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Ballistic performances of the hourglass lattice sandwich structures under high-velocity fragments

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Defence Technology（防务技术） 2024年第1期31卷 312-325页

作者： He-xiang Wu Jia Qu lin-zhi Wu Key Laboratory of Advanced Ship Materials and Mechanics College of Aerospace and Civil EngineeringHarbin Engineering UniversityHarbin150001China School of Civil Engineering Northeast Forestry UniversityHarbin150040China

In this paper,the numerical simulation method is used to study the ballistic performances of hourglass lattice sandwich structures with the same mass under the vertical incidence of *** is paid to elucidating the influences of rod cross-section dimensions,structure height,structure layer,and rod inclination angle on the deformation mode,ballistic performances,and ability to change the ballistic direction of *** results show that the ballistic performances of hourglass lattice sandwich structures are mainly affected by their structural *** this respect,structural parameters optimization of the hourglass lattice sandwich structures enable one to effectively improve their ballistic limit velocity and,consequently,ballistic performances.

关键词： Hourglass lattice sandwich structures Ballistic performances high-velocity Finite element analysis

Preparation of a novel composite electrode based on N-doped TiO_2-coated Na Y zeolite membrane and its photoelectrocatalytic performance

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Chinese Chemical Letters 2016年第3期27卷 467-470页

作者： zhi-lin Cheng Shuai Han College of Chemistry and Chemical Engineering Yangzhou University

For the first time the preparation of the N-doped TiO2-coated NaY zeolite membrane（N-doped TiO2/NaY zeolite membrane） as an electrode material for photoelectrocatalysis has been achieved and *** XRD, SEM, UV–vis and XPS techniques were used to characterize the structure of the N-doped TiO2/NaY zeolite membrane. The results verified that the surface of the N-doped TiO2/NaY zeolite membrane was coated by TiO2 nanoparticles of ca. 20 nm size and exhibited a distinct red-shift in the UV–vis spectra compared to N-doped TiO2. The photoelectrocatalysis performance of the N-doped TiO2/NaY zeolite membrane electrode was evaluated by phenol degradation. The results revealed it is a promising novel electrode material for application of photoelectrocatalysis in the removal of organic contaminants in waste water.

关键词： Zeolite membrane Nanocomposites Photoelectrocatalysis NaY TiO2

Preparation of nano-CuO-loaded halloysite nanotubes with high catalytic activity for selective oxidation of cyclohexene

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Chinese Chemical Letters 2016年第1期27卷 81-84页

作者： zhi-lin Cheng Wei Sun College of Chemistry and Chemical Engineering Yangzhou University

A facile preparation method of nano-CuO catalysts, assembled in the hollow nanotube of halloysite nanotubes（HNTs）, was developed. The characterizations of XRD, TEM, SEM, BET, XRF and FT-IR were used to analyze the structure and properties of the nano-CuO/HNT loaded catalyst. The XRD patterns indicated that the CuO nanoparticles on HNTs were monoclinic phase. The TEM-EDX and SEM images confirmed that most of nano-CuO catalysts with the crystal size of ca. 20 nm were assembled into the hollow nanotube of HNTs. The catalytic performance of the nano-CuO/HNT catalysts was evaluated by using selective oxidation of cyclohexene. The reaction temperature and recycling times were investigated. The results reveal that the nano-CuO/HNT catalysts exhibit an excellent catalytic oxidation performance for selective oxidation of cyclohexene to 2-cyclohexene-1-one.

关键词： Cyclohexene CuO Selective oxidation HNTs

Full-Range Compressive Stress-Strain Curves for Cold-Formed 304 Stainless Steel Circular Hollow Sections After Exposure to Vacuum Brazing

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Acta Mechanica Solida Sinica 2018年第5期31卷 557-572页

作者： Bin Hu Yang Jin lin-zhi Wui Center for Composite Materials Harbin Institute of Technology Harbin 150001 China Key Laboratory of Advanced Ship Materials and Mechanics College of Aerospace and Civil Engineering Harbin Engineering University Harbin 150001 China

