bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation of the Effective Parametric Errors in Coordinate Measuring Machines Using the Locus of Stylus on the Horizontal Plane
Authors: Pahk H J , Burdekin M
Published: February 2007

A new method is proposed for the evaluation of effective parametric errors in three-axis coordinate measuring machines (CMMs), using the locus of stylus of the measuring probe on an ideal horizontal plane. The CMM base, which is mostly made of granite or steel, can be used as a good reference surface for obtaining the locus of stylus of the CMM probe, after the flatness calibration has been performed. Rectangular grid measurement with electronic level has been applied for the flatness measurement, then analysed either by the least squares technique or by the minimum separation technique. The CMM probe was moved and took the reading (vertical scale coordinates) on the corresponding grid points on the precalibrated base, giving the base probing data. The discrepancy data between the flatness and the base probing data become the locus of stylus, which is to be processed to give a mean plane plus the deviation data. The mean plane is called the locus plane which is the metrological reference plane for a specific machine, the deviation data (called the error of the locus of stylus) indicate a unique error feature of the specific machine in the vertical direction. This error of the locus of stylus can be decomposed into three effective parametric error components such as vertical straightness errors of the horizontal axes, and the roll error of a horizontal axis. As the parametric errors are evaluated in the effective sense, this technique can be applied to the modern CMMs which have a software compensation scheme, which is the advantage over the conventional parametric error method. Two cases of ‘on site’ calibrations have been shown in order to demonstate the efficiency and validity of the developed method. The computer aided feature is fully achieved, so that the data acquisition, analysis, and representation are performed on line with the aid of a microcomputer (IBM/PC/XT/AT compatible).
Japanese Total Quality Control: A Study of Best Practice
Authors: Dale B G , Tidd J
Published: February 2007

This paper reports the main findings of a mission to Japan to study total quality control (TQC) best practice in manufacturing industry. The manner in which the Japanese companies manage TQC is impressive; however, there are a number of outstanding features including: their planning for improvement is second to none, from publication of the President's policy and its deployment through all levels of the organizational hierarchy and the visual display of what is required from each section of every manufacturing division in order to achieve specific improvement goals; top management are totally committed to TQC and are involved in planning, auditing improvement, motivating their people, cross-functional teams and committees, and taking a personal interest in TQC education and training; there is total dedication and attention to detail in all aspects of quality assurance and quality improvement from listening to the ‘voice of customers’ to daily control of routine activities—no effort appears to be spared by each employee in analysing the reasons for quality troubles and putting into place countermeasures to prevent their reoccurrence; and the considerable resources that are committed to training employees from President to line operator in TQC principles, procedures and tools and techniques. It is also pointed out that numerous means are used to involve employees in quality improvement activities.
Transient Brake Temperatures Found by use of Analytical Solutions for Finite Hollow Cylinders
Authors: Fermér M , Lundén R
Published: February 2007

A linear analytical model for calculating transient axisymmetric temperature distributions in finite hollow cylinders is established and adapted for practical use. A homogeneous isotropic material with temperature-independent thermal properties is assumed. Among possible applications are brake discs, brake drums and block braked railway wheels. The thermal power from braking is applied as prescribed heat influxes over parts of the lateral and radial surfaces of the cylinder. Bessel series solutions to the heat conduction equation are found where Newton's law for heat transfer is used in the boundary conditions. In addition to convection prescribed surface temperatures and insulated surfaces are also studied. Arbitrary thermal loading histories are treated by use of Duhamel's principle where step loadings are superposed. Convergence and limitations of the method and required computer times are discussed. Calculated numerical results for some typical braking operations are compared with those of other studies.
Response of Bulk Flowmeters to Multiphase Flows
Authors: Baker Roger C
Published: February 2007

This review has attempted to select the most recent references with the most useful data. It does not cover local velocity measurements or related parametric measurements. The nature of multiphase and multi-component flow is briefly considered. Data on existing flowmeter designs in two-component flow suggest that the most likely contenders for fiscal measurement precision are venturi, positive displacement, electromagnetic and correlation flowmeters. There are inadequate data so far to determine the eventual usefulness of the Coriolis mass flowmeter.

Flowmeter combinations of volume and momentum sensing have been used to deduce mass flow, as have combinations of volume flowmeter and densitometer. Major systems under development incorporate many sensors to measure both combined and separated flows.

The discussion section seeks to give a general insight into the topic and the associated problems by identifying common themes across a number of meters. Various topics are discussed which relate to the problem of precise multi-component flow measurement: what to measure; gas entrapment; ancillary equipment; dynamic modelling; damage; physical effects; whether to separate the components; the need for calibration.

