共查询到20条相似文献，搜索用时 171 毫秒
1.
2.
李冬梅 《广东技术师范学院学报》2010,31(6):44-47
为了揭示含两个对称缺口的单向玻璃纤维筋拉伸破坏机理,预估其破坏规律,本文基于剪滞理论,建立一种对各单层分划为有限子单元的剪滞分析模型,分析含两个对称割口的玻璃纤维筋在拉伸载荷作用下的应力重新分布及割口之间的相互影响问题,求出含两个割口的玻璃纤维筋割口附处近完整纤维的应力集中因子及其破坏强度并与实验数据进行对比.本文结果可为进一步研究含多个割口的玻璃纤维筋的破坏机理提供理论依据. 相似文献
3.
布尔运算是实体造型的常用工具之一,但在设计实践中,设计师不太习惯于使用其中的布尔交运算。本文探讨了布尔交运算的实质、优点和适用场合,提出了一种造型设计的新思路。 相似文献
4.
论述了对称曲线槽槽轮机构的极坐标设计方法,介绍了利用平移和布尔运算函数进行槽轮加工仿真的过程,通过加工仿真既可以检验加工的干涉情况,又可以完成槽轮的三维实体造型。 相似文献
5.
万朝阳陈国新王康陈磊 《实验室研究与探索》2017,(2):30-33
将直径8的玄武岩纤维增强塑料(BFRP)和玻璃纤维增强塑料(GFRP)筋恒温30 min再冷却至室温,用钢套管固定BFRP和GFRP筋端头并对其进行拉伸力学性能试验。研究BFRP和GFRP筋受拉本构关系、拉伸弹性模量、极限抗拉强度、极限拉应变等力学性能,并拟合温度在20~120℃时BFRP和GFRP筋拉伸力学性能随温度作用后的变化规律。结果表明:随荷载增加到极限荷载65%~80%,BFRP和GFRP筋均发出清脆的声音,其表面纤维丝断裂而导致脆性破坏;随温度增加,BFRP和GFRP筋受拉本构关系呈线性变化;120℃与20℃相比,极限抗拉强度分别降低9.8%和10.6%;BFRP筋极限拉应变减少20.4%,而GFRP筋出现先减后稍增趋势;BFRP筋拉伸弹性模量提高5.4%和13.9%,而GFRP筋呈先增后减现象。 相似文献
6.
《实验室研究与探索》2017,(2)
将直径8的玄武岩纤维增强塑料(BFRP)和玻璃纤维增强塑料(GFRP)筋恒温30 min再冷却至室温,用钢套管固定BFRP和GFRP筋端头并对其进行拉伸力学性能试验。研究BFRP和GFRP筋受拉本构关系、拉伸弹性模量、极限抗拉强度、极限拉应变等力学性能,并拟合温度在20~120℃时BFRP和GFRP筋拉伸力学性能随温度作用后的变化规律。结果表明:随荷载增加到极限荷载65%~80%,BFRP和GFRP筋均发出清脆的声音,其表面纤维丝断裂而导致脆性破坏;随温度增加,BFRP和GFRP筋受拉本构关系呈线性变化;120℃与20℃相比,极限抗拉强度分别降低9.8%和10.6%;BFRP筋极限拉应变减少20.4%,而GFRP筋出现先减后稍增趋势;BFRP筋拉伸弹性模量提高5.4%和13.9%,而GFRP筋呈先增后减现象。 相似文献
7.
本文应用美学原理，就服装设计中不对称美，从款式造型，结构设计，色彩设计，到面料，配饰对不对称美的作用和影响，进行全方位的论述，从而阐明不对称只是体现服装创作灵感，思维的一种设计手段，不对称与对称完美结合才是服务设计的根本。 相似文献
8.
插花造型一般可分为对称式和不对称式。不对称式插花造型是一种传统的 ,中国式的造型方法 ,一般具有三个主枝 :中心枝、根饰枝、配饰枝 ,各枝的长度都有严格比例 ,造型比较复杂、灵活 ,对于初学者来说存在一定的难度 ,需要反复实践 ,积累经验 ,逐步掌握。而对称式插花的构图相对容易些 ,只要颜色搭配得好 ,花朵大小搭配得当 ,初学者只要将构图背过 ,记忆在脑子里 ,就可以在短时间内 ,插做出较好的作品。对称式插花突破了传统的束缚 ,人们只要用一个较为简洁的构图 ,依照自己的喜好 ,就可以快速地将对美的追求坦率地表现出来 ,充分地显示出现… 相似文献
9.
