Real-time Facility Research Articles

Petri nets in dynamic process planning

Abstract A framework for combining Petri Nets with Computer Aided Process Planning (CAPP) systems is presented. The Petri Nets are used to provide realtime facility status information while the CAPP system is used to generate the revised process plans. Combining these two methodologies overcomes most of the weaknesses with the traditional CAPP systems. The result is a dynamic, realtime CAPP system.

Developing robot programming languages using an existing language as a base—A viewpoint

SUMMARYThe development of robot languages has followed a pattern similar to that of conventional programming languages, where robot languages have been based on an existing programming language. This paper first identifies the use of an existing base as one way of developing robot programming languages, and discusses the areas of difficulty in this approach. Then, on-line and off-line programming of robots is discussed and the requirements of robot programming languages that are different to those of non-specialised programming languages are presented. A discussion and evaluation of some programming languages in terms of their appropriateness for use as the base for an intelligent robot programming language is presented. This leads to the conclusion that no current language forms an adequate base for intelligent robot programming languages. What is needed as a base is a language for use in the artificial intelligence domain, that incorporates real-time facilities.

Advanced real-time X-ray facility is opened

Advanced real-time X-ray facility is opened

Real-Time Neutron Radiography System Performance—Measurements and Methods

The University of Virginia's real-time neutron radiography facility was characterized by measurement of the total neutron flux, gold/cadmium ratio, neutron/gamma ratio, and the effective collimar length-to-aperture diameter (L/D) ratio. The real-time neutron imaging system and collimator were further characterized by measuring the modulation transfer function (MTF) of the system. The collimator effectiveness was measured by using the MTF to determine the ''unparallelism'' of the neutron beam. The computer-based image processing system allowed rapid calculation of the MTF and the collimator effectiveness. The results of these measurements, using no collimator and a simple tube collimator, demonstrated the method's ability to determine the effective L/D ratio. The MTF measurement scheme provided a fast, reliable, and reproducible means of monitoring any changes in the real-time system, including both the neutron beam and the electronic components. This paper describes the methods and measurements implemented to characterize the changes in the radiographic system performance. These include standard measurements of the neutron, flux, neutron-to-gamma ratio, the effective collimator length-to-aperture diameter (L/D) ratio, and effective neutron temperature.

An interactive layout design system with real-time logical verification and extraction of layout parasitics

The interactive layout design system PARIS (placement and routing interactive system), which meets the special requirements of cell-based design methods, like gate array, bipolar analog standard cell, and transistor array approaches, is discussed. A real-time logic connectivity extraction tool is provided, which is integrated into the system's interactive layout editor GRILLE. Apart from online execution of formal layout checks during the design process, the system enables online net-list extraction of arbitrary layout parts and extraction of specific parasitics for bipolar transistor array applications. All PARIS tools for these real-time logic connectivity verification and parasitics extraction facilities support a hierarchical design philosophy based on a detailed functional and logical description of the layout components. This yields significantly shorter design cycles and avoidance of time-consuming net-list comparisons on the transistor level, which are superfluous especially for cell-based design methods. >

Parallel Programming in Ada and in the Hungarian Ada Compiler

Abstract The Ada language definition includes besides the classical programming technics new concepts to overcome various problems in high-level programming. One of the most powerful tools found in Ada is that for real-time programming with facilities to model parallel tasks. In Ada task is the basic unit for defining a sequence of actions that mav be executed in parallel to other similar units. Synchronization is achieved by rendezvous between a task issuing an entry call and a task accepting the call. The real-time facilities are briefly discussed with the special features of the Hungarian Ada compiler in this paper.

μψ(muPSI)-a microcomputer simulation language with computer control capabilities

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

A simple Ada compiler invalidation test

This small program tests some of the not-so-easily implemented features of Ada. Among the things tested are separate compilation, overloading, generics, aggregates, tasking and various real time facilities. The program can be used to get a quick assessment of the completeness of a non validated Ada compiler.

