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  • A Flexible Wireless Sensor Patch for Real-Time Monitoring of Heart Rate and Body Temperature

    Seok-Oh YUN  Jung Hoon LEE  Jin LEE  Choul-Young KIM  

     
    LETTER-Biological Engineering

      Pubricized:
    2019/02/18
      Vol:
    E102-D No:5
      Page(s):
    1115-1118

    Real-time monitoring of heart rate (HR) and body temperature (BT) is crucial for the prognosis and the diagnosis of cardiovascular disease and healthcare. Since current monitoring systems are too rigid and bulky, it is not easy to attach them to the human body. Also, their large current consumption limits the working time. In this paper, we develop a wireless sensor patch for HR and BT by integrating sensor chip, wireless communication chip, and electrodes on the flexible boards that is covered with non-toxic, but skin-friendly adhesive patch. Our experimental results reveal that the flexible wireless sensor patch can efficiently detect early diseases by monitoring the HR and BT in real time.

  • An Optimized Level Set Method Based on QPSO and Fuzzy Clustering

    Ling YANG  Yuanqi FU  Zhongke WANG  Xiaoqiong ZHEN  Zhipeng YANG  Xingang FAN  

     
    PAPER-Image Processing and Video Processing

      Pubricized:
    2019/02/12
      Vol:
    E102-D No:5
      Page(s):
    1065-1072

    A new fuzzy level set method (FLSM) based on the global search capability of quantum particle swarm optimization (QPSO) is proposed to improve the stability and precision of image segmentation, and reduce the sensitivity of initialization. The new combination of QPSO-FLSM algorithm iteratively optimizes initial contours using the QPSO method and fuzzy c-means clustering, and then utilizes level set method (LSM) to segment images. The new algorithm exploits the global search capability of QPSO to obtain a stable cluster center and a pre-segmentation contour closer to the region of interest during the iteration. In the implementation of the new method in segmenting liver tumors, brain tissues, and lightning images, the fitness function of the objective function of QPSO-FLSM algorithm is optimized by 10% in comparison to the original FLSM algorithm. The achieved initial contours from the QPSO-FLSM algorithm are also more stable than that from the FLSM. The QPSO-FLSM resulted in improved final image segmentation.

  • Detecting Communities and Correlated Attribute Clusters on Multi-Attributed Graphs

    Hiroyoshi ITO  Takahiro KOMAMIZU  Toshiyuki AMAGASA  Hiroyuki KITAGAWA  

     
    PAPER

      Pubricized:
    2019/02/04
      Vol:
    E102-D No:4
      Page(s):
    810-820

    Multi-attributed graphs, in which each node is characterized by multiple types of attributes, are ubiquitous in the real world. Detection and characterization of communities of nodes could have a significant impact on various applications. Although previous studies have attempted to tackle this task, it is still challenging due to difficulties in the integration of graph structures with multiple attributes and the presence of noises in the graphs. Therefore, in this study, we have focused on clusters of attribute values and strong correlations between communities and attribute-value clusters. The graph clustering methodology adopted in the proposed study involves Community detection, Attribute-value clustering, and deriving Relationships between communities and attribute-value clusters (CAR for short). Based on these concepts, the proposed multi-attributed graph clustering is modeled as CAR-clustering. To achieve CAR-clustering, a novel algorithm named CARNMF is developed based on non-negative matrix factorization (NMF) that can detect CAR in a cooperative manner. Results obtained from experiments using real-world datasets show that the CARNMF can detect communities and attribute-value clusters more accurately than existing comparable methods. Furthermore, clustering results obtained using the CARNMF indicate that CARNMF can successfully detect informative communities with meaningful semantic descriptions through correlations between communities and attribute-value clusters.

