bluuebunny/crossref_metadata_2025 huggingface dataset:
Three-Dimensional Analysis of Closed-Die Forging Processes: Part 1: Formulation
Authors: Lugora C F , Bramley A N
Published: February 2007

In this series of papers, a theoretical model based on the upper bound elemental technique is presented for prediction of forging load and metal flow in three-dimensional closed-die forging processes. Three basic elements are introduced in order to partition a forging into simple elementary regions. An optimum velocity distribution within the forging is obtained by minimizing the total rate of energy dissipation using a simplex optimizing procedure. Applications of the proposed model are discussed in Part 2.
Fabrication Techniques for Advanced Composite Components
Authors: Potter K D
Published: February 2007

Advanced composites are being used increasingly in the aerospace, and other industries, to reduce weight or improve component performance. A wide range of fabrication processes are available for composites manufacture, each of these has a unique mix of technical and economic features. An understanding of fabrication processes is essential if the designer is to generate cost-efficient design solutions. This paper seeks to present a framework within which fabrication techniques can be compared, via the definition of a hypothetical ideal fabrication process. Consideration of this ideal process enables us to identify the current limitations of four specific moulding processes. Finally development work is described, which was aimed at reducing the limitation of one process, resin transfer moulding, to broaden the opportunities for its cost-effective application.
Assessment of Impingement Effects in the Isentropic Core of a Small Satellite Control Thruster Plume
Authors: Boyd I D , Stark J P W
Published: February 2007

Two computational techniques commonly employed in the calculation of rocket and thruster expansion plumes are assessed. These are the method of characteristics (MOC), which is derived from the continuum Euler equations, and the direct simulation Monte Carlo (DSMC) method, which adopts a discrete particle approach. These techniques vary both in the computational expense and in the accuracy and detail of the solutions that they provide, depending upon the regime of application. The assessment is made with reference to the plume expanding from a small monopropellant hydrazine thruster and concentrates on the isentropic core of the jet for the flow regime lying between the continuum and free molecular limits. It is found that the more numerically intensive DSMC method offers the better correspondence to the available experimental data. In addition, large differences in typical impingement effects such as drag force and heat transfer are found at the free molecular limit of the plume expansion for the two predictive techniques. It is concluded that accurate estimation of impingement potential may only be achieved through application of the discrete particle method.
Gear Steels for Future Helicopter Transmissions
Authors: Davies D P , Gittos B C
Published: February 2007

In order to reduce weight, improve reliability and increase safety, significant changes in the design of future helicopter transmissions are envisaged. Such designs are likely to place new demands on conventional steels which will eventually result in the capability of the gear steels themselves to become the limiting factor, restricting any further opportunities for transmission design and development.
Manufacturing Strategies from Concept to Realization
Authors: Wallis J
Published: February 2007

GEC is one of the major manufacturing companies in the United Kingdom with sales to customers outside the Group of £D5553 millions in 1987–8, of which £D1232 millions were exports.

Little is known about GEC's huge manufacturing capability. Somewhere in the organization, practically every piece of new technology is employed. Radical changes are constantly taking place. Every manufacturing development is designed to meet the requirements of the business which it is to serve.

This paper demonstrates success from matching manufacturing achievements to business needs. Examples will be taken from some of the more mature businesses within GEC where the sceptics may say that change is difficult to accomplish.
A Major Advance in the Manufacture of Large Structural Beams and Columns
Authors: Walker J H , Walpole L B
Published: February 2007

This paper describes the enhancement project undertaken at British Steel's Teesside Works which enabled the Universal Beam Mill to become the first such mill in the Western World to introduce the use of continuously cast slabs as the feedstock for rolling heavy beams and columns.

The change necessitated construction of a new slab reheating furnace, a complete modification of mill rolling practice and involved several engineering developments needed to enable the new process to be successfully integrated within the existing plant. The new process has resulted in significant benefits for the mill's customers and has greatly improved mill performance through a reduction in material yield losses, higher output speeds and improved plant availability.
Degradation of Mechanical Properties by Corrosion Fatigue
Authors: Congleton J , Parkins R N
Published: February 2007

This paper considers the factors involved in corrosion fatigue and looks at the possible effects of solution composition, loading frequency, waveform, electrochemical potential etc. on crack growth rates. Preventative measures are described but no general guidelines can be given as the choice of the most appropriate remedy depends on the system being investigated.
Modified Independent Modal Space Control Method for Active Control of Flexible Systems
Authors: Baz A , Poh S , Studer P
Published: February 2007

A modified independent modal space control (MIMSC) method is developed for designing active vibration control systems for large flexible structures. The method accounts for the interaction between the controlled and residual modes. It also incorporates optimal placement procedures for selecting the optimal locations of the actuators in the structure in order to minimize the structural vibrations as well as the actuation effort.

