bluuebunny/crossref_metadata_2025 huggingface dataset:
Combustion Inhomogeneity and Percolation
Authors: Belmont M R , Thurley R , Thomas J , Morris E L , Buckingham D J , Haviland J S
Published: February 2007

This paper briefly examines the scale and consequences of inhomogeneity in the fuel/air system within the cylinder of a petrol IC engine. This work serves as the basis around which to introduce a percolation network approach as the natural description for combustion inhomogeneity. The underlying structural elements of the percolation model link in a very direct way with the various physical quantities concerned. This allows the general aspects of the theory to offer new concepts in combustion which appear attractively obvious once they have been stated. The most important point to emerge is that the percolation approach generates very clear design guidelines, particularly for operation under lean conditions.
An Expert System for Generating Contact Configurations for Robot Gripper Jaws
Authors: Pham D T , Tacgin E
Published: February 2007

The generation of systems of contacts for stably holding a workpiece is a task requiring knowledge of a large number of rules about rigid-body constraint. A knowledge-based expert system has been developed to automate this process. The system is capable of synthesizing valid constraint configurations for a wide range of workpieces. Its ultimate use is to generate contact profiles for robot gripper jaws based on these constraint configurations. The system is described in this paper, which also gives a brief overview of expert systems in general and of the particular development tool adopted.
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.
A Parametric Study Using a Single Cam-Follower System Dynamic Model
Authors: Hardy S J , M-Daragheh M
Published: February 2007

The paper describes a parametric study of valve system dynamics using a single cam-follower system model. The effect of the choice of damping coefficients and the degree of flexibility of the camshaft on the valve motion are highlighted.
The Feedback of Plant Data to Design
Authors: Thompson G
Published: February 2007

The paper is an interim statement on a research project that describes the principles and working of a feedback system for plant operating data to design. The system differs from conventional practice of data collection in that a design reference is established against which actual plant experience is compared. Work has been carried out to demonstrate that it is feasible to establish a design reference which contains quantified expectations of reliability and maintainability. The reporting system is described, as are the methods by which designers can interrogate the computer database generated. The paper concludes with a discussion of the advantages of this system with respect to the involvement of designers, the usefulness of the system and the motivation of maintenance personnel to collect good-quality data.
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.
Couplings
Authors: Waterman A W
Published: February 2007

A seminar on ‘Couplings’, organized by the Railway Division of the Institution of Mechanical Engineers, was held in London on 13 March 1990
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.
Why Space is Expensive—Operational/Economic Aspects of Space Transport
Authors: Parkinson R C
Published: February 2007

This paper focuses attention on the tremendous costs involved in space activities and proposes that these must be examined if projects are to be continued. They can only be justified if a more commercial attitude is taken to cost recovery without increasing the cost of operations. Communications satellites, launching and space stations are investigated to see where low transport costs can be achieved.
Quality Costing at British Aerospace Dynamics: A Case Study
Authors: Hesford M G , Dale B G
Published: February 2007

This paper reports on the development and use of quality costing at British Aerospace (Dynamics) Limited; the method used was based on BS 6143. It was found that developing a model that is considered useful by management and applicable across five different sites was not an easy task. A trade-off was made between accuracy, in the accounting sense, and utility. Other difficulties encountered included determining the cost of engineering changes, obtaining convenient or user friendly quality cost data from the accounting system and quality cost definitions. It is also pointed out that the management of British Aerospace (Dynamics) have found that quality costing allows them to quantify key problem areas, helps them to decide on the allocation of resources to identify and resolve specific problems, and closes the loop with quantifiable achievements.
EIPOS for Ice-Formation Control on Aircraft in Flight: An Alternative Technique
Authors: Levin I A
Published: February 2007

