We propose an extended one-shot decorrelating detector (EOS-DD) which may be viewed as a generalized double window multiuser detector (DW-MD) for asynchronous direct-sequence code-division multiple-access (DS/CDMA) systems in frequency selective fading environments. The EOS-DD extends a processing window and the received signal over an extended window is utilized for decorrelating. The effects of the window size on BER performance are investigated by numerical analysis. Analysis and simulation show that the EOS-DD is superior to the one-shot decorrelating detector (OS-DD) and finite memory length truncated decorrelating detector (FIR-DD) in terms of noise enhancement and near-far resistance. It is also shown that the EOS-DD with window size 4 can provide significantly improved performance compared to the EOS-DD with window size 2.

In recent years, sliding electric contacts came to be often used under very severe conditions such as high temperature, extremely low temperature, high vacuum, etc. Conventionally, solid lubricants having excellent properties in lubricating performance are generally used compositely with a metal of high electric conductivity, because of their high electrical resistivity. In the present study, we proved that more excellent sliding electrical contacts can be produced with a design made by controlling the distribution on contact surface of a solid lubricant having excellent lubricating performance and of a metal with high electric conductivity through expansion of Greenwood's theory.

The interrupting characteristics of low voltage current limiting circuit breakers have directly relationship with the magnitude and distribution of magnetic field produced by contact system and splitter plates. In order to analyze the influence of configuration of contact system on current limiting characteristics, 3D magnetic field of arc chamber (including contact system, arc, splitter plates) is calculated. Furthermore, the electromagnetic repulsion force of movable contact is also calculated. The results can be used to improve configuration of arc quenching chamber. The cooperation between operating mechanism and electromagnetic repulsion force is also analyzed in this paper.

Arc duration of silver contacts was measured with fixed short gap under the condition of different constant gaps and different constant currents, which are close to the minimum arc current of the contact material. The results indicated that the arc occurred even at the current less than the minimum arc current. The arc duration varies in different operations at the same testing condition and it distributes exponentially in the time range up to 100 microseconds. The time constant τ and the extinction rate λ of the distribution were calculated, and related to the arc current. It was assured by silver electrode arc that, even below the so-called minimum arc current, arc ignition may occur but, in this case, the arc duration is momentary, and, as the arc current decreases, the arc extinction rate becomes large.

The low phase noise, low supply voltage 1.3 GHz CMOS VCO has been realized by 0.25 µm standard CMOS technology without any trimming and any tuning. The phase noise characteristics of -109 dBc/Hz and -123 dBc/Hz at 100 kHz offset and 500 kHz offset were achieved from carrier, respectively, with 1.3 GHz oscillation frequency at 1.4 V supply voltage. The performance of 1.4 V supply voltage phase noise was superior to that of 2.0 V supply voltage phase noise due to low output impedance current source. The tuning ranges of 13.3%, 16.6%, and 20.1% for 1.4 V, 1.8 V, and 2.0 V supply voltage were achieved, respectively. The amplifier consisted of one pair of PMOS differential stage with large gate length NMOS current source to realize low supply voltage operation and to avoid flicker noise contribution for phase noise. The on-chip spiral inductor consisted of three terminals arranged in a special shape to obtain high Q and small chip area. The power dissipation of this VCO was 22.4 mW without buffer amplifier.

This paper describes the design of a 2.7 V operational, 200 MS/s, 14-bit CMOS D/A converter (DAC). The DAC consists of 63 current cells in matrix form for an upper 6-bit sub-DAC, and 8 current cells and R-2R ladder resistors for a lower 8-bit sub-DAC. A source degeneration resistor, for which a transistor in the triode operational region is used, is connected to the source of a MOS current source transistor in a current cell in order to reduce the influence of threshold voltage (Vth) variation and to satisfy the differential nonlinearity error specification as a 14-bit DAC. In conventional high-speed and high-resolution DACs that have the same design specifications described here, spurious-free dynamic range (SFDR) characteristics commonly deteriorate drastically as the frequency of the reconstructed waveform increases. The causes of this deterioration were carefully examined in the present study, finding that the deterioration is caused in part by the input-data-dependent time-constant change at the output terminal. Unexpected current flow in parasitic capacitors associated with current sources causes the change in the output current depending on the input data, resulting in time-constant change. In order to solve this problem, we propose a new output circuit to fix the voltage at the node where the outputs of the current sources are combined. SPICE circuit simulation demonstrates that 63 dB of SFDR characteristics for the 90 MHz reconstructed waveform at the output can be realizable when the supply voltage is 2.7 V, the clock rate is 200 MS/s, and the power dissipation is estimated to be 300 mW.

