bluuebunny/crossref_metadata_2025 huggingface dataset:
Creating a More `Just' Order
Authors: Birdsall Andrea
Published: November 2007

This article analyses the creation of the International Criminal Tribunal for the Former Yugoslavia (ICTY) in light of its potential for creating and institutionalizing justice norms in international society. The theoretical and analytical framework is based on the English School of International Relations and its central conflict between order and justice. The framework integrates a constructivist approach and the `norm life-cycle' to explain the dynamic process of norm emergence and institutionalization in international society. I argue that establishing the ICTY, despite a number of problems resulting from the way it was set up, constituted an important precedent for multilateral action towards institutionalizing respect for the rule of law and principles of individual justice. This suggests that these norms are being taken increasingly seriously and are being given priority over other fundamental principles of order, such as sovereignty and non-intervention. The ICTY's establishment constitutes a significant development in international politics and law and is evidence of the international society's move towards increased norm internationalization. The ICTY also contributed to the establishment of the International Criminal Court and the further institutionalization of human rights norms in creating a more just order.
Do States Play Signaling Games?
Authors: Igoe Walsh James
Published: November 2007

The study of international conflict and cooperation has long drawn on game theory for insights. Recent developments have made the assumptions of game theory more realistic. Particularly important is the development of signaling games, which analyze situations when decision-makers lack complete information about their environment. Signaling game logic has been applied to many areas of international politics in the past decade, including decisions to go to war, crisis bargaining, international economic negotiations, regional integration, and the foreign policies of democratic states. The signaling games approach assumes that states are unitary actors with a single preference ordering and set of beliefs. I relax this assumption by developing an informal model in which decision-makers can hold different prior beliefs and preferences, and investigate this model's usefulness by analyzing how the United States responded to the more cooperative foreign policy signals initiated by the Soviet Union under Gorbachev. This step further deepens the realism of game-theoretic applications to foreign policy by explaining how political conflict among domestic actors influences foreign policy choices.
Homeschooling and Racism
Authors: Levy Tal
Published: November 2007

This article examines the diffusion of homeschooling legislation throughout the 50 states. Event history analysis is used to assess why certain states adopted homeschooling legislation and why some states adopted such legislation earlier than others. Results show that several state-level characteristics are associated with higher odds of enacting homeschooling legislation of which the most noted is state school segregation levels. The data suggest a correlation between racism and the geotemporal diffusion of homeschooling legislation.
Construction and Initial Validation of the Worldview Analysis Scale (WAS)
Authors: Obasi Ezemenari M. , Flores Lisa Y. , James-Myers Linda
Published: November 2007

This study describes the development of the Worldview Analysis Scale (WAS), an instrument designed to assess the way in which people perceive, think, feel, and experience the world. Four studies were conducted to describe the scale development of the WAS and to assess its psychometric properties. Eight hundred sixteen African, African American, European, European American, and multiethnic participants served as the validation sample. Exploratory and confirmatory factor analyses provided evidence for seven subscales: materialistic universe, spiritual immortality, communalism, indigenous values, tangible realism, knowledge of self, and spiritualism. MANOVA analyses found evidence for cultural differences in worldview at the ethnic level of analysis. Results indicated favorable reliability, validity, and factor structure indices for the WAS. Applications of the WAS in culturally competent research, training, and psychotherapy are discussed.
Improvement of Cell Opening by Maintaining a High Temperature Difference in the Surface and Core of a Foam Extrudate
Authors: Lee Patrick C. , Guangming Li  , Lee John W.S. , Park Chul B.
Published: November 2007

This article presents an extrusion-based, open-cell foaming process using thermoplastic polymers such as polystyrene (PS) and polycarbonate (PC) with supercritical CO2. Our previous studies have indicated that a cell opening can be promoted by inducing: (i) a nonhomogeneous melt structure by cross-linking, polymer blending, or filler compounding, (ii) cell-wall thinning by a high volume expansion ratio while maintaining soft cell walls, (iii) cell-wall thinning by a high cell-population density, and (iv) plasticization of the soft region of the cell walls with a secondary blowing agent. Until now, the foam extrudate temperature across the cross-section was maintained uniformly for the simplicity of the experiments. In this study, the significant temperature difference between the core and surface of the foam extrudate was induced by surface cooling method. This method increased the chance of cell opening by: (i) increasing the core temperature of the foam extrudate and thereby softening the cell walls, and (ii) decreasing the foam surface temperature to prevent gas loss and thereby increasing the internal gas pressure within the cells. The effects of CO2 content, surface quenching, die geometry, and temperature on foam morphologies were investigated. Low-density, microcellular, open-cell foams were successfully produced. The large intercellular pores were observed from micrographs for both PS and PC foams at optimum processing conditions.
Polypropylene Foaming in a Reactive Process
Authors: Frounchi Masoud , Sharif-Pakdaman Ali , Mousavi S.A. , Dadbin Susan
Published: November 2007