The MIMSC method relies on an important feature which is based on ‘time sharing’ of a small number of actuators, in the modal space, to control effectively a large number of modes.

Numerical examples are presented to illustrate the application of the method to generic flexible systems. The obtained results suggest the potential of the devised method in designing efficient active control systems for large flexible structures.
The Strength of Surfaces in Rolling Contact
Authors: Johnson K L
Published: February 2007

The common engineering applications of rolling contact are reviewed: the wheel, rolling bearings, traction drives, gears and cams. It is shown that increasing the rigidity of the materials and decreasing the conformity of the surfaces reduces the resistance to rolling, but only at the expense of higher contact stress. The principal modes of failure are described: plastic deformation, contact fatigue, wear, scuffing and corrugation. Recent research into plastic deformation and fatigue is discussed. It is concluded that, if wear and scuffing are controlled by adequate lubrication and surface finish, and clean steel is used, the load capacity and life are governed by the nucleation of micro shear cracks through the action of cyclic plastic deformation.
Dehumidification of Air on a Vertical Rectangular Fin: A Numerical Study
Authors: Coney J E R , Kazeminejad H , Sheppard C G W
Published: February 2007

A theoretical analysis of the performance of a cooling and dehumidifying vertical rectangular fin has been carried out. Conventional fin theory based on the assumption of a uniform and known sensible heat-transfer coefficient was extended by incorporating the condensate thermal resistance and fin thickness into the analysis for gravity-controlled flow during dehumidification. The fin and the condensate layer equations were solved numerically and evaluated for both insulated and uninsulated fin tip boundary conditions, by assuming a Biot number at the fin tip. Numerical results are presented for various psychrometric and flow conditions and compared with those of a dry fin.
Simulation of the Pressure Ripple Characteristics of Hydraulic Circuits
Authors: Johnston D N , Edge K A
Published: February 2007

The pressure ripple in a hydraulic circuit is commonly a major source of noise. A computer program has been written to simulate the pressure ripple characteristics of hydraulic circuits and to aid in the design of low noise circuits. Mathematical models of flexible hose and of pump flow ripple and source impedance have been developed. Validation tests on various circuits show that the program produces good correlation with experimental measurements.

A simple silencer consisting of an asymmetric pipe loop, known as a Quincke tube, was analysed. Its performance was shown to be limited, providing attenuation over very narrow bandwidths.
Transient Double-Diffusive Salinity in a Horizontal Fluid Layer
Authors: Tag I A , Hassab M A
Published: February 2007

The transient double-diffusive stability problem for a horizontal layer of salty water bounded by two rigid isothermal surfaces was examined using both the frozen-time technique leading to an eigenvalue problem and the linear amplification theory leading to an initial value problem. Initially, the layer was subjected to zero temperature and salinity gradients. At the time t = 0, uniform step increases in both temperature and salinity were imposed at the bottom surface while the top surface is impermeable to the diffusion of salt. In the early developing stages scaling lengths based on thermal and mass boundary layer thicknesses were taken into consideration. Several parameters were considered in the analysis, namely, the thermal and solute Grashof numbers, Prandtl number, Schmidt number, time and wave size. Stability results based on the frozen-time technique and the linear amplification theory were compared in order to check the validity of the frozen-time technique within the range of the system parameters considered.
The Lubrication of Slippers in Axial Piston Pumps and Motors—the Effect of Tilting Couples
Authors: Hooke C J , Li K Y
Published: February 2007

In addition to the load from the fluid pressure acting on the piston, slippers in axial piston pumps and motors must carry couples produced by the centrifugal loads from pump rotation and by the friction acting at the piston/slipper ball joint. These couples have a major influence on slipper performance and largely control the slipper clearance and leakage. Small amounts of surface non-flatness are known to be necessary for slipper lubrication and it is shown that, on this basis, the behaviour of slippers when subject to tilting couples can be satisfactorily predicted. Neither the magnitude nor precise shape of the surface profile appears to be of critical importance provided that the slipper lands have a generally rounded and convex profile. Measured clearances under slippers subject to tilting couples confirm the theoretical predictions.
Characteristics of Miniature Short-Tube Orifice Flows
Authors: Fox T A , Stark J
Published: February 2007

This paper presents the results of an experimental investigation into the flow characteristics of miniature short-tube orifices of a type commonly used for fuel injection. From measurements of differential pressure and volumetric discharge it is shown that these devices are susceptible to a cavitation-induced instability phenomenon known as hydraulic flip. It was found that this instability is limited to orifices of length less than fourteen diameters and occurs at a critical pressure differential which varies as a function of the orifice l/d ratio and contraction parameter β. In addition, the performance of the device is examined in terms of the head loss characteristics and it is shown that the mechanisms associated with hydraulic flip have a significant effect on the efficiency of discharge.
Designing for CNC Manufacture
Authors: Hodgson B A , Pitts G
Published: February 2007

An alternative to the transfer of components between machine tools is proposed that makes more effective use of stand-alone CNC machine tools. A design discipline is suggested whose adoption results in components that satisfy the function requirement and which can be machined in a single setup. This results in easier machine-shop scheduling and more straightforward assembly, since the latter is always from a single direction.
The Development of a Direct Injection Diesel Combustion System for Low Noise, Emissions and Mechanical Loading
Authors: Jane P A H , Brear F
Published: February 2007

In recent years the whole climate of diesel engine development has changed with the advent of noise and emissions legislation combined with the demand for higher specific output.

