Materials for a new reinforcement method using an internal heating technique have been developed experimentally for fusion splices. The method employs a protective package of a carbon-fiber composite and a hot-melt adhesive in a heat-shrinkable tube. The most appropriate heating current and heating time were determined from a consideration of the decomposition temperature of the adhesive (300) and the complete shrinking temperature (115) and the minimum welding temperature of Nylon 12 (about 180). The protective package can be installed in less than 30 seconds at a power of 10 W. Air bubbles which might cause microbending were completely eliminated by using Nylon 12 as the hot-melt adhesive, irradiated polyethylene as the heat-shrinkable tube and a carbon-fiber-composite electrical heating rod which also acted a tension member. The key for preparing the carbon-fiber composite was to remove its impurities. Under the condition of temperature difference larger than 40 deg. between the shrinking temperature of the heat-shrinkable tube and the melting temperature of the hot-melt adhesive. Nylon 12 and irradiated polyethylene were needed for the complete elimination of residual bubbles. By using Nylon 12 as the hot-melt adhesive, a reliable protective package could be achieved for a fusion spliced optical fiber with a low excess loss of less than 0.06 dB/splice between -60 and +70 and a high tensile strength of 3.9 kg.

We have developed a Beam Space CMA (Constant Modulus Algorithm) Adaptive Array Antenna system (BSCMA adaptive array antenna) that may be suitable for mobile communications. In this paper, we present experimental results of interference cancellation characteristics using the developed system. The experiment was carried out in a large radio anechoic chamber, while desired and interference signals were transmitted to the system. We focused on the characteristics of capture, convergence and tracking in adaptive processing. The experimental results show excellent interference cancellation characteristics, and demonstrate that the BSCMA adaptive array antenna has a greater feasibility to be applied practically in mobile communications.

Several types of transmission-line coupling are analyzed to use in one- and two-dimensional active antenna arrays, and a method is developed to scan the beam of the arrays using the mutual locking theory. To compensate the undesired effect of strong radiative coupling of the nearest neighbor elements on the phased array performance, addition of resistive stubs to the end elements is proposed. In a 14 array it was observed that after the connection of resistive stubs, the scanning range of the array increased considerably. The effect of oscillator amplitudes on the phased array behavior is explored numerically. In the experiments main beam of 22 and 33 active antenna arrays were steered up to 25 and 15, respectively in the H-plane.

We present a novel replication technique for parallel applications where instances of the replicated application are active on different group of processors called replicas. The replication technique is based on the FTAG (Fault Tolerant Attribute Grammar) computation model. FTAG is a functional and attribute based model. The developed replication technique implements "active parallel replication," that is, all replicas are active and compute concurrently a different piece of the application parallel code. In our model replicas cooperate not only to detect and mask failures but also to perform parallel computation. The replication mechanisms are supported by FTAG run time system and are fully application-transparent. Different novel mechanisms for checkpointing and recovery are developed. In our model during rollback recovery only that part of the computation that was detected faulty is discarded. The replication technique takes full advantage of parallel computing to reduce overall computation time.

In this paper, we propose a new switching network architecture with output queueing, The proposed switch, FBSF (FAB Banyan Switching Fabrics) can deliver up to 2r packets simultaneously destined for the same outlet in a single time slot. The switch fabrics consist of Batcher sorter, a radix-r double shuffle network r-packet distributors, two FAB networks, and output buffer modules. The performance of the switch fabric is evaluated by measures of throughput, average queue length, average waiting time, and packet loss rate. Numerical and simulation results indicate that the switch exhibits very good delay-throughput performance over a wide range of input traffic.

A fully differential folded cascode CMOS OP amp is combined with an adaptive bias OTA to increase the slew rate, and a continuous-time CMFB circuit with a push-pull type combination of a NMOS input and a PMOS input differential amplifiers is used to maximize the output voltage swing. The fabricated OP amp using a 0.8 µm digital CMOS process gives more than three times improvement in slew rate with a 15% increase in DC power consumption and a 7.5% increase in chip area compared to the conventional OP amp fabricated on the same die. The output voltage swing was measured to be -0.75 V -0.7 V at the supply voltage of +/-1.2 V.

This paper proposes an FFT (Fast Fourier Transform) interference detection for interference suppression which combines notch filtering and FEC (forward error correction) to improve the Pe (probability of error) performance degradation due to co-channel interference in digital satellite communication systems. The proposed FFT interference detection scheme can determine the co-channel interference carrier frequency, power, and bandwidth precisely by using the power detection threshold suitable for the desired signal power spectrum, and the notch filter characteristic can be set according to the results. The interference suppression with the proposed scheme achieves the degradation in required Eb/No to only 1.0 dB at a Pe of 10-4 compared to that with the optimum notch filter (ideal detection) in unknown CW (continuous wave) and FM (frequency modulation) co-channel interference environments. Moreover, the proposed scheme improves the required Eb/No by 6.5 dB compared to that without a notch filter in an FM interference environment with interference carrier frequency offset normalized by the desired signal clock rate of 0.52, desired to undesired (interference) signal power ratio of 3 dB and interference bandwidth at 10 dB down power point from the peak normalized by the desired signal clock rate of 0.25.

