bluuebunny/crossref_metadata_2025 huggingface dataset:
Venturi investigations into cavitation in ethylene glycol/water mixtures
Authors: Gummer J H , Thew M T
Published: October 2002

The objective of the investigation was to study cavity formation with various concentrations of ethylene glycol/water (EG/W) in order to gain an insight into the previously observed anomalous thermal effects in these mixtures. The normal thermal effect is for the apparent cavitation coefficient to decrease with increase in fluid temperature whereas in EG/W mixtures it has been observed to increase. Cavities in a cavitating venturi tube were observed and photographed. The cavity pressure was measured, together with cavity temperatures at various distances along the cavity. The measured temperatures confirmed that the cavity temperature depression, which is responsible for the normal thermal effect, is present in EG/W mixtures and, if this were the only factor, these mixtures should exhibit the same thermal effect as other liquids. However, the cavity pressure measurements showed that a gas (undoubtedly air) was present in the cavity, the proportion of air increasing with the concentration of ethylene glycol (EG). This air is responsible for the reverse thermal effect with EG/W mixtures, a phenomenon previously observed at higher temperatures with water. It is thought that microbubbles of air observed circulating in the rig are responsible for the collected air in the cavity, the persistence of these bubbles increasing with increasing concentration of EG.
Two-phase jet impingement for non-volatile residue removal
Authors: Klausner J F , Mei R , Near S , Stith R
Published: October 2002

A high-speed jet impingement facility, which was developed for non-volatile residue removal from aerospace components in contact with liquid oxygen, has been fabricated and tested. A two-phase mixture, consisting of water droplets suspended in air, expands through a converging—diverging nozzle and the resulting jet impacts the target surface at high speed. The advantage of this facility over conventional high-speed water jets is that the water consumed is extremely low, typically 1.67 × 10−4-16.7 × 10−4kg/s. Thus the disposal of the waste water is greatly simplified. This work explores the performance of the jet impingement facility over a range of operating conditions using different nozzle configurations. The performance is characterized by the rate of residue removed, which is measured using a laser reflectivity technique. It is demonstrated that the optimum rate of residue removal is achieved when the air/liquid mixture temperature is as high as possible without evaporating liquid and the water flowrate is as high as possible without water droplets agglomerating. Based on theoretical considerations in conjunction with the experimental results, it is demonstrated that the residue removal mechanism is due to emulsification upon liquid droplet impact with the target surface. Potential applications for the jet impingement facility reach far beyond the aerospace industry.
Effects of local flow on the heat transfer characteristics of a cowled, finned system
Authors: Gallagher G J , Griffiths A J , Lin S , O'Doherty T
Published: October 2002

Experimental studies of the local flow and heat transfer characteristics within the finned region of a cowled, annularly finned cylinder are presented. The temperature and local heat fluxes across fin surfaces were measured using thermocouples and Micro-foil™ heat flux sensors. Areas of maximum heat transfer coefficients greater than 60 W/m2K were observed in the forward fin tip and base regions. A local minimum of 12 W/m2K was found in the mid-fin regions behind the finned cylinder. The local flow characteristics with in the finned region were measured using laser Doppler anemometry at an inlet Reynolds number of 4 × 105. Areas of high turbulence intensity and shifting high-velocity zones were found. Correlation between the heat transfer and flow characteristics confirm the existence of boundary layer development, forward edge separation, and root and tip vortices. The application of the cowl system on a finned cylinder leads to a heat transfer enhancement of greater than 29 per cent. Localized fluctuations of the heat flux on the fin surface are also discussed.
Automated visual inspection of wood boards: Selection of features for defect classification by a neural network
Authors: Pham D T , Alcock R J
Published: October 2002

Attempts are being made to automate the process of wood sheet grading by using automated visual inspection (AVI). In AVI of wood sheets, much work has been performed on the segmentation and classification stages but relatively little on the extraction of features from segmented images for defect classification purposes. This paper concentrates on feature extraction and presents 32 features potentially suitable for characterizing wood defects. The paper describes a technique for evaluating features and discusses its application to the selection of the features helpful for accurate defect classification by a multi-layer perceptron.
Polyfunctional plants for industrial waste disposal: Capacity analysis
Authors: Caputo A C , Pelagagge P M
Published: October 2002

A major problem in polyfunctional plant planning concerns the search for the optimal treatment capacity in relation to the input waste mix. The capital intensive nature of polyfunctional plant projects needs, in fact, careful evaluation analyses to help investors to make wise economic decisions. In this paper a polyfunctional plant capacity analysis has been carried out, aimed to highlight the effect on investment profitability and to identify the optimal plant size. In this way a treatment capacity has been recognized which is able to pursue best values for all the considered evaluation indexes. Generally speaking an unequivocal optimal plant size occurs, which corresponds, in the examined scenario, to an incoming waste stream of about 300000 ton/year. As a result, the polyfunctional plant planning problem may be effectively faced by adopting capacity analysis as a methodological approach.
Design for optimum gasket assembly stress and leak rate control in bolted gasketed joints
Authors: Nau B S
Published: October 2002

