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Search Results: 1 - 10 of 344972 matches for " 张志国 "
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恒加试验下复杂系统可靠度的估计与性质
The Estimation and Properties of Reliability for Complex System under Constant-Stress Accelerated Life Tests
 [PDF]

杨俊丽,
Statistics and Applications (SA) , 2012, DOI: 10.12677/SA.2012.12003
Abstract:

本文研究了恒加试验下,基于最小路径描述的复杂系统可靠度的估计问题。假设每个子系统的寿命分布为指数分布,且在恒加试验下,得到的每个子系统的寿命样本为定数截尾样本,在此条件下,本文给出了复杂系统的可靠度的估计及其渐近分布。

This paper studies estimation of the complex system described by minimal paths under the constant-stress accelerated life tests. Assuming that the product life time from each subsystem in the exponential distribution are type II censoring date under the constant-stress accelerated life tests. Under this condition, this paper gives the estimation and its asymptotic distribution of reliability of a complex system.

 

公平视角下优质教育资源配置审视与开发研究
Research on Survey and Development of High-Quality Education Resources Allocation from the Perspective of Fairness
 [PDF]

, 姜正
Advances in Education (AE) , 2015, DOI: 10.12677/AE.2015.54013
Abstract:
由人力资源大国向人力资源强国转变是我国未来十年教育发展的战略目标。优质教育资源的合理配置与开发则有利于这一目标的实现,从公平视角审视我国建国以来教育资源配置的演变过程及存在的问题可以帮助我们辩证地思考与解决教育资源配置与利用上存在效率与公平问题。
Transformation from a big country to a powerful country with huge human resources is the stra-tegic target of education development in the next ten years in China. Reasonable allocation and development of high-quality education resources are conducive to the realization of this goal. Re-viewing the evolution process of education resources allocation and the problems existing from the perspective of fairness since the founding of the People’s Republic of China can help us make dialectical thinking and find ways to solve the problems in educational resources allocation and utilization.
活性炭烧结机烟气有害成分协同处理技术

环境工程 , 2014, DOI: 10.13205/j.hjgc.201402025
Abstract: 阐述了活性炭烧结机烟气有害成分协同处理工艺的基本构成和主要反应机理,该工艺包括多种污染物同步脱除、活性炭再生、硫酸生产等。活性炭工艺能够实现脱硫、脱硝、除尘、脱重金属、脱二恶英协同处理,利用活性炭技术处理烧结烟气不仅能达到国家新排放标准和特别排放标准,而且能满足国家环保进一步严格的要求。
谈近代黄河三角洲土地资源的开发利用

中国农业资源与区划 , 1991, DOI: 10.7621/cjarrp.1005-9121.19910503
Abstract: 近代黄河三角洲是指以山东的东营市垦利县的宁海为顶点,东临渤海,北起套尔河口,南至溜肋沟,约5450平方公里,为扇形冲积平原。是我国最年轻,开发潜力较大的一块宝地,也是山东省重点开发的地区之一。本文试图从土地资源的农业开发利用角度,对该区的发展进行探讨。
新型超硬材料BC2N的第一性原理研究
First principles investigation of novel superhard BC2N