  • A Parallel Flow Monitoring Technique That Achieves Accurate Delay Measurement

    Kohei WATABE  Shintaro HIRAKAWA  Kenji NAKAGAWA  

     
    PAPER-Network Management/Operation

      Pubricized:
    2018/10/03
      Vol:
    E102-B No:4
      Page(s):
    865-875

    In this paper, a parallel flow monitoring technique that achieves accurate measurement of end-to-end delay of networks is proposed. In network monitoring tasks, network researchers and practitioners usually monitor multiple probe flows to measure delays on multiple paths in parallel. However, when they measure an end-to-end delay on a path, information of flows except for the flow along the path is not utilized in the conventional method. Generally, paths of flows share common parts in parallel monitoring. In the proposed method, information of flows on paths that share common parts, utilizes to measure delay on a path by partially converting the observation results of a flow to those of another flow. We perform simulations to confirm that the observation results of 72 parallel flows of active measurement are appropriately converted between each other. When the 99th-percentile of the end-to-end delay for each flow are measured, the accuracy of the proposed method is doubled compared with the conventional method.

  • The Shift-and-Add Property of m-Sequences

    Fanxin ZENG  Lijia GE  Xiping HE  Guixin XUAN  Guojun LI  Zhenyu ZHANG  Yanni PENG  Linjie QIAN  Sheng LU  

     
    LETTER-Information Theory

      Vol:
    E102-A No:4
      Page(s):
    685-690

    The shift-and-add property (SAP) of a p-ary m-sequence {ak} with period N=pn-1 means that this sequence satisfies the equation {ak+η}+{ak+τ}={ak+λ} for some integers η, τ and λ. For an arbitrarily-given p-ary m-sequence {ak}, we develop an algebraic approach to determine the integer λ for the arbitrarily-given integers η and τ. And all trinomials can be given. Our calculation only depends on the reciprocal polynomial of the primitive polynomial which produces the given m-sequence {ak}, and the cyclotomic cosets mod pn-1.

  • A Simple Heuristic for Order-Preserving Matching

    Joong Chae NA  Inbok LEE  

     
    LETTER

      Pubricized:
    2018/10/30
      Vol:
    E102-D No:3
      Page(s):
    502-504

    Order preserving matching refers to the problem of reporting substrings in the text which are order-isomorphic to the pattern. In this paper, we show a simple heuristic which runs in linear time on average, based on finding the largest elements in each substring and checking their locations against that of the pattern. It is easy to implement and experimental results showed that the running time grows linearly.

  • A 6th-Order Quadrature Bandpass Delta Sigma AD Modulator Using Dynamic Amplifier and Noise Coupling SAR Quantizer

    Chunhui PAN  Hao SAN  

     
    PAPER

      Vol:
    E102-A No:3
      Page(s):
    507-517

    This paper presents a 6th-order quadrature bandpass delta sigma AD modulator (QBPDSM) with 2nd-order image rejection using dynamic amplifier and noise coupling (NC) SAR quantizer embedded by passive adder for the application of wireless communication system. A novel complex integrator using dynamic amplifier is proposed to improve the energy efficiency of the QBPDSM. The NC SAR quantizer can realize an additional 2nd-order noise shaping and 2nd-order image rejection by the digital domain noise coupling technique. As a result, the 6th-order QBPDSM with 2nd-order image rejection is realized by two complex integrators using dynamic amplifier and the NC SAR quantizer. The SPICE simulation results demonstrate the feasibility of the proposed QBPDSM in 90nm CMOS technology. Simulated SNDR of 76.30dB is realized while a sinusoid -3.25dBFS input is sampled at 33.3MS/s and the bandwidth of 2.083MHz (OSR=8) is achieved. The total power consumption in the modulator is 6.74mW while the supply voltage is 1.2V.

