bluuebunny/crossref_metadata_2025 huggingface dataset:
A Study of Highly Turbocharged High-Speed Diesel Engines
Authors: Charlton S J
Published: February 2007

The paper discusses the potential of a conventional high-speed diesel engine for operation at increased power output (+ 50 per cent), using readily available components and ancillaries, whilst retaining the traditional virtues of good thermal efficiency, ruggedness and low cost.

The baseline engine was turbocharged and intercooled having a maximum b.m.e.p. of 14 bar at 1500 r/min. The research engine was designed for, and operated at a b.m.e.p. of 21 bar at the same speed. The results of a computer simulation and extensive experimental programme using an 11 litre in-line six-cylinder engine are presented. The project demonstrates the contribution that computer modelling may make to the design of turbocharged engines, making possible a considerable reduction of the costly development phase.

The effects of compression ratio, valve timing, fuel injection and turbocharger match on performance and mechanical and thermal hading are discussed. Although extended durability testing was beyond the scope of the project, piston, cylinder head and valve temperature measurements show that metal temperatures were within accepted limits. The thermal efficiency of the research unit was consistently within the range 37–38.5 per cent at the target power output, which compares well with the baseline engine.
The Effect of Droplet Size on the Flow in the Last Stage of a One-Third Scale Model Low-Pressure Turbine
Authors: Yeoh C C , Young J B
Published: February 2007

The wet steam flow in a one-third scale model low-pressure turbine has been investigated theoretically using a non-equilibrium throughflow calculation technique. The method is based on the combination of a well-known streamline curvature analysis with wet steam theory. The study centres on the influence of droplet size on the associated supersaturation phenomena in the flowfield, namely, the effect on the massflowrate, the distribution of the degree of supercooling and the magnitude of the thermodynamic wetness loss.
The Relevance of Analysis and Synthesis in Management and Engineering Education
Authors: Muster D , Weekes W H
Published: February 2007

It is beyond argument that, today, our industrialized economies are characterized by sluggish economic performance and relatively low productivity growth rates. The statistical information and accompanying extensive literature that document this characterization have been widely disseminated. Yet, our managers and engineers are hard put to explain the cause of our troubles. Further, they have offered no generally accepted recommendations as to how these trends can be reversed. We have come to realize gradually the inadequacies of the analytical methods that have dominated Western scientific and educational philosophy for over a century. The closed (structured) problems of simplicity identified with the Machine Age demanded skills in analysis with little emphasis on synthesis. In both management and engineering we designed our educational system and methods to fill this need. Now, at the dawn of the Systems Age, managers and engineers are confronted with large-scale, long-term problems of organized complexity. The space shuttle is an example. It is an open (structured or partially structured) problem in which the management of technological change is central. In order to prepare them for other such problems, a case is made here for changing how managers and engineers are educated and trained. The analytical skills associated with reductionism and mechanism would be complemented by introducing and developing the intellectual foundation and tools needed for managers and engineers to use approaches to problem solving based on synthesis supported by analysis.
A Study of Quality Assurance in Small Businesses
Authors: Dale B G , Duncalf A J
Published: February 2007

Recent research by the authors into quality assurance in small businesses suggests that in many cases the approach to the management of product quality leaves room for improvement. The findings indicate that many small companies are unlikely to have: a coherent quality assurance policy and genuine strategy on quality; a separate quality department; produce reports on quality matters; undertake vendor rating of suppliers; and collect and use quality costs as an aid to strategic and tactical quality related decision-making. A possible consequence of this approach to quality may mean the loss of business opportunities due to inadequate product quality or indeed the high costs of maintaining product quality resulting from the inadequacy of the quality assurance policy and ineffective operations in the quality area. If in the long-term, as suggested by the previous and present Conservative administration, the small business sector is to save British industry and even the British economy itself, then immediate steps must be taken to help small firms to get their quality right and to be aware of the influencing factors which management must examine in order to continue effective quality assurance.
The Impact of Microprocessors on Postal Mechanization Control Systems
Authors: Henly H R
Published: February 2007

The impact of the microprocessor on the control systems used in postal mechanization is considered both from the point of view of the effect upon equipment costs, and the intellectual demands placed upon the engineer. Particular emphasis is placed upon the value of the expertise and the disciplined approach which the engineer brings to the design function. It is concluded that developments in this field will continue apace and the engineer must rise to the challenge of applying this technology to an ever widening field.
Computer Aided Layout of Metal Stamping Blanks
Authors: Nee A Y C
Published: February 2007

In a metal stamping operation, the major cost is that of materials; any efforts during the design stage to minimize scrap by selecting interlocking figures or by using careful layouts may result in substantial savings.

