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[Author] Takayuki NAKA(43hit)

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  • EcAgent Architecture Providing Networking Services Based on Loose Communities

    Takayuki NAKAMURA  Michiharu TAKEMOTO  Satoshi TANAKA  

     
    PAPER

      Vol:
    E85-B No:8
      Page(s):
    1455-1462

    For future adaptive networking services, it will be effective if autonomous agents utilize widely spread information that continuously changes. A communication network should provide a framework for agents to utilize information in a large-scale network and should positively support communications among agents. This paper proposes EcAgent (Environment for Communities of Agents). EcAgent provides agents with access to communities that are loose collections of agents. It gathers global information about communications among all agents and makes the agents share it in communities. It makes possible adaptive networking services that use various types of information. We implemented the EcAgent execution environment and some experimental applications to make an adaptive networking service. We also implemented a simulation system to evaluate how accurately the library recognized the embedded relationships as communities. The results of experiments show that the proposed methods for community recognition work efficiently.

  • An MMT-Based Hierarchical Transmission Module for 4K/120fps Temporally Scalable Video

    Yasuhiro MOCHIDA  Takayuki NAKACHI  Takahiro YAMAGUCHI  

     
    PAPER

      Pubricized:
    2020/06/22
      Vol:
    E103-D No:10
      Page(s):
    2059-2066

    High frame rate (HFR) video is attracting strong interest since it is considered as a next step toward providing Ultra-High Definition video service. For instance, the Association of Radio Industries and Businesses (ARIB) standard, the latest broadcasting standard in Japan, defines a 120 fps broadcasting format. The standard stipulates temporally scalable coding and hierarchical transmission by MPEG Media Transport (MMT), in which the base layer and the enhancement layer are transmitted over different paths for flexible distribution. We have developed the first ever MMT transmitter/receiver module for 4K/120fps temporally scalable video. The module is equipped with a newly proposed encapsulation method of temporally scalable bitstreams with correct boundaries. It is also designed to be tolerant to severe network constraints, including packet loss, arrival timing offset, and delay jitter. We conducted a hierarchical transmission experiment for 4K/120fps temporally scalable video. The experiment demonstrated that the MMT module was successfully fabricated and capable of dealing with severe network constraints. Consequently, the module has excellent potential as a means to support HFR video distribution in various network situations.

  • A Waveguide Compatible NRD Guide E-Plane Bandpass Filter for 55 GHz Band OFDM Applications

    Takashi SHIMIZU  Yuki KAWAHARA  Takayuki NAKAGAWA  Tsukasa YONEYAMA  

     
    PAPER-Passive Devices/Circuits

      Vol:
    E90-C No:9
      Page(s):
    1729-1735

    A rectangular waveguide compatible NRD guide E-plane bandpass filter is proposed for 55 GHz band OFDM applications. The NRD guide E-plane bandpass filter is constructed by inserting a metal foil array in the E-plane of NRD guide. Simulation, fabrication, and handling of the filter are not difficult because each resonator is constructed by a couple of metal foils of a simple shape. A Chebyshev response 5-pole bandpass filter with a very narrow bandwidth of 550 MHz is designed and fabricated at 55 GHz band. Simulated and measured filter performances agree well with the design specifications. Insertion loss of the fabricated filter is found to be around 2.0 dB. Although temperature stability of the fabricated filter are found to be within manageable level, the adoption of cyclo olefin polymer can be one of solution for the temperature stability improvement.

