bluuebunny/crossref_metadata_2025 huggingface dataset:
Phase Interactions in Monoclinic Zirconia Reinforced Hydroxylapatite Bioceramics
Authors: Ergun Celaletdin , Evis Zafer , Doremus Robert H.
Published: November 2008

Hydroxylapatite composites with pure zirconia were prepared with pressureless air sintering and hot pressing for 1 hour at different temperatures between 900°C and 1300°C. The interaction between the phases was monitored with XRD and thermal analysis. At sintering temperatures higher than 1000°C, an apparent Ca diffusion occurred from hydroxylapatite to pure zirconia phase and changed its structure from monoclinic to tetragonal/cubic. In the mean time, hydroxylapatite decomposed and formed tricalcium phosphate. Also, a reaction was occurred at 1220°C between hydroxylapatite and zirconia phase forming CaZrO3. The existence of air in the processing environment increased the reactivity between hydroxylapatite and zirconia.
ECT Visualization of Two Phase Flows
Authors: Liu S. , Wang H. , Jiang F. , Yan R. , Dong X. , Yang W. Q.
Published: November 2008

Electrical capacitance tomography (ECT) has been under rapid development in recent years. However, as a relatively new technology, ECT is far from mature and its applications are rather appliance-dependent, i.e. the sensor design, calibration, and data interpretation etc., depend on the understanding of the specific situations for ECT measurement. The authors have experimented several sensing strategies and developed algorithms for 3D image presentation and online iterative image reconstruction, and applied ECT to the measurement of several typical cases of two phase flows, which is reported in this paper.
Numerical Solution of Transient Flow in Wind Tunnels
Authors: Nouri-Borujerdi A. , Ziaei-Rad M.
Published: November 2008

This paper deals with design and analysis of intermittent supersonic wind tunnels. System can be constructed by allowing air at atmospheric pressure to pass through a converging-diverging nozzle, a test section and a diffuser into a vacuum tank. The governing equations of compressible fluid flow have been solved numerically using flux vector splitting method to obtain running time under which it works at the design Mach number. The formulation has been tested on the theory of quasi one-dimensional compressible flow. The numerical results are in good agreement with the results of the theory.
Non-Linear System Identification of Flexible Plate Structures Using Neural Networks
Authors: Mat Darus I. Z. , Tokhi M. O. , Mohd. Hashim S. Z.
Published: November 2008

This paper investigates the utilisation of feedforward and recurrent neural networks for dynamic modelling of a flexible plate structure. Neuro-modelling techniques are used for non-parametric identification of the flexible plate structure based on one-step-ahead prediction. A multi layer perceptron (MLP) and Elman neural networks are designed to characterise the dynamic behaviour of the flexible plate. Results of the modelling techniques are validated through a range of tests including input/output mapping, training and test validation, mean-squared error and correlation tests. Results are presented in both time and frequency domains. Comparative performance assessments of both neuro-modelling approaches in terms of mean-squared error and estimation of the resonance modes of the system are carried out. It is noted that both techniques have been able to detect the first five vibration modes of the system successfully. Investigations also signify the advantage of a recurrent Elman network over an MLP feedforward network in modelling the flexible plate structure.
A High Speed Current Pulse Electrical Resistance Tomography System for Dynamic Process Monitoring
Authors: Randall E. W. , Wilkinson A. J. , Long T. M. , Sutherland A.
Published: November 2008

This paper describes an instrument for Electrical Resistance Tomography (ERT) measurements based on a current pulse technique which has been shown by the authors to be a viable and easily implemented alternative to conventional AC excited systems. This system enables data to be acquired and recorded at 1000 frames/second on a single plane 16 electrode system and every 50th frame to be reconstructed and displayed to provide a real time display. The high frame rate enables transient phenomena to be investigated. The design incorporates a multiplexor allowing 8 rings of 16 electrodes to be sampled sequentially and thus provide data sets from all planes at 125 frames/second. This data can be processed to provide 3-D reconstructions and for velocity measurements using cross-correlation techniques. The system is primarily intended for use in minerals processing applications and data is presented from electrode systems used in slurry pipeline monitoring. It is suggested that simplified design and low manufacturing cost of the current pulse ERT systems will open the way for wide scale industrial applications.
Adaptive IIR Filtering Techniques for Dynamic Modeling of a Twin Rotor System
Authors: Tokhi M. O. , Alam M. S. , Aldebrez F. M.
Published: November 2008

