bluuebunny/crossref_metadata_2025_split huggingface dataset:
Influence of tractor—trailer interaction on assessment of road damaging performance
Authors: Cole D J , Cebon D 
Published: October 2002

The influence of dynamic interaction between tractor and trailer on the assessment of the road damaging performance of heavy goods vehicles is investigated using simple mathematical models. Tractor and trailer damage indices are used to quantify the ‘in-service’ road damaging performance of a simulated fleet of vehicles with parametric variations typical of highway traffic in the United Kingdom. Simulated results of assessment tests on individual tractor—trailer combinations are correlated with the performance of the simulated vehicle fleet. The main aim is to establish the characteristics of a ‘standard’ semi-trailer to be used in the assessment of tractors, and a ‘standard’ tractor for testing semi-trailers. It is found that measurement of suspension ‘frequency’ gives the poorest correlation with the damage indices, while the ‘dynamic aggregate force coefficient’ gives the best correlation. Correlation achieved when assessing trailers is higher than when assessing tractors. Optimum specifications for standard test tractors and trailers to maximize test accuracy are determined.
Development of a modified diesel engine cycle
Authors: Zhou P L , Qian Y Q 
Published: October 2002

This paper presents an investigation of a novel type of diesel engine cycle, an approximate constant pressure cycle. The prototype engine is called the diesel engine with oil cushioned piston (DEOCP). In contrast to conventional engines, the DEOCP has a variable cylinder volume which is controlled automatically by the engine's cylinder pressure. The variable cylinder pressure is achieved by inserting a hydraulic cylinder into the engine's piston rod. The engine cylinder pressure is thus self-controlled and an ideal constant pressure cycle can theoretically be achieved. Computer simulations and engine tests have shown that the DEOCP distinguishes itself with high cycle efficiency, improved low-load performance and good starting ability. A detailed theoretical analysis and test results are presented in the paper, as well as a discussion of existing problems and possible further developments. Development of the diesel engine with oil cushioned piston could break the limit of cycle efficiency of conventional engines, hence opening a new avenue for diesel engine development.
Barrel swirl breakdown in spark-ignition engines: Insights from particle image velocimetry measurements
Authors: Reeves M , Haste M. J. , Garner C. P. , Halliwell N. A. 
Published: October 2002

Particle image velocimetry (PIV) has been used here to study the formation and breakdown of barrel swirl (‘tumble’) in a production geometry, four-stroke, four-valve, motored, spark-ignition, optically accessed internal combustion (IC) engine. The barrel swirl ratio (BSR) of the cylinder head could be enhanced by means of a port face inducer gasket so that the flow processes taking place at low and high swirl ratios could be investigated conveniently. Double-exposed images from planes both parallel and perpendicular to the cylinder axis were recorded at selected crank angles through the induction and compression strokes at a motored engine speed of 1000 r/min, with a wide open throttle, for both high and low BSR cases. The recorded images were interrogated by digital autocorrelation to give two-dimensional maps of instantaneous velocity. In both high and low BSR cases, a barrel or tumbling vortex motion is generated during induction, which is shown to persist throughout the majority of the compression stroke. The details of barrel swirl formation during induction and its subsequent modification during compression, however, differ strongly between the two cases. These differences can be explained qualitatively in terms of two main events; the first being competition during induction between vortices of unequal strength and the second being competition between the large-scale swirl motion and the local flow field generated by piston motion during compression. In the low barrel swirl case, significant dissipation occurs owing to these interactions and consequently the large-scale motion exhibits lower mean velocities and undergoes significant distortion. In the case of high BSR, the competition effects are minimized and a single ordered vertical vortex exhibiting high velocity magnitudes is observed to avoid piston induced distortion. It then moves into the apex of the pent roof combustion chamber where it survives as a single ordered vortex until at least 40° crank angle (CA) before top dead centre (TDC). Limitations and developments of the PIV technique are discussed.
Analysis of stratified EGR and air on combustion and NO formation in a spark-ignition engine
Authors: Zhao H , Peng Z , Calnan P , Ladommatos N , Ma T 
Published: October 2002

Using a phenomenological model (Brunel Engine Emissions, Performance and Autoignition Simulation, BEEPAS) developed at Brunel University, the influence of stratified exhaust gas recycled (EGR) and stratified air (lean burn) on spark-ignition (SI) engine performance and NO emission were analysed. The mixture in the cylinder was divided spherically into three parts: a central core with a stoichiometric air—fuel charge, a dilution region without any combustible charge and a mixing region lying between the core and the dilution region. Three mixture stratification parameters were investigated: the amount of mixing in the cylinder, the extent of dilution in the mixing region and the gradient of stratification in the mixing region. In addition, the difference in the effects on combustion and NO formation of stratified EGR and air was analysed. The results indicate that stratified air operation is better for improving engine efficiency than stratified EGR operation. It was found that the longer combustion duration, as well as the increased heat capacity of EGR, contributes to the superiority of stratified EGR over stratified air in the suppression of in-cylinder NO formation. For the same initial charge temperature, stratified EGR has a much lower dilution limit than stratified air owing to retardation of flame propagation. As long as the degree of dilution in the mixing region is within the dilution limit of the combustible charge, the gradient of dilution has little effect on combustion and NO formation.
Systems integration in maintenance engineering
Authors: Starr A , Ball A 
Published: October 2002