  • Large Size In-Cell Capacitive Touch Panel and Force Touch Development for Automotive Displays Open Access

    Naoki TAKADA  Chihiro TANAKA  Toshihiko TANAKA  Yuto KAKINOKI  Takayuki NAKANISHI  Naoshi GOTO  

     
    INVITED PAPER

      Vol:
    E102-C No:11
      Page(s):
    795-801

    We have developed the world's largest 16.7-inch hybrid in-cell touch panel. To realize the large sized in-cell touch panel, we applied a vertical Vcom system and low resistance sensor, which are JDI's original technologies. For glove touch function, we applied mutual bundled driving, which increases the signal intensity higher. The panel also has a low surface reflection, curved-shaped, and non-rectangular characteristics, which are particular requirements in the automotive market. The over 15-inch hybrid in-cell touch panel adheres to automotive quality requirements. We have also developed a force touch panel, which is a new human machine interface (HMI) based on a hybrid in-cell touch panel in automotive display. This study reports on the effect of the improvements on the in-plane variation of force touch and the value change of the force signal under different environment conditions. We also a introduce force touch implemented prototype.

  • Internet Access System with GMPLS Architecture Configured on Wavelength Assignment Photonic Switching System

    Tadahiko YASUI  Takuya KAMINOGOU  Takayuki NAKATA  Hironari MATSUDA  

     
    PAPER-Fiber-Optic Transmission for Communications

      Vol:
    E90-B No:4
      Page(s):
    836-844

    We have successfully applied Generalized Multiprotocol Label Switching (GMPLS) architecture to the Wavelength Assignment Photonic Switching System (WAPS) to create an internet access system that can provide, between terminals, not only conventional best-effort type of IP packet forwarding, but also high-speed and Quality of Service (QoS)-guaranteed IP forwarding. In this paper the system architecture, system specifications, and system hardware/software implementations are described.

  • A 2-D Adaptive Joint-Process Lattice Estimator for Image Restoration

    Takayuki NAKACHI  Katsumi YAMASHITA  Nozomu HAMADA  

     
    PAPER-Digital Signal Processing

      Vol:
    E80-A No:1
      Page(s):
    140-147

    The present paper examines a two-dimensional (2-D) joint-process lattice estimator and its implementation for image restoration. The gradient adaptive lattice (GAL) algorithm is used to update the filter coefficients. The proposed adaptive lattice estimator can represent a wider class of 2-D FIR systems than the conventional 2-D lattice models. Furthermore, its structure possesses orthogonality between the backward prediction errors. These results in superior convergence and tracking properties versus the transversal and other 2-D adaptive lattice estimators. The validity of the proposed model for image restoration is evaluated through computer simulations. In the examples, the implementation of the proposed lattice estimator as 2-D adaptive noise cancellator (ANC) and 2-D adaptive line enhancer (ALE) is considered.

  • Two-Dimensional Least Squares Lattice Algorithm for Linear Prediction

    Takayuki NAKACHI  Katsumi YAMASHITA  Nozomu HAMADA  

     
    LETTER-Digital Signal Processing

      Vol:
    E80-A No:11
      Page(s):
    2325-2329

    In this paper, we propose a two-dimensional (2-D) least-squares lattice (LSL) algorithm for the general case of the autoregressive (AR) model with an asymmetric half-plane (AHP) coefficient support. The resulting LSL algorithm gives both order and space recursions for the 2-D deterministic normal equations. The size and shape of the coefficient support region of the proposed lattice filter can be chosen arbitrarily. Furthermore, the ordering of the support signal can be assigned arbitrarily. Finally, computer simulation for modeling a texture image is demonstrated to confirm the proposed model gives rapid convergence.

  • FOREWORD

    Takayuki NAKACHI  Makoto NAKASHIZUKA  

     
    FOREWORD

      Vol:
    E99-A No:11
      Page(s):
    1907-1908
  • Development of Millimeter-Wave Mobile Camera and Performance Improvement in Outdoor LOS Environment