The behavioural factors affecting the design of a bolted gasketed joint for a prescribed leak rate are described. The traditional approach is now known to be ill founded while the proposed alternative has disadvantages. These approaches are outlined and their problems described. An improved design method is presented, on the basis of a design chart. In this the optimum gasket assembly stress to achieve a given level of leak tightness is plotted against the known gasket stress change as the fluid pressure is applied, giving curves for a series of leak-tightness values. The design chart can be derived graphically from a Pressure Vessel Research Council (PVRC) ‘ROTT’ test-data plot or by calculation from the PVRC gasket coefficients Gb, a and Gs; the procedures are described. The approach presented has the advantages of simplicity and accuracy. Examples of the new design chart are given for ten types of gasket and the effects of varying individual PVRC gasket coefficients are demonstrated.
An approach to design for reliability
Authors: Thompson G , Liu J S , Hollaway L
Published: October 2002

A method is presented by which design problems may be formulated, evaluated and developed in order to achieve maximum reliability. The method integrates component failure and functional performance considerations so that a maximum safety margin is achieved with respect to all failure criteria. The method proposed does not rely on failure rate data. Additionally, provided that all parameters are able to be calculated, it is possible to undertake a multi-objective optimization to determine an optimal solution.
Rolling contact fatigue of rails—finite element modelling of residual stresses, strains and crack initiation
Authors: Ringsberg J. W. , Bjarnehed H , Johansson A , Josefson B. L.
Published: October 2002

Numerical models that can be used to evaluate crack initiation in rails owing to rolling contact loads are of great value. Very few models on rail fatigue assessments exist in the literature that consider the non-linear stress and strain response in the rail caused by both global dynamic track response and local wheel-rail contact loads. In the present investigation, such a tool has been developed using finite element (FE) models. The tool can be used to calculate governing fatigue conditions such as residual stresses, plastic strains and orientation of crack planes for crack initiation. The ability to perform parameter studies of, for example, track properties, different materials and load cases is inherent in the tool. The tool was used in a case study of commuter train traffic at a Swedish test site. In the FE simulations, a material model with non-linear isotropic and kinematic hardening, which was able to consider ratchetting behaviour, was used. Ratchetting material response near the railhead surface was found. A criterion for fatigue crack initiation caused by ratchetting and a criterion for fatigue crack initiation caused by low-cycle fatigue (LCF) were compared. The LCF criterion showed the lowest number of cycles to crack initiation, which, given the models used, indicates that cracks will initiate owing to LCF rather than ratchetting. Good agreement for the direction of surface cracks between the rail track at the test site and the results from the simulations was achieved.
The Northern Line train service contract
Authors: Harding A , Watts P
Published: October 2002

The involvement of the private sector in the funding of large-scale public sector projects has become a feature of Government policy within the United Kingdom. The first such initiative within the railway field has been the usage contract placed by London Underground Limited (LUL) with the ALSTOM Transport Sector. The implementation and operation of this very large contract could well become a model for future projects.
The calculation of noise from railway viaducts and bridges
Authors: Harrison M. F. , Thompson D. J. , Jones C. J. C.
Published: October 2002

The noise radiated by railway bridges and viaducts may add to the environmental impact of railways. Statutory requirements for environmental impact assessment of new railway schemes have led to the development of different methods for calculating such noise. A rapid calculation method is presented that is based on a particular form of statistical energy analysis. The method takes account of the origin of the noise, i.e. the relative roughness at the wheel-rail interface, and provides a framework for the calculation of the propagation, dissipation and final radiation of vibrational energy as noise. Validation of the method is provided for a particular form of composite concrete and steel viaduct. The elements of the structure contributing most to the levels of structure-radiated sound under the soffit are identified, along with means for reducing that noise by track and bridge or viaduct design.
Improvement to the aerodynamic characteristics of Shinkansen rolling stock
Authors: Ito M
Published: October 2002

Following the Series 300, which was introduced in March 1993, the next-generation Series 700 train-set was put into commercial operation on the Tokaido-Sanyo Shinkansen lines in March 1999. The Series 700 has a number of aerodynamic improvements, focusing on the nose shape, the area around the carbody, car coupling areas, the pantograph and the pantograph cover. These improvements have resulted in lower wayside noise and pressure fluctuations, improved riding comfort in tunnels, reduced power consumption and increased speed (285 km/h) over some track sections. This paper reports the development of the Series 700 train-set by describing the techniques used to improve the aerodynamic characteristics of the car and the results of the improvements in comparison with the Series 300 train-set.
The effect of intermittent lubrication on the fatigue life of pearlitic rail steel in rolling-sliding contact
Authors: Fletcher D. I. , Beynon J. H.
Published: October 2002

