共查询到20条相似文献，搜索用时 187 毫秒
1.
KimberLeigh Felix Hadfield 《Teaching Statistics》2021,43(1):28-35
Undergraduate students tend to struggle with probability in their introductory statistics course. Probability problem solving requires several steps. First, students must make sense of the probability scenario, then determine the appropriate probability rules, and finally, execute the procedures to solve the problem. With no previous exposure to probability, this presents too great a cognitive load for many students. Using worked‐out problems then transitioning to partially worked‐out problems in an introductory statistics course at a large university helped students succeed at solving probability problems. The worked‐out problems included writing prompts to encourage self‐explanation of students' thinking through studying the worked‐out examples. This paper explains the use of these instructional principles and their implementation in an introductory statistics course for non‐STEM majors, resulting in higher student achievement and understanding. 相似文献
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The weld nugget formation in the resistance spot welding(RSW) of aluminum alloy was investigated in the present study. The nugget formation process was directly observed by using a digital high-speed camera. Numerical simulation was also employed to investigate the nugget formation process. The results showed that for the RSW of two aluminum alloy sheets, a nugget was first formed in the workpiece/workpiece(W/W) interface and grew along the radial direction and axial direction of the sheets, and then it became a large elliptical nugget. For the RSW of three aluminum alloy sheets, two small nuggets were firstly formed in two W/W interfaces and grew along the axial direction and radial direction; finally they fused into one nugget. Besides, there existed a critical welding time, after which the nugget size remained nearly unchanged. This indicates that a long welding time is unnecessary for the RSW of aluminum alloy. In addition, the calculated nugget radius was compared with the experimental results, which showed that the simulation results agreed well with the experimental results. 相似文献
3.
为了探讨光敏剂瘤内注射法在临床上的应用,本实验将高浓度血卟啉衍生物（HpD）直接注入荷瘤小鼠的肿瘤内,利用组织涂片法,通过荧光显微镜观察．结果,注射后1～5天内,局部注射组肿瘤内发橘红色荧光的细胞的百分比明显高于腹腔注射组,以1～4天为著．局部注射组的肝、脾、肾组织中发荧光细胞的百分比低于腹腔注射组．根据实验结果．肿瘤内注射可以提高瘤内HpD的浓度,而减少正常组织中HpD的含量,减轻毒副作用． 相似文献
4.
路世英 《商丘职业技术学院学报》2006,5(2):19-20
对一些级数求和问题,如果用一般的初等方法,很难求解.但是如果能构造成一个概率模型,则求解过程会变得非常简单.为此,我们就一个级数的求和问题,讨论如何用概率论的知识求解. 相似文献
5.
David Palmer 《Research in Science Education》2008,38(2):167-188
This paper reports part of a larger study which was designed to investigate current practices in initial teacher education
programs in Australia. The main data collection was by telephone interviews, which were carried out with science education
specialists and program coordinators at all institutions which offer primary teacher education or secondary science teacher
education. The interviews focused on practices in relation to program structures, science content studies, science methods
studies and links to science-related school projects or to science business/industry. A large number of innovative practices
were described. In addition, several case studies were carried out, which focused on particular innovations. The study identified
several aspects of science teacher education which were of concern. 相似文献
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对初中生学习概率定义的思考 总被引：1，自引：0，他引：1
了解概率的意义,已成为我国初中数学的教学内容之一,不同的初中数学教材对概率定义的处理方式有所不同.在概率论的历史上,概率的定义经过了古典概率、几何概率、概率的频率定义以及概率的公理化定义.初中生学习概率的意义时,可以将古典概率作为起点,然后引申到几何概率,最后上升到更具有一般性的概率的频率定义。 相似文献
8.
