bluuebunny/crossref_metadata_2025_split huggingface dataset:
Quality of the Surface Finish of the Head of the Femoral Component and the Wear Rate of the Socket in Long-Term Results of the Charnley Low-Friction Arthroplasty
Authors: Wroblewski B M , McCullagh P J , Siney P D 
Published: February 2007

Four Charnley femoral stems, removed on average 20 years after implantation, were examined for the quality of surface finish of the head. The average roughness was 0.031 μm (range 0.008–0.102 μm) as compared with 0.019 μm (range 0.008–0.031 μm) for the current production models and 0.05 μm as recommended by the British Standard and the International Standards Organization. The average socket penetration rate was 0.022 mm/year and there was no radiological or operative evidence of socket loosening. The findings emphasize the importance of achieving and maintaining good surface finish of the head of the femoral component. A suggestion is also made that the orientation of the asperities may be important.
Smart Structures—a Concept or a Reality?
Authors: Culshaw B 
Published: February 2007

A smart structure has intelligence and reaction capability embedded within it. Consequently, via a sensor and actuator network, it can respond to external environmental or operational requirements. The most obvious driving force stimulating the need for smart structures lies within the aerospace industry but civil engineering interests have already exploited the ideas in, for example, compensating for earth tremors. There may even be a potential to be exploited by a future generation of toy manufacturers. This paper will illustrate the principles underlying the concepts referring to current, evolving and futuristic technologies. It will also assess the present exploitation of the basic ideas and will indicate future trends, making the comparison between European, Japanese and American philosophies towards this rapidly evolving subject. The successful exploitation of smart structure concepts will prove to be vital in twenty-first-century engineering. Potential paths whereby this exploitation may be realized in a European context will be discussed.
Stabilization of the Mechanical Dynamics of a Road Load Simulator Using Classical Control Techniques
Authors: Stringer I A , Bullock K J 
Published: February 2007

The open-loop transfer function of a complex hydrostatic pump-motor dynamometer system was derived from an analysis of the dynamics of the individual components. Many system components exhibit non-linearities; however, internal feedback mechanisms contribute to linearization of sub-systems. The resulting model, which was in good agreement with the system's open-loop performance, was used to predict the behaviour of the closed-loop system, this indicated that the system would be unstable. Classical control theory was used to analyse the performance of a number of stabilizing control strategies, with root locus plots, Bode diagrams and Nichols charts being used to assess the resultant performance. A lead compensation, designed as a differential controller, combined with a bi-linear gain was predicted to provide acceptable speed control. The performance of the system with this controller installed was found to satisfy the design requirements of speed of response, limited overshoot and zero steady-state error.
Modelling of a Radial-Piston Hydraulic Motor
Authors: Chappie P J 
Published: February 2007

The paper is concerned with the theoretical modelling of the torque-producing mechanism in a radial-piston, eccentric-type, hydraulic motor for low-speed operation. The major difficulty in such an analysis is the description of the frictional losses which, at low speeds, principally result from boundary lubrication conditions. The level of friction is also dependent on the distribution of the transferred forces and the amount of distortion in the bearings These forces vary during the pressure cycle, and squeeze-film effects are introduced between the bearing faces during the period of time following the introduction of pressure into the cylinder. The interaction between the frictional effect in the connecting rod bearing and the operation of the hydrostatic slipper is central to the modelling process. Friction coefficients in the bearings are determined that predict similar efficiencies to those obtained from test measurements on a low-speed motor. The evaluation of internal motor parameters is then carried out using these coefficient values in the model. Such a model is invaluable for establishing critical areas in the mechanism and for predicting the effect of component design changes on the motor performance.
Coolant Optimization of a Gas Turbine Engine
Authors: Brown A , Jubran B A , Martin B W 
Published: February 2007

This paper describes an analysis used to study the performance of the gas turbine engine with particular emphasis on the optimum amount of coolant required for maximum overall efficiency of the engine. The effect of pre-bled air, as well as that drawn from the exit of the compressor, is also studied. The optimum amount of coolant for the engine is found to depend on the effectiveness of the heat extraction parameter A, component efficiencies of the engine and the compressor pressure ratio of the engine.
The Batch Pyrolysis of Tyre Waste—Fuel Properties of the Derived Pyrolytic Oil and Overall Plant Economics
Authors: Williams P T , Besler S , Taylor D T 
Published: February 2007