Railway flange lubrication can be unreliable, resulting in intermittent rather than continuous lubrication. Twin-disc contact simulation tests were carried out to investigate the influence of intermittent lubrication on rail steel fatigue life, using both a colloidal suspension of molybdenum disulphide in an oil carrier fluid (similar to a commercial flange lubrication product) and water. A brief interruption of the lubricant supply during molybdenum disulphide lubrication produced rapid surface failure of the rail steel, which was followed by rapid contact fatigue crack growth upon reapplication of the lubricant. During water lubrication the interruption of the lubricant (water) supply did not produce such rapid crack growth. The results were found to be in qualitative agreement with the predictions of the three-mechanism model of rolling contact fatigue, which combines the mechanisms of ratchetting (accumulation of unidirectional plastic strain until the critical failure strain of the material is reached) and the fracture mechanics-based mechanisms of shear stress driven and tensile fluid assisted crack growth. Analysis of the test results using this model revealed crack face friction to be an important factor controlling crack growth, which may be responsible for the difference in behaviour between contacts lubricated with the molybdenum disulphide-based lubricant and those lubricated by water.
Influence of track gauge variation on rail vehicle dynamics (an examination based on comparison between data from a test train running on track with irregularity artificially set and numerical simulation)
Authors: Fujimoto H , Tanifuji K , Miyamoto M
Published: October 2002

In order to clarify the relation between train dynamics and track irregularity, test trains running on track irregularities artificially set were run at a speed of up to 210km/h and the responses of the carbody, etc., were observed on the Jyoetsu Shinkansen line in Japan. The authors analysed the responses of the carbody to alignment irregularity with gauge enlargement (enlargement of the rail-flange clearance) on the basis of the observed data. The responses were compared with the results of vehicle dynamics simulation. In addition, using the same simulation program, the influence of gauge variation on carbody hunting motion of a new high-speed Shinkansen train, which has soft suspension between the carbody and bogie owing to the bolsterless bogie, was studied. It was concluded that gauge enlargement decreases the response to alignment irregularity but lowers the stability of hunting characteristics.
Out-of-round railway wheels-a literature survey
Authors: Nielsen J. C. O. , Johansson A
Published: October 2002

This literature survey discusses the state-of-the-art in research on why out-of-round railway wheels are developed and on the damage they cause to track and vehicle components. Although the term out-of-round wheels can be attributed to a large spectrum of different wheel defects, the focus here is on out-of-round wheels with long wavelengths, such as the so-called polygonalization with 1-5 harmonics (wavelengths) around the wheel circumference. Topics dealt with in the survey include experimental detection of wheel/rail impact loads, mathematical models to predict the development and consequences of out-of-round wheels, criteria for removal of out-of-round wheels and suggestions on how to reduce the development of out-of-round wheels.
Class Re 465 locomotives for heavy-haul freight service
Authors: Gerber P
Published: October 2002

The class Re 465 locomotives operated by the Swiss private railway company BLS Lötschbergbahn Limited (Fig. 1) are the result of further development of Swiss Federal Railways' Re 460, the first new class to emerge from the Lok 2000 design concept for main-line locomotives. The converter-fed class Re 465 locomotives with their new drive concept involving independent traction supplies for each axle have enabled enhanced heavy-haul freight service on Swiss transalpine lines. Daily, up to three ‘Jumbo’ trains with a gross mass of up to 3250 t are hauled by Re 465 locomotives over the Swiss Lötschberg—Simplon transalpine route from Basle to Domodossola.
The critical speed of a railway vehicle on a roller rig
Authors: Allen P. D. , Iwnicki S. D.
Published: October 2002

The dynamic behaviour of a railway vehicle is largely governed by the interaction of the wheelset with the track. This behaviour can be reproduced in a laboratory using a roller rig and can also be mathematically simulated by solving the equations of motion which govern the dynamic behaviour. This paper presents the results of a study that compares the predictions of these equations of motion for a one-fifth scale railway vehicle on track and on a roller rig. In particular, the critical speed at which the motion first becomes unstable has been shown to differ between the vehicle on track and on the roller rig. It has been shown that for most cases the roller rig case has a lower critical speed but for some suspension parameter combinations the critical speed on the roller rig can be higher.
Ultra light rail developments
Authors: Griffin T
Published: October 2002

Ultra light rail systems are small-scale tramways that utilize energy storage rather than continuous electrification. They have excited considerable interest because potentially they are a very cost-effective way of providing attractive urban public transport.