,,
- , 2015,
Abstract: 应用基于粒子群优化算法的卡里普索(CALYPSO)晶体结构预测方法, 我们发现了一种新型的具有四方结构的BC????2??N的同素异形体, 空间群为??I??4/??MMM??. 利用基于密度泛函理论的第一性原理计算方法对该新型BC????2??N结构的电子能带结构、 态密度、 以及弹性性质展开了深入的研究. 计算结果发现: 此BC????2??N结构动力学稳定, 并且具有较大的体弹模量 (354??4 GPa) 和剪切模量 (375??5 GPa); 同时, 理论计算还表明该结构是一个带隙宽度为2??16 eV的直接带隙半导体, 其维氏硬度值可达到65??6 GPa. 因此, BC????2??N有望成为一种潜在的新型超硬材料和发光材料. 本工作将为人们探索新型的超硬材料提供一定的理论依据.
Using CALYPSO crystal structure prediction method via particle swarm optimization, we found a novel tetragonal BC????2??N with the space group??I??4/??MMM??. The band structure, electronic density of states, elastic constants, and bulk modulus of BC????2??N carbon were investigated using first principles calculations based on density functional theory. The present results reveal that BC????2??N is dynamically stable, and simultaneously posses a high bulk modulus of 354??4 GPa and a high shear modulus of 375??5 GPa. Furthermore, the electronic structure calculations show that it is a direct semiconductor with a band gap of 2??16 eV, and the Vickers hardness value of I 4 carbon is 65??6 GPa. The results adequately indicate that BC????2??N maybe a potential superhard material. Our work may provide some theoretical guidance toward exploring novel superhard materials
隧道冻结法施工引起地表沉降的数值分析
向东,
力学与实践 , 2008, DOI: 10.6052/1000-0992-2006-493
Abstract: 利用ADINA软件针对某工程实例隧道建立了有限元模型,然后对其开挖过程中地表沉降进行了预测并分析了隧道及冻结壁的应力与位移场,其结果与工程实测值相符;在此模型基础上,对隧道水平局部冻结法施工引起地表变形的相关因素进行了模拟分析,结果表明冻结法施工时,增加冻结壁厚度对地表沉降影响并不大,而采用扩大冻结壁的范围或减小隧道半径及埋深的方法可有效地控制地表沉降,这对今后的冻结法施工设计有借鉴意义.
不锈钢电解硫酸钠再生工艺应用实践
,李向东
环境工程 , 2014, DOI: 10.13205/j.hjgc.201403035
Abstract: 介绍了电解硫酸钠再生工艺技术和工艺流程,对电解硫酸钠再生工艺的影响因素进行分析和讨论。经过硫酸钠再生工艺后ρ(Cr6+)为2~3g/L、ρ(Me)为2~5g/L,满足酸洗工艺要求。该工艺有效解决了硫酸钠电解过程中金属离子超标、设备维护困难和环境污染等问题,同时实现硫酸钠再生利用,节约水资源。
某桥墩抗撞、防撞措施设计及分析
,禚一
铁道工程学报 , 2013,
Abstract: ?研究目的:随着船舶交通量和吨位的不断增加,跨越可通航水域的大跨桥梁结构的船舶抗撞、防撞设计问题已越来越多的引起了设计人员和专家学者们的重视。本文以某客运专线铁路的预应力混凝刚构连续梁特大桥为背景,对比国内外三种规范对该桥的船舶撞击力结果,并对防撞措施进行研究,以便能够给当前的桥墩防撞设计提供参考。研究结论:(1)采用国内《公路桥规》、《铁路桥规》及美国aashto三种规范对该桥的船舶撞击力进行计算,采用midas建立了全桥及桥墩模型,通过反复试算的方法得出了主墩能够承受的最大横桥向撞击力为13.62mn,大于国内规范的设计值9.62mn,均满足规范要求;(2)采用设置钢箱混凝土结构防撞墩和废旧轮胎相结合的防撞措施对主墩进行防护,防撞墩的最大抗撞力计算结果表明:每个钢箱混凝土防撞结构可分别承受55%和50%的横向、纵向撞击力设计值;(3)本文的研究成果为客运专线特大桥桥墩的抗撞和防撞措施设计提供了一定的理论依据,对桥墩防撞研究工作有一定的参考意义。
芽后型除草剂防除大花萱草田杂草试验
杜 娥?,
西北农林科技大学学报(自然科学版) , 2006,
Abstract: 大花萱草(hemerocallishybrida)移栽定植后,用不同浓度稀禾定、吡氟禾草灵进行了茎叶喷雾防除大花萱草田杂草试验,结果表明,稀禾定和吡氟禾草灵能有效防除禾本科杂草,对成株阔叶杂草防除效果很差;药后45d,1200~1800ml/hm212.5%稀禾定、1050~1575ml/hm215%吡氟禾草灵对禾本科杂草的防除效果均较好,对大花萱草植株安全无害。
大尺寸测量场在运载火箭装配中的应用探析
Application Analysis of Large Size Measurement Field in the Assembly of Launch Vehicle
 [PDF]

, 黄小春, , 秦春云, 李强,
Journal of Aerospace Science and Technology (JAST) , 2016, DOI: 10.12677/JAST.2016.43010
Abstract:
随着运载火箭的发展,传统的测量手段已无法满足新一代大型运载火箭的装配需求了。利用数字化测量设备构建数字化测量场,精确定位运载火箭部件的空间位置姿态,是新一代大型运载火箭数字化装配的前提和基础。本文以新一代大型运载火箭大部段数字化装配为研究对象,讨论了几种数字化测量场的建立方法,并提供了测量场的工程实际实施方法,为航空航天及其他领域大部件数字化装配中大尺寸测量场的构建提供了参考。
With the development of the launch vehicle, the traditional measurement methods have been un-able to meet the needs of the assembly of the new generation of large launch vehicle. It is the premise and the foundation of large launch vehicle digital assembly to build digital measurement field for accurate measurement of launch vehicle’s position. Several methods of building digital measurement field are discussed by using large launch vehicle digital assembly as the research object. And then, practical engineering implementation methods of building digital measurement field are proposed. A reference is provided for the construction of large size measurement field to digitize assembling large components in Aeronautics and Astronautics, etc.
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