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2.
一般教材在讨论夫琅和费单缝衍射时都没有考虑倾斜因子对光强分布的影响，本给出了考虑倾斜因子时的光强分布，并指出当缝的宽度较宽时，倾斜因子的影响可以忽略． 相似文献
3.
Preschool children can navigate by simple geometric maps of the environment, but the nature of the geometric relations they use in map reading remains unclear. Here, children were tested specifically on their sensitivity to angle. Forty‐eight children (age 47:15–53:30 months) were presented with fragments of geometric maps, in which angle sections appeared without any relevant length or distance information. Children were able to read these map fragments and compare two‐dimensional to three‐dimensional angles. However, this ability appeared both variable and fragile among the youngest children of the sample. These findings suggest that 4‐year‐old children begin to form an abstract concept of angle that applies both to two‐dimsional and three‐dimensional displays and that serves to interpret novel spatial symbols. 相似文献
4.
李辉 《兰州石化职业技术学院学报》2008,8(3):78-80
随机变量的统计规律是一个复杂的概念。通过对典型实例的分析研究,揭示出一维离散型随机变量的形成过程及其变化规律。具体描述了样本点与随机变量之间的对应关系及事件与随机变量取值之间的等价关系,得出掷硬币正面出现的“总次数”近似服从正态分布,据此可刻划“掷硬币正面出现”这一随机现象的统计规律性． 相似文献
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李慧 《贵州教育学院学报》2003,14(2):52-55
在乎面应力状态分析中，通过取出受力构件内某点的应力状态，便可以求出任意斜截面上的应力和主应力，从而对复杂受力构件作强度计算。这是单元体上两微面间相互垂直的特殊情况下进行的。当两微面相互不垂直时，求解未知应力就比较因难。本文经过研究，找出了任意两截面上应力之间的关系，并研究用应力圆表示。这对求解复杂受力构件内任意两截面上的应力，带来较大的方便，提供了一个新的方法，并举例说明它的应用。 相似文献
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利用分布函数法求二维连续型随机变量函数的分布密度是通用的方法,但这种方法在具体实施中会遇到计算上的麻烦,本文着重对使用变量变换法求二维连续型随机变量的函数的分布密度进行了探讨,并得出了若干结论。 相似文献
7.
WEN Liang-ying OU Yang-qi BAI Chen-guang WANG Hua 《重庆大学学报(英文版)》2005,4(4):195-198
1 Introduction 1 For pulverized coal injected into a blast furnace, the space from the outlet of the coal gun to the center of the raceway is the key district for the coal’s burning and also for works to probe hearth state. Remarkable achievements have been made in research on numerical simulation of combustion processes [1], but further advances are hindered owing to the limits of the means to examine three-dimension parameter distribution in the furnace. Temperature is the most basic parame… 相似文献
8.
徐晓军 《潍坊教育学院学报》2009,22(3):55-57
在建筑装饰设计中,色彩是十分重要而富有魅力的艺术语言,借助它可以在一个二度或三度空间中创造出惊人的视觉真实和独特的艺术效果。正确地认识和理解把握建筑装饰中的色彩是运用好色彩的前提和基础。 相似文献
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何燕 《鞍山师范学院学报》2009,11(6):23-25
采用元胞自动机方法对多晶金属热变形中的动态再结晶过程建立了二维模型．模型模拟了热加工变形中动态再结晶过程．通过模拟可以得到热变形金属的微观组织形貌和变形后晶粒的大小与分布,再现了再结晶组织的微观特征．结果与实验观察到的热变形组织形貌基本符合,并分析了热加工参数对再结晶组织形貌的影响． 相似文献
10.
应用发光细菌进行水质监测的初步研究 总被引：1，自引：0，他引：1
用青海弧菌(Vibro qinghaiensis)67号菌株作为指示生物,以其发光强度为指标来进行水质监测和评价,继而确定污水的污染程度。试验表明:用适当的缓冲液,在合适的pH和菌液浓度下,细菌的发光强度与污水的污染程度呈负相关性。 相似文献
11.
Image reconstruction in elecrical impedance tomography(EIT)is a highly ill-posed inverse problem,Regularization techniques must be used in order to solve the problem,In this paper,a new regularization method based on the spatial filtering theory is proposed.The new regularized reconstruction for EIT is independent of the estimation of impedance distribution,so it can be implemented more easily than the maxiumum a posteriori(MAP) method.The regularization level in our proposed method varies spatially so as to be suited to the correlation character of the object‘s impedance distribution.We implemented our regularization method with two dimensional computer simulations.The experimental results indicate that the quality of the reconstructed impedance images with the descibed regularization method based on spatial filtering theory is better than that with Tikhonov method. 相似文献
12.
在光源非单色性模型——三角形模型下，求出了光强分布与光程差之间的关系，应用MATLAB软件模拟出了光强分布曲线，并对该模型下干涉条纹的可见度进行了分析。 相似文献
13.
