泡沫铝夹芯结构油罐车罐体优化设计

为了提高油罐车的节能性、环保性和安全性,以某油罐车罐体为设计原型,首先初步设计了泡沫夹芯结构油罐车罐体.然后在ANSYS中使用MOGA方法对影响罐体强度的主要参数进行目标驱动优化分析,得到各参数的敏感度曲线和相应面及候选优化设计点之后对优化后的泡沫铝夹芯结构油罐车罐体和原型结构的罐体进行分析比较.结果表明,优化设计的泡沫夹芯结构油罐车罐体相比原型罐体在质量减少的情况下可提高罐体的应力和应变,进而可提高罐体乃至整车的轻质、节能性、环保性和安全性.     

主框架梁布置对巨型结构抗震受力性能的影响

运用有限元分析软件SAP2000对主框架梁位置布置不同的巨型框架结构进行地震反应的弹性时程分析．结果表明,随着巨型梁布置位置的上移,结构侧移变大,结构层间相对位移沿高度方向趋于不均匀,最大结构层间侧移发生部位逐渐上移．     

古建砖塔砌体结构抗震性能模拟分析

通过利用计算机模拟地震对砖塔砌体的影响得到古建砌体结构抗震特点。建立砖塔砌体结构力学分析模型,对结构分别施加特定的人工波和天然波,进行时程分析和模态分析,得到X、Y方向层间位移图,层间剪力图以及弯矩图。结果表明,在人工波作用下,结构第3层和第4层的层间剪力比天然波作用下的层间剪力大30%左右,第2层和第3层的弯矩比第2种地震波作用下的弯矩大20%左右;在2种特征周期的地震波作用下,最大层间位移都集中体现在第6层,其层间位移是第1层的2倍多,塔在天然波作用下将会发生损坏。     

语篇微观层面的夹档关系结构及其序列照应研究

夹档关系是借用电脑中"文件夹"和"文档"这两个概念,使具有包容和被包容关系的词、短语、句子进入语篇微观层面所形成的话语成分之间的语义关系.认知语言学中的"容纳图式"理论是夹档关系结构成立的认知理据.鉴于夹档关系结构与总分关系结构、例举结构、框棂关系存在交叉性,确立并研究夹档关系结构是非常必要的.夹档关系结构的表现形态主要包括辐射型、收束型、综合型.从各档项的语序排列层面看,夹档关系结构中各档对夹所具有的显性或隐性序义存在不同程度的序列照应.     

交联聚丙烯酸吸水性树脂的结构与性能研究

研究了交联聚丙烯酸吸水性树脂的结构与性能,并对影响其结构与性能的因素进行了探讨。为合成和应用提供了依据;同时对交联聚丙烯酸吸水性树脂的吸水机理及应用方面的研究进展进行了讨论。     

针织保暖内衣面料舒适性能的探讨

通过对针织保暖内衣品种与面料结构的分析，着重对不同保暖层结构的保暖内衣面料舒适性能进行了探讨，提出了舒适型保暖内衣面料的选择意见。     

高速电弧喷涂超硬复合材料粉芯丝材的工艺研究

介绍了一种ф2.5mm铁基超硬复合材料粉芯丝材。用正交设计试验方案,在钢基体上采用高速电弧喷涂制备耐磨涂层,进行涂层结合强度试验,获得了最佳工艺参数组合,并探讨了涂层厚度与结合强度之间的关系。     

DAR成色剂结构与性能的关系

通过分析DAR成色剂的结构和作用机理,讨论了其结构与照相性能之间的关系.DAR成色剂的结构可表示为:Cp-L-A,其中Gn代表成色剂母体,A代表促进显影的功能基团即增强基团,L代表连接基团同时也有吸附功能即吸附基团.本文指出:当吸附基团和增强基团相同时,母体对照相性能影响不大;当母体及增强基团相同时,吸附基团的吸附性越强,照相性能越好;当母体及吸附基团相同时,增强基团的感染显影作用越强,照相性能越好.     

