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Wuhan Ligong Daxue Xuebao (Jiaotong Kexue Yu Gongcheng Ban)/Journal of Wuhan University of technology (Transportation science and Engineering) 2007年第5期31卷 780-783页

作者： Ye, Zhihao Zhang, Xiaofeng Zhang, Ling Yang, Xidang National Key Laboratory for Vessel Integrated Power System Technology Naval University of Engineering Wuhan 430033 China Research Institute of Power Electronic Technology Naval University of Engineering Wuhan 430033 China College of Ship and Power Engineering Naval University of Engineering Wuhan 430033 China Wuhan Ordnance NCO Academy Wuhan 430073 China

On the basis of achieving 12-phase cycloconverter output harmonic voltage, the four Y integrated, voltage harmonics of the variable speed system with cycloconverter fed 12 phase synchronous motor are derived which denotes the voltage harmonics of four Y windings that can be bucked each other and make the axis harmonic voltage zero, the axis one only have much less harmonics with little amplitude. A further analysis on current harmonics and electromagnetic torque harmonic proves the good effect of this voltage harmonics bucking action on improving the harmonic character of variable speed system with cycloconverter fed 12-phase synchronous motor. The simulating and experimental results validate the correctness of theoretic analysis.

关键词： 12-Phase synchronous motor Cycloconverter Electromagnetic torque Harmonic Simulation Test

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High Frequency Modeling for Transformer Common Mode Noise Coupling Path Based on Multiconductor Transmission Line Theory

High Frequency Modeling for Transformer Common Mode Noise Co...

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Annual IEEE Applied power Electronics Conference and Exposition

作者： Peipei Meng Xiangming Zhang School of Automation Wuhan University of Technology Wuhan Hubei 430070 China National Key Laboratory of Science and Technology on Vessel Integrated Power System Technology Naval University of Engineering Wuhan Hubei 430033 China

ISBN: (纸本)9781467395519

Transformer is an important common mode (CM) noise coupling path in isolated power converters. But the EMI behavior of transformer is difficult to predict because of the complicated high frequency parasitics. This paper proposes a transformer Common-mode (CM) noise coupling path modeling approach based on multiconductor transmission line (MTL) theory. The MTL model can include the complicated magnetic and electrical couplings among the windings, the distribution of parasitic parameters, and the high frequency losses caused by skin and proximity effects. Physical structure oriented model is established in Maxwell 2D to extract the high frequency parasitic parameters of the transformer based on finite element method (FEM). With the MTL model the CM noise caused by the converter can be well predicted in the whole conducted EMI frequency range from 150 kHz to 30 MHz, which is validated by measured results with EMI receiver.

关键词： EMI/EMC common mode noise multiconductor transmission line theory finite element method transformer

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Measurement technology of RF interference current in high current system

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AIP Conference Proceedings 2018年第1期1971卷

作者： Zhihua Zhao Jianxuan Li Xiangming Zhang Lei Zhang National Key Laboratory of Science and Technology on Vessel Integrated Power System Naval University of Engineering Wuhan China

Current probe is a detection method commonly used in electromagnetic compatibility. With the development of power electronics technology, the power level of power conversion devices is constantly increasing, and the power current of the electric energy conversion device in the electromagnetic launch system can reach 10kA. Current probe conventionally used in EMC (electromagnetic compatibility) detection cannot meet the test requirements on high current system due to the magnetic saturation problem. The conventional high current sensor is also not suitable for the RF (Radio Frequency) interference current measurement in high current power device due to the high noise level in the output of active amplifier. In this paper, a passive flexible current probe based on Rogowski coil and matching resistance is proposed that can withstand high current and has low noise level, to solve the measurement problems of interference current in high current power converter. And both differential mode and common mode current detection can be easily carried out with the proposed probe because of the probe’s flexible structure.

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An Improved Strategy for Modular Multilevel Converter at Low Speed Operation

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IOP Conference Series: Materials science and Engineering 2018年第4期394卷

作者： Qifan Zeng Fei Xiao Sheng Ai Qiang Ren National Key Laboratory of Science and Technology on Vessel Integrated Power System Naval University of Engineering Wuhan China

One of the main problems of the Modular Multilevel Converter (MMC) for ship electric propulsion applications is the significant magnitude of capacitor voltage ripple at low speed operation. The commonly used solution is harmonic injection. In this paper, the injection rules are explored through the dynamic relationship of MMC in a comprehensive way, and the harmonic characteristics of injection current are derived. Furthermore, the circulating current controller is modified according to the harmonics of injected current with changing frequency, which reduces the ripple of capacitor voltage effectively in a wide speed range. Simulation results are shown to demonstrate the effectiveness of the proposed method.

