bluuebunny/crossref_metadata_2025 huggingface dataset:
Superconducting Marine Propulsion Power
Authors: Appleton A D
Published: February 2007

Over the last 25 years a large amount of research and development has been undertaken on the application of superconductors to marine propulsion systems and a number of superconducting homopolar motors and generators were constructed between the mid 1960s and the early 1980s. The paper reviews this work and shows that the technology had almost reached the point where industrial exploitation could have commenced. The reason why these machines did not reach the market place is discussed together with the impact which the recently discovered higher temperature superconductors may have upon future developments. Reference is made to a new ship which has been constructed in Japan and which derives its thrust directly from electrical energy using superconducting magnets in an engine based upon magnetohydrodynamics (MHD). With the exception of the MHD ship and the programme in the United States all of the work on d.c. machines described in this paper has been carried out by or under the direction of the author.
Variability in Thermal Performance and Measured Heat Rate in Fossil-Fuelled Power Plants
Authors: Carvalho F L , Conradie F H D , Kuerten H , McDyer F J
Published: February 2007

The paper examines the variability of key parameters in the operation of ten thermal power plants in various commercial grid environments with a view to assessing the viability of ‘on-demand’ plant performance monitoring for heat rate declaration. The plants of various types are limited to coal- and oil-fired units in the capacity range of 305–690 MW generated output. The paper illustrates the influence of control system configuration on effective and flexible power plant management. The analysis of variability indicates that there is a reasonable probability of achieving adequately stable operating periods within the normal operating envelope of grid dispatch instructions when thermal performance monitoring and display can be undertaken with a high confidence level. The levels of variability in fuel quality, which were measured during nominally constant levels of fuel input and generated output, range from about +1 per cent for oil-fired plants to about ±5 per cent for coal-fired power plants. The implications of adopting on-line monitoring of unit heat rate as an input to the generation ordering and unit commitment process are potentially significant cost and energy conservation benefits for utilities having a high proportion of coal- and oil-fired generation.
Evaluation of Windage Losses for High-Speed Disc Machinery
Authors: Etemad M R , Pullen K , Besant C B , Baines N
Published: February 2007

Design and development of experimental apparatus is detailed for stator drag torque measurement as well as a method to evaluate rotor windage losses directly from air mass flow and temperature changes. Effects of air jets at the rotor rim were also investigated. Results are presented for air windage losses associated with ultra-high-speed machinery. These show that within the range investigated the air gap length between the rotor and the stator has an insignificant effect on windage losses. The lowest windage losses were encountered when air was forced through the rotor/stator gap from the direction of rim to bore.
In-Cylinder Measurement of Mixture Strength in a Turbocharged Natural Gas Engine
Authors: Charlton S J , Jager D J , Tawfig M E
Published: February 2007

Measurements of in-cylinder mixture strength, during compression and combustion, were made on a natural gas engine using a novel fast-response flame ionization detector (FID). The Collings FID was found to be an effective instrument for measuring the spatial and temporal development of mixture strength in such engines. It is necessary when using the FID to establish suitably controlled bench tests to validate its pressure independence. Other parameters, such as the transit time and the frequency response of the instrument, may be confirmed by similar bench tests. A comparison is made between experimental measurements of mixture strength in the prechamber close to ignition and the results of a computational fluid dynamics (CFD) study of the mixing processes.
Analytical Optimization Design of Radial and Mixed Flow Turbines
Authors: Chen H , Baines N C
Published: February 2007

The optimization of radial and mixed flow turbine design, based on simple one-dimensional aerodynamic principles, is described. The objective is to minimize energy losses by reducing the inlet and exit velocities of the rotor. The procedure is based on the specification of a loading coefficient. Previous work has shown that turbines of this type have loading coefficients that lie in a narrow band, and so suitable values can be readily determined. A more detailed specification of losses is unnecessary for the optimization. Optimizations are described for zero and non-zero inlet blade angles, and zero, positive and negative exit swirl conditions.
The Development and First Commercial Application of an Innovative Diesel Engine Based Cogeneration System
Authors: Nash F
Published: February 2007

This paper covers the development of a cogeneration (combined heat and power) system based upon a compression ignition, reciprocating, internal combustion engine and a standard three-pass economic shell-and-tube industrial boiler as well as the first commercial application of the system. An innovative feature of this cogeneration system is that additional fuel is burnt to utilize the free oxygen in the engine exhaust gas (a practice common with gas turbines but rarely attempted with reciprocating engines) to provide a significant, fuel-efficient and easily variable increase in the high-quality heat, that is steam, output from the system.