This paper describes two methods to construct fuzzy inference rules by the simplified fuzzy reasoning. The present methods have a construction mechanism of the rule unit that is applicable in two parameters: the central value and the width of the membership function in the antecedent part. The first approach is to create a rule unit near the selected rule which has the nearest position from the central input space for the central value. The second is to create a rule unit near the selected rule which has the minimum width for the width. Experimental results are presented in order to show that the proposed methods are effective in difference on the inference error and the number of learning iterations.

With the advance of high-speed network technologies, availability and popularity of streaming media contents over the Internet has grown rapidly in recent years. Because of their distinct statistical properties and user viewing patterns, traditional delivery and caching schemes for normal web objects such as HTML files or images can not be efficiently applied to streaming media such as audio and video. In this paper, we therefore propose an integrated caching scheme for streaming media with segment-based caching and hierarchically distributed proxies. Firstly, each stream is divided into segments and their caching algorithms are considered to determine how to distribute the segments into different level proxies efficiently. Secondly, by introducing two kinds of segment priorities, segment replacing algorithms are proposed to determine which stream and which segments should be replaced when the cache is full. Finally, a Web-friendly caching scheme is proposed to integrate the streaming caching with the conventional caching of normal web objects. Performance of the proposed algorithms is verified by carrying out simulations.

Gallium nitride (GaN) is one of the wurtzite-type materials and has semiconducting properties. Crystallinities of GaN thin films are usually poor when they are directly grown on polycrystalline metal-foils which are expected as substrates for realizing novel giant microelectronic devices. Improvements of crystal orientations of GaN thin films grown on such polycrystalline metal-foils are tried by using several kinds of intermediate layers. Aluminum nitride (AlN), GaN, silicon dioxide (SiO2) and Si are chosen as materials for the intermediate layers. The crystal orientations of GaN thin films grown by inserting the SiO2 and Si intermediate layers with adequate thicknesses are markedly improved, while those grown on the AlN or GaN intermediate layers are not improved. These differences are not caused by the kinds of the materials used for the intermediate layers but by differences in their crystallinities.

In the study, we build a system called Adaptive Visual Attentive Tracker (AVAT) for the purpose of developing a non-verbal communication channel between the system and an operator who presents intended movements. In the system, we constructed an HMM (Hidden Markov Models)-based TD (Temporal Difference) learning algorithm to track and zoom in on an operator's behavioral sequence which represents his/her intention. AVAT extracts human intended movements from ordinary walking behavior based on the following two algorithms: the first is to model the movements of human body parts using HMMs algorithm, and the second is to learn the model of the tracker's action using a model-based TD learning algorithm. In the paper, we describe the integrated algorithm of the above two methods: whose linkage is established by assigning the state transition probability in HMM as a reward in TD learning. Experimental results of extracting an operator's hand sign action sequence during her natural walking motion are shown which demonstrates the function of AVAT as it is developed within the framework of perceptual organization. Identification of the sign gesture context through wavelet analysis autonomously provides a reward value for optimizing AVAT's action patterns.

It is well known that Orthogonal Frequency Division Multiplexing (OFDM) scheme is robust to frequency selective fading in wireless channels. However, once delayed signals beyond a guard interval of an OFDM symbol are introduced in a channel with large delay spread, inter-symbol interference causes a severe degradation in the transmission performance. In this paper, we propose a novel pre-Fast Fourier Transform (FFT) OFDM adaptive antenna array, which requires only one FFT processor at a receiver, for suppressing such delayed signals. We analytically derive the optimum weights for the beamformer based on the Maximum Signal-to-Noise-and-Interference power Ratio (SNIR) and the Minimum Mean Square Error (MMSE) criteria, respectively. Computer simulation results show its good performance even in a channel where Directions of Arrival (DoAs) of arriving waves are randomly determined.

Transmit diversity schemes are an effective capacity improvement method for down link of wideband code division multiple access (W-CDMA) systems. In this paper, we propose to use transmit antenna subset selection scheme in conjunction with closed loop transmit adaptive array (TxAA). The proposed scheme selects NS optimum antennas among NT (>NS) transmit antennas in order to maximize diversity gain from the selected antennas, and also reduces the cost of RF chains by employing two different types of RF modules for the selected and the unselected antenna group, respectively. Computer simulation results show performance improvement by the proposed scheme over the conventional TxAA when considering up link control information feedback.

This paper proposes an enhanced method for multiple description coding (MDC) using whitening transform. The MDC using correlating transform is an error resilient coding technique that explicitly adds correlation between two descriptions to enable the estimation of one set from the other when one set is dropped in channel. This paper proposes a method to overcome practical problems that decoder must know statistics of original image in the conventional correlating transform method. The MDC using whitening transform does not need additional statistical information to reconstruct a image because the coefficients whitening transformed have uni-variance statistics. Our experimental results show that the proposed method achieves a good trade-off between the coding efficiency and the reconstruction quality. We obtain that PSNR of image reconstructed from two descriptions is about 0.93 dB higher at the 1.0BPP and PSNR from only one description is about 1.88 dB higher than conventional method at the same rate of 'Lena' image.

