检索结果-南通市图书馆

Supersonic flow onto solid wedges, multidimensional shock waves and free boundary problems Dedicated to Professor LI Ta Tsien on the Occasion of His 80th Birthday

在线全文

学校读者我要写书评

暂无评论

Science China Mathematics 2017年第8期60卷 1353-1370页

作者： CHEN gui-qiang School of Mathematical Sciences Fudan University Academy of Mathematics and Systems Science Chinese Academy of Sciences School of Mathematical Sciences University of Chinese Academy of Sciences Mathematical Institute University of Oxford

When an upstream steady uniform supersonic flow impinges onto a symmetric straight-sided wedge,governed by the Euler equations,there are two possible steady oblique shock configurations if the wedge angle is less than the detachment angle—the steady weak shock with supersonic or subsonic downstream flow(determined by the wedge angle that is less than or greater than the sonic angle)and the steady strong shock with subsonic downstream flow,both of which satisfy the entropy *** fundamental issue—whether one or both of the steady weak and strong shocks are physically admissible solutions—has been vigorously debated over the past eight *** this paper,we survey some recent developments on the stability analysis of the steady shock solutions in both the steady and dynamic *** the static stability,we first show how the stability problem can be formulated as an initial-boundary value type problem and then reformulate it into a free boundary problem when the perturbation of both the upstream steady supersonic flow and the wedge boundary are suitably regular and small,and we finally present some recent results on the static stability of the steady supersonic and transonic *** the dynamic stability for potential flow,we first show how the stability problem can be formulated as an initial-boundary value problem and then use the self-similarity of the problem to reduce it into a boundary value problem and further reformulate it into a free boundary problem,and we finally survey some recent developments in solving this free boundary problem for the existence of the PrandtlMeyer configurations that tend to the steady weak supersonic or transonic oblique shock solutions as time goes to *** further developments and mathematical challenges in this direction are also discussed.

关键词： shock wave free boundary wedge problem transonic mixed type Euler equations static stability dynamic stability

A medical robot for needle placement therapy in liver cancer

在线全文

学校读者我要写书评

暂无评论

Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2010年第4期11卷 263-269页

作者： Xing-guang DUAN gui-bin BIAN Hong-hua ZHAO Xing-tao WANG qiang huang Intelligent Robotics Institute Beijing Institute of Technology Beijing 100081 China

Hepatocellular carcinoma (HCC) is the second most common malignancy in *** microwave ablation (MWA) is an effective method for liver cancer,a robotic surgical system with ultrasound-directed was designed to assist surgeons on positioning the *** robotic system includes a surgical robot with 5 degrees of freedom,a workstation for path-planning and image processing,a conventional 2D ultrasound device,and an electromagnetic (EM) tracking *** space,clinical operation requirements and optimal mechanical structure are the key factors to be considered in designing a medical robot suitable for use by *** on the mechanics of the needle placement robot,we have conducted detailed kinematic analysis,including a combined numerical algorithm and coordinate ***,the feasibility of the needle placement robot has been validated by experiment.

关键词： Surgical robot Needle insertion Inverse kinematics Numerical solution

Natural products targeting mitochondria: A promising strategy for metabolic syndrome

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Natural Medicines 2020年第11期18卷 801-802页

作者： qiang gui-Fen State Key Laboratory of Bioactive Substance and Function of Natural Medicines Institute of Materia MedicaChinese Academy of Medical Sciences and Peking Union Medical College and Beijing Key Laboratory of Drug Target and Screening ResearchBeijing 100050China

Metabolic syndrome (MetS) is a complex pathophysiological state characterized by obesity, insulin resistance,dysglycemia, dyslipidemia and hypertension, which consequently contributes to coronary heart disease, stroke... 详细信息

