bluuebunny/crossref_metadata_2025_split huggingface dataset:
Technical Considerations for Catalysts for the European Market
Authors: Gandhi H S 
Published: February 2007

The durability of automotive catalysts for European applications were investigated as a function of higher temperatures encountered in autobahn driving over extended periods of time, potentially higher lead levels anticipated in the beginning in European unleaded fuels and occasional misfuelling with leaded fuels. Increasing residual lead levels from 3 mg Pb/L to 10 mg Pb/L in laboratory experiments at 1000°C peak temperature substantially decreased three-way catalyst (TWC) performance. Higher temperature ageing conditions from 730 to 1000°C resulted in 50 per cent loss of BET area and increased stoichiometric light-off temperatures. The paper also reviews briefly the role of noble metals, rare earth oxides and base metal oxides in the formulation of practical TWCs. The operation of a TWC and the effects of A/F modulation frequency and amplitude on its performance are also discussed. Important thermal and chemical modes of TWC deactivation are discussed with specific examples. The importance of matching the active metal component to the support material to achieve the desired metal-support interactions and how this understanding has led to the development of practical TWC with proper utilization of noble metals is emphasized. Finally, the lean-burn versus stoichiometric combustion approach as it relates to catalyst requirements is also discussed.
Friction in Femoral Prosthesis and Photoelastic Model Cone Taper Joints
Authors: Fessler H , Fricker† D C 
Published: February 2007

Static axial push-on and lift-off, and push-on and twist-off experiments were designed and performed to measure the effective, room-temperature coefficient of friction μ for different design femoral prosthesis cone taper joints comprising a universal head on a stem spigot. Alumina and metal heads were tested on metal spigots using either distilled water, Ringer's solution, blood or no lubricant. Complementary push-on and lift-off friction tests of Araldite model joints for subsequent frozen-stress, photoelastic stress analysis were performed at 130°C. It was found that lubricant caused little decrease in the values of the coeficient of friction in prosthesis tapers. The values measured were typically μ =0.2 for an alumina head on a Co-Cr-Mo or Ti-6Al-4V spigot, μ = 0.15 for a Co-Cr-Mo head on a Co-Cr-Mo or Ti-6Al-4V spigot and μ =0.13 for a stainless steel head on a stainless steel spigot. For Araldite photoelastic models of an alumina head on a Vitallium spigot, as-cast taper surfaces lubricated with silicone grease gave consistent friction of typically μ = 0.14. The axial displacements of model heads on their spigots were compared with predicted values and previously measured values for prosthesis heads.
A Study of Stresses in Alumina Universal Heads of Femoral Prostheses
Authors: Fessler H , Fricker† D C 
Published: February 2007

Three-dimensional, frozen-stress photoelasticity was used to study the best shape for a proposed alumina universal head loaded on to a Vitallium cone taper spigot with a 30° inclined force, as in vivo. Typical cone taper friction values were reproduced in the photoelastic models. The location of the highest tensile stresses in the Mark I shape with a flat crown was found to be on the inner surface of the crown. Changing to a torispherical surface in the Mark II shape reduced this magnitude. However, the Mark III shape with a hemispherical inner crown surface gave even lower stress there, equal to the maximum value of the hoop stress at the taper, which was measured to be fairly uniform both around and along the taper except at the ends where contact pressure concentrations were found to occur and it became reduced. Lamé axisymmetric cylinder stress predictions were found to be useful approximations to measured values and were generally overestimates of the tensile hoop stress at the head taper surface.
Electricity—Some Views on the Selection of Plant for the Next Generation of Power Stations
Authors: Masding H 
Published: February 2007

This paper reviews some of the factors influencing the selection of thermal generating plant for installation in the next generation of power stations in England and Wales. The effect of the variations in the demand for electricity throughout the day and the seasons is considered in brief outline and it is concluded that the power system will be best served by the installation of large high-efficiency plant to cover the base load on the system supplemented by smaller, cheaper flexible plant for part load and two shift operation. After a brief introduction the paper is set out under the following headings: Consumers' needs and the existing system Load growth and plant replacement General considerations Machine design and commercial strategy Concluding remarks The views expressed in this paper are the personal views of the author and are not influenced by any organization. Some of the current proposals are disputed and the object is to promote further discussion in order to lead to the unqualified establishment of the best policy for both the utility and the power plant industries for application at home and overseas.
Co-Generation Energy Centres in Diverse Production Facilities
Authors: Phillips A L , Pearson A 
Published: February 2007

