Polarity Correlator for Conduction Velocity Measurement

Techniques for the estimation of skeletal muscle fiber conduction velocity are of considerable interest. These techniques use, in general, some form of cross correlation or zero-crossing analysis. Cross correlation is a straightforward method of conduction velocity estimation, however, it is difficult to realize low-cost real-time processors. Polarity correlation offers a method which preserves the advantages of cross correlation and satisfies the speed-cost constraint. This paper describes the algorithm for implementation of a polarity cofrelator instrument using a microprocessor. The instrument is tested with deterministic and stochastic signals and used to estimate the conduction velocity of biceps brachii fibers of ten normal subjects. The performance of the instrument is compared to the zero-crossing technique described by Lynn.     

Direct On-Line Estimation of Muscle Fiber Conduction Velocity by Surface Electromyography

A new approach to the measurement of muscle fiber conduction velocity by surface electromyography (EMG) is developed, based upon a triple surface-electrode configuration. Unlike previously reported methods, it does not require the Fourier transformation of raw EMG data, and can be implemented on-line on a simple digital computer. Although programmed here on a PDP-11 machine, the algorithms developed are equally suited to a 16-bit microprocessor, without any need for hardware multiplication or floating-point facilities. Accurate conduction velocity estimates may be obtained every few seconds.     

A Note on the Noninvasive Estimation of Muscle Fiber Conduction Velocity

Average muscle action potential conduction velocity values were obtained during isometric constant-force contractions by a cross-correlation technique. To minimize the bias introduced by nondelayed activity appearing on the two myoelectric derivations, the signals were doubly differentiated. This arrangement effectively reduced the nondelayed activity and increased the accuracy of the estimate.     

The Measurement of Muscle Fiber Conduction Velocity Using a Gradient Threshold Zero-Crossing Method

The conduction velocity of myoelectric potential along muscle fiber is known to be an index of the degree of muscular fatigue or muscular disease. When detecting the myoelectric potential by means of surface electrodes, the conduction velocity must be extracted from an apparently random wave of a myoelectric signal. In this paper, a method for determining conduction velocity is proposed based upon a zero-crossing time delay measurement with reference to the derivative of a myoelectric signal. The slope value of the input signal provides an effective criterion for rejecting undesired zero crossing caused by noise. This method needs no spectral analysis nor correlation calculation. Compared to another previously reported zero-cossing approach using digital filter preprocessing, it shows a more accurate and rapid estimation of velocity.     

A Microprocessor-Based System for On-Line Parameter Identification in Continuous Dynamical Systems

The paper proposes a microprocessor-based unit for online identification of the parameters in linear continuous lumped dynamical systems. The unit implements an algorithm which uses the so-called Poisson mement functionals (PMF) of input-output data from the actual process under identification.     

A Microprocessor-Based Scheme for Torque-Angle and Speed Measurement

This paper describes a new scheme for continuous monitoring of torque angle and speed of a 3-kVA laboratory synchronous machine. The proposed scheme does not require mounting of an optical disc or a magnetic pickup on the shaft of the machine. Use is made of a 400-Hz 32-pole tacho generator mounted on the machine shaft. Intel's 8085A microprocessor is employed for the measurement and calculations of torque angle and percentage slip. The testing and evaluation of the scheme, for various operating conditions, have been carried out in the laboratory.     

Frequency Parameters of the Myoelectric Signal as a Measure of Muscle Conduction Velocity

Dunrng a sustained muscle contraction, the spectrum of the myoelectric signal is known to undergo compression as a function of time. Previous investigators have shown that the frequency compression is related to the decreasing conduction velocity of the muscle fibers. It is proposed that the frequency compression may be tracked by obtaining a continuous estimate of a characteristic frequency of the spectrum, such as the mean and median, or the ratio of low-frequency components to high-frequency components of the spectrum. A theoretical analysis was performed to investigate the restrictions in estimating the three parameters, as well as their sensitivity to the conduction velocity. The ratio parameter was found to be most sensitive to conduction velocity, but was the least reliable of the three. The median frequency was the least sensitive to noise. Therefore, from a theoretical point of view, the median frequency is the preferred parameter. A technique is described which determines an unbiased consistent estimate of the median frequency. The technique may be readily implemented in analog hardware.     

On-Line Measurement of Sarcomere Length from Diffraction Patterns in Muscle

Two different systems designed to extract sarcomere length and several other variables from the light diffraction pattern in muscle are described. One system utilizes a linear photodiode array to detect the intensity distribution of diffracted light from muscle. This system provides computed outputs of sarcomere length, first order width, and time rate of sarcomere length change according to two different algorithms. Another system utlizes a Schottky photo-position sensor and provides sarcomere length and integrated first order intensity. The accuracy (within 1%) and resolution (2 nm) of both systems are comparable. The former system offers better convenience of operation while the latter offers wider bandwidth (2.5 kHz vs. 100 kHz).     

The Action of Dither in a Polarity Coincidence Correlator

An analysis has been made of how dither added to the input of a polarity coincidence correlator eliminates capture of a weak signal by an unwanted signal. For certain interfering environments the output signal-to-noise ratio of various correlators with three specific input dithers is analyzed. The correlators considered were a polarity coincidence correlator with: 1) no dither, 2) dither of random, amplitude uniformly distributed between the chosen plus-and-minus peak values, 3) sinusoidal dither, and 4) Gaussian dither. Each correlator was analyzed for the cases of Gaussian-noise, rectangular-wave, and sinusoidal interference and compared with the classical correlator. The choice of dither amplitude based upon the measured value of the noise power was studied. A uniformly distributed dither is shown to be slightly superior to sinusoidal dither, and both superior to Gaussian noise.     

