原子核~(145)Tb的多准粒子激发态

利用能量为165 MeV的32S束流, 通过反应118Sn(32S, 1p4n)布居了145Tb的高自旋态. 基于标准在束核谱学实验测量结果, 首次建立了激发能高达 7.4 MeV的145Tb能级纲图. 145Tb的能级结构具有球形原子核的特征, 其高自旋态是由单粒子激发形成的. 根据邻近N = 80同中子素核结构的系统性, 采用一个11/2h价质子与偶偶核芯144Gd的弱耦合很好地解释了145Tb激发能在2 MeV以下的能级结构. 利用多准粒子壳模型组态解释了激发能在2 MeV以上的晕态和部分近晕态能级.

~(145)Tb的高自旋态能级纲图

利用能量为 1 61— 1 75MeV的32 S束流 ,通过反应118Sn( 32 S ,1p4n)产生了145 　Tb的高自旋态 .进行了γ射线的激发函数、γ γ t符合测量 .首先建议了由 2 4条能级和 4 2条γ跃迁组成的145 Tb核的能级纲图 ,并指定了各条能级的自旋值及部分低位能级的宇称 .用一个πh11/ 2 价质子与144 Gd核芯激发态的耦合定性地解释了145 Tb的一些低位激发态

Experimental study of the beta-delayed proton decays of Er-145,Er-147

The beta-delayed proton decays of Er-145,Er-147 have been studied experimentally using the Ni-58 + Mo-92 reaction at beam energy of 383 MeV. On the basis of a He-jet apparatus coupled with a tape transport system, the beta-delayed proton radioactivities both from the nu s(1/2) ground state and the nu h(11/2) isomer in Er-145,Er-147 were observed by proton-gamma coincidence measurements. By analyzing the time distributions of the 4(+) -> 2(gamma)(+) transitions in the granddaughter nuclei Dy-144,Dy-146, the half-lives of 1.0 +/- 0.3 s and 1.6 +/- 0.2 s have been deduced for the nu h(11/2) isomers in Er-145,Er-147, respectively.

~(145)Er的β延发质子衰变性质研究；Properties of β-delayed Proton Decay of ~(145)Er

通过92Mo(58Ni,2p3n)熔合蒸发反应生成了非常缺中子核145Er。利用氦喷嘴带传输系统把研究目标核传输到低本底测量站,进行了质子-γ符合测量,得到了不受同量异位素干扰的145Er的β延发质子谱。经过仔细分析与延发质子符合的γ谱,发现了145Er的11/2-同核异能态具有β延发质子衰变性质。经拟合退激144Dy不同激发态γ跃迁的衰变曲线,得出145Er的1/2+基态和11/2-同核异能态的半衰期分别为(1.6±0.6)和(0.6±0.1)s。最后,简单介绍了中重质量区缺中子新核素的合成及衰变研究计划。

Increasing Critical Sensitivity of the Load/Unload Response Ratio before Large Earthquakes with Identified Stress Acclumulation Pattern

The Load/Unload Response Ratio (LURR) method is proposed for short-to-intermediate-term earthquake prediction [Yin, X.C., Chen, X.Z., Song, Z.P., Yin, C., 1995. A New Approach to Earthquake Prediction — The Load/Unload Response Ratio (LURR) Theory, Pure Appl. Geophys., 145, 701–715]. This method is based on measuring the ratio between Benioff strains released during the time periods of loading and unloading, corresponding to the Coulomb Failure Stress change induced by Earth tides on optimally oriented faults. According to the method, the LURR time series usually climb to an anomalously high peak prior to occurrence of a large earthquake. Previous studies have indicated that the size of critical seismogenic region selected for LURR measurements has great influence on the evaluation of LURR. In this study, we replace the circular region usually adopted in LURR practice with an area within which the tectonic stress change would mostly affect the Coulomb stress on a potential seismogenic fault of a future event. The Coulomb stress change before a hypothetical earthquake is calculated based on a simple back-slip dislocation model of the event. This new algorithm, by combining the LURR method with our choice of identified area with increased Coulomb stress, is devised to improve the sensitivity of LURR to measure criticality of stress accumulation before a large earthquake. Retrospective tests of this algorithm on four large earthquakes occurred in California over the last two decades show remarkable enhancement of the LURR precursory anomalies. For some strong events of lesser magnitudes occurred in the same neighborhoods and during the same time periods, significant anomalies are found if circular areas are used, and are not found if increased Coulomb stress areas are used for LURR data selection. The unique feature of this algorithm may provide stronger constraints on forecasts of the size and location of future large events.

Molecular dynamics simulation of hydrogen enhancing dislocation emission

The interactive pair potential between Al and H is obtained based on the ab initio calculation and the Chen-Mobius 3D lattice inversion formula. By utilizing the pair potentials calculated, the effects of hydrogen on the dislocation emission from crack tip have been studied. The simulated result shows that hydrogen can reduce the cohesive strength for Al single crystal, and then the critical stress intensity factor for partial dislocation emission decreases from 0.11 MPa root m (C-H = 0) to 0.075 MPa root m (C-H=0.72%) and 0.06 MPa root m (C-H = 1.44%). This indicates thar hydrogen can enhance the dislocation emission. The simulation also shows that atoms of hydrogen can gather and turn into small bubbles, resulting in enhancement of the equilibrium vacancy concentration.

Dynamic function of damage and its implications

Dynamic function of damage is the key to the problem of damage evolution of solids. In order to understand it, one must understand its mesoscopic mechanisms and macroscopic formulation. In terms of evolution equation of microdamage and damage moment, a dynamic function of damage is strictly defined. The mesoscopic mechanism underlying self-closed damage evolution law is investigated by means of double damage moments. Numerical results of damage evolution demonstrate some common features for various microdamage dynamics. Then, the dynamic function of damage is applied to inhomogeneous damage field. In this case, damage evolution rate is no longer equal to the dynamic function of damage. It is found that the criterion for damage localization is closely related to compound damage. Finally, an inversion of damage evolution to the dynamic function of damage is proposed.

Some advances in study of crack identification problems

In the present paper, the crack identification problems are investigated. This kind of problems belong to the scope of inverse problems and are usually ill-posed on their solutions. The paper includes two parts: (1) Based on the dynamic BIEM and the optimization method and using the measured dynamic information on outer boundary, the identification of crack in a finite domain is investigated and a method for choosing the high sensitive frequency region is proposed successfully to improve the precision. (2) Based on 3-D static BIEM and hypersingular integral equation theory, the penny crack identification in a finite body is reduced to an optimization problem. The investigation gives us some initial understanding on the 3-D inverse problems.

实时TV光电子全息散斑干涉仪及其在折射率场中的应用

介绍了一种不需PC微机支持图象卡的实时TV光电子全息散斑干涉仪,成功地应用于折射率流场的显示定量测量,并给出了实验结果。

自动跟踪式同步机在高速摄影中的应用

<正> 自动跟踪式同步机是一种新型的多功能计时、延时仪器。它可以对μs精度测量和显示被测时间间隔,并根据测量值自动跟踪被摄对象,以±0.2μs的精度输出多路延时讯号,解决各种高速摄影中的同步问题。它具有极强的抗干扰能力,可以在放电电压1MV,放电电流10KA,空间电磁场5KV/m的强电磁干扰的恶劣条件下正常工作。

国内非牛顿流体力学进展

非牛顿流体;;本构方程;;流变测量;;流动稳定性;;收缩流动;;聚合物加工;;石油工业;;生物流体力学