  • Accurate Library Recommendation Using Combining Collaborative Filtering and Topic Model for Mobile Development

    Xiaoqiong ZHAO  Shanping LI  Huan YU  Ye WANG  Weiwei QIU  

     
    PAPER-Software Engineering

      Pubricized:
    2018/12/18
      Vol:
    E102-D No:3
      Page(s):
    522-536

    Background: The applying of third-party libraries is an integral part of many applications. But the libraries choosing is time-consuming even for experienced developers. The automated recommendation system for libraries recommendation is widely researched to help developers to choose libraries. Aim: from software engineering aspect, our research aims to give developers a reliable recommended list of third-party libraries at the early phase of software development lifecycle to help them build their development environment faster; and from technical aspect, our research aims to build a generalizable recommendation system framework which combines collaborative filtering and topic modeling techniques, in order to improve the performance of libraries recommendation significantly. Our works on this research: 1) we design a hybrid methodology to combine collaborative filtering and LDA text mining technology; 2) we build a recommendation system framework successfully based on the above hybrid methodology; 3) we make a well-designed experiment to validate the methodology and framework which use the data of 1,013 mobile application projects; 4) we do the evaluation for the result of the experiment. Conclusions: 1) hybrid methodology with collaborative filtering and LDA can improve the performance of libraries recommendation significantly; 2) based on the hybrid methodology, the framework works very well on the libraries recommendation for helping developers' libraries choosing. Further research is necessary to improve the performance of the libraries recommendation including: 1) use more accurate NLP technologies improve the correlation analysis; 2) try other similarity calculation methodology for collaborative filtering to rise the accuracy; 3) on this research, we just bring the time-series approach to the framework and make an experiment as comparative trial, the result shows that the performance improves continuously, so in further research we plan to use time-series data-mining as the basic methodology to update the framework.

  • The Covering Radius of the Reed-Muller Code R(3, 7) in R(5, 7) Is 20

    Gui LI  Qichun WANG  Shi SHU  

     
    LETTER-Coding Theory

      Vol:
    E102-A No:3
      Page(s):
    594-597

    We propose a recursive algorithm to reduce the computational complexity of the r-order nonlinearity of n-variable Boolean functions. Applying the algorithm and using the sufficient and necessary condition put forward by [1] to cut the vast majority of useless search branches, we show that the covering radius of the Reed-Muller Code R(3, 7) in R(5, 7) is 20.

  • Fabrication and Evaluation of Integrated Photonic Array-Antenna System for RoF Based Remote Antenna Beam Forming

    Takayoshi HIRASAWA  Shigeyuki AKIBA  Jiro HIROKAWA  Makoto ANDO  

     
    PAPER-Lasers, Quantum Electronics

      Vol:
    E102-C No:3
      Page(s):
    235-242

    This paper studies the performance of the quantitative RF power variation in Radio-over-Fiber beam forming system utilizing a phased array-antenna integrating photo-diodes in downlink network for next generation millimeter wave band radio access. Firstly, we described details of fabrication of an integrated photonic array-antenna (IPA), where a 60GHz patch antenna 4×2 array and high-speed photo-diodes were integrated into a substrate. We evaluated RF transmission efficiency as an IPA system for Radio-over-Fiber (RoF)-based mobile front hall architecture with remote antenna beam forming capability. We clarified the characteristics of discrete and integrated devices such as an intensity modulator (IM), an optical fiber and the IPA and calculated RF power radiated from the IPA taking account of the measured data of the devices. Based on the experimental results on RF tone signal transmission by utilizing the IPA, attainable transmission distance of wireless communication by improvement and optimization of the used devices was discussed. We deduced that the antenna could output sufficient power when we consider that the cell size of the future mobile communication systems would be around 100 meters or smaller.