The conventional direct injection combustion chambers that have been used in the 1 litre/cylinder class of engine now present difficulties to the engineer in meeting these increasingly stringent demands.

The development history of a novel combustion system, ‘Quadram’, is presented, leading up to its introduction into quantity production. Emphasis has been placed on achieving the legislative targets while retaining cost effective fuel injection equipment, in an intensely competitive market complicated by worldwide fuel quality variations.

The ‘Quadram’ system is shown to display the key feature of achieving optimum performance with retarded injection timing, without any compromise to engine durability.
A Study on the Accurate Calculation Method of Heat-Release Rate in Swirl Chamber Indirect Injection Diesel Engine
Authors: Liu J P , Ge X K , Peng L X
Published: February 2007

Taking the two chambers of swirl chamber indirect injection diesel engine (SC engine) as two relative but independent thermodynamic systems, this paper builds up thermodynamic equations respectively in the two chambers, together with the mass and enthalpy flow equations describing the mass and energy exchanges between them. This model, based on the synchronous pressure diagrams measured in the two chambers, is used to calculate the thermodynamic state of medium and heat-release process in both of the chambers. Furthermore, with the help of the thermodynamic equivalent system, the calculation of the variable flow coefficient of the connecting passage has been successfully achieved. A Model 6105Q SC engine is taken as a practical calculation example to reveal the combustion pattern of this type of engine. In the last part of this paper, several methods currently used for the heat-release rate calculation have been analysed to show their application field and accuracy.
British Steel—Achieving Industrial Success
Authors: Sambrook G H
Published: February 2007

This paper outlines how in the last decade British Steel management have turned massive losses into very substantial profits. This has been achieved through dramatic improvements in efficiency, demanning, new and more flexible working practices, improved plant utilization and an emphasis on marketing, particularly in the construction industry.
A Supervisory Grid to Understand the Role of the Maintenance Foreman in Process Industries
Authors: Riddell H S
Published: February 2007

The maintenance foreman occupies a critical role in a process industry. He is at the focus of two strong, sometimes conflicting, sets of influences, top-down from senior management, and bottom-up from the maintenance workload and tradesmen. It is a complex and ambiguous role both to the foremen themselves and to their managers. This paper explains why such ambiguity is likely to arise.

A novel matrix is developed comprising four key interrelated domains of the maintenance foreman's role, and into which all the duties he is normally expected to perform can be categorized. The resulting supervisory grid clarifies both the wide scope of these duties, and identifies the two differing personal characteristics which maintenance foremen require in order to succeed in performing them.

The grid has many practical applications. In particular it provides a sound basis for examining the new specialist and diversified roles for maintenance foremen which are now emerging in the process industry.
Experience of Three-Phase Electrical Traction Equipment on the Madrid Underground
Authors: Tejero R
Published: February 2007

This paper discusses the use of three-phase traction on coaches used by the Madrid Underground. The a.c. drive is already in service with urban and inter-urban passenger railways. Once all the technical problems and likely interferences are sorted out, this technology appears to be competitive, profitable, simple, reliable and has overhauling advantages. 170 a.c. drive cars run on the Madrid Underground with very satisfactory experience.
Seat Dynamics and Passenger Comfort
Authors: Corbridge C , Griffin M J , Harborough P R
Published: February 2007

The influence of the characteristics of the vibration input, the seat and the seat occupant on the transmissibility of vertical vibration through railway seat cushions has been investigated. Seat characteristics were found to have a larger effect on transmissibility than occupant or vibration characteristics. Laboratory measurement of the transmissibilities of ten different seat cushions demonstrated that if the cushions were fitted into vehicles, the occupant would receive significantly different rides. The need for standardized dynamic testing of vehicle seating is identified.
Transient Temperature Distribution in Arc Welding of Finite Thickness Plates
Authors: Boo K S , Cho H S
Published: February 2007