焦油聚酯防水材料的结构与性能研究

本文介绍了以MOCA和甘油为交联剂合成的两种不同类型聚氨酯与不同重量比的焦油所形成的防水材料，初步探讨了两类材料的耐热性能，耐水性能与材料的断面形貌间的依赖关系，实验结果表明，以MOCA为交联剂的焦油聚氨酯是耐水性能较好的防水材料。     

高分子材料结构与性能研究型综合实验设计

为提高高分子材料实验内容综合性,培养学生创新能力和综合素质,设计了研究型综合实验"可控降解β-聚丙烯的结构与性能".内容包括配方设计、制备加工、结构表征和性能测试等,将多方面知识串联整合.该实验有助于学生深入理解高分子材料结构特点以及结构决定性能的原理,解决了学生对高分子材料微观结构难以理解的问题.通过学科前沿知识引人...     

安阳产CW6163B车床油泵部分零件的改造

根据CW6163B车床油泵启动部分实际运转情况,结合设备装配图,分析出油泵部分的设计缺陷,提出改造设计方案,并分析了其可行性,最终完成了零件的改造.     

研发联盟治理结构的成因及绩效分析(英文)

由于传统的理论将治理结构分为"等级、市场"或是"股权、非股权"等,而这些分类方式并不能充分描述研发联盟治理结构的特点,因此本研究首先解释在研发联盟当中,为何必须存在不同的组织治理结构类型;继而探讨在面对不同特性的研发联盟时,如何选择适当的治理结构类型.结合交易成本经济学理论与资源基础观点,推导出影响研发联盟组织治理结构的6个主要因子,分别为技术不确定性、文化差异、资产特殊性、技术的互补性、个别公司独门技术的研发专用性、信任,据此建立本研究模型.当研发联盟的技术不确定性较高、文化差异较大、独门技术的研发专用性有较多的防范时,则采用非集中联盟;当研发联盟的资产特殊性较高、技术的互补性较大、伙伴之间的信任度较高时,则采用集中联盟.搭配这些因子的特性选择组织治理结构类型,则研发联盟有更好的绩效,反之亦然.     

New method for high performance multiply-accumulator design

This study presents a new method of 4-pipelined high-performance split multiply-accumulator （MAC） architecture, which is capable of supporting multiple precisions developed for media processors. To speed up the design further, a novel partial product compression circuit based on interleaved adders and a modified hybrid partial product reduction tree （PPRT） scheme are proposed. The MAC can perform 1-way 32-bit, 4-way 16-bit signed/unsigned multiply or multiply-accumulate operations and 2-way parallel multiply add （PMADD） operations at a high frequency of 1.25 GHz under worst-case conditions and 1.67 GHz under typical-case conditions, respectively. Compared with the MAC in 32-bit microprocessor without interlocked piped stages （MIPS）, the proposed design shows a great advantage in speed. Moreover, an improvement of up to 32% in throughput is achieved. The MAC design has been fabricated with Taiwan Semiconductor Manufacturing Company （TSMC） 90-nm CMOS standard cell technology and has passed a functional test.     

Understanding inclusive STEM high schools as opportunity structures for underrepresented students: Critical components

Inclusive STEM high schools (ISHSs) can be viewed as opportunity structures for students underrepresented in STEM. By opportunity structures, we mean an education that provides not only access to high quality STEM curriculum and instruction or “opportunity to learn,” but also the capacity to create learning environments where students can build STEM social capital and the dispositions, knowledge, skills, and networks to be successful in STEM college majors and careers. This is a cross‐case analysis of case studies that describe the design and implementation of eight “exemplar” ISHSs. Beginning with 10 hypothesized critical components, we found evidence for all 10, but present in unique patterns of prominence, depending on the school context. Further inductive analysis located an additional four emergent critical components that complete the picture of how these successful ISHSs were able to achieve their goals. Importantly, across schools, four components stood out as foundational: a flexible and autonomous administrative structure; a college‐preparatory, STEM‐focused curriculum for all; well‐prepared STEM teachers and professionalized teaching staffs; and supports for students in underrepresented groups. Although many of the critical components found in the ISHSs are also found in the school reform literature, these schools also had characteristics unique to STEM education. This paper is important in understanding STEM high schools as opportunity structures and as a school reform alternative that can help solve equity and social mobility gaps in STEM.     

