bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Strategy for Selecting Engineering Components
Authors: Vogwell J , Culley S J 
Published: February 2007

Selecting components from catalogues is an important engineering activity and it is found that computerizing the process provides major advantages for the design engineer and has serious implications for manufacturers. Difficulties arise when computing the selection procedure, however, because catalogue data formats and analysis techniques (which are essential for verifying suitability in an application) have evolved from manual usage. Computer data handling methods and search strategies differ significantly, consequently, major changes are necessary to transfer information from catalogue formats in order to achieve a fully computer aided system approach. Experience has been gained at Bath University designing and developing numerous component selection programs; dealing with bearings, springs, gears, fastenings etc. One system has been developed to a commercial standard. This paper describes why there is increasing interest in automating the selection of catalogue components. It discusses the nature of the data and some of the salient features which are considered desirable if such programs are to be fully exploited by practising engineers. In particular, the strategy which has been used for efficiently dealing with the different data types inherent with mechanical components is shown.
A Study on Prediction of Welding Current in Gas Metal arc Welding Part 1: Modelling of Welding Current in Response to Change of Tip-to-Workpiece Distance
Authors: Kim J W , Na S J 
Published: February 2007

A model of the welding arc in gas metal arc welding (GMAW) is very useful for the analysis and automation of the welding process. Thus a mathematical model that is able to predict the welding current change in response to the variation of tip-to-workpiece distance was proposed for the gas metal arc welding process. The model was deveoped by analysing the welding arc behaviour and by considering the characteristic of the welding power source. The welding current variation was calculated with respect to various welding conditions and slope of the power source characteristic. By comparing the calculated and measured current signals, it could be concluded that the model proposed can well define the relation ship between welding current and tip-to-workpiece distance for various welding conditions in gas metal arc welding. Both the calculated and measured signals of welding current show almost a linear variation in response to the linear change of tip-to-workpiece distance
An example of Automatic Two-Dimensional Component Inspection Using Computer Vision
Authors: Al-Kindi G A , Baul R M , Gill K F 
Published: February 2007

Automatic inspection processes require intelligent devices which combine the attributes of existing measuring techniques with those of the experienced practitioner. With the rapid growth of solid state electronics and computer applications during the last two decades, the field of computer vision has developed significantly and its application in the field of inspection is becoming a reality. This paper examines the use of computer vision for the inspection of engineering components. A range of existing edge detection algorithms has been tested for their suitabiliy for two-dimensional component inspection together with a new algorithm for application when contour tracing methods fail to detect localized edges in a complex scene. Assessments are mainly subjective but are also based on computational speed; an important factor in on-line inspection applications. An algorithm has been proposed which can be used for the simultaneous analysis of internal and external contours with the ultimate aim of automatic component classification. In addition an alternative boundary coding system eliminates errors which are normally associated with other coding methods when monitoring components at different orientations.
Computer Simulation of a Variable Fill Hydraulic Dynamometer; Part 1: Torque Absorption Theory and the Influence of Working Compartment Geometry on Performance
Authors: Raine J K , Hodgson P G 
Published: February 2007

A mathematical model of the steady state torque absorption process in variable fill hydraulic dynamometers is described. This is the initial part of a general model that has been developed to simulate the dynamic behaviour of Froude-type dynamometers under open-loop control and of an engine/dynamometer system under various closed-loop control modes. In this paper, the equations for steady state torque, energy dissipation, fluid vortex pressure in the working compartment and water outflow from the dynamometer are presented. Predictions by the model for the special case of characteristic running full torque absorption performance are compared with experimental test bed results for different working compartment geometries. Effects of vane angle and working fluid properties on maximum torque capability are examined. Subsequent parts of this paper will address the dynamic variable fill simulation.
Calculations of a Curved-Pipe Flow Using Reynolds Stress Closure
Authors: Lai Y G , So R M C , Anwer M , Hwang B C 
Published: February 2007

It has been observed that as a fully developed turbulent flow enters a curved bend the anisotropy of the normal stresses near the outer bend (furthest from the centre of the bend curvature) increases. According to the arguments of vorticity generation, a sudden increase in the anisotropy of the normal stresses may lead to the formation of a secondary flow of the second kind. If this secondary motion is to be calculated, then a near-wall Reynolds stress closure that can mimic the anisotropic turbulence behaviour near a wall has to be used. This study presents the results of just such an attempt. In addition, two high Reynolds number closures assuming wall functions in the near-wall region are tested for their ability to replicate the behaviour of the normal stresses in a curved-pipe flow. These two closures differ in their modelling of the pressure-strain terms. Consequently, the effects of near-wall and pressure-strain modelling on curved-pipe flow calculations can be examined. Comparisons are also made with recent curved-pipe flow measurements. The results show that pressure-strain modelling alone is not sufficient to predict the rapid rise of the anisotropy of the normal stresses near the outer bend, and hence the formation of the secondary flow of the second kind. Overall, the near-wall Reynolds stress closure gives a more accurate prediction of the measured mean flow and turbulence statistics, and a realistic calculation of the secondary flow of the second kind near the outer bend.
Friction, Surface Science and Tribology—A Personal View
Authors: Tabor D 
Published: February 2007