The review concludes by identifying future areas where academe and industry can contribute, particularly if they do so collaboratively.
An Experimental and Numerical Investigation into the Thermal Behaviour of a Three-Lobe Profile Bore Bearing
Authors: Gethin D T , Basri S B
Published: February 2007

A combined experimental and numerical investigation into the thermal behaviour and its consequent effect on the performance of a three-lobe profile bore bearing is presented. Symmetric and tilted geometries are studied and the results show that loading direction has a significant effect on the thermal behaviour, but has little impact on the lubricant requirements and torque reactions in the bearing. The comparison between the numerical model and experiment shows very good correlation which supports the application of the numerical approach in the design role.
Blockage Effects on Cavitation Inception Characteristics of Bluff Bodies
Authors: Balachandar R , Ramamurthy A S
Published: February 2007

The study deals with the prediction of cavitation inception in the wake of two-dimensional bluff bodies subject to wall interference effects. Corrections are included in the model to account for flow entrainment effects and loss of circulation in the vortices shed from the bluff body. Experimental results are also presented to verify the proposed model over a range of blockages.
Intimate Thermodynamic Design of the Stirling Engine Gas Circuit without the Computer
Authors: Organ A J
Published: February 2007

Thermodynamic similarity conditions are cited for the gas circuit of the Stirling machine. Charts or a hand calculator become the only tools required for the design of a new machine to the detail previously calling for sophisticated software. Independent corroboration is presented.
Optimum Structural Design of Internal Combustion Engine Systems by Branch-and-Bound Algorithm
Authors: Wang W G , Mucino V H , Smith J E
Published: February 2007

This paper develops an alternative optimization approach for systematic design of a parametrized engine system and illustrates the procedure through application to a novel conversion device, the patented Stiller-Smith mechanism (1, 2). Using simultaneous interplay between a simulation scheme, presented in detail elsewhere (3), and an optimization scheme, the proposed structural design process integrates the multiple objectives of structural design. Developed here in detail, optimization involves intermediate continuous optimization via a penalty function method, and integer or discrete programming through the branch-and-bound algorithm. The ensuing application illustrates the approach by optimizing a 16-cylinder Stiller-Smith engine for minimum weight-power and dimensions-power ratios under several types of constraints. In the context of a multi-objective constrained non-linear programming problem, the design example proceeds through three stages: (a) preliminary, in which the designer applies the simulation scheme to obtain the system response variables from the design requirements to reflect trade-off relationships among multiple design objectives; (b) secondary, the intermediate continuous optimal design stage, in which a penalty function method is used to specify constraints within a general range to allow variation in the choice of parameters; and (c) final, in which the branch-and-bound algorithm constrains integer variables to take integer values and discrete variables to take discrete values, thereby arriving at an optimal design.
Estimation of Rollover Threshold of Partially Filled Tank Trucks
Authors: Rakheja S
Published: February 2007

A simple methodology to estimate static rollover threshold of trucks and tractor-semitrailers, equipped with a partially filled clean-bore cylindrical tank, is presented. Lateral liquid load transfer is determined as a function of fill level, tank geometry, roll angle of the sprung mass and lateral acceleration. The static rollover threshold is then estimated by balancing the total overturning moment against the restoring moment. Results are compared to those obtained from software based on comprehensive kineto-static analysis of tank vehicles.
Belt Tensioning Procedures on IC Engines
Authors: Fawcett J N , Burdess J S
Published: February 2007

The tension in auxiliary and camshaft drive belts is set during assembly of the engine. Repeatable and accurately known tensions are required to ensure long life and low noise levels. Experimental results, based on tests carried out on two engines, show how setting procedure, pulley tolerances and creep can affect the long-term values of belt tension. The importance of careful design of tension-adjusting systems is emphasized.
Thermal Effects and Pressure Distributions in Brakes
Authors: Day A J , Tirovic M , Newcomb T P
Published: February 2007

Heat generated at the sliding interface between the friction material and the mating surface of a friction brake is not uniformly distributed over the sliding surfaces but depends upon the local interface pressure. Many thermal problems associated with brake friction pairs, including performance variation (fade, speed sensitivity) and rotor damage (heat spotting and thermal cracking) can be analysed in terms of localized frictional heat generation as discussed here.

