一种高强汽车弹簧用钢的超高周疲劳研究

采用超声疲劳试验技术对一种高强汽车弹簧用钢进行了超高周疲劳试验。采用扫描电镜对失效试样进行断口分析,并对断口特征区域尺寸进行了测量。结果表明:在0~10~6循环周次内失效的试样断口起源萌生于试样表面;而在10~6~10~9循环周次内失效的试样断口萌生于试样次表面或内部,且断口呈现鱼眼状特征,随着夹杂物处应力强度因子幅的减小,疲劳寿命增加;而粒状亮面处的应力强度因子幅并不随寿命变化而明显变化,基本为一常数。弹簧钢的超高周疲劳S-N曲线呈现二次下降型特性,其S-N曲线的形态特征跟试样夹杂物尺寸密切相关。     

轧机主传动轴万向节失效分析及预防

某热轧厂R1下主传动轴万向接节在轧制SPHC钢种时突然发生断裂失效,导致现场停产16个小时。通过对万向节进行工况分析、断口分析、力学性能分析、化学成分分析、微观组织分析,发现指出万向节失效的原因为焊接缺陷,在气孔和夹渣处应力集中,导致断裂。据此提出了避免万向轴断裂失效的改进措施,避免类似事故的再次发生。     

20kHz和140Hz下高强汽车弹簧用钢的疲劳性能

对一种高强汽车弹簧用钢分别进行了常规疲劳和超高周疲劳试验。常规疲劳试验频率为140Hz,超高周疲劳试验频率为20kHz。采用扫描电镜分别对失效试样进行断口扫描分析。结果表明,140Hz和20kHz下的疲劳断口表现出相似的特征,在106循环周次内失效的试样断口起源萌生于试样表面;而高周和超高周疲劳试样断口起裂于试样次表面或内部,且断口呈现"鱼眼"状特征。另外,超高周疲劳断口裂纹源周围存在粒状亮面特征区。弹簧钢的超高周疲劳S/N曲线呈现二次下降型特性,其S/N曲线的形态特征跟试样夹杂物尺寸密切相关。140Hz得到的疲劳试验结果与20kHz下的超高周疲劳试验结果有着明显的偏差,弹簧钢频率效应明显。     

20钢螺钉断裂失效分析

以20钢螺钉为研究对象,采用断口观察、硬度测试和力学计算等方法,分析了某机器上20钢螺钉断裂失效原因。结果表明,螺钉以脆性断裂为主,螺钉中C含量极低,P含量偏高,组织为大量铁素体+少量片状珠光体,晶内与晶界有夹杂物;每个螺钉承受的平均剪切应力为447 MPa,因受载过大导致最终断裂失效。建议定期对螺钉进行更换或采用强度较高、韧性较好的材料。     

异径管开裂失效分析

对抚顺石化三厂白油车间一在役异径接管的开裂进行失效分析,包括开裂部件的断口观察、材质的化学成分分析、金相组织检验和力学性能测试。得出的结论是:异径接管在长期服役中,由于受迫振动而造成疲劳开裂。     

高压油管开裂失效分析

两件汽车柴油机高压油管在服役的过程中发生了断裂,断口学分析表明疲劳断裂是两件高压油管的主要失效机制。通过对油管表面缺陷、金相组织的观察及油管力学性能的测定确定两件油管的失效原因。     

油润滑下短碳纤维强化PEEK齿轮接触疲劳试验研究

针对注塑成型的碳纤维强化PEEK(PEEK-CF)齿轮在接触疲劳方面所进行的研究较少、失效机理尚不清晰的问题,开展30%PEEK-CF齿轮几何精度、齿面粗糙度和注塑缺陷的表面完整性测试表征,并进行油润滑下钢-PEEK-CF齿轮副耐久试验,绘制PEEK-CF齿轮接触疲劳S-N曲线。发现PEEK-CF齿轮能更好地适用于中低载荷工况,认为其在输出扭矩为40 N·m、接触应力为323.6 MPa的条件下有无限寿命。通过对失效试件断口SEM图进行失效分析,判断30%PEEK-CF齿轮失效机理主要为基体内碳纤维断裂。     

洗瓶机蜗轮断裂的失效分析

本在对断裂失效的洗瓶机蜗轮进行了断口的宏观分析和显微分析， 结论：疲劳源发生于齿根部位的主要原因是蜗轮材料存在成分偏析，致使齿根某部位三元共晶量多，在应力集中下发生低周疲劳断裂。     

电子元器件可靠性增长方法和技术

从电子元器件的可靠性存在的问题出发,与可靠性增长相联系,简述了可靠性增长曲线和电子元件的可靠性分析基本思路方法.从元器件可靠性物理分析技术角度,系统地阐述了失效信息的收集与分析、失效分析、破坏性物理分析、失效模式及机理与工艺的相关性分析、失效模式与影响分析等元器件的质量与可靠性分析技术,得出分析失效机理和失效原因才可以有效实现可靠性增长的相关结论.     