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Research on the Overall Framework of the integrated power system Fuel Economy Optimization Scheduling Strategy

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IOP Conference Series: Materials science and Engineering 2019年第4期677卷

作者： Chen Xu Gang Wang Runlong Xiao National Key Laboratory for Science and Technology on Vessel Integrated Power System Naval University of Engineering Wuhan China

Due to the differences in research objects, operational requirements and control methods, the fuel economy strategies of land-based power systems and traditional marine power systems cannot be directly applied to integrated power systems. Aiming at the energy optimization and regulation requirements of the integrated power system, a fuel economy optimization scheduling strategy model was established. By analyzing the operational requirements of the system under normal and abnormal conditions, the overall framework of the fuel economy optimization scheduling strategy for the integrated power system was established. The generator excitation adopts the master-slave control mode, which realizes the optimal dispatch of the generator output under the overall frame operation demand. Finally, the simulation test verifies the effectiveness of the proposed method.

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TRUST: A Toolkit for TEE-Assisted Secure Outsourced Computation over Integers

arXiv

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arXiv 2024年

作者： Zhao, Bowen Li, Jiuhui Xu, Peiming Li, Xiaoguo Pei, Qingqi Shen, Yulong Guangzhou Institute of Technology Xidian University Guangzhou510555 China State Key Laboratory of Public Big Data Guizhou University Guiyang550025 China Electric Power Research Institute CSG Guangdong Guangzhou510663 China Guangdong Provincial Key Laboratory of Power System Network Security Guangdong Guangzhou510663 China The College of Computer Science Chongqing University Chongqing400044 China The State Key Laboratory of Integrated Service Networks Xidian University Xi’an710126 China

Secure outsourced computation (SOC) provides secure computing services by taking advantage of the computation power of cloud computing and the technology of privacy computing (e.g., homomorphic encryption). Expanding computational operations on encrypted data (e.g., enabling complex calculations directly over ciphertexts) and broadening the applicability of SOC across diverse use cases remain critical yet challenging research topics in the field. Nevertheless, previous SOC solutions frequently lack the computational efficiency and adaptability required to fully meet evolving demands. To this end, in this paper, we propose a toolkit for TEE-assisted (Trusted Execution Environment) SOC over integers, named TRUST. In terms of system architecture, TRUST falls in a single TEE-equipped cloud server only through seamlessly integrating the computation of REE (Rich Execution Environment) and TEE. In consideration of TEE being difficult to permanently store data and being vulnerable to attacks, we introduce a (2, 2)-threshold homomorphic cryptosystem to fit the hybrid computation between REE and TEE. Additionally, we carefully design a suite of SOC protocols supporting unary, binary and ternary operations. To achieve applications, we present SEAT, secure data trading based on TRUST. Security analysis demonstrates that TRUST enables SOC, avoids collusion attacks among multiple cloud servers, and mitigates potential secret leakage risks within TEE (e.g., from side-channel attacks). Experimental evaluations indicate that TRUST outperforms the state-of-the-art and requires no alignment of data as well as any network communications. Furthermore, SEAT is as effective as the Baseline without any data protection. Copyright © 2024, The Authors. All rights reserved.

关键词： Side channel attack

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Analysis of the Axial Fan Performance Mounted on a 4.5kW Aviation Motor

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Journal of Physics: Conference Series 2021年第1期1820卷

作者： Bin Liu Zhongjun Yu Jia Fu Zutao Chen National Key Laboratory of Science and Technology on Vessel Integrated Power System Naval University of Engineering Wuhan 430033 China

Integrating an axial flow fan with the rotor is a sufficient cooling method for high-speed and high power density motors. Different from the axial fan design work under ideal intake condition, i.e. the intake flow of the fan is axial and uniform, the flow in actual engineering is more complex, which means the flow characteristics of an integrated fan are changed and disturbed. It leads to a performance penalty of the fan, and in some conditions it makes the fan stall, so it is important to get a knowledge of the flow characteristics and the performance of the integrated fan. A certain 4.5kW aviation motor with integrated axial fan is taken as the research object. Firstly, the motor-fan coupling simulation model and ideal axial intake simulation model are established, in which the mass flow rates are same, then calculation is conducted. Secondly, the simulation results are analyzed and compared, focusing on the performance of the axial fan, especially the static pressure rise, and the conclusion is obtained that the static pressure rise in ideal axial intake situation is higher than that in coupling situation. Furthermore, the reasons for the characteristics change are explored, finding that the increase of flow turbulence due to the more complex wind road structure is the main cause for these changes. This paper investigates the flow characteristics and axial fan performance mounted a whole motor, making a contribution to better understand the changes in fan performance under motor-fan coupling situation.