A number of template layout solutions has been developed but most of the methods require rather lengthy computation time even on a large computer. In addition, the solutions are not particularly geared towards metal stamping operations.

This paper presents a simplified heuristic solution of nesting metal stamping blanks with near optimum layouts. A complete analysis, including press capacity, coiled or strip stock, cost analysis etc. is also suggested.
Digital Computer Simulation as an Aid in Improving the Performance of Positive Displacement Pumps with Self-Acting Valves
Authors: Edge K A , Brett P N , Leahy J C
Published: February 2007

There is significant and growing demand for pumps with self-acting valves capable of handling water and water-based fluids. This paper describes a study performed on an eight cylinder radial piston diaphragm pump designed for water-based fluid operation. Pumping dynamics have been modelled by digital computer simulation and the results compared with those obtained from an extensive experimental programme. By means of simulation it has been possible to examine the effects of modifications to the original design. The influence of valve mass, lift, and valve seating springs on volumetric efficiency are presented. Delivery manifold pressure fluctuations are predicted using the method of characteristics taking into consideration the configuration and size of the manifold. These predictions are compared with experimental results.

A modular approach has been adopted in the development of the model and as a result it may be readily adapted to suit a wide range of pumps employing self-acting valves.
Acoustic Emission Transducers for the Vibration Monitoring of Bearings at Low Speeds
Authors: McFadden P D , Smith J D
Published: February 2007

The use of acoustic emission transducers for the vibration monitoring of rolling element bearings at low speeds is explored. The frequency response and the base strain and bending sensitivities of the transducers are shown to be important.
Error Analysis of Cam-Follower Systems: A Probabilistic Approach
Authors: Rao S S
Published: February 2007

The actual output kinematic characteristics of a cam-follower system will be different from the theoretical (desired) ones due to errors in manufacture and assembly. A method of evaluating the mechanical error in the kinematic response of cam-follower systems is presented using a stochastic approach. The tolerances on cam profiles and other geometrical parameters are treated as random variables that influence the mechanical error. The equations necessary for the mechanical error analysis of a planar cam-follower system (disc cam with translating roller follower) are derived. The equations for a spatial cam-follower system (globoidal cam with oscillating cylindrical follower) are also given at the end. An optimal synthesis procedure is outlined for the allocation of tolerances so as to minimize the manufacturing costs while satisfying a constraint on the maximum mechanical error in the kinematic response of cam-follower systems. The application of analysis and synthesis procedure is demonstrated with reference to a disc cam with translating roller follower.
A Method of Predicting the Effect of the Dissolved Gas Content of Water on Cavitation Inception
Authors: Naylor P , Millward A
Published: February 2007

A technique has been developed which allows the effect on the cavitation inception number of the gas content in the water to be predicted in cavitation experiments. The predicted results have been compared with data obtained during experiments to measure cavitation inception in the tip vortex of a low aspect ratio hydrofoil and have shown good agreement.

The results showed that the gas content affected the cavitation inception number significantly at low free stream speeds, particularly below about 4 m/s.
High-Frequency Contact Mechanics: The Derivation of Frequency-Dependent Creep Coefficient
Authors: Knothe K , Gross-Thebing A
Published: February 2007

Kalker's creep coefficients for linear rolling contact problems are only valid in the steady state case. An approximate method for the extension of linear contact mechanics into the high-frequency range is presented
The Use of Various Types of Pressure Element in Some Elastic Contact Problems
Authors: Mostofi A , Gohar R
Published: February 2007

The numerical solution to the problem of the contact between an elastic half-space and a punch of rectangular section, is compared with the classical solution. The numerical method uses both triangular and rectangular pressure elements in order to find which gives the more accurate results, especially in the vicinity of the singularity at the punch edge. It is found that rectangular elements generally give a smaller percentage error than do triangular elements. When, however, the pressure elements are used in conjunction with a power law singularity element at each edge of the punch, a considerable improvement in overall accuracy results. Three-dimensional singularity elements are then used in the contact problem of overriding conformal gear teeth, where the normal footprint ellipse has been truncated.
Sonic Flow Through an Abrupt Change in Cross-Section
Authors: Anderson J S , Meier G E A
Published: February 2007

The steady, transonic flow in a rectangular duct following an abrupt change in section has been studied by measuring the density with a Mach-Zehnder interferometer and velocity with a laser-Doppler velocimeter. The flow structure was controlled either by a single, normal shock wave or by a series of reflected oblique shocks. In the case of the normal shock wave structure the one-dimensional compressible flow theory was found to apply adequately to the overall duct. Within the duct the flow was not one-dimensional, but had a minimum velocity in the centre and four shear layers.
On the Performance of Pressurized Fluidized Bed Combined Cycles for Power Generation
Authors: Evans R L , Anastasiou R B
Published: February 2007

