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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.

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.

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”.

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.

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.

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.

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.

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.

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.

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.

This paper describes the major aspects of modelling and a control systems design for the MZFR-Siemens pressurized heavy water, natural uranium nuclear power plant prototype - now in operation at Karlsruhe, W.Germany. The paper describes the development of a representative mathematical model for this plant and its hybrid simulation. The simulation results for both the uncontrolled and the (conventionally) controlled plant have shown close agreement with the actual plant dynamic behaviour. In addition to its technological significance as regards dynamic investigation of the plant, the model also forms the basis for testing new control strategies. A systematic method based on modern control theory is suggested for the solution of the overall plant control problem. A new approach is proposed for model reduction, optimal state estimation and optimal control system design. The optimal control law developed on the basis of the reduced model is modified to account for the actual input constraints and implemented on the hybrid model in d.d.c. mode. The. results demonstrate the feasibility of this approach to control systems design for large scale multivariable industrial processes .

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

Summary When a computer control system reaches a certain size it is no longer enough that the system is possible to work with. In order to be effective the work also must be convenient. Thus one of the basic concepts in the joint Billerud/IBM efforts has been that a computer control system should conveniently be used by - process operators - production managers - system engineers and programmers. For the communication between process operators and the process control system, carefully designed process operators consoles were developed. These consoles are designed in such a way that they are convenient and effective to work with for process operators as well as for process engineers. In order to ensure a good communication between production managers and control systems the process computers have been located adjacent to production managers' offices. During the first process computer project at Billerud, the 1710-project, it was found that programming took far longer than expected. When installing a second computer, an IBM 1800, controlling not only paper-machines but also a Kamyr digester and chemical recovery processes, an effective way of programming was necessary. Thus a programming package for the basic functions of process control and production follow-up was developed. The process and production control programs (PPCP) enables the system engineer or programmer to program the entire periodic part (read, check, filter, convert, control, etc.) of the control system by filling in forms. After punching, special conversion programs select the proper data acquisition and control algorithms based on these forms. Included in the system are routines for “cold start” standard messages, contract change handling, data acquisition and data reduction (as a base for the reporting system) etc. Also, the package includes routines for the communication with process operators and process engineers. Although the system is general and applicable to any process industry there are also a few routines available, which have been developed for pulp and paper applications, e. g. programs treating the signls from a travelling basis weight and moisture meter. The PPCP package has been used extensively for the IBM 1800 process computer installed at Gruvon in 1968. The package has proved to be as effective and convenient as expected, both computerwise and in handling. Thus an improved version, compatible with a modern operating system, is now in use in two IBM 1800 process control computers at the Gruvon mill.

The paper describes how one chemical plant contractor made himself able to install a computer as part of the instrumentation and control system for new plants. First there is an appreciation of what a contractor can and can not be expected to do. Then follows a discussion of the design criteria used to produce a universal system for chemical plants. The design employs DDC and provides backup with a digital presentation. The operators' panels were designed by the contractor and all the system programs were written by him in a low level language. It was realised that a very heavy client training load would be imposed on the contractor and solutions to the problems have been chosen which result in ease of explanation rather than technical brilliance. By the same token the computer used was chosen for the reliability of its hardware and its ease of programming rather than for economy in first cost. Absolute priority has been given to the aim of leaving the client with a system he understands and can exploit by adding extra plant supervisory programs. He is expected to start by writingrelatively short programs which are best written in machine code. Consequently no use has been made of a back ng store and a high level language is not expected to be necessary, although there is adequate provision for the use of any high level language for which a compiler has been written. It was considered more important that when he has written his program, be it long or short, he should be able to get it into the machine, check it, and put it on line, all without stopping the computer or disturbing the plant. The time shared operating system “Simcos” and the commissioning aids programs “Simcom” and “Simcheck” make this possible. The second part of the paper describes what happened when these ideas were put into practice for the first time.

