Showing papers in "Iete Journal of Research in 1989"
TL;DR: The notion of Markovianity on a plane, statistical inference in GMRF models, and their applications in several image related problems such as, image synthesis, texture classification, segmentation and image restoration are discussed.
Abstract: This paper is concerned with a systematic exposition of the usefulness of two-dimensional (2-D) discrete Gaussian Markov random field (GMRF) models for image processing applications. Specifically, we discuss the following topics; notion of Markovianity on a plane, statistical inference in GMRF models, and their applications in several image related problems such as, image synthesis, texture classification, segmentation and image restoration.
146 citations
TL;DR: In this paper, the authors present technical details of the antenna arrays, the declination scanning system and the tracking system in hour angle for a large decameter wave radio telescope at Gauribidanur, Karnataka, India.
Abstract: The Raman Research Institute and the Indian Institute of Asrtophysics in a joint collaboration program constructed a large decameter wave radio telescope at Gauribidanur, Karnataka, India (Latitude: 13°36' 12” and Longitude 77° 26' 07”) which is in operation for several years now. This Decameter-wave Radio-Telescope, operating at 34.5 MHz, consists of 1,000 broad band dipoles arranged in the form of the letter “T” In this paper, we present technical details of the antenna arrays, the declination scanning system and the tracking system in hour angle.
8 citations
TL;DR: Recursive relations for the number of non-trivial summations and multiplications required for the various fast Hartley transform algorithms are derived and show that Bracewell's and Meckelburg and Lipka's decimation-in-frequency algorithms are equally fast and slower than the split radix algorithm.
Abstract: Recursive relations for the number of non-trivial summations and multiplications required for the various fast Hartley transform algorithms are derived. These relations show that Bracewell's decimation-in-time [3] and Meckelburg and Lipka's decimation-in-frequency [5] algorithms are equally fast and slower than the split radix algorithm due to Pei and Wu[1] and Sorensen et al [2].
6 citations
TL;DR: In this article, the authors proposed a modified forward-backward linear prediction (MFBLP) method to estimate the number of sinusoids corrupted by white noise, which is based on the information theoretic criteria for model selection.
Abstract: The modified forward-backward linear prediction (MFBLP) method of estimating the frequencies of sinusoids corrupted by white noise, proposed recently by Tufts and Kumaresan [1], has been receiving much attention. In the MFBLP method, there is an implicit assumption that the number of sinusoids is either known or it can be estimated using some criteria.In this paper, we first suggest sonic improvements to the MFBLP method and then propose a novel method for detection of the number of sinusoids. The improvements are obtained by using a cleaned desired response vector and a better lower rank approximate of the data matrix in the solution for the predictor coefficients. The detection criterion is based on the application of the information theoretic criteria for model selection, introduced by Akaike (AIC) and by Schwartz and Rissanen (MDL). The method is novel in that the computations involved over and above those needed for singular value decomposition (which is an essential step in the MFBLP method) are mar...
5 citations
TL;DR: The minimal cutsets are obtained by the technique of merging nodes and an algorithm has been given for easy evaluation of the unreliability expression.
Abstract: This paper describes a method for finding a reliability expression of a general network through cutset approach. There are many methods to enumerate cutsets of directed/undirected graphs. All those involve mathematics. In first part of this paper, the minimal cutsets are obtained by the technique of merging nodes. The method suggested in this paper needs no knowledge of mathematics in enumerating the minimal cutsets. In second part of this paper, an algorithm has been given for easy evaluation of the unreliability expression. The complement of unreliability expression directly gives the reliability expression.
4 citations
TL;DR: In this paper, a generalized synthesis procedure of higher order OTA-C networks is presented, where the general circuit configuration can realize LP, HP and AP characteristics after inserting capacitors at the appropriate points.
Abstract: A generalized synthesis procedure of higher order OTA-C networks is presented. The general circuit configuration proposed can realize LP, HP and AP characteristics after inserting capacitors at the appropriate points. From the admittance matrix derived, the transfer functions are also obtained in terms of the capacitances of the network and transconductances of OTAs.
4 citations
TL;DR: This paper presents scalar implementations of multichannel fast Recursive Least-Squares algorithms in transversal filter form (so-called FTF algorithms) that are amenable to VLSI implementation on arrays of parallel processors naturally follow from this approach.
