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Evaluating the accuracy of two satellite-based Quantitative Precipitation Estimation products and their application for meteorological drought monitoring over the Lake Victoria Basin,East Africa

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Geo-Spatial Information Science 2022年第3期25卷 500-518页

作者： Priyanko Das Zhenke Zhang hang ren Center of African Studies Nanjing UniversityNanjingChina and School of Geographic and Oceanographic SciencesNanjing UniversityNanjingChina Center of African Studies Nanjing UniversityNanjingChina and School of Geographic and Oceanographic SciencesNanjing University Nanjing China Institute of Population Studies Nanjing University of Posts and TelecommunicationsNanjingJiangsu provinceChina

This study evaluates the high-resolution satellite estimated long-term precipitation data for monitor-ing the drought condition over the Lake Victoria Basin(LVB)from 1984 to *** Precipitation Indices(SPI)were used to capture the short,medium and long-term meteorological drought conditions at multiple time scales(i.e.3,6,and 12).For these,the following two primaries Quantitative Precipitation Estimation(QPEs)products were employed-1)Climate Hazards group Infra-Red Precipitation with Station(CHIRPS),and 2)the Precipitation Estimation from Remotely Sensed Information using Artificial Neural Network-Climate Data Record(PERSIANN-CDR).This dataset was compared based on the observation data obtained from the Climate Research Unit(CRU)over the nine selected regions surrounding lake *** performance of these two QPEs products was evaluated using seven statistical *** findings of this study indicate that the CHIRPS and PERSIANN-CDR datasets could capture the behavior of drought magnitude based on the time scale of SPI-3,SPI-6,*** results indicate that 2012 and 2017 are significant severe drought years in the recent decade over ***,the CHIRPS datasets provide good agreement(Correlation Coefficient(CC)=0.65)with observation,whereas PERSIANN-CDR present satisfactory results(CC=0.54).In addition,Hurst(H)exponent was used to predict the future drought trend and found that the CHIRPS performed well to predict the degree of drought ***,this study considers the CHIRPS product for near-real-time drought monitoring and PERSIANN-CDR for historical drought ***,the outcome from the H values is greater than 0.5,which indicates the future drought trend would be decreased over *** results are useful for developing the strategies for drought hazards and water resource management in LVB.

关键词： CHIRPS CRU hurst exponent PERSIANN-CDR SPI

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The impact of political connections on firm pollution: New evidence based on heterogeneous environmental regulation

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Petroleum Science 2023年第1期20卷 636-647页

作者： Zong-Run Wang Hai-Qin Fu Xiao-hang ren School of Business Central South UniversityChangsha410083China

Increasing attention has been focused on the extent to which corporate political connections influence the growing pollution due to the rapid growth in the popularity of firm pollution in developing *** adopt a static threshold regression model to investigate the effects of heterogeneous environmental regulation on political connections and firm pollution based on the panel data from China’s A-share listed companies from 2012 to *** empirical results show a non-linear relationship between the degree of political connection of listed company executives and the level of firm *** the relationship between the two roughly presents a U-shaped relationship under the action of the marketincentive environmental regulation ***,it roughly presents an inverted N-shaped relationship under the action of the command-control environmental regulation ***,the group test results show that the existence of regional and ownership heterogeneity causes certain differences in the environmental behaviour of politically connected *** findings indicate that diverse environmental regulations are needed to promote sustainable green development and to further expand the theoretical and practical exploration of political connections on firm pollution.

关键词： Political connections Firm pollution Market-incentive environmental regulation Command-control environmental regulation Threshold model

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Size-dependent elastic properties of thin films: surface anisotropy and surface bonding

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Science China(Technological Sciences) 2014年第4期57卷 680-691页

作者： ZHOU XiaoYe ren hang HUANG BaoLing Zhang TongYi Department of Mechanical and Aerospace Engineering Hong Kong University of Science and Technology Clear Water Bay

Surface eigenstress and eigendisplacement models were used to investigate the surface stress, surface relaxation and surface elasticity of thin films with different surface orientations. Molecular dynamics simulations and first-principles calculations were conducted on face-centered cubic Au films with the focus on relaxation induced nonlinear initial deformation. The simu- lation results verify the theoretical predictions of the size dependency of surface energy density and surface stress, and the non- linear scaling law of the size-dependent Young＇s modulus of thin films. The mechanism of the size-dependent behaviors was further explored at the atomic bonding level with the charge density field. The Au atomic bonding at surfaces is enhanced compared to its interior counterpart and therefore the nominal Young＇s modulus of the Au thin films is larger when the film thickness is *** elasticity,

