrees of freedom when subjected to saturation is presented. The method is especially applied to a system that consists of a DC motor with a nonlinear controller and subjected to a harmonic forcing voltage. Approximate solutions are sought using the method of multiple scales. Also, singular point analysis is used to study stability of solutions. These findings are then compared with the corresponding numerical results. Good agreement between the two is observed.
Nonlinear Free Vibrations of a Timoshenko Beam Using Multiple Scales Method
Authors: Ramezani Asghar , Ghorashi Mehrdaad
Published: November 2008

In this paper, the large amplitude free vibration of a cantilever Timoshenko beam is considered. To this end, first Hamilton’s principle is used in deriving the partial differential equation of the beam response under the mentioned conditions. Then, implementing the Galerkin’s method the partial differential equation is converted to an ordinary nonlinear differential equation. Finally, the method of multiple scales is used to determine a second order perturbation solution for the obtained ODE. The results show that nonlinearity acts in the direction of increasing the natural frequency of the thick-cantilevered beam.
Trend-Morph-PDS: A Methodology for Innovative (Mechanical) Engineering Design
Authors: Dartnall John , Johnston Stephen
Published: November 2008

The paper describes a design methodology, TREND-MORPH-PDS, an original contribution to design science. It is a relatively simple methodology that has grown from efforts to innovate mechanical machines with their strong dependence on solid (geometrical) reasoning. The approach focuses on combinatorial methods of invention/innovation/design emphasizing the manipulation of form (as distinct from the manipulation of function alone) that help the designer to generate a wide range of good design alternatives. The first premise of this approach is that the elements and functions of mature technologies such as mechanical machines are well documented and understood. Thus, innovations are more likely to involve new combinations of existing forms than the introduction of new machine elements. The second premise is that valuable information is available about most elements and the more popular subsystems and machines. That information has evolved, sometimes over time spans ranging to hundreds of years, but usually has not been systematically documented and categorised, thus leaving opportunities to investigate these areas and discover good design possibilities. Further, some valuable information is available only anecdotally or is tightly held by the managements of the companies that have manufactured the device(s) or own the intellectual rights. The TREND-MORPH-PDS methodology involves three phases: 1. TREND: Start with a general goal or goals. Break this down into sub-areas/systems, including: socio-economic, near physical environment, power source, prime mover, gearing/matching, transmission, working sub-system and control system. Research and document historical trends in each of these areas and their possible influences on the design. 2. MORPH: Apply morphological analysis to each sub-system, using rapid graphical techniques. Move to detail design for specific alternatives as satisficing sub-systems are identified. 3. PDS: At all times during these stages, take advantage of design knowledge/tools that are currently available, looking for ideas and opportunities. Work constantly on constructing the Product Design Specification (PDS). The conceptual design is complete when the PDS is finalized. Detail design, which would follow from the PDS, is not treated in this paper. We illustrate the methodology with a case study of a morphological analysis of a ground water pumping system suitable for low volume flow pumping.
Finite Element Modeling and Dynamic Stress Analysis of the Arterial Wall With Physiological Arterial Pressure Waveforms
Authors: Tafazzoli Shadpour Mohammad , Avolio Albert , Delavarpour Shahram
Published: November 2008

Arterial diseases, promoted by modification of arterial wall properties, are among the main causes of morbidity and mortality. Biomechanical parameters, including mechanical wall stress, are important factors determining arterial function in normal and pathological conditions. This investigation aims to determine dynamic stress distribution in the arterial wall 7subjected to physiological pressure waveforms. Finite element models of a typical artery were developed to evaluate Von Mises stress in the arterial wall due to physiological pressure waveforms and with differing mechanical parameters, including Young’s modulus of elasticity, non-linear stress-strain relationship and visco-elastic parameter, and appropriate boundary conditions allowing radial expansion. Results showed marked effects by mentioned parameters on maximum, minimum and amplitude of the stress wave and stress waveform. This study suggest to analyse fatigue effects of the arterial wall due to differing stress waveforms and values.
Elastic-Plastic Modeling of Kinematic Hardening Materials Based on F=FeFp Decomposition and the Logarithmic Strain Tensor
Authors: Ghavam Kamyar , Naghdabadi Reza
Published: November 2008