The steam-tube and air heater combined cycles utilizing pressurized fluidized bed combustion have been proposed for coal-fired power generation because of their potentially high efficiency and low levels of pollutant emissions. Thermodynamic models have been developed and used to predict the performance of both cycles. The intercooled steam–tube cycle was found to be the most efficient cycle with an efficiency approximately 1.5 percentage points higher than a conventional plant with flue gas desulphurization.
Linear Modelling of Ship Propulsion Plants
Authors: Kidd P T , Munro N , Thiruarooran C , Winterbone D E
Published: February 2007

The extension of a non-linear digital simulation model of a marine propulsion plant, to include an approximate equation for the propeller shaft torque, is considered. It is then shown how linearized transfer-function matrix models can he developed from the non-linear system model. The evaluation of the first order partial derivatives, using the non-linear data in the simulation program, will then be described.
Methods of Taking Samples from Engineering Components for Mechanical Testing—Particularly Remanent Life Assessment
Authors: Barraclough D R
Published: February 2007

Sampling of engineering components to produce mechanical test specimens has recently been used increasingly for post exposure stress rupture testing. In order to obtain a sufficiently large test piece, it is often necessary to remove so much material that the excavated component requires a weld repair before continuing service. Such a repair can necessitate post weld heat treatment, which may be too time consuming for critical plant. A requirement was to design and produce a method of taking small samples, without the need for weld repair of the component, by appropriate consideration of design and stress analysis criteria.

This paper reviews some current sampling methods for producing multiple specimens. Large samples can conveniently be taken by trepanning a full thickness plug, followed by a weld repair. Small samples can be obtained by a new jig, using the chain drilling principle, by joining a series of 3 mm diameter holes, leaving a small excavation requiring only blending out. Various jigs are available to produce samples for gauge diameters up to 15 mm. Very small samples can also be obtained by small, hand held cutting wheels, but these are only adequate to provide metallographic specimens.

Maximum benefit can be gained from the small samples by using them to produce specimen gauge diameters by welding on specimens’ ends. A procedure using electron beam welding has been developed and its initial application to stress rupture of test specimens is reported.

The overall procedure from initial sampling to a post exposure stress rupture programme is outlined and typical current costs are given. Total site and testing cost can be below £5000 and it offers a cost effective route to quantify an extended creep life beyond the design minimum.
Non-Destructive Testing of Mass Produced Components by Natural Frequency Measurements
Authors: Cawley P
Published: February 2007

Vibrations in engineering components may be excited by a light tap and the vibration response may be measured with a microphone and displayed as a frequency spectrum from which the natural frequencies of the component can be extracted. Changes in the natural frequencies of the various modes are observed when small defects such as cracks are present.

The use of this technique for the production quality control of mass produced components has been investigated. Tests have been carried out on a cantilever beam, a piston-shaped component and a pulley wheel. It has been shown that, in the absence of dimensional variations, defects removing between 0.5 and 2 per cent of the cross-sectional area of the component at a single section may be detected, the precise size depending on the geometry of the component and the location of the defect. Dimensional variations reduce this sensitivity, but a method has been developed for correcting the results for dimensional changes, without the need for more measurements to be taken. The results show that, unless the likely location of a defect is known in advance, it is essential to measure the natural frequencies of more than one mode of vibration. The test takes less than ten seconds to set up, about one second to carry out and is amenable to automation.
The Updating of Engineers—Improved Profitability or Just More Courses?
Authors: Cannell R L
Published: February 2007

The purposes of updating are seen as fa) improving job performance, (b) developing the country's engineering manpower, and (c) increasing job satisfaction. This leads to the actions which can be taken by employers, individuals, government and professional institutions, as well as consideration of the part being played by the Engineering Council. The development of updating plans is an important part of implementing future business plans.

Updating is defined as technical and professional development subsequent to first qualification as a professional practitioner. It can cover a wide range of topics dealt with in many ways, ranging from counselling on the job to a specialized short course or the use of distance learning systems. Information technology (IT) is an important example affecting most of industry. Updating courses usually have a short-term objective and are aimed at solving specific problems—they differ in nature from most initial courses. Finally the questions of certifying and quantifying units of continuing education and training are also considered.
A Study of Pressure Fluctuations in the Suction Lines of Positive Displacement Pumps
Authors: Edge K A , de Freitas F J T
Published: February 2007

This paper is a contribution to the understanding of the generation and transmission of pressure ripples in hydraulic systems. Previous research on fluid-borne pressure fluctuations in hydraulic systems has been largely directed towards high pressure lines. This paper examines the behaviour of the pressure fluctuations in axial piston and gear pump suction lines.