This paper describes how the thermal effects of interface pressure distribution may be divided into bulk temperature effects, such as brake drum expansion and brake disc coning, and its macroscopic thermal effects, such as heat spotting, and suggests how the two are related through the process of thermoelastic instability. The results of analyses, using finite element methods, indicate that uniform friction interface pressure is very important in minimizing brake thermal problems. However, more basic research in the area of interface contact and pressure distribution, and frictional heat generation and dissipation, still remains to be done in order to understand fully the role played by each part of the friction pair in thermally related braking problems.
A Note on the Design of Air Springs
Authors: Agnew B
Published: February 2007

The geometry of the shell of an air spring is examined and it is shown that it can be described in a plane of symmetry by the following equation cast in the XY plane:

The error in calculating the stress in the shell, assuming it to be of spherical form, is determined and it is shown that the error can be small if care is taken with the geometric design of the spring.
Gas Through the Looking Glass—An Engineer Reflects
Authors: Rooke Sir Denis
Published: February 2007

This paper gives an overview of developments in the gas industry over the last half-century.
A Lightweight Hydrocarbon Sample Vessel
Authors: Murphy P V
Published: February 2007

Existing stainless steel hydrocarbon sample vessels were heavy and sometimes suffered corrosion problems. There was a need to redesign in an alternative material that would meet the requirements for pressure, temperature, weight, corrosion resistance, availability and cost.

A materials survey led to titanium 318 being chosen. The redesign took full account of the different properties of the new material, particularly its relatively low stiffness.

Following detailed discussions with the material supplier and the manufacturer, prototype vessels were designed, manufactured and tested successfully. This led to the production of many more sample vessels, and an increased use of titanium 318 for other pressure vessels.
Multi-Thermocouple Probes for Temperature Prediction in the Process Industries
Authors: Brett P N , Moore J M
Published: February 2007

In short-cycle batch production processes difficulties are experienced in the direct measurement of temperature in high-viscosity fluid mixing environments. There is often a need to penetrate high shear flows with the sensor to ensure that measurements representative of bulk temperature are obtained. Significant measurement errors are experienced due to the temperature differential between the bulk of the fluid and the surface of the probe. The resulting strength requirements of probe supporting structures also contribute errors as a result of additional heat capacity and additional heat conduction paths from the sensors. This paper presents research towards the design of a multi-sensor probe integrated with computational algorithms devised to reduce these effects. Initial trials demonstrate that such schemes can be applied to reduce steady state errors and to improve response times over existing measuring devices.
The new Pressure Systems and Transportable Gas Containers Regulations: Part 1: Inspection Procedures to Meet the Regulations
Authors: Towndrow R F R , Groome R D
Published: February 2007

In preparation for the coming into force of the Pressure Systems and Transportable Gas Containers Regulations (1989), two Seminars were sponsored in May and June 1990 by the Process Industries Division, North West Centre, and the Pressure Systems Group of the Institution of Mechanical Engineers.

New ground is broken in the Regulations in the primary duty of compliance being placed on the users of fixed pressurized systems.

Mr Towndrow's paper (Part 1) describes already proven engineering management and control procedures that meet the user's new responsibilities and outlines further changes required during the four year lead-in programme.

The scope of the legislation for gas cylinders has been greatly extended in variety, size and new technology. Dr Irani's paper (Part 2) traces the improvement in cylinders, and draws attention to new procedures on filling, rerating and repairs. He demonstrates the contribution of British Standards to gas cylinder development and anticipates the Regulations forming a valuable input to the proposed European Directive currently being drafted.

The Pressure Systems and Transportable Gas Containers Regulations (1989) provide a legal framework for many of the existing voluntary procedures in the process industries. The presentation outlines how ICI's inspection procedures have evolved in recent years, and how they will be able to meet the requirements of the new legislation. While designed primarily for an in-house inspection organization, they are also applicable where a third party inspectorate provides the inspection service to particular works.
Problems in Developing Process Machinery
Authors: Bergwerk W
Published: February 2007

The development of process machinery poses certain special problems which are additional to those normally encountered in engineering development. In industries as widely different as oil refining, textiles, or agriculture, the equipment suppliers must all link into a lengthy process chain, they must deal with the question of process material spoilt during experimental work and they have to resolve the problem of the ownership of design know-how arising from operating experience gained by the processor. These problems have a significant influence on the development strategies adopted in different industries. On technical matters it is usual to try to isolate the machine from the process chain by using specification parameters. Five levels of abstraction in defining the parameters are described. On the commercial side the relationship between the manufacturer of the machine and the company operating the process must be established in unambiguous terms at the outset. Depending on the degree to which the machine manufacturer can later accept responsibility for some processes matters, various arrangements can be agreed for the future development of the machine and process and for the running of plant trials.
Shot and Bead Peening Control
Authors: John R
Published: February 2007

This paper discusses the merits of the peening effect in improving the fatigue resistance of compounds and looks at machines that perform the task. There is a lack of information about the process but now a significant increase in studies dealing with peening is helping to overcome problems.
Intervertebral Motion during Vibration
Authors: Pope M H , Kaigle A M , Magnusson M , Broman H , Hansson T
Published: February 2007

