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Theory and test of underground explosions:Coupling rule between cratering and ground shock

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Underground Space 2024年第4期17卷 146-160页

作者： Wei Guo Jie Li Benjun Shi Tianhan xu Xiaohui xu gan Li Jie Shi State Key Laboratory of Disaster Prevention and Mitigation of Explosion and Impact Army Engineering University of PLANanjing 210007China

Calculating the parameters of the ground shock induced by an underground explosion is a complex energy coupling *** is difficult to establish a unified ground shock coupling law from limited test *** paper summarizes the research results obtained at home and abroad and systematically analyzes the coupling mechanism of craters formed by an underground explosion and the ground *** differences between the concepts of"closed-explosion critical depth"and"equivalent closed-explosion critical depth"are clearly *** spreading of the ground shock energy is attributed to the explosive expansion of the air cavity,revealing a linear relationship between the volume of the cavity region(or the volume of the crack region)and the ground shock energy associated with the underground *** proportionality factor is related to the mechanical properties of the medium and is independent of the magnitude of the explosion *** on this,a theoretical calculation formula and conversion method for the ground shock coupling coefficient were *** tests were conducted in clay and Plexiglass under varying burial *** test results were consistent with the theoretically calculated *** study provides a theoretical basis for the design of explosion-resistant structures in underground engineering.

关键词： Underground explosion Ground shock coupling Coupling coefficient Equivalent closed explosion Experimental study

Experimental Realization of a Magnetically Tunable Cavity in a Gyromagnetic Photonic Crystal

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Chinese Physics Letters 2012年第7期29卷 122-125页

作者： lian Jin FU Jin-Xin gan Lin LI Zhi-Yuan Laboratory of Optical Physics National Laboratory for Condensed Matter PhysicsInstitute of PhysicsChinese Academy of SciencesP.O.Box 603Beijing 100190

We theoretically and experimentally study the cavity modes in a gyromagnetic photonic crystal (GPC).Because the permeability of gyromagnetic material relies on the dc magnetic field exerted upon it,the band gap of the GPC is supposed to be *** on this,it is expected that the cavity mode in the GPC is also tunable under the variation of dc magnetic *** relation between the frequency of the cavity mode and exerted dc magnetic field is theoretically ***,we measure the frequency variation of the cavity mode in the GPC and demonstrate the tunable property of GPC cavity.

关键词： Crystal cavity mode

Characterization of the Topological Features of Catalytic Sites in Protein Coevolution Networks

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Chinese Physics Letters 2020年第6期37卷 127-131页

作者： Xiu-lian xu Jin-xuan Shi School of Physics Science and Technology Yangzhou UniversityYangzhou 225002China

The knowledge of sequence and structural properties of residues in the catalytic sites of enzymes is important for understanding the physiochemical basis of enzymatic *** reveal new features of the catalytic sites by analyzing the coevolutionary behavior of amino acid *** performing direct coupling analysis of the sequences of homologous proteins,we construct the coevolution networks at the residue *** on the analysis of the topological features of the coevolution networks for a dataset including 20 enzymes,we show that there is significant correlation between the catalytic sites and topological features of protein coevolution *** at the catalytic center often correspond to the nodes with high values of centralities in the networks as characterized by the degree,betweenness,closeness,and Laplacian *** results of this work provide a possible way to extract key coevolutionary information from the sequences of enzymes,which is useful in the prediction of catalytic sites of enzymes.

关键词： evolution networks catalytic

Fabrication of 6FDA-HFBAPP Polyimide Asymmetric Hollow Fiber Membranes and Their CO2/CH4 Separation Properties

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Chinese Journal of Polymer Science 2019年第8期37卷 815-826页

作者： Cong-Jun gan Xiao-Chen xu xue-Wei Jiang Feng gan Jie Dong Xin Zhao Qing-Hua Zhang State Key Laboratory for Modification of Chemical Fibers and Polymer Materials College of Materials Science and Engineering Donghua University

In this work, poly(amide acid) solution, the precursor of polyimide, was synthesized by the reaction of 4,4′-(hexafluoroisopropylidene)diphthalicanhydride and 2,2-bis[4-(4-aminophenoxy)phenyl]-hexafluoropropanane in the solvent of N-methyl-2-pyrrolidone(NMP) and tetrahydrofuran(THF). Then, hollow fiber membranes for high flux gas separation were prepared by dry-jet wet spinning using the precursor solution of poly(amide acid) as the spinning dope and a subsequent imidization process. Silicone rubber was further coated outside the obtained hollow fiber membranes to repair the defects on the denser layer. The effects of internal, external coagulation bath ratios with air gap, and coating solution concentrations on the morphologies, structures, and separation performance of the membranes were studied. Results showed that the sponge-like support layer was formed when the content of NMP was increased from 50% to 90% in the internal coagulation bath. The outer surface of the membrane became denser when the water content in the external coagulation bath increased from 40% to 100%, and the separation coefficient of CO2/CH4 increased by 2 times. This value could reach up to 1.4 when the air gap was 6 cm. With tuning the mass fraction of silicone rubber as 5%, hollow fiber composite membranes with uniform coating layer and an improved separation coefficient of 5.4 could be obtained.

