bluuebunny/crossref_metadata_2025 huggingface dataset:
Buckling of Fibre-Reinforced Plastic-Steel Torispherical Shells Under External Pressure
Authors: Galletly G D , Muc A
Published: February 2007

The paper deals with the buckling of torispherical shells consisting of a steel external layer plus different numbers of composite layers. It is assumed that the total thickness of the fibre-reinforced plastic (FRP)-steel shell is constant but that the thickness of the steel and of the composite may be varied. In the paper it is shown (a) how the orientation of the fibres and the composite lamina thicknesses affect the elastic buckling modes and (b) how substantial increases in elastic buckling pressures may be achieved by reinforcing the steel torispheres with layers of composite. The analysis is carried out for various values of the geometrical parameters describing torispheres, including spherical caps.

The influence of the yielding of the steel layer on the buckling pressures of FRP-steel torispheres is also discussed. As might be expected, it is necessary to take plasticity into account when predicting the buckling pressures of these shells. Some experimental results are given which confirm this expectation.

The effect of initial shape imperfections in the shells is also considered briefly. However, the dearth of experimental results on FRP-steel shells prevents a proper evaluation of the way in which imperfections decrease their buckling strength.
Assessment of a Strategy for Optimum Control of Ignition Advance Angle
Authors: Quayle R S , Bhot S R
Published: February 2007

The control of ignition timing in an internal combustion engine can improve fuel consumption. Electronic control implemented in software with a microprocessor has advantages over conventional mechanical systems. An open-loop electronic system, while incorporating an optimum profile against inlet manifold vacuum and speed, cannot readily adjust for wear. The optimum crank angle at which the peak cylinder pressure occurs has been found to be reasonably constant for a particular engine design irrespective of operating conditions. This paper presents a discussion of the use of this parameter as a measurand for a closed-loop ignition timing system. A discussion is presented of the control strategy used and results demonstrate the ability of the strategy to maintain constant the peak pressure position.
The Optimization of Fuel Enrichment Patterns with Throttle Body Injection
Authors: Boam D J , Finlay I C , Finlay I C , Fairhead G S
Published: February 2007

The influence of fuel enrichment levels on the transient response of a single-point injected engine is reported. The measurements were made on a 1600 cc, four-cylinder engine driving an eddy current brake and linked to a set of inertia flywheels. Throttle ramps of 0.3, 1 and 2 second duration were used and the response of the engine was determined from in-cylinder pressure measurements and, in terms of torque, from the acceleration of the flywheels. The influence of parameters such as manfold temperature and size on the optimum enrichment pattern was then investigated. Measured data are compared with corresponding predictions from a simple model of fuel and air behaviour in the intake system. The results show that for the limited range of conditions explored, the model appears to give a reasonable approximation to the measured values.
Electric Bo-Bo-Bo locomotives for New Zealand Railways
Authors: Roe M J
Published: February 2007

Twenty-two, 3 M W freight locomotives are being supplied to New Zealand Railways Corporation as part of the 25 kV electrification project of the North Island Main Trunk route. The mountainous terrain of this route favours a Bo-Bo-Bo configuration with its good curving performance. Separately excited d.c. traction motors fed from microprocessor-controlled thyristor bridges enable 1000 tonne trains to be started on a I in 50 gradient. The provision of a regenerative brake offers significant energy cost savings.
Gearing up for the Future—Story of Commercial Vehicle Transmission Development
Authors: Parmee K
Published: February 2007

This paper outlines the development of transmissions for commercial vehicles from 1895 to the present day. The contribution of transmission engineers to the automotive industry in the United Kingdom, Europe and the United States is reviewed, and some individual transmission systems are described in detail. The author predicts possible future trends in commercial vehicle engineering.
Training and Skills Requirements for British Rail Depot Maintenance Staff
Authors: Crosby J P
Published: February 2007

The changing technologies and skill requirements in the maintenance of traction, rolling stock and plant and machinery have demanded a reappraisal of the training requirements for mechanical and electrical engineering regional workshop staff. This has led to the development of a modular training programme, which includes segments of training appropriate to the work location and the potential of the individuals.

An investigation of conventional training schemes within British Rail's Mechanical and Electrical Engineering Department was undertaken. The training procedures operating in other transport organizations were also analysed. All types of work progressed in mechanical and electrical engineering areas and depots have been considered, including coach body making, plumbing, welding, as well as fitting and electrical work. Proposals in respect of mechanical and electrical engineering depot strategy which incorporates the impact of design and development of new products have also been considered.

Also included are the implications of the significant change in the maintenance policy introduced in April 1987 for all British Rail's traction and rolling stock, with its emphasis on component changing.

