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Interference coordination in full-duplex HetNet with large-scale antenna arrays

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Frontiers of Information Technology & Electronic Engineering 2017年第6期18卷 830-840页

作者： zhao-yang zhang Wei LYU College of Information Science and Electronic Engineering Zhejiang UniversityHangzhou 310027China

Massive multiple-input multiple-output (MIMO), small cell, and full-duplex are promising techniques for future 5G communication systems, where interference has become the most challenging issue to be *** this paper, we provide an interference coordination framework for a two-tier heterogeneous network(HetNet)that consists of a massive-MIMO enabled macro-cell base station (MBS) and a number of full-duplex small-cell base stations (SBSs). To suppress the interferences and maximize the throughput, the full-duplex mode of each SBS at the wireless backhaul link (i.e., in-band or out-of-band), which has a different impact on the interference pattern, should be carefully selected. To address this problem, we propose two centralized algorithms, a genetic algorithm (GEA)and a greedy algorithm (GRA). To sufficiently reduce the computational overhead of the MBS, a distributed graph coloring algorithm (DGCA) based on price is further proposed. Numerical results demonstrate that the proposed algorithms significantly improve the system throughput.

关键词： Massive MIMO Full-duplex Small cell Wireless backhaul Distributed algorithm

The three-dimension model for the rock-breaking mechanism of disc cutter andanalysis of rock-breaking forces

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Acta Mechanica Sinica 2012年第3期28卷 675-682页

作者： zhao-Huang zhang Fei Sun School of Energy Power and Mechanical EngineeringNorth China Electric Power University102206 BeijingChina School of Foreign Languages North China Electric Power University102206 BeijingChina

To study the rock deformation with three- dimensional model under rolling forces of disc cutter, by car- rying out the circular-grooving test with disc cutter rolling around on the rock, the rock mechanical behavior under rolling disc cutter is studied, the mechanical model of disc cutter rolling around the groove is established, and the the- ory of single-point and double-angle variables is proposed. Based on this theory, the physics equations and geometric equations of rock mechanical behavior under disc cutters of tunnel boring machine （TBM） are studied, and then the bal- ance equations of interactive forces between disc cutter and rock are established. Accordingly, formulas about normal force, rolling force and side force of a disc cutter are de- rived, and their validity is studied by tests. Therefore, a new method and theory is proposed to study rock- breaking mech- anism of disc cutters.

关键词： Full face rock tunnel boring machine (TBM) Disc cutte Three-dimension model

A Game Theoretic Approach for a Minimal Secure Dominating Set

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IEEE/CAA Journal of Automatica Sinica 2023年第12期10卷 2258-2268页

作者： Xiuyang Chen Changbing Tang zhao zhang the College of Mathematics and System Science Xinjiang UniversityUrumqi 830000China IEEE the College of Physics and Electronic Information Engineering Zhejiang Normal UniversityJinhua 321004China the School of Mathematical Sciences Zhejiang Normal UniversityJinhua 321004China

The secure dominating set(SDS),a variant of the dominating set,is an important combinatorial structure used in wireless *** this paper,we apply algorithmic game theory to study the minimum secure dominating set(Min SDS) problem in a multi-agent *** design a game framework for SDS and show that every Nash equilibrium(NE) is a minimal SDS,which is also a Pareto-optimal *** prove that the proposed game is an exact potential game,and thus NE exists,and design a polynomial-time distributed local algorithm which converges to an NE in O(n) rounds of *** experiments are done to test the performance of our algorithm,and some interesting phenomena are witnessed.