关键词： surface stress size-dependent Young's modulus Molecular dynamics simulations First-principle calculations

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Risk measurement of international oil and gas projects based on the Value at Risk method

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Petroleum Science 2019年第1期16卷 199-216页

作者： Cheng Cheng Zhen Wang Ming-Ming Liu Xiao-hang ren School of Management Science and Engineering Shanxi University of Finance and Economics Academy of Chinese Energy Strategy China University of Petroleum-Beijing School of Mathematical Sciences University of Southampton

International oil and gas projects feature high capital-intensity, high risks and contract diversity. Therefore, in order to help decision makers make more reasonable decisions under uncertainty, it is necessary to measure the risks of international oil and gas projects. For this purpose, this paper constructs a probabilistic model that is based on the traditional economic evaluation model, and introduces value at risk(VaR) which is a valuable risk measure tool in finance, and applies Va R to measure the risks of royalty contracts, production share contracts and service contracts of an international oil and gas project. Besides, this paper compares the influences of different risk factors on the net present value(NPV) of the project by using the simulation results. The results indicate:(1) risks have great impacts on the project's NPV, therefore, if risks are overlooked, the decision may be wrong.(2) A simulation method is applied to simulate the stochastic distribution of risk factors in the probabilistic model. Therefore, the probability is related to the project's NPV, overcoming the inherent limitation of the traditional economic evaluation method.(3) VaR is a straightforward risk measure tool, and can be applied to evaluate the risks of international oil and gas projects. It is helpful for decision making.

关键词： Risk measurement Value at risk International oil and gas projects Fiscal terms - Probabilistic model

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A method to calculate effective Hamiltonians in quantum information

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Chinese Physics B 2019年第11期28卷 114-119页

作者： Jun-hang ren Ming-Yong Ye Xiu-Min Lin Fujian Provincial Key Laboratory of Quantum Manipulation and New Energy Materials College of Physics and EnergyFujian Normal UniversityFuzhou 350117China Fujian Provincial Collaborative Innovation Center for Optoelectronic Semiconductors and Efficient Devices Xiamen 361005China

Effective Hamiltonian method is widely used in quantum information. We introduce a method to calculate effective Hamiltonians and give two examples in quantum information to demonstrate the method. We also give a relation between the effective Hamiltonian in the Shr?dinger picture and the corresponding effective Hamiltonian in the interaction ***, we present a relation between our effective Hamiltonian method and the James–Jerke method which is currently used by many authors to calculate effective Hamiltonians in quantum information science.

关键词： effective Hamiltonian method quantum information

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Multi-target vehicle detection and tracking based on video 32

Multi-target vehicle detection and tracking based on video

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第32届中国控制与决策会议

作者： Zhang Kun ren hang WEI Yongquan GONG Jun School of Information Science ＆ Engineering Northeastern University

ISBN: (纸本)9781728158549

In order to realize the vehicle tracking on the traffic road,a multi-target vehicle detecting and tracking method K-YOLOv3 based on video tracking is proposed in combination with *** algorithm is composed of vehicle detection,tracking,trajectory generation *** focus of this paper is vehicle detection and tracking.K-YOLOv3 is an improvement on YOLOv3,which is combined with KCF to detect and track the target vehicle at the same time,and then the vehicle trajectory set is established to form the vehicle *** results show that the detection accuracy of k-yolov3 algorithm is slightly higher than YOLOv3,while the detection speed is much faster than YOLOv3.

关键词： YOLOv3 KCF Object detection Object recognition

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Research on shape parameters of circular arc disc teeth for three-cone bit

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Petroleum 2018年第1期4卷 108-114页

作者： Qin Hu Huan Zhu hang ren School of Electromechanical Engineering Southwest Petroleum UniversitySichuan 610500China

Through the single row drilling experiment,this paper studied the regularity of the tooth shape parameter's influence to the disc teeth's rock-breaking effect,which provided some basis for the composite teeth type roller bit's combined experimental study and the structure design of the tooth *** experimental research is only for the circular arc disc teeth which is arranged on the composite teeth type roller bit's main *** experiments were designed using the method of orthogonal design and the results were analyzed by the fuzzy optimization *** results show that the disc tooth's drilling effect is the best when the tip diameter is 2 mm,taper angle is 30and the groove number is 8,and the disc tooth's drilling effect is the second best when the tip diameter is 3 mm,taper angle is 30and the groove number is *** above two combined ways of drilling effect's difference is very small(the difference of the degree of the membership is 0.003).