The information gathered from these various sources has enabled key areas for training development to be identified and the future training strategy to be formulated.
Development of New High-Speed Motor Train Units to be Operated on the German Federal Railway Network
Authors: Rahn T , Rahn T , Spöhrer W
Published: February 2007

Following the completion of the new rail lines, now under construction between Hannover, Würzburg, Mannheim and Stuttgart, the German Federal Railway will introduce a new concept in high-speed passenger travel which heralds the use of the new high-speed trains called Intercity-Express.

As a forerunner of this new generation of vehicles, the Intercity-Experimental train was first put into operation in 1985. It incorporates the results of a systematic study of wheel-on-rail research and will open up a new dimension in travel when Intercity-Express is in full operation.

From test running, which on 17 November 1986 led to a new German speed record of 345 km/h, a new series of test results was obtained which is reported here.

The production Intercity-Express trains are briefly described; these will come into fleet operation in 1991.
Jaguar XK120
Authors: Newcomb T P , Spurr R T
Published: February 2007

An account of the genesis of the Jaguar XK120 is given, and the engine and car are described in some detail.
The Motor Vehicle's Contribution towards Achieving Improvement in Air Quality
Authors: Seiffert U
Published: February 2007

The air-quality situation in Europe in relation to automobile exhaust emissions is described. In addition the European exhaust emission legislation and the consequences to engine concepts are discussed.
Relating Vehicle Emission Regulations to Air Quality
Authors: Williams M L
Published: February 2007

The European regulations governing the emissions of gaseous pollutants from gasoline-engined motor vehicles is reviewed and discussed, including the so-called ‘Luxembourg Agreement’. The relationship between the regulation emission limits and those measured in practice from ‘as-received’ vehicles in use is also discussed.

Having discussed the relationship between regulations and emissions, the further relationships between vehicle emissions and air quality are also discussed, giving particular attention to carbon monoxide, oxides of nitrogen and lead.
The Remodelling of Crewe Machine Shops: The Opus Programme
Authors: Lowe P J
Published: February 2007

This paper describes BREL's approach to cost effective small batch manufacture through the introduction of group technology machining cells, new computer systems for part programming and manufacturing control, and the standardization of tooling and raw material.
The Need for Excellence
Authors: French C C J
Published: February 2007

The 1988 President gives a brief resume of his education and apprenticeship and then goes on to review his career at Ricardo Consulting Engineers. He describes some of the projects with which he has been involved, including a torpedo engine, a recycle diesel engine, heat transfer in engines, two-cycle diesel engines and the Atlas research engine. He discusses the future of the reciprocating internal combustion engine and concludes by emphasizing the need for engineering excellence in an increasingly competitive world market.
Evaluation of Wear in a Centrifugal Slurry Pump
Authors: Rayan M A , Shawky M
Published: February 2007

This paper presents some experimental results of erosive wear in a centrifugal slurry pump. The erosion rate of a centrifugal pump impeller is measured by the weighing method. In this part of the study only the erosion of the impeller is considered. Two different concentrations of coarse sand are used. The effect of speed of rotation is also investigated. The experimental results show the correlation between the erosive wear development, and solid particle concentration.

The objective of this investigation is to study the relation between erosive wear in a centrifugal pump impeller and solid particle concentration.
Non-Linear Phenomena in Aero-Engine Rotor Vibration
Authors: Holmes R , Dede M M
Published: February 2007

This paper describes a test facility which reproduces the essential features of a twin-rotor assembly for a medium-size jet engine. Its purpose is to investigate phenomena experienced in an actual engine, which relate to system non-linearities. These phenomena include subharmonics, combination oscillations and jumps in frequency response. All such phenomena manifested themselves in the test facility and explanations are given as to their cause and possible elimination.
A Microcomputer-Based Respiratory Heat Exchange Facility for Use in the Diagnosis of Thermally Induced Asthma
Authors: Farley R D , Patel K R
Published: February 2007

Exercise-induced asthma is prevalent in many asthmatics and during the winter months can be exacerbated by cold air inhalation. A laboratory facility was required to permit early diagnosis of cold air sensitivity in these patients.

This paper describes the development of a modular air conditioning system to produce a range of inhalative thermal burdens and the microcomputer interfacing to measure the rate of airway heat loss imposed. A single-stage refrigerator was built capable of cooling 150 1/min air to —25°C. This was also used to generate dry ambient temperature air by rewarming the chilled air supply. An air humidifier was developed based upon natural convection and evaporation. It was capable of raising 150 1/min ambient air to 37°C, 100 per cent relative humidity.

