基于条件概率积分变换的多元Copula函数选择

本文构建了基于条件概率积分变换的Copula函数选择方法,通过对条件概率积分变换下Anderson-Darling(AD)、Kolmogorov-Smirnov(KS)、Cramér-von Mises(CM)这三种统计量的比较,讨论在不同样本容量和变量维数下其对多种Copula函数的拟合效果。利用GSPTSE、INMEX.MX和NDX三大股指样本,将基于条件概率积分变换的Copula函数选择方法与核密度估计和极大似然估计选择法的效果进行系统比较。结果表明,基于条件概率积分变换的检验法可以有效解决多元Copula函数的选择问题,其拟合优度检验更精确、更稳定;核密度估计检验在大样本下比较稳定,而小样本下稳定性较差;相比之下,极大似然值检验法则不稳定。     

基于ASRank和MMAS的蚁群算法求解飞机指派问题

本文将航班串的飞机指派问题归结为车辆路径问题,考虑连续航班串之间衔接时间、衔接机场的约束、每架飞机的总飞行时间约束,建立了带有飞行时间约束的车辆路径问题的混合整数规划模型。构造了蚁群系统算法,引入基于排序的蚂蚁系统和最大最小蚂蚁系统算法的信息素更新策略。选取某航空公司7组初始航班串集合进行测试,并对算法中的重要参数进行了分析。实验结果表明,本文设计的模型和算法可以有效地减少连续航班串之间的总衔接时间,在可接受的计算时间内获得满意解。     

中国高龄老人生活自理能力纵向动态研究

利用"中国老年健康长寿跟踪调查"1998年、2000年、2002年的跟踪数据分析中国高龄老人ADL的变动趋势及其影响因素。个体增长模型结果显示,高龄老人ADL状况随年龄增长出现了明显的下降趋势,ADL个体差异十分显著。个体之间的差异解释了ADL总差异的31.13%。经历三次追踪调查的高龄老人ADL均值较高,状况较好,下降速度较慢;基期具有3-4项残障的高龄老人,未来ADL下降最为迅速;基期ADL水平高的高龄老人,ADL下降较慢。从ADL的个体影响因素来看,对于基期ADL水平影响最大的变量是"年龄"、"疾病状况"以及"居住安排"等,而对观测期ADL变动速度影响最大的变量是"年龄"以及"过去是否经常从事体力劳动"等。     

广义岭选择指数(英文)

把岭回归的原理和方法应用到家畜性状的选择指数中 ,提出了广义岭选择指数 ,理论和实践证明的这一指数形式在一定意义上优于传统的选择指数。也可以说 ,它在一定意义上丰富了选择指数的理论 ,但不能代替经典的选择指数     

从胡文化“汉化”看生态环境的迁移对文化转型的影响

不同文化特质的形成 ,除受政治经济影响外 ,还受特定生态环境的制约。胡汉两大文化体系的差异 ,在很大程度上就是不同生态环境作用的结果。与此相应 ,文化的发展一旦脱离了与自身相适应的环境 ,就势必要出现势能上的劣势 ,并逐渐与异地文化相溶     

脉宽调制型DC—DC变换器的线性描述函数分析法

介绍了一种分析开关变换器的新方法－线性描述函数法的理论证明及实验结果,这种方法具有精确度高的优点。     

DNA芯片技术

DNA芯片可用于核酸序列的测定及基因突变检测等,这里对DNA芯片的制作、作用原理、性能及用途等进行了综述。     

鲇鱼(Silurus asotus)产卵类型的研究

本文侧重研究了站鱼个体生殖力及产卵类型。结果表明：雌性个体1冬龄达性成熟,性腺一次成熟,卵子分批产出,产卵期是6—8月份,性成熟系数在7月份达高峰,8月份是产卵盛期,在产卵前的卵巢切片只发现有第4时相和第5时相卵母细胞,确定产卵类型为一次产卵。     

PSS码词组输入法及教学实践

本文介绍了PSS码（拼音、声调、首笔码）汉字输入法的词组编码及输入方法,并总结了PSS码作为一门选修课的教学效果。     

A gender comparison of HIV and drug use across the rural-urban continuum

Despite the central role of women drug users in escalating AIDS statistics, there is still a limited number of studies that examine the roles of gender and drug use type in HIV seroprevalence. This lacuna in the research literature has led to significant gaps in researchers' understanding of how and to what extent women may differ in their drug-using and HIV risk behaviors compared to their better-studied male counterparts. This study, derived from a sample of 3,555 out-of-treatment drug users residing in three South Florida urban and rural communities, attempts to compare the drug usage and needle and sexual risk behaviors of male and female drug users that put them at risk for HIV infection. The overall seropositivity rate for women drug users was 26.5% compared to 19.5% for their male counterparts. Results of multivariate analyses indicate that females compared to males were 1.4 times more likely to be HIV seropositive. Risk behaviors associated with this elevated seropositivity include living arrangements, homeless status, drug use, sexual trading behaviors, and history of STDs. Furthermore, there was a strong linear relationship between drug use type and HIV seroprevalence among women drug users. Compared to those who were neither crack smokers nor injectors of illicit drugs, those who were crack smokers only were 2 times more likely to be HIV seropositive, while those who were both crack smokers and injectors were 5 times more likely to be HIV seropositive, and those who were injectors only were 6 times more likely to be HIV seropositive. These findings indicate that among women, drug abuse and its associated risk behaviors, increase the vulnerability of this population for HIV and thus render them an extremely important priority population on which to focus HIV prevention and public health efforts and programs.