bluuebunny/crossref_metadata_2025 huggingface dataset:
The Case for Lateral Stiffness in Walking Orthoses for Paraplegic Patients
Authors: Stallard J , Major R E
Published: February 2007

The provision of walking for paraplegic patients has therapeutic benefits but must be at a low energy cost. Although claims have been made regarding the need for high lateral stiffness in any orthosis targeted at this group, much of the supporting evidence was confusing. This paper presents the theoretical reasoning behind this claim and reviews recent evidence that would appear to support it.
Friction and Lubrication in Cushion Form Bearings for Artificial Hip Joints
Authors: Auger D D , Dowson D , Fisher J , Jin Z-M
Published: February 2007

Two hip joint prostheses were designed and constructed to be elastohydrodynamically equivalent producing approximately equal initial contact areas and theoretical film thicknesses. One was made from conventional UHMWPE (ultra-high molecular weight polyethylene) and the other was a cushion component which had a low modulus layer introduced into the joint space. Friction measurements were carried out on a pendulum simulator apparatus and the two joints were compared. In addition the experimental results were compared with theoretical values of friction predicted from elastohydrodynamic lubrication theory. Values for the friction factor at peak load and peak velocity in the cushion cup (0.003–0.009) were much lower than in the UHMWPE cup (0.017–0.042). The low friction values in the cushion cup are consistent with fluid film lubrication in the contact with the thin lubricating film being preserved by microelastohydrodynamic action.
Sliding Friction Analysis of Phosphatidylcholine as a Boundary Lubricant for Articular Cartilage
Authors: Williams P F , Powell G L , LaBerge M
Published: February 2007

Dipalmitoyl phosphatidylcholine (DPPC), the major lipidic component of the synovial fluid (45 per cent), has been implicated in previous studies in synovial joint lubrication as a potential boundary lubricant for articular cartilage. The purpose of this study was to evaluate the effectiveness of DPPC as a boundary lubricant at physiological stresses experienced by weight-bearing joints (up to 7.5 MPa). The sliding coefficients of static and kinetic friction for glass surfaces coated with DPPC layers of physiological thickness (70 nm) were measured as a function of average contact stress, contact geometry (point and line), applied load and relative velocity (from 25 to 0 mm/s) and compared to the coefficient of friction for clean glass in the same conditions. The coefficient of friction for DPPC-lubricated surfaces was dependent on contact geometry, obeyed Amonton's law (not dependent on axial load or contact area), was dependent on relative velocity within the range stated and was an effective lubricant at physiological stresses.

This study showed that dipalmitoyl phosphatidylcholine can be an effective boundary lubricant at stresses observed in load-bearing joints. Because of their surface-active nature, these adsorbed molecules might also act as a protective layer for the articular surfaces.
A Method for the Kinematic Evaluation of the Knee following Anterior Cruciate Ligament Injury and Reconstruction
Authors: Long A J , Monsell F P , Porter M L , Bowker P , Hukins D W L
Published: February 2007

A quantitative method for assessing the kinematics of the knee in the sagittal plane has been developed in order to evaluate the role of the anterior cruciate ligament following injury and reconstruction. Measurements were made on a series of lateral radiographs obtained at different angles of flexion with the limb weight-bearing and the foot and ankle rotated so that the condyles of the femur overlapped. The kinematics of the joint were then defined by recording the path of the tip of the medial tibial spine as flexion proceeded, using a coordinate system based on the femur. This method overcomes the problems inherent in quantifying knee kinematics by using the pathway of the centre of rotation. In an amputated knee, tibial positions could be specified to within approximately 1.2 mm. There were no significant differences between results obtained at the beginning and end of a six month period for the normal knees of two patients; the standard deviation of the measured tibial positions was approximately 1.6 mm.
Examination of Alumina Ceramic Components from Total Hip Arthroplasties
Authors: Nevelös A B , Evans P A , Harrison P , Rainforth M
Published: February 2007

Materials analysis has been conducted on retrieved Mittelmeier-Autophor ceramic components from total hip arthroplasties, correlating articulating surface wear morphology with clinical reasons for failure.