In two pilot studies of 18 asthmatics it was found that the rate of respiratory heat exchange could be correlated with the magnitude of post exertional bronchoconstriction (lung dysfunction) and that exercise-induced asthma could be minimized by attenuating the rate of airway heat loss.
Validation of Ultrasonic Inspections for Sizewell ‘B’ Pressurized Water Reactor
Authors: Cartwright D K
Published: February 2007

To assist in ensuring a high standard of structural integrity of the Sizewell ‘B’ pressure circuit, components are inspected both during fabrication and in service. The more critical inspections are to be validated. This paper describes the validations of ultrasonic inspections to be carried out at the Inspection Validation Centre, United Kingdom Atomic Energy Authority, Risley.
Investigation of the Mechanical Properties of Bone Using Ultrasound
Authors: Gill P J , Kernohan G , Mawhinney I N , Mollan R A B , McIlhagger R
Published: February 2007

This paper examines the serial use of ultrasonic velocity measurement to monitor fracture healing. New Zealand White rabbit tibiae were fractured using a constant-energy technique and the ultrasonic velocity along the bone measured in animals sacrificed at 16 day intervals up to 96 days from fracture. In parallel with these measurements the mechanical performance of the healed tibiae were determined using a three-point bending test. Regression analysis failed to show a sufficiently good correlation between ultrasonic velocity measurements and the bending properties of healing fractures for the method to be of use clinically.
Failure and Hydrodynamic Function Testing of Explanted Pericardial and Porcine Bioprosthetic Valves
Authors: Fisher J , Spyt T J , Wheatley D J
Published: February 2007

The long-term durability and function of cardiac bioprostheses can be affected by both calcification and mechanical failure of the tissue. The mechanisms of failure and hydrodynamic function of 66 explanted bioprostheses have been studied.

The majority of porcine valves were heavily calcified with leaflet tears adjacent to the calcification at the commissures. These tears caused prolapsed leaflets and regurgitation of between 30 and 70 per cent. Only three porcine valves had tissue failure in the absence of calcification. The majority of pericardial valves failed due to leaflet tears at the edge of the frame in the absence of macroscopic calcification. These tears also produced prolapsed leaflets and large regurgitation in hydrodynamic tests. Three pericardial valves were heavily calcified and stenotic without leaflet tears. Leaflet dynamics in the pericardial valves were affected by host tissue ingrowth which produced increased pressure drops across the valves, an asymmetrical open position and leaflet flutter. In the absence of calcification and leaflet tears, there was little change in the function of explanted porcine valves.
Rheology of Bovine Bone Marrow
Authors: Bryant J D , David T , Gaskell P H , King S , Lond G
Published: February 2007

The viscosity of bovine bone marrow was measured using samples taken from proximal and distal sites of five radii. The viscosity was found to be independent of shear rate and temperature above 37°C (distal samples) and 42°C (proximal samples). The viscosity of all samples fell to a lower limit of 0.04 Pas above these temperatures, irrespective of the treatments used. Below them the measured viscosity of the proximal marrow was some ten times that of the distal marrow at 35°C and some 15 times that of the distal marrow at 30°C. Below 30°C the proximal marrow solidified. Distal marrow remained liquid to below 20°C.
Sailing Vessels—The Search for Performance and Structural Integrity
Authors: Dubois E
Published: February 2007

This paper aims to describe how yacht design methods have changed in the last 20 years and in particular hopes to show how scientific methods have been used to predict and improve performance.

Different craft have different functions and it is important for the designer of a vessel to be able to identify clearly the priorities and to be able to predict a particular vessel's performance, whether it be speed, sea-keeping, manoeuvrability or safety, with surety and accuracy. Equally, it is important for structural integrity to be predictable no matter what material and method of construction are employed.
Modelling Gas Turbine Combustor Flow Fields in Isothermal Flow Experiments
Authors: Bicen A F , McGuirk J J , Palma J M L M
Published: February 2007

Future designs of gas turbine combustors will demand an increasingly detailed understanding of their internal flow structure. Acquisition of complete velocity field information in realistic combustor geometries under burning conditions is, however, extremely difficult, if not impossible, and recourse will always be made to the study of isothermal, constant density systems. Exact similarity between isothermal and combusting flows is clearly not possible. A question is therefore raised as to the most suitable way in which an isothermal experiment may be tailored to make it as closely as possible a simulation of the equivalent burning flow. This is the issue addressed in this paper.

A can-type combustor geometry is studied; this includes a swirler-driven primary zone and two rows of radially inflowing jets. Two flow splits are considered to simulate the burning flow in a geometrically similar combustor with transply walls for cooling. The first split simulates swirler-total and primary-dilution flow ratios. The second split concentrates on swirler-primary and dilution-cross-flow ratios.

Laser Doppler anemometry measurements and flow visualizations obtained in a plexiglass water model show that the first flow split results in atypical and totally unsuitable flow patterns for modelling the burning flow. The second flow split produces much improved flow patterns in both primary and dilution zones. Measurements of both axial and swirl velocity components are provided to demonstrate the acceptability of the resulting flow structure.
Design of a Load Cell for the Wagner Distractor
Authors: Verkerke G J , Koops H Schraffordt , Veth R P H , Nielsen H K L , van den Kroonenberg H H , Grootenboer H J , de Boer L J , van Krieken F M , Wagner H , Pock H G
Published: February 2007

A leg length inequality can be treated by using a Wagner distractor. With this apparatus, it is possible to extend the upper or lower leg slowly. By analysing the measurements of the axial force acting on the femur or tibia the treatment can be optimized and soft tissue damage prevented.