This paper introduces a new analytical solution to predict the transient temperature distributions in a finite thickness plate during arc welding. This analytical solution is obtained by solving a transient three-dimensional heat conduction equation with convection boundary conditions at the surfaces of the weldment. The heat source due to electric arc is assumed to take a travelling Gaussian distribution. To prove the validity of the model, a series of GTA bead-on-plate welding were performed on a medium carbon steel under various welding conditions. The isothermal lines of the cross-sectional view at various distances from the arc start were examined and compared with those predicted by the proposed analytical model. The results show that the finite thickness solution well predicts the transient temperature distribution of the finite thickness or thin plates with satisfactory accuracy. Due to the simplicity of the solution method, the developed analytical model may be implemented to the feedback control of the arc welding process or to the optimization of the process parameters.
Safety and Unreasonable Danger as Design Criteria for Engineers: Some Effects of Products Liability Law on Engineering Design
Authors: Muster D
Published: February 2007

In this paper, the interrelated concepts of safety and unreasonable danger (as they apply to industry's products) are discussed in the context of their uses in the courts and design offices. It is shown that safety and design can be brought into essential harmony by defining safety in terms of qualities with meaning in the real worlds of both engineering and the courts. A lexicon of terms is introduced; the terms are used routinely in product liability litigation but are virtually unknown to many engineers. Finally, examples are cited of some industrial products whose designs have been changed as a result of their having been involved in product liability suits. The sense of the conclusions given in the paper can probably be extended, without significant change, to other industrial products.
The ‘Secondary Source’ Method for the Measurement of Pump Pressure Ripple Characteristics Part 1: Description of Method
Authors: Edge K A , Johnston D N
Published: February 2007

The difficulties involved in measuring a pump fluid-borne noise rating are discussed. A new test method is described for measuring the source flow ripple and source impedance of positive displacement hydraulic pumps. This is called the ‘secondary source’ method, and is based on the analysis of the wave propagation characteristics in a circuit which includes the pump under test and an additional source of fluid-borne noise.
The Presentation of Research and Development Plans
Authors: Bergwerk W
Published: February 2007

The planning formats used in industry generally assume that most of the events which make up the plan are known at the outset and that deviations from the plan will arise largely from changes in timing. In research and development work many actions cannot be predicted with any accuracy, not least because they may depend on the outcome of previous activities. As a result, plans for research and development are difficult to present effectively. Even if information on possible alternative actions is indicated at the outset the need for ready modification of the plan remains. The paper distinguishes between the factual, the forecasting and the target setting elements of a plan and emphasizes how the plan should be aimed at communicating with a particular audience. It proposes a way of dealing with the problem of research and development plans by issuing them in carefully related sections, each with its own updating procedure. A format suitable for a typical research situation in a medium sized organization is described as an example.
Large-Scale Combined Heat and Power
Authors: Haywood R D
Published: February 2007

The paper reviews the results of the Belfast, Edinburgh and Tyneside combined heat and power with associated district heating (CHP/DH) studies and highlights the main findings and indicates how these have been used to arrive at a potentially viable scheme. Industrial combined heat and power (CHP) is discussed and examples given of various systems within the United Kingdom. The main parameters in system selection are examined and the availability of suitable software is commented on.
The Application of Weld Repair Techniques to Reduce Costs and Outage Time of Steam turbines
Authors: Hollingworth K J , Ortolano R J
Published: February 2007

The paper outlines the history of the reasons and type of weld repair that have been introduced into the power generation industry in the past ten years. It goes on to illustrate typical repairs that have been successfully carried out on various components in the flow passages of turbines, both in the power utilities and also in the specialized repair companies.
A New Way of Plotting the Cylindrical Blade
Authors: Yan J
Published: February 2007

A new way of plotting the cylindrical blade, shown in this paper, guarantees that the vane setting angle varies linearly and continuously smooth streamlines are thus obtained to avoid flow separation within the impeller channels. The blade contour is the solution to a differential equation in polar coordinates.
Vibration Monitoring of the Internal Centreless Grinding Process Part 1: Mathematical Models
Authors: Lacey S J
Published: February 2007

The grinding process is complex with many interrelated parameters, and an initially stable process can become unstable as grinding conditions naturally deteriorate. Forced vibration from machine rotating elements and self-excited vibration produce a relative radial movement between the wheel and workpiece during grinding and the wheel and diamond during dressing, causing errors in workpiece finish and form. By monitoring vibration produced during the grinding and wheel dressing operations a measure of expected workpiece quality can be obtained.

