色散特性对毫米波频率步进雷达影响的研究

对影响毫米波频率步进雷达分辨率的主要因素进行了分析。除目标速度以外,为毫米波频率步进雷达提供频率信号的频率源的色散特性也会对雷达分辨率造成恶化影响。微波频段上的色散特性会被搬移到毫米波频段,导致毫米波发射信号和本振信号的初始相位差不为常数,对雷达系统尤其是距离分辨率造成严重影响。仿真结果与实验结果一致。为了抵消色散特性对雷达分辨率的恶化影响,可以通过对色散特性的补偿来实现。色散特性补偿的方法被应用到实现W波段频率步进频率源的设计中,满足了0.45m距离分辨率的要求。     

大学生数学成绩影响因素的实证分析

伴随着近几年高校的扩大招生,部分大学生的数学成绩显著下降。用统计学软件SPSS 13.0对哈尔滨工程大学部分学生的高等数学成绩及其相关因素进行统计分析,考察学生的高考数学成绩、性别、生源所在地等因素对其大学数学成绩的影响。在给出了一些切实可行的对策和建议的同时,指出培养大学生学习的主动性和研究探索精神,已经成为当今高校教师和教育工作者培养高素质人才和提高教学水平的关键。     

緩变截面矩形波导开放式谐振腔

本文给出了求解缓变截面波导型开放式谐振腔的解析解,对缓变截面矩形疲导开放式谐振腔作了计算,求出了谐振频率,绕射Q值和场分布函数,所得结果与实验吻合。     

福建省农业科技期刊学术影响力的评估与分析

对福建省16种农业科技期刊连续10年的总被引频次和他引率进行统计与比较。结果表明,《福建农林大学学报(自然科学版)》、《福建林学院学报》、《福建农业学报》3种学术类期刊和《福建农业科技》、《福建林业科技》2种技术类期刊具有较高的学术影响力。并对统计结果和统计方式进行了分析。     

国外生物学期刊出版概况和特点

以《外国报刊目录》第九版为资料,对生物学期刊的学科分布、国别分布、类别分布、出版频率及出版机构等进行了认真调查,并对其突出的特点进行了简要的描述。     

基于频度与价格指标法比较的服务贸易壁垒研究

以中国入世承诺表及服务业上市公司的财务数据为基础,分别运用频度和价格指标法对中国各服务部门的贸易壁垒进行研究,并与制造业比较。结果显示,中国服务贸易对外开放广度大,但深度低,与制造业相比,服务贸易壁垒水平仍很高;服务部门间的壁垒水平差异大,除运输服务业外,传统服务业的贸易壁垒低于现代服务业,其中金融业的贸易壁垒限制最多;除教育服务外,其他部门的市场准入限制大于国民待遇限制。因此,应明确政府在服务贸易中的管理职能,完善相关法律体系。同时,逐步降低市场准入壁垒,优化产业结构,提高现代服务业竞争水平。     

Combinatorial Equivalence of Fractional Factorial Designs

Two symmetrical fractional factorial designs are said to be combinatorially equivalent if one design can be obtained from another by reordering the runs, relabeling the factors and relabeling the levels of one or more factors. This article presents concepts of ordered distance frequency matrix, distance frequency vector, and reduced distance frequency vector for a design. Necessary conditions for two designs to be combinatorial equivalent based on these concepts are presented. A new algorithm based on the results obtained is proposed to check combinatorial non-equivalence of two factorial designs and several illustrating examples are provided.     

软件无线电中正交数字变频的DSP实现

介绍了软件无线电的概念及DSP基本原理,利用DSP实现软件无线电中的正交数字变频技术,给出了中频下变频的数字化实现的主程序.     

A Probabilistic Methodology for the Assessment of Safety from Dropped Loads in Offshore Engineering

Pipeline damage by dropped objects from crane activities is a significant hazard for offshore platform installations. In this paper a probabilistic methodology is utilized for the estimation of the pipeline impact and rupture frequencies; this information is obtained both for the overall pipeline section exposed to the hazard and for a number of critical locations along the pipeline route. The presented algorithm has been implemented in a computer program that allows the analysis of a large number of possible drop points and pipeline target point locations. This methodology may be used in common risk analysis studies for evaluating the risk for platform personnel from dropped objects; however, the proposed technique may also be useful for other applications where engineering judgment has so far been the main driving criterion. In particular, two sample cases have been analyzed. The first one is the problem of selecting the best approaching route to a platform. By analyzing different route alternatives, a reduction of the impact frequency and therefore of the risk for the platform personnel may be achieved. The second application deals with the selection of the location for a safety valve at the riser base. The analysis may give useful information, such as the highest impact frequency location and the rupture frequencies upstream and downstream of the valve as a function of the valve position; this information, together with the transported medium inventory upstream of the valve, may give the designer a documented and justifiable rationale for selecting the best location for the valve from a safety point of view.