In this paper, based on the multiplicative decomposition of the deformation gradient tensor an elastic-plastic modeling of kinematic hardening materials is introduced. In this model, the elastic constitutive equation as well as the flow rule and hardening equation are expressed in terms of the corotational rate of the elastic and plastic logarithmic strains. As an application, the simple shear problem is solved and the stress components are plotted versus shear displacement for a kinematic hardening material.
Analysis of Mixed Convection in Vertical Convergent Channels
Authors: Bianco Nicola , Manca Oronzio , Mauro Alfonso W. , Naso Vincenzo
Published: November 2008

Air mixed convection in a convergent channel with the two principal flat plates at uniform heat flux is analyzed numerically. In the considered system two parallel adiabatic extensions are placed downstream the convergent channel. The forced flow is obtained by imposing a pressure drop between the inlet and the outlet of the channel. The flow in the channel is assumed to be two-dimensional, turbulent and incompressible. A k-ε turbulent model is employed. Results in terms of dimensionless wall temperature distribution as a function of the walls converging angle, the Grashof number and the pressure drop are presented in the ranges: 0 ≤ ΔP ≤ 2.2·107, 2.8·104 ≤ Gr ≤ 2.1·105. Results show that increasing the angle of converging the Reynolds number increases at the same pressure drop. The larger the pressure drop the smaller the contribution of the free convection to the Reynolds number. Increasing the converging angle only slightly increases the ΔP value for which the effect of free convection is negligible.
Processing Product Fault Causes Induced During Solution Principle Synthesis
Authors: Bruch Christine
Published: November 2008

This paper addresses the problem of product fault anticipation and prevention during conceptual design of mechanical engineering products by introducing the concept of undesired functions as potential fault causes. The undesired functions considered in this paper are induced during solution principle synthesis and affect a product either by reducing the input of its intended functions or by producing undesired outputs, and can be processed either by determining and optimizing their distribution function, or by finding inverse, consecutive or compensation functions to them. The formal definition of the generic process of processing undesired functions bases on its subdivision into elementary steps, each step being described by its states and the according state transition. Object patterns and process patterns are adopted for the representation of the static and dynamic design knowledge respectively. The concept is verified with a product example from mechanical engineering.
Dimethylether From Coal: Performance Assessment of IGCC Power Plants Integrated With DME Synthesis Processes
Authors: Cocco Daniele , Pettinau Alberto , Tola Vittorio
Published: November 2008

It is well known that coal gasification plants allows to produce a clean synthesis gas which can be used as a fuel in IGCC power plants and as a raw material in order to produce hydrogen, methanol, dimethylether (DME) and other chemicals. Recent studies show the growing interest of DME as a new clean fuel for diesel engines, gas turbines, fuel cells and household uses. In this paper, a comparative performance analysis of two different IGCC power plants integrated with a DME synthesis process has been carried out. In particular two different coal gasification processes (a dry-feed and a slurry-feed entrained-flow gasifiers) and the advanced liquid phase DME (LPDME™) synthesis process have been considered. The analysis has been carried out in order to evaluate the influence of the operating parameters of the DME synthesis section (pressure and purge gas recycle ratio) on both DME production and net power output. The performance assessment has shown that, according to both gasification process and DME synthesis parameters, the produced DME accounts for about 40–46% of the coal chemical energy, whereas the net power output of the IGCC-DS plant accounts for about 13–19%. Moreover, the performance assessment also has shown that the IGCC-DS power plants based on the slurry-feed gasification processes lead to an higher DME production and a corresponding lower power output with respect to the solutions based on the dryfeed gasifiers.
Direct Adaptive Control for a Certain Class of Nonlinear Systems Using Modified Radial Basis Function Neural Network
Authors: Chen Hsuan-Ju , Chen Rongshun
Published: November 2008

This paper proposes a direct adaptive controller for SISO affine nonlinear systems using Gaussian radial basis function (RBF) neural network (NN). The exact plant model is not necessary for composing the controller. If the plant is SISO, of affine form, without zero dynamics, and all the state variables are available, the controller is applicable under several mild assumptions. In this paper, the Gaussian RBF network (GRBFN) is modified to include pre-scale weights as its parameters for the input variables, which are also adapted in the control law. Pre-scaling the inputs is equivalent to extending or contracting the spectrum of the approximated function. With the modification, the spectrum along each coordinate of the domain can be scaled separately for approximating. The adaptation of the nonlinear parameters, including the variances, centers, and pre-scaling weights, are derived. Appropriate modification techniques are applied to the adaptation laws to ensure the robustness. The stability is analyzed with Lyapunov’s Theory. From the analysis, the effect of the controller design parameters is also examined. A simulation of an inverted pendulum control is demonstrated to show the effectiveness.
Wave Response of Underwater Observation Tower Constructed at the Breaker Zone
Authors: Sasaki Takahiro , Saijo Osamu , Maruyoshi Koichi
Published: November 2008