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 There is some interest in the paper, rubber and plastics industries in non-contacting methods of measuring the thickness of strip products non-line. Optical methods potentially provide a class of non-contacting measuring techniques with a certain specific combination of advantages. Firstly, optical techniques work basically by locating the physical surfaces of the strip to be measured, so that the measurement is of actual thickness and is not modified by the internal composition of the material. Secondly, optical measuring heads may be not merely non-contacting but quite remote from the surfaces to be located, so that it is possible to allow for a degree of strip flap, thus avoiding the need for accurate strip location. Thirdly, the speed of response of an optical thickness gauge, limited fundamentally by the response of the photodetectors used, may be very rapid. Optical systems are particularly flexible, so that it is possible in principle to design thickness monitoring systems to cover any given range of thickness variation. A chief problem in design of optical systems for thickness measurement is in achieving adequate rigidity of the mechanical framework. It is however possible to design optical systems which minimise the mechanical rigidity requirement. An experimental optical instrument suitable for use in the rubber and plastic industries is briefly described, with details of its performance in on-line trials. Possible future developments of this instrument are outlined. Alternative design methods are discussed with particular reference to systems which may be suitable for thickness measurement in the paper industry.

An optimum state regulator for a once-through boiler is presented in this paper. The ordinary state regulator problem, i.e., bringing the control system from a given initial state to the origin, had to be modified for steam boiler control. The problem arising here is to maintain a desired state, i.e., steam temperature and pressure, in the presence of disturbances, where the load demand is usually regarded as the most important disturbance. In the variable pressure operation, the regulator problem can be formulated as a tracking problem. The turbine output has to follow a given power demand signal as closely as possible. Since in variable pressure operation the turbine output can be assumed to be directly proportional to the steam pressure, the pressure has to follow this signal as well. At the same time the steam temperatures should be maintained at a constant value. This paper is concerned with the variable pressure constant temperature operation. An optimal tracking system including an observer, is designed and compared with the performance of the optimally adjusted actual PID-control equipment.

Summary The paper is devoted to the problem of teaching automatic systems pattern recognition. At the basis of the experiments that were conducted with regard to teaching, lies a profound and original hypothesis relating to the teaching process—a so-called ‘compactness hypothesis’. This hypothesis is interesting in that it opens a path to the mathematical description of the essence involved in the teaching process, which description is not attached to any concrete technical realization of the learning system nor to any concrete pattern type. At the same time, it prompted the experiments described in the present paper, and also made it possible to comprehend already-known studies on teaching. The fact that the experiments on teaching described in this paper were conducted on a universal (multi-purpose) computer is naturally tied in with the presence of such an hypothesis. The ‘compactness hypothesis’ makes it possible to formulate various teaching algorithms. Two of them (the algorithm of random planes and the algorithm of potential surfaces) were verified experimentally and yielded good results.

Summary The stock preparation supplies two paper machines. Separate storage chests exists for each pulp group. Some of the chests are attached to exclusively one machine others are provided for both machines. Continuous flows from the storage chests and small capacities of the following parts of the stock preparation involves a strong coupling with the outputs of the paper machines. The computer induces the charging of the storage chests and the selection of a suitable pulper. Possible times for charging will be predicted with the knowledge of levels and effluents of the chests. Furthermore additional information about the state of machines ensures a more flexible adjustment. Each time a pulper had been discharged the forecasts will be adapted for actual data. The charging of the pulpers is done over two transportation ways. The worker will be informed about the demanded charges with digital displays. Simultaneously the computer transfers information about the selected pulper and the chest of destination in the controller of the transport system. The worker put the charge in the system and gives a reply message. The further run will be automatically and start by the computer as soon as the time of loading a pulper has come.

The first part of paper covers the commissioning of the plant control programs for the start-up and shut down of a 500MW Unit. The testing necessary to bring the programs up to the stage of applying them to the plant is described followed by the results of the testing on the plant. A typical plant group is taken as an example and all the stages are worked through to highlight the problems. Special mention is made of the matching of the control programs with the safety interlocks. Integration of the logic for the various plant groups concludes this part of the paper. Reference is also made to the problems encountered in the commissioning of the hardware. The second principal part concerns the description of the commissioning of an Arch Computer for the direct digital control of an auxiliary boiler. The site commissioning and subsequent performance of the computer system equipment in the environment of a boiler house operating floor is detailed. Testing and commissioning of the boiler control both sequence start-up and direct digital control is dealt with in detail showing how confidence is established. Reference to earlier work on analogue simulation of the plant and control of the model by the Arch Computer shows the correctness of modelling techniques and the necessity of early testing. The paper concludes with the consideration of some of the extra facilities and improvements that were made to the initial schemes and items to be considered in engineering future systems.