某工程由两榀超大曲形混凝土桁架组成,为确保工程质量,对桁架上弦杆、下弦杆钢筋连接、安装:确立纵向纲筋采用机械直螺纹连接技术,弦杆钢筋安装固定采用定距框与限位箍筋措施.检查验收、实体质量检测结果表明,钢筯保护层厚度符合设计要求及施工质量验收规范. 相似文献
10.
彭颖 《南宁职业技术学院学报》2007,12(2):110-113
基于现有规范小曲率半径U形预应力筋张拉伸长量缺乏陈述,而该类预应力筋实测伸长值和理论伸长值偏差过大。在目前的工程实践中,往往需要对该类预应力筋做张拉试验,通过结合有关试验总结了该类预应力筋张拉伸长量修正的试验方法和计算方法。 相似文献
11.
吴淑姣 《暨南大学华文学院学报》2006,(4):43-48
本文首先分析了经贸汉语术语的特点,明确了经贸汉语术语的教学原则和目标;在此基础上,本文重点结合实例介绍了经贸汉语教学实践中几种行之有效的术语教学方法,涉及课堂讲授方法和课堂巩固方法两个方面。 相似文献
12.
虚拟现实技术在网络教学中的研究与应用 总被引：7，自引：0，他引：7
通过简要介绍了虚拟现实技术、VRML及虚拟技术应用于教育教学的必要性,并结合虚拟机械零部件实例,阐述了虚拟现实技术在网络教学中应用的基本方法与实现途径。先通过三维造型软件完成实体建模,然后利用VRML语言进行位置、动作、空间背景、空间视点、传感器等设置,以实现虚拟机械零部件的运动仿真效果,从而达到让学生在网络教学环境下了解机械零部件结构、实体形状和运动特征的目的。 相似文献
13.
Bernadet de Jager Margo Jansen Gerry Reezigt 《School Effectiveness & School Improvement》2013,24(2):179-196
Constructivist ideas have influenced recent major innovations in Dutch secondary education and new curricula for reading and math in primary education, for example, pay much more attention to metacognition than before. In our study, we compared the growth of student metacognition in varying learning environments, direct instruction, and cognitive apprenticeship in primary school. The study also included a control group of teachers. In order to measure metacognition we developed a questionnaire, with separate parts for metacognitive skills and metacognitive knowledge. In the item selection procedure we made use of item response modeling. It was found that in the direct instruction and the cognitive apprenticeship group the pupils had higher scores on metacognitive skills and metacognitive knowledge compared to the control group pupils. No clear differences were found between direct instruction and cognitive apprenticeship. Interactions of learning environment and student intelligence were non-significant for both output measures. 相似文献
14.
Catherine P. Prinsell Philip H. Ramsey Patricia P. Ramsey 《Journal of Educational Measurement》1994,31(4):327-337
Six undergraduate and three graduate classes were given multiple-choice tests with subsequent evaluation of answer changes. The 300 students were tested twice, once before and once after instruction on answer changing. After each test, students were asked to complete two forms. The forms evaluated attitude toward answer changing, reasons for changing, and confidence in final answers. Students showed a significant increase in favorability toward answer changing after instruction. No significant change was found in number of answers changed. Psychology students were found to change significantly more items than were business students. Mean gain score did not change significantly after instruction. It was concluded that although instruction does lead to a change in attitude in answer changing, the number of changes and overall gain due to answer changing do not change. It was also determined that students continue to make significant gains even when their confidence in the final answer is less than 50 on a 100-point scale. 相似文献
15.
教育技术重点迁移探析 总被引：1，自引：0，他引：1
马德俊 《徐州师范大学学报(哲学社会科学版)》2002,28(4):139-142
现代科学技术的发展和现代教育理论的广泛应用，促使教育技术领域的重点不断迁移。其演进过程大致呈现出这样几个阶段：早期教育技术重点强调媒体；当今则强调教学中各要素间的相互关系；今后，教育技术将注重影响和促进学习的资源和过程，并且进一步朝着强调绩效即业绩和能力的方向发展。 相似文献
16.