This paper gives a review of applications within the Unilever Group, including plants in operation and studies that did not result in implementation, discusses the development of Unilever's Mersey side site and gives a review of Unilever's recently completed remodelling of the Merseyside Power Station, Port Sunlight, including the financial case, how it is put into practice and operating experience. The oil-fired high-pressure boilers/backpressure steam turbines station now incorporates a 105 tonne/h, 103 bar, 510°C, spreader stoker coal-fired boiler and a 9.5 MWe heavy fuel oil-burning medium-speed diesel engine. Both operate on ‘base load’. The station is flexibly integrated by means of feedwater and air heating systems.
The Differentiation of Loose and Secure Femoral Implants in Total Hip Replacement Using a Vibrational Technique: An Anatomical and Pilot Clinical Study
Authors: Rosenstein A D , McCoy G F , Bulstrode C J , McLardy-Smith P D , Cunningham J L , Turner-Smith A R 
Published: February 2007

Anatomical study: The common pathway to failure in total hip replacements is loosening of the acetabular and femoral components. The reliable diagnosis of this loosening is difficult. A non-invasive technique has been developed which analyses a vibration signal transmitted through the femur. This can distinguish between a femoral component which is loose and one which is firmly fixed. Charnley femoral components were cemented securely into ten cadaver femurs and the transmitted vibration signal recorded. The prostheses were then loosened first at the cement-prosthesis and then at the cement-bone interface. The tests were then repeated. Consistent and distinct differences between output vibration signals were observed between the firmly implanted and the loose prostheses. Pilot clinical study: Seven patients admitted for recision surgery because of clinical and radiological evidence of femoral implant loosening were tested using this technique. A further four patients with secure femoral components were tested approximately two weeks after total hip replacement. The differences in output signal, which had been observed between firmly implanted and loose prostheses during the anatomical study, were again demonstrated.
Fan Blade Selection for Low Noise Part 1: Design Philosophy
Authors: Hay N , Mather J S B , Metcalfe R 
Published: February 2007

It has been known for many years that the broadband noise of rotating machinery is dependent on the condition of the boundary layers on the lifting surfaces. Designs with high efficiencies and clean flow have mainly produced low noise levels. These units have generally used high technology blading, with low inlet velocities and minimal separated flow. In the application of machines in industry, however, many are subject to inlet flow distortion and turbulence. These produce changes to the flow pattern around the blades which may have a relatively insignificant effect on the aerodynamics of the machine but almost completely destroy its acoustic performance. The design method described by Hay, Metcalfe and Reizes (15) allows the designer to pitch the operating point well away from stall. Thus low-response blading can be used for those installations whose flow conditions cannot be improved. This method is further developed in this paper using some correlations from McKenzie's work (17). The application of the method to the design of a low noise fan in the presence of a ±10 per cent perturbation on inlet velocity is given in way of illustration of the approach. In Part 2 of this paper (to be published later) it is hoped to demonstrate the validity of the design philosophy presented here with test results from fans designed according to this philosophy.
The Fort Dunlop Combined Heat and Power Plant
Authors: Price M E , Chilton M D 
Published: February 2007

The paper describes the combination of a large medium-speed diesel engine with a conventional chain grate boiler at the Fort Dunlop combined heat and power (CHP) station. The CHP station is situated in Birmingham, England, and is owned and operated by the Midlands Electricity Board (MEB). A detailed description of the plant is given including the combination of both the water and gas systems.
Small Arms Manufacturing for the 1990s
Authors: Summerfield P H 
Published: February 2007

When British Aerospace acquired Royal Ordnance in 1987 it was midway through the first phase of a fixed-price contract to supply rifles to the Ministry of Defence (MOD), its single biggest customer, and had a firm option on the second phase. However, there was a significant problem in that each new British Army rifle was incurring a 30 per cent loss and deliveries were 18 months behind programme. The new management team had two months to decide whether to accept the option or pull out. After that the MOD would go to competitive tender. The decision was a fundamental one for Royal Ordnance. To pull out of the contract would mean in effect surrendering the rifle business to competitors, but if the contract was accepted it was clear that radical changes would be required to cut costs and reverse the losses. The management team chose to stay in the market and fight. The events that followed, which are described in this paper, illustrate the step function in change that successful companies are having to make to stay ahead of the competition.
Split Torque Helicopter Transmissions with Widely Separated Engines
Authors: White G 
Published: February 2007

