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FSS: algorithm and neural network accelerator for style transfer

Science China(Information Sciences) 2024年第2期67卷 253-266页

作者： Yi LING Yujie HUANG Yujie CAI Zhaojie LI Mingyu WANG Wenhong LI Xiaoyang ZENG state key laboratory of asic & system Fudan University Shanghai Explore X Technology Co. Ltd.

Neural networks(NNs), owing to their impressive performance, have gradually begun to dominate multimedia processing. For resource-constrained and energy-sensitive mobile devices, an efficient NN accelerator is necessary. Style transfer is an important multimedia application. However, existing arbitrary style transfer networks are complex and not well supported by current NN accelerators, limiting their application on mobile devices. Moreover, the quality of style transfer needs improvement. Thus, we design the Fast Style system(FSS), where a novel algorithm and an NN accelerator are proposed for style transfer. In FSS, we first propose a novel arbitrary style transfer algorithm, Fast Style. We propose a light network that contributes to high quality and low computational complexity and a prior mechanism to avoid retraining when the style changes. Then, we redesign an NN accelerator for Fast Style by applying two improvements to the basic NVIDIA deep learning accelerator(NVDLA) architecture. First, a flexible dat FSM and wt FSM are redesigned to enable the original data path to perform other operations(including the GRAM operation)by software programming. Moreover, statistics and judgment logic are designed to utilize the continuity of a video stream and remove the data dependency in the instance normalization, which improves the accelerator performance by 18.6%. The experimental results demonstrate that the proposed Fast Style can achieve higher quality with a lower computational cost, making it more suitable for mobile devices. The proposed NN accelerator is implemented on the Xilinx VCU118 FPGA under a 180-MHz clock. Experimental results show that the accelerator can stylize 512×512-pixel video with 20 FPS, and the measured performance reaches up to 306.07 GOPS. The asic implementation in TSMC 28 nm achieves about 22 FPS in the case of a 720-p video.

关键词： neural network accelerator style transfer neural network deep learning

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On the Polygonal Wear Evolution of Heavy-Haul Locomotive Wheels due to Wheel/Rail Flexibility and Its Mitigation Measures

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Chinese Journal of Mechanical Engineering 2024年第1期37卷 40-61页

作者： Yunfan Yang Feifan Chai Pengfei Liu Liang Ling Kaiyun Wang Wanming Zhai state key laboratory of Mechanical Behavior and system Safety of Traffic Engineering Structures Shijiazhuang Tiedao UniversityShijiazhuang 050043China state key laboratory of Rail Transit Vehicle system Southwest Jiaotong UniversityChengdu 610031China

Wheel polygonal wear can immensely worsen wheel/rail interactions and vibration performances of the train and track,and ultimately,lead to the shortening of service life of railway components.At present,wheel/rail medium-or high-frequency frictional interactions are perceived as an essential reason of the high-order polygonal wear of railway wheels,which are potentially resulted by the flexible deformations of the train/track system or other external excitations.In this work,the effect of wheel/rail flexibility on polygonal wear evolution of heavy-haul locomotive wheels is explored with aid of the long-term wheel polygonal wear evolution simulations,in which different flexible modeling of the heavy-haul wheel/rail coupled system is implemented.Further,the mitigation measures for the polygonal wear of heavy-haul locomotive wheels are discussed.The results point out that the evolution of polygonal wear of heavy-haul locomotive wheels can be veritably simulated with consideration of the flexible effect of both wheelset and rails.Execution of mixed-line operation of heavy-haul trains and application of multicut wheel re-profiling can effectively reduce the development of wheel polygonal wear.This research can provide a deep-going understanding of polygonal wear evolution mechanism of heavy-haul locomotive wheels and its mitigation measures.

关键词： Heavy-haul locomotive Wheel polygonal wear Wheel/rail flexibility Long-term polygonal wear evolution Mitigation measures

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Influence of vibration on the lubrication effect of a splash-lubricated gearbox

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2024年第4期25卷 324-339页

作者： Yi LIU Kailin ZHANG Shuai SHAO Hongxu XIANG Zhijian YE state key laboratory of Rail Transit Vehicle system Southwest Jiaotong UniversityChengdu 610031China