This paper traces the history of ice-formation control on aircraft in flight and the efforts made to provide an alternative to the uneconomic heating techniques. The EIPOS was developed in the USSR and uses dynamic wave pulses generated directly in the structure by an external electrodynamic field to break up the ice. The method has proved so successful that it is now finding applications in other fields.
Recent Research into the Aerodynamics of ASTOVL Aircraft in Ground Environment
Authors: Knowles K , Bray D
Published: February 2007

A brief survey is presented of the aerodynamic phenomena associated with jet-lift aircraft in ground effect. The particular problems of modelling the ground vortex formed by impinging jets in cross-flows are then described, in the light of the authors' own experimental studies. Finally, areas of these flow fields exhibiting stochastic properties are highlighted.
Bioengineering Aspects of Rehabilitation
Authors: Wright V
Published: February 2007

This paper discusses the development of bioengineering in the field of human joints and its particular relevance to rehabilitation.
Migrating Wear Marker in the Charnley Low Friction Arthroplasty
Authors: Wroblewski B M
Published: February 2007

The author notes the unusual appearance of several cases of Charnley low friction arthroplasty and seeks to explain the sequence of events which may have taken place to bring about this change.
Bioengineering Activities in the Department of Orthopaedic Surgery and Trauma, Royal Adelaide Hospital, Adelaide, South Australia
Authors: Pearcy M J , Howie D W
Published: February 2007

This paper outlines the main areas of bioengineering research in the Department of Orthopaedic Surgery and Trauma at the Royal Adelaide Hospital, South Australia.
The Application of Modern Control Theory to a Turbocharged Diesel Engine Powerplant
Authors: Winterbone D E , Jai-In S
Published: February 2007

A brief review of the intrinsic features of diesel engine performance and control is given. The introduction of electronic control to fuel systems is described. It is shown that engine dynamic performance (in the form of transfer functions) can be both calculated and measured. An example is given of multi-variable control techniques applied to a turbocharged diesel engine with variable geometry turbocharger. It is shown that there are significant benefits in terms of smoke emissions from such a system, and that the synergy of more controllable engine systems together with modern control techniques enable diesel engines to reduce emissions.
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.
Parallel Implementations of Gas Turbine Simulations Using Transputers
Authors: Thompson H A , Fleming P J
Published: February 2007

Growing complexity in gas turbine engines and the demand for improved performance suggest that parallel processing systems will be necessary to meet processing demands. These demands are further heightened by the need for complex control and health monitoring functions and a software fault tolerance capacity. Using the Inmos transputer as the processing element for the parallel system, this paper explores the potential of such a system to meet these demands with reference to a specific practical turbine engine example. Mapping issues are explored and real-time simulations demonstrate the validity of the approach, while highlighting difficulties associated with the parallelization of irregularly structured systems.
High-Intensity Burners with Low Nox Emissions
Authors: Andrews G E , Alkabie H S , Aziz M M Abdul , Hussain U S Abdul , Dabbagh N A Al , Ahmad N A , Shaikly A F Ali Al , Kowkabi M , Shahabadi A R
Published: February 2007

Experimental combustion and NOx emissions results are summarized for a range of jet shear layer combustion systems that have rapid fuel and air mixing, short intense flames, a high turn-down ratio and low NOx characteristics. Two burner sizes of 76 and 140 mm are investigated for propane and natural gas. Three jet shear layer burners are compared with axial and radial swirlers. The combustion techniques were developed for application to low NOx combustion systems for industrial gas turbines, where NOx emissions as low as 10 ppm at 15 per cent oxygen have been demonstrated. It is shown that at one bar pressure, gas turbine combustors and high-intensity burners operate at similar air flow, blockage and pressure loss conditions.
Monitoring in-Service Changes in Materials Properties
Authors: Parker J D , Bisbee L H
Published: February 2007

The safe operation of a wide range of large-scale plant depends on knowledge of component specific materials properties. Techniques that allow reliable measurement of changes in critical properties are therefore vital. The present paper describes a new procedure for removing miniature material samples. The technique can be applied even in difficult access conditions and results in minimum material removal so that sampling is effectively non-destructive. Specific case studies where this technique has been applied to the condition assessment of steam plant are described.
Optimizations for Brayton-Joule Gas Turbine Cycles
Authors: Frost T H , Agnew B , Anderson A
Published: February 2007

