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Issues influencing accuracy of hydrological modeling in a changing environment

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Water Science and Engineering 2021年第2期14卷 167-170页

作者： chong-yu Xu Department of Geosciences University of OsloOslo N-0316Norway

Hydrological models have undergone a long period of development and *** hydrological models of different temporal and spatial scales have been developed and applied in various fields of hydrological research and hydro-logical engineering,including hydrological forecasting,water resources estimation,river basin management,reservoir design and operation,and runoff simulation in ungauged *** have also been used in research on the impact of land use change and climate ***,hydrological models have taken on the most important problem-solving tasks in hydrology.

关键词： change. reservoir runoff

A PROCESS FOR SOLVING A FEW EXTREME EIGENPAIRS OF LARGE SPARSE POSITIVE DEFINITE GENERALIZED EIGENVALUE PROBLEM

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Journal of Computational Mathematics 2000年第4期18卷 387-402页

作者： chong-hua yu O.Axelsson Department of Mathematics Fudan UniversityShanghai 200433China Faculty of Mathematics and Informatics University of Nijmegen6525 ED NijmegenThe Netherlands

In this paper, an algorithm for computing some of the largest (smallest) generalized eigenvalues with corresponding eigenvectors of a sparse symmetric positive definite matrix pencil is presented. The algorithm uses an iteration function and inverse power iteration process to get the largest one first, then executes m - 1 Lanczos-like steps to get initial approximations of the next m - 1 ones, without computing any Ritz pair, for which a procedure combining Rayleigh quotient iteration with shifted inverse power iteration is used to obtain more accurate eigenvalues and eigenvectors. This algorithm keep the advantages of preserving sparsity of the original matrices as in Lanczos method and RQI and converges with a higher rate than the method described in [12] and provides a simple technique to compute initial approximate pairs which are guaranteed to converge to the wanted m largest eigenpairs using RQL. In addition, it avoids some of the disadvantages of Lanczos and RQI, for solving extreme eigenproblems. When symmetric positive definite lira ear systems must be solved in the process, an algebraic multilevel iteration method (AMLI) is: applied. The algorithm is fully parallelizable. [ABSTRACT FROM AUTHOR]

关键词： eigenvalue sparse problem

Solvothermal Synthesis, Crystal Structure and Characterization of a New Binuclear Copper(Ⅱ) Complex with K^(3):N^(1):N^(2):N^(4)-3-(Pyridin-2-yl)-1,2,4-triazole(HPT)

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Chinese Journal of Structural Chemistry 2021年第4期40卷 453-458,406页

作者： LI chong-yu yu Peng School of Chemistry and Materials Science Hunan Agricultural UniversityChangsha 410128China

A new binuclear copper(Ⅱ)complex[Cu_(2)(MBBA)_(2)(HPT)_(2)(H_(2)O)_(2)]·2H_(2)O(1)was synthesized with copper acetate,2-(4-methylbenzoyl)benzoic acid(MBBA)and 3-(pyridin-2-yl)-1H-1,2,4-triazole(HPT).It crystallizes in the monoclinic space group P21/c with a=14.722(2),b=8.8907(12),c=18.5565(18)A,β=116.820(7)o,V=2167.6(5)A^(3),Mr=483.96,Dc=1.483 g/cm^(3),Z=4,μ(Mo Ka)=1.049 mm^(-1),F(000)=981,the final GOOF=0.952,R=0.0586 and w R=*** whole molecule consists of two copper ions bridged by two HPT *** central Cu(Ⅱ)ion is coordinated by six atoms to give a distorted octahedral coordination *** structure of 1 has been determined by X-ray diffraction,IR spectrum and thermal stability *** solid-state fluorescence displays an obvious emission band at 412 nm upon excitation at 330 *** properties indicate that 1 exhibits antiferromagnetic properties.

