bluuebunny/crossref_metadata_2025 huggingface dataset:
Automatic Weave Diagram Construction from Yarn Positional Data of Woven Fabric
Authors: Shinohara Toshihiro , Takayama Jun-Ya , Ohyama Shinji , Kobayashi Akira
Published: August 2008

We propose a novel automatic weave diagram construction method from yarn positional data of woven fabric. In this work, a set of yarn positional data implies a sequence of center points of a yarn obtained using the yarn tracing method proposed in our previous study. For constructing the weave diagram, the sets of yarn positional data are first divided into warp and weft based on the gradient of a line, which approximates the yarn positional data. The intersections between warp and weft are then calculated using the approximated lines. Then the weave diagram is constructed by comparing the warp positions with the weft positions at all the intersections. The effectiveness of the automatic weave diagram construction method is confirmed by experimentally applying this method to the yarn positional data of a double-layered woven fabric.
Assessing the Wear of the Oxide Layer of a Spindle-neck Coating with a Collapsed Balloon Crown
Authors: Płonka Stanistaw
Published: August 2008

The results of an investigation into the wear of the spindle-neck coating with a collapsed balloon crown of a ring-spinning frame during mating with the yarn under industrial conditions is presented. The investigation included examining the wear of the spindle-neck coating made of aluminum alloy 2024, which was subjected to the following different methods of finishing: grinding with abrasive cloth, burnishing only, and burnishing followed by hard anodic oxidation. The analysis of the process of wear and the thickness of the oxide layer before and after the operation has confirmed that the oxide layer increases the wear resistance by several orders of magnitude. It was also concluded that hard anodic oxidation gives the spindle-neck coating a durability equal to the lifetime of the bearing inserts. We assessed the surface topography by means of microphotography, the yarn kinetic friction coefficient µ k, and the microstructure of the oxide layer before and after the period of operation. This allowed us to find out that the wear of the spindle-neck coating caused by the friction of yarn on the surfaces is determined by the abrasive wear.
Design, Manufacture, and Experimental Analysis of 3D Honeycomb Textile Composites Part I: Design and Manufacture
Authors: Xiaogang Chen  , Ying Sun  , Xiaozhou Gong
Published: August 2008

Textile composites have the advantage of being strong and lightweight over the conventional materials, and thus have found applications in many areas, most notably for materials used in aircraft. In this two-part paper, the engineering design and characterization of 3D honeycomb composites are described on the basis of an attempt to create a novel type of composite material which is extra lightweight and voluminous. The first part of the paper explains the basic concept of 3D honeycomb composites, and the procedure of design and manufacture of 3D honeycomb fabrics and composites. An algorithm has been established to create weaves based on the specification of the 3D honeycomb composite parameters, and this algorithm has been implemented into a computerized procedure which gives accurate solutions for making reinforcing fabrics of this type. It has been demonstrated that 3D honeycomb textile composites with various structural parameters can be engineered. Four groups of honeycomb composites, involving 14 varieties, have been systematically created for the first time in order for the experimental analysis of the honeycomb composites to be carried out. A simple yet effective method for making honeycomb textile composite is described in Part I. The experimental analysis and the results will be described in Part II of this paper.
Objective Evaluation of Soil Release in Fabrics
Authors: Gururajan Arunkumar , Hequet Eric F. , Sari-Sarraf Hamed
Published: August 2008

Soil release is an important attribute of fabrics that impacts their pricing on the marketplace. Currently, stain release is evaluated manually and hence its assessment tends to be subjective. This paper introduces a novel approach based on image analysis for objective evaluation of stain release in fabrics. This system has the capability to accurately detect, localize and grade stains with minimal human intervention. The grades assigned by the system are based on a digitized version of the AATCC soil release replica. The stain detection performance of the system was validated on a large dataset of 360 stain images. The system produced excellent results with a sensitivity (true positive rate) of around 93 percent and specificity (1 — false positive rate) of around 95 percent. Further, a correlation study and analysis of variance were performed using the system assigned grades and the technician assigned grades, and these initial results are very promising.
The modelling of injectors, pumps and compressors in process simulation
Authors: Martin E.N.
Published: August 2008

Control engineering studies during the design of an industrial process frequently use simulation methods which require its operation to be represented in mathematical terms. This contribution reviews the salient features of various types of pumps and compressors encountered in such processes and presents models which embody these properties in a form suitable for use on a computer.

