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[Author] Hao ZHANG(60hit)

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  • Robust Non-Parametric Template Matching with Local Rigidity Constraints

    Chao ZHANG  Haitian SUN  Takuya AKASHI  

     
    PAPER-Image Recognition, Computer Vision

      Pubricized:
    2016/06/03
      Vol:
    E99-D No:9
      Page(s):
    2332-2340

    In this paper, we address the problem of non-parametric template matching which does not assume any specific deformation models. In real-world matching scenarios, deformation between a template and a matching result usually appears to be non-rigid and non-linear. We propose a novel approach called local rigidity constraints (LRC). LRC is built based on an assumption that the local rigidity, which is referred to as structural persistence between image patches, can help the algorithm to achieve better performance. A spatial relation test is proposed to weight the rigidity between two image patches. When estimating visual similarity under an unconstrained environment, high-level similarity (e.g. with complex geometry transformations) can then be estimated by investigating the number of LRC. In the searching step, exhaustive matching is possible because of the simplicity of the algorithm. Global maximum is given out as the final matching result. To evaluate our method, we carry out a comprehensive comparison on a publicly available benchmark and show that our method can outperform the state-of-the-art method.

  • Robust Projective Template Matching

    Chao ZHANG  Takuya AKASHI  

     
    PAPER-Image Recognition, Computer Vision

      Pubricized:
    2016/06/08
      Vol:
    E99-D No:9
      Page(s):
    2341-2350

    In this paper, we address the problem of projective template matching which aims to estimate parameters of projective transformation. Although homography can be estimated by combining key-point-based local features and RANSAC, it can hardly be solved with feature-less images or high outlier rate images. Estimating the projective transformation remains a difficult problem due to high-dimensionality and strong non-convexity. Our approach is to quantize the parameters of projective transformation with binary finite field and search for an appropriate solution as the final result over the discrete sampling set. The benefit is that we can avoid searching among a huge amount of potential candidates. Furthermore, in order to approximate the global optimum more efficiently, we develop a level-wise adaptive sampling (LAS) method under genetic algorithm framework. With LAS, the individuals are uniformly selected from each fitness level and the elite solution finally converges to the global optimum. In the experiment, we compare our method against the popular projective solution and systematically analyse our method. The result shows that our method can provide convincing performance and holds wider application scope.

  • An Edge Dependent Weighted Filter for Video Deinterlacing

    Hao ZHANG  Mengtian RONG  Tao LIU  

     
    LETTER-Image

      Vol:
    E98-A No:2
      Page(s):
    788-791

    In this letter, we propose a new intra-field deinterlacing algorithm based on an edge dependent weighted filter (EDWF). The proposed algorithm consists of three steps: 1) calculating the gradients of three directions (45°, 90°, and 135°) in the local working window; 2) achieving the weights of the neighboring pixels by exploiting the edge information in the pixel gradients; 3) interpolating the missing pixel using the proposed EDWF interpolator. Compared with existing deinterlacing methods on different images and video sequences, the proposed algorithm improves the peak signal-to-noise-ratio (PSNR) while achieving better subjective quality.

  • Measurement of Complex Waveforms in Wide Wavelength Range by Using Wavelength-Swept Light Source and Linear Optical Sampling

    Sougo SHIMIZU  Chao ZHANG  Fumihiko ITO  

     
    PAPER-Fiber-Optic Transmission for Communications

      Pubricized:
    2021/12/28
      Vol:
    E105-B No:7
      Page(s):
    797-804

    This paper describes a method to evaluate the modulated waveforms output by a high-speed external phase modulator over a wide wavelength range by using linear optical sampling (LOS) and a wavelength-swept light source. The phase-modulated waveform is sampled by LOS together with the reference signal before modulation, and the modulation waveform is observed by removing the phase noise of the light source extracted from the reference signal. In this process, the frequency offset caused by the optical-path length difference between the measurement and reference interferometers is removed by digital signal processing. A pseudo-random binary-sequence modulated signal is observed with a temporal resolution of 10ps. We obtained a dynamic range of ∼40dB for the measurement bandwidth of 10 nm. When the measurement bandwidth is expanded to entire C-Band (∼35nm), the dynamic ranges of 37∼46dB were observed, depending on the wavelengths. The measurement time was sub-seconds throughout the experiment.

