~(126)I高自旋态的识别

利用重离子融合蒸发反应12 2 Sn(11B ,5n2p)布居了双奇核12 6 I的激发态 ,首次建立了具有集体带结构特征的能级纲图 ,其中包括 2 0条新γ跃迁 .所建能级纲图的核素归属指定得到了核反应12 4 Sn(7Li,5n)的交叉支持 .简单讨论了所建带结构的可能组态 .

~(126)Xe~(q+)轰击Al表面产生的原子和离子光谱线

报道了高电荷态离子12 6Xeq + (6≤q≤ 30 )入射到固体Al表面产生的 2 0 0～ 10 0 0nm波段的发射光谱的实验结果。实验表明 ,在弱束流 (nA量级 )高电荷态的情况下 ,通过入射离子与固体靶的相互作用可有效地产生原子和离子的复杂组态间跃迁所形成的可见光波段的特征谱线 ,而且当入射离子的电荷剥离数超过一临界值后 (对Al,q=2 6 ) ,谱线相对强度突然显著增强。根据经典过垒模型COB(Theclassicover barriermodel) ,在入射离子的动能较小 (～ 1keV/u)的条件下 ,高电荷态离子与表面相互作用过程中电子的俘获或转移起着非常重要的作用 ,通过提高入射离子的电荷态可增强入射离子俘获电子的能力 ,显著增强激发粒子的光谱线的强度。

~(126)Cs的高自旋态能级结构

利用融合蒸发反应 116Cd(14 N ,4n) 12 6Cs布居了 12 6Cs的高自旋态 .观测到了 10 0多条新的γ跃迁和相应的能级 ,建立了双奇核 12 6Cs由 9个转动带构成的能级纲图 .尝试性地指定了大部分能级的自旋和宇称以及各转动带的Nilsson单粒子组态 .极大地丰富了已有的实验结果 .

高电荷态离子~(126)Xe~(q+)与Ti固体表面作用的激发光谱

报道用 15 0keV的高电荷态离子1 2 6 Xeq + (6≤q≤ 30 )轰击Ti固体表面产生 2 0 0— 10 0 0nm波段发射光谱的实验结果 .结果显示 ,用电荷态足够高的离子作光谱激发源 ,无需很强的束流强度 (nA量级 ) ,便可激发起样品表面的原子和离子在可见光波段的特征谱线 .当入射离子剥离度q >qc≈ 2 0时 ,Ti原子及其离子的特征谱线强度突然显著增强 ;不同金属靶 ,特征谱线突然增强的qc值不同 .理论分析表明 ,这与q大于此临界值后 ,单电子转移释放能量激发靶材料传导电子气体的表面等离激元密切相关 .

Observation of negative-parity high spin states of Cs-126

The nucleus Cs-126 was investigated by means of in-beam gamma-ray spectroscopy techniques using the Nordball detector system at the Niels Bohr Institute. Excited states of Cs-126 were populated via the Cd-116(N-14, 4n)Cs-126 reaction at a beam energy of 65 MeV. The Cs-126 level scheme was considerably extended, especially at negative parity and about 40 new levels and 70 new transitions were added into the level scheme. The previously reported negative-parity rotational bands, built on pi g(7/2)circle times nu h(11/2),pi d(5/2)circle times nu h(11/2),pi h(11/2)circle times nu g(7/2), and pi h(11/2)circle times nu d(5/2) configurations, have been extended and evolve into bands involving rotationally aligned (pi h(11/2))(2) and (nu h(11/2))(2) quasiparticles. Two new rotational bands have been tentatively assigned the pi h(11/2)circle times nu s(1/2) and pi g(9/2)circle times nu h(11/2) configurations, respectively

Candidate chiral doublet bands in the odd-odd nucleus Cs-126

The candidate chiral doublet bands recently observed in Cs-126 have been extended to higher spins, several new linking transitions between the two partner members of the chiral doublet bands are observed, and gamma-intensities related to the chiral doublet bands are presented by analyzing the gamma-gamma coincidence data collected earlier at the NORDBALL through the Cd-116(N-14, 4n)Cs-126 reaction at a beam energy of 65 MeV. The intraband B(M1)/B(E2) and interband B(M1)(in)/B(M1)(out) ratios and the energy staggering parameter, S(I), have been deduced for these doublet bands. The results are found to be consistent with the chiral interpretation for the two structures. Furthermore, the observation of chiral doublet bands in Cs-126 together with those in Cs-124, Cs-128, Cs-130, and Cs-132 also indicates that the chiral conditions do not change rapidly with decreasing neutron number in these odd-odd Cesium isotopes.

Mixing process in estuaries

A theoretical expression for vertical profile-of horizontal velocity in terms of its depth-average is derived based on oscillatory boundary layer theory and estuarine flow characteristics. The derived theoretical profile is then incorporated into a vertical quasi-two-dimensional model, which is proved advantageous in more physical implications and less CPU time demand. To validate the proposed model, the calculated results are compared to the field data in the Yangtze River Estuary, exhibiting good agreement with observations. The proposed quasi-two-dimensional vertical model is used to study mixing process, especially dependence of salinity distribution and salt front strength on runoff and tides in estuaries.

