宽带随机混沌雷达高速目标速度估计与成像

随机混沌具有真随机性、对初值敏感、易于产生和控制等特点,频率步进信号易于工程实现和处理,结合两者的优势,提出了一种载频随机步进的随机混沌信号(RSCFSCS)模型,用于高速目标的速度估计和距离维高分辨成像。首先,通过非周期函数激励非线性系统,产生不可预测的随机混沌信号(SCS),经频率调制后用作基带子脉冲。同时,将SCS通过映射变换得到跳频编码(FHC),用来决定调频脉冲串的载频步进。RSCFSCS 速度估计包括粗搜索和精搜索,粗搜索采用固定步长,保证速度偏差小于速度分辨单元,而精搜索采用黄金分割搜索算法可得到精确的速度估计。最后,子脉冲经相干合成形成宽带信号,实现高分辨距离成像。数值仿真表明提出的信号模型和处理算法性能良好。     

高压风式清扫器在洗煤厂中的应用

邢台煤矿洗煤厂用风量较大,风源较多,而传统清扫器自身重量较大,使用时聚氨酯板磨损快,不易安装和进行日常维护,且维护成本较高。本文对传统清扫器进行改造升级,介绍一种利用高压风去除皮带运输机返程皮带上的残余物料的清扫装置,解决了传统清扫器的问题,大幅度节省了运行成本,效果上有明显的优点。     

基于电缆网时域反射信号检测与预处理技术研究

运行电缆网时域反射信号检测与预处理技术研究。应用小波分析变换电缆网时域反射信号的奇异点进行检测与预处理误差较大,采用小波分析的反射波消噪技术提出一种小波分析最优分解层数的自适应确定函数算法。     

直升机尾桨涡环状态研究

介绍了直升机尾桨涡环状态的现象,分析比较了三种涡环判据的应用特点。针对某型直升机尾桨涡环状态,计算了其侧飞临界速度和临界悬停回转角速度。描述了实际飞行中直升机进入尾桨涡环状态的现象,提出了改出尾桨涡环状态的方法。     

The Output Effect of a Transition to Price Stability When Velocity Is Time Varying

This paper explores the effect of time‐varying velocity on output responses to policies for reducing/stopping inflation. We study a dynamic general equilibrium model with sticky prices in which we introduce time‐varying velocity. Specifically, we endogenize time‐varying velocity into the model developed by Ireland (1997) for analyzing optimal disinflation. The nonlinear solution method reveals that, depending on velocity, the “disinflationary boom” found by Ball (1994) may disappear even under perfect credibility and that early output losses may be much larger than previously thought. Indeed, we find that a gradual disinflation from a low inflation may even be undesirable.     

China's search for the future: A genealogical approach

This paper is a dialectical inquiry, presenting a genealogy of, China futures discourses and visions from ancient times through to the, present. It uses both structural and macrohistorical based approaches. The identified worldviews are placed in their broader historical, epistemes; asked why change has occurred, how it fits within patterns of, history and what kind of futures are offered. It is unique in that I use, the futures triangle methodology to discuss the “pulls” of the future in, each historical era with the corresponding “pushes” of the present and, “weights” of the past. The article concludes with a theory of futures in, Chinese history and looks at which philosophies are likely to play a role, in the possible futures of China. The aim is to highlight which visions, and images have been victorious is affecting the present and influencing, the future.     

290m刚构桥三角区施工期间支架及上弦箱梁的受力分析

北盘江大桥主桥为(82.5+220+290+220+82.5)m预应力混凝土斜腿连续刚构桥。受下弦梁段浇筑、扣索张拉、预应力张拉等工序影响,该桥三角区受力复杂。针对此问题,结合三角区施工工艺,采用通用有限元软件建立三角区模型,分别对不考虑下弦箱梁变形及扣索和上弦箱梁预应力张拉影响、不考虑下弦箱梁变形及扣索张拉影响、考虑各工序影响的三角区支架及上弦箱梁进行全过程受力分析。分析结果表明,扣索张拉及下弦箱梁变形对上弦箱梁受力影响较小;随着扣索的张拉,各排支架轴力增大;但随下弦箱梁浇筑、上弦箱梁预应力筋张拉,各排支架轴力又将有所降低;受上弦箱梁预应力筋的张拉影响,第2~8排钢管支架在整个三角区施工过程中出现了脱空现象。     

角速度传感器误差校正研究

某角速度传感器的输入与输出成近似线性关系,测量输出的电压值即可得到目标运动的角速度。为了提高测量的精度,通过对角速度传感器零位和灵敏度的误差进行校正,可得到更为精确的目标运动角速度。实验表明,该校正方法能有效提高角速度传感器的测量精度,有一定的实用性。     

Threatened Species as Public Goods and Public Bads

This paper discusses Pareto efficient allocations of an environmental commodity, which is both a public good and a public bad, with an application to the Scandinavian problem of conserving wild predators that are killing semi-domesticated reindeer. The paper begins by briefly outlining this conflict. This is followed by a theoretical analysis employing a diagrammatic tool called the Kolm triangle, which is an analogue of an Edgeworth box in an economy with a public good. Bargaining, Pareto improving reallocations and the shape of the Pareto set are discussed, using a simple model, where one of the agents is involountarily contributing to a public good. The paper concludes with an analysis of income-loss compensations and incentives for illegal hunting of predators.     

个体差异、企业特征、制度保护与流动人口社会保险可及性——基于“福利三角”理论模型的实证研究

"福利三角"理论是现代社会政策研究的重要范式,其也可运用于经验研究。本文基于"福利三角"理论视角,从个体差异、企业特征、制度保障三个维度,利用南开大学"2013年流动人口管理和服务对策研究问卷调查"数据,对流动人口社会保险可及性及其影响因素进行实证研究。分析发现,在个体特征方面,受教育程度、工作年限等对流动人口人力资本具有关键影响的因素,企业性质、行业类型等企业特征,劳动合同、合同协商、工会等制度保障因素对流动人口社会保险可及性具有显著影响。在此基础上,应提高流动人口社会保险可及性。