This paper is a rather personalized account of research carried out over many years by a physicist exploring the basic mechanisms of friction and the general field of tribology. It indicates how side-tracks have often led to other rich pastures and reflects the sometimes fruitful unpredictability of scientific research. This paper records several such felicitous surprises emerging from studies of friction. These include the direct measurement of surface forces, the adhesion of elastomers in terms of surface energy and viscoelastic properties, the skid-resistant properties of tyres, diffusion in polymers and measurement at the molecular level of the shear properties of oriented layers of boundary lubricants. In all this work the author is conscious of the original initiatives of the late Professor Bowden and recognizes the major contributions made by research students and colleagues. He is also conscious of many elements of serendipity.
The Effects of Mixture Preparation and Trapped Residuals on the Performance of a Spark-Ignition Engine with Air-Shrouded Port Injectors, at Low Load and Low Speed
Authors: Brown C N , Ladommatos N 
Published: February 2007

This paper is concerned with the steady state combustion performance of a port-injected spark-ignition engine operating at low load and low speed. The main areas of investigation were the effects of mixture quality and trapped combustion residuals on combustion performance. The behaviour of the inlet manifold fuel film was also investigated under various engine running conditions. The effects of injection timing were quantified, both with warm and hot engine coolant. Each of the six fuel injectors on the engine was equipped with an air-shrouded injector which improved fuel-spray atomization. Tests were carried out both with and without air flowing through the shrouds. A new method is also presented which provides a measure of the size of the inlet-manifold wall film under various engine running conditions. Finally, measurements of the amount of trapped combustion residuals are presented, and their effect on combustion performance is quantified.
Practical Tools for Vehicle Impact Simulation Part 2: An Integrated Approach Using Oasys Dyna3D
Authors: Miles J C , Sturt R M V , Leach J H 
Published: February 2007

This paper describes the use of a non-linear finite element analysis program (OASYS DYNA3D) for the simulation of vehicle impact events. The purpose of the paper is to demonstrate how one single program can be used at a number of different levels of complexity to serve the needs of the analyst at all stages of vehicle design. Examples are given of lumped mass/spring simulations, continuum (shell/brick) simulations and an intermediate stage in which the two analytical philosophies are combined to form a ‘hybrid’ approach. The paper conclues with some observations on the future for hybrid modelling techniques and suggests some simple extensions which would allow the occupant and safety restraint systems to be included in the global vehicle simulation.
On the Implementation of Severely Compressed Automobile Product Cycles
Authors: Bertodo R , Mitchell C G 
Published: February 2007

Progressive strategic, organizational and product actions taken by the Japanese automotive manufacturers during the past two decades have gained them leadership in almost every benchmark of competitive and industrial competence. From this vantage point, they stand poised to alter the nature of the market during the 1990's through the introduction of a proliferation of low-volume niche products with very short life spans. Two-year automobile product cycles are within their competence now. The paper outlines the implications of introducing such severely compressed product cycles in a European context. These were exposed by a determined attempt to match Japanese methods and techniques over a period of eleven years. Attaining the goal affected every aspect of the business and its external interfaces. The resultant new company ethos and culture is described. Future evolutionary developments are signposted.
Controlling Two-Phase Flow Using a Fluidic Vortex Amplifier
Authors: Owen I , Abdul-Ghani A M 
Published: February 2007

This paper describes the results from an investigation into the use of a fluidic vortex amplifier for controlling two-phase gas/liquid flow. A two-phase flow facility has been built and an axial vortex amplifer, designed to suit a 75 mm pipe, has been manufactured and tested. The results show that the vortex amplifier operates satisfactorily in cavitating and two-phase flow but that there is a reduction in the performance as measured by the turn-down ratio. However, it is clearly demonstrated that this is due to the increased resistance of the vortex amplifier to the two-phase supply flow and that the control flow characteristics remain unaffected by the nature of the supply flow. To provide an illustration of how a vortex amplifier might be used for controlling two-phase flow, its application as a separator control valve has been suggested.
Propulsion Systems for Twenty-First Century Commercial Transports
Authors: Powell D T 
Published: February 2007