In general, these represent a compromise between the extremes of simplicity and rigour which has proved satisfactory in this context. Each application should, however, be the subject of engineering judgment on the degree of approximation which will be consistent with the quality of the data available and the objectives for which the simulation is being performed.
Frequency domain solution to the optimum multivariable tracking problem
Authors: Grimble M.J.
Published: August 2008

A solution is obtained to the infinite time optimal tracking problem for a multivariable system. The derivation is more direct than the usual approach through Parseval's theorem and it relates Hilbert space gradient techniques to the complex frequency domain.

where W * : Ln2 (0, ∞) → L m2 (- ∞, ∞). By considering the properties of the impulse response matrix it may be confirmed that the system represented by the operator W * has a response (W*y) (t) existing for negative time, even though y is zero for negative time. It is clear that W * represents a non-causal system.
Practical aspects of the identification of process dynamics
Authors: Godfrey K.R. , Brown R.F.
Published: August 2008

The steps to be followed in the identification of process dynamics are developed logically. These steps cover experiment design, the use of physical laws and a priori knowledge, model structure determination, parameter estimation and model validation. The presentation is directed toward guiding the control engineer in industry to the intelligent use of the copious, well-documented supply of theory and case studies. Emphasis is laid upon techniques which have proven practical value.
A frequency response method for control system design
Authors: Hind E.C.
Published: August 2008

A method is shown for the design of series compensators for type 1 and type 0 control systems. It is based on the use of the contour of constant closed loop phase angle, α = - 90°, and assumes second order response specifications such as closed loop relative damping. The compensator parameters are determined from the intersection point of the open loop frequency response locus and a design curve which originates at a design point. The method yields directly an equivalent second order model which may be used to approximate the transient response of the compensated closed loop system.
A study of double mode limit cycles in a resonator controlled oscillator
Authors: Steel G.K. , Sanders S.A.C.
Published: August 2008

A system is described which excites continuous oscillations in a resonator at two frequencies simultaneously. The resonator, typically in the form of a disc, can have modes which are close together in frequency and a double mode oscillator facilitates measurement of the difference in frequency. Such a measurement can be used to accurately determine Poisson ratio for the material of the disc. The resonator is excited by means of a nonlinear feedback loop which is designed to give stable double mode oscillations with frequencies close to the natural modes of the resonator. Several results from describing function theory are used to predict the behaviour of the system and the analysis is compared with the results of an analogue computer simulation.
Threshold fluid logic and its application to knitting machine control
Authors: Burns N.D. , Douglas N.G.
Published: August 2008

Threshold logic holds many advantages over conventional logic when applied to switching network design. The advantages are greatest when the functions are complex. In such cases threshold logic solutions result in fewer gates and interconnections than purely binary solutions. The application of threshold gates to fluid-logic systems can result in cost savings and performance improvements.

Although the logical functions are relatively simple, the use of threshold elements still results in reductions in elements over the purely boolean solution. The success of threshold logic is critically dependent upon the physical structure of the device, its cost, response speed, reliability, etc. Some tentative designs for devices are presented in this paper. Prototypes have been manufactured and during early tests some problems became apparent. Further long term tests are continuing.
The wind tunnel behaviour of a scaled model with a gust alleviation system in a deterministic gust field
Authors: Krag B.
Published: August 2008

The DFVLR and the Dornier aircraft factory are developing in a joint programme a low-cost gust alleviation system for future application in a small twin-engined transport aircraft. The main purpose of this gust alleviation system is the improvement of passenger ride comfort. The gust alleviation system was tested using a scaled down model of the ZKP-research aircraft. All testing was performed in the wind tunnel by means of the installation for dynamic simulation. The investigations have shown that a simple open-loop gust alleviation system can be designed which satisfies the desired conditions. In this paper the wind tunnel technique is described and some results are presented.
Simulation and control for heat treatment
Authors: Tullett A.D. , Hessey M.F. , Smith N.F.
Published: August 2008

A mathematical model simulating the gas carburising of steel components has been developed for the prediction of optimum process parameters. The utilisation of optimised process parameters has given rise to increases in furnace throughput of ~ 20%. The implementation of the optimised process parameters has demanded faster, more accurate process control than that achieved with conventional furnace control equipment. The required degree of control has been achieved with systems based on either a minicomputer or a microcomputer in which furnace atmosphere analysis is effected with oxygen probes.
Integrated control of ship roll and yaw motions
Authors: Broome D.R. , Elias N.R.
Published: August 2008

Conventionally ships are steered automatically using gyroscopic feedback of heading to compare with a demanded course, and the resultant error signal is processed by a standard three-term controller before activating the steering gear to produce a rudder deflection and correct course. Similarly independent active fin stabiliser systems are fitted, measuring roll gyroscopically and using the fins to reduce roll Significant cross coupling has been observed in this multi-variable system, and this has been used to some advantage in an active rudder roll stabilisation system. This paper describes an analogue computer study to assess the advantages of various fin control strategies, to see if significant course keeping improvements were possible, and hence to synthesise an integrated ship control system.
Instrument models for process simulation
Authors: While C. , Hutchinson S.J.
Published: August 2008

