Normal reference value of forced vital capacity of Chinese younger women and geographical factors

Objective To supply a scientific basis for standardizing the normal reference value of forced vital capacity (FVC) of Chinese younger women. Methods We studied the relationship between the normal reference value of 21767 samples of FVC of younger women and eight geographical factors in 157 areas in China. Results It was found that the correlation between geographical factors and the normal reference value of FVC of younger women was quite significant (F=5.884, P=0.000). By adopting the method of mathematical regression analysis, one regression equation was inferred: =3.146+0.00006919X1+0.01315X4-0.006966X6+0.09524X8±0.254. In the above equation, is the normal reference value of younger women' FVC (L); X1 is the altitude (m); X4 is the annual mean air temperature (℃); X6 is the annual mean relative humidity (%); X8 is the annual mean wind speed (m/s); 0.254 is the value of the residual standard deviation. Conclusion If geographical values are obtained in a certain area, the normal reference value of FVC of younger women in this area can be obtained by using the regression equation. Furthermore, according to the geographical factors, China can be divided into eight regions: Northeast China Region, North China Region, Shanxi-Shaanxi-Inner Mongolia Region, middle and lower reaches of the Yangzte River Region, Southeast China Region, Northwest China Region, Southwest China Region, and Qinghai-Tibet Plateau Region.     

GIS-T中交通事件的动态表达

针对当前GIS -T中对于交通事件表达的不足,首先利用交通波理论计算交通事件对路网影响范围的时空变化情况;其次基于线性参考和标准动态分段思想,在标准动态分段中增加时间维属性,通过程序扩展在现有GIS平台上实现时空动态分段方法,并用该方法实现交通事件影响临近路段范围的时空变化可视化表达.结果表明,利用时空动态分段方法可以...     

一种基于神经网络的模型参考自适应控制的研究

本文将ＢＰ网络的非线性映射特性和联想记忆功能用于模型参考自适应控制中，用以克服传统模型参考自适应控制算法的不足。仿真研究表明，该方法不仅能实现原方法的功能，而且该系统稳定性和抗干抗方面中优于原方法。     

基于地理信息系统的公路设施空间数据库概念模型

应用实体－关系（Ｅ－Ｒ）数据库概念模型设计工具，通过对公路设施数据库特性、实体组成及实体间关系的深入研究，建立一个比较完整严密的基于地理信息系统的公路设施空间数据库概念模型，为地理信息系统技术在公路设施管理中的应用打下理论基础。     

考虑变质量的路基沉降应力变形协调分析法

针对传统分层总和法存在小变形假定和无法考虑地基排水引起的质量变化等缺点，在不同参考构形等概念的基础上，重新解释了应变和压缩模量等度量的内涵，结合分层总和法和有限变形理论的基本思想，提出考虑变质量的应力变形协调分析法，用于计算最终沉降和固结沉降。对手排水和不排水路基的沉降问题，分析了最终沉降量的协调解与两种传统解的计算差别及其相对误差的变化规律，探讨了新方法在预测路基固结沉降中的应用。结果表明：最终沉降量的协调解和两种传统解均随着压缩层厚度的增加近似按双曲线规律增加，随着荷载的增加近似按线性规律递增；常用的不考虑应变历史修正的传统解计算结果偏小；协调分析法能提高顸估路基固结沉降的精度等。用新方法可以更准确地计算路基的最终沉降和固结沉降。     

关于现行公路桥规中城市桥梁设计的几点探讨

现行<公路桥涵设计通用规范>(JTG D60-2004)、<公路钢筋混凝土及预应力混凝土桥涵设计规范>(JTG D62-2004),较85规范在很多方面有实质性的改进,但是,<城市桥梁设计准则>(CJJ 11-93)及<城市桥梁设计荷载标准>(CJJ 77-98)与其存在着脱节的内容.探讨上述规范中城市桥梁的设计基准期、荷载组合及冲击系数等问题.     

The asymmetric effects of service quality on passengers' choice of carriers for international air travel

The asymmetric effects of service quality on international travelers' airline choice behavior were investigated in this paper. The linear structural equation modeling system was first applied to quantify passengers' perceptions of service quality provided by airlines, which were then used as the input variables of the asymmetric response model developed to capture international travelers' airline decision. Their asymmetric responses to various service quality of airlines were assumed to be either gains or losses with respect to their reference points. The results showed that the asymmetric response model performs better than the traditional logit models that capture only symmetrical effects.     

室内固结试验测定基准基床系数的方法与分析

通过对室内固结试验相关参数的设定,模拟地基土承载变形试验,根据固结试验的压力-变形关系,计算地基土的基床系数,并通过相应的换算求取土的基准基床系数。从而实现基准基床系数的批量测定,解决现场试验条件和经费的限制的问题,提供更多的试验数据,为工程设计使用。     

某分析接收机的晶振及其5分路器单元电路

本文详细地分析了某分析接收机晶振的具体单元电路,给出了具体的电路图、方框图,主要组成和关键部分分析,具有较强的实用性。     

N-P准则与CA-CFAR检测技术研究

在杂波和噪声环境下脉冲雷达对杂波和噪声进行统计分析处理,确定杂波和噪声的概率分布模型,选择相应的恒虚警检测方法,以检测目标回波信号。N-P准则不能随环境的变化而调整门限,虚警概率较高;而CA-CFAR检测能够根据参考窗内的信号的特性,自适应调整检测门限,虚警概率较低。文章研究了N-P准则和CA-CFAR检测技术的基础,并对二者的检测性能进行了仿真分析比较。