Abstract: In this paper, we present scalar implementations of multichannel fast Recursive Least-Squares algorithms in transversal filter form (so-called FTF algorithms). The point is that by processing the different channels sequentially, ie one at a time, the processing of any channel reduces to that of the single-channel algorithm. This sequential processing decomposes the multichannel algorithm into a set of intertwined single-channel algorithms. Geometrically, this corresponds to a modified Gram-Schmidt orthogonalization of multichannel error vectors. Algebraically, this technique corresponds to matrix triangularization of multichannel error covarianre matrices and converts matrix operations into a regular set of scalar operations.Algorithm structures that are amenable to VLSI implementation on arrays of parallel processors naturally follow from our approach. Numerically, the resulting algorithm benefits from the advantages of triangularization techniques in block-processing, which are a well-known part of Kalm...
4 citations
TL;DR: In this article, the authors focus on modelling FMSs using stochastic models such as Markov and semi-Markov processes, queueing networks, and stochastically Petri nets.
Abstract: Performance modelling and evaluation play a vital role in the design and operation of flexible manufacturing systems (FMSs). This paper focuses on modelling FMSs using stochastic models such as Markov and semi-Markov processes, queueing networks, and stochastic Petri nets. The role of these modelling tools is brought out by constructing performance models of simple, illustrative FMS examples. Recent research contributions in this important area and a comparison of the three modelling techniques are presented.
3 citations
TL;DR: The Universal Hybrid-pi model was found to predict more realistic and practically verifiable performance parameters such as the reverse transmission parameter and the output impedance R0 of CB configuration, by examining the data sheets of CE h parameters.
Abstract: Certain inconsistencies in the results worked out by Millman and Halkias in his book “Integrated Electronics” impelled the first author to introduce the Universal Hybrid-pi model which incorporates the current generator β0 ib in place ofgm vπ at midfrequencies. The physical reasoning for doing so was the simple argument that why should not the total base nodal current ib be the useful transistor instead ofiπ. The Universal Hybrid-pi model was found to predict more realistic and practically verifiable performance parameters such as the reverse transmission parameter and the output impedance R0 of CB configuration. By examining the data sheets of CE h parameters also, the trend in support of Universal Hybrid-pi model seems to be found. Some more accurate and sensitive measurements are in order before the Universal Hybrid-pi model can conclusively be validated.
3 citations
TL;DR: The algorithm is simple, geometrically intuitive and strongly uses distance functions for its implementation and is applied to an articulated, two link planar arm and shown to generate good paths using only short computing times.
Abstract: This paper presents a heuristic method of collision avoidance for robots with two degrees of freedom. The algorithm is simple, geometrically intuitive and strongly uses distance functions for its implementation. The method is applied to an articulated, two link planar arm and shown to generate good paths using only short computing times.
3 citations
TL;DR: In this paper, the vertical symmetry of radio refractivity of the troposphere has been suggested to explain the availability of radio signals at long distances from the transmitters, at frequencies UHF and above.
Abstract: To explain the availability of radio signals at long distances from the transmitters, at frequencies UHF and above, the vertical symmetry, instead of horizontal symmetry, of radio refractivity of the troposphere has been suggested. Formation of thermal cells and their effect on radiowave propagation through troposphere has been numerically treated. It has been inferred that the instantaneous changes in the meteorological conditions in the thermal cell provide greater understanding of the tropospheric propagation characteristics.
TL;DR: The perturbation theorem can be easily applied for sensitivity analysis of any SVD based algorithm that can be formulated in terms of the SVD truncated matrices or/and the SDF truncated pseudoinverses.
Abstract: We present a perturbation theorem on the perturbations in the SVD truncated matrices and the SVD truncated pseudoinverses. The theorem can be easily applied for sensitivity analysis of any SVD based algorithm that can be formulated in terms of the SVD truncated matrices or/and the SVD truncated pseudoinverses. The theorem is applied to a SVD based polynomial method and an SVD based matrix pencil method for estimating parameters of exponential signals in noise.
TL;DR: A regular grammar approach for the chance collection of partial fingerprint pattern classification is described, which involves the division of a fingerprint pattern into quadrants and the transformation of each quadrant into sampling matrices indicating dominant direction of the ridges for each subpicture.