  • Optimal Mutually Orthogonal ZCZ Polyphase Sequence Sets

    Fanxin ZENG  Xiping HE  Guixin XUAN  Wenchao ZHANG  Guojun LI  Zhenyu ZHANG  Yanni PENG  Sheng LU  Li YAN  

     
    LETTER-Information Theory

      Vol:
    E101-A No:10
      Page(s):
    1713-1718

    In an approximately synchronized (AS) code-division multiple-access (CDMA) communication system, zero correlation zone (ZCZ) sequences can be used as its spreading sequences so that the system suppresses multiple access interference (MAI) and multi-path interference (MPI) fully and synchronously. In this letter, the mutually orthogonal (MO) ZCZ polyphase sequence sets proposed by one of the authors are improved, and the resultant ZCZ sequences in each set arrive at the theoretical bound regarding ZCZ sequences under some conditions. Therefore, the improved MO ZCZ sequence sets are optimal.

  • Self-Cascode MOSFET with a Self-Biased Body Effect for Ultra-Low-Power Voltage Reference Generator

    Hao ZHANG  Mengshu HUANG  Yimeng ZHANG  Tsutomu YOSHIHARA  

     
    PAPER

      Vol:
    E96-C No:6
      Page(s):
    859-866

    This paper proposes a novel approach for implementing an ultra-low-power voltage reference using the structure of self-cascode MOSFET, operating in the subthreshold region with a self-biased body effect. The difference between the two gate-source voltages in the structure enables the voltage reference circuit to produce a low output voltage below the threshold voltage. The circuit is designed with only MOSFETs and fabricated in standard 0.18-µm CMOS technology. Measurements show that the reference voltage is about 107.5 mV, and the temperature coefficient is about 40 ppm/, at a range from -20 to 80. The voltage line sensitivity is 0.017%/V. The minimum supply voltage is 0.85 V, and the supply current is approximately 24 nA at 80. The occupied chip area is around 0.028 mm2.

  • Energy Minimization over m-Branched Enumeration for Generalized Linear Subspace Clustering Open Access

    Chao ZHANG  

     
    PAPER-Artificial Intelligence, Data Mining

      Pubricized:
    2019/09/19
      Vol:
    E102-D No:12
      Page(s):
    2485-2492

    In this paper, we consider the clustering problem of independent general subspaces. That is, with given data points lay near or on the union of independent low-dimensional linear subspaces, we aim to recover the subspaces and assign the corresponding label to each data point. To settle this problem, we take advantages of both greedy strategy and energy minimization strategy to propose a simple yet effective algorithm based on the assumption that an m-branched (i.e., perfect m-ary) tree which is constructed by collecting m-nearest neighbor points in each node has a high probability of containing the near-exact subspace. Specifically, at first, subspace candidates are enumerated by multiple m-branched trees. Each tree starts with a data point and grows by collecting nearest neighbors in the breadth-first search order. Then, subspace proposals are further selected from the enumeration to initialize the energy minimization algorithm. Eventually, both the proposals and the labeling result are finalized by iterative re-estimation and labeling. Experiments with both synthetic and real-world data show that the proposed method can outperform state-of-the-art methods and is practical in real application.

  • Networked Control System with Delay Adaptive Cyber-Physical Integration

    Chao ZHANG  Jialuo XIAO  

     
    LETTER-Systems and Control

      Vol:
    E97-A No:3
      Page(s):
    873-876

    A Networked Control System (NCS) can be considered a form of Cyber-Physical System (CPS) with its network architecture and typical features, such as delay, jitter and package loss. So far, less discussion has been carried out for NCS from the view point of CPS. In this letter, the NCS with short delay is analyzed with cyber-physical integration. The sampling rate is depicted as one of the states in the state equations. The simulation results show that the cyber-physical integration not only adjusts the sampling rate to the states of the controlled physical system, but also adapts to the delay of the network. The averaged sampling rate and the stabilization time are smaller compared with the traditional NCS.

