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Effect of compressibility on the hypervelocity penetration

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Acta Mechanica Sinica 2018年第1期34卷 82-98页

作者： w.J.Song X.w.chen P.chen Department of Mechanics and Engineering Science College of Engineering Peking University Advanced Research Institute for Multidisciplinary Science Beijing Institute of Technology The State Key Lab of Explosion Science and Technology Beijing Institute of Technology Centre for Applied Physics and Technology (CAPT) Peking University

we further consider the effect of rod strength by employing the compressible penetration model to study the effect of compressibility on hypervelocity ***, we define different instances of penetration efficiency in various modified models and compare these penetration efficiencies to identify the effects of different factors in the compressible model. To systematically discuss the effect of compressibility in different metallic rod-target combinations, we construct three cases, i.e., the penetrations by the more compressible rod into the less compressible target, rod into the analogously compressible target, and the less compressible rod into the more compressible target. The effects of volumetric strain, internal energy, and strength on the penetration efficiency are analyzed simultaneously. It indicates that the compressibility of the rod and target increases the pressure at the rod/target interface. The more compressible rod/target has larger volumetric strain and higher internal energy. Both the larger volumetric strain and higher strength enhance the penetration or anti-penetration ability. On the other hand, the higher internal energy weakens the penetration or anti-penetration ability. The two trends conflict, but the volumetric strain dominates in the variation of the penetration efficiency, which would not approach the hydrodynamic limit if the rod and target are not analogously compressible. However, if the compressibility of the rod and target is analogous, it has little effect on the penetration efficiency.

关键词： Compressibility Hypervelocity penetration Equation of state(EOS) Shockwave Bernoulli equation

Vlultifunctional immune responses of HMBPP-specific Jy2Vδ2 T cells in M. tuberculosis and other infections

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Cellular & Molecular Immunology 2013年第1期10卷 58-64页

作者： Zheng w chen Department of Microbiology and Immunology Center for Primate Biomedical Research University of Illinois College of Medicine Chicago chicago IE 60612: USA

Vy2Vδ2 T （also known as Vy9Vδ2 T） cells exist only in primates, and in humans represent a major yδ T-cell sub-population in the total population of circulating yδ T cells. Results from recent studies suggest that while （E）-4-hydroxy-3-methyl-but-2-enyl pyrophosphate （HMBPP） phosphoantigen from Mycobacterium tuberculosis （Mtb） and other microbes activates and expands primate Vy2Vδ2 T cells, the Vy2Vδ2 T-cell receptor （TCR） recognizes and binds to HMBPP on antigen-presenting cells （APC）. In response to HMBPP stimulus, Vy2V82 TCRs array to form signaling-related nanoclusters or nanodomains during the activation of Vy2V82 T cells. Primary infections with H MBPP-producing pathogens drive the evolution of multieffector functional responses in Vy2Vδ2 T cells, although Vy2V82 T cells display different patterns of responses during the acute and chronic phases of Mtb infection and in other infections. Expanded Vy2Vδ2 T cells in primary Mtb infection can exhibit a broader TCR repertoire and a greater clonal response than previously assumed, with different distribution patterns of Vδ,2Vδ2 T-cell clones in lymphoid and non-lymphoid compartments. Emerging in vivo data suggest that HMBPP activation of Vy2w2 T cells appears to impact other immune cells during infection.

关键词： (E)-4-hydroxy-3-methyl-but-2-enyl pyrophosphate yδ T cell HMBPP human infection phosphoantigen T cell receptor T-cell response tuberculosis

Process of Photoluminescence and Photostimulated Luminescence in BaFBr:Eu Phosphors

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Journal of Materials Science & Technology 1995年第5期11卷 388-390页

作者： chen, w SU, MZ BEIJING UNIV DEPT CHEM BEIJING 100871 PEOPLES R CHINA

The photoluminescence (PL) and photostimulated luminescence (PSL) of BaFBr: Eu phosphors are reported. In the photoluminescence of BaFBr:Eu, the emission of Eu2+, e-h recombination and Eu3+ have been observed, while in the photostimulated luminescence only the emission of Eu2+ was observed. This phenomenon may be explained well by the suggestion of a two-hand model for the host emission in which the host emission energy may transfer to Eu2+ difference of excitation in those two processes results in different transfer rates which makes the PL and PSL emission different.