Traditionally, the simple Brayton–Joule cycle has been optimized for maximum output and for minimum compressor work with inter-cooling and maximum turbine work with reheat. To these Woods et al. (1) have added optimization for peak efficiency of the simple cycle with internal irreversibilities. The results now presented include both maximum output and peak efficiency for both regenerative and intercool/reheat cycles with internal irreversibilities. Two special cases, for a regenerative cycle and for a non-regenerative cycle with both reheat and intercooling, are identified where the conditions for maximum output and peak efficiency coincide.
Mechatronics and the Imitation of Nature
Authors: French M J
Published: February 2007

The author provides a definition of mechatronics. He explains how mechanical engineering design must change to take full advantage of developments in microelectronics and illustrates this by three structural examples. He goes on to show by further examples how mechatronics strengthens an underlying trend in engineering he calls ‘the imitation of nature’ with products which tend increasingly to resemble living creatures.
Optimum Cutting Conditions for Turned Components
Authors: Arsecularatne J A , Hinduja S , Barrow G
Published: February 2007

This paper describes the procedures used in a technologically orientated numerically controlled (NC-) system to determine the optimum culling conditions automatically for turning, drilling, grooving, threading and parting-off operations. In rough turning, the optimum depth and feed combination is determined using a direct search procedure on the allowable depth/feed region for chip control. The system determines the optimum depth of cut, feed and velocity for each pass in multi-pass turning on the basis of a user-selected objective criterion and a number of technological limitations that may apply to the process, such as machine power, dynamic instability, allowable range of depths and feeds for the tool and workholding limitations which include axial slip, circumferential slip and component throw-out. A user-friendly manual option is also provided which allows the user to specify the cutting parameters. Examples are given to illustrate how these procedures determine the optimum cutting conditions. A comparison between the machining costs and times using cutting conditions obtained from handbooks and the aforementioned procedures shows that for all the operations considered, there are cost and time savings when the cutting conditions obtained by the latter are used.
Sensitivity of Front-Face Weld Geometry in Representing the Full Penetration
Authors: Zhang Y M , Kovacevic R , Wu L
Published: February 2007

The measurement of weld penetration using a front-face sensor has been an important issue in welding automation. The fundamental problem is to find a measurable front-face parameter that can adequately represent the weld penetration. In this paper, both the front-face average weld depression depth (a novel weld geometrical parameter) and the weld width are selected as possible representations of full penetration in GTA welding. Two types of sensitivities of front-face weld geometry, with respect to variations in welding conditions and with respect to control variables, are proposed as criteria for determination of promising parameters. Sensitivity calculation of experimental data shows that the front-face weld width is not promising while the average front-face weld depression depth is. This conclusion is also confirmed by a specific experiment and statistic models.
Statics of Gas-Lubricated Slider Bearings in Magnetic Recording Disk Files
Authors: Zheming Z , Wenkang S
Published: February 2007

This paper presents theoretical and experimental analyses of the static characteristics of gas-lubricated slider bearings. An implicit scheme, based on the Patankar-Spalding method, which is commonly utilized in the numerical heat transfer and fluid flow, is developed for the numerical solution of the Reynolds equation. Further investigations on the steady static minimum flying height and the pitch angle are presented by use of a transient response analysis. Theoretical results are experimentally verified to be correct and reliable. By comparing a grooved slider with a non-grooved one in the surface of bearing rails, it is concluded that the grooves in the surface of bearing rails may effectively improve statics of gas-lubricated slider bearings in magnetic disk storages.
The Receptances of Beams, in Closed form, Including the Effects of Shear and Rotary Inertia
Authors: Stone B J
Published: February 2007

