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Science China Mathematics 2008年第4期51卷 777-784页

作者： wu hung-hsi(h.wu) Department of Mathematics University of California

A historical survey of the Gauss-Bonnet theorem from Gauss to Chern.

关键词： Gauss-Bonnet theorem Chern classes characteristic classes 01-02 53-03 53C20

Modified spherical cavity-expansion model for projectile penetration into concrete targets

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Acta Mechanica Sinica 2019年第3期35卷 518-534页

作者： Y.Peng h.wu Q.Fang X.Z.Kong College of Liberal Arts and Sciences National University of Defense TechnologyChangsha 410073China Key Laboratory of Performance Evolution and Control for Engineering Structures Tongji UniversityShanghai 200092China Research Institute of Structural Engineering and Disaster Reduction College of Civil EngineeringTongji UniversityShanghai 200092China State Key Laboratory for Disaster Prevention and Mitigation of Explosion and Impact PLA Amy Engineering UniversityNanjing 210007China

A modified spherical cavity-expansion model is developed in this paper.(1) We introduce a piecewise hyperbolic yield criterion suitable for pressure less than fc/3 to describe the mechanical behavior in the elastic region for the elastic-plastic response and modify the crack occurrence condition for the elastic-cracked-plastic response.(2) The hyperbolic yield criterion and a piecewise equation of state (EOS) are adopted for a better description of the plastic behavior of concrete material. Then, the modified model is validated by several projectile penetration tests in both the normal strength concrete (NSC) and ultra-high performance cement-based composite (UhPCC) targets. Finally, the hydrostatic pressure of the targets under rigid ogive-nosed projectile penetrations is found to be nearly within (0, 1.6 GPa), which usually exceeds the range that the shear strength-pressure test data covered. The influence of yield criterion on depth of penetration is discussed and it is recommended that the pressure should arrive at least 400 MPa in the related triaxial compression tests.

关键词： Dynamic cavity-expansion model Projectile Penetration Concrete Depth of penetration

Interface defeat studies of long-rod projectile impacting on ceramic targets

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Defence Technology（防务技术） 2020年第1期16卷 50-68页

作者： Y.X.Zhai h.wu Q.Fang Amy Engineering University of PLA Nanjing210007China Research Institute of Structural Engineering and Disaster Reduction College of Civil EngineeringTongji UniversityShanghai200092China

The interface defeat phenomenon always occurs when a long-rod projectile impacting on the ceramic target with certain velocity,i.e.,the projectile is forced to flow radially on the surface of ceramic plates for a period of time without significant *** defeat has a direct effect upon the ballistic performance of the armor piercing projectile,which is studied numerically and theoretically at ***,by modeling the projectiles and ceramic targets with the SPh(Smoothed Particle hydrodynamics)particles and Lagrange finite elements,the systematic numerical simulations on interface defeat are performed with the commercial finite element program *** different responses,i.e.,complete interface defeat,dwell and direct penetration,are reproduced in different types of ceramic targets(bare,buffered,radially confined and oblique).Furthermore,by adopting the validated numerical algorithms,constitutive models and the corresponding material parameters,the influences of projectile(material,diameter,nose shape),constitutive models of ceramic(Jh-1 and Jh-2 models),buffer and cover plate(thickness,constraints,material),as well as the prestress acted on the target(radial and hydrostatic) on the interface defeat(transition velocity and dwell time) are syste matically ***,based on the energy conservation approach and taking the strain rate effect of ceramic material into account,a modified model for predicting the upper limit of transition velocity is proposed and *** present work and derived conclusions can provide helpful reference for the design and optimization of both the long-rod projectile and ceramic armor.

关键词： Interface defeat Ceramic Transition velocity Numerical simulation Parametric study

An Improved Method for Preparation of Uniform and Functional Mitochondria from Fresh Liver

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Journal of Clinical and Translational hepatology 2019年第1期7卷 46-50页

作者： Nagham Khouri Farah Xiaocong Liu Catherine h.wu George Y.wu Department of Medicine Division of Gastroenterology-HepatologyUniversity of Connecticut Health CenterFarmingtonCTUSA

Background and Aims:As the major energy source for mammalian cells,mitochondria have been the subject of numerous ***,the isolation and purification of healthy mitochondria,especially from fresh tissue,remains *** most popular methods and kits involve various centrifugation steps which require substantial time and equipment but do not consistently provide pure preparations of functional *** aim of this study was to determine whether methods could be devised to improve the purity and yield of functional mitochondria from fresh ***:Fresh mouse liver was homogenized,and cells *** size analysis,quantitation of mitochondrial DNA,mitochondrial oxygen consumption,and purity of mitochondria(by electron microscopy)were measured in samples after various purification steps and significant differences ***:A two-step procedure consisting of centrifugation followed by filtration through 1.2μand 0.8μfilters resulted in uniform mitochondrial preparations with diameters between 520-540 nm,and approximately 5-times more pure *** mitochondria thus obtained had oxygen consumption and sensitivities to mitochondrial inhibitors that were indistinguishable from those purified by centrifugation *** microscopy confirmed the presence of more uniform and 4-5 times greater concentrations of mitochondria compared to centrifugation ***:A two-step procedure consisting of sequential centrifugation followed by filtration is a rapid method for the production of highly purified,uniform and functional mitochondria.