This paper describes latest technical advances and service experience of the two principal developers. These are the Parry-Clayton range of vehicles, which are concentrating on mechanical and mechanical/hydrostatic transmission systems, and the EROS vehicle, which will have electric transmission. The paper also considers longer-term traction options and developments in related fields that should allow some transfer of technology to accelerate the process of achieving market-ready products.
The development of a railway dynamics modelling and simulation package to cater for current industrial trends
Authors: Shen G , Pratt I
Published: October 2002

A number of proprietary software packages, focusing on predicting the dynamic behaviour of railway vehicles, have been developed over the last 30 years. These packages have gained wide acceptance within the industry, since they shorten the design cycle and avoid the need for extensive field testing. The current trend within the industry to move towards to the development of vehicles with mechatronic systems and non-standard vehicles, has highlighted the shortcomings of many of these packages. Parallel developments in the software industry have led to the adoption of object-oriented and knowledge-based techniques. These techniques aid the human thought process; it is convenient to think of a railway vehicle as an assembly of many objects: bogies, axles, etc. This paper describes the development of a new software tool, based upon these techniques, which is intended to highlight many of these advantages.
Abrasive wear of railway track by solid contaminants
Authors: Grieve D. G. , Dwyer-Joyce R. S. , Beynon J. H.
Published: October 2002

The operation of railway track is likely to involve the presence of solid contaminants on the line at some stage. This may be from the dispersion of freight goods such as coal or minerals, or the presence of ballast stone thrown on to the track either by the passage of the train or during ballast cleaning operations. In addition, where a driver experiences low traction (particularly on steep or liquid-contaminated track), sand may be deliberately placed on the track surface to improve traction. Railway track in dessert areas is also known to suffer from severe wear induced by wind-borne sand particles. The effect of these contaminants is of concern since they may cause damage and accelerated wear of both track and wheel. This paper attempts to examine the effect of brittle contaminant materials on the wear of railway track. A series of small-scale laboratory experiments has been carried out in which crushed granite ballast is fed into a rolling-sliding contact. The level of surface damage is shown to be slight and generally insignificant when compared to normal rail roughness. However, the repeated entrainment of solid particles can lead to excessive wear. An attempt has been made to quantify this wear process and to develop a simple empirical model.
A model of an actively controlled roller rig for tests on full-size railway wheelsets
Authors: Bruni S , Cheli F , Resta F
Published: October 2002

A mathematical model of a roller rig for full size tests on a railway wheelset is proposed. The model is used in order to allow optimal utilization of the testing facility and is expected to give important insights into wheel-rail contact modelling and wear mechanisms, through comparison between numerical results and experimental ones performed in a controlled and stable environment. The mathematical model includes a description of the mechanical system, of the hydraulic actuators and of the electric servomotors used to control the motion of the wheelset. Comparisons between measurements performed on the roller rig and numerical results provided by the model are reported and briefly discussed.
Dynamic analysis of the track structure of a high-speed railway using finite elements
Authors: Lei X
Published: October 2002

In this paper, a three-dimensional model for analysing track structure is developed by means of a finite element method, in which rails, ties, rail clips and pads, ballast and roadbed are considered as a whole system. The action of the locomotive and rolling stock on a track is obtained using a wheelset model. In the wheelset model, only sprung mass is considered and the weight of the locomotive or rolling stock is assumed to be uniformly distributed to each wheelset. The track structure is treated as a double elastic beam. The three-dimensional analysis of the track structure of a high-speed railway is performed by first using the wheelset model to derive the load spectrum varying with the time and acting on the ties. The load spectrum is then entered as input data into the model for three-dimensional analysis of the track structure. Finally, analyses of the dynamic response of the track structure to high-speed trains (TGV) at different speeds are performed.
Calculating speech intelligibility for the design of public address systems at railway stations
Authors: Harrison M. F.
Published: October 2002

Station public address (PA) forms part of a wider passenger information system that otherwise provides visual information. The PA system makes a unique contribution as information is actively broadcast rather than passively displayed and people's attention, including those with impaired vision, is thereby attracted. This valuable contribution is lost in cases where the announcements are unintelligible. A method is presented for the calculation of the speech transmission index (STI) of speech intelligibility in railway stations; this method may be used to design new PA systems. The method uses a quasi-diffuse model to calculate the level of PA announcements broadcast over a given physical area, the modulation transfer function and finally the STI. The method is shown to produce predictions of the rapid speech transmission index (RASTI) that agree well with results measured on railway station platforms in the open air and on platforms in deep-tube underground stations. The method is described as being hybrid empirical/deterministic as it requires prior knowledge of the spatial average reverberation times and of the prevailing background noise levels while calculating other parameters. This approach along with simplifying assumptions for the relative influence of direct and reverberant speech allows the rapid calculation of STI or RASTI and removes the need to describe the station structure in three dimensions as required by completely deterministic methods. The common requirement for PA systems to meet a performance target of at least 0.5 STI is investigated for station platforms in the open air and those in deep-tube underground stations.
Watershed UK accidents—lesson learned
Authors: Rasaiah W. G.
Published: October 2002

Rail vehicle crashworthiness in the United Kingdom has developed over the past 15 years or so and is based on lessons learned from accident statistics and specific multifatality accidents. Recent UK accidents and developments in rolling stock design and operation require a review of current specifications and consideration of practicable changes to enhance crashworthiness in the future.