A three-stage helicopter transmission of split torque type is shown to offer advances in a configuration that allows the engine axes to be widely separated and parallel. Three variants of the configuration are examined; one design with separated drive paths and four final-drive pinions is discussed in detail. This design offers 26 per cent less weight and 9 per cent lower losses than current production transmissions. Comparison is made with epicyclic type transmissions of similar rating that have been developed in the past decade.
An Approach to the Low-Cost Computer Aided Manufacture of Components Embodying Free-Form Surfaces
Authors: Gao X , Harrison D K , Davies B J 
Published: February 2007

The numerical control (NC) machining of free-form surfaces is usually accomplished utilizing minicomputer or mainframe computer aided design and manufacturing (C ADC AM) systems. The resulting NC data are suitable for either three-axis or five-axis machining dependent upon machine tool type/capability and CAM package complexity. However, the cost of such packages and systems precludes the use of these in smaller companies with an occasional requirement for components embodying free-form surfaces. The increasing availability of powerful yet reasonably priced personal computers (PC) coupled with improving software provides such companies with a far cheaper alternative approach. However, a common feature of PC-based CADCAM systems is that they are limited to 2 1/2-axis machining for all but special applications such as three-axis canted Z-plane milling of four-axis wire electro discharge machining (EDM). This paper presents a method for manufacturing true three-dimensional free-form surfaces using PC-based 2 1/2-axis CADCAM systems. All the main functions performed on mainframe systems can be performed on personal computers, such as toolpath generation for free-form surfaces, cusp height determination and change in shape and volume which may be used for the compensation of shrinkage or to suit market requirements. This is significant for manufacturers who make use of moulds, such as are found in the plastic processing industries. The manufacture of a blown plastic bottle mould is presented as a typical example. The inclusion into the PC environment of features to be found in mainframe systems is also discussed, such as machining the surface patch by patch in any direction or machining a number of patches at one time, shape and volume change in any direction, cusp height determination, etc.
Helicopter Transmissions—design for Safety and Reliability
Authors: Astridge D G 
Published: February 2007

Recent improvements in design and component technologies are reviewed against a background of accident data analysis, resulting in grounds for confidence in higher safety levels in future rotorcraft transmission designs. Recommendations are made concerning the realization of significant safety and reliability benefits afforded by effective health and usage monitoring systems. The results of this study are applicable to all new aerospace gearbox applications including helicopters, tilt-rotor aircraft, advanced propeller engines and accessory drive systems.
Analysis of Displacements and Stresses in Oil Storage Tanks Caused by Differential Settlement
Authors: Kamyab H , Palmer S C 
Published: February 2007

Differential vertical settlement around the circumference of the foundations of large open-topped oil storage tanks can produce deformation of the tank including radial deflection of the tank shell. Excessive radial deflections may result in jamming of the floating roof. The results of an analysis by Malik et al. (1), based on the assumption that the behaviour of the shell is inextensional, are outlined. Two further analyses of the tank shell and the primary wind girder are presented. Both of these are simple, but use less restrictive assumptions than in reference (1). In the first analysis the shell is considered to act as a membrane. The second analysis makes use of a simplified version of the modified Donnell equation. The results of these analyses are compared with those of the analysis based on the inextensional behaviour of the shell. The limits of validity of the three different analyses are identified. It is proposed that the membrane solution is valid for all practical applications, and the results are presented in non-dimensional form in Fig. 6.
On the Deployment of Automotive Engineers
Authors: Bertodo R G 
Published: February 2007

British automotive design philosophies, engineering traditions, organizational structures and managerial practices have been geared to the generally recognizable European product concept. This distinctiveness has been eroding due to the convergence of Japanese and North American trends towards European values. Regaining the competitive edge has become the challenge facing the industry. The present paper describes a determined attempt to do so. Earlier investigations had shown that, in automotive engineering, the attainment of customer-perceived superb ‘quality’ was the only assurance of market acceptability and competitiveness. Traditional design methodologies were demonstrated as inadequate and incapable of ensuring the attainment of product attributes in line with end-user needs and expectations. The subsequent evaluation of an alternative design logic indicated the need for a reappraisal of the engineering culture. The organizational, managerial and operational changes necessary to implement this new philosophy are described in detail. A preliminary quantification of the benefits reaped are presented. Scope for further improvement is shown to exist. Although the transition was broadly successful, different areas showed different rates of progress. This highlighted the need for a commonality of ethos, objectives, goals and understanding by all. Apprehension and discomfort was encountered at all levels, but was particularly evident among middle management. This underlined the importance of mutual trust, good communications and appropriate training. The continuing evolution of the automotive industry and the pressing challenge of competition will force ongoing changes in engineering organizations to meet new market needs. The likely directions of such changes in the management of automotive engineering work are outlined.
The Effect of Vaneless Diffuser Geometry on the Surge Margin of Turbocharger Compressors
Authors: Whitfield A , Sutton A J 
Published: February 2007

