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1.
Two-dimensional irregular polygons packing problem is very difficult to be solved in traditional optimal way.Simulated annealing (SA) algorthm is a stochastic optimization technique that can be used to solve packing problems.The whole process of SA is introduced firstly in this paper,An extended neighborhood searching method in SA is mainly analyzed,A general module of SA algorithm is given and used to lay out the irregular polygons.The judgment of intersection and other constrains of irregular polygons are analyzed,Then an example that was used in the paper of Stefan Jakobs is listed .Results show that this SA algorithm shorterns the computation time and improves the soluiton. 相似文献
2.
In the conventional differential quadrature (DQ) method the functional values along a mesh line are used toapproximate derivatives and its application is limited to regular regions. In this paper, a local differential quadrature (LDQ)method was developed by using irregular distributed nodes, where any spatial derivative at a nodal point is approximatedby a linear weighted sum of the functional values of nodes in the local physical domain. The weighting coefficients in thenew approach are determined by the quadrature rule with the aid of nodal interpolation. Since the proposed method directlyapproximates the derivative, it can be consistently well applied to linear and nonlinear problems and the mesh-free feature isstill kept. Numerical examples are provided to validate the LDQ method. 相似文献
3.
以14种不同的红茶为分析对象,采用超声波提取法提取其黄酮类化合物,并用三波长-光谱法对其含量进行测定.采用三波长-光谱法有效地消除了红茶中由于黄酮类化合物光谱吸收峰的不对称给定量分析造成的影响,并校正了基于干扰组分的吸收光谱具有线性吸收产生的基线倾斜.加入铝盐使得黄酮类化合物与铝离子形成稳定的配合物,吸收带I明显红移,则吸光度大大增加.实验结果,回归方程为△A=0.017 1C＋0.020 0,相关系数r=0.999 8;说明黄酮的浓度在8.00~48.00μg/mL范围内,波长分别在λ=295 nm、λ=270 nm、λ=250 nm处测吸光度时△A与浓度C呈良好线性关系,可按标准曲线法进行定量分析.本方法的回收率为97.9%~101.2%,变异系数小于0.20%.方法的准确度与精密度均令人满意,而且操作简便易行. 相似文献
4.
Elias Hemelsoet 《Educational theory》2011,61(6):659-669
In this article Elias Hemelsoet questions the way irregular migrants are approached in educational policymaking. In most cases, estimations of the number of irregular migrants serve—despite large methodological problems—as a starting point for policymaking. Given the very diverse composition of this group of people, the question is whether residence status is an appropriate benchmark for dealing with the social problems related to these people. There seems to be a homogenizing tendency at work that reduces the complexity of irregular migration. Preferable distinctions are overlooked or even denied. Inclusive education seems to provide an alternative that does not reduce individuals to a group they belong to, claiming that differences only matter at the individual level. The question is whether such an approach entails a new form of homogenization. Using the case of Roma people, Hemelsoet argues here that group differences do matter for educational practice, theory, and policy. Qualitative data on the social practices of groups can help provide insight into the particularity of situations. This “insight” or “understanding,” in its turn, is a requirement in order for policymakers to make well‐considered choices. 相似文献
5.
B. Sury 《Resonance》2017,22(10):943-953
Greeks used the method of cutting a geometric region into pieces and recombining them cleverly to obtain areas of figures like parallelograms. In such problems, the boundary is ignored. However, in our discussion, we will take every point of space into consideration. The human endeavour to compute lengths, areas, and volumes of irregular complicated shapes and solids created the subject of ‘measure theory’. The paradox of the title can be informally described as follows. Consider the earth including the inside stuff. It is possible to decompose this solid sphere into finitely many pieces and apply three-dimensional rotations to these pieces such that the transformed pieces can be put together to form two solid earths! The whole magic lies in the word ‘pieces’. The pieces turn out to be so strange that they cannot be ‘measured’. 相似文献
6.
非正规就业被称为吸纳劳动力的“蓄水池”。目前，我国的非正规就业已经成为促进就业的重要渠道。非正规就业的“不正规”决定了它在发展中出现了诸多问题，应当采取各种措施规范其发展。 相似文献
7.
利用自制的流通池,提出了流动注射分析与光散射光谱法联用的测定技术;探讨了铜的流动注射和光散射光谱测定工作条件,铜的线性范围为0～400μg/mL,检出限为3.266μg/mL,测定频率为48次/h;实验结果表明所建立的方法快速、所需的化学试剂少. 相似文献
8.
Analytical solution for electromagnetic scattering from a sphere of uniaxial left-handed material 总被引：2，自引：0，他引：2
INTRODUCTION The concept of left-handed materials (LHM for short, also called negative index materials) was in- troduced by Veselago (1968). An LHM has both negative permittivity and negative permeability, which makes the wave vector, the electric-field vector, and the magnetic-field vector in the LHM obey the left-hand rule. Experimental verifications for the existence of an LHM were made and its use as a perfect lens was suggested (Pendry, 2000; Shelby et al., 2001a; 2001b; Smith … 相似文献
9.
《普通话水平测试实施纲要》中的朗读作品理应在语言应用方面起到规范和表率作用。如果原作品在此方面存在不规范的问题, 那么编委可以而且应该予以修改, 使之规范。然而, 《纲要》朗读作品中语言不规范甚至有语病的问题, 还是屡见不鲜。有些问题, 是不能以“省略”或“用语求简”来掩饰的。省略, 不能导致成分残缺; 用语求简, 也不能不讲语法和逻辑。这些问题如不解决, 将对读者造成一定的不良影响。 相似文献
10.
