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新课标提出:问题是探究的起点,一切数学教学都应该从问题出发,到更高一级问题的产生.问题中心是指课堂教学中教师、学生围绕问题所形成的系统,课堂藉以问题形式展开,学生通过问题学习,教师经由问题组织教学.其核心是教学始终把问题作为学生发展的载体,用基本问题及其解决来建构知识,让学生自觉、主动地发现问题、提出问题、探究问题、形成问题意识.…… 相似文献
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新课标提出:问题是探究的起点,一切数学教学都应该从问题出发,到更高一级问题的产生.问题中心是指课堂教学中教师、学生围绕问题所形成的系统,课堂藉以问题形式展开,学生通过问题学习,教师经由问题组织教学.其核心是教学始终把问题作为学生发展的载体,用基本问题及其解决来建构知识,让学生自觉、主动地发现问题、提出问题、探究问题、形成问题意识.…… 相似文献
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新课标提出:问题是探究的起点,一切数学教学都应该从问题出发,到更高一级问题的产生.问题中心是指课堂教学中教师、学生围绕问题所形成的系统,课堂藉以问题形式展开,学生通过问题学习,教师经由问题组织教学.其核心是教学始终把问题作为学生发展的载体,用基本问题及其解决来建构知识,让学生自觉、主动地发现问题、提出问题、探究问题、形成问题意识.1.问题情境教学的含义以问题为中心组织教学,强调把学习设置到有意义的问题情景中,这就需要教者尽心设计问题情境.所谓问题情境教学,就是教学中将数学课程本身与现实生活中所熟悉的问题或学生个… 相似文献
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《数学的实践与认识》2015,(8)
货郎问题(TSP)是研究计算复杂性理论的经典问题.在货郎问题的基础上,提出"数学家货郎问题"(MTSP).经过研究发现,数学家货郎问题是一个典型的NP类问题,但它却不属于P类问题.因此,数学家货郎问题是一个NP类问题与P类问题不相等的例证. 相似文献
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高考数学应用题十年回顾 总被引:1,自引:0,他引:1
自1995年在高考中引入数学应用问题起,为培养中学生数学应用意识的新题型——数学应用题成为每年数学高考的一道“大菜”,从简单的贺卡分配问题到复杂的价格问题、人口耕地粮食问题、全程运输成本问题,污水处理的质量分数问题、带钢冷轧减薄问题、西红柿的种植与成本问题、旅游业的投入产出问题,汽车保有量问题,台风预报问题等,逐步形成贴近课本、贴近生活、贴近学生实际,贴近问题的实际, 相似文献
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该文研究三种新变形的全一问题及最小全一问题. 原始的全一问题可被形象的称为顶点点亮顶点问题, 而这三类新问题则分别被称为顶点点亮边问题,边点亮顶点问题,边点亮边问题. 顶点点亮顶点问题已经得到了广泛的研究. 比如,解的存在性问题和求解的有效算法已经被解决,一般图上的最小顶点点亮顶点问题已经被证明是NP- 完备的,树、单圈图和双圈图上的最小顶点点亮顶点问题的线性时间最优算法也已被给出等. 该文对于顶点点亮边问题,证明一个图有解当且仅当它是二部图,因此只可能有两组解和最优解. 对于边点亮顶点问题,证明一个图有解当且仅当它包含偶数个顶点,并通过将其最优问题多项式变换成最小权的完美匹配问题,得出一般图上的最小边点亮顶点问题可在多项式时间内求解. 边点亮边问题可归约成线图上的顶点点亮顶点问题. 相似文献
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《Operations Research Letters》2023,51(1):84-91
In this paper, we study the bilevel programming problem with discrete polynomial lower level problem. We start by transforming the problem into a bilevel problem comprising a semidefinite program (SDP for short) in the lower level problem. Then, we are able to deduce some conditions of existence of solutions for the original problem. After that, we again change the bilevel problem with SDP in the lower level problem into a semi-infinite program. With the aid of the exchange technique, for simple bilevel programs, an algorithm for computing a global optimal solution is suggested, the convergence is shown, and a numerical example is given. 相似文献
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J. R. WillemsA. V. Cabot 《Mathematical and Computer Modelling》1995,21(12):75-84
In this paper, we present a branch and bound algorithm for solving the constrained entropy mathematical programming problem. Unlike other methods for solving this problem, our method solves more general problems with inequality constraints. The advantage of the proposed technique is that the relaxed problem solved at each node is a singly constrained network problem. The disadvantage is that the relaxed problem has twice as many variables as the original problem. An application to regional planning is given, and an example problem is solved. 相似文献
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The multilevel generalized assignment problem is a problem of assigning agents to tasks where the agents can perform tasks at more than one efficiency level. A profit is associated with each assignment and the objective of the problem is profit maximization. Two heuristic solution methods are presented for the problem. The heuristics are developed from solution methods for the generalized assignment problem. One method uses a regret minimization approach whilst the other method uses a repair approach on a relaxation of the problem. The heuristics are able to solve moderately large instances of the problem rapidly and effectively. Procedures for deriving an upper bound on the solution of the problem are also described. On larger and harder instances of the problem one heuristic is particularly effective. 相似文献
