Generalization of Response Number for Dynamic Plastic Response of Shells Subjected to impulsive Loading

A dimensionless number, termed as response number in Zhao [Archive of Applied Mechanics 68 (1998) 524], has been suggested for the dynamic plastic response of beams and plates made up of rigidly perfect plastic materials subjected to dynamic loading. Many theoretical and experimental results can be reformulated into new concise forms with the response number. The concept of a new dimensionless number, response number, termed as Rn(n), is generalized in Zhao [Forschung im Ingenieurwesen 65 (1999) 107] to study the elastic, plastic, dynamic elastic as well as dynamic plastic buckling problems of columns, plates as well as shells. The response number Rn(n) is generalized to the dynamic behaviour of shells of various shapes in the present paper.

Micromechanics Modeling Of Strength For Nanocrystalline Copper

We present a model in this paper for predicting the inverse Hall-Petch phenomenon in nanocrystalline (NC) materials which are assumed to consist of two phases: grain phase of spherical or spheroidal shapes and grain boundary phase. The deformation of the grain phase has an elasto-viscoplastic behavior, which includes dislocation glide mechanism, Coble creep and Nabarro-Herring creep. However the deformation of grain boundary phase is assumed to be the mechanism of grain boundary diffusion. A Hill self-consistent method is used to describe the behavior of nanocrystalline pure copper subjected to uniaxial tension. Finally, the effects of grain size and its distribution, grain shape and strain rate on the yield strength and stress-strain curve of the pure copper are investigated. The obtained results are compared with relevant experimental data in the literature.

Sediment sources and the flood record from Wanghu lake, in the middle reaches of the Yangtze River

A sediment core was collected from the centre of Wanghu Lake, in the Middle Reaches of the Yangtze River. The recent part of the core was dated using a combination of Pb-210 and spheroidal carbonaceous particle (SCP) techniques. Extrapolating this chronology dated the laminated section of the core, between 723 and 881 mm, to the first half of the 18th century and this section was selected for detailed study. The thicknesses of the laminae were measured using reflecting and polarizing microscopes whilst geochemistry was determined by an electron probe. The thickness of the dark layers was found to be positively correlated with titanium concentrations, and negatively correlated with aluminium and potassium concentrations. The thickness of the light layers was found to be negatively correlated with the concentrations of titanium. It is concluded that the dark layers were deposited from the Fushui River, a tributary of the Yangtze River, under periods of normal flow whilst the light Layers were mainly deposited from the Yangtze River itself during flood periods. Documentary evidence for floods occurring in the take catchment corresponded with thick laminations of high titanium concentration. Further, two of the three thickest, light laminations with low titanium concentrations were found to be synchronous with recorded flood dates of the main Yangtze River in its Middle Reaches, but one was synchronous with a local drought. These data suggest that the Lake sediment provides an archive of the relative water levels of the Yangtze and Wanghu including floods of both the main Yangtze River and the local hydrological regime. (c) 2006 Elsevier B.V. All rights reserved.

激光器和电吸收调制器的动态特性研究

Submitted by 阎军 (yanj@red.semi.ac.cn) on 2010-04-07T05:18:29Z No. of bitstreams: 1 博士论文哈森其其格：激光器和电吸收调制器的动态特性研究.pdf: 4109731 bytes, checksum: ebddabbb486d40eacc004f166b1c1365 (MD5)

Influence of ZnS and MgO Shell on the Photoluminescence Properties of ZnO Core/Shell Nanowire

Chinese Academy of Sciences；National Science Fund for Distinguished Young Scholar 60925016；National High Technology Research and Development program of China 2009AA034101；Postdoctoral Foundation 0971050000

低维体系中的量子相变及其研究方法

Submitted by 阎军 (yanj@red.semi.ac.cn) on 2010-04-07T09:01:44Z No. of bitstreams: 1 10001_200718013607017李彦超_paper.pdf: 8237052 bytes, checksum: a2e86438d84113ac36c0cc7302649834 (MD5)

神经接口专用集成电路

Submitted by 阎军 (yanj@red.semi.ac.cn) on 2010-04-07T08:58:22Z No. of bitstreams: 1 张旭论文电子版.pdf: 6590471 bytes, checksum: 9df3ec1aca65041f5b463108f6258d11 (MD5)

Fe 和(Ga,Cr)As 薄膜的分子束外延生长及磁学性质

Submitted by 阎军 (yanj@red.semi.ac.cn) on 2010-04-28T14:23:05Z No. of bitstreams: 1 鲁军_博士论文.pdf: 4237580 bytes, checksum: 3a1a5f0ea10b0895d92e102e4cdcf5d0 (MD5)

