Digital computers have been used more and more to control different industrial processes during the last decade. As of today, many sy­ stems are designed to include a process control computer as a vital part. The use of computers has created a need for sophisticated me­ thods for the operation and supervision of complex industrial proces­ ses. To summarize the state of the art from the practical as well as from the theoretical point of view, the 4th IFAC/IFIP International Conference on "Digital Computer Applications to Process Control" will be held at Zurich from March 19 to 22, 1974. The first two vo­ lumes of the proceedings contain the accepted papers submitted to the conference mentioned above. The papers are arranged according to the topics of the conference. A third volume will include the six follow­ ing survey papers: 1. Digital Control Algorithms Prof. A. P. Sage, Dallas Texas / USA 2. Interface Problems for Process Control Prof. T. J. Williams, Lafayette Indiana / USA 3. Software for Process Computers Dr. J. Gertler, Budapest / Hungary Dr. J. Sedlak, Prague / CSSR 4. Digital Computer Applications in Metallurgical Processes Mr. W. E. Miller, Salem / USA Mr. W. G. Wright, Schenectady / USA 5. Digital Computer Applications in Power Systems Mr. D. Ernst, Erlangen / FRG 6. Digital Computer Applications in Chemical and Oil Industries Dr. H. Amrehn, Marl / FRG We hope, that the publication of these papers from specialists.

Digital Control in Metallurgical Processes.- Control investigations on a nonlinear lumped-parameter model of a sintering process.- Einsatz eines Prozessrechners zur Durchsatzmaximierung an einer quasi-kontinuierlichen fertigungsstrasse.- Dynamic control of multistand aluminum cold rolling mills.- Modèle Numérique pour la simulation de certaines classes de procède métallurgique et son utilisation pour l'optimation de la qualité de produit.- Development of a computer system for the aluminium electrolysis process.- Computer Control of Vuonos Mine.- Multivariable Control of a Five-Stand Cold Mill.- Numerically controlled bending of metal beams.- Improvement in oxygen furnace controllability.- Dynamic control of LD converter with digital computer.- Digital Control in Power Systems.- Use of graphic data screen as operator interface.- Digital control of a hydroelectric power plant.- A dual computer controlled load dispatching system.- Die Ueberwachung eines Teils des schweiz. Hochspannungsnetzes mit State-Estimation, Prozessaufbau und Praktische Erfahrungen.- A simulation study of data acquisition and data communication in a complex power transmission network.- Application of digital control to thermal power plant for automation.- Synthesis of security monitoring schemes in power systems.- Equivalences among model reduction, filter-observer and feedback control design.- Automation of scientific experiments on digital-analog physical complex for investigation of processes in power systems.- Bad data analysis for power system state estimation.- DDC in power plant - application and operational results.- A minicomputer based system for suboptimal control and automation of a nuclear research reactor.- Digital controller for a turbine and alternator.- The improvement ofpower system synchronizing and damping torques using adaptive control techniques.- Practical design considerations affecting the use of digital computers in high voltage substations.- On-line security assessment and control of interconnected power systems using sensitivity concept.- Beschreibung des Rechnereinsatzes in Einem Thermo Kraftwerk.- A pattern recognition approach to the preventive evaluation of power system security.- A direct digital control system for a steam power plant.- Frequency control of the "Donut" system using modern control theory.- Temperature raise control of super critical boiler using derivative digital filter.- Digital load frequency control in a multiarea power system.- Freilastberechnung im Kraftwerk mit Einem Prozessrechner.- Digital Control in Other Processes: Material Handling and Storage, etc..- Use of a process computer to control a high-bay warehouse.- Process control: digital regulation of a turboreactor using A.S.M.O.D.E.E. 01 prototype.- Optimal coupling of an incinerator plant to a district central heating system.- Computer control of a conveyor system.- ASTRA-71, a system for operational control of industrial motor transport in open pits.- Die ÜEberwachung Einer Tiefdruckrotationsmaschine mit Hilfe Eines Prozessrechners.- Computer control of conventional rotary telephone exchanges.- Reliability of Digtal Control.- Reliability of non-redundant digital control computer systems.- Wechselwirkung zwischen prozess, DDC und Back-up bei Hohen Anforderungen an die Betriebssicherheit.- Economics of Digital Control.- Economics of digital control, how, why and where, a case history.- Informationstheoretisch Begrüntiete Qualitätsrriterien für Rechnersysteme und Möglichkeiten zur Einbeziehung Ökonomischer Gesichtspunkte.