The initial development work was done in 1983 using heavy fuel oil as the fuel to both engine and burner, while the first commercial application in 1988 utilizes a dual-fuel engine (gas and diesel oil pilot or diesel oil) and dual firing of the exhaust gas duct burner with gas or diesel oil.
A Theoretical Study of a Variable Compression Ratio Turbocharged Diesel Engine
Authors: Rychter T J , Teodorczyk A , Stone C R , Leonard H J , Ladommatos N , Charlton S J
Published: February 2007

A variable compression ratio concept that can give a different expansion ratio to the compression ratio has been evaluated by means of a simulation of a turbocharged diesel engine. The compression ratio is controlled by varying the ratio of the connecting rod length to the crank throw, hence the name variable crank radius/connecting rod length engine (VR/LE). The VR/LE mechanism kinematics have been defined and described, and the compression ratio and expansion ratio have been presented as a function of the eccentric phase angle (αo). A zero-dimensional engine simulation that has been the subject of comprehensive validation has been used as the basis of the VR/LE study. The effect of the compression ratio on the engine performance at fixed loads is presented. The principal benefits are a reduction in fuel consumption at part load of about 2 per cent and a reduction in ignition delay that leads to an estimated 6 dB reduction in combustion noise. The study has been conducted within the assumption of a maximum cylinder pressure of 160 bar.
Influence of Nozzle Sac Volume on Diesel Spray Droplet Sizes
Authors: Farrar-Khan J R , Andrews G E , Williams P T
Published: February 2007

The influence of nozzle sac volume and associated changes in the fuel hole upstream flow on the spray atomization, velocity and penetration were studied. Four injectors, designed for applications in 1 litre per cylinder diesel engines, were investigated with the same 215 bar injector nozzle opening pressure and fuel flow quantity. A Malvern 2600c Series diesel spray laser diffraction spray analyser was used. Significant differences in the spray characteristics were found which helped to explain some of the emission differences between the four injectors.
Development of European Gas Supply and Demand and Prospects for Gas Use in Power Generation
Authors: White N
Published: February 2007

Demand for natural gas in Europe is expected to grow rapidly, particularly for use in power generation, as a result of technological developments and regulatory action to protect the environment.

While there is no shortage of gas reserves to meet this potential demand, there is uncertainty over how rapidly such reserves can be developed and marketed, and at what level of cost. It seems probable that incremental gas supplies will be available only at higher prices than those being paid today, as a result of rising gas supply costs. However, it would appear that gas prices can rise further before other fuels become more commercially attractive in the power generation sector.
In Situ Decommissioning—the Radical Approach for Nuclear Power Stations
Authors: Brown G A , Hancock R , Cooper R D
Published: February 2007

In situ decommissioning (ISD) is a radical approach to the disposal of nuclear reactors by burying them on-site beneath a mound of suitable material. The engineering and construction of the mound is dealt with and the selection of suitable material. The radiological impact of leaving radioactive materials on-site is studied and it is concluded that ISD could be a solution for some sites.
Decommissioning of Nuclear Reactor Systems
Authors: Large J H
Published: February 2007

The decision-making process involving the decommissioning of the British graphite-moderated, gas-cooled Magnox power stations is complex. There are timing, engineering, waste disposal, cost and lost generation capacity factors and the ultimate uptake of radiation dose to consider and, bearing on all of these, the overall decision of when and how to proceed with decommissioning may be heavily weighed by political and public tolerance dimensions. These factors and dimensions are briefly reviewed with reference to the ageing Magnox nuclear power stations, of which Berkeley and Hunterston A are now closed down and undergoing the first stages of decommissioning and Trawsfynydd, although still considered as available capacity, has had both reactors closed down since February 1991 and is awaiting substantiation and acceptance of a revised reactor pressure vessel safety case. Although the other first-generation Magnox power stations at Hinkley Point, Bradwell, Dungeness and Sizewell are operational, it is most doubtful that these stations will be. able to eke out a generating function for much longer.

It is concluded that the British nuclear industry has adopted a policy of deferred decommissioning, that is delaying the process of complete dismantlement of the radioactive components and assemblies for at least one hundred years following close-down of the plant. In following this option the nuclear industry has expressed considerable confidence that the decommissioning technology required will he developed with passing time, that acceptable radioactive waste disposal methods and facilities will be available and that the eventual costs of decommissioning will not escalate without restraint.
The Secret Brain Drain
Authors: Lewinton Christopher
Published: February 2007

This paper discusses a hidden disease currently afflicting British industry—the invisible brain drain within Britain caused by the failure of industry to attract the best brains. Reasons are given as to why this occurs and constructive goals are described in an effort to reverse the trend. Only by producing winning companies can Britain hope to regain its role as a major industrial nation.
A Moving Object Detection Process for Computer Vision Application
Authors: Shieh I , Gill K F
Published: February 2007