Vibration exposure is widely recognized as a risk factor for low back pain. An experimental protocol was designed to quantify the intervertebral motion response in human subjects to sinusoidal vertical vibration at 5 and 8 Hz, and at a variety of acceleration levels. Intervertebral motion in the mid-sagittal plane was measured using a transducer linkage system attached to pins placed directly into the spinous processes of adjacent vertebrae. The postures of the subjects were carefully controlled. The effects of forward flexion, arm support, gravitational load, and sitting on a cushion were evaluated. The rigid body motion of the superior vertebra with respect to the inferior vertebra was expressed in terms of relative sagittal plane rotation, axial translation, and anterior-posterior shear translation. It was found that the lumbar motion segments exhibited coupled periodic behaviour in response to sinusoidal vertical vibration, with up to 1 mm peak-to-peak displacement in the axial direction. The greatest intervertebral motion occurred when the subject was exposed to 5 Hz vibration as compared to 8 Hz. For a constant frequency of 5 Hz excitation, the peak-to-peak amplitudes of the computed motions tended to increase as the acceleration level increased. In the flexed posture, with no arm support, the active trunk musculature helped reduce the intervertebral motion. Additional gravitational load on the shoulders caused increased relative axial displacement. A polyethylene foam cushion placed on the seat reduced vibration transmission at 5 Hz excitation and consequently decreased the intervertebral motion.
Design Considerations for Cushion Form Bearings in Artificial Hip Joints
Authors: Dowson D , Fisher J , Jin Z M , Auger D D , Jobbins B
Published: February 2007

Lubrication mechanisms and contact mechanics have been analysed in a new generation of ‘cushion form’ bearings for artificial hip joints, which comprise low elastic modulus layers on the articulating surfaces. Comparisons have been made with ‘ hard’ bearings used in existing prostheses and also with the natural hip joint. Lubricating film thicknesses are enhanced by larger contact areas and lower contact pressures. For a fixed contact area, simultaneous changes in layer thickness and radial clearance have been shown to have a small effect on elastohydrodynamic film thickness. Hard bearings designed with the same contact area as the cushion bearings produced a similar film thickness, but lubricant film thickness is not optimized in current designs. The main advantage of using a cushion bearing with low elastic modulus layers was found to be associated with microelastohydrodynamic lubrication. Careful selection of the elastic modulus is important in order to ensure that this lubrication regime was effective. Low elastic modulus layers may also produce local deformations, which enhance squeeze film action. The elastic modulus of the material should not be lower than necessary to produce effective microelastohydrodynamic lubrication, as a further reduction in modulus only increases the strain distribution in the material. A lubricant film thickness of 0.3 μm has been predicted for a cushion hip prosthesis with a femoral head diameter of 32 mm and radius of contact zone of 16 mm, using a 2 mm thick layer with an elastic modulus of 20 MPa.
A New Technique for Measuring Contact Areas in Human Joints—The ‘3S Technique’
Authors: Yao J Q , Seedhom B B
Published: February 2007

The need for estimating average stresses acting in human joints has prompted the measurement of contact areas. Various existing methods predict contact areas much larger than the actual ones occurring in vivo. This discrepancy is due to the inevitable flow of the interstitial water of articular cartilage in the form of creep deformation. Some of the tests are also too complicated and time consuming for them to be suitable for tests where a large body of data are to be collected. In this report, the authors present a new technique of indicating contact areas occurring in human synovial joints. The new technique employs silicone oil-carbon black powder suspension which is applied to one of the contact surfaces. The suspension is squeezed out of the contact area on applying the load leaving the contact area clearly indicated and possible to record photographically. This Silicone oil-carbon black powder Suspension Squeeze technique (the ‘3S technique’ in short) has been validated and compared with another technique which is equally accurate but cannot be used in human joints. The technique the authors developed is simple, quick and allows accurate measurements of contact areas under physiological conditions with ease. Also, it leaves no permanent staining on cartilage surfaces and so allows one to repeat the test on the same joint under different loads and flexion angles of the joint. As an example, the change of contact areas in a tibio-talar joint during a normal level walking cycle is shown, which can be used to show the variation of the contact stress level at various instances within a walking cycle.
Tribology of Total Artificial Joints
Authors: Fisher J , Dowson D
Published: February 2007

The tribology of total artificial replacement joints is reviewed. The majority of prostheses currently implanted comprise a hard metallic component which articulates on ultra high molecular weight polyethylene surface. These relatively hard bearing surfaces operate with a mixed or boundary lubrication regime, which results in wear and wear debris from the ultra high molecular weight polyethylene surface. This debris can contribute to loosening and ultimate failure of the prostheses. The tribological performance of these joints has been considered and a number of factors which may contribute to increased wear rates have been identified. Cushion bearing surfaces consisting of low elastic modulus materials which can articulate with full fluid film lubrication are also described. These bearing surfaces have shown the potential for greatly reducing wear debris.
Technical Evaluation of a Cad System for Orthopaedic Shoe-Upper Design
Authors: Lord M , Foulston J , Smith P J
Published: February 2007