This paper investigates the development of a parametric model to characterise pitch movement in a twin rotor multi-input multi-output system (TRMS) using adaptive infinite impulse response (IIR) models. The TRMS is a laboratory platform designed for control experiments. In certain aspects, its behaviour resembles that of a helicopter. It typifies a high-order nonlinear system with significant cross coupling between its two channels. It also simulates similar problems and challenges encountered in real systems. These include complex dynamics that lead to both parametric and dynamic uncertainty, unmeasurable states and sensor and actuator noise. In this work, adaptive IIR filtering techniques using least mean square (LMS) and recursive least square (RLS) algorithms are investigated for dynamic modelling of the system. The system is initially excited with random gaussian sequence input signal of sufficient bandwidth (0–10Hz) to ensure that all resonance modes of interest are captured. The magnitude of the input signal is selected so that it does not drive the system out of its linear operating range. Good excitation is achieved from 0–2.5 Hz, which includes all the important rigid body and flexible modes. Then, adaptive IIR filters based on equation error formulation are used for modelling the system. Three standard algorithms; namely, LMS, normalized LMS and RLS are utilized as learning algorithms, to update the parameters of the filter during the modelling process. A comparative assessment of the three learning algorithms, in characterising the system, is conducted. The performance of each model is assessed in terms of output tracking, minimization of the mean-square error, stability and algorithm convergence.
Centrifugal Water Pump Driven With a DC Motor Powered by an Emulator of MK5-E Proton Exchange Membrane Fuel Cell Stacks
Authors: Lo Mastro Fabio , Blando Gandolfo
Published: November 2008

Direct Current (DC) motors can be directly powered by Proton Exchange Membrane Fuel Cell (PEMFC) Stacks, to obtain plants with little maintenance and good reliability. To obtain a suitable efficiency working plant, it’s necessary to correctly match the load in order to operate in proximity to the best power line of the FC stacks generator. Otherwise by a proper field current regulation of a separately excited DC motor directly powered by a FC stacks generator, it is possible to extract from the generator itself the correct power for every temperature level. The present interest for this problem has advised the Authors to perform an experimental investigation, whose results are reported in this paper, about a centrifugal water pump powered as above c/o the machines laboratory of the Mechanical Department of the University of Palermo.
The Application of Approximate Reasoning Methodologies to Offshore Engineering Design Based on Risk Assessment
Authors: Eleye-Datubo A. G. , Sii H. S. , Wang J. , Yang J. B. , Liu J.
Published: November 2008

In dealing with complex and ill-defined systems of an offshore application, modelling of human reasoning for the purpose of risk assessment requires the effectiveness of a systematic logic-based approach. Floating production, storage and offloading (FPSO) installations, for example, combine traditional process technology with marine technology, and thus are quite dependent on technical design and operational safety control. Such safety-critical dependencies require novel approaches to properly analyse the risk involved. Hence, a proposed framework utilising approximate reasoning and evidential reasoning approaches is provided for modelling the assessment task. As based on fuzzy set theory, the model enables uncertainties to be described mathematically and further processed in the analysis of the structures. The forms of membership functions that could be used in representing fuzzy linguistic variables to quantify risk levels are presented. A case study of collision risk between FPSO and shuttle tanker due to technical failure during tandem offloading operation is used in this paper to illustrate the application of the proposed model. Furthermore, the obtained results from the case study provide confirmation that at various stages of offshore engineering systems design process the framework of incorporated approximate reasoning is a suited and convenient tool for attaining reliable risk analysis.
S. I. Engine Pollution Control Using Low-Cost Palletized Catalytic Converter
Authors: Jakkaraju Madhuri , Patri Vasudha
Published: November 2008

I. C. Engines consume large amounts of fossil fuel emitting harmful pollutants like carbon monoxide (CO), unburnt hydrocarbons (UBHC), and oxides of nitrogen (NOx). By using a catalytic converter (CC), the carbon monoxide, hydrocarbon emissions can be transformed into less harmful carbon dioxide (CO2) & water vapor (H2O). Currently available CC’s are using costly noble metals like platinum (pt), palladium (pd), rhodium (rh) etc., hence making them expensive. This paper deals with the use of low-cost palletized silver coated alumina as the catalyst element in a CC. In this study, alumina and silver were used in the ratio of 10:1. All tests have been conducted on a stationary S.I. Engine at a constant speed of 1500 r.p.m with and without CC. Also, the performance of the palletized CC in combination with promoters like Bismuth, Cerium and Lanthanum was tested which have shown better results than silver alone as the coating element. It has been experimentally determined that the CO emissions have dropped from 7.25 (% vol) to 3.03(% vol) and the HC values have reduced from 350 ppm to 190 ppm.
Application of Vector Bond Graphs to the Modeling of a Class of Hand Prostheses
Authors: Vaz Anand , Hirai Shinichi
Published: November 2008

Vector bond graphs have been systematically applied to the modeling of prosthesis for a partially impaired hand. The partial impairment considered covers a category of the hand that has lost one or more fingers but retains the ability of its remaining natural fingers. The fingers and their prosthetic extensions are considered as rigid links. Rotation matrices which specify orientation of finger links are obtained from respective angular velocities. String-tube mechanism used to actuate prosthetic joints is modeled with the connection to joint variables of the mechanism. The vector bond graph approach enables the modeling of three dimensional movement of the hand mechanism. An example of a two joint string-tube actuated prosthetic mechanism is presented to describe the construction of the vector bond graph model. Systematic derivation of dynamics from the vector bond graphs is shown. The approach based on vector bond graphs presented here is useful for simulations and control systems design of such biomechanical systems.
Design and Optimization of Piezoelectric-Actuated Torsion Mirror With Lever Mechanisms
Authors: Wu Cho-Chun , Lin Meng-Ju , Huang Jin H.
Published: November 2008

