bluuebunny/crossref_metadata_2025_split huggingface dataset:
Transmission Line Modelling of Shaft System Dynamics
Authors: Partridge G J , Christopoulos C , Johns P B 
Published: February 2007

The transmission line modelling (t.l.m.) method is well established as a numerical routine for the solution of electromagnetic wave problems and electrical lumped networks. In this paper the method is adapted for the solution of dynamic mechanical systems. The method provides discrete models suitable for manipulation by digital computer and straightforward modelling of non-linearities. A complete modelling example of a bearing with non-linear friction characteristics is presented.
Three-Dimensional Geometric Analysis of the Plunge Centreless Grinding Process
Authors: Udupa N G Subramanya , Shunmugam M S , Radhakrishnan V 
Published: February 2007

The grinding action and the rounding mechanism are highly complex in centreless grinding. The axis of the workpiece not only moves laterally but also tilts during the grinding process. Rowe and Barash have developed a two-dimensional model for an infeed centreless grinding neglecting the tilt of the workpiece. In this paper, an attempt has been made to develop a simulation model which incorporates the tilt of the workpiece. The theoretical and experimental investigations have been carried out with workpieces having specific geometries and the results are discussed.
Natural-Convective Heat Exchanger with Vertical Rectangular Fins and Base: Design Criteria
Authors: Leung C W , Probert S D 
Published: February 2007

Steady state rates of free-convective, conductive and radiative heat transfer from a polished, duralumin and extended-plate, heat exchanger through air have been measured. When its vertical base was maintained at 40.0 (±0.2) K above the local air temperature (=15.5 ± 0.4°C) in the laboratory, optimal values of the vertical-fin array's geometrical parameters, corresponding to achieving maximum rates of heat loss, were deduced. For a base of width 190 mm and length 250 mm, the optimal uniform separation between 3 mm thick fins rose from 9.5 to 11.1 mm as the fin protrusion was decreased from 90 to 30 mm: it was almost independent of temperature within the range considered. For a base of width 190 mm and length 500 mm, the optimal uniform thickness for fins of 60 mm protrusion rose from 1.5 to 3.6 mm as the fin separation was increased from 15 to 55 mm, the optimal fin thickness being almost invariant with respect to changes in the fins' base temperature. No generalized quantitative recommendations emerge from the present investigation with respect to the optimal values for the fins' length or fins' protrusion. These would have to be evaluated, by making additional due allowances for the weight and cost of material involved in each proposed heat exchanger, according to each particular application envisaged. Nevertheless, it can be concluded that the use of two separated heat exchangers of the considered type, rather than a single one of similar design but whose length is the sum of the lengths of the previous two, should be considered when attempting to enhance the heat-transfer performance.
Alleviating Thermal Resistances of Thermally Distorted Pressed Contacts
Authors: O'Callaghan P W , Probert S D 
Published: February 2007

A suite of interactive computer codes, described previously, for simulating the heat-transfer behaviours of pressed contacts between dissimilar materials has been used to examine how thermal contact resistances may be minimized by: (a) optimizing the roughnesses of the contacting faces, (b) introducing appropriate interfacial fillers, (c) suitably pre-machining (under isothermal room-temperature conditions) the surfaces which will subsequently be pressed together. It has been shown that an inexpensive means of eliminating the component of the macroscopic constrictional resistance, which would arise from thermal distortions of the contacting materials in the presence of a temperature gradient, can be achieved by selecting optimal surface roughnesses.
The Quantification and Reduction of Piston Slap Noise
Authors: Richmond J W , Parker D A 
Published: February 2007

Recent advances by engine and vehicle manufacturers in the reduction of overall noise levels have resulted in piston slap noise becoming more intrusive and its reduction increasingly important. At AE an essential part of a larger programme aimed at achieving this objective has been to develop a technique to assess piston noise in gasoline engines. The paper describes this technique and its application to investigate the effect of piston clearance and bore ovality. The technique may be applied to engines in development without recourse to internal instrumentation and correlates well with the result of listening panels.
The Integration of Noise Control in Plant Design—A Review
Authors: Lyle C D 
Published: February 2007

Adequate control of industrial noise is essential to ensure that local residents are not subjected to nuisance and that people on site are not exposed to noise levels which cause hearing impairment. Noise control engineering should be an integral part of the design process. This paper explains what noise limits must be met and how the noise control requirements should be incorporated in the project. It is shown how noise control interacts with other engineering disciplines to achieve the optimum cost effective design. This is contrasted with the situations which could arise if noise control were considered an add-on feature which is included after the overall design has been completed, or, worse still, after commissioning. It is concluded that involving a noise control engineer from the early planning of a project, through the design stage and ultimately carrying out a post-commissioning noise survey, ensures that noise control engineering expertise is used effectively, technical feedback is maximized and the right standard of noise control is achieved at minimum cost.
Non-Metallic Asbestos-Free Gaskets
Authors: Childs P 
Published: February 2007

With the increasing concern over asbestos, more companies are considering the possibility of changing to asbestos-free, non-metallic gaskets. However, caution should be exercised when adopting alternative materials because their applicational requirements are significantly different. Specifically, when compared with premium quality compressed asbestos fibre grades, the calendered asbestos-free grades generally have: lower temperature and pressure ratings, temperature and pressure ratings which do not co-exist (that is as the temperature increases, the maximum internal pressure sealable decreases), higher minimum surface stress requirements, lower maximum surface stress values, lower creep resistance, different chemical resistance, poorer performance in steam and less tolerance to the deleterious effects of jointing compounds. This paper attempts to demonstrate why this new group of materials should not be considered as a direct replacement for compressed asbestos fibre but rather as a limited substitute. It also offers some hope for the future with the prediction of the development of a calendered asbestos-free grade with similar properties to the best traditional asbestos-based grades but without the large cost penalty involved in selecting exfoliated graphite.
A Review of the Development of Safety and Relief Valve Silencers for Steam Discharge
Authors: Crawford C J 
Published: February 2007