In order to use vibration monitoring effectively as a means of detecting adverse grinding and dressing conditions it is necessary to gain an insight into the dynamics of the process so that relevant parameters for monitoring are identified. In Part 1 of this paper, with the aid of simple models, the different types of vibration that can occur during the grinding and dressing operations are identified, along with their likely effect on workpiece quality.
Active Vibration Control of a Centrally Clamped Disc by Means of a Piezoelectric Polymer
Authors: Irons J , Kennedy W
Published: February 2007

With the advent of piezoelectric polymers, it is now possible to implement distributed control of flexible structures. Previous investigations of piezoelectric active vibration control have been mainly concerned with beams and beam-like structures; here a thin, centrally clamped steel disc is considered with polyvinylidene fluoride (PVDF) acting as the control actuator. Assuming that the PVDF imparts a controlled moment, and having ascertained the coupling and bonding layer effects, theoretical results are obtained. These results are compared with experimental results.
A Review of the Indirect Calculation of Excitation Forces from Measured Structural Response Data
Authors: Dobson B J , Rider E
Published: February 2007

Using discrete structural models it is possible to predict accurately the response to any form of excitation providing that the behaviour remains linear and damping mechanisms approximate to specific, mathematically describable, forms. Theoretically this process should be reversible so that excitations can be identified and quantified from masured responses. However, in practice this process is often unreliable. This article reviews the work that has been done on force prediction and highlights those areas that require further research.
Squeeze-Film Damping of the Motion of a Control Flapper-Nozzle
Authors: Akers A , Lin S-C J
Published: February 2007

A squeeze film used in a flapper-nozzle affords stand-alone properties to the flapper motion, meaning that it behaves in a dynamically stable manner. The device constitutes the first stage of a new family of two-stage electrohydraulic control valves. Successful mathematical modelling of it has been reported by Lin and Akers (1,2).

Because of the expense of maintaining close manufacturing tolerances within the damper, the investigation included the extent of deterioration of dynamic response when the dimensions of the damper are varied, when the tolerances on the squeeze-film annular area are relaxed and when the annular clearance is increased.

As a result of the investigation, the dimensions and other variables, chosen by trial-and-error procedures, appeared to be optimum from the point of view of dynamic performance, convenience of installation and cost.
Dynamic and Static Axial Crushing of Axially Stiffened Square Tubes
Authors: Jones N , Birch R S
Published: February 2007

The axial impact of thin-walled tubes with square cross-sections, which incorporate axial stiffeners, is studied in this paper. An examination is made into the influences of stiffener depth (T), number of stiffeners (N) and the effect of external or internal stiffening. The experimental results on mild steel specimens of side width c suggest, for a given impact energy, that the permanent axial displacements are not reduced significantly by the addition of stiffeners unless T/c exceeds a certain value.
A Comparison of Orthogonal Transforms in Engineering Computer Vision
Authors: Al-Kindi G A H , Baul R M , Gill K F
Published: February 2007

A comparison of a number of commonly used orthogonal transforms, when applied to the recognition and visual inspection of engineering components, has been made. The impact on the performance and computational time for the machine vision process due to varying numbers of transform coefficients is assessed.
Influence of the Blade Stacking on the Flow Through an Axial Flow Runner and Predictions of Three-Dimensional and Quasi Three-Dimensional Numerical Codes
Authors: Ardizzon G , Pavesi G
Published: February 2007

The influence of the stacking of the blade sections on the flow through an axial flow runner is investigated by means of quasi and three-dimensional finite element programs.

The results show up higher pressure gradients close to the leading edges, in the sections near the hub, when the stacking point is displaced towards the trailing edge. These gradients become noticeable near the trailing edge when the stacking point moves towards the inlet, even if in an attenuated way these trends reverse in sections close to the shroud.

The above-mentioned effects are highlighted only if three-dimensional codes or quasi three-dimensional codes with more than one hub-to-shroud surface are employed.
Elastohydrodynamic Film Thickness in Point Contacts for Arbitrary Entraining Angle
Authors: Greenwood J A
Published: February 2007

This paper investigates the effect of different entraining angles on the film thicknesses in an isothermal elliptical elastohydrodynamic contact, and recommends the simple rule [Formula: see text] where the film thicknesses are found for the same load and speed.
The Influence of Slipstreaming on the Performance of a Grand Prix Racing Car
Authors: Dominy R G
Published: February 2007

During the course of a race a Grand Prix car may spend substantial periods following closely behind other cars, yet the wind tunnel testing of Formula 1 racing cars is almost entirely carried out in an undisturbed air flow. This study demonstrates that the influence of slipstreaming is sufficient to be given much greater consideration during the aerodynamic design process
Complete Balancing of the Stiller—Smith Engine: 4, 8, 12, 16 or More Cylinders
Authors: Craven R P M , Smith J E
Published: February 2007

A review of the Stiller-Smith mechanism is followed by a summary of balancing techniques to date. These are supplemented with further balancing techniques which allow engines with any multiple of four cylinders to be balanced. The use of counter-rotating shafts enables wobble induced by a single four-cylinder Stiller-Smith mechanism to be countered. The advantages and disadvantages of the different configurations are discussed with respect to balancing. Of special interest are two 16-cylinder configurations which are completely balanced without the use of counterweights.
Team-Working: An Automotive Experience
Authors: Bertodo R
Published: February 2007

