A piece of information on the polarization effects on the effective dielectric constant εeff of a medium whose dielectric circular cylinders are randomly distributed is obtained by analyzing εeff for both E-wave and H-wave incidences. Our numerical analysis shows clearly the difference of εeff between E-wave and H-wave incidences and also shows the difference of εeff between our method and the Foldy's approximation.

44 matrix-based analysis of electromagnetic waves scattered by an infinite array of slots with polar-type anisotropic media are presented. In the analysis, the total fields are given as sum of the fields which exist even if the apertured plane are replaced by a ground plane and the fields scattered from the magnetic currents within the apertures. The scattered fields are expanded in terms of two-dimensional Floquet modes. Expression of each fields are obtained through eigenvalue problem for 44 coupled wave matrix. Unknown magnetic currents in the apertures are determined by applying Galerkin's method to the continuity condition about the magnetic fields in the apertures. Calculated results for isotropic cases are compared with other results for the complementary problem available in the literature using Babinet's principle. Further numerical calculations are performed in the case of gratings with polar-type anisotropic slab.

The thermal and/or the tensile strain distribution along the fiber make the Brillouin gain coefficient different in each point of the fiber. As a basic study of the Brillouin fiber optic gyro, its effect on lasing characteristics of a fiber Brillouin ring laser is formulated in the general form by using the statistical function and then calculation is done for typical values of the parameters. By suppressing the polarization-fluctuation-induced noise caused by the temperature, an example of the effect of the spatially distributed gain coefficient is experimentally demonstrated.

For the expansion of using the integral equation methods on wave-field analysis, a new method called "Source and Radiation Field Solution" is suggested. This solution uses a couple of integral equations. One of them is the traditional integral expression giving the scattered field from the wave source, another is newly proposed one which expresses the wave source from both of the source and the scattered field, by using the conjugate Green function expression. Therefore this method can derive both of the source and the scattered field at the same time by coupled two equations. For showing the effect of this method, we analyze scattering problems for dielectrics in this paper.

A mathematical model based on an optimization formulation is presented for perceptual clustering of dot patterns. The features in the present model are its nonlinearity enabling the model to reveal hysteresis phenomena and its scale invariance. The clustering of dots is given by the mutual linking of dots by virtual lines. Every dot is assumed to be perceived at locations displaced from their original places. It is exemplified with simulations that the model can produce a hierarchical clustering of dots by variation in thresholds for the wiring of virtual lines and also the model can additionally reproduce some geometrical illusions semiquantitatively. This model is further extended for perceptual grouping in line segment patterns and geometrical illusions obsrved in those patterns are reproduced by the extended model.

This paper deals with the scattering of a plane wave from a two-dimensional random thin film. For a Gaussian random disorder, a first order solution is derived explicitly by a probabilistic method. It is then found that ripples appear in angular distributions of the incoherent scattering. Furthermore, the incoherent scattering is enhanced in the directions of backscattering and specular reflection. Physical processes that yield such an enhanced scattering are discussed. Numerical examples of the coherent and incoherent scattering are illustrated in figures.

To improve the demodulated signal-to-noise ratio, SNR, for colored noise environments, we present a new direct-sequence spread-spectrum receiver system, whose construction is based on the concept of Shaped M-sequence Demodulation (SMD). This receiver has the function for shaping the local dispreading-code waveform. This method can modify the frequency transfer function from a received input to the damp-integrated output according to the power spectrum of colored noise added in the transmission process. SMD performs the combined function of a whitening filter and a matched filter, which can be used to implement an optimum receiver. For the case when the additive colored-noise power spectrum is known and the transmission channel is non-band-limited, a design theory is derived that provides the maximum SNR by choosing the best dispreading-code sequence corresponding to a given signature spreading-code sequence. The noise power component produced in the receiver damp-integrated-output is anayzed by introducing the auto-correlation matrix of the additive noise. The SNR performance of systems, one using non-optimized codes and the other using optimized codes, is examined and compared for various noise models. It is verified by analysis and computer simulation that, compared to a conventional system using non-optimized codes, remarkable SNR improvements can be achieved due to the whitening effect acquired without producing inter-symbol interference. In contrast, if a transversal whitening filter is front-ended, it produces inter-frame interference, degrading the SNR performance. The band-limiting effect of the transmission channel is also analyzed, and we confirmed that the codes optimized for the non-band-limited channel can be applied to the band-limited channel with little degradation of SNR. SMD is inherently tolerant of fast-changing noise such as fading, due to its frame-by-frame operation. Considering this function as a general demodulation scheme, it may be called "Local Code Filtering."

