Fast System Response Research Articles

The Design of a Solid State Trip System for Nuclear Power Plants

In this paper, a new nuclear safety system has been devised that promises a great reduction in the unavailability of conventional systems of compatible arrangement. Four principal design approaches are combined to realize this improvement. The first is the employment of solid state devices throughout the system for achieving not only a much faster system response, but also a better reliability. The second involves the application of sequential redundancy, so that the effective system operation can be maintained by a standby unit in the event of a failure in the principal system. The third approach employs the concept of cellular automata in failure detection and switching functions. Finally, the fourth design approach provides an automatic shift from 2 out of 3 to 2 out of 2, whenever a channel is rejected.

The design of a solid state trip system for nuclear power plants

In this paper, a new nuclear safety system has been devised that promises a great reduction in the unavailability of conventional systems of compatible arrangement. Four principal design approaches are combined to realize this improvement. The first is the employment of solid state devices throughout the system for achieving not only a much faster system response, but also a better reliability. The second involves the application of sequential redundancy, so that the effective system operation can be maintained by a standby unit in the event of a failure in the principal system. The third approach employs the concept of cellular automata in failure detection and switching functions. Finally, the fourth design approach provides an automatic shift from 2 out of 3 to 2 out of 2, whenever a channel is rejected.

Control aspects of a tracked magnetic levitation high speed test vehicle

The paper deals with the control system of the high speed test vehicle KOMET. The control hardware configuration consisting of digital computer, interface, sensors, magnet drivers and magnets is described. Control system synthesis is performed based on the state space approach and the classical approach of the z-transform. It leads to various control concepts, which are evaluated with regard to their responses to guideway irregularities, external forces and their sensitivity to plant parameter variations. The measurements used to reconstruct the state vector are magnet gaps, vehicle accelerations and/or magnet currents. To be efficient, the magnets have to be operated on small magnet gaps. This demands a fast system response to external disturbances and guideway inputs. This in turn may lead to the excitation of the elastic modes of the system. The higher order modes of vehicle and guideway are therefore included in the control synthesis. The speed range of the KOMET extends to 400 km/hr. Results from high speed testing are evaluated with regard to system responses, power requirements, and loss in magnetic force due to eddycurrents.

Design of Fast Response System

The quick response indicators usually have large settling time. The present approach is an attempt to reduce the settling time in instruments having second-order system behaviour. Here the system behaviour is changed automatically by electronic switch from underdamp to critically damp which ultimately reduces the transient response to a great extent from 2.95 ms to 0.75 ms. The device is solid-state and portable.

Increased Control and Data Acquisition Capabilities via Microprocessor-Based Timed Reading and Time Plot CAMAC Modules

By implementing a microprocessor-based CAMAC module capable of being programmed to function as a time plot or a timed reading controller, the capabilities of the experimental area serial CAMAC control and data acquisition system at Fermilab have been extensively increased. These modules provide real-time data gathering and pre-processing functions synchronized to the main accelerator cycle clock while adding only a minimal amount to the host computer's CPU time and memory requirements. Critical data requiring a fast system response can be read by the host computer immediately following the request for this data. The vast majority of data, being non-critical, can be read via a block transfer during a non-busy time in the main accelerator cycle. Each of Fermilab's experimental areas, Meson, Neutrino and Proton, are controlled primarily by a Lockheed MAC-16 computer. Each of these three minicomputers is linked to a larger Digital Equipment Corporation PDP-11/50 computer. The PDP-11 computers are used primarily for data analysis and reduction. Presently two PDP-11's are linked to the three MAC-16 computers.

