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  • Pre-T Event-Triggered Controller with a Gain-Scaling Factor for a Chain of Integrators and Its Extension to Strict-Feedback Nonlinearity Open Access

    Ho-Lim CHOI  

     
    LETTER-Systems and Control

      Pubricized:
    2024/04/30
      Vol:
    E107-A No:9
      Page(s):
    1561-1564

    We propose a pre-T event-triggered controller (ETC) for the stabilization of a chain of integrators. Our per-T event-triggered controller is a modified event-triggered controller by adding a pre-defined positive constant T to the event-triggering condition. With this pre-T, the immediate advantages are (i) the often complicated additional analysis regarding the Zeno behavior is no longer needed, (ii) the positive lower bound of interexecution times can be specified, (iii) the number of control input updates can be further reduced. We carry out the rigorous system analysis and simulations to illustrate the advantages of our proposed method over the traditional event-triggered control method.

  • Investigating and Enhancing the Neural Distinguisher for Differential Cryptanalysis Open Access

    Gao WANG  Gaoli WANG  Siwei SUN  

     
    PAPER-Information Network

      Pubricized:
    2024/04/12
      Vol:
    E107-D No:8
      Page(s):
    1016-1028

    At Crypto 2019, Gohr first adopted the neural distinguisher for differential cryptanalysis, and since then, this work received increasing attention. However, most of the existing work focuses on improving and applying the neural distinguisher, the studies delving into the intrinsic principles of neural distinguishers are finite. At Eurocrypt 2021, Benamira et al. conducted a study on Gohr’s neural distinguisher. But for the neural distinguishers proposed later, such as the r-round neural distinguishers trained with k ciphertext pairs or ciphertext differences, denoted as NDcpk_r (Gohr’s neural distinguisher is the special NDcpk_r with K = 1) and NDcdk_r , such research is lacking. In this work, we devote ourselves to study the intrinsic principles and relationship between NDcdk_r and NDcpk_r. Firstly, we explore the working principle of NDcd1_r through a series of experiments and find that it strongly relies on the probability distribution of ciphertext differences. Its operational mechanism bears a strong resemblance to that of NDcp1_r given by Benamira et al.. Therefore, we further compare them from the perspective of differential cryptanalysis and sample features, demonstrating the superior performance of NDcp1_r can be attributed to the relationships between certain ciphertext bits, especially the significant bits. We then extend our investigation to NDcpk_r, and show that its ability to recognize samples heavily relies on the average differential probability of k ciphertext pairs and some relationships in the ciphertext itself, but the reliance between k ciphertext pairs is very weak. Finally, in light of the findings of our research, we introduce a strategy to enhance the accuracy of the neural distinguisher by using a fixed difference to generate the negative samples instead of the random one. Through the implementation of this approach, we manage to improve the accuracy of the neural distinguishers by approximately 2% to 8% for 7-round Speck32/64 and 9-round Simon32/64.

  • Advance Sharing of Quantum Shares for Quantum Secrets Open Access

    Mamoru SHIBATA  Ryutaroh MATSUMOTO  

     
    PAPER-Information Theory

      Pubricized:
    2023/11/24
      Vol:
    E107-A No:8
      Page(s):
    1247-1254

    Secret sharing is a cryptographic scheme to encode a secret to multiple shares being distributed to participants, so that only qualified sets of participants can restore the original secret from their shares. When we encode a secret by a secret sharing scheme and distribute shares, sometimes not all participants are accessible, and it is desirable to distribute shares to those participants before a secret information is determined. Secret sharing schemes for classical secrets have been known to be able to distribute some shares before a given secret. Lie et al. found a ((2, 3))-threshold secret sharing for quantum secrets can distribute some shares before a given secret. However, it is unknown whether distributing some shares before a given secret is possible with other access structures of secret sharing for quantum secrets. We propose a quantum secret sharing scheme for quantum secrets that can distribute some shares before a given secret with other access structures.

