bluuebunny/crossref_metadata_2025_split huggingface dataset:
Surface Effects on Alloys Drilled by Electrochemical are Machining
Authors: de Silva A , McGeough J A 
Published: February 2007

Electrochemical arc machining (ECAM) utilizes pulsed power in an electrolyte, in order to remove metal by combined electro-discharge erosion (EDE) and electrochemical dissolution (ECD). In drilling by this technique, EDE occurs at the frontal gap between the cathode-tool and anode-workpiece; in the side gap, ECD is predominant. Machining rates are much greater than those of electrochemical (ECM) and electro-discharge machining (EDM). This paper is concerned with an investigation of the effects of EDE and ECD on the surface integrity of a range of alloys of industrial interest, drilled by ECAM. Chrome, cobalt and low-alloy steels and nickel-based (nimonic) alloys all exhibited a smooth surface finish typical of that found with ECM, for most of the length of the drilled hole, except at the exit. There, metallurgical damage due to EDE was apparent. The surface characteristics with titanium were typical of those found in EDM, with virtually no evidence of ECM action. This effect was attributed to the presence of a tenacious oxide film formed on titanium in water-based electrolytes which effectively blocks ECM.
A Semi-Analytical Finite Element Method for Three-Dimensional Contact Problems with Axisymmetric Geometry
Authors: Park S G , Kwak B M 
Published: February 2007

A combination of conventional two-dimensional finite elements and a Fourier series expansion in the tangential direction is shown to be efficient for modelling an elastic three-dimensional frictionless contact problem of geometrically axisymmetric bodies under non-axisymmetric external loads. For the solution procedure, the governing partial differential equations and contact conditions on the contact surface are formulated into an equivalent minimization problem with constraints. It is shown that the resulting objective function can be expressed as the sum of decoupled contributions from each harmonic. A modified simplex method is used to solve this quadratic programming problem. An example problem, motivated from a modular prosthesis design for artificial joint replacements, has shown the significant computational efficiency of this approach as compared to a conventional full three-dimensional finite element method.
Plastic Envelopes and their Problems for the Postal Service
Authors: Barton P H 
Published: February 2007

Envelopes manufactured from plastic films offer many advantages to mailers in terms of security, marketability and most importantly a potential to reduce enveloping costs when compared to traditional paper envelopes. The British Post Office currently prohibits plastic envelopes which are of a size and class that would normally be machine coded and sorted because the physical properties of typical plastics give rise to mechanical transport and code mark printing problems. This paper describes a research programme to allow the introduction of plastic envelopes. Important aspects of the research include the development of an automatic plastic/paper discriminator and the quantification of the physical properties of an envelope suitable for current code-sort equipment. Modifications to existing equipment to suit common plastic films are discussed together with the development of new plastic films which are both acceptable to the British Post Office for mechanized sorting and acceptable to mailers in terms of cost and other qualities.
Elastic Buckling of Internally Pressurized Cylinder—Bulkhead Combinations
Authors: Galletly G D , Blachut J 
Published: February 2007

The shell structures considered in this note are unstiffened spherical caps attached to unstiffened cylindrical shells by means of circumferential stiffening rings. The loading is uniform internal pressure and the object of the analysis is to determine if elastic bifurcation buckling can occur and, if so, where the buckles will be located. The BOSOR 5 shell buckling program was used in the analysis and several stiffener geometries were investigated. The present results show that elastic buckling can occur in the cylindrical portion of some cylinder—bulkhead combinations. If the structure is subjected to repeated loading, then the formation and disappearance of the elastic buckles could contribute to the initiation of fatigue cracks. Designers should, therefore, be aware of this possible elastic buckling mode. As some of the geometries investigated in the present note are not unlike some commercial aircraft configurations, the present results may be relevant to them also (even though those structures are stiffened).
Buckling of Shallow Dished Ends under External Pressure—a Caveat
Authors: Galletly G D 
Published: February 2007

The application of BS 5500 to the design of some shallow steel torispheres subjected to external pressure can result in safety factors which are lower than the expected 1.5. Some examples in which this occurs with elastic, perfectly plastic steels having yield points in the range 150 N/mm2 < σyp < 400 N/mm2 are given in the present note. Results are also given which show how the collapse pressures increase when linear strain hardening is included in the analysis. For shallow aluminium torispheres, the Code rules seem safe but, since elastic buckling of the imperfect spherical cap may often be the controlling failure mode, the designs can be rather inefficient in the use of material. Experiments on externally pressurized shallow torispheres having relatively low yield points are desirable in order to develop satisfactory buckling design rules for both the knuckle and the spherical cap regions of these dished ends.
Implementation of a Cavitation Algorithm into a Procedure for the Prediction of Non-Newtonian Flow in Hydrodynamic Journal Bearings
Authors: Williams P D , Symmons G R 
Published: February 2007

