The conventional synthesis procedure of discrete time sparsely interconnected neural networks (DTSINNs) for associative memories may generate the cells with only self-feedback due to the sparsely interconnected structure. Although this problem is solved by increasing the number of interconnections, hardware implementation becomes very difficult. In this letter, we propose the DTSINN system which stores the 2-dimensional discrete Walsh transforms (DWTs) of memory patterns. As each element of DWT involves the information of whole sample data, our system can associate the desired memory patterns, which the conventional DTSINN fails to do.

In this paper, we consider new and general models for imperfect sources of randomness, and show how to obtain quasi-random sequences from such sources. Intuitively, quasi-random sequences are sequences of almost unbiased elements over a finite set. Our model is as follows: Let A be a finite set whose number of elements is a power of 2. Let 1/|A| δ 1 be a constant. The source outputs an element on A with probability at most δ, depending on outputs made by itself so far. From the definition, our sources output at least two elements with nonzero probability. This model is very general, because the source may output only two elements of A with nonzero probability, and the other elements with probability 0. This ability becomes a big difficulty for generating quasi-random sequences. All the methods for the existing models such as PRB-models and δ-sources fail to generate quasi-random sequences from our models. We here give a new algorithms which generates almost unbiased elements over A from such models.

This paper presents a heuristic algorithm that minimizes the delay of the given circuit through a two-pass cell selection in cell-based design. First, we introduce a new graph, called candidate web, which conveniently represents all cell combinations available for the implementation of the given circuit. We, then, present an efficient method to obtain a tentative set of optimal cells, while estimating the delay of the longest path between each cell and the primary output on the candidate web. In this step, multiple cells are allowed to bind the same logic gate. Finally, we describe how the proposed approach actually selects the optimal cells from the tentative set, which would minimize the circuit delay. Experimental results on a set of benchmarks show that the proposed approach is effective and efficient in minimizing the delay of the given circuit.

There are two dynamics issues in vision chips: (i) The temporal dynamics issue due to the parasitic capacitors in a CMOS chip, and (ii) the spatial dynamics issue due to the regular array of processing elements in a chip. These issues are discussed in [1]-[3] for the resistor network with only associated parasitic capacitances. However, in this paper we consider also parasitic inductances as well as parasitic capacitances for a more precise network dynamics model. We show that in some cases the temporal stability condition for the network with parasitic inductances and capacitances is equivalent to that for the network with only parasitic capacitances, but in general they are not equivalent. We also show that the spatial stability conditions are equivalent in both cases.

Acquisition of three-dimensional information of a real-world scene from two-dimensional images has been one of the most important issues in computer vision and image understanding in the last two decades. Noncontact range acquisition techniques can be essentially classified into two classes: Passive and active. This paper concentrates on passive depth extraction techniques which have the advantage that 3-D information can be obtained without affecting the scene. Passive range sensing techniques are often referred to as shape-from-x, where x is one of visual cues such as shading, texture, contour, focus, stereo, and motion. These techniques produce 2.5-D representations of visible surfaces. This survey discusses aspects of this research field and reviews some recent advances including video-rate range imaging sensors as well as emerging themes and applications.

Feedback of class memberships is incorporated into multimodal pattern classifiers and their unsupervised learning algorithm is presented. Classification decision at low levels is revised by the feedback information which also enables the reconstruction of patterns at low levels. The effects of the feedback are examined for the McGurk effect by using a simple model.

In this paper, the bit error rate (BER) of 16 differential amplitude phase shift keying (16DAPSK) modems in future mobile communication system is derived analytically. The channel employed in this paper is the frequency-selective and fast Rayleigh fading channel, corrupted by cochannel interference (CCI) and additive white Gaussian noise (AWGN). Exact expressions for the probability distributions of the differential phase and amplitude ratio are derived for the BER calculation. The BER and optimum boundary are obtained for various channel conditions. In addition, the results for the BER in the presence of CCI are provided.

This paper proposes a novel sequential coherent preambleless demodulator that uses phase signals instead of complex signals in the automatic frequency control (AFC) and carrier recovery circuits. The proposed demodulator employs a phase-combined frequency error detection circuit and dual loop AFC circuit to achieve fast frequency acquisition and low frequency jitter. It also adopts an open loop carrier recovery scheme with a sample hold circuit after the carrier filter to ensure carrier signal stability within a packet. It is shown that the frame error rate performance of the proposed demodulator is superior, by 30%, to that offered by differential detection in a frequency selective Rayleigh fading channel. The hardware size of the proposed demodulator is about only 1/10 that of a conventional coherent demodulator employing complex signals.

In Adleman's Function Field Sieve algorithm solving the discrete logarithm problem in a finite field, it is assumed that a random bivariate polynomial in the certain class is absolutely irreducible with high probability. In this letter we point out that if we use Cab type random polynomials then we always get absolutely irreducible polynomials. We can also simplify the calculation of a product of many rational functions on a curve that belongs to the field of definition by the use of a Cab curve.

Optical frontend and distributed amplifier IC modules, both containing GaAs heterojunction-bipolar-transistors (HBT), have been developed for 40 Gb/s optical receiver. To achieve high-speed operations, the elements in the modules including the IC and signal lines, were designed to achieve a wider bandwidth with lower electrical reflection. The influence of a bonding-wire inductance was taken into particular account in optimizing the parameters of the ICs. The optical frontend, consisting of a waveguide pin-photodiode and an HBT preamplifier IC, exhibits a transimpedance gain of 43 dBΩ and a bandwidth of 31 GHz. The distributed amplifier IC module achieves a gain of 9 dB and a bandwidth of 39 GHz. A 40-Gb/s optical receiver constructed with these modules exhibited a high receiver sensitivity of -28. 2 dBm for a 40-Gb/s optical return-to-zero signal.