Considering with high frequency response and self-detection function, a torsion mirror is designed by using piezoelectric material. For large rotating angle requirement, the torsion mirror contains a mechanism with four levers. The torsion mirror is rotating due to actuated by reflection of a piezoelectric beam deposing on the structure layer. The structure layer connects to the lever mechanism. The lever mechanism has four levers. Three levers enlarge the rotating angles by the different ratio of apply and resist moment arms lengths. The fourth lever has the same apply and resist moment arms lengths to adjust the rotating direction the same as deflection of piezoelectric-actuated beam. For self-detecting rotating angle, another additional beam with piezoelectric material depositing is attached to the mirror plate. Finite element method is used to analyze. To investigate the effect of piezoelectric actuated beam on rotating angle, the results show when the actuated beam has length and width of 300 and 24 μm, the thickness structure and piezoelectric actuation layers are both 1 μm, and the applied voltage is 10 volts, the maximum rotating angles could be 50.4 degree. In this rotating angle, the sensing voltage is 170 volts by the piezoelectric material beam attached to mirror plate. Therefore, the torsion mirror can rotate to large angle and have high resolution of angle sensing. To investigate the effect of ratio of apply and resist moment arms lengths on rotating angle. A maximum value is obtained. To optimize the ratio of apply and resist moment arms lengths, the structure of the torsion mirror with piezoelectric actuated beam being 100 and 8 μm long and wide is investigated. The thickness of structure and piezoelectric actuation layers are both 1 μm. And the applied voltage is 10 volts. It shows that the rotating angle increases nonlinearly as the ratio of apply and resist moment arms lengths increasing. And when the rotating angle reaches the maximum values, the rotating angle decreases fast as the ratio of apply and resist moment arms lengths increasing to 1. The maximum rotating angle is 22.71 degrees and the corresponding ratio of apply and resist moment arms lengths is 46/54. Theoretical analysis is derived and has similar tendency.
The Use of Virtual Reality and Automatic Training Devices in Sport: A Review of Technology Within Cricket and Related Disciplines
Authors: Justham Laura M. , West Andrew A. , Harrison Robert , Jones Roy , Harland Andrew R. , Caine Michael P. , Roberts Jonathan R.
Published: November 2008

Modern technology plays a major role in all aspects of many sports, from training to media commentary and video referees. The work contained in this report is focused on the ball launching devices which are prolific in a number of these sports such as cricket, baseball, tennis and football. These devices are used as aids to enhance the intensity and quality of a training session whilst also enabling batsmen to train without requiring the presence of a bowler. Technological advances, such as visualisation and programmable sessions, have been included in the design of baseball pitching machines but not within the domain of cricket training. The ongoing research presented in this paper highlights a shortfall in the current market and begins to develop a novel cricket bowling system. This includes a fully computer controllable environment capable of creating any cricket bowling delivery synchronised with an accurate visualisation of the bowler throughout the delivery process.
Performances of a High-Speed Impedance Camera for Flow Informatics
Authors: Ma Y. , Wang M.
Published: November 2008

An impedance camera has been developed and optimized for visualization and measurement of two-phase flows. This camera, in its basic construction, can synchronously map two cross sections of a pipeline flow in time sequence, where the components of the flow have impedance contrast. Flow velocity distribution can be implemented from the two series of images using the cross-correlation method. The data capture, image reconstruction, concentration and velocity implementation, all are processed on-line using multi-digital signal processor built in the camera. This paper presents a part of test results regarding to the system major performances of the measurement repeatability, consistency of 16 parallel measurement channels, speeds of data acquisition, rate of image reconstruction and cross-correlation implementation, estimation of the discrimination error in flow velocity and flow rate measurements, etc.
Exhaust-Gas Reforming of Methane to Aid Natural Gas HCCI Combustion: Experimental Results of Open Loop Hydrogen Production and Basic Thermodynamic Analysis
Authors: Peucheret S. , Wyszyn´ski M. L.
Published: November 2008