A study into the effect of two methods of changing the geometry of a vaneless diffuser on the performance of the compressor of a road haulage diesel engine turbocharger is described. The development of compressor variable geometry will enable the full potential of variable geometry turbines to be realized. This will give a more flexible power unit which will provide, for example, better low-speed torque and hence a smaller gearbox, and shorter journey times or larger payloads than are currently the practice. The disadvantages are added complexity and cost in the relatively simple turbocharger, and the need for an engine management system. The latter is currently being implemented on many vehicles to meet tight emissions regulations in Europe and elsewhere, and is thus not a drawback limited to variable geometry turbocharging. A compressor test facility, including appropriate instrumentation and a computer-based data-acquisition system, was constructed with the specific aim of investigating the unstable flow regime prior to and including surge. Alternative fixed vaneless diffuser geometries were designed to simulate a variable geometry diffuser which could be achieved through a flexing diffuser wall and a sliding throttle ring. Both the converging wall and throttle ring arrangement moved the peak pressure ratio to lower flowrates, and at the near surge flowrates (where the device would be introduced, when operating in a variable geometry mode) improvements in both pressure ratio and efficiency are shown. While the converging wall concept exhibited slightly better aerodynamic performance than the throttle ring, it has implementation difficulties with respect to material integrity under continuous flexing when developed to a fully variable geometry device. The simplicity of the sliding throttle ring makes it a more viable proposition. Prototype variable geometry (VG) devices have been constructed with a view to further rig and engine testing.
Theoretical Analysis of Active Suspension Performance Using a Four-Wheel Vehicle Model
Authors: Hady M B A Abdel , Crolla D A 
Published: February 2007

Techniques for obtaining control laws for an active suspension implemented at all four wheel stations of a vehicle are outlined. It is shown that the classical optimal control law based on full state feedback can be replaced by one that involves limited state feedback—omitting, in particular, the ground input information—and that may involve measurement errors. Performance of this system is almost as good as that of the full state feedback system and is much more attractive in terms of its practical implementation. Previous work, much of which has been based on the quarter car model, is extended so that the performance indices may include body roll, body pitch, seat lateral acceleration and lateral and fore/aft dynamic load transfer.
Design and Testing of a Servo Controller for Pneumatic Cylinders
Authors: Marchant J A , Street M J , Gurney P , Benson J A 
Published: February 2007

A closed-loop method of controlling a pneumatic cylinder is proposed where the cylinder can respond to varying position demands from an external source. The method uses a state space design technique involving the experimental identification of a dynamic model for the cylinder and valve combination. Data for the identification are obtained from an initial phase in which the valve and cylinder are excited by an operator. The controller constants are then derived using a pole placement design technique. The model and control constants are derived within the controller, resulting in automatic tuning. Experimental data are presented in response to step and ramp inputs. With moderate closed-loop bandwidths the response is well damped but as the designed bandwidth increases, lightly damped oscillations occur in the response, probably caused by differences between the responses of the experimental system and its model. If greater closed-loop bandwidths are required further work needs to be done on the form and order of the model.
An Experimental Study of a Plasto-Hydrodynamic Strip Drawing Process
Authors: Memon A H , Symmons G R , Crampton R , Hashmi M S J 
Published: February 2007

Experimental results are presented for a new dieless strip drawing process in which conventional wedge-shaped dies have been replaced by a reduction unit having a stepped rectangular cavity. The smallest cavity dimensions are larger than those of the incoming strip, thus eliminating the problem of die friction and consequential tool wear. In this novel process, the strip is passed through a chamber filled with polymer melt and then pulled through the reduction unit. The strip material is deformed due to the combined effects of shear drag and the hydrodynamic pressure generated by the converging flow of the polymer melt. Experiments were carried out in which the process parameters such as the unit geometry, speed and polymer melt temperature and hence viscosity were varied and the hydrodynamic pressure, reduction in strip size and drawing load were measured. Initial experiments were carried out by using copper strip and low-density polyethylene at two different melt temperatures. Results from experiments showed that a reduction in area of strip of more than 10 per cent could be achieved in a single pass. The Newtonian analysis presented by the authors in reference (9) is modified to incorporate the critical shear stress limit of the polymer melt and the non-linear strain-hardening property of the strip material.