An Aquifer Model for Fissured Reservoirs

Abstract A model has been developed for describing aquifer influx in a fissured reservoir. This model includes petrophysical properties of good and poor rock, as petrophysical properties of good and poor rock, as well as fissure parameters. For the applications considered thus far, it has been found that flow in the fissures dominates the aquifer performance and that rock properties and spacing between fissures are of lesser importance. For a given aquifer, the fissure permeability and fissure volume fraction appear to be important parameters, as are rock permeability and porosity in cases of a high permeability and porosity in cases of a high percentage of poor rock. percentage of poor rock Introduction The use of material balance has been well established in analysis of reservoir performance. For water drive reservoirs, it is usually desirable to have a functional description of aquifer behavior. Such a description is provided by the functions obtained by van Everdingen and Hurst for homogeneous and isotropic reservoirs. This method uses one set of values of permeability, porosity, and compressibility, and usually requires some history matching or curve fitting for determining the best values. Functions analogous to those of van Everdingen and Hurst also would be useful in reservoir performance studies of fissured reservoirs. Any performance studies of fissured reservoirs. Any attempt to formulate a realistic model for such systems, however, will usually confront the problem of insufficient knowledge of aquifer properties. There usually will be a comparatively large number of degrees of freedom corresponding to parameters introduced into the theory. Nevertheless, such a model should provide insight into the relative importance of certain variables. It may also serve as a framework in which more accurate information, if eventually obtained, could be used. Pressure behavior was used to study fissured reservoir properties by Pollard, who characterized the pressure buildup by three exponentials. These exponentials corresponded to a skin near the well, transient behavior in the fracture system, and transient flow of fluid from matrix to fissures. A characteristics feature of fissured reservoir systems and the reservoir fast fluid pressure response of the fissure system compared with response in the porous matrix. A model that treats this aspect porous matrix. A model that treats this aspect appropriately as proposed by Warren and Root, who assumed that flow of fluid from matrix to fissures could be treated as quasi-steady state. The problem of transient pressure distribution within an actual block of the reservoir was thereby circumvented. This model was further studied by Odeh. Kazemi replaced the network of fractures with an equivalent set of horizontal fractures and solved numerically for pressure distribution in fissures and matrix. Because the dimensionless time scale based on fracture properties and well radius was long, Warren and Root and Odeh were able to use the long-time solution for the constant terminal rate case of pressure behavior in an oil reservoir. In the present instance, the inner aquifer radius may be quite large, so that we must consider smaller dimensionless times, and will require a general solution. The actual times of interest, however, will not be so small as to invalidate the model. This model is being considered for use in fissured carbonate reservoirs where two basic rock types, defined in terms of porosity, are sometimes specified. In such cases, the rock permeabilities usually are very much smaller than the fissure permeability, The matrix can be considered as permeability, The matrix can be considered as being made up of good and poor rock. Wide variations in rock type are often encountered in carbonate reservoirs. The designations of good and "poor" are largely arbitrary. A typical example would be: good porosity greater than 12 percent, and poor-porosity 2 to 12 percent, with the remainder poor-porosity 2 to 12 percent, with the remainder of the rock nonproductive. In some cases, however, it may be sufficient to specify only one rock type. In studying the constant terminal pressure case it is desirable to reformulate the fissured reservoir model to include the additional features of change, boundary conditions and two basic rock types. SPEJ P. 385

Control Aspects of a Tracked Magnetic Levitation High Speed Test Vehicle

Summary The paper deals with the control system of the high speed test vehicle KOMET. The control hardware configuration consisting of digital computer, interface, sensors, magnet drivers and magnets is described. Control system synthesis is performed based on state space approach and the classical approach of z-transform. It leads to various control concepts, which are evaluated with regard to their responses to guideway irregularities, external forces and their sensitivity to plant parameter variations. The measurements used to reconstruct the state vector are magnet gaps, vehicle accelerations and/or magnet currents. To be efficient, the magnets have to be operated on small magnet gaps. This demands a fast system response to external disturbances and guideway inputs. This in turn may lead to the excitation of the elastic modes of the system. The higher order modes of vehicle and guideway are therefore included in the control synthesis. The speed range of the KOMET extends to 400 km/h. First results from high speed testing are evaluated with regard to system responses, power requirements, and loss in magnetic force due to eddycurrents.

The continuous preparation of cattle diets containing ground straw: I. A low horse-power straw milling plant

The application of a new system of feeding beef cattle is currently limited by the lack of suitable equipment for milling straw. Farm electricity supplies are usually inadequate for the direct milling of straw bales, hence a 2-stage operation of chopping and then milling is proposed. The high specific power requirement of milling straw together with its variable moisture content indicate the need for automatic control of the mill feed, therefore a fast response system of augering chopped straw into a standard hammer mill fitted with a high torque motor has been developed and tested. With commercially available components it has been found that a printed circuit motor drive to the auger gives the most satisfactory results.

Variation of Lateral Gustiness with Wind Speed

Abstract The variations of lateral gustiness with wind speed were studied using a light-weight, fast-response wind system coupled to an automatic sampling system. Accuracies of 1° in determining the width of the wind direction distribution and 1 km hr−1 in determining wind speeds above the 1 km hr−1 threshold were obtained. Results show a decreasing trend of lateral direction fluctuations with increasing wind speed, for speeds >2 m sec−1. For winds <2 m sec−1, direction fluctuations increase with increasing wind speed, both during stable and unstable conditions. It is suggested that increasing wind speed is necessary to provide the energy to overcome pressure resistance to lateral fluctuations, which therefore increase with wind speed. This result is consistent with continuity considerations. At higher wind speeds, increasing air momentum results in a decrease of fluctuations with increasing wind speed. The product of wind speed and the width of the lateral fluctuation distribution increases monotonically...

