bluuebunny/crossref_metadata_2025 huggingface dataset:
Development of a n alternative control scheme fo r a naval propulsion plant
Authors: Kidd P.T. , Munro N. , Winterbone D.E.
Published: August 2008

The control of a gas-turbine powered controllable-pitch propeller ship propulsion plant, of the type found in modern warships is considered. The existing control philosophy is examined, and the development of a gain-scheduled multivariable control system, suitable for implementation in a distributed computer control system, is presented. Some typical non-linear simulation results are presented and a number of potential problem areas of the proposed control system are outlined.
Digital compensation: a comparison of methods
Authors: Forsythe W. , Sherit K.L. , Self A.W.
Published: August 2008

Four methods of designing a digital compensator for a simple plant are examined and the dynamic performance of each is compared with that of an analogue phase advance network. The comparison is made in terms of closed-loop, step and frequency responses and steady-state error, and significant conclusions are drawn about the merits of the design methods.
Minimisation of interference effects in thyristor converters by feedback/ forward control
Authors: Luo F.L. , Hill R.J.
Published: August 2008

In industrial closed-loop control systems such as thyristor current converters, good system quality can be difficult to obtain, for example, because of the lack of complete compensation of interference by the feedback arrangement. This paper describes an application to such equipment of Feedback/Forward Control (FBFC), which can implement optimum regulation provided that the regulated output and the open-loop transfer function are both stable.

The basic premise of the control scheme considered here is that, since there is zero steady-state error between reference and feedback signals, it is possible to replace the feedback circuit by a digital controller having a number of inputs; when the reference or feedback signal varies, the output of the controller will then follow the change, and the system output can reach a new steady-state with a minimum time lag (optimum regulation). FBFC achieves accurate system regulation by combining the usual advantages of feedback control with the anticipatory properties of feedforward control.
Analysis of swirl, viscosity and temperature effects on turbine flowmeters
Authors: Salami L.A.
Published: August 2008

This paper shows that swirl has a great influence on turbine meter characteristics and the error per degree of swirl is about 2.5%. It also demonstrates that the viscosity effect on the turbine meter is not correlated by Reynolds' number especially at high viscosities. Range of viscosity covered is 1-400 centipoise. Temperature effects were shown to be better correlated using an empirical relation based on pulses per unit mass flow rather than pulses per unit volumetric flow. Temperature range covered is 20-60°C.

A theoretical model has been proposed which gives a fair agreement with experimental results provided that the changes in the axial velocity profile with swirl are taken into consideration. The same model has been used to explain the effects of viscosity and temperature.
Finite element modelling of Bourdon tubes used in pressure and temperature gauges
Authors: Bansil M.S. , Abdullah F.
Published: August 2008

A finite element program has been developed for the elastic analysis of Bourdon tubes used in both pressure and temperature sensing. The theory developed succeeds in enabling the three-dimensional Bourdon tube to be treated as a two-dimensional problem, by assuming that material properties and geometry do not change in one direction.

The program was applied to several Bourdon tubes. Results for end-deflection data given by Bourdon tube manufacturers are compared with the finite-element-program results. These agree to within 10%. Also, stress patterns for two temperature Bourdon tubes are presented; one with edge grooves and one without. The post-processing showed that reduction in the level of stresses can be achieved by incorporating edge grooves. The use of such a model for Bourdon tube design is discussed briefly.
Occam structures in control applications
Authors: Jones D.I.
Published: August 2008

Examples are given illustrating the use of the Occam programming language in control applications. It is demonstrated that numerical algorithms for real-time control and computer aided design may be configured for multiprocessor systems using the Occam approach. The three examples are:

1. Numerical integration.,

2. Gradient minimisation with array line search ;

3. Inverse dynamics for a robot manipulator.
A technical drawing aid for blind students using stereo audio feedback
Authors: Linkens D.A. , Rimmer S.J. , Powell R.S. , Peers M.
Published: August 2008

This paper describes a project to develop a technical drawing aid for blind secondary school children to assist their scientific education. The aim was to produce an accurate graph-construction system which can be used both for producing graphs and reading out existing material. The instrument comprises a conventional draughting board equipped with optical sensing of a bar track to provide digital information of co-ordinate positions. Error signals are produced in stereo headphones, and Braille tactile read-out signals are provided. Good tracking performance and acceptability have been achieved in trials with a group of blind children at Tapton Mount Blind School, Sheffield.
Digitising and measurement of variable-frequency waveforms in thyristor drives
Authors: Martin J.G. , Roebuck C.A.
Published: August 2008