There exist eight underwater observation towers in Japan. Seven of them have been built by vertical circular cylindrical shell structure, which are fixed at the sea bed like cantilever. And the other one is constructed of floating structure. Among the seven fixed-type structures, one stands under the frozen sea. The underwater observation towers are surrounded by sea water, and the inside is perfectly a close-spaced. Sightseers and several interested people visit to observe the undersea scene. Therefore, top priority must be given to structure safety. There is a vast existence of various creatures within the outstanding underwater scene which needed to be maintained to proliferate life. In order to satisfy with convenient access and outstanding scene, most structures have been built at the breaker zone. This paper presents the following contents: 1) Assuming that the underwater observation tower is constructed by vertical circular cylindrical shell, natural frequency analysis will be shown using present simple equation of added mass. We developed this equation uniquely based on fluid-structure interaction problem through water tank experiment and systematic numerical calculation. 2) Sawaragi, et al had presented wave breaking force acting on the vertical cylinder through the experiment. With reference to the force given by total force, we have newly extended its force to the wave pressure distribution so as to correspond to FEM analysis. We will show this developed method with regard to wave pressure distribution on the surface of cylindrical shell. 3) Using this simple equation of added mass and nodal forces obtained from wave breaking force, a procedure of calculation will be shown with demonstration. The evaluation and the validity in terms of added mass, load arrangement and responses will be discussed through the comparison of experimental result.
A Case Study in Healthcare Quality Management: A Practical Methodology for Auditing Total Patient X-Ray Dose During a Diagnostic Procedure
Authors: Palmer Paul , Mason Lesley , Dunn Mike
Published: November 2008

The healthcare industry is adopting many of the best practices familiar to the manufacturing sector. For example the need for ISO 9000 registration is now seen as an important business driver, indeed, BSI offers specific advice for Healthcare organisations seeking to gain ISO 9001:2000 approval. Accompanying the integration of quality systems into the healthcare business is the need to find practical measures of quality that may be used as part of an overall process to deliver improved performance. The manufacturing industry has a rich array of techniques such as JIT (Just In Time), 6 Sigma, SPC (Statistical Process Control), TQM (Total Quality Management) which may all now be found cited in conjunction with the healthcare industry. This paper focuses on the legislatively driven need to locally audit and minimise the diagnostic X-ray dose received by patients during a Barium Enema procedure. This procedure was selected as it has been shown by other authors to have a reasonably narrow spread of total patient dose levels and therefore might be relatively easy to draw statistically significant inferences for management purposes. The Ionising Radiation (Medical Exposure) Regulations 2000 (IRMER) and Health Service Circular on Clinical Governance (HSC1999/065) state that Clinical Audit should be performed to identify and monitor the issues leading to quality improvement and best practice. This is a statement of requirement, which delegates the responsibility of implementation to the local level. The IRMER Regulation also require the setting of local Diagnostic Reference Levels (DRLs). These are levels of radiation dose for individual examinations which under normal circumstances should not be exceeded. Producing a meaningful audit and DRLs in small departments raises many issues: data availability and capture may be time consuming especially if records are kept on paper-based systems; analysis of the data may present a steep learning curve in statistical techniques; a high degree of statistical confidence in the results is required along with sensitivity in their presentation and dissemination to ensure that they become part of a process of continuous improvement (rather than part of a blame culture). This paper presents a practical approach to delivering a meaningful audit of locally collected data using readily available software tools (Excel Spreadsheet), in conjunction with a relatively simple numerical statistical analysis technique called ‘bootstrapping’. Bootstrapping enabled us to set the local DRL for this procedure with an estimate of statistical confidence. An analysis was performed on the data to determine factors contributing to total patient dose.
Processing and Characterization of Particulate SiC Reinforced Copper Matrix Composites
Authors: Bhanu Prasad V. V. , Vasudeva Rao V. , Putrevu Aditya , Vijay A. S. , Harini G.
Published: November 2008