  • Constructions of 2-Correlation Immune Rotation Symmetric Boolean Functions Open Access

    Jiao DU  Ziwei ZHAO  Shaojing FU  Longjiang QU  Chao LI  

     
    PAPER-Cryptography and Information Security

      Pubricized:
    2024/03/22
      Vol:
    E107-A No:8
      Page(s):
    1241-1246

    In this paper, we first recall the concept of 2-tuples distribution matrix, and further study its properties. Based on these properties, we find four special classes of 2-tuples distribution matrices. Then, we provide a new sufficient and necessary condition for n-variable rotation symmetric Boolean functions to be 2-correlation immune. Finally, we give a new method for constructing such functions when n=4t - 1 is prime, and we show an illustrative example.

  • Privacy Preserving Function Evaluation Using Lookup Tables with Word-Wise FHE Open Access

    Ruixiao LI  Hayato YAMANA  

     
    PAPER-Cryptography and Information Security

      Pubricized:
    2023/11/16
      Vol:
    E107-A No:8
      Page(s):
    1163-1177

    Homomorphic encryption (HE) is a promising approach for privacy-preserving applications, enabling a third party to assess functions on encrypted data. However, problems persist in implementing privacy-preserving applications through HE, including 1) long function evaluation latency and 2) limited HE primitives only allowing us to perform additions and multiplications. A homomorphic lookup-table (LUT) method has emerged to solve the above problems and enhance function evaluation efficiency. By leveraging homomorphic LUTs, intricate operations can be substituted. Previously proposed LUTs use bit-wise HE, such as TFHE, to evaluate single-input functions. However, the latency increases with the bit-length of the function’s input(s) and output. Additionally, an efficient implementation of multi-input functions remains an open question. This paper proposes a novel LUT-based privacy-preserving function evaluation method to handle multi-input functions while reducing the latency by adopting word-wise HE. Our optimization strategy adjusts table sizes to minimize the latency while preserving function output accuracy, especially for common machine-learning functions. Through our experimental evaluation utilizing the BFV scheme of the Microsoft SEAL library, we confirmed the runtime of arbitrary functions whose LUTs consist of all input-output combinations represented by given input bits: 1) single-input 12-bit functions in 0.14 s, 2) single-input 18-bit functions in 2.53 s, 3) two-input 6-bit functions in 0.17 s, and 4) three-input 4-bit functions in 0.20 s, employing four threads. Besides, we confirmed that our proposed table size optimization strategy worked well, achieving 1.2 times speed up with the same absolute error of order of magnitude of -4 (a × 10-4 where 1/$\sqrt{10}$ ≤ a < $\sqrt{10})$ for Swish and 1.9 times speed up for ReLU while decreasing the absolute error from order -2 to -4 compared to the baseline, i.e., polynomial approximation.

  • A Multi-Channel Biomedical Sensor System with System-Level Chopping and Stochastic A/D Conversion Open Access

    Yusaku HIRAI  Toshimasa MATSUOKA  Takatsugu KAMATA  Sadahiro TANI  Takao ONOYE  

     
    PAPER-Circuit Theory

      Pubricized:
    2024/02/09
      Vol:
    E107-A No:8
      Page(s):
    1127-1138

    This paper presents a multi-channel biomedical sensor system with system-level chopping and stochastic analog-to-digital (A/D) conversion techniques. The system-level chopping technique extends the input-signal bandwidth and reduces the interchannel crosstalk caused by multiplexing. The system-level chopping can replace an analog low-pass filter (LPF) with a digital filter and can reduce its area occupation. The stochastic A/D conversion technique realizes power-efficient resolution enhancement. A novel auto-calibration technique is also proposed for the stochastic A/D conversion technique. The proposed system includes a prototype analog front-end (AFE) IC fabricated using a 130 nm CMOS process. The fabricated AFE IC improved its interchannel crosstalk by 40 dB compared with the conventional analog chopping architecture. The AFE IC achieved SNDR of 62.9 dB at a sampling rate of 31.25 kSps while consuming 9.6 μW from a 1.2 V power supply. The proposed resolution enhancement technique improved the measured SNDR by 4.5 dB.