The published receptances of beams have been based on the Bernouli-Euler model for beams and thus do not include the effects of shear and rotary intertia. As a result, under some circumstances significant errors occur. The receptances of beams including shear and rotary inertia effects are derived in this paper and compared with those based on the Bernouli-Euler model. In addition, because slope continuity is no longer a compatibility requirement for the addition of beams, the approach for the addition of such ‘systems’ is discussed.
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.
Light Duty Diesels—The Emissions Challenge
Authors: Horrocks R W
Published: February 2007

Further restrictions of automotive diesel emissions are planned for European Economic Community countries at the end of 1992 and in North America for 1994. The effect of changes in emission legislation on engine development is reviewed. This paper also examines these standards and the technologies that are being applied to light duty automotive diesel engines. Combustion systems, fuel injection equipment, exhaust gas recirculation and oxidation catalysts are areas where development is reaping benefits in reducing diesel emissions.
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.
A Theoretical Study of the Lateral Impact of Fully Clamped Pipelines
Authors: Jones N , Shen W Q
Published: February 2007

A theoretical rigid-plastic procedure is developed in order to predict the quasi-static response of a ductile pipeline which is fully clamped across a span and struck laterally by a rigid mass. This theoretical study allows the local or denting deformations to continue during the global deformation phase which has been considered only semi-empirically in previous work. In addition, it is valid for a mass striking at any position on the span, except very close to a support. Good agreement is obtained with the maximum permanent transverse displacements recorded in the experimental tests which are reported in a companion paper (the preceding paper in this issue) on steel pipelines having 11 ≤ D/H ≤ 62.3 and 2L/D ≅ 10 and struck at the mid span and one-quarter span positions.
BOA—the RAPT's New Concept for its Urban System
Authors: Hafter G H
Published: February 2007

This mini-paper describes the background to the decision of the Régie Autonome des Transports Parisiens (RAPT), the Paris Transport Authority, to develop a new form of rolling stock for operation on the urban Métro network (as opposed to the RER), where car size is severely constrained by a tight loading gauge and extremely sharp curvature. The object was to provide for better passenger distribution throughout a train, coupled with a reduction in overall weight and a reduction of waste space between vehicles, with a consequent increase in the effective passenger capacity.
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.
The Development Status of the Space Technology Research Vehicle Programme
Authors: Ryden K , Fearn D G , Gould R D
Published: February 2007

In order to test in orbit a wide variety of new systems and technologies and to carry out associated research, the Royal Aerospace Establishment is developing two small 50 kg satellites, designated Space Technology Research Vehicles 1a and 1b. They are scheduled to be launched into the geostationary transfer orbit by an Ariane 4 in 1993; in this orbit they will be able to investigate the effects of a very high radiation dose, atomic oxygen erosion and spacecraft charging. The paper discusses the design of the spacecraft and describes the development status as at September 1991. Details are also given of a selection of the payload experiments.
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.
Optimal Design Methodology of Point-to-Point Servo Systems for Minimization of Energy Consumption
Authors: Kim S W , Park J S
Published: February 2007

An optimum design methodology is presented for point-to-point motion control servo systems in which d.c. permanent magnetic motors are used as the main actuators. Emphasis is focused on establishing a series of comprehensive decision-making practices in dealing with three major design subjects: determination of the velocity profile, optimization of the speed reduction ratio, and selection of the motor. Finally, a practical design example is discussed to illustrate how the suggested design methodology may be applied to actual design problems.
Maximizing the Efficiency of Wave-Energy Plant Using Complex-Conjugate Control
Authors: Nebel P
Published: February 2007

A method of determining the hydrodynamic coefficients of a floating wave-energy absorber is outlined, and the coefficients of a Salter's duck are measured experimentally. A complex-conjugate synthesizer, derived from these coefficients, is used both theoretically and experimentally to predict and to measure the efficiency of a duck in unidirectional monochromatic waves. The synthesis produces a higher efficiency over a greater bandwidth than has been achieved before. The reason for the improvement in efficiency is explained, and conclusions are drawn about the implications of complex-conjugate control for predicting practical engineering constraints on the design of a full-sized wave-energy absorber.
The Reliability Estimation of the Low-Cycle Fatigue Life of Steam Turbine Rotors
Authors: Huang S H
Published: February 2007

