Use Of Digital Computer Research Articles

Direct adaptive control for linear multivariable systems†

Abstract The aim of this paper is to survey direct adaptive control for linear multivariable systems. The discrete-time case is emphasized because of the increasing use of digital computers. Some adaptive control structures are given, as well as the different assumptions made on the process in order to achieve some specified objectives. Trends, new solutions and open problems are also discussed.

On the Uncertainty in the Correctness of Computer Programs

The use of digital computers in critical process control systems requires the formal assessment of the system reliability. Failures can be due to either component malfunctions or design faults. Only the latter are relevant in evaluating software reliability. Although it is preferable to prove whether the program meets its specification, this is not yet practical for real-time control programs. Further, the specification itself can be incorrect or incomplete due to the complex requirements.

Automatic test scheme for a class of non-linear servosystems using transient response data

The paper discusses the use of digital computers in developing dynamic tests for testing a control system during its actual operation, or for a test rig which simulates the system's working conditions. Usually three levels are required in any successful test scheme: a check-out test to classify the system as faulty or non-faulty, a diagnostic test to locate the parameter or component responsible for the fault and finally an estimation test to establish a quantitative measure for the faulty component before it is repaired or replaced. The scheme is applied in a case study of a throttle control servosystem, where a digital model of the actual system used as a vehicle for the study.

Command of a mini‐scanning electron microscope by digital computer for use in industrial process

ScanningVolume 7, Issue 3 p. 158-161 Short NoteFree to Read Command of a mini-scanning electron microscope by digital computer for use in industrial process J. L. Franceschi, J. L. Franceschi Laboratoire d'Optique Electronique du C.N.R.S. associé à l'Université Paul Sabatier, 29, rue Jeanne Marvig, 31055 Toulouse Cedex, FranceSearch for more papers by this authorH. le Floch, H. le Floch Laboratoire d'Optique Electronique du C.N.R.S. associé à l'Université Paul Sabatier, 29, rue Jeanne Marvig, 31055 Toulouse Cedex, FranceSearch for more papers by this author J. L. Franceschi, J. L. Franceschi Laboratoire d'Optique Electronique du C.N.R.S. associé à l'Université Paul Sabatier, 29, rue Jeanne Marvig, 31055 Toulouse Cedex, FranceSearch for more papers by this authorH. le Floch, H. le Floch Laboratoire d'Optique Electronique du C.N.R.S. associé à l'Université Paul Sabatier, 29, rue Jeanne Marvig, 31055 Toulouse Cedex, FranceSearch for more papers by this author First published: 1985 https://doi.org/10.1002/sca.4950070308Citations: 1AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Citing Literature Volume7, Issue31985Pages 158-161 RelatedInformation

State-of-the-art and prospects of adaptive systems

The theory and applications of adaptive control have developed very intensively. There are two reasons for this: variable parameters of controlled plants change within a broad range, on the one hand, and accuracy requirements to process equipment, aircraft systems etc. increase, on the other. Moreover, the wide use of digital computers permits now even complex adaptation algorithms to be easily realized. The paper attempts to review methods of design analysis and synthesis of adaptive systems (AS). Extreme systems, systems with passive adaptation and identification problems have not been considered. Since contributions of Soviet authors has been largely overlooked by the writers of earlier reviews (Åström, 1983; Fujii, 1981; and others) we have decided to focus our attention mainly on the results obtained in the U.S.S.R.