The instrument models, described in this paper, are intended for inclusion in larger models of processes and not as detailed models of instruments in their own right. These larger process models can be used either directly for control studies, or for simulation exercises where an estimate of the dynamic response of the process to disturbances is required. The emphasis in this paper is on models for use in digital simulations. The most important message of the paper is that the detail used to model the instrumentation should match the problem one is trying to solve. ?'he modeller should question the need for complex models of instrumentation and avoid over-elaboration whenever possible.
A Volterra series-derived describing function for a motor/variable gearbox/load combination
Authors: Lawrence P.J.
Published: August 2008

A solution to the speed variations of a load driven via a variable ratio gearbox from a non constant speed drive is obtained as a Volterra series. A particular solution is found when the gear ratio is varied sinusoidally. This leads to a simple transfer function, with coefficients varying with input amplitude, which is shown to adequately model the overall dynamics.
A review of the control of depth of anaesthesia
Authors: Chilcoat R.T.
Published: August 2008

This paper is an attempt to provide an exhaustive review of work in the area of automatic control of depth of anaesthesia. It includes systems using both open and closed-loop control and describes 37 papers from 1949 through 1980.
Optimal self-tuning control systems: Theory and application
Authors: Grimble M.J. , Johnsont M.A. , Fung P.T.K.
Published: August 2008

Self- tuning regulators and controllers have proven to be a useful industrial control device. The self- tuning theory upon which these devices are based comprises the two aspects: controller design and system identification. In this first paper the emphasis is on the design, or more correctly, the synthesis, of the controller. In particular, classes of optimal controllers each dependent on a different cost function are discussed. The two most popular controllers- the minimum variance and the generalised minimum variance control laws - are derived in this first part.
Control of manipulators by means of discrete regulators
Authors: Kirdanski N. , Vukobratović M.
Published: August 2008

This paper considers the aspects of forming a discrete approximation of the mathematical model of open active mechanisms. Discretisation of the model of a manipulation system with respect to subsystems has been performed as well as the discretisation of mechanical part of the system. Since the discrete approximation holds only for a range of low values of the sampling period, a sampled-data dynwnic model of the manipulator has been formed Aspects of the synthesis of discrete linear regulators are presented and illustrated by an example of a six-degree-of-freedom manipulator.
The application of an adaptive noninteracting controller to a motor-generator set
Authors: Gooder A.V. , Swanick B.H.
Published: August 2008

Relatively few experimental applications of decoupling theory to actual systems are recorded in the literature. It was decided, therefore, to examine a practical system consisting of a motor-generator machine set controlled by thyristor amplifiers, and to apply a decoupling strategy with adaptive properties to this system. A mathematical model of the coupled system was produced and validated from open-loop steady-state and transient characteristics. The system equations were arranged in state-variable form, and a strategy for decoupling this linearised system was developed theoretically and later confirmed by analogue simulation and actual system tests. It was then necessary to extend this linearised model theory to obtain a generalised nonlinear control strategy in terms of the system output variables; the elements of the feedback and feedforward matrices were made to adapt to the nonlinear effects within the system. Satisfactory decoupling of the appropriate state variables, together with eigenvalue assignment, was achieved both from the analogue simulation of the motor-generator model (linear and nonlinear) and upon the system itself incorporating transducer and equipment design. The results of the work have been engineered into an actual decoupled, adaptive motor-generator machine set.
Solids-concentration measurement and flow measurement of slurries and sludges using ultrasonic sensors with random data analysis
Authors: Balachandran W. , Beck M.S.
Published: August 2008

The flow velocity is measured by cross- correlating the output signals from two axially spaced ultrasonic sensors, similar to the sensors described in Part 1 of this paper.

A meter factor of 0.84 ± 0.02 was observed to calibrate the measured cross- correlation velocity against actual mean flow velocity, for flow of Reynold's number from 3× 10 3 up to 75 × 103. The meter performance was not affected by change in particle size and concentration; small quantities of gas bubbles (up to 5% by volume) do not affect the calibration curve.
Digital displacement transducer using pseudo-random binary sequences and a microprocessor
Authors: Jones B.E. , Zia K.
Published: August 2008

This novel transducer enables measurement of displacement over a large range without undue expense to be made; high resolution is possible. A maximal length pseudo-random binary sequence is laid down as a mechanical track of 1s and 0s. As the moving component traverses the track in a given direction it causes the sequence to be inputted into a microcomputer in which it is compared with a similar sequence generated internally. When the two patterns become identical, then the absolute position of the moving component is defined with a digital output. A second digital track is required for bidirectional displacement. Various transducer configurations are proposed.
Methods for the study of unidentifiable state space models
Authors: Lecourtier Yves , Walter Eric , Bertrand Pierre
Published: August 2008

