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  • Combining Spiking Neural Networks with Artificial Neural Networks for Enhanced Image Classification

    Naoya MURAMATSU  Hai-Tao YU  Tetsuji SATOH  

     
    PAPER-Biocybernetics, Neurocomputing

      Pubricized:
    2022/11/07
      Vol:
    E106-D No:2
      Page(s):
    252-261

    With the continued innovation of deep neural networks, spiking neural networks (SNNs) that more closely resemble biological brain synapses have attracted attention because of their low power consumption. Unlike artificial neural networks (ANNs), for continuous data values, they must employ an encoding process to convert the values to spike trains, suppressing the SNN's performance. To avoid this degradation, the incoming analog signal must be regulated prior to the encoding process, which is also realized in living things eg, the basement membranes of humans mechanically perform the Fourier transform. To this end, we combine an ANN and an SNN to build ANN-to-SNN hybrid neural networks (HNNs) that improve the concerned performance. To qualify this performance and robustness, MNIST and CIFAR-10 image datasets are used for various classification tasks in which the training and encoding methods changes. In addition, we present simultaneous and separate training methods for the artificial and spiking layers, considering the encoding methods of each. We find that increasing the number of artificial layers at the expense of spiking layers improves the HNN performance. For straightforward datasets such as MNIST, similar performances as ANN's are achieved by using duplicate coding and separate learning. However, for more complex tasks, the use of Gaussian coding and simultaneous learning is found to improve the accuracy of the HNN while lower power consumption.

  • A Study of Phase-Adjusting Architectures for Low-Phase-Noise Quadrature Voltage-Controlled Oscillators Open Access

    Mamoru UGAJIN  Yuya KAKEI  Nobuyuki ITOH  

     
    PAPER-Electronic Circuits

      Pubricized:
    2022/08/03
      Vol:
    E106-C No:2
      Page(s):
    59-66

    Quadrature voltage-controlled oscillators (VCOs) with current-weight-average and voltage-weight-average phase-adjusting architectures are studied. The phase adjusting equalizes the oscillation frequency to the LC-resonant frequency. The merits of the equalization are explained by using Leeson's phase noise equation and the impulse sensitivity function (ISF). Quadrature VCOs with the phase-adjusting architectures are fabricated using 180-nm TSMC CMOS and show low-phase-noise performances compared to a conventional differential VCO. The ISF analysis and small-signal analysis also show that the drawbacks of the current-weight-average phase-adjusting and voltage-weight-average phase-adjusting architectures are current-source noise effect and large additional capacitance, respectively. A voltage-average-adjusting circuit with a source follower at its input alleviates the capacitance increase.

  • Machine Learning in 6G Wireless Communications Open Access

    Tomoaki OHTSUKI  

     
    INVITED PAPER

      Pubricized:
    2022/08/10
      Vol:
    E106-B No:2
      Page(s):
    75-83

    Mobile communication systems are not only the core of the Information and Communication Technology (ICT) infrastructure but also that of our social infrastructure. The 5th generation mobile communication system (5G) has already started and is in use. 5G is expected for various use cases in industry and society. Thus, many companies and research institutes are now trying to improve the performance of 5G, that is, 5G Enhancement and the next generation of mobile communication systems (Beyond 5G (6G)). 6G is expected to meet various highly demanding requirements even compared with 5G, such as extremely high data rate, extremely large coverage, extremely low latency, extremely low energy, extremely high reliability, extreme massive connectivity, and so on. Artificial intelligence (AI) and machine learning (ML), AI/ML, will have more important roles than ever in 6G wireless communications with the above extreme high requirements for a diversity of applications, including new combinations of the requirements for new use cases. We can say that AI/ML will be essential for 6G wireless communications. This paper introduces some ML techniques and applications in 6G wireless communications, mainly focusing on the physical layer.

