IEEE Pacific Rim Conference on Communications, Computers, and Signal Processing. Proceedings

17-19 May 1995

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Displaying Results 1 - 25 of 151
  • Formal modelling and analysis of computerized control in rail transport: a case study

    Publication Year: 1995, Page(s):610 - 613
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (434 KB)

    The formal modelling and analysis of computerized real-time control systems is emerging as a new and important topic of research in both the control systems and software engineering literature. Formal modelling helps makes precise the specifications of what must be done which in turn makes possible the formal analysis required to establish guarantees about certain aspects of system behavior. This ... View full abstract»

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  • CDMA multi-user interference cancellation with reference symbol aided estimation of channel parameters

    Publication Year: 1995, Page(s):429 - 432
    Cited by:  Papers (4)  |  Patents (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (464 KB)

    A novel multi-stage successive interference cancellation scheme is proposed which operates on the reverse CDMA link using BPSK modulation, coherent detection and reference symbols to obtain channel estimates. Single user analysis shows that the performance of the coherent detector with reference symbols is approximately 1.5 dB worse than that of an ideal coherent receiver on Rayleigh flat fading a... View full abstract»

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  • Integer dilation and contraction for quadtrees and octrees

    Publication Year: 1995, Page(s):426 - 428
    Cited by:  Papers (6)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (216 KB)

    Integer dilation and contraction are functions used in conjunction with quadtree and octree mapping systems. Dilation is the process of inserting a number of zeros before each bit in a word and contraction is the process of removing those zeros. Present methods of dilation and contraction involve lookup tables which consume considerable amounts of memory for mappings of large or high resolution di... View full abstract»

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  • Ocean-depth measurement: a frequency-domain approach

    Publication Year: 1995, Page(s):423 - 425
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (172 KB)

    A new formulation for ocean-depth measurement using the frequency-domain approach is proposed. This technique uses a high-resolution eigen subspace method to estimate the ocean-depth from backscattered noisy data. The problem has been addressed for real attenuation coefficients by utilizing a eigenstructure decomposition procedure on a Toeplitz matrix structure View full abstract»

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  • An analysis of DOA estimation method under a dispersive signal model

    Publication Year: 1995, Page(s):351 - 354
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (232 KB)

    In direction of arrival estimation, the signal sources are usually assumed to be point sources. If the signal sources are dispersive, however, direction of arrival estimation methods based on the point source assumption may result in poor performance. In this paper, we consider direction of arrival estimation under a parametric dispersive signal modeling. An estimation method based on the well-kno... View full abstract»

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  • Moire patterns in disparity measurement

    Publication Year: 1995, Page(s):420 - 422
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (240 KB)

    Calculating disparity between left and right images is an essential operation in stereo vision. The technique proposed in this paper explores the Moire phenomenon for determining the disparity between regions in two images. Moire patterns are obtained when two similar images are superimposed one on another. Any two images that differ in orientation would still match at the fixed point, according t... View full abstract»

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  • Dealing with the useful window related with the far field pattern

    Publication Year: 1995, Page(s):347 - 350
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (188 KB)

    With a convenient representation, the radiation pattern of a spatial distribution of radiating sources is always related with that distribution by a window in the inverse spatial Fourier transform of the distribution. This fact is used to change the distribution of sources without disturbing the radiation pattern. On the other hand, the error, in the mean square sense, made by source elimination i... View full abstract»

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  • The spatial U-order and some of its mathematical characteristics

    Publication Year: 1995, Page(s):416 - 419
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (420 KB)

    A new spatial order, called the U-order, is analyzed; the order is closely related to the Z-order or Morton-order which induces linear quadtrees. A number of mathematical relationships and algorithms are presented, in particular the functional relationships between the Euclidean coordinates of a pixel in the U-domain and its location code, the translation of a pixel by an arbitrary vector, finding... View full abstract»

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  • Time-cost analysis of fault-tolerant parallel programs with timing constraints

    Publication Year: 1995, Page(s):343 - 346
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (312 KB)