Plastically deformed, agglomerated wear debris (30–60 μm) has been identified on femoral head articulation wear surfaces, displaying exaggerated wear, especially during the initiation stage. Such surfaces were associated with clinical failures involving displacement of the acetabular cup and perforation of the cortex by the femoral stem, It is thought that this wear debris may play an important role in the promotion of the ‘avalanche’ wear mechanism, as it is adherent and thus difficult to remove from the wear interface
Optimal Design of a Six-Bar Linkage with One Degree of Freedom for an Anthropomorphic Three-Jointed Finger Mechanism
Authors: Guo G , Zhang J , Gruver W A
Published: February 2007

This research concerns the design of a three-jointed, anthropomorphic, finger mechanism for use as a prosthesis or robotic end-effector. Based on a study of finger configurations for the human hand, a six-bar linkage with one degree of freedom is proposed. A model of the fingertip displacement of the mechanism is derived by a vector analysis approach. The effects of joint friction on the transmission efficiency are analysed. By measuring the joint positions of a human finger, a mathematical model of the pinching and holding configurations are developed. Optimal parameters for the finger mechanism are obtained by non-linear programming based on an objective functional involving motion posture and locus, transmission efficiency and weight subject to geometric and bionic constraints. Simulation results indicate that the mechanism is useful for a variety of prosthetic and robotic applications.
Asperity Lubrication in Human Joints
Authors: Yao J Q , Unsworth A
Published: February 2007

The asperity lubrication in human joints is examined in the present paper, with particular reference to the tertiary undulation with wavelengths of around 20–45 μm. It was found that, under dynamic physiological loading conditions, the secondary waviness of the cartilaginous surface (typically 0.5 mm wavelength) could be effectively flattened to sustain a fluid film of 0.1–0.3 μm thick, while the tertiary waviness could be squashed to sustain a much thinner fluid film of 0.01 μm (10 nm) thick with normal synovial fluid as the lubricant. The calculated film thickness for the tertiary undulation was less than 5 nm when the ankle joint was lubricated by Ringer's solution or pathological synovial fluids, or when only quasi-static loading conditions were considered, while a sufficiently thick fluid film could still be formed when the secondary undulations were considered alone. It was thus suggested that the fluid film lubrication mechanism was operative for human joints with normal synovial fluid as the lubricant under physiological dynamic loading conditions and the mixed lubrication mechanism could take over when static loading conditions prevailed or when watery lubricants (n ≈ 0.001 Pas) were used.
Finite Element Analysis of Poor Distal Contact of the Femoral Component of a Cementless Hip Endoprosthesis
Authors: Taylor M , Abel E W
Published: February 2007

The difficulty of achieving good distal contact between a cementless hip endoprosthesis and the femur is well established. This finite element study investigates the effect on the stress distribution within the femur due to varying lengths of distal gap. Three-dimensional anatomical models of two different sized femurs were generated, based upon computer tomograph scans of two cadaveric specimens. A further six models were derived from each original model, with distal gaps varying from 10 to 60 mm in length. The resulting stress distributions within these were compared to the uniform contact models. The extent to which femoral geometry was an influencing factor on the stress distribution within the bone was also studied.

Lack of distal contact with the prosthesis was found not to affect the proximal stress distribution within the femur, for distal gap lengths of up to 60 mm. In the region of no distal contact, the stress within the femur was at normal physiological levels associated with the applied loading and boundary conditions. The femoral geometry was found to have little influence on the stress distribution within the cortical bone. Although localized variations were noted, both femurs exhibited the same general stress distribution pattern.
Multi-Step Ahead Prediction Based on the Principle of Concatenation
Authors: Kaynak M O
Published: February 2007

In long-range predictive control schemes, multi-step ahead predicted values can be arrived at by concatenating the unit step predictions. In doing this, the missing outputs are replaced by their previously predicted values. This approach is much simpler than the approach commonly adopted in the literature which is based on the solution of an identity. The paper concludes with the formulation of the scheme for the trajectory control of a servo-system.
Sensitivity Computation via Algebraic Manipulations
Authors: Szczepaniak P S
Published: February 2007

The problem of determination of sensitivity functions with respect to variations in system parameters and in the initial state is solved for linear dynamic systems using the orthogonal series approach. By means of this technique the problem becomes algebraic. A simple relation between the solutions of a class of matrix algebraic equations is derived. This important algebraic result, applied to the approximate sensitivity problem, leads to a significant simplification of the computational procedure and reduces the computational effort.
Fault Detection Using Reduced Order Models
Authors: Daley S , Wang H
Published: February 2007

Based on the reduction of dynamic system models, an algebraic redundancy method is proposed which consists of fault detection through the redundant variables and fault diagnosis using a diagnostic matrix. This diagnostic matrix approach, which is an extension of the influence matrix method, is capable of identifying different combinations of failure modes. It is shown that this method can produce a correct diagnosis for the failure of sensors and actuators and can also detect changes in the system parameters. A simulation of a three-shaft gas turbine is used to demonstrate the potential of the method.
An Unsteady Prescribed Wake Model for Vertical Axis Wind Turbines
Authors: Coton F N , Jiang D , Galbraith R A McD
Published: February 2007