关键词： coronary obesity Metabolic

Weak Continuity and Compactness for Nonlinear Partial Differential Equations

在线全文

学校读者我要写书评

暂无评论

Chinese Annals of Mathematics,Series B 2015年第5期36卷 715-736页

作者： gui-qiang G.CHEN School of Mathematical Sciences Fudan University Academy of Mathematics and Systems Science Chinese Academy of Sciences Mathematical Institute University of Oxford

This paper presents several examples of fundamental problems involving weak continuity and compactness for nonlinear partial differential equations, in which compensated compactness and related ideas have played a significant role. The compactness and convergence of vanishing viscosity solutions for nonlinear hyperbolic conservation laws are first analyzed, including the inviscid limit from the Navier-Stokes equations to the Euler equations for homentropic flow, the vanishing viscosity method to construct the global spherically symmetric solutions to the multidimensional compressible Euler equations, and the sonic-subsonic limit of solutions of the full Euler equations for multi-dimensional steady compressible fluids. Then the weak continuity and rigidity of the Gauss-Codazzi-Ricci system and corresponding isometric embeddings in differential geometry are revealed. Further references are also provided for some recent developments on the weak continuity and compactness for nonlinear partial differential equations.

关键词： Weak continuity Compensated compactness Nonlinear partial differential equations Euler equations Gauss-Codazzi-Ricci system

Investigation on the flow control of micro-vanes on a supersonic spinning projectile

在线全文

学校读者我要写书评

暂无评论

Defence Technology（防务技术） 2016年第3期12卷 227-233页

作者： Jie MA Zhi-hua CHEN Zhen-gui huang Jian-guo GAO qiang ZHAO Key Laboratory of Transient Physics Nanjing University of Science and Technology

Studies have shown that micro-wedge vortex generators(MVG)can effectively control the flow separation of supersonic boundary *** order to improve the flight stability of spinning projectile,the original standard 155 mm projectile was taken as an example,and the micro-vanes were mounted at the projectile shoulder to investigate the separation control on the aerodynamic characteristics of *** simulations were performed with the use of DES method for the flow fields of projectiles with and without micro-vanes,and the characteristics of the boundary layer structures and aerodynamic data were compared and *** results show that the micro-vanes can be used to inhibit separation of fluid on projectile surface,and improve the flight stability and firing dispersion of projectile.

关键词： Spinning projectile Micro-vane Stability Aerodynamic characteristics Fluid control

Hierarchical Porous Carbon Counter Electrode for Dye-Sensitized Solar Cells

在线全文

学校读者我要写书评

暂无评论

Chinese Physics Letters 2011年第3期28卷 224-227页

作者： WANG gui-qiang huang Cong-Cong XING Wei ZHUO Shu-Ping College of Chemical Engineering Shandong University of TechnologyZibo 255049

Hierarchical porous carbon is prepared by a combination of self-organization and chemical activation and explored as counter electrode for dye-sensitized solar *** structure analysis shows that micropores generated within the mesopore wall and the pristine mesopore structure of mesoporous carbon are preserved during KOH *** impedance spectroscopy studies demonstrate a relatively high electrocatalytic activity of hierarchical porous carbon electrode for triiodide reduction,as compared with a pristine mesoporous carbon *** enhanced electrocatalytic activity is beneficial for improving the photovoltaic performance of dyesensitized solar *** overall conversion efficiency of dye-sensitized solar cells with the hierarchical porous carbon electrode increased by 11.5%compared with that of the cell with a pristine mesoporous carbon electrode.