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A convergence proof is given for the finite-element solutionof the infinite dimensional quadratic programming problem ofminimizing a quadratic functional subject to linear constraints.The proof for the unconstrained problem is briefly reviewed,and then extended to the constrained case. Only the first partof the proof is given, in which necessary conditions for convergenceare derived for the specific problem and its finite-elementapproximation. The final step of proving that any problem doesobey these conditions will depend on the specific problem, butit is shown that if the finite element formulation is pointwiseconvergent and the unconstrained problem is convergent, thenso too will be the constrained problem. 相似文献
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Tchavdar T. Marinov Rossitza S. Marinova 《Journal of Computational and Applied Mathematics》2010,235(2):450-459
A method for solving the inverse problem for coefficient identification in the Euler-Bernoulli equation from over-posed data is presented. The original inverse problem is replaced by a minimization problem. The method is applied to the problem for identifying the coefficient in the case when it is a piece-wise polynomial function. Several examples are elaborated and the numerical results confirm that the solution of the imbedding problem coincides with the direct simulation of the original problem within the second order of approximation. 相似文献
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Huiqing Xie Hua Dai 《高等学校计算数学学报(英文版)》2006,15(2):97-106
1 Introduction Structural dynamics design is to design a structure subject to the dynamic characteristics re- quirement, i.e., determine physical and geometrical parameters such that the structure has the given frequencies and (or) mode shapes. This problem often arises in engineering connected with vibration. Recently, Joseph [1], Li et al. [2,3] converted the structural dynamics design to the following inverse eigenvalue problem. GIEP Let x = (x1, , xm)T , and let A(x) and B(x) be real n… 相似文献
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在很多自由边界问题的研究中,变分不等式是一个有力的工具,它不但可以用来研究解的存在唯一性、正则性等理论问题,而且还提供了有效的数值方法(见[1-3]).对轴对称机轴的弹塑性扭转问题,[4,5]用变分不等式研究了解的存在唯一性和正则性,在此基础上,[6]建议用有限元法求解等价的障碍问题.该法的缺点是,事先要解一个一阶非线性偏微分方程的Cauchy问题以求出障碍函数,并且此Cauchy问题的解一般不唯一.本文的方法是直接将原来的变分不等式问题作有限元离散,再将离散问题化成鞍点问题,然后采用Uzawa型算法求解.这就避免了[6]中方法的上述困难. 相似文献
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J. Haslinger P. Neittaanmki E. Meister 《Mathematical Methods in the Applied Sciences》1986,8(1):157-181
A problem for finding optimal shape for systems governed by the mixed unilateral boundary value problem of Dirichlet-Signorini-type is considered. Conditions for the solvability of the problem are stated when a variational inequality formulation and when a penalty method is used for solving the state problem in question. The asymptotic relation of design problems based on these two formulations is presented. The optimal shape design problem is discretized by means of finite element method. The convergence results for the approximation are proved. The discretized versions are then formulated as a non-linear programming problem. Results of practical computations of the problem in question are reported. 相似文献
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In this paper we research the single machine stochastic JIT scheduling problem subject to the machine breakdowns for preemptive-resume and preemptive-repeat.The objective function of the problem is the sum of squared deviations of the job-expected completion times from the due date.For preemptive-resume,we show that the optimal sequence of the SSDE problem is V-shaped with respect to expected processing times.And a dynamic programming algorithm with the pseudopolynomial time complexity is given.We discuss the difference between the SSDE problem and the ESSD problem and show that the optimal solution of the SSDE problem is a good approximate optimal solution of the ESSD problem,and the optimal solution of the SSDE problem is an optimal solution of the ESSD problem under some conditions.For preemptive-repeat,the stochastic JIT scheduling problem has not been solved since the variances of the completion times cannot be computed.We replace the ESSD problem by the SSDE problem.We show that the optimal sequence of the SSDE problem is V-shaped with respect to the expected occupying times.And a dynamic programming algorithm with the pseudopolynomial time complexity is given.A new thought is advanced for the research of the preemptive-repeat stochastic JIT scheduling problem. 相似文献