Long-chain branches are incorporated into the molecular backbone of a polypropylene (PP) in a foaming process. The branching of PP occurs by radical reactions of dicumyl peroxide and a tri-functional monomer, trimethylol propane trimethacrylate. Use of peroxide without tri-functional monomer results in scission of PP molecular chains and significant reduction in melt viscosity. The increase in melt viscosity in conjunction with the flow ability of the modified PP indicates that the polymer has a branched structure. Melting temperature of PP remains unchanged with branching reactions implying that reactions occur mainly in amorphous regions of PP. The improvement in melt strength and strain-hardening of the modified PP is examined by a batch foaming process. The foaming process conditions are optimized for the level of blowing agent, time and temperature of process, and talc content as nucleating agent. The formation of closed and evenly distributed cells in the foam structure verifies improvement in the rheological behavior of modified PP resulting from the presence of long branches in the molecular structure.
The Rotational Molding Characteristics of Metallocene Polyethylene Skin/Foam Structures
Authors: Archer E. , Harkin-Jones E. , Kearns M.P. , Fatnes A.-M.
Published: November 2007

This article reports on the results of ongoing work in which the foaming characteristics of metallocene-catalyzed linear low density polyethylenes for rotational molding are investigated. Earlier publications related rheological and thermal parameters to the polymer structure and mechanical properties and found that metallocene polyethylene can be used in rotational foam molding to produce a foam that will perform as well as a Ziegler-Natta catalyzed foam. Through adjustments to molding conditions, the significant processing and physical material parameters, which optimize metallocene catalyzed linear low-density polyethylene foam structure, have been identified. This article details the optimum processing route for the production of two layer skin/foam parts using the drop box method.
Evaluation and Control Principle of the Crepe Effect on Fabrics
Authors: Yang Xu-Hong , Li Dong-Gao
Published: November 2007

Fabrics made up of both raw silk and other fibers can form a kind of peculiar visual texture, which is know as the crepe effect, on fabric surfaces. However, the level of crepe is difficult to control. We put forward a method using image analysis and fractal geometry to evaluate the visual effect of creping, and analyze the relationships between the bending shape of yarns and the visual effect of creped fabrics. The results indicate that it is possible to control the crepe level by adjusting the fabric breadth during the breadth drawing process.
Worsted Cashmere Top and Yarns Blended with Low or High Curvature Superfine Merino Wool
Authors: McGregor B.A. , Postle R.
Published: November 2007

In this replicated experiment, we investigated the impact of cashmere on blends with superfine wools on the quality of tops, rovings, and worsted spun yarns. We also investigated the relative performance of soft, low crimp/low fiber curvature superfine wool when compared with cashmere and also when compared with traditional high crimp/high fiber curvature superfine wool in pure and blended yarns. The results indicate both the cashmere blend ratio and fiber curvature/crimp of wool affected processing requirements and the attributes of worsted pure and blended tops, rovings, and yarns. Adding wool to cashmere improved the processing of cashmere roving and reduced yarn faults. Mean fiber curvature was a good predictor of yarn hairiness and yarn tenacity.
Paul Sérant and the extreme right's rhetoric of antithesis
Authors: Frey Hugo
Published: November 2007

The starting point for this article is Paul Sérant's novel, Le Meurtre rituel (1950). It is a significant work for political and cultural historians because it reveals a dominant rhetorical perspective common to many other literary and non-literary texts written by extreme right-wing intellectuals in France. In particular the article highlights how Sérant's novel exemplifies the group's fascination with the idea of polarity: that is to say dramatic comparisons between seemingly contradictory concepts. Certainly, this aspect of Sérant's novel foreshadows the thesis presented in his better-known historiography, Le Romantisme fasciste (1959). It also perpetuates themes which were common in the work of Henry de Montherlant and Drieu la Rochelle, among others.

