The search functionality is under construction.
The search functionality is under construction.

Keyword Search Result

[Keyword] Al(20498hit)

12061-12080hit(20498hit)

  • Applying Logic of Multiple-Valued Argumentation to Eastern Arguments

    Hajime SAWAMURA  Takehisa TAKAHASHI  

     
    PAPER

      Vol:
    E88-D No:9
      Page(s):
    2021-2030

    In our former paper, we formalized a Logic of Multiple-valued Argumentation (LMA) on an expressive knowledge representation language, Extended Annotated Logic Programming (EALP), in order to make it possible to construct arguments under uncertain information. In this paper, We confirm expressivity and applicability by applying LMA to arguments reflecting Easterners' preference over argumentation as well as Eastern thought and philosophy. In doing so, we exploit a wide variety of complete lattices as truth-values, showing the flexibility and adaptability of LMA to various multiple-valuedness required in argumentation under uncertain information. In particular, we consider a significant specialization of LMA to Tetralemma with an Eastern mind. Through various argument examples, it is shown that LMA allows for a kind of pluralistic argumentation, or a fusion of Eastern and Western argumentation.

  • Estimation of Direction of Arrival Using Weighted Subspace Fitting for Wireless Communications

    Suk Chan KIM  Iickho SONG  

     
    PAPER-Wireless Communication Technologies

      Vol:
    E88-B No:9
      Page(s):
    3717-3724

    Estimation of unknown signal parameters with sensor array measurements has been investigated quite extensively. Also, there has been in recent years an explosive increase in the number of mobile users in wireless cellular systems, thus contributing to growing levels of multi-user interference. To overcome this problem, application of adaptive antenna array techniques to further increase the channel capacity has been discussed. In this paper, a new model of locally scattered signals in the vicinity of mobiles is proposed by defining the mean steering vector and manipulate it mathematically for several distributions. Under this model an estimation method of the direction of arrival is investigated based on a weighted subspace fitting technique. Statistical analysis and simulations are also considered.

  • A New Approach to Cell Loss Analysis for Long-Range Dependent Network Traffic

    Chien Trinh NGUYEN  Shinji SUGAWARA  Tetsuya MIKI  

     
    PAPER-Network

      Vol:
    E88-B No:9
      Page(s):
    3668-3681

    A new expression for cell/packet loss probability in an ATM and packet switched queue system with a finite buffer is presented. Cell and packet loss analysis is based on the new concept of a "buffer overflow cluster" and the overflow probability for a queue with an infinite buffer. This approach holds for a wide variety of long-range dependent traffic sources typical of wide-area networks, as well as Internet and other communication traffics. The method is verified by simulations of two long-range dependent traffic scenarios: fractional Gaussian noise and multifractal wavelet model traffic with a beta marginal distribution.

  • An Explicit Stability Criterion of Adaptive Virtual Queue Algorithm

    Fengyuan REN  Chuang LIN  Xiaomeng HUANG  

     
    LETTER-Network

      Vol:
    E88-B No:9
      Page(s):
    3768-3771

    Adaptive Virtual Queue (AVQ) introduces a novel implementation algorithm for Active Queue Management (AQM). The stability criterion for AVQ was deduced in literature [1], but it lacks practicability due to the difficulty of solving the transcendental equation. In this letter, the AVQ stability is further investigated based on the characteristic roots of delay-differential equation. Another stability criterion explicitly associated with parameters of network configuration is deduced and the upper bound of delay time for stable AVQ algorithm is determined. Finally, the conclusion is validated through simulation experiments.

  • The Roles of Phase Transition in Multi-Agent Performance Regulation

    Kouji HARADA  Tetuo KINOSHITA  

     
    PAPER

      Vol:
    E88-D No:9
      Page(s):
    2039-2046

    The resource allocation problem in multi-agent systems is one of the crucial problems hindering the development of multi-agent technologies. This study demonstrates that "time delay" functions as an effective factor in a resource allocation, contrasting to the conventional real-time oriented multi-agent paradigm by 1) introducing a "fickle" agent, whose own strategy fluctuates randomly, and 2) an agent repository mechanism. This study also demonstrates that in the resource allocation process, time delay induces dramatic changes in performance, the specific phenomenon is the so-called "phase transition phenomenon". This finding means emergence of the phase transition is cited as a major factor governing multi-agent system performance. This knowledge is of essential importance in the regulation in multi-agent performance.