The Homogeneous Charge Compression Ignition (HCCI) combustion has potential to radically reduce emissions, especially NOx, but is inherently difficult to achieve and control, especially when natural gas is used as fuel. Hydrogen addition, particularly from fuel reforming was successfully used as an aid. Methane reforming with exhaust gas and air in a monolith catalytic reactor is presented here as a source of hydrogen. An open-loop fuel exhaust gas reforming system has been developed and tested; experimental results are compared with two different models of basic thermodynamic equilibria calculations. The experimental results have shown that for low temperature of engine exhaust gas, typical for HCCI conditions, additional air is needed to produce the quantities of H2 required to enhance the feasibility and range of HCCI combustion. At the low reactor inlet temperatures needed for the HCCI application the simplified three-reaction thermodynamic model is in broad agreement with experimental results, while the high hydrogen yields predicted from the multi-component equilibrium model for medium temperature reforming are difficult to achieve in a practical reformer.
Development and Experimental Validation of a Simulation Tool for a Fuel Cell Based Power System
Authors: Andreassi Luca , Cordiner Stefano , Feola Massimo , Romanelli Fabio
Published: November 2008

Fuel cells (FC) technology applied to energy production could represent an effective solution to face greenhouse gas emissions and to differentiate energy sources. However, real performances of FC systems still represent a critical issue in the definition of an assessed and economically competitive technology. In fact, FC performances depend on many variables such as temperature, pressure, current, membrane humidification, stoichiometry of the reactant gas, etc.; additionally, many of these influencing parameters depend one on the other, further complicating the analysis. Numerical simulation could greatly contribute to a better understanding of the influence of design parameters. Nevertheless, the availability of experimental data to validate and to verify the numerical models is an imperative issue. The primary target of the research activity described in this paper is the set up of an experimental test bench for Proton Exchange Membrane Fuel Cell (PEM FC) at the Department of Mechanical Engineer of the University of Roma Tor Vergata aiming to completely test 8 cells 0.1 kW stack: the measured data are fundamental to validate the numerical models which have been developed by the Authors following different hierarchical levels (both semi-empirical and dimensional analytical approach) with different predictive capabilities. This apparatus allows the control of the reactant gas mass flow rates, stack pressure, humidity, current, temperature and voltage. In this way it is possible to assess a mixed experimental-numerical methodology allowing a tuning procedure for the developed models making a wide use of dedicated experimental data. The preliminary results in terms of comparisons between experimental and computational data show a good agreement even by varying some of the most performance-affecting parameters such as operating pressure and temperature.
Magnetostatic Permeability Tomography in Material Inspection
Authors: Soleimani Manuchehr , Lionheart William R. B.
Published: November 2008

Structural materials in reinforced concrete, often made of iron, are sometimes damaged due to acid, rain or salty wind. The magnetic permeability of the damaged materials change due to this damage. In this paper we study an advance monitoring system based on a magnetostatic permeability tomography (MPT) technique. The magnetostatic field is applied to the material from the external surfaces and the measurement data for inspection are the normal components of the resulting magnetostatic fields in the surface. Knowing the tangential component of the applied field and normal component of the measured field uniquely defines the permeability distributions. In practise, excitation and sensing coils can be used for the measurement configuration, in order to gather the data from the surface. The problem of the permeability reconstruction is then a nonlinear and ill-posed inverse problem. We employed a regularised Gauss-Newton method to recover the permeability distribution. The forward problem is to simulate the measurement process. We have implemented a 3D edge-based finite element package to solve the magnetostatic problem via a formulation based on magnetic vector potentials. For the Jacobian matrix and the sensitivity analysis we derived an efficient formulation based on the reciprocity theorem. The results of the forward problem and the sensitivity map will be presented in this paper. We also show the results of 3D permeability reconstruction for a numerically simulated MPT system. The system consists of 8 coils which are used to apply the primary field and measuring the resulting field. The images are reconstructed using synthetically generated data with 28 independent scanning measurements with added noise. The high contrast and low contrast permeability reconstruction will be discussed.
Stability Theory in the Sense of Lyapunov — Basic Approach: Discrete Singular Time Delayed System
Authors: Debeljkovic D. Lj. , Milinkovic S. A. , Stojanovic S. B. , Jovanovic M. B.
Published: November 2008

This paper gives sufficient conditions for the stability of linear singular discrete delay systems of the form Ex(k+1) = Aox(k)+A1x((k-1). These new, delay-independent conditions are derived using approach based on Lyapunov’s direct method. A numerical example has been working out to show the applicability of results derived. To the best knowledge of the authors, such result have not yet been reported.
Two Dimensional Transient Analysis of Temperature Distribution in a Solid Irradiated by a Gaussian Laser Source
Authors: Bianco Nicola , Manca Oronzio , Nardini Sergio
Published: November 2008

The use of localized heat source, such as lasers and electron beams, in many manufacturing processes has received a lot of attention in last years. This is due to their versatility and to the possibility to concentrate high powers over small areas. In this paper the transient two dimensional thermal field in a solid irradiated by a moving Gaussian laser beam has been numerically analyzed. The numerical simulation allows for both surface heat losses, convective and radiative, and variable thermophysical properties. Three cases are considered: one is related to an adiabatic workpiece, the other two to a diabatic workpiece with a constant or variable heat transfer coefficient on the upper and lower surfaces. Results show that a local quasi-steady state condition is reached after a time that is much larger when the solid is adiabatic than the cases with constant or variable heat transfer coefficient. Thermal gradients along the depth decrease as z and x coordinates increase.
The Smart Parcel Concept for Condition Monitoring of Materials Handling Machinery
Authors: Walker Gavin J. , Zorriassatine Farbod , Parkin Robert M. , Jackson Mike R. , Coy Joanne
Published: November 2008