螺旋橡胶挤压脱水机驱动轴断裂分析

螺旋橡胶挤压脱水机驱动轴在使用环境中早期异常断裂,经受力分析、断口分析、材料成分及力学性能测试得出失效原因结论。确认该轴为高应力低周疲劳破坏。该轴材料及热处理均无问题,失效是由于加工工艺缺陷和装配不良导致轴的应力集中部位恶劣力学环境,埋下了应变疲劳隐患。该案例说明即使材料选择合适,热处理合格,也不能忽略机加及装配精度,在结构一定的前提下,这些因素是决定构件力学环境的、可人为影响的关键因素。同时说明一定要从相关的各个方面综合分析才能为机械失效准确的溯源。     

Practices and opinions reported by coordinators of graduate programs

Information is presented about the organization of graduate studies, based on questionnaire responses of 582 coordinators of Canadian graduate programs. These coordinators, who were representative of disciplines and geographic regions, provided information about a wide range of matters, including enrolments, staff, admissions, supervision, research, publications, financial support, teaching experience, and completion rates and times. Many substantial differences were noted among the percentage frequencies of responses for departments classified by discipline and size. For example, students were perceived to choose their doctoral theses topics themselves much more frequently in education, social sciences, and humanities than in engineering, medical sciences, physical sciences, and biological sciences. Also, departments with smaller numbers of full-time graduate students tended to provide all doctoral students, with some teaching experience to a greater extent than did larger departments.     

实践的自由与美的范畴

人，作为个体的生存，从实践（以物质生产为中心）出发才逐步生成，而在实足走向创造的过程中，人们才不断达到一定的自由境界。正是人的实践－创造的自由使自然人化，人也人化，从而产生出人对现实的审美关系；这种审美关系体现对象之上就是美，而体现在人本身之上则是美感。人类的实践－创造的自由同样是一个历时性的过程和一个共时性的结构，因此，它不仅有不同的自由程度和不同的自由境界，而且还有自由，反自由，不自由，准自由等几个维度；与这些不同的自由给度相关便形成了美，丑，柔美，刚美，悲剧性，喜剧性，滑稽，幽默的相应的美的范畴，并形成各个美的范畴之间的过渡，转化，对应等关系，从而形成一个完整的美的范畴体系。     

论罗蒂协同性实用主义的反哲学本性

理查德·罗蒂立足后现代主义、解构主义、文化自由主义、相对主义和后哲学文化论,建立的协同性实用主义,批判分析哲学、现象学、传统的认识论、反映论、符合论和真理观,肯定解释学的功能与教化作用,否定客观性、绝对性、永恒性和不变性,反对理性主义、科学主义和实在论,主张解构形而上学,创立无冕哲学,提倡工具主义、约定主义、实用主义、多元主义,以及心灵与社会的协同性作用。     

劳伦斯与非理性主义

以叔本华、尼采、弗洛伊德为代表的非理性主义是劳伦斯小说创作的思想基础。受叔本华影响,劳伦斯把生存意志作为人物行动的基本动力,这主要表现为向性力和精神占有欲。受尼采影响,劳伦斯赞美躯体,重视生命的内在能量和自我超越性,并与基督教决裂,成为西方基督教道德观的激烈批判者。劳伦斯在性与无意识这两个领域,对弗洛伊德精神分析理论有接受,也有超越。弗洛伊德与劳伦斯都把性、无意识与文明对立起来,但弗洛伊德进行的是否定性研究,强调对其疏导和控制,劳伦斯则认为性与无意识是原初的创造性力量,是生活的源泉,是对抗人之社会化和理性化的正面力量。非理性主义丰富和深化了劳伦斯对现代人心理世界的理解,加强了他的小说的社会批判力量。     

