Modal behavior of photonic-crystal vertical-cavity surface-emitting diode laser analyzed with Plane Wave Admittance Method

A three-dimensional, full vectorial model has been applied for investigation the modal characteristics of a phosphide photonic-crystal vertical-cavity surface-emitting diode laser. The photonic crystal has been defined as a regular, hexagonal net of holes, etched in the upper, p-type Distributed Bragg Reflector of the laser. The electromagnetic field has been confined to the active region by a single defect of the photonic crystal providing overlapping with carriers funneled by a tunnel junction. We have determined the range of design parameters, which provide single mode operation.     

Atomistic explanation of the Gough-Joule-effect

An interpretation of the Gough-Joule-Effect from an atomistic point of view is given by a special investigation of lattice vibrations using a non-interacting model. The calculations are restricted to crystals with ideal crystal structure built up of only one kind of particles. Approximate analytical formulas are derived. A comparison between the classical macroscopic theory and the here presented microscopic calculations is drawn. Received 5 April 2001 and Received in final form 16 August 2001     

THE SUPPORT POINTS AND EXTREME POINTS OF THE UNIT BALL OF H'p

Byσthe author denotes the areal measure on the unit disk D=z: |z|<1. Let H'p={f(z): f(z) is analytic in D and 1/π∫D|f(z)|p dσ<+∞}. Let B(H＇p)={f:f∈H＇p and 1/π∫D|f(z)|p dσ1. This article researches the support points and extreme points of B(H'p).     

Modeling Structure–Activity Relationship of AMPK Activation

The adenosine monophosphate activated protein kinase (AMPK) is critical in the regulation of important cellular functions such as lipid, glucose, and protein metabolism; mitochondrial biogenesis and autophagy; and cellular growth. In many diseases—such as metabolic syndrome, obesity, diabetes, and also cancer—activation of AMPK is beneficial. Therefore, there is growing interest in AMPK activators that act either by direct action on the enzyme itself or by indirect activation of upstream regulators. Many natural compounds have been described that activate AMPK indirectly. These compounds are usually contained in mixtures with a variety of structurally different other compounds, which in turn can also alter the activity of AMPK via one or more pathways. For these compounds, experiments are complicated, since the required pure substances are often not yet isolated and/or therefore not sufficiently available. Therefore, our goal was to develop a screening tool that could handle the profound heterogeneity in activation pathways of the AMPK. Since machine learning algorithms can model complex (unknown) relationships and patterns, some of these methods (random forest, support vector machines, stochastic gradient boosting, logistic regression, and deep neural network) were applied and validated using a database, comprising of 904 activating and 799 neutral or inhibiting compounds identified by extensive PubMed literature search and PubChem Bioassay database. All models showed unexpectedly high classification accuracy in training, but more importantly in predicting the unseen test data. These models are therefore suitable tools for rapid in silico screening of established substances or multicomponent mixtures and can be used to identify compounds of interest for further testing.     

支持向量回归算法在光纤光栅非均匀应变重构中的应用

当布拉格光栅轴向存在大的应变梯度时,其反射光谱的形状会被扭曲.甚至出现多峰,发展非均匀应变分布重构方法对于结构健康监测技术具有重要意义.但采集反射光谱时的测试噪声会显著影响应变分布重构的精度.为此,提出了采用支持向量机对含噪的反射光谱进行回归预处理,并运用适应度排序改进的遗传优化算法结合传输矩阵反射光谱构建方法识别布拉格光栅轴向非均匀应变分布的方法.该方法将反射光谱视为时间序列.利用支持向量回归的全局优化和泛化能力进行噪声抑制.从而回归出有效的反射光谱;通过传输矩阵方法将光栅轴向应变分段均匀化,利用改进的遗传算法进行并行重构.对多种应变分布形式下的应变重构进行了仿真研究,结果表明,支持向量机方法可以有效地进行反射光谱同归,提高非均匀应变分布重构的精度.     

带有强吸收项的半线性热方程解的相关性质

研究了一类带有强吸收项的半线性热方程的Cauchy问题,得出了解的存在性和惟一性,并利用比较原理给出了解的支集的瞬间收缩性质和解的有限时间淹没性质及指标p的最优性.     

c/uA及mi/me取值对于磁重联过程的影响

构造控制电磁场散度误差的有限差分方法,该方法结构简单,可将电磁场散度误差控制在舍入误差量级.该方法应用到GEM,得到的结果与已发表文献类似.研究双流体模型中可调参数光速和离子与电子的质量比对磁重联过程的影响.结果表明：光速增加后,净电荷的积累减少,而重联率几乎不变.离子与电子质量比增加导致电流片变薄,从而使得重联加快.     

1.5m级大口径标准镜面支撑系统的研究

现阶段科研检测仪器对光学镜面的面形精度要求越来越高.光学镜面的口径越大,自重导致的变形问题越严重.为了保证大口径标准镜在法线水平状态下的面形精度,提出了侧面钢带支撑和杠杆平衡重锤卸荷的组合支撑结构,与传统使用的钢带支撑、水银带支撑方式作了比较,并通过ansys有限元分析软件建立的模型对几种不同侧支撑方法进行了分析比较,...     

旋波介质中的色散关系

从介质的物态方程出发，研究旋波介质的色散性质，给出了波数随旋波参量和频率变化的关系。     

傅立叶望远镜外场试验聚光镜子镜支撑模块的设计

傅立叶望远镜（Fourier Telescope）作为一种新兴的光电探测技术,已经成为对深空目标高分辨率成像的首选技术之一。为了推进实际系统的工程化进展,本文设计了傅立叶望远镜外场实验系统聚光镜子镜支撑模块,对镜面支撑与角度调整机构采用串联分级设计。子镜底支撑采用圆周均布的3点柔性膜片,可以很好的抵消热变形对面型精度的影响;侧支撑采用中心柔性隔膜定位,6点杠杆重锤承受径向重力载荷的方式;角度调整机构采用3点螺旋传动可以实现对子镜室的3自由度调整。经有限元分析,镜面的PV值为200nm,RMS值为40nm,曲率半径变化小于1毫米。该设计方法对薄镜面的支撑调整也具有一定的参考价值。