Computer aided design is now employed routinely in the volume shoe trade. New styles are developed on a three-dimensional image of the last followed by automated pattern generation and engineering. It is suggested that such systems could be useful in the orthopaedic footwear industry although the different requirements for these bespoke products need careful consideration. A clinical trial has been conducted on the Shoemaster (Clarks Shoes) upper design system both to assess its technical capabilities and to consider its role in improvement of service and cosmetic appearance. This particular system works throughout on a three-dimensional representation of the shoe last, which offers particular advantages for integration with shape capture and reproduction. The report concentrates on the technical evaluation to assess (a) its ability to work with unusual last shapes dictated by medical requirements and (b) its potential for integration into a complete computer system for design of both shoe lasts and shoe uppers. The trial indicates that this particular system is promising in both respects.
Bioengineering in the Department of Mechanical Engineering at the University of Western Australia
Authors: Stachowiak G W
Published: February 2007

Current research projects conducted in the area of bioengineering at the Department of Mechanical Engineering, University of Western Australia, are outlined in this paper.
Automatic Algebraic Computation of Basic Kinematic Equations of Tree Structure Robot Arms: Application to Human Arms
Authors: Megahed S M
Published: February 2007

Tree structure robot arms have been very little studied due to the complexity of their topological structure compared with those of the simple chain type. This paper presents a symbolic computation of the basic kinematic equations of these tree structure robot arms. This leads to the calculation of the homogeneous transformation matrices (HTMs) of the tree branches. These computations are arranged to need the smallest possible number of arithmetic operations. A computer program MGLAT is developed in Pascal to generate such equations in symbolic form. The human arm which consists of the forearm, a wrist and fingers is a very good example of such a structure. A simplified model of 25 degrees of mobility of such an arm is presented. Its basic kinematic equations need 358 multiplications, 214 additions and 252 equations. These equations are useful for improving the existing designs of the artificial arms for handicapped persons and for designing new robot hands for delicate tasks.
Bioengineering Activities at the New York Orthopaedic Hospital Research Laboratory
Authors: Pawluk R J
Published: February 2007

An outline is given of the history of the New York Orthopaedic Hospital and a description of the bioengineering activities carried out at the Research Laboratory there.
Fixation of a Surface Replacement Endoprosthesis of the Metacarpophalangeal Joint
Authors: Sibly T F , Unsworth A
Published: February 2007

Surface replacement of the metacarpophalangeal joint would provide many benefits over current conservative treatment or the use of hinged spacers in excision arthroplasty. One of the main problems in surface replacement is securing adequate fixation of the prosthesis, especially if cement is not to be used. The direction and size of the forces that cause loosening have been described and a series of experiments in cadaveric bone have been used to elucidate the best shape of the component and stem to resist these forces. A 5 mm square section stem of 30 mm length gave the best overall result when combined with a flat on the palmar aspect of the inner bearing surface.
A Model of Force Transmission in the Tibio-Femoral Contact Incorporating Fluid and Mixtures
Authors: Schreppers G J M A , Sauren A A H J , Huson A
Published: February 2007

An axisymmetric finite element model is formulated which comprises a rigid spherical indentor, a meniscal ring and an articular cartilage layer, both considered as mixture materials which are interacting with an ideal fluid sub-system.

From parameter studies it is concluded that the application of the mixture theory in comparison with solid modelling only leads to significant effects when the outer surfaces of the components are not sealed. The load distribution appears to change enormously during relaxation of the models. Initially the largest fraction of the load is borne by the fluid in the cavity, while at the end, when the system has reached its final configuration, the meniscal ring bears the major part of the load. Further, the length of the relaxation period appears to depend on the magnitude of the step change of the load. Finally, the curvature of the spherical indentor appears to have significant effects on the loading of the meniscal ring, only immediately after the step changes of load are applied, and these effects disappear as soon as the fluid starts to exude from the models.
Computation of Two-Dimensional Transfer Functions
Authors: Whalley R
Published: February 2007

Procedures enabling the computation of the transfer function description of a two-dimensional system model from its state space representation are presented. A typical problem is outlined.
Relative Importance of the Various Vibration Transmitting Mechanisms in Hoses in Typical Hydraulic Systems
Authors: Longmore D K , Schlesinger A
Published: February 2007

The relative magnitudes of vibration in different directions and pressure fluctuations generated by typical hydraulic pumps are examined in conjunction with the extent to which they are transmitted along different types of hose to the subsequent circuit. By using a vibratory power flow approach, and looking at trends in the absence of resonances, it is possible to compare the importance of the different excitations and of their transmission by axial, bending and torsional waves along the hose. The predominant effect of pressure fluctuations from the pump is revealed.
Assignment of Eigenstructure by Use of Polynomial Matrices
Authors: White B A
Published: February 2007