Copper Matrix Composites reinforced with particulate Silicon Carbide were consolidated by Vacuum Hot Pressing and Press-Sinter routes. The reinforcement content was varied from 10% to 30% by volume. The composites were then characterized for their microstructure, density, X-ray diffraction (XRD), Coefficient of Thermal Expansion (CTE), hardness, tensile strength, electrical conductivity and elastic modulus. The properties were compared with those of Copper Tungsten alloys. Cu/SiC composites are found to be potential materials for electrical contact and welding applications. An attempt has also been made to evaluate the suitability of copper matrix composites as a replacement to copper tungsten alloys.
Use of Neural Network and Discrete Wavelet Transformations in Estimation of Road Profile
Authors: Durali Mohammad , Kasaaizadeh Alireza
Published: November 2008

This paper presents a method for estimation of road profile for automotive research applications with more accuracy and higher speed. Dynamic response of a car equipped with position and velocity sensors and driving on a sample road is used as basic data. A feed-forward neural network, trained with outputs from a car model in ADAMS, is used as the car inverse model. The neural network is capable of estimating the road roughness from the car response during test drives. The ADAMS model is corrected and validated using a series of dynamic experiments on the car, performed on a hydro-pulse test rig. The only problem in this approach, like other identification and optimization methods, is the large volume of generated data in time domain, acquired from car response during road test. This problem is solved using wavelet methods to code the acquired data. Unlike all frequency methods that eliminate a large portion of the data details during processing, the wavelet coding method restores most of the details, while the volume of the stored data is kept to a minimum. The results show that this method can estimate the road profile accurately and with great savings in processing time and effort.
A Study on the Behavior of the Pressure Drop for the Fluid Flow in a Triangular Microchannel
Authors: Teng Jyh-Tong , Chu Jiann-Cherng , Chen Jyh-Juinn , Wang Chi-Chuan , Lin Chun-Hung , Greif Ralph
Published: November 2008

This study investigates experimentally and numerically the characteristic of the pressure drop and the behavior of the fluids under the influence of the configurations of flow channel. The triangular microchannels have the transverse dimensions from 50μm to 100μm; the fluid flowing through these channels has Reynolds numbers from 0.1 to 35. For this study, significant difference between the pressure losses obtained from the conventional macro-scale theory and those obtained from the experimental data. However, the results obtained from the conventional theory are not much different from the results obtained from the numerical simulation. For the triangular microchannel under study, the pressure loss in terms of fRe obtained from the experimental results is lower than those obtained from the conventional theory; the highest relative error is 27%. The revised correlation derived from the experimental results for the value of fRe of the fluid in the Triangular is fRe = 45.6; using this expression would provide a better fit to the experimental data.
A Novel Approach for Extracting Sensor Information From Different Industrial Networks for Internet Based Condition Monitoring Applications
Authors: Ashraf Bilal , Zorriassatine Farbod , Parkin R. M. , Coy Joanne
Published: November 2008

Automated Condition Monitoring (ACM) has become a necessity for complex modern day systems. The advent and ever increasing popularity of Internet has given a new dimension to ACM. Many Internet Based Condition Monitoring (IBCM) solutions have since been implemented. There are many types of Industrial Networks that are used in the industry to implement ACM. The protocols and information sent through these networks are very different from one another. Sharing information between industrial networks and presenting it for consolidated monitoring can be a daunting task. This paper describes a novel way for extracting sensor information from different industrial networks into a single standard format using Extensible Markup Language (XML). Implementation of the solution with an Industrial Network, Controller Area Network (CAN), is also shown. The results demonstrate that by using this approach communication between automated systems and mechatronic devices will become more integrated, more efficient and less complex.
Thermal Performance Characteristics of a Nuclear Fuel Element Dissipating Heat in a Surrounding Medium
Authors: Ramis M. K. , Jilani G.
Published: November 2008

This paper deals with the numerical prediction of thermal performance characteristics of a rectangular nuclear fuel element dissipating fission heat in its surrounding medium. Assuming uniform heat generation within the fuel element, the steady, two-dimensional heat conduction equation along with appropriate boundary conditions is solved using second order accurate finite difference scheme. On the basis of axial temperature profiles and the variation of Biot number, Bi and heat generation parameter, Q with respect to maximum temperature, θmax within the fuel element, results are presented for a wide range of aspect ratio, Ar, Bi, and Q and discussed in detail. It is found that with the increase in Ar, the effect of axial conduction on the temperature profile diminishes rapidly and ultimately for all values of Ar ≥7, it remains confined to the region very close to the leading edge. It is also concluded that for a set of fixed values of Ar and Q, there exists a lower limiting value of Bi below which it cannot be decreased. Similarly, for a set of fixed values of Ar and Q, there also exists an upper limiting value of Q above which θmax exceeds its allowable limit. Furthermore, it is concluded that the requirement of increase in Bi due to increase in Q, θmax being within its allowable limit, becomes larger and larger as Q becomes higher and higher.
How to Design and How to Teach Designing
Authors: Lans Wendelien
Published: November 2008