A model M (θ) is unidentifiable if there exist several values of the parameter vector θ which are associated with the same input-output relation. In such a situation any further use of θ is questionable. A methodology for dealing with unidentifiable state space models is proposed. Some tools are given to set up either a new experiment or a new parametrisation in order to make the model identifiable; others allow us to generate the set of all output-indistinguishable models. Compartmental models, widely used in biology, supply both the practical motivations and an example of application for the proposed methodology.
Design of closed-loop optimal controllers for systems with shape deterministic inputs
Authors: Grimble M.J.
Published: August 2008

The design of closed-loop optimal controllers for systems with output-feedback is considered. The disturbance, initial condition and reference signals in the system are assumed to be either deterministic or shape-deterministic or a sum of both, The shape-deterministic signals have a specified time response, but the magnitude of the response is a random variable with known mean and covariance. The performance criterion includes the expectation averaging operator, and the cost is measured over the positive-time interval only. The performance criterion also includes dynamical operators which may be chosen to achieve specified response characteristics.

The solution for the closed-loop controller is obtained, for both tracking and regulating problems, in the s-domain. The controller is not, in general, the same as those obtained from either the LQP or LQG optimal-control problems. The advantages of the technique are that output feedback, rather than state-feedback, is used, and both random and deterministic signals are optimised. In other approaches to such problems, there are severe difficulties in defining a performance criterion which is suitable for both deterministic and stochastic signals.
Nonlinear modelling of calcium metabol ism — first attempt in the calcium-deficient rat
Authors: Staub Jean-François , Brezillon Patrick , Perault-Staub Anne-Marie , Milhaud Gérard
Published: August 2008

A nonlinear model of calcium metabolism in the calcium-deficient rat is pro posed. It takes fully into account the experimental time-courses of plasma calcium and its radionuclide concentrations, circadian variations included. Through its mathematical representation (a set offive first-order differential equations incorporating a nonlinearity representing a second-order autocatalysis), calcium metabolism is considered as a self-organised system and its circadian behaviour is dictated mainly by nonlinear processes involved in bone calcification. From our identification procedure, a probably unique set of parameters is obtained and both temporal stability and the time-course of calcium distribution within the model are studied. The model exhibits a stable limit cycle corresponding to two observed characteristics of calcium metabolism: stability and circadian periodicity. Simulated behaviour of different compartments is discussed in relation to calcium deficiency. In conclusion, this investigation represents the first attempt to elucidate a quantitative study of calcium metabolism, visualised as a self-oscillating system, ie, in a non-steady stable state.
A low-noise control system for a high-pointing-accuracy satellite
Authors: Montanari P. , Ravazzotti M.T.
Published: August 2008

This work deals with the design of an attitude-control system for a scientific mission which performs astrometric measures by the use of an optical strapdown telescope. The optical system requires a very low vibration level and a high pointing accuracy. This task is performed by a control loop which can filter the noise and assure a smoothed motion to the S/C in order to follow any path in the sky without losing star signals. A further improvement is obtained by optimising the observation procedure and sampling time. By the analytical treatment and the simulations performed, results show that the jitter level of the system is lower than that allowed, and the dynamical motion of the S/C is satisfactory.
Some aspects of a microprocessor based control system for a hybrid tube heating furnace
Authors: Duguid W.R.
Published: August 2008

A hybrid (gas/induction) furnace for preheating hollows up to 120 m in length for processing in a stretch reducing mill (SRM) has recently been installed at BSC's Tubes Division Works at Corby, Northants. The control system needed to ensure that tube is presented to the SRM at the required temperature within close tolerance has posed some interesting problems. Two of these problems: the feed-forward system for the control of the induction section, and the logic requirements of that part of the safety system concerned with tube stoppage within the furnace; are described in some detail. The control system employed is the Babcock-Bristol Micro-B, and the software language used is ACCOLG.
Reliability design evaluation of electrical and electronic equipment
Authors: Mathew A.E.
Published: August 2008

The objectives of reliability design evaluation are discussed. The application of fault tree analysis as a design-evaluation technique is described with reference to a communications receiver system. A criticality analysis is performed on the system, and, arising from this, it is shown that more usual methods of evaluating system reliability are inadequate to describe the reliability of systems which can suffer different forms of performance degradation. A reliability figure of merit is derived which takes account of the severity of various forms of performance degradation, and this is used to compare the reliability of alternative design configurations.
Automatic detection of drilling holes in PC boards
Authors: Groen F.C.A. , Ligthart Ir G.
Published: August 2008