This paper describes the development of a fully unsteady three-dimensional aerodynamic performance prediction scheme for vertical axis wind turbines (VAWTs). The method is based on the prescribed wake approach of Basuno in which the turbine is represented by a series of bound vortex segments from which emanates a wake consisting of shed and trailing vorticity filaments. Unlike a free vortex method, these wake filaments are constrained to follow a predetermined path, the shape of which is dictated by momentum considerations. By coupling this technique with the unsteady aerofoil performance method of Leishman and Beddoes, a fully unsteady V AWT model is developed. The difficulties associated with coupling the two techniques are discussed and a new formulation for the tangential blade force is introduced. The resulting calculation scheme is shown to agree well with field data from a straight bladed vertical axis wind turbine, even at very low tip speed ratios.
A Quasi-Steady Performance Prediction Model for Dynamic Characteristics of a Volute Pump
Authors: Thanapandi P , Prasad R
Published: February 2007

A performance prediction model generally applicable for volute-type centrifugal pumps has been extended to predict the dynamic characteristics of a pump during its normal starting and stopping periods. Experiments have been conducted on a volute pump with different valve openings to study the dynamic behaviour of the pump during normal start-up and stopping, when a small length of discharge pipeline is connected to the discharge flange of the pump. Such experiments have also been conducted when the test pump was part of a hydraulic system, an experimental rig, where it is pumping against three similar pumps, known as supply pumps, connected in series, with the supply pumps kept idle or running. Instantaneous rotational speed, flowrate, and delivery and suction pressures of the pump were recorded and it was observed in all the tested cases that the change of pump behaviour during the transient period was quasi-steady, which validates the quasi-steady approach presented in this paper. The nature of variation of parameters during the transients has been discussed. The model-predicted dynamic head-capacity curves agree well with the experimental data for almost all the tested cases.
Development of the Trilateral Flash Cycle System Part 2: Increasing Power Output with Working Fluid Mixtures
Authors: Smith I K , da Silva R Pitanga Marques
Published: February 2007

The trilateral flash cycle system is a proposed means of power recovery from single-phase low-grade heat sources. Its feasibility depends on the efficient adiabatic expansion of light hydrocarbons from the saturated liquid phase into the two-phase region. Such a process is performed most effectively with a Lysholm twin-screw expander when the exhausted vapour is wet. At higher temperatures, when multi-stage expansion is required, working fluids may be found which complete the process as dry saturated vapour. It is shown that at condensing temperatures of 0–50°C, this is possible with a mixture of n-pentane and 2,2–dimethylpropane (neopentane) for fluid inlet temperatures in the 150–180 °C range. A radial inflow turbine may then be used in place of a screw for the last stage. With such an arrangement, expander adiabatic efficiencies of up to 85 per cent have been predicted for power outputs in excess of 5 MW. The method of fluid property estimation is described and its accuracy confirmed by experiment.
Design and Performance of Vaneless Volutes for Radial Inflow Turbines: Part 3: Experimental Investigation of the Internal Flow Structure
Authors: MacGregor S A , Whitfield A , Noor A B Mohd
Published: February 2007

An experimental study is presented which considers the flow structure in the vaneless volute of a radial inflow turbine. The data show evidence of significant secondary flows around the volute. The volute tested generated a uniform ‘free vortex’ type structure and produced a uniform mass flow distribution around the periphery of the rotor. The flow within the volute was turbulent although this did not appear to have a detrimental effect on the overall performance of the volute. However, the turbine performance appears to be insensitive to variations in the inlet conditions in the axial direction.
The Implementation of a Feature-Based Component Representation for CAD/CAM Integration
Authors: Case K , Gao J X , Gindy N N Z
Published: February 2007

Recent research and development has the objective of increasing productivity and cost effectiveness by integrating many activities such as design, analysis, process planning, assembly planning and production planning which encompass the entire manufacturing planning and operational control aspects of a manufacturing enterprise. It has been recognized that a key to the integration lies in the determination of a representation scheme for products that can be interpreted for the various needs of these different applications. Geometric (solid) modellers were regarded by many researchers as the appropriate representation, but more recently a features approach has been proposed to enhance the capabilities of solid modellers.

This paper introduces ongoing research which is aimed at the development of a feature-based design system for process planning. The system is fully integrated with a conventional boundary representation (Brep) modeller which enhances its modelling capabilities in representing, editing and validating features of components. The main aspects of the feature-based design system are described in detail, such as the feature library, feature taxonomy, feature operations, feature relationships and tolerances. The generation of a detailed data model for transmission to manufacturing planning activities is also described and demonstrated by reference to an example component. A brief indication is given of our parallel research work in using such models as the basis of process planning and process capability modelling.
Self-Tuning Control of Cutting Force for Rough Turning Operations
Authors: Allen R , Huang K
Published: February 2007

Considerable developments have taken place in recent years in the versatility and sophistication of computer numerical control (CNC) controllers. Machine tool control schemes have not, however, advanced to the same extent. Control of the metal cutting process has long been advocated as a goal to pursue to improve productivity, but progress has been slow.