  • Energy Efficiency Optimization for MISO-NOMA SWIPT System with Heterogeneous QoS Requirements

    Feng LIU  Xianlong CHENG  Conggai LI  Yanli XU  

     
    LETTER-Mobile Information Network and Personal Communications

      Pubricized:
    2022/08/18
      Vol:
    E106-A No:2
      Page(s):
    159-163

    This letter solves the energy efficiency optimization problem for the simultaneous wireless information and power transfer (SWIPT) systems with non-orthogonal multiple access (NOMA), multiple input single output (MISO) and power-splitting structures, where each user may have different individual quality of service (QoS) requirements about information and energy. Nonlinear energy harvesting model is used. Alternate optimization approach is adopted to find the solution, which shows a fast convergence behavior. Simulation results show the proposed scheme has higher energy efficiency than existing dual-layer iteration and throughput maximization methods.

  • Does Introduction of Individual Learning at Home Improve the Effectiveness of Group Learning at Classroom in First-Year PBL Course?

    Katsuhiko ISHIKAWA  Taro MURAKAMI  Mikiya TANIGUCHI  

     
    PAPER

      Pubricized:
    2022/11/18
      Vol:
    E106-D No:2
      Page(s):
    121-130

    This study examined whether distance learning in a first-year PBL courses in the first unit of instruction improves the effectiveness of subsequent group work learning over face-to-face learning. The first-year PBL consisted of three units: an input unit, a group work unit and an outcomes presentation unit. In 2017/2018, the input unit was conducted in the classroom with face-to-face learning. In 2017, a workshop was held in addition to face-to-face learning in classroom. In 2020/2021, the input unit was conducted with distance learning. In the years, approximately 100 people completed the questionnaire. A preliminary check confirmed that the average score of students' self-assessment of their own social skills were not significantly different among the four years. Analysis showed that in 2018, the perceived efficacy in the group work unit depended on learners' high social skills. Alternatively, in 2017/2020/2021, the perceived efficacy in group work was not dependent on learners' social skills. This suggests that distance learning and face-to-face learning with workshop learning, instead of full face-to-face learning for the units placed before the group work unit facilitates the learning efficacy of the group work unit, even for students with social skill concerns.

  • Chinese Lexical Sememe Prediction Using CilinE Knowledge

    Hao WANG  Sirui LIU  Jianyong DUAN  Li HE  Xin LI  

     
    PAPER-Language, Thought, Knowledge and Intelligence

      Pubricized:
    2022/08/18
      Vol:
    E106-A No:2
      Page(s):
    146-153

    Sememes are the smallest semantic units of human languages, the composition of which can represent the meaning of words. Sememes have been successfully applied to many downstream applications in natural language processing (NLP) field. Annotation of a word's sememes depends on language experts, which is both time-consuming and labor-consuming, limiting the large-scale application of sememe. Researchers have proposed some sememe prediction methods to automatically predict sememes for words. However, existing sememe prediction methods focus on information of the word itself, ignoring the expert-annotated knowledge bases which indicate the relations between words and should value in sememe predication. Therefore, we aim at incorporating the expert-annotated knowledge bases into sememe prediction process. To achieve that, we propose a CilinE-guided sememe prediction model which employs an existing word knowledge base CilinE to remodel the sememe prediction from relational perspective. Experiments on HowNet, a widely used Chinese sememe knowledge base, have shown that CilinE has an obvious positive effect on sememe prediction. Furthermore, our proposed method can be integrated into existing methods and significantly improves the prediction performance. We will release the data and code to the public.

  • Superposition Signal Input Decoding for Lattice Reduction-Aided MIMO Receivers Open Access

    Satoshi DENNO  Koki KASHIHARA  Yafei HOU  

     
    PAPER-Wireless Communication Technologies

      Pubricized:
    2022/08/01
      Vol:
    E106-B No:2
      Page(s):
    184-192

    This paper proposes a novel approach to low complexity soft input decoding for lattice reduction-aided MIMO receivers. The proposed approach feeds a soft input decoder with soft signals made from hard decision signals generated by using a lattice reduction-aided linear detector. The soft signal is a weighted-sum of some candidate vectors that are near by the hard decision signal coming out from the lattice reduction-aided linear detector. This paper proposes a technique to adjust the weight adapt to the channel for the higher transmission performance. Furthermore, we propose to introduce a coefficient that is used for the weights in order to enhance the transmission performance. The transmission performance is evaluated in a 4×4 MIMO channel. When a linear MMSE filter or a serial interference canceller is used as the linear detector, the proposed technique achieves about 1.0dB better transmission performance at the BER of 10-5 than the decoder fed with the hard decision signals. In addition, the low computational complexity of the proposed technique is quantitatively evaluated.