The dominant `polarity' theme running through Le Meurtre rituel supported Sérant's encouragement for a U-turn from the corrupt political space of Fourth Republic France to a new and rich spiritual zone. The article explores how this lesson was commonly taken up in the 1950s by other right-wingers who, like Sérant, also searched for the `sacred' in a variety of esoteric schools of thought. It will also highlight the historical roots of the esoteric drift and examine its after-e fects, notably its influence on thinkers associated with the 1970s nouvelle droite . However, Sérant did not manage to execute all of the inversions encouraged in his rhetoric. The article concludes with consideration of Sérant's failed exchange: his retention of the anti-Semitic trope of ritual murder in the novel.
Quantisation errors in digital filters and their dependence on sampling frequency
Authors: Forsythe W.
Published: November 2007

This article examines the three sources of quantisation error in digital filters for three filter structures and presents expressions for their evaluation. The effect on these expressions of changing the sampling interval is assessed and it is shown which types of quantisation error increase and which decrease with sampling frequency and how this depends upon filter structure.
Strategic microworlds and system dynamics modelling
Authors: Morecroft John D. W.
Published: November 2007

In the past ten years, system dynamics has become more accessible to managers and more applicable to strategic issues. This paper reviews developments in software, theory, gaming and methods of simulation analysis that have brought about this change. Together, these developments allow modellers to create computer-based learning environments (or microworlds) for managers to 'play-with' their knowledge of business and social systems and to debate strategic change.
The use of system dynamics in manufacturing systems engineering
Authors: Edghill Jane , Towill Denis
Published: November 2007

This paper considers the characteristic dynamic behaviour associated with basic manufacturing system designs. In studying such systems the focus will be on three fundamental flows: orders; materials; and information. Of specific interest is the influence of these flows on scheduling decision rules based on stock levels and/or product order rates, as well as how information is passed through the system. Thus it is the optimum combination of feedforward and/or feedback flow paths in a manufacturing-system design which is being sought.

This paper will propose a 'middle ground' between two categories of technique used when considering dynamic behaviour - i e, building models using continuous computer simulation packages and alternatively using models capable of mathematical solution. It is proposed that mathematical models, of limited complexity, can provide the necessary insight to guide the design and appraisal of live system models built with a continuous computer package.

The paper concludes by developing the idea that a generic application in the study of scheduling strategies for live manufacturing systems.
Minimisation of computation for digital controllers
Authors: Goodall R.M.
Published: November 2007

A novel Structure is described and analysed which has a number of advantages for the practical implementation of recursive digital filters in control applications. It is based upon the use of an established alternative to the usual z-1 delay operator, but this has been developed into a standard form called a δ filter which is both robust and versatile.

The advantages are shown to be in the simplicity of implementation, including the determination of word-lengths for the coefficients and variables. First- and second-order filter structures are given in detail, and simulations presented to demonstrate the operation of a few typical filters. Significant reductions in computation requirements are possible using the δ filter.
Active position control of stepping motors with flexible transmission shaft
Authors: Firoozian R. , Bajir J.G.
Published: November 2007

In this paper the authors present an active control algorithm for position control of stepping servomotors with flexible transmission shaft. A non-linear mathematical model is derived to describe the dynamic behaviour of the system. To implement the full state-variable active-control technique, the non-linear model is first linearised. It is shown that the full state variables could be used in a closed-loop controller to introduce damping in the eigenvalues of the system. For realistic application of active control, a state estimator (observer) is used to construct the full state variables from a single measured signal. The estimated state variables are fed in the controller to generate the control signal.

It is shown that this method facilitates the introduction of damping in all eigenvalues of the system and so eliminates the undesirable oscillation due to the flexibility of the transmission shaft. Furthermore the effectiveness of linear control algorithm on the non-linear system is studied.
A simple approach to the decoupling of multivariable control systems using output feedback
Authors: Forsythe W.
Published: November 2007

Considering first a 2-square plant, it is shown how the elements of the compensating matrices may be chosen in a simple manner to create a non-interacting system with desirable dynamic properties; the results are then gereralised to show that the same scheme, with little alteration, can be used on the general n-square system.
An optical system for determining the positional accuracy of a robot
Authors: O'Connor B.
Published: November 2007

To test robot position and path accuracy and repeatability, an optical system was developed to measure positional accuracies based on a position-sensitive detector. The paper shows how the accuracy of a system using the PSD device may be improved significantly through using computer based accuracy enhancement techniques. Results of measurements carried out on robots are presented. The success of the system suggests possible application in other areas requiring accurate position location.
A digital phase-shift-keyed technique for narrowband system identification
Authors: Henderson I.A. , McGhee J.
Published: November 2007

Maximum-entropy binary test signals using microcomputer software are used for real-time interrogation of control systems to evaluate frequency response information. The most commonly used of these test signals spread their energy among known baseband frequencies of octave and/or decade ratios starting with the fundamental. Digital phase-shift-keyed modulation is used to design new zoom binary test signals, which use either a finite squarewave or a compact octave binary modulating signal. A zoom factor, or zoom factors with multiphase-shift-keyed modulation, are used to concentrate the test signal energy in an ever decreasing bandwidth on either side of a selected suppressed carrier. This allows a more selective system identification by a microcomputer in the form of frequency information, with high spectral resolution, about a specified central frequency. These novel binary interrogation signals are used to 'zoom in' on the closed-loop maximum magnification of a lightly damped DC position servo and highlight the gain margin of an air temperature control system.
Model validation: philosophy, methodology and examples
Authors: Carson E.R. , Flood R.L.
Published: November 2007

