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杜有威 《天津成人高等学校联合学报》2003,5(2):107-110
解决线性规划问题古典的拉氏乘子法和单纯形法，是运筹学的内容。通过相关表格的描述，表达求解线性规划高斯消元法(基本解)与单纯形法(可行解)的关系，及迭代次数多少的比较；得出单纯形(凸多面体)是按一定(趋近最优值)方向替换基坐标轴，大大减少了求解联立方程组的个数。 相似文献
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单纯形法和对偶单纯形法是求解线性规划问题最基本的方法。但它们分别要求有一个可行基和对偶可行基 ,这往往不易得到。若添加人工变量 ,则不仅增加了计算量 ,而且由于变量繁多 ,给上机作业带来不便。下面我们将单纯形法和对偶单纯形法综合使用 ,不需添加人工变量 ,即可求出线性规划问题的解。基本思路是 :先用对偶单纯形法求出线性规划问题的一个基本可行解 ,然后再用单纯形法求出最优解。对问题的分析如下 :设标准线性规划问题是 :Ｍａｘｚ =Ｃｘ ,约束条件为Ａｘ =ｂ ,ｘ≥ 0 (1)其中Ａ是ｍ×ｎ阶满秩阵 ,ｍ≤ｎ令Ｂ是此问题的一个基 ,基… 相似文献
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单纯形法解线性规划问题的算法探究 总被引：1，自引：0，他引：1
线性规划就是用数学为工具,来研究一定限制条件下,如何实现某一线性目标最优化。而单纯形法是解决线性规划问题的主导方法。本文以线性规划模型常见的实例为依据,通过引入普通单纯形法,依次迭代并判断,逐步逼近,最后得到最优解。然后,介绍了求解一般线性规划问题的大M单纯形法（简称大M法）和两阶段法,并分别举一例说明求解的基本思路：通过添加人工变量使得标准化后的系数矩阵一定含有单位矩阵,从而得到一组基变量和初始基本可行解。由于人工变量是人为添加的,为了不改变原问题,在目标函数中消去人工变量,并将人工变量由初始的基变量化成非基变量,使之取值为零,然后用普通单纯形法求解。 相似文献
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《扬州职业大学学报》1996,(1)
本文就含有“=”约束条件的线性规划问题给出了一种综合算法.首先利用等号对原问题化简,再用一般单纯形法求解.若求出的最优解代入原问题不可行,再将删去的约束条件插入最后单纯形表中,利用对偶单纯形法求解. 相似文献
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《洛阳师范学院学报》2016,(2):22-25
本文从几何意义上探讨基本可行解的特征.实践证明,这项研究不仅加深了对基本可行解的认识和理解,而且为进一步学习和掌握单纯形法求解线性规划提供了帮助. 相似文献
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单纯形法是解决线性规划问题的重要方法之一,表格直接求解法则是单纯形法中最直接有效的方法。本文主要研究了线性规划中的单纯形算法的表格直接求解法,并且通过所给算例验证了表格求解法的可行性与有效性。 相似文献
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Benjamin Blaisdell 《Teaching Education》2018,29(4):330-342
ABSTRACTThe one-drop rule refers to the process of being racialized Black when someone contains any amount of Black ancestry, i.e. one drop of Black blood. In this article, I use what I call ‘the new one-drop rule’ to explain how even the smallest presence of white discourse can disrupt racial equity work in schools. Based on a critical race study in a racially desegregated elementary school, I illustrate how one drop of white discourse from even one less racially literate white teacher can cause usually more racially literate white teachers to support white supremacy. I also share how collaborative research utilizing critical race theory (CRT) can help schools build greater racial literacy and resist white discourse. I argue that critical research on race with in-service teachers should not forefront the consciousness-raising of resistant white teachers but rather center the wants, needs, and racial knowledge of racially literate teachers and especially teachers of color. 相似文献
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This study investigated mathematics teachers' professional knowledge among elementary school teachers exposed to a professional training program that either supported self-regulated learning (SRL) or offered no SRL support (no-SRL). The SRL support was based on the IMPROVE metacognitive self-questioning method that directs students' attention to understanding when, why, and how to solve problems (Kramarski and Mevarech, Am Educ Res J 40:281–310, 2003). Sixty-four Israeli elementary teachers participated in a month-long professional development program to enhance mathematical and pedagogical knowledge. The course was part of a 3-year professional development program sponsored by the Israeli Ministry of Education. This mixed-method study included quantitative assessments of teachers' professional knowledge in mathematical problem solving for an authentic task based on Program for International Student Assessment's framework (Program for International Student Assessment, 2003) and in lesson planning, as well as qualitative interviews and videotaped observations of two teachers. Results indicated that teachers in the SRL program outperformed those in the no-SRL program on various problem solving skills (e.g., reflection and conceptual mathematical explanations) and lesson planning (e.g., task demands and teaching approach). Videotaped observations of actual teaching indicated that the SRL-trained teacher demonstrated more teaching practices that aimed to promote students' understanding and better supported students' regulation of their own learning, compared to the no-SRL-trained teacher. We discuss educational and practical implications. 相似文献
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教育改革必须突破的难点:教育改革主体的自我变革 总被引：1，自引：0，他引：1
我国教育改革已进入攻坚阶段,但其突破的难点是什么,各界还未形成共识。从教育改革的主体及其关系的角度审视,教育改革实际存在着"我改你"、"你改我"、"我改我(自己改自己)"三种形式。"我改你"的教育改革是改革主体乐意的改革,"你改我"的教育改革是改革主体转化为改革对象后惧怕的改革,而"我改我"的改革则是改革主体最不愿意的改革,因而也是教育改革中最艰难的改革。当前需要成立具有一定超脱性的教育改革指导或领导小组,使之成为唤醒教育改革主体进行自我变革的外力,进而促进教育改革主体的自我变革。 相似文献
