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[Author] Hiroshi FUJITA(15hit)

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  • Relationship between Induced Noise and Load Current at Ag Contacts Breaking with Inductive Load

    Keiichi UCHIMURA  Hiroshi FUJITA  

     
    LETTER-Electromagnetic Compatibility

      Vol:
    E73-E No:3
      Page(s):
    351-353

    This letter illustrates the characteristics and causes of the noise voltage induced in adjacent circuit having resistive terminations at the break of silver contacts with inductive load.

  • Prevention in a Chip of EMI Noise Caused by X'tal Oscillator

    Atsushi KUROKAWA  Hiroshi FUJITA  Tetsuya IBE  

     
    PAPER

      Vol:
    E91-A No:4
      Page(s):
    1077-1083

    Developing LSIs with EMI suppression, particularly for use in automobiles, is important for improving warranties and customer acquisition. First, we describe that the measures against EMI noise caused by a X'tal oscillator are important. Next, we present a practical method for analyzing the noise with models of the inside and outside of a chip. In addition, we propose a within-chip measure against EMI noise that takes chip cost into account. The noise is suppressed by using an appropriate resistance and capacitance on the power line. Simulation results demonstrated the method's effectiveness in suppressing noise.

  • An Automatic Detection Method for Carotid Artery Calcifications Using Top-Hat Filter on Dental Panoramic Radiographs

    Tsuyoshi SAWAGASHIRA  Tatsuro HAYASHI  Takeshi HARA  Akitoshi KATSUMATA  Chisako MURAMATSU  Xiangrong ZHOU  Yukihiro IIDA  Kiyoji KATAGI  Hiroshi FUJITA  

     
    LETTER-Artificial Intelligence, Data Mining

      Vol:
    E96-D No:8
      Page(s):
    1878-1881

    The purpose of this study is to develop an automated scheme of carotid artery calcification (CAC) detection on dental panoramic radiographs (DPRs). The CAC is one of the indices for predicting the risk of arteriosclerosis. First, regions of interest (ROIs) that include carotid arteries are determined on the basis of inflection points of the mandibular contour. Initial CAC candidates are detected by using a grayscale top-hat filter and a simple grayscale thresholding technique. Finally, a rule-based approach and a support vector machine to reduce the number of false positive (FP) findings are applied using features such as area, location, and circularity. A hundred DPRs were used to evaluate the proposed scheme. The sensitivity for the detection of CACs was 90% with 4.3 FPs (80% with 1.9 FPs) per image. Experiments show that our computer-aided detection scheme may be useful to detect CACs.

  • Induced Noise Properties Caused by Circuit Interruption with Electric Contacts

    Keiichi UCHIMURA  Hiroshi FUJITA  

     
    PAPER-Electromagnetic Compatibility

      Vol:
    E74-B No:7
      Page(s):
    1935-1940

    Electric contact is one of the most important noise sources of electromagnetic noise. Hence, the noise of contact switching has been researched from various points of view with respect to the generation mechanism and properties. However, many phenomena have been remained not being investigated yet. In this paper, we describe our recent investigations about characteristics of the induced noise that is produced by the break of silver contact. The number of TTL IC's malfunction in the relay switching are counted under conditions of inductive load (10mH), circuit current (0.1-2A), and low source voltage (24V). From this experimental results, it became clear that the rate of malfunction decreased with increasing circuit current. To clarify its phenomenon, the circuit current dependence of the induced noise voltage was measured. It was observed that the level of induced noise voltage became the maximum in the current range of 0.2-1A. This property is discussed by the occurrence mechanism of each discharge mode on the break of contacts and the observation of induced noise corresponding to its mode.