This paper proposes an integrated framework within which philosophical and methodological issues relating to model validation should be set. The viewpoint adopted is more expansive than that of traditional scientific rationality. Rather, it is suggested that there are several ways of 'dividing up reality', each of which has an associated rationality, dependent on purpose and problem context. Modelling methodology is then considered emphasising the role of validation 'sub-methodologies'. Examples are presented, chosen from the domains of physiology and medicine, which illustrate some of the major issues of model validation.
Predictive criteria for the optimisation of a vibrating-reed transducer
Authors: Mahgerefteh Haroun , Al-Khoory Hassan
Published: November 2007

The optimisation of a vibrating-reed technique which is capable of measuring various properties such as fluid pressure, density, viscosity and mass under aggressive environments is described. The unit operates simply by utilising a stiff reed which is clamped securely at an intermediate point along its length. One end, mounted with an inert concentrated mass is exposed to the test environment, while the other is mechanically excited so that the system is sinusoidally vibrated at its first modal resonant frequency. Changes in the resonant conditions then reveal information about the physical properties of the fluid under test. The finite-element method of analysis adopted for a cylindrical reed reveals that optimum operating conditions in terms of output response are achieved with maximum reed diameter, minimum reed length and minimum mass ratio of the attached mass to that of the reed. The stability criteria on the other hand indicate that most stable operation corresponds to the clamping of the reed as far away as possible from its centre. The analysis also considers the effect of choosing different reed materials and shapes on the system's resolution and sensitivity. Most of the theoretical predictions are also confirmed by experimental evidence.
Remote sensing of water pollution by lasers
Authors: Ahmad S.R.
Published: November 2007

Non-elastic scattering of laser light by molecules manifests itself in characteristic fluorescence spectra and unique Raman scattered lines. Therefore, pollutants in water can be identified, and their concentration deduced, by remotely detecting and analysing such spectral signals. Spectral signatures of some samples, commonly encountered as water pollutants, are recorded and analysed. The methodologies, the present status and the future prospect of remote monitoring of pollution in surface waters and real-time non-invasive detection of pollution for the water and waste-water process control are reviewed in this article.
Optical-fibre ring-main multiplexing optically powered hybrid OFS
Authors: Cheshmehdoost A.
Published: November 2007

Field-installable duplex optical-fibre couplers based on bending effect are described. Addition of these couplers to a high-integrity optical-fibre bus is possible without interrupting operation. The duplex couplers are designed to have a variable tapping ratio, to power a hybrid optical-fibre sensor (OFS) and to relaunch a digital output from the sensor into the bus. A low-power microelectronic sensor which is optically powered via the bus fibre is described, and a two-sensor system configuration has been successfully demonstrated.
A new measurement system for high-resolution tactile imaging
Authors: Gelaky R. , Keating D.
Published: November 2007

Over the last 12 years, consistent effort has been directed toward the development of a usable sense of touch for machines. This research has been somewhat overshadowed by the ongoing development in artificial vision, but has remained important for specialised object identification applications. Over the aforementioned period, a great number of different transduction and measurement principles have been adopted, each claiming to offer certain desirable characteristics. The last five years have shown a reduction in the variation of methods being pursued.

One of the main surviving transduction methods is based upon the variable-separation capacitive transducer. The method of capacitance measurement, adopted by two major American research teams developing such sensors, has been a simple charge amplifier. Their measurement methodology has limited the spatial resolution, or inter-tactel separation, and slowed the acceptance of an otherwise near ideal taction device.

This paper describes the development, a design model and subsequent construction, of a variable-separation capacitive tactile system which employs an improved measurement system. The system permits the sensor spatial separation to be reduced to the limits of the physical construction method and no longer be confined by the measurement technique. This will, it is hoped, lead to the construction of larger, more densely packed, arrays capable of low-cost, efficient object recognition. The sensor performance, possible applications and intended direction for further research are also discussed.
The steering control of an experimental autonomous vehicle
Authors: Pears N.E. , Bumby J.R.
Published: November 2007

