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11541-11560hit(42807hit)

  • A Data Prefetch and Reuse Strategy for Coarse-Grained Reconfigurable Architectures

    Wei GE  Zhi QI  Yue DU  Lu MA  Longxing SHI  

     
    PAPER-Computer System

      Vol:
    E96-D No:3
      Page(s):
    616-623

    The Coarse Grained Reconfigurable Architectures (CGRAs) are proposed as new choices for enhancing the ability of parallel processing. Data transfer throughput between Reconfigurable Cell Array (RCA) and on-chip local memory is usually the main performance bottleneck of CGRAs. In order to release this stress, we propose a novel data transfer strategy that is called Heuristic Data Prefetch and Reuse (HDPR), for the first time in the case of explicit CGRAs. The HDPR strategy provides not only the flexible data access schedule but also the high data throughput needed to realize fast pipelined implementations of various loop kernels. To improve the data utilization efficiency, a dual-bank cache-like data reuse structure is proposed. Furthermore, a heuristic data prefetch is also introduced to decrease the data access latency. Experimental results demonstrate that when compared with conventional explicit data transfer strategies, our work achieves a significant speedup improvement of, on average, 1.73 times at the expense of only 5.86% increase in area.

  • HEAP-Based Defense Modeling and Simulation Methodology

    Yong-Jun YOU  Sung-Do CHI  Jae-Ick KIM  

     
    PAPER-Information Network

      Vol:
    E96-D No:3
      Page(s):
    655-662

    This paper proposes an agent-based modeling and simulation methodology for analyzing the tactical and operational effectiveness of warfare environment. To do this, we adopt the advanced agent modeling principle, HEAP (Hierarchical Encapsulation and Abstraction Principle), as well as the hierarchical modeling and simulation framework, SES/MB (System Entity Structure/Model Base). Proposed methodology is differentiated from other conventional agent-based defense M&S approaches in that; (i) it supports an intelligent hierarchical multi-agent architecture, (ii) it provides an efficient mechanism for analyzing the strategic and operational effectiveness of warfare environment between multiple platforms. The proposed methodology is successfully applied to the two by two warships warfare simulation for analyzing the tactical effectiveness.

  • An Approximate Flow Betweenness Centrality Measure for Complex Network

    Jia-Rui LIU  Shi-Ze GUO  Zhe-Ming LU  Fa-Xin YU  Hui LI  

     
    LETTER-Information Network

      Vol:
    E96-D No:3
      Page(s):
    727-730

    In complex network analysis, there are various measures to characterize the centrality of each node within a graph, which determines the relative importance of each node. The more centrality a node has in a network, the more significance it has in the spread of infection. As one of the important extensions to shortest-path based betweenness centrality, the flow betweenness centrality is defined as the degree to which each node contributes to the sum of maximum flows between all pairs of nodes. One of the drawbacks of the flow betweenness centrality is that its time complexity is somewhat high. This Letter proposes an approximate method to calculate the flow betweenness centrality and provides experimental results as evidence.

  • Refinement of Landmark Detection and Extraction of Articulator-Free Features for Knowledge-Based Speech Recognition

    Jung-In LEE  Jeung-Yoon CHOI  Hong-Goo KANG  

     
    LETTER-Speech and Hearing

      Vol:
    E96-D No:3
      Page(s):
    746-749

    Refinement methods for landmark detection and extraction of articulator-free features for a knowledge-based speech recognition system are described. Sub-band energy difference profiles are used to detect landmarks, with additional parameters used to improve accuracy. For articulator-free feature extraction, duration, relative energy, and silence detection are additionally used to find [continuant] and [strident] features. Vowel, obstruent and sonorant consonant landmarks, and locations of voicing onsets and offsets are detected within a unified framework with 85% accuracy overall. Additionally, 75% and 79% of [continuant] and [strident] features, respectively, are detected from landmarks.

