Influence of structure plane size on seismic response of soil-structure interaction     

姜忻良  张亚楠 《天津大学学报(英文版)》2013,19(5):345-350

The influence of the change of structure plane size on seismic response was studied for a soil-structure interaction system. Based on the finite element method, a soil-structure interaction calculation model was established to analyze the seismic response by changing the structure plane size and choosing different earthquake waves for different soil fields. The results show that when the natural periods of vibration for different structure plane sizes are close, under the same earthquake wave, the total displacement on the top layer of the structure and the foundation rotation displacement decrease with the increase of structure plane size, and the proportion of superstructure elastic selfdeformation displacement to the total displacement increases with the increase of structure plane size. While for different types of sites and seismic waves, under the horizontal and vertical seismic waves, the seismic responses of different plane sizes have a similar change rule.  相似文献   

Minimizing the Influence of Item Parameter Estimation Errors in Test Development: A Comparison of Three Selection Procedures     

Mark J. Gierl  Dianne Henderson  Michael Jodoin  Don Klinger 《Journal of Experimental Education》2013,81(3):261-279

In test development, item response theory (IRT) is a method to determine the amount of information that each item (i.e., item information function) and combination of items (i.e., test information function) provide in the estimation of an examinee's ability. Studies investigating the effects of item parameter estimation errors over a range of ability have demonstrated an overestimation of information when the most discriminating items are selected (i.e., item selection based on maximum information). In the present study, the authors examined the influence of item parameter estimation errors across 3 item selection methods—maximum no target, maximum target, and theta maximum—using the 2- and 3-parameter logistic IRT models. Tests created with the maximum no target and maximum target item selection procedures consistently overestimated the test information function. Conversely, tests created using the theta maximum item selection procedure yielded more consistent estimates of the test information function and, at times, underestimated the test information function. Implications for test development are discussed.  相似文献   

热载荷下梯度结构硬质合金的弹塑性响应     

黄自谦  李传新 《东南大学学报》2013,(4):463-466

采用有限元方法模拟了热载荷下梯度结构硬质合金的弹塑性响应．样品几何模型为二维梯度结构的轴对称圆柱体．通过引入约束因子构建了梯度材料的弹塑性本构方程．数值模拟表明：当材料温度从初始无应力的800℃下降到0℃时,在样品表面出现了压应力而在富钴区出现了拉应力;表面压应力的最大值为254MPa,富钴区拉应力的最大值为252MPa;在钴相浓度差等于或大于0．3时,钴相梯度区出现了明显的塑性流动;当温度从0℃上升到800℃时,总的塑性应变达到0．0014．塑性流动有利于降低材料内部的热应力集中．  相似文献   

Perfectionism and Goal Orientations Among Chinese Gifted Students in Hong Kong     

David W. Chan 《Roeper Review》2013,35(1):9-17

Positive and negative perfectionism as well as four goal orientations were assessed in a sample of 315 Chinese gifted students in Hong Kong. These students tended to endorse positive perfectionism more than negative perfectionism and prefer learning and social goals over performance and avoidance goals. Learning and social goal orientations emerged as significant predictors in the prediction of positive perfectionism, whereas performance and avoidance goal orientations emerged as significant predictors for negative perfectionism. Implications of the findings for promoting healthy strivings for excellence through setting different goals are discussed.  相似文献   

Ambiguity as persuasion: The Vietnam Veterans memorial   总被引：3，自引：1，他引：2  

Sonja K. Foss 《Communication quarterly》2013,61(3):326-340

Visitors to the Vietnam Veterans Memorial generally are deeply moved by it—regardless of their positions on the Vietnam War itself. In this essay, five visual features of the memorial are identified that enable it to appeal to virtually all visitors: (a) It violates the conventional form of war memorials; (b) It assumes a welcoming stance; (c) It provides little information to the visitor; (d) It focuses attention on those who did not survive the war; and (e) It generates multiple referents for its visual components. The effectiveness of the memorial suggests that it may serve as a model for contemporary anti‐war rhetoric.  相似文献   

网络舆情的挑战与应对——以泉州市为例     

林宏丹 《闽西职业大学学报》2013,(4):45-50

网络舆情作为信息化与民主化发展的新兴舆论现象,对社会管理和意识形态产生极为深刻的影响,也带给执政党和政府全新的挑战和考验。针对福建泉州的网络舆情可能释放的负能量和政府监管不到位等问题,必须从领导、预警、研判、引导、法治、培训等方面探索构建完善的网络舆情应对机制,以有效地运用和管控网络舆情。  相似文献   

响应曲面法优化微波辅助提取海蓬子茎叶总黄酮的工艺研究     

扶庆权  陈昌云 《南京晓庄学院学报》2013,(3):29-35

对海蓬子总黄酮的提取工艺条件进行了优化,通过单因素试验考察乙醇浓度、料液比、提取时间、微波温度和微波功率对总黄酮得率的影响.在单因素试验的基础上,采用响应曲面法优化微波辅助提取海蓬子总黄酮的最佳工艺条件.结果表明,微波辅助提取海蓬子总黄酮的最佳工艺条件是：乙醇浓度60%（V/V）,料液比1∶40,微波时间9 min,微波温度60℃,微波功率500 W,此时海蓬子茎叶总黄酮得率达到6.06%,与模型预测值6.34%基本相同.  相似文献   

基于时频分析的裂纹转子碰摩故障特征研究     

陶海亮  左志涛  高庆  谭春青 《唐山学院学报》2013,(4):520-528

为研究转子系统耦合故障特性,采用有限元方法建立了含有横向裂纹、转静碰摩的非线性转子动力学模型。首先研究了不同转速下裂纹、碰摩单一故障下转子系统的振动响应,其次研究了两种故障耦合情况下系统的振动响应特征。采用波形图、FFT谱图、瞬时频率和Hilbert-Huang时频谱(HHS)相结合的方法对故障转子振动信号进行了分析。分析结果表明:运用多种时频分析相结合的方法可以较为全面地了解转子的故障特征,裂纹转子在1/5、1/3临界转速时会发生较为明显的5X、3X谐波,且裂纹的产生会导致响应幅值增大,从而引起更为严重的碰摩。   相似文献   

Rhetorical theory as message reception: A cognitive response approach to rhetorical theory and criticism     

William L. Benoit  Mary Jeanette Smythe 《Communication Studies》2013,64(1):96-114

Traditional rhetorical theory tends to adopt the rhetor's point of view, emphasizing invention of rhetorical messages, rather than the audience's reception and interpretation of messages. The audience is ordinarily conceptualized in humanistic rhetorical theory as a target, a source of expectations to guide the rhetor's invention, a means to accomplish the rhetor's ends, or even an obstacle. We argue that a more complete view of rhetoric should include the audience as a potentially active part of the process of persuasion. Accordingly, we propose to supplement our traditional theories of rhetoric by sketching a complementary view of rhetoric as the process of an auditor's processing and responding to messages. The inspiration for this conception, Petty and Cacioppo's Elaboration Likelihood Model, is sketched, and implications for rhetorical theory and criticism are discussed.  相似文献   

电路系统分析法     

王丹琦  黄根春  阿依夏木·力提甫 《中国科技纵横》2011,(4):193-194

本文对动态二阶电路系统进行了分析,通过变换域求解,总结出各种方法的优缺点及适用情况。  相似文献