bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Matrix of Confusion—a Classification of Robot Movement
Authors: Morley E C , Wilson J R 
Published: February 2007

The human-machine interface for robots has received only limited attention as robots have developed. Most research has focused on the design of teach pendants, hand-held devices for programming and manual motion control. Results from these studies have been generally inconclusive as to the best control design for teach pendants. In a fresh approach to the area, the human-robot interface has been analysed. This has resulted in the development of a method of classifying robot movements called the ‘matrix of confusion’. The classification shows the robot motions an operator would see when using a given control for a unique combination of operator position, robot position, programming mode and robot configuration. The use of the matrix has helped to highlight the most important factors in the task of manual motion control of the robot. This has helped in the development of a new motion system for a PUMA robot which is currently being tested in comparative trials.
A Sensing Technique for the Measurement of Tactile Forces in the Gripping of Dough-Like Materials
Authors: Stone R S W , Brett P N 
Published: February 2007

This paper describes a tactile sensing technique that is devised for applications concerned with the control of the active gripping of deformable compact shaped non-rigid materials. The sensor uses measurements of thin aluminium plate deformation to determine a close representation of the force distribution applied to the surface of the workpiece and can be used to indicate deformation and slip of soft materials under the action of gripping forces. Two methods of operation are described along with the results of each of these implementations. The first method utilizes a model of the sensor mechanical structure to interpret the sensory data from the deformed shape created by the applied force of the object on the sensor surface. The second method relies on an algorithm for comparing theoretical and measured bending moments to achieve the force distribution that provides close agreement between these two entities. In this case the theoretical moment is adjusted by manipulation of the parameters used in the expression describing the force distribution.
Towards a Comparative Study of Quarter-Turn Pneumatic Valve Actuators
Authors: French M , Ramìrez A C 
Published: February 2007

Comparative design studies are potentially a valuable source of design knowledge, surveying as they do the work of many designers in many companies and incorporating the judgement of the market-place. Quarter-turn pneumatic valve actuators are a good product to study, as they are small and self-contained and used in large numbers, and there are many makers (many more even than were expected). Experimental tests were made on nineteen designs. Criteria for comparison were found, and applied, measuring efficiency, matching and compactness. Some explanation of the diversity of designs was found in niches in the market, for example for different valve types and applications. Historical trends have generally been to greater refinement. Some function costs are given. The industry has shown serious interest in this work.
Thermal Investigation of a Honing Process Utilizing Polyborosiloxane Impregnated with Abrasive Particles
Authors: Fioravanti A , Fletcher A J 
Published: February 2007

A novel honing and polishing process utilizes polyborosiloxane impregnated with a range of abrasives in particulate form, to polish mould cavities of complex geometry. The polymer, which deforms in such a way as to allow complete coverage of the target surface, is used to carry the abrasive. This compound is agitated using an ultrasonic source and is made to flow relative to the target surface. The process causes heating of the various components in the system. This is the second paper concerned with the prediction of the resultant temperature distributions. The work reported here is an extension of the previous work to take into account the complex geometry of the multi-component system used in the operation. Furthermore, the development of the honing process required the introduction of flow of polishing compound relative to the workpiece. As a result the previous work has been extended to take into account the thermal effects of this flow. The modelling work has been complemented by measurement of temperatures in a geometry that is representative of the processing requirements. The calculated and measured results have been compared and the model validated accordingly.
Three-Dimensional Flow Measurements in Conical and Straight Wall Centrifugal Compressor Vaneless Diffusers
Authors: Pinarbasi A , Johnson M W 
Published: February 2007

In the current work three-dimensional flow measurements in two types of centrifugal compressor vaneless diffuser were obtained using hot wire anemometry. The first diffuser was conical, designed to give a constant flow area, while the second straight wall diffuser had a constant axial width. Measurements of mean velocity, flow angle and velocity fluctuation level were obtained on eight cross-sectional planes in each diffuser. The jet-wake flow pattern and the impeller blade wakes are clearly visible at the inlet of both diffusers. Mixing out of the blade wake proceeds more rapidly in the straight diffuser. The hub boundary layer also develops more rapidly in this diffuser because of the adverse pressure gradient. Velocity fluctuation level measurements highlight the mixing regions within the diffusers. Recommendations are also made for the design of vaned diffusers. A larger vaneless space would be required with a straight wall diffuser and significant twisting of the vane would be required for both diffuser geometries if significant incidence losses are to be avoided.
An Experimental Study of the Mean Flow and Turbulence Structure Of Cross-Flow Over Tube Bundles
Authors: Balabani S , Yianneskis M 
Published: February 2007