The aim of this paper is to present a novel method for processing a digitized image that will allow pertinent information to be extracted on object movement in a scene. A frame difference method locates the moving candidates in a region which is evaluated by a hypothesis testing procedure to identify accretion and deletion regions. Accretion regions are selected and used as seeds to search for moving objects in the current frame. Contour tracing is applied to establish the boundary of an accretion region which is then used to help recognize the moving object. The results of this work reveal that motion can be used as an effective cue for object detection from an image sequence.
Incremental Forming of Flanged Sheet Metal Components Without Dedicated Dies
Authors: Powell N N , Andrew C
Published: February 2007

This paper describes research that has investigated a process for forming flanged sheet metal parts without dedicated tooling by repeated localized deformation—an incremental process. The complete formation of a shrink flange over a former by a grooved roller, moving around the flange in a series of passes, is analysed by the finite element method and reasonable agreement with experimental results shown. Some evidence is presented that the use of a grooved roller can extend the forming limits of a conventional single die pressing operation. The predicted reaction distribution at the fixed edge of a variety of flanges during their incremental formation by different rollers is then examined. It is shown that the most significant reactions are limited to the vicinity of the current position of the roller. This result leads to a proposal that the form tool might be replaced by non-dedicated tooling, to support the component web only in the region near to the roller. This proposal is tested experimentally and the principle of a dieless flange-forming process is successfully demonstrated. Such a process may be of benefit to any industry that produces a variety of flanged parts in small batches, for example airframe manufacture. Further research is proposed to develop a prototype machine based on the principle outlined here.
Cutting Tool Selection: An Intelligent Methodology and its Interfaces with Technical and Planning Functions
Authors: Maropoulos P G
Published: February 2007

This paper presents a new cutting tool selection methodology, namely the intelligent tool selection (ITS), which covers the whole spectrum of tool specification and usage in machining environments. The selection process has five distinct levels and starts by deriving a local optimum solution at the process planning level, which is progressively optimized in the wider context of the shop-floor. Initially, multiple tools are selected for each machining operation and tool lists are formed by sorting selected tools in order of preference. The second selection level provides a tooling solution for a component by considering all the operations required as well as the characteristics of the machine tool. The selected tools are then rationalized by forming a set of tools for machining a variety of components on a given machine tool at level 3 and by increasing the use of common and standard tools within a group of machines at level 4. Finally, the fifth level aims at reducing tool inventory by classifying existing tools into categories according to their usage and is also used for introducing new tools into the manufacturing system.

The selection method allows the implementation of the minimal storage tooling (MST) concept, by linking the ordering of new and replacement tools to production control. ITS also uses the concept of tool resources structure (TRS), which specifies all tooling resources required for producing a component. By using the framework provided by ITS, TRS and MST it can be shown that tooling technology interfaces with diverse company functions from design and process planning to material/tool scheduling and tool management. The selection methodology results in higher utilization of tools, improved efficiency of machining processes and reduced tool inventory.
Towards a Manufacturing Technology for High-Volume Production of Composite Components
Authors: Rudd C D , Kendall K N
Published: February 2007

The last decade has seen strong interest from high-volume manufacturers such as the automotive industry in the development of processes which provide cost effective routes to the manufacture of components in fibre-reinforced composite materials. This paper considers one family of processes that have been targeted as offering a solution—that of resin transfer moulding (RTM)—and reviews the findings of work based at the University of Nottingham. The mechanisms involved are examined together with the variants on the basic process and the implications for high-volume production. Consideration is given to process technology, materials and the relationship between design and manufacture. A route to high-volume manufacture based upon computer aided engineering is proposed.
Finite Element Analysis of Four-Roll Pass Cold Rolling
Authors: Wen S W , Hartley P , Pillinger I , Sturgess C E N
Published: February 2007

This paper presents a study of the mechanics of deformation of the four-roll pass cold rolling using an elastic-plastic finite element program. This process has been developed at the Anshan Institute of Iron and Steel Technology, People's Republic of China, where a new four-roll pass small section cold rolling mill has been built. The initial finite element analysis has been carried out for the rolling of 8 mm square section bar from 10 mm diameter round stock under dry friction conditions. The results show clearly how the areas of plastic deformation develop during the rolling process. The distributions of the generalized stress and the generalized plastic strain, both on the longitudinal symmetrical plane and on the transverse cross-sections of the workpiece, have been obtained, and the pressure distribution along the arc of contact has been determined. In addition, the roll separation force and the pass elongation of the workpiece predicted by the finite element program have been compared with the corresponding values measured in experiments when rolling 6.5 mm square section bar from 8 mm round material with machine oil lubrication. Good agreement has been obtained.
The Politics of Industry
Authors: Warren Kenneth
Published: February 2007

From a career in the aeronautical and electronics industry, rising from the shop floor and university to management, Kenneth Warren entered Parliament in 1970. During his time in Parliament he has been Chairman of the Conservative Back-Bench Aviation Committee and of the Western European Union's Science and Technology Committee. For four years he was Parliamentary Private Secretary to Sir Keith Joseph in the Department of Trade and Industry and then Education and Science. Currently he is Chairman of the British Russian Parliamentary Group as well as the Select Committee on Trade and Industry.

