共查询到20条相似文献，搜索用时 31 毫秒
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为了解高温气候条件下重载水泥混凝土路面结构受力特征,本文以福建省高温气候条件与重载交通特性为研究实体,采用三维有限元程序EverFE2.24计算高温气候下重载交通对路面的影响.研究结果表明,高温气候下重载交通对水泥混凝土路面造成的不利影响,降低了路面寿命.各参数对面板的受力敏感性分析结果表明,增加面板的厚度、提高地基刚度及设置传力杆,均能有效改善面板的受力性能,其中增加面板厚度带来的受力性能改善的效果最显著.此外,增大基层厚度,在减少了车辆荷载应力的同时,也增大了面板的温度应力,因此对于改善面板受力特性不一定有效. 相似文献
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Surface contact explosion experiments have been performed for the study of dynamic response of the hard-soft-hard sandwich panel under blast loading. Experimental results have shown that there are four damage modes, including explosion cratering, scabbing of the backside, radial cracking induced failure and circumferential cracking induced failure. It also illustrates that the foam material sandwiched in the multi-layered media has an important effect on damage patterns. The phenomena encountered have been analyzed by the calculation with ALE method. Meanwhile, the optimal analysis of foam material thickness and position in the sandwich panel were performed in terms of experimental and numerical analysis. The proper thickness proportion of the soft layer is about 20% to the thickness of sandwich panel and the thickness of the upper hard layer and lower hard layer is in the ratio of 7 to 3 under the condition in this paper when the total thickness of soft layer remains constant. 相似文献
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针对热塑性长纤维增强复合材料模板体系在剪力墙混凝土浇筑过程中的实测,探讨其简化计算模型的选取。现场实测结果表明:在混凝土侧压力和施工荷载的作用下,面板主要处于受拉状态,平面上两个方向的应变比为0.65～1.79, 说明该塑料模板的简化验算,除整体按双向板进行验算外, 尚应针对面板、水平肋、垂直肋等分别进行验算。 相似文献
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Petros J. Axaopoulos Konstantinos N. Moutsopoulos Michael P. Theodoridis 《European Journal of Engineering Education》2012,37(1):39-48
An experiment using real hardware and under real test conditions can be remotely conducted by engineering students and other interested individuals in the world via the Internet and with the capability of live video streaming from the test site. The presentation of this innovative experiment refers to the determination of the current voltage characteristic curve of a photovoltaic panel installed on the roof of a laboratory, facing south and with the ability to alter its tilt angle, using a closed loop servo motor mounted on the horizontal axis of the panel. The user has the sense of a direct contact with the system since they can intervene and alter the tilt of the panel and get a live visual feedback besides the remote instrumentation panel. The whole procedure takes a few seconds to complete and the characteristic curve is displayed in a chart giving the student and anyone else interested the chance to analyse the results and understand the respective theory; meanwhile, the test data are stored in a file for future use. This type of remote experiment could be used for distance education, training, part-time study and to help students with disabilities to participate in a laboratory environment. 相似文献
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采用ANSYS结构分析程序的四节点壳单元对压型钢板及等效的正交各向异性板进行了线弹性分析,结果表明在压型钢板受力蒙皮作用的有限元分析中正交各向异性板可以取代真实压型板进行分析,并得到了等效的正交各向异性板的弹性常数计算公式。 相似文献
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白云 《河南师范大学学报(哲学社会科学版)》2005,32(3):75-79
专家组程序在WTO争端解决机制中居于核心地位,其影响非常巨大。随着专家组程序的运行,很多缺陷和不足也暴露出来,本文着重就专家组的组成、专家组程序的法律特征、专家组的职能、专家组程序暴露出来的问题及其完善与发展几个方面进行探讨并提出一些个人的观点。 相似文献
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The blast resistance of structures used in buildings needs to be investigated due to the increased threat of a terrorist attack. The damage done by Composition B or Powergel to steel fibre reinforced reactive powder concrete (SFRPC) panels and ordinary reinforced concrete (RC) panels of equivalent static flexural strength is compared. A 0.5 kg charge was detonated at a distance of 0.1 m from the 1.3 m×1.0 m×0. 1 m (thick) panels, which were simply supported and spaning 1.3m. Dynamic displacement measurements, high-speed video recording and visual examination of the panels for spall and breach were undertaken. The SFRPC panels withstood the bare charge blast better than the reinforced ordinary concrete panels. Neither type of panel was breached using a 0.5 kg charge. The RC panel exhibited more spalling when Composition B was used. Under successive Composition B loading conditions, the RC panel was breached. In comparison the SFRPC panel was not breached. Exposure to fragmenting charge loading conditions confirmed these performance differences between the SFRPC panel and the reinforced ordinary concrete panel. 相似文献
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无人驾驶汽车由于无须乘坐者对车辆实施监控,只能通过汽车仪表面板的显示了解车辆信息,其人机界面的设计就尤为重要。对无人驾驶汽车的仪表面板的人机界面设计原理作了简要阐述,就显示装置在自动观光汽车面板中的选用、设计、布局作了简要探讨。 相似文献