With the rapid development of microscale cellular structures, the small-diameter cold-formed welded stainless steel tubes have recently been used for creating the metallic lat- tice topologies with high mechanical properties. In this paper, to obtain the accurate material properties of the circular hollow section （CHS） under pure compression, a series of concentric compression tests are conducted on the millimeter-scale cold-formed 304 stainless steel circu- lar tubular stub columns after exposure to a vacuum brazing process. The tests cover a total of 18 small-diameter stub tubes with measured thickness-to-diameter ratios （t/D） from 0.023 to 0.201. A generalized three-stage nominal stress-strain model is developed for describing the compressive behavior of the post-brazing CHSs over the full strain range. This mechanical model is especially applicable to computer code implementation. Hence, an interactive computer pro- gram is developed to simultaneously optimize three strain hardening exponents （n1, n2, n3） in the expression of the model to produce the stress-strain curve capable of accurately replicating the test data. To further reduce the number of the model and material parameters on which this model depends, this paper also develops five expressions for determining the 2.5% proof stress （ap2）, n2, the ultimate compressive strength （σp3）, n3, and the ultimate plastic strain （p3%） for given experimental values of three basic material parameters （E0, σ0.01, σ0.2）. These expressions are validated to he effective for the CHSs with t/D 〉_ 0.027. The analytically predicted full-range stress-strain curves have generally shown close agreement with the ones obtained experimentally.

关键词： Compression test Stress-strain curve Cold-formed 304 Stainless steel Circular hollow section (CHS) Post-brazing

Abundance and Community Composition of Ammonia-Oxidizers in Paddy Soil at Different Nitrogen Fertilizer Rates

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Journal of Integrative Agriculture 2014年第4期13卷 870-880页

作者： SONG Ya-na lin zhi-min Institute of Biological Technology Fujian Academy of Agricultural Sciences

Ammonia oxidation, the first and rate-limiting step of nitrification, is carried out by both ammonia-oxidizing bacteria （AOB） and ammonia-oxidizing archaea （AOA）. However, the relative importance of AOB and AOA to nitrification in terrestrial ecosystems is not well understood. The aim of this study was to investigate the effect of the nitrogen input amount on abundance and community composition of AOB and AOA in red paddy soil. Soil samples of 10-20 cm （root layer soil） and 0-5 cm （surface soil） depths were taken from a red paddy. Rice in the paddy was fertilized with different rates of N as urea of N1 （75 kg N ha＂ yr-1）, N2 （150 kg N ha~ yrl）, N3 （225 kg N ha1 yrl） and CK （without fertilizers） in 2009, 2010 and 2011. Abundance and community composition of ammonia oxidizers was analyzed by real-time PCR and denaturing gradient gel electrophoresis （DGGE） based on amoA （the unit A of ammonia monooxygenase） gene. Archaeal amoA copies in N3 and N2 were significantly （P〈0.05） higher than those in CK and N1 in root layer soil or in surface soil under tillering and heading stages of rice, while the enhancement in bacterial amoA gene copies with increasing of N fertilizer rates only took on in root layer soil. N availability and soil NO3--N content increased but soil NH4＋-N content didn＇t change with increasing of N fertilizer rates. Otherwise, the copy numbers of archaeal amoA gene were higher （P〈0.05） than those of bacterial amoA gene in root lary soil or in surface soil. Redundancy discriminate analysis based on DGGE bands showed that there were no obvious differs in composition of AOA or AOB communities in the field among different N fertilizer rates. Results of this study suggested that the abundance of ammonia-oxidizers had active response to N fertilizer rates and the response of AOA was more obvious than that of AOB. Similarity in the community composition of AOA or AOB among different N fertilizer rates indicate that the community composition of ammonia-oxidizers w

关键词： ammonia-oxidizing bacteria ammonia-oxidizing archaea nitrogen fertilizer rates paddy soil

Energy dissipation and contour integral characterizing fracture behavior of incremental plasticity

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Acta Mechanica Sinica 2011年第2期27卷 251-258页

作者： Qi-lin He lin-zhi Wu Ming Li Hong-Bo Chen Chen Center for Composite Materials Harbin Institute of Technology 150080 Harbin China

J ep -integral is derived for characterizing the frac- ture behavior of elastic-plastic materials. The J ep -integral differs from Rice’s J-integral in that the free energy density rather than the stress working density is employed to define energy-momentum tensor. The J ep -integral is proved to be path-dependent regardless of incremental plasticity and deformation plasticity. The J epintegral possesses clearly clear physical meaning：（1） the value J ep tip evaluated on the infinitely small contour surrounding the crack tip represents the crack tip energy dissipation; （2） when the global steadystate crack growth condition is approached, the value of J ep farss calculated along the boundary contour equals to the sum of crack tip dissipation and bulk dissipation of plastic zone. The theoretical results are verified by simulating mode I crack problems.