To measure the axial force, a load cell has been designed and constructed. This load cell is built into a Wagner distractor and connected with a specially designed measuring amplifier. The load cell and amplifier do not interfere with the lengthening procedure. They are safe for the patient and have an acceptable error of 7 per cent.
Design Measures to Meet Safety Requirements
Authors: George B V , Appleby J R
Published: February 2007

The approach to achieving a safe design of a nuclear power station is described and is illustrated by reference to the proposed design for Sizewell ‘B’.
Design of a Lengthening Element for a Modular Femur Endoprosthetic System
Authors: Verkerke G J , Koops H Schraffordt , Veth R P H , Oldhoff J , Nielsen H K L , van den Kroonenberg H H , Grootenboer H J , van Krieken F M
Published: February 2007

A malignant tumour may develop around the knee joint of a child. In the majority of cases it will then be necessary to resect the involved bone with adjacent tissue. A joint team of Groningen University Hospital and University of Twente is currently working on the project of developing a modular endoprosthetic system to bridge the defect resulting from the resection. Since the other, normal, leg continues to grow, the endoprosthetic system will have to include an element the length of which can be adjusted non-invasively. The main conditions to be met by the lengthening element are non-invasive continuous adjustability and a maximum total lengthening of 114 mm. This was achieved by using an external magnetic field. Animal experiments showed that the lengthening element worked well, although moisture infiltrated the telescopic tubes and the lengthening element was covered by proliferating bone at an early stage. Also, the necessary magnetic field proved to be larger than calculated. In a revised design, these problems are resolved. In vitro tests show that the new lengthening element meets all requirements.
A Numerical Study of Turbulent Flow Characteristics of Servo-Valve Orifices
Authors: Pountney D C , Weston W , Banieghbal M R
Published: February 2007

A numerical scheme based on the k—e turbulences model has been employed to determine turbulent flow characteristics of servo-valve orifices. Numerical predictions of flow patterns, flow coefficients and pressure variations within the valve orifice are presented and their implications for control of spool forces and cavitation effects are considered. The limitations of the model are considered and a proposal for more effective servo-valve modelling, together with a comparable experimental study, is made.
Measurements and Predictions of the Fuel Consumption and Emission of a Spark Ignition Engine Fuelled with Hydrogen-Enriched Gasoline
Authors: Sher E , Hacohen Y
Published: February 2007

The effect of the amount of hydrogen addition on the fuel consumption and emission of a spark ignition engine has been studied. Dynamometer test results for a wide range of engine speeds, engine loads, equivalent ratio and hydrogen enrichment under steady state operation are presented, and the engine requirements for minimum b.s.f.c. are specified. A detailed model to simulate a four-stroke cycle of a spark ignition engine fuelled with hydrogen-enriched gasoline was used to predict the optimal amount of hydrogen supplement as well as the corresponding minimum best torque (MBT) optimal throttle position and emissions levels of CO and NOx. It has been shown that a significant reduction in the b.s.f.c, in the order of 20 per cent, is achieved with hydrogen-enriched gasoline for a hydrogen-fuel mass ratio of 6 per cent and equivalence ratio of 0.65. A very smooth operation has been observed under these conditions. The energy conversion gain is prominent at partial loads and depends only to a limited extent on the engine speed.
Occupational Hot Exposures: A Review of Heat and Mass Transfer Theory
Authors: Galbraith G H , McLean R C , Stewart D
Published: February 2007

The assessment and control of hot working environments is based on an appraisal of the thermal interaction between an individual and the surroundings. This paper examines in detail the processes of convection, radiation and evaporation which constitute the principal mechanisms for this interaction. The defining equations are discussed with particular attention given to the appropriate numerical values of body heat and mass transfer coeficients. The use of the heat-mass transfer analogy for the prediction of the mass transfer coefficient is introduced and verified. Finally, recommendations are given as to the most appropriate set of energy exchange equations for use in the analysis of high-temperature environments. The physiological criteria involved in hot working conditions, and the generation of a suitable assessment procedure based on the energy exchange equations, are the subject of a companion paper.
Improved Techniques for Measuring the Indentation and Thickness of Articular Cartilage
Authors: Swann A C , Seedhom B B
Published: February 2007

A review of the techniques previously employed in the indentation and measurement of the thickness of articular cartilage has led to new and improved techniques for performing both measurements. By utilizing high-speed, microcomputer-controlled data logging techniques, simultaneous monitoring of signals from a dynamic load cell and a displacement transducer could be made throughout an indentation test. The position of the indenter as it touched the articular surface could thus be determined automatically by identifying the moment at which a positive change in the load signal occurred. Less accurate and more time consuming techniques previously required for determining the position of the cartilage surface were hence avoided. The apparatus also included a critically damped dashpot which prevented any transient loads being applied to the cartilage. Depths of indentation could be measured to an accuracy of 0.005 mm with a measurement repeatability of 2.14 per cent.

