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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

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

APPLICATION OF TWO-DIMENSIONAL WAVELET TRANSFORM IN NEAR-SHORE X-BAND RADAR IMAGES

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Journal of Hydrodynamics 2011年第2期23卷 179-186页

作者： FENG Xiang-bo YAN Yi-xin, zhang wei State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering and College of Harbor Coastal and Offshore Engineering Hohai University Nanjing 210098 China

Among existing remote sensing applications, land-based X-band radar is an effective technique to monitor the wave fields, and spatial wave information could be obtained from the radar images. Two-dimensional Fourier Transform （2-D FT） is the common algorithm to derive the spectra of radar images. However, the wave field in the nearshore area is highly non-homogeneous due to wave refraction, shoaling, and other coastal mechanisms. When applied in nearshore radar images, 2-D FT would lead to ambiguity of wave characteristics in wave number domain. In this article, we introduce two-dimensional Wavelet Transform （2-D WT） to capture the non-homogeneity of wave fields from nearshore radar images. The results show that wave number spectra by 2-D WT at six parallel space locations in the given image clearly present the shoaling of nearshore waves. Wave number of the peak wave energy is increasing along the inshore direction, and dominant direction of the spectra changes from South South West （SSW） to West South West （WSW）. To verify the results of 2-D WT, wave shoaling in radar images is calculated based on dispersion relation. The theoretical calculation results agree with the results of 2-D WT on the whole. The encouraging performance of 2-D WT indicates its strong capability of revealing the non-homogeneity of wave fields in nearshore X-band radar images.

关键词： non-homogeneity X-band radar two-dimensional Wavelet Transform (2-D WT) dispersion relation nearshore wave field

Proteomic analysis of the alteration of protein expression in the placenta of Down syndrome

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Chinese Medical Journal 2011年第22期124卷 3738-3745页

作者： SUN Cheng-juan YAN Li-yu WANG wei YU Song WANG xin zhang wei-yuan Department of Obstetrics Beijing Obstetrics and Gynecology Hospital Capital Medical University Beijing100026 China

Background Down syndrome （DS） is the most common form of human aneuploidy, and there is no effective therapy for the chromosomal abnormalities. We aimed to unravel the molecular mechanisms underlying DS and to provide clues to prenatal screening. Methods A series of proteomics-based experiments was conducted using 19 patients with DS fetuses and 17 normal pregnancies. The proteome of placenta was investigated as displayed by two-dimensional difference gel electrophoresis （2D-DIGE）, and comparisons were made between placentas that developed under DS and normal pregnancy conditions. Multivariate analysis of the resulting protein patterns revealed DS-specific protein expression. Matrix-assisted laser desorption/ionization （MALDI） time-of-flight/time-of-flight （TOF/TOF） high-resolution tandem mass spectrometer （MS）-based identification was successful for 12 out of 17 selected protein spots. Results Among those, three proteins involved in the resist of reactive oxygen species （ROS） and neurogenesis were more abundant in the DS placenta （superoxide dismutase 1, endoplasmic reticulum protein 29 and heat shock protein beta-l）, while peroxiredoxin-6 involved in cell defense mechanism against ROS was expressed at a higher level in the normal pregnancies. Conclusion Knowledge of the DS placenta proteome emphasizes the role of proteins involved in anti-oxidation during DS, and may form the basis of a potential approach to minimize the incidence of DS in the clinical settina.

关键词： Down syndrome placenta proteomics, two-dimensional difference gel electrophoresis Matrix-assisted laser desorption/ionization

QoE oriented intelligent online learning evaluation technology in B5G scenario

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Digital Communications and Networks 2024年第1期10卷 7-15页

作者： Mingzi Chen xin wei Peizhong Xie Zhe zhang School of Communications and Information Engineering Nanjing University of Posts and TelecommunicationsNanjing210003China Key Lab of Broadband Wireless Communication and Sensor Network Technology(Nanjing University of Posts and Telecommunications) Ministry of EducationNanjing210003China Institute of Higher Education Nanjing University of Posts and TelecommunicationsNanjing210003China

