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11641-11660hit(21534hit)

  • A New Two-Phase Approach to Fuzzy Modeling for Nonlinear Function Approximation

    Wooyong CHUNG  Euntai KIM  

     
    PAPER-Computation and Computational Models

      Vol:
    E89-D No:9
      Page(s):
    2473-2483

    Nonlinear modeling of complex irregular systems constitutes the essential part of many control and decision-making systems and fuzzy logic is one of the most effective algorithms to build such a nonlinear model. In this paper, a new approach to fuzzy modeling is proposed. The model considered herein is the well-known Sugeno-type fuzzy system. The fuzzy modeling algorithm suggested in this paper is composed of two phases: coarse tuning and fine tuning. In the first phase (coarse tuning), a successive clustering algorithm with the fuzzy validity measure (SCFVM) is proposed to find the number of the fuzzy rules and an initial fuzzy model. In the second phase (fine tuning), a moving genetic algorithm with partial encoding (MGAPE) is developed and used for optimized tuning of membership functions of the fuzzy model. Two computer simulation examples are provided to evaluate the performance of the proposed modeling approach and compare it with other modeling approaches.

  • A Dynamic Index Allocation Scheme for Data Retrieval and Provision in Peer-to-Peer Networks

    Atsushi ITO  Tomoyuki OHTA  Kouichi MITSUKAWA  Yoshiaki KAKUDA  

     
    PAPER

      Vol:
    E89-B No:9
      Page(s):
    2336-2346

    File-sharing Peer-to-Peer systems are effective for autonomous data retrieval and provision over the networks. However, the early data retrieval schemes such as Gnutella and Local Indices have low performance and large overhead. In order to solve weakness of early schemes, this paper proposes a dynamic scheme for data retrieval and provision, in which indices are adaptively allocated in appropriate nodes to variation of traffic patterns caused by query messages. The simulation experimental results show that the proposed scheme has good performance with reasonable overhead even when the traffic patterns vary as time proceeds.

  • Experimental Investigation of Undersampling for Adjacent Channel Interference Cancellation Scheme

    Anas Muhamad BOSTAMAM  Yukitoshi SANADA  

     
    PAPER-Wireless Communication Technologies

      Vol:
    E89-B No:9
      Page(s):
    2548-2554

    In this paper an adjacent channel interference (ACI) cancellation scheme with undersampling for multi-channel reception is proposed and investigated. Low-IF receiver architecture is used in the multi-channel reception scheme. In this system, signal in the adjacent channel causes interference to the desired signal. The ACI cancellation scheme with analog filter bank has been proposed to mitigate the influence from the adjacent channel [10]. Undersampling technique is applied in this system in order to lower the required sampling frequency and power consumption. The effects of the adjacent channel to the undersampling technique in this scheme is examined and discussed.

  • Individual Cell Equalization for Series Connected Lithium-Ion Batteries

    Yuang-Shung LEE  Ming-Wang CHENG  Shun-Ching YANG  Co-Lin HSU  

     
    PAPER-Energy in Electronics Communications

      Vol:
    E89-B No:9
      Page(s):
    2596-2607

    A systematic approach to the analysis and design of a bi-directional Cuk converter for the cell voltage balancing control of a series-connected lithium-ion battery string is presented in this paper. The proposed individual cell equalizers (ICE) are designed to operate at discontinuous-capacitor-voltage mode (DCVM) to achieve the zero-voltage switching (ZVS) for reducing the switching loss of the bi-directional DC/DC converters. Simulation and experimental results show that the proposed battery equalization scheme can not only enhance the bi-directional battery equalization performance, but also can reduce the switching loss during the equalization period. Two designed examples are demonstrated, the switch power losses are significantly reduced by 52.8% from the MOSFETs and the equalization efficiency can be improved by 68-86.9% using the proposed DCVM ZVS battery equalizer under the specified cell equalization process. The charged/discharged capacity of the lithium-ion battery string is increased by using the proposed ICEs equipped in the battery string.