Experimental results relating to the steering control system of an experimental autonomous vehicle operating in a pre-defined and structured environment are presented. A method of steering control is formulated which relates second-order criteria, such as rise time and damping factor, to the parameters of the control system. With the control system described, the vehicle can track a path of constant heading with very little steady-state error and, if the control parameters are chosen in the correct ratio, it will respond in a critically damped fashion to the step disturbances which are generated by position corrections. For a curved path, demand curvature is treated as an input to the system in order to eliminate steady-state offset errors in tracking. In order to make the vehicle's performance independent of velocity, control parameters are derived as simple functions of velocity. This has the effect of allowing the vehicle to manoeuvre more tightly at lower speeds, and makes use of the increased availability of drive-system torque at such speeds. In order to prevent stalling of the stepper-motor drive system at large changes in demand curvature, a method of limiting the rate of steering is described.
The real-time application of Variable Structure System (VSS) controllers: an experimental comparative study on a simple robot arm
Authors: Richards R.J. , Reay D.S.
Published: November 2007

As an initial step in a programme to test VSS controllers on robot arms, the VSS control strategy is applied to a single link and revolute joint. Experimental results demonstrate the successful use of this type of control and indicate the advantages to be gained by some of its suggested modifications.
Stabilisation of chaotic biological systems
Authors: Endean V.G.
Published: November 2007

A novel adaptive procedure for stabilising certain types of non-linear, time-varying, discrete system is described. Its application to one-dimensional unimodal systems, which are particularly important in the dynamic modelling of biological populations, is illustrated. An unusual feature is that the controlled system automatically locates a natural equilibrium state, as opposed to being driven to a pre-defined set point. This has the important advantage in the control of biological populations of minimal interference with the system. Robust equilibrium is maintained, not only in the period-doubling and chaos regions, but also deep into the catastrophically unstable extinction region.
A comparison of different scheduling techniques for H-infinity controllers
Authors: Hyde R.A. , Glover K.
Published: November 2007

Several approaches to designing schedule H-infinity control systems are compared. These include a controller switching approach and also parameter scheduling of an observer representation of the controller. They are illustrated by application to a Generic VSTOL Aircraft Model (GVAM) supplied by The Royal Aerospace Establishment (RAE) at Bedford. The switched design has been tested on the simulator at RAE Bedford. The linear H-infinity designs make use of a loop-shaping followed by robust stabilisation to additive perturbations of a normalised coprime factorisation of the shaped plant. The different scheduling approaches are compared with respect to achieved robust stability levels, performance and complexity of implementation.
Submarine periscope-depth depth-keeping using an H-infinity controller together with sea-noise-reduction notch filters
Authors: Marshfield W.B.
Published: November 2007

The paper shows the usefulness of H-infinity techniques in designing a depth-control autopilot for a submarine at periscope depth. It also shows that a significant reduction in nugatory hydroplane activity can be effected if tracking notch filters are included in the autopilot inputs to discriminate against wave frequencies.

The results of simulations of a submarine at periscope depth in sea-state 5 in bow and stern seas are given. The simulation uses a full six-degrees-of-freedom nonlinear mathematical model of the submarine.

Depth control is maintained using an H-infinity controller designed using a linear mathematical model of the submarine. The inputs to the controller are depth and pitch and the outputs are bow and stern hydroplane angles. Both input signals contain noise at wave frequencies which cause nugatory motions of the hydroplanes.

Previous work, (Daniel and Richards, 1983), with LQG (Linear, Quadratic, Gaussian) controller designs showed that notch filters, designed to track the predominant wave frequency, could be used to reduce the hydroplane activity at periscope depth. This technique has now been applied successfully to an H-infinity controller.
The Viable System: An introduction
Authors: Leonard Allenna
Published: November 2007

This article provides an introduction to the Viable System Model (VSM). The importance of organisational identity is described. The VSM is shown to be a model which enables the recognition of patterns necessary for survival within organisations. The five systems of the VSM are outlined. Emphasis is given to the distinctive channels of communication made explicit by the VSM. The importance of developing common perspectives and common languages is highlighted. The VSM is put forward as a useful contribution in this endeavour. Examples were chosen from the public sector.
Managing change with VSM and STS: an experiential approach
Authors: Leonard Allenna
Published: November 2007

This article describes a simulation exercise using Stafford Beer's Viable-Systems Model. The workshop, titled Managing Change, was presented as a collaborative event by the Viable Systems International Partnership and Socio-Technical Systems Associates to participants familiar with socio-technical systems design from previous workshops. The simulation was based on an STS experiential demonstration of traditional and self-managing team motivation and productivity. Participants were assigned roles corresponding to the five functions of the VSM for two sessions. The first session was in real time with several environmental disturbances. The second was done as a walk-through, one system and one disturbance at a time. The exercise underlined that practice is required before newly learned methods can be applied confidently in turbulent situations.
A differential system simulator for process dynamics and control design
Authors: Zhu Zhong-Xiang , Jutan A.
Published: November 2007

A Simulation System- MDSS- is developed for the Dynamic Simulation of Systems described by ordinary and partial differential equations.