A system to detect drilling hole positions in PC-board masks is described. The masks are scanned by a mechanical moving stage scanner. Both scan-control and detection of the rings that indicate the drilling positions are performed by an INTEL 8030 microprocessor system. After determination of the effective board size and the reference position of the 1/20-inch (1.27mm) drilling grid, scanning along this grid starts recognising the rings at the drilling positions. The prototype scans a board of size 100 x 160 mm (Eurocard size) in 10 minutes.
Blood flow and blood velocity measurement in vivo by electromagnetic induction
Authors: Wyatt D.G.
Published: August 2008

The application of electromagnetic induction to the measurement of blood flow and blood velocity in vivo is reviewed, The electronic requirements are discussed and the associated problems are surveyed. A brief account is given of Bevir's virtual current theory and its application to flow and velocity measuring devices. The devices at present known to be in use or to be under development are reviewed under the following headings: invasive local magnetic field devices which include cannular and perivascular flowmeters, also intravascular velometers and flowmeters, invasive extracorporeal field perivascular and intravascular flowmeters; and noninvasive systems which either utilise skin electrodes and a separate extracorporeal magnet or comprise an integral extracorporeal flowmeter. There is a brief discussion of the present state of development.
Measurement of blood flow using Doppler-shifted ultrasound
Authors: Stevens A.L.
Published: August 2008

Ultrasonic fields can be used to measure the complex dynamic flow patterns in a wide range of intact blood vessels with calibres ranging from fractions of a millimetre to several centimetres. Many of these vessels may be examined non-invasively from outside the body. Ultrasonic flowmeters have developed from the early transit-time instruments through the continuous-wave Doppler velocimeters to the complex multigate pulsed Doppler and conposite duplex B-mode/pulsed Doppler imaging systems which are capable of measuring true volume flowrates. The natural constraints associated with the fundamental methods, the various techniques, and the signal-processing stages are all considered in relation to the quantitative measurement of blood-flow velocity and volume flow rate with particular reference to potential sources of error.
In-vivo measurement of blood flow using radionuclides
Authors: Rowan J.O.
Published: August 2008

This paper reviews the fundamental basis of radionuclide tracer methods used in the investigation of the circulation. The various Xenon-133-clearance methods for the measurement of cerebral blood flow are described, and their advantages and limitations are indicated. An outline is also given of the use of corresponding tracer-clearance techniques in the determination of blood flow in liver and muscle. The potential advantages of short-lived positron-emitting radionuclides and positron-emission tomography are considered, and quantitative and qualitative non-diffusible radionuclide tracer methods are also discussed.
The effect of load flexibility in hydraulic manipulators
Authors: Broome D.R.
Published: August 2008

The mechanical design of a servosystem is important to ensure the required accuracies. Compliance of the elastic structure of the mechanism may be compensated by resulting inputs to the servo position controllers. The effect of load compliance is examined for a single-degree-of-freedom system, and the results can be used to generate a full system model from which a suitable controller can be synthesised.
PSICON—A simulation package for the design of digitally controlled systems
Authors: Linkens D.A. , Menad M. , Mort N. , Gray L.S. , Bennett S.
Published: August 2008

A simulation language is described which is based on a block-oriented continuous systems simulator called PSI. Using the message-transfer capability of the multitasking operating system of a minicomputer, external digital control algorithms can be developed rapidly in Fortran, while retaining the advantages of a flow-chart based and precompiled structure of the continuous simulation language. The use of the package is illustrated with two examples. The first is an anaesthetics problem in which time-delay dynamics are controlled using an external Fortran programme comprising a Smith predictor plus a PID regulator. The second example is a self-tuning adaptive autopilot for ship steering. The package gives fast simulation and good interactive properties, with the external controller segments giving the required flexibility for a wide range of uses.
Design of diametral displacement transducer for continuous measurement of the external diameter of a ring under compression at any temperature
Authors: Abdul N.A.
Published: August 2008

A knowledge of the amount of friction present at the die/ workpiece interface and the basic yield characteristics of a workpiece material are fundamental requirements for any metal-forming analysis to have a useful practical application Coincidentally the property of a ring under compression provides a reliable means of sensing and measuring friction and of determining the basic yield characteristic of the workpiece material under bulk plastic deformation.

However, the application of the ring technique requires measurement of axial as well as diametral displacements which - for ease of application and saving on material — should be made continuously, especially for high temperature application.