传感网络经常采用Flooding协议作为路由管理,但碰撞和重传会导致大量重复的数据包,造成有限资源的浪费.讨论了隐藏节点及邻居节点对碰撞的影响,并进行了仿真.结果表明当发射半径达到一定区域时,隐藏节点引起的碰撞数量达到一个峰值,从而可以通过合适的设计避免高碰撞概率的网络分布区域.另外,还可以通过增加传输延迟来减少节点碰撞. 相似文献
9.
任卫东 《张家口职业技术学院学报》2012,25(1):54-56
介绍基于数控加工仿真器面板的注塑模具设计流程。使用Moldflow软件对塑件的注射成型过程进行CAE分析,找出模具设计过程中可能产生各种缺陷的原因,并制定解决方案,最终确定出最优化的模具结构。在UG MoldWizard基础上,完成注塑模设计。结果表明,在实际的生产过程中,利用Moldflow进行分析在优化塑料模设计和工艺参数等方面具有指导作用。 相似文献
10.
BOT是Build-Operate-Transfer的缩写,译为建筑—运营—转移,它是利用私人部门的资金来进行传统意义上应该由公共部门专营的基础设施建设,向社会提供公共服务的一种形式。BOT模式的出现在很大程度上提高了城市基础设施的建设,在一定程度上降低了政府的管理成本,解决了现代社会政府建设城市基础设施的财政危机,但BOT并不是政府解决城市基础设施问题的灵丹妙药,其负面影响就是:公民的利益可能在BOT模式中(即公共服务市场化过程中)受损,基础设施的公益性严重缺失。 相似文献
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黄国凯 《福建工程学院学报》2019,(3):242-246
以某主跨85m钢管混凝土拱桥为研究对象,采用ANSYS建立局部精细化模型,对拱座进行受力分析。研究表明:拱梁组合体系拱桥拱座的结构刚度比较大,在拱脚最大弯矩工况下,最大变形出现在哑铃型拱肋加载截面下缘,变形值仅为4.3mm;拱座整体应力分析表明,结构受力以纵桥向受压为主,整体应力值不大,拱肋与拱座节点交界面因刚度突变出现了较大的应力变化,存在不大于1MPa的主拉应力;除了端横梁预应力锚固处压应力在10MPa左右,其他部位应力绝对值均在1MPa以下,满足要求;为了进一步优化结构受力,避免局部应力集中,应在结构中增加加腋、倒角等。 相似文献
13.
拥塞控制是计算机网络课程中的一个重点和难点。文章通过引入NS3网络仿真工具,对构建复杂混合网络实验环境的方法和步骤进行了论述,并在4∶4哑铃网络拓扑结构的基础上,实现了多个网络实验场景;以拥塞窗口大小为依据,对常见的多种拥塞控制算法进行了理论验证性实验;以吞吐量为依据,对同类拥塞控制算法之间的公平性和异类拥塞控制算法之间的友好性进行了对比实验。实验结果与理论分析相符,并对拥塞控制的算法思路和控制过程进行了形象直观的展示。 相似文献
14.
NomenclatureV-Relative velocity vectorV′-Absolute velocity vectorω-Relative vorticity vectorω′-Absolute vorticity vectorR-Pipe radiusa-Radius of cylinder for helical vortex filament2πl-Pitch of i mage helical vortex filamentQ-Flowrate in pipe with an arbitrary cross-sectionΓ-Circulation of each helical vortex filamentV0-Constant transferal velocity of vortex filaments along thez-axisΩ-Constant angular velocity of vortex filaments around thez-axis(a,χ1) ,(a,χ2) -Relative helical … 相似文献
15.