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.

This paper describes an approach to dynamic modeling and on-line carbon estimation based on waste gas analysis in a basic oxygen furnace. As is well known, the basic oxygen process for steelmaking is highly stochastic in nature. There is, at present, no satisfactory model for predicting the decarbonization rate of the process. The first part of this paper considers approaches to on-line dynamic modeling. A two-stage dynamic model is developed using time-series analysis and empirical information on the decarbonization rate. This model is put in a state-vector form which is ideal for online estimation and control. The second part of the paper applies linear and nonlinear filtering to estimate the carbon and the decarbonization rate of the process during each heat. Since there is a time delay between the bath conditions and the measurements, the state of the system must be predicted. Two different methods for prediction are given. One is based on the present estimate of the carbon in the bath, and the other is based on the present estimate of the decarbonization rate of the bath. A combination of the two schemes is shown to provide better results than those achieved so far in practice. A total of 175 heats from a 220-ton BOF are processed and analyzed, and the results are discussed.

This paper is a continuation of the previous report at the IV-th IFAC congress. The authors describe here the results of the latest investigations concerning designing and partial testing an original system of checking and optimum controlling of the thermal condition of modern blast furnaces. The problem of static optimization and dynamic stabilization of the thermal condition of the blast furnace melting is solved by subdividing it into two sub-problems, one concerning the upper thermal zone of the furnace and the second - the lower one. Specified and proved algorithm of automatic processing and analysing multidimensional current information concerning the operation of the furnace is given in the paper. This enables to estimate the intensification of the main blast furnace processes and to calculate independent generalized thermal condition parameters of the upper and lower zones of the furnace. The expediency of using such generalized parameters for checking and controlling blast furnace processes is proved by the results of statistical investigations. The methods of calculating optimum value of generalized parameters of the thermal condition of the upper section of the furnace worked out by the authors of the paper a static model of thermal regime of the blast furnace process and the algorithm of selecting optimum complex of quick-response action controls are also described here. This algorithm is based on applying new ideas of controlling blast blast furnace thermal condition and its realization is associated with using modern computers.

The paper discusses an on-line computing scheme designed to assist in the predictive control of a large interconnected electrical power system (C.E.G.B., U.K.). The paper claims that man will not merely be a monitor in such a control scheme but will occupy a key role in the control loop. It is suggested that this role can only be fulfilled if the computer can answer questions about the actual and predicted system state accurately, quickly and clearly. The aspects of providing such a facility which are discussed include:- (1) Graphic c.r.t. and light pen. (2) Main file data structure and access system (3) Display programming language. (4) General purpose control programming language. (5) (5) Computer executive program. The paper concludes that programs will need continuous development during the life of the scheme, and shows the type of languages and computer executive programs that are required to provide the software flexibility needed.

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.

The paper describes a computer control system for the optimisation of four cement kilns in Malmo, Sweden. The scheme underwent acceptance trials in June 1970. The “hill climbing” optimisation technique is employed which checks a series of actual or derived plant constraints by a complex logical sequence. The paper describes how the individual programs for each kiln were built up on line as plant experience was obtained. Stress is laid on the practical advantages of this approach as compared with the more normal method of offline development with subsequent on-line application. Description is made of the novel programming technique which allows complex optimisation strategies to be set up and modified by a control engineer with no programming experience whilst the computer remains on line. The paper stresses the significance of this facility in terms of reduction of system commissioning times. Benefits of the optimisation are listed, which amount to production increases of up to 10% and fuel savings of up to 6%.

SUMMARY The purpose of this paper is to initiate discussion on the impact of sensitivity methods on the theory of automatic control and to indicate future trends of developments. Also, the papers to be presented at the “sensitivity” session of this Congress (Session No. 31) are discussed in the view of the results so far achieved in sensitivity analysis.

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.