  • N-Shift Zero Correlation Zone Sequence

    Chao ZHANG  Keke PANG  

     
    LETTER-Spread Spectrum Technologies and Applications

      Vol:
    E97-A No:1
      Page(s):
    432-435

    N-Shift Zero Correlation Zone (NS-ZCZ) sequence is defined with the N-shift zero correlation zone in the correlation function. Namely, the N-shift zero only appears within the correlation zone symmetrically distributed in the center of the correlation function. Moreover, the traditional ZCZ sequences can be considered as the N-shift ZCZ sequence with N=1. Similar to ZCZ sequence, NS-ZCZ sequences can be applied in sequence design for co-channel interference mitigation with more sequences in the sequence set compared with the traditional N-shift sequences. In this letter, the definition and construction algorithms are proposed. The corresponding theoretical bounds are analyzed.

  • Blind Compressive Sensing Detection of Watermark Coded by Limited-Random Sequence

    Chao ZHANG  Jialuo XIAO  Yaxin ZHANG  

     
    LETTER

      Vol:
    E98-A No:8
      Page(s):
    1747-1750

    Due to the fact that natural images are approximately sparse in Discrete Cosine Transform (DCT) or wavelet basis, the Compressive Sensing (CS) can be employed to decode both the host image and watermark with zero error, despite not knowing the host image. In this paper, Limited-Random Sequence (LRS) matrix is utilized to implement the blind CS detection, which benefits from zero error and lower complexity. The performance in Bit Error Rate (BER) and error-free detection probability confirms the validity and efficiency of the proposed scheme.

  • The Design of a Monolithic MSTP ASIC

    Peng WANG  Chao ZHANG  Nan HUA  De-peng JIN  Lie-guang ZENG  

     
    PAPER-Integrated Electronics

      Vol:
    E89-C No:8
      Page(s):
    1248-1254

    A highly integrated monolithic Multi-Service Transport Platform (MSTP) ASIC MSEOSX8-6 incorporating more than 26M transistors has been fabricated with 0.18 µm CMOS technology. The chip is a powerful monolithic MSTP ASIC that supports RPR applications and serves as a generic building block for MSTP network. To accelerate the chip design, we devise a novel methodology called Embedded Reduced Self-Tester (ERST), which integrates the reduced self-tester structure into the chip to shorten the duration of dynamic simulation. Moreover, we divide the design into 12 smaller Hierarchical Layout Blocks (HLB) to enable parallel layout. Resultantly, the whole design has been completed in 5 months, which saves at least 80% of the design cycle in all.

  • Adaptive CI-OSDM in Time-Frequency Selective Fading Channel

    Xiaoming TAO  Chao ZHANG  Jianhua LU  Naoki SUEHIRO  

     
    PAPER-Spread Spectrum Communications

      Vol:
    E91-A No:12
      Page(s):
    3712-3722

    Orthogonal Signal Division Multiplexing (OSDM), also known as SD-OFDM, has been proposed for information transmission with high spectrum efficiency. In this paper, a new signal construction method named Adaptive Carrier Interferometry OSDM (ACI-OSDM) is proposed for time-frequency selective fading channel. Particularly, the Adaptive CI codes originated from CI-OFDM are employed in the frequency domain of OSDM signal. Compared with traditional OFDM, the ACI-OSDM improves the performance considerably of broadband transmission, i.e., spectrum efficiency, Peak-to-Average Power Ratio (PAPR) mitigation and interference cancelation in the high speed mobile environment with multipath emission, e.g. super express train with speed more than 250 km/h.

  • A Low Complexity Tree-Structure Based User Scheduling Algorithm for Up-Link Multi-User MIMO Systems

    Junyi WANG  Kiyomichi ARAKI  Zhongzhao ZHANG  Yuyuan CHANG  Houtao ZHU  Tsuyoshi KASHIMA  

     
    PAPER-Wireless Communication Technologies

      Vol:
    E90-B No:6
      Page(s):
    1415-1423

    The paper describes a low complexity tree-structure based user scheduling algorithm in an up-link transmission of MLD-based multi-user multiple-input multiple-output (MIMO) wireless systems. An M-branch selection algorithm, which selects M most-possible best branches at each step, is proposed to maximize the whole system sum-rate capacity. To achieve the maximum capacity in multi-user MIMO systems, antennas configuration and user selection are preformed simultaneously. Then according to the selected number of antennas for each user, different transmission schemes are also adopted. Both the theoretical analysis and simulation results show that the proposed algorithms obtain near optimal performance with far low complexity than the full search procedure.

