Brillouin scattering study on elastic and piezoelectric properties of laser irradiated ZnO single crystals

Brillouin light scattering technique can be successfully used to determine the whole set of elastic and piezoelectric constants of a ZnO single crystal irradiated by different laser energy densities, into a micron range (radiation layer thickness). It is found that the scattering intensity, the linewidth and the Brillouin scattering shift of acoustic phonons are all strongly dependent on laser energy density. Based on the sound propagation equations and these results, the directional dependences of the compressional and shear moduli of the irradiated ZnO sample in the (001) plane are investigated. It is found that under an appropriate laser condition, 248 nm KrF excimer laser irradiation can significantly improve the surface quality and increase the elastic properties of ZnO single crystal. This procedure has potential applications in the fabrication of ZnO-based surface acoustic wave and optic-electronic devices.     

Study of Partial Coefficients for Design of Semicircular Breakwaters

In the present study,the reliability design of semicircular breakwater is based on the verification of the rules defined by standard specifications,where partial coefficients are introduced to ensure safety.The reliability of the semicircular breakwaters has been analyzed by using the Hasofer-Lind method to determine the reliability index of structure that has correlated loads,utilizing the long-term observed wave data at a given place.The relation curve between reliability index and safety factor in the traditional design method,as well as the relationships between reliability index and partial coefficients,have been obtained.This paper proposes values of partial coefficients for the design expression of semicircular breakwaters in the cases of anti-sliding and anti-overturning.     

利用相关逼近法建立定位与姿态数据的同步模型

根据海道测量精密测量的需求,对姿态与定位数据融合的同步方法进行了研究。通过GPS大地高数据和升沉数据,建立了一种基于相关逼近原理的定位与姿态数据同步模型。该模型能够确定定位与姿态数据的相对延时,实现两类数据在同一时间基准下的同步。实例计算表明,定位与姿态数据的相对延迟时间已成为两类数据融合应用中必须考虑的因素。由同步模型解算后,GPS大地高数据与总升沉数据体现了更好的一致性,由此也验证了模型的有效性。     

甘肃省会宁县和定西市安定区退耕农户恩格尔系数差异

测度退耕还林农户的恩格尔系数并分析其显著影响因素及差异性,对于完善退耕还林政策、巩固退耕还林成果、改善退耕农户贫困状况具有重要的现实意义。选取位于黄土高原丘陵沟壑区的会宁县和定西市安定区退耕户跟踪数据,基于收入、政策、家庭因素等多个层面构建相关经济指标,揭示两个区域退耕户恩格尔系数呈现的基本特征、显著影响因素及其差异性。结果表明：首先,由于自然地理环境和区位相近,会宁县和安定区退耕户恩格尔系数呈现出较为一致的高位波动趋势,消费需求弹性较弱是主要影响因素;其次,退耕还林户补贴率对会宁县恩格尔系数有显著的负向影响,说明退耕还林政策对当地居民经济生活具有显著影响,安定区退耕还林户补贴率对恩格尔系数有显著的正向影响,主要原因是退耕还林补贴额在家庭收入中所占比重较少;最后,会宁县和安定区农户退耕率对恩格尔系数有显著影响,这意味着退耕户的主要收入来源于农业收入。     

基于改进的向后-向前选择法粗差定位与估值算法

对传统的向后-向前选择法粗差定位方法进行改进,即在原有基础上加入对平差模型的整体检验,计算统计量的相关系数,通过对偏相关系数的检验来定位统计量相关的粗差观测值。通过模拟粗差算例证明,该算法能够准确定位多维粗差,有效改善粗差定位转移的现象,且粗差估值结果比较可靠。     

Interaction of flexural gravity waves with shear current in shallow water

In the present study, the effect of shear current on the propagation of flexural gravity waves is analyzed under the assumptions of linearized shallow-water theory. Explicit expressions for the reflection and transmission coefficients associated with flexural gravity wave scattering by a step discontinuity in both water depth and current speed are derived. Further, trapping and scattering of flexural gravity waves by a jet-like shear current with a top-hat profile are examined and certain limiting conditions for the waves to exist are derived. The effects of change in water depth, current speed, incident wavelength and the angle of incidence on the group and phase velocities as well as on the reflection and transmission characteristics are analyzed through different numerical results.     