Despite painful restructuring, the European automotive industry has failed to attain product cost or engineering output parity with Japanese producers and transplant operations. Earlier published work showed that the gap could be closed by a change in the organizational effectiveness and culture. This required the abandonment of traditional function values and deployments in favour of autonomous multi-functional team-working. Experience with such a structure over a period of three years showed major and quantifiable competitive benefits. Important issues, false myths, significant truths and vital enabling needs were revealed during the implementation. These are discussed in detail. Further dramatic gains would seem feasible through the exploitation of information technology.
Computer Aided Engineering for Pistons, Rings and Pins
Authors: Ruddy B L , Kinsella F H
Published: February 2007

Market requirements for high-quality, minimum-cost components developed with minimum lead times necessitate the integration of quality, manufacturing and design activities at the very start of the product life cycle. This paper describes the development of integrated engineering software that addresses these requirements as applied to the design and development of automotive piston assemblies.
A Finite Element Approach to Butt Fusion Welding Analysis
Authors: Shillitoe S , Day A J , Benkreira H
Published: February 2007

A methodology for the simulation of the butt fusion welding process applied to the joining of plastic pipes has been developed using the finite element package ABAQUS as a precursor to a more detailed and extensive simulation. This has been accomplished using a time-stepping approach in which the process is subdivided into small time steps, where melt flow and heat transfer are analysed separately. All the necessary stages in the development of this finite elment model are described and a simulation of the first stage of the welding process, the bead-up stage, is presented.
Improved Cam Profiles for High-Speed Machinery Using Polynomial Curve Fitting
Authors: Sadek K S H , Daadbin A
Published: February 2007

Traditionally, cams are designed using standard curves of harmonic, cycloidal and parabolic functions, which are applied to certain intervals of the cam cycle. In fact it is the discontinuity in the acceleration diagrams of these cams which produces the high harmonics of the running speed and makes them unsuitable for high-speed applications.

Using polynomial curve fitting for the acceleration diagram, one of these cams is smoothed down in such a way that the deviation from the initial lift diagram is minimal. The profile produced is shown to have far fewer harmonics. Furthermore, when the profile was tested using a two-degree-of-freedom model it was shown that the vibration of the mechanism and its tendency to bouncing were reduced significantly.
Modelling and Simulation of the Wheelspin and Gear Loading Processes of a Locomotive During Starting
Authors: Lu G , Sharp R S
Published: February 2007

An analytical investigation of the phenomenon of locomotive wheelspin during starting is carried out. A wheelset-power unit model with 6 degrees of freedom (D-O-F) is developed. It has two non-linear factors: meshing gears having backlash and wheels having different friction coefficients when they stick to or slip on the rail. Calculated results show that the whole spinning process can be divided into four stages. The second and the third stages are destructive to wheel and rail surface, while the fourth stage is the most dangerous to gear strength. Further, a model with 7 D-O-F with elastic driven gear is developed and discussed in detail. The effect of some design parameters on gear impulsive force is also investigated so that the results may be useful in design. It is believed that the models, the equations and the procedure in this study contribute toward understanding of impact behaviours of more complicated locomotive drive systems with frequent stop-and-start operation.
Condition Monitoring of Aircraft High Lift Systems
Authors: Chan K W , Southcombe G , Trmal G J , May A P H
Published: February 2007

Condition monitoring of aircraft mechanical systems is shown to be the next stage in the development of lower cost higher quality maintenance systems. The paper focuses upon mechanical drive systems for the high lift surfaces at the leading and trailing edge of aircraft wings. Monitoring is shown to be feasible and, as well as leading to reduced costs and improved maintenance, could lead to future weight reduction through the approved use of lower safety factors in structural design. The research has shown that mechanical systems of this nature should not be regarded simply as ‘black boxes’ with inputs and outputs. To obtain the full benefits of condition monitoring at low cost, detailed knowledge of the characteristics and behaviour of the system as a whole must be acquired.
Testing of Total Hip Replacements: Endurance Tests and Stress Measurements: Part 2: Stress Measurements
Authors: Humphreys P K , Orr J F , Bahrani A S
Published: February 2007

Brittle lacquer techniques and electric resistance strain gauge rosettes were used to measure strains on the stems of total hip replacements while loaded according to three standards. The stresses in these locations were also calculated and good agreement was found between the measured and calculated values.