Complex machinery which bears loads over large distances requires a large capital outlay to monitor condition at many points. Hand-held monitoring units necessitate knowledgeable operators and are of limited use when applications involve areas inaccessible during operation. This paper presents the idea of deploying a ‘smart parcel’ to navigate the process, reporting on performance. Equipment was mounted on a receptacle belonging to such a machine, and sound data was recorded for later analysis. Frequencies present were compared with component characteristic frequencies in order to ascertain robustness of method as compared to traditional installations. The presence of common information and also some that are not obtainable by other means has rendered the theory a viable proposal.
Performance Enhancement of a Friction Damper System Using Bond Graphs
Authors: Ngwompo Roger F. , Guglielmino Emanuele , Edge Kevin A.
Published: November 2008

This paper describes a study of the performance of a servo-driven dry-friction damper employed in a vehicle suspension application. The damper is force-controlled via an electrohydraulic pressure control system. Previous experimental work showed that the theoretically predicted system performance does not reflect actual system behaviour because of both the residual back-pressure which produces an undesired constant-amplitude damping force and reduced hydraulic system bandwidth due to presence of free air within the hydraulic fluid. Possible solutions are proposed and performance assessed against a simulated system with dynamic performance purposely worsened. The first issue can be addressed by spring-preloading the friction damper so as to compensate the constant force caused by the residual back-pressure. The second issue can be tackled by closing a local pressure control loop around the control valve. The friction damper is controlled by a variable structure scheme that performs spring force compensation tracking. Bond graphs are employed as a tool for modelling and designing the control system.
Necessary and Sufficient Conditions for Delay-Dependent Asymptotic Stability of Linear Discrete Large Scale Time Delay Autonomous Systems
Authors: Stojanovic S. B. , Debeljkovic D. Lj.
Published: November 2008

This paper offers new, necessary and sufficient conditions for delay–dependent asymptotic stability of the linear discrete large scale time delay systems. It has been shown that asymptotic stability this class of systems can be mapped to the asymptotic stability of the corresponding so called ith discrete SES systems. The order of the SES system is manifold lower than the order of the observed large scale systems. At that, it necessary to solve system of matrix equations whose solution always exists. Using the feature that the observed large scale system is finite-dimensional, necessary and sufficient condition of stability was derived independent of time-delay, which is based on the equivalent matrix of the system, whose order is considerably higher than the corresponding SES system. Numerical computations are presented for illustration.
Application of Modal Analysis to Damage Detection in Composite Laminates
Authors: Hu Huiwen , Wang Bor-Tsuen , Su Jing-Shiang
Published: November 2008

A nondestructive detection of damage in composite laminates by using modal analysis is investigated in this paper. Continued fiber-reinforced composite AS4/PEEK was used to fabricate a symmetrical laminate plate and a surface crack was created in one side of the laminate plate. The results of modal testing are presented for the application of modal analysis to the laminate plate before and after damage. Changes in mode shapes, mode shape slopes and strain energies were used to calculate the damage index for indicating the damage location. Differential quadrature method (DQM) was introduced to solve the problem of partial derivatives function in strain energy formula. A 3-D finite element model was created for comparison with the experimental results. The model accurately predicted the dynamic responses. It was found that damage index using strain energy method provides a more promising result than other methods in locating the damage.
Modeling the Shape Control of Beam Structures by Shape Memory Alloy Actuators
Authors: Ghorashi Mehrdaad
Published: November 2008

In this paper, the application of an actuator wire made of shape memory alloy (SMA) and externally attached to a cantilever beam is analyzed. To this end, an integrated model that includes the constitutive equations of the SMA, the phase transformation equations from martensite to austenite and vice versa, the heat transfer equation for the SMA that also includes the input energy from an electric source, and the equations of the elastic deformation of the cantilever beam as well as the SMA wire, is presented. The simultaneous solution of the mentioned set of equations can result in the evaluation of the system response to an electrical activation of SMA.
Performance and Failure Analysis of Injection Molded Carbon Reinforced Nylon Gears
Authors: Senthilvelan S. , Gnanamoorthy R.
Published: November 2008

