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SSRN 2022年

作者： Li, Zheng-Yang Zheng, Mei-Yin Yang, Zhong-Bo Ren, Quan-Yao Cai, Zhen-Bing Jiao, Yong-Jun Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610213 China Tribology Research Institute Key Lab of Advanced Technologies of Materials Southwest Jiaotong University Chengdu610031 China

The corrosion behavior of MAO coating on Zr alloy was investigated in 400 ºC/10.3 MPa condition. The surface morphology, phase composition, and element distribution of MAO coating were analyzed. The results indicate that the oxide layer on MAO coating presents fewer cracks and pores than Zr alloy, because the high compressive stress can stabilize the t-ZrO2 and restrain the phase transformation, thus reducing the volume expansion and future decreasing defect. Based on the XRD, Raman mapping, SEM, XPS, and TEM results, the formation mechanism of t-ZrO2 and phase transformation process of MAO coating in superheated steam condition was summarized. © 2022, The Authors. All rights reserved.

关键词： Phase transitions

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Learning Pre-Grasp Manipulation of Flat Objects in Cluttered Environments using Sliding Primitives

Learning Pre-Grasp Manipulation of Flat Objects in Cluttered...

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IEEE International Conference on Robotics and Automation (ICRA)

作者： Jiaxi Wu Haoran Wu Shanlin Zhong Quqin Sun Yinlin Li State Key Laboratory of Turbulence and Complex Systems Intelligent Biomimetic Design Lab College of Engineering Peking University Beijing China Department of Automation University of Science and Technology of China Heifei China State Key Laboratory of Management and Control for Complex System Institute of Automation Chinese Academy of Science Beijing China Science and Technology on Thermal Energy and Power Laboratory Wuhan China

Flat objects with negligible thicknesses like books and disks are challenging to be grasped by the robot because of the width limit of the robot's gripper, especially when they are in cluttered environments. Pre-grasp manipulation is conducive to rearranging objects on the table and moving the flat objects to the table edge, making them graspable. In this paper, we formulate this task as Parameterized Action Markov Decision Process, and a novel method based on deep reinforcement learning is proposed to address this problem by introducing sliding primitives as actions. A weight-sharing policy network is utilized to predict the sliding primitive's parameters for each object, and a Q-network is adopted to select the acted object among all the candidates on the table. Meanwhile, via integrating a curriculum learning scheme, our method can be scaled to cluttered environments with more objects. In both simulation and real-world experiments, our method surpasses the existing methods and achieves pre-grasp manipulation with higher task success rates and fewer action steps. Without fine-tuning, it can be generalized to novel shapes and household objects with more than 85% success rates in the real world. Videos and supplementary materials are available at https://***/view/pre-grasp-sliding.

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High-Fidelity Neutronic/Thermal-Hydraulic Coupling Analysis of Plate-Type reactor based on MOOSE and cosRMC

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SSRN 2023年

作者： Chen, Junyi Liu, Guodong Huang, Shanfang He, Ying Qiu, Meiming Wang, Kan Lu, Chuan Li, Zhigang Quan, Guoping Wang, Xing Department of Engineering Physics Tsinghua University Haidian district Beijing100084 China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Shuangliu district Chengdu610213 China State Power Investment Corporation Research Institute Changping district Beijing102209 China

A full scale high-fidelity neutronic/thermal-hydraulic coupled analysis method for plate-type reactor is proposed based on the open-source Multiphysics Object-Oriented Simulation Environment (MOOSE) and Monte Carlo Code cosRMC. The two-dimensional heat transfer model and one-dimensional coolant subchannel model are established, and integrated into the thermalhydraulic analysis code SPhase. The code-to-code validations of SPhase show good agreement with that of CTF and Fluent. The detailed neutronics model and parameters schemes are verified through cosRMC to ensure accuracy of physics calculation. The criticality search is implented, and the full scale JRR-3M critical coupled simulation under steady state is realized through celllevel resolution. The thermal feedback introduces negative activity of about 400 pcm. The insertion of absorbers renders the complexity of power distribution. The reflection effect results in peak thermal neutrons flux and temperature at the edge of the core. This work provides reference for correlational studies on neutronic/thermal-hydraulic characteristics of plate-type reactor. © 2023, The Authors. All rights reserved.

