Small Digital Computer Research Articles

Electronic digital computer control of ventilation and anaesthesia.

The use of a small digital computer to control a number of interactive physiological variables is demonstrated. It is shown that by monitoring the values of end tidal per cent CO2, inspired O2 percentage and mean arterial blood pressure, a computer-controlled system can regulate the ventilation and anaesthesia of an animal within fine tolerances. Similarly it is shown that by controlling the infusion of muscle relaxant, the integrated electromyogram of a muscle can be maintained at any desired level. The computer control system automatically allows for random disturbances in system parameters in maintaining set levels of the controlled variables. The system responds rapidly to changes in the desired level of variables, and prescribed time courses of variables can be followed.

A study of precision in modern liquid Chromatography using a dedicated computer

The on-line coupling of a small digital computer to a liquid chromatograph is described. A new real-time language, MIRACL II, is used for programming. The experimental set-up is presented and a ndw automatic sample loop valve is described. The system has been studied in terms of the precision in peak area, peak height and retention attainable with commercial liquid chromatographic equipment. Precision in peak area and height is found to be significantly improved with the sampling valve relative to syringe injection. The influence of several pumping systems on precision was also studied and marked differences in the relative standard deviations of peak area and height were found. The relationship of the relative standard deviation of the peak area to sample size has also been studied. In addition, the important role of the flow-rate of the mobile phase on detection limits and precision is shown. Finally, some results are presented on the reproducibility of retention over short and long time periods.

An on-line digital-computer system for the semiautomatic analysis of Golgi-impregnated neurons.

Rapid and accurate measurements of neuronal processes in Golgi preparations are possible with the aid of a small computer (Glaser and Van der Loos, 1965). This paper describes a system for doing this, using a small digital computer which controls stepping motors (0.5-?m steps) attached to the stage (x, y axes) and fine focus (z axis) of a microscope. The observer tracks the processes, topological information, such as the location of the soma, dendritic origins, branch points, and ends of processes, is signaled to the computer by special controls, and the x, y, and z coordinates of each are stored in digital format. The computer printout yields 1) individual x, y, and z coordinates with associated topological identifiers; 2) quantitative data for each dendritic segment in order (i.e., primary and secondary branches, etc.); and 3) computes the actual linear dimensions of each segment in microns. An associated oscilloscope display can 1) display the whole neuron, or individual processes, by connecting recorded points by vectors; 2) identify each dendrite; 3) rotate (continuously or by a specified angle) the whole cell, or individual dendrites, around any selected point or axis; and 4) indicate spatial relationships by dynamic rotation, intensity modulation, or stereo pairs. The performance of this system has been evaluated for accuracy and the repeatability of measurements.

An Array Simulation Facility

A system employing a small digital computer and a multichannel tape recorder produces a set of signals simulating those obtained from the elements of an array when a source moves through its field of view. Source and array may be two-dimensional, the source may move in real time and a change in the array or source characteristics is simply a program change. The principles of operation and two test simulations are described.

An on-line computer system for the acquisition and analysis of temperature jump data

A system for the on-line acquisition and analysis of chemical relaxation data by a small digital computer has been developed. The system is designed so that knowledge of specialized digital electronics and logic is unnecessary for its implementation and a variety of fast reaction instrumentation can be serviced. Programs are discussed which analyze the relaxation data rapidly, yielding values for the amplitude and the reciprocal relaxation time of the kinetic process. Signal averaging of repetitive measurements also is described. The data can be stored on punched paper tape. Typical experimental data and the resulting data analysis are presented.

Analysis of gamma-camera imaging data by a small digital computer.

The use of a small digital computer system can substantially extend the diagnostic usefulness of a gamma-camera, particularly by allowing rapid manipulation of dynamic data. It also has a real place in complex functions such as flat-field correction and dual isotope substraction. (auth)

Design and Application of a Time-Optimum Controller for a Class of Nonlinear Processes

A procedure was developed to extend time-optimum control of linear processes to a class of nonlinear processes consisting of a second-order overdamped linear process followed by a nomemory nonlinearity. Bang-bang control was combined with a proportional-integral-derivation (PID) controller to achieve time-optimum control for set-point changes and good regulator operation for minor disturbances. This dual-mode controller was implemented with a small digital computer. The settling time for step set-point changes with dual-mode control was compared to that with PID control alone. A factor of 2 improvement was achieved through time-optimum control. The dualmode control was successfully applied to an actual nonlinear process.