It has been found that the unsteady flow taken in by a pump creates a standing wave in the inlet line in much the same way as a delivery line. The magnitudes of the pressure fluctuations are very sensitive to mean inlet pressure, due to changes in inlet flow ripple with mean pressure. No evidence of air release in the inlet line was found and it is concluded that at low inlet pressures air release occurs in the pump inlet passageway, although in microscopic proportions since no reduction in volumetric efficiency was observed. System air-borne noise was found to be very dependent on mean inlet pressure.
Applications of a Computer Model in the Design and Development of a Quiet Vane Pump
Authors: Seet G G L , Penny J E T , Foster K
Published: February 2007

In hydraulic pumps the combined effects of compressibility and of segment and port compression mismatch results in high levels of fluid flow ripple. However, the introduction of resistive flow paths allows correct segment compression by providing adequate leakage from the ports. A computer model has been developed for a novel pump with twin abutments and independently retractable radial vanes. The model computes the flow and pressure histories for the segment and ports, based on compressibility, leakage and geometry effects, and these have been found to correlate well with actual measurements. Using the model, silencing grooves have been shown to be effective in reducing the amplitudes of flow ripples over a wide range of operating conditions. In the pump tested, reductions of 5.4 dB were achieved. Further simulations have shown that lower noise levels could be achieved under optimum conditions.
An Analysis of the Circumferentially Grooved Journal Bearing with Consideration of Lubricant Film Reformation
Authors: Dowson D , Ruddy A V , Sharp R S , Taylor C M
Published: February 2007

An analysis of a central, circumferentially grooved journal bearing has been undertaken. As well as considering the rupture of the lubricant, detailed attention has been paid to film reformation. A computer program has been developed which automatically locates the cavitation region without manual intervention and the numerical analysis technique developed to do this is fully described. Results for the steady state and dynamic performance characteristics of the bearing are presented and predictions compared with other published work where possible. The effect of not considering the reformation of the lubricant film is examined and it is concluded that satisfactory predictions of performance can be obtained for all parameters except the axial flowrate.
An Energy Approach to Linearizing Squeeze-Film Damper Forces
Authors: Hahn E J
Published: February 2007

Analyses of multi-degree of freedom rotor-bearing systems incorporating non-linear elements, such as squeeze-film dampers, generally necessitate time consuming transient solution. Consequently, it is often too expensive to carry out parametric design studies on such systems. This paper presents a general technique for linearizing the non-linear element forces using equivalent stiffness and damping coefficients with energy dissipation and energy storage-release concepts. The approach is illustrated and tested for both centrally preloaded squeeze-film dampers and for squeeze-film dampers without centralizing springs under a combination of unidirectional and unbalance loading. The results predicted by using such equivalent stiffness and damping coefficients agree quite well with those obtained from the full transient solution, even where the unidirectional load exceeds the dynamic load and the damper is operating at high eccentricity. An iterative procedure is proposed which, with the aid of such stiffness and damping coefficients, should significantly reduce the computation time presently needed to carry out parametric design studies on general multi-degree of freedom systems incorporating non-linear elements such as squeeze-film dampers.
Contact Loss at Revolute Kinematic Joints: A ‘Ludodynamic’ Theory Tested
Authors: Haines R S
Published: February 2007

An experimental apparatus has been used to investigate the conditions for loss of contact between the members of a ‘ludodynamic’ journal bearing, that is one with clearance but without hydrodynamic lubrication. In certain circumstances the results are approximately consistent with specific predictions that distinguish a theory published by the author from other theories. Other results are not correctly predicted by any of the theories cited.
Steady State Heat Losses from Horizontal Pipes in an Air-Filled Rectangular Concrete Duct
Authors: Babus'Haq R F , Probert S D , Shilston M J
Published: February 2007

Factors influencing the steady state heat loss behaviours of horizontal ‘supply’ and ‘return’ hot-water pipes, within an atmospheric pressure air-filled, relatively cold, horizontal rectangular trench, are considered. An experimental investigation concerning the effects of the displacement ratios for the two pipes revealed the optimal configuration, that is one which achieves a minimum steady state rate of heat loss from the supply pipe. For one set of temperatures for the pipes and trench walls, the optimal configuration of the supply and return pipes occurred at displacement ratios of +0.70 and −0.05, that is with the supply pipe in the upper region of the cavity and the return pipe vertically below it, the pipes being equidistant from the vertical walls of the trench. This configuration is of significance with respect to achieving maximum energy thrift for district heating pipelines, because it differs radically from the ‘side-by-side’ arrangement of pipes conventionally adopted in district heating practice.
The Vacuum Vessel of JET
Authors: Walravens M J
Published: February 2007