Towards taking maximum advantage of the ring technique, this work presents a design of a special diametral displacement transducer consisting of four cylindrical variable area capacitors for continuous measurement of external diametral displacement of a ring under compression. The transducer, capable of automatically recording the mean of two orthogonal diametral displacements was used at elevated temperature.
Pharmacokinetics
Authors: Godfrey K.R.
Published: August 2008

This is a review paper dealing with the dynamics of drugs and their metabolites in the body. After an introduction in which terms commonly used in the pharmacokinetics literature are introduced, linear pharmacokinetic models are analysed, distinction being drawn between intravascular administration, in which the drug is injected directly into the systemic blood circulation, and extravascular administration, where an absorption phase occurs before the drug appears in the systemic blood. Some commonly occurring non-linear effects are described, and the relationships between pharmacokinetics (drug in blood) and pharmacodynamics (pharmacological effect) are discussed. Throughout the paper, emphasis is laid on the mathematical modelling and, in particular, aspects of system identification. The special features of pharmacokinetics in relation to the identification process are illustrated, and the general lessons to be learnt are discussed.
Control of medium-term dynamic econometric models: an application to the Cambridge Growth Project model
Authors: van der Ploeg Rick
Published: August 2008

The latest version of a large-scale multisectoral dynamic model of the UK's economy, developed by the Cambridge Growth Project under direction of Sir Richard Stone, is described. Its dynamic properties, owing to an investment cycle of the order of five or six years, and its main economic properties are analysed thoroughly.

The medium- term nature of the model is exploited to formulate a macroeconomic policy for the UK's economy. An understanding of the long- run dynamics of the economy is crucial, since a change in policy today has complicated consequences many years later. A regulation approach is proposed and yields an optimal reflationary mix for steering the economy over the next decade towards its desired target trajectory. The dynamics in the policy ensure satisfactory levels for growth, inflation and unemployment. The industrial implications of the feedback policy are discussed and suggestions for sectoral policy are given.
Control theory and feeding
Authors: Toates M.
Published: August 2008

A very basic model of the neural processes underlying feeding is presented. In this model, feeding is aroused by the sensory properties of food, under the restraint or amplification of a signal arising from internal energy state. The anticipatory and adaptive nature of the feeding control system is described. Feeding is compared with other control systems such as temperature, sodium and fluid control. Feeding and energy regulation are used as the basis for a discussion on the meaning of the term 'set point'. In the context of this term, at least three levels of explanation commonly used in the literature are identified. It is argued that, in discussions of whether or not set-points exist, it is important to specify the level of descriptian/explanation that is being employed.
Complex processes random optimisation
Authors: Cebuhar W.A. , Morales J.E.
Published: August 2008

This paper describes so-called random search techniques : simple, adaptive, and reinforced learning. Concerning these techniques, the studies carried out at the Research and Advanced Studies Center (Mexico), for optimal operation of biological plants, are reported. Subsequent results concerning mathematical and computational aspects- that have been under development at INTEC since 1979 - are presented. The method can be applied to complex industrial control problems for which there is no model of the process.
Surge analysis and suppression techniques for a water supply scheme - a case study
Authors: Dawson P.A. , Fox J.A.
Published: August 2008

This paper describes a surge analysis which was undertaken on the Caledon-Bloemfontein supply scheme, a large-diameter pipeline (1.2 m) on which the static head is unusually high: over 240 m. Currently, the pipeline operates at less than 20% of the design flow, but transducer traces show that surge pressures following pump failure already cause concern, with a peak at least 16% above the pipeline rating. Moreover, these peak pressures are not compatible with those predicted by traditional methods. Thus, the computer analysis described herein was undertaken firstly to determine the reasons for the unexpectedly high transient pressures, and secondly, to study the effectiveness of alternative surge suppression methods.
Cycles in business planning†
Authors: Shearer P.R.
Published: August 2008

The plastics business-features large cyclical swings, both short and long term, and effective planning demands an appreciation of the mechanisms involved. Long-term plastics growth is typically 3% pa, but year-on-year growth or deline of 15-20% is normal rather than unusual, and such movements need to be anticipated. This paper outlines work developed during the 1970s in ICI Plastics Division (now a constituent part of Petrochemicals and Plastics Division), aimed at improving forecasting performance for plastics products by incorporating cyclical factors.
Dead-time controller applied to interacting feedback loops on a baking oven
Authors: McFarlane Ian
Published: August 2008

Feedback control has been applied to direct gas-fired ovens used for baking biscuits. The signals from in-line sensors for density, moisture and surface colour of the finished product have been used to modify temperature set points at various parts of the oven, which is built in a series of zones. Some observations of the characteristics of particular ovens are reported. This information has been used for the process modelling needed to apply 'Smith Predictor' compensation for transport lags in the process; two ovens have been controlled by this method. Interaction between colour and moisture feedback control loops is discussed, and some work on an arrangement for partial decoupling is described. The decoupling is illustrated with some results from a simulation using actual plant parameters.
Practical aspects of piezoelectric ceramic load cells
Authors: Bindal V.N. , Som J.N. , Kumar Ashok
Published: August 2008