  • Risk Assessment of a Portfolio Selection Model Based on a Fuzzy Statistical Test

    Pei-Chun LIN  Junzo WATADA  Berlin WU  

     
    PAPER-Fundamentals of Information Systems

      Vol:
    E96-D No:3
      Page(s):
    579-588

    The objective of our research is to build a statistical test that can evaluate different risks of a portfolio selection model with fuzzy data. The central points and radiuses of fuzzy numbers are used to determine the portfolio selection model, and we statistically evaluate the best return by a fuzzy statistical test. Empirical studies are presented to illustrate the risk evaluation of the portfolio selection model with interval values. We conclude that the fuzzy statistical test enables us to evaluate a stable expected return and low risk investment with different choices for k, which indicates the risk level. The results of numerical examples show that our method is suitable for short-term investments.

  • Low-Complexity Soft-ML Detection Algorithm for Modified-DCM in WiMedia UWB Systems

    Kilhwan KIM  Jangyong PARK  Jihun KOO  Yongsuk KIM  Jaeseok KIM  

     
    LETTER-Wireless Communication Technologies

      Vol:
    E96-B No:3
      Page(s):
    910-913

    This letter proposes a low-complexity soft-detection algorithm for modified dual-carrier modulation (MDCM) in WiMedia ultra-wideband (UWB) systems. In order to reduce the complexity of soft-output maximum-likelihood detection (soft-MLD), which gives the optimal performance for MDCM symbols, the proposed algorithm utilizes the following three methods: real/imaginary separation, multiplierless distance calculation, and candidate set reduction. Through these methods, the proposed algorithm reduces the complexity of soft-MLD by 97%, while preventing the deterioration of its optimality. The performance of the proposed algorithm is demonstrated by simulations of 640–1024 Mbps transmission modes of the latest Release 1.5 standard of the WiMedia UWB.

  • High-Tc Superconducting Electronic Devices Based on YBCO Step-Edge Grain Boundary Junctions Open Access

    Shane T. KEENAN  Jia DU  Emma E. MITCHELL  Simon K. H. LAM  John C. MACFARLANE  Chris J. LEWIS  Keith E. LESLIE  Cathy P. FOLEY  

     
    INVITED PAPER

      Vol:
    E96-C No:3
      Page(s):
    298-306

    We outline a number of high temperature superconducting Josephson junction-based devices including superconducting quantum interference devices (SQUIDs) developed for a wide range of applications including geophysical exploration, magnetic anomaly detection, terahertz (THz) imaging and microwave communications. All these devices are based on our patented technology for fabricating YBCO step-edge junction on MgO substrates. A key feature to the successful application of devices based on this technology is good stability, long term reliability, low noise and inherent flexibility of locating junctions anywhere on a substrate.

  • Novel Superconducting Quantum Interference Device Bootstrap Circuit and Its Application in Biomagnetism Open Access

    Xiangyan KONG  Yi ZHANG  Xiaoming XIE  Mianheng JIANG  

     
    INVITED PAPER

      Vol:
    E96-C No:3
      Page(s):
    320-325

    The voltage biased SQUID Bootstrap Circuit (SBC) was recently demonstrated for direct readout of SQUID signals. The SBC combines current- and voltage-feedbacks in one circuit to suppress the preamplifier noise. It offers not only a good noise performance, but also wide tolerance of SQUID parameters. Using SBC gradiometer, the bio-magnetic signals were successfully measured. In this paper, we overview the concept of SBC and its applications.

  • Investigation of Interfacial Charging Process of Pentacene/C60/BCP Triple-Layer Organic Solar Cells

    Xiangyu CHEN  Dai TAGUCHI  Takaaki MANAKA  Mitsumasa IWAMOTO  

     
    PAPER

      Vol:
    E96-C No:3
      Page(s):
    358-361

    By using electric-field-induced optical second-harmonic generation (EFISHG) measurement, we investigated interfacial carrier behavior in organic solar cells (OSCs) with a blocking layer of bathocuproine (BCP). Results evidently showed that the Maxwell-Wagner type excess charges accumulate on both pentacene/C60 and C60/BCP interfaces. Also, the measurement under short-circuit and open-circuit conditions clearly showed the different photo-induced carrier behaviors in the OSCs devices. Our work proved that the dielectric nature of OSCs dominates the operation of our OSCs and the EFISHG technique is very effective to characterize the dielectric performance of the OSCs.