This paper gives a description of the vacuum vessel and indicates the main design criteria. The results of the studies carried out during the design phase and which cover the mechanical behaviour of the chamber during its operation and in particular during plasma hard radial disruptions are reported. The fabrication and assembly of the octants, the particular aspects and problems met during the manufacture of the rigid sectors and bellows assemblies are presented. Finally the assembly and preparation of the vacuum chamber are briefly reported.
Improving Flow Distribution in Centrifugal Compressors
Authors: Polak P , Roberts B D
Published: February 2007

This paper contrasts traditional theory with observed flow patterns and develops explanations based on density variation, spill-over or rapid change of curvature. Impellers modified in the light of these explanations have shown efficiency improvements of 1–2 per cent. Some successes with flow visualization are described.
Conditions under Which Wind Turbines Can Be Financially Viable for Private Power Generation in Industry
Authors: Thabit S S , Primrose P L
Published: February 2007

Methods of evaluating the economics of wind energy conversion systems (WECS) reported in the literature are not readily understood by management in industry, and are not presented in a form suitable for appraising industrial investment in capital projects. This has led to companies being unaware of the advantages of investing in WECS as an option in private electricity generation.

This paper presents the general principles of a comprehensively structured method of investment in a wind turbine, using a company's own local and financial conditions. The return on such an investment for an example company in south-east England is 15.8 per cent, rising to 22.4 per cent if the same company was located in North Wales where wind availability is slightly higher. These results indicate that the prospects of economically viable WECS installations for industrial applications are evident over large geographical areas of the UK.
Design Equations for Preventing Buckling in Fabricated Torispherical Shells Subjected to Internal Pressure
Authors: Galletly G D
Published: February 2007

Design rules to prevent buckling in thin fabricated torispherical shells subjected to internal pressure are not yet available in either the American or the British pressure vessel Codes. They are the subject of the present paper and some possible design equations are suggested. The equations were obtained from the buckling equations for perfect torispheres after considering all known experimental results on fabricated models. The empirical constants in the proposed design equations depend on the type of head construction used, i.e. whether crown and segment or pressed and spun. For both types of head the equations give a factor of safety of at least 1.5. The design equation proposed for the crown and segment heads was also checked on several large vessels which had failed in service. The safety factors found for these cases were all greater than 1.7, which means that the vessels would not have buckled if the design equation had been available at the time.

The other failure mode of these torispherical heads, i.e. large axisymmetric deformations leading to through-thickness yielding, is also discussed briefly. Curves are given which show that, for 300 < D/t < 500, buckling controls the failure mode in some cases and axisymmetric yielding in others. Neither the American nor the British codes recognize that buckling can occur in this D/t range but the theoretical predictions have been confirmed by experiments. However, the amount of test data is limited and more work is needed on the topic.

It is also shown in the paper that, for torispherical shells with D/t ratios in the range 300 < D/t < 500, the axisymmetric limit pressures, pDS, are lower than both the internal buckling pressures and the large deflection axisymmetric yielding pressures. From this, one would expect the failure modes to be axisymmetric in this D/t range. However, as some non-symmetric buckling failures have occurred, the limit analysis predictions for the failure mode are thus not always correct.

One feature of the experimental results on stainless steel torispherical shells which are reviewed in the paper is the relatively poor buckling performance of the heads tested by Kemper in comparison with similar heads tested by Stanley and Campbell. As the values of the empirical constants in the design equations are controlled by the lowest test results, the higher bucking pressures obtained by Stanley/Campbell cannot be utilized unless an adequate explanation for the difference in the two sets of results is forthcoming.
Fluid Transmission Lines—Distributed Parameter Models Part 2: Comparison of Models
Authors: Stecki J S , Davis D C
Published: February 2007

This paper presents a comparison of distributed parameter models of uniform, rigid fluid transmission lines. Analytical solutions to five fluid transmission line models of differing complexity are compared. The theoretical frequency responses of a fluid-filled transmission line are compared with experimentally determined data. Effects of fluid parameters on the accuracy of predicted responses are evaluated.
A Method for Reducing the Corner Wear in Plunge Grinding
Authors: Radhakrishnan V , Achyutha B T
Published: February 2007

There are many cylindrical grinding operations like crankshaft grinding in which the corner radius is critical and hence, the corner wear is important. Studies with a patented side-grooved wheel have shown a remarkable improvement in the performance of the wheel. With the side-grooved wheel, there was reasonable reduction in grinding forces, wheel corner wear and glazing tendencies.