Abstract: A regular grammar approach for the chance collection of partial fingerprint pattern classification is described in this paper. The procedure involves the division of a fingerprint pattern into quadrants and the transformation of each quadrant into sampling matrices indicating dominant direction of the ridges for each subpicture. These sampling matrices are used for feature extraction and a class of regular grammar is then used to describe each quadrant of the partial fingerprint pattern. The classification is then accomplished by means of finite automata for each quadrant.
TL;DR: In this article, a recursive implementation of first order KLT by reconfiguring a lattice filter has been demonstrated, and the usefulness of a deflation scheme for estimating eigen vectors has been shown.
Abstract: Transform Domain Adaptive Signal Processing scheme using a combination of transforms and correlation cancellers implemented with plane rotations have been described. A recursive implementation of first order KLT by reconfiguring a lattice filter has been demonstrated. The usefulness of a deflation scheme for estimating eigen vectors has been shown. A study has been made of the acquisition behaviour of the rotation angle in Jacobi and Givens operations. The convergence behaviour of transforms such as DHT, DCT and low order KLT together with lattice stages and Jacobi/Givens plane rotation decorrelator has been studied. The study shows that for time series data best performance is obtained if transforms are preceded by lattice filter and followed by Jacobi stages.
TL;DR: In this paper, a simulation package has been developed for the design and implementation of the Flexible Manufacturing Systems (FMSs), which can take up any type of jobs irrespective of their process plans and of the number of operations.
Abstract: A simulation package has been developed for the design and implementation of the Flexible Manufacturing Systems. The system was made to suit the actual implementation of it in practical FMSs.The system is designed to take up any type of jobs irrespective of their process plans and of the number of operations. In the system developed, the following have been taken into consideration: the precedences and the alternate process plans, the availability of tools, jigs fixtures and NC programs and the manual involvement in the system.The simulation package has been developed to (i) get the system configuration, (ii) get the part definitions, (iii) do the static scheduling, (iv) create the dynamic schedule, (v) graphically execute it, and (vi) evaluate the system utilization. Of these the static scheduling is the heart of the simulation package and this has been dealth with at length in this paper.The programs, developed in Quick Basic version 4.0., have been made in a modular structure to facilitate further enha...
TL;DR: It is shown that one can use a form of spatial smoothing on both the auto and cross covariance matrices to restore the rank of the associated generalized eigenvalue problem before estimating the signal parameters via rotational invariant techniques.
Abstract: In this paper, we suggest a pre-processing technique that allows the application of rotational invariance technique (ESPRIT) of Paulraj et al [1], for estimating the Directions-of-Arrival (DOA) in the presence of multipath propagation. Here, we show that one can use a form of spatial smoothing on both the auto and cross covariance matrices to restore the rank of the associated generalized eigenvalue problem before estimating the signal parameters via rotational invariant techniques. This technique shares the common disadvantage associated with the conventional spatial smoothing due to which the number of sources d (when all of them are fully correlated) is limited to (N—1)/2 where (N—1) is the number of doublets in the array. We also formulate here, a “forward-backward” averaging technique which can increase the coherent signal resolving capability of the array compared to forward smoothing alone.
TL;DR: Software implementation of several Reed-Solomon codecs over GF(25), GF(26) and GF(27) and their performances in presence of random errors have been reported and help the designer to gain an insight into the complexities involved in the design and implementation of the R-S codes.
Abstract: Along with a brief review, the generalised design philosophy of forward error correcting codecs using systematic primitive Reed-Solomon (R-S) codes over GF(2m) has been discussed. For decoding die R-S codes, the Berlekamp-Massey algorithm, the Chien search procedure and Forney's method of finding error magnitudes have been adopted. Software implementation of several Reed-Solomon codecs over GF(25), GF(26) and GF(27) and their performances in presence of random errors have been reported in this paper. The purpose of this paper is to help the designer to gain an insight into the complexities involved in the design and implementation of the R-S codes and to explore their features for required applications.
TL;DR: A new form of microwave FM discriminator using the technique of injection synchronization is described, needing only few off-the-shelve microwave components and having low distortion at the output.