关键词： Multiphysics

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Explicit design optimization of air rudders for maximizing stiffness and fundamental frequency

arXiv

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arXiv 2024年

作者： Jia, Yibo Meng, Wen Du, Zongliang Liu, Chang Li, Shanwei Wang, Conglei Ge, Zhifu Su, Ruiyi Guo, Xu State Key Laboratory of Structural Analysis Optimization and CAE Software for Industrial Equipment Department of Engineering Mechanics Dalian University of Technology Dalian116023 China Ningbo Institute of Dalian University of Technology Ningbo315016 China Beijing System Design Institute of Electro-Mechanic Engineering Beijing100854 China

In aerospace engineering, there is a growing demand for lightweight design through topology optimization. This paper presents a novel design optimization method for stiffened air rudders, commonly used for aircraft attitude control, based on the Moving Morphable Components (MMC) method. The stiffeners within the irregular enclosed design domain are modeled as MMCs and discretized by shell elements, accurately capturing their geometry and evolution during optimization process using explicit parameters. In order to maximize the stiffness and fundamental frequency of the rudder structures, numerical analysis algorithms were developed with shape sensitivity analysis conducted. To comply with the manufacturing requirement, a minimum thickness is prescribed for the stiffeners. Penalty strategies were developed for the thickness and density of stiffeners with thickness smaller than the threshold to meet the thickness requirement and suppress spurious modes. The method's effectiveness was demonstrated through optimization examples of two typical air rudders, illustrating the significance of stiffener’s distribution on design objectives. The explicit modeling characteristics allow for directly importing the optimization results into CAD systems, significantly enhancing the engineering applicability. Copyright © 2024, The Authors. All rights reserved.

关键词： Stiffness

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Small-Target Infrastructure Detection with Spatial Tracking and Multi-Level Feature Extraction of Railway Track Scenes

Small-Target Infrastructure Detection with Spatial Tracking ...

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Intelligent Communication, Sensing and Electromagnetics (ICSE), International Conference on

作者： Heng Du Huaiming Cang Yiwen Bai Xinyi Wang Beijing Elephant Technology Co. Ltd Beijing China School of Transportation Science and Engineering Beihang University Beijing China The State Key Lab of Intelligent Transportation System Beijing China Tianjin Key Laboratory for Advanced Mechanical System Design and Intelligent Control School of Mechanical Engineering Tianjin University of Technology Tianjin China National Demonstration Center for Experimental Mechanical and Electrical Engineering Education (Tianjin University of Technology) Tianjin China

ISBN: (数字)9798350354935

ISBN: (纸本)9798350354942

In the field of railway transportation, with the continuous improvement of train running speed and the continuous increase of operating mileage, it becomes particularly important to ensure the safety and integrity of small-target infrastructure along the railway train. Although many small-target detection methods have been proposed, the research on small-target infrastructure detection along rail trains is very rare. To solve this problem, this paper proposes a small-target infrastructure detection network with spatial tracking and multi-level feature extraction based on Yolov8n. The experimental results show that ST-YOLO has a 3.6% mAP improvement on the OSDaR23 dataset compared to the baseline Yolov8n, and shows significant advantages over other state-of-the-art methods.

