Search

This paper describes the computer control system used in the paper mill of Oy Nokia Ab in Nokia, Finland. The computer controlled Yankee Paper Machine produces paper with basis weight from 17 to 72 grams/m 2 . The operational principles of this paper machine and its control system are described. The control system software includes data collecting and reporting programs as well as supervisory programs. The most important variables and conditions of the paper machine are measured and reported. Among the control application programs the basis weight and moisture control can be considered as the most important. The target values of both moisture and basis weight are maintained by the computer. Thus the operation of the paper machine enables us to obtain maximum permissible moisture values of the produced paper. The computer also controls the non-continuous or continuous proportioning by the amounts of pulp components. Thus, an economic and exact proportioning is reached. The computer also controls the changes of grade, which are thus made accurately and fast. The computer measures continuously the lengths of the machine reel and the customer rolls on the winding machine, and tells the proper times for changes, and so the lengths are optimized. The conclusion includes the experiences we have gathered when using this computer control system.

Summary Digital simulation and plant tests have demonstrated the feasibility and the economic advantages of coordinated control of paper machines. The design of coordinated control is discussed, with examples and plant test results of paper machine coordination. On-line simulation models are proposed as an aid to coordination during certain state change, and for use in on-line estimation. The digital computer implementation of the new control schemes is described.

This paper tells about a computer application in the control and supervision of paper manufacture. The operating system and the control program modules as well as the opportunities of the process operator to interact with the execution of the programs are described in addition to the computer equipment. Control objects are the basis weight, humidity, machine speed and headbox level and pressure. Their essential features are described together with a description of the supervision, which consists of quality and production reports.

Summary A multilevel approach to design of a paper machine control system has been presented. The system described includes not only regulating and coordinating control, but also on-line optimizing algorithms. In addition to being a convenient means for organizing the control activity, the multilevel approach provides a framework for organizing the computer software. In actual operating systems, the frequently executed first level programs are core memory resident, while the remaining levels of control reside in a rapid access drum mass storage. The core-drum memory combination is an economical way to implement multilevel control structures.

Summary A mathematical model of the drying part, as a controlled member for paper sheet moisture control is being constructed. In constructing it the distribution of temperature along the thickness of the cylinder as well as the distribution of the moisture along the length of the drying part is taken into account. The optimization of the dynamic responses of the controlled member is achieved with using of model through the choice of the proper structure of the steam pipeline, of the proper design of the drying cylinder and of the proper value of some technological parameters. In construction the combined system of control the vacuum in the chamber of the couch-roll is used as an indirect indicator of the basic disturbance. A further improvement of the efficiency of the moisture control is achieved by the statistical prediction of the indirect indicator of disturbance.

This paper is intended to give some background survey of the “industrial management systems” research in the recent years, and also to give some comments on the six papers in Session 26. Since the industrial management systems is one of the typical large-scale systems with hierarchical structure, the three basic types of hierarchies in industrial management systems, which is systematically proposed by Mesarovic, et al., are presented. Each paper is looked at again from the basic types of hierarchies point of view. Finally, the promising area of future research in industrial management systems is anticipated.

Summary As converting operations increase in speed, the need for greater uniformity in reel performance increases, leading to stricter and more objective specifications of reel properties. This paper reviews efforts to define and control them. Reel properties depend on paper properties, winding tension, reel size, and core properties. The cross directional variations of paper properties and tension cause the main problems in producing satisfactory reels. It has been shown by experiment and by theory that the sheet tension within a reel is lower than its wound-on value; it is usually necessary to increase the wound-on tension steadily to maintain a tight reel. Complications to the calculation of the stress distribution arise from several features: the non-Hookean compressive characteristics of paper, its viscoelastic nature, the spiral form of a reel, friction between layers, and the increase in wound-on tension caused by a drum winder. Assessment of reel quality is based on various tests: visible defects, moisture content, average density, hardness (level and variability), diameter variability, and roundness. The uniformity within one reel is particularly troublesome and many studies have been made attempting to relate reel hardness and diameter variations with, on the one hand variations in web characteristics and, on the other, reel performance. Several useful correlations have been found but their interpretation, it is considered, is confused by the local interactions of web properties (thickness, compressibility, tension) and by the difficulty in understanding how hardness depends on them. It is concluded that the theoretical and experimental study of these interactions is required, with cross directional variations in mind, before the type of instrumental control could be suggested with confidence. Subjective control of reeling might then be replaced by instrumental control, since the need for instrumentation, once establ ished, can only lead to a rapid development of their technology.