Improvements in the propulsion system design and performance will continue into the twenty-first century just as they have during the twentieth century. However, for subsonic commercial applications, there is a definite shift away from placing major emphasis on fuel burned and system weight. Total reliability (engine and associated systems) along with lower maintenance costs will dominate the design decisions although engine performance will continue to be a major consideration. For supersonic transport application, engine performance (weight, total specific fuel consumption (TSFC), noise and emissions) will be the primary influences since improvements in these areas are required to meet the mission goals. This paper addresses the subjects of engine/airframe integration for the large-diameter engines expected to enter service with the next generation of subsonic commercial transports. The paper discusses system design for reliability, safety considerations, computational fluid dynamics (CFD) applications to the propulsion installation, engine/airframe integration, cockpit displays and control systems. The primary propulsion system installation requirements for future supersonic transports are also discussed. The supersonic transport performance is predicated on a strong interdependence between the airframe and the engine. Variable geometry is required for both the inlet and the nozzle to satisfy the various operating and missions requirements. Fuel is approximately 65 per cent of the total operating costs, making it imperative to minimize the fuel burned by improved engine performance and reduced installation drag. Environmental issues are also discussed.
Numerical Modelling of Reciprocating Pumps with Self-Acting Valves
Authors: Johnston D N 
Published: February 2007

The performance of reciprocating pumps with self-acting valves is dependent upon the dynamic characteristics of the valves. Particularly when the pumps are working at high speed, delays in valve operation can lead to cavitation, reduction in volumetric efficiency and increased noise and wear. The behaviour of the valves is complex and difficult to predict. A computer program for the modelling of the dynamic behaviour of such pumps has been developed. The mathematical models of the components are described in this paper. The modelling of the effects of cavitation is included. Results compare favourably with experimental measurements.
Computation of Three-Dimensional Turbulent Flows in a Pipe Junction with Reference to Engine Inlet Manifolds
Authors: Fu H , Tindal M J , Watkins A P , Yianneskis M 
Published: February 2007

This paper presents a numerical study of the flows in an internal combustion engine inlet manifold. The three-dimensional turbulent flows through a single branched manifold were simulated using the κ-ɛ model of turbulence. The flow structure was characterized in detail and the effects of the flow split ratio and inlet flowrate were investigated. Detailed measurements were performed to validate the numerical predictions, using laser Doppler anemometry. Good agreement was obtained between the predicted and the measured mean velocities. The predicted levels of turbulence energy are in qualitative agreement with the measurements.
The Thrust Exerted on a Gas-Pressurized Vessel During Axial Rupture
Authors: Baum M R , Parry A A 
Published: February 2007

This paper investigates the thrust exerted on a vessel as a result of axial rupture, which has not previously been examined theoretically or practically. A simple model is developed to predict the peak thrust when the breach is large, that is when the fracture is propagating with constant velocity and the maximum rate of separation of the free edges downstream of the fracture tip has been achieved. The model assumes that the depressurization process within the breach zone is dominated by the transverse rarefaction wave initiated by the arrival of the breach as it advances along the vessel. The prediction is compared with a measurement made during a burst test on a large air-pressurized steel vessel. A novel measurement technique employed an inverse Brinell hardness test, in which the indentation size was used to calculate back to the force that produced it. This was interpreted with the help of a finite element computer simulation of the indentation process.
Carefree Handling Systems for Helicopters
Authors: Massey C P 
Published: February 2007

A programme of work is being undertaken with the aim of defining features to help the pilot respect the helicopter's numerous flight limitations, reducing the workload and enhancing mission performance. Carefree handling features that have been studied include visual, audible and tactile cues and direct intervention methods. These features have been evaluated in a series of piloted simulation trials at DRA Bedford. Most of the work to date has been based around helicopters with active control technology (ACT) flight control systems, but conventionally controlled helicopters have also been considered. Results from the programme suggest some benefits for head-up visual displays, tactile and audible cues, with more significant benefits for the direct intervention methods. A combination of these features allows the pilot to use the full performance of the vehicle without exceeding limits and at low pilot workload.
Revision of Cemented Fixation and Cement—Bone Interface Strength
Authors: Rosenstein A , MacDonald W , Iliadis A , McLardy-Smith P 
Published: February 2007

Interfacial shear strength between poly(methyl methacrylate) (PMMA) bone cement and cancellous bone was measured in bone samples from human proximal femora. Samples were prepared with fresh cement-bone, fresh cement inside a mantle of existing cement and with fresh cement-revised bone surfaces. Push-out tests to measure shear strength caused failure only at bone-cement interfaces; revised bone interfaces were 30 per cent weaker (P < 0.02) than primary interfaces. The clinical relevance is that revision of cemented joint arthroplasties may necessitate removal of components with sound cement-bone fixation. The practice of removing all traces of PMMA cement may not yield the optimal fixation; adhesion of fresh cement to freshly prepared surfaces of the existing cement might also be considered where circumstances are favourable.
Application of Predictive Control in District Heating Systems
Authors: Palsson O P , Madsen H , Søgaard H T 
Published: February 2007