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Camouflaged Object Detection via Context-aware Cross-level Fusion

arXiv

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arXiv 2022年

作者： Chen, Geng Liu, Si-Jie Sun, Yu-Jia Ji, Ge-Peng Wu, Ya-Feng Zhou, Tao Northwestern Polytechnical University Xi’an710072 China National Engineering Laboratory for Integrated Aero-Space-Ground-Ocean Big Data Application Technology School of Computer Science and Engineering China Data Processing Center School of Power and Energy China Key Laboratory of System Control and Information Processing Ministry of Education Shanghai200240 China School of Computer Science and Engineering Nanjing University of Science and Technology Nanjing210094 China School of Computer Science Inner Mongolia University Hohhot010021 China Artificial Intelligence Institute School of Computer Science Wuhan University Wuhan430072 China

Camouflaged object detection (COD) aims to identify the objects that conceal themselves in natural scenes. Accurate COD suffers from a number of challenges associated with low boundary contrast and the large variation of object appearances, e.g., object size and shape. To address these challenges, we propose a novel Context-aware Cross-level Fusion Network (C2F-Net), which fuses context-aware cross-level features for accurately identifying camouflaged objects. Specifically, we compute informative attention coefficients from multi-level features with our Attention-induced Cross-level Fusion Module (ACFM), which further integrates the features under the guidance of attention coefficients. We then propose a Dual-branch Global Context Module (DGCM) to refine the fused features for informative feature representations by exploiting rich global context information. Multiple ACFMs and DGCMs are integrated in a cascaded manner for generating a coarse prediction from high-level features. The coarse prediction acts as an attention map to refine the low-level features before passing them to our Camouflage Inference Module (CIM) to generate the final prediction. We perform extensive experiments on three widely used benchmark datasets and compare C2F-Net with state-of-the-art (SOTA) models. The results show that C2F-Net is an effective COD model and outperforms SOTA models remarkably. Further, an evaluation on polyp segmentation datasets demonstrates the promising potentials of our C2F-Net in COD downstream applications. Our code is publicly available at: https://***/Ben57882/C2FNet-TSCVT. Copyright © 2022, The Authors. All rights reserved.

关键词： Object detection

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PCG: Mitigating Conflict-based Cache Side-channel Attacks with Prefetching

arXiv

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arXiv 2024年

作者： Jiang, Fang Tong, Fei Wang, Hongyu Cheng, Xiaoyu Zhou, Zhe Ling, Ming Mao, Yuxing The School of Cyber Science and Engineering Southeast University Jiangsu Nanjing China Jiangsu Province Engineering Research Center of Security for Ubiquitous Network China The Purple Mountain Laboratories Jiangsu Nanjing China The State Key Laboratory of Power Transmission Equipment & System Security and New Technology Chongqing University Wiscom System Co. LTD China The School of Integrated Circuits Southeast University Jiangsu Nanjing China

To defend against conflict-based cache side-channel attacks, cache partitioning or remapping techniques were proposed to prevent set conflicts between different security domains or obfuscate the locations of such conflicts. But such techniques complicate cache design and may result in significant performance penalties. Therefore, there have been lightweight prefetching-based schemes proposed to introduce noise to confuse attackers’ observation. However, we have validated experimentally that relying on prefetching to only introduce noise is insufficient, as attackers can still reliably distinguish the victim’s cache accesses. This paper proposes a novel prefetching-based scheme, called PCG. It combines adding victim-irrelevant cache occupancy changes and reducing victim-relevant cache occupancy changes to disrupt attackers by generating noisy and indistinguishable cache access patterns. Additionally, PCG can either work independently or seamlessly be integrated with most of the commonly used prefetchers. We have implemented and evaluated PCG in both gem5 and the open-source RISC-V core BOOMv3. The evaluation results show the PCG’s robust security superior to the existing solutions, while without resulting in significant performance degradation. According to the evaluation based on the SPEC CPU 2017 benchmark suite, PCG even shows an average performance improvement of about 1.64%. Moreover, it incurs only 1.26% overhead on hardware resource consumption. Copyright © 2024, The Authors. All rights reserved.

关键词： Side channel attack

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Research on Topology and Modulation Control Method of a Novel Three-Level Current-Fed DCDC Converter

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IOP Conference Series: Materials science and Engineering 2019年第4期612卷

作者： Kai Ji Tingyang Chen Wenfeng Long Jinping He National Key Laboratory of Science and Technology on Vessel Integrated Power System Wuhan Institute of Marine Electric Propulsion Wuhan China

Multilevel current source converter has the benefits of high output capacity, low current switching stress and low harmonic or ripple content. This paper presents a new topology of three-level current-fed DC/DC converter for superconducting magnetic energy storage application. In this topology, a superconducting inductance acting as a constant current source and a shunt inductance acts as current divider ensure current flows through the power switch components equally to generate immediate level of current. A novel kind of pulse width modulation (PWM) switching strategy for the current instantaneous control of the current source converter was proposed. The modulation switching strategy proposed is able to effectively control the DC current output of the converter. Also, due to the both of proposed topology and control method are quite a simple, it can be easily realized in the practice. Simulation results prove the feasibility and validity of the proposed topology and modulation strategy

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