In this study,we investigate the effect of rail vibrations on the lubrication and efficiency of a splash-lubricated gearbox;specifically,the gearbox of a rail-transit vehicle.A high-fidelity 3D numerical model of the gearbox in a moving reference system is described,as well as computational fluid dynamics(CFD)simulations of the gearbox with different vibration directions.The effects of rotational speed,oil-immersion depth,and different oil-injection volume rates on lubrication and efficiency are discussed.We propose a method of evaluating the internal lubrication condition of a splash-lubricated gearbox and quantitatively compare the effects of different operating parameters on lubrication and efficiency.Finally,our experiment to verify the feasibility of the simulation method is described.The results show that with vibration,the churning loss and oil supply for the bearings are significantly higher than those under static conditions.In addition,among different vibrational directions,lateral vibration has the greatest influence on the lubrication condition and efficiency of the gearbox.For the studied railway-vehicle gearbox,the best lubrication condition is achieved at a rotational speed of 1600 r/min and an oil-immersion depth of two times the tooth height(2.Oh).Rotational speed is the operating parameter that has the most significant effect on the lubrication and efficiencyofthegearbox.

关键词： Comprehensive lubrication evaluation Churning loss Moving reference system Splash lubrication Vibrational excitation Gearbox

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Recent Advances in Electrochemical-Based Silicon Production Technologies with Reduced Carbon Emission

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Research 2024年第1期2023卷 209-236页

作者： Feng Tian Zhongya Pang Shen Hu Xueqiang Zhang Fei Wang Wei Nie Xuewen Xia Guangshi Li Hsien-Yi Hsu Qian Xu Xingli Zou Li Ji Xionggang Lu state key laboratory of Advanced Special Steel&Shanghai key laboratory of Advanced Ferrometallurgy&School of Materials Science and Engineering Shanghai University99#Shangda RoadShanghai 200444China Center for Hydrogen Metallurgy Technology Shanghai UniversityShanghai 200444China state key laboratory of asic and system School of MicroelectronicsFudan University220#Handan RoadShanghai 200433China School of Energy and Environment Department of Materials Science and EngineeringCity University of Hong KongKowloon TongHong KongChina

Sustainable and low-carbon-emission silicon production is currently one of the main focuses for the metallurgical and materials science communities.Electrochemistry,considered a promising strategy,has been explored to produce silicon due to prominent advantages:(a)high electricity utilization efficiency;(b)low-cost silica as a raw material;and(c)tunable morphologies and structures,including films,nanowires,and nanotubes.This review begins with a summary of early research on the extraction of silicon by electrochemistry.Emphasis has been placed on the electro-deoxidation and dissolution–electrodeposition of silica in chloride molten salts since the 21st century,including the basic reaction mechanisms,the fabrication of photoactive Si films for solar cells,the design and production of nanoSi and various silicon components for energy conversion,as well as storage applications.Besides,the feasibility of silicon electrodeposition in room-temperature ionic liquids and its unique opportunities are evaluated.On this basis,the challenges and future research directions for silicon electrochemical production strategies are proposed and discussed,which are essential to achieve large-scale sustainable production of silicon by electrochemistry.

关键词： directions electrodeposition electricity

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Dynamics modeling and electromechanical coupling characteristics analysis of cage induction motors

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Science China(Technological Sciences) 2024年第3期67卷 709-724页

作者： ZHOU ZiWei CHEN ZaiGang ZHAI WanMing state key laboratory of Rail Transit Vehicle system Southwest Jiaotong UniversityChengdu 610031China

Induction motors, as typical electromechanical energy conversion devices, have received limited attention in previous studies on electromechanical coupling vibrations, precise modeling, and the use of electromechanical coupling effects for fault diagnosis and condition assessment in motor drive systems. This study proposes a comprehensive model of cage induction motors that integrates the multiple coupled circuit model with a rotor-bearing dynamics model. The model accounts for the linear increase in the magnetomotive force across the slot and incorporates the skidding characteristics of bearings in the rotor-bearing system. By calculating the time-varying mutual inductance parameters based on the air-gap distribution in the vibration environment, the electromechanical coupling vibration of the cage motor is investigated. Furthermore, this study examines the electromechanical coupling vibration characteristics influenced by various factors, including bearing clearances, radial loads, and the vertical excitation frequencies of the stators. The results show that the proposed model improves the excitation inputs for the electrical and mechanical systems of the motor compared with conventional models. Increased bearing clearance and radial load affect the current and torque similarly but have opposite effects on the slip ratio. This study provides a deeper understanding of electromechanical coupling mechanisms and facilitates the use of such phenomena for fault diagnosis and condition assessment in motor-driven systems.

