Recent growth in computer communications has led to an increased requirement for high-speed backbone networks. In such high-speed networks, the principle adopted for a time-sensitive flow control mechanism should be that of autonomous decentralized control. In this mechanism, each node in a network manages its local traffic flow only on the basis of the local information directly available to it, although it is desirable that the individual decisions made at each node lead to high performance of the network as a whole. In our previous studies, we have investigated the behavior of local packet flows and the global performance achieved when a node is congested, and proposed the diffusion-type flow control model. However, since we used a simple and homogeneous network model in the evaluation, the results cannot be generalized. In this paper, we propose an extension of the diffusion-type flow control model in order to apply it to networks with inhomogeneous configurations. We show simulation results for two cases: different propagation delays and multiple bottlenecks. Both results show that the proposed diffusion-type flow control achieves high and stable performance even if the network is congested.

A new state reduction method of incompletely specified sequential machines is proposed in this paper. The method is based on a genetic algorithm implementing a dormant mechanism. MCNC benchmark machines are simplified by using this method to evaluate the method. The experimental results show that machines of almost the same number of states as the minimum ones can be derived by this method.

The present paper proposes differential transmission line structures on Si ULSI. Interconnect structures are examined using numerical results from a two-dimensional electromagnetic simulation (Ansoft, 2D Extractor). The co-planar and diagonal-pair lines are found to have superior characteristics for gigahertz signal propagation through long interconnects. The proposed diagonal-pair line can reduce the crosstalk noise and interconnect resource concurrently.

Evaluation of cyclic transitions in the discrete-time neural networks with antisymmetric and circular interconnection weights has been derived in an asymptotic mathematical form. The type and the number of limit cycles generated by circular networks, in which each neuron is connected only to its nearest neurons, have been investigated through analytical method. The results show that the estimated numbers of state vectors generating n- or 2n-periodic limit cycles are an exponential function of (1.6)n for a large number of neuron, n. The sufficient conditions for state vectors to generate limit cycles of period n or 2n are also given.

In this study, an improved heterojunction bipolar transistor (HBT) monolithic microwave integrated circuit (MMIC) active mixer is designed and fabricated. The HBT MMIC active mixer that is integrated with a low-noise amplifier (LNA) and active power adder can not only achieve high isolation, but can also dispense with one active component and reduce power consumption at the same time. Measurement results show that the conversion gain, LO-RF isolation, and double sideband noise figure (DSB-NF) of the proposed mixer are 22 dB, 40 dB, and 7 dB, respectively.

The development of multi-channel digital broadcasting has generated a demand not only for new services but also for smart and highly functional capabilities in all broadcast-related devices. This is especially true of TV receivers on the viewer's side. With the aim of achieving a friendly interface that anybody can use with ease, we built a prototype spoken dialogue interface for TV operation based on data collected by using Wizard of Oz method. At the current stage of our research, we are using this system to investigate the usefulness and problem areas of an interactive voice interface for TV operation.

A CMOS voltage-to-current converter in weak inversion is presented in this Letter. It can operate for low supply voltage and its power consumption is also low. As the input voltage varies from -0.15 V to 0.15 V, the measured maximum linearity error for the proposed voltage-to-current converter, is about 3.35%. Its power consumption is only 26 µW under the supply voltage of 2 V. The proposed voltage-to-current converter has been fabricated in a 0.5 µm N-well CMOS 2P2M process. The proposed circuit is expected to be useful in analog signal processing applications.

The parasitic capacitances induced in the spaces between an air-bridge interconnection and a drain pad (Cad), and between an air-bridge interconnection and a gate head (Cag) from a power CPW PHEMT are not negligible. In this paper, a modified equivalent circuit model for a CPW PHEMT and an improved CPW PHEMT for millimeter-wave applications are proposed. These were proved by measuring the fabricated CPW PHEMT and improved CPW PHEMT. These capacitances were confirmed by measuring the gate-source coupling using CPW PHEMT patterns without an active layer. From the measurements, the improved CPW PHEMT has the lowest coupling (loss) and the highest S21 gain among four different types tested at 60 GHz. And the improved CPW PHEMT is a feasible device which can be directly applied in millimeter-waves as a power device.

In this work, we study on a data encryption scheme based on a shape-variable truncated Baker transformation. First we show statistical properties of the shape-variable truncated Baker transformation. Then we propose a data encryption scheme with this map and verify its performance whether it satisfies fundamental conditions on confusion and diffusion required for data encryption schemes.

An adaptive 4-state phase-frequency detector (PFD) for clock and data recovery (CDR) PLL of non return to zero (NRZ) data is presented. The PLL achieves false-lock free operation with rapid frequency-capture and wide bit-rate-capture range. The variable bit rate operation is achieved by adaptive delay control of data delay. Circuitry and overall architecture are described in detail. A z-Domain analysis is also presented.

We analyze the Lagarias-Odlyzko low-density attack precisely, and show that this low-density attack can be applied to the Chor-Rivest and the Okamoto-Tanaka-Uchiyama cryptosystemes, which are considered to be secure against the low-density attack. According to our analysis, these schemes turn out to be no longer secure against the low-density attack.