关键词： J-integral · Energy dissipation · Proportional loading · Deformation plasticity · Incremental plasticity

Analytical approach to quantum phase transitions of ultracold Bose gases in bipartite optical lattices using the generalized Green＇s function method

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Frontiers of physics 2018年第4期13卷 195-208页

作者： zhi lin Jun Zhang Ying Jiang Department of Physics State Key Laboratory of Surface Physics and Laboratory of Advanced Materials Fudan University Shanghai 200433 China Department of Physics Shanghai University Shanghai 200444 China Qian Weichang College Shanghai University Shanghai 200444 China Key Lab for Astrophysics Shanghai 200234 China

In order to investigate the quantum phase transitions and the time-of-flight absorption pictures analyt- ically in a systematic way for ultracold Bose gases in bipartite optical lattices, we present a generalized Green＇s function method. Utilizing this method, we study the quantum phase transitions of ultracold Bose gases in two types of bipartite optical lattices, i.e., a hexagonal lattice with normal Bose-Hubbard interaction and a d-dimensional hypercubic optical lattice with extended Bose-Hubbard interaction. Furthermore, the time-of-flight absorption pictures of ultracold Bose gases in these two types of lat- tices are also calculated analytically. In hexagonal lattice, the time-of-flight interference patterns of ultracold Bose gases obtained by our analytical method are in good qualitative agreement with the exDerimental results of Soltan-Panahi, et al. [Nat. Phys. 7, 434 （2011）]. In square optical lattice, the emergence of peaks at（±π/a,±π/a） in the time-of-flight absorption pictures, which is believed to bea sort of evidence of the existence of a supersolid phase, is clearly seen when the system enters the compressible phase from charge-density-wave phase.

关键词： ultracold Bose gases quantum phase transition bipartite optical lattice generalizedGreen's function method time-of-flight absorption picture

Effects of the types of overlap on the mechanical properties of FSSW welded AZ series magnesium alloy joints

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International Journal of Minerals,Metallurgy and Materials 2012年第3期19卷 231-235页

作者： Dan Wang Jun Shen lin-zhi Wang School of Materials Science and Engineering Chongqing UniversityChongqing 400044China

The effects of the types of overlap on the mechanical properties of the friction stir spot welding （FSSW） welded AZ series magnesium alloy joints were investigated by microstructural observations, microhardness tests, and tensile tests. The results show that the microstructure of the stir zone adjacent to the periphery of the rotating pin is mainly composed of the upper sheet. The average distance D between the longitudinal segment of the curved interface and the keyhole periphery, the tensile shear force, and the microhardness of the stir zone of the FSSW welded AZ61 alloy joint are the highest in all samples. During FSSW of AZ31 and AZ61 dissimilar magnesium alloys, the irregular deformation of the longitudinal segment of the curved interface appears, while the microhardness of the stir zone is higher when AZ61 alloy is the upper sheet. Moreover, the microhardness of the stir zone increases initially and then decreases sharply in the longitudinal test position.

关键词： magnesium alloys friction stir welding microstructure microhardness tensile properties

A FINITE DIFFERENCE SCHEME FOR SOLVING THE NONlinEAR POISSON-BOLTZMANN EQUATION MODElinG CHARGED SPHERES

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Journal of Computational Mathematics 2006年第3期24卷 252-264页

作者： Zhong-hua Qiao zhi-lin Li Tao Tang Department of Mathematics Hong Kong Baptist University Kowloon Tong Hong Kong China Center for Research in Scientific Computation and Department of Mathematics North Carolina State University Raleigh NC 27695 USA

In this work, we propose an efficient numerical method for computing the electrostatic interaction between two like-charged spherical particles which is governed by the nonlinear Poisson-Boltzmann equation. The nonlinear problem is solved by a monotone iterative method which leads to a sequence of linearized equations. A modified central finite difference scheme is developed to solve the linearized equations on an exterior irregular domain using a uniform Cartesian grid. With uniform grids, the method is simple, and as a consequence, multigrid solvers can be employed to speed up the convergence. Numerical experiments on cases with two isolated spheres and two spheres confined in a charged cylindrical pore are carried out using the proposed method. Our numerical schemes are found efficient and the numerical results are found in good agreement with the previous published results.

关键词： Nonlinear Poisson-Boltzmann equation Electrostatic interaction Irregulardomain Monotone iterative method Multigrid solver