This paper reviews ‘watershed’ UK accidents which have shaped vehicle crashworthiness design so far and the recent accidents which are likely to do so in the future. It begins with an overview of crashworthiness principles and accident statistics.
Structural crashworthiness—possibilities and practicalities
Authors: Lewis J. H.
Published: October 2002

Historically, improvements to the crashworthiness of rolling stock have come about largely through the investigation of accidents. More recently, specific programmes of work have been aimed at providing and validating improved levels of crashworthiness in vehicle design standards. Concurrently with these improvements, vehicle performance continues to advance and, as it does, the general public demands ever-increasing levels of safety; vehicle crashworthiness requirements must hence be continually reassessed. This paper addresses a few areas where enhancement of current standards should be considered to improve vehicle passive safety further.
An introduction to China's rail transport Part 2: Urban rail transit systems, highway transport and the reform of China's railways
Authors: Xue X , Schmid F , Smith R. A.
Published: October 2002

In this paper, an introduction is provided to some of the components of China's transport system. The authors include the urban rail transit systems, the highway transport systems and its competition for China's railways and the reform of China's railway industry. This is the second of two papers on the situation of rail transport in China.
Geometrical analysis of self-compensating suspension systems for railcar engineering
Authors: Sorge F
Published: October 2002

The present analysis addresses several passive tilt systems for railroad cars aiming to compensate for the cart deficiency on curved tracks. To this end, the virtual centre of suspension must be located as close as possible to the longitudinal plane of symmetry of the coach, above the mass centre level for stability reasons. On the one hand, pantograph or Peaucellier's mechanisms may achieve the correct self-compensation. On the other hand, simpler articulated systems yield the desired goal with an excellent approximation. For example, selective algorithms can be applied for designing eight-link mechanisms, to be optimized thereafter by some method of the gradient type, minimizing the mean square value of the transverse acceleration component.
Wheel-rail dynamics with closely conformal contact Part 2: Forced response, results and conclusions
Authors: Bhaskar J , Johnson K. L. , Woodhouse J
Published: October 2002

The linearized dynamic models for the conformal contact of a wheel and rail presented in reference (1) have been used to calculate the dynamic response to a prescribed sinusoidal ripple on the railhead. Three models have been developed: single-point contact with low or high conformity, and two-point contact. The input comprises a normal displacement Δeiwt together with a rotation Δeiwt applied to the railhead. The output comprises rail displacements and forces, contact creepages and forces, and frictional energy dissipation. According to the Frederick-Valdivia hypothesis, if this last quantity has a component in phase with the input ripple, the amplitude of the ripple will be attenuated, and vice versa. Over most of the frequency range, a pure displacement input (Ψ = 0) was found to give rise, predominantly, to a normal force at the railhead. A purely rotational input (Δ = 0) caused a single point of contact to oscillate across the railhead or, in the case of two-point contact, to give rise to fluctuating out-of-phase forces at the two points. The general tenor of behaviour revealed by the three models was similar: frictional energy dissipation, and hence wear, increases with conformity and is usually of such a phase as to suppress corrugation growth. Thus the association, found on the Vancouver mass transit system, of corrugations with the development of close conformity between wheel and rail profiles must arise from some feature of the system not included in the present models.
Calibration of an on-board noise measuring device by simultaneous measurements of trackside noise of three different wheelsets for the ETR500 FS train
Authors: Bracciali A , Ciuffi L , Ciuffi R
Published: October 2002

An on-board device for bolting to the axlebox of a railway vehicle or locomotive to measure rolling noise close to the wheel surface has been developed by the authors (1, 2). Even though laboratory calibration and test runs have shown that the measured noise data are consistent, there was no way to prove that they were in accordance with the on-ground measured ones. Italian State Railways (FS) have performed tests with different wheelsets to evaluate the efficiency of several noise-reduction solutions; during these tests it was possible to repeat noise measurements on-board, therefore obtaining a sufficient amount of data to calibrate the device and to analyse in detail the behaviour of such wheelsets. Calculated calibration constants prove that on-board measured data can be used with confidence to estimate noise levels at several distances from the track, thereby reducing the necessity of long and expensive on-ground tests to measure environmental noise pollution.
Railway managers—creative styles
Authors: Murtaza M. A.
Published: October 2002