On-going research within our department concerns the testing of thyristor drives for traction use. As a result of this work it became necessary to digitise the repetitive variable-frequency signals produced by the drives, to obtain by software processing root-mean-square and average values of current and voltage waveforms. This was undertaken primarily for calibration and comparison with standard methods of obtaining average and root-mean-square values using meters and integrated analogue devices like the AD636J. The paper describes the hardware and software developed around a low-cost microcomputer BBC Model B, to digitise a complex waveform and calculate its r.m.s. and average value.
A novel system for in-flight detection of wind shear
Authors: McLean D. , Samaka M.B.
Published: August 2008

For any aircraft an encounter with wind shear during take-off, initial climb, or landing approach is a hazardous flight situation. This paper describes the design of an airborne wind shear detection system which has been arranged to provide pilots with a vocal alert upon encountering wind shear, and also vocal annunciation of the intensity and direction of the horizontal component of wind shear. Its vertical velocity component is presented visually. The system is based upon Luenberger observer theory and the design involves the use of a microprocessor and a voice synthesis device. The results of the simulation of a landing approach in the presence of an acute wind shear are used to illustrate the effectiveness of the system.
Kalman filter parameter identification: a practical approach
Authors: Freeman J.M. , Hassan F.N. , Morton D.
Published: August 2008

This paper describes the principles of application of the extended Kalman filter identification technique as a means of identification of linear systems with Gaussian random inputs. Major consideration is given to an algorithmic implementation rather than to theoretical background in an attempt to make the technique more widely available to the engineer. Results of simulation studies suggest guidelines to aid in successful application of the technique to experimental situations.
System analysis of digitally controlled thyristor converters
Authors: Luo F.L. , Hill R.J.
Published: August 2008

This paper describes the behaviour of digitally controlled thyristor converter systems and includes the effects of variable firing angle and feedback filter configuration. System stability has been analysed by using the perturbation method, and system responses for both reference and disturbance signals have been obtained using z-transforms. System optimisation has been achieved by careful choice of the regulatable parameters. Both theoretical analysis and experimental results indicate that closed-loop control with unity feedback can have good system quality, with easy optimisation.
Computer aided analysis and design of MIMO bilinear control systems
Authors: Kleftouris D.N. , Petrou L.P. , Hassapis G.D.
Published: August 2008

In this paper a CAD procedure for the analysis and design of bilinear MIMO control systems is presented. Algorithms are developed for the solution of the bilinear system state-space equations, based on the fact that the bilinear system can be treated as a linear one at every sampling instant. Stability is examined by means of suitable signal and induced system norms. Finally, a bilinear system is analysed and designed, using the developed CAD procedure.
Self-tuning and adaptive control-a reviewofsomebasictechniques
Authors: Hughes F.M.
Published: August 2008

Established methods for adaptive and self-tuning control are looked at with the aim of providing a guide to both the methods and the fundamental principles involved. Some model reference adaptive control and explicit and implicit self-tuning methods are presented, along with their major characteristics. In addition, the similarities which exist between methods derived from widely differing concepts are also indicated.
Modelling of a fluid catalytic cracker
Authors: McGreavy C. , Isles-Smith P.C.
Published: August 2008

The operational characteristics of the fluid catalytic cracking process are determined by a complex interaction between the energy balance arising from the reactor and regenerator units and the pressure distribution, which determines the recirculation of the solid catalyst. In addition, there are both lumped and distributed parameter elements which, together with the non-linearities arising from the kinetics of reaction and combustion (as a result of regenerating the catalyst), cause unexpected behaviour patterns. Using a detailed dynamic model of the process, it is possible to resolve many of these problems and, in particular, show the important role played by combustion in the freeboard region of the regenerator. Such information is particularly useful in relation to the design of the regenerator since the mode of operation can have a significant effect on per formance, especially with respect to stability.
Dynamic model of a pyrolysis furnace
Authors: McGreavy C. , Odloak D.
Published: August 2008

A dynamic model of a pyrolysis furnace is developed which takes account of the lags arising from the reactor coils, the radiation and convection combustion zones and the furnace refractories. The physical problem is analysed to find computational strategies for the numerical solution which overcome the inherent stiffness of the overall system equations. In order to be able to predict the product distribution during transient operation, it is essential to have a mechanistic-type kinetic model for the reactions, and the thermal processes must be capable of predicting the spatial distribution of temperature at any time. An examintion of the minimum level of detail to do this provides valuable insight as to how the observed dynamic responses can be explained in terms of the interaction of the characteristic fundamental processes. From this, it is possible to identify modes of operation which will not result in design limitations being exceeded, and enable safe procedures to be established for start-up and shut down which can be interpreted in terms of the physicochemical processes.
Microwave moisture and density measurements in particulate solids
Authors: Kent M. , Kress-Rogers E.
Published: August 2008