Abstract: A new form of microwave FM discriminator using the technique of injection synchronization is described. Detailed theoretical and experimental results on its performance have been presented. The merits of the discriminator are: (i) tracking but with the snag of false locking, (ii) low distortion at the output, and (iii) needing only few off-the-shelve microwave components.
TL;DR: In this paper, the authors review some of the significant developments in the area of optical correlation filter design that were aimed at solving some of these problems, including low light throughput, lack of real-time spatial light modulators and sensitivity to misalignment.
Abstract: Optical Pattern Recognition got its start when Vander Lugt proposed the frequency plane correlator to implement the matched spatial filtering. Since that time, correlators have been the subject of much research. While matched filter is theoretically optimum when the input signal (or image) is an exact replica of the reference signal, its performance degrades severely in practical situations where the input image may differ from the original due to distortions such as rotations and scale changes. Additional problems facing conventional correlators include: low light throughputs, lack of real time spatial light modulators and sensitivity to misalignment. Here, we review some of the significant developments in the area of optical correlation filter design that were aimed at solving some of these problems.
TL;DR: In this paper, the authors present a state-of-the-art review of flexible automation and robotics in manufacturing and discuss the role of robotics in the context of flexible automata.
Abstract: This paper presents a state-of-art review of flexible automation and robotics in manufacturing. Stages of development of automation are presented and the role of robotics is discussed in the context of flexible automation. The review attempts to cover some general aspects related to the issue such as: basic concepts and trends in automation, flexible automation, industrial applications and role of robots in flexible automation followed by socio-economic impacts and management issues.
TL;DR: The simulation study of the uncoded variable-rate bipolar signalling with continuous rate adaptation over an infinite range shows that such a system can completely nullify the effect of fading.
Abstract: Ideas of feedback, adaptive transmission and coding have been combined to improve the performance of communication systems over the Rayleigh fading channel with slow and flat fading assumption. The coded variable-rate transmission systems employ the Fano and the modified Fano algorithms for decoding [1]. The simulation study of the uncoded variable-rate bipolar signalling with continuous rate adaptation over an infinite range shows that such a system can completely nullify the effect of fading. A four-rate uncoded systems is only 0.5 dB inferior and the two-rate coded system with either Modified-Fano or Fano decoding is only 0.4 dB inferior to the ideal infinite rate systems at a BER of 10-5. The increase in the average rate of transmission of both coded and uncoded variable rate systems is found to degrade the error performance. For the coded systems both the Fano and Modified-Fano algorithms provide the similar error performance but the Modified-Fano decoder provides the throughput advantage over the Fa...
TL;DR: In this article, an improved design technique based on previously unemployed theory has been developed and used in the design of linear array, and the experimental results demonstrate the effectiveness of the technique.
Abstract: Usually, the linear slotted waveguide arrays employing longitudinally displaced slots on broad wall exhibit higher sidelobes, in particular Gruenberg lobes at ±45° as compared to theoretically designed value. The occurrence of such higher lobes has been investigated theoretically as well as experimentally. The theory has been extended to the suppression of these lobes. The improved design technique based on previously unemployed theory has been developed and used in the design of linear array. The experimental results demonstrate the effectiveness of the technique. The present technique is a significant improvement over the existing ones.
TL;DR: In this paper, the effect of convolutional coding in Direct Sequence Spread Spectrum (DSSS) and Frequency-Hopping Spread Spectrum(FHSS) in the presence of the Gaussian, Pulse and Partial band jamming has been made and compared with the bit error performance of the uncoded scheme under the same total bandwidth constraint.
Abstract: In this paper a study of the effect of convolutional coding in Direct Sequence Spread Spectrum (DSSS) and Frequency-Hopping Spread Spectrum (FHSS) in the presence of the Gaussian, Pulse and Partial band jamming has been made and compared with the bit error performance of the uncoded scheme under the same total bandwidth constraint. This study has been made with respect to the variation in thermal noise density and jamming-to-signal power ratio. Different values of the constraint length and the processing gain are considered. The Viterbi decoding scheme with soft decision has been used for the convolutional decoding. A table look-up method has been employed to determine the signal-to-noise power ratio. The possible burst errors present here are randomised through an interleaving-deinterleaving operation.The coding of the DSSS is found to improve the bit error performance in-spite-of the reduced processing gain over a range of signal-to-thermal noise density ratio and jamming-to-signal power ratio. Thus thi...