This paper looks at the problem of eigenstructure assignment using output feedback. It solves the eigenvector and eigenvalue assignment for any system with output feedback by characterizing the solutions as polynomial matrices. It presents the concept of an annihilating polynomial matrix product to enable the space containing the eigenvectors to be described by a matrix polynomial. The range of eigenvectors is expressed as a polynomial vector for the achievable closed-loop spectrum, which is also expressed as a diagonal polynomial matrix. Two examples are given to illustrate the technique both for single-input and multi-variable systems.
Design of Robust Controllers for Position Servos Using H-Infinity Theory
Authors: Piché R , Pohjolainen S , Virvalo T
Published: February 2007

Linear feedback controllers for position servos are designed using a frequency domain optimization method based on H∞ theory. This method aims to produce a low-order controller which is ‘robust’, in the sense that the closed-loop system is guaranteed to meet performance objectives in the presence of unmodelled dynamics. A detailed design of a controller for a hydraulic position servo, including experimental results, is presented.
A Guide to Model Parameter Conversion in a Dual-Rate Adaptive Control System
Authors: Naumović M
Published: February 2007

The conversion procedures of slow model parameters to those of the fast model in self-tuning controllers based on dual-rate sampling are given. The proposed model parameter conversion allows the use of a larger sampling interval for on-line parameter estimation and a smaller one for control. Some results from an extensive simulation study are presented.
Rotodynamic Pump Efficiency Variations Due to Changes of Operating Speed or Temperature
Authors: Neumann B
Published: February 2007

The same pump is often required to operate at speeds and temperatures different from those at which it was tested by the manufacturer. This can be and is frequently done with appropriate design measures taken to meet the most stringent operating conditions dictated by the highest operating speed and temperature. In other cases testing of the unit at its design speed (or temperature) may be impractical and too costly to he justified.

In all cases a prediction of the unit's performance at its full operating conditions is important, particularly for high-power, large or high-speed machines. Theoretical considerations and test evidence show that changes of performance do take place at varying speed and temperature. These changes are due mainly to the variation of the flow Reynolds number. However, a reliable method of quantifying these changes has been and still is a matter of controversy.

A large number of formulae has been published by different authors in an effort to establish a general rule of efficiency ‘scaling’ for all hydraulic machines. Initially all losses of the machine were considered; it was found later that certain types of losses (kinetic) should not be ‘scaled’. However, in all cases, it is still expected that the higher the increment of speed (or temperature) in relation to test, the higher the efficiency improvement for all hydraulic machines.

The present work suggests that each category of energy loss behaves in a different fashion at increased speed or temperature. Therefore, whereas some losses remain constant at all speeds, other losses vary at different rates with Reynolds number. For this reason it follows that, in certain circumstances, an ‘optimum’ speed ratio or temperature ratio may exist at which efficiency increment would become a maximum. Two expressions describing such an optimum speed ratio and temperature ratio in terms of the loss breakdown of the pump are developed and discussed. An analysis of the expressions shows that, in certain circumstances, which may easily occur in practice, a loss of efficiency rather than an increment can occur with increased speed (or temperature).

Moreover, since disc friction and volumetric losses exert a major influence on the magnitude and the position of the optimums, the individual unit breakdown of losses in test conditions is required to make a reliable performance prediction for speeds (or temperatures) different from test speeds (or temperatures).
Design of a Highly Loaded Mixed Flow Turbine
Authors: Abidat M , Baines N C , Firth M R
Published: February 2007

The high boost pressures and fuel–air ratios required for the next generation of turbocharged diesel engines imply an increased turbine expansion ratio without an increase in the speed of rotation. This leads to a requirement for high peak efficiency at lower values of blade speed/isentropic expansion velocity U/C than are normal today. The objective of this project was to achieve this with a mixed flow rotor with a positive inlet blade angle. Two rotors were manufactured and tested: one a ‘constant blade angle’ design and the other a ‘constant incidence’ design. In practice both achieved a peak efficiency at a low U/C value, but the constant blade angle design, at 0.84 total to static efficiency, was significantly more efficient than the constant incidence design at 0.77. These efficiencies are highly competitive, compared to current radial turbine design. It is suggested that the reasons for this difference are a lack of understanding of the incidence and its effects on a mixed flow rotor, and a region of diffusion in the shroud-trailing edge corner of the suction surface, apparently worse for the constant incidence design.
Performance Prediction of a Mixed Flow Impeller
Authors: Sarkar S
Published: February 2007

A method based on two-dimensional cascade theory is presented here to predict the characteristics of mixed flow impellers of high specific speed having a conical flow path. The theoretical characteristics are compared with the experimental results. Agreement is fairly good in the normal operating range, but some uncertainties exist in the assessment of appropriate slip factors and losses in the field of mixed flow rotor cascades, which need further studies. In the present case, the flow is assumed to be incompressible.
Matching and Work Ratio in Elementary Thermal Power Plant Theory
Authors: Smith I K
Published: February 2007