Microwave techniques for the measurement of moisture content are very well known. Their use with particulate solids is, however, difficult unless the bulk density of the material is either stabilised or monitored. This limitation of the method can be overcome by using instruments which measure two microwave parameters and, in addition, some further computation can yield not only density compensation but also density determination. To demonstrate the wide applicability of this method, dielectric data are taken from the literature for a variety of different particulate solids, and the parameters relevant to industrial microwave measurements extracted.
Validation of a compressor model
Authors: Elder R.L. , Razak A.M.Y.
Published: August 2008

A mathematical model capable of simulating transient performance of fan and compression systems is described. The model is based on the dynamic forms of the conservation equations and incorporates a polytropic analysis. The steps taken to validate the model and several applications of the model are described.
Application of distortion technique for model validation to nuclear power plant - AGR scatter plug
Authors: Li C.L.R.
Published: August 2008

The distortion technique has been applied to validate quantitatively a dynamic model of a scatter plug as used on advanced gas-cooled reactors from comparison with recorded rig results, A brief outline of the technique is given which illustrates the distortion required for the constant parameters within the model and the assessment of model adequacy. Initially these assessments indicated that the model was not adequate to explain the test results. This led to significant improvements of the model and better under. standing of the model and the tests, Eventually, after several improvements in the model, the quantified criterion inherent in the distortion technique was satisfied indicating model adequacy.
Thermocouple and RTD approximations for the design of portable microprocessor-based simulators
Authors: Dooley L.S. , Evanst W.A.
Published: August 2008

Thermocouple and R TD simulators are instruments that fall into the 'intelligent instrument' category and are increasingly being used for calibration and fault diagnosis purposes in applications where thermocouple and resistance-temperature detectors (RTDs) are used for the sensing of temperature, These instruments depend on storing and retrieval of the transducer characteristics so that, in operation, the instrument will meet and exceed the British Standards for thermocouples and RTDs.

This paper contains a detailed study of the problem of storage and generation of the transducer characteristics, concluding that linear curve fitting combined with the exchange algorithm offers the best solution for instruments based on cheap, low-powered microprocessors with limited instruction sets.
Industrial application of the frequency-domain aspects of the Kalman filter
Authors: Odonde J.
Published: August 2008

Several classical industrial filtering applications have used notch filters to reject the unwanted dominant frequencies. For a class of industrial systems, it has been shown that the filter gain between the observations and the signal estimates is unity. While the gain between the observations and the disturbance state estimates is zero, the zeros of the Kalman filter are determined by the poles of the disturbance model. These results are generalised to a more representative case of a block-diagonal structure with feedback coupling.
A graphical pre-processor for computer-aided control system design
Authors: Barker H.A. , Chen M. , Grant P.W. , Jobling C.P. , Townsend P.
Published: August 2008

Features in the design of a graphical man-machine interface for pre-processing the inputs to computer-aided control system design software are described in this paper. The primary objective is to allow the control engineer to communicate with a modem graphics workstation in a natural, familiar and friendly way, by means of block diagrams, signal flow graphs and standard mathematical text. Graphical methods for the input and output of these are described. Transformations between different system descriptions are considered which allow all algebraic manipulations and reductions to be performed on signal flow graphs. For these manipulations, rule-based methods are shown to be effective. The possibility of using symbolic computation languages for algebraic operations is also considered.
A systems approach to combat modelling
Authors: Wolstenholme E.F.
Published: August 2008

This paper presents a demonstration of the potential contribution of system dynamics to defence operational analysis. The changing face of modelling in this area is highlighted, and a demonstration model, capable of analysing overall interactions between red and blue strategies, is presented.
Pipelined algorithm-specific hardware for shape comparison of tableglass
Authors: Appleton I.K. , Nixon M.S.
Published: August 2008

An instrument has been designed to enable a glass-blower to check the shape of a glass in real-time. The outline of the glass being inspected is displayed on a television monitor superimposed on the outline of'a reference glass so that differences in shape between the two can be ascertained. This instrument uses techniques of optical inspection and implements an algorithm which was first developed on a conventional image processing system and then translated to a hardware implementation to provide the inspection facility. A novel pipelined architecture is used to implement the algorithm to enable operation at video rate at low cost; this avoids the use of a high-speed (and expensive) computer system. It also provides a precise measure which is obtained instantaneotisly, without contact. At the 'hot end' of manufacture, this facilitates rejection of faulty items prior to cooling. At the 'cold end', this is a major step towards automation of inspection and sorting of glassware. Checking of shape is naturally not restricted to the glassware industry; this instrument may be useful in other areas of manufacturing.
Optical fibres in chemical sensing - a review
Authors: Guthrie A.J. , Narayanaswamy R. , Russell D.A.
Published: August 2008

