京昆高速河北省石家庄至晋冀界T梁试验研究

对京昆高速河北省石家庄至晋冀界质量存在疑问的T梁采用超声回弹综合测试法进行了钢筋混凝土梁的混凝土强度测试,并对其中1片T梁进行非破坏性静载试验,将测试结果进行综合分析,对测试梁的强度和承载力进行客观评价,最终将测试梁应用于施工现场,节省工程资金,排除安隐患。     

钢筋混凝土T型截面梁的优化设计

以T型截面梁单位长度造价最低为追求目标，对钢筋混凝土梁正截面承载力的约束条件进行了优化，并推导出简单实用的T型截面梁的优化设计公式。     

钢筋混凝土T型截面梁的优化设计

本文以T型截面梁单位长度造价最低为追求目标，对钢筋混凝土梁正截面承载力的约束条件进行了优化，并推导出简单实用的T型截面梁的优化设计公式。     

碳纤维布围覆加固T形钢筋混凝土梁受弯承载力试验研究

通过对三面围覆碳纤维布进行加固的钢筋混凝土T形梁的试验,探讨了梁的受弯破坏形态、极限状态和设计要求,并根据实测纤维布极限应变值,讨论了纤维布允许拉应变的取值问题。     

碳纤维薄板补强钢筋砼梁界面破坏的试验

通过碳纤维薄板补强钢筋混凝土梁的抗弯试验，采用改变碳纤维薄板粘贴长度、梁的缺口高度和配筋率等参数，对加固梁的界面破坏形式进行了较系统的试验研究，并初步分析了界面的剥离失效机理。     

基于静载试验的T梁桥体外预应力加固效果评价

云南某预应力混凝土简支T梁桥主梁竖向开裂,对该桥采用张拉体外预应力钢绞线进行加固.为验证加固效果,对6#跨在加固前、后进行静载试验,试验结果表明:加固前,L/2截面梁底应力及挠度校验系数均大于1,判断该桥承载能力不满足公路Ⅱ级(JTG D60-2015)荷载要求.加固后,L/2截面梁底应力及挠度校验系数均小于1,T梁抗裂性及刚度显著提升,在试验荷载作用下,体外钢绞线与T梁能够共同协调受力,桥梁承载能力满足设计荷载要求.荷载试验结果显示该桥加固效果良好.     

T形截面钢梁桥模型实验研究

为了研究中横隔梁对T形梁桥荷载横向分布的影响,制作了2个T形钢梁桥实验模型,每个模型由5片T梁肋组成,其中一个有中横隔梁,一个无中横隔梁.用Midas/civil有限元分析软件建立了T形梁桥实验模型,进行了理论计算与分析,并与实测值进行了比较.结果表明,有中横隔梁的T形梁桥模型的整体刚度相对较大,各单片梁肋间的传力较好,故各梁肋的荷载横向分布系数接近直线分布;无中横隔梁T形梁桥由于仅有桥面板传递剪切变形,在对称及偏心荷载作用下,集中荷载作用梁肋的应变与挠度均较大,荷载横向分布呈不均匀现象.     

基于超声波法的T梁厚度检测方法研究

为快速测试桥梁梁板厚度,本研究运用超声波法对典型桥梁T梁梁板厚度检测方法进行研究,并对其检测方法的检测精度进行分析。研究发现超声波测量T梁横隔板边缘测量误差最大为3.5%,T梁中腹板超声波测量误差最大为20%。根据超声波法的测试结果,提出了超声波测试桥梁梁板精度修正的处理方法。研究结果表明超声波在桥梁梁板厚度测试中具有优越性的同时也存在一些问题,如何克服超声波梁板厚度测试快速定点及测试结果数据处理提高精度是超声波梁板厚度测试的难点和关键。     

重载铁路超低高度梁安全运营性能研究

铁路是国民经济的大动脉,重载铁路运输的不断发展在带来明显经济效益的同时,也给铁路桥梁带来越来越多的不利影响,如冲击振动加大、梁体开裂加重等,尤其对梁体刚度较小的超低高度梁,重载运输带来的不利影响更加明显。以32 m超低高度简支T梁为研究对象,采用有限元仿真分析与实桥试验相结合的方法,并与32 m普通高度简支T梁的安全运营参数相比较,对超低高度梁在不同列车速度和轴重下的安全运营性能进行研究,相关结论对该类型桥梁的科学维护管理提供依据。     

鄄城黄河桥引桥50m折线配筋预应力砼T梁施工

德商高速公路鄄城黄河公路大桥引桥50m折线配筋预应力砼T梁是目前国内建设规模最大的折线配筋先张梁项目,它采用先张梁较后张梁优势明显,先张梁完全避免了后张法中可能出现的堵孔、压浆不密实、预应力失控等影响结构质量与耐久性的问题.鄄域黄河桥的50m折线配筋先张法T梁的建设也为后来的折线配筋先张法项目提供了大量的试验数据和宝贵的施工经验.     

Study time and test performance as a function of test expectations

Study time and test performance change as a function of subjects expecting either open questions or a multiple-choice test on the contents of a history text. After studying a first history text, the subjects immediately received a test consisting of either open questions or multiple-choice items. They were led to expect the same type of test on a second text. Study time on Text 2 was self-paced, and the type of test was either the expected or unexpected one (either open questions or a multiple-choice test). The main hypothesis was confirmed that subjects consider open questions a more demanding test than a multiple-choice test. Accordingly, subjects expecting open questions on Text 2 used more study time and performed better on both types of test than did subjects expecting a multiple-choice test. Internal analyses revealed that the differences on study time and test achievement between the two expectation conditions occurred only when the subjects were thoroughly acquainted with the processing requirements of the learning material and its expected test.     

