Determining Surface Potentials from Current Dipoles, with Application to Electrocardiography

This paper presents a method for determining the potentials over the surface of a three-dimensional volume due to internal current sources. The volume may be inhomogeneous and irregularly shaped. The method for determining the potentials uses N simultaneous equations which when solved produce the potentials at N different surface points. The N simultaneous equations are solved by an iterative technique on an IBM computer.     

Epidemiology

A simple problem in epidemiology is described. The purpose is to demonstrate how computers, analog im this paper, can be used to assist the student in visualizing a complex system. The very act of creating the necessary equations to describe a system forces the experimenter to crystallize his understanding of the system. When, and usually if, the computer simulation does not match the data, the investigator must revise his model. Several iterations result in a more accurate understanding of the system being studied. The analog computer is a handy tool for performing rapid parameter studies and model revisions at low cost. More scientific investigators need exposure to the advantages of small low-cost computers.     

On-Line Real-Time Digital Computer Separation of Extracellular Neuroelectric Signals

An on-line real-time spike recognition and separation system for up to six different spikes in multiple unit extracellular records has been developed using the Micro-LINC 300 computer. Assuming biphasic potentials, the computer extracts four unambiguous variables, two in amplitude and two in time. One variable of a selected pair is plotted against the other on the computer CRT. Points representing the same class of signal will fall into clusters. Cluster boundaries for spike separation are set visually by the investigator. Output is in the form of pulses on different relay lines. The system permits waveforms to overlap up to 15 percent. Examples of system performance with real signals are presented. A comparison is made with other spike recognition systems. A simple system is presented for generating artificial test signals and a technique described for testing any spike recognition system.     

A 4-bit Josephson computer ETL-JC1

The first computer operation of a 4-b Josephson computer, ETL-JC1 (Electrotechnical Laboratory-Josephson Computer no.1), designed using a reduced instruction set computer (RISC) architecture is described. In the experiment, the computer functions have been verified by executing a computer program installed in a Josephson read-only memory (ROM) at a low repetition frequency. To construct the computer, four Josephson LSI chips including a register and arithmetic logic unit, a sequence control unit, an instruction 1280-b ROM unit, and a 1-kb RAM unit were connected on a nonmagnetic printed circuit board. The Josephson LSI chips were fabricated using Nb/AlO_x/Nb tunnel junctions with 3-μm design rules. The total power dissipation was 6.2 mW in the total circuit, which consists of 22000 junctions including regulators on every chip. On the basis of measurements of the delay times of the logic gates and the access times of the memory chips, it is expected that the program execution in the critical path can be carried out with a single central processing unit in less than 1 ns, resulting in 1 giga-instructions per second (GIPS)     

An investigation into the use of iteration methods for the analysis of axially symmetric and sheet beam electrode shapes with an emitting surface

The techniques for analyzing an axially symmetric or two-dimensional electrode system with an emitting surface have been studied with a computer program. The program is very easy to use and performs in one pass the steps which have usually previously been followed on analog and digital devices separately. The program alternately solves Poisson's equation by a relaxation technique, traces trajectories, recomputes the space-charge distribution and again performs a relaxation process. This procedure continues until satisfactory convergence has been achieved. The ease of use of the computer program has allowed the investigation of different methods of speeding up the convergence. The results are illustrated with two specific examples.     

Fault Isolation in Conventional Linear Systems: A Progress Report

A computer program is described which implements a previously suggested procedure for isolating faults in conventional linear systems. The technique is based on the analysis of network function responses at critically chosen test frequencies applied to the normal input-output terminals of the circuit under test. The feasibility of the diagnosis technique is discussed in terms of the experience with the computer program and some empirical studies which have been conducted. Example circuits are included which have been processed by the computer program. Problem areas related to both the basic theory of the technique and the computational limitations of implementation are defined. Solutions are proposed for some of these problems; others are merely defined for study by the circuit theorists.     