关键词： Mitochondria Isolation Filtration Purified Uniform Functional

Secondary Structural Elements of the hCV X-region Involved in Viral Replication

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Journal of Clinical and Translational hepatology 2015年第1期3卷 1-8页

作者： Nidhi Gupta Catherine h.wu George Y.wu Department of Medicine Division of Gastroenterology-Hepatology University of Connecticut Health Center Farmington CT USA

Background and Aims:The noncoding regions in the 3'-untranslated region (UTR) of the hepatitis C virus (hCV)genome contain secondary structures that are important for *** aim of this study was to identify detailed conformational elements of the X-region involved in hCV ***:Ribonucleic acid (RNA) structural analogs X94,X12,and X12c were constructed to have identical conformation but 94%,12%,and 0% sequence identity,respectively,to the X region of hCV genotype *** of structural analogs on replication of hCV genotypes 1b and 2a hCV RNA were studied by quantitative reverse transcriptase polymerase chain ***:In replicon BB7 cells,a constitutive replication model,hCV RNA levels decreased to 55%,52%,53%,and 54% after transfection with expression plasmids generating RNA structural analogs 5B-46,X-94,X-12,and X-12c,respectively (phCV genotype 2a infection model,RNA analogs 5B-46,X-94,and X-12 in hepatic cells inhibited replication to 11%,9%,and 12%,*** the X-12 analog was only 12% identical to the corresponding sequence of hCV genotype 2a,the sequence per se,or antisense effects were unlikely to be ***:The data suggest that conformation of secondary structures in 3'-UTR of hCV RNA genome is required for hCV *** expression of RNA analogs predicted to have identical stem-loop structures might inhibit hCV infection of hepatocytes in liver and may represent a novel approach to design anti-hCV agents.

关键词： hCV RNA genome hCV X-region hepatitis C virus Infection Japanese Fulminant hepatitis Virus RNA secondary structure

Stability analyses of the mass abrasive projectile high-speed penetrating into a concrete target Part III: Terminal ballistic trajectory analyses

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Acta Mechanica Sinica 2015年第4期31卷 558-569页

作者： h.wu X.W.Chen Q.Fang X.Z.Kong L.L.he Institute of Systems Engineering China Academy of Engineering Physics State Key Laboratory for Disaster Prevention & Mitigation of Explosion & Impact PLA University of Science and Technology

During the high-speed penetration of projectiles into concrete targets （the impact velocity ranges from 1.0 to 1.5 km/s）, important factors such as the incident oblique and attacking angles, as well as the asymmetric abrasions of the projectile nose induced by the target-projectile interactions, may lead to obvious deviation of the terminal ballistic tra- jectory and reduction of the penetration efficiency. Based on the engineering model for the mass loss and nose-blunting of ogive-nosed projectiles established, by using the Differ- ential Area Force Law （DAFL） method and semi-empirical resistance function, a finite differential approach was pro- grammed （PENTRA2D） for predicting the terminal ballistic trajectory of mass abrasive high-speed projectiles penetrating into concrete targets. It accounts for the free-surface effects on the drag force acting on the projectile, which are attributed to the oblique and attacking angles, as well as the asymmetric nose abrasion of the projectile. Its validation on the prediction of curvilinear trajectories of non-normal high-speed pene- trators into concrete targets is verified by comparison with available test data. Relevant parametric influential analyses show that the most influential factor for the stability of ter- minal ballistic trajectories is the attacking angle, followed by the oblique angle, the discrepancy of asymmetric nose abrasion, and the location of mass center of projectile. The terminal ballistic trajectory deviations are aggravated as the above four parameters increase.

关键词： Projectile Penetration Concrete Massabrasion Terminal ballistic trajectory

Gyroscopic modes decoupling method in parametric instability analysis of gyroscopic systems

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Acta Mechanica Sinica 2018年第5期34卷 963-969页

作者： Y.J.Qian X.D.Yang h.wu W.Zhang T.Z.Yang College of Mechanical Engineering Beijing University of TechnologyBeijing 100124China Department of Mechanics Tianjing UniversityTianjing 300072China

Traditional procedures to treat vibrations of gyroscopic continua involve direct application of perturbation methods to a system with both a strong gyroscopic term and other weakly coupled *** this study,a gyroscopic modes decoupling method is used to obtain an equivalent system with decoupled gyroscopic modes having only weak *** the axially moving string as an example,the instability boundaries in the vicinity of parametric resonances are detected using both the traditional coupled gyroscopic system and our system with decoupled gyroscopic modes,and the results are compared to show the advantages and disadvantages of each method.

