二次曲线拟合算法的统计性能分析与改进

传统的二次曲线拟合使用标准特征值分析算法。通过统计分析技术 ,可知该技术在拟合数字二次曲线时 ,存在估计偏差大、均方误差大的缺点。其产生原因是数据噪声的有色性和自相关函数矩阵的条件数过大 ,因此白化数据噪声和正则化变换是提高曲线拟合的有效措施。这从理论上有力地支持了Hartley提出的正则化算法。通过理论分析和计算机仿真实验 ,表明了降维EVD技术固有地同时具备噪声预白化功能和数据正则化功能 ,因此它能给出均方误差相当小的无偏估计。由于它无须进行预白化变换或正则化变换 ,并把最优化过程的维数从 6降为 2 ,所以它还具有计算快速、实现简单方便的优点。     

Seeking Nettle Textiles – Utilizing a Combination of Microscopic Methods for Fibre Identification

Bast fibres have been commonly used as a textile material in Northern Europe since Neolithic times. However, the process of identifying the different species has been problematic, and many important questions related to their cultural history are still unanswered. For example, a modified Herzog test and the presence of calcium oxalate crystals have both been used in identification. In order to generate more reliable results, further research and advancement in multi-methodological methods is required. This paper introduces a combination of methods which can be used to identify and distinguish flax (Linum usitatissimum), hemp (Cannabis sativa), and stinging nettle (Urtica dioica). The research material consisted of reference fibres and 25 fibre samples obtained from 12 textiles assumed to be made of nettle. The textiles were from the Finno-Ugric and Historical Collections of The National Museum of Finland. The fibre samples were studied by observing the surface characteristics and cross sections with transmitted light microscopy, and by using a modified Herzog test with polarized light, in order to identify the distinguishable features in their morphological structures. The study showed that five out of 25 samples were cotton, 16 nettle, one flax, and one hemp. Findings from two samples were inconsistent. The results show that it is possible to distinguish common north European bast fibres from each other by using a combination of microscopic methods. Furthermore, by utilizing these combined methods, new and more reliable information could be obtained from historical ethnographic textiles, which creates new vistas for the interpretation of their cultural history.     

教研室管理视域下的大学英语教师素养提升

教研室工作的核心力量是教师。教师整体素养的提升，是教研室工作得以顺利展开的关键。在提升教师素养方面，大学英语教研室可以开展如下工作：引导探究大学英语教师素养的内涵；组织分析优秀教师个人素养提升的案例；保持团队的持续发展与影响。     

输水渠道横断面设计水深测试及计算(综合性)实验

输水渠道横断面设计水深测试及计算实验结合“灌溉排水工程学”及“水力学”等学科的知识,在实验过程中,通过对实验数据的测试、分析及计算和渠道模型实物的观摩,加深了对渠道设计原理的理解,与课堂上的理论教学起到了良好的互动作用。     

基于Pro/E的直齿锥齿轮Program参数化造型

介绍Pro/Engineer的Program参数化造型方法及其程序结构,并且以直齿锥齿轮为实例,详细地介绍Program参数化造型的实现过程。为同类产品实现参数化造型,减少重复劳动,提高设计效率提供一种适用、有效的方法。     

普通高中基层弹性教研组织的建构

普通高中基层教研组织是学校的基本单位,是教师成长、发展、互动的群体。尽管传统教研组织在“教师职业化”方面意义深远,但其在现实中过于彰显科层性管理功能:只涉及问题的解决,而不注重问题的发现和问题的界定;高扬的“工具理性”阻碍了“教师职能的专业化”的发展。面对走向“专业化的教师职业”问题,本研究认为:对教研组的研究和改型变得十分必要;构建一个弹性教研组织作为教师反思、批判和发展的平台已势在必行。     

正确把握“三个关系“促进机关后勤服务的顺利转轨

机关后勤服务业要努力塑造服务新形象,变被动服务为主动服务,坚定走产业化道路,这样才能保证可持续发展.     

一维搜索的程序实现

对于不可微的一元目标函数，我们用一维搜索去解决。本文给出了一维搜索中的三个算法：二分法，三等分算法，黄金分割法各自的C语言源程序，从而可以求出目标函数比较精确的近似最优点。     

From natural numbers to numbers and curves in nature —I

The interconnection between number theory, algebra, geometry and calculus is shown through Fibonacci sequence, golden section and logarithmic spiral. In this two-part article, we discuss how simple growth models based on these entities may be used to explain numbers and curves abundantly found in nature     

从美军观察组看抗战后期美国对中共政策

1944年美国向延安派遣了一个军事观察组,代号＂迪克西使团＂,与中共取得了直接的接触,但是,美军观察组的派遣,并不意味着美国放弃片面的扶蒋联共政策,开始对中共进行军事援助,而是试图以联合中共作为向蒋介石施加压力的手段,以促使蒋改革内政,成为控制中国的唯一政治力量,避免中国内战的爆发,从而达到控制中国及保持远东稳定的目标。