  • Dynamic Limited Variable Step-Size Algorithm Based on the MSD Variation Cost Function Open Access

    Yufei HAN  Jiaye XIE  Yibo LI  

     
    LETTER-Digital Signal Processing

      Pubricized:
    2023/09/11
      Vol:
    E107-A No:6
      Page(s):
    919-922

    The steady-state and convergence performances are important indicators to evaluate adaptive algorithms. The step-size affects these two important indicators directly. Many relevant scholars have also proposed some variable step-size adaptive algorithms for improving performance. However, there are still some problems in these existing variable step-size adaptive algorithms, such as the insufficient theoretical analysis, the imbalanced performance and the unachievable parameter. These problems influence the actual performance of some algorithms greatly. Therefore, we intend to further explore an inherent relationship between the key performance and the step-size in this paper. The variation of mean square deviation (MSD) is adopted as the cost function. Based on some theoretical analyses and derivations, a novel variable step-size algorithm with a dynamic limited function (DLF) was proposed. At the same time, the sufficient theoretical analysis is conducted on the weight deviation and the convergence stability. The proposed algorithm is also tested with some typical algorithms in many different environments. Both the theoretical analysis and the experimental result all have verified that the proposed algorithm equips a superior performance.

  • High-Throughput Exact Matching Implementation on FPGA with Shared Rule Tables among Parallel Pipelines Open Access

    Xiaoyong SONG  Zhichuan GUO  Xinshuo WANG  Mangu SONG  

     
    PAPER-Network System

      Vol:
    E107-B No:5
      Page(s):
    387-397

    In software defined network (SDN), packet processing is commonly implemented using match-action model, where packets are processed based on matched actions in match action table. Due to the limited FPGA on-board resources, it is an important challenge to achieve large-scale high throughput based on exact matching (EM), while solving hash conflicts and out-of-order problems. To address these issues, this study proposed an FPGA-based EM table that leverages shared rule tables across multiple pipelines to eliminate memory replication and enhance overall throughput. An out-of-order reordering function is used to ensure packet sequencing within the pipelines. Moreover, to handle collisions and increase load factor of hash table, multiple hash table blocks are combined and an auxiliary CAM-based EM table is integrated in each pipeline. To the best of our knowledge, this is the first time that the proposed design considers the recovery of out-of-order operations in multi-channel EM table for high-speed network packets processing application. Furthermore, it is implemented on Xilinx Alveo U250 field programmable gate arrays, which has a million rules and achieves a processing speed of 200 million operations per second, theoretically enabling throughput exceeding 100 Gbps for 64-Byte size packets.

  • A Small-Data Solution to Data-Driven Lyapunov Equations: Data Reduction from O(n2) to O(n) Open Access

    Keitaro TSUJI  Shun-ichi AZUMA  Ikumi BANNO  Ryo ARIIZUMI  Toru ASAI  Jun-ichi IMURA  

     
    PAPER

      Pubricized:
    2023/10/24
      Vol:
    E107-A No:5
      Page(s):
    806-812

    When a mathematical model is not available for a dynamical system, it is reasonable to use a data-driven approach for analysis and control of the system. With this motivation, the authors have recently developed a data-driven solution to Lyapunov equations, which uses not the model but the data of several state trajectories of the system. However, the number of state trajectories to uniquely determine the solution is O(n2) for the dimension n of the system. This prevents us from applying the method to a case with a large n. Thus, this paper proposes a novel class of data-driven Lyapunov equations, which requires a smaller amount of data. Although the previous method constructs one scalar equation from one state trajectory, the proposed method constructs three scalar equations from any combination of two state trajectories. Based on this idea, we derive data-driven Lyapunov equations such that the number of state trajectories to uniquely determine the solution is O(n).

  • A Trie-Based Authentication Scheme for Approximate String Queries Open Access

    Yu WANG  Liangyong YANG  Jilian ZHANG  Xuelian DENG  

     
    PAPER-Data Engineering, Web Information Systems

      Pubricized:
    2023/12/20
      Vol:
    E107-D No:4
      Page(s):
    537-543

    Cloud computing has become the mainstream computing paradigm nowadays. More and more data owners (DO) choose to outsource their data to a cloud service provider (CSP), who is responsible for data management and query processing on behalf of DO, so as to cut down operational costs for the DO.  However, in real-world applications, CSP may be untrusted, hence it is necessary to authenticate the query result returned from the CSP.  In this paper, we consider the problem of approximate string query result authentication in the context of database outsourcing. Based on Merkle Hash Tree (MHT) and Trie, we propose an authenticated tree structure named MTrie for authenticating approximate string query results. We design efficient algorithms for query processing and query result authentication. To verify effectiveness of our method, we have conducted extensive experiments on real datasets and the results show that our proposed method can effectively authenticate approximate string query results.