Summary A brief study has been carried out into the possible applications of real-time infra-red thermal imaging devices in the paper and board industry. Because of lack of experience the interpretation of the displays produced by the devices can be difficult. It appears that under some circumstances the instruments can be used to study non-uniformity problems and though the presence of these can be demonstrated, the data available as yet does not allow detailed diagnosis by employing IR thermal images.

Summary Paper stock flowing at constant velocity through a pipe has a consistency which is proportional to the mass of solids flowing through the system. If the flow is turbulent the local concentration of suspended solids varies in a random manner; these concentration variations are proportional to the mass of suspended solids which can be measured by an electrical transducer. Only the dynamic a.c. component of conductivity is measured and the d.c. component is ignored; in th is way the variation of concentration due to the solids can be accurately measured and any drift in conductivity, due for example to polarisation or to changes in the mean conductivity of the liquid phase, is of no consequence.

This paper constitutes a review of the research work completed at the Computing Center of the USSR Academy of Sciences dealing with the theory of optimal orbit transfers for space vehicles powered by low-thrust rocket engines.

Summary 1 Aim function formulation is given and criterion of optimum stock inlet process control is chosen. 2 Mathematical stock inlet process model is represented with nonlinear differential equation system with variable coefficients. It concerns the whole stock inlet system and also the stock feeding system, pipelines, stock flowmeter, inlet chamber and so on. 3 After model linearization and grounding connected with it idealization computerized calculation methods of stock inlet system design are worked out. It allows to increase dynamical stock flow stability during inlet without control systems. 4 The further increase of dynamical stock flow stability is ensured with feedback control. During computerized investigation transition processes in control system variants the peculiarities of different control systems are found.

Summary The paper describes a control system particularly suitable for processes with long transit time lags, but which is equally suitable for other applications. The system uses a time proportional pulse to actuate the controlled element, the time proportionality being arrived at by plant modelling. The amount of correction given does not rely on feedback, but a sampling technique is used to check that the amount of correction given is correct. Provision can be made to cater for non-linear control functions, backlash correction and differing degrees of control in the positive and negative directions. “Bump-less” transfer from automatic to manual and vice versa is an inherent feature of the system.

Nearly 4 years ago in the field of Artificial Intelligence a learning machine called STeLLA was conceived. After three years of computer simulation of the machine in a variety of problem environments, the design is greatly improved, although the main features have survived. Since the machine is being simulated with a vehicle-steering control problem which is second order, non-linear and stochastic it would appear that STeLLA now qualifies for the title of “adaptive controller”.

It was of some surprise, after listening to all the contributions, to conclude that nothing had been said about the theory and application of extremum-seeking devices based on Evolutionary Operation EVOP and its associated modifications such as SIMPLEX and COMPLEX. In many real control systems the values of the measured variables are obtained at discrete intervals of time, which may be of the order of minutes, and consequently there may be considerable delay in the evaluation of the Performance Index. Many of the continuous-perturbation methods proposed at the Symposium do not lend themselves to systems of the former type, and it is thus desirable to be aware of alternative methods of control.