The velocity characteristics of cross-flow over tube bundles were investigated in a water tunnel. Three tube arrays with a transverse pitch ratio of 3.6 were studied: an in-line and two staggered arrays with longitudinal pitch ratios of 2.1, 1.6 and 2.1 respectively. The mean velocities, turbulence levels, spectra, time and length scales and dissipation rates were determined from ensemble-averaged and time-resolved laser Doppler anemometry (LDA) measurements. The pressure drop across the bundles was also measured. The staggered arrays were found to generate higher levels of turbulence and a higher pressure drop. Turbulence kinetic energy reaches a maximum downstream of the second row in staggered arrays. The wake regions in both geometries are anisotropic with transverse r.m.s. velocities being higher than axial ones. Increasing the longitudinal spacing in the staggered configuration results in lower r.m.s. levels in the wakes and alteration of the recirculation characteristics. A discrete periodicity with a Strouhal number of 0.26 was identified in the 3.6 times 1.6 staggered array which is associated with vortex shedding. Turbulence scales and dissipation rates were estimated and compared with numerical predictions.
Statistical Mechanics Material Model for the Constitutive Modelling of Elastomeric Compounds
Authors: Allport J M , Day A J 
Published: February 2007

Material models for the finite element analysis (FEA) of polymeric and elastomeric compounds are only available in limited form in most commercial finite element (FE) packages. The most common are the phenomenological Mooney-Rivlin and the Ogden models, for which the constants bear no relationship to the physical or chemical characteristics of the rubber and their derivation is difficult. Both models are limited in their accuracy for filled rubbers used in combined states of tensile and compressive deformation, and since these are common operational conditions for engineering components such as drive couplings, engine mounts and torsional vibration dampers, their use in engineering analyses is restricted. In this paper a statistical mechanics material modelling approach for synthetic, filled elastomeric compounds in FEA is presented. Using styrene-butadiene rubber (SBR) as an example, the theory and its application in the commercially available ABAQUS finite element analysis program is explained. FE models of tensile and compressive specimens in two and three dimensions are used to demonstrate the use of the model, and results are presented, discussed and compared with measured data. Good correlation in both tension and compression is demonstrated. A practical application of the model to the SBR blocks in a Holset torsional drive coupling is presented; this analysis involves complex issues of mesh design and contact modelling. The results show good agreement with measured performance, and clearly demonstrate how this type of material modelling approach can be effectively used in the computer aided engineering and design of engineering rubber components.
Couette Flow Heat Loss Model for the Rotary Combustion Engine
Authors: Gorla R S R , Bartrand T A 
Published: February 2007

A novel model for predicting heat transfer in a rotary engine was formulated and implemented in a zero-dimensional engine performance model. Results were compared with a commonly used intermittent combustion engine heat transfer model and with results from a three-dimensional simulation of flow within a rotary engine. When squish effects associated with fluid motion within the chamber were included, the Couette flow model reproduced peak heat transfer rates and timing for the peak heat transfer rate was better than that of the commonly used heat transfer model. Previously, rotary engine performance models have employed flat plate type heat transfer correlations. These correlations, though useful, do not model the flow physics in the rotary engine faithfully. Rather than flow over a flat plate, flow in the rotary engine was approximated as turbulent Couette flow. The Couette model was altered to account for centre-line velocities higher than half the rotor speed. There are two advantages to using the Couette flow model. Firstly, as noted, the underlying physics of the Couette flow model is closer to conditions in the rotary engine. Secondly, with the Couette flow model it is possible to differentiate between the rotor and housing heat transfer coefficients.
Particle Image Velocimetry Measurements of In-Cylinder Flow in a Multi-Valve Internal Combustion Engine
Authors: Reeves M , Garner C P , Dent J C , Halliwell N A 
Published: February 2007

Particle image velocimetry (PIV) has been used here to characterize the formation and breakdown of barrel swirl or tumble in a production geometry, four-stroke, four-valve motored optical internal combustion (IC) engine. The engine was motored at 1000 r/min at wide open throttle. Double exposed images were recorded from a plane parallel to the cylinder axis which passed through the centre-lines of an inlet and exhaust valve. Particle image velocimetry images from a range of crank angles between inlet valve closure and the ignition point were interrogated by digital autocorrelation to give two-dimensional maps of instantaneous velocity. The in-cylinder flow is characterized by the formation of an ordered barrel swirl or tumbling vortex, which is shown to persist throughout the majority of the compression stroke with maximum velocities of the order of three times the mean piston speed and a high velocity bulk flow at the time of ignition near the spark plug. With respect to the PIV technique itself, image labelling and cross correlation are considered essential to improve measurement dynamic range, valid data rate and tolerance to velocity gradients in the turbulent flows encountered near top dead centre (TDC).
Truck Suspension Design to Minimize Road Damage
Authors: Cole D J , Cebon D 
Published: February 2007