Having visited some eighty countries, led parliamentary delegations overseas on a number of occasions and contributed papers at technical conferences in the United Kingdom, the United States, Holland, France, Japan and Hungary, he has a world-wide interest in the development of engineering and markets for technology.

Communication between industry and politics and vice versa is not at the level of quality required in a major supplier/customer relationship. The author will develop a thesis on how this interface can be eroded. He will base his lecture on a background of international experience in politics and industry, including the Chairmanship of the Select Committee on Trade and Industry and as one of the four qualified engineers in the House of Commons.
An Expert System Designed for Success
Authors: Kirwin S V , Boyes J
Published: February 2007

Expert systems have been in use in industry for several years and many have gone some way towards providing effective solutions to what would otherwise be tedious manual tasks. This paper describes the development of a medium size personal computer based expert system, currently in use by a major aircraft manufacturer, and explains the various development stages that have enabled it to be successful. The techniques used to develop this expert system are discussed and will prove useful to other knowledge engineers.
Development of an Integrated Process Planning-Based Cae System for Cold Forging
Authors: Lee R S , Hsu Q C
Published: February 2007

In this paper, an integrated system for computer aided engineering of cold forging, based on the development of a knowledge-based process planning system, is proposed. The system is integrated into a structure of computer software which combines the experience-based design guidelines and the science-based analysis and simulation. By using the proposed system, the manufacturing engineer can obtain an engineering solution between cold forged part design and part manufacture. The implemented system consists of cold forging process planning, plasticity analysis of the forging process, die design and die manufacture, and production simulation. Several industrial examples were given to demonstrate the concept of a proposed intelligent system.
Manufacturing Management in Strategic Uncertainty
Authors: Mcintosh M K
Published: February 2007

Using defence as the particular case, the paper outlines the strategic uncertainties facing British manufacturing, and comments on the responses available to Government and industry. It focuses on international trends and the United Kingdom's place in a restructuring world. It goes on to argue for competitiveness based on technological excellence and rapid adoption of international best practice, combined with a more aggressive approach to uncompetitive activities, particularly when they flow through to competitive sectors.
Deep Drawing with a Fluid Pressure Assisted Blankholder
Authors: Yossifon S , Tirosh J
Published: February 2007

The feasibility of replacing the rigid blankholder in the conventional deep drawing process with a ‘soft’ hydrostatic fluid pressure is examined. The recommended fluid pressure range (the ‘working zone’) which guarantees a sound product in different circumstances is presented. The locus curve for possible failure by wrinkling of the flange and the locus curve for possible ductile rupture along the wall provide the lower and the upper limits respectively of the ‘working zone’. These loci are found by a systematic series of deep drawing tests with different constant fluid pressure blankholders for three kinds of materials (copper, aluminium and stainless steel) at various thicknesses and friction conditions. The influence of the friction coefficient, the drawing ratio and the workpiece wall thickness on the blankholder fluid pressure needed to suppress flange wrinkling becomes evident experimentally.
Implementation Requirements for Electronic Standard Component Catalogues
Authors: Culley S J , Webber S J
Published: February 2007

The majority of information regarding standard components is currently delivered to the engineering designer in paper-based catalogues. These generally contain performance and physical data together with methods for selecting the appropriate component. When engineers are engaged in a design problem requiring the use of a standard component, they are faced with mantially searching the catalogues and carrying out calculations by hand. The tedious and time consuming nature of this activity frequently means a nonoptimal component is chosen on the grounds that it has been used before. Computer aided selection of components seeks to improve the efficiency in this situation, with the aim of providing access in an unbiased way to the most appropriate item. Experience has shown that this does not just mean the implementation of selection algorithms; the user is looking for a wide range of facilities in the ‘electronic catalogue’. Yet the increasing number of packages that are now available are widely deficient. This paper aims to set out the requirements for comprehensiveness for what will be the delivery medium for standard component information in the next decade.
A Network Technique for Metal Flow Analysis in the Filling System of Pressure Diecasting and its Experimental Verification on a Cold Chamber Machine
Authors: Sulaiman S B , Gethin D T
Published: February 2007

This study reports the results of analysis and measurement of metal flow in the pressure diecasting process. The analysis involved the simplification of the Navier Stokes equations and solution of the resulting set using a network method. Since the filling system is an important part of the pressure diecasting process, this aspect was, studied. Concurrently, an experiment to measure pressure in the diecasting process was carried out on a cold chamber machine to obtain the pressure history and flow characteristics. The predicted results were then compared with experimental data and agreement between them was achieved. In addition the fill of an actual part type has been carried out to illustrate the modelling capability.
Investigation into Development of Liquid Layer and Formation of Surface Plasma During CO2 Laser Cutting Process
Authors: Yilbas B S , Davies R , Gorur A , Yilbas Z , Begh F , Akcakoyun N , Kalkat M
Published: February 2007