关键词： Phosphors

Analysis on the velocity relationship and deceleration of long-rod penetration

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Acta Mechanica Sinica 2019年第4期35卷 852-865页

作者： w.J.Jiao X.w. chen Department of Modern Mechanics University of Science and Technology of China Hefei230027 China Institute of Systems Engineering China Academy of Engineering Physics Mianyang621999 China The State Key Lab of Explosion Science and Technology Beijing Institute of Technology Beijing100081 China Advanced Research Institute of Multidisciplinary Science Beijing Institute of Technology Beijing 100081 China

The relationship between the average penetration velocity,UˉUˉ,and the initial impact velocity, V0V0,in long-rod penetration has been studied recently. Experimental and simulation results all show the linear relationship between UˉUˉ and V0V0 over a wide range of V0V0 for different combinations of rod and target materials. However, the physical essence has not been fully *** this paper, the Uˉ?V0Uˉ?V0relationship is profoundly analyzed using hydrodynamic model and Alekseevskii-Tate model. Especially, the explicitUˉ?V0Uˉ?V0 relationships are derived fromapproximate solutions of Alekseevskii-Tate model. Besides, the decelerationin long-rod penetration is discussed. The decelerationdegree is quantified by adeceleration index,α=2μˉ/(KΦJp)≈Ypρ?1/2p(ρ?1/2p+ρ?1/2t)V?20α=2μˉ/(KΦJp)≈Ypρp?1/2(ρp?1/2+ρt?1/2)V0?2, which is mostly related to the impact velocity, rod strength and rod/target densities. Thus, the state of penetration process can be identified and designed in experiments.

关键词： Long-rod penetration Average penetration velocity Initial impact velocity Alekseevskii-Tate model Deceleration

Approximate solutions of the Alekseevskii–Tate model of long-rod penetration

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Acta Mechanica Sinica 2018年第2期34卷 334-348页

作者： w.J.Jiao X.w.chen Department of Modern Mechanics University of Science and Technology of China Institute of Systems Engineering China Academy of Engineering Physics Advanced Research Institute for Multidisciplinary Science Beijing Institute of Technology The State Key Lab of Explosion Science and Technology Beijing Institute of Technology

The Alekseevskii–Tate model is the most successful semi-hydrodynamic model applied to long-rod penetration into semi-infinite targets. However, due to the nonlinear nature of the equations, the rod(tail) velocity, penetration velocity, rod length, and penetration depth were obtained implicitly as a function of time and solved numerically By employing a linear approximation to the logarithmic relative rod length, we obtain two sets of explicit approximate algebraic solutions based on the implicit theoretica solution deduced from primitive equations. It is very convenient in the theoretical prediction of the Alekseevskii–Tate model to apply these simple algebraic solutions. In particular, approximate solution 1 shows good agreement with the theoretical(exact) solution, and the first-order perturbation solution obtained by walters et al.(Int. J. Impac Eng. 33:837–846, 2006) can be deemed as a special form of approximate solution 1 in high-speed penetration. Meanwhile, with constant tail velocity and penetration velocity approximate solution 2 has very simple expressions, which is applicable for the qualitative analysis of long-rod penetration. Differences among these two approximate solutions and the theoretical(exact) solution and their respective scopes of application have been discussed, and the inferences with clear physical basis have been drawn. In addition, these two solutions and the first-order perturbation solution are applied to two cases with different initial impact velocity and different penetrator/target combinations to compare with the theoretical(exact) solution. Approximate solution 1 is much closer to the theoretical solution of the Alekseevskii–Tate model than the first-order perturbation solution in both cases, whilst approximate solution 2 brings us a more intuitive understanding of quasi-steady-state penetration.

关键词： Long-rod penetration Alekseevskii–Tate model Theoretical solution Approximate solution Perturbation solution

Review of the experiments for energetic particle physics on HL-2A

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Plasma Science and Technology 2018年第9期20卷 93-105页

作者： X T DING w chen Southwestern Institute of Physics Chengdu 610041People＇s Republic of China

This paper reviews the energetic particle（EP） experiments during electron cyclotron resonance heating（ECRH） and neutral beam injection in the HL-2 A tokamak.A number of important results are summarized,which relate to ITER physics,including the behavior of the multi-mode instability,the nonlinear interaction between wave-wave and wave-particles,the losses of EP induced by the instabilities,the effect of the EP instabilities on the thermal plasma confinement and the control of the EP instabilities by means of *** experiments indicate that when the drive is great enough,the nonlinear effects and the multi-mode coexistence may play an important role,which affect the transport both of the EPs and the background plasma confinement,and these instabilities could be *** new phenomena about the EP induced instabilities discovered recently on the device,such as high frequency reversed shear Alfvén eigenmodes,Alfvénic ion temperature gradient modes,the geodesic acoustic mode induced by energetic electrons excited by interaction between tearing mode and beta induced Alfvén eigenmode and double e-fishbone in negative magnetic shear discharges etc,have also been presented in the paper.