The objective of the work described in this paper is to establish guidelines for the design of passive suspensions that cause minimum road damage. An efficient procedure for calculating a realistic measure of road damage (the 95th percentile aggregate fourth power force) in the frequency domain is derived. Simple models of truck vibration are then used to examine the influence of suspension parameters on this road damage criterion and to select optimal values. It is found that to minimize road damage a suspension should have stiffness about one fifth of current air suspensions and damping up to twice that typically provided. The use of an anti-roll bar allows a high roll-over threshold without increasing road damage. It is thought that optimization in the pitch-plane should exclude correlation between the axles, to ensure that the optimized suspension parameters are robust to payload and speed changes. A three-dimensional ‘whole-vehicle’ model of an air suspended articulated vehicle is validated against measured tyre force histories. Optimizing the suspension stiffness and damping results in a 5.8 per cent reduction in road damage by the whole vehicle (averaged over three speeds). This compares with a 40 per cent reduction if the dynamic components of the tyre forces are eliminated completely.
An Experimental Study of a Fluidic Type Fuel Injector in Comparison With a Solenoid Type Injector
Authors: Huang Q , Sansum D P 
Published: February 2007

An experimental study of a fluidic type fuel injector for spark ignition (SI) engines is described in this paper. The fluidic injector unit consists of four monostable fluidic devices controlled by a solenoid interface and air–fuel mixing nozzles for better fuel atomization. The prototype fluidic injector unit was implemented on a research engine. The results of air–fuel ratio (AFR) variations, engine combustion characteristics and exhaust emissions from the fluidic injector were compared with those from a baseline solenoid type injector. It was demonstrated from single cylinder engine tests that the fluidic system produces 9 to 20 per cent lower hydrocarbon (HC) emissions and 5 to 8 per cent higher indicated mean effective pressure (IMEP) than the baseline injection system. This has confirmed the effectiveness of the use of air-assisted fluidic injectors and the fact that improved mixture preparation and better fuel presentation are obtained by the fluidic injector. However, the lean misfire limit by the fluidic injector is reduced by 1 AFR compared to that of the solenoid injector due to large AFR dispersions caused by cyclic fuel delivery variations of the fluidic device. It is envisaged that the fluidic injector potentially offers cost and emission benefits for SI engines when the cyclic flow stability is improved.
The Transmission of Vibration to the Occupants of a Car Seat with a Suspended Back-Rest
Authors: Lewis C H , Griffin M J 
Published: February 2007

A new type of car seat has been designed in which the back-rest is able to move freely in the vertical direction. The design allows the back-rest to follow the vertical vibration of the back of an occupant of the seat. This is intended to decrease any strain on the lumbar part of the spinal column caused by a different vertical motion at the seat squab and the seat back. The transmission of vertical (z axis) vibration from the base of this seat to the seat surface, to the back-rest and to the backs and heads of seat occupants has been measured. Measurements were made with the seat back fixed, to prevent vertical motion relative to the seat frame, and with the seat back free to move. Vibration transmissibilities from the seat base to the seat surface were characterized by a resonance at frequencies in the region of 4 Hz. The resonance frequencies were slightly higher with the fixed back-rest than with the moving back-rest. The transmissibilities at frequencies above 4 Hz were generally higher with the fixed back-rest. Measurements with no contact between the seat occupants and the seat back indicated that the dynamic properties of the human body and the seat cushion were less influenced by the moving seat back than by the fixed seat back. Differential motion between the seat surface and seat back was smaller with the moving seat back than with the fixed back.
An Investigation of Combustion Chamber Shapes for Small Automotive Direct Injection Diesel Engines Employing Spray Impaction
Authors: Park K , Watkins A P 
Published: February 2007