    We present a model for representing fault-tolerant parallel programs an a real-time shared memory system. We use time-cost modelling techniques to derive the condition for which a program's deadline can be met. We apply a fault-tolerant mechanism based on imprecise computation technique and provide an algorithm for deciding when to sacrifice the result accuracy in order to meet the timing constrai... View full abstract»

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  • On the use of discrete Laplacian operators in image restoration

    Publication Year: 1995, Page(s):411 - 415
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (440 KB)

    The role of the stabilizing functional in the Tikhonov (1964) regularization is as crucial as that of the regularization parameter. However, a 3×3 discrete differential operator is usually used to generate the stabilizing functional. It is demonstrated that the restoration quality is practically independent of the size of the generating stabilizing operator. As a result, the choice of small ... View full abstract»

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  • Coherence multiplexing/subcarrier FDM transmission system with bus configuration

    Publication Year: 1995, Page(s):550 - 553
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (308 KB)

    We propose fiber optic subcarrier transmission system using coherence multiplexing techniques with bus configuration for mobile communication. The proposed system can carry N optical channels, each supporting M subcarrier channels, thus providing NM channels. Therefore it is possible to reduce the number of intermodulation distortion (IMD) and the effects of the interference noise. Thus, the perfo... View full abstract»

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  • Compression of bathymetric data using wavelets

    Publication Year: 1995, Page(s):635 - 638
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (232 KB)

    The compression of bathymetric data using three different types of wavelet transforms as well as the discrete cosine transform (DCT) is considered. The various compression schemes are then compared with respect to the compression ratios achieved, computational complexity, and accuracy of reproduction. The results indicate that the wavelet transforms can yield higher compression ratios than the DCT... View full abstract»

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  • An analytical model for multi-group slotted ALOHA with capture

    Publication Year: 1995, Page(s):534 - 537
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (304 KB)

    The performance of multi-group slotted ALOHA with capture improves dramatically over single-group slotted ALOHA. An analytical model is proposed to evaluate the throughput, delay, and stability of a multi-group slotted ALOHA system with capture. The model approximates a K-group system as K interactive slotted ALOHA systems with independent Bernoulli jamming sources. An iterative procedure is used ... View full abstract»

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  • Fast graph partitioning algorithms

    Publication Year: 1995, Page(s):337 - 342
    Cited by:  Papers (5)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (408 KB)

    The following k-way graph partitioning (GP) problem is considered: given an undirected weighted graph G(V,E), partition the nodes of G into k parts of almost equal size such that the partition-cost (sum of the weights on edges with nodes in different parts) is minimized. Two simple and fast algorithms are proposed, namely, direct algorithm AUCTION and iterative algorithm GREEDYCYCLE. In algorithm ... View full abstract»

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  • Measurement and analysis of defocused point spread functions and optical transfer functions of a microscope

    Publication Year: 1995, Page(s):407 - 410
    Cited by:  Patents (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (368 KB)

    The defocused point spread functions and optical transfer functions of a microscope were measured and analyzed. The main purpose of the analysis was to verify the accuracy of analytical approximations of these functions, which were presented but not extensively studied in the literature. The measured results were compared with those calculated by Castleman's (1979) theoretical approximation, in th... View full abstract»

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  • Reconstruction of human voice using parallel structure transfer function and its estimation error

    Publication Year: 1995, Page(s):575 - 580
    Cited by:  Patents (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (460 KB)

    In this paper, we present a new method to reconstruct the speech signal using the parallel structure transfer function. In the case of a speech signal, the characteristics of the glottis wave and the resonance in vocal and nasal tracts are convoluted. Specifically, because the glottis waves are not the ones generated by the resonance, the waves have a non-linear characteristic. In our method, the ... View full abstract»

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  • Composite algorithms for adaptive IIR filtering using lattice realization

    Publication Year: 1995, Page(s):189 - 192
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (376 KB)