This paper deals with the analysis of an individual's style based on Kirton's adaption and innovation inventory (KAI) score. The KAI score identifies an individual's style, i.e adaptive or innovative. Analysis includes various constituents of a group e.g. managers, ministerial staff, technical supervisors, artisans, men and women. Group estimates of individuals and the individual's scores are indicative of a positive relationship and the KAI score can be used to identify an individual's style so as to form a team for a specific task or project.
Risk management and assessment for rolling stock safety cases
Authors: Kennedy A
Published: October 2002

Since the introduction of the Railway (Safety Case) Regulations in 1994 the railway industry has gone through a steep learning curve as the new safety culture has become established. A key question for any safety case is ‘how safe is safe enough’ since it is never possible to eliminate all risk. To answer this question it is necessary to establish risk or safety targets and then demonstrate compliance with them. Based on his experience preparing the Heathrow Express rolling stock safety case for Siemens, the author describes the stages of establishing the safety targets and demonstrating compliance with them. The criteria by which individual risks, rather than the train's overall safety performance, are judged is also considered. Finally, the merits of this approach compared to the risk matrix adopted by Railtrack, and currently being reviewed, is discussed.
Introduction: Theory of tilting train behaviour
Authors: Harris H. R. , Schmid E , Smith R. A.
Published: October 2002

This paper is intended as a general introduction to the concept of tilt and its value to the railways. Relevant railway curve design concepts are discussed, paving the way for a discussion of limits to tilt application. The performance advantages of tilting systems, including passenger comfort and reduced journey time, are discussed. Second-order effects such as increased track forces and fuel savings are also included.
Rolling stock to eliminate the gaps in the high-speed network—tilting trains in Germany
Authors: Kottenhahn V
Published: October 2002

This paper traces the history of the introduction of tilting trains in Germany. It is hoped that with their introduction in 1999 journey times on long-haul routes can be reduced.
Development of a wheel mounted disc brake for a high-speed train
Authors: Tirovic M
Published: October 2002

This paper describes the development of a wheel mounted disc brake for the power car of a high-speed train. The disc design consists of two rings bolted on to the wheel hub, one either side of the wheel. The finite element method was used extensively from the very beginning of the design process. This considerably reduced development time and enabled the successful design of a disc for an extremely severe duty. Modelling of bulk thermal effects was found to be most effective for shape optimization and prediction of global disc behaviour, with more sophisticated analyses required to determine more detailed design limits. Results from dynamometer tests and vehicle trials gave good correlation with theoretical results and proved the design suitability for the required duty.
Wheel/rail impacts at a railway turnout crossing
Authors: Andersson C , Dahlberg T
Published: October 2002

The vertical dynamics of a common Swedish railway turnout under the load of moving vehicles is investigated. The turnout is described by a linear finite element model with modal damping. The model of the turnout (a section of it) has a length of 36 sleeper spans surrounding the crossing. Rails and sleepers are modelled with uniform Rayleigh-Timoshenko beam elements. The rails are connected via railpads (linear springs) to the sleepers, which rest on an elastic foundation. The vehicles which model the dynamic behaviour of trains are discrete systems of masses, springs and dampers. They pass the turnout on the through rails at a constant speed and only vertical dynamics (including roll and pitch motions) is studied. The wheel/rail contact is modelled by use of a non-linear Hertzian spring. The train/track interaction problem is solved numerically by using an extended state space vector approach in conjunction with modal superposition for the turnout. The analyses show that the rail discontinuity at the crossing leads to an increase in the wheel/rail contact force. Both smooth and irregular transitions of the wheels from the wing rail to the crossing nose have been examined for varying speeds of the vehicle. Under perfect conditions, the wheels will change quite smoothly from rolling on the wing rail to rolling on the nose. The impact at the crossing will then be small, giving a maximum wheel/rail contact force which is only 30-50 per cent larger than the static contact force. For uneven transitions, the severity of the impact loading at the crossing depends strongly on the train speed. The increase in the contact force, as compared with the static force, is of the order of 100 per cent at 70 km/h and 200 per cent at 150 km/h.
Maintenance depot transformation, not just a face-lift
Authors: Chamberlin M , Weerasinghe M
Published: October 2002

London Underground Limited (LUL) has awarded GEC ALSTHOM (GECA) a service provision contract to provide and maintain 106 new trains under a leasing agreement for the next 20 years. The service will be provided to the Northern Line, with LUL retaining responsibility for operational control. Maintenance will be performed in the existing Northern Line facilities and the depots will be leased from LUL to GECA for the contract period. The maintenance depots require modernization to support the new trains and GECA Railway Maintenance Services Limited (RML) will manage and operate the depots. RML is now responsible for delivering the existing trains to the Northern Line and for introducing the new fleet of trains while the maintenance facilities are modernized. This paper addresses the modifications made to the maintenance facilities for the new fleet of trains. It discusses the philosophy behind the redesign of the depot layout, the steps throughout construction and the maintenance equipment necessary to provide the service required to meet the needs of the customer.
Idealized steady state interaction between railway vehicle and track
Authors: Dukkipati R. V. , Dong R
Published: October 2002