Interaction studies between the liquid metal and gas jet during laser cutting were made and relationships between the various parameters influencing the cutting action were identified theoretically. In the theoretical analysis, the effect of the jet on the process, due to jet momentum and the interface (gas-liquid) shear stress, were considered. On the experimental side, the work was carried out in two parts. In the first part, cutting of mild steel at the different thickness levels was carried out using an argon/oxygen gas mixture at 5/1 pressure ratio and 138 kPa total pressure. The depth of resolidification around the keyhole resulted from the cutting process and was examined microscopically. In the second part, the motion of plasma generated during the laser cutting process was monitored using a CCD (icharge coupled device) camera, fibre-optic probe and microlens camera. In this case oxygen was used as the assisting gas.
Parametric Minimum Film Thickness Performance of an Elastic Big-End Bearing under Inertial Load
Authors: Aitken M B , McCallion H
Published: February 2007

Big-end bearing design has, in the past, been well served by design charts. However, in more recent times, simple design-level information has not kept pace with developments in bearing analysis.

This paper presents simple parameterizations of the effects of con-rod distortion on dynamic big-end minimum film thickness performance. Non-dimensionalization of cyclic minimum film thickness, film mechanism transitions, bearing flexibility and inertial load enabled quantitative tribological measures of elastic geometry to be developed.

This characterization, ratified against corresponding full analyses, provides a useful new insight into elastic con-rod bearing design, something hitherto based on experience and intuition.
Kinetostatic Modelling of an Unconventional Motion Conversion Mechanism in Application of a Plunger Pump System
Authors: Wang W G , Mucino V H , Smith J E , Lyons D W
Published: February 2007

The development of a mathematical model of Stiller-Smith mechanism for the application of a four-cylinder plunger pump system is presented. The magnitude and direction of the internal dynamic load are obtained by solving a set of equations using the overall geometric parameters, prescribed motions, inertia distribution and applied torques on the system. The simulation presented here yields the history of the internal loads, which are then normalized with respect to the required peak output load on the plungers, through an entire rotary cycle. The approach allows for the development of further design criteria through parametric sensitivity studies.
Prediction of Vibration Behaviour of Large Turbo-Machinery on Elastic Foundations Due to Unbalance and Coupling Misalignment
Authors: Simon G
Published: February 2007

A computational assessment of the vibrational behaviour of turbo-sets on elastic foundations is of significance with regard to the design and optimization of the complete installation. Using modern computer programs, for example, MADYN, and refined modelling techniques, the natural and response behaviour of even large systems can be calculated reliably, but there does remain some uncertainty, especially with regard to vibration excitement. The present contribution develops possibilities of how to handle these problems.
Computer Simulation of a Variable Fill Hydraulic Dynamometer: Part 2: Steady State and Dynamic Open-Loop Performance
Authors: Hodgson P G , Raine J K
Published: February 2007

Part 1 of this paper presented a theoretical model for the torque absorption and energy dissipation processes in a variable fill Froude-type hydraulic dynamometer. Effects of working compartment geometry changes on steady state running full torque absorption performance were also shown. Part 2 presents both steady state and dynamic computer simulations of an engine-dynamometer system under open-loop control. Comparisons between model simulations and test bed data show that the dynamic model reproduces both the negative torque-speed dynamometer characteristics and other transient phenomena that occur under real open-loop partial fill conditions. Requirements of control systems to modify this behaviour and ensure stable set point holding are introduced. Part 3 of the paper will deal with the simulation of the engine-dynamometer system under closed-loop control.
A Flow-Continuity Approach to the Analysis of Hydrodynamic Journal Bearings
Authors: Paydas A , Smith E H
Published: February 2007

Results are presented from a new model of the lubricating film in journal bearings. This is based upon flow continuity and permits more realistic rupture and reformation boundary conditions to be employed. In dynamically loaded arrangements, this implies that oil-film history is accommodated. Comparisons are presented between available experimental measurements and theoretical predictions of bearing performance. It is shown that combinations of stationary grooves and rotating oil holes can be handled by the computer programs employed.
Optimal Synthesis of Point Contact Restraint
Authors: PhD Y L Xiong , Sanger D J , Kerr D R
Published: February 2007