INS real-time data processing composite system using large scale general purpose computers

Quick response real-time facilities, with an overhead time of 18.3 ms, using a general purpose large scale computer, FACOM M-180IIAD (2.5 MIPS), and channel coupled terminal minicomputers, PANAFACOM U-400, have been developed and are in operation at INS Tokyo. The system is useful for computer aided real-time data acquisition and processing for experimental nuclear and elementary particle physics. Another batch processing system for the same type of large scale computer is connected with a real-time machine. Sophisticated analysis of experimental data as well as pure theoretical problems and design studies can be performed by this system. The system is also capable of backing up minicomputer terminals through a modem for the computer control of accelerators and beam diagnostics.

Implementation of Real-Time Facilities in Pascal

A real-time kernel which supports concurrent programming in Pascal is described. It implements semaphores for mutual exclusion and events for other synchronization. The kernel also offers the possibility to program I/O handlers. The kernel is written in Pascal, but relies on a small number of assembly written procedures for process creation, transfer between processes and handling of interrupts. The approach shows what has to be added to get concurrency in a sequential language and is therefore suitable for education.

Interfacing real-time operating systems to process control languages

The paper gives an overview over an operating system which provides for a flexible interface to support a wide spectrum of real-time language facilities. Due to its modular structure it can be tailored to the requirements of the language. In many cases this is achieved by an automatic, dialogue controlled generation of the system. For more serious changes well defined “basic functions” of the system have to be changed or new functions can easily be introduced. On the assembler level the system requests (SVC) are available as macro statements defined similar to real-time language syntax. A list of these macro calls is explicitly presented to give an overview over an implementation for the pdp 11 computer family; it shows the range in the definition of such a macro library. Based on this lowest level three methods to implement system requests in real-time languages are discussed. If the language allows assembler insertions the macros can immediately be used. If the real-time facilities of the language are connected via subroutine calls, they are realized by adding code procedures which contain the corresponding macros. In the third case, real-time operations are part of the syntax and can be compiled using the macros as inline code or generating adequate subroutine calls. These three methods are discussed with respect to readability, portability, software-safety, runtime efficiency and implementation costs. Implementations are illustrated by a few examples.

High-level languages and real-time operating systems for minicomputers: a review of their availability and facilities

This review discusses the role of high-level languages and real-time operating systems when minicomputers are used in the field of scientific instrumentation. Comparative information is given on the advantages and disadvantages of the main high-level languages currently in use in the scientific environment. Information on high-level languages and real-time operating system facilities available on current minicomputers was obtained by sending a questionnaire to all major suppliers in the United Kingdom. To help to give a proper overview of the role of high-level languages and real-time operating systems, sections have been included in the paper on interrupt systems, benchmarks (speed tests), emulators, certain hardware facilities, instrumentation which already utilises minicomputers, diagnostic for and debugging of real-time programs, user groups, program packages, job control languages, interfacing, computer peripherals and microprocessors.

YEPS: Running real-time experiments on a timesharing system

The Yale experimental programming system is described. This system consists of user-callable subroutines and a set of modifications to the UNIX operating system which support the development and execution of real-time psychology experiments. The interactions between a timesharing operating system and the provision of real-time facilities for experiments are discussed.

Interfacing Real-time Operating Systems to Process Control Languages

The paper gives an overview over an operating system which provides for a flexible interface to support a wide spectrum of real-time language facilities. Due to its modular structure it can be tailored to the requirements of the language. In many cases this is achieved by an automatic, dialogue controlled generation of the system. For more serious changes well defined “basic functions” of the system have to be changed or new functions can easily be introduced. On the assembler level the system requests (SVC) are available as macro statements defined similar to real-time language syntax. A list of these macro calls is explicitly presented to give an overview over an implementation for the pdp 11 computer family; it shows the range in the definition of such a macro library. Based on this lowest level three methods to implement system requests in real-time languages are discussed. If the language allows assembler insertions the macros can immediately be used. If the real-time facilities of the language are connected via subroutine calls, they are realized by adding code procedures which contain the corresponding macros. In the third case, real-time operations are part of the syntax and can be compiled using the macros as inline code or generating adequate subroutine calls. These three methods are discussed with respect to readability, portability, software-safety, runtime efficiency and implementation costs. Implementations are illustrated by a few examples.