A lead-zirconate-titanate disc, with a double electrode system, has been used as a sensing element in a piezoelectric ceramic load cell. Variations in output voltage at a fixed excitation frequency, and also the shift in resonant frequency with respect to change in load, have been measured. It is shown that the maximum sensitivity and optimum performance is achieved when the disc is made to vibrate in the radial mode at a frequency lower that the resonant frequency of the unloaded disc. The effects of various parameters on the performance of loadcell are also discussed, along with linearity, temperature stability and repeatability.
μψ(muPSI)-a microcomputer simulation language with computer control capabilities
Authors: Linkens D.A. , Rimmer S.J. , van den Bosch P.P.J.
Published: August 2008

muPSI is a block-oriented, continuous system, simulation language implemented on a microcomputer with a Z80 processor, 56K RAM and twin floppy discs. It retains all the facilities of its minicomputer parent language PSI, together with additional features for implementation of computer control schemes, Intermachine communication is feasible via analogue channels and also provides for real-time clock facilities and hand-shake protocol for machine synchronisation. A version is also available which allows for multiprocessor communication via serial RS232 digital linkage. The use of muPSI is illustrated via a stand-alone benchmark problem involving the cardio-vascular system, and a self-tuning computer control example involving naval frigate manoeuvring. The language offers extensive simulation facilities using a desk-top microcomputer system, and should be useful as an educational tool as well as in research and development projects.
Solving distributed heat-exchanger models by the method of characteristics
Authors: Smith A.J.
Published: August 2008

This note describes a simple method for solving distributed heat exchanger models while preserving their distributed nature. The method is illustrated for the case of parallel flow exchangers, and a comparison of analytic and numerical results is given for a simplified case.
Frequency limits for gas flow pulsation damping criteria
Authors: Mottram R.C. , Mohammad W.A.
Published: August 2008

The accuracy of most flowmeters is seriously affected by pulsations, and these must be damped before reliable measurements can be achieved. Damping criteria based on the Hodgson Number have been used for many years in flow measurements made with differential pressure-type flow meters. The objects of this paper are to demonstrate the validity of such criteria in gas flows and to specify their frequency limits.

A damping criterion derived from a theoretical analysis applicable to any pulsation waveform is presented. Results of experimental tests carried out with both piston- and siren-type devices, producing pulsations of sinusoidal and non-sinusoidal waveforms in the frequency range of 5-500 Hz, are shown. The results verify that the damping criterion is valid on the Surrey University air flow rig at various pulsation amplitudes and damping volumes at frequencies below 50 Hz.

It is suggested that these results are applicable to any gas flow system provided the limiting frequency is such that:

(i) The dimensions of the damping chamber are not greater than one-tenth of the pulsation wavelength.

(ii) The length of pipe between damping tank and flowmeter should not exceed one-fifth of the pulsation wavelength.
Complementary filtering in the central nervous system
Authors: Landers P.
Published: August 2008

Complementary filtering theory is used to explain the behaviour of three mammalian reflexes, all concerned with the measurement of head angular movement and with reflex control of eye movements. A short explanation of complementary filtering theory is followed by a discussion of the vestibulo-ocular reflex. Experimental results are presented, indicating the frequency response of this system and a transfer function is derived. The optokinetic reflex is then described, and results of further experiments are used to obtain a transfer function for these two reflexes combined. A transfer function is then obtained for the optokinetic reflex alone. This is compared with that obtained for the vestibulo-ocular reflex, and the two are found to be consistent with complementary filtering theory. This theory is then used to predict the dynamics of the cervico-ocular reflex, and these predictions are compared with the experimental results of others. Complementary filtering theory is found to conform well with all the experimental results described, and it is therefore claimed that the three reflexes combined may be regarded as a complementary filter.
Variable operating costs of wastewater treatment plants
Authors: Smeers Y. , Tytecat D.
Published: August 2008

In this paper, variable operation of the plant is studied through a model previously developed for simulating steady-states and optimising the total design cost of a treatment plant. In particular, various possible designs of a plant are considered; for each of them, a set of steady-state values for the effluent quality level, compatible with the initial design, are simulated and the total variable operating costs are optimised. In this way the dependence of the variable operating costs on both the design and operating effluent quality levels can be analysed.
Microcomputer control of a triple heat exchanger
Authors: Fung E. H. K. , Chiut P.C.
Published: August 2008

Direct digital control is applied to a pilot-scale triple heat exchanger employing two single-board microcomputers, one for control and the other for data acquisition. Comparison is made on the performance of six control algorithms for the control of the heat exchanger. In particular, the branched predictive controller and the variable precompensator based on inverse Nyquist array method are selected for single-variable and two-variable controls of the pilot plant, respectively.
Engineering development of a centrifuge inertia monitoring
Authors: Thomas P.J.
Published: August 2008