The use of optical fibres for the sensing of chemical species is reviewed in this paper, which is divided into three sections. The first section discusses the variety of probe designs that have been proposed and studied, the second presents the numerous applications and the sensing techniques studied to date, and the final section summarises these developments and is presented in the form of a table. Finally, conclusions have been drawn on the state-of-the-art of this new technology and on the future applications of these novel devices.
Microcomputer-controlled robotic equipment for precision TIG welding
Authors: Morris E. , Lucas J.
Published: August 2008

The TIM robot has been designed for use with high-precision welding using the TIG (tungsten-inert-gas) process. Details are given of the design and construction of a five degrees of freedom machine, having cartesian and wrist movements. Details are also given of the operating features and the microcomputer and electronic hardware necessary to achieve these design features. An Intel 8085 8-bit microcomputer was used to control the welding operation; the workpiece position and movement and the time sequence of the welding cycle could be controlled in accordance to a predetermined set of parameters stored in memory.

The approach adopted for software development is also described. Emphasis is placed on the use of a high-level language to achieve flexibility, with subroutines in assembly language for faster response. Path entry was carried out by moving the torch around the joint and recording by the point-to-point technique. Complex joint paths, for example circular, square and triangular paths, can be reproduced accurately, and such welds have been used as illustrations of the flexibility of the machine.

In designing the machine for TIG welding operations, the controller was fully protected against HF airborne noise present during arc initiation.
Digital controller fluctuation-source tracing using power spectral decomposition technique
Authors: Shieh D.J.
Published: August 2008

In a digital controller, the outputs may have large fluctuations due to the quantisation noises. If the digital controller is part of a closed-loop system, then the fluctuations will propagate to everywhere and it is difficult to locate the primary source of the fluctuations by studying only the plain data. In this paper, a power spectral decomposition technique is applied to resolve this problem. To make the application viable, the data taken from the digital controller are modified to reflect the cause- consequence calculation-sequence. A successful application in a real digital controller debugging case confirms the usefulness of the technique.
A view of metrology training in manufacturing industry
Authors: Whitehouse D.J.
Published: August 2008

The role of the metrologist in engineering is changing. The paper identifies this new role and examines eight different ways in which the training of suitable metrologists might be achieved, both at present and in the future.
A survey on the formation of metrologists
Authors: Benson F.A.
Published: August 2008

The paper presents and discusses some of the results of a survey carried out to determine (a) to what extent the field of measurement technology is covered in undergraduate and lower-level courses; (b) whether representatives from industry and academic institutions have got together to ensure that courses on measurement technology required by industry are anticipated and met; and (c) if sufficiently modern equipment and techniques can be provided and demonstrated and whether the increasing impact on measurement technology of microprocessor and computer technology is being adequately covered. Some evidence was also gathered during the survey on the supply of and needs for measurement technologists, the status and career prospects for such technologists, employment of women in metrology and metrology centres and clubs. Possible actions to overcome the shortage of industrial measurement technologists are mentioned.
Training and staff requirements in measurement, calibration and metrology
Authors: Flanagan T.P.
Published: August 2008

After an opening argument for less usage of the words metrology and metrologist and a more consistent use of the word measurement as both noun and adjective, the paper deals with the author's main task of analysing the qualities required of people seeking to work in the measurements business. This is related to the author's own organisation, Sira Ltd, and its work in instrumentation R&D and technology services. After a broad review of Sira's work, the need for qualities ranging from inventiveness and breadth of vision to communication and commercial awareness are emphasised. Figures are given which show how the proportions of graduates with differing disciplines (physicists, chemists, engineers, mathematicians) are distributed differently between R&D and other demanding technical activities. Types of training needed to reduce the shortage of measurement specialists are discussed, from the postgraduate taught MSc course to the few-day specialists' courses. The measurements community should influence the teaching of measurement principles in all science and engineering courses. It must play its part in persuading young people to enter science and engineering careers and then ensure it attracts a good proportion of them to the field of measurement.
The role of the service sector
Authors: Nankivell O.
Published: August 2008

As the economies of the western world swing more and more towards service activity, and those working in production industries themselves contribute increasingly by service activities within their organisations, measuring output and productivity becomes a vital concern. In this paper an economist studies the issues from a national viewpoint. Many of the ideas are directly relevant at the level of the firm or corporation.
The design of a control system for an unstable canard aircraft using eigenstructure assignment
Authors: Cowling David A.
Published: August 2008

The problem of designing a control system for a nonlinear unstable canard aircraft is presented. Design performance criteria including robustness and pilot-handling qualities are discussed. The eigenstructure-assignment technique is used to determine the gains of a simple, practical system. The results of three designs are presented and show good handling and robustness qualities.
Structural load alleviation
Authors: Ali Q.R.
Published: August 2008