This paper deals with a detailed investigation on the performance of side-grooved wheels in cylindrical plunge grinding applications.
The Need for a Business to Renew Itself
Authors: Ashton E W S
Published: February 2007

In this paper the present method of company reporting is shown to be defective in that profits extracted from the postponement of long-term renewal work are often included in present profits without any indication that the long-term capability has been damaged. A companion paper (1) sets out the factors involved in staying in business and concurs that much better information is reguired concerning these factors.
A Computer Model for Vibrating Conveyors
Authors: Ng K L , Ang L A , Chng S C
Published: February 2007

This paper presents the development of a computer model for predicting the performance of vibrating conveyors with reciprocating, circular or elliptical vibrating excitation. Experimental validation of the computer model for the reciprocating conveyor was carried out. The computer model takes into consideration all the three possible modes of motion (i.e. the throw mode, slide mode and stationary mode) and the transitions from one mode to another. It is based on a single particle mass analysis but using bulk material properties as the input, parameters. The predicted results are presented in non-dimensional plots. An experimental reciprocating vibrating conveyor with variable amplitude and frequency was constructed and tested with padi-rice and wet coal. Agreements between the theoretical and experimental results are good. Contour graphs derived from the non-dimensional plots of the reciprocating vibrating conveyor are also presented for design applications.
The Use of Distance Learning in Industry
Authors: Stephen K D
Published: February 2007

Industry, universities and polytechnics in the UK are becoming aware of the benefits and extent of use being made of distance learning video courses (DLVCs) by their competitors in other countries. In the United States these courses for engineers, scientists and technical managers are now being distributed for credit towards a master's degree by satellite as well as by cassette. Experience in the UK using cassettes and the tutored video instruction (TVI) methodology has shown that the system, when used sensibly, is very cost effective and has several advantages when compared with traditional methods. Grants are now available in the UK to promote the production and use of DLVCs—but rate of adoption depends partly on the attitudes of top management.
High Precision Manufacturing and the British Economy
Authors: McKeown P A
Published: February 2007

In Industry Year, this James Clayton Lecture appropriately addresses the field of manufacturing engineering and aims to contribute to a wider understanding of how our economy and standard of living critically depend on those who design, manufacture and sell the products of high quality necessary to compete in world markets.

The two main thrusts worldwide, in manufacturing engineering are:

Automation—in particular, computer integrated, flexible manufacture to reduce overall cost and lead time and in which CADCAM, FMS and CIM are crucially important technologies Manufacture with higher precision—on which a wide range of advanced technology products are totally dependent—and in which precision engineering, micro-engineering and nanotechnology are generally less well understood and practised than by our main international competitors

The paper traces recent developments in precision engineering in general and several new and non-conventional high precision ‘machining’ processes in particular, including those by which ‘atomic-bit machining’ is possible. Principles and modern techniques for controlling the accuracy of tool to workpiece in two- and three-dimensional work-zones of high precision production machines are reviewed and illustrated.

Today's precision engineering, which can be defined as work at the forefront of design and manufacturing technology, can also be expected to become the general engineering of tomorrow. Its importance to the future of the UK economy cannot be overstated.
Modelling of a Controller for a Flexible Manufacturing Cell
Authors: Chan T S , Pak H A
Published: February 2007

In a flexible manufacturing cell (FMC) the supervisor controller plays a central role in co-ordinating the interaction between various manufacturing, transportation and inspection machines. In this paper, certain control rules for the selection of alternative routes, using transport facilities and machine failure are examined. This analysis is based upon computer simulation of the FMC and its interaction with the cell controller, which is also modelled as a separate entity. The parameters used in the models of the FMC and the controller may be altered independently and their effects may be noted prior to the implementation of the control software.
A Constrained Optimization Technique to Improve the Performance of Strain Gauge Transducers
Authors: MacCarthy B L , Sharp J M , Burns N D
Published: February 2007

An optimization strategy is developed to improve the performance of strain gauge transducers. For a specific transducer configuration, the method used is to select an output characteristic to be optimized and to set realistic constraints on the remaining output characteristics and on physical dimensions. Using this strategy, a non-linearly constrained optimization problem may be formulated mathematically.

Numerical methods to solve problems of this type are discussed and practical details arising from their use are considered. Correctly formulated problems are solvable quickly and efficiently with routines which are generally available.