  • Transmit Power Efficiency of Multi-Hop MRC Diversity for a Virtual Cellular Network

    Imane DAOU  Eisuke KUDOH  Fumiyuki ADACHI  

     
    LETTER

      Vol:
    E88-B No:9
      Page(s):
    3643-3648

    In virtual cellular network (VCN), proposed for high-speed packet mobile communications, the signal transmitted from a mobile terminal is received by wireless ports distributed in each virtual cell and relayed to the central port that acts as a gateway to the core network. In this letter, we apply the multi-hop maximal ratio combining (MHMRC) diversity and propose the route modification algorithm in order to improve transmit power efficiency degradation caused by the carrier frequency difference between the control and the data communication channels for VCN. The transmit power efficiency and the distribution of the number of hops are evaluated by computer simulation for a VCN.

  • Load Balancing Routing Algorithm for Reverse Proxy Servers

    Satosi KATO  Hidetosi OKAMOTO  Toyofumi TAKENAKA  

     
    PAPER-Internet

      Vol:
    E88-B No:9
      Page(s):
    3693-3700

    We propose a novel routing algorithm for reverse proxy servers, called load balancing content address hashing (LB-CAH), and evaluate the performance of the proposed routing algorithm compared with that of the content address hashing (CAH) and the hash and slide (HAS) routing algorithms. The proposed LB-CAH routing algorithm calculates the popularity of pages in the load balancer using an LFU caching technique and periodically makes a popularity list. Using this popularity list, the proposed routing algorithm selects a reverse proxy server as follows. When the requested page appears in the popularity list, the request is routed according to the round robin method; otherwise, it is routed according to the content address hashing method. We evaluate and compare the LB-CAH, CAH and HAS routing algorithms by simulation experiments from the viewpoints of load balancing, consumed cache space and cache hit rate. Simulation experiments show that the proposed LB-CAH routing algorithm achieves almost the same degree of load balancing as the HAS algorithm and the same cache hit rate as the CAH algorithm for reverse proxy servers in various web site environments.

  • Phase Error Correction for OFDM-Based WLANs

    Zi-Wei ZHENG  Zhi-Xing YANG  Yi-Sheng ZHU  

     
    LETTER-Network

      Vol:
    E88-B No:9
      Page(s):
    3776-3778

    A novel phase error correction scheme is proposed for the high rate OFDM-based wireless local area networks (WLANs). The proposed scheme makes the system capable of efficiently compensating the whole phase error due to the residual sampling clock offset and frequency offset estimation error after timing and frequency offset compensation, as well as the phase noise.

  • On the Optimal Chip Rate of Adaptive Power and Rate DS/CDMA Communication Systems in Nakagami Fading Channels

    Ye Hoon LEE  Dong Ho KIM  Hong Jik KIM  

     
    LETTER-Wireless Communication Technologies

      Vol:
    E88-B No:9
      Page(s):
    3798-3801

    We investigate the optimal chip rate of power or rate adapted direct-sequence code division multiple access (DS/CDMA) communication systems in Nakagami fading channels. We find that the optimal chip rate that maximizes the spectral efficiency depends upon both the channel parameters, such as multipath intensity profile (MIP) and line-of-sight (LOS) component, and the adaptation scheme itself. With the rate adaptation, the optimal chip rate is less than 1/Tm irrespective of the channel parameters, where Tm is multipath delay spread. This indicates that with the rate adaptation, correlation receiver achieves higher spectral efficiency than RAKE receiver. With the power adaptation, however, the optimal chip rate and the corresponding number of tabs in RAKE receiver are sensitive to MIP and LOS component.

  • A Simple Nonautonomous Chaotic Spiking Circuit with a Refractory Threshold

    Yoshifumi KOBAYASHI  Hidehiro NAKANO  Toshimichi SAITO  

     
    LETTER-Nonlinear Problems

      Vol:
    E88-A No:9
      Page(s):
    2464-2467

    This letter studies a simple nonautonomous chaotic circuit constructed by adding an impulsive switch to the RCL circuit. The switch operation depends on time and on state variable through a refractory threshold. The circuit exhibits various chaotic attractors, periodic attractors and related bifurcation phenomena. The dynamics can be analyzed using 1-D return map focusing on the time-dependent switching moments. Using a simple test circuit model typical phenomena are verified in PSPICE simulations.