This paper introduces a simplified generalized minimum variance approach to self-tuning which shows promise for the adaptive control of metal cutting. An experimental rig is described and the results of tests to adaptively control the vertical component of cutting force during rough turning operations by manipulating the feedrate are presented. A simulation of the rig was also developed and used as an initial testbed for adaptive control techniques.
A Study of Mechanical Stress Relief (MSR) Treatment of Residual Stresses for One-Pass Submerged Arc Welding of V-Grooved Mild Steel Plate
Authors: Bae K-Y , Na S-J , Park D-H
Published: February 2007

The heat-transfer and thermal stress distributions in one-pass submerged arc welding (SAW) were numerically determined using the finite element method (FEM) for a V-grooved rectangular steel plate in which the weld preparation was filled during welding. A two-dimensional non-linear heat-transfer analysis was performed for a transverse section of the plate. This was followed by a thermo-elasto-plastic transient thermal stress analysis, assuming plane strain to be constant for the same model section. The same stress model was used to simulate a mechanical stress relief (MSR) treatment of the plate. This has frequently been used in the fabrication of large pressure vessels instead of post-weld heat treatment (PWHT). In this way its effect in reducing the residual stress in the welded plate was investigated. MSR was simulated by enforcing a constant displacement loading in the welding direction.

The solution of the thermal stress analysis showed that it was possible for the residual stress around the weld centre to be accurately estimated by accurate modelling of the dilution of the filler metal in the fused zone of the base metal. The conclusion derived from the MSR simulation was that it could quantitatively predict the effect of reducing the residual stress in the welded plate. Only limited experimental data were available. The mechanism of stress reduction was plastic straining in regions of high residual stress. The amount of stress reduction at the weld centre had a linear relationship to the magnitude of the external stress relieving load. The numerical results for the MSR simulation agreed fairly well with experimental ones obtained from the MSR test performed on a welded plate.
A Functional Data Model for Assemblies Used to Verify Product Design Specifications
Authors: Baxter J E , Juster N P , de Pennington A
Published: February 2007

During the design of a product periodic reviews must be conducted to verify that the product will meet its specification. However, there are few, if any, computer-based design systems that aid in engineering processes other than those involving low-level geometry. This paper describes two applications that use a functional representation of a product to aid the designer during the redesign process. The applications are aimed at assisting designers in checking that a design meets all the requirements in a product's specification. The form of the data used by the applications is defined by a data model that allows the representation of the function of each feature, component and assembly in the product. This functional data model has the strength that it can represent a product as both a structural and a functional hierarchy. The paper concludes by describing results of experiments using a mechanical engineering product as a case study.
New Applications of Non-Destructive Testing in Metal Forming Technology
Authors: Engel U , Schwind M , Stancu-Niederkorn S
Published: February 2007

In forming technology non-destructive testing (NDT) methods are already quite established in basic and industrial research as well as in practice. Due to the continually enhanced capabilities of these methods, new fields of application can be expected in future. In this paper recent developments in experimental and evaluation techniques for three such new applications are presented. The first is the ultrasonic in situ inspection of the real contact area (RCA) between billet and tool in upsetting. It is demonstrated that the evolution of the RCA during the forming process can be measured with high lateral resolution and good reproducibility. The second application deals with the examination of the state of pre-stressing of extrusion dies reinforced by a stress ring. Again the ultrasonic method is applied and is shown to be suited to give detailed information about the conformity of the reinforcement. Finally, the well-known method of material characterization based on the magneto-inductive principle is adapted to the task of on-line quality control in sheet metal forming. The applicability and efficiency of this method are verified by experimental results.
The Ideal Locations for the Contra-Rotating Shafts of Generalized Lanchester Balancers
Authors: Chiou S-T , Davies T H
Published: February 2007

The inertia of the moving parts of high-speed planar mechanisms creates a shaking force that is variable in magnitude, direction and line of action throughout a cycle. Alternatively, the instantaneous shaking force vector can be represented by an equal parallel force acting through an arbitrarily chosen origin, together with a moment about that origin. The two components of the force and the moment can be computed by kinetostatic analysis at discrete intervals of a cycle to create three arrays.

The discrete Fourier transform converts these arrays from the time to the frequency domain. The lowest frequency term of order k = 1 is of cycle frequency. Terms of higher order k > 1 have frequencies that are k times cycle frequency.

The shaking force frequency term of order k can be represented by two contra-rotating force vectors of constant, but generally unequal, magnitude rotating at k times cycle frequency. The forces can be eliminated by equal and opposite forces exerted by counterweights mounted on contra-rotating shafts rotating at the same speed. However, if the locations of these shafts are both arbitrarily chosen, a shaking couple of order k will generally remain unbalanced.

