研究者業績
基本情報
- 所属
- 千葉大学 大学院情報学研究院 教授湘潭大学 Xiangtan University Honored Professor長崎総合科学大学 客員教授
- 学位
- 博士（工学）(慶應義塾大学)
- ORCID ID
https://orcid.org/0000-0003-3557-1463- J-GLOBAL ID
- 200901086143684628
- researchmap会員ID
- 1000357243
- 外部リンク
令和6年- 千葉大学大学院情報学研究院教授
平成30年-令和6年 千葉大学大学院工学研究院 教授
平成28年-平成30年 千葉大学大学院融合科学研究科 教授
平成27年-令和2年 湘潭大学(Xiangtan University) Honorary Professor
平成23年-平成28年 千葉大学大学院融合科学研究科 准教授
平成20年-平成22年 Wright State University 訪問研究員(日本学術振興会海外特別研究員)
平成19年-平成23年 千葉大学大学院融合科学研究科 助教
平成13年-平成19年 千葉大学大学院自然科学研究科 助手
平成13年 慶應義塾大学院理工学研究科電気工学専攻博士課程修了 博士(工学)
受賞
7-
2020年6月
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2008年
論文
139-
IEEE Transactions on Industrial Electronics 71(9) 10433-10443 2024年9月1日This article presents a load-independent zero-current switching (ZCS) parallel-resonant inverter with a constant output current. The proposed inverter features constant-current output inherently without the need for any control method. Moreover, ZCS is achieved despite load variations, ensuring high power efficiency even at MHz-order switching frequencies. We conduct a comprehensive circuit analysis of the proposed inverter and provide a step-by-step parameter design method for achieving load-independent conditions. Additionally, a 25 W, 1 MHz prototype of the proposed inverter was implemented. In the circuit experiment, constant current output and ZCS were achieved across the entire range of load variations, which demonstrated the effectiveness of the proposed load-independent inverter.
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EPL 146(5) 2024年6月Synchronisability of limit cycle oscillators has been measured by the width of the synchronous frequency band, known as the Arnold tongue, concerning external forcing. We clarify a fundamental limit on maximizing this synchronisability within a specified extra low power budget, which underlies an important and ubiquitous problem in nonlinear science related to an efficient synchronisation of weakly forced nonlinear oscillators. In this letter, injection-locked Class-E oscillators are considered as a practical case study, and we systematically analyse their power consumption; our observations demonstrate the independence of power consumption in the oscillator from power consumption in the injection circuit and verify the dependency of power consumption in the oscillator solely on its oscillation frequency. These systematic observations, followed by the mathematical optimisation establish the existence of a fundamental limit on synchronisability, validated through systematic circuit simulations. The results offer insights into the energetics of synchronisation for a specific class of injection-locked oscillators.
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Wireless Power Transfer Technologies: Theory and technologies 89-117 2024年1月1日
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Proceedings - 2024 IEEE 48th Annual Computers, Software, and Applications Conference, COMPSAC 2024 1572-1573 2024年The fusion of IoT and Blockchain (i.e., IoT-Blockchain) promisingly revolutionizes numerous domains. However, IoT-Blockchain systems may face scalability challenges due to a large number of IoT devices and blockchain performance. Sharding, which divides the blockchain into smaller groups, offers a solution to enhance blockchain scalability. However, most previous sharding research typically considers even node distribution in a shard (i.e., a fixed node number). Hence, it may not capture the characteristics of IoT- Blockchain systems well, where nodes are diversely distributed. This paper investigates a new scenario of shards having unevenly distributed nodes, aiming to see the impacts of the scenario on sharding protocols. More specifically, we evaluate the BrokerChain protocol on the sharding-based emulation platform (i.e., BlockEmulator) in scenarios with even and uneven node distributions. The results show that the protocol performance degrades with the uneven node distribution, suggesting the need for a dynamic sharding protocol.
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IEEE Vehicular Technology Conference 2024年Blockchain holds significant potential in addressing the security, privacy, decentralization, and interoperability challenges prevalent in the Internet of Things (IoT), However, this advancement often comes at the expense of scalability. Therefore, enhancing the scalability of IoT blockchain systems while preserving other essential blockchain attributes is imperative. This paper aims to mitigate network latency in the blockchain network, a factor directly linked to blockchain scalability. Achieving this goal requires implementing an efficient peer selection method, moving beyond the reliance on default selection (i.e., the one in Bitcoin, Ethereum, etc.). In existing literature, Perigee has been introduced as a method that nearly optimizes the delay in the transaction transmission process. However, Perigee has not comprehensively addressed the complete transaction life cycle, which includes a crucial process-block transmission. In response to this limitation, we propose Dual Perigee, a solution that thoroughly considers and optimizes both transaction-oriented latency (TOL) and block-oriented latency (BOL). To show the effectiveness of Dual Perigee, we implemented and evaluated it within an emulated IoT-Blockchain system, comparing its performance with Perigee and the default peering method in Ethereum. The results reveal that Dual Perigee excels in reducing BOL compared to Perigee. Moreover, Dual Perigee exhibited a latency that was 43% and 80% lower than the default peering method and Perigee, respectively.