The techniques introduced here are applicable to a wide range of design problems in transducers of this type and provide a significant design aid.
A Note on the Elastohydrodynamic Lubrication of Soft Contacts
Authors: Hooke C J
Published: February 2007

The clearances in highly loaded non-Hertzian contacts can be calculated directly from the dry contact pressure distribution. This note presents a method of extending the analysis into less highly loaded regions. It is shown that the method accurately predicts the clearance over much of the transition zone for Hertzian contacts and its use in a non-Hertzian situation is illustrated using the contact between a rigid cylinder and an elastomer-lined surface as an example.
Effects of Various Polymer Additives on Cavitation Damage
Authors: Tsujino T , Shima A , Nanjo H
Published: February 2007

Cavitation damage tests in various polymer solutions have been carried out using a vibratory damage apparatus. The relation of weight loss-time, the damage patterns, the cavitation clouds and the damaged area in a polyacrylamide solution, a sodium carboxy-methylcellulose solution, a hydroxyethylcellulose solution, a guar gum solution and a polyethylene oxide solution are compared and are discussed. It is found that the weight losses in the PAM solution and the Polyox solution, which are more elastic, are smaller than the cases of the other polymer solutions and water after sixty minutes exposure to cavitation.
The Flow Resistance of Experimental Models of Naturally Occurring Cracks
Authors: Gardner G C , Tyrrell R J
Published: February 2007

Naturally occurring cracks have rough surfaces which mate in such a fashion as to close the crack completely when the surfaces are pressed together. Experimental work shows that friction factors are given by a Nikuradse type of equation when the crack surfaces are widely spaced. The equation remains applicable as the crack closes until roughness elements from opposing surfaces start to overlap and then an upper limit is achieved. Further reduction in the crack wall separation causes a reduction in the friction factor, which may fall to the level applicable to a smooth-walled tortuous channel. These observations are in accord with theoretical concepts.
The Rheological Properties of Elastohydrodynamic Lubricants
Authors: Evans C R , Johnson K L
Published: February 2007

The methods of measuring the rheological properties of EHD lubricants are reviewed, but for pressures in excess of 1.0 GPa there is currently no simple alternative to the disc machine. A technique has been developed which enables disc machine traction tests to be carried out at constant mean film temperature. Isothermal tests provide further evidence for the existence of a limiting shear stress τc at which the fluid shears in the manner of a plastic solid. At stresses below this limit the experimental data are found to be in very good accord with the non-linear Maxwell rheological model based on the Eyring theory of fluid flow proposed by Johnson and Tevaarwerk and by Hirst and Moore. The model incorporates three fluid properties: shear modulus G, viscosity τ and Eyring stress τ0. Disc machine measurements of τ, τ0 and the limiting shear stress τc for three fluids—a mineral oil HVI 650, a synthetic polyphenyl ether 5P4E and a traction fluid Santotrac 50—are presented for a range of pressures (0.6–2.5 GPa) and temperatures (40–120°C).
A Study of a Fast Self-Tuning Control Algorithm
Authors: Daley S
Published: February 2007

The implementation of a fast self-tuning control algorithm on a microcomputer system is described. The controller, which uses the pole placement approach to self-tuning, is applied to an analogue simulation of an electrohydraulic cylinder drive. It is demonstrated that the controller performs extremely well in tracking both the demand signal and time-varying process parameters.
The Relative Performance Capabilities of Passive, Active and Semi-Active Car Suspension Systems
Authors: Sharp R S , Hassan S A
Published: February 2007

Based on the well-known quarter car representation of the automobile suspension design problem, pdomnce parameters relating to passenger discomfort, working space and tyre load variability are generated for passive, active and semi-active suspension systems. Active systems of two types having different hardware implications are considered, and linear optimal control theory is used in each case to derive a good set o control law parameters. The semi-active systems studied have control laws based on the fully active systems, but are capable only of dissipating energy, so that where the corresponding active system would be acting as an energy supply, the semi-active system switches off Practically realizable switching dynamics are assumed in the calculations. Results for all the systems, for one road surface roughness and vehicle speed, are generated in a form which allows comparison between systems of diffient types which have equal suspension working space requirements. The wider implications of the results are discussed, and far-reaching conclusions about the relative capabilities and design features of passive, active and semi-active systems are drawn.
Modifications to the Method of Characteristics for the Analysis of the Gas Exchange Process in Internal Combustion Engines
Authors: Payri F , Corberán J M , Boada F
Published: February 2007

Some modifications to the method of characteristics for the analysis of the gas exchange process in internal combustion engines are presented in this paper. The modifications are related to the calculation of the path lines and the Riemann characteristic lines at the grid points. Regarding the path lines, the algorithm for the generation and elimination of path lines has been improved, mainly for the cases in which the fluid motion passes from being null or going out of the pipe to going into the pipe. In those cases the algorithm proposed by Benson can cause some mistakes in the entropy level field of the duct. An alternative method is proposed: the duplication ofpath lines. The other modifcation proposed is related to assuming a linear interpolation for the pressure and the volume flowrate between the nearest grid points, rather than assuming a linear interpolation of the value of the Riemann characteristics. These modijcations substantially improve the results obtained in the calculation of the fluid flow in manifolds of reciprocating internal combustion engines.
The Development of a High Comfort, High Stability Rear Suspension
Authors: Cartwright A J
Published: February 2007