A Microprocessor-Based Signal Processing System for Measurement of Vascular and Urethral Parameters

A relatively simple, flexible, and economical system is reported for processing biological signals which contain frequencies in the audio range. The microprocessor-based system has been tested successfully on ultrasonic scattered signals from blood and urine to provide diagnostic information in real-time. Measurements were obtained for average velocity, standard deviation of velocity (indicative of laminar and turbulent flow), relative flow rate, and relative cross-sectional area as functions of time. Comparison of these measures at various locations along a vessel, and at various times in the life of a patient, could help to detect stenotic zones and physiological changes associated with disease.     

Blood Velocity Measurement by Fiber Optic Laser Doppler Anemometry

Laser Doppler anemometry has been used to measure blood velocities by using a fine fiber optic probe both to deliver laser light into the blood and to receive reflected light from red blood cells at the tip of the probe. In vitro, with the probe aligned in the direction of flow, nonlinear calibration is possible to velocities of 15 cm/s in a 3 mm diameter vessel. When the probe is aligned against the flow, measurement of velocity is linear to at least 1 m/s. In vivo recordings of coronary and aortic blood velocity are produced by performing a fast Fourier transform (FET) in real time.     

微处理化医用光纤温度传感器研究

通过对该传感器温度检测原理和探头结构的分析,提出了光纤温敏探头的优化设计。应用微机化信号处理系统,使该传感器的温度分辨率及自动测控功能得到提高。     

环形光纤激光器自混合散斑自相关测速的研究

研究了一种基于强度自相关函数的光纤激光器自混合散斑速度测量方法.基于环形激光器光反馈理论,对自混合散斑信号进行自相关分析,推导出自混合散斑信号的自相关频率与表面粗糙物体运动速度之间的关系式.利用构建的环形掺铒光纤(EDF)激光器自混合散斑测速实验系统,对不同速度下的运动物体进行了实验测试,验证了自相关频率与物体运动速度...     

光缆在线监测系统

近几年来光缆在电力系统的应用越来越普及，电力系统的通信、自动化、维护等越来越依赖高可靠、高性能的光纤传输。但在实际应用中，由于受外力及光缆本身质量等因素影响，光缆很容易遭到破坏，从而影响光缆的传输质量。光缆在线监测系统能在光缆遭到破坏时迅速确定光缆的故障点，为光缆故障修复提供宝贵的时间。     

利用光纤延时实现光速测定的实验研究

介绍了光纤延时法实现光速测定的实验设计思想。利用光纤对溴化亚铜激光器输出的脉冲激光进于延时,通过常规测长手段测得光纤的几何长度并用示波器测出两相邻光脉冲间的时间间隔,即可获得光速。     

A Wide-Range Velocity Measurement Method for Motion Control

This paper discusses velocity measurement for motor drives with optical encoders. Although many methods on velocity measurement have been proposed, accurate measurement was not achieved in a high-speed range. This paper therefore proposes synchronous-measurement method (S method) that measures the velocity synchronized with the alteration of pulse numbers in each sampling period. Accurate velocity measurement is achieved in all speed ranges with this method. Furthermore, other velocity prediction methods are applicable in addition to the method. Simulation and experimental results verify the validity of the proposed method.      

A Microprocessor-Based System for Diagnosis of Cognitive Dysfunction

Memory impairment has been associated with a deficit in a functional component of attention termed "focused arousal." Short, aperiodic bursts of EEG activity in a narrow frequency band (36?44 Hz) centered at 40 Hz have been established as an indicator of this state of "focused arousal." A measure of this 40 Hz EEG activity could be very useful in the diagnosis of different types of cognitive dysfunction. Automated detection of the 40 Hz bursts is seriously hampered by the presence of high amplitude EMG signals from the scalp muscles and by the low amplitude of the 40 Hz EEG.     

On-Line Measurement of Airway Closing Volume

An on-line real-time program for measurement of airway closing volume has been developed, using the Lab-8/e (PDP-8/e) computer. The paper describes the procedure for measurement of airway closing volume and the program which was developed. The program in addition to measuring airway closing volume also measures the alveolar plateau volume, and the slopes of the alveolar plateau and the closing volume excursion. The program operates in conjunction with the Digital Equipment Corporation Pulmonary Test System.     

用于多点测试的全光纤速度干涉仪研究

基于时分复用（TDM）原理，提出了一种新型的用于多点速度测试的全光纤干涉系统，通过同一个冲击靶面的测速实验验证方案的可行性。该系统通过在原有全光纤速度干涉仪（AFVI）的探测端口引入光纤耦合器和延迟线，由于延时的存在，被测点干涉信号之间在时间上存在相同的延时，利用时分复用原理，能够实现以往需要多套速度干涉仪才能实现的对测试靶面的多点测试功能。通过对同一个测试自由面上的两点进行测试，得到了具有一定时延的相似干涉条纹，而且延迟的时间与光纤延迟线对应。实验验证了系统设计的正确性。