MISC
710-
IEEE International Symposium on Industrial Electronics 2021-June 2021年6月20日This paper proposes a load-independent class-E-1 inverter with shunt capacitance. This inverter achieves the ZVS and the constant output current at any load resistances without any control, which is called load-independent mode. This paper provides waveform and design equations of the proposed inverter. We confirmed that the laboratory prototype worked with the load-independent characteristics, which denoted validities of the analytical equations.
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IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences E104A(2) 476 2021年2月1日
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Proceedings - International SoC Design Conference 2021, ISOCC 2021 175-176 2021年This paper proposes the load-independent inverse class-E oscillator with Armstrong-oscillator based topology. The proposed oscillator achieves constant output voltage and soft switching against load variations due to the load-independent design. Moreover, the proposed circuit realizes the self-Tuning function using the Armstrong-oscillator topology. As a result, the oscillator can also have robustness against the variations in the resonant frequency. The experimental results showed the effectiveness of the proposed oscillator.
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Proceedings - International SoC Design Conference 2021, ISOCC 2021 173-174 2021年In this research, a novel numerical design strategy is presented for the class-DE inverter design, which is based on particle swarm optimization (PSO) algorithm. Compared with previous numerical design methods based on Newton's method, the proposed method shows convenience without restricting the number of design parameters. Additionally, no initial estimation is needed for ensuring convergence. Therefore, system-level optimization, which considers optimized inductor designs, can be realized. A design example of the class-DE inverter is shown in this paper. The numerical calculation proved the validity of the proposed design method.
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Proceeding - 2021 26th IEEE Asia-Pacific Conference on Communications, APCC 2021 94-98 2021年This paper tackles the problem of using and paying a network service with guaranteed quality of service (QoS) at a fine granularity in the future wireless network. We propose the IOTA-based QoS guaranteed Flow system (IQF), where a user and service provider can exchange the IOTA cryptocurrency for the guaranteed network resources, such as latency and bandwidth. First, IQF uses the IOTA Tangle, a lightweight, efficient distributed ledger technology, for its payment and transaction record. Second, IQF adopts Software Defined Networking to realize the guaranteed delay and bandwidth provision. We have implemented the IQF systems using the mininet-wifi emulator, an SDN controller (i.e., POX), and IOTA clients. Moreover, we have evaluated the service provisioning algorithms with a micropayment of IQF with the test Tangle (i.e., comnet). The evaluation results show that IQF has successfully achieved the delay and bandwidth provision with all the transactions stored in comnet.
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Proceedings - IEEE International Symposium on Circuits and Systems 2021-May 2021年This paper presents a 2-hop wireless power transfer (WPT) system for the robot-arm application. The proposed WPT system consists of the class-E inverter on the transmitter side and a class-D rectifier on the receiver side. We obtain the analytical model of the WPT system for obtaining the class-E ZVS/ZDS conditions. The model includes the detailed physical information of the coil, namely coil diameter, height, wire thickness, winding turn number, and so on. Therefore, it is possible to optimize the WPT system for the theoretical highest power-delivery efficiency under the robot-arm coil-space restriction. The circuit experiment showed quantitative agreements with the theoretical predictions, which proved the validity of the proposed design method. The experimental prototype achieved 78.0 % power-delivery efficiency at 6.78 MHz operating frequency and 39.3 W output power.
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IEICE Transactions on Communications E103B(12) 1375 2020年12月1日
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2020 IEEE Globecom Workshops, GC Wkshps 2020 - Proceedings 2020年12月Network softwarization, such as Software-Defined Networking (SDN), is a potential technology to manage networking resources and routing paths dynamically in 5G and beyond. However, SDN, which provides the control plane programmability, requires a de-factor protocol (i.e., OpenFlow) on network devices. In an SDN network, the load of network control traffic is likely concentrated on a network controller. Moreover, most of SDN advantages are not easily extensible in wireless networks. Programming Protocol-independent Packet Processors (P4), which enables the data plane programmability, potentially solves SDN issues. P4 allows programming new packet forwarding methods, which don't necessarily rely on the predefined protocols. In this paper, we show the feasibility of P4 in realizing a multipath communication mechanism in wireless networks. We first introduce and implement a P4-based multipath transmission mechanism of UDP traffic. We then evaluate the mechanism on an emulated wireless network (i.e., using mininetwifi) in comparison to the single path. The results show that the P4-based mechanism can effectively achieve the throughput aggregation with a slightly bigger latency variation.
