400 research outputs found

    Review for children\u27s understanding of additive commutatity

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    Research of Network Security Risk Accessment based on Cloud Model

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    互联网的飞速发展给人们的工作和生活带来了便利,然而网络安全事故频发,无疑给网络世界蒙上了一层阴影,一旦重要的私人信息在网络安全事故中被泄露的话,就有可能造成非常严重的后果,不仅有可能是财产上的损失,甚至有些不法分子还会收集和利用这些信息对人身造成伤害,因而网络领域的安全问题已经引起了人们的广泛的关注。而网络安全风险评估是该领域的最基础的工作,能够帮助我们对于网络的整体状况有一个大致的了解,从而能够为如何改善网络,提升网络的安全性能提供可靠的参考,是一个值得研究的方向。 目前使用的网络安全风险评估理论和方法中,历史资料扮演了十分重要的角色,整个评估的过程需要对历史资料进行仔细的研究,并且评估结...The rapid development of Internet brings convenience to our work and life. However , when we hear about network security events , we become anxious. As a technology to make network information system more secure and robus, risk assessment not only takes many security factors such as threatens,assets,vulnerabilities into account,but also helps administrators take an active attitude to identify thos...学位:工学硕士院系专业:信息科学与技术学院_计算机系统结构学号:2302010115305

    Study on Rebuilding of China's Criminal Identification System

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    鉴定制度改革是近年来司法改革领域的热点问题。刑事鉴定制度作为司法改革的重要组成部分,理应成为改革的重要内容之一。但是从现实来看,涉及刑事鉴定领域的制度改革及实证研究相对较少,远远不能满足司法实践的需要。如何从全局出发,理性地思考和设计未来我国刑事诉讼中鉴定制度的总体构架,切实建立起有中国特色的符合公正效率原则的独立的司法鉴定制度,是未来研究的首要课题。而建立健全合法、公正、有效、科学的刑事鉴定制度,并对各项鉴定工作进行有效的指导,促成鉴定体系的良性运行也是理论研究和司法实践的重要目标。 本文共分为三章,分别是: 第一章为我国刑事鉴定现状的阐述。主要从两个方面进行,第一个方面是刑事鉴定的性质...The reform of identification system is a hot issue in the field of judicial reform in recent years. Criminal identification system as an important part of the judicial reform should become an important part of the reform. But from a practical point of view,there is not much research on the reform of criminal identification system and the empirical study,which can not meet the needs of judicial pr...学位:法律硕士院系专业:法学院法律系_法律硕士(JM)学号:X200912012

    镍钛形状记忆合金薄膜在基底约束下的马氏体相变行为及尺度效应

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    利用基底曲率方法测量薄膜应力随温度的变化曲线来研究镍钛形状记忆合金薄膜在基底约束下的马氏体相变行为。通过使用不同类型的基底材料,利用镍钛薄膜和基底材料的热膨胀系数不匹配,获得薄膜材料中不同的残余应力水平,从而研究薄膜应力水平对相转变行为的影响规律。同时对于不同厚度的镍钛合金薄膜,合理选择退火条件,有效控制晶粒尺寸使其远远大于薄膜厚度,使得通常获得的多晶薄膜的行为接近具有各种晶粒取向贡献的单晶薄膜,从而研究薄膜厚度对相变行为的影响

    Dynamic VaR study adjusted by Liquidity Risk:Based on DCC-MVGARCH

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    随着基础金融工具及其衍生品越来越多元化,金融市场的不确定性因素也越来越多,因而投资者的风险也就越来越高。市场风险是最主要的风险之一。20世纪90年代以来,尤其是1998年长期资本管理公司(LTCM)的破产和此次金融危机,使得流动性风险也越来越被众多监管机构和机构投资者所关注。如何准确识别和度量这些风险,是投资者风险管理的第一步。VaR是一个用于描述和刻画市场风险的有力工具,如何把流动性风险融入到传统VaR中,就成为国内外学者和实务工作者关注的焦点。 国内外现存的各种拓展VaR模型大多针对的是单个资产,很少研究股票组合,同时也只有收益率的部分为动态的,而流动性的部分仍为静态的。由于机构投资者通...With more and more diverse financial instruments, their derivatives and financial market uncertainty, the risk of investors is also increasing. Market risk is the most important one of the risks. Since 90s, 20th century, especially the bankruptcy of the Long Term Capital Management (LTCM) in 1998, and this financial crisis, many regulatory agencies and institutional investors have paied more and m...学位:经济学硕士院系专业:经济学院金融系_金融工程学号:1562007115146