A JOINT STATE-INDUSTRY PROGRAM FOR OIL POLLUTION CONTROL

ABSTRACT This paper describes a project undertaken to establish specific measures for reducing the threat of oil pollution and to respond more effectively to oil spills in an intensely utilized estuarine area near Boston. Its recommendations are the result of a study of potential sources of pollution and the mechanisms that spread it. To help design a fast-response system for containing and removing spilled oil, the study team developed a computer program that could predict the probable path of oil spilled anywhere in the area under various conditions of wind and tide. This information was used to select locations for containment devices and determine the speed with which they would have to be deployed. The study was supported by the Massachusetts Division of Water Pollution Control and aided by the active cooperation of local industries through a joint industry committee.

Density Sensor Utilizing Positrons

A positron source and detector of annihilation quanta are shown to form a fast response system that senses changes in its environment. Experimental results are presented to demonstrate that such a sensor can be used to measure gas densities. A particular densitometer design has been calibrated for air at room temperature over the pressure range 100-mm Hg&amp;lt;p&amp;lt;760-mm Hg, the particular pressure range being determined by the limitations of the vacuum chamber used in the calibration. The counting rate has been observed to vary linearly with pressure. Expressions are given for the sensitivity and the statistical uncertainty as a function of source strength, counting interval, and thickness of beryllium covering the source. Experimental results are also presented which demonstrate that the presence of a solid in the field of the positrons can be detected. The observed counting rate is a function of the distance of the solid from the sensor.

A Dual Mode Suboptimum Minimum Time Control of Higher Order Systems for Step Displacement Inputs

In this paper a dual mode suboptimum minimum time control of a high order system with negative real roots and with inputs restricted to step displacement input has been discussed. In this dual mode suboptimum minimum time control, the mechanization of the switching computer is simplified by initially reducing the number of switching reversals by forcing some of the higher order derivatives of error to zero at the switching instant and secondly by realizing linear switching boundaries by modifying the magnitude of the actuating input. To combine the good steady state accuracy of the linear system with the fast response of the suboptimum system, the system is connected in the linear mode near the steady state point using a linear switching boundary.A third order example has been studied and the performance of the sub-optimum system has been compared with the optimum systems. A third order system with coulomb friction has also been studied.

Responses of perfused isolated leg preparations of the cockroach, Gromphadorhina portentosa, to L-glutamate, gaba, picrotoxin, strychnine and chlorpromazine.

AbstractA perfused leg preparation of Gromphadorhina portentosa (Orthoptera) was developed for use in pharmacological studies and bioassay procedures. Study of tibial flexion with increasing stimulation intensity at low frequency revealed five fast motor units. Chlorpromazine (2.5 × 10−4 M) progressively blocked these motor units. GABA generally failed to affect fast system responses, even at high concentration (2.5 × 10−4 M). A high concentration (2.5 × 10−4 M), picrotoxin produced effects consistent with the interpretation that motor axon excitability was affected. Strychnine (2.5 × 10−4 M) produced no effect on isolated leg preparations. L‐Gultamate (pH 7.2) produced contractures; the threshold for this response was 2.5 × 10−4 M. Contractures were produced after application to resting muscle, and were also observed in preparations receiving low frequency indirect stimulation. The response to glutamate under the latter condition closely resembled incomplete tetanus. L‐Glutamate (2.5 × 10−4 M) produced a reversible depression of kick force in locusts. These responses are compatible with the hypothesis that L‐glutamate is an excitatory neuromuscular transmitter in insects.

Numerical Hilbert transform and automatic phase correction in magnetic resonance spectroscopy

Methods for the automatic correction of the phase of magnetic resonance spectra by means of a numerical Hilbert transformation are described. The problem of the Hilbert transform of a sequence of discrete sample values is analyzed. The direct Hilbert transform and the indirect Hilbert transform through intermediate Fourier transformation are compared; the latter is found to be more efficient with respect to computing time. It is shown that any linear fast passage response of a linear system obeys Kramers-Kronig relations; particularly, fast passage absorption and dispersion mode spectra are Hilbert transforms of each other.

Positive-feedback phase-space trajectories and application to servo systems

The phase-space trajectories for second- and third-order positive-feedback servo systems are investigated. These trajectories, together with the negative-feedback phase-space trajectories, are used to design fast-response servo systems, which switch back and forth between positive and negative feedback modes. The approach used for the third-order systems may be applied to higher order systems. Experimental results of simulated systems are presented.

A Fast-Response Resistance Thermometer System for Simultaneous Recording of Air Temperatures at a Number of Separated Points1

A resistance-thermometer system is described which permits simultaneous and continuous recording of air temperatures at a number of separated points. Unbalance current in a Wheatstone bridge network is used as the measure of temperature, and is recorded by a multichannel light-beam oscillograph. The lag coefficient of the system is approximately 0.1 second.