MDSS has unique features in system management, structure design, data processing and input-output interface, in addition to its powerful equation-solution functions with a built-in integration 'engine', which allows for interactive analysis of complec dynamic systems and design of control loops.
Stabilisation of dynamic saturating systems with structured plant perturbations
Authors: Chou Jyh-Horng
Published: November 2007

This paper investigates the robust stabilisation problem of uncertain dynamic systems with actuator saturation. A simple method, developed recently for the elemental plant perturbation bound analysis, is extended to obtain the robust stabilisation condition. Confirmation is given that a state feedback controller design will satisfy the requirement of robust stability under plant perturbations. An example is given to demonstrate the use of the proposed approach.
Robust and adaptive control of a multi-variable system
Authors: Wu Wen-Teng , Tseng Ching-Guey
Published: November 2007

An on-line robust control and robust adaptive control of a multi-variable system has been developed to solve the problem of plant/model mismatch. An on-line stability index is proposed for stability indication of the control system. Although very small mismatch can be handled by conventional feedback control, moderate and large mismatch must be corrected by on-line robust and robust adaptive control, respectively. Regarding the former, the control algorithm is based on tuning the parameters of designed filters, and the tuning method depends on the robust stability index which is on-line determined. Regarding robust adaptive control, system identification is carried out, and the identified model replaces the original one. Control of a continuous stirred tank reactor (CSTR) is presented to illustrate the proposed method.
A generalised algorithm for polarity correlation estimation using binary patterns
Authors: Harba M.I.A.
Published: November 2007

A recently developed binary-pattern correlator uses the binary patterns of a group of successive samples of the polarity-sampled signal for correlation estimation. At high sampling rates (compared to the bandwidth of the signal), only a limited number of polarity changes may take place within a finite signal duration. Thus, a finite interval of a polarity-sampled signal may only have a limited set of binary patterns. The correlator estimates the frequency of occurrence of these patterns on-line and stores them in tables. The actual correlation coefficients are then deduced from these tables. Because the number of patterns is limited, efficient operation results.

A general binary-pattern correlation algorithm is presented, with examples implemented on a Z-80 microprocessor. These examples represent different implementations of the algorithm. They differ in the number of signal samples effectively input each time, and in the size of the frequency of pattern-occurrence tables. As a result they have different sampling rates, and different off-line processing intervals. However, there is a trade-off between the achieved sampling rate and the amount of off-line processing.
Self-tuning control of non-linear plant - a bilinear approach
Authors: Goodhart S.G. , Burnham K.J. , James D.J.G.
Published: November 2007

This paper describes a collaborative project involving British Gas plc, Midlands Research Station, Solihull, the Control Theory & Applications Centre of Coventry University, the Energy Technology Support Unit, Harwell and Eurotherm Controls Ltd, Worthing. The project is concerned with the design, development and real-time evaluation of a new bilinear self-tuning controller, which is primarily being aimed at improving temperature control of high temperature gas fired industrial heating plant. The largest energy savings are anticipated on plant experiencing variable operating conditions which may occur under continuous operation or during batch process changes. To provide for a realistic comparison, the performance of the bilinear self-tuner is compared to that achieved using a standard industrial auto-tuned PID controller when applied to an industrial test furnance.
The dynamic thermometer: an instrument for fast measurements with Platinum Resistance Thermometers
Authors: Rosemary Taylor H. , Bashir Rihawi M.
Published: November 2007

The 'Dynamic Thermometer' is a versatile instrument used in conjunction with a platinum resistance sensor which is both accurate and fast. It can measure resistance ratio to an accuracy of 30 ppm or better in less than 1 s. The resolution is programmable in the range 15 bits in 0.6 s or 20 bits in 11 s. In the high-accuracy mode, the readings are converted into temperature measurements according to the ITS-90 scale. In the diagnostic mode, the instrument measures the response to a self-heating step function and determines the thermal parameters of the sensor and its housing without removing it from its working position. This information is useful to check the integrity of the sensor and to estimate its response time. In the high-speed mode, temperature is computed from resistance measurements according to the Callendar equation and digitally compensated so that the overall response time is less than the response time of the sensor alone. Examples of measurements made with the instrument are quoted to illustrate its applications.
Comparison studies of point-to-point near-minimum-time control of planar flexible manipulators with multiple links
Authors: Hwang San-Tai , Eltimsahy Adel
Published: November 2007