A procedure for solving the Navier–Stokes equations for the steady, three-dimensional, cavitated flow of non-Newtonian liquids within finite-breadth journal bearings is described. The method uses a finite difference approach, together with a technique known as SIMPLE (Semi-Implicit Method for Pressure-Linked Equations) which has now become well established in the field of computational fluid dynamics. The concept of ‘effective viscosity’ to describe the non-linear dependence of shear stress on shear rate is used to predict the performance of bearings having a single axial inlet groove situated at the position of maximum clearance between the shaft and housing. The implementation of a cavitation algorithm into the equation set allows the loci of film rupture and reformation in the vicinity of the supply groove and elsewhere to be traced, these having a particularly important influence on the predicted lubricant flowrate. Results are obtained for a range of non-linearity factors and lead to the conclusion that all the important indicators of bearing performance can be determined using the technique described.
London Underground Prototype Tube Trains
Authors: Aylward R W , Minter R H 
Published: February 2007

As part of the overall programme for the renewal of the Central Line, London Underground is purchasing three prototype trains. These trains incorporate many new features and will form the basis for the next generation of tube rolling stock. The trains are being bought on a main contractor basis and a complete specification was produced. The trains were ordered in May 1984 and are due for delivery this year. The major technical innovations of the trains are the use of large aluminium extrusions, solid state traction control, and materials with an improved fire performance.
Power Transmission Losses in V-Belt Drives Part 1: Mismatched Belt and Pulley Groove Wedge Angle Effects
Authors: Childs T H C , Cowbum D 
Published: February 2007

AV 10 raw-edged V-belts cut to wedge angles from 32° to 42° have been run in 36° grooves on pulleys of 51 mm pitch circle radius. It has been shown experimentally that belts with wedge angles from 37° to 38.5° fitted the grooves best and were the most efficient. The excess speed and torque loss parts of the power loss of other belts was due to the larger radial compliance of these belts which did not fit their pulley groove. Current theoretical models of radial compliance of misfitting belts are shown to be wrong. The results have been generalized and a theory of belt bending distortion developed to give detailed recommendations of the most efficient pulley groove angles in which to run belts cut to 40°, depending on pulley radius, belt construction and belt length.
British Rail Diesel Multiple Unit Replacement Programme
Authors: Shore A G L , Shore A G L 
Published: February 2007

During the 1980s British Rail has been addressing itself to the problem of replacing its diesel multiple unit fleet. Initially two approaches of lightweight railbus and full weight diesel-electric multiple unit were tried and subsequently medium weight diesel-mechanical prototypes were evaluated. The paper sets out the principal factors affecting the specification of each of the prototype units, the service experience gained with each type and the system studies and cost evaluations which were carried out. All of this has taken place against a background of a constantly changing business requirement for the size of fleet, the duty and the sector of the market for which the units are intended. The paper shows how these changed requirements have influenced, and are continuing to influence, the specification of the production fleet which is currently based on a mixture of medium and lightweight units.
Compressible and Leaky Trains in Tunnels
Authors: Vardy A E , Fox J A 
Published: February 2007

It is hypothesized that phase differences commonly observed between computed and measured pressure histories in railway tunnels may be caused in part by reduced acoustic wave speeds in the annular regions of flow alongside trains. Such reductions in wave speed are shown to be a possible consequence of the compressibility of trains and/or the leakage of air into and out of trains. These effects are shown to be capable in principle of reducing the effective wave speed by a factor of (1-β)1/2 where β denotes the train-tunnel area blockage ratio. The potential influence of reduced wave speeds due to these causes is shown to be much greater in short tunnels than in long tunnels. An alternative explanation for the discrepancies observed in long tunnels has yet to be found.
Fire Protection on Trains
Authors: Dee A W 
Published: February 2007

The hazards from fire in a moving vehicle are similar to the hazards from fire in a building and so similar steps must be taken to detect the presence of fire, to prevent it spreading and to extinguish it in this special circumstance. This paper describes the diferent methods that can be used to provide an effective fire protection system from trains. The various system requirements are set out and a selection is made of the type of system required and the equipment needed to perform each task. Each element of the system, consisting of detection, control and monitoring and extinguishment, is dealt with separately and its advantages and disadvantages are given. Finally, an assessment is made of the applications of the system, and reliability, testing, maintenance and safety features are discussed.
Internal and Atmospheric Leakage Assessment and Intergate Overpressurization of Isolation Valves
Authors: Airey D R , Lung F K K , Metcalf M J , Salter S 
Published: February 2007