  • Effect of Photoreactive SAM at the Interface of an Indium-Tin Oxide Electrode and a Polymer Hole Transport Layer

    Seong-Ho KIM  Hanae OHTSUKA  Rigoberto C. ADVINCULA  Kuniaki TANAKA  Hiroaki USUI  

     
    BRIEF PAPER

      Vol:
    E96-C No:3
      Page(s):
    365-368

    A self-assembled monolayer having a benzophenone unit as a photoreactive terminal group (BP-SAM) was prepared on an indium-tin oxide (ITO) electrode, on which a hole-transport layer of a phenoxazine-dioctylfluorene copolymer (H5) was spin-coated and irradiated with UV light. After washing the physisorbed H5 molecules, contact angle measurement and ellipsometry showed that the H5 molecules can be tethered to the ITO surface via the BP-SAM. Organic light-emitting diodes (OLEDs) were prepared in the structure of ITO/H5 hole transport layer/tris(8-hydroxyquinolato) aluminum/bathocuproin/LiF/Al electrode with and without the BP-SAM layer on the surface of ITO. The device with the BP-SAM showed higher current density and higher luminance due to the improvement of contact at the ITO/H5 interface by forming covalent bonds via the BP-SAM.

  • Enhanced Photocurrent Properties of Dye/Au-Loaded TiO2 Films by Grating-Coupled Surface Plasmon Excitation

    Hathaithip NINSONTI  Weerasak CHOMKITICHAI  Akira BABA  Wiyong KANGWANSUPAMONKON  Sukon PHANICHPHANT  Kazunari SHINBO  Keizo KATO  Futao KANEKO  

     
    BRIEF PAPER

      Vol:
    E96-C No:3
      Page(s):
    385-388

    We report enhanced photocurrent properties of dye/Au-loaded titanium dioxide (TiO2) films on Au gratings. Au-loaded TiO2 nanopowders were first synthesized by a modified sol-gel method and then prepared by the impregnation method. We also fabricated dye-sensitized solar cells, which were composed of Au grating/Au-TiO2/TMPyP-SCC LbL (20 bilayers)/electrolyte/ITO substrates. Short-circuit photo-current measurements showed that Au-loaded TiO2 with grating-coupled surface plasmon excitation can enhance the short-circuit photocurrentof the fabricated cells.

  • Electrostatic Control of Artificial Cell Membrane Spreading by Tuning the Thickness of an Electric Double Layer in a Nanogap

    Yoshiaki KASHIMURA  Kazuaki FURUKAWA  Keiichi TORIMITSU  

     
    PAPER

      Vol:
    E96-C No:3
      Page(s):
    344-347

    When we apply a voltage to a supported lipid bilayer self-spreading through a nanometer-scale gap (nanogap), the effects can be divided into two types. One is that there is no voltage-dependent change in the self-spreading behavior. Namely, the lipid bilayer passes through a nanogap without any stagnation. The other reveals that the self-spreading of a lipid bilayer can be controlled by an electric field modulation between nanogap electrodes. As a mechanism for these phenomena, we have proposed an electrostatic trapping model, in which the relationship between the thickness of an electric double layer and the nanogap spacing plays a crucial role. Here, to confirm the validity of this mechanism, we investigated the ionic concentration dependence of an electrolyte solution on the self-spreading behavior, which enabled us to tune the thickness of the electric double layer precisely. The result exhibited a certain threshold for controlling the self-spreading behavior. We also approximated the electric potential in the nanogap by using the Debye-Huckel equation. Our calculation result was in good agreement with the ionic concentration dependence experiments, suggesting the validity of our proposed mechanism. The results described in this work provide useful information regarding the realization of nanobio devices and the fundamental study of nanoelectronics.