Fast Fourier transform (FFT) analysis of the array of moments as well as the force components enables suitable shaft locations to be determined in such a way that this couple vanishes. The couple vanishes if the balancing shafts are coaxial with a centre at an invariant location in the plane. The couple can also be eliminated even though the location of either shaft, but not both, is chosen arbitrarily. The location of the second shaft is then determinate and two procedures are explained to determine that location.
Simple Method for Evaluation of Fatigue Damage of Structures in Wide-Band Random Vibrations
Authors: Kim J J , Kim H Y
Published: February 2007

The note describes a simple method for evaluation of fatigue damage of structures in wide-band vibrations from response power spectral density data in the frequency domain. The method is applied to three sample cases and the results are compared with those of the damage calculation in the time domain.
A Spectral Feedback Compensation Technique for the Generation of Random Wave Fields
Authors: Rouillard V , Lleonart G T
Published: February 2007

Computer software was developed to control an electromechanical wave generator to accurately simulate random wave fields derived from mathematical spectral models. The software algorithm makes use of a spectral feedback control technique to improve accuracy and reliability in the continuous generation of random waves in the laboratory. Experiments were conducted to investigate the advantages of this closed-loop control technique over more commonly used open-loop random wave generation methods. The results show a decided advantage in using closed-loop control for the generation of random waves, especially for double-peak wave spectra and model testing purposes.
Generalized Frequency Response Functions for Systems with Time-Varying Coefficients
Authors: Belmont M R
Published: February 2007

An extension of the concept of frequency response is introduced which can be applied to systems described by differential equations whose coefficients vary periodically or almost periodically with time. Such systems are not accessible to traditional frequency response function methods because while the governing equations may be linear in the time domain they are non-linear in frequency. The basic theory of the technique is introduced and results are obtained for a wide range of systems. Time domain solutions are also deduced to complement the spectral development. Numerical results are calculated for an illustrative case that deals with a photochemical problem driven by a solar daylight cycle.
Turbulent boundary layer approach allowing chemical reactions for CO2 laser oxygen-assisted cutting process
Authors: Yilbaş B S , ŞSahin A Z
Published: February 2007

The present study presents a theoretical model for the laser gas-assisted cutting mechanism which includes the chemical reactions, momentum and assisting gas effects as well as that of conduction and convection. A heat-transfer model based on a boundary layer consideration has been adopted. In the analysis the relationship between the various parameters including power intensity, material thickness, gas jet velocity and cutting speed are predicted. A quantitative measure of chemical reactions between the molten and the assisting gas, evaporation of metal and the cooling effect of the gas jet are taken into account. The turbulent boundary layer over the molten metal is considered. An experiment is carried out to measure the cutting speed with different settings of laser power intensity. This provides a comparison between the theoretical predictions and experimental results. The experiment is extended to include monitoring of the initial plasma formation during the cutting operation. This enhances the understanding of the oxygen effect and initiation of the cutting process.
Frequency Equations and Modes of Free Vibrations of Rectangular Plates with Various Edge Conditions
Authors: Bert C W , Malik M
Published: February 2007

This paper considers linear free vibrations of thin isotropic rectangular plates with combinations of the classical boundary conditions of simply supported, clamped and free edges and the mathematically possible condition of guided edges. The total number of plate configurations with the classical boundary conditions are known to be twenty-one. The inclusion of the guided edge condition gives rise to an additional thirty-four plate configurations. Of these additional cases, twenty-one cases have exact solutions for which frequency equations in explicit or transcendental form may be obtained. The frequency equations of these cases are given and, for each case, results of the first nine mode frequencies are tabulated for a range of the plate aspect ratios.
Experimental Approach to Electrostatic Liquid Filtration Using a Single Fibre Model: Part 1: Effects of Base Oils and Additives
Authors: Yanada H , Takikawa Y , Yamamoto M
Published: February 2007

This paper deals with a fundamental investigation of an electrostatic liquid filter. Aiming at clarifying the capturing mechanism of contaminants on a collector and the relationships between the quantity of captured particles and various factors, experiments have been conducted using a single fibre model which uses a single fibre as a simplified model of the collector. The effects of base oil and additive have been investigated. The experiments have revealed that the electrification characteristics of particles in oil are strongly affected by the type of base oil and additive, and that the form and quantity of deposition of particles on a collector differ considerably from one combination of base oil, additive and additive concentration to another.
Brittle Fracture from a Sliding Hertzian Contact
Authors: Hills D A , Munisamy R L , Nowell D , Atkins A G
Published: February 2007

