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Differentially Private Distributed Parameter Estimation

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Journal of Systems Science & Complexity 2023年第1期36卷 187-204页

作者： wang jimin TAN Jianwei ZHANG Ji-Feng School of Automation and Electrical Engineering University of Science and Technology BeijingBeijing 100083China Key Laboratory of Systems and Control Institute of Systems ScienceAcademy of Mathematics and Systems ScienceChinese Academy of SciencesBeijing 100190China School of Mathematical Sciences University of Chinese Academy of SciencesBeijing 100049China

Data privacy is an important issue in control systems,especially when datasets contain sensitive information about *** this paper,the authors are concerned with the differentially private distributed parameter estimation problem,that is,we estimate an unknown parameter while protecting the sensitive information of each ***,the authors propose a distributed stochastic approximation estimation algorithm in the form of the differentially private consensus+innovations(DP-CI),and establish the privacy and convergence property of the proposed ***,it is shown that the proposed algorithm asymptotically unbiased converges in mean-square to the unknown parameter while differential privacy-preserving holds for finite number of ***,the exponentially damping step-size and privacy noise for DP-CI algorithm is *** estimate approximately converges to the unknown parameter with an error proportional to the step-size parameter while differential privacy-preserving holds for all *** tradeoff between accuracy and privacy of the algorithm is effectively ***,a simulation example is provided to verify the effectiveness of the proposed algorithm.

关键词： Differential privacy distributed parameter estimation stochastic approximation

Privacy security in control systems

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Science China(Information Sciences) 2021年第7期64卷 227-229页

作者： Jifeng ZHANG Jianwei TAN jimin wang Academy of Mathematics and Systems Science Chinese Academy of Sciences School of Mathematical Sciences University of Chinese Academy of Sciences

Privacy issues in control systems are getting more and more attention from both industry and research. In recent years,information technology and artificial intelligence technology are being increasingly employed in emerging applications such as the Internet-of-Things [1], cloud-based control systems, smart buildings, autonomous vehicles, and 5G networks.

关键词： Information Systems and Communication Service

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Chinese Science Bulletin 2008年第14期53卷 2230-2238页

作者： LIAN JiJian wang jimin GU JinDe School of Civil Engineering Tianjin University Tianjin 300072 China

Similarity law is the conversion rule between model and prototype, on which a lot of research works have been done, with no agreement reached referring to the similarity law of fluctuating pressure fre- quency spectrum. Experimental data of peak frequency and dominant frequency range of fluctuating pressure spectrum beneath hydraulic jump obtained from serial models of scales 1:1, 1:2 and 1:5 are compared. As a result, similarity law of fluctuating pressure spectrum in the strongly rolling area agrees with the gravity law. As peak frequency and dominant frequencies of fluctuating pressures in hydraulic jump, toe and tail are rather low, and the similarity is often misunderstood to be λf = 1. However, the normalized spectrums of fluctuating pressures show that the similarity nearly agrees with the gravity law.

关键词：水跃脉冲压力相似性水资源利用

Numerical Investigation of Heat Transfer Characteristics of Supercritical CO_2 Tube in Combustion Chamber of Coal-Fired Boiler

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Journal of Thermal Science 2019年第3期28卷 442-453页

作者： wang jimin CHEN Xue ZHANG Chao GU Mingyan CHU Huaqiang School of Energy and Environment Anhui University of Technology

To achieve compact structure, light weight, and high thermal efficiency for the coal-fired boiler, the supercritical CO_2 power cycle has been considered as one of the promising alternatives in the coal-fired power conversion system. One of the major problems concerning fossil fuel powered plants is the safety of the water wall in boiler design. In this work, the heat transfer characteristics of the supercritical CO_2 tube in the combustion chamber were determined through the low Reynolds number k-ε model, the gas real model and the P-1 radiation model. The study covered the supercritical CO_2 tube and the fins, and the annulus flue gas passage was also included. The wall temperature and the heat transfer coefficient were compared against those obtained from the experiments. Based on the examinations of the calculated flow and turbulence fields, the distributions of the velocity and the temperature inside the supercritical CO_2 tube in the combustion chamber were resolved numerically. Moreover, the effects of the heat transfer coefficient on the heat transfer characteristics were also discussed. And it was numerically focused on the influence of the inclined angle on the flow and the heat transfer of the supercritical CO_2 tube. The results show that the heat transfer coefficient keeps namely constant as the increasing inclined angle. It would help to better understand the heat transfer mechanism of unique characteristics of supercritical CO_2 above the pseudo-critical temperature, which may provide the corresponding theoretical basis on the optimization design of the coal-fired boiler.