TL;DR: In this article, it is shown that the wave filter representation is very useful in analog simulation of semiconductor devices and propagating structures, and applications of such matrices for iterative generation of trigonometric functions, computation of transforms and phase locked loops have been discussed.
Abstract: Wave networks realised with switched capacitors can be used to represent transmission and scattering matrices associated with propagating structures. Applications of such matrices for iterative generation of trigonometric functions, computation of transforms and phase locked loops have been discussed. It is shown that the wave filter representation is very useful in analog simulation of semiconductor devices and propagating structures.
TL;DR: In this paper, a hybrid of the periodogram approach and the maximum entropy extension of signals outside the observation interval is proposed for radar target detection, which is shown to possess the high resolution advantages of the MEM method while closely retaining the advantages of periodogram method.
Abstract: This paper suggests a new method of high resolution spectral estimation for radar target detection. This method is a hybrid of the periodogram approach and the maximum entropy extension of signals outside the observation interval. This method is shown to possess the high resolution advantages of the MEM method while closely retaining the advantages of the periodogram method. This is shown to be advantageous, particularly when applied with, data windowing. Some simulation results supporting the performance advantages are also included.
TL;DR: It is shown that continuous parameter inner products on the reproducing kernel Hilbert space can be used to calculate detection indices for either distributed sensor or discrete optimum array processors.
Abstract: Characterization of second-order inhomogeneous random fields (four dimensional generalization of nonstationary stochastic processes) is of fundamental importance to the design of optimum array processors for reception of multipath signals in anisotropic and nonstationary noise fields. We review and establish interrelations between four second-order characterizations of inhomogeneous random fields. These are covariance functions, 2n-dimensional spectral density functions, Wigner distributions and complex ambiguity functions. We show that continuous parameter inner products on the reproducing kernel Hilbert space can be used to calculate detection indices for either distributed sensor or discrete optimum array processors. Discrete array processor is a special case of the continuous field formulation. Expressions for detection indices are derived in terms of Wigner distributions of signals and inverse kernels. Use of Wigner distribution in array processing is illustrated by specific examples.
TL;DR: This paper discusses a hardware implementation of Char's spanning tree enumeration algorithm using high speed digital integrated circuits that takes care of all the advantages offered by the Char's algorithm.
Abstract: Several algorithm have been proposed to enumerate all the spanning trees of a graph. This paper discusses a hardware implementation of Char's spanning tree enumeration algorithm using high speed digital integrated circuits. The implementation takes care of all the advantages offered by the Char's algorithm. Each node and its adjacent vertices are represented as a programmable digital circuitry and is modelled as a Mealy machine. A controller for the nodes gives out a signal when a tree is generated. This controller is connected to a microprocessor system in handshaking mode. This also controls the to and from communication between the digital circuitry and the microprocessor system.
TL;DR: In this article, important reservations regarding the validity of two recently published circuits have been brought out. Corrected circuits are given in place of earlier ones, and they are shown to be correct.
Abstract: Important reservations regarding the validity of two recently published circuits have been brought out. Corrected circuits are given in place of earlier ones.
TL;DR: This paper presents some mathematical algorithms developed by the authors for image analysis, understanding and computer vision applications and are found to be computationally attractive in comparison with the conventional algorithms.
Abstract: All imaging systems give images of imperfect quality because of degradations caused by various reasons and needs to be restored for computer processing. Compression of image data by using different mathematical techniques without loss of significant information is another necessity for image analysis, understanding and computer vision applications. This paper presents some mathematical algorithms developed by the authors for the above mentioned two objectives, their performances experimentally analysed and are found to be computationally attractive in comparison with the conventional algorithms.
TL;DR: The stepper motor control of solar energy collectors using Intel 8085 microprocessor selects one of the five modes (0, 1, 2, 3, 4,) of operation and displays the data.
Abstract: This paper describes the stepper motor control of solar energy collectors using Intel 8085 microprocessor. The software selects one of the five modes (0, 1, 2, 3, 4,) of operation and displays the data. The software also includes the positioning of collectors through the stepper motor, data acquisition and processing etc. The system program occupies about 1600 bytes with 25 subroutines.