讨论了n维k（n,k∈N）次有限元空间逆估计不等式右端常数因子的界定问题.针对n维k（n,k∈N）次有限元空间,采取n单体剖分,结合Pk型Lagrange插值基函数,利用条件极值和Matlab软件,提出了计算n维k次有限元空间中逆估计不等式右端常数因子下确界的一种通用方法.利用该方法,对二维k（1≤k≤4）次有限元空间中逆估计不等式右端常数因子的下确界进行了具体计算,并且得到了下确界C 2,k的具体数值为：C 2,1=12,C 2,2≈25.0664,C 2,3≈40.0206,C 2,4≈82.3844. 相似文献
14.
A teaching tool that facilitates student understanding of a three‐dimensional (3D) integration of dermatomes with peripheral cutaneous nerve field distributions is described. This model is inspired by the confusion in novice learners between dermatome maps and nerve field distribution maps. This confusion leads to the misconception that these two distribution maps fully overlap, and may stem from three sources: (1) the differences in dermatome maps in anatomical textbooks, (2) the limited views in the figures of dermatome maps and cutaneous nerve field maps, hampering the acquisition of a 3D picture, and (3) the lack of figures showing both maps together. To clarify this concept, the learning process can be facilitated by transforming the 2D drawings in textbooks to a 3D hands‐on model and by merging the information from the separate maps. Commercially available models were covered with white cotton pantyhose, and borders between dermatomes were marked using the drawings from the students' required study material. Distribution maps of selected peripheral nerves were cut out from color transparencies. Both the model and the cut‐out nerve fields were then at the students' disposal during a laboratory exercise. The students were instructed to affix the transparencies in the right place according to the textbook's figures. This model facilitates integrating the spatial relationships of the two types of nerve distributions. By highlighting the spatial relationship and aiming to provoke student enthusiasm, this model follows the advantages of other low‐fidelity models. Anat Sci Educ 6: 277–280. © 2013 American Association of Anatomists. 相似文献
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研究了一个三维的孤立子方程的B(a)cklund变换(BT)和非线性叠加公式,证明了文[3,4]中的三维的B(a)cklund变换可以分解成三个二维的B(a)cklund变换,并讨论了一些与N维Liouville方程有关的问题. 相似文献
17.
April Richardson‐Hatcher Matthew Hazzard German Ramirez‐Yanez 《Anatomical sciences education》2014,7(6):469-478
Visualization of the complex courses of the cranial nerves by students in the health‐related professions is challenging through either diagrams in books or plastic models in the gross laboratory. Furthermore, dissection of the cranial nerves in the gross laboratory is an extremely meticulous task. Teaching and learning the cranial nerve pathways is difficult using two‐dimensional (2D) illustrations alone. Three‐dimensional (3D) models aid the teacher in describing intricate and complex anatomical structures and help students visualize them. The study of the cranial nerves can be supplemented with 3D, which permits the students to fully visualize their distribution within the craniofacial complex. This article describes the construction and usage of a virtual anatomy platform in Second Life?, which contains 3D models of the cranial nerves III, V, VII, and IX. The Cranial Nerve Skywalk features select cranial nerves and the associated autonomic pathways in an immersive online environment. This teaching supplement was introduced to groups of pre‐healthcare professional students in gross anatomy courses at both institutions and student feedback is included. Anat Sci Educ 7: 469–478. © 2014 American Association of Anatomists. 相似文献
18.
对任意二维物体的无升力绕流问题进行了研究。简述了求解任意二维物体绕流的源面元法,编制了计算机源程序,对单体和群体绕流的流体动力特性进行了计算。计算结果表明,这是一种实用、快速、有效的数值解法。用这种方法求得的数值解同解析解吻合得非常好,误差在整个区域上分布比较均匀。 相似文献
19.
Jean Langlois Christian Bellemare Josée Toulouse George A. Wells 《Anatomical sciences education》2017,10(3):235-241
Anatomy knowledge has been found to include both spatial and non‐spatial components. However, no systematic evaluation of studies relating spatial abilities and anatomy knowledge has been undertaken. The objective of this study was to conduct a systematic review of the relationship between spatial abilities test and anatomy knowledge assessment. A literature search was done up to March 20, 2014 in Scopus and in several databases on the OvidSP and EBSCOhost platforms. Of the 556 citations obtained, 38 articles were identified and fully reviewed yielding 21 eligible articles and their quality were formally assessed. Non‐significant relationships were found between spatial abilities test and anatomy knowledge assessment using essays and non‐spatial multiple‐choice questions. Significant relationships were observed between spatial abilities test and anatomy knowledge assessment using practical examination, three‐dimensional synthesis from two‐dimensional views, drawing of views, and cross‐sections. Relationships between spatial abilities test and anatomy knowledge assessment using spatial multiple‐choice questions were unclear. The results of this systematic review provide evidence for spatial and non‐spatial methods of anatomy knowledge assessment. Anat Sci Educ 10: 235–241. © 2016 American Association of Anatomists. 相似文献
20.
运用算子论的方法，把有限维情况下幂等算子的和与差仍是幂等算子成立的一些条件推广到无限维的情况，给出了在无限维的情况下幂等算子的和与差仍是幂等算子的充要条件，并且进一步得到了幂等算子的线性组合也是幂等算子的充要条件。 相似文献