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141.
张居舟 《分析测试技术与仪器》2011,17(2):79-82
建立了用正己烷超声提取食品塑料包装材料中的邻苯二甲酸二烯丙酯,经滤纸过滤,浓缩定容后采用选择离子模式对其进行气相色谱-质谱联机分析,外标法定量.方法对食品塑料包装材料中的邻苯二甲酸二烯丙酯的检测限为10.0μg/kg,检测浓度范围为10~500μg/L,样品的加标回收率为80%~110%,可满足食品塑料包装材料中邻苯二... 相似文献
142.
143.
拟对称集和拟圆周集是万有Teichm(u|¨)er空间中两个常用模型.对于任一个由K-拟圆周诱导的拟对称,应用有界度圆填充的方法,构造了其近似映射,并证明了这些近似映射一致收敛于该拟对称. 相似文献
144.
We study a differential game of approach in a system whose dynamics is described by a Sobolev‐type second‐order operator differential equation in Hilbert spaces. Solutions of the equation are represented by cosine and sine operator functions. To obtain solvability conditions of the game problem, we use support functionals of two sets, which defined by the behaviors of pursuer and evader. The results are applied to the investigation of conflicted‐controlled dynamics of bending waves in a rod. 相似文献
145.
The Apollonian packings (APs) of spheres are fractals that result from a space-filling procedure. We discuss the finite size effects for finite intervals s?∈?[s min,?s max] between the largest and the smallest sizes of the filling spheres. We derive a simple analytical generalization of the scale-free laws, which allows a quantitative study of such physical fractals. To test our result, a new efficient space-filling algorithm has been developed which generates random APs of spheres with a finite range of diameters: the correct asymptotic limit s min/s max?→?0 and the known APs' fractal dimensions are recovered and an excellent agreement with the generalized analytic laws is proved within the overall range of sizes. 相似文献
146.
以脱氧核糖核酸和工程中的细长结构为背景, 大变形大范围运动的弹性杆动力学受到关注. 将分析力学方法运用到精确Cosserat弹性杆动力学, 旨在为前者拓展新的应用领域, 为后者提供新的研究方法. 基于平面截面假定, 在弯扭基础上再计及拉压和剪切变形形成精确Cosserat弹性杆模型. 用刚体运动的概念描述弹性杆的变形, 导出弹性杆变形和运动的几何关系; 在定义截面虚位移及其变分法则的基础上, 建立用矢量表达的d’Alembert-Lagrange原理, 在线性本构关系下化作分析力学形式, 并导出Lagrange方程和Nielsen方程, 定义正则变量后化作Hamilton正则方程; 对于只在端部受力的弹性杆静力学, 导出了将守恒量预先嵌入的Lagrange方程, 并讨论了其首次积分. 从弹性杆的d’Alembert-Lagrange原理导出积分变分原理, 在线性本构关系下化作Hamilton原理. 形成的分析力学方法使弹性杆的全部动力学方程具有统一的形式, 为弹性杆动力学的对称性和守恒量的研究及其数值计算铺平道路.
关键词:
精确Cosserat弹性杆
分析动力学方法
变分原理
Lagrange方程 相似文献
147.
Marek Janata 《Discrete Mathematics》2007,307(16):2002-2007
Let T be a family of graphs. A T-packing of a graph G is a subgraph of G, components of which are isomorphic to members of T. We are concerned with families T, such that in every graph G, the subsets of vertices that can be saturated by some T-packing form a collection of independent sets of a matroid. The main purpose of this paper is to introduce a new class of families with this property. 相似文献
148.
Christian Prins 《Journal of Mathematical Modelling and Algorithms》2002,1(2):135-150
The basic Vehicle Routing Problem (VRP) consists of computing a set of trips of minimum total cost, to deliver fixed amounts of goods to customers with a fleet of identical vehicles. Few papers address the case with several types of vehicles (heterogeneous fleet). Most of them assume an unlimited number of vehicles of each type, to dimension the fleet from a strategic point of view. This paper tackles the more realistic tactical or operational case, with a fixed number of vehicles of each type, and the optional possibility for each vehicle to perform several trips. It describes several heuristics, including a very efficient one that progressively merges small starting trips, while ensuring that they can be performed by the fleet. This heuristic seeks to minimize the number of required vehicles as a secondary objective. It outperforms classical VRP heuristics, can easily handle various constraints, and gives very good initial solutions for a tabu search method. The real case of a French manufacturer of furniture with 775 destination stores is presented. 相似文献
149.
Optimal lower bounds for cubature error on the sphere 总被引:6,自引:1,他引:5
We show that the worst-case cubature error E(Qm;Hs) of an m-point cubature rule Qm for functions in the unit ball of the Sobolev space Hs=Hs(S2),s>1, has the lower bound , where the constant cs is independent of Qm and m. This lower bound result is optimal, since we have established in previous work that there exist sequences of cubature rules for which with a constant independent of n. The method of proof is constructive: given the cubature rule Qm, we construct explicitly a ‘bad’ function fmHs, which is a function for which Qmfm=0 and . The construction uses results about packings of spherical caps on the sphere. 相似文献
150.
In this paper, we present a non-linear one-dimensional model for thin-walled rods with open strongly curved cross-section, obtained by asymptotic methods. A dimensional analysis of the non-linear three-dimensional equilibrium equations lets appear dimensionless numbers which reflect the geometry of the structure and the level of applied forces. For a given force level, the order of magnitude of the displacements and the corresponding one-dimensional model are deduced by asymptotic expansions. 相似文献