Summary Standard proving tests are used to predict the processing characteristics of polymers. However, even when processability test results are available, there are no conversion data provided by the machine builders for the various polymers and their own particular machines. In fact inadequacies in design and instrumentation usually preclude such a possibility. Absence of thermal isolation is the principal design factor which has not been allowed for on machines other than presses. The paper concentrates on the attainable, and discusses some of the simple but worthwhile improvements which could be undertaken by both the machine builders and the processors. The modernisation of their existing machines would appreciably reduce the setting up time and increase the dimensional repeatability of the products. The paper deals specifically with a plastic extruder and a ram injection moulding machine. Rubber extruders and the mill are also discussed.

The central core of a real time computer control system is the operating system which handles the allocation of the computer resources. Any realtime operating system can be shown to have a fundamental structure and data base which will be discussed in this paper. In implementing such a system for a given application, a subset of the general form and data base is used in order to efficiently handle the given application, decrease the time spent in the executive and reduce the size and storage requirements. However, in doing so one changes the flexibility and how the system operates. It is these tradeoffs and assumptions which we study in this paper. We shall look at three systems: the GE Real-Time Multiprogramming Operating System (RTMOS), the IBM 1800 Multiprogramming Executive (MPX) and the XDS Sigma 5 Real-Time Batch Monitor (RBM-2). It will be shown that each of these three systems has certain parts which are more flexible than the others. However, it would not be economical, desirable nor practical for a process control size system to have the same degree of flexibility in all parts. It is shown that each of these systems has a balance between capability, flexibility, and time response. The discussion will primarily show that there exists a commonality of structure and of necessary information even though the three systems were developed completely independently of each other.

When installing process control computer systems, too much emphasis is often placed on sophisticated control theory and on that mysterious black box rather than on the exceptions and abnormal situations, and on the necessary communications with those people responsible for production. Effective operator communication is the key to successful implementation of process control computer systems. This paper reviews operator communication requirements from a practical viewpoint based on experience with process computer systems, and discusses basic principles that should be included in the design of computer/operator communications. Typical computer display and data input functions found in an industrial process environment are discussed. Devices for accomplishing those functions are reviewed and critiqued from the viewpoint of adaptability to the industrial environment and in meeting the requirements of the operator. Hardware interface, computer system design, and programming considerations are presented. Mead's recent computer installation at its Escanaba, Michigan, paper mill incorporates many of the points made in the paper, resulting in a system of man/machine communications for process control, reporting functions, and data entry that has been successful since its installation two years ago. An effective operator training program prior to actual startup of the production facilities assured that intimidation by the computer and poor computer communications would not be operating problems.

The paper refers to the modernisation of existing plants by automation with particular reference to computers. The degree of automation which can be properly employed is discussed against the background of the differing individual design and operational limitations normally encountered in existing plants. The extent to which computers can be applied within an automation scheme is evaluated in relation to considerations of technical and economic viability and stages in the growth of computer systems are suggested. The paper describes not only the technical aspects but also the effect on plant staff in accepting and assimilating computer systems in the day to day operation of the process.

A navigation system using information gathered from a cluster of four non-coplanar synchronous orbital satellites is proposed. The system consists of: 1. At least one cluster of four non-coplanar satellites, 2. Auxiliary ground stations for satellite tracking and data processing, 3. User equipment. Since the cost of user equipment, in particular the computing cost, plays a very significant part in commercial feasibility of any satellite navigation technique, a special emphasis is placed upon the simplicity of computation algorithm and the feasibility of a small hard wired special purpose digital computer. The system operates on the range differences and range rate differences between the pair of satellites and the satellite ephemeris obtained by tracking. A tremendous amount of computation simplicity at the user end is achieved by preprocessing the ephemerous information and telemetering instead of the ephemeris data, this preprocessed data. The user computing equipment varies from a special purpose slide rule for a fixed terrestrial user to a simple digital computer for a fast moving aircraft. A sophisticated dispJay equipment can be used to display longitude, latitude, altitude, velocity, and heading. The analytical details for computation and error analysis are shown in the body of the paper. The major contribution of this paper is the development of a computational technique which results in an inexpensive, hard wired, modular type user computing equipment.