  • Composite Right/Left-Handed Transmission Lines Based on Conductor-Backed Coplanar Strips

    Rei GOTO  Hiroyuki DEGUCHI  Mikio TSUJI  

     
    PAPER

      Vol:
    E89-C No:9
      Page(s):
    1306-1311

    We propose here a composite right/left handed transmission line constructed by using conductor-backed coplanar strips. In this line, we can easily realize a shunt inductor without via because it has the electric-wall symmetry at the guide center. The left-handed nature is verified by both the finite difference time-domain (FDTD) and the equivalent-circuit calculations. Furthermore, we demonstrate the proposed line can easily satisfy the balanced condition for no band gap between the right-handed and the left-handed modes, and can be applied to a leaky-wave antenna, numerically and experimentally.

  • Parametric Uncertainty Bounds for Stabilizing Receding Horizon H Controls

    ChoonKi AHN  SooHee HAN  WookHyun KWON  

     
    LETTER-Systems and Control

      Vol:
    E89-A No:9
      Page(s):
    2433-2436

    This letter presents parametric uncertainty bounds (PUBs) for stabilizing receding horizon H∞ control (RHHC). The proposed PUBs are obtained easily by solving convex optimization problems represented by linear matrix inequalities (LMIs). We show, by numerical example, that the RHHC can guarantee a H∞ norm bound for a larger class of uncertain systems than conventional infinite horizon H∞ control (IHHC).

  • A Compact C-CMRC Feeding Open-Loop Resonator for Harmonic Rejection Bandpass Filter

    Jianzhong GU  Xiaowei SUN  

     
    LETTER-Microwaves, Millimeter-Waves

      Vol:
    E89-C No:9
      Page(s):
    1365-1367

    A compact open-loop resonator bandpass filter is presented to suppress the spurious passband using compensated compact microstrip resonant cell (C-CMRC) feeding structure. Based on the inherently compact and stopband characteristics of the C-CMRC feeding, the proposed filters shows a better spurious rejection performance than the only open-loop resonator filter. The suppression is -57.4 dB, -49.5 dB, and -43.9 dB at the 2nd, 3rd and 4th harmonic signal separately. All the performance of proposed filters have been verified by the measured results.

  • An Entropy-Based Approach to Protecting Rating Systems from Unfair Testimonies

    Jianshu WENG  Chunyan MIAO  Angela GOH  

     
    PAPER-Contents Technology and Web Information Systems

      Vol:
    E89-D No:9
      Page(s):
    2502-2511

    How to mitigate the influence of unfair testimonies remains an open issue in the research of rating systems. Methods have been proposed to filter the unfair testimonies in order to mitigate the influence of unfair testimonies. However, existing methods depend on assumptions that ratings follow a particular distribution to carry out the testimony filtering. This constrains them in specific rating systems and hinders their applications in other reputation systems. Moreover, existing methods do not scale well with the increase of testimony number due to their iterative nature. In this paper, a novel entropy-based method is proposed to measure the testimony quality, based on which unfair testimonies are further filtered. The proposed method does not require the assumption regarding the rating distribution. Moreover, it scales linearly with the increase of the testimony number. Experimental results show that the proposed method is effective in mitigating the influence of various types of unfair testimonies.

  • Clustering Environment Lights for an Efficient All-Frequency Relighting

    Henry JOHAN  Tomoyuki NISHITA  

     
    PAPER-Computer Graphics

      Vol:
    E89-D No:9
      Page(s):
    2562-2571

    We present a novel precomputed radiance transfer method for efficient relighting under all-frequency environment illumination. Environment illumination is represented as a set of environment lights. Each environment light comprises a direction and an intensity. In a preprocessing step, the environment lights are clustered into several clusters, taking into account only the light directions. By experiment, we confirmed that the environment lights can be clustered into a much smaller number of clusters than their original number. Given any environment illumination, sampled as an environment map, an efficient relighting is then achieved by computing the radiance using the precomputed clusters. The proposed method enables relighting under very high-resolution environment illumination. In addition, unlike previous approaches, the proposed method can efficiently perform relighting when some regions of the given environment illumination change.