Design processes have been formalized into models in several ways, for instance Findeisen and Quade (1985), Woestenek (1999). Cognitive processes that take place in a designer’s mind during a design process are related to these formal models, but are more complex. These cognitive processes can be considered as cyclic processes in which several activities play a role, such as processes of trial and error, discovering new solutions and broadening the scope of possible solutions, as well as evaluating tentative solutions and taking decisions. The process of learning how to design, in turn, is related to the cognitive design processes. A student’s learning process can be considered as based on a — whether or not deliberately composed — mix of ingredients. We can discern self experience — sometimes based on trial and error —, next to experience passed on by others (e.g. the teacher) and knowledge as a result of scientific investigations. To some extent, learning is also based on imitation behaviour. In the paper, these aspects will be worked out into (first steps to) a teaching model as a basis for developing a curriculum and for explication of adequate teacher’s tasks. Starting point is the student’s self-reliant learning process, the aim of which is to educate self-reliant designers. The paper should be considered as a first result of a more extended study that will be undertaken in the next years.
Application of FPGAs to High-Speed Condition Based Maintenance of Rolling Element Bearings
Authors: Harriman Mark , Zorriassatine Farbod , Parkin Rob , Jackson Mike , Coy Jo
Published: November 2008

Field-Programmable Gate Array (FPGA) technology has been applied widely in electronic engineering and computing industries, but it has not had the same level of reception in other disciplines including mechanical engineering [1]. The purpose of this paper is to examine FPGA implementations of signal processing techniques that are used in the context of bearing condition monitoring. As the number of bearings can be large sparse sensor arrays are used to locate and detect their condition. The demands of realtime process monitoring [2] [3] can place a heavy burden upon the monitoring system. Field-Programmable Gate Array (FPGA) technology [4] in this application makes it possible to implement more sophisticated algorithms. These exploit its high-speed, parallel, reconfigurable architecture. Bring forth the advantages of FPGA technology to condition monitoring. The techniques covered are: cross-correlation, digital signal processing (DSP) Infinite Impulse Response (IIR) filters, neural networks and signature matching. The implemented designs are optimised for both execution time and the amount of logic area consumed. Results were obtained from each technique and were assessed and compared in terms of execution time and also the amount of logic consumed on the FPGA. Over the past 15 years FPGA technology has been applied extensively in electronic engineering but its scope has not been as vastly in mechanical engineering. The objective of this paper was to examine an application in mechanical engineering. Ideally this would be done with a mechanical engineering compatible approach, giving rise to a methodology, which would allow FPGA programming [5] to become a transferable skill.
General Derivations for Conjugate Strains of Eshelby-Like Stress Tensors
Authors: Behfar K. , Sheshmani A. , Naghdabadi R.
Published: November 2008

In this paper, a general type of Eshelby-like stress tensor is defined which is based on the right stretch tensor and is equal to the product of a general class of strain and the corresponding conjugate stress tensor. The Eshelby-like stress tensor depending on the fact that from which side the stress tensor is multiplied by, is categorized into the right-weighted and left-weighted ones. General relations for conjugate strains of Eshelby-like stress tensors are investigated using the method, based on the definition of energy conjugacy and Hill’s principal axis method.
The Response Analysis of the Piezoelectric Shell Panel Actuators Based on the Theory of Elasticity
Authors: Daneshmehr A. , Shakeri M.
Published: November 2008

A study on the elasticity solution of shell panel piezoelectric actuators is presented. In this paper, the structure is infinitely long, simply-supported, orthotropic and under pressure and electrostatic excitation. The equations of equilibrium, which are coupled partial differential equations, are reduced to ordinary differential equations with variable coefficients by means of trigonometric function expansion in circumferential direction. The resulting ordinary differential equations are solved by Galerkin finite element method. Numerical results are presented for [0/90/P] lamination. Finally the results are compared with the assumption of piezoelectric layers in published results.
Generalization of the RANS Equations Using Mean Modal Decomposition of the Navier Stokes Equations
Authors: Sabetghadam Fereydoun
Published: November 2008