  • Performance Comparison of the Two Reconstruction Methods for Stabilizer-Based Quantum Secret Sharing

    Shogo CHIWAKI  Ryutaroh MATSUMOTO  

     
    LETTER-Quantum Information Theory

      Pubricized:
    2023/09/20
      Vol:
    E107-A No:3
      Page(s):
    526-529

    Stabilizer-based quantum secret sharing has two methods to reconstruct a quantum secret: The erasure correcting procedure and the unitary procedure. It is known that the unitary procedure has a smaller circuit width. On the other hand, it is unknown which method has smaller depth and fewer circuit gates. In this letter, it is shown that the unitary procedure has smaller depth and fewer circuit gates than the erasure correcting procedure which follows a standard framework performing measurements and unitary operators according to the measurements outcomes, when the circuits are designed for quantum secret sharing using the [[5, 1, 3]] binary stabilizer code. The evaluation can be reversed if one discovers a better circuit for the erasure correcting procedure which does not follow the standard framework.

  • An Output Voltage Estimation and Regulation System Using Only the Primary-Side Electrical Parameters for Wireless Power Transfer Circuits

    Takahiro FUJITA  Kazuyuki WADA  Kawori SEKINE  

     
    PAPER

      Pubricized:
    2023/07/24
      Vol:
    E107-A No:1
      Page(s):
    16-24

    An output voltage estimation and regulation system for a wireless power transfer (WPT) circuit is proposed. Since the fluctuation of a coupling condition and/or a load may vary the voltage supplied with WPT resulting in a malfunction of wireless-powered devices, the output voltage regulation is needed. If the output voltage is regulated by a voltage regulator in a secondary side of the WPT circuit with fixed input power, the voltage regulator wastes the power to regulate the voltage. Therefore the output voltage regulation using a primary-side control, which adjusts the input power depending on the load and/or the coupling condition, is a promising approach for efficient regulation. In addition, it is desirable to eliminate feedback loop from the secondary side to the primary side from the viewpoint of reducing power dissipation and system complexity. The proposed system can estimate and regulate the output voltage independent of both the coupling and the load variation without the feedback loop. An usable range of the coupling coefficient and the load is improved compared to previous works. The validity of the proposed system is confirmed by the SPICE simulator.

  • IGDM: An Information Geometric Difference Mapping Method for Signal Detection in Non-Gaussian Alpha-Stable Distributed Noise

    Jiansheng BAI  Jinjie YAO  Yating HOU  Zhiliang YANG  Liming WANG  

     
    PAPER-Fundamental Theories for Communications

      Pubricized:
    2023/08/25
      Vol:
    E106-B No:12
      Page(s):
    1392-1401

    Modulated signal detection has been rapidly advancing in various wireless communication systems as it's a core technology of spectrum sensing. To address the non-Gaussian statistical of noise in radio channels, especially its pulse characteristics in the time/frequency domain, this paper proposes a method based on Information Geometric Difference Mapping (IGDM) to solve the signal detection problem under Alpha-stable distribution (α-stable) noise and improve performance under low Generalized Signal-to-Noise Ratio (GSNR). Scale Mixtures of Gaussians is used to approximate the probability density function (PDF) of signals and model the statistical moments of observed data. Drawing on the principles of information geometry, we map the PDF of different types of data into manifold space. Through the application of statistical moment models, the signal is projected as coordinate points within the manifold structure. We then design a dual-threshold mechanism based on the geometric mean and use Kullback-Leibler divergence (KLD) to measure the information distance between coordinates. Numerical simulations and experiments were conducted to prove the superiority of IGDM for detecting multiple modulated signals in non-Gaussian noise, the results show that IGDM has adaptability and effectiveness under extremely low GSNR.