An implementation of photometric stereo is described in which all directions of illumination are close to and rotationally symmetric about the viewing direction. THis has practical value but gives rise to a problem that is numerically ill-conditioned. Ill-conditioning is overcome in two ways. First, many more than the theoretical minimum number of images are acquired. Second, principal components analysis (PCA) is used as a linear preprocessing technique to determine a reduced dimensionality subspace to use as input. The approach is empirical. The ability of a radial basis function (RBF) neural network to do non-parametric functional approximation is exploited. One network maps image irradiance to surface normal. A second network maps surface normal to image irradiance. The two networks are trained using samples from a calibration sphere. Comparison between the actual input and the inversely predicted input is used as a confidence estimate. Results on real data are demonstrated.

The authors previously proposed a reconfigurable architecture called the "XL-scheme" in order to cope with processor element (PE) faults as well as link faults. However, they described an algorithm for compensating only for link faults. They determined the potential ability to tolerate faults of the XL-scheme for simultaneous faults of links and PEs, and left a reconstruction algorithm for simultaneous PE and link faults to be studied in the future. This paper briefly explains the XL-scheme and gives a reconstruction algorithm for simultaneous PE and link faults. The algorithm first replaces faulty PEs with healthy ones and then replaces faulty links with healthy ones. We then compute the reliabilities of the mesh-arrays with simultaneous PE and link faults by simulation. We compare the reliability of the XL-scheme with that of the one-and-half track switch model. It is seen that the former is much larger than the latter. Furthermore, we show the result for processing time.

The construction of fault-tolerant processor arrays with interconnections of cube-connected cycles (CCCs) by using an advanced spare-connection scheme for k-out-of-n redundancies called "generalized additional bypass linking" is described. The connection scheme uses bypass links with wired OR connections to spare processing elements (PEs) without external switches, and can reconfigure complete arrays by tolerating faulty portions in these PEs and links. The spare connections are designed as a node-coloring problem of a CCC graph with a minimum distance of 3: the chromatic numbers corresponding to the number of spare PE connections were evaluated theoretically. The proposed scheme can be used for constructing various k-out-of-n configurations capable of quick broadcasting by using spare circuits, and is superior to conventional schemes in terms of extra PE connections and reconfiguration control. In particular, it allows construction of optimal r-fault-tolerant configurations that provide r spare PEs and r extra connections per PE for CCCs with 4x PEs (x: integer) in each cycle.

For mobile communication systems with code division multiple access (CDMA), a new modulation scheme, π/2-shift BPSK, is proposed. The performance has been evaluated in terms of relative out-of-band power, bit-error rate (BER), and spectral efficiency. As the result, it is shown that the proposed scheme has an advantage over conventional BPSK, conventional QPSK, and π/4-shift QPSK under nonlinear amplification.

The dipole-dipole interaction among excitons is shown to give rise to an intrinsic nonlinearity, which yields a localized mode in a forbidden band, providing a coherent state for quantum computation. Employing this mode, a quantum XOR (exclusive OR) gate is proposed. A block structure of quantum dot arrays is also proposed, to implement quantum circuits comprising the quantum XOR gates for computation.

A punctured convolutional coded PR4ML system for digital magnetic recording, which applies a punctured coding method to the convolutional code and records the punctured code sequences on two tracks, is proposed. In this study, the bit error rate performance of the proposed system is obtained by computer simulation taking account of partial erasure, which is one of the nonlinear distortions at high densities, and it is compared with those of a conventional 8/9 coded PR4ML system and an I-NRZI coded PR4ML system. The results show that the proposed system is hardly affected by partial erasure and exhibits good performance in high-density recording. A bit error rate of 10-4 can be achieved with SNR's of approximately 13.2 dB and 9.1 dB less than those of the conventional 8/9 coded and I-NRZI coded PR4ML systems, respectively, at a normalized linear density of 3.

In this paper, we propose a novel algorithm for all-digital high speed symbol synchronization to be called the MBECM (Modified-Band Edge Component Maximization). The proposed algorithm has a structure based on the spectral line method. It simplifies and modifies the existing BECM algorithm to compensate for the timing offset caused by different phase characteristics of the BPF (band pass filter) at 1/2T and -1/2T. The algorithm is also independent of the carrier recovery and requires only two samples per symbol for its operation. Until now the timing detector's characteristics of the spectral line method including the M-BECM was not analyzed, particularly effect of the timing offset at convergence point. We analyze the timing detector's characteristics of the M-BECM and derive expressions for the timing detector's mean value (often called the S-curve) as a function of the normalized symbol-clock phase, the rolloff parameterand the bandwidth of the BPF. By using these expressions, the PDbias for eliminating the timing offset at an optimal convergence point are calculated. We also analyze and evaluate performance of the proposed algorithm in various ways such as jitter, timing detector output characteristics, etc. and suggest improvements. The proposed M-BECM is compared to the popular Gardner algorithm for high speed modem applications. The proposed algorithm has simpler structure than the Gardner algorithm and simulation results reveal that the proposed algorithm has better overall performance than the Gardner algorithm in narrow band.

