Powerful nonparametric statistics to compare k independent ROC curves

The authors deal with the problem of comparing receiver operating characteristic (ROC) curves from independent samples. From a nonparametric approach, they propose and study three different statistics. Their asymptotic distributions are obtained and a resample plan is considered. In order to study the statistical power of the introduced statistics, a simulation study is carried out. The (observed) results suggest that, for the considered models, the new statistics are more powerful than the usually employed ones (the Venkatraman test and the usual area under the ROC curve criterion) in non-uniform dominance situations and quite good otherwise.     

A step-by-step algorithm for combining diagnostic tests

Combining data of several tests or markers for the classification of patients according to their health status for assigning better treatments is a major issue in the study of diseases such as cancer. In order to tackle this problem, several approaches have been proposed in the literature. In this paper, a step-by-step algorithm for estimating the parameters of a linear classifier that combines several measures is considered. The optimization criterion is to maximize the area under the receiver operating characteristic curve. The algorithm is applied to different simulated data sets and its performance is evaluated. Finally, the method is illustrated with a prostate cancer staging database.     

共同海损债务中的运费分摊

结合海运实务就共同海损债务中的运费分摊人、运费分摊原则与条件、运费分摊价值计算等问题加以分析和探讨。     

离心管摩擦桩的设计

本文引用了优化理论的基本概念,着重论述了离心管摩擦桩的优点。     

基于多相滤波的宽带数字化接收机技术

提出了一种多相滤波的宽带数字化接收机的设计技术;讨论了多相滤波的基本原理、设计及FPGA实现,给出了多相滤波的中频数字化接收机的实现方案。计算机仿真结果和现场可编程门阵列仿真结果表明,多相滤波的中频数字化接收机设计方法是可行的,并还可灵活地实现现有专用芯片很难实现的宽带接收技术。     

光源对于太阳能电池基本特性测量实验影响的研究

本文研究了光源对于太阳能电池基本特性测量实验的影响。分别采用白炽灯和日光灯作为光源,测量了太阳能电池的伏安特性、开路电压、短路电流、最大输出功率、填充因子、光照特性等基本特性。     

低渗透气藏气体渗流速度修正式

渗流的基本规律达西定律,是100多年前法国水利工程师达西提出的,他是通过液体实验得到的。对于气体渗流来讲,存在着滑脱效应,特别是在低渗、低速和低压时,滑脱效应更为显著。在考虑了气体渗流的特点后,结合分子扩散理论得到了考虑滑脱效应的气体渗流速度方程,为进一步开展低渗透气藏渗流理论研究,油藏工程研究和动态分析建立了基础。     

圆管分层层流的流动规律

从流体力学中NOS 方程出发,建立了圆管两相分层层流流动的数学模型。通过两相分层层流的相互作用的流体力学分析,提出了两相流动界面的耦合条件,从而得到了一组完整描述两相圆管分层流的数学方程,再通过数值求解分层流的数学方程,得到了对工程实际应用有重要价值的流动规律。应用圆管两相分层层流的流动规律,可以实现高粘流体的高效率输送, ,其节能效果十分明显。     

石油钻杆内爬行器信号处理系统的设计

基于漏磁检测原理的钻杆内爬行器，可在石油钻杆内部运动．并对分布于钻杆内壁的缺陷进行检测。由于石油钻井用钻杆的外径通常都较小（通常在60．3～88．9mm），要求内爬行器的信号处理系统体积小、功耗低、具有数据记录功能、自带供电模块。设计了石油钻杆用漏磁信号处理系统，包括了一组信号放大电路、信号处理模块、电源模块、数据存储模块，并设计了相应的软件，实现了对漏磁信号的分析和记录，系统已在相关企业获得应用，取得良好效果，检测信噪比不低于10dB，对人工刻制的缺陷检出率达到100％。     

支撑板制造质保软件可靠性评估的模糊层次分析

用模糊层次分析法建立了管子支撑板制造质保软件的可靠性评估模型，并以实例求解。