  • Partial Gathering of Mobile Agents in Arbitrary Networks

    Masahiro SHIBATA  Daisuke NAKAMURA  Fukuhito OOSHITA  Hirotsugu KAKUGAWA  Toshimitsu MASUZAWA  

     
    PAPER

      Pubricized:
    2018/11/01
      Vol:
    E102-D No:3
      Page(s):
    444-453

    In this paper, we consider the partial gathering problem of mobile agents in arbitrary networks. The partial gathering problem is a generalization of the (well-investigated) total gathering problem, which requires that all the agents meet at the same node. The partial gathering problem requires, for a given positive integer g, that each agent should move to a node and terminate so that at least g agents should meet at each of the nodes they terminate at. The requirement for the partial gathering problem is no stronger than that for the total gathering problem, and thus, we clarify the difference on the move complexity between them. First, we show that agents require Ω(gn+m) total moves to solve the partial gathering problem, where n is the number of nodes and m is the number of communication links. Next, we propose a deterministic algorithm to solve the partial gathering problem in O(gn+m) total moves, which is asymptotically optimal in terms of total moves. Note that, it is known that agents require Ω(kn+m) total moves to solve the total gathering problem in arbitrary networks, where k is the number of agents. Thus, our result shows that the partial gathering problem is solvable with strictly fewer total moves compared to the total gathering problem in arbitrary networks.

  • The Coloring Reconfiguration Problem on Specific Graph Classes

    Tatsuhiko HATANAKA  Takehiro ITO  Xiao ZHOU  

     
    PAPER

      Pubricized:
    2018/10/30
      Vol:
    E102-D No:3
      Page(s):
    423-429

    We study the problem of transforming one (vertex) c-coloring of a graph into another one by changing only one vertex color assignment at a time, while at all times maintaining a c-coloring, where c denotes the number of colors. This decision problem is known to be PSPACE-complete even for bipartite graphs and any fixed constant c ≥ 4. In this paper, we study the problem from the viewpoint of graph classes. We first show that the problem remains PSPACE-complete for chordal graphs even if c is a fixed constant. We then demonstrate that, even when c is a part of input, the problem is solvable in polynomial time for several graph classes, such as k-trees with any integer k ≥ 1, split graphs, and trivially perfect graphs.

  • Scalable State Space Search with Structural-Bottleneck Heuristics for Declarative IT System Update Automation Open Access

    Takuya KUWAHARA  Takayuki KURODA  Manabu NAKANOYA  Yutaka YAKUWA  Hideyuki SHIMONISHI  

     
    PAPER

      Pubricized:
    2018/09/20
      Vol:
    E102-B No:3
      Page(s):
    439-451

    As IT systems, including network systems using SDN/NFV technologies, become large-scaled and complicated, the cost of system management also increases rapidly. Network operators have to maintain their workflow in constructing and consistently updating such complex systems, and thus these management tasks in generating system update plan are desired to be automated. Declarative system update with state space search is a promising approach to enable this automation, however, the current methods is not enough scalable to practical systems. In this paper, we propose a novel heuristic approach to greatly reduce computation time to solve system update procedure for practical systems. Our heuristics accounts for structural bottleneck of the system update and advance search to resolve bottlenecks of current system states. This paper includes the following contributions: (1) formal definition of a novel heuristic function specialized to system update for A* search algorithm, (2) proofs that our heuristic function is consistent, i.e., A* algorithm with our heuristics returns a correct optimal solution and can omit repeatedly expansion of nodes in search spaces, and (3) results of performance evaluation of our heuristics. We evaluate the proposed algorithm in two cases; upgrading running hypervisor and rolling update of running VMs. The results show that computation time to solve system update plan for a system with 100 VMs does not exceed several minutes, whereas the conventional algorithm is only applicable for a very small system.

  • Evasive Malicious Website Detection by Leveraging Redirection Subgraph Similarities

    Toshiki SHIBAHARA  Yuta TAKATA  Mitsuaki AKIYAMA  Takeshi YAGI  Kunio HATO  Masayuki MURATA  