The paper outlines the progress made by the Central Electricity Generating Board (CEGB) in the development of silencers for the control of boiler safety valve and relief valve noise. System noise sources and the formulation of environmental noise criteria are discussed; the silencer design philosophy adopted by the CEGB is described and the progressive improvements are charted to demonstrate the advances made over earlier practices. The results of this work are design concepts which provide silencers which are suitable for application to any of the CEGB's steam valve vent systems and are capable of meeting stringent neighbourhood noise criteria.
Estimating the Performance of Gas Turbine Heat-Recovery Boilers Off-Design
Authors: Weir C D 
Published: February 2007

In installations where a gas turbine is coupled to a steam prime mover through an exhaust heat steam generator, the need may arise to estimate the behaviour of the latter away from its specified design conditions. For example, the performance of the steam generator when the gas turbine is operating away from its design conditions may be of fundamental importance in relation to the economics of a proposed coupled installation. In particular, it determines inter alia the extent to which supplementary firing may be required. A question closely related to that of the off-design performance of a given exhaust heat steam generator is that of evaluating the comparative merits as regards thermal performance of designs differing in the layout and configuration of the heat-transfer surfaces when tendered for the same specified duty. (The need for such assessments frequently arises in the examination of competitive tenders.) The paper discusses briefly procedures allowing the influences of the interrelated heat balances of the heat-transfer surfaces, of the heat-transfer surface geometry and of the steam and gas physical properties to be analysed separately and integrated into a computational procedure permitting their combined effect on performance to be determined with sufficient accuracy.
Prediction of the System Efficiency of Balanced Automatic Transfer Lines
Authors: Ma X , Kochhar A K 
Published: February 2007

This paper presents a simulation study of the system efficiency, in terms of production rate, of automatic transfer lines. A particular type of system, referred to as balanced automatic transfer lines, is considered in the study. In such a balanced automatic transfer line, the stations are considered identical in terms of availability and the buffers are uniformly allocated, and only four system design parameters are involved, namely the number of stations, the identical failure and repair rates, and the uniform buffer capacity. Based upon simulation results, an empirical production rate equation is established by using available optimization techniques for fitting non-linear functions. The empirical relationship is validated using further experimental results. It is shown that this empirical equation can be simply used, with a high enough accuracy in many practical applications, to predict production rates of balanced automatic transfer lines with reasonably wide ranges of system design parameters.
The Management of Product Quality: A Study
Authors: Duncalf A J , Dale B G 
Published: February 2007

This paper reports on an investigation based on manufacturing companies in the United Kingdom. The investigation examined various ways in which companies manage their product quality. In carrying out the study three different pieces of work have been undertaken: namely, case studies, two separate postal questionnaire surveys, and the development and testing of a method for helping organizations to focus on their quality-related decisions. The method developed enables an organization to identify the strengths and weaknesses of their approach to quality management. The findings reveal the many different opinions, structures and functions relative to the approaches of manufacturing companies to quality management. Due to the multitude of factors which influence the way a company goes about managing the task it was impossible to identify a general approach. It was, however, possible to evolve a method based on a quality-related decision-making approach, which provides a means for manufacturing companies to assess their ongoing management of quality and relate this to their specific needs.
The Effect of Billet Location on Completely Closed Cavity Die Forging
Authors: Ibhadode A O A , Dean T A 
Published: February 2007

The effect of the accuracy of location of cylindrical billets in completely closed cavity dies, on forging loads and product accuracy has been investigated. Aluminium billets with various off-centre locations were forged at room temperature on a 3000 kN hydraulic testing machine. The results indicate that inaccuracies in billet location significantly affect forging load requirements and dimensional accuracy of forgings. An energy method solution is presented to provide accurate load predictions for relatively small off-centre locations of billets.
A Thermodynamic Design Simulation for Stirling Cycle Machines Using a Lagrangian Formulation
Authors: Rix D H 
Published: February 2007

This paper describes a one-dimensional simulation of the Stirling cycle machine. A Lagrangian coordinate system is used in conjunction with an implicit solution scheme. The detailed formulation of the conservation equations is set out, including the heat transfer and fluid friction correlations used. The regenerator model includes the use of a spline function to represent the axial temperature distribution. The means of increasing the rate at which the solution attains its final steady state value is outlined. The choice of working fluid subdivision size and number is investigated along with the equation integration time increment. It is shown that optimum values exist for both. Finally, a favourable comparison is made of predicted and experimental results for the pressure-time variations and heat transfers to and from the compression and expansion spaces of a heat pump. The problems of using air as the working fluid are discussed.
History Dependence in Two-Disc Scuffing Tests
Authors: Williams P A , Finnis M P , Kelly D A 
Published: February 2007

Salient features are described of a two-disc machine and its use to monitor friction, resistance drop count rate, surface roughness and disc bulk temperature in scuffing tests on mineral oil lubricated, case-hardened En 36A steel. Tests with two different load sequences and three oil supply temperatures are reported. Results for two extreme-pressure-additive oils are compared with earlier results for a non-additive oil and shown to support the validity of a recent hypothetical model by Baglin for the onset of microelastohydrodynamic lubrication. Compared to the non-additive oil, the additive oils gave higher disc bulk temperature rises, greater running-in and more severe conditions at scuffing when tested at sliding and rolling speeds of 6 m/s. Nevertheless, these scuffing conditions were not so severe as those for the non-additive oil tested at a sliding speed of 3 m/s and a rolling speed of 4.5 m/s.
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.
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.
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.
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.
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.
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.
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.