Aircraft having flexibility can develop large amplitude acceleration due to structural modes, in addition to that caused by the rigid body motion. Reduction of these loads by means of active control systems is an important problem in flight control. Load alleviation control by means of full state variable feedback, obtained as a solution to an eigen vectorleigen value assignment problem is demonstrated in this paper. The mathematical model of the aircraft used as an example, the C-5A, includes the linearised longitudinal equations of the rigid motion, the dynamics associated with the first flexural mode of the wing and the linear dynamics of the control surface actuators. Assessment of the degree of alleviation achieved is based on the calculated root mean square (RMS) values of both the bending and torsional moments at the wing root, these moments being represented by an output equation which is a linear combination of the state variables of the aircraft dynamics and the command signals to the control surface actuators,
Hypersonic vehicle pitch stability measurement in a ground based facility
Authors: Hutt G.R.
Published: August 2008

The determination of the aerodynamic pitch stability derivatives of a hypersonic-flight vehicle require the measurement and subsequent analysis of model motion time histories. This paper outlines, briefly, the strain-gauge and optical systems employed with captive and free-flight model experiments as performed in a hypersonic wind tunnel. The advantages of optical model position measurement are presented, highlighting both an intensity modulating system and an intensity compensated absolute position sensing system.
Polynomial matrix solution of the optimal deterministic continuous-time servomechanism problem
Authors: Grimble M.J.
Published: August 2008

A polynomial matrix solution of the optimal deterministic servomechanism problem, for continuo its-time systems, is presented. A closed-loop optimal controller is obtained driven by the tracking error, as in classical control schemes. The controller is easily computed via a standard polynomial matrix manipulation and solution algorithms.
A microcomputer-based measurement system fordisplaying the admittance characteristics of acoustic transducers
Authors: Coates R.
Published: August 2008

The admittance circle diagram is an important method of characterising the terminal response and, thus, the electrical equivalent circuit of acoustic transducers. Equipment to yield such plots is relatively costly and consequently less readily available than might be desired. This paper describes a method of obtaining admittance plots, typically to frequencies of the order of a few megahertz, which involves only modest circuit development. The method avoids circuit design complexity by relying upon the computing power of any readily available microcomputer to effect correction of parameter cross-coupling.
Transfer-function-matrix realization in multivariable systems
Authors: Perry R.J. , Sun H.H. , Berger W.A.
Published: August 2008

This paper considers the realisation of a multivariable system Transfer Function Matrix (TFM) using a new systematic approach to the closed-loop pole-zero assignment. It is shown that complete control of the individual TFM elements can be achieved by obtaining complete control over the state-space matrices {A,B ,C ,D} in a systematic way. In terms of the TFM, this is achieved by producing any desired poles and any desired single row and column of numerator polynomials. The method utilises all of the available degrees of freedom and is sufficient to produce an arbitrary n th-order TFM. New transformation matricesM andV play an important role in the relationship between the state-variable matrix forms and the poles and zeros of the individual elements of the TFM, as well as in computation of required feedback and feedforward gains,
Design of robust adaptive digital setpoint tracking Pl controllers incorporating recursive step-response matrix identifiers for gas turbines
Authors: Porter B. , Khaki-Sedigh A.
Published: August 2008

It is shown that, by incorporating fast on-line recursive identifiers to provide updated step-response matrices for inclusion in digital proportional-plus-integral control laws, highly robust adaptive digital setpoint tracking PI controllers can be readily designed for multivariable plants. The effectiveness of this methodology is illustrated by designing an adaptive digital setpoint tracking PI controller for a gas turbine using both exactly parametrised and grossly under-parametrised models.
Manoeuvring and motion control of a hydrofoil
Authors: Whalley R. , Gregory P.C.
Published: August 2008

Computer-aided design techniques are described and demonstrated in studies associated with the regulation of pitch, roll, heave and yaw of a 31 m surface piercing hydrofoil. The procedures outlined are effected by way of a comprehensive suite of software for control system data processing which is employed in the transformation of the basic model into partitioned subsystems and thereafter into spectral factors, allowing the dynamic composition of the system and the number of decoupling strategies available to be determined. A preferred family of dynamic elements is identified from this procedure for reduction and simplification, to achieve the containment of output coupling rather than non-interaction in the target scheme. Compensators selected for their robustness, simplicity or integrity are generated within the design program, and the performance of the interfaced system is assessed thereafter using frequency-response methods.
Sensitivity aspects of pre-compensator design for a shipsteering/stabilisation system
Authors: Roberts G.N. , Navy Royal , Towill D.R.
Published: August 2008

The main problem encountered in the implementation of controller designs based on simulation studies is the effect that plant uncertainty can have on the compensated system's performance. This problem is exacerbated in the multivariable case, in which interaction levels can also exhibit uncertain characteristics. This paper examines the simple relationship which exists between the multivariable plant and its pre-compensator and shows how it is possible to predict the sensitivity of the compensator to system uncertainty.
Digital controllers for bank-to-turn CLOS guidance
Authors: McConnell G. , Irwin G.W.
Published: August 2008