Spread-spectrum (SS) sharing with comb spectrum structure in a microcell/macrocell cellular architecture in order to increase spectral efficiency is proposed. Such method employs a filter in the code division multiple access (CDMA) transmitter to feature comb spectrum structure, and suppress interference with a narrowband time division multiple access (TDMA) system in using together in SS sharing. The relationship between microcellular capacity and macrocellular capacity of the system is explored and compared to those of conventional SS sharing and orthogonal sharing. To be concrete, we investigate two cases, i.e., using no power control and ideal power control in the TDMA system. In both cases, the proposed SS sharing gives better capacity results than the conventional SS sharing and in the comparison when ideal power control is used in th. TDMA system, it even has the property to oppose the orthogonal sharing in ideal condition without interference.

A method is presented for reconstructing the surface profile of a two dimensional rough surface boundary from the scattered far field data. The proposed inversion algorithm is based on the Kirchhoff approximation and in order to determine the surface profile, the numerical results illustrating the method are presented.

A method for the recognition of handprinted Thai characters input using an image scanner is presented. We use methods of edge detection and boundary contour tracing algorithms to extract loop structures from input characters. The number of loops and their locations are detected and used as information for rough classification. For fine classification, local feature analysis of Thai characters is presented to discriminate an output character from a group of similar characters. In this paper, four parts of the recognition system are presented: Preprocessing, single-character segmentation, loop structure extraction and character identification. Preprocessing consists of pattern binarization, noise reduction and slant normalization based on geometrical transformation for the forward (backward) slanted word. The method of single-character segmentation is applied during the recognition phase. Each character from an input word including the character line level information is subjected to the processes of edge detection, contour tracing and thinning to detect loop structures and to extract topological properties of strokes. The decision trees are constructed based on the obtained information about loops, end points of strokes and some local characteristics of Thai characters. The proposed system is implemented on a personal computer, and a high recognition rate is obtained for 1000 samples of handprinted Thai words from 20 subjects.

This paper presents an O(mn log n) time algorithm for an approximate string matching problem, in which a pattern string may contain variable length don't care characters. This problem is important for searching DNA sequences or amino acid sequences.

This paper presents a configuration of circularly polarized annular-ring microstrip antenna (ARMSA) and its design method to obtain high gain and low axial ratio including the analysis of finite ground plane effect using G.T.D. for personal satellite communication use. The ARMSA excited at TM21 mode through co-planar branch-line hybrid coupler for circular polarization produces a conical pattern which has high gain in low elevation angle. The relation of gain and axial ratio versus the dielectric constant of substrate are shown and the existence of the dielectric constant which satisfies two requirements, that is, high gain and low axial ratio are clarified. For car-top application, experimental results in the L-band showed satisfactory characteristics for vehicle antenna.

The ringing occurred in the step response causes an undesirable stripe pattern in TV signals. A simultaneous approximation with both the frequency and the step response is required in the designing filter which is used in the image signal processing in order to prevent the ringing. The wellknown Remez algorithm for designing FIR filters approximates the response only in the frequency domain. As the result, the filters designed by this algorithm causes the large ringing in the step response. In this paper, we propose the method of design for FIR filters with minimum amplitude in the stopband, under the condition that the step response has no ringing and the prescribed rise characteristics. For this end, we use the constrained successive projections method.

In this paper, we first analyze the resolution performance of the Gerschgorin radii based source number estimator (GDE, Gerschgorin Disk Estimator) proposed in [1] for independent closely-spaced plane waves. Based upon this analysis, we verify the resolution threshold of the Gerschgorin radii based method for two sources. New close-form expressions of the Gerschgorin radii are formulated and examined. For improvement of detection performance, we then further propose a enhanced GDE method (EGDE). Examples and comparisons with methods based on Gerschgorin radii and weighted Gerschgorin radii, as well as conventional methods are included. Finally, multi-source and/or closely spaced source problems are discussed.