The paper describes the development of an on-line instrumentation system to monitor the moment of inertia of a solids-liquid separation centrifuge operating in a highly radioactive environment in a fast-reactor fuel- reprocessing plant. The principal interest of the paper lies in the close interweaving of measurement and control, both theory and experiment that was needed before an engineered solution to the measurement problem was possible.
The application of a direct method for designing decoupling pre-compensators for multivariable systems
Authors: Fricker A.J.
Published: August 2008

This paper describes work demonstrating the feasibility of using a pre-compensator in a co mpressor- turbine re frigeration system for aircraft cabin cooling to permit largely independent closed- loop control of cooling air temperature and drive shaft speed.
The operation and control of the CEGB power system‡
Authors: Knight U.G. , Moran F.
Published: August 2008

The paper briefly describes how the CEGB power system is controlled, from the operational planning phase through to the on-line dispatch of generation to meet the varying consumer demand. These activities are highly dependent on studies carried out on the Board's large central computing facility and on assistance provided to the operators by a network of computers located in the Control Centres. Brief reference is made to developments which are in hand or planned in this area. The paper goes on to describe a research project oriented to developments in on-line control in the longer term. Through it the problems of computer-aided dispatching will be investigated and the potential benefits of this evolution in the control procedure will be evaluated.
Optimisation of the operation of gas transmission systems
Authors: Pratt K.F. , Wilson J.G.
Published: August 2008

A computer program for the steady-state optimisation of the operation of a gas transmission system is described. The program solves the nonlinear optimisation problem iteratively, linearising the gas-flow equations to give a linear constrained problem; optimising by mixed-integer linear programming; and re-linearising about the optimum; until convergence is obtained. Costs may include compressor fuel, flows from sources, or any chosen control variables. Examples of applications are given . Some other published methods are briefly described.
Optimisation of water networks
Authors: Coulbeck B.
Published: August 2008

The paper seeks to establish useful and flexible techniques for optimising the operation of water networks and also to extend the range of systems which can be treated. As a preliminary, a detailed systems analysis is performed which allows formulation of simplified hydraulic and cost models covering all significant operational aspects. A problem at present under investigation concerns optimised pump scheduling of single reservoir sources, For this situation practical results are obtained by use of dynamic programming. The method is then extended to cover systems having multiple source supplies external to the network, together with variable closure valves which can be used to control the network operation. Under these conditions it is possible to partition the problem into that of a dynamic source optimisation task and a static network control task. Source optimisation takes account of the relative cost of supply to yield optimal pumping schedules, and network control involves adjustment of the valves to maintain the optimal operating conditions.
The adaptive tracking of slowly varying processes with coloured-noise disturbances
Authors: Fung P.T.K. , Chen X.P. , Grimble M.J.
Published: August 2008

An adaptive tracking technique is developed to estimate the output of a slowly varying process which is corrupted by a coloured noise disturbance. There are two estimators in the adaptive tracker. The primary estimator and the vernier estimator is simply a low-pass filter or its equivalent. The vernier estimator is self-tuning and is adaptive to the varying disturbances. Since the process contains unknown parameters, the usual Kalman filter can not be used. A conventional low-pass filter might be employed but it would give a significant phase lag in this situation. The adaptive tracker has a small phase lag and has particular advantages over the conventional low-pass filter when the frequency of the coloured noise disturbance is varying.
An optical-fibre data-telemetry system for use in remote or hazardous locations
Authors: Crossley S.D. , Giles I.P. , Culshaw B. , Sadler A.A.
Published: August 2008

This paper describes the evolution of a form of optical-fibre telemetry highway that is believed to be unique. The system is based upon the modulation of the phase of coherent light within an optical fibre by passing ultrasound across the fibre. This phase modulation is cofiverted to amplitude modulation by the partial detection of the light received at the output. The fibre used is commercially available multimode fibre, and by using a number of ultrasonic transducers, each modulated at different frequencies, a multichannel data collection system can be implemented. The system is ideally suited to applications involving telemetry from remote or hazardous environments, since the power consumption of these simple clip-on modulator structures, including all the associated electronics, may be below 1 m W. Transmission distances of up to several kilometres may be realised using the same basic system format.
Estimation of fundamental relations for an electromagnetic float-flowmeter based on magnetic suspension
Authors: Smigielski J.
Published: August 2008

The general principle of operation of the electromagnetic float-flowmeter is briefly outlined. Relations between the magnetic, hydrodynamic and gravitational forces acting on the float and the geometric, fluid-flow and electric parameters are presented. They are derived theoretically or determined as empirical relations generalising the results of experimental investigations. By proper normalisation the graphic representations of most important functions have been reduced to simple curves convenient for computations. On the basis of these relations the measuring range of the flowmeter as well as parameters of the coil and power supply have been evaluated. These data may be utilised for the purpose of optimum design and analysis of the influence of variations in the operating conditions.