高频引力波与现代宇宙学

文章简要综述了由典型现代宇宙学模型和膜振荡模型预期的微波频带的高频引力波的特性和可能的观测方案，以及研究这一课题的重要科学意义和所面临的挑战和机遇．     

Two-wavelength method for full-field automated photoelasticity

A new method for the whole-field determination of the isoclinic angle α and the isochromatic parameter ϕ is presented. The problems appearing during the calculation of these two parameters are solved with the use of two different wavelengths. Indeed, when a monochromatic light is used as an incident light, α is not measurable at the points where ϕ is equal to 2kπ. In this method, each monochromatic light can compensate for the influence of ϕ to obtain the isoclinic angle for the entire model. Also, most of the methods calculate the fractional fringe order that is unwrapped afterward to obtain the isochromatic parameter. This unwrapping process needs an initialization, which cannot be automatic with only one isochromatic fringe pattern. The use of two wavelengths permits a complete automatic unwrapping of the isochromatic parameter, even for the initialization of the process.     

Prophet inequalities for cost of observation stopping problems

Comparisons are made between the expected gain of a prophet (an observer with complete foresight) and the maximal expected gain of a gambler (using only non-anticipating stopping times) observing a sequence of independent, uniformly bounded random variables where a non-negative fixed cost is charged for each observation. Sharp universal bounds are obtained under various restrictions on the cost and the length of the sequence. For example, it is shown for X₁, X₂, … independent, [0, 1]-valued random variables that for all c ≥ 0 and all n ≥ 1 that E(max_{1 ≤ j ≤ n}(X_j − jc)) − sup_{t Tn} E(X_t − tc) ≤ 1/e, where T_n is the collection of all stopping times t which are less than or equal to n almost surely.     

微重力条件下晶体生长过程的实时观察

从材料科学的微重力效应和晶体生长基本过程等两个方面出发，阐明了一种新的生长技术（晶体生长过程的光学实时观察法）的必要性，并介绍了空间高温实时观察装置的基本特性．在我国的科学技术探测卫星上，该装置进行了搭载实验，并首次清楚地观察到了空间溶质扩散效应和高温溶液的表面张力对流图像．     

不等面积设施布局 的收敛 算法

采用单变量搜索在大范围移动设施以寻找最佳布局位置是不等面积矩形设施自动布局的一种算法‘但它的布局结果依赖于各设施的初始排列以及它们的移动次序.为了便于对原有布局进行迭代改进，本文使用.控制收敛”方法.它通过用放大设施数倍的包络块来代替原来的设施进行初始布局，并在每次优化循环后缩小包络块大小来为下一次优化循环产生移动空余空间，通过循环优化使设施的大小逐渐缩小到实际大小而终止.实例调试结果表明了该方法是有效的.     

O4对利用天顶散射光法测量大气组分含量的影响研究

通过实验证明是否考虑O₄的存在对利用天顶散射光测量大气组分含量的结果存在影响.介绍了天顶散射光的观测原理、实验仪器、测量方法、光谱处理以及浓度反演过程.用具体的实验数据说明考虑O₄在实验波段内的吸收能提高NO₂和O₃浓度反演结果的准确性.同时将观测得到的臭氧垂直柱密度与美国TOMS观测数据进行了对比. 关键词： 4')" href="#">O₄ 臭氧 天顶散射光 DOAS     

Stochastic stabilization of hybrid neural networks by periodically intermittent control based on discrete-time state observations

This paper is concerned with stabilization of hybrid neural networks by intermittent control based on continuous or discrete-time state observations. By means of exponential martingale inequality and the ergodic property of the Markov chain, we establish a sufficient stability criterion on hybrid neural networks by intermittent control based on continuous-time state observations. Meantime, by M-matrix theory and comparison method, we show that hybrid neural networks can be stabilized by intermittent control based on discrete-time state observations. Finally, two examples are presented to illustrate our theory.     

基于粒子滤波的微小卫星姿态确定算法

为了提高非线性卫星姿态控制系统的滤波性能,在建立了采用磁强计及太阳敏感器的卫星姿态模型的基础上尝试了新兴的粒子滤波(PF)算法对卫星系统进行姿态估计,进而对采用矢量观测的三轴稳定卫星的姿态确定问题进行了滤波算法的实时仿真,并将四元数转换成旋转矢量引入了粒子滤波算法,最后给出了卫星模型在不同粒子数目下的滤波性能比较,并在系统初始误差较大的情况下将粒子滤波算法与EKF滤波算法进行了滤波性能的对照。仿真结果表明,粒子滤波算法对粒子数目具有明显的依赖性,但是当粒子达到一定的数目时,粒子滤波的精度以及滤波稳定性都可以得到保证,尤其是在系统初始误差较大的情况下粒子滤波算法更显示了其优于EKF算法的滤波性能。     

铜黄公路某滑坡安全监测及预测研究

铜黄公路全长93.9km,其中遇到的各种滑坡30余处。为了研究这些滑坡的治理效果,对其变形与稳定进行了检测。以川口滑坡检测为例,运用灰色理论建立铜黄滑坡安全监控的GM(2,1)模型,其中非等时距位移序列采用拉格朗日插值函数转变为等时距序列。采用非等时距GM(2,1)和GM(1,1)模型对铜黄公路川口滑坡观测点进行安全预测。非等时距GM(2,1)模型预测滑坡变形精度总体较GM(1,1)模型高。由预测结果可见,治理后该滑坡是稳定的,预测结果和实际吻合良好。     

QuickFF: A program for a quick and easy derivation of force fields for metal‐organic frameworks from ab initio input

QuickFF is a software package to derive accurate force fields for isolated and complex molecular systems in a quick and easy manner. Apart from its general applicability, the program has been designed to generate force fields for metal‐organic frameworks in an automated fashion. The force field parameters for the covalent interaction are derived from ab initio data. The mathematical expression of the covalent energy is kept simple to ensure robustness and to avoid fitting deficiencies as much as possible. The user needs to produce an equilibrium structure and a Hessian matrix for one or more building units. Afterward, a force field is generated for the system using a three‐step method implemented in QuickFF. The first two steps of the methodology are designed to minimize correlations among the force field parameters. In the last step, the parameters are refined by imposing the force field parameters to reproduce the ab initio Hessian matrix in Cartesian coordinate space as accurate as possible. The method is applied on a set of 1000 organic molecules to show the easiness of the software protocol. To illustrate its application to metal‐organic frameworks (MOFs), QuickFF is used to determine force fields for MIL‐53(Al) and MOF‐5. For both materials, accurate force fields were already generated in literature but they requested a lot of manual interventions. QuickFF is a tool that can easily be used by anyone with a basic knowledge of performing ab initio calculations. As a result, accurate force fields are generated with minimal effort. © 2015 Wiley Periodicals, Inc.