Summary The cooking process control of the “Kamyr” reactors with the application of a computer permits to maintain the preset proporties of the kraft pulp at most economical technological conditions. Such a system is based on a mathematical model of the process obtained on hand of a physical model with the use of the factorial and simplex experiment planning methods expressed in the form of an equation system of the first and second order. In-site checking of the process model showed In-sit with sufficient accuracy the quantity relationship of the wood pulp yield, the residual lignin content, the cocking degree and the mechanical properties of the pulp versus the main sulphate cooking variables: the cooking temperature curve, the liquor-towood ratio, the active alkali, the proportion of the coniferous and hardwood species and the white liquor sulfidity. The synthesized control system functions on the principle of compensating the influence of the measurable input disturbances and the application of the feedback for compensating the immeasurable disturbances. In-site tests of the system at the Kotlass pulp and paper mill with the application of a computer to control the operation of the “Kamyr” digester producing 425 tpd kraft pulp for bag paper showed the efficiency of the developed system.

Summary This paper includes purpose, field of application, mechanism, structure and technical data for the consistometer resulting from the URS System (universal automatic control and regulation system) and working according to a twin-cell alternating light principle with optical self-acting intensity balance. Whereas calculation of the quotients for A can be made with a computing relay or an analogous computer component, the advantages of the consistometer URSAFOT T2 can be fully utilized only within the bounds of a process control system by realization of a true forward control, for instance for head bow consistency control of a paper machine.

Summary A continuously measuring ashmeter, based on x-ray absorption principles and developed jointly by Reed Engineering and Development Services Limited and Nuclear Enterprises Limited, has been installed on one of the fine paper machines within the Reed Group. Calibration of the meter has been carried out for the grades made on that machine using static samples and verified on-line by comparing the results with quality control values. The meter is capable of determining the ash content of a moving web of paper in the range 2 to 25 per cent ash, 40 to 120 g/m2, with a standard deviation of 0.71 per cent ash. Both china clay and titanium dioxide may be determined with equal sensitivity; other fillers may also be measured providing they are present uniquely in the sample. Signals from the ashmeter are processed within the online DDC computer at the mill and used to control the addition of china clay slurry continuously at the mixing pump in order to achieve the desired level of ash in the finished sheet. The use of this control system has red the within-grade variability of ash, which is now normally held to ± 1 per cent. This has led to improved quality, a lower rejection rate and more efficient use of raw materials. Nuclear Enterprises Limited are developing a completely self-contained ash-substance-moisture meter which will perform all the necessary calculations internally. The provision of analogue controllers will then allow automatic control of ash content based on continuous clay addition even where no computer is available.

Description of main principles of antenna steering system utilizing a simple special-purpose digital computer and a precision analog power servo drive. Input to system is 8-channel paper tape with predicted satellite positions in special format; typically 3 feet of tape required for one hour steering. Over-all pointing error ±2 minutes of arc excluding prediction errors.

For a rotary lime kiln used in the recausticizing process of a (kraft) paper mill, R mathematical model is presented. The form of the mathematical description is obtained on the basis of the mass and energy balances. The unknown coefficients in the mathematical model are determined by applying the stochastic approximation method. The identification scheme yields the optimal values of the parameters such that the best fit to the available discrete measurements is attained.

Summary Measurement of the attenuation of acoustic waves is suggested as a method for deducing the consistency of thin suspensions of papermaking fibres. Results obtained by a pulse method in the frequency range 1 to 6 MHz show that attenuation increases linearly with consistency. The measurements are in the range 0 to 2.5 wt. %, a range wh ich is not adequately covered by other methods of consistency measurement. The specific attenuation varies between samples. Values of the order of 20 dB/wt.% metre at 1 MHz are reported, increasing roughly as the square of frequency. The effects of temperature, wetness, additives, and entrained air are discussed.

Summary Pulp bleaching is a contiuous process carried out in a number of reactors arranged in succession. The object of the bleach plant control system is directed towards stabilizing the operating conditions as present by temperature, consistency and the reaction time at each bleaching stage as well as by the output pulp quality properties. The cooking degree and the pulp flow at the inlet of the department are the main disturbances The computer solve two tasks: 1. Evaluation of the clorine requirement at the chlorination stage input. The calculation is carried out with the use of the magnitude of the oxidation-reduction potential measured value, the time transport lag and the real clorine consumption value at the moment of measuring. 2. Stabilization of the reaction time at variable pulp flow at the input of the department is the second task. To solve it a highcapacity computer memory is required. The calculation algorithm of levels in the bleach towers involves the probable flow limitations at the input of the individual towers and ensures filling of the memory to switch it quickly for the monitoring procedures. The system is applied at one of the mills in the U.S.S.R.