Integration in maintenance engineering systems provides a potential solution to some complex and conflicting problems. Decision making is often achieved with uncertainty and unknowns, while measuring against conflicting performance criteria. Maintenance decisions are made in the context of business priorities.Integration must consider the bidirectional flow of data and information into the decision-making and planning process at all levels. This reaches from business systems right down to sensor level. Integration automates the organization and operation of systems, data collection and actuation, information storage and decision making. Critically, integrated systems display the evidence of thorough top-down system design, which incorporates the elements above and closes the loop from the minutiae of data collection to strategic decision making.This paper introduces the systems associated with maintenance and draws comparisons with adjacent disciplines such as control. A globalized model is proposed, and methods for selecting and adapting technologies for the model are discussed. Examples of industrial implementation are shown at several levels within the model.
Incorporation of modern on-line spectral condition monitoring for operational availability improvement of reactor coolant pumps
Authors: Kang C W , Golay M W 
Published: October 2002

At the design stage, the work reported here recommends provision of the possibility of employing modern on-line spectral condition-monitoring equipment in order to improve the operational availability of nuclear power plant equipment, the reactor coolant pump (RCP). Following an analysis of the leading causes in the RCP forced outages, incorporation of the use of advanced on-line spectral condition-monitoring sensors and their corresponding data-processing equipment in new power plant designs is sought. They are employed in order to detect the incipient symptoms generated during the progression of potential system faults of major concern. Firstly, the applicability of recent developments in new sensors and data-processing techniques is examined. This examination concerns system status parameter monitoring in the analysis of vibration, motor current, partial discharge and wear debris. Finally, use of modern sensors and data-processing equipment, which are valuable for the intended condition-monitoring systems, is recommended. Furthermore, valuable information on the future trend of currently developing sensors at the research stage is briefly presented. This state-of-the-art review lays a foundation for developing modern comprehensive sensor networks to support efficient condition monitoring in other power plant rotating machines.
Effects of the properties of bulk solids on the relative performance of polyethylene and stainless steel wall lining materials in mass flow hoppers and other applications
Authors: Bradley M S A , Bingley M , Farnish R J , Pittman A N , Lee G 
Published: October 2002

Reducing the friction between the walls of storage vessels and the bulk solids that they contain is widely known to be beneficial in obtaining more satisfactory flow patterns in such vessels, and to reduce flow problems. In particular, the advantages of low friction in promoting a mass flow discharge pattern are well understood; means of obtaining data to design a hopper for mass flow are also well established. In recent years a number of polyethylene materials have come on to the market, intended for use in lining silos and claimed by their manufacturers to offer low wall friction in comparison with other materials. In this paper, one particular commercial grade of ultra-high molecular weight polyethylene (UHMWPE) material has been tested alongside a commonly used type and finish of ferritic stainless steel. The wall friction has been measured for both materials, with a variety of bulk solid materials and conditions, and the hopper half-angles needed for mass flow computed for each combination. The results show that the UHMWPE material does not always offer a lower friction than the stainless steel; in some cases it offers much lower friction and hence much greater scope for obtaining mass flow discharge. However, in other cases it gives significantly higher friction and is a bad choice for promoting flow. The principal conclusion is that, under certain circumstances, UHMWPE offers substantial advantages over other wall materials. However, this advantage is by no means universal and, if it is to be considered for employment in a hopper design, then a wall friction test should be undertaken. This test should use a sample of the bulk solid to be handled against both the UHMWPE material and other possible materials.
Optimization of a heat exchanger network superstructure using nonlinear programming
Authors: Morton W 
Published: October 2002

A heat exchanger network design for a particular set of hot and cold stream duties requires multiple stream splits for minimum energy use. A modern NLP solver, FilterSQP, is applied to minimize a total cost function that takes account of capital and energy costs. The best solution contains fewer exchangers than the initial network. There are multiple local optima at various cost levels. They contain different subsets of exchangers of the initial design, which constitutes a partial superstructure for the problem. Several optimization alternatives are examined: for the model formulation, leading to problems with different optimum costs, for the way the objective is written, which affects the formal degree of nonlinearity in the equations or objective, and for the way the solver operates. For each combination of options, tests were run using widely different initial values for the Trust Region size, a parameter in the solver. FilterSQP solved the network with impressive reliability and efficiency from several starting guesses, some of which were highly arbitrary. From even the most unpromising initial guesses, the solver converged to a local optimum in nearly all cases.
Vortex magnetic separation
Authors: Watson J L S , Li Z 
Published: October 2002