Estimates for the generation of scrap tyres in the European Community are of the order of 1.5 million tonnes per year, including approximately 0.4 million tonnes per year from the United Kingdom. The majority of the tyre waste is dumped in open or landfill sites but represents a large wasted energy potential. Incineration has been considered as an alternative to dumping in an effort to utilize the high calorific value of scrap tyres; however, this disposal route may not maximize the potential economic recovery of energy and chemical materials from the waste. Pyrolysis of tyres is currently receiving renewed attention, since the derived oils may be used directly as fuels or added to petroleum refinery feedstocks; they may also be an important source of refined chemicals. The derived gases are also useful as fuel and the solid char has the potential to be used either as smokeless fuel, carbon black or activated carbon. In this paper, halved and whole scrap tyres were pyrolysed in a commercial two tonne per day batch pyrolysis unit at furnace temperatures from 700 to 950°C. The proportion of derived products was dependent on pyrolysis conditions, with a maximum yield of 30 per cent oil. The fuel properties of the derived oils, including calorific value, flash point, carbon residue, viscosity, sulphur content, etc., were analysed and compared to refined petroleum products. In addition the benzene, xylene, toluene, limonene and styrene concentration of the oils was determined to assess the potential of the oils as a source of chemical feedstocks. The oils were also analysed in terms of their chemical composition via liquid chromatography and Fourier transform infra-red spectroscopy and molecular mass range. The pyrolytic oils derived from tyres showed properties that were dependent on pyrolytic conditions and showed fuel properties comparable to those of petroleum products.
Derivation of the Torque—Speed Characteristic of a Reaction Turbine
Authors: Levy D 
Published: February 2007

When a reaction turbine is coupled to a generator or when an electric motor is coupled to a pump, the torque–speed characteristic of the runner needs to be known so that the control engineer can analyse the system for stability and optimal operation. The currently used one-dimensional vector analysis applies only where there is smooth flow in the inlet of the machine. This paper modifies and extends this analysis to apply to a variable flow situation which occurs when the load on the machine is not equal to the optimal specified load. Runaway speed and starting torque of the machine can also be calculated using this analysis.
The Supplementary-Fired Exhaust-Heated Cycle for Coal, Wood and Refuse-Derived Fuel
Authors: Wilson D G 
Published: February 2007

An analysis is presented of a system that would enable refuse-derived fuel (RDF) (produced from, principally, paper) or other biomass (for example wood chips) or coal to be burned cleanly in a highly efficient gas turbine system of a size that would match the needs of many communities (a solid waste flow of 1000–3000 tons per day). The system consists of a gas turbine engine with two principal and several minor additions. The principal additions are a combustor to burn the RDF at approximately atmospheric pressure in the hot turbine exhaust flow and a high-temperature heat exchanger to transfer heat from this stream to the compressed air leaving the compressor. A design-point thermal efficiency of 55–60 per cent and high off-design efficiencies are predicted for the most favourable configuration with components designed for the purpose. About half the heat input would come from the RDF and half from conventional gas turbine liquid or gas fuel. In this paper the possible alternative configurations of such a plant are discussed, the thermodynamic implications are reviewed and some typical component performance values are introduced so that the overall plant performance can be predicted.
Nuclear Power Generation in Japan—Present Status and Future Prospects
Authors: Sekine Y 
Published: February 2007

The paper outlines the present status and future prospects of nuclear power generation in Japan with emphasis on the situations peculiar to Japan. It first describes why among the many kinds of energy resources available, Japan has decided to follow a nuclear energy policy. Next presented is the current status of nuclear power generation with a brief review of nuclear power technology development. All phases of nuclear power generation from procurement of nuclear fuel to the waste disposal are covered. Social, political and technological problems that the Japanese electric power industry has to tackle in order to utilize fully nuclear energy are also discussed, together with the new technologies that will need to be developed to solve the problems effectively. As many quantitative data as possible are presented throughout the paper to provide a precise description.
Surface Roughness Model for Turning Grey Cast Iron (154 BHN)
Authors: Baradie M A El 
Published: February 2007

Computerized machinability data systems are essential for the selection of optimum cutting conditions during process planning, and they form an important component in the implementation of computer integrated manufacturing (CIM) systems. This paper presents a study of the development of a surface roughness model for turning grey cast iron (154 BHN), using tipped carbide tools under dry conditions and a constant depth of cut. The model is developed in terms of cutting speed, feedrate and nose radius of the cutting tool. These variables were investigated using design of experiments and utilization of the response surface methodology (RSM). A first-order equation covering the speed range 110–350 m/min and a second-order generation equation covering the speed range 80–495 m/min are presented. The results are given in terms of mean values with confidence intervals.
Large Electrical Machines: Powering a Business Renaissance for the Twenty-First Century
Authors: Lloyd M R , Mason M 
Published: February 2007