关键词： cage induction motors rotor-bearing dynamics mutual inductance electromechanical testing current signal analysis

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Security-constrained Transmission Maintenance Optimization Considering Generation and Operational Risk Costs

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Journal of Modern Power systems and Clean Energy 2024年第3期12卷 767-781页

作者： Dan Xu Zhi Cai Qian Cheng Guodong Huang Jingyang Zhou Junjie Tang Beijing key laboratory of Research and system Evaluation of Power Dispatching Automation Technology China Electric Power Research Institute state key laboratory of Power Transmission Equipment & system Security and New Technology Chongqing University

With the large-scale integration of renewable energy, the traditional maintenance arrangement during the load valley period cannot satisfy the transmission demand of renewable energy generation. Simultaneously, in a market-oriented operation mode, the power dispatching control center aims to reduce the overall power purchase cost while ensuring the security of the power system. Therefore, a security-constrained transmission maintenance optimization model considering generation and operational risk costs is proposed herein. This model is built on double-layer optimization framework, where the upper-layer model is used for maintenance and generation planning, and the lowerlayer model is primarily used to address the operational security risk arising from the random prediction error and N-1 transmission failure. Correspondingly, a generation-maintenance iterative algorithm based on a defined cost feedback is included to increase solution efficiency. Generation cost is determined using long-term security-constrained unit commitment, and the operational risk cost is obtained using a double-layer N-1 risk assessment model. An electrical correlation coupling coefficient is proposed for the solution process to avoid maintenance of associated equipment simultaneously, thereby improving model convergence efficiency. The IEEE 118-bus system is used as a test case for illustration, and test results suggest that the proposed model and algorithm can reduce the total cost of transmission maintenance and system operation while effectively improving the solution efficiency of the joint optimization model.

关键词： Maintenance engineering Costs Optimization Power systems Renewable energy sources Power grids Load modeling

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A versatile humanoid robot platform for dexterous manipulation and human-robot collaboration

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CAAI Transactions on Intelligence Technology 2024年第2期9卷 526-540页

作者： Xin Shu Fenglei Ni Xinyang Fan Shuai Yang Changyuan Liu Baoxu Tu Yiwei Liu Hong Liu state key laboratory of Robotics and system Harbin Institute of TechnologyHarbinChina

Humanoid robots have attracted much attention by virtue of their compatibility with human environments.However,biped humanoids with immense promise still cannot function steadily and reliably in real-world settings in the current state.Hence,rationally combining a humanoid robot with different stable mobile platforms is a favoured solution for diverse scenarios.Here,a new versatile humanoid robot platform,aiming to provide a generic solution that can be flexibly deployed in diverse scenarios,for example,indoors and fields is presented.Versatile humanoid robot platform incorporates multimodal perception,and extensible interfaces on hardware and software,allowing it to be rapidly integrated with different mobile platforms and end-effectors,only through easyto-assemble interfaces.Additionally,the platform has achieved impressive integration,lightness,dexterity,and strength in its class,with human-like size and rich perception,targeted to have human-intelligent manipulation skills for human-engineered environments.Overall,this article elaborates on the reasoning behind the design choices,and outlines each subsystem.Lastly,the essential performance of the platform is successfully demonstrated in a set of experiments with precise and dexterous manipulation,and human–robot collaboration requirements.

关键词： intelligent robots robotics

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Contact engineering for temperature stability improvement of Bi-contacted MoS2 field effect transistors

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Science China(Information Sciences) 2024年第6期67卷 172-179页

作者： Zizheng LIU Qing ZHANG Xiaohe HUANG Chunsen LIU Peng ZHOU state key laboratory of Integrated Chip and systems School of MicroelectronicsZhangjiang Fudan International Innovation CenterFudan University Frontier Institute of Chip and system Shanghai Key Lab for Future Computing Hardware and SystemFudan University Shaoxin laboratory

Semimetallic bismuth（Bi） is one of the most effective strategies for reducing the contact resistance of two-dimensional transition metal dichalcogenide field effect transistors（FETs）. However, the low melting point of Bi contact（271.5℃） limits its reliable applications. In this study, we demonstrated that the temperature stability of Bi-contacted electrodes could be improved by inserting a high-melting point semimetallic antimony（Sb） between the Bi contacting layer and the gold（Au） capping layer. The proposed Bi/Sb/Au contact electrodes tended to form a metal mixture with a continuous surface during the heating process（Voids appeared on the surface of the Bi/Au contact electrodes after heating at 120℃）. Because of the improved contacting layer formed by the semimetal Bi/Sb alloy, the fabricated Bi/Sb/Au-contacted molybdenum sulfide（MoS2） FETs with different gate lengths demonstrated higher on-state current stability after heating treatment than the Bi/Au contact. Because of the Bi/Sb/Au contact and poly（methyl methacrylate） package, the MoS2FETs demonstrated time stability of at least two months from the almost unchanged transfer characteristics. The electrical stability indicates that the insertion of semimetallic Sb is a promising technology for reliable Bi-based contact.

