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Numerical investigation of a muzzle multiphase flow field using two underwater launch methods

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Defence Technology（防务技术） 2022年第8期18卷 1454-1469页

作者： Jing-hui zhang Yong-gang Yu xin-wei zhang School of Energy and Power Engineering Nanjing University of Science&TechnologyNanjing210094China

A two-dimensional axisymmetric model, employing a dynamic mesh and user-defined functions, is used to numerically simulate the transient multiphase flow field produced by an underwater gun. Furthermore, a visualized shooting experiment platform with a high-speed camera is built to observe the evolution process of such a multiphase flow field. The simulated phase distribution diagram is agreed well with the shadow photo of the experiment, indicating that the numerical model is reasonable. Further examinations of the multiphase flow fields by using the submerged and sealed launch methods show that use of the sealed launch can significantly improve the interior ballistic performance of an underwater gun. In the cases by using these two types of underwater launch methods, the displacement of the projectile within the range of the muzzle flow field meets the exponential law over time. Moreover, a not fully developed bottle-shaped shock wave is formed when t = 0.4 ms, but this bottle-shaped shock wave expands more rapidly for the sealed launch. In addition, the amplitude of pressure oscillation for the sealed launch is larger than that of the submerged launch, but the pressure oscillation of the sealed launch lasts shorter.

关键词： Underwater launch Multiphase flow Muzzle flow field Numerical simulation Mach disk

Statistical model of magnetization reversal in Nd-Fe-B sintered magnets

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Rare Metals 2006年第z1期25卷 521-525页

作者： WANG Huijie ZHU Minggang LI wei zhang xin Division of Functional Materials Central Iron & Steel Research Institute Beijing 100081 China Division of Functional Materials Central Iron & Steel Research Institute Beijing 100081 China Division of Functional Materials Central Iron & Steel Research Institute Beijing 100081 China China Petroleum Materials Tianjin Corporation Tianjin 300204 China

Statistical model of magnetization reversal was used to simulate the magnetization reversal behavior in the sintered Nd-Fe-B magnets with double grain-size distributions due to the abnormal grain growth (AGG). The magnetic properties and mechanical properties due to the formation of AGG grains in Nd-Fe-B sintered magnets were tested. The results show that the magnetic properties, especially the rectangularity were severely deteriorated after the formation of the AGG grains and a step was shown on the demagnetization curve, and the occurrence of AGG may account for the poor rectangularity and existence of the step on demagnetization curve according to the statistical model of magnetization reversal. The fracture toughness and bending strength are lowered because of the stress concentration in the AGG grains. The SEM images show that the formation of AGG grains is caused by the solid sintering due to the absence of RE-rich phase. Statistical model of magnetization reversal can qualitative by explain the dependence of the magnetization reversal behavior on the grain size in the Nd-Fe-B sintered magnets.

关键词： sintered Nd-Fe-B magnets mechanical properties magnetization reversal abnormal grain growth

Chemical Constituents of Daphne giraldii Nitsche

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Journal of Integrative Plant Biology 2006年第12期48卷 1498-1500,1501页

作者： wei-xin Sun Qiang zhang Jian-Qin Jiang Department of Natural Medicine Chemistry China Pharmaceutical University Nanjing 210038 China

In a search for structurally interesting substances from traditional Chinese medicines, eight compounds were isolated from an ethanolic extract of the stem bark of Daphne giraldii Nitsche. On the basis of one- and two-dimensional nuclear magnetic resonance and mass spectrometry data, and chemical methods, their structures were determined to be 2H-1-benzopyran-2-one-8-hydroxy-7-O-β-D-glucopyranosyl-5-（2-oxo- 2H-1-benzopyran-7-hydroxy-8-yloxy）（compound 1）, 1-pentanone, 1-（4-hydroxyphenyl）-5-phenyl （compound 2）, octadecyl caffeate （compound 3）, （＋）syringaresinol-4,4＇-diglycoside （compound 4）, daphnetin-8-O-β-D- glucopyranoside （compound 5）, p-hydroxybenzoic acid （compound 6）, 7,7＇-dihydroxy-[6, 8＇-bi-2H-benzopyran]- 2, 2＇-dione （compound 7）, and daphnorin （compound 8）, respectively. Of the compounds isolated, compounds 1 and 2, which we named daphnolin and daphnolon, respectively, were new, and the others were obtained from this plant for the first time.