     
    PAPER

      Pubricized:
    2018/10/30
      Vol:
    E102-D No:3
      Page(s):
    430-443

    Many users are exposed to threats of drive-by download attacks through the Web. Attackers compromise vulnerable websites discovered by search engines and redirect clients to malicious websites created with exploit kits. Security researchers and vendors have tried to prevent the attacks by detecting malicious data, i.e., malicious URLs, web content, and redirections. However, attackers conceal parts of malicious data with evasion techniques to circumvent detection systems. In this paper, we propose a system for detecting malicious websites without collecting all malicious data. Even if we cannot observe parts of malicious data, we can always observe compromised websites. Since vulnerable websites are discovered by search engines, compromised websites have similar traits. Therefore, we built a classifier by leveraging not only malicious but also compromised websites. More precisely, we convert all websites observed at the time of access into a redirection graph and classify it by integrating similarities between its subgraphs and redirection subgraphs shared across malicious, benign, and compromised websites. As a result of evaluating our system with crawling data of 455,860 websites, we found that the system achieved a 91.7% true positive rate for malicious websites containing exploit URLs at a low false positive rate of 0.1%. Moreover, it detected 143 more evasive malicious websites than the conventional content-based system.

  • A Device-Centric Clustering Approach for Large-Scale Distributed Antenna Systems Using User Cooperation

    Ou ZHAO  Lin SHAN  Wei-Shun LIAO  Mirza GOLAM KIBRIA  Huan-Bang LI  Kentaro ISHIZU  Fumihide KOJIMA  

     
    PAPER-Wireless Communication Technologies

      Pubricized:
    2018/08/13
      Vol:
    E102-B No:2
      Page(s):
    359-372

    Large-scale distributed antenna systems (LS-DASs) are gaining increasing interest and emerging as highly promising candidates for future wireless communications. To improve the user's quality of service (QoS) in these systems, this study proposes a user cooperation aided clustering approach based on device-centric architectures; it enables multi-user multiple-input multiple-output transmissions with non-reciprocal setups. We actively use device-to-device communication techniques to achieve the sharing of user information and try to form clusters on user side instead of the traditional way that performs clustering on base station (BS) side in data offloading. We further adopt a device-centric architecture to break the limits of the classical BS-centric cellular structure. Moreover, we derive an approximate expression to calculate the user rate for LS-DASs with employment of zero-forcing precoding and consideration of inter-cluster interference. Numerical results indicate that the approximate expression predicts the user rate with a lower computational cost than is indicated by computer simulation, and the proposed approach provides better user experience for, in particular, the users who have unacceptable QoS.

  • How to Select TDOA-Based Bearing Measurements for Improved Passive Triangulation Localization

    Kyu-Ha SONG  San-Hae KIM  Woo-Jin SONG  

     
    LETTER-Measurement Technology

      Vol:
    E102-A No:2
      Page(s):
    490-496

    When time difference of arrival (TDOA)-based bearing measurements are used in passive triangulation, the accuracy of localization depends on the geometric relationship between the emitter and the sensors. In particular, the localization accuracy varies with the geometric conditions in TDOA-based direction finding (DF) for bearing measurement and lines of bearing (LOBs) crossing for triangulation. To obtain an accurate estimate in passive triangulation using TDOA-based bearing measurements, we shall use these bearings selectively by considering geometric dilution of precision (GDOP) between the emitter and the sensors. To achieve this goal, we first define two GDOPs related to TDOA-based DF and LOBs crossing geometries, and then propose a new hybrid GDOP by combining these GDOPs for a better selection of bearings. Subsequently, two bearings with the lowest hybrid GDOP condition are chosen as the inputs to a triangulation localization algorithm. In simulations, the proposed method shows its enhancement to the localization accuracy.

  • Preordering for Chinese-Vietnamese Statistical Machine Translation

    Huu-Anh TRAN  Heyan HUANG  Phuoc TRAN  Shumin SHI  Huu NGUYEN  

     
    PAPER-Natural Language Processing

      Pubricized:
    2018/11/12
      Vol:
    E102-D No:2
      Page(s):
    375-382

    Word order is one of the most significant differences between the Chinese and Vietnamese. In the phrase-based statistical machine translation, the reordering model will learn reordering rules from bilingual corpora. If the bilingual corpora are large and good enough, the reordering rules are exact and coverable. However, Chinese-Vietnamese is a low-resource language pair, the extraction of reordering rules is limited. This leads to the quality of reordering in Chinese-Vietnamese machine translation is not high. In this paper, we have combined Chinese dependency relation and Chinese-Vietnamese word alignment results in order to pre-order Chinese word order to be suitable to Vietnamese one. The experimental results show that our methodology has improved the machine translation performance compared to the translation system using only the reordering models of phrase-based statistical machine translation.