The effects of token reinforcement, cognitive behavior modification, and direct instruction on learning-disabled students' math skills were compared. Math skills were measured by 2-minute classroom timings of basic addition and subtraction problems, and the Stanford Diagnostic Mathematics Test. Treatment was provided to 94 students for 4 weeks in daily 1-hour sessions. Significant differential gain between treatment and direct instruction groups in achievement test scores was found, F(4, 182) = 4.03, p<.01. Token reinforcement and cognitive behavior modification were found to be equally effective. All three groups improved with 2-minute classroom timings, F(2, 91) = 8.53,p<.001. Retention of skills for both treatments was maintained over a 2-week no-treatment period. Teachers' social validity ratings indicated differences between the two treatments relative to student behaviors and teacher roles. It is concluded that token reinforcement and cognitive behavior modification are equally effective techniques to remediate learning-disabled students' math achievement, and both are superior to direct instruction in some cases. 相似文献
17.
李润 《兰州石化职业技术学院学报》2012,12(1):16-18
应用Pro/E参数化和行为建模技术,实现齿轮的优化设计,分析零件的质量如何随齿轮齿数的变化而变化。首先在Pro/Engineer的建模环境中完成齿轮零件的三维建模,在完成优化设计的数学模型定义之后,转换到Pro/Mechanica工作环境中,通过灵敏度分析找出关键的设计变量（齿轮的齿数）对优化目标进行优化,从而可以根据设计者的特定要求分析出最佳的设计结果。该方法可以推广应用于其他零件的结构设计中。 相似文献
18.
Sylvia P. van Borkulo Wouter R. van Joolingen Elwin R. Savelsbergh Ton de Jong 《Journal of Science Education and Technology》2012,21(2):267-275
Computer modeling has been widely promoted as a means to attain higher order learning outcomes. Substantiating these benefits,
however, has been problematic due to a lack of proper assessment tools. In this study, we compared computer modeling with
expository instruction, using a tailored assessment designed to reveal the benefits of either mode of instruction. The assessment
addresses proficiency in declarative knowledge, application, construction, and evaluation. The subscales differentiate between
simple and complex structure. The learning task concerns the dynamics of global warming. We found that, for complex tasks,
the modeling group outperformed the expository group on declarative knowledge and on evaluating complex models and data. No
differences were found with regard to the application of knowledge or the creation of models. These results confirmed that
modeling and direct instruction lead to qualitatively different learning outcomes, and that these two modes of instruction
cannot be compared on a single “effectiveness measure”. 相似文献
19.
This study examined the effects of adding collaborative modeling of text structure as an additional component of self-regulated strategy development for elementary school 6th-grade students learning English as a second language (ESL). In this study, 34 students receiving a ‘Self-regulated strategy development plus collaborative modeling of text structure’ intervention were compared with 36 students receiving a ‘collaborative modeling of text structure only’ intervention, 38 students receiving a ‘self-regulated strategy development only’ intervention, and 36 students receiving traditional instruction. Several measures (i.e., content comprehension, summarization of main ideas, and essay writing) were administered after the one-month intervention. Results revealed that, compared to traditional instruction, self-regulated strategy development and collaborative modeling of text structure respectively resulted in better comprehension levels and writing performance. The combination of self-regulated strategy development and collaborative modeling of text structure was particularly effective in increasing primary school students’ content comprehension and writing quality. These findings highlight the benefit of coupling self-regulated strategy development and collaborative modeling of text structure for elementary school ESL classroom instruction. 相似文献
20.
UML 课程是计算机科学与技术专业的重要课程,为提高学生应用能力,使用案例驱动教学法改进传统UML 建模技术课程教学模式。案例驱动教学以案例作为课程关键点将 UML 教学分为 3 部分,通过案例教学实现学生对知识的认识、掌握和应用。案例驱动教学具体步骤包括：提出案例、分析案例、讨论案例并讲解知识点;再次提出新案例、分小组讨论并给出解决方法、教师给出建议及参考性答案;提出更深层次的问题,学生课后分组完成,并巩固提高。案例驱动教学让学生在解决实际问题的过程中建构自己的知识体系,促进他们不断提高问题解决能力和实际应用能力。 相似文献