BTT CLOS guidance is achieved on the basis of two identical, independent single-plane controllers in conjunction with polar conversion of the guidance commands. Design techniques studied include six methods of discretisation, design in the w' plane, pole placement in the z plane and discrete optimal LQ control. Computer simulation results for a three-dimensional stationary target engagement and a 10th-order non-linear state model of the missile dynamics are included
Discrete dual-rate stochastic optimal control
Authors: Grimble M.J.
Published: August 2008

The digital control of industrial systems in which the measurement system sample-time is longer than the controller and filter scan rate is considered. The problem is posed using a stochastic linear optimal control framework, and a separation principle is shown to apply. If the plant is assumed to be time-invariant and the noise sources are stationary, then the control gain matrix can be shown to be a constant matrix; however, the filter Riccati equation gives a periodic solution and the filter gain matrix is only non-zero at the measurement points. The conditions under which the dual rate feedback control system is asymptotically stable are established.
Indirect adaptive pole-assignment controllers with direct implementations
Authors: Teng Fong-Chwee
Published: August 2008

A new strategy involving the cancellation of system poles and controller zeros is proposed for the indirect adaptive pole-assignment controllers. The resulting controllers can be implemented without solving simultaneous equations. A new method of eliminating the offset due to reference input without an explicit integrator is also proposed. The new strategies can be applied to pole assignment controllers of both general-feedback structure and error-driven structure. The results obtained from the simulations and trials on a stirred tank process verify that the controllers work well.
Expert systems, fuzzy logic and rule-based control explained at last
Authors: Efstathiou Janet
Published: August 2008

New techniques are becoming available to control and manage manufacturing plant, including rule-based systems, knowledge-based systems, fuzzy logic, etc. This paper will describe briefly what the terms mean and how they interrelate. It is argued that expert, rule-based systems for control differ fundamentally from traditional control systems because they attempt to model the skills of the human operator, rather than modelling the process itself Expert systems and intelligent knowledge-based systems will be introduced, explaining how they may be used in industrial control, for other complex tasks. The problem of knowledge acquisition is discussed, again in the context of control, and the role of fuzzy logic is explained, as a means of expressing necessarily imprecise knowledge and coping with the problems of an incomplete knowledge-base. The self-organising controller is briefly introduced as an enhancement of rule-based control The scope of rule-based control and artificial intelligence in general is discussed briefly. Existing and possible applications of the techniques are indicated, together with what their limitations likely to be.
Surface-topography assessment: precursor to the prediction of pressed-contact behaviour
Authors: O'Callaghan P.W. , Babus'Haq R.F. , Probert S.D.
Published: August 2008

The deformation mechanisms ensuing when a contact between two nominally-flat surfaces is subjected to mechanical and thermal stresses have been examined and the surface properties essential for the prediction of the contact's behaviour identified. These parameters include: the surface micro-hardness (in order to estimate the total true area of contact); the root-mean-square roughness as well as the mean absolute asperity-slope (so as to be able to predict the number and mean size of micro-contacts); the mean radius of curvature of the asperity peaks (which will help to indicate whether the surface deformations will be predominantly plastic or elastic); and surface wavelength parameters, such as autocorrelation and power spectral density functions (which are needed to estimate how micro-contact populations cluster at contacts formed between wavy surfaces). Various methods for surface-topography assessment and appropriate data manipulation in order to deduce values for meaningful parameters are described.
System dynamics: a methodological perspective
Authors: Keys P.
Published: August 2008

System Dynamics has been a recognised means of modelling and understanding the behaviour of complex systems for over 30 years. In that time it has been interpreted from several different perspectives. In this paper a theme is developed which cuts across these different views and opens up a further area of investigation. By considering the methodology of System Dynamics, the changing purpose and role of the approach are identified. Issues which were previously seen as sources of conflict may now be re-interpreted as examples of confusion caused by different views of what problems the discipline tackles, how it goes about investigating them and how this relates to the decision-making process.
Automatically-controlled analyser for intererograms
Authors: Newborough M. , Batty W.J. , Probert S.D.
Published: August 2008

A simple low-cost digital photogrammetric system for interpreting Mach-Zehnder interferograms is described. The associated software permits the rates of heat transfer occurring within test cells of two-dimensional section to be deduced. The interferograms may be analysed quantitatively much more rapidly, and with less supervision, via this facility, than by the laborious conventional technique of using a travelling microscope.
Violence, Battering, and Psychological Distress Among Women
Authors: GELLES RICHARD J. , HARROP JOHN W.
Published: August 2008