关键词： supercritical CO2 numerical simulation combustion chamber heat transfer characteristics inclined angle

Who is Going to Supply the Milk to China's South?

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China & World Economy 2008年第4期16卷 94-109页

作者： jimin wang Zhangyue Zhou Qiuhong Shen Professor Institute of Agricultural Economics Chinese Academy of Agricultural Sciences Beijing Associate Professor School of Business James Cook University Townsville Australia Researcher Institute of Agricultural Economics Chinese Academy of Agricultural Sciences Beijing

China＇s dairy industry has experienced rapid expansion in recent years, with an average annual growth rate of 23.8 percent from 2000 to 2006. However, there exists a serious geographical distribution imbalance in milk production and consumption. Approximately 85 percent of China＇s milk is produced in northern China, where 40 percent of the country＇s population reside. In contrast, only about 15 percent of the milk is produced in China＇s south, where 60percent of China＇s population reside. This has resulted in a significant gap between milk production and consumption in southern China and this gap is expected to rise. This paper considers China＇s milk demand and supply situation, analyzes the likely potential for China to expand its milk production and explores options for meeting milk demand-supply shortages. Policy and trade implications are discussed.

关键词： dairy trade milk consumption milk production southern China

Reflective spectrum broadened by nano-particle-network in chiral liquid crystals

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Frontiers of Optoelectronics 2008年第Z1期1卷 188-191页

作者： Ziqiang HUANG Wenjun YANG jimin wang Opto-Electronic Information School University of Electronic Science and Technology of China

Based on the analytical expression of the electromagnetic field solution of a helical symmetric dielectric material, the relationship between spectral reflectivity and birefringence of a chiral liquid crystal and the blue shift of the Bragg reflection in the condition of oblique incidence are presented in this paper. The theoretical results indicated that: 1) If birefringence(Δn)of the liquid crystal is greater than 0.2 and the thickness of the liquid crystal layer reaches 3μm, the liquid crystal layer will reflect more than 90% of the incident light; 2)To reflect the whole visible spectrum by Bragg reflection,Δn of the liquid crystals in plane alignment state should exceed 0.6; 3) When the incident beam inclines to 60°from the normal direction, the blue shift of the reflective spectrum will reach to 100 nm. On the other hand, since the Δn of the commercial chiral liquid crystals is not larger than 0.2, to get the entire visible reflective spectrum, it needs to introduce a polymer network into the liquid crystals and make a sagging structure on the surface of substrates. The contribution of the network is to establish random anchorage that makes the pitch varied, hence broadening the Bragg reflection *** random distribution of the sagging structure on the surface substrate is used to induce random screw axes of the chiral liquid crystal, which not only causes a blue shift of Bragg reflection but also further stretches the reflection spectra. Experiments demonstrated that the Bragg reflection spectrum could be broadened from80 nm to more than 120 nm, and the contrast reaches 4:1by introducing both polymer network and sagging structure on the substrate surface cell.

关键词： reflective spectrum chiral liquid crystal cholesteric nano-particle-network

Giant dipole resonance parameters from photoabsorption cross-sections

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Chinese Physics C 2019年第11期43卷 77-84页

作者： Yuan Tian Xi Tao jimin wang Xianbo Ke Ruirui Xu Zhigang Ge China Nuclear Data Center China Institute of Atomic EnergyP.O.Box 275(41)Beijing 102413China Guangxi Normal University GuilinGuangxi Province541004China

The structural effect is believed to have no influence on the decay properties of medium and heavy-mass nuclei at excitation energies above the pairing *** properties can be described by statistical properties using so-called photon strength functions for different multipolarities,and directly related to the photoabsorption cross-section(σabs).σabs is dominated by the electric giant dipole resonance at y energy εγ≤40 *** this study,we construct two kinds of systematic giant dipole resonance parameters by fitting the experimental photoabsorption *** is based on the microscopic relativistic quasiparticle random phase approximation approach,whereas the other is estimated by the phenomenological models within the Lorentzian *** of them are demonstrated of efficiently describe the experimental photoabsorption cross-sections available for medium to heavymass nuclei,and they can obtain more reliable predictions for the unknown nuclear system.