By replacing the indenter with a sharp needle, the apparatus was also capable of measuring the undeformed thickness of cartilage. An accuracy of ±0.012 mm could be achieved with a measurement repeatability of 1.2 per cent. The apparatus is particularly suited to survey work where large numbers of indentation tests are to be performed.
Correlation of Breath Sounds with Diagnoses of Lung Dysfunction: Experimental Observations
Authors: Stoneman S A T , Parker R , Jones A
Published: February 2007

An investigation has been undertaken to determine whether there is any correlation between the spectral analyses of breath sounds at the mouth and the diagnosis of lung dysfunction in a small number of patients. The results of the investigation have shown that it is possible to differentiate between the spectral characteristics of the breath sounds of people who are:

normal; asthmatic adult, both before and after the administration of a bronchodilator drug; asthmatic adult, treated with an inhaled steroid, both before and after the administration of a bronchodilator drug; asthmatic child, both before and after the administration of a bronchodilator drug.

The possible applications of the technique are discussed.
Nucleation Phenomena in Flowing High-Pressure Steam: Experimental Results
Authors: Bakhtar F , Zidi K
Published: February 2007

The paper describes the results of an experimental investigation of limiting supersaturation in high-pressure steam. It follows an earlier investigation and to avoid the uncertainties associated with leakage past sliding profiles, the test section has been redesigned and the measurements taken with fixed nozzles. Three convergent-divergent nozzles with nominal rates of expansion of 3000, 5000 and 10000 per second have been used and the inlet stagnation pressures cover the range 25–35 bar. The data consist mainly of axial pressure distributions but some droplet measurements have also been recorded.
Twenty Years of Sulzer Experience with Artificial Hip Joint Materials
Authors: Semlitsch M
Published: February 2007

This paper reviews the development of hip prostheses over the past 20 years with particular reference to the materials employed. The material properties required are discussed and the alloys used in different designs of prostheses are described.
Performance Requirements of Hydraulic Pumps/Motors Related to Non-Conventional Energy Sources
Authors: Rizk M
Published: February 2007

Hydraulic pumps/motors can be connected to different systems which utilize non-conventional energy. These systems produce unsteady output energy even when a control policy is adopted to stabilize it. Therefore, in such systems, hydraulic pumps/motors work under dynamic conditions. This paper presents examples of wind energy conversion systems with different control policies. The available daily wind-power distributions at El-Minia, Wadi El-Natrun and Hurghada in Egypt are calculated. A suitable cut-in wind power is chosen for each site. The maximum rate of change of the available power is determined. The starting input power required to drive a hydraulic gear pump and a hydraulic gear motor, experimentally measured, is compared with the cut-in wind power at the studied sites. An example of the speed dynamic response of the pump and motor is illustrated. The study in this paper reveals that specifications of hydraulic pumps/motors should include, in addition to the static performance, both their frictional torque and dynamic behaviour as well.
Observations of Experimental Research on Oscillating Linear Drives for Small Piston Compressors
Authors: Roubicek O , Pejsek Z , Rozprim J
Published: February 2007

Electric drives provided with an oscillating reluctance or synchronous linear motor and intended to be used in small piston compressors are inherently electromechanical systems. Exclusively electronic control of the drives, based upon special inductance or capacitive methods of measurement of the clearance volume of the driven compressor, enables automatic regulation of the clearance volume to reach the required nominal value or its control, depending upon superior automatic regulation of the output pressure difference, of flow volume (in air compressors) or of the reference temperature of the cooled place (in refrigerating compressors) to the required value. The long-term experimental investigation of research prototypes with the compressors with both types of finely tuned block mechanisms of linear motors of both types enables present-day knowledge to be presented concerning the behaviour and operating and advantageous properties of the developed systems. This experimental research confirmed the favourable influence of the simplified design of the compressors and of electronic control upon the improvement and new possibilities in the construction and also in the application of the compressors.
The Potential of the Stirling Cycle Heat Pump
Authors: Rix D H
Published: February 2007

An important potential application of the electrically driven Stirling cycle heat pump is in the field of industrial waste heat recovery. Here the temperatures and temperature lifts required are often outside the scope of existing types of heat pump. What has to be ascertained is whether the Stirling cycle heat pump can achieve a sufficiently high coefficient of performance.