Reinforced polymers offer superior strength and modulus required in many load-bearing applications. Reinforced thermoplastic polymer gears are used in motion as well as power transmission applications. The performance of reinforced polymer gears needs to be thoroughly understood for widening their application. This paper describes results of the ongoing research on polymer composite gear performance. Unreinforced and 20% short carbon fiber reinforced Nylon granules were used for the development of gears using injection-molding process. Gear tests were conducted in a power absorption type gear test rig. Gears were tested at a constant rotational speed of 1000 rpm and at various torque levels up to 3 Nm. Test results showed the superior fatigue strength of carbon reinforced Nylon gears compared with the unreinforced Nylon gears. Improved thermal resistance, high strength and modulus contributed to the superior fatigue performance of carbon reinforced Nylon gear. Failed and worn out surfaces were observed using optical and scanning electron microscope. Three major gear failure modes were observed; excessive wear, severe deformation and tooth fracture. Fiber orientation, presence of fiber particles between contact surfaces and poor surface finish affects the wear resistance of carbon-reinforced gear.
Design for Patient Safety: A Review of the Effectiveness of Design in the UK Health Service
Authors: Clarkson P. John , Ward James , Buckle Peter , Stubbs Dave , Coleman Roger
Published: November 2008

The Department of Health and the Design Council jointly commissioned a scoping study to deliver ideas and practical recommendations for a design approach to reduce the risk of medical error and improve patient safety across the NHS. The research was undertaken by the Engineering Design Centre at the University of Cambridge, the Robens Institute for Health Ergonomics at the University of Surrey and the Helen Hamlyn Research Centre at the Royal College of Art. The research team employed diverse methods to gather evidence from literature, key stakeholders, and experts from within healthcare and other safety-critical industries. Despite the multiplicity of activities and methodologies employed, what emerged from the research was a very consistent picture. This convergence pointed to the need to better understand the health care system as the context into which specific design solutions must be delivered. Without that broader understanding there can be no certainty that any single design will contribute to reducing medical error and the consequential cost thereof.
Residual Stress and Circumferential Stress Distribution in a Finite Element Model of the Arterial Wall
Authors: Haghighipour Nooshin , Tafazzoli Shadpour Mohammad , Avolio Albert
Published: November 2008

Stress distribution of the arterial wall is an important factor in biomechanics of arteries. It has been suggested that excessive stress leads to arterial degeneration and lesion formation. In addition to circumferential tensile stress caused by luminal pressure, arterial wall contains circumferential residual stress with compressive and tensile components with maximum values on intima and adventitia respectively. The compressive residual stress component compensates part of maximum tensile stress, and therefore decreases severity of tension on endothelial lining. If an arterial ring is cut in radial direction it opens. The degree of opening angle is a determinant of circumferential residual stress. In this investigation, Finite element modeling was used to evaluate circumferential residual stress in a typical model of cross section of human aorta with differing opening angle and Young’s modulus of elasticity. Results show that residual stress values are influenced by structural and mechanical parameters. Elevation of the opening angle and stiffening of the arterial wall resulted in increase of residual stress level.
A Micro-Fluidic Real-Time Monitoring of the Dynamics of Polymeric Liquids
Authors: Viola Ilenia , Cingolani Roberto , Gigli Giuseppe
Published: November 2008

Manipulating liquid fluids within networks of micro-channels is crucial in the fabrication of micro-fluidic devices for electronic and for medical applications, as well as for the fundamental understanding of the fluid dynamics properties in geometrical confined systems, in which localization phenomena and surface effects can strongly affect the fluid behaviour. A detailed analysis of the fluid dynamics properties is particularly important for glass-forming liquids, polymeric solutions or bio-fluids, which do not behave as Newtonian fluids, due to the the elasticity of the molecules. For these materials the determination of the structural dynamical parameters is not trivial, requiring the solution of a complex many body problem and the introduction of non-linear mechanical parameters. In this work we have provided a micro-fluidic approach to assess the structural rheological parameters of a glass-forming liquid under real operation conditions. The method was applied to a viscoelastic polymeric liquid, polyurethane (PU) adhesive, during its driving flow in a micro-capillary network.
Thermal Design of Uniformly Heated Vertical Convergent Channels in Natural Convection in Air
Authors: Bianco Nicola , Langellotto Luigi , Manca Oronzio , Nardini Sergio
Published: November 2008

In this paper, design charts for the evaluation of thermal parameters for natural convection in air in a vertical convergent channel are proposed. In the thermal analysis of natural convection in a convergent channel, the parameters that play an important role are: the heat flux, maximum wall temperatures and geometrical parameters such as the length of the heated walls, the minimum and maximum channel sections. A simple numerical procedure to obtain the thermal design charts is presented. Results are carried out for symmetrically heated channels with walls at uniform heat flux. Some simple examples are given to show the use of the charts. The proposed charts are obtained from data resulting from numerical investigation in the following parameter ranges: angles of convergence not greater than 10 deg, surface emissivity between 0.10 and 0.90, 30 ≤ (qc + qr)≤ 220 W/m2, 2.0 ≤ L/bmax ≤ 60 and 0.030 ≤ bmin/bmax ≤ 1.0.
Manufacturing of Micro-Ridges and Micro-Gears by Laser Ablation
Authors: Liess Helmar , Heinzl Joachim
Published: November 2008