深水地质和土工调查的新进展

介绍了近十年来国外在深水地质和土工调查方面取得的新进展,包括:地质调查方法;钻孔取样技术、原位试验方法以及CPT、PCPT分析理论;天然气水合物的地质调查.

Trans-Scale Mechanics: Looking For The Missing Links Between Continuum And Micro/Nanoscopic Reality

Problems involving coupled multiple space and time scales offer a real challenge for conventional frameworks of either particle or continuum mechanics. In this paper, four cases studies (shear band formation in bulk metallic glasses, spallation resulting from stress wave, interaction between a probe tip and sample, the simulation of nanoindentation with molecular statistical thermodynamics) are provided to illustrate the three levels of trans-scale problems (problems due to various physical mechanisms at macro-level, problems due to micro-structural evolution at macro/micro-level, problems due to the coupling of atoms/molecules and a finite size body at micro/nano-level) and their formulations. Accordingly, non-equilibrium statistical mechanics, coupled trans-scale equations and simultaneous solutions, and trans-scale algorithms based on atomic/molecular interaction are suggested as the three possible modes of trans-scale mechanics.

Electrochemical Impedance Spectroscopy Of Peo Coating On Aluminum Alloy In Nacl Solution

Various Plasma Electrolytic Oxidation (PEO) ceramic coatings were prepared on LY12 aluminum alloy by adjusting the concentration of sodium silicate solution. Optical microscope (OM), XRD and EIS were used to study their morphology, composition and anti corrosion behavior in NaCl solution. Increasing concentration of sodium silicate leads to the increase of the total coating thickness while too high and too low concentration lead to the decrease of inner dense layer. The main composition of PEO coatings prepared in 20, 40 and above 60g/L concentration solution are correspondingly alumina, alumina with mullite, and amorphous phase. The corrosion resistance is determined by the inner dense layer. Increasing the thickness of inner dense layer can improve the anti-corrosion performance. PEO coating's corrosion resistance in acidic, alkaline and neutral NaCl solution is proved and the corrosion mechanism involved is also discussed.

Singularity of dynamic stress fields around an interface crack between viscoelastic bodies

The singular nature of the dynamic stress fields around an interface crack located between two dissimilar isotropic linearly viscoelastic bodies is studied. A harmonic load is imposed on the surfaces of the interface crack. The dynamic stress fields around the crack are obtained by solving a set of simultaneous singular integral equations in terms of the normal and tangent crack dislocation densities. The singularity of the dynamic stress fields near the crack tips is embodied in the fundamental solutions of the singular integral equations. The investigation of the fundamental solutions indicates that the singularity and oscillation indices of the stress fields are both dependent upon the material constants and the frequency of the harmonic load. This observation is different from the well-known -1/2 oscillating singularity for elastic bi-materials. The explanation for the differences between viscoelastic and elastic bi-materials can be given by the additional viscosity mismatch in the case of viscoelastic bi-materials. As an example, the standard linear solid model of a viscoelastic material is used. The effects of the frequency and the material constants (short-term modulus, long-term modulus and relaxation time) on the singularity and the oscillation indices are studied numerically.

Computer simulation on the collision-sticking dynamics of two colloidal particles in an optical trap

Collisions of a particle pair induced by optical tweezers have been employed to study colloidal stability. In order to deepen insights regarding the collision-sticking dynamics of a particle pair in the optical trap that were observed in experimental approaches at the particle level, the authors carry out a Brownian dynamics simulation. In the simulation, various contributing factors, including the Derjaguin-Landau-Verwey-Overbeek interaction of particles, hydrodynamic interactions, optical trapping forces on the two particles, and the Brownian motion, were all taken into account. The simulation reproduces the tendencies of the accumulated sticking probability during the trapping duration for the trapped particle pair described in our previous study and provides an explanation for why the two entangled particles in the trap experience two different statuses. (c) 2007 American Institute of Physics.

优化研究所内部环境的初步尝试

<正>力学所成立已34年,目前职工总人数逾800人,是力学科学的综合性研究大所。它面临着课题分散、人员及设备老化、资金紧张、住房紧张等一系列问题。如何走出困境,如何进一步完善综合性研究大所的运转机制,在竞争中寻求自身的生存与发展,是有待深入讨论研究和急需解决的重要问题。近年来,力学所在这些方面也进行了初步的探索和尝试。一、适当调整内部科研组织结构,建立跨室联合研究集体,增强研究所的竞争力和自身发展能力力学所原有13个研究室,基本上是按力学分支学科划分建立起来的,主要研究领域包括爆炸力学、物理力学、磁流力学和等离子体动力学、土力学、高速气体动力学、流体力学、空气动力学、高温气体动力学、固体力学、激光流体物理、跨声速空气动力学、材料力学性质、微重力科

用蒙特卡罗方法研究混合物模型

本文用蒙特卡罗方法计算了五种高密度二元混合物的压缩因子,并与两种解析的混合物模型的计算值进行了比较,结果表明单液范德瓦尔斯混合物模型的计算值更接近于蒙特卡罗方法的结果。

第2届全国疲劳学术会议

<正> 中国力学学会、中国航空学会、中国机械工程学会联合召开的第2届全国疲劳学术会议,于1984年10月8—11日在四川峨眉西南交通大学举行,参加会议代表150多人,宣读和交流126篇论文,并进行了专题讨论,论文内容大致包括以下几个方面。