  • Specific Properties of the Computation Process by a Turing Machine on the Game of Life

    Shigeru NINAGAWA  

     
    PAPER-Nonlinear Problems

      Vol:
    E102-A No:2
      Page(s):
    415-422

    The Game of Life, a two-dimensional computationally universal cellular automaton, is known to exhibits 1/f noise in the evolutions starting from random configurations. In this paper we perform the spectral analysis on the computation process by a Turing machine constructed on the array of the Game of Life. As a result, the power spectrum averaged over the whole array has almost flat line at low frequencies and a lot of sharp peaks at high frequencies although some regions in which complicated behavior such as frequent memory rewriting occurs exhibit 1/f noise. This singular power spectrum is, however, easily turned into 1/f by slightly deforming the initial configuration of the Turing machine. These results emphasize the peculiarity of the computation process on the Game of Life that is never shared with the evolutions from random configurations. The Lyapunov exponents have positive values in three out of six trials and zero or negative values in other three trails. That means the computation process is essentially chaotic but it has capable of recovering a slight error in the configuration of the Turing machine.

  • A Universal Two-Dimensional Source Coding by Means of Subblock Enumeration Open Access

    Takahiro OTA  Hiroyoshi MORITA  Akiko MANADA  

     
    PAPER-Information Theory

      Vol:
    E102-A No:2
      Page(s):
    440-449

    The technique of lossless compression via substring enumeration (CSE) is a kind of enumerative code and uses a probabilistic model built from the circular string of an input source for encoding a one-dimensional (1D) source. CSE is applicable to two-dimensional (2D) sources, such as images, by dealing with a line of pixels of a 2D source as a symbol of an extended alphabet. At the initial step of CSE encoding process, we need to output the number of occurrences of all symbols of the extended alphabet, so that the time complexity increases exponentially when the size of source becomes large. To reduce computational time, we can rearrange pixels of a 2D source into a 1D source string along a space-filling curve like a Hilbert curve. However, information on adjacent cells in a 2D source may be lost in the conversion. To reduce the time complexity and compress a 2D source without converting to a 1D source, we propose a new CSE which can encode a 2D source in a block-by-block fashion instead of in a line-by-line fashion. The proposed algorithm uses the flat torus of an input 2D source as a probabilistic model instead of the circular string of the source. Moreover, we prove the asymptotic optimality of the proposed algorithm for 2D general sources.

  • A Small Printed Inverted-F Antenna for Circular Polarization

    Takafumi FUJIMOTO  Keigo SHIMIZU  

     
    PAPER-Antennas

      Pubricized:
    2018/08/21
      Vol:
    E102-B No:2
      Page(s):
    197-204

    In this paper, a printed inverted-F antenna for radiating circularly polarized wave around its resonant frequency is proposed. To get good axial ratio at the frequency band with 10dB-return loss, a rectangular element is loaded at the feeding line perpendicularly. The axial ratio and the frequency giving the minimum axial ratio can be adjusted by the ratio of the length to the width of the whole antenna and by the dimension of the loaded rectangular element. The operational principle for circular polarization is explained using the electric current distributions. Moreover, the approach of the enhancement for the bandwidth is discussed. The simulated and measured bandwidths of the 10dB-return loss with a 3dB-axial ratio are 2.375GHz-2.591GHz (216MHz) and 2.350-2.534GHz (184MHz), respectively. The proposed antenna's dimension is 0.067λ2c (λc is the wavelength at the center frequency). The proposed antenna is compact and planar, and is therefore useful for circular polarization in the ISM band.

321-340hit(2923hit)