SUMMARY This paper deals with the theory of asynchronous motors running at variable frequency. Motor characteristics are found by the help of a computer programme where higher harmonics are neglected, but the influence of saturation is considered. It is shown that it is impossible to get optimum performance if the voltage is a function of the frequency only. A regulator which controls the voltage as a function of both frequency and load to keep constant flux gives torque and current characteristics equal to those of a dc-machine. This paper presents two alternatives for such a regulator. Braking methods are discussed and a regulator principle for a four-quadrant drive without current sensing is shown.

The author has been engaged in design, installation, commissioning, and subsequent operation of a ship automation system with advanced instrumentation. The paper deals with the instrumentation as such, without entering into details of the end use of this instrumentation. The instrumentation was installed in a motor tanker, and much thought was given to the planning of locating and securing components, selecting cable runs, screening and grounding methods. Experience shows that preparing and working according to such plans pay off in reduced electrical noise problems. Selection of sensors and other components has been found to be a tricky business. The severity of the ship environment can be misjudged. While temperature and vibration problems are at least expected, if not fully understood, the hazards of climbing crew members and liberal use of high pressure cleaning may be surprises . The instrumentation is considered overall successful, However, the paper points out some mistakes that were made. Good practice and well considered component selection help to reduce mistakes, but there are cases where components will not stand up to all requirements of the specification at the same time. These cases can hardly be avoided except through experience.

In this paper, it is shown that the design of a linear control system with following properties: (1) having no steady state error can be guaranteed for all inputs (applied to the control system) and disturbances (applied to the controlled object) described by p-th order polynomials, (2) any set of arbitrarily designated eigenvalues can be always realized, (3) the property (1) of the steady state error can be held unchanged in spite of the change or the ambiguity of system parameters in controlled objects, can be established by the use in combination of state and output (controlled variable) feed-back. Throughout this paper, it is assumed that controlled objects are all controllable observable time-invariant linear systems with m inputs, m outputs and n state variables, and always satisfy a certain condition concerning a steady state solution of the systems. The structure and design formula of the control system for each of the following four cases are given: (1) continuous type of controlled objects (a) with directly measurable states only or (b) with directly unmeasurable states and (2) discrete type of controlled objects (c) with directly measurable states only or (d) with directly unmeasurable states. The practical design procedure and some discussion are also given.

This paper is concerned with a digital computer simulation of the effects of series ventricular assist pumping (intra-aortic balloon pumping) on left ventricular mechanics and arterial hemodynamics. The human ventricle is, in general, characterized by a ventricular elastance function (E) that is a function of end-diastolic volume (V) and time, and the arterial load presented the ventricle is represented by a modified Windkessel model. A model for the intra-aortic balloon pump is also incorporated in arterial load model. The paper demonstrates (1) the characterization of the ventricular mechanics of the normal and failing (coronary artery disease, hypertrophied) heart in terms of elastance functions and (2) the utility of such an overall model in assessing the effects of ventricular assist device pumping on ventricular mechanics and arterial hemodynamics

This paper treats one aspect of the shipboard automation, namely an automated engine room for turbine driven ships. The automation system presented compromise the result of a Norwegian research and development project which started in 1970. The system is based on one standard type process control computer. The general goals of such an automated engine room system are stated. A description of the automation system is given, and the advantages of digital computer applications are pointed out. Special attention is made to on-line condition monitoring and trend analysis of steam turbine plants, and to the optimal Direct Digital Control (DDC) of the main boiler. The computer system has conventional back-up. A brief discussion on the back-up philosophy and the method of swtiching from computer mode to conventional mode is carried through. Complete computer system simulation testing of the automation system before entering the ship is very important and some space is devoted to this matter. The qualifications of the operating personnel is explained. The necessary training in addition to the basic education and experience of the engineers will be given. The paper concludes with a summary of the importance of the new developments which are implemented in this automation system.

