Two-dimensional potential energy function for internal rotation in 1,2-dihydroxybenzenes

We have obtained an analytical expression for the two-dimensional potential energy function for internal rotation in 1,2-dihydroxybenzenes, allowing us to use perturbation theory methods to calculate and interpret the torsional spectra of these compounds. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 1, pp. 133–136, January–February, 2006.     

Responses of a non-linearly coupled pitch-roll ship model under harmonic excitation

Stationary responses of nonlinearly coupled pitch and roll ship modes are studied using a modified averaging method, along with two second order multiple time scale (MTS) methods for comparison. Stability of the solutions is also studied. In the case of harmonic excitation all the three methods give fairly accurate results to the original problem but the averaging method is the most efficient. Analytic solutions are obtained from the averaged equations, which can be used to predict stationary responses both for small and for large excitations. From the averaging method several qualitatively different phenomena which cannot be addressed by the first order theory have been obtained: (i) the saturation phenomenon is lost, (ii) the bifurcation points are altered and (iii) a drift term is present which, although small, appears to have a significant effect on the accuracy of the solutions.     

Natural radioactivity in marble stones- Jordan

Natural radioactivity has been measured in marble stone samples collected from Dabaa'h, Ajloun and Azrak areas using a gamma spectroscopy technique. The measured ²²⁶Ra activities in the stones collected from Dabaa'h quarries varied from 264.9 Bq kg⁻¹ to 369.5 Bq kg⁻¹. In samples from Ajloun and Azrak the maximum values of ²²⁶Ra were 28.3 Bq kg⁻¹ and 23.41 Bq kg⁻¹, respectively. The measured values of ²³²Th were less than 17.89 Bq kg⁻¹. The average values of the radium equivalent activities as well as external and internal hazard indices were also calculated. It was observed that for marble stones from Dabaa'h area, estimated average value of the external hazard index is 0.873 and that of internal hazard index is 1.71.     

Risk aversion and optimal forest replanting: A stochastic efficiency study

A new stochastic efficiency analysis approach, called stochastic efficiency with respect to a function (SERF), is applied to analyse optimal tree replanting on an area of recently harvested forest land. SERF partitions a set of risky alternative tree replanting strategies in terms of certainty equivalents (CEs) for a specified range of attitudes to risk. Both the entailed risk and the forest owner’s risk aversion are taken into account. The forest owner’s degree of risk aversion affects both the optimal tree replacement strategy and the reinvestment decision. The degree of risk aversion also needs to be taken into account when designing policy measures to affect forest investment.     

3种动态分析法用于多方案比较的研究

介绍了用于多方案比较的 3种动态分析法的原理及应用 ,从数学上证明了利用这三种方法进行方案比较所得的结论之间的关系 .     

团簇碰撞中的相对转动研究

采用距离相关紧密束缚的分子动力学模型,研究了在不同碰撞能量以及不同的碰撞参数下,碱金属团簇碰撞过程中的转动行为.研究表明,团簇碰撞中存在着较大的转动.对确定的能量,存在极值的碰撞参数,小于该碰撞参数时,转动能量随碰撞参数增加而迅速增加;大于该碰撞参数时,转动能量随碰撞参数的增加迅速减小.能量低时,相对转动弛豫时间更长;碰撞能量越大,越过势垒的能力越强,势场的相对影响就越小,由此引起的相对转动也就越小.     

偏心结构体在光学系统中的应用（一）：棱镜在光学系统中的局限性

本文从偏心本（棱镜）的角度来对光学系统性能指标，结构布局等的合理性进行判断，研究表明，光学系统的视场和结构布局决定了棱镜的造反范围，这种选择性与人瞳直径，渐晕系数，物镜焦距无关，而仅与棱镜本身参数，即所用材料，展开长度有关。     

Rotation sensitivity of Lau fringes: an analysis based on coherence theory

An analysis based on coherence theory is presented, which explains the experimentally observed rotation sensitivity of the contrast of Lau fringes obtained under spatially incoherent illumination.     

Pathlength alteration in an interferometer by rotation of a retroreflector

In optical interferometers the alteration of pathlengths is usually achieved by moving one of the two interferometer mirrors back and forth. Employing rotating retroreflectors (corner reflectors), two slightly different concepts have been developed to replace this stop and go movement by a continuous rotation.     

FLOW-INDUCED INTERNAL RESONANCES AND MODE EXCHANGE IN HORIZONTAL CANTILEVERED PIPE CONVEYING FLUID (Ⅰ)

The Newtonian method is employed to obtain nonlinear mathematical model of motion of a horizontally cantilevered and inflexible pipe conveying fluid. The order magnitudes of relevant physical parameters are analyzed qualitatively to establish a foundation on the further study of the model. The method of multiple scales is used to obtain eigenfunctions of the linear free-vibration modes of the pipe. The boundary conditions yield the characteristic equations from which eigenvalues can be derived. It is found that flow velocity in the pipe may induced the 3:1, 2:1 and 1:1 internal resonances between the first and second modes such that the mechanism of flow-induced internal resonances in the pipe under consideration is explained theoretically. The 3:1 internal resonance first occurs in the system and is, thus, the most important since it corresponds to the minimum critical velocity.