关键词： HL-2A tokamak energetic particle Alfven eigenmode plasma confinement

The crucial roles of Th17-related cytokines/signal pathways in M. tuberculosis infection

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Cellular & Molecular Immunology 2018年第3期15卷 216-225页

作者： Hongbo Shen Zheng w chen Unit of Anti-tuberculosis Immunity CAS Key Laboratory of Molecular Virology and ImmunologyInstitut Pasteur of ShanghaiChinese Academy of SciencesShanghai200031China Department of Microbiology and Immunology and Center for Primate Biomedical Research University of Illinois College of MedicineChicago60612ILUSA

Interleukin-17(IL-17),IL-21,IL-22 and IL-23 can be grouped as T helper 17(Th17)-related cytokines because they are either produced by Th17/Th22 cells or involved in their ***,we review Th17-related cytokines/Th17-like cells,networks/signals and their roles in immune responses or immunity against Mycobacterium tuberculosis(Mtb)*** studies suggest that Th17-related cytokine pathways may be manipulated by Mtb microorganisms for their survival benefits in primary tuberculosis(TB).In addition,there is evidence that immune responses of the signal transducer and activator of transcription 3(STAT3)signal pathway and Th17-like T-cell subsets are dysregulated or destroyed in patients with ***,Mtb infection can impact upstream cytokines in the STAT3 pathway of Th17-like *** on these findings,we discuss the need for future studies and the rationale for targeting Th17-related cytokines/signals as a potential adjunctive treatment.

关键词： immunotherapy miRNA STAT Th17-related cytokines

Spherical cavity-expansion model for penetration of reinforced-concrete targets

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Acta Mechanica Sinica 2019年第4期35卷 535-551页

作者： Y.J.Deng w.J.Song X.w.chen Institute of Systems Engineering China Academy of Engineering PhysicsP.O.Box 919-416Mianyang 621999China Shock and Vibration of Engineering Materials and Structures Key Laboratory of Sichuan Province Mianyang 621000China Department of Civil Engineering and Architecture Southwest University of Science and TechnologyMianyang 621000China Department of Mechanics and Engineering Science College of EngineeringPeking UniversityBeijing 100871China Advanced Research Institute for Multidisciplinary Science Beijing Institute of TechnologyBeijing 100081China State Key Lab of Explosion Science and Technology Beijing Institute of TechnologyBeijing 100081China

The feature of reinforcing bars is introduced into dynamic cavity-expansion theory. Based on the elastic-plastic response penetration model of plain (i.e., unreinforced) concrete (Forrestal and Tzou, 1997), a dynamic spherical cavity-expansion penetration model for reinforced-concrete targets is developed with consideration of the circumferential restriction effect derived from reinforcing bars in the crushed region. The theoretical solution and simplified calculation formula for the cavity radial stress in incompressible and compressible reinforced concrete are obtained by introducing a reinforcement ratio as the volume fraction of rebars in the concrete target. A damping function is presented to describe the restriction effect of a single layer of reinforcing bars on the surrounding concrete, thus establishing a model to calculate the penetration resistance of multilayer reinforced-concrete targets. Compared with test data for the penetration depth, this model considering the circumferential restriction effect produces better results compared with the existing theory.

关键词： Dynamic cavity-expansion theory Reinforced concrete Penetration resistance Reinforcement ratio

Neutrophils, reverse traffic and detrimental potential

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Cellular & Molecular Immunology 2012年第2期9卷 99-100页

作者： Gucheng Zeng Zheng w. chen Department of Microbiology Zhongshan School of Medicine Sun Yat-sen University Guangzhou China ahd Department of Microbiology and immunology Center for Primate Biomedical Research University of Illinois College of Medicine Ch cago L USA

Transmigration of leukocytes through venular walls into the inflamed tissues plays a central role in innate immune res- ponses against infection or injury. Trans- endothelial migration （TEM） was widely believed to be the final step in the process of leukocyte emigration into inflamed tissues. Leukocyte TEM is driven by large-scale, comlicated molecular interactions that allow leukocyte TEM to occur with minimal disruption to the complex and delicate structures of vessel walls.1,2 However, the molecu- lar mechanisms underlying the leukocyte

关键词： Neutrophils reverse traffic potential