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[Author] Takashi MATSUBARA(14hit)

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  • A Fault Tolerant Intercommunication Scheme Using Bank Memory Switching

    Norihiko TANAKA  Takakazu KUROKAWA  Takashi MATSUBARA  Yoshiaki KOGA  

     
    PAPER

      Vol:
    E75-D No:6
      Page(s):
    804-809

    This paper proposes a new fault tolerant intercommunication scheme for real-time operations and three new interconnection networks to construct a fault tolerant multi-processor system for pipeline processings. The proposed intercommunication scheme using bank memory switching technique has an advantage to make a fault tolerant pipeline system so that it can detect any failure caused in a processing element of the system. In addition, it can overcome conventional problems caused in interconnection circuits to flow data with one way direction such as a pipeline processing.

  • Target-Oriented Deformation of Visual-Semantic Embedding Space

    Takashi MATSUBARA  

     
    PAPER

      Pubricized:
    2020/09/24
      Vol:
    E104-D No:1
      Page(s):
    24-33

    Multimodal embedding is a crucial research topic for cross-modal understanding, data mining, and translation. Many studies have attempted to extract representations from given entities and align them in a shared embedding space. However, because entities in different modalities exhibit different abstraction levels and modality-specific information, it is insufficient to embed related entities close to each other. In this study, we propose the Target-Oriented Deformation Network (TOD-Net), a novel module that continuously deforms the embedding space into a new space under a given condition, thereby providing conditional similarities between entities. Unlike methods based on cross-modal attention applied to words and cropped images, TOD-Net is a post-process applied to the embedding space learned by existing embedding systems and improves their performances of retrieval. In particular, when combined with cutting-edge models, TOD-Net gains the state-of-the-art image-caption retrieval model associated with the MS COCO and Flickr30k datasets. Qualitative analysis reveals that TOD-Net successfully emphasizes entity-specific concepts and retrieves diverse targets via handling higher levels of diversity than existing models.

  • Dependable Bus Arbitraion by Alternating Competition with Checkers

    Kazuo TOKITO  Takashi MATSUBARA  Yoshiaki KOGA  

     
    PAPER-Testing/Checking

      Vol:
    E80-D No:1
      Page(s):
    44-50

    A fault in multi-processing system arbitration circuits result in incorrect arbitration or abnormal operation of the system. A highly reliable system requires dependable arbitration in order to operate properly. Previously, we proposed alternate competing arbitration suitable for highly reliable systems. In this paper, we propose a method for improvement of fault detection and location using additional checkers. This method is effective to maintain reliability of the system.

  • Fault Tolerant Properties and a Fault-Checking Method of Fuzzy Control

    Hiroshi ITO  Takashi MATSUBARA  Takakazu KUROKAWA  Yoshiaki KOGA  

     
    PAPER-Fail-Safe/Fault Tolerant

      Vol:
    E76-D No:5
      Page(s):
    586-593

    Generally it is said that a fuzzy control system has fault tolerant properties, but it is not clearly studied. In this paper, first, the influence of faults in fuzzy control systems is examined. Errors given by fault simulation are not negligible. However, no fault detecting method is applied in the realized fuzzy control systems. Then a fault-checking method to detect faults is proposed in this paper.

  • Ultrafast Time-Serial to Space-Parallel Converter Using Organic Dye Films

    Makoto FURUKI  Izumi IWASA  Satoshi TATSUURA  Yasuhiro SATO  Minquan TIAN  Takashi MATSUBARA  Hiroyuki MITSU  Makoto NARUSE  Fumito KUBOTA  

     
    INVITED PAPER

      Vol:
    E87-C No:7
      Page(s):
    1161-1165

    Using ultrafast nonlinear-optical response of organic dye films, a train of picosecond optical pulses can be converted into a space pattern of a mm scale. As applications of this technique we demonstrate a single-shot multichannel optical switching for 1 Tbit/s pulse trains, and a timing jitter suppression of pulse trains using a control system with femtoseconds time resolution.