For most thermal power plant, the Carnot cycle efficiency is not the true ideal. Matching the cycle to the source leads to alternative limits and improved perceptions of how practical power plant can be improved. A method of including the work ratio into an ideal cycle analysis is presented which simplifies the estimation of practical power plant efficiencies and highlights the historic course of thermal efficiency improvement.
A Study on an Improved Direct Search Interpolation Method for Two-Axis CNC Thermal Cutting Systems
Authors: Lho T-J , Na S-J
Published: February 2007

A microcomputer-based reference pulse software interpolator, which can be effectively applied for two-axis computer numerical control (CNC) systems such as those used in plasma arc cutting and laser beam cutting machines, is proposed in the present study. The proposed interpolation method is based upon searching in two or three directions for the minimum path error, while the axes of motion do not move simultaneously in the stairs approximation method and the basis for selecting an interpolating point is not related to any criteria of path error in the digital differential analyses (DDA) method. Accordingly, this method has many advantages over the other two competing methods, such as small maximum path error of only a half basic length unit (BLU), uniform velocity along the cutter path, high degree of path smoothness and maximum velocity allowable.

Since the velocity of the proposed CNC system is controlled through adjusting two interrupt interval times at each interpolation step, a constant velocity can be maintained along any cutting path. The proposed interpolation algorithm is very simple and can be easily applied for the practical CNC systems, since it is based on transforming the interpolating paths in all interpolating cases to those in one typical case.
A Study on Parameter Optimization With Numerical Heat Conduction Model For Circumferential Gas Tungsten Arc (GTA) Welding of Thin Pipes
Authors: Lho T-J , Na S-J
Published: February 2007

One of the important problems to be solved in welding engineering is to develop a mathematical method for the determination of optimum process parameters. In order to estimate the optimal process parameters in circumferential gas tungsten arc (GTA) welding of thin pipes, an objective was chosen to maintain a uniform bead width over the full circumferential joint, while the constraints consist of the capacity limit of the welding power source and equipment used.

A transient three-dimensional finite difference model (FDM) of the heat conduction flow in the circumferential GTA welding of pipes was adopted for calculating the temperature field considering the temperature-dependent thermal properties of the workpiece, and consequently for determining the resultant bead width in circumferential welding of the pipe workpiece. An efficient optimization model for the numerical heat conduction flow was proposed to evaluate the optimal welding current with a given welding velocity for a required bead width. Its solution was obtained by employing the steepest descent method (SDM), where the initial value of the welding current was estimated by using the linear complementary problem (LCP), and the welding currents in the middle part of the pipe were interpolated by the least-squares approximation method of the second order.

The experimental results of the bead formation showed that the developed mathematical model can be effectively applied to obtain the optimal welding condition in circumferential welding of thin pipes, especially thin pipes with a small diameter and high thermal conductivity.
Geometric Constraints on the Forming Path in Roll Forming Channel Sections
Authors: Panton S M , Zhu S D , Duncan J L
Published: February 2007

In roll forming, flat strip is progressively deformed by sets of rotating rolls; it is a commercially important metal forming process but not one that has been extensively studied on a scientific basis. This paper introduces a new method of indicating forming severity, the bend angle curve, which shows the bend angle distribution and the geometric restrictions imposed by the shape of the rolls, it includes and extends an existing theoretical model of deformation in the unsupported strip based on a modified minimum energy concept. Experiments were carried out in which a channel section was roll-formed and the shape of the strip measured along the whole deformation region. Good correlation was obtained with the predicted bending angle curve and the results demonstrate the influence of roll diameter as well as cross-sectional shape.
Cold Rolling of Foil
Authors: Fleck N A , Johnson K L , Mear M E , Zhang L C
Published: February 2007

A theory of cold rolling of thin gauge strip is presented which, within the idealizations of homogeneous deformation and a constant coefficient of Coulomb friction, rigorously models the elastic deformation of the rolls and the frictional traction at the interface. In contrast with classical theories (3) it is shown that, for gauges less than a critical value, plastic reduction takes place in two zones, at entry and exit, which are separated by a neutral zone in which the rolls are compressed fiat and there is no slip between the rolls and the strip. Roll load and torque are governed by five independent non-dimensional parameters which express the influence of gauge, reduction, friction and front and back tensions. Values of load and torque have been computed (for zero front and back tensions) for a wide range of thickness, reduction and friction and have been found to collapse approximately on to a single master curve.
Application of Three Non-Linear Programming Techniques in Optimizing Machining Conditions
Authors: Eskicioğlu A M , Eskicioğlu H
Published: February 2007