  • An Efficient Method to Decompose and Map MPMCT Gates That Accounts for Qubit Placement

    Atsushi MATSUO  Wakaki HATTORI  Shigeru YAMASHITA  

     
    PAPER-Algorithms and Data Structures

      Pubricized:
    2022/08/10
      Vol:
    E106-A No:2
      Page(s):
    124-132

    Mixed-Polarity Multiple-Control Toffoli (MPMCT) gates are generally used to implement large control logic functions for quantum computation. A logic circuit consisting of MPMCT gates needs to be mapped to a quantum computing device that invariably has a physical limitation, which means we need to (1) decompose the MPMCT gates into one- or two-qubit gates, and then (2) insert SWAP gates so that all the gates can be performed on Nearest Neighbor Architectures (NNAs). Up to date, the above two processes have only been studied independently. In this work, we investigate that the total number of gates in a circuit can be decreased if the above two processes are considered simultaneously as a single step. We developed a method that inserts SWAP gates while decomposing MPMCT gates unlike most of the existing methods. Also, we consider the effect on the latter part of a circuit carefully by considering the qubit placement when decomposing an MPMCT gate. Experimental results demonstrate the effectiveness of our method.

  • Face Image Generation of Anime Characters Using an Advanced First Order Motion Model with Facial Landmarks

    Junki OSHIBA  Motoi IWATA  Koichi KISE  

     
    PAPER

      Pubricized:
    2022/10/12
      Vol:
    E106-D No:1
      Page(s):
    22-30

    Recently, deep learning for image generation with a guide for the generation has been progressing. Many methods have been proposed to generate the animation of facial expression change from a single face image by transferring some facial expression information to the face image. In particular, the method of using facial landmarks as facial expression information can generate a variety of facial expressions. However, most methods do not focus on anime characters but humans. Moreover, we attempted to apply several existing methods to anime characters by training the methods on an anime character face dataset; however, they generated images with noise, even in regions where there was no change. The first order motion model (FOMM) is an image generation method that takes two images as input and transfers one facial expression or pose to the other. By explicitly calculating the difference between the two images based on optical flow, FOMM can generate images with low noise in the unchanged regions. In the following, we focus on the aspect of the face image generation in FOMM. When we think about the employment of facial landmarks as targets, the performance of FOMM is not enough because FOMM cannot use a facial landmark as a facial expression target because the appearances of a face image and a facial landmark are quite different. Therefore, we propose an advanced FOMM method to use facial landmarks as a facial expression target. In the proposed method, we change the input data and data flow to use facial landmarks. Additionally, to generate face images with expressions that follow the target landmarks more closely, we introduce the landmark estimation loss, which is computed by comparing the landmark detected from the generated image with the target landmark. Our experiments on an anime character face image dataset demonstrated that our method is effective for landmark-guided face image generation for anime characters. Furthermore, our method outperformed other methods quantitatively and generated face images with less noise.

  • Face Hallucination via Multi-Scale Structure Prior Learning

    Yuexi YAO  Tao LU  Kanghui ZHAO  Yanduo ZHANG  Yu WANG  

     
    LETTER-Image

      Pubricized:
    2022/07/19
      Vol:
    E106-A No:1
      Page(s):
    92-96

    Recently, the face hallucination method based on deep learning understands the mapping between low-resolution (LR) and high-resolution (HR) facial patterns by exploring the priors of facial structure. However, how to maintain the face structure consistency after the reconstruction of face images at different scales is still a challenging problem. In this letter, we propose a novel multi-scale structure prior learning (MSPL) for face hallucination. First, we propose a multi-scale structure prior block (MSPB). Considering the loss of high-frequency information in the LR space, we mainly process the input image in three different scale ascending dimensional spaces, and map the image to the high dimensional space to extract multi-scale structural prior information. Then the size of feature maps is recovered by downsampling, and finally the multi-scale information is fused to restore the feature channels. On this basis, we propose a local detail attention module (LDAM) to focus on the local texture information of faces. We conduct extensive face hallucination reconstruction experiments on a public face dataset (LFW) to verify the effectiveness of our method.