  • In situ Observation of Electron Transfer Kinetics of Cytochrome c Adsorbed on ITO Electrode with Applying Pulse Potential Step with Slab Optical Waveguide Spectroscopy

    Naoki MATSUDA  Hirotaka OKABE  

     
    BRIEF PAPER

      Vol:
    E96-C No:3
      Page(s):
    389-392

    In situ UV-vis. absorption spectra of cytochrome c adsorbed on ITO electrode was observed with slab optical waveguide spectroscopy combining pulse potential step (PPS) between 0.3 and -0.45 V vs. Ag/AgCl. The amount of cytochrome c adsorbed on ITO electrode was estimated from the amount of coulomb of the peaks in cyclic voltammogram to be about a monolayer coverage in this experimental condition. Spectral change between oxidized and reduced cytochrome c by PPS was finished in about 20 msec with phosphate buffer solution. The results strongly proved that SOWG spectroscopy should be effective for in situ observation of ET reaction kinetics of surface adsorbed molecules.

  • Low Voltage Pulse Application to Biological Cells

    Hidenori OTSUKA  Saya OKIMURA  Masako NAGAMURA  Daisuke MATSUKUMA  Koichi KUTSUZAWA  Naoki MATSUDA  Hirotaka OKABE  

     
    PAPER

      Vol:
    E96-C No:3
      Page(s):
    348-352

    As an application of low electric field to biomedical engineering, this paper attempts to study the dose-effect of biological effects caused by msPEF with experiments on HeLa cells. MTT assay was used to trace the cell electroporation and examine cell viability. It is observed that with the increasing electric field intensity and pulse numbers, IRE effects will occur successively.

  • Digital Ink Search Based on Character-Recognition Candidates Compared with Feature-Matching-Based Approach

    Cheng CHENG  Bilan ZHU  Masaki NAKAGAWA  

     
    PAPER-Pattern Recognition

      Vol:
    E96-D No:3
      Page(s):
    681-689

    This paper presents an approach based on character recognition to searching for keywords in on-line handwritten Japanese text. It employs an on-line character classifier and an off-line classifier or a combined classifier, which produce recognition candidates, and it searches for keywords in the lattice of candidates. It integrates scores to individually recognize characters and their geometric context. We use quadratic discriminant function(QDF) or support vector machines(SVM) models to evaluate the geometric features of individual characters and the relationships between characters. This paper also presents an approach based on feature matching that employs on-line or off-line features. We evaluate three recognition-based methods, two feature-matching-based methods, as well as ideal cases of the latter and concluded that the approach based on character recognition outperformed that based on feature matching.

  • On the Length-Decreasing Self-Reducibility and the Many-One-Like Reducibilities for Partial Multivalued Functions

    Ji-Won HUH  Shuji ISOBE  Eisuke KOIZUMI  Hiroki SHIZUYA  

     
    PAPER

      Vol:
    E96-D No:3
      Page(s):
    465-471

    In this paper, we investigate a relationship between the length-decreasing self-reducibility and the many-one-like reducibilities for partial multivalued functions. We show that if any parsimonious (many-one or metric many-one) complete function for NPMV (or NPMVg) is length-decreasing self-reducible, then any function in NPMV (or NPMVg) has a polynomial-time computable refinement. This result implies that there exists an NPMV (or NPMVg)-complete function which is not length-decreasing self-reducible unless P = NP.

  • Online Vertex Exploration Problems in a Simple Polygon

    Yuya HIGASHIKAWA  Naoki KATOH  

     
    PAPER

      Vol:
    E96-D No:3
      Page(s):
    489-497

    This paper considers online vertex exploration problems in a simple polygon where starting from a point in the inside of a simple polygon, a searcher is required to explore a simple polygon to visit all its vertices and finally return to the initial position as quickly as possible. The information of the polygon is given online. As the exploration proceeds, the searcher gains more information of the polygon. We give a 1.219-competitive algorithm for this problem. We also study the case of a rectilinear simple polygon, and give a 1.167-competitive algorithm.

