A Critical review of theoretical models of negatively polarized light scattered by atmosphereless solar system bodies

About a dozen physical mechanisms and models aspire to explain the negative polarization of light scattered by atmosphereless celestial bodies. This is too large a number for the reliable interpretation of observational data. Through a comparative analysis of the models, our main goal is to answer the question: Does any one model have an advantage over the others? Our analysis is based on new laboratory polarimetric and photometric data as well as on theoretical results. We show that the widely used models due to Hopfield and Wolff cannot realistically explain the phase-angle dependence of the degree of polarization observed at small phase angles. The so-called interference or coherent backscattering mechanism is the most promising model. Models based on that mechanism use well-defined physical parameters to explain both negative polarization and the opposition effect. They are supported by laboratory experiments, particularly those showing enhancement of negative polarization with decreasing particle size down to the wavelength of light. According to the interference mechanism, pronounced negative branches of polarization, like those of C-class asteroids, may indicate a high degree of optical inhomogeneity of light-scattering surfaces at small scales. The mechanism also seems appropriate for treating the negative polarization and opposition effects of cometary dust comae, planetary rings, and the zodiacal light.     

Optimal Compensation and Implementation for Adaptive Optics Systems

This paper develops a compensation algorithm based on Linear–Quadratic–Gaussian (LQG) control system design whose parameters are determined (in part) by a model of the atmosphere. The model for the atmosphere is based on the open-loop statistics of the atmosphere as observed by the wavefront sensor, and is identified from these using an auto-regressive, moving average (ARMA) model. The (LQG) control design is compared with an existing compensation algorithm for a simulation developed at ESO that represents the operation of MACAO adaptive optics system on the 8.2 m telescopes at Paranal, Chile. This revised version was published online in July 2006 with corrections to the Cover Date.     

草莓红绿柱石(Pezzottaite)的晶体结构测定及其意义

利用CCD单晶衍射仪对草莓红绿柱石进行晶体结构测定,测定其空间群为R3c,并讨论了结构中Li 有序地置换Be2 造成c/a值的变化特征。晶体中发现复三方偏三角面体的负晶包裹体,其宏观对称属m,它与空间群Rc相对应,但与测出晶体结构的空间群有矛盾。X射线结构测定已否定了其空间群为Rm的看法。要解决草莓红绿柱石晶体空间群是否有对称中心(Rc或Rc)的问题,还需进一步将X射线结构的数据及其有关的电性实验结合分析。     

黄河断流对河口空间场后效反馈的遥感复合信息研究

就黄河断流对河口空间场后效所涉及的地理要素的演变,以所建河口演变概念-遥感信息系统,分析研究了黄河口近期演变的互关联信息基础,并依据研究目标的信息需求分析(IRA)与水下地貌趋势面分析的结果,阐述了河口空间场诸种反馈信息、变异中直观信息及隐伏信息.     

传感器电桥电路的非线性修正──用反馈补偿法修正传感器电桥电路的非线性误差

介绍一种反馈补偿法修正传感器电桥电路的非线性。提出反馈补偿原理及应用实例，指出用该方法可获得满意的补偿效果。     

受扰线性系统的前馈-反馈最优控制

针对具有外部持续扰动的线性系统，研究前馈-反馈最优控制律的设计问题。给出了最优控制律的存在唯一性条件。并提出了最优控制律的设计算法。利用滤波器解决了前馈控制的物理不可实现问题。仿真结果表明，此算法易于实现，与传统的反馈最优控制相比对抑制外部扰动具有较强的鲁棒性。     

浅谈（TCP）射孔技术在松辽地区应用与发展

油管传佃式射孔是近几年来射孔新技术,应用于石油、天燃气勘探、开发井中。的使用,大大提高了油气井的射孔效率,增加油气产量,降低了作业成本,从而能获得较好的经济效益,解决了正压射孔存在的不足,是一项新的负压射孔方式。通过几年来在松辽地区的应用,效果很佳。大部分的高产油气流都是采用这种射孔方法进行的。     

自重湿陷性黄土地区桩基设计探讨

根据自重湿陷性黄土的特点、《湿陷性黄土地区建筑规范》（GB50025—2004）和《建筑桩基技术规范》（JGJ94—94）中关于桩基设计的对比分析，通过自重湿陷性黄土场地工程实例分析计算，依据负摩擦产生的机理——中性点理论，论述了自重湿陷性黄土场地中桩基设计应考虑中性点，而不应全部计入负摩阻的观点。     

高新技术产业集聚的城市化响应与反馈机制研究

高新技术产业集聚与城市化存在互动机制。一方面,高新技术产业结构效应影响了城市化动力机制,集聚效应则促进了城市外部经济的发展,使城市化表现出不同的模式特征和地域特征;另一方面,城市化促进了高新技术发展所需要素资源的聚集与流动,为高新技术产业集聚提供人力资本保障,还为高新技术企业提供创新的源动力。文章以苏州高新区的高新技术产业发展和城市化互动关系佐证了这一理论,并认为建立二者之间切实可行的调控模式是当务之急。     

Study on the characteristics of rock failure strain and acoustic emission field for two parallelling faults with the same slip direction including asperities

Introduction Concerning about research on grouped-earthquake seismogenic and occurrence, at present it is only limited on the stage of the theoretical analysis and numerical model. For instance, ZHANG (1987) simulated the grouped-earthquake generation and physical mechanism making use of spring-block principle. Applying for non-linear dynamic model, referring to Chinese continental plate as object, LI, et al (1997) performed the numerical simulation on the seismogenic and occurring of group…