The object of this paper is to develop a procedure that will allow the establishment of necessary and sufficient point contacts on a rigid body to ensure that the body has any desired state of instantaneous motion or restraint. The screw space and its sub-spaces are employed; these are vector spaces but not Euclidean spaces. The states of restraint and instantaneous motion of a body restrained by a system of screws of point contacts are specified by reciprocal sub-spaces of the screw space. This leads to a synthesis procedure for restraint of a rigid body by means of point contacts. The existence and uniqueness of the synthesis solution are discussed, and necessary and sufficient conditions for a realizable surface of a kinematic pair are given. Finally, two quality measures for a feasible set of screws are defined. One represents the uniformity of the distribution of internal forces while the other indicates the restraint's ability to resist external forces.
Numerical Simulation of Fluid Flow in Poppet Valves
Authors: Vaughan N D , Johnston D N , Edge K A
Published: February 2007

Simulations of flow through poppet valves were performed using a proprietary finite volume computational fluid dynamics program. A range of valve geometries was simulated, and the flow was turbulent, incompressible and steady. Simulations were compared with experimental measurements and visualized flow patterns. Qualitative agreement between simulated and visualized flow patterns was good. However, errors in the prediction of jet separation and reattachment resulted in quantitative inaccuracies. These errors were due to the limitations of the upwind differencing scheme employed and the representation of turbulence by the κ-ɛ model, which is known to be inaccurate when applied to recirculating flow.
An Analysis of the Mechanical Forces in Latch Needle Cam Systems
Authors: MacCarthy B L , Sharp J M , Burns N D
Published: February 2007

The majority of textile fabrics are either woven or knitted. Knitted fabrics are most frequently produced on weft knitting machines. The range of machinery is very diverse but the same basic mechanism is employed to convert textile yarn into knitted textile fabric. The mechanism is a specialized needle and cam system known as a latch needle cam system. This paper develops a general model for the mechanical forces that arise in normal operation of a latch needle cam system. The limitations of previous models are noted. The model may be used to predict mechanical forces for any specified cam profile and for the most common needle and cam arrangements. The model will be used in a following paper on yarn forces in latch needle cam systems. The performance of the model will be reported in a following paper describing an experimental programme and experimental results
A Simple, Accurate Method for Calculation of Stresses and Deformations in Elliptical Hertzian Contacts
Authors: Dyson A , Evans H P , Snidle R W
Published: February 2007

The note describes a simple and highly accurate numerical routine for calculating contact pressure and dimensions in elliptical Hertzian contacts. A FORTRAN implementation of the routine is given.
Catastrophe Theory, Curve Veering and the Vibration of Bladed Discs
Authors: Afolabi D , Alabi B
Published: February 2007

The problem of vibration in bladed disc assemblies is discussed in terms of catastrophe theory and the ‘curve veering’ phenomenon. A region in the bifurcation diagram of a bladed disc where unstable vibration amplitudes could occur as a result of coupling and mistumng is identified.
Vibration Control of Conical Shells Using Viscoelastic Materials
Authors: Khatri K N
Published: February 2007

The vibration and damping analysis of multi-layered conical shells incorporating layers of viscoelastic materials in addition to elastic ones, the former causing dissipation of vibratory energy, is the subject matter of this paper. The analysis given herein uses Hamilton's variational principle for deriving equations of motion of a general multi-layered conical shell. In view of the correspondence principle of linear viscoelasticity which is valid for harmonic vibrations, the solution is obtained by replacing the moduli of viscoelastic layers by complex moduli. An approximate solution for axisymmetric vibrations of multi-layered conical shells with two end conditions—simply supported edges and clamped edges—is obtained by utilizing the Galerkin procedure. The damping effectiveness in terms of the system loss factor for all families of modes of vibrations for three-, five- and seven-layered shells is evaluated and its variation with geometrical parameters is investigated.
Externally Pressurized Hemispherical Fibre-Reinforced Plastic Shells
Authors: Blachut J , Galletly G D
Published: February 2007

The results of external pressure tests on ten 0.8 m diameter torispherical shells made from FRP (fibre-reinforced plastic) were discussed in a recent paper by the authors. In the present paper, the results of similar tests on six hemispherical FRP shells are given. Four of the hemispheres were made from single sheets of woven pre-preg (three of carbon-fibre-reinforced plastic and one of glass-fibre-reinforced plastic): two of those made from carbon-fibre-reinforced plastic (CFRP) were petalled, that is they were made by butt-jointing together pieces of composite cloth. The diameter-average thickness (D/tav) ratios of the hemispherical domes varied from 66 to 108.

The BOSOR 4 program was used to predict the stresses in the composite shells and their buckling pressures; the Tsai-Wu equation (in stress space) was utilized for the material failure criterion. For all the shells in this investigation, the controlling failure mode appeared to be first-ply failure (FPF). The latter is, of course, influenced by the compressive strength of the composite. Assuming a reasonable value for this (for example 570 N/mm2 for CFRP) gave ratios of Pexpt/PFPF which were in the range 1.05–1.19. In all cases, the experimental result was higher than the theoretical prediction, that is it was on the safe side.