The Sines equation was used to calculate the endurance limit stress. Again good agreement was found with observed results. Suggestions are made regarding the endurance testing of hip prostheses.
Coefficients for Solution of the Analytical Freezing Equation in the Range of States for Rapid Solidification of Biological Systems
Authors: Diller K R
Published: February 2007

Solution of the classical solidification heat transfer problem for many biological applications involves states for which roots of the transcendental equation associated with the governing differential equation are not available. These roots are calculated and presented for conditions that characterize a large ratio of solid to liquid phase thermal conductivities and diffusivities and large differences between the initial and final temperatures for the cooling process.
A Design Concept for a Swing-Lock Knee Joint for Whole-Leg Calipers
Authors: Frost R B
Published: February 2007

Whole-leg calipers, extending from the heel to the groin region, have traditionally employed knee joints that remain locked throughout the gait cycle, thereby imposing disadvantages in the dynamics, energy utilization and cosmesis of the resulting gait. A design concept is presented for a knee joint that will allow the knee joint to automatically unlock and relock at appropriate points in the gait cycle, to allow a swing-through gait style to be used.
New Engineering Concepts and Alternative Materials for Prostheses
Authors: Smeathers J E , Wright V
Published: February 2007

This overview paper summarizes work in new materials and designs for prostheses and reports on the papers presented at the Fifteenth Annual Day Conference, held at Leeds, 5 January 1990, by the Bioengineering Group for the Study of Human Joints in association with the Biological Engineering Society.
Power Plant and Systems—An Incremental Approach to a Final-Year Course
Authors: Baines N C , Crane R I , Gibbins J R
Published: February 2007

An optional course has been developed that makes the transition from thermodynamics, as a core engineering science subject, to broader considerations of the supply, conversion and end use of energy. The course is treated as several simultaneous progressions, from components to systems and from detailed analysis to discussion based on case studies and source materials, gradually embracing environmental, social and political as well as technical issues. The motivation for this type of course is described, its objectives, content and organization are outlined, its strengths and shortcomings are assessed and possible future developments are suggested.
A Comprehensive Classification of Combined Cycle and Cogeneration Plant: Part 1: Presenting the Map of Turbomachinery Options for Heat and Power
Authors: Taft M
Published: February 2007

An overall picture of combined gas and steam cycle options, without dependence on numerical analysis, is long overdue. A single equation is derived for plant thermal efficiency. This is based upon component efficiencies and the ratio of steam plant size to gas turbine size. Therefore, a unique map can be graphically presented covering the whole steam range from power generation through to cogeneration (that is combined heat and power) in association with gas turbines.

Understanding of the map leads to recognition of an underutilized area. The gas turbine is normally integrated with the main steam boiler. Conversely, the unfixed combined cycle plant may be integrated with a conventional boiler and back-pressure turbine. The correct steam turbine-gas turbine size ratio must be chosen.

A practical example is given of how a gas turbine and waste heat boiler may be introduced part-way along a large power station's main steam turbine. The integration is achieved in the steam cycle and not at the main boiler. This approach allows low-risk, low capital cost, simple repowering of large power stations. It is not a new thermodynamic cycle, but has the following advantages:

1. The tie between the extent of after-firing and waste heat boiler efficiency is avoided. The conventional boiler is fired and the waste heat boiler is unfired. Integration of the plant occurs at the intermediate pressure level of the steam turbine. 2. The above integration gives high thermal efficiency. It also retains the conventional boiler, or equivalent, which is free to burn a range of fuels. 3. The gas turbine waste heat boilers and the main boiler together fill a common steam turbine of an economic size.

Two types of plant are considered to demonstrate the practical usefulness of the integrated steam cycle. Examples are given based on coal-fired, or heavy-fuel-oil-fired combined cycle plant, integrating conventional boiler, gas turbine plus unfired boiler and steam turbine. The data are based on real equipment, which is either at existing UK installations or plant of known performance.

An explicit analysis is also presented to compare fuel running costs for the integrated steam cycle with costs for both unfired combined cycle plant and conventional steam plant.
Nett Energy Flow Analysis—Constraints on the Growth Rate of Power Station Construction Programmes
Authors: Hill R
Published: February 2007

The construction of all energy supply devices requires an energy input. The intensive programmes of construction of non-fossil-fuel power stations which some have proposed to alleviate carbon dioxide emissions from electricity generation would require a substantial energy input. It is shown in this analysis that the nett energy available to society, that is the energy generated minus the energy needed for construction, is critically dependent on the growth rate of the construction programme. All construction programmes are initially nett users of energy, but a rapidly expanding programme of construction can lead to a nett deficit of socially available energy for 20 years or more, and under some circumstances the entire construction programme can be a nett user of energy.