  • Better Approximation Algorithms for Grasp-and-Delivery Robot Routing Problems

    Aleksandar SHURBEVSKI  Hiroshi NAGAMOCHI  Yoshiyuki KARUNO  

     
    PAPER

      Vol:
    E96-D No:3
      Page(s):
    450-456

    In this paper, we consider a problem of simultaneously optimizing a sequence of graphs and a route which exhaustively visits the vertices from each pair of successive graphs in the sequence. This type of problem arises from repetitive routing of grasp-and-delivery robots used in the production of printed circuit boards. The problem is formulated as follows. We are given a metric graph G*=(V*,E*), a set of m+1 disjoint subsets Ci ⊆ V* of vertices with |Ci|=n, i=0,1,...,m, and a starting vertex s ∈ C0. We seek to find a sequence π=(Ci1, Ci2, ..., Cim) of the subsets of vertices and a shortest walk P which visits all (m+1)n vertices in G* in such a way that after starting from s, the walk alternately visits the vertices in Cik-1 and Cik, for k=1,2,...,m (i0=0). Thus, P is a walk with m(2n-1) edges obtained by concatenating m alternating Hamiltonian paths between Cik-1 and Cik, k=1,2,...,m. In this paper, we show that an approximate sequence of subsets of vertices and an approximate walk with at most three times the optimal route length can be found in polynomial time.

  • On the Study of a Novel Decision Feedback Equalizer with Block Delay Detection for Joint Transceiver Optimization

    Chun-Hsien WU  

     
    PAPER-Transmission Systems and Transmission Equipment for Communications

      Vol:
    E96-B No:3
      Page(s):
    737-748

    This paper presents a novel decision feedback equalizer (DFE) with block delay detection for the joint transceiver design that uses channel state information (CSI). The block delay detection in the proposed DFE offers a degree of freedom for optimizing the precoder of the transmitter, provided the transmission power is constrained. In the proposed DFE, the feedforward matrix is devised to enable a block-based equalizer that can be cooperated with an intrablock decision feedback equalizer for suppressing the intersymbol interference (ISI) for the transmitted block with a certain block delay. In this design, the interblock interference (IBI) for the delay block is eliminated in advance by applying the recently developed oblique projection framework to the implementation of the feedforward matrix. With knowledge of full CSI, the block delay and the associated block-based precoder are jointly designed such that the average bit-error-rate (BER) is minimized, subject to the transmission power constraint. Separate algorithms are derived for directly determining the BER-minimized block delays for intrablock minimum mean-squared error (MMSE) and zero-forcing (ZF) equalization criteria. Theoretical derivations indicate that the proposed MMSE design simultaneously maximize the Gaussian mutual information of a transceiver, even under the cases of existing IBI. Simulation results validate the proposed DFE for devising an optimum transceiver with CSI, and show the superior BER performance of the optimized transceiver using proposed DFE. Relying on analytic results and simulation cases also builds a sub-optimum MMSE design of the proposed DFE using the BER-minimized block delay for ZF criterion, which exhibits almost identical BER performance as the proposed MMSE design in most of the signal-to-noise ratio (SNR) range.

  • Magnetospinography: Instruments and Application to Functional Imaging of Spinal Cords

    Yoshiaki ADACHI  Daisuke OYAMA  Shigenori KAWABATA  Kensuke SEKIHARA  Yasuhiro HARUTA  Gen UEHARA  

     
    PAPER

      Vol:
    E96-C No:3
      Page(s):
    326-333

    Magnetospinography (MSG) is one of the most promising techniques to detect the nerve activity of spinal cords thanks to its noninvasiveness and high spatial/temporal resolutions. Multichannel superconducting quantum interference device (SQUID) MSG measurement systems optimized for supine subjects have been developed previously and employed in clinical applications in hospitals. Magnetic source analyses of MSG data based on spatial filter techniques reveal the transition of reconstructed current distributions adjacent to the spinal cord. The propagation of the neural signals was noninvasively visualized. The MSG measurements provide significant diagnostic information such as irregularities in the transitions of the reconstructed current distribution and/or considerable decreases in the current intensity at the lesion. Such functional imaging of the spinal cord in addition to conventional neurologic examinations and morphological imaging will be fairly effective in presurgical lesion localizations of the spinal cord.

11541-11560hit(42807hit)