    Shinichi SUZUKI  Takayuki NAKAGAWA  Tetsuomi IKEDA  

     
    PAPER

      Vol:
    E93-A No:11
      Page(s):
    2099-2107

    The Millimeter-wave Mobile Camera (MiMoCam) developed by NHK STRL uses millimeter-wave band (42 GHz/55 GHz) to transmit Hi-Vision TV picture with high quality and low latency. Multiple-input multiple-output (MIMO) technology which uses a number of antennas at both the transmitter and receiver can be adapted to use to transmit higher quality Hi-Vision TV picture. The camera was intended to be used in a studio environment where there is a high degree of multi-path, however there are also many requests for the MiMoCam to be used outdoor. This will present a different channel statistics where the camera will be operating in a near line-of-sight (LOS) environment without much reflected waves. We have conducted an outdoor transmission test and measured the outdoors transmission performance of the proposed MIMO system to clarify the possibility of using the MiMoCam in outdoor environment. This paper introduces the features of the MiMoCam system and the MIMO transmission technique used in the MiMoCam and presents the findings of this outdoor test. It was also confirmed that channel correlation of the MIMO propagation channels were suppressed by using orthogonally polarized waves and bit error rate (BER) characteristics with respect to the average receiving carrier-to-noise ratio (CNR) was improved. Finally, we could find the feasibility of the MiMoCam outdoor operation from these results.

  • Anti Reflection Films Fabricated by Roll-to-Roll Layer-by-Layer Adsorption Process

    Shiro FUJITA  Koji FUJIMOTO  Takayuki NAKA  Seimei SHIRATORI  

     
    PAPER-Characterization and Abilities of Organic Electronic Devices

      Vol:
    E87-C No:12
      Page(s):
    2064-2070

    Recently, flexible and lightweight optical devices are desired from the practical viewpoint. We demonstrated roll-to-roll type Anti Reflection (AR) film fabricated by layer-by-layer (LBL) adsorption process. When deposition time was 2.5 min and repeating cycle was 8 cycles, refractive index of LBL layer was 1.499 at 632 nm and thickness was 93.1 nm, which are almost the same as those of batch type LBL layer. The minimum reflectance was about 0.6% at 600 nm and transmittance was over 75% at visible region. However as compared with batch type, roll type AR film has lower reflectance and transmittance. This reason is that the flow of solution and rinse and quantity of rinse was smaller, a number of bathes of roll type was lower than that of batch type. Furthermore, comparing the deposition time and film speed, LBL layer was fabricated clearly long deposition time and slow film speed. The roll-to-roll film had a problem of peeling off during the deposition process. By increasing the contact area between film and guided roll, vertical pressure was decrease and friction force was decreased. Furthermore, as rotational speed of guided roll and film speed was decreased, LBL layer was not peeled by friction force between film and guided roll. Because rotational speed of guided rolls and films were almost same in the range of less than about 30 mm/min. There was the problem that polymer complexes were likely to appear on the substrate when the surface was dried during moving between solution and rinse bath. This phenomenon was observed during the roll-to-roll as well as batch process. The quality of roll-to-roll LBL process was depending on deposition time and film speed and drying at moving process critically compared with batch type. It is necessary to design the roll-to-roll machine with care: important points are deposition time and film speed, drying at moving process.

  • Learning State Recognition in Self-Paced E-Learning

    Siyang YU  Kazuaki KONDO  Yuichi NAKAMURA  Takayuki NAKAJIMA  Masatake DANTSUJI  

     
    PAPER-Educational Technology

      Pubricized:
    2016/11/21
      Vol:
    E100-D No:2
      Page(s):
    340-349

    Self-paced e-learning provides much more freedom in time and locale than traditional education as well as diversity of learning contents and learning media and tools. However, its limitations must not be ignored. Lack of information on learners' states is a serious issue that can lead to severe problems, such as low learning efficiency, motivation loss, and even dropping out of e-learning. We have designed a novel e-learning support system that can visually observe learners' non-verbal behaviors and estimate their learning states and that can be easily integrated into practical e-learning environments. Three pairs of internal states closely related to learning performance, concentration-distraction, difficulty-ease, and interest-boredom, were selected as targets of recognition. In addition, we investigated the practical problem of estimating the learning states of a new learner whose characteristics are not known in advance. Experimental results show the potential of our system.