MA Hai-zhu YE Gao-xiang 《浙江大学学报(A卷英文版)》2007,8(7):991-998
The unperturbed dimension and temperature character of poly(dibenzyl itaconate)s (PDBzI) are studied by a revised rotational isomeric state (RIS) method. The improved formulas of the mean-square radius of gyration, deduced by the pseudo-stereochemical equilibrium approach, may be used to investigate the configurational-conformational properties of atactic polymers with large side groups [poly(itaconates) for instance]. The calculated results showed that poly(itaconates) have larger dimension of the molecule than other vinyl polymers. Comparison of the dimension between considering and without considering side groups showed that the effect of large side groups on the unperturbed dimension for short-chain polymers is more obvious than that of long-chain polymers and, if the dimension of side groups increases, the effect also increases. The dimension differences of PDBzI between short-chain and long-chain polymers are investigated by the relation of characteristic ratios and temperature coefficients with temperature. Moreover, the dependence between the temperature coefficients and the tacticity of chains shows that the temperature characters of the isotactic, syndiotactic and atactic PDBzI chains have remarkable difference. 相似文献
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目的：考察都匀毛尖茶中铅含量的测定方法.方法：用干法灰化法处理都匀毛尖茶茶叶试样,使用石墨炉原子化器测定.结果：铅含量在10.0ng/mL ～ 80.0ng/mL范围以内具有良好线性关系,r=0.9996,平均回收率为92.7％,RSD为2.41％.结论：该法的操作简单,适合大批量的试样分析,灰化过程中产生的污染小,精密度和加样回收率较好,可用于都匀毛尖茶中铅含量的测定. 相似文献
18.
叶子飘 《重庆大学学报(英文版)》2003,2(2)
1. Introduction J. N. Bahcall computed 7Be electron-capture consi-dering only the capture of continuum electrons and neglecting the plasma screening by the ionized gas of the star [1] . While I. Iben et al. thought that there is a finite probability that 7Be exists as an atom with one or two bound K-shell electrons [2]. They computed the capture rate of bound electron in 7Be3+ and 7Be4+ using Debye-Huckel approximation to estimate the screening effect of the ionized plasma on the rate of b… 相似文献
19.
Nicholas Rose Charles Van Horn 《Educational technology research and development : ETR & D》1956,4(1):21-30
Summary and Conclusion A showing, to a small audience, before production has begun, may be useful to give a film maker advance information about
the reactions of an audience to his film. Such tests are most useful when used early in the process of production, but not
before the material available for showing to the test audience bears a systematic resemblance to the finished film. In most
cases, the story board is the earliest stage at which a film may be tested, although exceptions are found to this rule. Testing
cannot be utilized unless the producer's intent and the target audience are specified, and is most apt to be profitable when
the content is very complex or when the production unit has had no experience with a topic or technique. Useful information
may be obtained by any alert producer, but if the target audience is heterogeneous or has not been clearly specified, or if
precise and careful predictions are needed, the services of poll and survey specialists or a phsychological test constructor
should be sought.
The production of a motion picture, as anyone who has attempted it knows, involves a series of decisions. Preproduction testing
may be viewed as a sort of “decision insurance” which, although it does not guarantee the desired outcomes, increases the
probability of their occurrence.
In the preceding article, Hoban pointed out the need for prerelease evaluation of educational communications. This paper presents
a theory and a technique for the application of such evaluation. Nicholas Rose is chief clinical psychologist, Wadsworth Hospital,
Veterans' Administration Center, Los Angeles. He was formerly research director at the Department of Cinema, University of
Southern California. Charles Van Horn is research associate, Department of Cinema, University of Southern California. 相似文献
20.
为了解决DV-HOP算法在节点随机部署环境下定位误差较大的缺点,提出一种基于DV-HOP多通信半径的加权双曲线定位算法RWHDV-HOP。该算法通过理想跳数与实际跳数的差值修正平均跳距,结合多通信半径使跳数小数化,利用基于跳数加权的双曲线算法估算未知节点坐标。仿真结果表明,在相同条件设置下,RWHDV-HOP算法定位精度比传统DV-HOP算法提高了25%,比RWDV-HOP算法提高了10%。因此,基于DV-HOP多通信半径的加权双曲线定位算法RWHDV-HOP在节点随机部署环境下能够较大程度上提高节点定位精度。 相似文献