关于次序统计量数学期望的两个恒等式的简证及其应用

给出了最大最小次序统计量分布函数和密度函数的恒等式,从而在随机变量独立同分布情形下,给出了关于次序统计量数学期望的两个恒等式的简捷证法.最后将几个恒等式应用于威布尔分布的最大次序统计量的分布及其数字特征的计算.     

咳嗽变异性哮喘患儿白三烯水平与白三烯受体拮抗剂疗效的相关研究

目的探讨不同白三烯（LT）水平的咳嗽变异性哮喘（CVA）患儿接受白三烯受体拮抗剂（LTRA）治疗后体内LT水平变化与临床疗效的关系。方法以本地300例同年龄儿童所测定的尿LTE4值（25.17±14.26）ng/L作为基础对照,将使用LTRA孟鲁司特治疗的67例CVA患儿按LTE4水平是否高于基础对照水平的2SD,分成LTRA-高（H）组25例和LTRA-低（L）组42例,治疗1个月后观察尿LTE4水平变化和临床疗效;采用相同方法将使用吸入糖皮质激素（ICS）氟替卡松治疗的60例患儿分成ICS-H组20例和ICS-L组40例进行对照。结果所有CVA患儿尿LTE4水平与基础对照相比均有统计学差异（均P＜0.05）;在接受2种不同方法治疗1个月后,LTRA-H组、LTRA-L组和ICS-H组患儿尿LTE4水平均有明显下降（均P＜0.05）,但ICS-L组无明显变化（P＞0.05）。LTRA组与ICS组总体疗效相当（P＞0.05）;LTRA-H组疗效优于LTRA-L组（P＜0.05）,LTRA-L组与ICS-H组、ICS-L组疗效均无统计学差异（均P＞0.05）。结论 CVA患儿采用LTRA和ICS治疗总体疗效相当;体内LT水平与LTRA临床疗效密切相关,LT水平高者疗效优于低者;尿LTE4检测可以作为临床选用LTRA的指标。     

负超几何随机变量期望与方差的一种简捷计算

给出了负超几何分布的概率模型,通过将负超几何分布随机变量进行和式分解,比较简捷地计算了它的期望和方差,并指出文献[4]计算的期望和方差是错误的.     

Comparative research on the transmission-mode GaAs photocathodes of exponential-doping structures

Early research has shown that the varied doping structures of the active layer of GaAs photocathodes have been proven to have a higher quantum efficiency than uniform doping structures. On the basis of our early research on the surface photovoltage of GaAs photocathodes, and comparative research before and after activation of reflection-mode GaAs photocathodes, we further the comparative research on transmission-mode GaAs photocathodes. An exponential doping structure is the typical varied doping structure that can form a uniform electric field in the active layer. By solving the one-dimensional diffusion equation for no equilibrium minority carriers of transmission-mode GaAs photocathodes of the exponential doping structure, we can obtain the equations for the surface photovoltage (SPV) curve before activation and the spectral response curve (SRC) after activation. Through experiments and fitting calculations for the designed material, the body-material parameters can be well fitted by the SPV before activation, and proven by the fitting calculation for SRC after activation. Through the comparative research before and after activation, the average surface escape probability (SEP) can also be well fitted. This comparative research method can measure the body parameters and the value of SEP for the transmission-mode GaAs photocathode more exactly than the early method, which only measures the body parameters by SRC after activation. It can also help us to deeply study and exactly measure the parameters of the varied doping structures for transmission-mode GaAs photocathodes, and optimize the Cs-O activation technique in the future.     

A method for phase reconstruction in optical three-dimensional shape measurement

In optical three-dimensional shape measurement, a method of improving the measurement precision for phase reconstruction without phase unwrapping is analyzed in detail. Intensities of any five consecutive pixels that lie in the x-axis direction of the phase domain are given. Partial derivatives of the phase function in the x-and y-axis directions are obtained with a phaseshifting mechanism, the origin of which is analysed. Furthermore, to avoid phase unwrapping in the phase reconstruction, we derive the gradient of the phase function and perform a two-dimensional integral along the x- and y-axis directions. The reconstructed phase can be obtained directly by performing numerical integration, and thus it is of great convenience for phase reconstruction. Finally, the results of numerical simulations and practical experiments verify the correctness of the proposed method.     

基于MTS特征选择的神经网络集成方法

在Bagging算法基础上,运用马田系统进行特征选择,形成双重扰动改善神经网络集成的分类性能.实验表明,双重扰动增加了集成网络个体精度和差异度,基于MTS-Bagging算法的分类性能相比于Bagging有明显提高.     

动态因子模型在房价波动因素分解中的应用——基于中国26个城市房价波动的分析

利用动态多因子模型,对26个大中城市1999年1月-2010年5月的房地产价格波动进行因素分解,分别提取了表示区域特征的区域因子和城市特征的城市因子,从区域因子的特征看各区域房价波动受政府调控和宏观经济形势影响较大.因素分解结果表明:各区域因子对区域内各城市房价波动的影响贡献度较大,而且在经济发达地区这个特征更明显.对区域因子互动关系的研究表明:我国大中城市房价波动存在从东部沿海发达地区分别向东北,中部,西部蔓延的"波纹效应".本文的结论有助于加强不同区域房地产市场调控和监管的针对性.     

数学的概念教学与解题策略

一、万般皆“ 下品”,唯有概念高 数学概念是数学的基础,是建立数学知识体系的基石.学生对概念的理解是否真的到位,是否能掌握其内涵和外延,是学好数学的关键.无论采用什么教学方法,这一点必须落实到位.否则,无论如何是不能收到应有的效果——因为基础不扎实.     

Cu(In,Ga)Se2太阳能电池快速热退火效应

利用光致发光（PL）分析快速热退火对Cu(In,Ga)Se2 (CIGS)电池的影响,研究退火对薄膜缺陷的影响。Cu(In,Ga)Se2电池的PL谱中总共有 7个峰,即2个可见波段峰和5个红外波段峰。退火温度较低,可减少薄膜体内缺陷,提高载流子浓度,改善薄膜质量;退火温度过高,则会引起正常格点处元素扩散,元素化学计量比改变,体内缺陷增加,吸收层带隙降低,反而会对CIGS薄膜造成破坏。     

声悬浮实验中谐振腔形状对声压大小的影响研究

研究了不同谐振腔接收器表面的声压大小,发现谐振腔内增减凹球面反射面对声压波形有较大影响.分析了声压波形发生变化的原因,认为增加凹球面反射面时,声压波形变化是由于声波在谐振腔上下两表面存在非垂直反射.