    Analysis of financial statements of Rebecca Hair Products Co., LTD

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    上百年来,“找头发换针”的叫卖声伴随了几代人的回忆。早在明末清初之时,许昌就开始为西方国家提供制作假发的原材料人发,并逐渐成为发制品生产加工中心。如今,发制品早已成为一种时尚消费品,被誉为“头上的时装”,发制品生产也成为许昌当地的支柱性产业,河南瑞贝卡发制品股份有限公司便是这一支柱产业中的龙头企业。 本文选取河南瑞贝卡发制品股份有限公司作为案例研究的对象,在对瑞贝卡公司的相关行业情况及公司战略进行解读的基础上再对财务报表进行研究,最后对公司发展的前景做出了分析。瑞贝卡公司作为世界最大的发制品生产企业,也是A股市场上唯一的发制品上市公司,之前却一直不为国人所知,2007年强势回归国内市场后才逐...Xuchang began to provide hair to western countries to make hair products as early as the transitional period of Ming and Qing dynasty. Then it becomes hair products production center. Nowadays hair products already became a kind of fashion consumer goods and be known as “head fashion”. The production of hair product also becomes the backbone industry of Xuchang. Rebecca Hair Products Co., LTD is o...学位:工商管理硕士院系专业:管理学院工商管理教育中心(MBA中心)_工商管理硕士(MBA)学号:1792009115082

    Surface morphology and deformation mechanism of single crystal copper treated by laser shock peening

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    To study the relation between surface morphology and deformation mechanism of the target material under the shock, a flexible boundary loading, in laser shock peening(LSP), the macroscopic and microscopic surface morphology of a single crystal copper treated by LSP was investigated. The optical profilometer shows a 200-μm-deep pit forms on the shocked surface under LSP. The optical microscopy shows a set of parallel slip bands appear at the center of the shocked region and many vertical cross slip bands appear at the edge of shocked region. This indicates a large plastic deformation occurs by means of slip for the single crystal copper under LSP and the distributing features of slip bands correspond to the spatial distribution of the shock pressure. The results confirm that the surface morphology of materials under LSP can reflect the deformation mechanism and it can be a new method of studying the deformation mechanism of materials under LSP. © (2014) Trans Tech Publications, Switzerland

    Determination of polycyclic aromatic hydrocarbons(PAHs) in tea using solid phase microextraction coupled gas chromatography mass spectrometry

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    本文优化了萃取条件,建立了顶空-固相微萃取(HS-SPME)、气相色谱-质谱测定茶叶中4种多环芳烃的方法.茶叶中多环芳烃含量和对应的信号强度在0.3~150mg kg~(-1)范围内呈良好的线性关系,检出限为0.1~0.2mg kg~(-1),回收率在72.6%~102.4%之间;茶汤中含量和对应的信号强度在0.01~10mg kg~(-1)范围内呈良好的线性关系,检出限为0.005~0.01mg kg~(-1),回收率为76.4%~103.6%.In this study, GC-MS coupled head-space solid-phase microextraction(HS-SPME) was applied to detect 4 kinds of PAHs in tea and in tea infusion. After the optimization of the experimental consideration, the linear ranges for the PAH4 signal intensity and their concentrations are found to be 0.3–150 and 0.01–10 mg kg~(-1). The detection limit is 0.1–0.2 and 0.005–0.01 mg kg~(-1), with recovery of 72.6%–102.4% and 76.4%–103.6%, respectively

    一种车载网络中基于簇的时隙碰撞解决方法

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    车载自组织网络(VANETs)是一种传统移动自组织网络在道路交通领域中的一种特殊应用。通过将车载网络中的车辆节点进行分簇,把整个车载网络分成若干个小型的自组织网络,使网络的管理与维护变得更为简单。但是,当两个独立的簇相互靠近时,碰撞问题就难以避免。本论文针对基于IEEE1609.4标准的分簇网络,提出一种解决两簇时隙碰撞问题的方法。当然,研究者们可以将该方法延伸到其余协议上

    城市教育设施分布引起的居住空间分异研究——基于厦门市厦港、滨海街道小学“学区房”分析

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    教育设施作为城市公共服务设施的重要组成部分,其不均衡分布是城市居住空间分异的影响因素之一,引发了社会上对于\"学区房\"的广泛关注。基于对居住空间分异的理论研究,结合地方政策分析,对厦门市厦港街道、滨海街道小学学区的居住空间分异进行实证研究。从收入水平、年龄阶层、社区邻里以及单位和非单位人群等方面探讨居住空间分异情况,据此在入学制度、供需平衡等方面提出相应的建议
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