Mathematical models used for determining optimal machining conditions are non-linear functions subject to non-linear constraints. In this paper models for unit production cost and unit production time for multi-pass milling operations are developed, taking cutting speed, depth of cut, feed and number of passes as design variables. The problem is then solved by three non-linear programming methods, namely the generalized reduced gradient (GRG) method, the sequential unconstrained minimization technique (SUMT) and the flexible tolerance method. The efficiency of the methods in obtaining the solution is discussed. It is shown through computational experience that their usefulness differs considerably, some parameters in the computer codes used requiring careful selection for the models in question.
Computer Aided Design Of Garments Using Digitized Three-Dimensional Surfaces
Authors: McCartney J , Hinds B K
Published: February 2007

In the apparel field, there is the problem of creating a design with respect to an underlying standard form. Instead of applying general-purpose three-dimensional computer aided design systems to such tasks it is proposed that design can be carried more efficiently with bespoke design systems. These can be targeted to deal with the problems of accurately defining the offset surfaces which comprise the garment. Such a system is introduced and the methods of data entry are discussed. Position on the three-dimensional form is determined using a digitizer tablet and fit with respect to the form is specified by an offset dimension. It is shown that complex garment pieces with variable fit can be quickly specified within the system.
Supply Chain Dynamics—The Change Engineering Challenge of the Mid 1990s
Authors: Towill D R
Published: February 2007

Much has been written concerning the supply chain demand amplification problem, best described by the ‘law of industrial dynamics’. Broadly speaking, if a supply chain can find a way to fluctuate, it will.

The paper defines supply chains and reviews their current state of development. By way of a simulation example, the importance of good, shared, information flow is highlighted, as are several other strategies that lie more within the control of individual businesses. Good supply chain operation requires adequate design, led by a product champion committed to systems change. Persuasive evidence to support the product champion is therefore offered. Examples include internally generated demand amplification caused by human schedulers; an industrial supply chain case history; supply chain redesign via simulation; and a review of a proposed effectiveness framework which offers the possibility of integrating both modelling and design phases.

The methodologies that are described herein may be universally applied to any industrial or commercial sector in which there is a value-added process. They have found great favour in the automotive industry, which is manifestly an area of endeavour where customer selectivity leads directly to the ‘demand chain’ viewpoint. However, a health care supply chain example also appears in the paper because it contains an important feature which could be duplicated to great advantage in many other applications. This is the opportunity taken to build customer-driven ‘phase advance’ or predictive capability into the system in order to improve the flow of both orders and products.
Alias Errors in Precision Rotary Encoder Calibration
Authors: Smith J D
Published: February 2007

Discrepancies between errors measured by back-to-back tests on rotary encoders and the errors quoted by the manufacturers led to investigation of the causes for the difference. An error that was apparently at 96 cycles per revolution was found to be due to a much higher frequency which was well outside the normal operating range for transmission error work.
A Numerical Analysis of an Elastically Dissimilar Three-Dimensional Sliding Contact
Authors: Munisamy R L , Hills D A , Nowell D
Published: February 2007

A numerical method is employed to find the traction distribution caused by sliding contact between a sphere and an elastically dissimilar half-space. The resulting stress field is compared with a standard Hertzian analysis where coupling between the normal and shear tractions is absent. Significant differences are found at the surface for large values of the coefficient of friction.
A Gear Test Rig with a Variable Torque Actuator
Authors: Smith J D
Published: February 2007

The requirements for a test rig for gear damage monitoring purposes and the problems of standard recirculating designs are discussed. In particular, the need for torque variation while running is emphasized. An economical design based on easily replaceable standard gears and the use of an air torque actuator is shown. Problems were encountered with air leakage and with gear lubricating oil flows initially but simple solutions were applied successfully.
A Note on Compressible Flow through Orifices in Series
Authors: Anderson A
Published: February 2007

Because of the form of the standard equation for compressible flow through an orifice, it is difficult to solve problems for orifices in series where the inter-orifice pressures are not known a priori. However, a simple graphical construction combines the mass flowrate-pressure characteristics for individual orifices to give a single overall characteristic for those orifices in series. This also enables the main features of the flow to be examined, including the conditions under which it chokes.
Study on Transmitting Torque and Synchronism of Magnet Couplings
Authors: Tan Q C , Xin D , Li W , Meng H
Published: February 2007

Transmitting torque and synchronism of magnet couplings are studied by magnetic charge. A formula of transmitting torque is derived and examined by experiments and a parametric study is performed using the formula. The results show that even-number couples of magnetic poles can increase the transmitting torque, but it is not suitable for axial direction dimensions of the coupling magnets to he larger than 40 mm. The torque is largest when an angle of the relative rotation reaches half of the central angle of a coupling magnet.