  • Construction of Odd-Variable Strictly Almost Optimal Resilient Boolean Functions with Higher Resiliency Order via Modifying High-Meets-Low Technique

    Hui GE  Zepeng ZHUO  Xiaoni DU  

     
    LETTER-Cryptography and Information Security

      Pubricized:
    2022/07/12
      Vol:
    E106-A No:1
      Page(s):
    73-77

    Construction of resilient Boolean functions in odd variables having strictly almost optimal (SAO) nonlinearity appears to be a rather difficult task in stream cipher and coding theory. In this paper, based on the modified High-Meets-Low technique, a general construction to obtain odd-variable SAO resilient Boolean functions without directly using PW functions or KY functions is presented. It is shown that the new class of functions possess higher resiliency order than the known functions while keeping higher SAO nonlinearity, and in addition the resiliency order increases rapidly with the variable number n.

  • Robust Optimization Model for Primary and Backup Capacity Allocations against Multiple Physical Machine Failures under Uncertain Demands in Cloud

    Mitsuki ITO  Fujun HE  Kento YOKOUCHI  Eiji OKI  

     
    PAPER-Network

      Pubricized:
    2022/07/05
      Vol:
    E106-B No:1
      Page(s):
    18-34

    This paper proposes a robust optimization model for probabilistic protection under uncertain capacity demands to minimize the total required capacity against multiple simultaneous failures of physical machines. The proposed model determines both primary and backup virtual machine allocations simultaneously under the probabilistic protection guarantee. To express the uncertainty of capacity demands, we introduce an uncertainty set that considers the upper bound of the total demand and the upper and lower bounds of each demand. The robust optimization technique is applied to the optimization model to deal with two uncertainties: failure event and capacity demand. With this technique, the model is formulated as a mixed integer linear programming (MILP) problem. To solve larger sized problems, a simulated annealing (SA) heuristic is introduced. In SA, we obtain the capacity demands by solving maximum flow problems. Numerical results show that our proposed model reduces the total required capacity compared with the conventional model by determining both primary and backup virtual machine allocations simultaneously. We also compare the results of MILP, SA, and a baseline greedy algorithm. For a larger sized problem, we obtain approximate solutions in a practical time by using SA and the greedy algorithm.

  • A Low Insertion Loss Wideband Bonding-Wire Based Interconnection for 400 Gbps PAM4 Transceivers

    Xiangyu MENG  Yecong LI  Zhiyi YU  

     
    PAPER-Electronic Components

      Pubricized:
    2022/06/23
      Vol:
    E106-C No:1
      Page(s):
    14-19

    This paper proposes a design of high-speed interconnection between optical modules and electrical modules via bonding-wires and coplanar waveguide transmission lines on printed circuit boards for 400 Gbps 4-channel optical communication systems. In order to broaden the interconnection bandwidth, interdigitated capacitors were integrated with GSG pads on chip for the first time. Simulation results indicate the reflection coefficient is below -10 dB from DC to 53 GHz and the insertion loss is below 1 dB from DC to 45 GHz. Both indicators show that the proposed interconnection structure can effectively satisfy the communication bandwidth requirements of 100-Gbps or even higher data-rate PAM4 signals.