There are two types of distinct periodic dynamic waves in the history of the wheel/rail contact force. The first is caused by the variation in overall track stiffness owing to the effect of tie spacing. The second is caused by the travelling motion of the wheel and the oscillations of discrete supports. In the present train speed range these dynamic forces are usually less than 5 per cent of the static load, except that the coupled wheel/track resonant frequencies are excited at some speeds. The resonant forces due to discrete supports may be larger than 5 per cent of the static load in some cases. The magnitude of the resonant force mainly depends on the unsprung mass, tie spacing, vehicle primary and track ballast damping, rail stiffness and the stiffness on each support.
Tyre fracture: The problem, the causes and preventative action
Authors: Pollard M. G.
Published: October 2002

This paper investigates the causes of a tyre failure that occurred on 21 March 1998. The investigation has shown that faults in the cast steel from which the tyre was formed were translated into flaws in the tyre which cracked through hydrogen embrittlement. The crack created within the tyre generated associated fatigue cracks and these led to the complete rupture of the tyre. Recommendations are made to improve specifications and quality processes to ensure that, in the future, such imperfections are found before tyres are fitted to vehicles.
The influence of the non-linear stiffness behaviour of rail pads on the track component of rolling noise
Authors: Thompson D. J. , Jones C. J. C. , Wu T. X. , de France A
Published: October 2002

The stiffness of the rail pad is a critical parameter in determining the noise from the track. Both theoretical and experimental studies show that a stiff pad, by coupling the rail to the sleeper, leads to a high attenuation of rail vibration with distance along the track and an increase in the sleeper vibration. In this way the rail-radiated component of noise is reduced but the sleeper component is increased. Conversely a soft pad leads to a low sleeper noise component but greater rail noise, as the rail can vibrate over a greater length. In modern track, soft pads are used, as they lead to reduced track forces and less damage to track components such as sleepers. In this paper, measured vibration characteristics of track are presented and compared with predictions. A recent study of the effect of the load dependence of the rail pad and ballast stiffnesses on the dynamic behaviour of the track is extended to give a practical assessment of the effects on the noise radiation. It is shown that, for a typical soft pad with a high load dependence, neglect of the preloading effect would lead to a significant overprediction of the track noise component. It is thus shown that soft pads need not be so disadvantageous for noise as has been suggested.
On freight wagon dynamics and track deterioration
Authors: Stichel S
Published: October 2002

To increase understanding of the running behaviour of freight wagons a research project was started at the Royal Institute of Technology (KTH) in 1996. The background to the project included plans to increase axle load, loading gauge and speed of freight trains in Sweden to make freight traffic more competitive. Simulation models for three different types of UIC freight wagon running gear were developed. The present paper focuses on track deterioration of freight wagons caused by high vertical wheel-rail forces. First the characteristics and modelling of some suspension elements are described, followed by a description of the deterioration model. Then the influence of the parameters of axle load, height of the centre of gravity and vehicle speed on track deterioration is investigated. Track parameters such as rail type and sleeper spacing are varied. The conclusion is that track deterioration per transported pay load increases when the axle load and loading gauge are increased. However, this can be compensated by using an improved track design.
Recasting the Fay-Riddell formulae for computing the stagnation point heat flux
Authors: Zuppardi G , Esposito A
Published: October 2002

The Fay-Riddell formulae, used to compute the heat flux at the stagnation point of spherical bodies in very high speed, laminar flow and dissociating air, have been revived and recast. As these formulae were obtained by fitting a number of results of the original Fay-Riddell computing procedure, which suffered from inaccuracies concerning operative parameters, it is to be expected that these inaccuracies also influence the correctness of the formulae. A sensitivity analysis has been made in order to identify the most critical parameter. Recast formulae have been calibrated using the results of the improved version of the Fay-Riddell computing procedure and then validated both by numerical results of a Navier-Stokes code and by experimental data. For this purpose two sets of heat flux measurements have been made in HEBDAF (high enthalpy blown-down arc facility) at the University of Naples, matching the operating conditions of the formula for a frozen boundary layer and non-catalytic wall. Recast formulae are valid in the range of free-stream total enthalpy between 3 and 37 MJ/kg.
Vibration control of composite plates under random loading using piezoelectric material
Authors: Lee Y-Y , Ng C-F
Published: October 2002