Applications of a Scattering Spectrometer System for Marine Aerosol Measurement

A newly developed instrument has been successfully evaluated and applied to the measurement of marine aerosols. The instrument, known as the Scattering Spectrometer System (SSS), utilizes coherent scattering of laser radiation to size marine aerosols in flight and produce size distribution data in real time. Compared to current methods of using source cascade impactors, the SSS was found superior in terms of resolution, data reduction simplicity, and real-time capability. The application of the SSS at the Naval Air Propulsion Test Center (NAPTC) includes real-time facility diagnostics, control, and calibration. Novel information concerning aerosol separators has also been uncovered using the SSS.

A review of the London Hospital computer project

The paper reviews the key decisions taken in the implementation of The London Hospital Real-Time Computer Project. The advantages of the use of real-time facilities lie in the rapid availability of...

A clinician's approach to computer-based medical record systems

The medical record is a major factor in patient care and has many functions which the clinical user accepts without thought. Analysis reveals these functions in detail and shows up the limitations of present systems. It is seen that, as well as the more obvious functions of storage and communication of information, the medical record has importance as a medico-legal document and that, because of this, more thought needs to be given to the problems of identification of the various contributors. Along with these problems is the whole question of confidentiality which at present, because of the number of individuals who have access to the complete record, is largely in name only. The management of a hospital ultimately derives its basic data from the medical record. At present the nursing record is kept separate from the doctor's record until the patient's discharge, but because of this much duplication takes place and interaction between the two could avoid this. The application of computer techniques could do much to improve the flexibility and content of the medical record. Various methods of input and of interrogation have been tried, but the most applicable and useful appears to be the computer-driven visual display unit, giving a real time facility. Of the various schemes in use, that using branching display techniques gives the quickest input and allows much standardization of vocabulary, since the words and phrases the user may require are stored by the computer and presented in a logical sequence. Free text must be allowed but is used in the knowledge that future analysis will be extremely difficult, if not impossible. Careful display design should minimize the use of free text. The application of such a system to the nursing record will be very challenging and difficult. By the use of a computer system, the communication function of the record can be immeasurably improved.

A teleprocessing approach using standard equipment

The techniques described have all been implemented and are working well in an on-line environment assisting control of a vital national facility. The teleprocessing design is not just a technique to combine low-speed and high-speed terminals in one general package; it also provides a basis for development of techniques to provide real-time control facilities on standard general-purpose equipment and support programs. This basis is achieved by the automatic, on-line philosophy of the teleprocessing control program. This program is designed to run 24 hours a day, 7 days a week with minimal operator intervention. No external contact between operators of the central system or the terminal is needed. The foundation is laid for the next development, that of entering direct monitoring signals into the TCP and initiating appropriate calculations or responses. The multiprocessing control by ASP fulfills the reliability consideration of such a system, and it is feasible to build on this to provide automatic reconfiguration after failure, which is a requirement of real-time control. Already, the system described here is capable of reinitializing and restarting itself from an intermittent equipment or program failure, and is running in the environment of a normal batch job processing system.

A demonstration hybrid computer for real-time flight simulation

A hybrid, real-time simulation facility has been de signed, constructed, and demonstrated, using as a test vehicle the complete aerodynamic and engine equations for a high-performance military aircraft. The analog-digital configuration employs peripheral analog equipment to represent a linear, skeleton version of the aircraft and the PDP-1 digital com puter to carry out engine simulation, decision man agement, and corrections for nonlinear effects. To provide an all-digital reference against which the hybrid simulation could be compared, the air craft model was also simulated in real-time on the PDP-1 alone. It was found that the solution rate of 20 per second employed in the all-digital study could be reduced substantially without deleterious effects when the hybrid configuration was used. Such a re duction demonstrates that supplementing a digital computer by relatively inexpensive analog peripheral equipment greatly increases the real-time capacity of the digital computer in complex simulation appli cations. Moreover, because a number of key variables are computed continuously in the analog domain, the introduction of analog equipment results in a net decrease in the complexity of the interface.