关键词： Tooth shape parameters Rock-breaking experiments Orthogonal design Fuzzy analysis

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Slater determinant and exact eigenstates of the two-dimensional Fermi–Hubbard model

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Chinese Physics B 2018年第7期27卷 264-267页

作者： Jun-hang ren Ming-Yong Ye Xiu-Min Lin Fujian Provincial Key Laboratory of Quantum Manipulation and New Energy Materials College of Physics and EnergyFujian Normal UniversityFuzhou 350117China Fufian Provincial Collaborative Innovation Center for Optoelectronic Semiconductors and Efficient Devices Xiamen 361005China

We consider the construction of exact eigenstates of the two-dimensional Fermi-Hubbard model defined on an L ×L lattice with a periodic condition. Based on the characteristics of Slater determinants, several methods are introduced to construct exact eigenstates of the model. The eigenstates constructed are independent of the on-site electron interaction and some of them can also represent exact eigenstates of the two-dimensional Bose-Hubbard model.

关键词： Hubbard model exact eigenstate Slater determinant

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Processes of small-scale tidal flat accretion and salt marsh changes on the plain coast of Jiangsu Province,China

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Acta Oceanologica Sinica 2017年第4期36卷 80-86页

作者： Zhang Yunfeng Zhang Zhenke HE Huachun CHEN Yingying JIANG Songliu ren hang Ministry of Education Key Laboratory for Coast and Island Development Nanjing University Nanjing 210023 China Key Laboratory of the Coastal Zone Exploitation and Protection Ministry of Land and Resource Nanjing 210024 China

Large-scaled reclamation modifies the coastal environment dramatically while accelerating the disappearance of salt marshes,which causes the degradation of the coastal ecosystem and the biodiversity *** this study,we explored the changes of tidal flat and salt marsh coverage in a small-scale tidal flat with an area of ~160 000 m^2 in the plain coast of Jiangsu Province,*** activities（e.g.,the construction of dikes） are a crucial contributor that benefits for the tidal flat accretions and the following changes of salt marsh *** in the front of the man-made ＂concave coastline＂,the study area is suitable for sediment accretion after the dike construction in the end of *** the basis of the annual tidal surface elevation survey from 2007 to 2012,the sedimentation rates in the human influenced tidal flat varied from a few centimeters per year to 23 cm/*** study area experienced a rapid accretion in the tidal flat and the expansion of the salt marsh,with the formation of a longshore bar,and a subsequent decline of the salt *** waves during the flooding tide brought much sediment from the adjacent tidal flat to the study area,which caused burial and degeneration of the salt *** vertical grain size changes within a 66 cm long core in the study area also demonstrated the above changes in the tidal *** study indicates that the responses of small-scale tidal flat changes to reclamation are significant,and the rational reclamation would benefit for the new salt marsh formation in front of the *** research about the evolution of small scale tidal flat as well as the spatial planning of the polder dike should be strengthened for the purpose to maintain a healthier coastal environment.

关键词： tidal flat salt marsh small-scale tidal flat response to reclamation plain coast of Jiangsu Province

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A Turn-On Fluorescent Probe for Highly Selective and Sensitive Detection of Palladium

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Chinese Journal of Chemistry 2016年第7期34卷 715-719页

作者： Junliang Zhou Jian Zhang hang ren Xiaochun Dong Xing Zheng Weili Zhao Institute of Pharmacy and Pharmacology University of South China Hengyang Hunan 421001 China School of Pharmacy Fudan University Shanghai 201203 China Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study Hengyang Hunan 421001 China

A novel turn-on fluorescent probe for the detection of palladium has been designed. The probe can selectively and sensitively detect palladium in solution, and the limit of detection was calculated to be 11.4 nmol·L-... 详细信息

关键词： fluorescent probe palladium living cell

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