Descriptive and clinical accounts of wife abuse consistently report a high incidence of depression and anxiety among samples of battered women. However, these studies all suffer from methodological shortcomings such as nonrepresentative samples, small sample size, and lack of comparison groups. This study corrects many of the methodological shortcomings of previous studies and analyzes reports of psychological distress among victims of violence and abuse by examining data from the Second National Family Violence Survey. A national probability sample of 6,002 households comprised this survey. The examination of the effects of violence is based on an analysis of the information provided by 3,002 female respondents who lived with their husband or male partner, or who had been separated from their husband or male partner less than 12 months at the time of the interview. Women who reported experiencing violence and abuse also reported higher levels of moderate and severe psychological distress. Multivariate analysis indicated that violence made an independent and nonspurious contribution to the psychological distress experienced by women.
Emotional and Behavioral Difficulties in Sexually Abused Girls
Authors: MANNARINO ANTHONY P. , COHEN JUDITH A. , GREGOR MICHELE
Published: August 2008

This study investigated the kinds of emotional and behavioral difficulties exhibited by sexually abused girls. Ninety-four sexually abused girls ages 6-12 were compared with 89 clinical controls and 75 normal controls. Assessment measures included the Children's Depression Inventory (CDI), State-Trait Anxiety Inventory for Children (STAIC), the Piers-Harris Children's Self-Concept Scale, and the Child Behavior Checklist (CBCL parent version). All findings with the self-report measures were nonsignificant except on the STAIC A-State scale in which abused subjects were significantly more anxious than both control groups. On the CBCL, the sexually abused girls and clinical controls were significantly more pathological than the normal controls on the total behavior problems scale, internalizing and externalizing scales, social competence scales, and seven of nine subscales. Subgroup analysis of the sexually abused group (e.g., intra- versus extra-familial abuse, etc.) did not result in any significant findings. Findings are compared with those from other recent empirically sound investigations in the child sexual abuse field.
Depression, Anxiety, and Behavior Problems Among Victims of Father-Child Sexual Assault and Nonabused Siblings
Authors: LIPOVSKY JULIE A. , SAUNDERS BENJAMIN E. , MURPHY SHANE M.
Published: August 2008

The empirical research on the immediate effects of sexual abuse on child victims has yielded inconsistent results. Studies utilizing parent reports of children's behavior suggest that sexually abused children display more behavior problems than general population norms and children drawn from the general community, but display fewer problems than children seen in clinical populations. Few studies using standardized measures and comparison groups have assessed children's self-reported emotional difficulties. The present study compared the behavioral and emotional problems of children abused by a father (or other adult male functioning as a caretaker) with a comparison group of nonabused siblings drawn from the same families. Both the mother and the father/perpetrator completed parent rating scales on their children's behavior. In addition, children completed standardized self-report measures of depression, anxiety, and self-esteem. Results indicated that both mothers and father/perpetrators perceived the sexually abused children to display more behavior problems than nonabused siblings. Victims reported significantly higher levels of depression than did nonabused siblings. Both victims and nonabused siblings reported significant problems related to self-esteem.
Life on the Streets
Authors: SIMONS RONALD L. , WHITBECK LES B. , BALES ANDREW
Published: August 2008

Life-style/exposure theory and research findings concerning the consequences of criminal victimization were used to generate a set of hypotheses concerning the causes and consequences of criminal attack among the homeless. The sample for the study consisted of 79 homeless people residing in a midwestern state. The results largely supported the predictions. Employment problems, substance abuse, and, to a lesser degree, a history of psychiatric treatment increased involvement in a life-style based on desperate survival strategies (e.g., panhandling, rummaging through dumpsters, collecting cans, etc.). High utilization of these survival strategies was associated with high risk of criminal victimization. Being the victim of criminal attack, in turn, reduced feelings of self-efficacy and increased psychological distress.
Stress Responses of Children to Sexual Abuse and Ritualistic Abuse in Day Care Centers
Authors: KELLEY SUSAN J.
Published: August 2008

The purpose of this study was to examine the effects of sexual abuse and ritualistic abuse of children in day care settings. The sample was composed of 134 children; 67 children who were sexually abused and ritually abused in day care centers were compared on the Child Behavior Checklist with a carefully matched group of 67 nonabused children. Findings indicated that sexually abused children had significantly more behavior problems than did the nonabused children. Sexual abuse involving ritualistic abuse was associated with increased impact as well as increased severity in the extent of the sexual, physical, and psychological abuse the children experienced.
The Context of Anti-Gay Violence
Authors: HEREK GREGORY M.
Published: August 2008

