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中国电机工程学报 2013年第7期33卷 I0001-I0026页

作者： liu zhenya ZHANG Qiping State Grid Corporation of China

Hierarchical mobility prediction in the future heterogeneous networks for the tradeoff between accuracy and complexity

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The Journal of China Universities of Posts and Telecommunications 2019年第3期26卷 15-24页

作者： liu zhenya Li Xi Ji Hong Zhang Heli Key Laboratory of Universal Wireless Communications Beijing University of Posts and Telecommunications Beijing 100876 China School of Information and Communication Engineering Beijing University of Posts and Telecommunications Beijing 100876 China

Mobility prediction is one of the promising technologies for improving quality of service(QoS) and network resource utilization. In future heterogeneous networks(HetNets), the network topology will become extremely complicated due to the widespread deployment of different types of small-cell base stations(SBSs). For this complex network topology, traditional mobility prediction methods may cost unacceptable overhead to maintain high prediction accuracy. This problem is studied in this paper, and the hierarchical mobility prediction scheme(HMPS) is proposed for the future HetNets. By dividing the entire process into two prediction stages with different granularity, the tradeoff between prediction accuracy and computational complexity is investigated. Before performing prediction of user mobility, some frequently visited locations are identified from the user’s trajectory, and each location represents an important geographic area(IGA). In the coarse-grained prediction phase, the next most possible location to be visited is predicted at the level of the possible geographic areas by using a second-order Markov chain with fallback. Then, the fine-grained prediction of user position is performed based on hidden Markov model(HMM) from temporal and spacial dimensions. Simulation results demonstrate that, compared with the existing prediction methods, the proposed HMPS can achieve a good compromise between prediction accuracy and complexity.

关键词： mobility prediction heterogeneous networks prediction accuracy and complexity Markov chain, HMM

Understanding the Chinese stock market:international comparison and policy implications

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Economic and Political Studies 2017年第4期5卷 441-455页

作者： zhenya liu Shixuan Wang China Financial Policy Research Center School of FinanceRenmin University of ChinaBeijingChina Department of Economics University of BirminghamBirminghamUK Cardiff Business School Cardiff UniversityCardiffUK

The definitions of the bear,sidewalk and bull markets are ambiguous in the existing *** makes it difficult for practitioners to distinguish between different market *** this paper,we propose statistical definitions of the bear,sidewalk and bull markets,which correspond to the three states in our hidden semi-Markov *** apply this analysis to the daily returns of the Chinese stock market and seven developed *** the Viterbi algorithm to globally decode the most likely sequence of the market conditions,we systematically find the precise timing of the bear,sidewalk and bull markets for all the eight *** the comparison of the estimation and decoding results,many unique characteristics of the Chinese stock market are revealed,such as‘crazy bull’,‘frequent and quick bear’and‘no buffer zone’.In China,the bull market is more volatile than in developed markets,the bear market occurs more frequently than in developed markets,and the sidewalk market has not functioned as a buffer zone since *** causes of these unique characteristics are also discussed and implications for policy-making are suggested.

关键词： Chinese stock market asset return hidden semi-Markov model market conditions policy implications

Asymptotic Marginal Tax Rate of Individual Income Tax in China

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Economic and Political Studies 2014年第2期2卷 121-138页

作者： zhenya liu WU YANG DAVID DICKINSON the School of Finance Renmin University of China he Department of Economics University of Birmingham the School of International Trade and Economics Central University of Finance and Economics of China the Department of Economics University of Birmingham

This paper examines the asymptotic marginal rate of individual income tax which maximizes China's social welfare through numerical simulation based on the elasticity of China's labor supply, income distribution and the social objectives of redistribution in accordance with the optimal direct taxation theory. Taking advantage of the optimal direct taxation model with consideration of the income effect, it comes to the conclusion that combined with China's reality, the asymptotic marginal rate of individual labor income tax in China should be between 35% and 40%.

关键词： reform of individual income tax asymptotic marginal tax rate optimal direct taxation theory

Study on the sunny-shady slope effect on the subgrade of a high-speed railway in a seasonal frozen region

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Research in Cold and Arid Regions 2015年第5期7卷 513-519页

作者： QingZhi Wang BoWen Tai zhenya liu JianKun liu School of Civil Engineering Beijing Jiaotong University

The temperature distributions of different parts of a subgrade were analyzed based on the results of three years of moni- toring data from the Harbin-Qiqihaer Passenger Dedicated Line, a high-speed railway, including the slope toes, shoulders, and natural ground. The temperature variation with time and the maximum frozen depths showed that an obvious sun- ny-shady effect exists in the railway subgrade, which spans a seasonal frozen region. Development of frost heave is af- fected by the asymmetric temperature distribution. The temperature field and the maximum frozen depths 50 years after the subgrade was built were simulated with a mathematical model of the unsteady phase transition of the geothermal field.