RATIONALE FOR AN ADA SOFTWARE ENGINEERING ENVIRONMENT FOR NAVY MISSION CRITICAL APPLICATIONS

ABSTRACTThe U.S. Navy introduced the use of digital computers in mission critical applications over a quarter of a century ago. Today, virtually every system in the current and planned Navy inventory makes extensive use of computer technology. Computers embedded in mission critical Navy systems are integral to our strategic and tactical defense capabilities. Thus, the military power of the U.S. Navy is inextricably tied to the use of programmable digital computers.The computer program is the essential element that embodies the system “intelligence”. In addition, it provides the flexibility to respond to changing threats and requirements. However, this very flexibility and capability poses a host of difficulties hindering full realization of the advantages.This paper describes the lessons learned about computer program development over the past twenty five years and discusses a software engineering process that addresses these lessons. It then describes how Ada and its related Ada Programming Support and Run‐Time Environments foster this software engineering process to improve computer program productivity and achieve greater system reliability and adaptibility. Finally, the paper discusses how the use of Ada and its environments can enhance the interoperability and transferability of computer programs among Navy projects and significantly reduce overall life cycle costs for Navy mission critical computer programs.

Multiprocessor Control of a Telemanipulator with Optical Proximity Sensors

The complexity of robotic systems usually necessitates the use of digital computers in their control. When a sensory- feedback control loop is closed around a robot and its com puter system, the real-time flow of data through the computer strongly influences the fidelity of the resultant motion. The purpose of this paper is to identify characteristics of the com puter controller that have the greatest impact on the perform ance of the system and to show, by means of an example, how the performance may be enhanced through the use of digital control techniques. The Stanford Robotic Aid is a computer-assisted telemanip ulator equipped with optical proximity sensors and a multi processor control system. Digital control techniques are used in the study of its application to a surface-following task. Thè dynamic behavior of the manipulator and the computer network is modeled by a set of difference equations. Propor tional sensory feedback is analyzed through use of a root- locus method, and a pole-placement method is used to design a state-feedback controller. The actual behavior of the system in a step-response test is compared to the prediction of the model.

Advances in open-channel hydraulics after V.T. Chow's book

Although Ven Te Chow was more well known for his scholarly contributions in the field of hydrology and water resources, his book entitled Open-Channel Hydraulics , published in 1959, has unquestionably been established as a classic book in hydraulics. In terms of thoroughness and extensiveness in coverage and information, it has not been surpassed by any of the open-channel hydraulics books published after 1959. Even today, nearly a quarter of a century after its publication, most of the material presented in Open-Channel Hydraulics still remains current and fresh. Nevertheless, within one generation, considerable advances have been made in the field of open-channel hydraulics. As expected, there have been numerous investigations into various aspects of open-channel flows, especially through the use of high-speed digital computers. Some of the significant advances in open-channel flow are briefly reviewed in this article, including: fundamental derivation of the basic, general open-channel flow equations; flow resistance over rigid boundaries; fluvial hydraulics (alluvial bed forms and sediment transports); mathematical models for steady and unsteady gradually varied flows; flood routing for dam breaks; hydraulic jumps; environmental hydraulics; and secondary currents in open-channel flows. The purpose of this article is to list some of the advances in open-channel flow, published since Dr. Chow's text: Open-Channel Hydraulics . This article does not attempt to comprehensively review all the advances made in this area of study. Although over 150 articles have been listed, the remarkable fact is that the content that comprises the main theme of Dr. Chow's book has not been surpassed. This clearly indicates that the great majority of his book still remains current and valid after 23 years of intensive research. Great advances in the study of fluvial hydraulics and mathematical modeling through the use of digital computers, the two major areas discussed in this article, have occurred since the publication of Dr. Chow's book in 1959. It was certainly a great pleasure for the writers to have known this giant in the field of water resources, hydrology, and hydraulics.

Dynamic optimization of a sandwich beam

Analytical procedure for the determination of the least weight design sandwich beam which satisfies a specific frequency requirement is presented. The approach is to modify an initial design by varying the thickness of each of its different layers. This is accomplished using gradient equations to first obtain the correct beam fundamental frequency and then, while this frequency is held constant, to minimize the weight. The gradient equations are derived in matrix notation suitable for the use of digital computers. For practical as well as other considerations, imposing lower bounds on layers' thicknesses have been found necessary. The equations of motion used include all the higher order effects like inertia, extension and shear of all the layers. Hence the procedure is applicable for short as well as long, soft or stiff cored beams. The design procedure has been completely automated in a computer program. Results of numerical examples show that the method is convergent and that optimized configurations can be determined in a few redesign cycles.