关键词： photon strength functions RQRPA SMLO GDR

Engineering rock mechanics practices in the underground powerhouse at JinpingⅠhydropower station

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Journal of Rock Mechanics and Geotechnical Engineering 2016年第5期8卷 640-650页

作者： Aiqing Wu jimin wang Zhong Zhou Shuling Huang Xiuli Ding Zhihong Dong Yuting Zhang Key laboratory ofGeotechnical Mechanics and Engineering of the Ministry ofWaterResources Yangtze RiverScientificResearch InstituteWuhan430010China Yalong River Hydropower Development Company Ltd.Chengdu610051China HydroChina Chengdu Engineering Corporation Ltd.Chengdu610072China

Based on the analyses of data obtained from the underground powerhouse at Jinping I hydropower station, a comprehensive review of engineering rock mechanics practice in the underground powerhouse is first conducted. The distribution of strata, lithology, and initial geo-stress, the excavation process and corresponding rock mass support measures, the deformation and failure characteristics of the surrounding rock mass, the stress characteristics of anchorage structures in the cavern complex, and numerical simulations of surrounding rock mass stability and anchor support performance are presented. The results indicate that the underground powerhouse of Jinping I hydropower station is characterized by high to extremely high geo-stresses during rock excavation. Excessive surrounding rock mass deformation and high stress of anchorage structures, surrounding rock mass unloading damage, and local cracking failure of surrounding rock masses, etc., are mainly caused by rock mass excavation. Deformations of surrounding rock masses and stresses in anchorage structures here are larger than those found elsewhere： 20% of extensometers in the main powerhouse record more than 50 mm with the maximum at around 250 mm observed in the downstream sidewall of the transformer hall. There are about 25% of the anchor bolts having recorded stresses of more than 200 MPa. Jinping I hydropower plant is the first to have an underground powerhouse construction conducted in host rocks under extremely high geo-stress conditions, with the ratio of rock mass strength to geo-stress of less than 2.0. The results can provide a reference to underground powerhouse construction in similar geological conditions.

关键词： Underground powerhouse High geo-stress Rock mechanics Rock mass stability Engineering practice

Preliminary engineering application of microseismic monitoring technique to rockburst prediction in tunneling of Jinping Ⅱ project

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Journal of Rock Mechanics and Geotechnical Engineering 2010年第3期2卷 193-208页

作者： Chun＇an Tang jimin wang Jingjian Zhang School of Civil Engineering Dalian University of TechnologyDalian116024China Jinping Construction Management Authority Ertan Hydropower Development Co.Ltd.Xichang615012China School of Hydraulic Engineering North China Institute of Water Conservancy and Hydroelectric PowerZhengzhou450011China

Monitoring and prediction of rockburst remain to be worldwide challenges in geotechnical *** hydropower,transportation and other engineering fields in China,more deep,long and large tunnels have been under construction in recent years and underground caverns are more evidently featured by ＂long,large,deep and in group＂,which bring in many problems associated with rock mechanics problems at great depth,especially *** lead to damages to not only underground structures and equipments but also personnel *** has been a major technical bottleneck in future deep underground engineering in *** this paper,compared with earthquake prediction,the feasibility in principle of monitoring and prediction of rockbursts is discussed,considering the source zones,development cycle and *** authors think the feasibility of rockburst prediction can be understood in three aspects：（1） the heterogeneity of rock is the main reason for the existence of rockburst precursors;（2） deformation localization is the intrinsic cause of rockburst;and（3） the interaction between target rock mass and its surrounding rock mass is the external cause of *** an engineering practice,the application of microseismic monitoring techniques during tunnel construction of Jinping II Hydropower Station was *** is found that precursory microcracking exists prior to most rockbursts,which could be captured by the microseismic monitoring *** stress concentration is evident near structural discontinuities（such as faults or joints）,which shall be the focus of rockburst *** is concluded that,by integrating the microseismic monitoring and the rock failure process simulation,the feasibility of rockburst prediction is expected to be enhanced.

关键词： microseismic monitoring numerical modeling rockburst prediction