A simplified method of analysing the characteristic horseshoe cracks appearing behind a spherical indenter sliding along the surface of a brittle material, is described. The technique provides a reliable means of estimating the fracture toughness of the material and an explanation of the inter-crack spacing, which is found to be independent of the sliding speed.
Technical and Commercial Considerations for the Application of Titanium in Automotive Engines
Authors: Allen P G
Published: February 2007

Titanium alloys offer unique specific strength, fatigue and temperature capability characteristics. Substitution for steel in reciprocating engine components offers potential improvements in performance, vibration reduction and fuel efficiency. Issues such as alloy selection, processing, cost, benefits and demerits of using titanium for these components are addressed.
Synchronous Belt Materials and Belt Life Correlation
Authors: Dalgarno K W , Day A J , Childs T H C
Published: February 2007

This paper examines synchronous belt life through the determination of the life-limiting parameters within a belt drive. Six different belt constructions were life-tested, producing three failure modes: tooth root cracking, cord delamination and fabric separation. The life test results were then correlated to various tooth deflections within the belt run. The results of this examination were then used to draw conclusions about which material properties most influence the belt life. It is concluded that the tooth deflections at entry to and exit from the pulleys are most damaging, and that any material change which will increase the dynamic tooth stiffness will increase the belt life within the three failure modes encountered.
A Study of Nissan Motor Manufacturing (UK) Supplier Development Team Activities
Authors: Lloyd A R , Dale B G , Burnes B
Published: February 2007

This paper describes a study carried out on the role of the supplier development team (SDT) concept used by Nissan Motor Manufacturing (UK) (NMUK) to assist in the development of its suppliers. Among the major findings are that suppliers found it difficult to distinguish between the changes introduced as a result of SDT assistance and those arising from their overall relationship with NMUK. It was also not easy to quantify the effects of the SDT, although it was possible to identify benefits such as reduced scrap and less work in process arising from improvement activities undertaken with SDT support. The study found that suppliers are seeking to emulate NMUK's approach in a number of ways (for example changing their management structure, improving the role and status of supervisors, introducing team leaders and revising the payment system) and the NMUK approach, even though it was often more exacting, was preferred to that of its competitors.
Two-Dimensional Temperature Distributions of Combustion Chamber Surfaces in a Firing Spark Ignition Engine
Authors: Zhao H , Codings N , Ma T
Published: February 2007

This paper summarizes the development and application of advanced thermal imaging techniques to a spark ignition engine at the University of Cambridge Department of Engineering.

A thermal imaging system is described which is capable of viewing and recording the cylinder head surface temperature and piston surface temperature in a firing spark ignition engine. Two-dimensional temperature distributions of these surfaces were measured both during the engine's warm-up period and steady state operations. The influence of the engine's operating conditions was examined upon the temperature distributions of combustion chamber surfaces during the engine's warm-up period. The effect of spark timings, particularly the onset of knocking combustion on the surface temperatures, has been studied.
A Study of Multi-Dimensional Gas Flow in Engine Manifolds
Authors: Zhao Y , Winterbone D E
Published: February 2007

In this study, a three-dimensional Navier—Stokes solver was developed based on the finite volume fluid-in-cell (FVFLIC) method. The objective was to develop a comprehensive engine simulation tool that could predict unsteady flow features in the engine manifold and gas dynamic interaction between the intake system and the engine. Therefore the geometry effect of the manifold on gas dynamics could be fully investigated and later utilized in manifold design. Being shown here are some of the latest results of the research work aiming to validate the simulation program and apply it to the analysis of gas dynamics in manifolds for future design purposes.
Plasma Jet Ignition of Methanol at Sub-Zero Temperatures
Authors: Dawe J R , Smy P R , Haley R F , Dale J D , Bardon M F , Gardiner D P
Published: February 2007

Use of a pulsed plasma jet igniter to improve low-temperature starting of 100 per cent methanol (M100) fuelled engines is explored. A simple theoretical model of heat transfer from plasma to liquid methanol shows that sufficient energy is transferred for fuel vaporization in cold starting. Two laboratory experiments test liquid plane surface and droplet modes of ignition. An ordinary four cylinder auto engine fitted with plasma jet igniters is tested for cold starting in a Canadian winter, and cold starting is improved from +10°C (conventional ignition) to −16°C.
Design Optimization of Polyurethane Cored Three-Layered Carpeting
Authors: Ling M K
Published: February 2007

Multi-layered noise control systems are widely used in production vehicles to reduce interior noise levels. Traditionally, these systems had fibrous felt cores but increasingly moulded polyurethane (PUR) foam-backed carpets are now used. They provide the manufacturer with a single unit moulded car carpet, enabling easy and cheaper installation. However, little information has been published on their performance characteristics or their design optimization. This paper reports on work that examines the optimization of composite performance of these composites. A design model is developed which allows performance to be assessed before expensive road trials are carried out.
The Development and Validation of a Computer Aided Method for Design Evaluation of Tracked Vehicles with Rigid Links
Authors: Gao Y , Wong J Y
Published: February 2007