The aim of this development presented in this paper is to enhance the possible field of applications for the manufacturing of micro ridges and micro gears by laser ablation. For the processing of the interlocking two different laser systems were investigated. By means of an Nd:YAG-IR-Laser with a wavelength of 1064 nm and a third harmonic Nd:YAG-UV-Laser with a wavelength of 355 nm several materials such as hardened steel were grooved. For the adjusting of the work pieces high-precision translation and rotation stages were used. The described setup allows the fabrication of micro-ridges in several materials such as steel and copper with tooth pitches of 60 μm and length up to 300 mm. Furthermore micro-gears with modules of 0,038 and gear reduction up to 182:1 were processed.
A Three Dimensional Parametric Human Spine Model Generation
Authors: Ceran Murat , Acar B. Serpil
Published: November 2008

The human spine is a geometrically, non-linear complex structure. Solid models are widely used in spine modelling studies. There is a need for developing a generic parametric spine model to be employed in biomechanical modelling of the spine to reduce the complexity of the dimensions and orientations. In this proposed parametric model, the geometric complexity of the vertebrae is simplified by associating the geometry of the significant anatomic properties of the spine. This is achieved by identifying and employing the key parameters of geometric components. The features of each vertebra are generated by using these key parameters. These features are then combined to generate the model of a particular vertebra. The variables of this generic vertebra can then be edited to model the whole spinal column. The proposed technique helps the potential user to edit the variables with less effort, in order to form a realistic model of the full spine to represent different groups of people with different dimensions and postures.
The Packaging and Labelling of Solid Oral Medicine Using Oral Methotrexate as an Example
Authors: Ward James , Clarkson P. John , Buckle Peter , Harris Wendy
Published: November 2008

Solid oral Methotrexate (Methotrexate in tablet form) has been used for many years as an effective measure to treat severe rheumatoid arthritis and severe psoriasis. When taken at the right frequency and dose Methotrexate is a safe medication. However, in the community in the UK between 1993 and 2000, Methotrexate has been implicated in the deaths of some 25 patients and a further 26 cases of serious harm which have required hospitalisation [1,2]. In 2003 the National Patient Safety Agency (NPSA) began a programme of work to investigate the causes of errors with Methotrexate and to develop and implement solutions in response. Since then, three projects have been undertaken: • The development of a new patient treatment diary; • An investigation of IT systems in GP’s surgeries and community pharmacies; and • An assessment of the packaging and labelling of Methotrexate with patients and healthcare practitioners and the identification of changes which should improve patient safety. This paper describes the research and results from the third project.
Product- and CAD-Structure Planning Processes for Mass Customization Products
Authors: Maurer Maik , Janitza Dennis , Ott Alexander
Published: November 2008

Mass Customization (MC) is one approach to deal with the continuous increasing demand for individualized products. It’s major objective is to offer products with delivery times and prices comparable to mass produced goods. Hereby assigned possibilities are not only limited to the customization of appearance but affect a multitude of customer requirements, e.g. functions, technical attributes, or structural arrangements. Two major steps in designing customizable products are the product structure planning and the designing of CAD-models. The work presented in this paper specifies the mutual interdependencies as well as the data, which has to be exchanged in this alternating process. For an iteratively optimized planning of customizable products, knowledge will be extracted from parametric design for a further adaptation in the product spectrum structure. Using appropriate algorithms, the need for structure modifications will be derived, with the objective of eliminating critical interdependencies from the basic structure. The alternating data exchange between parametric product modeling and abstract structure planning helps to integrate bi-directional requirements (e.g. new techniques in manufacturing) or boundary conditions appearing at different design phases.
A Risk Analysis Procedure for Aeronautical Components
Authors: Soprano Alessandro , Caputo Francesco , Lamanna Giuseppe
Published: November 2008

This work describes a risk assessment procedure which has been developed by the authors to analyse the spreading of fatigue-induced damage in typical aeronautical components, also taking into account the effects of maintenance. The general model adopted in this procedure is based on a Markov propagation process, embedded in a Monte Carlo global integration strategy. The main feature of such a procedure is related to the modelling of the damage evolutionary process, not only to define the damage initiation step, but also to evaluate the transitional probabilities which characterize the passage from one damage level to a higher one and which is obviously related to time and to the damage state of surrounding zones. The evaluation of such transitional probabilities is often carried out by means of a mixed procedure, by using a probabilistic technique for the initiation phase and a deterministic one for propagation phase; in this work a fully probabilistic procedure has been considered.
Simulation of Roll Grinding System With Double Regenerative Chatter
Authors: Yuan Lihong , Ja¨rvenpa¨a¨ Veli-Matti , Keskinen Erno
Published: November 2008