  • Deep State-Space Model for Noise Tolerant Skeleton-Based Action Recognition

    Kazuki KAWAMURA  Takashi MATSUBARA  Kuniaki UEHARA  

     
    PAPER

      Pubricized:
    2020/03/18
      Vol:
    E103-D No:6
      Page(s):
    1217-1225

    Action recognition using skeleton data (3D coordinates of human joints) is an attractive topic due to its robustness to the actor's appearance, camera's viewpoint, illumination, and other environmental conditions. However, skeleton data must be measured by a depth sensor or extracted from video data using an estimation algorithm, and doing so risks extraction errors and noise. In this work, for robust skeleton-based action recognition, we propose a deep state-space model (DSSM). The DSSM is a deep generative model of the underlying dynamics of an observable sequence. We applied the proposed DSSM to skeleton data, and the results demonstrate that it improves the classification performance of a baseline method. Moreover, we confirm that feature extraction with the proposed DSSM renders subsequent classifications robust to noise and missing values. In such experimental settings, the proposed DSSM outperforms a state-of-the-art method.

  • Inverse Heat Dissipation Model for Medical Image Segmentation

    Yu KASHIHARA  Takashi MATSUBARA  

     
    LETTER-Artificial Intelligence, Data Mining

      Pubricized:
    2023/08/22
      Vol:
    E106-D No:11
      Page(s):
    1930-1934

    The diffusion model has achieved success in generating and editing high-quality images because of its ability to produce fine details. Its superior generation ability has the potential to facilitate more detailed segmentation. This study presents a novel approach to segmentation tasks using an inverse heat dissipation model, a kind of diffusion-based models. The proposed method involves generating a mask that gradually shrinks to fit the shape of the desired segmentation region. We comprehensively evaluated the proposed method using multiple datasets under varying conditions. The results show that the proposed method outperforms existing methods and provides a more detailed segmentation.

  • Realization of Multi-Terminal Universal Interconnection Networks Using Contact Switches

    Tsutomu SASAO  Takashi MATSUBARA  Katsufumi TSUJI  Yoshiaki KOGA  

     
    PAPER-Logic Design

      Pubricized:
    2021/04/01
      Vol:
    E104-D No:8
      Page(s):
    1068-1075

    A universal interconnection network implements arbitrary interconnections among n terminals. This paper considers a problem to realize such a network using contact switches. When n=2, it can be implemented with a single switch. The number of different connections among n terminals is given by the Bell number B(n). The Bell number shows the total number of methods to partition n distinct elements. For n=2, 3, 4, 5 and 6, the corresponding Bell numbers are 2, 5, 15, 52, and 203, respectively. This paper shows a method to realize an n terminal universal interconnection network with $ rac {3}{8}(n^2-1)$ contact switches when n=2m+1≥5, and $ rac {n}{8}(3n+2)$ contact switches, when n=2m≥6. Also, it shows that a lower bound on the number of contact switches to realize an n-terminal universal interconnection network is ⌈log 2B(n)⌉, where B(n) is the Bell number.

  • Hybrid of Reinforcement and Imitation Learning for Human-Like Agents

    Rousslan F. J. DOSSA  Xinyu LIAN  Hirokazu NOMOTO  Takashi MATSUBARA  Kuniaki UEHARA  

     
    PAPER-Artificial Intelligence, Data Mining

      Pubricized:
    2020/06/15
      Vol:
    E103-D No:9
      Page(s):
    1960-1970

    Reinforcement learning methods achieve performance superior to humans in a wide range of complex tasks and uncertain environments. However, high performance is not the sole metric for practical use such as in a game AI or autonomous driving. A highly efficient agent performs greedily and selfishly, and is thus inconvenient for surrounding users, hence a demand for human-like agents. Imitation learning reproduces the behavior of a human expert and builds a human-like agent. However, its performance is limited to the expert's. In this study, we propose a training scheme to construct a human-like and efficient agent via mixing reinforcement and imitation learning for discrete and continuous action space problems. The proposed hybrid agent achieves a higher performance than a strict imitation learning agent and exhibits more human-like behavior, which is measured via a human sensitivity test.

  • Neuron-Like Responses and Bifurcations of a Generalized Asynchronous Sequential Logic Spiking Neuron Model

    Takashi MATSUBARA  Hiroyuki TORIKAI  

     
    PAPER-Nonlinear Problems

      Vol:
    E95-A No:8
      Page(s):
    1317-1328

    A generalized version of sequential logic circuit based neuron models is presented, where the dynamics of the model is modeled by an asynchronous cellular automaton. Thanks to the generalizations in this paper, the model can exhibit various neuron-like waveforms of the membrane potential in response to excitatory and inhibitory stimulus. Also, the model can reproduce four groups of biological and model neurons, which are classified based on existence of bistability and subthreshold oscillations, as well as their underlying bifurcations mechanisms.

