Optimal arrangement of viscoelastic dampers for seismic control of adjacent shear-type structures

The optimal arrangement of viscoelastic dampers (VEDs) used to link two adjacent shear-type structures under seismic excitation was investigated. A two-step optimal design method is proposed. First, optimal parameter expressions of the Kelvin model are used to calculate the optimal stiffness and damping coefficient of the VEDs. Then, using the two-step optimal design method, taking the quadratic performance index as the optimization objective, the optimal arrangement of the dampers is determined. General rules about the optimal arrangement of the VEDs were obtained. The results show that the placement of only one damper between two adjacent shear-type structures should be avoided; if more than one damper is used, they should be distributed on the top and lower floors of the structures. Optimization of the number of dampers had little effect on response reduction. The most important factor was the optimization of the placement of the dampers. Through comparative study, for buildings of equal and unequal heights, the optimal parameters of dampers from parametric studies were shown to match the theoretical results for different numbers and placements of dampers. The level of response reduction was shown to be sensitive to the damping coefficient of the dampers.     

Classroom choice-making for Chinese master’s students: choice,motivation and learning contexts

ABSTRACT

Under the framework of self-determination theory, choice is a supporting factor for autonomy in the classroom. The provision of choice in the classroom is a distinct feature of higher education, through which students experience a shift from mandatory tasks to those are more learner-controlled. This study explores Chinese master’s students’ perspectives on choice and the relationship between choice and motivation, also, compares the choice-making opportunities in different learning contexts (China vs. UK). 60 Chinese master’s students, studying in China and the UK, participated in this study. The findings of this study indicate that most master’s students hold a positive attitude towards classroom choice, considering choice contributes to increased learning motivation in the classroom in most cases. Then, limited choices may not automatically decrease students’ motivation and students studying in China possess fewer opportunities for choice-making than students in the UK, which is influenced by the social and academic culture.     

“Putting Patients First”: Systematically Distorted Communication and Merck's Marketing of Vioxx

An estimated 27,000–60,000 patients died while taking Merck's drug Vioxx between 2000 and 2004. This essay uses Deetz's treatment of systematically distorted communication and Nilsen's significant choice to analyze Merck's communication about the drug. The company claimed publicly to be forthright about Vioxx's safety. The article shows, however, that Merck systematically distorted communication through neutralization, topical avoidance, and disqualification in ways that thwarted physicians’ and patients’ abilities to make an informed choice about Vioxx. The analysis shows that Merck employees’ consent to economic priorities framed these communication practices as legitimate and rational within the organization. The same practices, however, appeared socially irresponsible to members of the scientific community outside the company. In contrast to Merck's practices, the essay offers more participatory communication applications that uphold companies’ moral obligation to their stakeholders.     

The Interaction of Functional and Dysfunctional Emotions During Balance Beam Performance

The interaction between functional and dysfunctional emotions, as one of the major tenets of the Individual Zones of Optimal Functioning (IZOF) model (Hanin, 2000), was studied in a sport specific setting. Fourteen female gymnasts performed three attempts of a compulsory balance beam routine at three different heights. Heart rate and self-report of functional and dysfunctional emotions were measured during each routine. These data revealed the effectiveness of inducting emotions by manipulating height. Also, performance decreased on the most challenging condition, (i.e., the first attempt on the highest height). Moderated hierarchical regression analysis revealed a significant interaction between functional and dysfunctional emotions only when the dysfunctional emotion level was low.     

Exercise science and health-enhancing physical activity

Although technology has now infiltrated and prompted evolution in most mass participation sports, the advances in bat technology in such sports as baseball and cricket have been relatively minor. In this study, we used a simple finite element modelling approach to try to shed new light upon the underlying mechanics of the bat-ball impact, with a view to the future optimization of bat design. The analysis of a flexible bat showed that the point of impact that produced the maximum post-impact ball velocity was a function of the bat's vibrational properties and was not necessarily at the centre of percussion. The details of the analysis agreed well with traditional Hertzian impact theory, and broadly with empirical data. An inspection of the relative modal contributions to the deformations during impact also showed that the position of the node of the first flexure mode was important. In conclusion, considerable importance should be attached to the bat's vibrational properties in future design and analysis.     

Hierarchical confirmatory factor analysis of the Flow State Scale in exercise

In this study, we examined the factor structure and internal consistency of the Flow State Scale using responses of exercise participants.This self-report questionnaire consists of nine subscales designed to assess flow in sport and physical activity. It was administered to 1231 aerobic dance exercise participants. Confirmatory factor analyses were used to test three competing measurement models of the flow construct: a single-factor model, a nine-factor model and a hierarchical model positing a higher-order flow factor to explain the intercorrelations between the nine first-order factors. The single-factor model showed a poor fit to the data. The nine-factor model and the hierarchical model did not show an adequate fit to the data. All subscales of the Flow State Scale displayed acceptable internal consistency ( f > 0.70), with the exception of transformation of time ( f = 0.65). Collectively, the present results do not provide support for the tenability of the single-factor, nine-factor or hierarchical measurement models in an exercise setting.     

矩阵方程AXA~T+BYB~T=C的对称最小二乘解

建立了一种求矩阵方程AXAT＋BYBT=C对称最小二乘解的递推算法,对任意的初始对称矩阵,经过有限步迭代得到它的对称最小二乘解.若选取特殊的初始矩阵,通过递推算法得到的解就是极小范数对称最小二乘解.而且,对给定的任意矩阵,通过对方程的变形能得到它的最佳逼近对称解.     

What Factors Determine the Uptake of A-level Physics?

There has been much concern recently in the UK about the decline in the number of students studying physics beyond age 16. To investigate why this might be we used data from a national database of student qualifications and a multilevel modelling technique to investigate which factors had the greatest impact on the uptake of physics at Advanced Level (A-level) in a particular year. Each factor of interest was entered into a separate model, while accounting for prior attainment and gender (both well-known predictors of A-level uptake). We found that factors associated with greater probability of uptake included better attainment in physics (or combined science) and maths qualifications at age 16 in comparison to other subjects, and (for girls only) attending an independent or grammar school. While it is difficult to address these factors directly, the results imply that more needs to be done to improve relative performance at General Certificate of Secondary Education, perhaps by increasing the supply of specialist physics teachers at this level and to overcome the perception (especially among girls) that physics is a particularly difficult subject.     

现代远程教育中学习者选择网上媒体的探讨

现代远程教育机构为学习者提供了丰富的网上媒体。学习者对网上媒体的使用情况成为远程教育机构关注的重点。本文用任务技术匹配理论、技术采纳理论分析远程教育学习者选择网上媒体的行为,研究表明网上媒体与学习内容是否匹配,学习者感知网上媒体的易用性、有用性,学习者是否通过考试,学习者的个体特征等对网上媒体的选择有重要影响。