湘东南栖霞组底部史塔夫(Staffela)类动物群的发现

着重描述湖南邵东保和堂柳东早二叠世早期栖霞组底部首次发现的史塔夫 (Staffella)类动物群 ,共 5属 2 0种 ,这五属分别是史塔夫亚科的 Staffella,Pseudoendothyra,Nankinella和卡勒亚科的 Sphaerulina,Pisolina.该类动物群笔者曾命名为 Pseudoendothyra jazvensis带 .这一发现不仅填补了湘东南栖霞组生物地层学研究的空白 ,而且对我国南方石炭、二叠纪的生物地层划分提供了新的依据     

论教法设计的七要素——兼答美国人校长拉塞尔·S·比彻

作为教法中的教学模式系统,是由要素构成的。已有的成功的教学模式,其所构成的共同要素是:目、趣、序、思、练、诊、结七者。     

Opening Possibilities in Experimental Science and its History: Critical Explorations with Pendulums and Singing Tubes

A teacher and a college student explore experimental science and its history by reading historical texts, and responding with replications and experiments of their own. A curriculum of ever-widening possibilities evolves in their ongoing interactions with each other, history, and such materials as pendulums, flame, and resonant singing tubes. Narratives illustrate how questions, observations, and developments emerge in class interactions, along with the pair’s reflections on history and research. This study applies the research pedagogy of critical exploration, developed by Eleanor Duckworth from the interviewing of Piaget and Inhelder and exploratory activities of the 1960s Elementary Science Study. Complexity as the subject matter opens up possibilities which foster curiosity among participants. Like Galileo, Tyndall, Xu Shou, and others, this student recurrently came upon new physical behaviors. His responses to these phenomena enabled him to learn from yet other unexpected happenings. These explorations have implications for opening up classrooms to unforeseen possibilities for learning.

Teaching . . . is more about a conscientious participation in expanding the space of the possible by creating the conditions for the emergence of the not-yet-imaginable. . . . Teaching, like learning, is not about convergence onto a pre-established truth, but about divergence - about broadening what can be known and done. In other words, the emphasis is not on what is, but what might be brought forth. Teaching thus comes to be a participation in a recursively elaborative process of opening up new spaces of possibility while exploring current spaces. (Davis & Sumara, 2007, p. 64)

     

A view of Newton as a mathematician

In this article, we present certain topics such as quadrature of planar regions, introduced prior to the invention of calculus by Newton, and consider his other mathematical contributions, to binomial theorem and infinite series, cubics, theory of equations and imaginary roots. As the development of calculus and its enormous applications are well known, we will not discuss much about it. Earlier, he was in TIFR, Bangalore. His research interests include partial differential equations, homogenization, controllability and control problems, analysis, etc.     

基于ICM理论的隐性衔接语篇连贯解读

隐性衔接语篇连贯指的是不含显性衔接手段,如替代,省略,重复等,实现语义连贯的语篇。作为一种特殊的语言现象,隐性衔接语篇也是一种心理上的表征,是人类对认识世界的经验总结从语言上的反应。理想化认识模型（ICM）是人们在特定的文化背景中对某领域中的经验和知识所作出的抽象的、统一的、理想化的理解,它具有关联性、选择性、典型性,体验性等特征。正是因为人类对认知世界的体验,形成各种认知模型（CM）,而认知模型（CM）稳定而有规律,具有典型性特征。在认知过程中,各种认知模型（CM）之间的互相关联与相互选择,正好为人们解读隐性衔接语篇提供了认知上的新视角。     

Nanotechnology and Nanoscale Science: Educational challenges

Nanotechnology has been touted as the next ‘industrial revolution’ of our modern age. In order for successful research, development, and social discourses to take place in this field, education research is needed to inform the development of standards, course development, and workforce preparation. In addition, there is a growing need to educate citizens and students about risks, benefits, and social and ethical issues related to nanotechnology. This position paper describes the advancements that have been made in nanoscale science and nanotechnology, and the challenges that exist to educate students and the public about critical nanoscience concepts. This paper reviews the current research on nanotechnology education including curricula, educational programs, informal education, and teacher education. Furthermore, the unique risks, benefits and ethics of these unusual technological applications are described in relation to nanoeducation goals. Finally, we outline needed future research in the areas of nanoscience content, standards and curricula, nanoscience pedagogy, teacher education, and the risks, benefits, and social and ethical dimensions for education in this emerging field.