  • Robust Visual Tracking via Coupled Randomness

    Chao ZHANG  Yo YAMAGATA  Takuya AKASHI  

     
    PAPER-Image Recognition, Computer Vision

      Pubricized:
    2015/02/04
      Vol:
    E98-D No:5
      Page(s):
    1080-1088

    Tracking algorithms for arbitrary objects are widely researched in the field of computer vision. At the beginning, an initialized bounding box is given as the input. After that, the algorithms are required to track the objective in the later frames on-the-fly. Tracking-by-detection is one of the main research branches of online tracking. However, there still exist two issues in order to improve the performance. 1) The limited processing time requires the model to extract low-dimensional and discriminative features from the training samples. 2) The model is required to be able to balance both the prior and new objectives' appearance information in order to maintain the relocation ability and avoid the drifting problem. In this paper, we propose a real-time tracking algorithm called coupled randomness tracking (CRT) which focuses on dealing with these two issues. One randomness represents random projection, and the other randomness represents online random forests (ORFs). In CRT, the gray-scale feature is compressed by a sparse measurement matrix, and ORFs are used to train the sample sequence online. During the training procedure, we introduce a tree discarding strategy which helps the ORFs to adapt fast appearance changes caused by illumination, occlusion, etc. Our method can constantly adapt to the objective's latest appearance changes while keeping the prior appearance information. The experimental results show that our algorithm performs robustly with many publicly available benchmark videos and outperforms several state-of-the-art algorithms. Additionally, our algorithm can be easily utilized into a parallel program.

  • Vertical Link On/Off Regulations for Inductive-Coupling Based Wireless 3-D NoCs

    Hao ZHANG  Hiroki MATSUTANI  Yasuhiro TAKE  Tadahiro KURODA  Hideharu AMANO  

     
    PAPER-Computer System

      Vol:
    E96-D No:12
      Page(s):
    2753-2764

    We propose low-power techniques for wireless three-dimensional Network-on-Chips (wireless 3-D NoCs), in which the connections among routers on the same chip are wired while the routers on different chips are connected wirelessly using inductive-coupling. The proposed low-power techniques stop the clock and power supplies to the transmitter of the wireless vertical links only when their utilizations are higher than the threshold. Meanwhile, the whole wireless vertical link will be shut down when the utilization is lower than the threshold in order to reduce the power consumption of wireless 3-D NoCs. This paper uses an on-demand method, in which the dormant data transmitter or the whole vertical link will be activated as long as a flit comes. Full-system many-core simulations using power parameters derived from a real chip implementation show that the proposed low-power techniques reduce the power consumption by 23.4%-29.3%, while the performance overhead is less than 2.4%.

  • Design of a Compact Triple-Mode Dielectric Resonator BPF with Wide Spurious-Free Performance Open Access

    Fan LIU  Zhewang MA  Weihao ZHANG  Masataka OHIRA  Dongchun QIAO  Guosheng PU  Masaru ICHIKAWA  

     
    PAPER

      Pubricized:
    2022/03/30
      Vol:
    E105-C No:11
      Page(s):
    660-666

    A novel compact 5-pole bandpass filter (BPF) using two different types of resonators, one is coaxial TEM-mode resonator and the other dielectric triple-mode resonator, is proposed in this paper. The coaxial resonator is a simple single-mode resonator, while the triple-mode dielectric resonator (DR) includes one TM01δ mode and two degenerate HE11 modes. An excellent spurious performance of the BPF is obtained due to the different resonant behaviors of these two types of resonators used in the BPF. The coupling scheme of the 5-pole BPF includes two cascade triplets (CTs) which produce two transmission zeros (TZs) and a sharp skirt of the passband. Behaviors of the resonances, the inter-resonance couplings, as well as their tuning methods are investigated in detail. A procedure of mapping the coupling matrix of the BPF to its physical dimensions is developed, and an optimization of these physical dimensions is implemented to achieve best performance of the filter. The designed BPF is operated at 1.84GHz with a bandwidth of 51MHz. The stopband rejection is better than 20dB up to 9.7GHz (about 5.39×f0) except 7.85GHz. Good agreement between the designed and theoretically synthesized responses of the BPF is reached, verifying well the proposed configuration of the BPF and its design method.