关键词： electrode Solar dye

Storage life prediction under pre-strained thermally-accelerated aging of HTPB coating using the change of crosslinking density

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Defence Technology（防务技术） 2021年第4期17卷 1387-1394页

作者： Yong-qiang Du Jian Zheng gui-bo Yu Shijiazhuang Campus Army Engineering UniversityShijiazhuang050003China

In order to predict the storage life of a certain type of HTPB(hydroyl-terminated polybutadiene)coating at 25℃ and analyze the influence of pre-strain on the storage life,the accelerated aging tests of HTPB coating at 40℃,50℃,60℃,70℃ with the pre-strain of 0%,3%,6%,9%,respectively were carried *** variation regularity of the change of crosslinking density was analyzed and the aging model of HTPB coating under pre-strained thermally-accelerated aging was *** storage life of HTPB coating at 25℃ was estimated by using the Berthelot equation as the end point of the aging life with a 30% decrease in maximum *** results showed that the change of crosslinking density of HTPB coating increased with the increase of aging temperature and aging time,and decreased with the increase of *** 0% prestrain,the relationship between the change of crosslinking density of HTPB coating and the aging time can be described by the logarithmic model with the confidence probability greater than 99%.The stress relaxation phenomenon existed under 3%,6%and 9%pre-strained *** aging model considering chemical aging and pre-strain was established with the confidence probability greater than 90%.The storage life of HTPB coating was 15.2935 years at 25C under 0% prestrain,which was reduced by 13.9007%,75.6949% and 89.7859% under 3%,6% and 9% pre-strain,*** existence of pre-strain has a serious impact on the storage life of HTPB coating,therefore,the pre-strain should be avoided as much as possible during the actual storage.

关键词： HTPB coating Crosslinking density Aging model Storage life prediction Berthelot

Two-Dimensional Riemann Problems:Transonic Shock Waves and Free Boundary Problems

在线全文

学校读者我要写书评

暂无评论

Communications on Applied Mathematics and Computation 2023年第3期5卷 1015-1052页

作者： gui-qiang G.Chen Oxford Centre for Nonlinear PDE Mathematical InstituteUniversity of OxfordOxford OX26GGUK

We are concerned with global solutions of multidimensional(M-D)Riemann problems for nonlinear hyperbolic systems of conservation laws,focusing on their global configurations and *** present some recent developments in the rigorous analysis of two-dimensional(2-D)Riemann problems involving transonic shock waves through several prototypes of hyperbolic systems of conservation laws and discuss some further M-D Riemann problems and related problems for nonlinear partial differential *** particular,we present four different 2-D Riemann problems through these prototypes of hyperbolic systems and show how these Riemann problems can be reformulated/solved as free boundary problems with transonic shock waves as free boundaries for the corresponding nonlinear conservation laws of mixed elliptic-hyperbolic type and related nonlinear partial differential equations.

关键词： Riemann problems Two-dimensional(2-D) Transonic shocks Solution structure Free boundary problems Mixed elliptic-hyperbolic type Global configurations Large-time asymptotics Global attractors Multidimensional(M-D) Shock capturing methods

Study on Effectiveness of Solitary-Wave-Like Form Based on Overtopping Data from Irregular Wave Tests

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

China Ocean Engineering 2024年第4期38卷 701-710页

作者： LI Xiao-liang huang gui-biao School of Naval Architecture&Ocean Engineering Jiangsu University of Science and TechnologyZhenjiang 212100China

The previous study conducted by Li(2022)demonstrates that the Goda graph can be adequately represented by a solitary-wave-like form across the entire range of relative water depth,with the exception of the extremely shallow ***,it remains uncertain whether this form is equally effective when applied to test data generated by irregular waves,as the Goda graph was initially developed based on overtopping data from regular wave ***,it is unclear whether this form is suitable for formulating overtopping discharge at composite vertical *** order to address these questions,a 2D overtopping experiment was conducted,incorporating both simple and composite types of vertical walls,with various relative water depths across the entire range,excluding the extremely shallow zone.A novel analysis procedure was developed,which proved to be highly productive and can be considered a general method for data ***,the study yielded two conclusions:(1)the solitary-wave-like form is remarkably effective in formulating overtopping test data generated by irregular waves,regardless of whether the vertical wall is simple or composite,and(2)the resulting formulas exhibit definitely better performance compared with existing formulas.

关键词： solitary-wave-like form overtopping discharge overtopping formula vertical wall