Optimization design and residual thermal stress analysis of PDC functionally graded materials

INTRODUCTION Polycrystalline diamond compacts (PDC), con-sisting of a polycrystalline diamond (PCD) layer on a WC-Co substrate, and having high hardness and abrasive resistance, are used in a variety of drilling and machining applications (Farhad, 2001; Sadi and Muzaffer, 2001). However, due to differences of thermal and mechanical properties in diamond and WC-Co substrate, residual thermal stresses develop in regions near the interfaces during fabrication. The diamond coating exhib…     

结构动力响应仿真计算

本文提出了一种新的求解结构动力响应的仿真算法。算法原理基于求解状态方程的增广矩阵法。该算法能够给出精度今人十分满意的计算结果。     

大田期烤烟根系生长与分布研究

使用微根区管成像观察技术辅以根系扫描成像观察技术,结合winrhizotron2007b root measurement图像分析系统,对烤烟根群结构和其他各项根系生长指标进行了研究。结果表明：烤烟根系主要由主根、侧根和不定根组成,63.4%的根系直径小于1.5mm;烤烟根系的生长在移栽后50 d前以根长延伸为主,移栽70 d后则以直径增粗为主;烤烟根系干物质量的增长在移栽后50-70 d和70-90 d出现两个高峰;烤烟根长密度在土壤中的分布,因纵、横方向和土层不同而表现不同的变化规律;烟草根系主要分布在0-20 cm土层,30 cm以下仅有少量分布,呈＂干＂型结构。     

社会化进程中身份团体与城市空间的协商——以2011年昆明市开斋节为切入点

在新的时空背景下,尽管由于经济主导的发展片面性难以被打破,但是随着国家和社会综合性提升诉求的强化,包括宗教信仰在内的文化同样被提上了发展日程。社会化进程的推进,已使城市中的宗教文化日趋采取与城市空间“协商”的方式而延展生命力。回族作为伊斯兰文化的承载体,因宗教信仰确立的“界限实体”的角色而使自身与文化传统逻辑紧密相扣,也因政治经济发展之需而让自身转换成为顺应城市之趋的某种“身份团体”。由于发起与参与角色的多元性,当下的开斋节在形式与内容上,已俨然构成一桩独特的历史事件。开斋节的举办在价值意义上难免遭遇在社会生活多面向交聚的十字路口,而陷入错综复杂的境况之中。     

“模因论”和“四空间模型理论”指导下的大学英语写作教学

英语写作是大学生英语听、说、读、写四种能力中比较薄弱的一项,针对这种状况,探讨了"模因论"启发下的英语写作教学,并用认知语言学中的"合成空间理论"的典型模型——"四空间模型理论"来分析模因写作教学,重新认识背诵、仿写和联想等一些传统方法对英语写作教学的重要作用,从而为大学英语写作教学提供一条快捷、有效的途径。     

信息意识概念的新构想与实证

信息意识是信息素养的重要组成部分,影响着信息主体的信息需求表达和信息行为,决定了信息的利用效果。当前关于信息意识的概念模糊,未能体现意识的流动性,使得该领域的研究和实践表层化、单一化,难以有效指导教学实施过程。明确信息意识概念有助于为相关研究提供一种可操作性的定义和交流理解的框架,为信息技术教学实践提供切实可行的指导思想。在心理学意识概念的基础上,结合信息素养的过程结构和目标结构思想,将信息意识界定为信息主体在信息认知活动中产生的感受及感受积累后形成的对信息活动的觉知能力,由信息行为觉知、信息情感、信息观点三要素和信息需求、信息应用、信息交流三阶段组成。探索性因素分析和验证性因素分析验证了该概念模型的合理性。     

宜春国际商贸城建筑空间设计

宜春国际商贸城是集家居、五金、建材、机电、百货、物流、会展、住宅等为一体的大型现代化专业商贸城,通过对商贸城建筑空间设计,展示现代城市商贸城的空间价值和品牌形象。     

Because the Night Belongs to Lovers: Occupying the Time of Precarity

While much of Occupy's political power is rooted in its spatial tactic, the movement's temporal realities are also key to understanding its complexities. This talk considers those realities, specifically turning to the night: a time when the spatial practice of occupying and the temporality of precarity find each other in a strange embrace. In the dark, new and unheard of demands emerge for the first time. At night, the fault lines of the movement rupture to the surface in new ways. It is also at night that those outside the camps, from the police, journalists, and the public, fix their gaze upon Occupy. Night also reflects the lived experience of precarity that Occupy and other activists and theorists have long mobilized against. This paper considers what new strategies of resistance loom in the realm of time.     

广义转移的应用

进一步研究广义转移的性质,证明了几个较深刻的结果,推广了Grün第一定理.     

Some remarks on Navajo geometry and piagetian genetic theory

Abstract

Some of the basic findings of Piaget's study on spatial knowledge in Genevan children are contrasted to Navajo spatial knowledge: there is no unique spatial «primitive» in Navajo knowledge and each and every notion is constituted in a different way than its Genevan correlate. The total system of Navajo knowledge shows a structure of interrelated and codetermining notions which differs markedly from the unilinear logical-deductive structure in the Piagetian model. In the second half of the paper the investigation turns to education and schooling. Here a position is taken against the (Piaget-based) rationalistic education policy one finds in the New Math-movement. Instead, some of the principles of Freudenthal are explored in a non-western setting: children should reinvent geometry on their own, in the terms of their culture. To that end, a curriculum for geometry teaching in a Navajo bicultural school is presented, focusing on the schooling in geometric concepts within the Navajo language and with full respect for the Navajo spatial representations in pre-school children.