统计学中几个容易混淆的问题

统计学是一门重要的学科,在日常生活中有着极其广泛的应用。本文对统计学教学中几个容易混淆的问题进行阐明,旨在帮助学生对统计学中的一些概念有个正确的理解。     

声波垂直入射在两种介质界面处的反射和透射

通过对入射波、反射波和透射波振幅和声压的定量比较，得到了声波垂直入射在分界面处位移和声压的反射系数和透射系数，并对各种情况下的反射波和透射波进行了分析讨论．     

A matching algorithm based on hybrid matricesconsisting of reference differences and disparities

INTRODUCTION A common method for extracting depth in-formation from intensity images is based on theprinciples of stereovision. In this method, a pair ofimages is obtained using two cameras displacedfrom each other by a known distance. After deter-mining the stereo correspondence, the distance ofvarious points is computed using triangulation(Jeon et al., 2001). Stereo correspondence is theproblem of finding corresponding points in two ormore images of the same scene, usually assumin…     

边疆地区高校经济困难生心理健康及人格特点的调查分析

贫困大学生的心理健康问题备受关注，引起了大量的相关研究。由于地缘的差异性，贫困生心理问题体现出多样性特点。该文使用症状自评量表（SCL-90）和大学生现实感量表（艾森克现实性-幻想性测验）对滇南边疆民族地区两高校762名经济困难大学生进行团体测查，分析表明他们的心理健康水平较全国青年常模低，存在性别和经济状况等差异，其人格特质倾向于现实性，其中与他们的心理健康有因果关系的人格特征有实际性、男子气-女子气、攻击性和自信力。因此在对他们进行心理解困时，应有系统观理念，认知优化意识和“问题中心”的策略。     

一个混沌系统的霍普夫分叉分析

讨论了一个混沌系统的霍普夫分叉情况,并通过计算系统的第一李雅普诺夫系数判断了其分叉的方向,对相应的动力系统行为也作了简要的分析.     

体育专业大学生身体成分与心肺功能的相关性研究

以身体成分与心肺功能之间的相关性为研究目的,对本单位社会体育专业09级64名男生进行了身体成分、心率及肺活量测试,研究结果表明：各项身体成分同心率之间相关性不显著;体重与肺活量之间呈显著正相关（P〈0.01）,体脂百分比、肌肉百分比同肺活量之间的相关性不显著;体重、体脂百分比与肺活量体重指数之间呈极显著负相关（P〈0.01）,肌肉百分比与肺活量体重指数之间呈极显著正相关（P〈0.01）.     

功效系数法在高校财务风险预警系统中的应用

随着高等学校管理体制的改革,对高校财务风险的预警也成为高等教育界关注的问题.本文采取功效系数法构建高校财务风险预警模型,并结合M大学2006-2010年财务数据进行实例分析示范,希望结合其他方法使它能够有效识别风险,实现预警功能,从而在高校财务管理中发挥作用.     

一元线性回归系数比值不确定度的评定

分析一元线性回归系数的相关性,导出一元线性回归系数比值不确定度的计算公式,指出了某些文献中有关回归系数比值不确定度评定存在的问题.     

FARMER: A novel approach to file access correlation mining and evaluation reference model

File semantic has proven effective in optimizing large scale distributed file system. As a consequence of the elaborate and rich I/O interfaces between upper layer applications and file systems, file system can provide useful and insightful information about semantic. Hence, file semantic mining has become an increasingly important practice in both engineering and research community. Unfortunately, it is a challenge to exploit file semantic knowledge because a variety of factors could affect this information exploration process. Even worse, the challenges are exacerbated due to the intricate interdependency between these factors, and make it difficult to fully exploit the potentially important correlation among various semantic knowledges. This article proposes a file access correlation miming and evaluation reference (FARMER) model, where file is treated as a multivariate vector space, and each item within the vector corresponds a separate factor of the given file. The selection of factor depends on the application, examples of factors are file path, creator and executing program. If one particular factor occurs in both files, its value is non-zero. It is clear that the extent of inter-file relationships can be measured based on the likeness of their factor values in the semantic vectors. Benefit from this model, FARMER represents files as structured vectors of identifiers, and basic vector operations can be leveraged to quantify file correlation between two file vectors. FARMER model leverages linear regression model to estimate the strength of the relationship between file correlation and a set of influencing factors so that the “bad knowledge” can be filtered out. To demonstrate the ability of new FARMER model, FARMER is incorporated into a real large-scale object-based storage system as a case study to dynamically infer file correlations. In addition FARMER-enabled optimize service for metadata prefetching algorithm and object data layout algorithm is implemented. Experimental results show that is FARMER-enabled prefetching algorithm is shown to reduce the metadata operations latency by approximately 30%–40% when compared to a state-of-the-art metadata prefetching algorithm and a commonly used replacement policy.     

弹性管束换热器传热与阻力特性的实验研究

对弹性管束水-水换热器的传热与阻力特性进行了研究。主要分析了换热器在不同工况下的传热系数的变化规律;研究了弹性管束在管外流体和管内流体的共同诱导作用下,管外和管内对流换热的情况;并对管程和壳程的流动阻力损失进行了实验测量,得出了管程和壳程的阻力损失变化的规律,以及换热器管程阻力损失的计算方法。