Computer Aided Maintenance: A New Discipline for Developing Countries

Computer Aided Maintenance is a new discipline suggested by the specific conditions in the developing countries. Its final objective is to work out simple programs for small digital computers which, (a) based on data measured with unsophisticated instruments, (b) detect and (c) localize the fault (if any) in the equipment, (d) suggest the part or parts to be replaced, (e) give a list of devices which may replace it from the local market (f) give warning of the failures which can be expected as the consequence of the original defect and (g) keep account on the failures occurred and (h) furnish necessary statistical data for the future spare purchases. This paper suggests some of the maintenance problems encountered in developing countries, some aspects of maintainability from their standpoint, and presents the first practical results achieved in work on Computer Aided Maintenance

Computer controlled voltage clamp experiments.

A small digital computer (a Digital Equip. Corp. LINC-8) has been interfaced to voltage clamp control circuitry and a buffer memory in order for it to both control experiments and provide fast and flexible data acquisition. The experiments are designed and run from the computer graphic terminal in a conversational language, offering the experimenter programmed control over input voltage-time patterns and the rate of data sampling. Because many records are usually required and biological preparations tend to deteriorate with time, automated experiment control and faster data acquisition and storage provides more dependable data than manual methods. Subsequent analysis is much more convenient when the data has been stored along with parameters values and labels in a standard format on a digital bulk storage device such as a magnetic tape or disk.

Optimal Aircraft Go - Around and Flare Maneuvers

This paper analyzes in detail two of the critical aircraft maneuvers associated with approach and landing: the go-around maneuver and the flare maneuver. Optimal solutions that include state and control variable constraints are obtained for both problems. Two algorithms are given for computation of the minimum and maximum altitude loss associated with the pilot-controlled go-around maneuver. A matrix operator is obtained that can be used for in-flight computation of the altitude loss on a small general-purpose digital computer. The flare optimization presented is for a cost functional that includes both the longitudinal touchdown dispersion and the normal acceleration. A closed-loop mechanization is given that approximates the optimal trajectory. A second matrix operator which can be used for prediction of the longitudinal touchdown point is obtained. Uncertainties are also obtained for the purpose of establishing a prediction confidence level. It is proposed that these prediction techniques should be incorporated into a decision making performance monitor. This monitor could provide the pilot with a continuous assessment of the approach and could generate a preflare decision on whether or not to commit the aircraft to the flare maneuver.

Simulation on large batch and small interactive digital computers

A simple model for determining the costs of simula tion on two types of simulation systems is developed. One system is the batch-oriented S360/CSMP system operating on an IBM 360/50 computer. The other system is an interactive simulation system operating on a DEC PDP-12 computer. The workload considered includes six problems of varying complexity and is "typical" of those simulation problems encountered in undergraduate and graduate simulation courses. The model indicates that if only a few simulation runs are required, the PDP-12 system is the more cost effective of two systems. The S360/CSMP system, how ever, rapidly becomes more cost effective as the number of simulation runs increases. The factors affecting various cost tradoffs are indicated, and the model is evaluated for a selected set of parameters.

Computational processing of palatographic patterns

The time courses of articulatory movements and their random variation have been studied by recording palato-lingual contact patterns by use of a thin artificial palate with a number of implanted electrodes. The data were obtained from one subject for 25 repeated utterances of a carrier sentence in which a nonsense Japanese word of the form /aCa/ was embedded, where C represented one of nine consonants characterized by tongue tip articulations. Quantitative results have been obtained by recording, in real time, both the digitized palatal signals and analog speech waveforms and then processing the data in a small digital computer, deriving in particular four characteristic patterns for each consonant. The tense-lax characteristics of the Japanese /t/ and /d/ are briefly discussed as well as the articulatory characteristics of the flap /r/.

Aliasing in the time domain for the estimation of power spectra

When power spectral analysis is performed on a small digital computer, it is usually necessary to use a non-uniform data window in order to obtain desired spectral window properties. Unfortunately, this leads to loss of resolution and increased correlation between estimates without a corresponding reduction in their variance. It is shown that aliasing in the time domain may be used to restore resolution and reduce the correlation between spectral estimates when it is desired to maximize the information computed in a specified time, while optimal use of data is not important. The technique is particularly useful when data loss would otherwise occur in real-time analysis because the data processing rate is lower than the sampling rate.