关键词： Daphne giraldii daphnolin daphnolon dicoumaringlycoside

A New Compound from Daphne giraldii Nitsche

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Chinese Chemical Letters 2006年第8期17卷 1054-1056页

作者： wei xin SUN Qiang zhang Jian Qin JIANG Department of Natural Medicine Chemistry China Pharmaceutical University Nanjing 210038

A new compound, named daphnolin （1）, was isolated from the stem barks of Daphne giraldii Nitsche. Its structure was elucidated as 8-hydroxy-7-O-β-D-glucopyranosyl-5-（2-oxo-2H-1-benzopyran-7-hydroxy-8-yloxy）-2H-1-... 详细信息

关键词： Daphne giraldii dicoumaringlycoside daphnolin.

Electromagnetic Scattering and Inverse Scattering of Layered Media with a Slightly Rough Surface

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Chinese Physics Letters 2011年第1期28卷 86-89页

作者： LIN Zhi-wei XU xin zhang Xiao-Juan FANG Guang-You Key Laboratory for Electromagnetic Radiation and Sen ~ing Technology Institute o1 Electronics Chinese Academy ot Sciences Beijing 100190

An electromagnetic （EA1） scattering model for layered media covered by a 3D infinite rough surface and the corresponding inversion technique are investigated. The work aims at remote sensing the surface roughness and dielectric constant for different depths of bear soil through radar measurement data. The forward problem is carried out by the wave decomposition method. The small perturbation method （SPM） and EM boundary conditions are employed to solve the integral equations introduced by the wave decomposition method. The second-order SPM solution of the scatteringfield is involved in the computation of the forward problem for the first time. The backseattering coefficients of multiple frequencies, multiple angles and multiple polarizations are employed to create a nonlinear optimization problem. A genetic algorithm is introduced to help the inversion procedure approaeh to the global minimum of the cost function. Examples are carried out to validate the inversion technique. The inverion results show good agreement with the forward problem with given parameters and pose good tolerance to the input data with the additive white Gaussian noise.

关键词： INVERSE scattering transform SURFACE roughness ELECTROMAGNETIC wave scattering LAYER structure (Solids) DIELECTRICS RANDOM noise theory

An Inverse Electromagnetic Scattering Method for One-Dimensional Inhomogeneous Media

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Chinese Physics Letters 2011年第1期28卷 82-85页

作者： LIN Zhi-wei XU xin zhang Xiao-Juan FANG Guang-You Key Laboratory for Electromagnetic Radiation and Detection Technology Institute of Electronics Chinese Academy of Sciences Beijing 100190

A frequency-domain inversion scheme for reconstructing the permittivity profile of one-dimensional inhomoge- neous media is proposed. The generalized reflection coefficients and the generalized transmission coefficients of the inhomogeneous media are used as the input data of the inverse model. A Newton-like iterative algorithm known as the generalized pulse-spectrum technique with the Tikhonov regularization is applied to solve the in- verse problem. Novel boundary conditions are proposed for the inverse problem and therefore the permittivity at the boundary of the inhomogeneous media is not required as prior knowledge. The choice of frequency points of the frequency-domain method is also investigated. Numerical examples are carried out to validate the inversion technique. Good agreements between the reconstructed profiles and the true profiles are shown.

关键词： Mathematical physics Accelerators beams and electromagnetism

Hawking-Page transition and the dual relations of anti-de Sitter black holes surrounded by dark energy in general dimensions

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Communications in Theoretical Physics 2024年第7期76卷 94-104页

作者： zhang xin Xu wei School of Mathematics and Physics China University of GeosciencesWuhan 430074China

Recently,a dual relation T_(0)(n+1)=T_(HP)(n)between the minimum temperature(T_(0)(n+1))black hole phase and the Hawking-Page transition(T_(HP)(n))black hole phase in two successive dimensions was introduced by wei et al(2020 ***.D10210411);this was reminiscent of the anti-de Sitter/conformal field theory(AdS/CFT)correspondence,as the Hawking-Page transition temperature could be treated as the temperature of the dual physical quantity on the boundary and the latter corresponds to that in the *** this paper,we discuss the Hawking-Page transition and the dual relations in Ads black holes surrounded by dark energy in general *** findings reveal the occurrence of the Hawking-Page transition between the thermal AdS radiation and thermodynamically stable large AdS black holes,in both the spacetime surrounded by phantom dark energy and the spacetime surrounded by quintessence dark *** discuss the effects of the phantom dark energy and quintessence dark energy on the Hawking-Page transition *** the dual relation in particular,it works well for the case of an AdS black holes surrounded by phantom dark *** the case of an Ads black hole surrounded by quintessence dark energy,the dual relation should be modified under an open assumption that the state parameter and the density parameter of the quintessence dark energy depend on the dimensions of the spacetime.