A new dynamic programming (DP) based algorithm for monotonic and continuous two-dimensional warping (2DW) is presented. This algorithm searches for the optimal pixel-to-pixel mapping between a pair of images subject to monotonicity and continuity constraints with by far less time complexity than the algorithm previously reported by the authors. This complexity reduction results from a refinement of the multi-stage decision process representing the 2DW problem. As an implementation technique, a polynomial order approximation algorithm incorporated with beam search is also presented. Theoretical and experimental comparisons show that the present approximation algorithm yields better performance than the previous approximation algorithm.

In order to reduce state explosion problem, techniques such as symbolic state space traversal and partial order reduction have been proposed. Combining these two techniques, however, seems difficult, and only a few research projects related to this topic have been reported. In this paper, we propose handling single place zero reachability problem of Petri nets by using both partial order reduction and symbolic state space traversal based on ZBDDs. We also show experimental results of several examples.

This paper proposes an algorithm for analyzing the reachability property of Petri nets by the use of unfoldings. It is known that analyzing the reachability by using unfoldings requires exponential time and space to the size of unfolding. The algorithm is based on the branch and bound technique, and experimental results show efficiency of the algorithm.

This paper is consisting of the two novel EMC technologies that we have been developed in our laboratory. The first is the technology for measuring the RF (Radio Frequency) nearby magnetic field and estimation of the RF current in the printed circuit board (PCB) by using the small loop antenna with multi-layer PCB structure developed by our laboratory. I introduce the application of our small loop antenna with its physical structure and the analysis of the nearby magnetic field distribution of the printed circuit board applying the discrete Wavelet analysis. We can understand the behavior of the digital circuit in detail, and we can also take measures to meet the specification about the electromagnetic radiation from the digital circuit from the higher order of priority by using these technologies. The second is our proposing novel technology for reducing the electromagnetic radiation from the digital equipment by taking notice of the improvement of the de-coupling in the PCB. We confirmed the remarkable effect of this technology by redesigning the motherboard of the small-sized computer.

This letter introduces a new digital halftoning technique based on error diffusion along a random space-filling curve. The purpose of introducing randomness is to erase regular patterns which tend to arise in an image area of uniform intensity. A simple algorithm for generating a random space-filling curve is proposed based on a random spanning tree and maze traversal. Some experimental results are also given.

Phase performance in a fiber optic temperature sensor using a mode-division multiplex is studied. The phase shift due to the temperature change of a multimode graded-index optical fiber is analyzed. The intensity fluctuation by the interference of two modes is estimated in computer simulation.

This paper describes a 2.5-Gb/s optical receiver and transmitter chipset consisting of a preamplifier, a main amplifier, a clock and data recovery (CDR) circuit, and a laser-diode (LD) driver. Low-voltage and adjustment-free circuit techniques are introduced in order to achieve low cost and low power circuits. Circuit adjustments are eliminated by using a multi-stage automatic offset canceling technique in the main amplifier, and by using a PLL structure with a sample-and-hold technique in the CDR circuit. For power reduction, ICs are operated at a power supply voltage of -3 V. Fabricating the ICs by a 0.5-µm Si bipolar process makes it possible to achieve 2.5-Gb/s receiver and transmitter operation with a total power dissipation of 1.04 W. Especially significant is that the receiver ICs need no external devices and adjustments.

This paper proposes a medium access control (MAC) protocol for single-hop WDM star-coupler networks, in which the number of stations is larger than the number of channels and the stations have arbitrary distances to the star coupler. The proposed protocol has one control channel for reserving the slots of data channels and several data channels which are used to transmit traffic. This paper also suggests a scheme that accomplishes load balancing among data channels for arbitrary traffic patterns between stations. Since this load balancing scheme diminishes an influence that traffic patterns have on the performance of the proposed MAC protocol, the proposed system is appropriate for systems which have asymmetric traffic intensity between stations. Throughput and mean message delay of the MAC protocol are analyzed using a discrete time Markov process and a D/G/1 queue with batch arrivals. The numerical results show that the performance is improved as the message length increases, the maximum round-trip propagation delay decreases, and the number of data channels increases.

This paper analyzes the performance of direct-detection optical CDMA systems with single optical hard-limiter using equal-weight orthogonal (EWO) signaling. Moreover, this paper clarifies the basic structure and the performance of the system using time-shifted versions of optical orthogonal code (OOC's) as EWO signaling. The system assigns the time-shifted versions of OOC's to the transmission of bits "0" and "1," respectively. Thus, the system does not require dynamic estimation of the receiver threshold. The performance is analyzed under the Gaussian approximation of an avalanche photodiode (APD) output where the effects of APD noise, thermal noise and interference are included. From the theoretical analysis and numerical results, it is shown that the system has good performance without dynamic estimation of the receiver threshold.

This paper presents a high-speed CAC scheme, called PERB CAC (CAC based on Prior Estimation for Residual Bandwidth). This scheme estimates the residual bandwidth in advance by generating virtual requests for connection. When an actual new request occurs, PERB CAC can instantaneously judge if the required bandwidth is larger than the estimated residual bandwidth. PERB CAC provides very rapid response time both for statistical and deterministic bandwidth allocation services, while keeping statistical multiplexing gain for the former service. Numerical results indicate that PERB CAC provides reasonably accurate and conservative values of residual bandwidth. In addition, by using PERB CAC, both services are able to be accommodated into a single VP. VP capacity control is more relaxed than is true with conventional VP-separation management. This is another merit of PERB CAC. Therefore, PERB CAC can achieve high-speed connection set-up while utilizing network resources in a cost-effective manner.