Current rear suspension designs for rear-wheel drive high performance luxury vehicles are compromised by the conflicting requirements of handling, stability and passenger comfort. This paper describes the philosophy and development behind the new Jaguar XJ40 independent rear suspension systems and shows that by simple design these compromises can be significantly reduced.
Study of the Trapping of Fluid in a Gear Pump
Authors: Yanada H , Ichikawa T , Itsuji Y
Published: February 2007

In a gear pump, relief grooves are provided on the endplates to avoid the trapping of fluid, and their position has great influence on the performance of a gear pump. However, no definite design has been established on the relief groove position. In order to decide the optimal position of the relief groove, it is necessary to clarify the trapping phenomenon of working fluid in a gear pump. In this study, the pressure in the space trapped by tooth surfaces of the driving and driven gears was measured using a fixed endplate type of external gear pump, specially made, in which a miniature semiconductor type of pressure transducer was installed. The experiment revealed the effects of the relief groove position and the backlash size on the magnitude of the pressure rise in the trapped space and on the performance. The optimal position of the relief groove was made clear.
Design and Construction of the Nchanga Copper Tailings Leach Plant Stage 3
Authors: Hampsheir P R
Published: February 2007

The Nchanga Division of Zambia Consolidated Copper Mines Limited (ZCCM), the largest producing copper mine in the Commonwealth, has recently commissioned a new plant for reprocessing copper rich tailings. The tailings, some 140 million tonnes in total, are stored in large paddock dams. This paper records the problems and successes involved in completing the design, procurement and construction of the project, on time and ten per cent below budget.

Design and project management was by Zambia Engineering Services Limited in Ashford, Kent, a subsidiary of ZCCM, and project funding was from a consortium of international hanks, export credit agencies and development organizations.

The subjects dealt with include process design, project capital and funding, management, design and the use of models, estimating and cost control, planning, purchasing and procurement, construction and commissioning. The paper also highlights the problems associated with funding a new project of this type in the Third World in a depressed metals market, and the role of engineering in overcoming financial delays and transport problems.

Commissioning started in April 1986 and the plant is now coming up to full production with a few, but not unexpected, problems bearing in mind the size and complexity of the plant. With the addition of stage 3 to the tailings leach plant at Nchanga throughput of ore is increased from 850 000 tonnes/month to 1500 000 tonnes/month and copper output by 40 000 tonnes/annum for a total cost of $250 M.
The Influence of Diffuser Channel Geometry on the Flow Range and Efficiency of a Centrifugal Compressor
Authors: Clements W W , Artt D W
Published: February 2007

A small centrifugal compressor was tested with a series of straight wedge diffusers which had included channel divergence angles 2θ ranging from 4° to 14°. Diffusers employing sidewall divergence were also tested. Detailed pressure measurements were made with all of the diffusers. A channel divergence angle of 12° was found to be optimum since increasing the divergence angle beyond 12° produced no efficiency improvements but reduced the flow range of the compressor. Channels employing sidewall divergence produced almost identical efficiency and flow range to channels of the same area ratio without sidewall divergence
Coming to Terms with Complexity—Mechanical Engineering 1986 and Beyond
Authors: Roith Oscar
Published: February 2007

The paper questions whether current engineering practice provides the engineering profession with the ability to adapt flexibly to the technological and economic challenge of the future and discusses some ways forward.
Proposal for a Carbon Fibre Reinforced Composite Bridge across the Strait of Gibraltar at its Narrowest Site
Authors: Meier U
Published: February 2007

Tremendous progress has been made in the construction of long span bridges within the last two centuries. In this evolution structural concepts and strength of materials used have played key roles. The limiting span is defined as that span at which the structural system will just support itself. Comparison is made between limiting spans of cable-stayed bridges made of steel and of advanced composites. The use of advanced composites would allow the tripling of the limiting span in comparison to steel structures. To compare the quantities of material required for the cables of suspension and cable-stayed bridges, calculations are performed. The results are shown within a proposal for an advanced composites bridge across the Strait of Gibraltar.
Advances in High-Speed Phosphor Printing
Authors: Evans D , Spicer C J
Published: February 2007

The development of the optical character reading (OCR) machine for high-speed code marking and sortation of letter mail has led to the need for a high-speed method of printing the phosphorescent code marks used by the mechanised letter sorting machines. This paper looks at the requirements for the printing system, the method adopted and the results achieved.
The Development of Damage-Free Level Transfers
Authors: MacMillan C G
Published: February 2007

The development of new designs of parcel transfer from one conveyor to another at L-junctions and T-junctions is described. The new designs do not incorporate drops, and thus eliminate impact forces and greatly reduce parcel interactive forces.