排序方式: 共有87条查询结果,搜索用时 578 毫秒
1.
对于工学硕士的《数理统计》教学的研究 总被引:3,自引:0,他引:3
工学硕士的《数理统计》教学 ,要根据工学硕士的培养目标和数理统计课程的特点编写教材、确定讲授内容和授课方式 .力求使学员掌握处理随机数据的思考方法 ,培养解决问题、分析问题和善于应用知识的能力 .改革《数理统计》教学 ,实现和普及多媒体教学是时代发展的趋势 . 相似文献
2.
在Linux操作平台下应用FAST_wmg有限元前后处理软件对机械密封焊接金属波纹管膜片建立了有限元模型并进行了非线性有限元分析.在同等条件下对焊接金属波纹管采用了S型膜片和V型膜片,并分别进行了有限元强度评价和对比分析.结果表明,两种膜片最大应力集中都在膜片两端周围发生.这与文献所叙述的波纹管的主要失效发生在膜片两端与焊谷接近的部位非常吻合,但是,在同样边界条件下,在同样位移量时S型膜片最大应力值比V型膜片最大应力值小,压缩量大. 相似文献
3.
用随机模糊方法研究合理确定工程项目工期 总被引:1,自引:0,他引:1
谢忠镖 《数学的实践与认识》2006,36(10):41-45
站在兼顾业主与建造商的公正立场,基于网络优化技术基础上并以系统的观点,采用随机模糊数学方法研究合理确定项目工期,进而用实际项目进行分析验证,是一种科学合理确定工期的方法. 相似文献
4.
傅里叶变换红外光谱固体制样技术 总被引:2,自引:1,他引:1
通过对溴化钾与纳米固体超强酸样品的比例进行了探讨 ,得出制样时溴化钾与样品比例范围为1∶ 0 .0 0 1— 1∶ 0 .0 2 9,其最佳比例范围为 1∶ 0 .0 0 98— 1∶ 0 .0 1 5 ,并且应用于其他固体样品的测定 ,结果基本一致。同时得出 ,固体样品的最少检测量为 2 .0× 1 0 -5g 相似文献
5.
A scheme of time-dependent density functional theory (TDDFT) combined with single-excitation configuration interaction (CIS) approach was employed to make a detailed investigation of the emitting energy for fifteen well-known coumarin derivatives. The results showed that the predicted emitting energies as well as the absorption ones were dominated mainly by the exchange-correlation (XC) functional to be used. So long as a functional is properly chosen, the experimental emitting energy of most derivatives can be accurately reproduced within 0.16 eV by a calculation at the TDDFT/6-31G(d)//CIS/3-21G(d) theoretical level. It was found that, nevertheless, the hybrid functional, B3LYP, well predicted the absorption energies for all the fifteen coumarin derivatives but none of the functionals could work equally well for the emitting energy calculations. Two pure functionals, OLYP and BLYP, yield good emitting energies for the 7-aminocoumarins or derivatives with a N atom connected to 7-position, which exhibit inconspicuous charge transfer (CT) in their excited states, whereas the B3LYP hybrid functional, with 20% Hartree-Fock (HF) exchange energy, performs significantly better than OLYP and BLYP for those 3-substituted coumarins with larger CT in excited states. Thus, in comparison with the absorption energies, the selection of proper functionals for the emitting energy calculations becomes more complex. In all probability, it is effective and doable to choose an XC-functional with alterable fraction of HF exchange energy according to the composition and structure characteristics of molecule. 相似文献
6.
为了解决现有镜面偏心测量设备存在的问题,本文研究了一种采用切换镜头和调焦相结合的方法来设计的镜面偏心测量光学系统,使用这个光学系统,既能使被测镜面的曲率半径扩展到-∞~+∞范围,又能保证测量精度。通过Lighttools软件对这个光学系统进行光线追迹,分析其杂光分布,结果表明:准直镜头内部多次反射产生的杂光强度很低,可以忽略。而当被测镜头中存在相邻球心像距的镜面时,产生的杂光强度比较大,在后续的图像处理过程中,必须增强目标图像的对比度。利用研制的镜面偏心测量设备进行测量实验,结果进一步验证了杂光分析的正确性。 相似文献
7.
The fluorescent spectrum and the excitation spectrum were used to present the cluster molecular structure feature in ethanol-water solutions.Through analyzing the fluorescent characteristics of an excimer,it is proposed that the excimers are formed between the ethanol-water cluster molecules in the excited state and in the ground state.The fluorescent lifetime and the fluorescent intensity decay process give information about the photo-physical and photo-chemical processes of the formation and the dissociation of an excimer.The theoretical calculation and physical analysis coincide with the experimental results.The preliminary conclusion about the structure feature of ethanol-water cluster molecule is that it has a planar one like a sandwich. 相似文献
8.
In line with current efforts to understand the piece-by-piece structure and articulation of children’s mathematical concepts, this case study compares the reversibility schemes of two eighth-grade students. The aim of the study was to identify the mechanism through which students reverse their thought processes in a multiplicative situation. Data collected through clinical interviews depict the precise strategies that the participants used to work back to find the missing values in an inverse proportional task. This study also illustrates how a conceptual template generated by one of the participants afforded him considerable flexibility in the multiplicative task. Another outcome of the study is that it shows how the numerical characteristics of the parameters in the problem affected the students’ ability to reverse their thought processes. We infer that there is a need for further research on how students might represent their reversibility schemes in the form of algebraic equations. 相似文献
9.
10.
矢量分析在反射和折射中的应用 总被引:2,自引:2,他引:0
利用反射定律和折射定律的矢量公式计算出平面转镜和道威棱镜的转像规律. 相似文献