In this paper, a technique to define the low-cycle fatigue life damage and its cumulative effects on steam turbine rotors using the reliability estimation method is presented. Because of the dispersion of external load spectra and the fatigue strength of materials, the dispersion coefficient is defined to describe the probability relationship between reliability and life damage. The definition of the dispersion coefficient differs according to the probability distribution of service life. The situation for both the logarithmic normal distribution and the Weibull distribution is analysed in this paper. Using this technique, the internal relationship between the crack initiation life damage and the crack propagation life damage is investigated under any selected reliability. It is helpful for managers of power stations to evaluate the state of turbines and to manage the service life of turbine rotors. This technique is useful in evaluating the residual fatigue life of rotors and determining the optimal detecting date. An example is presented in the paper and some valuable results are obtained.
Combating Global Warming—Reducing CO2 Emissions from Coal-Fired Power Plant
Authors: Summerfield I R , Goldthorpe S H , Bower C J
Published: February 2007

The threat of global warming is sufficient to warrant ‘least regrets’ measures to reduce emissions of greenhouse gases, in particular through increased efficiency in energy production and use. British Coal has set up a programme to contribute to the international responses to the threat. It is concentrating on investigating options for removing carbon dioxide from fossil-fuelled power plants in case expensive fallback options become necessary. Screening of the options commenced with flowsheeting studies which estimated the thermal efficiency of a number of process schemes. These screening studies concluded that carbon dioxide (CO2) control could be retrofitted to existing coal-fired power stations, but that the new generation of gasification-based systems is more promising. CO2 separation could be more easily integrated into advanced power plants as they operate at high pressure, resulting in increased CO2 partial pressure which reduces the energy penalty associated with the separation. The CO2 would need to be exported as a liquid stream for storage in exhausted oil or gas fields. Costs of such power plants and CO2 disposal options have been developed. These studies suggest that, using proven technology, the cost of electricity would rise by about 42 per cent. If novel gas separation systems based on membranes can be developed, the increase in electricity cost could be limited to around 34 per cent. This paper discusses the options and presents the results of costing studies.
Design and Performance of a High-Pressure Ratio Turbocharger Compressor Part 1: Design Considerations
Authors: Whitfield A , Doyle M D C , Firth M R
Published: February 2007

The compressor design requirement was for a pressure ratio of 3.6, with a peak pressure ratio of 4.3 at the maximum non-dimensional speed of the impeller of 1.66. Due to the stress-limited speed, an aluminium alloy impeller was specified, the impeller discharge blade backsweep had to be restricted and the application of prewhirl was considered from the outset as a means of extending the operating range. A non-dimensional conceptual design procedure, including the effect of inlet prewhirl, was applied to the design of three turbo- charger impellers. An impeller, designated A, was designed with the inclusion of 25° of prewhirl. A second impeller, designated B, was designed with zero prewhirl for comparison purposes, but was not manufactured. A third impeller, C, was manufactured through the modification of an existing design and the design study was applied to the assessment of this third design.
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.
Stochastic Modelling of Surface Texture Generated by High-Energy Jets
Authors: Kovacevic R , Mohan R , Zhang Y M
Published: February 2007

The surfaces produced by two different jet cutting processes, namely abrasive waterjet (AWJ) cutting and laser machining, are characterized for a comparative study. The surface profile measurements from experiments are modelled using auto regressive moving average (ARMA) models. The characteristics of the different profiles are identified by analysing these models. To describe the surface adequately, a sufficiently large sized sample is utilized for modelling. A novel method for identifying ARM A models based on the concept of model distance, which is ideal for large size samples, is adopted here. The relative advantages of this method are quantified in terms of the accuracy ratio. The profile characteristics (both dynamic as well as static) reveal more information about the nature of these processes. Scanning electron microscope (SEM) photographs of the surfaces generated by laser and AW J are analysed to obtain more insight into the physics of these processes.
An Efficient Response Analysis Method for a Non-Linear/Parameter Changing System Using Sub-Structure Modes
Authors: Kim H K , Park Y-S
Published: February 2007