Summary The paper describes the physical nature of the origin and maintenance of vibrations resulting from the parametric resonance phenomenon in the “rectifier frequency converter asynchronous motor” system. The paper describes the influence of individual parameters and operational regimes of the system on the origin of these vibrations. It substantiates the application of the method of harmonic linearization for the analysis of parameters of set vibrations. The paper also examines ways and means of controlling the above-wentioned vibrations.

This paper presents a digital computer model of the cardiovascular system (CVS) for an integrated open loop, as well as a closed loop, regulator and indicates the results of experimentation to regulate pressure. The results of the mathematical analysis and simulation verify many of the conclusions of previous investigators and develop some new ones related to hypertension. The model is basically developed from the work of Grodins (1-3), and Mc Adam (4), and extended and refined to result in one of the few all digital computer simulations utilizing Starling's law of filling (5). The paper proceeds to develop the CVS model from Starling's law of filling for an isolated ventricle and presents a set of equations which will be utilized to develop a digital computer simulation as well as perform an analytical analysis. A model for the simulation of heart-rate feedback is carefully developed, tested and incorporated in the CVS model in order to study feedback regulation. Both the parameters used for linear and nonlinear operation of the system are extended from experimental data on dogs to those of humans. Experimental results of the digita1 computer model for a human CVS indicate the effects of pressure regulation with and without feedback. The effect of various gain factors on the heartrate feedback equations is carefully analyzed. It is clearly shown that the CVS operating with-cut heart-rate feedtack either delayed or inhibited causes excessively high arterial pressure (hyertension). Utilizing the correct type and kind of regulation causes normal pressure regulation. In addition to the response of the systems pressure the effect of regulation on cardiac output and blood volume are also experimented with. It was observed that for constant cardiac output the blood volume increased and the heart-rate decreased as the arterial pressure increased. Experimentations with the human CVS model also revealed the non-linear relationship between arterial pressure, cardiac output and heart-rate in addition to the linear relationship between arterial pressure and peripheral resistance. The CVS model developed should prove to be a valuable aid to medical doctors and researchers in their attempt to find causes for the nations number one killer - hypertension. This work is a result of more extensive analysis and simulation and represents a condensation of' the more basic work. Some of the more inportant results are presented in this paper.

Summary The development of rectifier frequency converters for controlling the velocity of synchronous motors which serve as drives for water pumps is becoming a pressing problem. This task depends to a considerable extent on the correct solution of the problems of starting and damping such systems. On the basis of analysis of starttoperational and damping regimes of the pumping units the paper substantiates the asynchronous start of the motor under low frequencies of the feed voltagetoutlines the zone of starting feed voltage, illustrates the influence of inverter types on the starting characteristic and steady operation of the motor under quasi-stationary start conditions. The paper also examines the influence of the design and parameters of the rotor on the range and rate of capacitor damping.

The effect of mathematical and physical modeling of processes has had relatively little effect on the glass industry. However, significant modeling results are available as indicated by a wide range of publications. In this paper, the published modeling work is grouped by area with discussion where appropriate. In addition, the major physical phenomena along a glass line are discussed with an assessment of the degree of difficulty in modeling them to an accuracy sufficient for either process control or process design. In this assessment the major assumptions and simplifications currently used in model derivative and specification are noted. It is concluded that many of the phenomenon are of such a complexity that models have not had sufficient accuracy for design purposes. One of these areas is the furnace with the main problems being the convection currents in the melt, the radiative heat transfer, and the melting physics and chemistry. Finally, the results of a questionnaire sent to glass industry technical personnel polling modeling efforts and results are discussed. An extensive bibliography of modeling work is a part of the paper.

