Sensitivity analysis of stamping processes using various friction models appropriate for non-stationary contact problems

This paper looks at the sensitivity of thickness to variation of friction. The models of friction used are: the classic Amontons-Coulomb; a nonlinear pressure-dependent model proposed by Wriggers, vu Van and Stein; and a velocity-dependent model proposed by Molinari, Estrin and Mercier. They are coded in FORTRAN for use with finite element program ABAQUS. The contact problem is then formulated in the total Lagrangian formulation for contact between an elastic-plastic body and rigid tools. The variational (weak) form of the formulation is given and this is discretized by finite element method. To test and compare the models, one common metal forming processes is simulated: deep drawing of a square-cup. The sensitivity graphs showing each of the three friction models together is given at the end. One other conclusion although not major part of this work is that Amonton-Coulomb is not the best model suited for contact conditions in metal forming processes, because Wriggers et al. model and Molinari et al. model provide better results for modelling bends and corners.     

对完善大学英语分级教学模式的思考

大学英语分级教学是行之有效的教学模式。完善英语分级教学要从基础最差的学生入手,围绕学生、教材、教学方法、教师及管理等多方面提高,这也是促进分级教学改革推广的关键。     

基于差调制的扩频水印算法(英文)

扩展频水印技术是一种鲁棒的水印算法.如何提高扩频水印算法的鲁棒性是当前一大研究热点.充分利用图象的像素与其周围像素之间的差值的统计特性,利用差调制的方法嵌入水印信息,从而降低了原始图象对该水印算法鲁棒性的影响,来提高水印算法的鲁棒性.理论分析表明,该算法可以同时获得较小的误警和误拒概率,从而表明该算法有较好的性能.实验结果表明,该算法可以鲁棒地抵抗常用的攻击,如JPEG压缩、中值滤波、加噪声和图象大小调整.     

试论西方经济学的前提假设

西方经济学是建立在逻辑演绎基础上的一种理论。该文主要对西方经济学基本流派的演进与前提假设进行了初步的分析与研究 ,并提出了经济学作为一门科学 ,中西方应是相同的等基本观点     

试论投入产出模型的假设与局限

该文阐述了投入产出模型的假设条件 ,指出了其存在的局限性 ,并提出了改进的办法     

MATLAB在粗差探测中的应用

测量工作中,观测数据可能会带有粗差,从而给数据处理带来困难,因此必须及时的发现并剔除观测数据中的粗差。基于粗差检验的原理,利用MATLAB强大的计算能力用于粗差探测中,通过对实例从整体和局部进行假设检验分析,结果表明是有效的,可行的。     

Promoting the attitudes of nursing students towards refugees via interventions based on the contact hypothesis: A randomized controlled trial

A randomized controlled study was implemented on 90 nursing students in Turkey. The sample was divided into two groups: intervention and control group. The intervention group received education on refugee health and participated in a practical internship with refugees. Three scales were administered to the two groups at baseline (pre-test) and the end of intervention (post-test): "Xenophobia", "Attitude Towards Refugees" and "Intercultural Sensitivity". The three scale post-test scores of the intervention statistically significantly differed from control group and showed a statistically significant interaction between the groups and time in the two-way analysis of variance. The three scale post-test scores significantly differed from the pre-test scores in the intervention group, showing more relevant effects on xenophobia scale, two subscales of attitude towards refugees and intercultural sensitivity scale. The interventions based on the contact hypothesis improved nursing students' attitudes towards refugees.     

Understandingg in terms of information processing

Psychometric g, the general factor in individual differences in all types of tests and performances involving any mental ability, has much wider importance and implications than are encompassed by the field of psychometrics. It is argued that the nature of g must be understood in terms of information processes rather than in terms of the specific knowledge and skills that are seen in the content of conventional mental tests. The wide range of individual differences in g and disparities in the distribution of g in different subpopulations have important implications for understanding some of the major problems confronting public education.     

Exploring the de-stigmatizing effect of social media on homosexuality in China: an interpersonal-mediated contact versus parasocial-mediated contact perspective

The subject of homosexuality remains taboo in contemporary China, given that the public maintains a considerably negative attitude toward the subject. Recent Pew Research indicates that, on average, 21% of Chinese respondents believe that homosexuality should be accepted. However, parallel surveys of Internet users paint a different picture, as online surveys found a more liberal atmosphere toward homosexuality and same-sex marriage. The online and offline discrepancy in attitudes toward homosexuality begs the question of whether the Internet carries a stigma-reducing function in terms of views on sexual minority groups. Guided by the contact hypothesis and parasocial contact theory, the current study investigates the de-stigmatizing effect of the social media on homosexuality in China. A web-based survey with 980 social media users with a heterosexual orientation confirmed the positive role of interpersonal-mediated contact with lesbian and gay celebrities via social media venues in stigma reduction; but findings did not lend support to the parasocial-mediated contact hypothesis.     

信息个性化干预对网络辟谣效果的影响研究

[目的/意义]受逆火效应影响,辟谣信息常常达不到预期效果,从信息个性化角度提出抑制逆火效应的方法,为治理网络谣言提供新策略。[方法/过程]基于信息个性化技术及认知资源匹配假说理论,通过对个性化程度不同的辟谣信息进行分组实验,验证个性化程度高低对辟谣信息及信息受众处理辟谣信息所投入的认知资源的作用影响。[结果/结论]个性化程度高的辟谣信息能够显著影响信息受众心智网络中关于谣言的原有观念及相关知识修正,而这一作用产生的原因主要是由于信息个性化程度能够正向的影响信息受众自身的认知资源分配。