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Spatial correlations in time and frequency domains between chlorophyll-a concentration and environmental factors in the Bohai Sea

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Journal of Oceanology and Limnology 2024年第4期42卷 1143-1156页

作者： Wan xu Di MU Zhenteng YANG Dekui YUAN department of Mechanics Tianjin UniversityTianjin 300350China Engineering Research Center of Seawater Utilization of Ministry of Education School of Chemical Engineering and TechnologyHebei University of TechnologyTianjin 300130China State Key Laboratory of Hydraulic Engineering Simulation and Safety Tianjin UniversityTianjin 300072China

Based on the reconstructed MODIS data and ECMWF reanalysis data from 2003 to 2021,spatial correlations between chlorophyll a(Chl a)and sea surface temperature(SST),photosynthetically available radiation(PAR),aerosol optical thickness(AOT),and wind speed(WS)in the Bohai Sea were analyzed from the perspective of time domain and frequency *** indicate that the frequency domain analysis was more conducive to revealing the correlations between Chl a and environmental *** spatial pattern of time-domain correlations was similar to the isobaths of the Bohai Sea,which was positive in shallow waters and negative in deep waters for SST,PAR,and AOT,and was reversed for ***-domain correlations were obtained by performing Fourier Transform and were higher than correlations in time *** spatial distributions indicated that the effects of SST and PAR on Chl a were greater than AOT and WS in the Bohai ***,cross-spectrum analysis was applied to explore the response relationships.A depth-dependent pattern was shown in correlations and time lags,indicating that the influential mechanism of environmental factors on Chl-a concentration is related to seawater depth.

关键词： chlorophyll a(Chl a) frequency domain spatial correlation Bohai Sea

COMPATIBILITY OF PVC WITH POLYURETHANES OF DIFFERENT SOFT SEGMENTS

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Chinese Journal of Polymer Science 1988年第1期6卷 84-96页

作者：肖凤飞张贤胡世如马德柱罗筱烈徐懋 Institute of Chemistry Academia Sinica beijing department of applied Chemistry university of Science and technology of china. department of Applide Chernistry university of Science and technology of china university of Science and technology of china.

Blends of PVC and polyurethanes with four different soft segments of molecular weight 1000 were prepared and studied by dynamic mechanical and DSC techniques. It was found that the compatibility of PVC with segmented polyurethanes was related to the mixing of PVC molecules and the soft segments of the polyurethanes. Polyester based polyurethanes are more compatible with PVC than polyether based polyurethanes. Solution cast blends of PVC with PCL-polyurethane （1/2/1） exhibit single and narrow glass transition, while the blends with PPO-polyurethane （1/2/1） are completely incompatible. The compatibility was found to decrease with increasing hard segment content for all the polyurethanes used. The methods of blend preparation may change the compatibility of PVC/PU blends through their influence on the mixing or demixing of the hard and soft segments.

关键词： PVC blends PU segmented copolymers PVC/PU blends Compatibility DSC Dynamic mechanical measurement.

Classification of spin Hall effect in two-dimensional systems

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Frontiers of physics 2024年第3期19卷 103-114页

作者： Longjun Xiang Fuming xu Luyang Wang Jian Wang College of Physics and Optoelectronic Engineering Shenzhen UniversityShenzhen 518060China Quantum Science Center of Guangdong-Hongkong-Macao Greater Bay Area(Guangdong) Shenzhen 518045China department of Physics The University of Hong KongPokfulam RoadHong KongChina

Physical properties such as the conductivity are usually classified according to the symmetry of the underlying system using Neumann’s principle, which gives an upper bound for the number of independent components of the corresponding property tensor. However, for a given Hamiltonian, this global approach usually can not give a definite answer on whether a physical effect such as spin Hall effect (SHE) exists or not. It is found that the parity and types of spin-orbit interactions (SOIs) are good indicators that can further reduce the number of independent components of the spin Hall conductivity for a specific system. In terms of the parity as well as various Rashba-like and Dresselhaus-like SOIs, we propose a local approach to classify SHE in two-dimensional (2D) two-band models, where sufficient conditions for identifying the existence or absence of SHE in all 2D magnetic point groups are presented.