Hate crimes against lesbians and gay men occur within a broader cultural context that is permeated by heterosexism. Heterosexism is defined here as an ideological system that denies, denigrates, and stigmatizes any nonheterosexual form of behavior, identity, relationship, or community. It operates principally by rendering homosexuality invisible and, when this fails, by trivializing, repressing, or stigmatizing it. This article focuses upon the nexus between cultural heterosexism and individual prejudice against lesbians and gay men. Key components of the ideologies of sex and gender from which heterosexism derives are identified: (a) the personal-public dichotomy, (b) the stigmatization of particular forms of sexuality, and (c) the linkage of heterosexuality to gender-role conformity. Supported by these ideological underpinnings, cultural heterosexism fosters individual anti-gay attitudes by providing a ready-made system of values and stereotypical beliefs that justify such prejudice as “natural.” By imbuing homosexuality with a variety of symbolic meanings, cultural heterosexism enables expressions of individual prejudice to serve various psychological functions. Further, by discouraging lesbians and gay men from coming out to others, heterosexism perpetuates itself. Recent social trends that may affect the ideology of heterosexism are identified, and their potential for reducing anti-gay prejudice is discussed.
Conceptualizing Anti-Gay Violence
Authors: HARRY JOSEPH
Published: August 2008

Anti-gay violence is here viewed as being the result of immature males fulfilling sexual status needs. Through such violence they reaffirm their commitment to heterosexuality in a way visible to their peers. Anti-gay offenders are divided into activists, who seek out homosexual victims; opportunists, who victimize gays and lesbians as occasions arise; and a much larger number who abandon any helping-citizen role when faced with such violence by others. Activists resort to gay-defined places to find victims; opportunists use other cues to identify victims. Chief among the cues used by offenders are behaviors and deportments that depart from traditional gender roles. Visibility of the victim as homosexual plays a dominant role in distinguishing gays or lesbians who have been assaulted from those who have not.
The Ecology of Anti-Gay Violence
Authors: EHRLICH HOWARD J.
Published: August 2008

This article discusses how prejudice and violence directed at lesbians and gay men are unique and how they are similar to other forms of prejudice and violence in American culture. The article begins with a brief discussion of how children learn prejudice in general and speculates about the possible origins of anti-gay prejudice in particular. Then, violence in American society is discussed, and the concept of “ethnoviolence” is introduced to refer to violence motivated by a desire to do harm to an “other” who represents a group against which the attacker is prejudiced. The assumption that most anti-gay violence is perpetrated by young males is rejected as biased because it is based only on reported cases. The characteristics of the attacker often are not known and, where known, are likely to vary according to the site of the attack. The article concludes with a brief discussion of the psychological impact of ethnoviolence on victims (who are more traumatized than victims of other crime), on witnesses, and on researchers and service providers.
Violence and Victimization of Lesbians and Gay Men
Authors: GARNETS LINDA , HEREK GREGORY M. , LEVY BARRIE
Published: August 2008

This article describes some of the major psychosocial challenges faced by lesbian and gay male survivors of hate crimes, their significant others, and the gay community as a whole. When an individual is attacked because she or he is perceived to be gay, the negative mental health consequences of victimization converge with those resulting from societal heterosexism to create a unique set of problems. Such victimization represents a crisis for the individual, creating opportunities for growth as well as risks for impairment. The principal risk associated with anti-gay victimization is that the survivor's homosexuality becomes directly linked to her or his newly heightened sense of vulnerability. The problems faced by lesbian and gay male victims of sexual assault, and the psychological impact of verbal abuse also are discussed. Suggestions are offered to assist practitioners in helping the survivors of anti-gay hate crimes.
Anti-Gay Violence and Mental Health
Authors: HEREK GREGORY M. , BERRILL KEVIN T.
Published: August 2008

Empirical studies are urgently needed of the scope and prevalence of anti-gay violence, its mental health consequences, its prevention, and institutional response to it. Researchers should seek data from a variety of sources, use representative samples whenever possible, use reliable and valid measures and methods, and design studies that are longitudinal and prospective. Each of these components of a research agenda for studying anti-gay violence and hate crimes is described.
Self-Report of Crimes Committed by Sex Offenders
Authors: WEINROTT MARK R. , SAYLOR MAUREEN
Published: August 2008

Using a computer-administered interview, self-reports of past criminal behavior were obtained from 99 institutionalized sex offenders. The sample contained both rapists and child molesters who had been mandated to receive specialized treatment. Offenders disclosed an enormous amount of undetected sexual aggression, a finding consistent with other self-report studies. Also striking was the high rate and variety of nonsex offenses. According to interview responses, nearly 20,000 nonsex crimes were committed during the year prior to institutionalization, with rapists contributing a disproportionate share. Still, child molesters, including those whose only known crime was incest, were very active in assault and property crime. The potential for utilizing sex offender self-reports in empirical research is discussed. Preliminary evidence of validity is presented.