A study of the use of H∞ control design to suppress the vibrations of composite plates with embedded piezoelectric actuators under random loading is presented. The finite element method is employed to obtain the dynamic equations of plate vibration. The finite element model includes fully coupled structural and electrical nodal degrees of freedom. The modal reduction method using the structural modes is adopted to reduce the finite element equations into a set of modal equations with fewer degrees of freedom. The modal equations are then employed for controller design and time domain simulation. The results of the modal convergence studies of the closed-loop systems show that the truncated modes, which are neglected in the control design, deteriorate the controller performance and affect the optimal location and size of the actuator. The vibrations of plates subjected to off-resonant narrow-band excitations cannot be suppressed significantly. The controller shaped with an extra weight function for mitigating measurement noise gives better vibration reduction performance.
Longitudinal flightpath predictor design for minimum pilot compensation
Authors: Sachs G
Published: October 2002

Flightpath prediction can substantially enhance the guidance and control capabilities offered by a novel display type that presents guidance information in a three-dimensional format. Based on pilot-centred requirements, a predictor design for longitudinal motion is proposed to achieve minimum pilot compensation for controlling the predictor-aircraft system. Key configuration factors of the pilot-predictor-aircraft system are identified and optimized. The compensatory control issues are verified in a simulation test program.
Numerical simulation of high-speed turbulent reacting coaxial jet flow using a structured grid
Authors: Mehta R C
Published: October 2002

Reacting flowfields are described by compressible turbulent Reynolds-averaged Navier-Stokes equations augmented with appropriate species continuity equations that provide for the convection, diffusion and production of each chemical species. The closure of the system of equations is achieved using a two-equation turbulence model. A single-step overall fast chemical reaction combustion model based on the eddy break-up concept is employed for the turbulence-chemistry interaction. A finite volume discretization is carried out in spatial coordinates to compute inviscid and viscous flux vectors. A multistage Runge-Kutta time-stepping scheme is used to obtain a steady state solution. The numerical algorithm is developed by taking into consideration the structured grid arrangement for a turbulent chemically reacting coaxial jet. The numerical scheme is shown to be computationally fact, easy to program and efficient. A supersonic diffusion flame is analysed and the results are compared with the available experimental data.
CHIMERA volume grid generation within the EROS code
Authors: Allen C B
Published: October 2002

The EROS (European ROtorcraft Software) project was a three-year, European Commission funded, collaborative project between research institutes, universities and industry, with the goal of producing a practical computational fluid dynamic (CFD)-based design tool for rotor blade design. The overlapping mesh, or CHIMERA, approach was adopted for structured grid generation within the project. The specifics of volume grid generation in GEROS, the EROS grid generator, are presented here. The capabilities and effectiveness of GEROS are demonstrated, and sample grids are shown for fixed-wing hovering rotor and forward-flight rotor cases.
An autonomous navigation scheme using global positioning system/geomagnetism integration for small satellites
Authors: Zuo W , Song F
Published: October 2002

This paper presents a low-cost scheme of an autonomous integrated global positioning system (GPS)/geomagnetism navigation system for small satellites to improve the performance of stand-alone GPS or geomagnetism navigation using the existing hardware equipment. In the paper, the use of the GPS and autonomous navigation systems based on magnetic field measurements (ANSMFM) to determine low Earth orbits (LEO) is discussed. The paper combines the GPS with the ANSMFM and constructs a new autonomous GPS/geomagnetism integrated navigation system (AGGINS) using two integration approaches: loosely and tightly coupled integrations. The improved extended Kalman filter completes the data processing for the optimal integration. The paper analyses the benefits of the AGGINS and finally gives simulation results that demonstrate the effectiveness and practicability of the method.
Adaptive notch filter design for bending vibration of a sounding rocket
Authors: Choi H D , Kim J
Published: October 2002

An adaptive notch filter design considering the body bending vibration for the attitude control of a two-stage sounding rocket is discussed in this paper. The algorithm adapts the parameter while keeping the poles of the notch filter inside the unit circle on the z plane, and thus satisfies the conditions concerning stability of the filter all the time. Only a single parameter of the filter is adapted to simplify the algorithm and thus to speed up the convergence rate. Applying this adaptive notch filter to the two-stage sounding rocket results in stable response characteristics of the attitude control system which has been unstable without adaptation. This newly designed method is simple and less CPU intensive, and is easier to implement in real-time application.
Flight test flutter prediction using neural networks
Authors: Crowther W J , Cooper J E
Published: October 2002

Flight flutter testing is a crucial part in the certification of a prototype aircraft. To aid the clearance process, a number of different methods have been proposed to determine the speed at which flutter occurs on the basis of data obtained during the flight envelope expansion. However, the most commonly used approach is simply to extrapolate the estimated damping ratios. In this paper, a method is proposed for the prediction of damping ratios during a flight test using a neural network trained on model data. The proposed method is compared with a simple statistical extrapolation approach, and the effects of noise are investigated. For noise-free data, the neural network method shows improved accuracy compared with the statistical method. With noisy data, the accuracy of the statistical method is unacceptably poor, but the accuracy of the neural network method remains good as long as the network is trained with noisy data.