GEC ALSTHOM Large Machines Limited is a traditional heavy engineering company specializing in electrical machines (Fig. 1), and has successfully evolved over 90 years of operation. This historical success, however, led to a very functionalized layout of workshops and facilities totally unsuited to the present dynamic world market. Through a company-wide improvement programme the company has been restructured within the existing buildings and site to take advantage of the latest cellular technology, using numerous innovative concepts in manufacture and adoption of just in time (JIT), total quality management (TQM) and design for manufacture (DFM) concepts in a low volume manufacturing environment. The project involved the complete redesign of the factory layout, introduction of new products and equipment and concepts, resulting in dramatically improved leadtimes, inventories and sales per employee. The case study is probably unique in that the programme was executed while increasing full production and involved the adoption of techniques often only associated with volume manufacture.
CIM-OSA and Stochastic Time Petri Nets for Behavioural Modelling and Model Handling in CIM Systems Design and Building
Authors: Aguiar M W C , Weston R H 
Published: February 2007

Means are considered that can structure design and building processes associated with integrated manufacturing systems. To meet the identified needs, the paper proposes the use of an environment for executing models which adopts and extends the concepts and guidelines identified by the CIM-OSA (computer integrated manufacturing-open sytems architecture) consortium. A key component of the environment concerns the execution of models of behaviour. The paper describes (with reference to on-going implementation work) how CIM-OSA behaviour models can be represented and handled by stochastic time Petri net model execution tools. The use of the design and building environment is illustrated with reference to a case study application involving the batch manufacture of a family of electronic products. Here, the necessary form of key CIM-OSA and Petri net models are described, as are results from the Petri net simulation studies. The paper also comments on the advantages and limitations of the CIM-OSA modelling approach and how certain of those limitations are circumvented by adopting the proposed environment for model execution.
Effects of Longitudinal Vibration on the Mechanical Properties of Mild Steel Weldments
Authors: Tewari S P , Shanker A 
Published: February 2007

This paper deals with the effect of longitudinal vibration on the mechanical properties of mild steel weldments. The weldments were prepared under different frequencies and amplitudes of vibration. Experiment was carried out in the frequency and amplitude ranges of 0-400 Hz and 0-40 μm respectively. It is found that yield strength, ultimate tensile strength and hardness improves for mild steel specimens welded under vibratory conditions. It is further observed that this improvement in the mechanical properties is appreciable up to 30 μm amplitude.
A Three-Dimensional Simulation for Non-Isothermal Forging of a Steam Turbine Blade by the Thermoviscoplastic Finite Element Method
Authors: Cho J-R , Lee N-K , Yang D-Y 
Published: February 2007

The study is concerned with the three-dimensional analysis for non-isothermal forging of a steam turbine blade by the thermoviscoplastic finite element method. The analysis includes deformation of the workpiece and heat transfer of the workpiece and the die. In the transient heat-transfer analysis, the finite element method is adopted for the workpiece, while the boundary element method is adopted for the die. The non-isothermal analysis is compared with the isothermal analysis as well as with the experimental results. The length of the forged blade increases by 20 per cent as compared to the initial billet, as confirmed by the deformed configuration of both the computation and experiment. The prediction for non-isothermal forging has been shown to be in good agreement with the experimental results from forging load, temperature and geometrical configurations. It has also been shown that consideration of nonisothermal conditions renders a better prediction of forging load.
Closed-Loop Vibration Control of Flexible Rotors—An Experimental Study
Authors: Burrows C R , Keogh P S , Tasaltin R 
Published: February 2007

An experimental study has been made for the synchronous vibration control of a rotor-bearing system using a magnetic actuator to supply the control forces. Both open- and closed-loop strategies were implemented using measured displacement signals from various transducer configurations. Model reduction based on dominant mode methods was used to aid the design of the closed-loop strategies. These were based on pole placement techniques. It was shown that state feedback, without co-location of sensors and actuator, can be used to suppress critical speed responses without encountering spillover problems. The robustness of the strategies was also assessed by deleting selected feedback paths.
Operation of a Two-Motor Robot Wrist to Achieve Three-Dimensional Manoeuvres with Minimum Total Rotation
Authors: Stammers C W 
Published: February 2007

By use of a friction drive, two motors can be used alternately to reproduce a three-degree-of-freedom wrist manoeuvre. The algorithms required to achieve this are developed. In particular the efficiency of the resolution of the desired rotation is defined and simple approximations are derived for optimum operation, that is for which the total rotation required by the two motors for a given manoeuvre is minimized. Results are presented of optimum resolution for a wide range of manoeuvres. The time for calculation is also studied. Resolution time is insignificant on a mainframe computer, but for a 286 PC the approximate analysis would have to be used unless the manoeuvres were preprogrammed or a rapid response was not needed, as in a rehabilitation application.
Flow Structures and Their Relevance to Passive Scalar Transport in Fume Cupboards
Authors: Özdemir İB , Whitelaw J H , Biçen A F 
Published: February 2007