The Position of Innervation Zones in the Biceps Brachii Investigated by Surface Electromyography

A linear surface electrode array placed along the muscle fibers detects motor unit action potentials propagating bilaterally to the tendons. The location of the propagation source is presumed to mark an innervation zone. We developed a computer program, which automatically determined the potential source by applying a correlation calculation and a linear regression to the recorded signals. The spacing between the contacts in the electrode array was 5.0 mm, whereas for some recordings the histogram indicating the position of estimated source had a sharp peak concentrated in a 1.0 mm area. In the biceps brachii some subjects were found to have two innervation zones separated by 10-20 mm. The peaks corresponding to the innervation zones differentially changed their histogram scores according to the contraction force. We also constructed an electrode assembly, which had four columns of the linear electrode arrays, and clarified the distribution of the innervation zones in the biceps brachii.     

A Computerized Klinger Cavity Mode Conversion Test Set

A mode conversion test set utilizing the klinger cavity technique has been developed for characterizing circular waveguide components in the millimeter waveguide region. The test set incorporates a precision linear displacement optical encoder and a specially designed controller which interfaces the test set to a Hewlett-Packard 2100 series computer. Control commands of a stored computer program are used by the operator for data acquisition and analysis. Experimental results show this system has high measurement accuracy and sensitivity while maintaining an uncomplicated measurement process.     

A comparison of spherical wave boundary value matching versus integral equation scattering solution for a perfectly conducting body

A spherical-wave expansion (SPEX) technique for calculating the scattering from a smooth perfectly conducting body is presented. Sample case results are compared with the well-known Lawrence Livermore National Laboratory Numerical Electromagnetics code (NEC), which is based on the integral equation formulation. The internal fields are computed for both results using a third surface current integration program, which is totally independent of both SPEX and NEC. The internal fields, which would be zero for a perfect solution, are much more sensitive to the currents than the scattered fields. The SPEX solution, which uses fewer unknowns and less computer time than NEC, also produces a lower internal field. The SPEX technique also allows a direct check on satisfaction of the boundary condition at any set of points on the surface, independent of the points used to obtain the solution. This provides a valuable built-in test feature for quickly validating results, which is one of the most attractive features of the technique.     

Convergence and accuracy criteria of iteration methods for the analysis of axially symmetric and sheet beam electrode shapes with an emitting surface

Convergence and accuracy criteria have been determined for computer techniques analyzing an axially symmetric or two-dimensional electrode system with an emitting surface. The convergence criterion has been drawn from analytical studies of the one-dimensional model and verified numerically by the computer program for an analytically designed, axially symmetric Pierce-type electrode system. The accuracy of the computer program is illustrated with two electron gun configurations of known analytical solutions, and comparison of cathode current emission, beam minimum radius, and its location is made with experimental data of a high perveance Pierce-type gun.     

A computer algorithm for accurate and repeatable profile analysis using anodization and stripping of silicon

The increased need for accurate and repeatable impurity profiling of shallow junction devices places stringent requirements on the profiling procedures and subsequent data reduction. A computer algorithm is described which simplifies the conversion of sheet resistance to impurity profile as required by the anodization and stripping technique. Error magnification commonly found in discrete data differentiation is avoided. Empirical mobility vs carrier concentration expressions are derived from several sources, and a self-contained computer algorithm is given which allows for data reduction on commonly available minicomputers using Fortran. The experimenter is provided with a check on the accuracy of the profile information.     

System diagnosis with FLIP

This paper presents a graphical technique implemented as a computer program called FLIP, whose main function is to select a minimal set of test points required to achieve 1 — distinguishability of failures in a system. In support of diagnostic test activities, fault signatures are also generated for every system failure, where the level of fault isolation is defined by the graphical model drawn of the system or subsystem. The paper shall first outline the theoretical basis upon which FLIP was developed, then briefly describe the various capabilities of the program, and finally discuss a specific application to electronic system diagnosis.     