  • Extending MaxSAT to Solve the Coalition Structure Generation Problem with Externalities Based on Agent Relations

    Xiaojuan LIAO  Miyuki KOSHIMURA  Hiroshi FUJITA  Ryuzo HASEGAWA  

     
    PAPER-Information Network

      Vol:
    E97-D No:7
      Page(s):
    1812-1821

    Coalition Structure Generation (CSG) means partitioning agents into exhaustive and disjoint coalitions so that the sum of values of all the coalitions is maximized. Solving this problem could be facilitated by employing some compact representation schemes, such as marginal contribution network (MC-net). In MC-net, the CSG problem is represented by a set of rules where each rule is associated with a real-valued weights, and the goal is to maximize the sum of weights of rules under some constraints. This naturally leads to a combinatorial optimization problem that could be solved with weighted partial MaxSAT (WPM). In general, WPM deals with only positive weights while the weights involved in a CSG problem could be either positive or negative. With this in mind, in this paper, we propose an extension of WPM to handle negative weights and take advantage of the extended WPM to solve the MC-net-based CSG problem. Specifically, we encode the relations between each pair of agents and reform the MC-net as a set of Boolean formulas. Thus, the CSG problem is encoded as an optimization problem for WPM solvers. Furthermore, we apply this agent relation-based WPM with minor revision to solve the extended CSG problem where the value of a coalition is affected by the formation of other coalitions, a coalition known as externality. Experiments demonstrate that, compared to the previous encoding, our proposed method speeds up the process of solving the CSG problem significantly, as it generates fewer number of Boolean variables and clauses that need to be examined by WPM solver.

  • Vapor-Deposition Polymerization of Vinyl Polymer Thin Films of Naphthalene Diimide Derivatives

    Keisuke TOMIDA  Hiroshi FUJITA  Satoshi USUI  Kuniaki TANAKA  Hiroaki USUI  

     
    BRIEF PAPER

      Vol:
    E100-C No:2
      Page(s):
    141-144

    Thin films of vinyl derivatives of naphthalene diimide were prepared by electron-assisted vapor deposition. Monomer materials of N, N'-bis(allyl)-naphthalene diimide (Allyl-NDI) and N,N'-bis(p-vinyl-benzyl)-naphthalene diimide (Sty-NDI) were newly synthesized for this purpose. Uniform films were obtained by vapor-depositing these materials, whereas spin-coating yielded nonuniform films. IR analysis suggested that Sty-NDI can be polymerized upon vapor deposition. An insoluble film of Sty-NDI was obtained by the electron-assisted vapor deposition. On the other hand, Allyl-NDI had lower reactivity for polymerization. It was concluded that Sty-NDI is a promising material for preparing thin films of vinyl polymer having naphthalene diimide units.

  • Automatic Segmentation of Hepatic Tissue and 3D Volume Analysis of Cirrhosis in Multi-Detector Row CT Scans and MR Imaging

    Xuejun ZHANG  Wenguang LI  Hiroshi FUJITA  Masayuki KANEMATSU  Takeshi HARA  Xiangrong ZHOU  Hiroshi KONDO  Hiroaki HOSHI  

     
    PAPER-Biological Engineering

      Vol:
    E87-D No:8
      Page(s):
    2138-2147

    The enlargement of the left lobe of the liver and the shrinkage of the right lobe are helpful signs at MR imaging in diagnosis of cirrhosis of the liver. To investigate whether the volume ratio of left-to-whole (LTW) is effective to differentiate cirrhosis from a normal liver, we developed an automatic algorithm for three-dimensional (3D) segmentation and volume calculation of the liver region in multi-detector row CT scans and MR imaging. From one manually selected slice that contains a large liver area, two edge operators are applied to obtain the initial liver area, from which the mean gray value is calculated as threshold value in order to eliminate the connected organs or tissues. The final contour is re-confirmed by using thresholding technique. The liver region in the next slice is generated by referring to the result from the last slice. After continuous procedure of this segmentation on each slice, the 3D liver is reconstructed from all the extracted slices and the surface image can be displayed from different view points by using the volume rendering technique. The liver is then separated into the left and the right lobe by drawing an inter-segmental plane manually, and the volume in each part is calculated slice by slice. The degree of cirrhosis can be defined as the ratio of volume in these two lobes. Four cases including normal and cirrhotic liver with MR and CT slices are used for 3D segmentation and visualization. The volume ratio of LTW was relatively higher in cirrhosis than in the normal cases in both MR and CT cases. The average error rate on liver segmentation was within 5.6% after employing in 30 MR cases. These results demonstrate that the performance in our 3D segmentation was satisfied and the LTW ratio may be effective to differentiate cirrhosis.