The authors measured the compressive strength of the CFRP composite experimentally. They obtained values in the range 510 ± 100 N/mm2. These were less than values obtained at Imperial College (664 ± 44 N/mm2). At the moment, it is not known why this wide variation in compressive strength was obtained. More work needs to be done on this aspect of the problem.

Each of the butt-jointed CFRP hemispherical domes was weaker than its unjointed counterpart. In part, this is due to the increase in thickness of the unjointed hemispheres near the clamped edge, where the failures originated. With the CFRP torispherical domes, the failure location was at the spherical cap/knuckle junction (that is away from the clamped edge) and the butt-jointed torispherical dome turned out to be stronger than its unjointed counterpart.

The 30-ply CFRP hemisphere (D/tav = 66) was 1.4 times as strong as the 36-ply GFRP hemisphere (D/tav = 73). In addition, the 30-ply CFRP hemisphere had the same collapse pressure as a geometrically similar welded steel hemisphere which had D/t ≈ 113 and a = σYP = 645 N/mm2. The CFRP dome would be much ligher than the steel one, in the ratio 1:2.8.
Signature Analysis of Roller Bearing Vibrations: Lubrication Effects
Authors: Su Y-T , Sheen Y-T , Lin M-H
Published: February 2007

This study investigates the vibration signature of roller bearings, induced by the surface irregularities of components, under various lubricating conditions. The bearing vibration is modelled as the output of the bearing assembly which is subjected to the excitations of surface irregularities through the oil-film. The oil-film acts as a spring between the roller and race. The stiffness of oil-film under different lubricating conditions is studied from the empirical equation of minimum oil-film thickness. It is shown that the vibration spectra of a normal roller bearing may have a pattern of equal frequency spacing distribution (EFSD) whose frequency information is similar to that of a damaged bearing. Under large loading and low running speed, the vibration energy is low if the lubricant viscosity is high. On the other hand, at high running speed, the vibration energy is high with high lubricant viscosity.
Analytical Investigation of the Load Capacity of the Full Squeeze-Film Bearing
Authors: Van Eetvelt P , Holmes R
Published: February 2007

Numerical computation has been used in the past to indicate that the full squeeze-film bearing has no dynamic load capacity in the presence of a static load. It is shown in this research note that this can be proven analytically.
Reduced Order Modelling of Non-Linear Squeeze Film Dynamics
Authors: Esmonde H , Fitzpatrick J A , Rice H J , Axisa F
Published: February 2007

The contribution of non-linear forces to the dynamic performance of liquid squeeze films is examined as a function of film thickness and fluid viscosity. The linear and non-linear component forces are identified from experimental data for two thicknesses at viscosities of 1.0, 13.19 and 26.87 cS using procedures based on random excitation. A procedure by which terms that contribute little to the overall dynamics of the model can be eliminated is developed and applied to the experimental data. This leads to a reduction in the complexity of the model for particular systems by removing those terms that have little significance. The technique is then validated by examining the relative contributions of the non-linear forces using a numerical simulation.
A Thumb-nail Sketch of the Gas Processes in the Stirling Cycle Machine
Authors: Organ A J
Published: February 2007

The gas processes in the Stirling cycle machine are usually modelled in the Eulerian reference frame. In Lagrange coordinates the energy equation by itself is a transparent statement of the physical phenomena involved, and is simple symbolically. It is virtually a ‘one-line’ description of the gas processes at all locations and at all points in the cycle.
The Application of the Wigner Distribution Function to Machine Tool Monitoring
Authors: Zheng K , Whitehouse D J
Published: February 2007

The Wigner distribution function has been investigated both theoretically and practically to assess its suitability for machine tool diagnostics. It is demonstrated that it is potentially useful for detecting incipient chatter and generally characterizing changes in the workpiece statistics as a result of poor machining.
Vaporizer Performance
Authors: Liu C H , Perez-Ortiz R M , Whitelaw J H
Published: February 2007

Measured values of fuel droplet velocity, size and flux are presented for a vaporizer based on a T-shaped duct with upstream atomization by a single axial jet and by six radial jets. They were obtained for a practical range of kerosene and air flowrates and inlet air temperatures with the vaporizer in free air and in a sector of an annular combustor with combustion. Phase Doppler velocimetry was used to measure droplet velocity and size distributions and was complemented by photographic visualization of the flames within the combustor.

The results obtained outside the combustor, and without combustion, showed that the Sauter mean diameter of the droplets ranged from 20 to 60 μm and the liquid-fuel flux from 0.2 to 30 per cent of the total fuel as the inlet air temperature was increased from that of ground-idle to that of full power. The droplet size and liquid-fuel flux also diminished with an increase in air flowrate, and an arrangement of six radial jets resulted in better atomization than an axial arrangement. The corresponding fluxes with combustion were in the range between 0.1 and 8 per cent as a consequence of heat transfer from combusting gases to the vaporizer tubes.