  • Neural Architecture Search for Convolutional Neural Networks with Attention

    Kohei NAKAI  Takashi MATSUBARA  Kuniaki UEHARA  

     
    PAPER-Image Recognition, Computer Vision

      Pubricized:
    2020/10/26
      Vol:
    E104-D No:2
      Page(s):
    312-321

    The recent development of neural architecture search (NAS) has enabled us to automatically discover architectures of neural networks with high performance within a few days. Convolutional neural networks extract fruitful features by repeatedly applying standard operations (convolutions and poolings). However, these operations also extract useless or even disturbing features. Attention mechanisms enable neural networks to discard information of no interest, having achieved the state-of-the-art performance. While a variety of attentions for CNNs have been proposed, current NAS methods have paid a little attention to them. In this study, we propose a novel NAS method that searches attentions as well as operations. We examined several patterns to arrange attentions and operations, and found that attentions work better when they have their own search space and follow operations. We demonstrate the superior performance of our method in experiments on CIFAR-10, CIFAR-100, and ImageNet datasets. The found architecture achieved lower classification error rates and required fewer parameters compared to those found by current NAS methods.

  • A Novel Double Oscillation Model for Prediction of fMRI BOLD Signals without Detrending

    Takashi MATSUBARA  Hiroyuki TORIKAI  Tetsuya SHIMOKAWA  Kenji LEIBNITZ  Ferdinand PEPER  

     
    PAPER-Nonlinear Problems

      Vol:
    E98-A No:9
      Page(s):
    1924-1936

    This paper presents a nonlinear model of human brain activity in response to visual stimuli according to Blood-Oxygen-Level-Dependent (BOLD) signals scanned by functional Magnetic Resonance Imaging (fMRI). A BOLD signal often contains a low frequency signal component (trend), which is usually removed by detrending because it is considered a part of noise. However, such detrending could destroy the dynamics of the BOLD signal and ignore an essential component in the response. This paper shows a model that, in the absence of detrending, can predict the BOLD signal with smaller errors than existing models. The presented model also has low Schwarz information criterion, which implies that it will be less likely to overfit the experimental data. Comparison between the various types of artificial trends suggests that the trends are not merely the result of noise in the BOLD signal.

  • Few-Shot Anomaly Detection Using Deep Generative Models for Grouped Data

    Kazuki SATO  Satoshi NAKATA  Takashi MATSUBARA  Kuniaki UEHARA  

     
    LETTER-Pattern Recognition

      Pubricized:
    2021/10/25
      Vol:
    E105-D No:2
      Page(s):
    436-440

    There exists a great demand for automatic anomaly detection in industrial world. The anomaly has been defined as a group of samples that rarely or never appears. Given a type of products, one has to collect numerous samples and train an anomaly detector. When one diverts a model trained with old types of products with sufficient inventory to the new type, one can detect anomalies of the new type before a production line is established. However, because of the definition of the anomaly, a typical anomaly detector considers the new type of products anomalous even if it is consistent with the standard. Given the above practical demand, this study propose a novel problem setting, few-shot anomaly detection, where an anomaly detector trained in source domains is adapted to a small set of target samples without full retraining. Then, we tackle this problem using a hierarchical probabilistic model based on deep learning. Our empirical results on toy and real-world datasets demonstrate that the proposed model detects anomalies in a small set of target samples successfully.

  • Stock Price Prediction by Deep Neural Generative Model of News Articles

    Takashi MATSUBARA  Ryo AKITA  Kuniaki UEHARA  

     
    PAPER-Datamining Technologies

      Pubricized:
    2018/01/19
      Vol:
    E101-D No:4
      Page(s):
    901-908

    In this study, we propose a deep neural generative model for predicting daily stock price movements given news articles. Approaches involving conventional technical analysis have been investigated to identify certain patterns in past price movements, which in turn helps to predict future price movements. However, the financial market is highly sensitive to specific events, including corporate buyouts, product releases, and the like. Therefore, recent research has focused on modeling relationships between these events that appear in the news articles and future price movements; however, a very large number of news articles are published daily, each article containing rich information, which results in overfitting to past price movements used for parameter adjustment. Given the above, we propose a model based on a generative model of news articles that includes price movement as a condition, thereby avoiding excessive overfitting thanks to the nature of the generative model. We evaluate our proposed model using historical price movements of Nikkei 225 and Standard & Poor's 500 Stock Index, confirming that our model predicts future price movements better than such conventional classifiers as support vector machines and multilayer perceptrons. Further, our proposed model extracts significant words from news articles that are directly related to future stock price movements.