  • TMTR Codes for Partial Response Channels

    Hui-Feng TSAI  Pi-Hai LIU  Yinyi LIN  

     
    LETTER-Storage Technology

      Vol:
    E88-C No:9
      Page(s):
    1903-1908

    A TMTR code is specified as (=2,=3,k) constraint. In this work, an approach for constructing (=2,=3,k) codes is presented. Based on this construction, a rate 8/9 code with k=7 is found. This code can achieve better timing recovery performance compared to the proposed previously TMTR code with k=11. An enumerating encoder and decoder exist for constructed (=2,=3,k) codes. A look-up table for the encoder/decoder is not required. Simulation results on an E2PRIV recording channel reveal that the TMTR code provides 2.2 dB gain over an uncoded case.

  • Blind Separation and Deconvolution for Convolutive Mixture of Speech Combining SIMO-Model-Based ICA and Multichannel Inverse Filtering

    Hiroshi SARUWATARI  Hiroaki YAMAJO  Tomoya TAKATANI  Tsuyoki NISHIKAWA  Kiyohiro SHIKANO  

     
    PAPER-Engineering Acoustics

      Vol:
    E88-A No:9
      Page(s):
    2387-2400

    We propose a new two-stage blind separation and deconvolution strategy for multiple-input multiple-output (MIMO)-FIR systems driven by colored sound sources, in which single-input multiple-output (SIMO)-model-based ICA (SIMO-ICA) and blind multichannel inverse filtering are combined. SIMO-ICA can separate the mixed signals, not into monaural source signals but into SIMO-model-based signals from independent sources as they are at the microphones. After the separation by the SIMO-ICA, a blind deconvolution technique for the SIMO model can be applied even when each source signal is temporally correlated and the mixing system has a nonminimum phase property. The simulation results reveal that the proposed algorithm can successfully achieve separation and deconvolution of a convolutive mixture of speech, and outperforms a number of conventional ICA-based BSD methods.

  • Optical Manipulation of Nano Materials under Quantum Mechanical Resonance Conditions

    Takuya IIDA  Hajime ISHIHARA  

     
    PAPER

      Vol:
    E88-C No:9
      Page(s):
    1809-1816

    We make a theoretical study about the laser-induced radiation force exerted on nano materials under a quantum mechanical resonance condition of electronic systems [1] confined in them. In our recent study, we have clarified that the remarkable effects of the electronic resonance appear in the radiation force on the small object whose size is much smaller than the light wavelength; (A) the acceleration on the object gets larger as the size decreases, (B) the peaks with less heat appear in the force spectra even under the resonance condition, (C) the peak position sensitively varies with the nanoscale-size changes. These are useful for the optical manipulation to precisely control the mechanical motions of nano materials. In this paper, toward the experiment to verify the above results, we discuss the dependence of the mechanical motion of nano objects on the width of the incident laser light, and on the diffusion and friction effects assuming that they are floating in the superfluid helium-4 with the cryogenic condition where the electronic resonance effects become conspicuous. The results of calculations show that the particular nano objects, whose resonance energy corresponds to the center frequency of incident laser, can move away from others over macroscopic distance beyond diffusion length. This means that we can observe the distribution of sizes and qualities of nano objects as a macroscopic spatial distribution of them if we prepare appropriate conditions of incident light. We call this new technique 'Nano Optical Chromatography (NOC).'

  • Nanophotonic Computing Based on Optical Near-Field Interactions between Quantum Dots

    Makoto NARUSE  Tetsuya MIYAZAKI  Tadashi KAWAZOE  Suguru SANGU  Kiyoshi KOBAYASHI  Fumito KUBOTA  Motoichi OHTSU  

     
    PAPER

      Vol:
    E88-C No:9
      Page(s):
    1817-1823

    We approach nanophotonic computing on the basis of optical near-field interactions between quantum dots. A table lookup, or matrix-vector multiplication, architecture is proposed. As fundamental functionality, a data summation mechanism and digital-to-analog conversion are experimentally demonstrated using CuCl quantum dots. Owing to the diffraction-limit-free nature of nanophotonics, these architectures can achieve ultrahigh density integration compared to conventional bulky optical systems, as well as low power dissipation.