In the paper this question is examined by the use of a theoretical model. The model is first checked against measured results from an actual Stirling heat pump which has been built and tested, but which was of low COP. It is shown that for a temperature lift of WOK, it should be possible to construct a heat pump with a COP of about 3.5. It is also shown that under these conditions, the maximum attainable specific output of heat would approach 1 J/cycle cm3 of piston displacement.
Thermoeconomic Optimization of a Ventilation Air Heater in a Backpressure Combined Heat and Power Plant
Authors: Kotas T J , Kibiikyo D S
Published: February 2007

In this paper a method of optimization of plant components is demonstrated for the case of a ventilation air heater in a backpressure combined heat and power (CHP) plant. The method, known as thermoeconomic optimization, combines the concepts of exergy analysis with those of economic analysis. The optimization is carried out in two stages. First the heat-exchanger geometry is optimized for a range of different fixed heat-transfer areas using the trade-off between irreversibility due to pressure losses and that due to heat transfer over a finite temperature difference. In the second stage the economically justified cost of the heat-exchanger is determined using a version of thermoeconomic optimization known as the structural method. The concept of the coefficient of structural bonds is discussed and its use in structural investigation and thermoeconomic optimization is explained. Potential for further improvement in the plant efficiency through optimization is discussed with reference to a diagram of exergy flows and irreversibility rates known as the Grass-mann diagram.
High-Speed Photography of Fuel Spray and Combustion Events in a Production Diesel Engine and Combustion Bomb
Authors: Karimi E R
Published: February 2007

The endoscopic high-speed combustion photography technique was used on a four-cylinder Perkins engine to investigate spray formation and combustion events under different engine running conditions. Some tests were also carried out in a fixed-volume combustion chamber (bomb) using conditions similar to those of the engine. The major advantage of using this rig was that each parameter could be varied independently. Spray formation, penetration rate and evaporation were studied in detail. Ignition delay times were established and the location of the start of combustion was identified. Finally, in the analysis of the results the most important factors affecting combustion in a direct injection (DI) diesel engine were outlined.
Foot Strike and the Properties of the Human Heel Pad
Authors: Ker R F , Bennett M B , Alexander R McN , Kester R C
Published: February 2007

Many force-plate records of human locomotion show an impulse (the foot strike) shortly after ground contact. The authors' hypothesis is that this results from the rapid deceleration of a mass (the ‘effective foot’) under forces which compress the heel pad. The quantitative implications are investigated through an illustrative calculation. The observations used are (a) the peak force reached in foot strike (b) the vertical velocity of the foot immediately before ground contact and (c) the properties of the heel pad in compression. Data for (a) and (b) are available in the literature; measurements for (c) are presented here. The deductions are: (a) the time taken to reach peak force is about 5.4 ms, which agrees with published measurements; (b) the mass of the effective foot is about 3.6 kg. The effective foot thus includes a substantial portion of the leg: this seems reasonable. The models used for the calculations clarify the relationship between the foot strike and the shock wave, which it generates.
Biodynamics of the Wrist in Rheumatoid Arthritis—The Enigma of Stiffness
Authors: Walsh E G , Wright G W , Powers N , Nuki G , Lakie M
Published: February 2007

The wrist has been moved rhythmically in the horizontal plane by sinusoidal torques provided by a printed motor. Measurements have been made on normal subjects and subjects with rheumatoid arthritis. Both groups exhibited a resonance, the oscillations being greatest when the applied torque was of certain frequency. In both groups the resonant frequency fell to approximately the same constant value when the torque was raised. While the main relationships were similar a somewhat lower torque resulted in the lowering of resonant frequency in the patients. The relationship between applied torque and peak velocity at resonance was also studied. For a given torque the motion was greater in the patients. No objective signs of increased viscous or elastic stiffness were demonstrable at the wrist in patients with rheumatoid arthritis.
A Conjecture on the Interface Mechanics in Fractures Based on the Interpretation of Impulse Vests
Authors: Brandon J A , Richards J
Published: February 2007

Time-domain tests for monitoring fracture healing, undertaken by the authors and workers elsewhere, show a repeatable characteristic signal behaviour which is difficult to explain using the linear models prevailing in biomechanics. The paper proposes a simple non-linear model which, it is believed, will reproduce the observed signal behaviour and is consistent with the biphasic stiffness model previously identifed in static mechanical testing for monitoring of fracture healing. This, in turn, correlates with the two stages of callus formation in the accepted biological model.
Excitement in Engineering: A Marine Engineer in the Royal Navy
Authors: Vallis M A
Published: February 2007

In this paper the author advances the view that engineering is an exciting profession. He uses examples from his experience in the Royal Navy to support his thesis.
Non-Linear Three-Dimensional Finite Element Analysis of a Cementless Hip Endoprosthesis
Authors: Tensi H M , Gese H , Ascherl R
Published: February 2007

In this finite element study the stresses between a stem component of a cementless hip endoprosthesis (Young modulus of Co—Cr—Mo) and the human femur were calculated for two different loading types. Linear and non-linear models were used to simulate the interface implant bone. Two models, a stem with a porous coated surface over the entire length and a stem with a porous coated surface in the proximal region were compared regarding the load transmission to the femur. An additional calculation of an ‘isoelastic’ stem (Young modulus of cortical bone) was done to show the influence of the stem stiffness.