  • Two Dimensional Combined Complementary Sequence and Its Application in Multi-Carrier CDMA

    Chao ZHANG  Xiaokang LIN  Mitsutoshi HATORI  

     
    PAPER

      Vol:
    E88-B No:2
      Page(s):
    478-486

    Multi-Carrier CDMA (MC-CDMA) has been considered as a combination of the techniques of Code Division Multiple Access (CDMA) and Orthogonal Frequency Division Multiplex (OFDM). However, even until now, the efficient MC-CDMA scheme is still under study because of the inherent bugs in OFDM, such as the troubles caused by Multiple Access Interference (MAI) and Peak to Average Power Ratio (PAPR). In this paper, we present a novel two-dimensional spreading sequence named "Two Dimensional Combined Complementary Sequence" (TDC). If we take this kind of sequences as spreading codes, several prominent advantages can be achieved compared with traditional MC-CDMA. First, it can achieve MAI free in the multi-path transmission both in uplink and downlink. Second, it offers low PAPR value within 3 dB with a quite simple architecture. The last but not the least, the proposed MC-CDMA scheme turns out to be an efficient approach with high bandwidth efficiency, high spreading efficiency and flexible transmission rate enriched by a special shift-and-add modulation. Meanwhile, an algorithm that constructs TDC sequences is discussed in details. Based on above results, we can get the conclusion that the novel TDC sequences and corresponding MC-CDMA architecture have great potential for applications in next generation wireless mobile communications, which require high transmission rate in hostile and complicated channels.

  • On the Minimum Distance of Some Improper Array Codes

    Haiyang LIU  Lianrong MA  Hao ZHANG  

     
    LETTER-Coding Theory

      Vol:
    E102-A No:12
      Page(s):
    2021-2026

    For an odd prime q and an integer m≤q, we can construct a regular quasi-cyclic parity-check matrix HI(m,q) that specifies a linear block code CI(m,q), called an improper array code. In this letter, we prove the minimum distance of CI(4,q) is equal to 10 for any q≥11. In addition, we prove the minimum distance of CI(5,q) is upper bounded by 12 for any q≥11 and conjecture the upper bound is tight.

  • Adaptive Analog-to-Information Converter Design with Limited Random Sequence Modulation

    Chao ZHANG  Jialuo XIAO  

     
    PAPER

      Vol:
    E96-A No:2
      Page(s):
    469-476

    Compressive sensing enables quite lower sampling rate compared with Nyquist sampling. As long as the signal is sparsity in some basis, the random sampling with CS can be employed. In order to make CS applied in the practice, the Analog to Information Converter (AIC) should be involved. Based on the Limited Random Sequence (LRS) modulation, the AIC with LRS can be designed with high performance according to the fixed sparsity. However, if the sparsity of the signal varies with time, the original AIC with LRS is not efficient. In this paper, the adaptive AIC which adapts its scheme of LRS according to the variation of the sparsity is proposed and the prototype system is designed. Due to the adaption of the AIC with the scheme of LRS, the sampling rate can be further reduced. The simulation results confirm the performance of the proposed adaptive AIC scheme. The prototype system can successfully fulfil the random sampling and adapt to the variation of sparsity, which verify and consolidate the validity and feasibility for the future implementation of adaptive AIC on chip.

  • Novel Sequence Pair and Set with Three Zero Correlation Windows

    Chao ZHANG  Xiaokang LIN  Mitsutoshi HATORI  

     
    PAPER-Fundamental Theories for Communications

      Vol:
    E88-B No:4
      Page(s):
    1517-1522

    In this paper, we present a set of sequence pairs which produce zero correlation windows not only in the middle part of the sum of aperiodic correlation functions, but also in the two terminal parts. We name it "Ear Windows." In approximately synchronous CDMA communication system, this set of sequences is able to completely remove the inter-symbol interference (ISI) and multi-user interference (MUI) caused by the multi-path effect if the maximum delay is shorter than the length of the "Ear windows." In addition, it is also feasible in M-ary modulation. The inter-code interference will be mitigated drastically.

41-60hit(60hit)