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Validation method for simulation models with cross iteration

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Journal of Systems Engineering and Electronics 2019年第3期30卷 555-563页

作者： FANG Ke ZHAO Kaibin ZHOU yuchen Control and Simulation Center Harbin Institute of Technology

Cross iteration often exists in the computational process of the simulation models, especially for control models. There is a credibility defect tracing problem in the validation of models with cross iteration. In order to resolve this problem, after the problem formulation, a validation theorem on the cross iteration is proposed, and the proof of the theorem is given under the cross iteration circumstance. Meanwhile, applying the proposed theorem, the credibility calculation algorithm is provided, and the solvent of the defect tracing is explained. Further, based on the validation theorem on the cross iteration, a validation method for simulation models with the cross iteration is proposed, which is illustrated by a flowchart step by step. Finally, a validation example of a sixdegree of freedom (DOF) flight vehicle model is provided, and the validation process is performed by using the validation method. The result analysis shows that the method is effective to obtain the credibility of the model and accomplish the defect tracing of the validation.

关键词： validation method simulation model cross iteration validation theorem validation example

Classification of disturbance vectors for collision attack in SHA-1

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Science China(Information Sciences) 2015年第11期58卷 103-112页

作者： TANG yuchen ZENG Guang HAN WenBao The Information Engineering University

A good disturbance vector is one of the key techniques to find SHA-1 collisions and to construct valid differential paths. The main work of this paper is to classify the types of the optimal disturbance ***, we improve the EEM disturbance vectors search algorithm by Manuel. We increase the Hamming weight of information window from 4 to 6, with 244 time complexity, which is 28 times better than that of Manuel’s work. Based on this result, we prove that there are only two types of the optimal disturbance vectors, type-I and type-II, which have minimum weight of 25 in the last 60 of the 80 expanded words, in the total 2512 disturbance vectors searching space.

关键词： Hash function SHA-1 collision attack disturbance vector extended expanded message

Changing patterns of urban-rural nutrient flows in China:driving forces and options

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Science Bulletin 2017年第2期62卷 83-91页

作者： Chaoqing Yu yuchen Xiao Shaoqiang Ni Department of Earth System Science Ministry of Education Key Laboratory for Earth System Modeling Tsinghua University Beijing 100084 China

Nutrient recycling has been practiced for thousands of years in China to maintain food production without environmental pollution. In the past three decades, however, the traditional nutrient recycling systems have been replaced with waste treatment systems, which have resulted in rapid and severe environmental pollution. By analyzing the primary driving forces of the changing nutrient flows(technology, labor costs, food supplies, fertilizer demands, environmental quality, human health, and public awareness), this paper argues that technology fundamentally motivated the nutrient-recycling strategy to address the malnutrition problem in traditional societies but has constrained the reconstruction of nutrient recycling systems in modern cities. With the availability of synthetic fertilizers in modern society, the lack of interdisciplinary views in policy making for nutrient management is the root cause of today's environmental situation. Ongoing fast urbanization has concentrated more nutrients in urban areas, creating the need for a national nutrient management plan to coordinate multiple ministries and fix the uncoupled nutrient cycling between urban and rural systems. Rebuilding the traditional nutrient-recycling systems is an environmentally and economically effective solution. There are three fundamental technological barriers to reconstructing the nutrient recycling systems, as follows: userfriendly toilets, the separation of sewage pipelines, and easy-to-use organic fertilizers made from human manure or other organic waste. Overcoming these barriers requires building institutional mechanisms,developing the necessary infrastructure, creating research funding, and providing open experimental platforms for technological development.