  • Loosely-Stabilizing Algorithm on Almost Maximal Independent Set

    Rongcheng DONG  Taisuke IZUMI  Naoki KITAMURA  Yuichi SUDO  Toshimitsu MASUZAWA  

     
    PAPER-Fundamentals of Information Systems

      Pubricized:
    2023/08/07
      Vol:
    E106-D No:11
      Page(s):
    1762-1771

    The maximal independent set (MIS) problem is one of the most fundamental problems in the field of distributed computing. This paper focuses on the MIS problem with unreliable communication between processes in the system. We propose a relaxed notion of MIS, named almost MIS (ALMIS), and show that the loosely-stabilizing algorithm proposed in our previous work can achieve exponentially long holding time with logarithmic convergence time and space complexity regarding ALMIS, which cannot be achieved at the same time regarding MIS in our previous work.

  • A Novel Quad-Band Branched Monopole Antenna with a Filter Suppressing Higher Order Modes

    Shingo YAMAURA  Kengo NISHIMOTO  Yasuhiro NISHIOKA  Ryosuke KOBAYASHI  Takahiro INO  Yoshio INASAWA  

     
    PAPER-Antennas and Propagation

      Pubricized:
    2023/05/16
      Vol:
    E106-B No:10
      Page(s):
    938-948

    This paper proposes a novel quad-band branched monopole antenna with a filter. The proposed antenna has a simple configuration in which branch-elements are added to a basic configuration consisting of a mast and dielectric wires. The antenna is characterized by performances such as wideband impedance matching, gain stabilization, and gain enhancement. Wideband impedance characteristics satisfying the voltage standing ratio of less than 2 are obtained by exciting a parallel resonance at the lowest band and multi-resonance at high bands. The filter suppressing higher order modes is used for gain stabilization, so that averaged gains above 5dBi are obtained at the quad-band. The antenna has a high gain of 11.1dBi because the branch-elements work as an end-fire array antenna at the highest band. Furthermore, it is clarified that an operating frequency is switched by using a variable bandpass filter at the lowest band. Last, a scale model of the antenna is fabricated and measured, then the effectiveness of the proposed antenna is demonstrated.

  • Local-to-Global Structure-Aware Transformer for Question Answering over Structured Knowledge

    Yingyao WANG  Han WANG  Chaoqun DUAN  Tiejun ZHAO  

     
    PAPER-Artificial Intelligence, Data Mining

      Pubricized:
    2023/06/27
      Vol:
    E106-D No:10
      Page(s):
    1705-1714

    Question-answering tasks over structured knowledge (i.e., tables and graphs) require the ability to encode structural information. Traditional pre-trained language models trained on linear-chain natural language cannot be directly applied to encode tables and graphs. The existing methods adopt the pre-trained models in such tasks by flattening structured knowledge into sequences. However, the serialization operation will lead to the loss of the structural information of knowledge. To better employ pre-trained transformers for structured knowledge representation, we propose a novel structure-aware transformer (SATrans) that injects the local-to-global structural information of the knowledge into the mask of the different self-attention layers. Specifically, in the lower self-attention layers, SATrans focus on the local structural information of each knowledge token to learn a more robust representation of it. In the upper self-attention layers, SATrans further injects the global information of the structured knowledge to integrate the information among knowledge tokens. In this way, the SATrans can effectively learn the semantic representation and structural information from the knowledge sequence and the attention mask, respectively. We evaluate SATrans on the table fact verification task and the knowledge base question-answering task. Furthermore, we explore two methods to combine symbolic and linguistic reasoning for these tasks to solve the problem that the pre-trained models lack symbolic reasoning ability. The experiment results reveal that the methods consistently outperform strong baselines on the two benchmarks.