  • Accurate Doppler Velocity Estimation by Iterative WKD Algorithm for Pulse-Doppler Radar

    Takumi HAYASHI  Takeru ANDO  Shouhei KIDERA  

     
    PAPER-Sensing

      Pubricized:
    2022/06/29
      Vol:
    E105-B No:12
      Page(s):
    1600-1613

    In this study, we propose an accurate range-Doppler analysis algorithm for moving multiple objects in a short range using microwave (including millimeter wave) radars. As a promising Doppler analysis for the above model, we previously proposed a weighted kernel density (WKD) estimator algorithm, which overcomes several disadvantages in coherent integration based methods, such as a trade-off between temporal and frequency resolutions. However, in handling multiple objects like human body, it is difficult to maintain the accuracy of the Doppler velocity estimation, because there are multiple responses from multiple parts of object, like human body, incurring inaccuracies in range or Doppler velocity estimation. To address this issue, we propose an iterative algorithm by exploiting an output of the WKD algorithm. Three-dimensional numerical analysis, assuming a human body model in motion, and experimental tests demonstrate that the proposed algorithm provides more accurate, high-resolution range-Doppler velocity profiles than the original WKD algorithm, without increasing computational complexity. Particularly, the simulation results show that the cumulative probabilities of range errors within 10mm, and Doppler velocity error within 0.1m/s are enhanced from 34% (by the former method) to 63% (by the proposed method).

  • Noise Suppression in SiC-MOSFET Body Diode Turn-Off Operation with Simple and Robust Gate Driver

    Hiroshi SUZUKI  Tsuyoshi FUNAKI  

     
    PAPER-Semiconductor Materials and Devices

      Pubricized:
    2022/06/14
      Vol:
    E105-C No:12
      Page(s):
    750-760

    SiC-MOSFETs are being increasingly implemented in power electronics systems as low-loss, fast switching devices. Despite the advantages of an SiC-MOSFET, its large dv/dt or di/dt has fear of electromagnetic interference (EMI) noise. This paper proposes and demonstrates a simple and robust gate driver that can suppress ringing oscillation and surge voltage induced by the turn-off of the SiC-MOSFET body diode. The proposed gate driver utilizes the channel leakage current methodology (CLC) to enhance the damping effect by elevating the gate-source voltage (VGS) and inducing the channel leakage current in the device. The gate driver can self-adjust the timing of initiating CLC operation, which avoids an increase in switching loss. Additionally, the output voltage of the VGS elevation circuit does not need to be actively controlled in accordance with the operating conditions. Thus, the circuit topology is simple, and ringing oscillation can be easily attenuated with fixed circuit parameters regardless of operating conditions, minimizing the increase in switching loss. The effectiveness and versatility of proposed gate driver were experimentally validated for a wide range of operating conditions by double and single pulse switching tests.

  • Model-Agnostic Multi-Domain Learning with Domain-Specific Adapters for Action Recognition

    Kazuki OMI  Jun KIMATA  Toru TAMAKI  

     
    PAPER-Image Recognition, Computer Vision

      Pubricized:
    2022/09/15
      Vol:
    E105-D No:12
      Page(s):
    2119-2126

    In this paper, we propose a multi-domain learning model for action recognition. The proposed method inserts domain-specific adapters between layers of domain-independent layers of a backbone network. Unlike a multi-head network that switches classification heads only, our model switches not only the heads, but also the adapters for facilitating to learn feature representations universal to multiple domains. Unlike prior works, the proposed method is model-agnostic and doesn't assume model structures unlike prior works. Experimental results on three popular action recognition datasets (HMDB51, UCF101, and Kinetics-400) demonstrate that the proposed method is more effective than a multi-head architecture and more efficient than separately training models for each domain.

  • Optimal Design of Optical Waveguide Devices Utilizing Beam Propagation Method with ADI Scheme Open Access

    Akito IGUCHI  Yasuhide TSUJI  

     
    INVITED PAPER

      Pubricized:
    2022/05/20
      Vol:
    E105-C No:11
      Page(s):
    644-651

    This paper shows structural optimal design of optical waveguide components utilizing an efficient 3D frequency-domain and 2D time-domain beam propagation method (BPM) with an alternating direction implicit (ADI) scheme. Usual optimal design procedure is based on iteration of numerical simulation, and total computational cost of the optimal design mainly depends on the efficiency of numerical analysis method. Since the system matrices are tridiagonal in the ADI-based BPM, efficient analysis and optimal design are available. Shape and topology optimal design shown in this paper is based on optimization of density distribution and sensitivity analysis to the density parameters. Computational methods of the sensitivity are shown in the case of using the 3D semi-vectorial and 2D time-domain BPM based on ADI scheme. The validity of this design approach is shown by design of optical waveguide components: mode converters, and a polarization beam splitter.