  • Solving Open Job-Shop Scheduling Problems by SAT Encoding

    Miyuki KOSHIMURA  Hidetomo NABESHIMA  Hiroshi FUJITA  Ryuzo HASEGAWA  

     
    LETTER-Artificial Intelligence, Data Mining

      Vol:
    E93-D No:8
      Page(s):
    2316-2318

    This paper tries to solve open Job-Shop Scheduling Problems (JSSP) by translating them into Boolean Satisfiability Testing Problems (SAT). The encoding method is essentially the same as the one proposed by Crawford and Baker. The open problems are ABZ8, ABZ9, YN1, YN2, YN3, and YN4. We proved that the best known upper bounds 678 of ABZ9 and 884 of YN1 are indeed optimal. We also improved the upper bound of YN2 and lower bounds of ABZ8, YN2, YN3 and YN4.

  • Model-Based Approach to Recognize the Rectus Abdominis Muscle in CT Images Open Access

    Naoki KAMIYA  Xiangrong ZHOU  Huayue CHEN  Chisako MURAMATSU  Takeshi HARA  Hiroshi FUJITA  

     
    LETTER-Medical Image Processing

      Vol:
    E96-D No:4
      Page(s):
    869-871

    Our purpose in this study is to develop a scheme to segment the rectus abdominis muscle region in X-ray CT images. We propose a new muscle recognition method based on the shape model. In this method, three steps are included in the segmentation process. The first is to generate a shape model for representing the rectus abdominis muscle. The second is to recognize anatomical feature points corresponding to the origin and insertion of the muscle, and the third is to segment the rectus abdominis muscles using the shape model. We generated the shape model from 20 CT cases and tested the model to recognize the muscle in 10 other CT cases. The average value of the Jaccard similarity coefficient (JSC) between the manually and automatically segmented regions was 0.843. The results suggest the validity of the model-based segmentation for the rectus abdominis muscle.

  • TPF: An Effective Method for Verifying Synchronous Circuits with Induction-Based Provers

    Kazuko TAKAHASHI  Hiroshi FUJITA  

     
    PAPER-Computer Hardware and Design

      Vol:
    E81-D No:1
      Page(s):
    12-18

    We propose a new method for verifying synchronous circuits using the Boyer-Moore Theorem Prover (BMTP) based on an efficient use of induction. The method contains two techniques. The one is the representation method of signals. Each signal is represented not as a waveform, but as a time parameterized function. The other is the mechanical transformation of the circuit description. A simple description of the logical connection of the components of a circuit is transformed into such a form that is not only acceptable as a definition of BMTP but also adequate for applying induction. We formalize the method and show that it realizes an efficient proof.

  • Proposal of Capacity Analysis in Wireless Sensor Networks with Multi-Hop Transmissions and Hidden Nodes

    Yun WEN  Kazuyuki OZAKI  Hiroshi FUJITA  Teruhisa NINOMIYA  Makoto YOSHIDA  

     
    PAPER

      Vol:
    E98-B No:9
      Page(s):
    1749-1757

    Wireless sensor networks play an important role in several industries. Ad-hoc networks with multi-hop transmissions are considered suitable for wireless sensor networks because of their high scalability and low construction cost. However, a lack of centralized control makes it difficult to respond to congestion when system capacity is exceeded. Therefore, the analysis of system capacity is a critical issue for system design. In this paper, we propose a novel zone division model to analyze the capacity of multi-hop wireless sensor networks using carrier sense multiple access with collision avoidance protocols. We divide the one-hop area to a gateway (GW) into two zones: an outer zone, where access nodes (ANs) can relay packets from multi-hop ANs, and an inner zone where ANs cannot relay packets. Using this approach, we calculate the packet loss for each zone to estimate the capacity, considering the difference in the communication range of the GW and ANs, as well as the collision with hidden nodes. Comparisons with simulation results and the conventional method show that our model achieves higher estimation accuracy.