The objective of this paper is to compare the dynamic behaviour of a near-minimum-time (NMT) controller for planar flexible manipulators by three control schemes; the rigid manipulator control (RMC), the passive flexible manipulator control (PFMC), and the active flexible manipulator control (AFMC). The Lagrange-Euler equation is employed to formulate workable state variable models for both rigid and flexible manipulators. The link flexibility is incorporated by using the method of assumed mode. Simulation results indicate that effects of small link flexibility could not be ignored. Higher torque inputs produce larger tip displacements, and reduce execution times. Simulation results indicate also that tip deflections could be suppressed in highly flexible links with small applied modal torques. However, applied modal torques would prolong the execution time, if they are too small.
On-line hierarchical steady-state optimising control of a power plant using the ISOPE technique with dynamic information
Authors: Augustin P. , Roberts P.D.
Published: November 2007

A new type of hierarchical optimising control algorithm is presented in the paper. A double loop ISOPE (Integrated System Optiniisation and Parameter Estimation) algorithm with price coordination is used, and dynamic model parameter estimation for real process derivatives approximation is employed instead of the difference equation approach, hence overcoming a main disadvantage of previous ISOPE techniques. This method is more suitable for real industrial application and, as an example of possible use, results from a simulation study of a power plant steady-state optimisation example are shown.
On the sampling period in Kalman's algorithm for dead-beat control, and on an extension to non asymptotically stable processes
Authors: de Paor Annraoi M.
Published: November 2007

A formula is derived which relates the sampling period explicitly to the ratio of initial and final values of control sequence in a sampled-data system controlled by Kalman's dead-beat algorithm. An extension to the Kalman controller is presented, which allows all its desirable attributes to be retained when applied to non asymptotically stable processes.
The use of Prolog in the implementation of a Knowledge-based Environment for Modelling and Simulation (KEMS)
Authors: Tanyi E.B. , Linkens D.A. , Bennett S.
Published: November 2007

This paper presents a Prolog implementation of a Knowledge-based environment. Although the design is still piecewise, it throws up several issues which are encountered in such systems, including Knowledge representation, integration of the Knowledge base with other simulation tools into a functional architecture, and Knowledge acquisition. The KEMS environment has been under research and development for some time now, and has evolved through four major stepping stones. These have been reported individually in the literature. The first stepping stone involved the implementation of an expert system based on the AI frame paradigm. This expert system formed the core of the simulation environment and was used to generate simulation models for gas compression and servo systems supplied by British Gas who have been collaborators in the project. The second phase involved linking the expert system core to a graphical front-end and a simulator. In the third phase, a Knowledge Acquisition Module (KAM) was implemented to enable domain experts to model systems using a pseudo-natural language format. Finally, KAM was extended to include object-oriented features. The paper contains several applications of the KEMS and KAM prototypes.
Non-linear and unsteady flow analysis of flow in a viscous flowmeter
Authors: Stone C.R. , Wright S.D.
Published: November 2007

An experimental and theoretical investigation has been undertaken on a viscous flowmeter, with both steady and unsteady flow. The steady flow analysis quantifies the nonlinear effects of entry and exit losses, development length effects and compressibility effects. The steady flow analysis and experiments show that the pressure drop has a quadratic response to flowrate, but that for practical applications a linear approximation will lead to an error of less than 1%.

The unsteadyflow experiments show that it is necessary to integrate the instantaneous flow over a whole number of cycles, in order to obtain reliable values of the mean flow. An analysis of unsteady viscous flow has been used to show how the instantaneous pressure difference measured across the viscous flowmeter can be analysed to give the instantaneous volume flow rate.
An experimental investigation of the dynamic performance of fuzzy logic control
Authors: Wang J. , Jordan J.R.
Published: November 2007

This paper presents the results of an experimental (simulation based) investigation of the effect of scaling factor choice on the step response of a fuzzy logic controlled system. It is shown that if scaling factors are adjusted to give the best step response than small changes of process parameters (eg, time constant and gain) quickly degrade this good performance. Alternatively, if the performance required is degraded from the best step response obtainable by tuning the scaling factors, then scaling factors can be selected to give an acceptable performance over a wide variation of process parameters.
Supervisory Generalised Predictive Control for electro-fluid systems
Authors: Linkens D.A. , Ting C.H. , Mahfouf M.
Published: November 2007

A control engineer is required to design a system to meet the specified desired performance with guaranteed reliability and safety. Reliability and safety are particularly important in the field of process control. However, not only in process control but also in other industrial applications, reliability and safety are emphasised as well as the performance of the controller. The goal of a supervisory structure is to establish the health of a system and design an alarm system for the user in the hope of preventing undesirable consequences. The component is called fault detection and diagnosis (FDI), and a process model-based algorithm is used in this study to monitor the operation of a system. Nevertheless, because stability is a primary requirement of a control system, another requirement of supervision is to guarantee the stability as well as the health of the plant. This is the theme of this paper which combines both control and supervision using GPC.
A Comparison Between the Metrological Performances of Humidity Sensors
Authors: Carotenuto A. , Dell'lsola M. , Vigo P.
Published: November 2007