In the past decade, a computer aided method for design evaluation of high-speed tracked vehicles with flexible tracks (or tracks with relatively short track pitch commonly in use in tracked transport vehicles and military vehicles) has been developed. It has been successfully used in assisting vehicle manufacturers in the development of new products and governmental agencies in the selection of vehicle candidates. For low-speed tracked vehicles commonly in use in agriculture, construction and logging, rigid tracks with relatively long track pitch are employed to achieve a more uniform ground pressure distribution. To assist manufacturers of this type of vehicle to expedite the development of new products in a cost effective manner, a computer aided method for design evaluation of tracked vehicles with rigid links has recently been developed. It treats the track as a system of interconnected rigid links and takes into account the characteristics of the interaction between track links and deformable terrain. The basic features of the method have been verified by field test data. The method can be an extremely useful tool for the engineer to optimize vehicle design and for the procurement manager to select appropriate vehicle candidates to meet specific operating requirements.
The Development of the Speed Hill-Climb Car
Authors: Wood J R
Published: February 2007

This paper highlights the development of a very specialized class of race vehicle—the speed hill-climb car. The speed hill-climb discipline requires a unique set of performance parameters which places particular emphasis on traction. Historical development is traced through a review of successful cars to the top contenders of 1993 and the paper concludes with an examination of future trends.
Evaluation of a Cyclone-Based Particulate Filtration System for High-Speed Diesel Engines
Authors: Arcoumanis C , Barbaris L N , Crane R I , Wisby P
Published: February 2007

A cyclone-based filtration system has been developed and its potential for reduction of exhaust particulates in high-speed direct injection diesel engines is evaluated; the filtration efficiency of the four cyclones has been enhanced by means of particulate agglomeration induced by cooling in a heat exchanger. With this system installed in the exhaust pipe of a 2.5 litre direct injection engine, tests covering a wide range of speed, load and exhaust gas recirculation (EGR) fraction resulted in reductions of up to 77 per cent in emitted particulate mass flowrate. The dependence of the system's performance on engine operating conditions, EGR configuration and cyclone geometry is presented and discussed.
Numerical Simulation Method Applied to the Multi-Expansion Exhaust System of a Two-Stroke Engine
Authors: Chiou J-S , Chiang M-S , Chen C-K
Published: February 2007

A numerical method is presented to simulate the pressure wave in the multi-expansion exhaust system of a two-stroke engine. In the simulated processes, the inlet pipe, scavenge pipe and exhaust pipe of the two-stroke engine are simplifed by the pipe model, while the engine cylinder, crankcase and the expansion chamber are treated as the vessel model.

The cubic-interpolated pseudo-particle (CIP) method combined with the method of characteristics (MOC) is used to solve the hyperbolic equations. The results from simulation compare reasonably well with the experimental data.
Photoelastic Determination of Elastic and Plastic—Elastic Strain Distributions in Tube Plates
Authors: Fessler H , Hyde T H , Musson J K
Published: February 2007

These tube plates are the parts of boiler drums that contain triangular arrays of holes for the water (or steam) tubes. These drums are thin enough to be treated as flat plates in biaxial tension. Photoelastic coatings were bonded to eight models made of two boiler steels and the strain distributions around the holes and in the ligaments between the holes were determined for several loads. The results showed confined yielding around the holes before failure of the diagonal or axial ligaments under the 2:1 load ratio, which occurs due to pressure without ‘beam’ bending of the boiler drum.

A frozen stress test was also carried out to determine the elastic principal stresses in the ligaments of one geometry. The results showed that, in this diagonal ligament, along the straight line joining points of greatest elastic stress at the holes, the smaller principal stresses in the plane of the plate were also tensile, but only about 10 per cent of the greater principal stresses. This shows that, along these lines of likely failure, the photoelastic coatings underpredict the onset of yielding slightly.
Dynamic Characteristics in the Design of Maglev Suspensions
Authors: Goodall R
Published: February 2007

The paper reviews the essential functions which apply to any kind of suspension, and distinguishes between the various inputs to which a suspension is subjected. These are used to assess the particular characteristics of an electromagnetically suspended (Maglev) vehicle, and to identify considerations which have important implications for the controller design, irrespective of the design method. Some general equations are developed which interrelate the vehicle speed, the quality of the track and the passenger comfort requirements, and these are used to identify operational conditions for which a second stage of suspension becomes necessary (that is, in addition to that provided by the magnets). The importance of understanding the suspension's response to deterministic track inputs is also highlighted. Although the paper is directed towards Maglev, the analysis is strongly based upon a consideration of the suspension transfer functions, and so many of the principles are applicable to actively controlled supensions in general.
Connections
Authors: Watts P H
Published: February 2007