  • Non-Orthogonal Physical Layer (NOPHY) Design towards 5G Evolution and 6G

    Xiaolin HOU  Wenjia LIU  Juan LIU  Xin WANG  Lan CHEN  Yoshihisa KISHIYAMA  Takahiro ASAI  

     
    PAPER-Wireless Communication Technologies

      Pubricized:
    2022/04/26
      Vol:
    E105-B No:11
      Page(s):
    1444-1457

    5G has achieved large-scale commercialization across the world and the global 6G research and development is accelerating. To support more new use cases, 6G mobile communication systems should satisfy extreme performance requirements far beyond 5G. The physical layer key technologies are the basis of the evolution of mobile communication systems of each generation, among which three key technologies, i.e., duplex, waveform and multiple access, are the iconic characteristics of mobile communication systems of each generation. In this paper, we systematically review the development history and trend of the three key technologies and define the Non-Orthogonal Physical Layer (NOPHY) concept for 6G, including Non-Orthogonal Duplex (NOD), Non-Orthogonal Multiple Access (NOMA) and Non-Orthogonal Waveform (NOW). Firstly, we analyze the necessity and feasibility of NOPHY from the perspective of capacity gain and implementation complexity. Then we discuss the recent progress of NOD, NOMA and NOW, and highlight several candidate technologies and their potential performance gain. Finally, combined with the new trend of 6G, we put forward a unified physical layer design based on NOPHY that well balances performance against flexibility, and point out the possible direction for the research and development of 6G physical layer key technologies.

  • Experimental Study on Synchronization of Van der Pol Oscillator Circuit by Noise Sounds

    Taiki HAYASHI  Kazuyoshi ISHIMURA  Isao T. TOKUDA  

     
    PAPER-Nonlinear Problems

      Pubricized:
    2022/05/16
      Vol:
    E105-A No:11
      Page(s):
    1486-1492

    Towards realization of a noise-induced synchronization in a natural environment, an experimental study is carried out using the Van der Pol oscillator circuit. We focus on acoustic sounds as a potential source of noise that may exist in nature. To mimic such a natural environment, white noise sounds were generated from a loud speaker and recorded into microphone signals. These signals were then injected into the oscillator circuits. We show that the oscillator circuits spontaneously give rise to synchronized dynamics when the microphone signals are highly correlated with each other. As the correlation among the input microphone signals is decreased, the level of synchrony is lowered monotonously, implying that the input correlation is the key determinant for the noise-induced synchronization. Our study provides an experimental basis for synchronizing clocks in distributed sensor networks as well as other engineering devices in natural environment.

  • A KPI Anomaly Detection Method Based on Fast Clustering

    Yun WU  Yu SHI  Jieming YANG  Lishan BAO  Chunzhe LI  

     
    PAPER

      Pubricized:
    2022/05/27
      Vol:
    E105-B No:11
      Page(s):
    1309-1317

    In the Artificial Intelligence for IT Operations scenarios, KPI (Key Performance Indicator) is a very important operation and maintenance monitoring indicator, and research on KPI anomaly detection has also become a hot spot in recent years. Aiming at the problems of low detection efficiency and insufficient representation learning of existing methods, this paper proposes a fast clustering-based KPI anomaly detection method HCE-DWL. This paper firstly adopts the combination of hierarchical agglomerative clustering (HAC) and deep assignment based on CNN-Embedding (CE) to perform cluster analysis (that is HCE) on KPI data, so as to improve the clustering efficiency of KPI data, and then separately the centroid of each KPI cluster and its Transformed Outlier Scores (TOS) are given weights, and finally they are put into the LightGBM model for detection (the Double Weight LightGBM model, referred to as DWL). Through comparative experimental analysis, it is proved that the algorithm can effectively improve the efficiency and accuracy of KPI anomaly detection.

141-160hit(5648hit)