关键词： Rails Transportation Railway safety Switches Feature extraction Rail transportation Real-time systems Sensors Safety Monitoring

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Capillary Limit of a Sodium Screen-Wick Heat Pipe

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SSRN 2022年

作者： Ma, Yugao Wang, Xueqing Yu, Hongxing Huang, Shanfang Zhang, Yingnan Huang, Jian Su, Guanghui Deng, Jian Chai, Xiaoming Hu, Wenzhen School of Nuclear Science and Technology Xi’an Jiaotong University Shanxi Xi’an710049 China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610213 China Department of Engineering Physics Tsinghua University Beijing100084 China State Key Laboratory of Multiphase Flow in Power Engineering China

High-temperature alkali-metal heat pipes are passive heat transfer devices, where the capillary pressure created by the menisci in the wick pumps the condensed fluid back to the evaporator. Thus, the heat pipe heat transfer capacity is limited by the maximum capillary pressure at high heat fluxes. This work presents a two-dimensional heat and mass transfer model that includes the capillary and gravitational forces that are used to predict the capillary limit which is then validated by experimental data. The predicted critical heat flux temperature has an error of less than 20℃ and a relative error of 6%. The predicted transient sequences are consistent with the measurements. The model shows that capillary limit is affected by inclination angle, heat flux, and wick structure. For inclinations, the critical heat flux at the capillary limit is linearly related to the inclination angle with the predicted temperature rising 2 ~10℃/s during the early stage of the capillary limit critical heat flux condition. The evaporator temperature oscillates before the capillary limit with positive inclinations. For heat fluxes, increasing the heat flux by 17% increases the temperature increase rate 10 fold with a longer dryout length. The evaporator exhibits hysteresis after the capillary limit due to partial dryout of evaporator. For wick structures, reducing the mesh screen pitch from 80 μm to 15 μm reduces the critical heat flux to 10% of the CHF at 80 μm. This model can accurately predict the heat pipe temperature variations at the capillary limit and can explain the physical mechanisms for the dryout oscillations and recovery hysteresis at the capillary limit. Thus, the measurements and model provide analytical guidelines for designing heat pipe cooling systems. © 2022, The Authors. All rights reserved.

关键词： Heat flux

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Direction Finding With Single Phase Pattern Reconfigurable Antenna

Direction Finding With Single Phase Pattern Reconfigurable A...

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IEEE Asia-Pacific Conference on Antennas and Propagation (APCAP)

作者： Siyu Zhou Dapeng Jiang Shuangshuang Zhu Ziheng Ding Jingfeng Chen Department of Electronic Engineering Shanghai Jiao Tong University Shanghai China China Ship Development and Design Center Wuhan China GoerTek Technology Co. Ltd. Qingdao China State Key Laboratory of Avionics Integration and Aviation System-of-Systems Synthesis

ISBN: (数字)9798350351019

ISBN: (纸本)9798350351026

This paper presents a novel direction-finding method that requires only a single phase pattern reconfigurable antenna. By controlling the switching of the antenna’s working state, a phase difference varied with the incident angle can be obtained from the radio frequency (RF) single channel by analyzing the harmonic components generated from periodic modulation. Utilizing the one-to-one correspondence between the phase difference and the incident angle, the direction can be estimated by the lookup table method. The proposed method realizes single antenna direction finding while retaining the advantage of the single channel and further simplifies the system structure. Simulation results verify the feasibility of the proposed method with the incidence angle ranging from -30° to 30°.

关键词： Radio frequency Navigation Phase modulation Simulation Switches Directive antennas Harmonic analysis Control systems Distance measurement Periodic structures

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Mixture of Experts for Intelligent Networks: A Large Language Model-enabled Approach

Mixture of Experts for Intelligent Networks: A Large Languag...

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International Wireless Communications and Mobile Computing Conference, IWCMC

作者： Hongyang Du Guangyuan Liu Yijing Lin Dusit Niyato Jiawen Kang Zehui Xiong Dong In Kim School of Computer Science and Engineering Nanyang Technological University Singapore Singapore State Key Laboratory of Networking and Switching Technology Beijing University of Posts and Telecommunications Beijing China School of Automation Guangdong University of Technology and Key Laboratory of Intelligent Information Processing and System Integration of IoT Ministry of Education Guangzhou China Guangdong-HongKong-Macao Joint Laboratory for Smart Discrete Manufacturing Guangzhou China Pillar of Information Systems Technology and Design Singapore University of Technology and Design Singapore Singapore Department of Electrical and Computer Engineering Sungkyunkwan University Suwon South Korea