SUMMARY An earlier paper (1) described the use of high power thyristors in Booster Power Supplies for Glass Melting. Since that time, the availability of even larger thyristors has allowed the economical design of larger Power Supply Systems. This paper describes the design features of a 4.3 Megawatt, Thyristor Controlled, Power Regulated, Glass Melting Power System. The System is installed on a 115 ton mixed melter furnace with bottom electrodes used in the production of Opal Borosilicate Glass. It includes High Voltage Switchgear, Dual Secondary Power Transformers, and Water Cooled Power Cables along with the Thyristor (SCR) equipment. Some information is also presented on electrode peripheral equipment; startup procedures and a method of computing approximate circuit resistance for use in determining controller and transformer voltage and current ratings.

Model Reference Adaptive Systems have been used more and more widely in the last few years to solve various control, parameter identification and state estimation problems. This survey paper tries to present in a systematic way the “state of the art” based on the literature published since 1964 (221 references). Attention is paid to the basic properties and the classification of various types of model reference adaptive systems. The most prominent design methods are reviewed ; unresolved questions and future areas of investigation are also discussed. A survey of the applications already accomplished and those that appear feasible in the near future conclude the paper.

This paper deals with the latest developments and technology of pneumatically handling materials. It deals with the conveying from railroad unloading site to bulk storage, blending the proportioned ingredients, and conveying mixed batch to furnace storage. The paper highlights the latest developments in pneumatic batch blending and portable vacuum conveying units.

Summary This paper presents an exact method for the investigation and stability analysis of the limit-cycle operation of pulsewidth modulator controlled systems with natural sampling. Two types of necessary conditions for the existence of a steady-state stable limit cycle are derived: 1. The existence as well as the parameters of possible limit-cycles can be determined from the so-called commutation conditions. 2. Local asymptotic stability of prospective limit-cycles is investigated by considering the system's equations of the first approximation. This paper presents a graphical procedure for evaluating the commutation equations, and a root-locus type method for determining the local asymptotic stability of possible limit-cycles. In order to present the above results in an exemplary fashion, a slightly unusual pulsewidth modulator controlled power converter is considered for which an analysis by other methods, exact or approximate, is not immediately obvious.

This paper presents a critical summary of present knowledge of human thermoregulation and indicates areas where definitive information is lacking. There are recent comprehensive review articles (1, 2, 3), so we have chosen to cite only representative papers which illustrate the various approaches which have been used in an attempt to elucidate the human thermoregulatory system. Since temperature regulation in the human encompasses a wide range of topics, the following subdivision is suggested as a basis for developing control mechanisms: a. normal short-term control; b. short-term reversible modifications due to fever, exercise, trauma, etc.; c. longer time scale modifying effects, such as hormonal action, adaptation, etc.; d. long-term irreversible neurological modifications. An experimentally confirmed signal-flow diagram for short term control perhaps could be extended to the other three conditions by effecting modifications in set-point, gain, etc.

and Introduction The purpose of this paper is to unify recent advances /1-8/ in the area of computer generation of sensitivity and pseudosensitivity functions and to point out new results which may be obtained from these known achievements. Particular attention is paid to an extention of the existing results to the generation of pseudosensitivity functions for linear multivariable systems whose mathematical models are given in the state space. The methods of generating pseudo sensitivity functions discussed in the paper, facilitate an easy extention of the methods for identification, parameter optimization and synthesis of adaptive systems, so far extensively used in the cases of single-input, single-output systems /8-15/, to linear multivariable systems. Already known results relevant to our subsequent discussion are reviewed in the first few sections.

SUMMARY The main aim of this paper is to show that well known definition of integral square error /ISE/ may be a criterion of comparative analysis of modulation procesees. The effect of analysis of ISE property is that the comparison of pulse signal with model signal by their integrals gives an estimation of shape of the signal which is aiequate to current on the output of inverters. Simultaneously, this ISE is the measure which is corresponding to additional losses in an inverter load caused by deformation of current. As an example of the application of this criterion the results of numerical calculations of ISE versus amplitude of the first harmonic for choosed forms of modulation are given in the paper. The possibility of making synthesis of pulse modulation by minimizing the ISE is also pointed.

