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Molecular dynamics simulation of mechanical properties of TATB/fluorine-polymer PBXs along different surfaces

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science china chemistry 2005年第6期48卷 504-510页

作者： XIAO Jijun1, HUANG Yucheng1, HU Yingjie1,2 & XIAO Heming1 1. department of chemistry, nanjing university of science and technology, nanjing 210094, china 2. department of chemistry, nanjing Xiaozhuang College, nanjing 210017, china Correspondence should be addressed to Xiao Heming (email: xiao@***) 1. department of chemistry Nanjing University of Science and Technology 210094 Nanjing China 2. department of chemistry Nanjing Xiaozhuang College 210017 Nanjing China

The mechanical properties of PBXs composed of the well-known insensitive explo-sive TATB (1,3,5-Triamino-2,4,6-trinitrobenzene) crystal and four kinds of typical fluo-rine-polymers, i.e. poly (vinylidene difluoride) (PVDF), polychlorotrifluoroethylene (PCTFE), fluo-rine rubber (F2311) and fluorine resin (F2314) individually, have been simulated by molecular dy-namics (MD) method. The results show that the mechanical properties of TATB can be effectively improved by blending with a small amount of fluorine-polymers. Different mechanical properties of PBXs are obtained by putting fluorine-polymer binders parallel to different crystalline surfaces. The whole effect of improving mechanical properties is found to be (010)?(100)>(001).

关键词： TATB, polymer bonded explosives, mechanical properties, molecular dynamics.

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science china chemistry 2004年第6期47卷 466-479页

作者： SONG Huajie1,2, XIAO Heming1 & DONG Haishan2 1. department of chemistry, nanjing university of science and technology, nanjing 210094, china 2. Institute of Chemical Materials, china Academy of Engineering Physics, Mianyang 621900, china 1. department of chemistry Nanjing University of Science and Technology 210094 Nanjing China 2. Institute of Chemical Materials China Academy of Engineering Physics 621900 Mianyang China

The symmetry-adapted perturbation theory (SAPT) that has the ability in decompo- sition of the total interaction energy into physically meaningful components is used to provide a more fundamental understanding of intermolecular forces. This work was motivated by the diffi- culty of standard SAPT in computing the intermolecular interactions for large energetic dimer systems. SAPT based on Kohn-Sham orbitals (SAPT(DFT)) proves computationally efficient for these large systems, but has been shown to perform poorly for interaction energy components. The deficiencies of SAPT(DFT) result from wrong asymptotical behaviors of commonly used exchange-correlation potentials. To remove the deficiencies, two asymptotic corrections by means of van Leeuwen and Baerends (LB) model potential and Fermi-Amaldi (FA) type potential were applied into three small test systems comprising He2, HF2 and (N2)2 and a set of larger ni- tramide dimers at several separations. The results showed that when utilizing newly developed frequency-dependent density susceptibilities (FDDS) technique for computing dispersion energy, the FA asymptotic correction is very effective to circumvent these deficiencies in SAPT(DFT) and yields a good accuracy over the LB correction. The FA corrected SAPT(DFT) approach is capa- ble of correctly predicting all the quantitative trends in binding energies for all test cases and substantially reduces computational cost as compared with the standard SAPT calculations. The successful application of the approach to nitramide dimer demonstrates that it potentially pro- vides a good means to calculate accurately intermolecular forces in larger system such as en- ergetic systems.

关键词： intermolecular interaction, density functional theory (DFT), symmetry adapted perturbation theory (SAPT), asymptotic correction, frequency-dependent density susceptibilities (FDDS).

Molecular dynamics simulations on the structures and properties of ε-CL-20-based PBXs ——Primary theoretical studies on HEDM formulation design

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science china chemistry 2007年第6期50卷 737-745页

作者： XU XiaoJuan1,2, XIAO JiJun1, HUANG Hui3, LI JinShan3 & XIAO HeMing1 1 department of chemistry, nanjing university of science and technology, nanjing 210094, china 2 department of chemistry, Yancheng Teacher’s College, Yancheng 224002, china 3 Institute of Chemical Materials, china Academy of Engineering Physics, Mianyang 621900, china department of chemistry Nanjing University of Science and TechnologyNanjing 210094China department of chemistry Yancheng Teacher''s CollegeYancheng 224002China Institute of Chemical Materials China Academy of Engineering PhysicsMianyang 621900

Five polymer bonded explosives(PBXs)with the base explosive epsilon-CL-20(hexanitrohexaazaisowurtzi-tane),the most important high energy density compound(HEDC),and five polymer binders(Estane 5703,GAP,HTPB,PEG,and F_(2314))were *** dynamics(MD)method was employed to investigate their binding energies(E_(bind))< compatibility,safety,mechanical properties,and energetic *** information and rules were reported for choosing better binders and guiding formulation design of high energy density material(HEDM).According to the calculated binding energies,the ordering of compatibility and stability of the five PBXs was predicted as epsilon-CL-20/PEG < epsilon-CL-20/ Estane5703 ≈ epsilon-CL-20/GAP < epsilon-CL-20/HTPB < epsilon-CL-20/F_(2314).By pair correlation function g(r)analyses,hydrogen bonds and vdw are found to be the main interactions between the two *** elasticity and isotropy of PBXs based epsilon-CL-20 can be obviously improved more than pure epsilon-CL-20 *** is not by changing the molecular structures of epsilon-CL-20 for each binder to affect the *** safety and energetic properties of these PBXs are mainly influenced by the thermal capability(C_p^(deg))and density(p)of binders,respectively.