Book reviewsIntroductory Physics of Nuclear Medicine. By ChandraR., pp. xiii + 237, 2nd edit. 1982 (Lea and Febiger, Philadelphia), $19.25. ISBN 0–8121–0826–4

There have been many advances in nuclear medicine since the first edition of this book appeared in 1976 (reviewed in British Journal of Radiology, 1978, 51, 621), and these are reflected in the major changes in the second edition. The chapter on radiopharmaceuticals has been expanded and an extra chapter has been added in order to give more attention to the gamma camera, including the use of digital computers to record and analyse images.

Monitoring of an Electrical Driven Pump Using Continuous-Time Parameter Estimation Methods

The supervision of technical processes has been subjected to an increasing development, due to the increased demands on reliability and safety of industrial plants. The use of digital computers and parameter estimation methods allows the application of supervision methods which result in substantial earlier detection and localization of process faults than with conventional limit and trend checks. Many process faults are associated with changes in the physical characteristics. Therefore process monitoring based on parameter estimation methods for continuous-time, time invariant and time variant process models was subject to some research. Applications are shown for an engine set, existing of an electrical drive and a centrifugal pump.

Graphics and Animation by Personal Computer

The use of digital computers in the visual arts began in the early 1960s. Now this is a common field for their application. A substantial number of articles describing such artworks have appeared in Leonardo, and some are reprinted in Ref. 1. I have written three articles myself on the subject, which were published in German (2-4). Generally, such work is done on large computers to which a small number of artists have access. More recently, however, small, rather inexpensive digital computers, called personal computers or home computers, have become available. They are widely used in account keeping, text editing, game playing, learning and control- ling the operation of electrical and of mechanical devices. They can also be applied in the production both of music and of artistic graphics and will undoubtedly be widely used by artists in the future. Thanks to today's technology of micro-electronics, their tiny integrated circuits or chips give them a computing power approaching that of very large expensive machines. The personal computers are not much larger than a typewriter. They consist of a keyboard of letters and numbers and combined units of electronic parts, such as a microprocessor, a memory device and input-output circuits; sometimes a monitor or CRT screen is added to the computer housing. The monitor can be used to display letters, words, text and numbers hand-typed on the keyboard. It serves also as the output for showing the results of computations, which may be in the form of text, numbers or graphics (points, lines and areas). A commercial home color television set may be used as the monitor for some types of personal computer.

Procedures for parametric analysis of the calls of nonhuman mammals

Whoever wishes to describe animal vocalizations is faced with the task of developing a species-specific phonetics. The most difficult part of the task is constructing adequate measures of vocalization. We have designed a system that uses digital computation based on linear prediction technique to quantify a family of parameters of feline calls. The analysis proceeds in two stages. First, a series of general functions that describe different parameters is obtained: pitch period, formant, rms values, harmonic ratio, energy ratio, and formant ratio. The second stage summarizes these functions as sets of descriptive statistics. Because the use of digital computation in analyzing animal cries is quite new, there is no standard approach to this measurement problem. The methods developed here will, we hope, prove useful in the quantitative description of the vocalization of a large number of mammalian species. Also, since these analyses stem from recent research on human speech, they may be useful in the comparative study of vocalizations of humans and other mammals. [Work supported in part by NIH HD-05958.]

Simple and High-Accuracy Digital Computer Control of Hot Strip Coil Temperature

Hot strip quality largely depends upon coiling temperature control. Coiling temperature must be controlled in the distributed parameter cooling process with dead time and because of the various operational restrictions involved, it is difficult to apply the linear control theory. After considering the underlying technical problems, the authors developed mathematical models and a dynamic control method to cope with them. This dynamic control method consists of a discrete parameter system and handles the strip-speed normalized capacity of cooling water synchronizing to the strip travel and cooling. This permitted simple control through the maximum use of digital computer. At the Ohgishima Hot Strip Mill which started operation in 1979, these models have been applied for 100% of all product sizes.