Since the introduction of magnetoresistive (MR) heads, the areal density of hard disk drives (HDDs) has been increasing at a rate of 60% a year, and has now reached 1.4 Gb/sq. in. The data rate has also been increasing at a rate of 40% or more, and this has recently become a key factor in the ability of multimedia applications to transfer stored data rapidly from the HDD to the PC or workstation. Currently, data rates of around 150 Mb/sec are being implemented in products. In this study, key technologies for increasing both the areal density and the data rate of HDDs are proposed. If they are implemented, an areal density of around 10 Gb/sq. in. and a data rate of 200 Mb/sec or more can be achieved.

This paper proposes a new multiuser detector, quasi-decorrelating detector (QDD), for a synchronous CDMA system. The QDD has the same complexity as that of decorrelator detector (DD) although it uses feedback loops, the number of which is adjustable to balance the near-far resistance and noise enhancement. The results show that the QDD outperforms the DD under various operational conditions. The impact of different spreading codes on the performance of the QDD is studied. It is shown that the Gold code is the best spreading code suitable for the QDD.

In this paper, we present an error concealment method to recover damaged blocks for block-based image coding schemes. Imperfect transmission of image data results in damaged blocks in the reconstructed images. Hence recovering damaged image blocks is needed for reliable image communications. To recover damaged blocks is to estimate damaged blocks from the correctly received or undamaged neighborhood information with a priori knowledge about natural images. The recovery problem considered in our method is to estimate a larger block, which consists of a damaged block and the undamaged neighborhood, from the undamaged neighborhood. To find an accurate estimate, a set of the feature vectors is introduced and an estimate is expressed as a linear combination of the feature vectors. The proposed method recoveres damaged blocks by projecting the undamaged neighborhood information onto the feature vectors. The sequential projections onto the feature vectors algorithm is proposed to find the projection coefficients of the feature vectors to minimize the squared difference of an estimate and the undamaged neighborhood information. We tested our algorithm through computer simulations. The experimental results showed the proposed method ourperforms the frequency domain prediction method in the PSNR values by 4.0-5.0dB. Tthe reconstructed images by the proposed method provide a good subjective quality as well as an objective one.

Within the framework of a previously proposed vision system, a new part-segmentation algorithm, that breaks an object defined by its contour into its constituent parts, is presented. The contour is assumed to be obtained using an edge detector. This decomposition is achieved in two stages. The first stage is a preprocessing step which consists of extracting the convex dominant points (CDPs) of the contour. For this aim, we present a new technique which relaxes the compromise that exists in most classical methods for the selection of the width of the Gaussian filter. In the subsequent stage, the extracted CDPs are used to break the object into convex parts. This is performed as follows: among all the points of the contour only the CDPs are moved along their normals nutil they touch another moving CDP or a point on the contour. The results show that this part-segmentation algorithm is invariant to transformations such as rotation, scaling and shift in position of the object, which is very important for object recognition. The algorithm has been tested on many object contours, with and without noise and the advantages of the algorithm are listed in this paper. Our results are visually similar to a human intuitive decomposition of objects into their parts.

The finite reconfigurability and local reconfigurability of graphs were proposed by Sha and Steiglitz [1], [2] in connection with a problem of on-line reconfiguraion of WSI networks for run-time faults. It is shown in [2] that a t-locally-reconfigurable graph for a 2-dimensional N-vertex array AN can be constructed from AN by adding O(N) vertices and edges. We show that Ω(N) vertices must be added to an N-vertex graph GN in order to construct a t-locally-reconfigurable graph for GN, which means that the number of added vertices for the above mentioned t-locally-reconfigurable graph for AN is optimal to within a constant factor. We also show that a t-finitely-reconfigurable graph for an N-vertex graph GN can be constructed from GN by adding t vertices and tN + t (t+1)/2 edges.

We previously proposed a robust hybrid edge detector which relaxes the trade off between robustess against noise and accurate localization of the edges. This hybrid detector separates the tasks of localization and noise suppresion between two sub-detectors. In this paper, we present an extension to this hybrid detector to determine its optimal parameters, independently of the scene. This extension defines a probabilistic cost function using for criteria the probability of missing an edge buried in noise and the probability of detecting false edges. The optimization of this cost function allows the automatic selection of the parameters of the hybrid edge detector given the height of the minimum edge to be detected and the variance of the noise, σ2n. The results were applied to the 2D case and the performance of the adaptive hybrid detector was compared to other detectors.