Vortex magnetic separation (VMS) is a new technique (1-3) which can not only greatly increase selectivity of high gradient magnetic separation but can also provide a much higher material throughput because high slurry velocity is used. This technique will have a wide range of applications in fields as diverse as mineral processing, biochemical engineering, sewage and wastewater treatment and industrial effluent treatment. At present in high gradient magnetic separation (HGMS) low Reynolds numbers (with respect to the wire diameter) are usually used and the magnetic product is captured on the upstream side of the wire matrix which results in a serious mechanical entrainment problem that is very detrimental to the purity of the magnetic fraction and to the reduction of the quantity of non-magnetic fraction (4). Vortex magnetic separation runs at moderate Reynolds number ( Re = 6–40) which leads to the formation of vortex flow in the neighbourhood of the matrix. Magnetic particles in the slurry are first concentrated in the boundary layer flow around the matrix and then brought into the magnetically attractive area on the matrix downstream side. The magnetic deposit on the downstream side of the matrix does not suffer the direct collisions with non-magnetic particles in the slurry, so the quality of the magnetic product is drastically improved. As will be described below, a new invention has been made with regard to the VMS matrix which allows capture to take place on both the upstream and downstream sides of the matrix without mechanical entrainment. This paper reviews experimental and theoretical work on the mechanisms involved in vortex magnetic separation.
Effect of changes in the taper-hub shape on the strength of high-pressure flanges
Authors: Fessler H , Perry D A 
Published: October 2002

Taper hub is the name of a ring of triangular cross-section which is integral with the flange and pipe to strengthen their junction. Eleven models, made of pearlitic-ferritic spheroidal graphite or flake case iron were tested by tightening and pressurizing to failure at room temperature. Models with four different taper-hub lengths and three different fillet radii were tested. Flange fillet, pipe fillet and pipe strains due to increasing (measured) bolt tensions were recorded and converted to non-dimensional stress indices. An approximately linear response was found owing to tightening and pressurization up to the nominal rated pressure of the basic British standard flange. Bolt tightening caused no stresses in the pipe remote from the taper hub. Pressure caused only small changes at the flange fillet. The lengths of the taper hub could be reduced to five pipe wall thicknesses without increasing stresses above those in the standard shape. Doubling the fillet radius increased the nominal hoop stress in the pipe at burst from 67 to 78 per cent of the ultimate tensile strength of the spheroidal graphite cast irons. A reduction in the hub length does not change the failure pressure.
Elastic buckling of imperfect circular toroidal shells under external pressure
Authors: Galletly G D 
Published: October 2002

When perfect, externally pressurized complete circular toroidal shells buckle, the minimum buckling pressure pcr usually occurs in the axisymmetric n = 0 mode, with pcr for n = 2 being only slightly larger. In the present paper, the effects of axisymmetric initial geometric imperfections on reducing pcr for the perfect shell are investigated. Various types of imperfection are studied, i.e. localized flat spots, smooth dimples, sinusoids and buckling mode shapes. The principal geometry investigated was R/b = 10, b/t = 100, although other geometries were also considered. The maximum decrease in buckling resistance, Δ pcr, was found to be about 16 per cent at δ 0/t = 1 and it occurred with smooth dimples at the north (φ = 180°) and south (φ=0°) poles. This value of Δ pcr is not large. Circular toroidal shells thus do not appear to be very sensitive to axisymmetric initial geometric imperfections. The reductions in the buckling pressure of the above shell, arising because of initial imperfections having the shape of the n = 0 and the n = 2 buckling modes, were 12 and 9 per cent respectively for wo/t = 1. These decreases in the buckling resistance are smaller than that for the ‘two smooth dimple’ case mentioned above.
A computational and experimental study of flows in a distribution chamber: Validation of a numerical model
Authors: Wong V H , Thompson C P , Avery P 
Published: October 2002

A computational fluid dynamics (CFD) model of the two-phase flow within a flow distribution chamber is presented in this paper. Several sets of results have been validated against experimental data obtained from a scale model of the chamber. The interaction between air and water within the chamber, the shape and location of the free surface are modelled by the volume-of-fluid (VOF) model. The k-∊ and renormalization group (RNG) k-∊ models are the two turbulence models used in the simulations. It is found that both the two-dimensional and the three-dimensional models using the RNG k-∊ model give a good qualitative description of the flow features within the chamber. The three-dimensional results also show very good quantitative agreement with the experimental results.
Coupled single-axle running gears—a new radial steering design
Authors: Polach O 
Published: October 2002