Blocking student performance in high school?

Block schedules have been used in several different high schools in various areas of the United States. Reasons for their use vary from better preparing students for college work to fewer disruptions of the school day. Several studies have examined the impact of changing from a semester system to a block system on the academic performance in specific areas with varying results. This paper examines the impact of a change of schedule on overall academic performance as measured by a student’s Grade Point Average. This study indicates that for the specific case studied, the change in systems did have a positive effect on performance.     

档案袋评价在高职Visual FoxPro课中的应用

通过对Visual FoxPro课的档案袋评价，探索教学评价中的“职业”特点，使学生从盲目应付考试的学习中解脱出来，培养学生的职业素养，提高其计算机应用技能。     

Crib sheets and exam performance in a data structures course

In this paper, we study the relationship between the use of “crib sheets” or “cheat sheets” and performance on in-class exams. Our extensive survey of the existing literature shows that it is not decisive on the questions of when or whether crib sheets actually help students to either perform better on an exam or better learn the material. We report on our own detailed analysis for a body of crib sheets created for the final exam in a junior-level Data Structures and Algorithms course. We wanted to determine whether there is any feature of the crib sheets that correlates to good exam scores. Exam performance was compared against a number of potential indicators for quality in a crib sheet. We have found that students performed significantly better on questions at the comprehension level of Bloom’s taxonomy when their crib sheet contained good information on the topic, while performance on questions at higher levels of the taxonomy did not show correlation to crib sheet contents. We have also seen that students at certain levels of performance on the final exam (specifically, medium-to-high performance) did relatively better on certain questions than other students at that performance level when they had good coverage of that question’s topic on their crib sheet.     

钢结构材料在高温(火灾)条件下的力学性能试验研究

从基本的钢结构材料在高温下的力学性能着手 ,进行高温条件下钢结构材料的性能试验 ,建立高温下钢材的屈服强度、极限强度、弹性模量和极限应变随温度变化的力学模型 ,为高温 (火灾 )条件下钢结构的结构分析提供依据。     

Using three-dimensional models to teach molecular structures in high school chemistry

The purpose of this study was to compare the effects of using two- and three-dimensional model representations of molecular structures on student learning of organic chemical structures. Organic structures were taught to high school students using one of four methods of molecular representation: (1) two-dimensional textbook representations, (2) three-dimensional computer models, (3) three-dimensional ball and stick models, and (4) combination of the computer molecular models and the ball and stick models. The computer software used in this study wasMolecular Editor. Students in the combination group of using both computer and ball and stick models scored significantly higher on the retention test of isomeric identification compared to the other groups. Molecules were represented in this test in the same mode as the instructional representation. However, on a similar two-dimensional post-instructional test of isomeric identification, this group had a significantly lower mean than the other groups; the two-dimensional group had the highest mean. This difference was not observed with the two-dimensional retention test of isomeric identification. When given a two-dimensional test of isomeric construction, no significant difference was found among the group means with either the posttest or the retention test.     

Factors influencing student academic performance in online high school algebra

This paper describes the effect of teacher comments, students’ demographic information and learning management system utilisation on student final scores in algebra courses in a K–12 virtual learning environment. Students taking algebra courses in a state virtual school in the Midwestern US region during 2007–2008 participated in this study. Student final scores on these courses were collected using tests administered at the end of semester in the virtual school courses. The hierarchical linear modelling technique was used for data analysis to account for the influence of school characteristics on student final scores. The results show these factors have different influences on student final scores in different algebra courses. The discussion of the findings addresses the implications for teaching.