    Adaptive IIR algorithms are implemented based on lattice realizations allowing the adaptive filter poles to be monitored in real-time. New simplified recursive-in-order equations are presented relating the parameters of the direct-form realization to the ones of the two-multiplier IIR lattice realization. Those equations yield a general method to implement any adaptive IIR algorithm including the ... View full abstract»

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  • Hardware techniques for testing software components

    Publication Year: 1995, Page(s):128 - 130
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (204 KB)

    Object-oriented software engineering concerns itself with system construction using standardized components in a manner analogous to the construction of hardware systems. These components are contained in class libraries. A number of class libraries have been developed and are commercially available. Class libraries should be well defined and documented, portable and carefully tested. However, the... View full abstract»

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  • 3-D modeling of current spreading and carrier diffusion in semiconductor DH laser with stripe discontinuities

    Publication Year: 1995, Page(s):546 - 549
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (376 KB)

    This paper presents a three-dimensional (3-D) numerical modeling of semiconductor double heterostructure (DH) single- and double-stripe lasers with stripe discontinuities along the longitudinal direction. Asymmetric step discontinuities in the biasing stripes or gradually varying stripe dimensions can contribute to eliminate undesirable two-lobed far-field pattern in strongly-coupled stripe arrays... View full abstract»

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  • Multi-agent programming system on a workstation network

    Publication Year: 1995, Page(s):315 - 318
    Cited by:  Patents (4)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (276 KB)

    We propose a multi-agent programming system based on Prolog. In this system, a new concept called “field” is introduced. A field provides a knowledge base which is written in a form of Prolog program. An agent can “enter” into or “exit” from a field. Multiple agents can enter into one field, and the knowledge base of the field is shared by the agents. Therefore,... View full abstract»

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  • Noise filtering and enhancement of seabed topography for airborne laser bathymetry

    Publication Year: 1995, Page(s):631 - 634
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (276 KB)

    A technique for noise filtering and enhancement of seabed topography of coastal waters is presented. The characteristics of the noise with which the bathymetric signals are contaminated are studied. A simple, yet efficient, data segmentation and interpolation method for regularizing irregularly spaced data is developed. Then a 2D noise filtering algorithm based on the use of local statistics of de... View full abstract»

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  • Performance prediction of GSM digital cellular speech and image transmission

    Publication Year: 1995, Page(s):26 - 31
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (516 KB)

    The Group Special Mobile (GSM) digital cellular system provides the European countries with a standard land mobile radio (LMR) architecture. This paper illustrates how voice coded (vocoded) speech and uncompressed image transmission can be expected to degrade as a function of signal to noise ratio (SNR) and carrier to interference ratio (CIR) for a cochannel GSM interferer. Performance is predicte... View full abstract»

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  • Split FIFO phase synchronization for high speed interconnect

    Publication Year: 1995, Page(s):66 - 69
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (344 KB)

    This paper describes a simple method of phase synchronization for high speed communication in a large distributed network such as a parallel processor interconnect. Reducing phase delta with matched clock distribution in a distributed system is not always practical. A split FIFO phase synchronizer provides reliable data transfer at fast clock speeds and high bandwidth. A digital delay locked loop,... View full abstract»

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  • A simulation model for performance analysis of routing algorithms in concurrent systems under realistic load

    Publication Year: 1995, Page(s):525 - 529
    Cited by:  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (468 KB)

    The communication behavior of concurrent programs has great influence on the efficiency of a routing algorithm. Selection of a good routing algorithm for a particular application or network constraint requires performance analysis under realistic load. We have proposed a simulator model for the study and analysis of the various routing policies in concurrent systems. In this paper a timed Petri ne... View full abstract»

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  • Estimating the cost of GraphLog queries

    Publication Year: 1995, Page(s):145 - 148
    Cited by:  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (372 KB)

    The efficiency of query execution in a logic program depends very strongly on the order in which subgoals are evaluated. If a suitable evaluation order is chosen, the number of alternatives to be explored is reduced, and the overall efficiency may be improved. We present a cost model that estimates the number of solutions associated with GraphLog queries, based on a probabilistic approach. The inc... View full abstract»

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