关键词： Axially moving material Decoupling of gyroscopic modes Parametric instability Perturbation method Gyroscopic system

The Molecular and Structural Basis of hBV-resistance to Nucleos(t)ide Analogs

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Journal of Clinical and Translational hepatology 2014年第3期2卷 202-211页

作者： Nidhi Gupta Milky Goyal Catherine h.wu George Y.wu Department of Medicine Division of Gastroenterology-HepatologyUniversity of Connecticut Heath CenterFarmingtonUSA Department of Microbiology College of Basic Sciences and HumanitiesPunjab Agriculture UniversityLudhianaPunjabIndia

Infection with hepatitis B virus(hBV)is a worldwide health *** hepatitis B can lead to fibrosis,liver cirrhosis,and hepatocellular carcinoma(hCC).Management of the latter two conditions often requires liver *** with conventional interferon or pegylated interferon alpha can clear the virus,but the rates are very *** likelihood,however,of viral resistance to interferon is *** main problems with this therapy are the frequency and severity of side *** contrast,nucleos(t)ide analogs(NAs)have significantly lower side effects,but require long term treatment as sustained virological response rates are extremely ***,long term treatment with NAs increases the risk for the development of anti-viral drug *** by understanding the molecular basis of resistance and using agents with multiple sites of action can drugs be designed to optimally prevent the occurrence of hBV antiviral resistance.

关键词： hBV hCC Nucleos(t)ide analogs

Achieving ultrahigh strength and ductility in high-entropy alloys via dual precipitation

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Journal of Materials Science & Technology 2023年第35期166卷 67-77页

作者： J.M.Guo B.C.Zhou S.Qiu h.J.Kong M.C.Niu J.h.Luan T.L.Zhang h.wu Z.B.Jiao Department of Mechanical Engineering Research Institute for Advanced ManufacturingThe Hong Kong Polytechnic UniversityHong KongChina The hong Kong Polytechnic University Shenzhen Research Institute Shenzhen 518057China Department of Materials Science and Engineering City University of Hong KongHong KongChina State Key Laboratory of Powder Metallurgy Central South UniversityChangsha 410083China

The strength-ductility trade-offhas been a longstanding dilemma in metallic *** we report an innovative approach to achieve a high strength-ductility synergy via dual precipitation of sheared and bypassed precipitates.(Ni_(2) Co_(2) FeCr)_(96-x) Al_(4) Nb_(x)(at.%)alloys strengthened by nanoscale L12 particles and Laves precipitates were selected as a model for this study,and their precipitate microstructures and mechanical properties were thoroughly *** dual-precipitation-strengthened alloys exhibit a yield strength of more than 1400 MPa,an ultimate tensile strength of over 1800 MPa,and a uniform elon-gation of 18%,thus achieving a high strength-ductility *** analysis reveals that the nanoscale L1_(2) precipitates contribute to the strength via the particle shearing mechanism,whereas the Laves phase provides the strengthening through the Orowan bypass *** study of deformation microstruc-tures shows that the L1_(2) precipitates are sheared by stacking faults,which facilitates long-range disloca-tion gliding through the *** a result,deformation induces the formation of hierarchical stacking fault networks and immobile Lomer-Cottrell locks,which effectively enhance the work hardening ca-pability and plastic stability,thereby resulting in a high ductility at high strength *** are piled-up against the interface between the Laves precipitates and matrix,which increases the work hardening capability at the early stages of plastic deformation but causes stress *** dual precipitation strategy may be useful for many other alloys for achieving superior mechanical properties for technological applications.

关键词： high-entropy alloy Dual precipitation Precipitation strengthening Deformation mechanism

Fenestrated Basilar Artery Associated with Multiple Aneurysms

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Journal of huazhong University of Science and Technology(Medical Sciences) 2003年第4期23卷 418-419,426页

作者：李文彬李明华 h.Grady Daniel Dee h.wu Timothy L.Tytle Rifat Karatas Yasemin Karatas William T.C.Yuh Department of Radiology the Affiliated Sixth People's Hospital Shanghai Jiaotong University Shanghai 200233 Department of Radiology University of Oklahoma Health Sciences Center Oklahoma City OK 73104 USA

Key words fenestrated basilar artery - multiple aneurysm LI Wenbin, male, born in 1964, M. D., Ph. D

关键词： fenestrated basilar artery multiple aneurysm