关键词： spin Hall effect symmetry two-dimensional system

Buckling behavior of pipes in oil and gas wells

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Progress in Natural Science:Materials International 2002年第2期 48-52页

作者： GAO Deli , LIU Fengwu and xu Bingye( department of Petroleum Engineering, university of Petroleum, beijing 100083, china State Key Laboratory of Automotive Safety and Energy, Tsinghua university, beijing 100084, china department of Engineering Mechanics, Tsinghua university, beijing 100084, china)

Based on the non-linear differential equations of buckled pipes, the buckling behavior of pipes in different wellbores has been analyzed. The relation between the deflection of buckled pipe and the loads on it has been given, and the critical loads for sinusoidal and helical buckling within different wellbores subjected to axial and torsional loads have been determined. Therefore, the profile of load increase during the post-buckling process and the bending moments in the buckled pipe can be determined. In addition, the effects of down-hole packer as fixed end on the helical buckling behavior of pipes have been investigated. These results can be applied to the related engineering design and construction.

关键词： sinusoidal buckling helical buckling post-buckling petroleum engineering.

Constructing Intranet for the Security of E-government

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Constructing Intranet for the Security of E-government

Numerical simulation of a buried hot crude oil pipeline during shutdown

The Second Conference on Fuzzy Information & Engineering

作者： JIAJUN LAI department of applied mathematics, Southwest Jiaotong university, Chengdu 610031, china YANG xu department of applied mathematics, Southwest Jiaotong university, Chengdu 610031, china

Nowadays, the security of E-govemment has been the principal problem in many countries. Furthermore the security of Intranet has become more and more important. In this a new scheme is brought forward, that is,a new strong way of authentication combined with the service of authorization has been put forward into the PKI (Public Key Infrastructures) system. It overcomes the shortcomings of single PKI system completely and ensures the security of Intranet well.

关键词： time token intranet PMI

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Petroleum Science 2010年第1期7卷 73-82页

作者： xu Cheng Yu Bo Zhang Zhengwei Zhang Jinjun Wei Jinjia Sun Shuyu beijing Key Laboratory of Urban Oil and Gas Distribution technology China University of Petroleum Beijing 102249China Zhejiang department Preparatory Team PetroChina West East Gas Pipeline Company Hangzhou Zhejiang 310000 China State Key Laboratory of Multiphase Flow in Power Engineering Xi＇an Jiaotong University Xi＇an Shaanxi 710049 China department of Mathematical Sciences Clemson University Clemson SC 29634-0975 USA

In this paper a mathematical model is built for a buried hot crude oil pipeline during shutdown, and an unstructured grid and polar coordinate grid are respectively applied to generating grids for the soil region and the three layers in the pipe （wax layer, pipe wall, and corrosion-inhibiting coating）. The governing equations are discretized using the finite volume method. The variations in temperatures of static oil and soil were investigated during pipeline shutdown in both summer and winter, in which some important parameters of the soil and crude oils of a Northeast pipeline are employed.

关键词： Moving boundary stagnation point equivalent thermal conductivity thermal influence region unstructured grid

Jackknife and Bootstrap Tests of the Composition Vector Trees

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Genomics, Proteomics & Bioinformatics 2010年第4期8卷 262-267页

作者： Guanghong Zuo1,2, Zhao xu1,3, Hongjie Yu1,4, and Bailin Hao1,5,6 1T-Life Research Center & department of Physics, Fudan university, Shanghai 200433, china 2Shanghai Institute of applied Physics, Chinese Acadamy of Sciences, Shanghai 201800, china 3applied Biosystems, Inc., beijing 100027, china 4Fudan-VARI Center for Genetic Epidemiology, Fudan university, Shanghai 200433, china 5Institute of Theoretical Physics, Chinese Acadamy of Sciences, beijing 100190, china 6Santa Fe Institute, Santa Fe, NM 87505, USA. T-Life Research Center & department of Physics Fudan University Shanghai 200433 China.