Some problem areas which would lead to internal and atmospheric leakage in valves, specifically for pressurized water reactors, are identified. Frequent thermal transients can induce thermal stresses and promote the propagation of surface faults into the valve body and cause eventual cracking of the seat. Trapping of hard debris around the seat causes seat and disc damage as well as providing leak paths. Cavitation can also produce seat and disc damage, particularly in high-speed flows. Atmospheric leakage is caused mainly by the deficiencies in gland packings and by overpressurization problems in valves. In the case of bellows and diaphragm sealed valves, metal fatigue, stress corrosion cracking and punctures are the usual cause. The overpressurization problem in valves can increase the rate of gland deterioration. The problem is discussed in some detail in this paper. Analysis of theoretical gland packing results suggest that stem friction reduction and discarding lantern rings in stuffing boxes can improve the sealing performance of the packings. Ideally the sealing material should have a low coefficient of friction and a high Poisson ratio.
Computational Method to Assess Concentration of Water in Crude Oil Downstream of a Mixing Section
Authors: Baker Roger C 
Published: February 2007

This paper describes a method for predicting the concentration distribution of water in crude oil in a pipe section downstream of a region of mixing and droplet break-up. The complexity of the problem and the necessary simplifications are described. The method with its approximations is justified on grounds of possible savings in financial outlay. Details of governing equations, computational method and boundary conditions lead on to the link between forces on the droplet and the velocity of the droplet relative to the bulk liquid. The model incorporates turbulence enhancement and decay, and secondary velocities likely to approximate to those following a T-piece or bend or swirl-creating element. The computer program was tested against data provided by BP and the results suggest that if the predictions indicate adequate mixing then they are likely to underestimate the uniformity of the mixture. The predictions may be used to assess the suitability for sampling based on Case 1 of the draft ISO Standard (1) but must not be used to assess the suitability for sampling based on Case 2 of the draft standard unless fall-out has been allowed for in the program. The paper reviews the assumptions and approximations involved in this model. Further work in these areas is needed to allow the model to be used with greater confidence.
A Model for Combustion Losses in a Pulverized Fuel Fired Power Plant Boiler
Authors: Krishna V , Sharma P B 
Published: February 2007

A model for the estimation of combustion losses in a pulverized fuel power plant boiler is presented. The model is based on the formulation of a probability density function which relates the probability of a fuel particle remaining unburnt to the combustion and resident times. An empirical model is also presented which relates the unburnt carbon loss to average particle size and excess air. The two models are shown to be in close agreement with each other. The models are validated from the experiments on a power plant boiler. The dependence of boiler efficiency on particle size and excess air is also examined and an empirical correlation between optimum excess air and particle size is derived. The mechanism of two-way coupling between boiler and turbine side parameters is also illustrated. It has been shown that the optimum excess air levels for maxima in plant heat rate and boiler efficiency are not the same, since the two-way coupling influences both the turbine heat rate and boiler efficiency. The effect of two-way coupling has been found to be more predominant for particle sizes of the order of 200 μm.
Knowledge Representation Database for the Development of a Fixture Design Expert System
Authors: Darvishi A R , Gill K F 
Published: February 2007

To meet the demands of the flexible manufacturing system, an exploratory approach to the design of fixtures using an expert system is presented. A small part of the range of knowledge existing is utilized to create a database framework that can be used to develop a computerized approach to fixture design. The method allows for an expansion to a relatively large database that, when established, would encompass all of the important practical aspects of fixture design.
Theoretical Road Damage Due to Dynamic Tyre Forces of Heavy Vehicles Part 2: Simulated Damage Caused by a Tandem-Axle Vehicle
Authors: Cebon D 
Published: February 2007

The literature relating to road surface failure and design is briefly reviewed and the conventional methods for assessing the road damaging effects of dynamic tyre forces are examined. A new time domain technique for analysing dynamic tyre forces and four associated road damage criteria are presented. The tyre force criteria are used to examine the road damaging characteristics of a simple tandem-axle vehicle model for a range of speed and road roughness conditions. It is concluded that for the proposed criteria, the theoretical service life of road surfaces that are prone to fatigue failure may be reduced significantly by the dynamic component of wheel forces. The damage done to approximately five per cent of the road surface area during the passage of a theoretical model vehicle at typical highway speeds may be increased by as much as four times.
The Design and Initial Testing of a Prototype Stirling Cycle Heat Pump
Authors: Rix D H 
Published: February 2007