  • A New Characterization of 2-Resilient Rotation Symmetric Boolean Functions

    Jiao DU  Ziyu CHEN  Le DONG  Tianyin WANG  Shanqi PANG  

     
    LETTER-Cryptography and Information Security

      Pubricized:
    2023/03/09
      Vol:
    E106-A No:9
      Page(s):
    1268-1271

    In this paper, the notion of 2-tuples distribution matrices of the rotation symmetric orbits is proposed, by using the properties of the 2-tuples distribution matrix, a new characterization of 2-resilient rotation symmetric Boolean functions is demonstrated. Based on the new characterization of 2-resilient rotation symmetric Boolean functions, constructions of 2-resilient rotation symmetric Boolean functions (RSBFs) are further studied, and new 2-resilient rotation symmetric Boolean functions with prime variables are constructed.

  • Information Recovery for Signals Intercepted by Dual-Channel Nyquist Folding Receiver with Adjustable Local Oscillator

    Xinqun LIU  Tao LI  Yingxiao ZHAO  Jinlin PENG  

     
    BRIEF PAPER-Electronic Circuits

      Pubricized:
    2023/03/24
      Vol:
    E106-C No:8
      Page(s):
    446-449

    Conventional Nyquist folding receiver (NYFR) uses zero crossing rising (ZCR) voltage times to control the RF sample clock, which is easily affected by noise. Moreover, the analog and digital parts are not synchronized so that the initial phase of the input signal is lost. Furthermore, it is assumed in most literature that the input signal is in a single Nyquist zone (NZ), which is inconsistent with the actual situation. In this paper, we propose an improved architecture denominated as a dual-channel NYFR with adjustable local oscillator (LOS) and an information recovery algorithm. The simulation results demonstrate the validity and viability of the proposed architecture and the corresponding algorithm.

  • Photochemical Stability of Organic Electro-Optic Polymer at 1310-nm Wavelength Open Access

    Yukihiro TOMINARI  Toshiki YAMADA  Takahiro KAJI  Akira OTOMO  

     
    BRIEF PAPER

      Pubricized:
    2022/11/10
      Vol:
    E106-C No:6
      Page(s):
    228-231

    We investigated the photochemical stability of an electro-optic (EO) polymer under laser irradiation at 1310nm to reveal photodegradation mechanisms. It was found that one-photon absorption excitation assisted with the thermal energy at the temperature is involved in the photodegradation process, in contrast to our previous studies at a wavelength of 1550nm where two-photon absorption excitation is involved in the photodegradation process. Thus, both the excitation wavelength and the thermal energy strongly affect to the degradation mechanism. In any cases, the photodegradation of EO polymers is mainly related to the generation of exited singlet oxygen.

  • Alternative Ruleset Discovery to Support Black-Box Model Predictions

    Yoichi SASAKI  Yuzuru OKAJIMA  

     
    PAPER-Artificial Intelligence, Data Mining

      Pubricized:
    2023/03/09
      Vol:
    E106-D No:6
      Page(s):
    1130-1141

    The increasing attention to the interpretability of machine learning models has led to the development of methods to explain the behavior of black-box models in a post-hoc manner. However, such post-hoc approaches generate a new explanation for every new input, and these explanations cannot be checked by humans in advance. A method that selects decision rules from a finite ruleset as explanation for neural networks has been proposed, but it cannot be used for other models. In this paper, we propose a model-agnostic explanation method to find a pre-verifiable finite ruleset from which a decision rule is selected to support every prediction made by a given black-box model. First, we define an explanation model that selects the rule, from a ruleset, that gives the closest prediction; this rule works as an alternative explanation or supportive evidence for the prediction of a black-box model. The ruleset should have high coverage to give close predictions for future inputs, but it should also be small enough to be checkable by humans in advance. However, minimizing the ruleset while keeping high coverage leads to a computationally hard combinatorial problem. Hence, we show that this problem can be reduced to a weighted MaxSAT problem composed only of Horn clauses, which can be efficiently solved with modern solvers. Experimental results showed that our method found small rulesets such that the rules selected from them can achieve higher accuracy for structured data as compared to the existing method using rulesets of almost the same size. We also experimentally compared the proposed method with two purely rule-based models, CORELS and defragTrees. Furthermore, we examine rulesets constructed for real datasets and discuss the characteristics of the proposed method from different viewpoints including interpretability, limitation, and possible use cases.

1-20hit(983hit)