A porous coated surface over the entire length causes principal shear stresses up to 2.75 MPa in the distal-medial region during level walking. The highest compressive stresses were calculated in the proximal-lateral region as 1.5 MPa in cancellous bone. A more physiological load transmission is obtained by limiting the coated area to the proximal region. All stresses in the two models are lower than experimentally evaluated strengths in the interface between implant and bone.

A strong infuence of the Young modulus of the stem material on the interface stresses was found. An ‘isoelastic’ stem causes compressive stresses in the proximal-lateral region whose values exceed the experimental strength of cancellous bone.
Simulation and Experimental Verification of Completely Closed Cavity Die Forging on a Mechanical Press
Authors: Ibhadode A O A , Dean T A
Published: February 2007

A mathematical model for mechanical press forging is developed and applied to solid cylindrical shapes forged in a sprung completely closed cavity die. It is used to investigate the effects of various process variables on the forging process.

Cold and hot forging tests, using commercially pure aluminium and AISI 1045 steel respectively, were carried out on a 2000 kN mechanical press. Experimental results compared well with those obtained from the theoretical model.
Quality Improvement: What is the Motivation?
Authors: Lascelles D M , Dale B G
Published: February 2007

Quality improvement is a strategic process which requires a breakthrough in the traditional resistance to change generally experienced in most companies. The management of quality improvement is in reality the management of organizational change. So how do organizations become aware that they need to change their approach, behaviour and attitudes to the issue of quality improvement? This paper discusses some possible quality improvement change agents, including: the Chief Executive; competition; demanding customers; a greenfield venture (which may be created artificially); and a restart situation. The case studies presented also outline the factors that contribute to the effectiveness of the change agents in specific situations.
Pulse Dressing in Creep Feed Grinding
Authors: Rezaei S M , Pearce T R A , Howes T D
Published: February 2007

Machining of the roots and shrouds of turbine blades is normally performed by continuous dress creep feed grinding. In this process, the grinding wheel is continuously dressed during the grinding operation, maintaining constant grinding forces and form accuracy. However, continuous-dressing has incurred higher wheel usage. In the tests described in this paper, creep feed grinding of nickel-base alloys was initially performed by continuous dressing to determine the burn barrier and the optimum dresser infeed rate. Pulse dressing, whereby the wheel is kept sharp by a series of dressing pulses, was then applied throughout the grinding cycle in such a way that the grinding forces were kept below the burn barrier. It was shown that wheel usage was reduced by a factor of two with the pulse dressing method. The effect of different grinding coolants under continuous and pulse dressing conditions is also discussed.
The Cost of Capital for Financial Evaluation of Plant and Machinery Capital Proposals
Authors: Mole R H
Published: February 2007

This paper makes the case for the close involvement of engineers in the financial appraisal of proposals for capital expenditure on plant and machinery. Post-tax assessments are now essential for the great majority of companies and this requires a coherent analytical framework which encompasses both the tax cash flows and the impact of tax upon the cost of capital in an inflationary environment. This paper deals with the impact of taxation upon the cost of capital, the discount rate and the yield (internal rate of return) which forms an essential component of modern methods of discounted cash flow financial appraisal. A companion paper considers tax cash flows and shows that the net present value discounted at the net cost of capital may be distorted in comparison to the pre-tax NPV discounted at the gross cost of capital.
Tax Cash Flows in Financial Evaluation of Plant and Machinery Capital Proposals
Authors: Mole R H
Published: February 2007

This paper describes tax cash flows, the tax payments associated with cash returns and the tax savings from capital allowances associated with capital expenditure upon plant and machinery. The post-tax net present value (NPV) of capital equipment proposals is then evaluated at the post-tax cost of capital, which is taken from a companion paper. A numerical example of the post-tax yield (internal rate of return) illustrates the crucial importance of incorporating the effects of a company's capital gearing ratio into financial evaluation procedures. An expression is derived for the ratio of the post-tax NPV to the pre-tax NPV as a function of the project duration, profitability and the capital structure of the company. The post-tax-pre-tax ratio is not just 65 per cent for the current 35 per cent rate of corporation tax, and it is seen to vary over a very wide range. Understanding the nature of such tax distortion will help the engineer to undertake realistic post-tax appraisals of capital projects.
Trends in Military Aircraft Propulsion
Authors: Denning R M , Mitchell N A
Published: February 2007

The major factors determining the choice of engine cycle for a combat aircraft are the requirements of the design mission and those of aircraft speed and agility. The requirement for jet-borne flight in short take-off vertical landing (STOVL) aircraft imposes further demands on cycle and configuration. The changing nature of combat aircraft requirements is the reason for changes in engine design.

Specific thrust is shown to be the major parameter defining engine suitability for a particular role. An examination of mixed turbofan characteristics shows that specific thrust is also the key to understanding the relationships between engine characteristics.