Velocity potential formulations of highly accurate Boussinesq-type models

The highly accurate Boussinesq-type equations of Madsen et al. (Madsen, P.A., Bingham, H.B., Schäffer, H.A., 2003. Boussinesq-type formulations for fully nonlinear and extremely dispersive water waves: Derivation and analysis. Proc. R. Soc. Lond. A 459, 1075–1104; Madsen, P.A., Fuhrman, D.R., Wang, B., 2006. A Boussinesq-type method for fully nonlinear waves interacting with a rapidly varying bathymetry. Coast. Eng. 53, 487–504); Jamois et al. (Jamois, E., Fuhrman, D.R., Bingham, H.B., Molin, B., 2006. Wave-structure interactions and nonlinear wave processes on the weather side of reflective structures. Coast. Eng. 53, 929–945) are re-derived in a more general framework which establishes the correct relationship between the model in a velocity formulation and a velocity potential formulation. Although most work with this model has used the velocity formulation, the potential formulation is of interest because it reduces the computational effort by approximately a factor of two and facilitates a coupling to other potential flow solvers. A new shoaling enhancement operator is introduced to derive new models (in both formulations) with a velocity profile which is always consistent with the kinematic bottom boundary condition. The true behaviour of the velocity potential formulation with respect to linear shoaling is given for the first time, correcting errors made by Jamois et al. (Jamois, E., Fuhrman, D.R., Bingham, H.B., Molin, B., 2006. Wave-structure interactions and nonlinear wave processes on the weather side of reflective structures. Coast. Eng. 53, 929–945). An exact infinite series solution for the potential is obtained via a Taylor expansion about an arbitrary vertical position z = zˆ. For practical implementation however, the solution is expanded based on a slow variation of zˆ and terms are retained to first-order. With shoaling enhancement, the new models obtain a comparable accuracy in linear shoaling to the original velocity formulation. General consistency relations are also derived which are convenient for verifying that the differential operators satisfy a potential flow and/or conserve mass up to the order of truncation of the model. The performance of the new formulation is validated using computations of linear and nonlinear shoaling problems. The behaviour on a rapidly varying bathymetry is also checked using linear wave reflection from a shelf and Bragg scattering from an undulating bottom. Although the new models perform equally well for Bragg scattering they fail earlier than the existing model for reflection/transmission problems in very deep water.     

青岛陆上观测点的气溶胶光学厚度特征分析及与渤海气溶胶光学厚度的比较

阐述了气溶胶散射对太阳光衰减的影响和对观测数据的统计分析.作者使用手持式五波段太阳光度计和臭氧监测仪对青岛崂山区陆域和渤海海域的大气衰减进行了较长时间的观测.分析表明,对可见光和近红外波段电磁渡的大气衰减贡献最大的是气溶胶散射,气溶胶散射的光学厚度随波长的增大而减小,但是它在大气总光学厚度中占的比例随波长的增大而增加.在青岛崂山区冬季,对应于440nm波长的气溶胶散射光学厚度主要分布在0.4～0.6和1.5～1.6区间,浑浊度系数α主要分布在0.15～0.45区间,埃斯特朗指数β主要分布在1.0～1.4区间.从时间上看,α和β在1d内的变化不大,但逐日变化非常显著.与晴天相比,青岛崂山区冬季雾天的气溶胶散射光学厚度增加了大约一倍,较大的浑浊度系数和较小的埃斯特朗指数表明,雾天的大气具有气溶胶散射的光学厚度大、粒子浓度大和粒径尺度大的特点.通过与海上观测数据的比较可见,青岛崂山区陆地冬季在雾天时的气溶胶分布与渤海夏季时相似,青岛崂山区陆地冬季在晴天无云时的气溶胶分布与渤海秋季时相似.     

The effect of current and wave on whitecap coverage via relative speed： the Atlantic Ocean case

Whitecapping plays an important role in many air-sea exchange and upper ocean processes. Traditionally, whitecap coverage is parameterized as a function of wind speed only. At present, the relative speed of ocean current to wind is considered to be important in the air-sea exchange parameterization which is the function of wind speed only. In this paper, the effects of ocean surface velocity (current velocity and wave induced velocity) and the wave parameters on whitecap coverage through relative speeds are investigated, by applying a 2-parameter whitecap coverage model to the Atlantic Ocean. It is found that the impacts of both current and wave on whitecap coverage are considerable in the most part of the Atlantic Ocean. It is interesting that the effect of wave is more significant than that of current.     

基于公平性的水环境容量分配研究——以沱江流域为例

公平与效益是容量分配的两个重要原则.在我国目前采用的水环境容量无偿分配方式下,公平原则是需遵循的首要原则,在公平的基础上追求效益.以沱江流域为对象,综合考虑涉及区域的社会、经济、自然等客观因素,筛选指标确定系数对流域容量进行分配.应用经济学中衡量收入公平的基尼系数概念,对分配结果的公平性进行评估,给出综合体现社会性、经济性和历史性的水环境容量分配方案.