关键词： high energy density material (HEDM), hexanitrohexaazaisowurtzitane (CL-20), polymer bonded explosives (PBXs), molecular dynamics (MD), compatibility, safety properties, mechanical properties, energetic properties

Theoretical study on tetrazole and its derivatives (Ⅰ)──Ab initio study on chlorotetrazole

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Chinese science Bulletin 1998年第6期43卷 480-483页

作者： XIAO Heming, CHEN Zhaoxu and GONG Xuedong department of chemistry, nanjing university of science and technology, nanjing 210094, china

Molecular geomitries and electronic structures of four chlorotetrazoles are calculated with ab initio method at MP2/6-311G ** level. The results show that all the titled compounds are planar and aromatic. The skeletal bond lengths of the ring tend to be uniformized. Compared with 1- and 2-substituted chlorotetrazoles, 5-substituted chlorotetrazoles are more acidic and lower in total energy. 5-chloro-2H-tetrazole has the lowest energy and is the most stable.

关键词： chlorotetrazole ab initio geometry electronic structure acidity aromaticity stability.

Theoretical Study on Tetrazole and its Derivatives (5) Ab Initio Study on Nitro Derivatives of Tetrazole

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Chinese Journal of Structural chemistry 1999年第1期18卷 63-70页

作者： CHEN Zhao Xu FAN Jian Fen\ XIAO He Ming * (department of chemistry, nanjing university of science and technology, nanjing 210094, People’s Republic of china) 南京理工大学化学系江苏南京 210014

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关键词： nitrotetrazole ab initio aromaticity stability

TRANSMISSION MOMENTARY EFFICIENCY BASED ON THE D'ALEMBERT-LAGRANGE EQUATION FOR INVOLUTES GEARS

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Chinese Journal of Mechanical Engineering 2004年第2期17卷 272-275页

作者： Liang Yi Lai Changying School of Mechanical Engineering,nanjing university of science and technology,nanjing 210094, china School of Mechanical Engineering Nanjing University of Science and Technology Nanjing 210094 China department of science and technology Studies University College London WC1E 6BT UK

The D'Alembert-Lagrange equation is introduced and used to derive theformulas of momentary efficiency for external gearing of standard involutes spur gears. The gearingswith correct and increased center distance are discussed. The momentary efficiency formula iscalculated and analyzed using software Matlab. The derived formula of momentary efficiency is alsocompared with the traditional formula.

关键词： D'Alembert-Lagrange equation Involutes gear Momentary efficiency

CORRELATION BETWEEN STRESS COMPONENTS AND STRESS CORROSION CRACKS IN BRASS Lecturer,department of Materials Physics,university of science and technology Beijing,Beijing 100083,china

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Acta Metallurgica Sinica(English Letters) 1992年第9期5卷 178-182页

作者： QIAO Lijie LIU Rui XIAO Jimei university of science and technology Beijing,Beijing,china

The effects of stress components on nucleation sites and propagation directions of stress cor- rosion cracks in brass were investigated with specimens under mode Ⅱ and mode Ⅲ loadings. The results indicated that under mode Ⅱ loading,stress corrosion cracks nucleated on the site with maximum normal stress component and propagated along the plane perpendieular to the maximum normal stress,under mode Ⅲ loading,the stress corrosion crack was not evident on the 45°plane due to the general corrosion in aqueous solution with high NH_4OH concentra- tion,while stress corroded in aqueous solution with low NH_4OH concentration, numerous cracks with spacings of 10—150μm were found on the 45°plane with maximum normal stress and no stress corrosion cracks was observed on the plane with maximum shear stress.

关键词： stress corrosion cracking stress compoonent brass ammonia solution

A new smoothing scheme for mathematical programs with complementarity constraints

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science china Mathematics 2010年第7期53卷 1881-1890页

作者： YAN Taodepartment of Information and Computational sciences, College of science, nanjing university of science and technology, nanjing 210094, china 1. department of Information and Computational sciences College of Science Nanjing University of Science and Technology Nanjing 210094 China

In this paper, we consider a mathematical program with complementarity constraints (MPCC). We present a new smoothing scheme for this problem, which makes the primal structure of the complementarity part unchanged mostly. For the new smoothing problem, we show that the linear independence constraint qualification (LICQ) holds under some conditions. We also analyze the convergence behavior of the smoothing problem, and get some sufficient conditions such that an accumulation point of stationary points of the smoothing problems is C (M, B)-stationarity respectively. Based on the smoothing problem, we establish an algorithm to solve the primal MPCC problem. Some numerical experiments are given in the paper.

关键词： mathematical program with complementarity constrains MPEC-LICQ B-stationarity C-stationarity M-stationarity

Three-dimensional investigation of velocity skin effect in U-shaped solid armature

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Progress in Natural science:Materials International 2008年第12期18卷 1565-1569页

作者： Xin Li~a Chunsheng Weng~b a School of Power Engineering,nanjing university of science and technology,nanjing 210094,china b National Key Laboratory of Transient Physics,nanjing university of science and technology,nanjing 210094,china [a]School of Power Engineering Nanjing University of Science and Technology Nanjing 210094 China [b]National Key Laboratory of Transient Physics Nanjing University of Science and Technology Nanjing 210094 China

A three-dimensional transient computational model is applied to investigate the velocity skin effect (VSE) in a U-shaped solid arma- *** this model,current and heat transport in the armature can be evaluated *** results show a local concentration of current and joule heating at the interface,and significant damage occurs at the edges of the *** is also observed that there is significant enhanced heating at sharp comers because of the armature *** three-dimensional model can efficiently capture the salient features of the physical phenomena at the rail-armature interface,and contribute to the development of the armature design.

关键词： Electromagnetic launch Railgun U-shaped armature Velocity skin effect Erosion