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Image processing techniques in the evaluation of droplet size distribution on sprayed leaves 喷雾剂叶片液滴大小分布评价中的图像处理技术
COMSIG 88@m_Southern African Conference on Communications and Signal Processing. Proceedings Pub Date : 1988-06-24 DOI: 10.1109/COMSIG.1988.49313
J. Beukman
{"title":"Image processing techniques in the evaluation of droplet size distribution on sprayed leaves","authors":"J. Beukman","doi":"10.1109/COMSIG.1988.49313","DOIUrl":"https://doi.org/10.1109/COMSIG.1988.49313","url":null,"abstract":"Four image segmentation techniques are assessed for use in determining the coverage of crop leaves by aerosol droplets after the application of chemicals for plant disease and pest control. The image analysis problem consists of effectively determining the number of droplets as well as the droplet size distribution on the sprayed leaves. Images of sprayed leaves are analyzed using a standard CCD camera mounted on a microscope. The entire image is digitized into 512 scan lines, each consisting of 512 pixels. Each pixel is assigned an integer value between 0 and 128 based on a brightness gray scale. Segmentation of the image is done using different thresholding techniques. The four methods compared are: the entropy method of T. Pun (1981); the moment preserving method of W.H. Tsai (1985); the maximum correlation method of A. Brink and G. De Jager (1987); and the minimum difference method. The usefulness of these methods are evaluated as to their accuracy in representing a bilevel image which can be used to determine the correct droplet areas. The maximum correlation method is recommended as the best of the four methods.<<ETX>>","PeriodicalId":339020,"journal":{"name":"COMSIG 88@m_Southern African Conference on Communications and Signal Processing. Proceedings","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1988-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126550869","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Optical matrix processing: a review 光学矩阵处理:综述
COMSIG 88@m_Southern African Conference on Communications and Signal Processing. Proceedings Pub Date : 1988-06-24 DOI: 10.1109/COMSIG.1988.49312
A. Scholtz
{"title":"Optical matrix processing: a review","authors":"A. Scholtz","doi":"10.1109/COMSIG.1988.49312","DOIUrl":"https://doi.org/10.1109/COMSIG.1988.49312","url":null,"abstract":"Matrix multiplication is well suited to optical techniques, since the size of the matrix has no direct influence on the speed with which the multiplication takes place. Although iterative techniques have been developed to solve systems of linear equations, to find the eigenvectors of matrices, and to perform other matrix manipulations, research has been hampered somewhat by a lack of fast two-dimensional spatial light modulators (SLMs). Advances in SLM technology are discussed, and different architectures for matrix processing are reported. Acoustic Bragg cells, liquid crystal devices, magnetooptic devices and silicon/PLZT crystal light modulators are briefly reviewed. Both Systolic and fully parallel optical vector-matrix multiplier configurations are described. Iterative optical processors and bimodal (analog-digital) optical computer accuracy are briefly considered.<<ETX>>","PeriodicalId":339020,"journal":{"name":"COMSIG 88@m_Southern African Conference on Communications and Signal Processing. Proceedings","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1988-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132245056","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 1
Diversity receiver for a serial HF modem 用于串行高频调制解调器的分集接收器
COMSIG 88@m_Southern African Conference on Communications and Signal Processing. Proceedings Pub Date : 1988-06-24 DOI: 10.1109/COMSIG.1988.49309
G. Muller, C. Pauw
{"title":"Diversity receiver for a serial HF modem","authors":"G. Muller, C. Pauw","doi":"10.1109/COMSIG.1988.49309","DOIUrl":"https://doi.org/10.1109/COMSIG.1988.49309","url":null,"abstract":"Two versions of a high-frequency (HF) diversity combination structure for use with an equalizer were investigated via a modem simulation. The two equalizers differ only in the way the weighting coefficients are generated. The output of each receiver is processed by an automatic gain control circuit. This signal is demodulated and fed into a decision-feedback equalizer. The outputs of the two equalizers are multiplied by a weighting factor before summation. A decision is made on this output. A separate error signal is generated for each equalizer by computing the difference between the final decision and the output of each equalizer. This forms an open looped system with no feedback. The equalizers are made adaptive by use of the stochastic gradient algorithm. Results for the structures are presented which differ from those obtained by P. Monsen (1981) for a troposcatter diversity system. The difference is due to the different channel characteristics for which his work was done.<<ETX>>","PeriodicalId":339020,"journal":{"name":"COMSIG 88@m_Southern African Conference on Communications and Signal Processing. Proceedings","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1988-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129896358","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Experimental comparison on several distance measures for speech processing applications 语音处理中几种距离度量的实验比较
COMSIG 88@m_Southern African Conference on Communications and Signal Processing. Proceedings Pub Date : 1988-06-24 DOI: 10.1109/COMSIG.1988.49293
L. Everson, W. Penzhorn