In the year that Britain's railways were actually linked to the Continental European systems, the author uses his own personal experience to examine how co-operation within the developing industry has led to cross-fertilization of ideas and practices between Britain and other countries, and addresses the criticism that the British approach has been overly insular.
Engineering Challenges of Linking into Europe
Authors: Etwell M W J
Published: February 2007

Anglo-French agreement to proceed with construction of the Channel Tunnel was formally finalized in 1987. The Usage Agreement allocated 50 per cent of Tunnel capacity for operating through international freight and passenger services. This paper investigates the varied technical and cultural challenges involved in linking into the European high-speed rail network. TMST Nightstock and Class 92 projects are described as examples of how differing standards and practices in design, maintenance and commissioning of these trains have been reconciled.
Optimization of a Railway Freight Car Wheel by Use of a Fractional Factorial Design Method
Authors: Fermér M
Published: February 2007

The performance of a ‘low-stress wheel’ exposed to vertical and lateral contact forces and to thermal braking loads is investigated. Based on finite element calculations, a two-level fractional factorial design method is used to quantify the influences of rim thickness, disc thickness and hub-rim offset on thermal and mechanical stressses, on axial rim displacement, and on wheel mass. A number of approximating linear empirical formulas have been obtained. They offer a powerful tool in designing and optimizing railway wheels. The most effective measure to reduce thermal and mechanical stresses is found to be a hub-rim offset but the penalty is a thermoelastic axial rim displacement during heating. This displacement can be minimized by using as large an offset as possible within geometrical limits. In contrast to the standard type of wheel, no residual deformations and large stresses are induced in the offset wheel after heavy block braking. Full-scale dynamometer brake tests performed on a new prototype wheel are reported. The test results support the calculation model used.
Split Torque Transmission Load Sharing
Authors: Krantz T L , Rashidi M , Kish J G
Published: February 2007

Split torque transmissions are attractive alternatives to conventional planetary designs for helicopter transmissions. The split torque designs can offer lighter weight and fewer parts but have not been used extensively for lack of experience, especially with obtaining proper load sharing. Two split torque designs that use different load-sharing methods have been studied. Precise indexing and alignment of the geartrain to produce acceptable load sharing has been demonstrated. An elastomeric torque splitter that has large torsional compliance and damping produces even better load sharing while reducing dynamic transmission error and noise. However, the elastomeric torque splitter as now configured is not capable over the full range of operating conditions of a fielded system. A thrust balancing load-sharing device was evaluated. Friction forces that oppose the motion of the balance mechanism are significant. A static analysis suggests increasing the helix angle of the input pinion of the thrust balancing design. Also, dynamic analysis of this design predicts good load sharing and a significant torsional response to accumulative pitch errors of the gears.
Measurement of Resonant Frequencies in the Human Chest
Authors: Goodwin M J
Published: February 2007

Measurements of resonant frequencies in the human chest, and of how resonant frequency varies with the subject's mass, height, chest size and sex, were undertaken as a pilot study on a sample of 15 volunteers. These were obtained by measuring the acceleration response of the chest when a force was applied to the back at a range of frequencies, and noting the peak response frequency. It is foreseen that mechanical stimulation of the chest at the appropriate frequency might form a useful part of physiotherapy treatment offered to patients with particular chest disorders. The results suggest that the chest resonant frequency is sensitive to the subject's mass and chest size, but is less dependent on height. Typical values found were 25 Hz for males and 33 Hz for females.
A Robotic System for Minimal Access Surgery
Authors: Potamianos P , Davies B L , Hibberd R D
Published: February 2007

A computerized manipulator-assisted method is presented to facilitate the execution of minimal access surgical procedures. The proposed method employs a passive manipulator to assist the surgeon in the three-dimensional spatial location of anatomical features, using general purpose X-ray fluoroscopy or ultrasound imaging equipment with video input/output facilities. The method enables the three-dimensional navigation of surgical tools in correlation with two-dimensional medical images.

A system is under development at Imperial College, London, for the application of this method to minimally invasive renal procedures. The system will enable the spatial location of renal calculi and the establishment of percutaneous renal track central axes. The proposed method is compatible with existing urological procedures and imaging equipment and enables the correlation of X-ray and ultrasound imaging modalities.
Using the Doppler Effect to Measure the Vibration of Human Bones: In Vitro Studies
Authors: Flint T , Nokes L , Maheson M , Woodcock J P
Published: February 2007

A novel application of ultrasound Doppler theory to the measurement of bone vibration is described. The theory and experimental apparatus is outlined and its initial calibration and in vitro assessment reported. It is speculated that this method may be used clinically in order to monitor in vivo bone fracture healing.