关键词： binuclear copper(Ⅱ)complex thermal stability fluorescence magnetic property

Effect of H impurity on misfit dislocation in Ni-based single-crystal superalloy:molecular dynamic simulations

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Chinese Physics B 2012年第2期21卷 407-412页

作者： yu Tao Xie Hong-Xian Wang chong-yu Central Iron and Steel Research Institute Beijing 100081China Department of Physics Tsinghua UniversityBeijing 100084China School of Mechanical Engineering Hebei University of TechnologyTianjin 300132China

The effect of H impurity on the misfit dislocation in Ni-based single-crystal superalloy is investigated using the molecular dynamic simulation. It includes the site preferences of H impurity in single crystals Ni and Ni3Al, the interaction between H impurity and the misfit dislocation and the effect of H impurity on the moving misfit dislocation. The calculated energies and simulation results show that the misfit dislocation attracts H impurity which is located at the γ/γ′ interface and Ni3Al and H impurity on the glide plane can obstruct the glide of misfit dislocation, which is beneficial to improving the mechanical properties of Ni based superalloys.

关键词： molecular dynamic H impurity misfit dislocation Ni-based superalloy

Magnetization of Coupled Ultrathin Ferromagnetic Films

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Communications in Theoretical Physics 2002年第7期38卷 107-112页

作者： WANG Huai-yu ZHOU yun-Song WANG chong-yu Department of Physics Tsinghua University Beijing 100084 China Department of Physics Capital Normal University Beijing 100037 China Department of Physics Tsinghua University Beijing 100084 China

The magnetization of coupled ferromagnetic films is calculated by Green's function method. The coupling can either be ferromagnetic or antiferromagnetic. For the latter case, a concept of pseudo-spin is suggested to make calculation possible. A pseudo-spin is actually an anti-spin with its properties being analogue to other known anti particles such as a hole. The decreasing of Curie point as the coupling strength decays is computed. It is noted that with the same strength, antiferromagnetic coupling has higher Curie point than ferromagnetic coupling.

关键词： magnetization, pseudo-spin, coupled ferromagnetic films

Normal Ordering Expansion of Hermite Polynomials of Radial Coordinate Operator in Three-Dimensional Coordinate Space

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Communications in Theoretical Physics 2008年第4期49卷 866-870页

作者： SHAO yu-chong FAN Hong-Yi Department of Material Science and Engineering University of Science and Technology of China Hefei 230026 China Special Class for the Gifted Young University of Science and Technology of China Hefei 230026 China Department of Physics Shanghai Jiao Tong University Shanghai 200030 China

For Hermite polynomials of radial coordinate operator in three-dimensional coordinate space we derive its normal ordering expansion, which are new operator identities. This is done by virtue of the technique of integr... 详细信息

关键词： normal ordering expansion Hermite polynomial IWOP technique

Modelling Hydrological Consequences of Climate Change—Progress and Challenges

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Advances in Atmospheric Sciences 2005年第6期22卷 789-797页

作者： chong-yu XU Elin WIDEN Sven HALLDIN Department of Geosciences University of Oslo P. O. Box 1047 Blindern N-0316 Oslo Norway Department of Earth Sciences Uppsala University Villavagen 16 S-75236 Uppsala Sweden Nanjing Institute of Geography and Limnology Chinese Academy of Sciences

The simulation of hydrological consequences of climate change has received increasing attention from the hydrology and land-surface modelling communities. There have been many studies of climate-change effects on hydrology and water resources which usually consist of three steps：（1） use of general circulation models （GCMs） to provide future global climate scenarios under the effect of increasing greenhouse gases, （2） use of downscaling techniques （both nested regional climate models, RCMs, and statistical methods） for ＂downscaling＂ the GCM output to the scales compatible with hydrological models, and （3） use of hydrologic models to simulate the effects of climate change on hydrological regimes at various scales. Great progress has been achieved in all three steps during the past few years, however, large uncertainties still exist in every stage of such study. This paper first reviews the present achievements in this field and then discusses the challenges for future studies of the hydrological impacts of climate change.