An efficient state-space method is presented to determine time domain forced responses of a structure using the Lagrange multiplier based sub-structure technique. Compared with the conventional mode synthesis methods, the suggested method can be particularly effective for the forced response analysis of a structure subjected to parameter changes with time, such as a missile launch system, and/or having localized non-linearities, because this method does not need to construct the governing equations of the combined whole structure. Both the loaded interface free-free modes and free interface modes can be employed as the modal bases of each sub-structure. The sub-structure equations of motion are derived using Lagrange multipliers and recurrence discrete-time state equations based upon the concept of the state transition matrix are formulated for transient response analysis. The suggested method is tested with two example structures, a simple lumped mass model with a non-linear joint and an abruptly parameter changing structure. The test results show that the suggested method is very accurate and efficient in calculating forced responses and in comparing it with the direct numerical integration method.
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.
Flow in the Stirling Regenerator Characterized in Terms of Complex Admittance Part 2: Experimental Investigation
Authors: Organ A J , Rix D H
Published: February 2007

Experiments are described that support analysis of the practical Stirling cycle in terms of linear waves. All aspects of the theoretical approach are corroborated, including the incidence of amplitude attenuation and marked phase shift between pressure-time records on either side of the matrix, together with the overriding importance of the dimensionless groups N MA and NSG in characterizing these features.
Parametric Excitation Instability of a Rigid Unbalanced Rotor in Short Turbulent Journal Bearings
Authors: Russo M , Russo R
Published: February 2007

The influence of oil-film turbulence on the parametric excitation instability of a symmetrical unbalanced rotor in short bearings is analysed for different values of Reynolds number. The method of calculating the journal orbit is described together with the method for predicting the synchronous orbit whose stability is to be evaluated.

In addition to examples of calculated and predicted orbits, stability maps are given for dimensionless unbalance values equal to 0.2, 0.3 and 0.4 and for the Reynolds numbers of 2500, 5000 and 10000.
The Stress Concentration Produced by a Hole near an Interface or Joint
Authors: Kelly P A , Hills D A , Nowell D
Published: February 2007

Solutions are presented for the stress concentration arising in bonded dissimilar elements weakened by a circular hole. The influence of both of the Dundurs constants (which quantify the mismatch in elastic properties of the two materials) is presented, and it is shown that the stress concentration produced is greater than that produced in an infinite body if the hole exists in the stiffer medium, and vice versa. The method of solution adopted is the distribution of dislocations around the periphery of the hole.
Generation of Smith Shocks in Gears during Oil Starvation
Authors: Smith J D
Published: February 2007

Failure of the oil supply to a gearbox leads to breakdown of the oil-film between teeth after extended running. The progressive stages in the surface contacts, which initially improve the gears and then give failure, can be monitored using the Smith shocks, which are generated at the asperity interactions.
Monitoring the Running-in of Gears using Smith Shocks
Authors: Smith J D
Published: February 2007

The progress of the running-in of a pair of test gears was monitored using the shocks which appear to be associated with asperity contact between rough surfaces. Variations of vibration levels with torque, speed and amount of running-in were recorded. Some possible explanations are proposed for the observed trends which were not as expected.
Subharmonic, Quasi-Periodic and Chaotic Motions of a Rigid Rotor Supported by an Eccentric Squeeze Film Damper
Authors: Zhao J Y , Hahn E J
Published: February 2007