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Proceedings of the 4th International Conference on Advanced Information Technologies, ICAIT 2020 7-11 2020年11月4日Guaranteeing delay performance is an essential issue in a Wi-Fi network since it has increasingly conveyed a huge amount of Internet application traffic. This paper introduces our continuous effort in delay-guaranteed provision for Wi-Fi networks. More specifically, we have introduced the previously proposed delay-guaranteed mechanism that uses the advantage of SDN technology. In this work, we evaluate the mechanism in a new environment considering several TCP flows. The evaluation results show that the SDN-based algorithm effectively controls the delay values of multiple flows. Moreover, the sharing bandwidth between the flows is fair with negligible overhead.
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International Conference on ICT Convergence 2020-October 305-310 2020年10月21日Wi-Fi technology has become popular in our lives with various Wi-Fi capable products such as laptops, mobile phones, etc. Moreover, in Wi-Fi networks, a device communicates typically with a server using Transmission Control Protocol (TCP) for most applications. In such a context, the behavior of the TCP congestion control primarily affects network performance. Hence, it is essential to determine and select an appropriate TCP congestion control that fits different network conditions. In this paper, we present a performance evaluation of TCP congestion control algorithms in an emulated Wi-Fi network. More specifically, we investigate 14 TCP congestion control algorithms in the Wi-Fi network, considering the variation of queue size and packet loss. The evaluation results of Round Trip Time (RTT) and achieved throughput allows us to compare the TCP congestion control algorithms. In our investigation, the Bottleneck Bandwidth Roundtrip-Time algorithm (BBR) has the best performance.
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Proceedings - International SoC Design Conference, ISOCC 2020 179-180 2020年10月21日This paper presents a design example of the class-Φ3 inverter. The design parameters can be theoretically obtained by applying the multi-frequency analysis. The class-Phi3 inverter is a special version of the class-E/F3 inverters, whose output reactance is zero. It is possible to obtain the circuit component values, which give zero output reactance of the output filter with consideration of low input inductance. The experimental results and PSpice-simulation results agreed with the analytical predictions quantitatively, which showed the validity of analytical expressions in this paper.
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ECCE 2020 - IEEE Energy Conversion Congress and Exposition 1571-1576 2020年10月11日This paper proposes a parallel resonant power oscillator that has the load-independent characteristic. The proposed oscillator is the first parallel-resonant power oscillator for high frequency operations. In addition, it achieves the constant output voltage and the soft switching against the load variations without any control. The feedback network for generating a driving signal does not have a resonant structure and its function is not affected by the self-oscillation frequency. Therefore, the proposed oscillator also has a self-tuning function for the resonant-filter component tolerances. Because of the above characteristics, the proposed oscillator is expected to be used in many applications such as a transmitter of the wireless power transfer systems.
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電気学会研究会資料. SPC = The papers of technical meeting on semiconductor power converter, IEE Japan / 半導体電力変換研究会 [編] 2020(102-106) 1-4 2020年7月10日
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IEEE INFOCOM 2020 - IEEE Conference on Computer Communications Workshops, INFOCOM WKSHPS 2020 1356-1357 2020年7月In the current and next generation of mobile networks, a mobile device intuitively has multiple wireless radios such as Wi-Fi, LTE, 5G New Radio, etc. Moreover, most likely, the mobile device continues to use the TCP/IP stack, which limits the device's network selection. The application traffic may stick to a default network, which may not have the best performance among the associated ones. That harms the performance of TCP short flows, such as web access. This paper proposes using TCP SYN duplication to relax the constraint, aiming to select the best network at the present moment. The device tries to initialize a TCP connection by duplicating and sending SYN packets via all the available networks. The network, which conveys the earliest SYN/ACK response, will be selected for the data transfer. We implement and evaluate the proposal in a testbed with real Internet connections to show its effectiveness.
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Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC 2020-March 2041-2047 2020年3月A novel design of single-stage single-switch PFC converter topology is presented in this paper. The converter bases on class-E2 topology and operates at 1 MHz frequency. With only one wide-bandgap GaN FET without extra stages or cells, it is possible to reduce the size of the circuit. Frequency modulation control method is applied to the system to decrease the harmonic distortions of the input line current. In order to keep the ZVS characteristic achieved during the entire period, a numerical design procedure of the converter is also considered, which can reduce the switching loss of the switch efficiently. Moreover, experiment prototype is implemented to validate the high performance of the proposed system. The experimental result shows good agreement with the simulation, achieving high power conversion efficiency and low total harmonic distortions (THD), which proves the effectivity of the proposed design procedure.