关键词： temperature stability semimetallic bismuth contact semimetallic antimony contact MoS$_{2}$ FETs time stability

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Femtosecond laser fabrication of 3D vertically aligned micro-pore network on thick-film Li4Ti5O12 electrode for high-performance lithium storage

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Journal of Energy Chemistry 2024年第8期95卷 250-262页

作者： Quansheng Li Xiaofei Sun Xuesong Mei Lingzhi Wang Minxing Yang Jianlei Cui Wenjun Wang state key laboratory for Manufacturing system Engineering Xi'an Jiaotong University Shaanxi key laboratory of Intelligent Robots Xi'an Jiaotong University School of Mechanical Engineering Xi'an Jiaotong University

The development of energy storage devices with high energy density relies heavily on thick film electrodes, but it is challenging due to the limited ion transport kinetics inherent in thick electrodes. Here,we report on the preparation of a directional vertical array of micro-porous transport networks on LTO electrodes using a femtosecond laser processing strategy, enabling directional ion rapid transport and achieving good electrochemical performance in thick film electrodes. Various three-dimensional(3D)vertically aligned micro-pore networks are innovatively designed, and the structure, kinetics characteristics, and electrochemical performance of the prepared ion transport channels are analyzed and discussed by multiple characterization and testing methods. Furthermore, the rational mechanisms of electrode performance improvement are studied experimentally and simulated from two aspects of structural mechanics and transmission kinetics. The ion diffusion coefficient, rate performance at 60 C,and electrode interface area of the laser-optimized 60-15% micro-porous transport network electrodes increase by 25.2 times, 2.2 times, and 2.15 times, respectively than those of untreated electrodes.Therefore, the preparation of 3D micro-porous transport networks by femtosecond laser on ultra-thick electrodes is a feasible way to develop high-energy batteries. In addition, the unique micro-porous transport network structure can be widely extended to design and explore other high-performance energy materials.

关键词： Femtosecond laser Ion transport kinetics Laser processing Micro-porous transport networks Thick film electrodes

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Influence of Anteroposterior Symmetrical Aero-Wings on the Aerodynamic Performance of High-Speed Train

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Computer Modeling in Engineering & Sciences 2024年第4期139卷 937-953页

作者： Peiheng He Jiye Zhang Lan Zhang Jiaqi Wang Yuzhe Ma state key laboratory of Rail Transit Vehicle system Southwest Jiaotong UniversityChengdu610031China

The running stability of high-speed train is largely constrained by the wheel-rail coupling relationship,and the continuous wear between the wheel and rail surfaces will profoundly affect the dynamic performance of the train.In recent years,under the background of increasing train speed,some scientific researchers have proposed a new idea of using the lift force generated by the aerodynamic wings(aero-wing)installed on the roof to reduce the sprung load of the carriage in order to alleviate the wear and tear of the wheel and rail.Based on the bidirectional running characteristics of high-speed train,this paper proposes a scheme to apply aero-wings with anteroposterior symmetrical cross-sections on the roof of the train.After the verification of the wind tunnel experimental data,the relatively better airfoil section and extension formof anteroposterior symmetrical aero-wing is selected respectively in this paper,and the aero-wings are fixedly connected to the roof of the train through the mounting column to conduct aerodynamic simulation analysis.The research shows that:compared with the circular-arc and oval crosssections,this paper believes that the crescent cross-section can form greater aerodynamic lift force in a limited space.Considering factors such as aerodynamic parameters,ground effect,and manufacturing process,this paper proposes to adopt aero-wings with arc type extension form and connect them to the roof of the train through mounting columns with shuttle cross-section.When the roof of the train is covered with aero-wings and runs at high speed,the sprung load of the carriages can be effectively reduced.However,there are certain hidden dangers in the tail carriage due to the large amount of lift force,so,the intervention of the aero-wing lifting mechanism is required.At the same time,it is necessary to optimize the overall aerodynamic drag force reduction in the followup work.

关键词： Anteroposterior symmetrical aero-wing wheel-rail wear aerodynamic lift force ground effect numerical simulation

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