关键词： climate change water-resources assessment water balance regional scale hydrological models review

Active Depths of Main Faults in the Ying-Qiong Basin Investigated by Multi-Scale Wavelet Decomposition of Bouguer Gravity Anomalies and Power Spectral Methods

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Journal of Ocean University of China 2022年第5期21卷 1174-1188页

作者： AN Long yu chong GONG Wei LI Deyong XING Junhui XU chong ZHANG Hao Key Laboratory of Submarine Geosciences and Prospecting Techniques Ministry of Educationand College of Marine GeosciencesOcean University of ChinaQingdao 266100China Laboratory for Marine Mineral Resources Pilot National Laboratory for Marine Science and Technology(Qingdao)Qingdao 266237China Shandong Zhengyuan Digital City Construction Co. Ltd.Yantai 264670China

The Ying-Qiong Basin is located on the northwestern margin of the South China Sea and at the junction of the South China Block and the Indochina *** is characterized by complex geological *** existing seismic data in the study area is sparse due to the lack of earthquake *** of the limited source energy and poor coverage of seismic data,the knowledge of deep structures in the area,including the spatial distribution of deep faults,is ***,satellite gravity data cover the entire study area and can reveal the spatial distribution of *** on the wavelet multi-scale decomposition method,the Bouguer gravity field in the Ying-Qiong Basin was decomposed and reconstructed to obtain the detailed images of the first-to sixth-order gravitational *** incorporating the known geological features,the gravitational field responses of the main faults in the Ying-Qiong Basin were identified in the detailed fields,and the power spectrum analysis yielded the depths of 1.4,8,15,26.5,and 39 km for the average burial depths of the bottom surfaces from the first-to fifth-order detailed fields,*** four main faults in the Yinggehai Basin all have a large active depth range:fault A(No.1)is between 5 and 39 km,fault B is between 26.5 and 39 km,and faults C and D are between 15 and 39 ***,the depth of active faults in the Qiongdongnan Basin is relatively shallow,mainly between 8 and 26.5 km.

关键词： Yinggehai Basin Qiongdongnan Basin active depth of fault Bouguer gravity anomaly wavelet multi-scale analysis power spectrum

Evaluation of mental fatigue based on multipsychophysiological parameters and kernel learning algorithms

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Chinese Science Bulletin 2008年第12期53卷 1835-1847页

作者： ZHANG chong ZHENG chongXun yu XiaoLin Key Laboratory of Biomedical Information Engineering of Education Ministry Xi'an Jiaotong University Xi'an 710049 China

Mental fatigue is an extremely sophisticated phenomenon, which is influenced by the environment, the state of health, vitality and the capability of recovery. A single parameter cannot fully describe it. In this paper, the effects of long time sustained low-workload visual display terminal (VDT) task on psychology are investigated by subjective self-reporting measures. Then power spectral indices of HRV, the P300 components based on visual oddball and wavelet packet parameters of EEG are combined to analyze the impacts of prolonged visual display terminal (VDT) activity on autonomic nervous system and cen-tral nervous system. Finally, wavelet packet parameters of EEG are extracted as the features of brain activity in different mental fatigue states. Kernel principal component analysis (KPCA) and support vector machine (SVM) are jointly applied to differentiate two states. The statistic results show that the level of both subjective sleepiness and fatigue increase significantly from pre-task to post-task, which indicate that the long time VDT task induces the mental fatigue to the subjects. The predominant activ-ity of autonomic nervous system of subjects turns to the sympathetic activity from parasympathetic activity after the task. The P300 components and wavelet packet parameters of EEG are strongly related with mental fatigue. Moreover, the joint KPCA-SVM method is able to effectively reduce the dimension-ality of the feature vectors, speed up the convergence in the training of SVM and achieve a high rec-ognition accuracy (87%) of mental fatigue state. Multipsychophysiological measures and KPCA-SVM method could be a promising tool for the evaluation of mental fatigue.

关键词：心理疲劳脑电图心率诊断方法