关键词： high-speed railway sunny-shady slope effect frost heave temperature field

A Concept Discussion on Northeast Asia Power Grid Interconnection

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CSEE Journal of Power and Energy Systems 2016年第4期2卷 87-93页

作者： zhenya liu Gesong Chen Xiupeng Guan Qiankun Wang Wei He Global Energy Interconnection Development and Cooperation Organization Beijing 100031China State Grid Jibei Electric Power Company Limited Beijing 100053China

Northeast Asia is one of world’s major economic and energy consumption *** in this region are undergoing rapid economic and social development,and energy security and greenhouse gas emission reduction have become prominent *** this region,clean energy resources including hydro,wind,and solar are concentrated in Russia,Mongolia,and Northeast China,whilst electricity load centers are in East China,Korea and ***,an energy and electricity model has been developed to project electricity demand through 2030 for each *** on the idea of a Global Energy Interconnection,this article proposes to establish a Northeast Asia Grid Interconnection(NEAG),connecting Mongolia,China,Korea,Japan,and Russia with large volumes of transmission lines,in an effort to facilitate optimized resource *** NEAG would be accomplished step by step along with identification of key *** is set to play an important role in establishing the NEAG by providing a strong sending grid and necessary technological *** economic,environmental,and social benefits are expected to be generated by the NEAG.

关键词： Clean energy resources global energy interconnection(GEI) grid interconnection power flow power supply and demand

Compressive strength and frost heave resistance of different types of semi-rigid base materials after freeze-thaw cycles

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Research in Cold and Arid Regions 2015年第4期7卷 365-369页

作者： zhenya liu JingYu liu QingZhi Wang JianKun liu School of Civil Engineering Beijing Jiaotong University

Freeze-thaw damage is the most common disease of semi-rigid bases in cold regions, which may greatly affect the dura- bility of roadways. In this study, the compressive strength and frost resistance of four different types of semi-rigid bases （lime-fly ash-stabilized sand, cement-stabilized sand, lime-fly ash-stabilized gravel, and cement-stabilized gravel） are assessed by varying the materials content. Based on freeze-thaw and compressive strength tests, this paper presents the performance of the different materials, each having different physical properties, and the optimal amounts of materials contents are proposed.

关键词： freeze-thaw cycles semi-rigid base stabilized base

Study on the Application of UHVDC Hierarchical Connection Mode to Multi-infeed HVDC System

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中国电机工程学报 2013年第10期33卷 I0001-I0026,25页

作者： liu zhenya QIN Xiaohui ZHAO Liang ZHAO Qingbo State Grid Corporation of China China Electric Power Research Institute

随着我国特高压交直流技术的广泛应用，多馈入直流集中落入受端负荷中心将是未来我国电网发展所面临的重要问题。为从电网结构上有效解决多馈入直流系统的问题，提出一种特高压直流分层接入交流电网的方式。研究分层接入方式直流多馈入... 详细信息

随着我国特高压交直流技术的广泛应用，多馈入直流集中落入受端负荷中心将是未来我国电网发展所面临的重要问题。为从电网结构上有效解决多馈入直流系统的问题，提出一种特高压直流分层接入交流电网的方式。研究分层接入方式直流多馈入短路比计算方法的适用性，从理论上对比特高压直流不同接入方式下多馈入直流电网的系统特性，证明特高压直流分层接入方式有助于提高多馈入直流系统的电压支撑能力，引导潮流在1000kV与500kV层级间合理分布。结合国家电网规划，仿真验证了特高压直流分层接入方式的优势。

关键词：多馈入直流输电系统特高压直流输电连接模式应用输电技术电网发展负荷中心电网结构

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中国特高压交流输电技术创新

电网技术 2013年第3期37卷 I0001-I0008页

作者：刘振亚国家电网公司北京市西城区100031

特高压交流输电是指1 000 kV及以上电压等级的交流输电,具有输送容量大、距离远、损耗低、占地省等显著优势,是一种资源节约型和环境友好型的先进输电技术。结合晋东南—南阳—荆门特高压交流试验示范工程,系统介绍了中国在发展特高压... 详细信息

特高压交流输电是指1 000 kV及以上电压等级的交流输电,具有输送容量大、距离远、损耗低、占地省等显著优势,是一种资源节约型和环境友好型的先进输电技术。结合晋东南—南阳—荆门特高压交流试验示范工程,系统介绍了中国在发展特高压交流输电方面的主要技术创新,重点包括电压控制、潜供电流控制、外绝缘配合、电磁环境控制、试验技术、成套设备、系统集成、调试运行等方面。推广应用这些新技术对于加快特高压电网发展有帮助作用。

关键词：特高压交流输电过电压与绝缘配合潜供电流电磁环境

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全球能源互联网跨国跨洲互联研究及展望

中国电机工程学报 2016年第19期36卷 5103-5110,5391页

作者：刘振亚全球能源互联网发展合作组织北京市西城区100031

构建全球能源互联网,实施"两个替代",是应对全球能源安全、环境污染、气候变化严峻挑战的治本之策。该文重点分析了亚洲、欧洲、非洲、美洲的清洁能源资源及分布特点,经济社会发展的电力需求及供需格局,初步论证了实施跨洲电网互联的可... 详细信息

构建全球能源互联网,实施"两个替代",是应对全球能源安全、环境污染、气候变化严峻挑战的治本之策。该文重点分析了亚洲、欧洲、非洲、美洲的清洁能源资源及分布特点,经济社会发展的电力需求及供需格局,初步论证了实施跨洲电网互联的可行性和必要性,研究提出了各洲洲内及跨洲电网互联的框架性设想,并展望全球电网互联构想。

关键词：全球能源互联网清洁能源资源电力供需电网互联