关键词： Algorithmic game theory multi-agent systems po-tential game secure dominating set

Mechanical Fault Diagnosis Based on Band-phase-randomized Surrogate Data and Multifractal

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Chinese Journal of Mechanical Engineering 2011年第5期24卷 885-890页

作者： zhang Shuqing zhao Yuchun zhang Liguo JIN Mei School of Electrical Engineering Yanshan University Qinhuangdao 066004 China

The vibration signals of machinery with various faults often show clear nonlinear ***,fractal dimension analysis as the common useful method for nonlinear signal analysis,is a kind of single fractal form,which only reflects the overall irregularity of signals,but cannot describe its local scaling *** comprehensive revealing of internal properties,a combinatorial method based on band-phase-randomized（BPR） surrogate data and multifractal is *** surrogate data method is effective to eliminate nonlinearity in specified frequency band for a fault signal,which can be utilized to detect nonlinear degree in whole fault signal by nonlinear titration method,and the overall nonlinear distribution of fault signal is displayed in nonlinear characteristic curve that can be used to analyze the fault signal *** multifractal theory as a quantitative analysis method is used to describe geometrical characteristics and local scaling properties,and asymmetry coefficient of multifractal spectrum and multifractal entropy for fault signals are extracted as new criterions to diagnose machinery *** typical faults include rotor misalignment,transversal crack,and static-dynamic rubbing fault are analyzed,and the results indicate that those faults can be distinguished by the proposed method effectively,which provides a qualitative and quantitative analysis way in the field of machinery fault diagnosis.

关键词： fault diagnosis band-phase-randomized surrogate data nonlinear titration multifractal

Bondage number of strong product of two paths

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Frontiers of Mathematics in China 2015年第2期10卷 435-460页

作者： Weisheng zhao Heping zhang School of Mathematics and Statistics Lanzhou University Lanzhou 730000 China

The bondage number b（G） of a graph G is the cardinality of a minimum set of edges whose removal from G results in a graph with a domination number greater than that of G. In this paper, we obtain the exact value of the bondage number of the strong product of two paths. That is, for any two positive integers ra ≥ 2 and n ≥ 2, b（Pm × Pn） = 7 - r（m） - r（n） if （r（m）,r（n）） = （1, 1） or （3,3）, 6 - r（m） - r（n） otherwise, where r（t） is a function of positive integer t, defined as r（t） = 1 if t ≡ 1 （mod 3）, r（t） = 2 if t ≡2 （mod 3）, and r（t） = 3 if t ≡0 （mod 3）.

关键词： Bondage number strong product path

Spatial and Temporal Changes in Vapor Pressure Deficit and Their Impacts on Crop Yields in China during 1980–2008

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Journal of Meteorological Research 2017年第4期31卷 800-808页

作者： Shuai zhang Fulu TAO zhao zhang Key Laboratory of Land Surface Pattern and Simulation Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of Sciences State Key Laboratory of Earth Surface Processes and Resource Ecology Beijing Normal University

Vapor pressure deficit（VPD） is a widely used measure of atmospheric water demand. It is closely related to crop evapotranspiration and consequently has major impacts on crop growth and yields. Most previous studies have focused on the impacts of temperature, precipitation, and solar radiation on crop yields, but the impact of VPD is poorly understood. Here, we investigated the spatial and temporal changes in VPD and their impacts on yields of major crops in China from 1980 to 2008. The results showed that VPD during the growing period of rice, maize, and soybean increased by more than 0.10kPa（10 yr）^–1 in northeastern and southeastern China, although it increased the least during the wheat growing period. Increases in VPD had different impacts on yields for different crops and in different regions. Crop yields generally decreased due to increased VPD, except for wheat in southeastern China. Maize yield was sensitive to VPD in more counties than other crops. Soybean was the most sensitive and rice was the least sensitive to VPD among the major crops. In the past three decades, due to the rising trend in VPD, wheat, maize, and soybean yields declined by more than 10.0% in parts of northeastern China and the North China Plain, while rice yields were little affected. For China as a whole, the trend in VPD during 1980–2008 increased rice yields by 1.32%,but reduced wheat, maize, and soybean yields by 6.02%, 3.19%, and 7.07%, respectively. Maize and soybean in the arid and semi-arid regions in northern China were more sensitive to the increase in VPD. These findings highlight that climate change can affect crop growth and yield through increasing VPD, and water-saving technologies and agronomic management need to be strongly encouraged to adapt to ongoing climate change.