Die mestechnische Ausnutzung von Germaniumdendriten verspricht, das viele technologische Schwierigkeiten bei der Herstellung verschiedener Bauelemente beseitigt werden konnen, namentlich bei der Herstellung von Halbleitermesstreifen und Hall-Generatoren. Weil Dendrite starke Nichthomogenitaten aufweisen, muste man ihren Einflus auf die physikalischen Konstanten bewerten, um beurteilen zu konnen, ob dieser ungunstige Einflus durch die Einfachheit der Fabrikation aufgewogen wird. Es wurde theoretisch und experimentell nachgewiesen, das die Herabsetzung der Linearitat relativ klein ist. The paper evaluates dendritic germanium crystals made at the Telecommunications Research Institute used as piezoresistant pick-ups and Hall multipliers in measuring and control engineering. The introduction contains brief explanations of the individual expressions and definitions. The main part of the paper contains the results of experimental work, particularly on the static and dynamic temperature dependence. It has been found, that for a certain range of temperatures the stability of the deformation sensitivity (K = 50 ÷ 150) of the piezoresistive effect can be maintained within a range comparing favourably with silicon semiconductor strain-gauges. The stability of the zero level is worse by one order of magnitude. The temperature dependence of the Hall constant is also satisfactory within the range of temperatures allowable for transistorized measuring instruments. The magnitude of the Hall constant is mostly lower than that of conventional multipliers. The production technology has been solved satisfactorily both for the strain-gauges as well as for the multipliers of germanium dendrites and represents a great economy of both costs and time required to prepare the elements.

The paper describes briefly the cement manufacturing process and its i importance in today's world economy. It further sketches the successive steps of the introduction of process control to the operation of a cement plant. The optimization of the production process i s emphasized in the light of plant integration and automatization of its departments. Reduced process variability, lower production costs, increased power efficiency, and higher plant availability and production capacity are shown as results of plant automation. Some views are given on the influence of computer control on basic plant conception and on the standard of mechanical and electrical equipment suppliers. The paper elaborates somewhat on the impact of automation on plant operators and equipment suppliers as well as the role of the General Systems Designer and Consultant in applying modern technologies in designing sophisticated systems and in counseling the cement industry community.

The paper presents the results of the investigations of systems approach to air pollution control and urban planning. The problem of environmental pollution and the associated ecological effects are briefly described. The concepts of systems approach and their applications to the current study are explained. The problems of rural and urban planning resulting from rapid industrialisation are discussed. The necessity for considering the environmental impact on the selection of industrial sites, design of processes and the manufacturing methods in the planning stages of industrialisation is explained. Environmental pollution problems from some of the basic industries, viz. Paper and Pulp, Foundries, Iron and Steel, Cement, are discussed. Some of the problems which a developing country should consider, while planning to import technology from industrially advanced countries, are explained.

Hot strip mills provided one of the earliest opportunities for the application of process control computers. The large investment, operating complexity - particularly in the multi-stand finishing train, the high product volume coupled with the demand for accurate and uniform product dimensions created favorable economic conditions for computer automation as early as 1961. Since then computer automation systems in hot strip mills have advanced from a highly developmental creation of engineering art to a mature, predictable and repeatable engineering product. Shorter design and implementation cycles, as well as full operator acceptance of computer control of the hot strip mill process, are evidence of the maturity these systems have achieved. The paper describes advances in the structuring of computer automation systems for hot strip mills, which have enhanced or will further enhance system maturity. The structure of a computer system largely determines its ability to perform in the intended environment. While technical discussions of computer automation systems generally concentrate on individual functional components such as a control algorithm or a process model, the greatest progress in terms of cost, performance, and installation time can often be made through careful design of system structure. Experiences of a major computer systems supplier for the metal industry are explored. The structure of recent systems is compared with that of older systems. Differences are noted and resulting benefits are analyzed. For example, present day systems use highly modularized software to minimize the impact of changing equipment configurations. This technique reduces design and programming effort for a new system and increases flexibility of an existing system. Another example is the emergence of test, diagnostic and evaluation features as integral parts of modern hot strip mill computer systems. The paper concludes with a review of system evolution during the first ten years of computer process control in hot strip mills.