Performance of a 5 kVA synchronous generator with an optimal excitation regulator

The feasibility of applying optimal control to the excitation of a synchronous generator is examined in the laboratory, using a 5 kVA 3-phase alternator connected through line reactors to an infinite busbar. The regulator is a small digital computer, which monitors the states of the system and computes the control signal applied to an electronic amplifier exciting the alternator field. The feedback gains of the optimal regulator satisfy a simple quadratic cost function. These are calculated offline for a grid of operating points in the complex power plane, and stored in the controlling computer. The gains used at any particular operating point are those corresponding to the nearest gridpoint. Comparisons of predicted and actual small-disturbance responses are made for leading-power-factor operation well beyond the open-loop stability limit, and, for low real power, beyond the closed-loop limit with voltage feedback alone.

On-line analysis of optokinetic nystagmus by small general purpose digital computer.

A program for a small general purpose digital computer was developed to analyse electro-oculograms of optokinetic nystagrnus in monkeys. It provides immediate print-out of means and standard deviations of maximum velocity of fast phases, velocity of slow phases, amplitude, total deviation during slow phases and number of nystagmic beats occurring in 15 sec trials. It has also the potential to measure other response features and the constants can be easily changed for application to individual circumstances. The validity of the system was verified by both simulation and sample analysis. The small size and relatively low cost of the equipment makes the system ideally suited for “on-line” close-loop experiments in the physiologic laboratory and for rapid quantification of data in the clinical setting which would allow evaluation of normal and abnormal eye movements under a variety of conditions within the same session.

Computer-Controlled Refueling Machine at Fort St. Vrain

The refueling system for the Fort St. Vrain Nuclear Generating Station uses a small digital computer for automatic control to handle approximately 3000 fuel and reflector blocks which constitute the reactor core. The computer has complete control of the handling mechanism, which has four freedoms of motion, and also logs information concerning all fuel movements for inventory purposes. Since safety is a prime consideration in equipment associated with a nuclear power plant, a combination of hardware and software protection monitors provides for fail-safe operation. Operating experience has proved that automatic control of the fuel handling process is approximately five times faster than manual operation with the same machine. In addition, operator errors are eliminated and an accurate log of all fuel movements is recorded.

Post‐buckling analysis of non‐uniform elastic columns

AbstractA numerical method for the second‐order analysis of elastic beam‐columns is described. For nominated values of axial load and end moments the deformed states and stress distribution can be determined by an automatic iterative procedure. For centrally loaded columns of non‐uniform section, the method can be used to predict the critical loads from the grossly deformed equilibrium states above the first critical load. Axial and shear strains may be accounted for as well as flexural strains. Solutions for the shape of the elastica can be obtained for non‐uniform columns. The method requires a small digital computer and is demonstrated for several plane, uniform and stepped elastic members. It can be readily extended to deal with transverse and distributed axial loading as well as flexural‐torsional behaviour.

A real-time speech synthesis system

A system for synthesizing speech is described. It consists of an electronic synthesizer controlled by a small digital computer. The computer uses stored rules to convert a phonetic input into the analogue voltages required for driving the synthesizer. It has been found possible to make the system operate in real time so that the acoustic output is generated at normal speaking rates.

An improved ultrasonic scanning system employing a small digital computer.

Abstract An ultrasonic scanning system is described in which the ultrasonic probe follows a cartesian raster pattern. The scanner has been connected to a small digital computer which enables scans to be recorded rapidly and displayed later. Echoes arising from tissue interfaces are digitized at a sampling rate of 670 kHz and stored directly in the computer memory. This sampling rate corresponds to a depth sampling interval of 1 mm. The ultrasonic beam axis is perpendicular to the raster scanning plane and at each position on the raster, a complete set of echoes (“A” scan) is stored and transferred to magnetic tape. When the raster has been covered the tape will contain echo data for a three-dimensional scan. Data for any plane of interest may then be selected from the tape and displayed on a storage oscilloscope or X–Y plotter. Echo intensity is represented by squares of variable size. The size of square which corresponds to a given intensity is set by threshold levels and these may be adjusted until the ...

The Mechanism of the Zinc(II)‐Zinc Amalgam Electrode Reaction in Alkaline Media As Studied by Chronocoulometric and Voltammetric Techniques

The reduction of zinc (II) and the oxidation of zinc amalgam was studied in solutions. The primary electrochemical technique employed was potential step chronocoulometry with data acquisition on a small digital computer. The kinetic parameters were obtained by fitting the experimental charge‐time curves to the complete theoretical equation for a stepwise electron transfer mechanism. The sytem was also studied by d‐c and a‐c polarography and linear scan voltammetry. The results of this study were compared to those of previous workers and shown to be consistent with a mechanism based on stepwise electron transfer