Is it Safe?

This final article introduces some examples of safety assessments which, for one reason or another, vary from the conventional patterns. Some are still being developed, for instance methods of assessing active controls, and problems associated with the use of digital computation. The article finishes with a glimpse of possible future trends.

Natural Frequencies of Curved Girders

A general finite element displacement formulation is presented to determine the natural frequencies of spatial thin-walled curved girders including the warping contribution. Also included are the rotatory inertia effects with respect to flexure and torsion, and the effects of antisymmetry of cross section (found to be significant). The stiffness and inertia properties of the finite element are obtained using the solutions of homogeneous differential equations governing the static problem as deformation modes. The obtained element relationships were programmed for use in digital computers, and a few example problems were analyzed. Some charts are given to expedite the determination of natural frequencies of horizontally curved girders.

Incorporating Software into Nuclear Power Plant System Design

High quality performance required in nuclear power plant systems is difficult to demonstrate when digital computers are involved. Special design considerations are needed to assure high quality performance of the digital computer program within the framework of the total system. Two ideas, discussed in this paper, contribute towards meeting the special considerations needed to incorporate software into a total system design in a highly safety-oriented industry. An orderly development process incorporates the software design into the early stages of the total system design. A graphic technique, SADT™ is presented as a means to plan, implement, and document the orderly development process. The use of digital computers increase the complex-ities of systems design. Contributions are made by diverse, highly specialized groups. The quality of system performance depends on the performance of each group and how well the individual contributions mesh together to form a total system. The system designer, the hardware designer, the software designer, and numerous others must coordinate their efforts to ultimately achieve an operational system which possesses evidence of high quality performance. To provide assurance that the digital computer program performs its intended function is a difficult task.

Bimoment contribution to stability of thin-walled assemblages

A finite element formulation for stability problems of structures assembled from thin-walled members with open crosssection is presented. The contribution of bimoment toward stability of unsymmetrical sections is included. Using the solutions of the homogeneous differential equations governing the static behavior as deformation modes, the stiffness and stability matrix are derived. The formulation has been programmed for use in digital computers and several appropriate examples are analyzed. The obtained results are exact for linear static problems and extremely close upper bounds for eigenvalue problems.

Computerized Method of Determining Insulation Requirements of EHV Transmission Lines

Statistical methods are increasingly being used in determining the insulation requirements of EHV transmission lines and stations. As these methods essentially involve complex mathematical calculations, the use of digital computer becomes inevitable to achieve desired speed and accuracy in calculation. An algorithm has been developed to determine the insulation requirements of transmission lines in terms of tower air clearances to give a predetermined risk of failure per switching operation. The tower air clearance requirements of a 765 kV, 500 towers transmission line has been determined under different overvoltage conditions for a constant risk of failure.The programme developed is also capable of determining the performance of the line from the raw data of switching overvoltage distribution and insulation strength.

Measurement and analysis of the dynamics of mechanical structures

This paper discusses modern methods of testing, modeling, and analyzing the dynamics of mechanical structures. The topics covered are mathematical modeling of structural dynamics, modes of vibration, the normal mode versus the transfer function technique for structural testing, and identifying modal parameters from transfer function measurements. As indicated, much of the discussion concerns the modes of vibration of mechanical structures which turn out to be the link between the testing and analysis methods discussed in this paper. These methods are based upon the use of digital computers, and algorithms such as the finite element method for modeling and analysis, and digital filtering such as the fast Fourier transform for dynamic measurements. Some of the latest techniques for graphically displaying modes of vibration using low cost measurement instrumentation will also be presented.