This paper describes an experimental investigation of air flow patterns and related passive scalar transport inside an open-fronted containment facility, with emphasis on the interaction with the laboratory environment. Time-averaged and instantaneous structures of the turbulent flow were examined by visualization and local measurements inside the enclosure and at the front aperture of 1200 mm × 500 mm cross-section. The cabinet was scavenged at an extract flowrate of 0.310 m3/s with 95 per cent of the air passing through the front aperture at a spatially averaged air velocity of 0.5 m/s and 5 per cent supplied through an auxiliary aperture of 1200 mm × 15 mm cross-section located at the front edge of the ceiling of the enclosure. Sulphur hexafluoride was used to mark the flow and the distributions of its time-averaged concentration over the front aperture and inside the cabinet were used to deduce the degree of mixing and passive scalar transport. The geometrical features of the cabinet provided a flow field with a spanwise vortex at the upper frontal part of the enclosure, whose cross-sectional dimension was larger close to the side walls where the velocity of the inflowing air was lower than in the central region. The spanwise vortex implemented to improve capture efficiency at low inflowing air velocities can be detrimental to the stability of the inflowing air stream along the sash handle, leading to severe leakage of the passive scalar encapsulated within the vortex itself. Without external disturbances, the leakage from the vortex occurs with the periodic bursts generated by the oscillations at the periphery of the spanwise vortex, but these oscillations become more random with the cross-draught. The structure and the orientation of the vortex were vulnerable to external disturbances in that the vortex was tilted and pushed below the sash level on one side, resulting in asymmetrical leakage.
Influence of Local Imperfections on the Collapse Strength of Domed End Closures
Authors: Blachut J , Galletly G D 
Published: February 2007

The influence of localized shape imperfections on the elastic buckling of torispheres is discussed in this paper. Perfect and imperfect injection-moulded torispheres were manufactured from ABS plastic and tested under vacuum. The models were made in five batches of thirty and all had the same basic geometry. One series was near-perfect and the other four had single localized increased-radius (‘flat patch’) imperfections in them. The centres of the imperfections were all located 12° from the axis of symmetry and the four series differed only in the size of the imperfection. This specific positioning of the imperfection was influenced by some unusual results which were published recently (1). The agreement between the experimental results and the numerical predictions, based on the BOSOR 4 and ABAQUS codes, was very good. In particular, the validity of the lower-bound curve of collapse pressure versus size of the imperfection was confirmed experimentally. The predicted buckling strength was also not influenced by the location of the flattening (that is whether on-axis or 12° off-axis) and the numerical results were confirmed by experiment. A finite element case study of an imperfect hemisphere with an on-axis and a 12° off-axis flat patch was also carried out. Once again, the location of the localized imperfection did not affect the buckling strength of the shell. This finding is at variance with a prediction made recently by other investigators of this problem.
Robotic Peg-Hole Insertion Operations using a Six-Component Force Sensor
Authors: Qiao H , Dalay B S , Parkin R M 
Published: February 2007

Peg-hole insertion is a widely used industrial robot process. For precise insertion it is common to use force sensors to obtain the deviation between the peg and the hole. In this paper, several examples of six-component force sensors, which are designed to measure the forces and torques in all directions, are reviewed. The problem of how to obtain the deviation between the peg and the hole from the measurement of the forces and the torques exerted on the sensors is then discussed. It is shown that the angle between the peg and the hole and the roughness of the contact surfaces (the end surface of the peg and the surface surrounding the hole) would significantly influence the identification of deviation, no matter how small they are. Two measures to address these phenomena are introduced. A novel strategy of the high-precision chamferless peg-hole insertion with a wrist force sensor is presented and verified experimentally. This strategy is constructed: to obtain the relationship between the peg and hole from the force sensor signal when angular misalignment and the defects of the contact surfaces are present to reduce the angular and lateral errors and to achieve precise chamferless robotic peg-hole insertion. In this paper, it is shown that the insertion can be effected with a reasonably large range of initial conditions. The principle is to move and rotate the peg from an area having many geometric uncertainties to a new area, where the deviation of the peg and hole can be obtained.
Kinematic Synthesis of RRSS Spatial Motion Generators using Euler Parameters and Quaternion Algebra
Authors: Lee K-W , Yoon Y-S 
Published: February 2007

This study proposes a new method using Euler parameters and quaternion algebra for the kinematic synthesis of an RRSS spatial motion generator. The proposed method is compared with the other method using rotation angles for two-position and three-position motion guide problems. It is found that the proposed method provides solutions better in most cases tested here because the synthesis equations in the method include no trigonometric functions. The solutions converge more easily than in the other method as well as avoiding rotational singularity problems encountered otherwise.