This paper covers the first step of an investigation into the potential of the Stirling cycle heat pump. The design and construction of a prototype is described. Particular reference is made to the use of a previously developed theoretical model in the design optimization of the heat exchangers and regenerator. The resultant machine has been tested over a wide range of heat delivery temperatures and temperature lifts, using a pair of hot oil circuits to exchange heat with. Though these initial tests have revealed two design flaws, which have seriously reduced the values attained for the coefficient of performance, they have demonstrated the ability of the Stirling cycle heat pump to deliver heat at higher temperatures and over larger temperature lifts than established types of heat pump.
The Changing Research and Development Role in the Mobility Industry from a Supplier's Point of View
Authors: Coleman W S 
Published: February 2007

Many changes are occurring in the transportation equipment industry and some changes are being made at an accelerating rate. Global competition has spawned mergers, acquisitions, joint ventures and ‘partnerships’ which are changing the traditional roles played by vehicle builders and their component and material suppliers. In some cases the OEMs are moving toward more reliance on ‘full service’ suppliers who can provide ‘cradle to grave’ support. This implies that a longer-term relationship must be established (and earlier) in the new product development cycles with a clearer under standing of the business needs of both parties. Product R and D and planning must be brought together with both suppliers and the OEMs participating in development programmes that will result in shorter response times, less ‘total’ programme and product costs, and much better downstream quality.
Optimizing Proportions of Railway Brake Discs by Temperature Transients Evaluation
Authors: Missori S , Sili A 
Published: February 2007

When evaluating the performances of railway brake discs, the ability to accumulate and spread heat to the air plays a major role, since wear of synthetic lining and disc deterioration are strongly dependent on maximum temperatures attained on the surface in contact with the friction pad. The energy developed during brake application gives rise to an increase of disc temperature, which can be correlated to braking power, braking sequences and durations and to disc features. Maximum temperatures are attained on the friction surface of the disc. Determination of the thermal cycle subsequent to brake application can be considered preliminary to the study of lining and disc wear. The present work proposes a simple method using finite difference numerical analysis to evaluate the efficiency of the brake disc in dissipating the heat, both on a constant speed and an up-to-stop brake application. The effect of the various dimensional parameters, such as number of ribs, disc thickness and ribs width, is considered with the aim of achieving a first rough optimization of the required size of disc brake. The results related to a commercial size disc brake are given.
Impact and Movement of Pedestrians in Frontal Collisions with Vehicles
Authors: Wood D P 
Published: February 2007

The movement of pedestrians after frontal impact with vehicles and the inter-relationship between pedestrian throw distance and the pre-impact velocity of the vehicle is of interest in accident reconstruction. This paper derives a single-segment rigid-body model for the primary and secondary impacts between the pedestrian and the vehicle. Published data on staged collisions involving horizontal flight are used to derive pedestrian-ground friction coefficients and show that the friction coefficient decreases with increasing speed. The analysis shows that for horizontal flight the throw distances of adults and children are similar. For impacts with cars the model for primary and secondary impact yields calculated throw distances that closely match published results for staged collisions between cars and dummies and cadavers.
Switch-On Delays in Multiplexed Automotive Brake Lamps
Authors: Greaves A , Hampshire M J 
Published: February 2007

The purpose of this report is to outline some of the facts associated with automotive brake lamps so that a well-informed decision may be taken as to whether or not they are suitable for inclusion in a multiplex system. For background data, driver reaction time is defined and quantified at around 700 ms, with individuals tested falling in the range 280 ms-2 s. The rate at which a hard-wired brake lamp bulb increases its luminance is then examined; this is found to depend largely upon the impedance of the wiring that connects the bulb to the battery. A minimum level of intensity that the bulb must reach is decided upon (297 lm), and it is found that the hard-wired bulb takes between 105 ms (Rline=250 mΩ) and 135 ms (Rline=500 mΩ) to reach this level. A similar experiment carried out using the bulb driven by a multiplex system found it now took between 108 and 120 ms to reach the same level. The conclusion is that for the system tested there can be no justification for not multiplexing the brake lamp circuit on the grounds of system latency.
High-Cycle Fatigue of Shafts due to Starting Transients in Drive Systems
Authors: Velonias S G , Aspragathos N A 
Published: February 2007

This paper investigates some of the effects that structural characteristics and main non-linearities of a drive system have on systems response and its shaft fatigue. In the suggested approach a general drive system, including a motor, load and speed reducers, is modelled as a multi-degree-of-freedom torsional vibrations non-linear system. The differential equations of the system are formed automatically. The user of the developed program must input just the constants of the components. An algorithm to compute the loss of life of the shafts due to fatigue is also incorporated into the program. As an example, a drive system, including a motor, a speed reducer and load is modelled and tested under starting conditions. The effects of changing spring constants of the shafts and the backlash of the speed reducer are investigated.