A generalization in the Reynolds decomposition and averaging are proposed in this paper. The method is directly applied to the Navier Stokes (N-S) equations to construction of a generalized Reynolds Averaged Navier Stokes (RANS) equations. The formulation which is presented for the fields realized in a suitable ensemble, is based on a two part decomposition. One part is an approximate unique representation of the field and when reconstruction of the field, will repeat in all ensemble elements. The other part represents deviation of the real field from the approximate part and therefore is different in any mode and each ensemble element. The decomposition is applied in both spatial and temporal fashions. In the temporal decomposition, a system of Partial Differential Equations (PDEs) is obtained that is nonclosed, coupled and second order in space and its zeroth mode is the classical Reynolds averaged values of the field. In the spatial decomposition whereas, a first order system of nonclosed PDEs is obtained which could be seen as an alternative version of the Proper Orthogonal Decomposition (POD) or the Coherent Vortex Simulation (CVS) methods. In both fashions however, there are some terms that must be modeled just like as the classical closure problem in the RANS method. The method is applied on a one dimensional mixed random-nonrandom field and successfully extracted the coherent part of the field.
Visualisation of Two-Phase Gas-Liquid Pipe Flows Using Electrical Capacitance Tomography
Authors: Hunt Andy , Pendleton John , Ladam Yves
Published: November 2008

Electrical Capacitance Tomography (ECT) has been used over a number of years to measure concentration distribution, and more recently velocity distribution, in two-phase flows. ECT is non-intrusive, and the reconstruction of the concentration and velocity distribution can be undertaken in real time and over an arbitrary number of zones in the flow cross-section. In this paper the concept of a ‘virtual instrument’ is introduced where zones of the image can be structured for comparison with other measurements. Numerical agreement with gamma-ray density measurements is shown to be excellent in slug and stratified flows. We present a series of measurements undertaken in complex oil/gas slug flows in a large flow loop. We present a variety of 2-D cross-sectional images, time series velocity and concentration graphs and 3-D contour plots. The good temporal and spatial resolution of ECT throws an extensive new light on these otherwise difficult to measure dynamic flow structures. In particular with bubbly-slug structures known as ‘ghosts’ ECT shows clearly that they are in fact bubbly waves which have extended ‘wings’ up and around the pipe.
Analysis of the Weighting Matrix for Load Distribution Using Weighted Pseudoinverse in a Redundantly Actuated System
Authors: Park Dong Il , Kim Soo Hyun , Kwak Yoon Keun
Published: November 2008

Redundant actuation indicates a situation when there are more actuators than a system’s mobility. A redundant actuated system has many strengths, such as better performance than a non-redundant system, avoiding singularity, reducing impact force using active stiffness control and fault tolerance. However, there are some issues on economic efficiency and minimization of a system, because redundant actuation can use more actuators than non-redundant actuation. Also, in a redundant actuation system, the actuator torque does not have one solution, but rather there are infinite torque sets even though a robot works on the same task. Therefore, it is very important to select a torque distribution method that is suitable for the objectives of the robot. In this paper, we used the weighted pseudoinverse matrix for torque distribution. This method is applied to a five bar link system and the influence of the weighting variables is analyzed. By adjusting the weighting values, we can find the relation between the actuator input and the weighting value and obtain various torque sets in real time. In other words, we find how each actuator torque changes according to the variation of each weighting value and how much the maximum torque reduce for the suggested weighting matrices.
Computation of Nonlinear and Edge Effects in a Thermoacoustic Refrigerator
Authors: Marx David , Blanc-Benon Philippe
Published: November 2008

In thermoacoustic refrigerators, the acoustic energy provided by an acoustic source is used to pump heat from a cold reservoir. Such refrigerators work with benign fluids, and may possibly be miniaturized, offering an application to microelectronic refrigeration. The linear theory frequently used to predict thermoacoustic refrigerators performance, because it relies on the simplification of the governing equations, can not account for all the phenomena involved in thermoacoustic heat pumping. In the present work, the full compressible two-dimensional Navier-Stokes equations are solved numerically, and the flow and heat transfer above a plate immerged in an acoustic standing wave are computed. Some phenomena, which are not taken into account in the linear theory, are observed. Non-harmonic temperature variations are found and are explained using the results of a former nonlinear analysis. The effect of vortical motions at the extremity of the stack plates on heat transfer is studied.