  • Lossless and Near-Lossless Color Image Coding Using Edge Adaptive Quantization

    Takayuki NAKACHI  Tatsuya FUJII  

     
    PAPER-Coding Theory

      Vol:
    E84-A No:4
      Page(s):
    1064-1073

    This paper proposes a unified coding algorithm for the lossless and near-lossless compression of still color images. The proposed unified color image coding scheme can control the Peak Signal-to-Noise Ratio (PSNR) of the reconstructed image while the level of distortion on the RGB plane is suppressed to within a preset magnitude. In order to control the PSNR, the distortion level is adaptively changed at each pixel. An adaptive quantizer to control the distortion is designed on the basis of psychovisual criteria. Finally, experiments on Super High Definition (SHD) images show the effectiveness of the proposed algorithm.

  • A Study on Site Diversity Techniques Related to Rain Area Motion Using Ku-Band Satellite Signals

    Yasuyuki MAEKAWA  Takayuki NAKATANI  Yoshiaki SHIBAGAKI  Takeshi HATSUDA  

     
    PAPER-Propagation

      Vol:
    E91-B No:6
      Page(s):
    1812-1818

    Directions and speeds of the motion of rain areas are estimated for each type of rain fronts, using time differences detected in the rain attenuation of the Ku-band satellite radio wave signals that have been measured at Osaka Electro-Communication University (OECU) in Neyagawa, Osaka, Research Institute of Sustainable Humanosphere (RISH) in Uji, Kyoto, and MU Observatory (MU) of Kyoto University in Shigaraki, Shiga, for the past five years since September 2002. These directions and speeds are shown to agree well with those directly obtained from the motion of rain fronts in the weather charts published by Japan Meteorological Agency. The rain area motion is found to have characteristic directions according to each rain type, such as cold and warm fronts or typhoon. A numerical estimate of the effects of site diversity techniques indicates that between two sites among the three locations (OECU, RISH, MU) separated by 20-50 km, the joint cumulative time percentages of rain attenuation become lower as the two sites are aligned along the directions of rain area motion. In such a case, compared with the ITU-R recommendations, the distance required between the two sites may be, on an average, reduced down to about 60-70% of the conventional predictions.

  • Extended Multiresolution Lossless Video Coding Using In-Band Spatio-Temporal Prediction

    Takayuki NAKACHI  Tomoko SAWABE  Tetsuro FUJII  

     
    PAPER-Image/Vision Processing

      Vol:
    E89-A No:3
      Page(s):
    698-707

    Lossless video coding is required in the fields of archiving and editing digital cinema or digital broadcasting contents. This paper combines a discrete wavelet transform and adaptive inter/intra-frame prediction in the wavelet transform domain to create multiresolution lossless video coding. Based on the image statistics of the wavelet transform domains in successive frames, inter/intra frame adaptive prediction is applied to the appropriate wavelet transform domain. This adaptation offers superior compression performance. A progressive transmission scheme is also proposed for effective resolution scalability. Experiments on test sequences confirm the effectiveness of the proposed algorithm.

  • Two Types of Adaptive Beamformer Using 2-D Joint Process Lattice Estimator

    Tateo YAMAOKA  Takayuki NAKACHI  Nozomu HAMADA  

     
    PAPER-Digital Signal Processing

      Vol:
    E81-A No:1
      Page(s):
    117-122

    This paper presents two types of two-dimensional (2-D) adaptive beamforming algorithm which have high rate of convergence. One is a linearly constrained minimum variance (LCMV) beamforming algorithm which minimizes the average output power of a beamformer, and the other is a generalized sidelobe canceler (GSC) algorithm which generalizes the notion of a linear constraint by using the multiple linear constraints. In both algorithms, we apply a 2-D lattice filter to an adaptive filtering since the 2-D lattice filter provides excellent properties compared to a transversal filter. In order to evaluate the validity of the algorithm, we perform computer simulations. The experimental results show that the algorithm can reject interference signals while maintaining the direction of desired signal, and can improve convergent performance.