In an attempt to improve the performance under frequency selective fading environment, we develop in this paper an orthogonal frequency division multiplex (OFDM) system in which adaptive interleaving is applied. The adaptive interleaving is a method that assigns symbols adaptively to the subcarriers in order to cope with frequency selective fading based on a channel state information (CSI) sent back from the reception end. The concept of adaptive interleaving is to maximize a free Euclidean distance in the limited interleave size. In this paper, we extend the method by an introduction of bit interleaving and multiple trellis coded modulation (MTCM). MTCM assigns two or more symbols to one trellis branch and shows good performance in frequency selective fading. If we could assign those set of symbols with an aid of the adaptive interleaving, the performance improvement can be expected. Another improvement method considered in this paper is the use of bit interleaving. The bit interleaving techniques randomize the effect of channel more efficiently compared to the case of symbols interleaving. Thus the further performance improvement is expected. One draw back is that since the interleaving process is done in bit level, bit interleaving can not be applied to TCM nor MTCM. In this paper, we mainly focus on adaptive bit and symbol interleaving and discuss the performance from the point of interleaving effect, and the error correcting code (convolutional code and MTCM).

In this paper, we propose an efficient requantization method for transcoding of MPEG video. Transcoding is the process of converting a compressed video format to another different compressed video format. We propose an simple and efficient transcoding by requantization in which MPEG coded video at high bit-rate is converted into MPEG bitstream at lower bit-rate. To reduce a image quality degradation, we use HVS (Human Visual System). By using this effect, the part of image in high activity region is coarsely quantized without seriously degrading the image quality. Experimental results show that the proposed method can provide good performance.

A bi-directional and multi-channel wireless telemetry capsule, 11 mm in diameter, is presented that can transmit video images from inside the human body and receive a control signal from an external control unit. The proposed telemetry capsule includes transmitting and receiving antennas, a demodulator, decoder, four LEDs, and CMOS image sensor, along with their driving circuits. The receiver demodulates the received signal radiated from the external control unit. Next, the decoder receives the stream of control signals and interprets five of the binary digits as an address code. Thereafter, the remaining signal is interpreted as four bits of binary data. Consequently, the proposed telemetry module can demodulate external signals so as to control the behavior of the camera and four LEDs during the transmission of video images. The proposed telemetry capsule can simultaneously transmit a video signal and receive a control signal determining the behavior of the capsule itself. As a result, the total power consumption of the telemetry capsule can be reduced by turning off the camera power during dead time and separately controlling the LEDs for proper illumination of the intestine.

An effective method for lossless video compression using intra-frame coding algorithms is described. Intra-frame coding is mainly used for still image compression and does not exploit a temporal correlation in video sequences. With the proposed method, multiple frames are combined into one large picture by interleaving all pixel data. In a large generated picture, the temporal correlation of the video sequence is transformed into a spatial correlation. A large picture enables images to be coded more efficiently and decreases the bitrate for lossless coding using intra-frame coding. We demonstrated the effectiveness of this method by encoding video sequences using JPEG 2000 and JPEG-LS.

In traditional file systems, data clustering and grouping have improved small file performance. These schemes make it possible for file systems to use large data transfers in accessing small files, reducing disk I/Os. However, as file systems age, disks become too fragmented to support the grouping and clustering. To offer a solution to this problem, we describe a De-Fragmented File System (DFFS), which gradually alleviates fragmentation of small files. By using data cached in memory, DFFS dynamically relocates blocks of small fragmented files, clustering them on the disks contiguously. In addition, DFFS relocates small related files in the same directory, grouping them at contiguous disk locations.

Design patterns can be regarded as an approach to encapsulate and reuse good design practices. However, most design patterns are specified using informal text and examples. To obtain all of the benefits of patterns, formal specification and tool support are indispensable. This paper proposes a Design Pattern Specification Language (DPSL) that is both manageable and effective. The DPSL provides software developers with the capability to treat design patterns as concrete design units without lowering abstraction. To demonstrate the usability of our DPSL and its application in design modeling, we have developed a prototype tool that supports the DPSL in UML diagrams. This prototype allows us to demonstrate the tool's support possibilities and the usability of patterns for software development applications.

High-speed streaming services are considered to be among the most promising services for the broadband Internet of the next generation. A contents delivery network (CDN) that allows effective and scalable content delivery will be required in this role. However, the actual requirements for the CDN, such as quality of service (QoS), the service deployment strategy and technical issues are not yet to be defined. In this paper, the bandwidth requirement of the CDN is derived through QoS evaluation. On the basis of this requirement, we propose two feasible CDN configurations: an IP technology based configuration and an optical video distribution technology based configuration. Finally, we make lists of technical issues for the configurations and discuss some of the possible solutions.