评价初中生物教育的主要内容是：师资条件、实验条件、开课学时、实验教学、教学环节及课外活动。调查结果显示：部分乡镇初中不按规定开设生物教育课，基本不做生物实验，无专职合格生物教师。扭转目前状况的主要对策是更新教育观念，加强规范管理，贯彻素质教育精神；重视生物教育的基础地位，重组教师队伍，改善办学条件；改善教学方法；改革中考制度。 相似文献
11.
CHEN Jun-sheng MO Hai-hong 《浙江大学学报(A卷英文版)》2006,7(11):1864-1869
INTRODUCTION Shield tunnel method has become the most pre- ferred method in city tunnel construction because of its excellent attributes: little effect on surrounding environment, fast and safe construction, outstanding performance in earthquake resistance, etc. (Zhang et al., 2004). In different shield tunnels, the arrangement and number of segments are different, but the whole assembling process is generally the same. The as- sembling process begins with A2P, then A1P, A3P, BP, CP, … 相似文献
12.
INTRODUCTION Electrodes or grooves in the path of surface acoustic wave (SAW) propagation give rise to SAW reflection and cause SAW scattering into bulk acous- tic wave. This is a fundamental SAW problem on which had been conducted many studies. It is espe- cially important for designing SAW radio frequency identification tags (RFID). Global SAW Tag (GST) (Hartmann, 2004) has many advantages over tradi- tional SAW RFID, but requires accurate knowledge of the reflectivity and … 相似文献
13.
运用模式匹配法，分析了圆-圆形槽波导结的散射特性．在圆-圆形槽波导结上匹配电场和磁场的边界条件，然后在边界方程两边同乘以圆波导和圆形槽波导的模式方程，得到了散射矩阵方程，结的散射系数可由此方程得出．然后分析了圆形槽波导中放置圆形膜片的散射特性．最后讨论了数值计算结果的收敛性；当选择恰当的模式组时，得到了收敛的数值结果，同时给出了膜片散射系数的频率响应结果． 相似文献
14.
李美 《雁北师范学院学报》2004,20(5):62-63
在学习高等数学的过程中,往往会形成一种思维的定势,局限解题思路.本文主要通过实例说明思维 不应该定势,而要充分发挥自己灵活思考,独立解决问题的能力,开发创新思维. 相似文献
15.
试论中国第三方物流发展的现状、存在问题及若干对策 总被引：6，自引：0，他引：6
王玲玲 《柳州职业技术学院学报》2004,4(2):12-16
我国现代物流行业的发展尚处于起步阶段，第三方物流市场存在着经营理念滞后、经营水平不高、地方性政策制约、市场管理不规范、专业人才匮乏、相应的法律法规还不能及时跟上等诸多问题。要促进我国第三方物流的发展，必须针对这些问题及时采取相应的对策。 相似文献
16.
文章对标准抛物线方程（SPE）的分裂步傅里叶变换（SSFT）方法进行了详细的分析,引入一种适合SPE的不规则地形建模方式,利用SSFT算法计算自由空间与不规则地形的电波传播问题,与经典理论计算所得的结果相当吻合。 相似文献
17.
激光相位多普勒技术 (PDA)是目前公认有效的多参数粒子测量技术之一 ,但是PDA对粒子的非球形特性极为敏感 .本文分析了粒子的非球形特性对PDA的影响 ,明确了PDA信号参数与粒子非球形特性的关系 ,表明非球形粒子条件下的PDA信号相位差是理想粒子条件下PDA信号相位差的无偏估计 .提出了基于对象分类识别的非球形粒子的检测方法 ,利用模糊模式识别中的群体识别技术 ,计算对象特性与参照物特性的贴近度 ,根据择近原则判断对象的类别及数量 .实验表明 ,不规则粒子的统计分类及其识别具有实用价值 相似文献
18.
非正规就业是扩大我国就业渠道的现实选择,能有效增加就业岗位,能提供了灵活、多样性的就业空间,为就业制度改革提供了必要保证。根据我国当前的非正规就业现状,笔者针对弱势群体的非正规就业提出了几点建议。 相似文献
19.
Nanostructures enhance phonon scattering and improve the figure of merit of thermoelectric materials. Nanosized CoSb3 skutterudite was synthesized by solvothermal methods using CoCl2 and SbCl3 as the precursors. A "two-step" model was suggested for the formation of CoSb3 based on the X-ray diffraction analysis. The first step is the formation of cobalt diantimonide in the earlier stage during the synthesis process. Diantimonide was then combined with antimony atoms to form the skutterudite structured triantimonide, CoSb3, in the later stage of the synthesis process as the second step. The synthesized CoSb3 powders consist of irregular particles with sizes of about 20 nm and sheets of about 80 nm. 相似文献
20.
Nanostructures enhance phonon scattering and improve the figure of merit of thermoelectric materials. Nanosized CoSb3 skutterudite was synthesized by solvothermal methods using CoCl2 and SbCl3 as the precursors. A "two-step" model was suggested for the formation of CoSb3 based on the X-ray diffraction analysis. The first step is the formation of cobalt diantimonide in the earlier stage during the synthesis process. Diantimonide was then combined with antimony atoms to form the skutterudite structured triantimonide, CoSb3, in the later stage of the synthesis process as the second step. The synthesized CoSb3 powders consist of irregular particles with sizes of about 20 nm and sheets of about 80nm. 相似文献