关键词： agriculture climate change vapor pressure deficit evapotranspiration water stress

Performance of Temperature-Related Weather Index for Agricultural Insurance of Three Main Crops in China

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International Journal of Disaster Risk Science 2017年第1期8卷 78-90页

作者： Jing zhang zhao zhang Fulu Tao State Key Laboratory of Earth Surface Processes and Resource Ecology/Key Laboratory of Environmental Change and Natural Hazards Academy of Disaster Reduction and Emergency Management Faculty of Geographical ScienceBeijing Normal University Institute of Geographical Sciences and Natural Resources Research Chinese Academy of Sciences

In this study, two categories of weather index—absolute index and relative index—for chilling injury and heat damage of three main crops in China were assessed to identify insurable counties. First, correlations between selected weather indices and yield losses were examined for each county. If a correlation was significant, the county was categorized as ‘‘insurable'' for the corresponding hazard or index. Second, the spatial distribution of insurable counties was characterized and finally, their correlation coefficients were analyzed at various spatial *** results show that the spatial patterns of insurable areas varied by categories of weather indices, crops, and ***, the weather indices based on relative threshold of temperature were more suitable for chilling injury in most regions, whereas the indices based on absolute threshold were more suitable for heat damage. The findings could help the Chinese government and insurance companies to design effective insurance products.

关键词： Chilling injury China Crop insurance Heat damage Weather index

Readily Prepared and Tunable Ionic Organocatalysts for Ring-opening Polymerization of Lactones

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Chinese Journal of Polymer Science 2019年第12期37卷 1205-1214,I0005页

作者： Zhuo-Lun Jiang Jun-Peng zhao Guang-zhao zhang Faculty of Materials Science and Engineering South China University of Technology

Highly potent ionic organocatalyst is developed for room-temperature controlled ring-opening polymerization(ROP)of lactones,includingδ-valerolactone,ε-caprolactone,andδ-*** catalysts are prepared by simply mixing tetra-n-butyl ammonium hydroxide and a(thio)urea at elevated temperature under vacuum,and used in cooperation with an alcoholic *** performance of the catalyst is readily adjusted and optimized through variation of the(thio)urea precursor,catalyst composition,and reaction ***-derived catalysts are generally superior to thiourea-derived *** with proper N-substituents,the catalyst affords both high polymerization efficiency and high selectivity for monomer enchainment over macromolecular transesterification,even at high monomer conversion and/or substantially extended reaction *** addition to acidity,structural symmetry of the urea also proves decisive for the catalytic activity,which enables a catalyst-assisted proton transfer process for the ring-opening of lactone and thus provides a novel mechanistic insight for ROP catalyzed by hydrogen-bonding type bifunctional ionic organocatalysts.

关键词： Organocatalytic polymerization Ring-opening polymerization Polyester

Optical Properties of Neodymium Substituted Bismuth Titanate Thin Film Grown by Metal-organic Solution Deposition

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Journal of Materials Science & Technology 2010年第11期26卷 977-980页

作者： Yuehua Wang Xinyin zhao Na zhao Min zhang Department of Physics China University of Mining and Technology Xuzhou 221116 China

Well-crystallized Bi2Nd2Ti3O12 （BNT） thin film with good surface morphology was prepared by metal-organic solution deposition （MOD）.The waveguide property was investigated by using a Metricon 2010 prism *** nonlinear optical properties of the film were measured by Z-scan technique at a wavelength of 532 nm with pulse durations of 35 ps.A large positive nonlinear refractive index,nonlinear refractive coefficient and two-photon absorption coefficient were determined to be 2.7×10-7 esu,5.29×10-7 esu and 2.41×10-7 m/W,*** origin of optical nonlinearity of BNT thin film was *** results suggested that the the BNT thin film may be a kind of new multifunctional materials.

关键词： Bi2Nd2Ti3O12 Optical property Metal-organic solution deposition