Summary For the choppers with indirect switching is characteristic that after the saturation of the main (operating) thyristor the load current flows for a certain period through the switching (blocking) circuit and only then is switched to the free-wheeiing diode. Hence the load current curve is composed out of three sections. The paper deals with an analytical method for the construction of the current curve for the case when it is possible to neglect the variation of the load current during its flow through the switching circuit. In case this variation cannot be neglected, the solving of the problem can be performed using a computer. The paper offers for that case a universal programme for determining the necessary values for the construction of the curve.

Summary The design of the digital controller frequently follows the aim to obtain the system with the fastest response. By the practical application of this criterion, cases are often encountered where the transient error, caused by an input of typical form, has a very short duration but an inadmissible magnitude. This shortcoming is removed by the numerical method of controller design presented in the paper. In this method the finite settling time is combined with the minimum of integral squared error. In this integral either the same importance is allotted to all errors during the control process, or only the errors occurring after the first sampling period are being considered. The physical meaning of the second case is the requirement of the computer liquidating the error, as far as possible, during one sampling period, and not instantaneously. The paper shows that good results can be obtained particularly by the second method. The method of calculating is arranged in such a way that both alternatives can be investigated simultaneously. The author succeeded in arranging the calculating procedure into a simple scheme. A numerical example is given.

This paper deals with the computational methods for the state estimation problem of a large-Scale electric Power system. This state estimation problem can be defined as the power flow problem which has overdetermined boundary conditions, and non-linear function minimization techniques can be used to solve the problem. The mathematical foundation of proposed methods is based upon the perturbed Newton method which includes as special cases standerd function minimization techniques such as Newton-Gauss method, Fretcher-Powel1 method and steerest descent method. The proposed methods in this paper are considered as decomposition methods for the reason that the coefficient matrices of iteration schemes are decomposed into block diagonal forms from the view joints of a power system configuration or a sersitivity between variab1es. These methods are suitable for the state-estimation problem which has many state variables for the simplicity of the coefficient moatrix in non-linear function minimization techniques.

Summary There are known controlled systems such as chemical plants or airplanes whose differential equations are not known completely to the controller because of environmental changes, ageing, etc. In many systems of this kind the best which can be accomplished is to construct a multistage optimalizing process which converges to the optimum control. In the case of zero-memory, non-linear plant processes of this kind can be constructed if the gradient of the performance measure is known or can be determined experimentally. In this paper an extension of this method is considered for the case of non-linear plants having memory and changing randomly in time. In the two introductory parts of the paper the assumptions and the necessary and sufficient conditions of optimality are formulated. It is shown that at any stage of optimalization the best change of the input signal should be adjoint to the mean value of the gradient of the performance measure. Then an optimalizing process, based on the so-called fixed point theorem, is constructed. It is shown that for certain classes of non-linear random plants all the necessary information about the generalized gradient can be obtained experimentally. As an example an optimalizing process which minimizes the cost of input energy and maximizes the output gain of a non-linear plant has been constructed and is discussed.

The design of direct computer control systems for groups of NC machine tools involves the determination of an optimum hardware-software configuration for the given task. For the case of continuous path control four basic configurations are: 1 Fully software interpolation by the control computer 2 Centralized /possibly time-shared/ interpolation by special hardware 3 Simplified local hardware interpolation, where preparatory simplification is done by central computer software 4 Full local hardware interpolation. The first alternative saves on specialized interpolation hardware but requires very high computing speed, severely restricts the number of controllable axes and needs expensive, broad bandwidth linkage with the machine tools in a noisy environment. The second requires special hardware and the same broad bandwidth linkage but saves on computer capacity. For the third and fourth alternatives there is increasing local hardware in an unfavourable environment, but simpler communication and better computer utilization. The choice between the possible configurations has generally been an empirical one, based on the equipment available. The authors have attempted, by balancing the advantages and disadvantages, to achieve a hardware-software equilibrium which will ensure optimal real-time conditions. To this end a FORTRAN simulation program of the direct computer control of groups of machine tools has been written and run on a CDC 3300 computer. The paper describes the structure of the program and the parameters it considers. In conclusion the paper describes a control system built in the authors’ Institute, incorporating the results of the above trade-off optimalization.