This paper describes a 2.4-GHz downconverter that runs on a 1-V supply. The downconverter integrates an LNA, a quadrature mixer, a complex channel-select band-pass filter (BPF), a limiting amplifier, and a frequency doubler using 0.2-µm CMOS/SOI technology. The frequency doubler doubles the frequency deviation of FM signals as well as the frequency itself, which in turn doubles the modulation index. This improves the sensitivity of FM demodulation. The power consumption of the downconverter is 23 mW with a 1-V power supply. A bit-error-rate (BER) measurement using the downconverter and a demodulation IC shows -76.5-dBm sensitivity at a 0.1% BER.

In 1960, the famous computer pioneer J.C.R. Licklider described a vision for human-computer interaction that he called "man-computer symbiosis. " Licklider predicted the development of computer software that would allow people "to think in interaction with a computer in the same way that you think with a colleague whose competence supplements your own. " More than 40 years later, one rarely encounters any computer application that comes close to capturing Licklider's notion of human-like communication and collaboration. We echo Licklider by arguing that true symbiotic interaction requires at least the following three elements: a complementary and effective division of labor between human and machine; an explicit representation in the computer of the user's abilities, intentions, and beliefs; and the utilization of nonverbal communication modalities. We illustrate this argument with various research prototypes currently under development at Mitsubishi Electric Research Laboratories (USA).

The accuracy of channel estimation significantly affects the performance of coherent rake receiver in DS-CDMA systems. It is desirable for improved channel estimation to employ a channel estimation filter (CEF) whose bandwidth is adjustable to the channel condition. In this paper, we consider the use of moving average (MA) FIR filters as the CEF since it is simple to implement and can provide relatively good receiver performance. First, we optimize the tap size of the MA FIR CEF so as to minimize the mean squared error of the estimated channel impulse response. For practical applications, we propose a low-complexity adaptive channel estimator (ACE), where the tap size of the MA FIR CEF is adjusted based on the estimated channel condition by exploiting the correlation characteristics of the received pilot signal. Numerical results show that the use of the proposed ACE can provide the receiver performance comparable to that of Wiener CEF without exact a priori information on the operating condition.

Modern video compression usually consists of ME/MC (Motion Estimation/Motion Compensation), transform, and quantization of the transform coefficients. Efficient bit allocation technique to distribute available bits to motion parameters and quantized coefficients is an important part of the whole system. A method that is very complex and/or needs buffering of many future frames is not suitable for real time application. We develop an efficient bit allocation technique that utilizes the estimated effect of allocated bits to motion parameter and quantization on the overall quality. We also propose an hierarchical block based ME/MC technique that requires less computations than classical BMA (Block Matching Algorithm) while offering better motion estimation.

There has recently been considerable interest in research on wearable non-grounded force display. However, there have been no developments for the communication of nonverbal information (ex. tennis and golf swing). We propose a small and lightweight wearable force display to present motion timing and direction. The display outputs a torque using rotational moment and mechanical brakes. We explain the principle of this device, and describe an actual measurement of the torque and torque sensitivity experiments.

A method for automatic and fast shot detection for the MPEG video is proposed. Shot detection is the first step in analyzing and searching a large amount of video data. Our proposed method is based on activity of images as well as intra MBs in the video frame. It is possible to detect scene changes rapidly by using information from the compressed MPEG video data without the need for full-frame decoding. Experimental results show that the proposed method can provide good performance at a low computational cost.

Most of the existing studies on storing and searching XML documents effectively manipulate each XML document independently. Therefore, techniques for storing XML documents together that have similar meaning or structure are required for efficiency. Also, as a unified access method for various XML storage systems that have different storage forms, studies to integrate the DTD or XML schema of each storage system into one are required, because many XML documents do not have a particular DTD or XML schema, or XML documents can be written in various ways. Therefore, studies on the integration techniques for XML instances are needed. The XML integration technique can be used effectively in the case of constructing a data warehouse for heterogeneous XML storage systems. The proposed integration techniques remove the space duplicated for the same elements in XML documents. The proposed techniques significantly reduce the search time for general queries on the XML documents because it stores the related parts in XML documents close.

Integral equation method is used to compute three-dimension-structure capacitance in this paper. Since some multi-conductor structures present regular periodic property, the periodic cell is used to reduce the computational domain with adding appropriate magnetic and electric walls. The periodic Green's function in the integral equation method is represented in the form of infinite series with slow convergence. In this paper, Shanks transformation is used to accelerate the convergence. Numerical examples show that the proposed method is accurate with a much higher efficiency in capacitance extraction for 3-D periodic structures.

This paper presents the improvement of the transient response and stability for a two-stage DC-DC converter by removing the output inductor. The conventional two-stage converter consists of a buck converter used as the first stage and a half-bridge converter used as the second stage. The proposed circuit topology removing the output inductor and the conventional topology are compared. Removing the output inductor results in the system-order reduction of the transfer function. As a result, the stability is improved, and the crossover frequency of the open-loop transfer function becomes higher. The effectiveness of the proposed circuit topology was experimentally confirmed.