In district heating systems, and in particular if the heat production takes place at a combined heat and power (CHP) plant, a reasonable control strategy is to keep the supply temperature from the district heating plant as low as possible. However, the control is subject to some restrictions, for example, that the total heat requirement for all consumers is supplied at any time and each individual consumer is guaranteed some minimum supply temperature at any time. A lower supply temperature implies lower heat loss from the transport and the distribution network, and lower production costs. A district heating system is an example of a non-stationary system, and the model parameters have to be time varying. Hence, the classical predictive control theory has to be modified. Simulation experiments are performed in order to study the performance of modified predictive controllers. The systems are, however, described by transfer function models identified from real data.
Information Technology
Authors: Williams David J 
Published: February 2007

This document summarizes the outcome of an Expert Meeting held jointly between the Science and Engineering Research Council and the Institution of Mechanical Engineers, which brought together a multi-disciplinary group of experts from the information technology (IT) and product design communities. The meeting was held to review the state of the art of IT in design, to identify the technology gaps and development problems, to inform each community of the views and developments being undertaken by the other and to help identify the way forward in the British R&D effort to stimulate innovative product design. One of the important outcomes of the meeting was the identification of priorities for research and development in the application of IT in the design process which will be necessary if the United Kingdom is to remain competitive in design for manufacturing industry. The meeting was attended by a distinguished group of industrialists and academics drawn from the United Kingdom and overseas. In terms of priorities, the findings of the meeting were: 1. There should be a co-ordinated programme to determine the way in which designers carry out design when supported by computer-based tools. 2. There should be support for further research through demonstrator projects which help to provide the scientific understanding required in the construction of the next generation of design tools. 3. Forward-looking projects should be defined with, say, a ten year time horizon to develop prototypes of the design tools of the future.
Discs and Drums: The Thermo-Fluid Dynamics of Rotating Surfaces
Authors: Bayley F J , Long C A , Turner A B 
Published: February 2007

This paper reviews long-term experimental and theoretical research programmes concerned with flow and heat transfer over the large rotating surfaces, commonly discs, often drums but sometimes conical, used to support the blades in turbomachinery. The account begins with a geometry found in turbomachinery from the oldest steam plant to the most modern gas turbine, in which a disc rotates near to a stationary, usually coaxial, member. The flow in the intervening ‘wheel-space’ is well understood, but external conditions can affect the extent and nature of ingress from the surrounding fluid. In the gas turbine this fluid is the mainstream hot gas, an inflow of which could have serious consequences, so that the study of ingress has become the principal subject of research for rotor-stator systems and recent work is fully reported here. In many turbo-machines, especially compressors, adjacent coaxial surfaces rotate together and thus enclose a cavity subject to unusual forces in which a wide range of flow regimes can obtain. The precise form depends largely on whether the cavity allows a net radial inflow or outflow of fluid or whether the only access and egress are from near the axis of the system, the so-called ‘axial through-flow’ case. Systems with a net radial flow, inward or outward, are well understood. In their absence, the flows are often four dimensional, varying with time and in the three space coordinates. Such regimes remain incompletely understood although recent congruence between experimental and theoretical studies is encouraging. Finally, attention is turned to surfaces nearer parallel than orthogonal to the axis of rotation, as in the drums used in older steam turbines and commonly in compressors. Here the main concern has been with the effect of stationary blading, where the close clearance between the blading and the rotating surface modifies the boundary layers and thus the friction and heat transfer on the latter.
Analysis of Hydrodynamic Journal Bearings Considering Lubricant Supply Conditions
Authors: Claro J C P , Miranda A A S 
Published: February 2007

A method of analysis of steadily loaded hydrodynamic journal bearings with a single axial groove (either on the load line or at 90° to the load line) or two diametrically opposed axial grooves is described. The method is based on Elrod's cavitation algorithm (which ensures conservation of mass flow in both the full film and the cavitated regions) and is able to accommodate specified lubricant supply conditions, namely groove size and location and supply pressure. Special attention has been given to the determination of flowrate. The equation governing the distribution of pressure around the bearing has been solved numerically using a finite differences approximation and multi-grid techniques to accelerate the convergence of the solution. Performance predictions of the analysis are compared with published experimental data and with experimental measurements obtained in laboratory tests carried out by the authors. The data used cover all grooving arrangements studied.