In particular, it is shown that a programme of construction of nuclear power stations to replace existing coal-fired stations and meet an expanding demand for electricity would produce a nett energy deficit until well into the next century. There would be no possibility of scrapping existing coal-fired power stations until about 20 years after the beginning of the construction programme.
A Simple and Realistic Model for the Scavenging Process in a Crankcase-Scavenged Two-Stroke Cycle Engine
Authors: Sher E , Harari R
Published: February 2007

A semi-empirical model for the scavenging process in a crankcase-scavenged two-stroke cycle engine is proposed. The model is based on the assumption that, typically, the time variation profile of the exhaust gas purity, β, exhibits a sigmoid-type curve while a rounded protuberance usually appears on its back, thus forming a ‘crest’ profile. The hump has been interpreted as the occurrence of an extensive short-circuiting. An exponential function of the form of

is suggested to fit this curve, from which the scavenging efficiency has been derived. Two parameters, namely the mixing degree, b, and the short-circuiting degree, c, are to be calibrated. However, it was found that the selection of the best fitting values for b and c do not depend on the engine speed or on the engine load. Rather, b and c are inherent properties of the engine design. For modern engine design a value of 0.57 is recommended for b and a value of 0.81 for c/c-max. Calculations of the scavenging efficiency were found to be in excellent agreement with predictions of a detailed computer program for three small Schnürle-type different make engines. The present model does not consider a specific mechanism for the gas exchange process, and as such it is believed that it is applicable to other engine types (cross, loop or uniflow) to the same extent.
Deviation in a Mixed Flow Fan
Authors: Matthews R D , Gasiorek J M , Cavanagh J
Published: February 2007

A simple empirical method for calculating the total deviation in mixed flow impellers is proposed. Data are presented which show that the total deviation can be modelled by the superposition of a viscous deviation, related to the blade cascade performance, and an inviscid deviation, due to a secondary flow in the blade passages.

Measured values of total deviation are given together with details of the inviscid secondary flow model. The viscous deviation component is shown to be a function of the modified blade loading parameter used in the correlation of cascade data.
Non-Dimensional Aerodynamic Design of a Centrifugal Compressor Impeller
Authors: Whitfield A
Published: February 2007

A fully non-dimensional preliminary design procedure for a centrifugal compressor is presented. The procedure can be applied for any desired pressure ratio to develop an initial non-dimensional skeleton design. The procedure is applied to compressor design for pressure ratios of 2, 6.5 and 8, and illustrates how the initial design can be developed without recourse to empirical loss models and the associated uncertainties.
The Interaction of Diesel Engine Turbocharging and Tuned Inlet Manifold Systems under Steady State and Transient Operation
Authors: Banisoleiman K , Smith L A , French B A
Published: February 2007

This paper explores the characteristics of inertia charging and turbocharging systems and considers their interaction during steady state engine operation. It also presents experimentally measured engine performance data for four different high-speed DI diesel engines.
Does the Methodology of Teaching Thermodynamics to Engineers Need Changing for the 1990s?
Authors: Mayhew Y R
Published: February 2007

‘Equilibrium’ or ‘classical’ thermodynamics is a relatively stable subject and it is not surprising, after a lapse of only ten years since the last Institution of Mechanical Engineers Symposium (and six years since the Cambridge Workshop), that few fundamental changes of presentation are likely to be proposed. The author raises two questions regarding presentation of the two laws, one question about the current sign convention for work used principally by engineers in the United Kingdom and the United States and one question of balance between the use of tables and of computer databases.
Experiences in Co-Operative Education
Authors: Gibson P R
Published: February 2007

This paper describes a co-operative education programme in mechanical and manufacturing engineering. The background and structure of the programme are considered together with the reasons for its evolution. The programme is offering significant benefits to academe, industrial sponsors and students. There is evidence to suggest that the programme has increased the overall quality of students applying to study mechanical and manufacturing engineering and that a need to supply high calibre technology based professionals who are directly useful to industry is being fulfilled.
The Thermal Performance of the Bonded Carbide Tipped Tool as Compared with Commercially Available Tools
Authors: Waked A , PhD M M Sadek
Published: February 2007

A finite element package has been used to predict the distribution of temperature and principal stresses in bonded and commercial carbide tip, tools. In the bonded tool, the temperature drop across the bond line was found to be small, due to its small thickness The results show that the thermal stresses dominate even under high levels of cutting loads, and were found to be largest further away from the tool tip, while the normal stresses were insignificant in the bond layer. Furthermore, an assessment of the performance of the bonded cutting tool in the presence of a load simulating the cutting process was carried out in relation to the commercial tool. The bonding material was found to decrease the temperature range in the steel shank while increasing it in the carbide tip. It was also concluded that, in general, the stresses arising are smaller in the bonded tool than in the commercial one. This has an advantage in reducing the wear in the carbide tip and increasing the tool life in addition to the known economical advantages found by other investigators.
Prediction of Robot Cycle Time for Threaded Components—Quality Condition Monitoring
Authors: Nwagboso C O , Whitehouse J C
Published: February 2007

The time expended during a particular robot work cycle is an important parameter to be considered when planning a robot application process. In order to predict an economic robot work cycle time, the use of a simple model which can easily be encoded into a computer program will be advantageous. This paper presents some results obtained with an off-line mathematical model for predicting robot work cycle time for quality condition monitoring of threaded components. The model relates the robot motion, end effector performance characteristics and workcell parameters to the task characteristics.