Experience with the vaporizer operating within the combustor at fuel flowrates and inlet air temperatures representative of take-off showed that the vaporizer performance could deteriorate rapidly due to the formation of carbon deposits, particularly in the region where the flow impinged on the cross tube. The deposits led to reduced heat transfer and vaporization with a consequently larger proportion of larger droplets and a tendency for the region of intense combustion to move downstream.
Identification of Surface Characteristics from Large Samples
Authors: Kovacevic R , Zhang Y M
Published: February 2007

Surface roughness characteristics have been modelled by autoregressive moving average (ARMA) models. Frequently, extra-large samples from the surface are available. Due to the non-linearity and the computational burden dependence on sample size, the available data can not be sufficiently utilized to fit ARMA models in most cases. In an attempt to sufficiently employ the available data, an innovative ARMA identification approach is presented. The computational burden of this approach is nearly independent of the sample size. The accuracy ratio between the present approach and the non-linear least squares algorithm is determined. Both simulation and application have been conducted to confirm its effectiveness.
Fatigue Strength of Thick-Walled Cylinders Containing Cross Bores with Blending Features
Authors: Masu L M , Craggs G
Published: February 2007

This paper reports on an investigation into the fatigue strength of thick-walled cylinders that contain a small transverse hole or cross bore in the cylinder wall having either a chamfer or a blending radius at its intersection with the main cylinder bore. Fatigue tests surprisingly show that plain cross-bore cylinders having thickness ratios K = 1.4 and 2.0 have a fatigue life that is marginally greater than comparable cylinders with blending features. A finite element investigation shows that local high stresses are produced on the surface of blending features and these stresses are considerably greater in magnitude than those found in plain cross-bore cylinders. These stress findings are used to explain the experimental fatigue life results obtained.
Heat-Transfer Mechanisms in an In-Line Tube Bundle Subject to a Particulate Cross Flow
Authors: Sterritt D C , Murray D B
Published: February 2007

The effect of solid particles in suspension on heat transfer for tubes located within a square tube bundle of pitch-diameter ratio 1.75 has been investigated. Tests conducted at a Reynolds number of 6000 with mean particle diameters of 58 and 127 μm at a mass loading ratio of 0.5 kg particles/kg air indicate that heat transfer is enhanced at all locations by the presence of the particles. However, at a Reynolds number of 12 000 there is a net decrease in the mean Nusselt number at all positions, with the exception of the first row. Assessment of the main mechanisms by which particles modify heat transfer in in-line tube arrays suggests that the enhancement of heat transfer is a consequence of the increased thermal capacity of the suspension, whereas the reduction in Nusselt number is considered to result from a change in the flow structure and turbulence within the array.
Static and Dynamic Axial Crushing of Externally Reinforced Tubes
Authors: Wang X G , Bloch J A , Cesari D
Published: February 2007

The effect of axial impact on thin-walled circular tubes, which are reinforced externally by a glass fibre reinforced plastic (FRP) composite, is studied in this paper. The influence of circumferential reinforcement on the static and dynamic crushing behaviour of steel tubes is examined. The experimental results show that the crushing mode depends strongly on the circumferential reinforcement. All the reinforced tubes collapsed in a diamond mode with more intensive lobes than the corresponding non-reinforced ones under quasi-static loading conditions. In the dynamic case, for slightly reinforced tubes, the dynamic effect on the crushing mode is not evident, whereas for strongly reinforced tubes, they collapsed in an ‘internal inversion’ mode, which did not appear in the static case.
Wave Problems for Repetitive Structures and Symplectic Mathematics
Authors: Zhong W X , Williams F W
Published: February 2007

Based on the analogy between structural mechanics and optimal control theory, the eigensolutions of a symplectic matrix, the adjoint symplectic ortho-normalization relation and the eigenvector expansion method are introduced into the wave propagation theory for sub-structural chain-type structures, such as space structures, composite material and turbine blades. The positive and reverse algebraic Riccati equations are derived, for which the solution matrices are closely related to the power flow along the sub-structural chain. The power flow orthogonality relation for various eigenvectors is proved, and the energy conservation result is also proved for wave scattering problems.
The Measurement of Force and Torque Using Capacitor Devices
Authors: Falkner A H
Published: February 2007

This paper concerns the use of electrical capacity in the measurement of force and torque as an alternative to conventional strain gauges. It has been established that for some requirements mechanical configurations can be designed with integrated capacitor bridges which combine a good performance with low cost and compactness. Simple electronic circuitry incorporating multiplexing has been developed and used to drive multi-axis devices. Examples include a configuration for measuring the three torques at a point. Work on an integrated circuit shows the possibility of positioning the electronics within a device with a serial digital interface to a host computer.