{"title":"Experimental comparison on several distance measures for speech processing applications","authors":"L. Everson, W. Penzhorn","doi":"10.1109/COMSIG.1988.49293","DOIUrl":"https://doi.org/10.1109/COMSIG.1988.49293","url":null,"abstract":"A description is given of a number of different distance measures between speech segments commonly used in the analysis and recognition of speech. The measures considered include spectral slope, correlation coefficients, log likelihood ration, cepstral, weighted ceptstral, and modified distance measures. These metrics were tested on either the linear predictive coding (LPC) or the frequency spectrum depending on the type of measurement. Work reported elsewhere, was also considered and experimentally verified. The tests were performed on speech in a noisy background in Gaussian and in high-frequency noise. All the measures were compared using the same speech database. These evaluations show that by eliminating unwanted information in speech segments, the distance metric can be made more robust in noisy environments. It was found that threshold 1/ sigma -weighted distance metric, where sigma is the standard deviation of a given cepstral coefficient, is generally the best speech distance metric to use in most types of noisy environments. Some of the other metrics work better in isolated areas, but do not show the same high general recognition result.<<ETX>>","PeriodicalId":339020,"journal":{"name":"COMSIG 88@m_Southern African Conference on Communications and Signal Processing. Proceedings","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1988-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124623511","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 5
Line-spectrum pairs-a review 线谱对——回顾
COMSIG 88@m_Southern African Conference on Communications and Signal Processing. Proceedings Pub Date : 1988-06-24 DOI: 10.1109/COMSIG.1988.49292
A.C. Smith, J.J.D. van Schalkwyk
{"title":"Line-spectrum pairs-a review","authors":"A.C. Smith, J.J.D. van Schalkwyk","doi":"10.1109/COMSIG.1988.49292","DOIUrl":"https://doi.org/10.1109/COMSIG.1988.49292","url":null,"abstract":"Line-spectrum pairs (LSPs) are presented as an alternative coding method for the vocal tract parameters of a linear predictive vocoder. These parameters provide improved control over the perceptual effect of quantization and coding. Two methods for determining the LSP-parameters are discussed, one making use of the fast Fourier transform, and the other of a ratio filter. A saving of 25% in coded bit rate is achieved when compared to 40-bit linear predictive coding.<<ETX>>","PeriodicalId":339020,"journal":{"name":"COMSIG 88@m_Southern African Conference on Communications and Signal Processing. Proceedings","volume":"103 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1988-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124575282","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 1
An algebraic approach to vector quantization 矢量量化的代数方法
COMSIG 88@m_Southern African Conference on Communications and Signal Processing. Proceedings Pub Date : 1988-06-24 DOI: 10.1109/COMSIG.1988.49320
W. Penzhorn
{"title":"An algebraic approach to vector quantization","authors":"W. Penzhorn","doi":"10.1109/COMSIG.1988.49320","DOIUrl":"https://doi.org/10.1109/COMSIG.1988.49320","url":null,"abstract":"The principle of vector quantization is briefly reviewed. It is pointed out that, for vector quantizers based on random codebooks, memory requirements and computational complexity grow exponentially with transmission rate and vector length. As a possible solution to this problem it is suggested to introduce sufficient algebraic structure into the codebook so as to facilitate a fast systematic and nonexhaustive search through a greatly reduced codebook. This goal is achieved by using n-dimensional lattices in real Euclidean space as quantizers. Two construction methods are introduced whereby dense lattices can be constructed from linear binary error-correcting codes. The densest lattices in up to 24 dimensions are presented and their performance as n-dimensional lattice quantizers is evaluated, based on the mean-square error criterion.<<ETX>>","PeriodicalId":339020,"journal":{"name":"COMSIG 88@m_Southern African Conference on Communications and Signal Processing. Proceedings","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1988-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116537109","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Digital measurement of FM transmitter quality 调频发射机质量的数字测量
COMSIG 88@m_Southern African Conference on Communications and Signal Processing. Proceedings Pub Date : 1988-06-24 DOI: 10.1109/COMSIG.1988.49316
H.L. Nattrass
{"title":"Digital measurement of FM transmitter quality","authors":"H.L. Nattrass","doi":"10.1109/COMSIG.1988.49316","DOIUrl":"https://doi.org/10.1109/COMSIG.1988.49316","url":null,"abstract":"A description is given of how a passive mixer can be used to replace a professional FM demodulator and distortion meter for FM transceiver measurements, when used with an automatic test system carrying a normal complement of signal generators and a timer/counter. The system measures two signal-to-noise and distortion (SINAD) power ratios for the FM transceiver by first causing the transmitter to be modulated by a standard 1000 Hz audio test tone and then downconverting the frequency of the transmitter carrier to a lower and more convenient value. A simple timer/counter is then used to measure a series of alternate periods between zero-crossing points of the frequency-converted transmitter output waveforms. These data points, taken over varying periods of time, are then converted into a series of equal interval data points by the author's proposed algorithms, and then the data are Fourier transformed into a frequency-domain representation of the FM transmitter modulating waveform. The required SINAD ratio and other useful data is then derived from this transformed data.<<ETX>>","PeriodicalId":339020,"journal":{"name":"COMSIG 88@m_Southern African Conference on Communications and Signal Processing. Proceedings","volume":"67 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1988-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124133026","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 3