关键词： Polyimide Gas separation Preparation conditions Membrane structure Permeability

Primary Exploration of Reliability Evaluation of Computer Live Forensics Model on Physical Memory Analysis

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Journal of Harbin Institute of Technology(New Series) 2014年第4期21卷 121-128页

作者： lian-Hai Wang Qiu-liang xu School of Computer Science and Technology Shandong University Shandong Provincial Key Laboratory of Computer Network Shandong Computer Science Center( National Supercomputer Center in Jinan)

The integrity and fidelity of digital evidence are very important in live forensics. Previous studies have focused the uncertainty of live forensics based on different memory snapshots. However,this kind of method is not effective in practice. In fact,memory images are usually acquired by using forensics tools instead of using snapshots. Therefore,the integrity and fidelity of live evidence should be evaluated during the acquisition process. In this paper,we study the problem in a novel viewpoint. Firstly,several definitions about memory acquisition measure error are introduced to describe the trusty. Then,we analyze the experimental error and propose some suggestions on how to reduce it. A novel method is also developed to calculate the system error in detail. The results of a case study on Windows 7 and VMware virtual machine show that the experimental error has good accuracy and precision,which demonstrate the efficacy of the proposed reducing methods. The system error is also evaluated,that is,it accounts for the whole error from 30% to 50%.

关键词： digital investigation live forensics volatile memory acquisition trusted probability

Rational and semi-rational engineering of cytochrome P450s for biotechnological applications

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Synthetic and Systems Biotechnology 2018年第4期3卷 283-290页

作者： lian-Hua xu Yi-Ling Du College of Life Sciences Zhejiang Sci-Tech UniversityHangzhou 310018China Institute of Pharmaceutical Biotechnology The First Affiliated HospitalZhejiang University School of MedicineHangzhou 310058China

The cytochrome P450 enzymes are ubiquitous heme-thiolate proteins performing regioselective and stereoselective oxygenation reactions in cellular *** to their broad substrate scope and catalytic versatility,P450 enzymes are also attractive candidates for many industrial and biopharmaceutical *** particular uses,enzyme properties of P450s can be further optimized through directed evolution,rational,and semi-rational engineering approaches,all of which introduce mutations within the P450 *** this review,we describe the recent applications of these P450 engineering approaches and highlight the key regions and residues that have been identified using such ***“hotspots”lie within critical functional areas of the P450 structure,including the active site,the substrate access channel,and the redox partner interaction interface.

关键词： Cytochrome P450 Protein engineering Rational design Crystal structure

CURVATURE COMPUTATIONS OF 2-MANIFOLDS IN IR^k

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Journal of Computational Mathematics 2003年第5期21卷 681-688页

作者： Guo-lian~xu ChandrajitL.Bajaj AcademyofMathematicsandSystemSciences ChineseAcademyofSciencesBeijing100080China DepartmentofComputerScience UniversityofTexasAustinTX78712

In this paper, we provide simple and explicit formulas for computing Riemannian curvatures, mean curvature vectors, principal curvatures and principal directions for a 2-dimensional Riemannian manifold embedded in IRk... 详细信息

关键词： Riemannian curvature Mean curvature vector Principal curvatures Principal directions.

Optical Absorption Spectra of Cr^(3+) and Cr^(4+) in Sr_(3)Ga_(2)Ge_(4)O_(14) Garnet Crystals

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Chinese Physics Letters 1995年第7期12卷 424-427页

作者： xu Jun DENG Peizhen ZHANG Qiang gan Fuxi Shanghai Institute of Optics and Fine Mechanics Academia SinicaShanghai 201800

Single crystals of Sr_(3)Ga_(2)Ge_(4)O_(14):Cr are grown by the Czochralski *** polarized optical absorption spectra of Cr in visible and near-infrared wavelength are presented and *** is suggested that Cr enters the ... 详细信息

关键词： method visible

Seasonal variability of the wind-generated near-inertial energy flux in the South China Sea

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Acta Oceanologica Sinica 2019年第4期38卷 136-145页

作者： Baonan Sun Zhan lian Yeli Yuan Haiyang xu College of Oceanic and Atmospheric Sciences Ocean University of China Key Laboratory of Marine Science and Numerical Modeling First Institute of OceanographyMinistry of Natural Resources Laboratory for Regional Oceanography and Numerical Modeling Pilot National Laboratory for Marine Science and Technology (Qingdao)

After validated by the in-situ observation, the slab model is used to study the wind-generated near-inertial energy flux(NIEF) in the South China Sea(SCS) based on satellite-observed wind data, and its dependence on calculation methods and threshold criteria of the mixed layer depth(MLD) is investigated. Results illustrate that the total amount of NIEF in the SCS could be doubled if different threshold criteria of MLD are adopted. The NIEF calculated by the iteration and spectral solutions can lead to a discrepancy of 2.5 GW(1 GW=1×109 W). Results also indicate that the NIEF exhibits spatial and temporal variations, which are significant in the boreal autumn,and in the southern part of the SCS. Typhoons are an important generator of NIEF in the SCS, which could account for approximately 30% of the annual mean NIEF. In addition, deepening of the MLD due to strong winds could lead to a decrease of NIEF by approximately by 10%. We re-estimate the annual mean NIEF in the SCS,which is(10±4) GW and much larger than those reported in previous studies.

关键词： near-inertial energy flux mixed layer depth South China Sea typhoon