~(206)At的[лh_(1/2)vi_(13/2)~(-1)]10~-同质异能态研究(英文)

利用能量为６０－８０ＭｅＶ的~(１２)Ｃ束流，通过~１９７Ａｎ（~(１２)Ｃ，３ｎ）~２０６Ａｔ反应研究了~２０６Ａｔ核的高自旋能级结构．用７台ＢＧＯ（ＡＣ）ＨＰＧｅ探测器和一台用于探测低能γ射线的平面型ＨＰＧｅ探测器进行了γ射线的激发函数、γ－γ－ｔ符合及γ射线的角分布测量．基于这些测量，首次建立了包括２５条γ跃迁的~２０６Ａｔ高自旋能级纲图．确定了一个半寿命为（９０８±４００）ｎｓ、自旋和宇称为１０的同质异能态．基于较重的双奇核~(２０８，２１０ )Ａｔ能级结构的系统性，对~(２０６)Ａｔ的１０~－同质异能态进行了讨论．

An experimental study of the influence of weak convection on perikinetic coagulation

A remarkably increased coagulation rate for 2-mu m PS spheres was previously reported for a perikinetic coagulation experiment performed under microgravity conditions (1998, R. Folkersma, A. J. G. van Diemen, and H. N. Stein, J. Colloid Interface Sci. 206, 482); from this experiment, it was assumed that the leading factor slowing the coagulation process under normal gravitation was free convection due to gravity (1998, R. Folkersma, and H. N. Stein, J. Colloid Interface Sci. 206, 494). To test the influence of free convection as a single-effect factor on the coagulation process, a ground-based experiment was constructed. The coagulation rate of 2-mu m PS spheres dispersed in water was determined by measuring the turbidity of the dispersion solution while convection-driven flows in the solution were checked with a visual magnification system. We found that it was possible to cease free convection-driven particle flows on the ground, as long as the experiments were carefully operated. The strength of convection was controlled by changing the temperature gradient applied to the sample cell. By monitoring both the coagulation rate and convection-driven flows simultaneously, our experiments showed that weak free convection (maximum speed <150 mu m/s) actually has negligible effects on the coagulation rate.

Determination Ofinterfacial Mechanical Parameters For An Al/Epoxy/Al2O3 System Byusing Peel Test Simulations

Peel test measurements and simulations of the interfacial mechanical parameters for the Al/Epoxy/Al2O3 system are performed in the present investigation. A series of Al film thicknesses between 20 and 250 microns and three peel angles of 90, 135 and 180 degrees are considered. Two types of epoxy adhesives are adopted to obtain both strong and weak interface adhesions. A finite element model with cohesive zone elements is used to identify the interfacial parameters and simulate the peel test process. By simulating and recording normal stress near the crack tip, the separation strength is obtained. Furthermore, the cohesive energy is identified by comparing the simulated steady-state peel force and the experimental result. It is found from the research that both the cohesive energy and the separation strength can be taken as the intrinsic interfacial parameters which are dependent on the thickness of the adhesive layer and independent of the film thickness and peel angle.

Two-phase flow patterns in a 90 degrees bend at microgravity

Bends are widely used in pipelines carrying single- and two-phase fluids in both ground and space applications. In particular, they play more important role in space applications due to the extreme spatial constraints. In the present study, a set of experimental data of two-phase flow patterns and their transitions in a 90degrees bend with inner diameter of 12.7 mm. and curvature radius of 76.5 mm at microgravity conditions are reported. Gas and liquid superficial velocities are found to range from (1.0 similar to 23.6) m/s for gas and (0.09 similar to 0.5) m/s for liquid, respectively. Three major flow patterns, namely slug, slug-annular transitional, and annular flows, are observed in this study. Focusing on the differences between flow patterns in bends and their counterparts in straight pipes, detailed analyses of their characteristics are made. The transitions between adjoining flow patterns are found to be more or less the same as those in straight pipes, and can be predicted using Weber number models satisfactorily. The reasons for such agreement are carefully examined.

圆柱运动的内波渐近解

本文提供一个二维内波的渐近解法,对水平圆柱在无粘、稳定的密度连续分层流体中任意倾角运动的问题,得到了伴随的色散关系式,结合倾角α=90°圆柱垂直运动情况,给出了圆柱面上的边界条件和无穷远衰减条件。用渐近展开的方法求出內波的渐近解;对内波传布的规律作了讨论并与內波流场显示结果进行了比较,计算结果合理,运用本解法可望在求解分层流体中圆柱任意方向运动的问题,其它形状物体分层绕流的内波问题、非定常色散以及三维的内波问题中得到推广应用。

变截面管道中爆轰胞格演变机制的数值模拟研究

应用频散可控耗散格式和基元化学反应模型模拟了二维爆轰波在变截面管道中的传播过程;研究了由于流动压缩和膨胀的影响,近壁面区域爆轰波横波和胞格的演变规律;通过分析爆轰波后气体组分变化、化学反应速率、反应区尺度和热力学参数,探讨了两种异常爆轰波的传播机制及其化学反应、反射激波和稀疏波在这些异常爆轰波发展和胞格演化过程的作用.