Test anxiety, perceived test difficulty, and test performance: temporal patterns of their effects

Two hypothesized models that represent relationships among test anxiety, perceived test difficulty, and test performance observed immediately before and after a final examination were tested. The structural equation modeling was used to examine the hypothesized relationships by imposing the structure of direct and indirect effects on the current data collected from 208 undergraduate students. Students' perception of test difficulty had a significant effect on the arousal of both worry and emotionality. Temporal changes were observed in the degrees of these relationships; while test difficulty perceived before and during the exam both had effects on test anxiety perceived at each corresponding time, students' perception of test difficulty during the exam had a greater direct effect on the arousal of test anxiety than did test difficulty perceived before the exam. Worry, but not emotionality, had a strong inverse relationship with performance. That perceived test difficulty did not have a direct effect on test performance, but had an indirect effect mediated by worry, indicates that test performance was not directly influenced by how they perceive the test difficulty, but worry aroused by the difficulty perception influenced their performance. Importance of understanding students' perceived test difficulty was discussed for its effect on arousing worry anxiety.     

用Flash MX中文版制作一套网上试题

详细介绍了用Flash MX中文版制作一套含有单选题、多选题、填空题、是非题的网上测试题的方法和步骤。     

学业水平考试物理试题难度预估方法探究

目前上海市普通高中学业水平考试未实行考前试测制度,因此试题难易度主要依据试题编制者的经验进行预估,尚无量化研究的方法。本研究根据国内外研究经验,从试题的物理概念、试题设计、数学运算三个项目出发,结合2011年上海市普通高中物理学业水平考试试题难度实测数据分析,构建试题难度预估的量化方法,并用2012年上海市普通高中物理学业水平考试试题难度实测数据检验其准确性,期望为今后物理试题难易度预估提供研究的基础。     

NCME 2007 Presidential Address: The Concordance Table: An Invitation to Misuse Test Scores

This article discusses a particular type of concordance table and the potential for test score misuse that may result from employing such a table. The concordance that is discussed is typically created between scores on different, nonequatable versions of a test that share the same or close to the same test title. These concordance tables often appear in the context of relating scores on computerized adaptive and paper‐and‐pencil versions of the same test. When such a table is presented in a complete point‐by‐point fashion, relating each reported score on the scale of the new version of the test to a reported score on the scale of the old version of the test, test score users will typically treat the table as if it represented an equating of scores between the two versions, and directly replace scores on the new version of the test by scores on the old version. This clearly represents a misuse of the test scores. Suggestions for avoiding this misuse of test scores from concordance tables are provided.     

基于启发式的协议漏洞挖掘策略研究

针对大量网络协议存在种种安全漏洞,采用Fuzzy测试可以有效地进行漏洞挖掘.为了提高Fuzzy测试的效率和漏洞挖掘的成功率,设计了启发式的Fuzzy测试方法.通过对待测协议的形式化描述,抽取出协议工作过程.通过对状态转移图的分析以及Fuzzy测试的响应,智能地触发新的测试数据,提高了Fuzzy测试效率.通过对自行设计的样本协议以及两个公开协议漏洞进行测试,漏洞挖掘时间比穷举式的平均缩短了57.3%.     

考试质量在线测评系统的设计——以经典测试理论和项目反应理论为基础

在总结目前考试测评系统不足的基础上提出科学有效的考试质量评价方法,并在该方法的指导下运用经典测试理论和项目反应理论设计考试质量在线测评系统。系统具有创建新表、成绩统计、质量分析以及基于经典测试理论下的信度和效度分析等功能,能够满足广大教师对考试质量分析的需求。     

低温制冷综合试验台的研究与探讨

对低温制冷综合试验台进行了研究,详细说明了该试验台的基本构成和参数控制思路,并对该试验台进行实验项目的探讨。试验台内部最低温度可达-35℃,能提供恒温、恒湿、恒风速实验环境,可进行蒸发器结霜特性、换热器性能等多方面的实验,也可进行其他交叉学科的科学研究,可为教学、科研换热设备的开发、研制提供服务。     

Does teaching to the test improve student learning?

A central concern surrounding test-based accountability is that teachers may narrow teaching practices to improve test performance on a curriculum-based specific knowledge test rather than student learning more broadly. Two of the most common teaching practices that “teach to the test” are providing test-specific classwork and increasing the frequency with which students take practice tests. Whether such teaching practices improve student learning—both in terms of learning the content associated with a specific knowledge test as well as more general learning—is a largely unanswered question. To approach this question, this paper uses a student fixed effects approach to analyze the impact of these kinds of narrow teaching practices on student performance on a specific test as well as a general knowledge test. We find that test-specific classwork and practice tests with specific test items tend to have little or negative impacts on curriculum specific or general knowledge test performance, except for male students, and that subject practice tests (without emphasizing test-specific items) have positive effects on student outcomes on both kinds of tests, but larger on the curriculum-specific than on the general test, and much larger on the curriculum-specific test for male students. We discuss the logic for these results and what they tell us about the effectiveness of test-focused teaching practices more generally.