Composition vector trees （CVTrees） are inferred from whole-genome data by an alignment-free and parameter-free method. The agreement of these trees with the corresponding taxonomy provides an objective justification of the inferred phylogeny. In this work, we show the stability and self-consistency of CVTrees by performing bootstrap and jackknife re-sampling tests adapted to this alignment-free approach. Our ultimate goal is to advocate the viewpoint that time-consuming statistical re-sampling tests can be avoided at all in using this alignment-free approach. Agreement with taxonomy should be taken as a major criterion to estimate prokaryotic phylogenetic trees.

关键词： composition vector phylogeny topological distance bootstrap jackknife CVTree

X-ray spectra induced in highly charged 40Ar^q+ interacting with Au surface

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Science china(Physics,Mechanics & Astronomy) 2006年第2期49卷 203-212页

作者： ZHANG Xiao’an1,2, XIAO Guoqing1, YANG Zhihu1, CHEN Ximeng3, ZHAO Yongtao1, LI Fuli4, ZHANG Yinping1, CUI Ying3, ZHANG Hongqiang3, xu xu3, SHAO Jianxiong3 & ZHAN Wenlong11. Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, china 2. department of Physics, Xianyang Normal university, Xianyang 712000, china 3. department of Modern Physics, Lanzhou university, Lanzhou 730000, china 4. department of applied Physics, Xi’an Jiaotong university, Xi’an 710049, china Institute of Modern Physics Chinese Academy of Sciences Lanzhou China department of Physics Xianyang Normal University Xianyang China department of Modern Physics Lanzhou University Lanzhou China department of applied Physics Xi’an Jiaotong University Xi’an China

By use of optical spectrum technology, the spectra of X-ray induced by highly charged 40Arq+ ions interacting with Au surface have been studied. The results show that the argon Kα X-ray were emitted from the hollow atoms formed below the surface. There is a process of multi-electron exciting in neutralization of the Ar16+ion, with electronic con-figuration 1s2 in its ground state below the solid surface. The yield of the projectile Kα X-ray is related to its initial electronic configuration, and the yield of the target X-ray is related to the projectile kinetic energy.

关键词： highly charged ion hollow multi-electron excitation X- ray.

Prolonged Alzheimer-like Tau Hyperphosphorylation Induced by Simultaneous Inhibition of Phosphoinositol-3 Kinase and Protein Kinase C in N2a cells

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Acta Biochimica et Biophysica Sinica 2005年第5期37卷 349-354页

作者： Guo-Gang xu Yan-Qiu DENG Shi-Jie LIU Hong-Lian LI Jian-Zhi WANG department of Pothophysiology,Institute of Neuroscience,Tongji Medical College, Huazhong university of Science and technology, Wuhan 430030, china department of Pathophysiology Institute of Neuroscience Tongji Medical College Huazhong University of Science and TechnologyWuhan 430030 China

Co-injection of wortmannin（inhibitor of phosphatidylinositol-3 kinase,PI3K）and GF109203X（inhibitor of protein kinase C,PKC）into the rat brain was found to induce spatial memory deficiency andenhance tau hyperphosphorylation in the hippocampus of rat *** establish a cell model with durativeAlzheimer-like tau hyperphosphorylation in this study,we treated N2a neuroblastoma cells with wortmanninand GF109203X separately and simultaneously,and measured the glycogen synthase kinase 3（GSK-3）activity by γ-（32）P-labeling and the level of tau phosphorylation by Western *** was found that theapplication of wortmannin alone only transitorily increased the activity of GSK-3（about 1 h）and the level oftau hyperphosphorylation at Ser396/Ser404 and Ser199/Ser202 sites（no longer than 3 h）;however,a prolongedand intense activation of GSK-3（over 12 h）and enhanced tan hyperphosphorylation（about 24 h）wereobserved when these two selective kinase inhibitors were applied *** conclude that the simultaneousinhibition of PI3K and PKC can induce GSK-3 overactivation,and further strengthen and prolong the Alzheimer-like tau hyperphosphorylation in N2a cells,suggesting the establishment of a cell model with early pathologicalevents of Alzheimer’s disease.

关键词： Alzheimer’s disease(AD) tau glycogen synthase kinase 3(GSK-3) protein kinase C(PKC) phosphatidylinositol-3 kinase(PI3K) N2a cells