Quantum Confinement Effects and Electronic Properties of SnO2 Quantum Wires and Dots

On the basis of the density functional theory (DFT) within local density approximations (LDA) approach, we calculate the band gaps for different size SnO2 quantum wire (QWs) and quantum dots (QDs). A model is proposed to passivate the surface atoms of SnO2 QWs and QDs. We find that the band gap increases between QWs and bulk evolve as Delta E-g(wire) = 1.74/d(1.20) as the effective diameter d decreases, while being Delta E-g(dot) = 2.84/d(1.26) for the QDs. Though the similar to d(1.2) scale is significantly different from similar to d(2) of the effective mass result, the ratio of band gap increases between SnO2 QWs and QDs is 0.609, very close to the effective mass prediction. We also confirm, although the LDS calculations underestimate the band gap, that they give the trend of band gap shift as much as that obtained by the hybrid functional (PBE0) with a rational mixing of 25% Fock exchange and 75% of the conventional Perdew-Burke-Ernzerhof (PBE) exchange functional for the SnO2 QWs and QDs. The relative deviation of the LDA calculated band gap difference Lambda E-g compared with the corresponding PBE0 results is only within 5%. Additionally, it is found the states of valence band maximum (VBM) and conduction band minimum (CBM) of SnO2 QWs or QDs have a mostly p- and s-like envelope function symmetry, respectively, from both LDA and PBE0 calculations.

弱局域和Kondo 效应

Submitted by 阎军 (yanj@red.semi.ac.cn) on 2010-04-28T14:31:26Z No. of bitstreams: 1 宋小会博士后出站报告.pdf: 2964383 bytes, checksum: 7f0f018c9f3baad4363c7ea5e2547b63 (MD5)

First-principles prediction of the magnetism of 3d transition-metal-doped Rocksalt MgO

Using first-principles band structure methods, we have systematically studied the electronic structures, magnetic stabilities, and half-metal properties of 3d transition-metal (TM) doped Rocksalt MgO compounds TMMg3O4 (TM = V, Cr, Mn, Fe, Co, and Ni). The calculations reveal that only CrMg3O4 has a ferromagnetic stability among the six compounds, which is explained by double-exchange mechanism. The magnetic stability is affected by the doping concentration of TM if the top valance band is composed of partially occupied t(2g) states. In addition, CrMg3O4 is a half-metallic ferromagnet. The origins of half-metallic and ferromagnetic properties are explored. The Curie temperature (T-c) of CrMg3O4 is 182 K. And it is hard for CrMg3O4 to deform due to the large bulk modulus and shear modulus, so it is a promising spintronic material. Our calculations provide the first available information on the magnetic properties of 3d TM-doped MgO.

GaAs/InP 键合技术研究及其太阳电池应用

Submitted by 阎军 (yanj@red.semi.ac.cn) on 2010-06-07T01:06:41Z No. of bitstreams: 1 晏磊--GaAs-InP键合技术研究及其太阳电池应用.pdf: 1948545 bytes, checksum: f2c55a092591dfa48fe9063fb432559f (MD5)

A new year message from Chinese Science Bulletin

Submitted by 阎军 (yanj@red.semi.ac.cn) on 2010-04-13T14:02:33Z No. of bitstreams: 1 A new year message from Chinese Science Bulletin.pdf: 888462 bytes, checksum: 950ebfe3456fc0d42f8d058a5d2b3979 (MD5)

低维氧化锌半导体材料中的激子态

Submitted by 阎军 (yanj@red.semi.ac.cn) on 2010-06-02T02:14:34Z No. of bitstreams: 1 熊稳.pdf: 995995 bytes, checksum: 873ae572930a1e29f1b2b5dca7bc280a (MD5)

First-principles LDA plus U and GGA plus U study of neptunium dioxide

We have performed a systematic first-principles investigation to calculate the electronic structures, mechanical properties, and phonon-dispersion curves of NpO2. The local-density approximation+U and the generalized gradient approximation+U formalisms have been used to account for the strong on-site Coulomb repulsion among the localized Np 5f electrons. By choosing the Hubbard U parameter around 4 eV, the orbital occupancy characters of Np 5f and O 2p are in good agreement with recent experiments [A. Seibert, T. Gouder, and F. Huber, J. Nucl. Mater. 389, 470 (2009)]. Comparing to our previous study of ThO2, we note that stronger covalency exists in NpO2 due to the more localization behavior of 5f electrons of Np in line with the localization-delocalization trend exhibited by the actinides series.