New railway vehicle concepts with broader and shorter carbodies necessitate new running gear concepts. One of the possibilities, the single-axle running gear, offers several advantages. The disadvantage of the conventional single-axle running gear during curving can be counteracted with a simple coupling between the single-axle running gears of the neighbouring carbodies. This paper presents parameter analysis and design principle of the coupled single-axle running gears. They can be constructed for an almost ideal curve negotiation in a great range of curve radii. The coupling of the running gears not only improves the running characteristics in a curve but also increases the stability limit. Bombardier Transportation Winterthur has developed the coupled single-axle running gears called FEBA. The test runs with prototype as well as with serial running gears in the Norwegian commuter train Class 72 have fully confirmed the anticipated running characteristics.
Train position and speed estimation using wheel velocity measurements
Authors: Allotta B , Colla V , Malvezzi M 
Published: October 2002

In order to improve safety and efficiency in the management of modern railways, several systems for monitoring and control of traffic are being developed. Automatic train protection (ATP) systems command an emergency braking procedure if dangerous situations occur, such as insufficient braking distance to one of the next target positions and target velocities. A novel ATP system named SCMT, to be installed on trains running on Italian railways, is currently being designed. One of the components of SCMT is a module for estimating train speed and positions between fixed balises, which communicate to the on-board system the distance to next targets and the velocity requirements at targets.In this paper algorithms are described for distance to target and velocity estimation, capable of compensating for poor wheel-rail adhesion conditions where conventional odometry algorithms may fail. The algorithms were derived using a variety of methods including neural networks, fuzzy logic and crisp logic. The system was designed and trained using a wide set of experimental data, obtained from test runs carried out with different types of vehicles and conditions (in particular, degraded adhesion conditions were investigated).
Innovations in tram and light rail systems
Authors: Topp H. H. 
Published: October 2002

Some 350 tram or light rail transit (LRT) systems are operated worldwide. After a period of little interest in trams during the 1960s and heavy cutbacks or total abandonment of tram networks, a renaissance combined with sociological and technical innovations is now taking place, especially in North America and Western Europe. More than 100 cities worldwide are considering the introduction of a tram/ LRT system. After defining tram and LRT and dealing with nine different types of tram/LRT, this article focuses on current innovations mainly in German and European cities like Hannover, Karlsruhe, Kassel, Oberhausen, Saarbrücken, Sheffield and Vienna. Sociological innovations encompass a changed perception of urban transport, changed traffic policies, the image of modern trams in the view of the citizens, tram or LRT in pedestrian malls, and the high appeal of well-designed vehicles and stops. On the technical side, innovations include low-floor vehicles, modular vehicle systems, lighter and less expensive vehicles, raised platforms at stops, the use of telematics in public transport for central control of vehicles, traffic lights actuated by vehicles, dynamic information of passengers, and track sharing by railway and LRT vehicles. Finally, tram and LRT systems are appropriate to fill the gap in capacity between bus and metro at construction expenses of about a tenth of a metro system.
Thermodynamic studies of a novel aeroengine concept
Authors: Panting J R , Pullen K R 
Published: October 2002

The purpose of the work described is to indicate the potential of a high-speed, spark ignition compound-turbocharged engine as an alternative to the gas turbine powered turboprop. Using relatively simple thermal cycle models, it is possible to show that such a compound-turbocharged engine should be capable of achieving very high thermal efficiency levels. A more sophisticated model of this engine type confirms these findings. It proves more difficult to estimate the power-weight ratio, but the specific power output of such an engine, measured in units of kW/1, is shown to be very high. In addition, such a thermally efficient engine type will permit a much reduced take-off fuel payload. As well as modelling the compound-turbocharged engine itself, comparisons are also made with the conventional gas turbine. The study focuses on propeller shaft input powers in the region of 1 MW. A suitable design strategy for the new engine type is discussed, including the requirement for a lightweight, continuously variable transmission system. At present, it is intended to employ a high-speed electrical transmission system for this purpose, and this relatively new technology is briefly highlighted.
The double-fuselage layout: A preliminary case study of a possible way of reducing the development costs for new high-capacity aircraft
Authors: Chiesa S , Di Sciuva M , Maggiore P 
Published: October 2002

The double-fuselage layout, sometimes proposed in the past, is considered to be an alternative (by utilizing a great number of components of an existing aircraft) to a new aircraft (with the traditional layout) of about twice the size of the existing aircraft. The development cost reduction is attractive if the technical performance of the double-fuselage is comparable with that of the hypothetical new aircraft. The first aim of the present work is to sketch a double-fuselage layout with similar values of wing loading, thrust-weight ratio and aspect ratio to the reference new aircraft of increased size. On the basis of this sketch, some other topics are discussed, such as the landing gear and tail surface configurations, ground operations, etc. Particular attention has to be paid to structural problems related to the double-fuselage layout, especially the different modes of stress in structural elements of the original aircraft.