关键词：养分循环驱动力变化规律流动中国废物处理系统营养循环技术壁垒

创造“无人的荒野”:从系谱学看美国国家公园制度与土著人民人权危机

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人权研究 2024年第4期 80-102页

作者：何雨宸朱明哲中国政法大学比较法学研究院格拉斯哥大学法学院

环境法学者往往强调国家公园的生态保护功能,却忽略了这一制度带来的政治社会关系变革。从系谱学的视角分析和整理美国的国家公园制度在1872年创立时的社会背景、立法过程和司法判决,将揭示该制度对定居者、土著人民和环境三者关系的重... 详细信息

环境法学者往往强调国家公园的生态保护功能,却忽略了这一制度带来的政治社会关系变革。从系谱学的视角分析和整理美国的国家公园制度在1872年创立时的社会背景、立法过程和司法判决,将揭示该制度对定居者、土著人民和环境三者关系的重构。早期国家公园的建立始终伴随着对印第安人的殖民压迫,造成了严重的人权危机。这一制度设立的初衷是满足来自欧洲的殖民定居者身份认同与宗教信仰的需求,并在实施中逐渐演化成了现代国家进行殖民掠夺的制度工具。通过污名化印第安人的生计、否认其条约权利和暴力驱逐等方式,美国政府在19世纪把早期国家公园变成了“无人的荒野”,剥夺了国家公园界内及附近土著人民的生存权、土地权和自然资源权。无论是19世纪盛行的天命论还是现在为国家公园制度辩护的生态话语,都无法正当化国家公园制度背后的霸权结构和殖民主义色彩。

关键词：美国国家公园土著人民人权危机生态殖民

On the improved tensile strength and ductility of Mg-Sn-Zn-Mn alloy processed by aging prior to extrusion

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Journal of Magnesium and Alloys 2019年第4期7卷 637-647页

作者： Liping Zhong Yongjian Wang yuchen Dou College of Materials Science and Engineering Sichuan University of Science&EngineeringZigong 643000China Material Corrosion and Protection Key Laboratory of Sichuan province Zigong 643000China

This study investigated the influence of aging prior to extrusion(APE)on the tensile strength and ductility of as-extruded Mg-8.32Sn-1.85Zn-0.17Mn *** demonstrated that APE treatment dramatically increased the volume fraction of recrystallized grains,thereby decreasing the grain size of the as-extruded *** phenomenon was primarily attributed to the particle-stimulated nucleation and pinning effect induced by large amounts of small Mg 2 Sn precipitates produced by the APE treatment and dynamic *** tensile yield strength increased from 242.4 MPa to 256.5 MPa after APE *** improved tensile strength can be attributed to the enhanced grain boundary strengthening and precipitation *** ductility of the as-extruded alloy also markedly increased from 7.1%to 13.5%after the APE *** improved ductility of APE alloy was attributed to the texture randomization,the activity of pyramidalslip and the suppressed formation of{10-11}contraction twins and coarse Mg 2 Sn phases.

关键词： Mg-Sn based alloy Aging prior to extrusion Microstructure Mechanical properties

Online distributed optimization with stochastic gradients:high probability bound of regrets

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Control Theory and Technology 2024年第3期22卷 419-430页

作者： yuchen Yang Kaihong Lu Long Wang Center for Systems and Control College of EngineeringPeking UniversityBeijing 100871China College of Electrical Engineering and Automation Shandong University of Science and TechnologyQingdao 266590ShandongChina

In this paper,the problem of online distributed optimization subject to a convex set is studied via a network of *** agent only has access to a noisy gradient of its own objective function,and can communicate with its neighbors via a *** handle this problem,an online distributed stochastic mirror descent algorithm is *** works on online distributed algorithms involving stochastic gradients only provide the expectation bounds of the *** from them,we study the high probability bound of the regrets,i.e.,the sublinear bound of the regret is characterized by the natural logarithm of the failure probability's *** mild assumptions on the graph connectivity,we prove that the dynamic regret grows sublinearly with a high probability if the deviation in the minimizer sequence is sublinear with the square root of the time ***,a simulation is provided to demonstrate the effectiveness of our theoretical results.

关键词： Distributed optimization Online optimization Stochastic gradient High probability

Cyclin-dependent Kinase 18 Promotes Oligodendrocyte Precursor Cell Differentiation through Activating the Extracellular Signal-Regulated Kinase Signaling Pathway

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Neuroscience Bulletin 2019年第5期35卷 802-814页

作者： yuchen Pan Zeping Jiang Dingya Sun Zhenghao Li Yingyan Pu Dan Wang Aijun Huang Cheng he Li Cao Institute of Neuroscience Key Laboratory of Molecular Neurobiology of the Ministry of Education and the Collaborative Innovation Center for Brain Science Second Military Medical University Shanghai 200433 China Department of Internal Medicine Jiangsu Provincial Corps Hospital Chinese People’s Armed Police Force Yangzhou 225003 China