In modern compact combustion chambers of direct injection diesel engines with high-speed injection spray, the impaction of the spray on the wall is almost inevitable. This may result in high levels of unburnt hydrocarbons. However, a number of combustion systems have been developed which deliberately employ wall impaction as a means of breaking up the fuel spray and/or directing it in a desired direction. These include chambers which employ impaction sites attached to the cylinder head or a cut-off pip in the piston bowl centre. A further type of geometry, which has been the subject of an earlier investigation by the authors, is presented here, in which cut-off pips are provided for a number of sprays directed not only straight down into the combustion chamber centre but also across and down into the bowl in the normal radial direction. For the current analysis, the sizes of the pips and their positions are based on the previous work. All these cases are investigated using a computation fluid dynamics code employing non-orthogonal grid systems, the k–epsis; turbulence model, the implicit PISO {pressure implicit by splitting of operators) solution scheme, and the discrete droplet model for the sprays. Comparisons of simulations with relevant experimental data show that the code returns good qualitative and quantitative results. Apparently good qualitative results are also returned for a number of the combustion chambers employing impaction sites attached to the combustion head and in the centre of the piston bowl. Simulations of combustion chambers employing a number of impaction sites around the piston bowl indicate the likely advantages of such a system over a conventional highly swirled one.
Diesel Injector Dynamic Modelling and Estimation of Injection Parameters from Impact Response Part 1: Modelling and Analysis of Injector Impacts
Authors: Gu F , Ball A D 
Published: February 2007

Part 1 of this paper presents the development and validation of a detailed dynamic model for the needle motion of a common hole-type dieselfuel injector as used in a direct injection diesel engine. The injector needle motion is described as a two-mass piece-wise linear vibro-impact system, unlike the conventional modelling techniques which use a single-mass approach. The use of two masses permits analysis of both the needle impact behaviour and of the more general dynamics of the fuel injection process. Model parameters are derived from a combination of measurement and estimation, and the subsequent model is evaluated via direct measurement of the spring seat displacement. The opening and closing needle impact behaviour is shown to exhibit close correlation with key injection parameters, including fuel injection pressure, fuelling rate and timing. The model revealed that the impact of the needle when opening is found to exhibit lower amplitude but more high-frequency components than the impact associated with the closing. The measurement of the injector body vibration response to these impacts is shown to enable non-intrusive estimation of injection parameters, alleviating the problems associated with conventional intrusive needle-lift measurement.
Current Issues and Technologies for the Reassessment of Existing Offshore Installations
Authors: Billington C J , Bolt H M 
Published: February 2007

The statutory requirement to prepare safety cases for United Kingdom offshore platforms following the Piper Alpha disaster, the extensive damage to offshore platforms in the Gulf of Mexico caused by Hurricane Andrew and the desire to extend the operational life of hydrocarbon production platforms throughout the world has led to several important industry initiatives concerning requalification and reassessment of offshore platforms. This paper describes the development of a new industry reassessment guideline document, the philosophy within the guidelines and the technologies available for reassessment. In particular, the availability of validated non-linear system ultimate strength collapse analysis computer software is revolutionizing the reassessment process by being able to take advantage of the system reserve and residual strength above the individual component design capacity level. However, there are problems in the application of these advanced techniques and there are several generic issues concerning acceptable levels of risk, the scope and methodology of reassessment and the development of international standards for reassessment. The paper draws out these issues and describes industry initiatives that are working towards their resolution.
Aerodynamic Drag on Trains in Tunnels Part 2: Prediction and Validation
Authors: Vardy A E 
Published: February 2007

The principal sources of aerodynamic drag on simple trains in tunnels are (a) surface skin friction and (b) stagnation pressure losses at the nose and tail. On sufficiently long trains, the first of these is dominant. On shorter trains, local losses can be more important. This paper seeks to provide a theoretical basis for predictions of the dependence of drag on the train/tunnel blockage ratio, attention being given to tunnel resistance as well as to train resistance. Hitherto, most predictions have relied on empirical formulae. It is shown that the train skin friction coefficient varies approximately linearly with the blockage ratio, βz. The dependence increases with increasing train roughness. The nose loss coefficient kN is shown to be smaller than 0.1 for reasonably streamlined noses. An approximate relationship between kN and βz is hypothesized. The tail loss coefficient kT is shown to be approximately equal to β2z for poorly streamlined tails. A tail shape coefficient is introduced for use with more streamlined tails.
Failure Detection and Location Using Residual Difference Generation Detection Filters
Authors: Martin K F , Moavenian M 
Published: February 2007

The paper describes a theoretical investigation of failure detection using a new type of filter. The latter, called a residual difference generation detection filter, is based upon using (a) a main detection filter and (b) a faulty parameter modifier. Both of these use a reference model of the system; this is a mathematical model of the system without faults. In (a) the reference model is used in parallel with the real system in order to generate residuals (functions of differences between the real system and the reference model); in (b) the reference model is used in parallel with another mathematical model of the system which contains a known fault which again generates residuals that are a function of the known fault. By analysing these residuals while changing the known fault in (b) it is possible to detect which fault is occurring. The technique is applied to faults in a servo-motor, faults being assumed to occur singly. Tests were carried out using a mathematical model of the real system which incorporated an ‘unknown’ fault.