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1.
We aim to theoretically investigate the focusing property of a 4Pi configuration under the illumination of azimuthally polarized high-order Bessel–Gaussian beams. The radial component is produced in the focal region through the introduction of a spiral phase plate. The focal region differs from the zero radial intensity component of the azimuthally polarized beams without the spiral phase plate. The spherical focal spot is generated by selecting an appropriate annular obstruction. The position of the focal spot can be shifted.  相似文献   
2.
旋转回归分析在预防病虫害中的应用   总被引:9,自引:1,他引:8  
旋转回归分析在预防病虫害中的应用.通过旋转回归正交试验,对农业三项措施与玉米大斑病发生发展关系及规律进行深入研究。创建了玉米大斑病与农业措施关系的总回归模型及六个子模型。通过实践检验,肯定了模型的可靠性和应用的有效性。为农业生产起到了很好的指导作用  相似文献   
3.
    
A multi‐scale model is used to simulate columnar dendritic growth in TIG (tungsten inert‐gas) weld molten pool of Al‐Cu alloy. The grain morphologies at the edge of the weld pool are studied. The simulated results indicate that the average primary dendrite spacing changes during the solidification process in the weld pool because of the complicated thermal field, solute diffusion field and competitive growth. And it is shown that the secondary dendrite arms grow insufficiently in the space between dendrite trunks if the primary dendrite spacing is small. And the phenomenon has been explained by analyzing the influence of the solute accumulation on the constitutional undercooling and undercooling gradient when there are two different opposite solute diffusion fields. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   
4.
    
A method is outlined that allows the determination of one‐dimensional stress gradients at length scales greater than 0.2 mm. By using standard four‐circle X‐ray diffractometer equipment and simple aperture components, length resolutions down to 0.05 mm in one direction can be achieved through constant orientation of a narrow, line‐shaped beam spot. Angle calculations are given for the adjustment of goniometer angles, and for the effective azimuth and tilt of the scattering vector for general angle settings in a four‐circle goniometer. The latter is necessary for the computation of stresses from lattice strain measurements.  相似文献   
5.
一种桁架结构智能生成与分析系统   总被引:1,自引:0,他引:1       下载免费PDF全文
建立了桁架结构的智能生成与分析系统,可以自动完成桁架结构的布局选型、拓扑生成以及分析计算等系列过程. 主要通过结点布置和有选择的杆件连接实现结构的布局选型,采用拓扑变化法完成结构的自动生成,并利用基内力阵进行结构的分析计算. 经算例分析表明,该系统性能良好,使用方便,具有智能、自适应的特点,是辅助完成结构拓扑和布局优化设计的有力工具之一.  相似文献   
6.
    
A plug‐in (EXTRAX) has been developed for ImageJ– a public domain Java‐based program widely used for image processing and analysis in microscopy. This plug‐in allows the extraction and measurement of intensities from electron diffraction spot patterns with a semi‐automatic peak location based on a two‐dimensional lattice given by the user. It is also possible to take into account supplementary spots originating from high‐order Laue zones and/or the existence of a modulation vector.  相似文献   
7.
    
The finite difference model is coupled with a cellular automaton (CA) model to simulate dendrite growth in TIG (tungsten inert‐gas) weld molten pool of nickel‐based alloys. Based on the macro finite difference computation of the thermal field of the whole weldment, the micro CA model is used to simulate grain formation process in 2‐dimension area within weld molten pool. The results illustrate that the complicated thermal field and solute field can lead to complex grain morphologies in weld molten pool. The primary dendrite spacing changes during welding solidification process and the final primary dendrite spacing is decided by the thermal field, solute field and other parameters. And it is indicated that the grain boundary segregation has important relationship with welding speed. The grain boundary segregations become more severe as the welding speed increases when the other parameters are kept unchanged. (© 2007 WILEY ‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   
8.
应用最小二乘法准则,并改进了层次分析法判断矩阵的构成,获得考虑专家评价水平的诸影响因素权向量;基于集值统计法和属性数学原理,建立了对高等级公路路线方案量化综合评价优选模型,并给出了计算实例.  相似文献   
9.
In this paper, a permutation-based genetic algorithm (GA) is applied to the NP-hard problem of arranging a number of facilities on a line with minimum cost, known as the single row facility layout problem (SRFLP). The GA individuals are obtained by using some rule-based as well as random permutations of the facilities, which are then improved towards the optimum by means of specially designed crossover and mutation operators. Such schemes led the GA to handle the SRFLP as an unconstrained optimization problem. In the computational experiments carried out with large-size instances of sizes from 60 to 80, available in the literature, the proposed GA improved several previously known best solutions.  相似文献   
10.
1.IntroductionLaserdiodehasbeenx`idelyusedinfibrc-opticcommunicat:onandopticaldisk$yctems.LaserbeamIsradiationangle(fullangu1aratha1f-maximumintensitypoint)ismeasuredbothparllelandPerpendiculartothcjunctionp1anclgenera1ly.o//=6,~1o",oJ-=2o"~5O':Inerasableopticaldisksystemsasmagneto-optica1disksystems,thelaserbcamiscollimatedandshapedtobecircularsymInetricbeaminordcrtoaquireahighintensityandhighqualityscanningbeamiPot,butitsoptica1systemiscomplicatedandeasyaddingassocialaberration.usingaellip…  相似文献   
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