单向海流载荷下海底管道局部冲刷试验研究

采用量纲分析法建立了海底管道局部冲刷的相似准则，利用模型实验研究了管道局部冲刷的物理过程，以及极限平衡冲刷深度的影响因素。实验观测发现，对于初始嵌入深度较小的管道而言，局部冲刷一般可分为管道悬空、间隙冲刷、尾迹冲刷和平衡冲刷四个特征阶段。在亚临界流动范围内，管道极限平衡冲刷深度与雷诺数的相关性较小。在清水冲刷条件下，无量纲极限平衡冲刷深度随希尔兹数的增加而增大；在所研究的初始间隙比范围内（-0．25〈e_0／D〈0．55），极限平衡冲刷深度与初始间隙比之间大致呈线性递减关系。

微重力蜡烛火焰特征数值模拟

建立了微重力蜡烛火焰的数学模型。计算与分析表明，火焰的形状由空气动力学特征决定，火焰是温度取决于化学反应动力学特征和火焰的热损失。在静止微重力环境中，自然对流的消失使火焰为半球形。辐射热损失对烛火焰温度（颜色）特征的形成有重要贡献，在静止重力环境下，化学反应放热速率受氧气扩散速率控制，辐射热损失的冷却使火焰温度低于正常重力温度值。但当环境气体的流动速度加大时，辐射热损失的影响逐渐减小，蜡烛火焰的温度逐渐接近正常重力蜡烛火焰的温度。当氧浓度较小时，火焰峰值温度小于烟黑形成的阈值温度（1300 K）；当氧浓度较大时，火焰温度大于烟黑形成的阈值温度。

Receptivity to free-stream disturbance waves for blunt cone axial symmetry hypersonic boundary layer

Based on high-order compact upwind scheme, a high-order shock-fitting finite difference scheme is studied to simulate the generation of boundary layer disturbance waves due to free-stream waves. Both steady and unsteady flow solutions of the receptivity problem are obtained by resolving the full Navier-Stokes equations. The interactions of bow-shock and free-stream disturbance are researched. Direct numerical simulation (DNS) of receptivity to free-stream disturbances for blunt cone hypersonic boundary layers is performed.

Energy Functions And Basic Equations For Ferroelectrics

Energy functions (or characteristic functions) and basic equations for ferroelectrics in use today are given by those for ordinary dielectrics in the physical and mechanical communications. Based on these basic equations and energy functions, the finite element computation of the nonlinear behavior of the ferroelectrics has been carried out by several research groups. However, it is difficult to process the finite element computation further after domain switching, and the computation results are remarkably deviating from the experimental results. For the crack problem, the iterative solution of the finite element calculation could not converge and the solutions for fields near the crack tip oscillate. In order to finish the calculation smoothly, the finite element formulation should be modified to neglect the equivalent nodal load produced by spontaneous polarization gradient. Meanwhile, certain energy functions for ferroelectrics in use today are not compatible with the constitutive equations of ferroelectrics and need to be modified. This paper proposes a set of new formulae of the energy functions for ferroelectrics. With regard to the new formulae of the energy functions, the new basic equations for ferroelectrics are derived and can reasonably explain the question in the current finite element analysis for ferroelectrics.

Exchange energy shifts under dense plasma conditions

The variation of the energy interval between the intercombination line ( 1s2p(P-3(1))-> 1s(2)) and the resonance line ( 1s2p(P-1(1))-> 1s(2)) of He-like aluminium with plasma density and temperature is investigated. Since such energy interval is equivalent to the exchange energy of the state 1s2p(P-3(1)), we consider the dependence of this energy shift on the plasma environment. It was found that the shifts of exchange energy increase ( decrease) with the increase of electron density ( electron temperature), and the shifts of exchange energy become more sensitive to the electron density as the electron temperature decreases, i. e. in the strongly coupled plasma regime. An approximately linear relation is found between the shifts of exchange energy and the electron density. The results show that dense plasma effects are very important for the simulation of the spectral fine structure. The relative shifts between the intercombination ( 1s2p(P-3(1))-> 1s(2)) and the resonance line ( 1s2p(P-1(1))-> 1s(2)) are discussed for diagnostic applications.

高重复率窄脉宽Nd∶YVO_4板条激光器

部分端面抽运的混合腔板条激光器是一种新型的全固态激光器,采用这种结构,实现了高重复率调Q运转。在脉冲抽运情况下,1kHz运转时,得到脉宽4.6ns,单脉冲能量4.5mJ的激光输出。在连续抽运调Q输出情况下,5kHz高重复率运转时,获得了脉宽6ns,单脉冲能量3.1mJ的脉冲序列输出,平均功率超过15W;当重复率高达25kHz时,得到脉宽9.5ns,单脉冲能量1.2mJ的激光输出,平均功率达30W。实验结果表明,输出水平还有很大的提升空间。