Classification of ships using underwater radiated noise 用水下辐射噪声对船舶进行分类
COMSIG 88@m_Southern African Conference on Communications and Signal Processing. Proceedings Pub Date : 1988-06-24 DOI: 10.1109/COMSIG.1988.49315
J. G. Lourens
{"title":"Classification of ships using underwater radiated noise","authors":"J. G. Lourens","doi":"10.1109/COMSIG.1988.49315","DOIUrl":"https://doi.org/10.1109/COMSIG.1988.49315","url":null,"abstract":"Concentrating mainly on the signal processing and physical models behind the algorithms used to classify ships by their underwater-radiated noise, the physical model for cavitation is expanded to include the losses by acoustical radiation and the heat transfer from the vapor to the fluid. The resulting equation allows one to find the characteristics of cavitation through simulation. Five algorithms for estimating the propeller speed have been found. The performance of the three most promising ones are judged with respect to the ratio of the expected value to the variance of the estimator. A complete Bayes hypothesis test on second-order autoregressive power density spectrum poles are then described for determining the kind of propulsion a vessel uses. The nature of gearbox noise is described, and the cepstrum is proposed as an algorithm to detect this kind of noise.<<ETX>>","PeriodicalId":339020,"journal":{"name":"COMSIG 88@m_Southern African Conference on Communications and Signal Processing. Proceedings","volume":"62 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1988-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130360631","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 30
On the generation of a smooth Gaussian random variable to 5 standard deviations 对生成一个光滑的高斯随机变量达到5个标准差
COMSIG 88@m_Southern African Conference on Communications and Signal Processing. Proceedings Pub Date : 1988-06-24 DOI: 10.1109/COMSIG.1988.49303
G. Muller, C. Pauw
{"title":"On the generation of a smooth Gaussian random variable to 5 standard deviations","authors":"G. Muller, C. Pauw","doi":"10.1109/COMSIG.1988.49303","DOIUrl":"https://doi.org/10.1109/COMSIG.1988.49303","url":null,"abstract":"The generation of a Gaussian random variable for use in a low-error-rate communication simulation is discussed. The authors describe the requirements for a uniform probability density function (PDF) pseudorandom number generator used as well as different methods of obtaining a Gaussian random number for various applications. A lookup table method is presented that was designed for digital signal processing cases where it is difficult to generate a logarithmic function for analytic synthesis of the Gaussian random number. The techniques and approach used are applicable to any probability distribution (other than a Gaussian PDF) for which the inverse cumulative density function either cannot be evaluated analytically or is too computationally intensive.<<ETX>>","PeriodicalId":339020,"journal":{"name":"COMSIG 88@m_Southern African Conference on Communications and Signal Processing. Proceedings","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1988-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131452579","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 5
Application of fractal geometry to modelling nature 分形几何在自然建模中的应用
COMSIG 88@m_Southern African Conference on Communications and Signal Processing. Proceedings Pub Date : 1988-06-24 DOI: 10.1109/COMSIG.1988.49314
C. Willers
{"title":"Application of fractal geometry to modelling nature","authors":"C. Willers","doi":"10.1109/COMSIG.1988.49314","DOIUrl":"https://doi.org/10.1109/COMSIG.1988.49314","url":null,"abstract":"An overview and some experimental results are presented on the use of fractal geometry to describe geographical topography and for the synthesis of new topographic surfaces. An informal introduction to the basic concepts of fractal geometry is first given to illustrate the principles, followed by a more formal description. Since topography models are based on Brown surfaces, Brown functions, also called Weiner functions, are considered in some detail. A method is proposed for determining the fractal dimension of a surface on a regular square grid. Experiments with surfaces created by midpoint displacement and methods indicate that, for finite data sets, the relationship for the fractal dimension does not hold for H approaching unity or zero, where the parameter H defines the fractional degree of integration or differentiation of the Brown function. A 400 km/sup 2/ area near Pretoria is analyzed to find its surface fractal dimensions. An approach to synthetic generation of topographic surfaces is also described.<<ETX>>","PeriodicalId":339020,"journal":{"name":"COMSIG 88@m_Southern African Conference on Communications and Signal Processing. Proceedings","volume":"91 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1988-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133180011","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 1
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