ISBN: (数字)9798350361261

ISBN: (纸本)9798350361278

Optimizing various wireless user tasks poses a significant challenge for networking systems because of the expanding range of user requirements. Despite advancements in Deep Reinforcement Learning (DRL), the need for customized optimization tasks for individual users complicates developing and applying numerous DRL models, leading to substantial computation resource and energy consumption and can lead to inconsistent outcomes. To address this issue, we propose a novel approach utilizing a Mixture of Experts (MoE) framework, augmented with Large Language Models (LLMs), to analyze user objectives and constraints effectively, select specialized DRL experts, and weigh each decision from the participating experts. Specifically, we develop a gate network to oversee the expert models, allowing a collective of experts to tackle a wide array of new tasks. Furthermore, we innovatively substitute the traditional gate network with an LLM, leveraging its advanced reasoning capabilities to manage expert model selection for joint decisions. Our proposed method reduces the need to train new DRL models for each unique optimization problem, decreasing energy consumption and AI model implementation costs. The LLMenabled MoE approach is validated through a general maze navigation task and a specific network service provider utility maximization task, demonstrating its effectiveness and practical applicability in optimizing complex networking systems.

关键词： Wireless communication Energy consumption Navigation Computational modeling Logic gates Probability Throughput

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On the Adaptive Damper system of the Electric reactor Based on Magnetorheological Fluid 6

On the Adaptive Damper System of the Electric Reactor Based ...

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2021 6th International Symposium on Advances in Electrical, Electronics and Computer Engineering, ISAEECE 2021

作者： Tian, Tian Zhou, Yuan Yang, Qiong Wang, Jingang Xu, Changjian Department Chongqing Electric Power Design Institute Co. Ltd Chongqing401121 China Department State Key Laboratory of Power Transmission Equipment and System Security and New Technology Chongqing400044 China

The electric reactor will generate irregular electromagnetic vibration during the onsite operation of substation. If so for a long time, it will cause problems such as broken indoor floor and loose connecting parts, endanger the building structure or damage to the building, thus leading to waste of land resources in indoor substation. In order to effectively suppress the irregular electromagnetic vibration of the electric reactor, this paper proposed an adaptive damper system of the electric reactor based on magnetorheological fluid to realize the all-around vibration suppression of reactor field vibration. This system placed the homemade damper in the center of each surface of the reactor, and used external filter circuit and signal amplification circuit to process the vibration signal and transform it into electrical signal, which controlled the single-chip microcomputer to regulate the damper to output the damping force, forming an adaptive damper system based on the magnetorheological fluid. Then, the good performance of vibration reduction of the system was verified by the onsite vibration reduction test of the reactor. And the adaptive regulate ability of the system is superior and is of good engineering application value. © Published under licence by IOP Publishing Ltd.

关键词： Signal processing

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Record 46.2Pbit · km/s real-time optical transmission over 1050-km G.652.D SSMF utilizing 400-Gbit/s transponder with a symbol rate of 91.6-GBaud

Record 46.2Pbit · km/s real-time optical transmission over ...

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OptoElectronics and Communications Conference, OECC

作者： Anxu Zhang Yuyang Liu Lipeng Feng Kai Lv Huan Chen Yuting Du Guangnan Su Xiaoli Huo Junjie Li State Key Laboratory of Optical Fiber and Cable Manufacture Technology China Telecom Research Institute Beijing China WDM system design department of wireline product R&D institute ZTE Corporation Wuhan China

We experimentally demonstrated a 110-channel 44-Tbit/s real-time wavelength division multiplexing (WDM) transmission over 1050-km G.652.D single-mode fiber (SMF) utilizing 400-Gbit/s transponders with a symbol rate of 91.6GBaud and 11-THz commercial C+L band Erbium-doped fiber amplifiers (EDFAs). To the best of our knowledge, this is a record capacity distance product $(46.2-Pbit\cdot km/s)$ in the real-time optical transmission systems.

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