  • Block Estimation Method for Two-Dimensional Adaptive Lattice Filter

    InHwan KIM  Takayuki NAKACHI  Nozomu HAMADA  

     
    PAPER-Digital Signal Processing

      Vol:
    E80-A No:4
      Page(s):
    737-744

    In the adaptive lattice estimation process, it is well known that the convergence speed of the successive stage is affected by the estimation errors of reflection coefficients in its preceding stages. In this paper, we propose block estimation methods of two-dimensional (2-D) adaptive lattice filter. The convergence speed of the proposed algorithm is significantly enhanced by improving the adaptive performance of preceding stages. Furthermore, this process can be simply realized. The modeling of 2-D AR field and texture image are demonstrated through computer simulations.

  • Microwave CT Imaging for a Human Forearm at 3GHz

    Takayuki NAKAJIMA  Hiroshi SAWADA  Itsuo YAMAURA  

     
    LETTER

      Vol:
    E78-B No:6
      Page(s):
    874-876

    This paper describes the imaging method for a human forearm in the microwave transmission CT at 3GHz. To improve the spatial resolution, the correction method of the diffraction effects is adopted and the high directivity antennas are used. A cross-sectional image of the human forearm is obtained in vivo.

  • A Study on Non-octave Scalable Image Coding and Its Performance Evaluation Using Digital Cinema Test Material

    Takayuki NAKACHI  Tomoko SAWABE  Junji SUZUKI  Tetsuro FUJII  

     
    PAPER-Image

      Vol:
    E89-A No:9
      Page(s):
    2405-2414

    JPEG2000, an international standard for still image compression, offers 1) high coding performance, 2) unified lossless/lossy compression, and 3) resolution and SNR scalability. Resolution scalability is an especially promising attribute given the popularity of Super High Definition (SHD) images like digital-cinema. Unfortunately, its current implementation of resolution scalability is restricted to powers of two. In this paper, we introduce non-octave scalable coding (NSC) based on the use of filter banks. Two types of non-octave scalable coding are implemented. One is based on a DCT filter bank and the other uses wavelet transform. The latter is compatible with JPEG2000 Part2. By using the proposed algorithm, images with rational scale resolutions can be decoded from a compressed bit stream. Experiments on digital cinema test material show the effectiveness of the proposed algorithm.

  • A Design Method of an Adaptive Multichannel IIR Lattice Predictor for k-Step Ahead Prediction

    Katsumi YAMASHITA  M. H. KAHAI  Takayuki NAKACHI  Hayao MIYAGI  

     
    LETTER-Adaptive Signal Processing

      Vol:
    E76-A No:8
      Page(s):
    1350-1352

    An adaptive multichannel IIR lattice predictor for k-step ahead prediction is constructed and the effectiveness of the proposed predictor is evaluated using digital simulations.

  • Machine Learning-Based Compensation Methods for Weight Matrices of SVD-MIMO Open Access

    Kiminobu MAKINO  Takayuki NAKAGAWA  Naohiko IAI  

     
    PAPER-Antennas and Propagation

      Pubricized:
    2023/07/24
      Vol:
    E106-B No:12
      Page(s):
    1441-1454

    This paper proposes and evaluates machine learning (ML)-based compensation methods for the transmit (Tx) weight matrices of actual singular value decomposition (SVD)-multiple-input and multiple-output (MIMO) transmissions. These methods train ML models and compensate the Tx weight matrices by using a large amount of training data created from statistical distributions. Moreover, this paper proposes simplified channel metrics based on the channel quality of actual SVD-MIMO transmissions to evaluate compensation performance. The optimal parameters are determined from many ML parameters by using the metrics, and the metrics for this determination are evaluated. Finally, a comprehensive computer simulation shows that the optimal parameters improve performance by up to 7.0dB compared with the conventional method.

21-40hit(43hit)