  • Temporal Error Concealment Based on Weighted Pixel Estimator

    Tien-Ying KUO  

     
    LETTER-Image Processing and Video Processing

      Vol:
    E89-D No:9
      Page(s):
    2583-2586

    A temporal error concealment algorithm for the block-based video coder has been proposed. The concept of block overlapping is adopted to conceal the erroneous blocks, and the recovered pixels are estimated by the weighted sum from the overlapping. The overlapping weighting matrix has been carefully selected in order to fully exploit the spatial-temporal correlation between boundary blocks and the lost block. Furthermore, the motion vector for the lost block has been recovered by considering the best results for the overlapping. The experimental results are shown by integrating our algorithm into the H.263+ coder.

  • End-to-End Lightpath Establishment Based on Rank Accounting in Multi-Domain WDM Networks

    Takuji TACHIBANA  Hiroaki HARAI  

     
    PAPER-Fiber-Optic Transmission for Communications

      Vol:
    E89-B No:9
      Page(s):
    2448-2456

    In this paper, we propose an end-to-end lightpath establishment method in multi-domain WDM networks. In this method, each domain contracts the provision of wavelength-state information and the number of wavelengths provided to neighbor domains. According to the contract, each source node selects the probed wavelengths, which are the candidates for backward wavelength reservation. In order to select wavelengths that are likely to be idle through the multi-domain network, the source node collects wavelength-state information from each destination node and ranks wavelengths for each destination node for giving priority. The source node selects the wavelengths with higher ranks. We propose two rank accounting methods for this purpose. Through simulation experiments, we show that the proposed rank accounting methods with the above contract provide better performance in terms of blocking probability with conventional methods, especially when intra-domain traffic is low. We present the effective number of contract wavelengths. Further, we also extend these rank accounting methods to methods that aggressively collect wavelength-state information from other destination nodes. We show further improvement of performance by the extended rank accounting methods.

  • A Compact Multi-Layered Wideband Bandpass Filter Exhibiting Left-Handed and Right-Handed Behaviors

    Yasushi HORII  Akira TANAKA  Takefumi HAYASHI  Yukio IIDA  

     
    LETTER

      Vol:
    E89-C No:9
      Page(s):
    1348-1350

    This letter proposes a compact multi-layered bandpass filter exhibiting left-handed and right-handed behaviors in its passband. This filter has a greatly expanded passband from 1.61 GHz to 4.16 GHz (88.4% bandwidth) with a maximum ripple of 1.2 dB and well-suppressed out-of-passbands with transmission zeros at 1.15 GHz and 4.52 GHz. The physical mechanisms are studied with FEM-based full-wave simulations, equivalent circuit analysis and careful experiments.

  • Reduction of Mutual Coupling in a Microstrip Patch Array Fed by a Triplate Waveguide with EBG Elements

    Toru OKAGAKI  Kazuo NAKANO  Yuichi KIMURA  Misao HANEISHI  

     
    LETTER

      Vol:
    E89-C No:9
      Page(s):
    1345-1347

    This letter presents mutual coupling reduction in an E-plane arranged microstrip patch array fed by a triplate waveguide. Five mushroom-like electromagnetic band-gap (EBG) elements arranged in one column are embedded both between two radiating patches and between the feeding lines for suppression of the surface wave and the parallel plate mode, respectively. Validity of the proposed EBG elements is confirmed by the measurement.

  • Linear Complexity of Sequences under Different Interpretations

    Andrew KLAPPER  

     
    INVITED PAPER

      Vol:
    E89-A No:9
      Page(s):
    2254-2257

    In this paper we study relationships between the linear complexities of a sequence when treated as a sequence over two distinct fields. We obtain bounds for one linear complexity in the form of a constant multiple of the other, where the constant depends only on the fields, not on the particular sequence.

  • Peer-to-Peer Non-document Content Searching Method Using User Evaluation of Semantic Vectors