This paper analyses the complexity of the unbalance response possible with a simple rigid rotor supported by an eccentric squeeze film damper. The damper forces are obtained from the ‘π’ film short bearing approximation to the Reynolds equation and a fourth-order Runge-Kutta integration is used to evaluate the rotor response. Poincaré maps, rotor trajectories, bifurcation diagrams and power spectra are used to elucidate and to illustrate the diversity of the system behaviour. It is shown that for a large unbalance and static eccentricity ratio, the system can exhibit undesirable jump phenomenon and subharmonic, quasi-periodic and even chaotic motions, which limit the operating conditions at which dampers should be used.
Rollover Threshold of Partially Filled Tank Vehicles with Arbitrary Tank Geometry
Authors: Ranganathan R
Published: February 2007

Rollover threshold limits of partially filled tank vehicles equipped with tanks of arbitrary cross-sections are estimated using a simple methodology. Overturning moment caused by the lateral liquid shift within a partially filled arbitrary tank geometry is obtained as a function of the tank shape, fill level and the gradient of the free surface of liquid. The liquid load shift computed using a set of closed-form equations, developed based on the tank shape and fill level, is compared to those obtained from a comprehensive software developed based on a numerical technique. The static rollover threshold of the tank vehicles with arbitrary tank shapes are estimated by balancing the total overturning moment against the restoring moment. The results are compared to those obtained from a kineto-static analysis of tank vehicles.
Trends in Rail Transit: London Underground and Hong Kong Mass Transit Railway Corporation
Authors: Newton Wilfrid
Published: February 2007

This paper compares the development of the London Underground and Hong Kong metro systems. The author describes the environment that both systems operate in. He concludes by outlining the steps being taken to modernize London Underground.
Rail Corrugation: Characteristics, Causes and Treatments
Authors: Grassie S L , Kalousek J
Published: February 2007

Corrugation is a phenomenon which has excited the interest of railwaymen for more than a century, but for which there often does not appear to be a cure. It has generally been realized that there are in fact different corrugation mechanisms, and that some types of corrugation can indeed be prevented. The present paper draws upon both the literature and the authors' experience to categorize corrugation according to two mechanisms: that damaging the rail (wear, plastic flow etc.) and that fixing the corrugation wavelength. Six types of corrugation are thus identified and described by the following proposed terminology: ‘heavy haul’, ‘light rail’, ‘ooted sleeper’, ‘contact fatigue’, ‘rutting’ and ‘roaring rails’. Both mechanisms are well understood for all but the last type of corrugation, for which a convincing and well-validated wavelength-fixing mechanism has yet to be demonstrated. Despite the absence of this understanding, satisfactory treatments of, and in many cases also means of preventing, all six types of corrugation have in fact been developed. Excitation of the vehicle's unsprung mass on the track stiffness is the most common wavelength-fixing mechanism.
High Angle of Attack Missile Aerodynamics
Authors: Dexter P C
Published: February 2007

A major influence in the aerodynamics of missiles is the significant amount of separated flow encountered for most flight conditions. This flow may be of an ordered nature, forming vortices, or random, such as encountered in wing stall. At high angles of attack the vortices of the body leeside flow may become unpredictably asymmetric, even on geometrically symmetric configurations, and their interactions with wing and tail panels can result in possible control problems. The modelling of such flows both accurately and easily is beyond present capabilities.
Mechanical Cooling Systems for use in Space
Authors: Bradshaw T W , Orlowska A H
Published: February 2007

This paper describes the development of long-life cooling systems for use in spacecraft. The original single-stage coolers were developed by the Rutherford Appleton Laboratory (RAL) and Oxford University for the Improved Stratospheric and Mesospheric Sounder (ISAMS), an Oxford University instrument that will be part of the National Aeronautics and Space Administration's (US) (NASA's) Upper Atmosphere Research Satellite. Since then RAL has continued development of these coolers to produce lower temperatures and the technology has been transferred to industry via the British Technology Group (BTG). This has been possible by the award of contracts from the European Space Agency (ESA) and internal funding.

The coolers are now available from industry and have been baselined for a variety of future instruments both in Europe and the United States.