The correct differentiation of oligodendrocyte precursor cells(OPCs) is essential for the myelination and remyelination processes in the central nervous *** the regulatory mechanism is fundamental to the treatment of demyelinating diseases. By analyzing the RNA sequencing data of different neural cells, we found that cyclin-dependent kinase 18(CDK18) is exclusively expressed in oligodendrocytes. In vivo studies showed that the expression level of CDK18 gradually increased along with myelin formation during development and in the remyelination phase in a lysophosphatidylcholine-induced demyelination model, and was distinctively highly expressed in oligodendrocytes. In vitro overexpression and interference experiments revealed that CDK18 directly promotes the differentiation of OPCs, without affecting their proliferation or apoptosis. Mechanistically, CDK18 activated the RAS/mitogen-activated protein kinase kinase1/extracellular signal-regulated kinase pathway, thus promoting OPC differentiation. The results of the present study suggest that CDK18 is a promising cell-type specific target to treat demyelinating disease.

关键词： OPC Oligodendrocyte Myelination CDK18 ERK

New Results in Cooperative Adaptive Optimal Output Regulation

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Journal of Systems Science & Complexity 2024年第1期37卷 253-272页

作者： DONG yuchen GAO Weinan JIANG Zhong-Ping State Key Laboratory of Synthetical Automation for Process Industries Northeastern UniversityShenyang 110819China Department of Electrical and Computer Engineering Tandon School of EngineeringNew York UniversityBrooklynNY 11201USA

This paper investigates the cooperative adaptive optimal output regulation problem of continuous-time linear multi-agent *** the multi-agent system dynamics are uncertain,solving regulator equations and the corresponding algebraic Riccati equations is challenging,especially for high-order *** this paper,a novel method is proposed to approximate the solution of regulator equations,i.e.,gradient descent *** is worth noting that this method obtains gradients through online data rather than model information.A data-driven distributed adaptive suboptimal controller is developed by adaptive dynamic programming,so that each follower can achieve asymptotic tracking and disturbance ***,the effectiveness of the proposed control method is validated by simulations.

关键词： Adaptive dynamic programming cooperative output regulation gradient descent method multi-agent systems.

不同连接刚度二次设备柜振动台试验与数值模拟研究

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河北工业科技 2024年第6期41卷 450-460页

作者：程智余张天忠胡广润王开库何宇辰冯玉龙于飞曾志豪国网安徽省电力有限公司安徽合肥230022 国网安徽省电力有限公司建设分公司安徽合肥230071 安徽送变电工程有限公司安徽合肥230071 国网安徽省电力有限公司经济技术研究院安徽合肥230022 合肥工业大学土木与水利工程学院安徽合肥230009

为了提高变电站二次设备柜抗震性能和韧性,探究了二次设备柜底部连接刚度对其动力响应的影响,对6个不同连接形式的二次设备柜进行了振动台试验。采用ABAQUS软件对试验进行了数值模拟,并对底部连接刚度进行了参数化分析。结果表明:底部... 详细信息

为了提高变电站二次设备柜抗震性能和韧性,探究了二次设备柜底部连接刚度对其动力响应的影响,对6个不同连接形式的二次设备柜进行了振动台试验。采用ABAQUS软件对试验进行了数值模拟,并对底部连接刚度进行了参数化分析。结果表明:底部螺丝数量显著影响设备柜基本频率,螺丝数量增加2倍后,设备柜的基本频率增大了61.8%;试验后拼柜基本频率最大下降了17.2%,在所有设备柜中下降幅度最大,应加强拼柜的底部连接刚度;地震作用下设备柜发生强度破坏的可能性较小,随着底部螺丝竖向刚度的增大,设备柜的峰值加速度先增大后减小,设备柜顶部峰值加速度增大了16.6%~74.2%;随着底部螺丝水平刚度的增大,设备柜顶部峰值加速度减小了3.28%~29.6%。研究可为变电站二次设备柜的抗震设计以及地震韧性变电站的建造提供重要参考。

关键词：金属结构二次设备柜连接刚度振动台试验动力响应