    Yoji YAMATO  Hiroshi SUNAGA  

     
    PAPER

      Vol:
    E89-B No:9
      Page(s):
    2309-2318

    With today's advances in peer-to-peer (P2P) techniques, a lot of non-document content has become searchable and usable. In the near future, since a huge amount of content will be distributed over the networks, not only index server searching but also P2P searching will become important because of its scalability and robustness. Typical P2P content searching services have some problems, such as low search precision ratio, significant increase in traffic and inundations of malicious content such as viruses. We propose a P2P content searching method in which a query is effectively forwarded only to peers that have indices of content semantically similar to the wanted content but not forwarded to the same peer repeatedly. It is based on the ideas of content addressable network (CAN) topology and a vector space method where vectors have a variable length. It maps non-document content to a vector space based on users' evaluations and manages the vector space or routes queries using the CAN topology control. The effectiveness of our method is shown by both analytical estimations and simulation experiments. The simulations clarified that our method is effective at improving the precision and recall ratios while reducing the amount of traffic compared with Gnutella flooding, the vector space method in which vector lengths are fixed (similar to the pSearch method), and Chord. In particular, when there was a lot of malicious content, our method exhibited a higher precision ratio than other methods.

  • Robust Adaptive Array Employing Null Constraint

    Yi CHU  Wei-Yau HORNG  

     
    LETTER-Antennas and Propagation

      Vol:
    E89-B No:9
      Page(s):
    2659-2661

    A deep null algorithm for adaptive narrowband beamforming in the presence of array gain errors is proposed. This new algorithm not only preserves the desired signal, but also yields superior performance. Simulations confirm this new approach.

  • Metamaterial-Based Antennas: Research and Developments

    Richard W. ZIOLKOWSKI  

     
    INVITED PAPER

      Vol:
    E89-C No:9
      Page(s):
    1267-1275

    A brief review of metamaterials and their applications to antenna systems is given. Artificial magnetic conductors and electrically small radiating and scattering systems are emphasized. Single negative, double negative, and zero-index metamaterial systems are discussed as a means to manipulate their size, efficiency, bandwidth, and directivity characteristics.

  • Khatri-Rao Unitary Space-Time Modulation

    Lei WANG  Shihua ZHU  Jun WANG  Yanxing ZENG  

     
    PAPER-Wireless Communication Technologies

      Vol:
    E89-B No:9
      Page(s):
    2530-2536

    Based on the Khatri-Rao matrix product, we propose a novel unitary space-time modulation design called KR-USTM in this paper. Different from existing USTM schemes, such as the systematic approach and space-time frequency-shift keying (ST-FSK), KR-USTM does not require any computer search and can be applied to any number of transmit antennas. Moreover, the special structure of KR-USTM also makes it a high-rate scheme and achieve full antenna diversity as well as lower decoding complexity. Simulation results show that the proposed KR-USTM constellation achieves error performance comparable to existing USTM designs at low rates, while it outperforms them at high rates.

  • Low Complexity Bit-Parallel Squarer for GF(2n) Defined by Irreducible Trinomials

    Sun-Mi PARK  Ku-Young CHANG  

     
    LETTER-Algorithms and Data Structures

      Vol:
    E89-A No:9
      Page(s):
    2451-2452

    We present a bit-parallel squarer for GF(2n) defined by an irreducible trinomial xn +xk +1 using a shifted polynomial basis. The proposed squarer requires TX delay and at most n/2 XOR gates, where TX is the delay of one XOR gate. As a result, the squarer using the shifted polynomial basis is more efficient than one using the polynomial basis except for k=1 or n/2.

  • Capacity Bound of MIMO Systems with MPSK Modulation and Time-Multiplexed Pilots

    Yifei ZHAO  Ming ZHAO  Yunzhou LI  Jing WANG  

     
    LETTER-Wireless Communication Technologies

      Vol:
    E89-B No:9
      Page(s):
    2629-2632

    In this letter, we elucidate the ergodic capacity of multiple-input multiple-output (MIMO) systems with M-ary phase-shift keying (MPSK) modulation and time-multiplexed pilots in frequency-flat Rayleigh fading environment. With linear minimum mean square error (LMMSE) channel estimation, the optimal pilots design is presented. For mathematical tractability, we derive an easy-computing closed-form lower bound of the channel capacity. Based on the lower bound, the optimal power allocation between the data and pilots is also presented in closed-form, and the optimal training length is investigated by numerical optimization. It is shown that the transmit scheme with equal training and data power and optimized training length provides suboptimal performance, and the transmit scheme with optimized training length and training power is optimal. With the latter scheme, in most situations, the optimal training length equals the number of the transmit antennas and the corresponding optimal power allocation can be easily computed with the proposed formula.

11641-11660hit(21534hit)