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Proceedings - 2020 International Conference on Green and Human Information Technology, ICGHIT 2020 58-61 2020年2月The IEEE 802.11ad technology, which is a member of the IEEE 802.11 family, promisingly extends the operation of Wi-Fi networks to the unlicensed 60 GHz band. In such a case, the Wi-Fi network can support the throughput of multi-gigabit per second, potentially support various emerging applications. Since the Transport Control Protocol (TCP) plays a vital role in Wi-Fi networks, it is necessary to understand the TCP performance in that multi-Gbps condition. This paper investigates the performance of popular TCP variants on the IEEE 802.11ad wireless link. We conduct the experiments with TCP CUBIC, CDG, BBR, which are typically loss-based, delay-based, and model-based TCP congestion control algorithms, in different loss conditions. The results show that in a no-loss scenario, CUBIC and CDG keep good throughput at the cost of high TCP latency. Meanwhile, BBR has excellent performance even under the high loss scenario.
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電子情報通信学会技術研究報告(Web) 120(181(EE2020 11-15)) 2020年
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8th International Conference on Renewable Energy Research and Applications, ICRERA 2019 599-602 2019年11月This paper presents an analytic expression of the class-E rectifier with low output-filter inductance. Compared with the traditional rectifiers, the larger power output capability can be obtained by varying the output-filter inductance. Also, the validity of the analytical expression and design strategy are presented by implementation of the class-E resonant DC-DC converter. The converter with low output-filter inductance achieved 11 % power output capability than the traditional class-E rectifier. 2
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IECON Proceedings (Industrial Electronics Conference) 2019-October 1615-1620 2019年10月This paper presents an easy-to-use analytical design approach of the load-independent class-E inverter at any duty ratio. By using the analytical approach, it is possible to maintain the amplitude of the output voltage and the operation of the zero-voltage switching. Additionally, a design example is given along with its LTspice simulation and laboratory experiment. The LTspice simulation and laboratory experiment waveforms are in good agreement with the analytical ones even load variations. Moreover, all the switch-voltage waveforms satisfy the ZVS condition. These results showed that the proposed approach and analytical expressions are available and effective.
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2019 IEEE Energy Conversion Congress and Exposition, ECCE 2019 1256-1260 2019年9月© 2019 IEEE. This paper presents a novel class-E2 dc-dc converter and its design procedure. The proposed converter can maintain high-frequency and high-efficiency operations while realizing low switch-voltage stresses. Additionally, by using the presented design procedure, the proposed converter satisfying the zero-voltage-switching and zero-derivative-switching (ZVS/ZDS) conditions can be implemented without applying any tuning processes. A design example of the proposed class-E2 converter is shown along with its LTspice simulation and laboratory experiment. The results from the LTspice simulator and laboratory experiment show quantitative agreement with the analytical predictions, which indicates the validity of the proposed topology and design procedure.
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2019 IEEE Energy Conversion Congress and Exposition, ECCE 2019 375-379 2019年9月© 2019 IEEE. This paper presents a design challenge of a SiC MOSFET class-E inverter with a class- high-speed driver. The driver is based on a class- inverter which is a novel class-E inverter with a harmonic resonant filter, enabling the driver to achieve not only the class-E zero-voltage-switching/zero-derivative-switching (ZVS/ZDS) conditions but also a low switch-voltage stress. In this paper, the class-E inverter and its driver are regarded as a whole system to be designed. Additionally, the whole system is designed by using the numerical design procedure. A design example is also given along with its laboratory experiment under 156 W output power and 6.78 MHz operating frequency. All the switch-voltage waveforms obtained from laboratory experiment satisfy the class-E ZVS/ZVDS conditions. It is also seen from the experimental results that the numerical calculations agreed with the experimental ones quantitatively, which shows the validity of the design procedure presented in this paper.
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Midwest Symposium on Circuits and Systems 2019-August 529-532 2019年8月© 2019 IEEE. This paper presents a numerical design method of the load-independent class-E inverter with MOSFET gate-to-drain and drain-to-source parasitic capacitances. A design example is shown along with its LTspice simulation and laboratory experiment. There are no changes in the output-voltage waveforms and all the switch-voltage waveforms satisfy the zero-voltage-switching (ZVS) condition even the load-resistance value varies from the desired one. Additionally, the results obtained from the LTspice simulation and laboratory experiment show quantitative agreement with the numerical predictions, which shows the effectiveness of the proposed design method of the load-independent class-E inverter with MOSFET parasitic capacitances given in this paper.
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