  • Breast Tumor Classification by Neural Networks Fed with Sequential-Dependence Factors to the Input Layer

    Du-Yih TSAI  Hiroshi FUJITA  Katsuhei HORITA  Tokiko ENDO  Choichiro KIDO  Sadayuki SAKUMA  

     
    PAPER-Medical Electronics and Medical Information

      Vol:
    E76-D No:8
      Page(s):
    956-962

    We applied an artificial neural network approach identify possible tumors into benign and malignant ones in mammograms. A sequential-dependence technique, which calculates the degree of redundancy or patterning in a sequence, was employed to extract image features from mammographic images. The extracted vectors were then used as input to the network. Our preliminary results show that the neural network can correctly classify benign and malignant tumors at an average rate of 85%. This accuracy rate indicates that the neural network approach with the proposed feature-extraction technique has potential utility in the computer-aided diagnosis of breast cancer.

  • FOREWORD Open Access

    Hiroshi FUJITA  

     
    FOREWORD

      Vol:
    E96-D No:4
      Page(s):
    771-771
  • Development of an Automated Method for the Detection of Chronic Lacunar Infarct Regions in Brain MR Images

    Ryujiro YOKOYAMA  Xuejun ZHANG  Yoshikazu UCHIYAMA  Hiroshi FUJITA  Takeshi HARA  Xiangrong ZHOU  Masayuki KANEMATSU  Takahiko ASANO  Hiroshi KONDO  Satoshi GOSHIMA  Hiroaki HOSHI  Toru IWAMA  

     
    PAPER-Image Recognition, Computer Vision

      Vol:
    E90-D No:6
      Page(s):
    943-954

    The purpose of our study is to develop an algorithm that would enable the automated detection of lacunar infarct on T1- and T2-weighted magnetic resonance (MR) images. Automated identification of the lacunar infarct regions is not only useful in assisting radiologists to detect lacunar infarcts as a computer-aided detection (CAD) system but is also beneficial in preventing the occurrence of cerebral apoplexy in high-risk patients. The lacunar infarct regions are classified into the following two types for detection: "isolated lacunar infarct regions" and "lacunar infarct regions adjacent to hyperintensive structures." The detection of isolated lacunar infarct regions was based on the multiple-phase binarization (MPB) method. Moreover, to detect lacunar infarct regions adjacent to hyperintensive structures, we used a morphological opening processing and a subtraction technique between images produced using two types of circular structuring elements. Thereafter, candidate regions were selected based on three features -- area, circularity, and gravity center. Two methods were applied to the detected candidates for eliminating false positives (FPs). The first method involved eliminating FPs that occurred along the periphery of the brain using the region-growing technique. The second method, the multi-circular regions difference method (MCRDM), was based on the comparison between the mean pixel values in a series of double circles on a T1-weighted image. A training dataset comprising 20 lacunar infarct cases was used to adjust the parameters. In addition, 673 MR images from 80 cases were used for testing the performance of our method; the sensitivity and specificity were 90.1% and 30.0% with 1.7 FPs per image, respectively. The results indicated that our CAD system for the automatic detection of lacunar infarct on MR images was effective.

  • MaxSAT Encoding for MC-Net-Based Coalition Structure Generation Problem with Externalities

    Xiaojuan LIAO  Miyuki KOSHIMURA  Hiroshi FUJITA  Ryuzo HASEGAWA  

     
    PAPER-Information Network

      Vol:
    E97-D No:7
      Page(s):
    1781-1789

    Coalition Structure Generation (CSG) is a main research issue in the domain of coalition games. A majority of existing works assume that the value of a coalition is independent of others in the coalition structure. Recently, there has been interest in a more realistic settings, where the value of a coalition is affected by the formation of other coalitions. This effect is known as externality. The focus of this paper is to make use of Maximum Satisfiability (MaxSAT) to solve the CSG problem where externalities may exist. In order to reduce the exponentially growing number of possible solutions in the CSG problem, we follow the previous works by representing the CSG problem as sets of rules in MC-nets (without externalities) and embedded MC-nets (with externalities). Specifically, enlightened by the previous MC-net-based algorithms exploiting the constraints among rule relations to solve the CSG problem, we encode such constraints into weighted partial MaxSAT (WPM) formulas. Experimental results demonstrate that an off-the-shelf MaxSAT solver achieves significant improvements compared to the previous algorithm for the same set of problem instances.