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Using data from a representative panel of 1,000 Minnesota youth, this paper explores "helpfulness" in 2 spheres of adolescents' lives: the home and paid work settings. We examine the social structural conditions under which helpful behaviors are elicited, the interrelations of helpfulness and competence across 2 years of middle adolescence, and whether social circumstances moderate the effects of helpfulness on competence. Both boys' and girls' helpfulness in the home is responsive to family need. Furthermore, helpfulness at work and girls' competence are reciprocally related. We find evidence that the effects of helpfulness depend on the helper's motivations and the act's meaning, as shaped by the social context. Girls' competence is diminished by helpfulness in the home under conditions of poor father-daughter relationships and coercive maternal control. 相似文献
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张文汇 《伊犁教育学院学报》2002,15(1):95-96
电工测量在电力系统中占有很重要的地位，而合理的使用电工仪表是保证测量准确性的前提，因此，在测量中要正确选用仪表，合理选用仪表的量程，并应该注意仪表内阻测量造成的误差。 相似文献
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Jeffrey W.?Gilger A Special Topics Panel of The Dyslexia Foundation 《Annals of dyslexia》2017,67(2):109-113
A panel of practioners and researchers convened to consider how to advance a broader understanding of the neurocognitive profile of people with dyslexia. While a great deal of research has been conducted on the reading process, the panel recognized that the “dyslexia brain” may be unique in other ways as well. In particular, the panel focused on complex nonverbal/spatial skills and correlated attributes such as career choice. The conclusion of the panel was that there is more to be learned about how people with dyslexia reason spatially and how these qualities manifest in academic, personal, and career behaviors. 相似文献
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Jerome C. Clauser Melissa J. Margolis Brian E. Clauser 《Journal of Educational Measurement》2014,51(2):127-140
Evidence of stable standard setting results over panels or occasions is an important part of the validity argument for an established cut score. Unfortunately, due to the high cost of convening multiple panels of content experts, standards often are based on the recommendation from a single panel of judges. This approach implicitly assumes that the variability across panels will be modest, but little evidence is available to support this assertion. This article examines the stability of Angoff standard setting results across panels. Data were collected for six independent standard setting exercises, with three panels participating in each exercise. The results show that although in some cases the panel effect is negligible, for four of the six data sets the panel facet represented a large portion of the overall error variance. Ignoring the often hidden panel/occasion facet can result in artificially optimistic estimates of the cut score stability. Results based on a single panel should not be viewed as a reasonable estimate of the results that would be found over multiple panels. Instead, the variability seen in a single panel can best be viewed as a lower bound of the expected variability when the exercise is replicated. 相似文献
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不确定条件下的最优教育选择——基于期权模型的实证研究 总被引：2，自引：0，他引：2
杨娟 《北京师范大学学报(社会科学版)》2008,(4)
教育投资不仅关系到个人一生的职业发展,还涉及到就业、稳定、资源分配等一系列社会问题,是各级政府都密切关注的问题。然而,教育投资存在很高风险,即投资收益存在较大的波动性和较宽的分布范围,阻碍个体作出合理教育投资的抉择。由于风险估计的复杂性,教育选择的研究一般都不考虑风险。借用金融的期权理论模型对风险的估算可以很好地评估个人预期收益的不确定性,进而推出个人的最优教育选择。采取工资微分和捆绑期权这两处巧妙的处理,就能使标准的期权公式适应教育投资的特殊性,便于实证检验在不确定条件下的最优教育投资成本。基于英国的面板数据估算结果显示,预测的最优高等教育参加人数与实际人数很接近,说明风险确实对于人们的教育选择有很显著的影响,尤其是对于普通高等学历来说更是如此。而参加职业高等教育的学生会更多考虑非货币因素。此外,对各学历的预测值均高于真实值,说明可能有部分群体由于得不到全面的信息而没有作出最优教育选择。 相似文献
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A growing literature documents significant differences in college student outcomes between adjunct and full-time instructors, although less is known regarding the causes of these differences. Many existing studies implicitly treat instructor quality—as measured by an instructor’s effect on student outcomes—as a fixed trait. However, instructor quality itself may be sensitive to employment rank, given that adjunct and full-time instructors work under very different conditions. Understanding mechanisms driving these differences is important for informing policy decisions aimed at improving student outcomes. Using panel data on first-semester students at public colleges in Arkansas, this paper first establishes that adjuncts have significantly worse student outcomes than full-time counterparts on a number of metrics. Next, I investigate mechanisms underlying differences in outcomes across instructor rank. I take advantage of the panel structure of the data and use an instructor fixed effects approach to provide evidence that within instructors, student outcomes improve when the instructor is full-time, compared to when the instructor is an adjunct. Results indicates improving student outcomes is about more than just getting better instructors, since instructor quality is not a fixed trait. Rather, factors like an instructor’s conditions of employment and teaching and working environment may affect the outcomes of their students. 相似文献
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针对信息显示技术专业的特点,建立了平板显示技术的核心——薄膜晶体管的工艺实验,并且以薄膜晶体管工艺为主线,分模块建立了平板显示技术实验平台,开设了从显示技术基础到显示系统的实验系列.平板显示技术工艺实验平台在教学与科研、基础与创新、教师与学生之间建立起了一座桥梁. 相似文献