关键词： Hawking-Page transition dark energy black hole thermodynamics

Research on the principle of space high-precision temperature control system of liquid crystals based Stokes polarimeter

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Research in Astronomy and Astrophysics 2021年第1期21卷 97-104页

作者： xin-wei zhang Yang zhang Jia-Ben Lin Jun-Feng Hou Yuan-Yong Deng Key Laboratory of Solar Activity National Astronomical ObservatoriesChinese Academy of SciencesBeijing100101China School of Astronomy and Space Science University of Chinese Academy of SciencesBeijing 101408China

The magnetic field is one of the most important parameters in solar physics,and a polarimeter is the key device to measure the solar magnetic *** crystals based Stokes polarimeter is a novel technology,and will be applied for magnetic field measurement in the first space-based solar observatory satellite developed by China,Advanced Space-based Solar ***,the liquid crystals based Stokes polarimeter in space is not a mature ***,it is of great scientific significance to study the control method and characteristics of the *** retardation produced by a liquid crystal variable retarder is sensitive to the temperature,and the retardation changes 0.09°per 0.10℃.The error in polarization measurement caused by this change is 0.016,which affects the accuracy of magnetic field *** order to ensure the stability of its performance,this paper proposes a high-precision temperature control system for liquid crystals based Stokes polarimeter in *** order to optimize the structure design and temperature control system,the temperature field of liquid crystals based Stokes polarimeter is analyzed by the finite element method,and the influence of light on the temperature field of the liquid crystal variable retarder is analyzed *** analyzing the principle of highprecision temperature measurement in space,a high-precision temperature measurement circuit based on integrated operational amplifier,programmable amplifier and 12 bit A/D is designed,and a high-precision space temperature control system is developed by applying the integral separation PI temperature control algorithm and PWM driving heating *** experimental results show that the effect of temperature control is accurate and stable,whenever the liquid crystals based Stokes polarimeter is either in the air or *** temperature stability is within±0.0150℃,which demonstrates greatly improved stability for the liquid crystals based Stokes polarim

关键词： liquid crystals based Stokes polarimeter high-precision temperature measurement space high-precision temperature control temperature field analysis PID control

Abdominal bronchogenic cyst:A rare case report

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World Journal of Clinical Cases 2022年第34期10卷 12671-12677页

作者： Chao Li xin-wei zhang Chang-An Zhao Min Liu School of Public Health Xi’an Jiaotong UniversityXi’an 710061Shaanxi ProvinceChina Department of General Surgery Xi’an Gaoxin HospitalXi'an 710075Shaanxi ProvinceChina Department of Thoracic Surgery Shaanxi Provincial Cancer HospitalXi’an 710061Shaanxi ProvinceChina Department of Pathology School of Basic Medical ScienceXi’an Jiaotong UniversityXi’an 710061Shaanxi ProvinceChina

BACKGROUND Bronchogenic cysts are cystic masses caused by congenital abnormal development of the respiratory system,and usually occur in the pulmonary parenchyma or *** SUMMARY A rare case of a bronchogenic cyst discovered in the abdominal cavity of a 35-year-old man is *** examination found a space-occupying lesion in the patient’s abdomen for 4 *** exploration found the cyst tightly adhered to the stomach and its peripheral blood vessels;therefore,intraoperative laparotomy was *** cystic mass was resected en bloc with an Endo-GIA *** final postoperative pathological diagnosis confirmed an abdominal bronchogenic *** This is a rare case of a bronchogenic cyst that was discovered within the abdominal cavity of a male *** cyst is easily confused with or misdiagnosed as other ***,it is necessary to distinguish abdominal bronchogenic cyst from gastrointestinal stromal tumor,Meckel’s diverticulum,enteric duplication cyst,or *** computer tomography and magnetic resonance imaging were the primary diagnostic approaches,endoscopic ultrasound-guided fine-needle aspiration could assist with clarification of the cytological or histopathological diagnosis before surgery.

关键词： Bronchogenic cyst Abdominal cavity Endoscopic ultrasound-guided fine-needle aspiration Case report