Uniqueness of the generators of brain evoked potential maps

This study considers the uniqueness of neuronal generators of human brain evoked potentials measured on the scalp using the physical and mathematical properties of the volume conductor model. The results are applicable to a realistic, nonhomogeneous head shape where the potential map is known on a continuous set of points on the scalp. It is shown that sources which occupy “zero volume” in space such as point dipoles or sources distributed on an open surface or a line are uniquely defined by the potential maps. Finite volume nonoverlapping sources are also uniquely defined by their potential map. However, there are infinitely many different but overlapping sources which can create the same map. Several examples of such sources are provided. It is shown that there is a unique, minimum volume source which can be defined in this case. Results suggest that if a reconstruction of the sources starts from a continuous scalp map (obtained by interpolation of the data between electrode sites), one can obtain unique results concerning the source parameters that are not available in a search for a source whose potential map fits only at a discrete set of points     

Active IMPATT Diode Parameters Obtained by Computer Reduction of Experimental Data

This paper describes a method of determining the junction parameters of an IMPATT device from basic microwave measurements through the use of a computer program. The technique, which evaluates the parasitic without the use of substituted impedances, and the computer program are described. Typical small and large signal results obtained on Ge and Si IMPATT devices are presented.     

The charge-density method of solving electrostatic field: Program and error analysis

The Charge-Density method of solving electrostatic field has many advantages over the finite difference or finite element method, but its accuracy and fitness are still in question. By direct evaluating electrical potentials, the errors along surface of the electrode are plotted, which are the maximum errors for an electrostatic problem. It is shown that higher accuracy will be reached if more sub-regions are chosen at where the charge density is high or at the region near the area where the field is to be calculated. This will be helpful to understand and use the method efficiently. It is more convenient and accurate to use the chargedensity method when we deal with the calculation of an electrostatic system having a great difference in size between electrodes (such as the point emitter diode). Using the information of error on the surface of electrode, we can estimate the potential errors in each calculation or rearrange the sub-regions to improve the accuracy of the next calculation. A program is set up. The difference between the calculated data and that of E. Harting and F. H. Read (1976) is less than 1%.     

A Procedure for Decomposing the Myoelectric Signal Into Its Constituent Action Potentials?Part I: Technique, Theory, and Implementation

A technique has been developed which enables the decomposition (separation) of a myoelectric signal into its constituent motor unit action potential trains. It consists of a multichannel (via one electrode) myoelectric signal recording procedure, a data compression algorithm, a digital filtering algorithm, and a hybrid visual-computer decomposition scheme. The algorithms have been implemented on a PDP 11/34 computer. Of the four major segments of the technique, the decomposition scheme is by far the most involved. The decomposition algorithm uses a-sophisticated template matching routine and details of the firing statistics of the motor units to identify motor unit action potentials in the myoelectric signal, even when they are super-imposed with other motor unit action potentials. In general, the algorithms of the decomposition scheme do not run automatically. They require input from the human operator to maintain reliability and accuracy during a decomposition.     

一种适用于教学实验的OFDM系统的设计与实现

本文介绍了正交频分复用（OFDM）的基本原理,提出了一种适用于教学实验的OFDM系统方案,并实现了实验系统的软硬件。本系统的发送端和信道模拟在计算机上通过软件完成,然后将数据发送给实验硬件,接收功能则在基于DSP的实验硬件上完成,最终输出解调后的信号。实验者可设置发送端以及信道中的各种参数并观察其对整个系统性能的影响。该实验系统不但有助于学生更好地掌握OFDM技术,而且可以拓展为开发平台供进一步研究和开发。     

基于神经网络的电机智能检测系统

利用神经网络技术建立电机的检测模型，由计算机构筑电机智能检测系统，与电机控制和执行机构相结合，对电动机进行控制，利用各种新型的传感技术，实现电动机各种参数的数据采集与分析处理，从而对电动机的性能进行判断。     

Semiconductor parameters extraction using cathodoluminescence inthe scanning electron microscope

Five semiconductor-related parameters have been extracted simultaneously from experimental cathodoluminescence output data collected as a function of electron-beam energy. The extraction technique is based on a recently proposed three-dimensional computer model of cathodoluminescence. It also uses a curve fitting technique based on the minimization of an area error criterion. Computational results show that a unique and unambiguous set of parameter values can be obtained for each set of the experimental data points using the algorithm suggested