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Relational reasoning, a higher-order cognitive ability that identifies meaningful patterns among information streams, has been suggested to underlie STEM development. This study attempted to explore the potentially unique contributions of four forms of relational reasoning (i.e., analogy, anomaly, antinomy, and antithesis) to mathematical problem solving. Two separate samples, fifth graders (n = 254) and ninth graders (n = 198), were assessed on their mathematical problem solving ability and the different forms of relational reasoning ability. Linear regression analysis was conducted, with participants’ age, working memory, and spatial skills as covariates. The results showed that analogical and antithetical reasoning abilities uniquely predicted mathematical problem solving. This pattern demonstrated developmental stability across a four-year time frame. The findings clarify the unique significance of individual forms of relational reasoning to mathematical problem solving and call for a shift of research direction to reasoning abilities when exploring dissimilarity-based relations (opposites in particular). 相似文献
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On the nature of problems 总被引：2，自引：0，他引：2
Raffaělla Borasi 《Educational Studies in Mathematics》1986,17(2):125-141
This paper is an attempt at clarifying the concept of problem, and originates from a concern for improving the teaching of problem solving.The following categories are identified and employed in the analysis of several examples of problems and related notions: (a) the formulation of a problem, i.e. the definition of the task to be performed, (b) the context in which the problem is embedded, (c) the set of suitable solutions, (d) the methods of approach that could be employed in solving the problem.Commonalities as well as contrasts among specific examples are used to identify important elements of problems. The study suggests a possible classification of types of problems of educational interest, and draws some implications for the choice and use of problems in classroom instruction. 相似文献
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Roza Leikin 《Journal of Mathematics Teacher Education》2003,6(4):297-329
The aim of the study presented in this paper was to explore factors that influence teachers' problem-solving preferences in the process of (a) solving a problem, (b) explaining it to a peer, (c) liking it, and (d) teaching it. About 170 mathematics teachers took part in the different stages of the study. A special mathematical activity was designed to examine factors that influence teachers' problem-solving preferences and to develop teachers' preferences concerning whether to use symmetry when solving the problems. It was implemented and explored in an in-service program for professional development of high-school mathematics teachers. As a result, three interrelated factors that influence teachers' problem-solving preferences were identified: (i) Two patterns in teachers' problem-solving behavior, i.e., teachers' tendency to apply a stereotypical solution to a problem and teachers' tendency to act according to problem-solving beliefs, (ii) the way in which teachers characterize a problem-solving strategy, (iii) teachers' familiarity with a particular problem-solving strategy and a mathematical topic to which the problem belongs. Findings were related to teachers' developing thinking in solving problems and using them with their students. The activity examined in this paper may serve as a model for professional development of mathematic teachers and be useful for different professional development programs. 相似文献
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Sveriges Dövas Riksförbund (SDR), i.e. Swedish National Association of the Deaf, in co-operation with the Department of Psychology, University of Stockholm, carried out and evaluated a research program concerning supportive interventions in group with therapeutic direction for hearing parents of deaf and hearing impaired children. The program which was based on a pilot study (Backenroth, 1976) demonstrating an actual need for a psychological supportive program focusing on the parents, was carried out between 1976 and 1979 in different parts of Sweden: Boden, Gävle, Göteborg, Lund, Malmö and Stockholm. Altogether 76 parents constituting eleven groups participated in the program which was financed by Delegationen för Social Forskning, i.e. the Delegation for Social Research. 相似文献
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江平 《教学研究(河北)》2002,25(4):354-356
人以鱼不若授人以“渔”。二十年来各种师范院校及大众书法临习教材与教法一味注重对范字形态的分析,片面强调书写应达到的结果,而对能否达到这一结果的最关键－－视觉注意的却未曾涉及。本针对此迫切问题,主要从师范院校实际出发,立足于侧重笔画组合,从读贴,书写两环节论述如何引导学生正确支配视觉注意。 相似文献
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