Students'demand for online learning has exploded during the post-COvID-19 pandemic ***,due to their poor learning experience,students'dropout rate and learning performance of online learning are not always *** technical advantages of Beyond Fifth Generation(B5G)can guarantee a good multimedia Quality of Experience(QoE).As a special case of multimedia services,online learning takes into account both the usability of the service and the cognitive development of the *** that affect the Quality of Online Learning Experience(OL-QoE)become more *** get over this dilemma,we propose a systematic scheme by integrating big data,Machine Learning(ML)technologies,and educational psychology ***,we first formulate a general definition of OL-QoE by data analysis and experimental *** formula considers both the subjective and objective factors(i.e.,video watching ratio and test scores)that most affect ***,we induce an extended layer to the classic Broad Learning System(BLS)to construct an Extended Broad Learning System(EBLS)for the students'OL-QoE *** the extended layer can increase the width of the BLS model and reduce the redundant nodes of BLS,the proposed EBLS can achieve a trade-off between the prediction accuracy and computation ***,we provide a series of early intervention suggestions for different types of students according to their predicted OL-QoE *** timely interventions,their OL-QoE and learning performance can be *** results verify the effectiveness oftheproposed scheme.

关键词： B5G Online learning Quality of experience

Dissipation-Driven Superradiant Phase Transition of a Two-Dimensional Bose-Einstein Condensate in a Double Cavity

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Chinese Physics Letters 2024年第6期41卷 44-48页

作者： Bo-Hao Wu xin-xin Yang Yu Chen wei zhang Department of Physics and Beijing Key Laboratory of Opto-electronic Functional Materials and Micro-nano Devices Renmin University of ChinaBeijing 100872China Key Laboratory of Quantum State Construction and Manipulation(Ministry of Education) Renmin University of ChinaBeijing 100872China Graduate School of China Academy of Engineering Physics Beijing 100193China Beijing Academy of Quantum Information Sciences Beijing 100193China

We study superradiant phase transitions in a hybrid system of a two-dimensional Bose–Einstein condensate of atoms and two cavities arranged with a tilt *** adjusting the loss rate of cavities,we map out the phase diagram of steady states within a mean field *** is found that when the loss rates of the two cavities are different,superradiant transitions may not occur at the same time in the two cavities.A first-order phase transition is observed between the states with only one cavity in superradiance and both in *** the case that both cavities are superradiant,a net photon current is observed flowing from the cavity with small decay rate to the one with large decay *** photon current shows a non-monotonic dependence on the loss rate difference,owing to the competition of photon number difference and cavity field phase *** findings can be realized and detected in experiments.

关键词： Einstein transitions decay

Automated Identification of Ordered Phases for Simulation Studies of Block Copolymers

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Chinese Journal of Polymer Science 2024年第5期42卷 683-692,I0011页

作者： Yu-Chen zhang wei-Ling Huang Yi-xin Liu State Key Laboratory of Molecule Engineering of Polymers Department of Macromolecular ScienceFudan UniversityShanghai200433China

In unit cell simulations,identification of ordered phases in block copolymers(BCPs)is a tedious and time-consuming task,impeding the advancement of more streamlined and potentially automated research *** this study,we propose a scattering-based automated identification strategy(SAIS)for characterization and identification of ordered phases of BCPs based on their computed scattering *** approach leverages the scattering theory of perfect crystals to efficiently compute the scattering patterns of periodic morphologies in a unit *** the first stage of the SAIS,phases are identified by comparing reflection conditions at a sequence of Miller *** confirm or refine the identification results of the first stage,the second stage of the SAIS introduces a tailored residual between the test phase and each of the known candidate ***,our strategy incorporates a variance-like criterion to distinguish background species,enabling its extension to multi-species BCP *** has been demonstrated that our strategy achieves exceptional accuracy and robustness while requiring minimal computational ***,the approach allows for real-time expansion and improvement to the candidate phase library,facilitating the development of automated research workflows for designing specific ordered structures and discovering new ordered phases in BCPs.

关键词： Block copolymer Phase identification Scattering function