  • Traffic Sign Classification Using Ring Partitioned Method

    Aryuanto SOETEDJO  Koichi YAMADA  

     
    PAPER-Intelligent Transport System

      Vol:
    E88-A No:9
      Page(s):
    2419-2426

    Traffic sign recognition usually consists of two stages: detection and classification. In this paper, we describe the classification stage using the ring-partitioned method. The proposed method uses a specified grayscale image in the pre-processing step and ring-partitioned matching in the matching step. The method does not need carefully prepared many samples of traffic sign images for the training process, alternatively only the standard traffic signs are used as the reference images. The experimental results show the effectiveness of the method in the matching of occluded, rotated, and illumination problems of the traffic sign images with the fast computation time.

  • Efficient Packet Distribution Scheme in Cluster-Based Active Router

    YoungBae JANG  SeungRyoul MAENG  JungWan CHO  

     
    LETTER-Computer Systems

      Vol:
    E88-D No:9
      Page(s):
    2201-2204

    An active network has the advantage of being able to accept new protocols quickly and easily. The cluster-based active router can provide sufficient computing power for customized computations. In the router architecture, load balancing is achieved by the efficient distribution of packets. We present a packet distribution scheme according to estimated processing time.

  • Size-Adjustable Visual Secret Sharing Schemes

    Ching-Nung YANG  Tse-Shih CHEN  

     
    LETTER-Information Security

      Vol:
    E88-A No:9
      Page(s):
    2471-2474

    Visual secret sharing (VSS) scheme is a perfect secure method that protects a secret image by breaking it into shadows. Unlike other secret sharing schemes, the VSS scheme can be easily decoded by the human visual sight when staking the shadows. We replace a pixel in the secret image by m sub pixels in the shadow image and the value m is called as pixel expansion. In general, most papers are dedicated to find the minimum m for a VSS scheme, i.e. a smaller shadow size. However, it seems that no one studies how to trade the shadow size for the contrast. In this paper, we take the lead in studying size-adjustable VSS schemes such that one can choose appropriate shadow size and the recovered image contrast for practical use.

  • Observation of Faraday Rotation and Magnetic Circular Dichroism in an Optical Near-Field Probe Coated with Fe

    Tadashi KAWAZOE  Shinya MARUYAMA  Kiyoshi KOBAYASHI  Motoichi OHTSU  

     
    LETTER

      Vol:
    E88-C No:9
      Page(s):
    1850-1852

    We demonstrate a novel fiber device exhibiting magnetic circular dichroism (MCD) and Faraday rotation in sharpened optical fibers coated with Fe. The degree of MCD was 0.68 in a magnetic field of 0.35 T and the Faraday rotation angle was as great as 110 degrees. Such great magneto-optical effect is due to optical near-field interactions in the sub-wavelength region, i.e., in the tip of the near-field fiber probe. These effects can be attributed to the large magnitude of the magneto optical coefficient of Fe.

  • A Novel Approach for Modeling a Hybrid ARQ (Automatic Repeat Request) Based on the Hidden Markov Model

    Yong Ho KIM  Tae Yong KIM  Young Yong KIM  

     
    LETTER-Network

      Vol:
    E88-B No:9
      Page(s):
    3772-3775

    In this letter, we propose a novel approach for use in the analytical modeling of the overall performance of a Hybrid ARQ (type I and II) together with arbitrary channel model, based on Hidden Markov Model (HMM). Using the combined HMM model developed for involved ARQ protocols with the finite state channel model, such critical performance measure as throughput and delay can be derived in closed form. Analytical results are derived for Stop-and-Wait as well as Go-back-N type together with the type I and type II Hybrid ARQ scheme adopted. We compare the analytical results along with the simulation results in order to check the correctness our model, and show the efficiency of our approach by applying it to realistic environments such as the CDMA IS-95 system with its derived equations.

  • High Rate Recursive Space-Time Trellis Code Designed for Serially Concatenated Space-Time Codes

    Ying LI  Xudong GUO  Xinmei WANG  

     
    LETTER-Wireless Communication Technologies

      Vol:
    E88-B No:9
      Page(s):
    3791-3793

    Using several high rate recursive convolutional codes as the basic element and the trace criteria as the designing principle, a new kind of recursive space-time trellis code with more flexible and higher data rate is presented for the serially concatenated space-time code. When 2b-ary modulation and N transmit antennas are used, the data rate of the new code can be arranged from b bps/Hz to Nb-1bps/Hz by modifying the number of recursive convolutional codes and the data rate of each code.

12061-12080hit(20498hit)