In this paper dynamical analysis of a grinding process in steel roll manufacturing is studied. The main sources of the regenerative chatter are the time delay effects from both work piece and tool surfaces. The dynamical behaviors of the system have been described in a multi-degree-of-freedom (MDOF) simulation model and both responses of the roll and the grindstone motions have been considered. The conventional controllers are included in order to achieve the desired rotational speeds of the two spindles. The simulation results of the model with double time delays will be carried out and the special characteristics of the system stability relative to delays will be discussed through analysis.
The Need for a Component-Based Approach to Automation Systems for Agile Manufacturing
Authors: Lee Szer Ming , Ong Min Huey , Harrison Robert , West Andrew A.
Published: November 2008

Manufacturing enterprises are facing new challenges caused by unprecedented changes due to volatile market demands. Such changes have direct impact to the design, implementation and operation of automation systems in the domain of automotive production. An in-depth study in the activities of building and operating automation systems in the domain of automation manufacturing has revealed weaknesses in current practices and in particular an inability to cope effectively with production changes. It is envisaged that a component-based approach will enable an automation system to be designed, implemented and modified quickly and effectively, thereby increasing the agility, responsiveness and changeability of the system. This paper investigates the impact of market demands on the lifecycle of automation systems in the automotive manufacturing and proposes a novel component-based approach suitable for automation system design and implementation.
Dynamical Behaviour of Piezoelectrical Cantilever Beams in an Inkjet Printhead
Authors: Scheicher Richard , Heinzl Joachim , Ott Alexander
Published: November 2008

In this paper, the functional principle of an inkjet printhead for different applications is explained. Using displacement effects the printhead is insensitive to gas bubbles and can be used for various fluids to generate droplets with volumes of less than 100 picoliters. The actuator is a composite of a piezoelectrical ceramic and a passive silicon beam. For tests, several systems with different geometries and a physical resolution up to 150 dpi were built. To verify the dynamical behaviour of the printhead in dependence of the dosing fluid, several measurement configurations and two test stations are used. With a stroboscopic vision system the generated droplets can be visualised and the diameter and the velocity of the droplets can be measured. The dynamical behaviour of the actuators in the fluid can be detected with a Laser-Doppler-Vibrometer. Thus, possible interactions between the single actuators can be measured. At last, the results of the measurements contribute to the verification of a theoretical compact model for a system simulation. This simplified model allows short time parameter studies to optimize the fluid flow, the activation signals, the interactions between the actuators and the geometry.
Reactor Safety Analysis Based on a Developed Two-Phase Compressible Flow Simulation
Authors: Nowakowski A. F. , Librovich B. V. , Lue L.
Published: November 2008

The direct numerical simulation of multiphase flow is a challenging research topic with various key applications. In the present work, a computational simulation of multi-phase compressible flow has been proposed for safety analysis of chemical reactors. The main objective of a pressure relief system is to prevent accidents occurring from over pressurisation of the reactor. We are particularly interested in understanding the phenomena associated with emergency pressure relief systems for batch-type reactors and storage vessels. Existence of multiphase flow is significantly influenced by the interface between the phases and the associated discontinuities across the phase. The approach, which builds on the method first introduced by Saurel and Abgrall [1], was developed for solving two-phase compressible flow problems. Each phase is separately described by conservation equations. The interactions between two phases appear in the basic equations as transfer terms across the interface. The equations are complemented by state equations for the two phases and by additional correlations for the right-hand side coupling terms. The method is able to deal with multiphase mixtures and interface problems between compressible fluids. The key difference compared to classical two-fluid model is the presence of separate pressures fields associated with phases and introduction of pressure and velocity relaxation procedures. The relaxation operators tackle the boundary conditions at the interface and consequently the model is valid for fluid mixtures, as well as for pure fluids. The numerical technique requires the system to be decomposed and involves a non-conservative hyperbolic solver, an instantaneous pressure relaxation procedure and source term operators. The solution is obtained by succession of integrators using a second-order accurate scheme. The ultimate goal of this research is to use the method for studying the venting problem in reactor systems after verifying its performance on a series of standardised test cases documented in the literature.
Lubricating Oil Condition Monitoring Using Vibration and Air-Borne Acoustic Measurements
Authors: Albarbar A. , Gennish R. , Gu F. , Ball A.
Published: November 2008

Modern diesel engine maintenance programs incorporate various methods and techniques for early fault detection and diagnosis to maintain efficiency, low pollution and high reliability and to avoid catastrophic failures. This study has been conducted aiming at engine oil condition monitoring and quality evaluation by analysing the engine block vibration and its induced noise. The vibration signals were measured using an accelerometer mounted on the thrust side of the first cylinder in a four cylinder diesel engine, and the noise was recorded using a microphone facing the cylinder. The signals are then band pass filtered and transformed to the frequency domain, where the amplitudes of the different frequency components of the vibration and noise waveforms are analysed and compared to the vibration and noise baseline signatures. The mean amplitudes of the spectral components in the frequency band 900 Hz to 2.5 kHz were found linearly proportional to the engine speed and load. It was also found that the RMS values of this frequency band are affected by the oil viscosity. These results show that it is possible to use vibration and airborne acoustics to predict the quality of lubrication.