This paper provides an architectural study of optical ring trunk-transmission networks using either Time Division Multiplexing (TDM) or Wavelength Division Multiplexing (WDM). A timeslot arrangement algorithm for distributed controlled TDM rings is proposed that minimizes the number of slots (wavelengths) required in bi-directional ring networks. This algorithm is applied in a straightforward manner to wavelength arrangement in WDM ring networks. The technique, characterized by timeslot (or wavelength) conversion, realizes common add/drop procedures in all Add/Drop Multiplexers (ADMs) when they are connected logically in a mesh topology. A self-healing algorithm is also proposed for network restoration. It offers good performance in terms of protection line-capacity, restoration delay, and survivability against multiple failures.

This paper presents the results of a simulation study of blocking and non-blocking switching for hierarchical ring networks. The switching techniques include wormhole, virtual cut-through, and slotted ring. We conclude that slotted ring network performs better than the more popular wormhole and virtual cut-through networks. We also show that the size of the node buffers is an important parameter and that choosing them too large can hurt performance in some cases. Slotted rings have the advantage that the choice of buffer size is easier in that larger than necessary buffers do not hurt performance and hence a single choice of buffer size performs well for all system configurations. In contrast, the optimal buffer size for virtual cut-through and wormhole switching nodes varies depending on the system configuration and the level in the hierarchy in which the switching node lies.

This paper concerns optimized facility design for VLSI production. The methods proposed are applicable in planning LSI production facilities with a good balance between the number of machines and the number of operators. The sequence in each processing step is analyzed in detail. A new algorithm based on the queueing model is developed for estimating the simultaneous requirements for the two kinds of resources, machines and operators. This estimation system can be applied to complicated fabrication schemes, such as batch processing, continuous processing, and mixed technologies. This methodology yields guidelines for ASIC LSI production system design.

This paper proposes a hierarchical parallel processing system for the multipass rendering method. The multipass rendering method based on the integration of radiosity and ray-tracing can synthesize photo-realistic images. However, the method is also computationally expensive. To accelerate the multipass rendering method, the system, called (Mπ)2, employs two kinds of parallel processing schemes. As a coarse-grain parallel processing, object-space parallel processing with multiple processing elements based on the object-space subdivision is adapted, and each processing element (PE) is equipped with multiple pipelined units for a fine-grain parallel processing. To balance load among the system, static load balancing at the PE level and dynamic load balancing at the pipelined unit level within the PE are introduced. Especially, we propose a novel static load allocation scheme, skewed-distributed allocation, which can effectively distribute a three-dimensional object space to one- or two-dimensional processor configuration of the (Mπ)2 system. Simulation experiments show that the two-dimensional (Mπ)2 systems with the skewed-distributed allocation outperform the three-dimensional systems with the non-skewed distributed allocation. Since lower dimensional systems can be built at a lower cost than higher dimensional systems, the skewed-distributed allocation will be meritorious. Besides, by the combination of static load balancing by the skewed-distributed allocation and the dynamic load balancing by dynamic ray allocation within each PE, the system performance can be further boosted. We also propose a cached frame buffer system to relieve access collision on a frame buffer.

Flurorinated liquid crystal compounds having fluorophenyl, difluorophenyl and trifluorophenyl moieties combined with ester linkages, 1,2-ethylenes and covalent bonds were prepared and checked for their physical properties i.e. mesophases, dielectric and optical anisotropy. viscosity, pretilt angle and threshold voltage. By introducing fluorine atom(s) into the molecules, optical anisotropy and threshold voltage decreased, though the nematic temperature range diminished. The investigated compounds were all chemically stable and by using the compounds nematic liquid crystalline mixtures having low threshold voltage, low viscosity, large optical anisotropy and wide nematic ranges which were suitable for AM-LCDs, could be obtained.

The order of faults which are targeted for test-pattern generation affects both of the processing time for test generation and the number of generated test-patterns. This order is referred to as a test generation schedule. In this paper, we consider the effect of scheduling in test generation. We formulate the test generation scheduling problem which minimizes the cost of testing. We propose schedulings based on test-pattern generation time, dominating probability and dominated probability, and analyze the effect of these schedulings. In the analysis, we show that the total test-pattern generation time and the total number of test-patterns can be reduced by the scheduling according to the descending order of dominating probability prior to the ascending order of test-pattern generation. This is confirmed by the experiments using ISCAS'85 benchmark circuits. Further, in the experiments, we consider eight schedulings, and show that the scheduling according to the ascending order of dominated probability is the most effective of them.