The future development of combat engines is discussed, in particular the implications of stoichiometric limits on cycle temperatures and the benefits of variable cycle engines are examined. Recent work on advanced STOVL (ASTOVL) aircraft is reviewed and aircraft/engine concepts designed to meet the requirements of the role are assessed.

Experience shows that the technology for these advanced engines must be fully demonstrated before production to minimize the risks and costs of the development programme.
A Finite Element Assessment of Clamping Effects in Composite Bolted Joints
Authors: Arnold W S , Marshall I H , Wood J
Published: February 2007

The problem of clamp-up in bolted composite joints has been studied using three-dimensional finite element techniques. In contrast to previous work, a contact analysis has been incorporated enabling both the pin and washer to be modelled. Friction and clamp-up distribution have been shown to significantly effect stress levels in the vicinity of a fastener hole. The results have shown reasonable correlation with experimentally observed strengths and failure modes.
Improving the Load-Carrying Capacity of Interference Fits
Authors: Ramamoorthy B , Radhakrishnan V
Published: February 2007

The application of interference fits is common in engineering. They provide reliable and simple designs capable of taking good static and dynamic load. For a specific fit with certain interference, the performance can be improved by imparting an excellent finish to the mating surfaces. In addition to this there is another possibility to improve the performance of such assemblies. This paper deals in detail with the procedure and the results obtained in this connection.
The Application of a Microcomputer to the on-line Calibration of the Flatness of Engineering Surfaces
Authors: Burdekin M , Pahk H J
Published: February 2007

In this paper, a microcomputer aided system for the calibration of the flatness of engineering surfaces is proposed. Rectangular grid-type measurement procedures with closing error technique are offered for angular assessment on the surfaces using electronic precision level. A new technique called ‘enclose tilt technique’ (ETT) is developed for the analysis of flatness in terms of minimum zone, and defines the flatness in terms of British and ISO standards. These measurement analysis processes are performed on-line with a microcomputer using an analogue/digital interface, amplifier with low-pass filter, triggering technique, etc., and appropriate high-level and low-level programming language. A practical flatness calibration of a granite table has been performed for application, and the results are shown with up to 0.1 μm uncertainty. The effect of the weight of the precision level, and the rigidity test of the granite table have also been assessed.
The Life-Long Education and Training of Mechanical Engineers
Authors: Crossland B
Published: February 2007

Without doubt Great Britain led the world into the Industrial Revolution, and for a considerable period up till the second half of the nineteenth century it could rightly consider itself as ‘the workshop of the world’. The author traces up till recent times why it was that Great Britain lost that position, mainly because of its reliance on engineers learning on the job by picking things up for themselves and learning by rule-of-thumb and ignoring the need for a soundly based education and well planned training. Since the end of World War II various attempts have been made to rectify this position, but without much success, until the Finniston Committee Report. The organization of the Engineering Council, set up in 1982 on the recommendation of the Finniston Committee, is considered, and in particular its responsibility for the engineering profession and for changing the public's perception of industry and the engineering profession.

The author expresses his opinion on the initial education and training of engineers. He comments on the need to reconsider whether mechanical engineering as presently taught is a viable subject, or if a course spanning mechanical and electronic engineering is needed. He sees the objective of engineering education as being a design for total life cost, and he explores how this may be achieved within a total technology concept.

Finally, he considers how to achieve better university/industry collaboration which is at the heart of effective education and training of engineers. He describes the Technology Centre concept recently set up in the Queen's University of Belfast, which integrates the services and resources provided for local industry and those required by the engineering departments of the University as well as providing for continuing education and training. He sees this as the way ahead in achieving close collaboration with industry.
OP-PLAN: An Automated Operation Planning System for Turned Components
Authors: Hinduja S , Huang H
Published: February 2007

OP-PLAN is one of the modules of TECHTURN (1) which is a technologically oriented system for turned components. Given the geometry of the component, OP-PLAN recognizes, in the first instance, features such as threads, grooves and recesses, and then subdivides the rest of the component into volumes. A novel method is presented which determines simultaneously the optimum subdivision of the stock into volumes and the most suitable operation. In arriving at the solution, cost calculations are performed based on optimum cutting conditions calculated with standard tools having indexable inserts. For other features, preassigned operations are used. The sequence of operations is based on commonly accepted rules used in turning and care is taken to ensure that the technological requirements can be guaranteed.

OP-PLAN caters for all axisymmetrical features and therefore it should be able to deal with a fairly large percentage of turned components found in industry. Three examples are included and they highlight some of the features of the system.
An Accurate Low-Friction Pneumatic Position Control System
Authors: Linnett J A , Smith M C
Published: February 2007

A fast, accurate, low-cost pneumatic control system in which the actuator can be programmed off-line to stop at any required position in its travel without the use of mechanical stops is described. A dual-mode control scheme switching two on/off valves is used. The system is able to position a 37 kg inertia load to within ± I mm at any point on a 300 mm stroke in less than a second.