To compare different methods of measuring humidity can be somewhat complicated because of both the high number of measurable hygrometric parameters and their lack of homogeneity. Given that there are measurement uncertainties, this comparison is possible through the law of propagation of measurement uncertainties. In this paper the authors use a method for calculating the uncertainties in indirect measurements of both relative humidity and humidity ratio and therefore for comparing the performances of different sensors. This comparison is developed, starting from the manufacturer's specification for the more common air humidity sensors. The indirect measurement uncertainties at different dry bulbs are presented using diagrams for each sensor family. The results provide useful information both for analysing the humidity measurement uncertainty of a specific sensor, and for choosing the most suitable sensor for given measurement conditions.
Robust eigenvalue assignment of a PI state feedback controller for discrete multivariable systems
Authors: Zhu Zhong-Xiang , Jutan Arthur , Krishnapura Venugopal G.
Published: November 2007

A PI state feedback controller for multivariable discrete systems is proposed and the issue of robust controller design is addressed. The resulting design structure, in contrast to other schemes, is always controllable and observable and can thus lend itself for the developing of control algorithms using standard methods such as eigenvalue assignment. Robust performance is achieved through a minimum norm design using a matrix pseudo inverse. Simulation example shows the effectiveness of the resulting controller.
Measurement techniques for the performance of multi-point interpolators
Authors: Hollis J.E.L. , Cronk T.E.
Published: November 2007

Methods for assessing band-limited image data interpolator speed and accuracy are addressed. Techniques for the measurement of interpolation performance and an interpolator accuracy test have been developed. Application to synthetic aperture radar image interpolators show that adequate accuracy can be achieved with as low as 4-point interpolation, and that fairly coarse spatial approximation can be used in many practical instances in order to gain a significant improvement in interpolation speed.
Model-based methods for fault diagnosis: some guide-lines
Authors: Patton R.J. , Chen J. , Nielsen S.B.
Published: November 2007

This paper provides a review of model-based fault diagnosis techniques. Starting from basic principles, the properties and limitations of different methods are discussed. The main aim is to give some guide-lines for the use of model-based methods. Accordingly, the problems encountered in both the residual generation and evaluation stages of fault diagnosis have been outlined. A comparison of quantitative and qualitative methods is also given. Finally, the limitation of model-based methods and the alternative and supplementary use of heuristic knowledge are discussed.
An application of a technique for the tuning of multiparameter controllers
Authors: Kocijan Jus , Kosin Peter , Karba Rihard
Published: November 2007

At control system implementation some trial-and-error on-line tuning of the controller is often necessary for performance improvement. This procedure is unfortunately difficult to pursue in some cases due to a high degree of controller complexity and therefore a large number of possible tuning parameters. The problem can be obviated through the implementation of a tuning technique based on sensitivity functions. Systematic adjustments are made on the basis of responses obtained from measurements on the system being tuned. No plant model is needed, in fact only the output responses to certain input signals, in our case step signals, must be available. The approach is illustrated by the aid of the DC motor generator pilot plant.
Observer-based feedback control of a class of discrete-event systems
Authors: Franke Dieter
Published: November 2007

The paper addresses discrete systems with a finite number of states which can be modelled by the state equations of a finite automaton. In contrast to traditional work, the paper is based on arithmetic representations of Boolean functions appearing on the right-hand side of the underlying finite state equations. This allows a unifying view of discrete-event systems and classical discrete-time systems. The paper focuses on the special class of arithmetically linear finite state machines. The design of feedback control using reduced-order observers is extended to this class of systems. The procedure will be illustrated by means of two examples.
Tactile and kinaesthetic feedback in virtual environments
Authors: Taylor Paul
Published: November 2007

Virtual reality technology has great potential for design for assembly, disassembly and maintenance but such manipulation tasks by their very nature involve tactile and kinaesthetic interaction. Consequently, a new generation of tools needs to be developed to provide the appropriate tactilelkinaesthetic feedback to the user in order to complement the traditional visual technology. Three feedback devices will be described arising from research supported by the EPSRC and BRITE-EURAM.

(1) A 2½-D programmable surface using shape-memory alloy wires.

(2) A surface with programmable compliance using electro-rheological fluids. Haptic searching over the surface gives the illusion of the presence of an object.

(3) The Reactabot™ , a robot-like device which provides force feedback to the user and is programmed to mimic the dynamic characteristics of the virtual object and its interaction both with the virtual environment and the operator.