共查询到20条相似文献,搜索用时 15 毫秒
1.
对国内有关轴拉试验结果进行了分析,说明高强混凝土轴心受拉强度与普通混凝土轴心受拉强度是有差异的.并给出了计算模型. 相似文献
2.
The fleet assignment model assigns a fleet of aircraft types to the scheduled flight legs in an airline timetable published six to twelve weeks prior to the departure of the aircraft. The objective is to maximize profit. While costs associated with assigning a particular fleet type to a leg are easy to estimate, the revenues are based upon demand, which is realized close to departure. The uncertainty in demand makes it challenging to assign the right type of aircraft to each flight leg based on forecasts taken six to twelve weeks prior to departure. Therefore, in this paper, a two-stage stochastic programming framework has been developed to model the uncertainty in demand, along with the Boeing concept of demand driven dispatch to reallocate aircraft closer to the departure of the aircraft. Traditionally, two-stage stochastic programming problems are solved using the L-shaped method. Due to the slow convergence of the L-shaped method, a novel multivariate adaptive regression splines cutting plane method has been developed. The results obtained from our approach are compared to that of the L-shaped method, and the value of demand-driven dispatch is estimated. 相似文献
3.
通过从一个导数值等式的证明谈起,探讨教师在课堂教学中如何根据教学内容创设能激起学生新异感的问题情景,启发和引导学生发散思考,类比、联想、猜想,探索和发现新问题并给出解答.使学生思维不断攀升,丰富教学内容,激发学生兴趣,培养学生科学思维方法和创新能力. 相似文献
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5.
Irving H. Anellis 《Logica Universalis》2009,3(2):153-218
My purpose here is purely historical. It is not an attempt to resolve the question as to whether Russell did or did not countenance
nonclassical logics, and if so, which nonclassical logics, and still less to demonstrate whether he himself contributed, in
any manner, to the development of nonclassical logic. Rather, I want merely to explore and insofar as possible document, whether,
and to what extent, if any, Russell interacted with the various, either the various candidates or their, ideas that Dejnožka
and others have proposed as potentially influential in Russell’s intellectual reactions to nonclassical logic or to the philosophical
concepts that might contribute to his reactions to nonclassical logics. 相似文献
6.
J.A.S. Williams S. Wongweragiat X. Qu J.B. McGlinch W. Bonawi-tan J.K. Choi J. Schiff 《European Journal of Operational Research》2007
The automotive recycling infrastructure successfully recovers 75% of the material weight in end-of-life vehicles primarily through ferrous metal separation. However, this industry faces significant challenges as automotive manufacturers increase the use of nonferrous and nonmetallic materials. As the nonferrous content in end-of-life vehicles rises, automotive shredders need to evaluate to what extent to separate nonferrous metals. We propose a recycling planning model for automotive shredders to make short-term tactical decisions regarding to what extent to process and to reprocess materials through multiple passes. In addition, the mixed integer programming model determines whether to combine materials for shipment. In a case study for automotive shredding decisions for the current composition and more polymer-intensive end-of-life vehicles, we use our model to show the sensitivity of the decision to reprocess light nonferrous metal to low and high metal prices. Contrary to observations in practice to mix light and heavy nonferrous metals for shipment, we show multiple scenarios where the model chooses to reprocess and ship separated light and heavy nonferrous metals. 相似文献
7.
刘林 《数学的实践与认识》2008,38(6):151-157
考虑一类在网络上点到路的距离意义下的最优干线选址问题,这是一类新型的选址问题.首先证明所讨论的两个问题是NP-hard,然后讨论树的情况,给出了当G是树时求解问题的算法,该算法的复杂性是O(n2).并对一些特殊网络的情况进行了讨论. 相似文献
8.
A. S. C. Ehrenberg 《The Journal of the Operational Research Society》1968,19(4):421-432
Repeat-buying habits for relatively frequently bought textile garments have been found to follow systematic patterns. Many of these patterns belong to the NBD/LSD model of repeat-buying which is already known to hold for non-durable household goods. The main exceptions relate to relatively long repurchasing cycles, to an apparent tendency for some garments to be bought two at a time, and to certain measurement biases in the data. 相似文献
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10.
《Discrete Mathematics》2022,345(10):112989
A mixed graph is cospectral to its converse, with respect to the usual adjacency matrices. Hence, it is easy to see that a mixed graph whose eigenvalues occur uniquely, up to isomorphism, must be isomorphic to its converse. It is therefore natural to ask whether or not this is a common phenomenon. This note contains the theoretical evidence to confirm that the fraction of self-converse mixed graphs tends to zero. 相似文献
11.
Alison S. Marzocchi 《International Journal of Mathematical Education in Science & Technology》2016,47(5):814-821
This article suggests that logic puzzles, such as the well-known Tower of Hanoi puzzle, can be used to introduce computer science concepts to mathematics students of all ages. Mathematics teachers introduce their students to computer science concepts that are enacted spontaneously and subconsciously throughout the solution to the Tower of Hanoi puzzle. These concepts include, but are not limited to, conditionals, iteration, and recursion. Lessons, such as the one proposed in this article, are easily implementable in mathematics classrooms and extracurricular programmes as they are good candidates for ‘drop in’ lessons that do not need to fit into any particular place in the typical curriculum sequence. As an example for readers, the author describes how she used the puzzle in her own Number Sense and Logic course during the federally funded Upward Bound Math/Science summer programme for college-intending low-income high school students. The article explains each computer science term with real-life and mathematical examples, applies each term to the Tower of Hanoi puzzle solution, and describes how students connected the terms to their own solutions of the puzzle. It is timely and important to expose mathematics students to computer science concepts. Given the rate at which technology is currently advancing, and our increased dependence on technology in our daily lives, it has become more important than ever for children to be exposed to computer science. Yet, despite the importance of exposing today's children to computer science, many children are not given adequate opportunity to learn computer science in schools. In the United States, for example, most students finish high school without ever taking a computing course. Mathematics lessons, such as the one described in this article, can help to make computer science more accessible to students who may have otherwise had little opportunity to be introduced to these increasingly important concepts. 相似文献
12.
Advanced transportation sensors use a wireless medium to communicate and use data fusion techniques to provide complete information. Large-scale use of intelligent transportation sensors can lead to data bottlenecks in an ad-hoc wireless sensor network, which needs to be reliable and should provide a framework to sensors that constantly join and leave the network. A possible solution is to use public transportation vehicles as data fusion nodes or cluster heads. This paper presents a mathematical programming approach to use public transportation vehicles as cluster heads. The mathematical programming solution seeks to maximize benefit achieved by covering both mobile and stationary sensors, while considering cost/penalty associated with changing cluster head locations. A simulation is developed to capture realistic considerations of a transportation network. This simulation is used to validate the solution provided by the mathematical model. 相似文献
13.
Z. Naniewicz 《Journal of Optimization Theory and Applications》1994,83(1):97-112
The hemivariational inequality approach is applied to establish the existence of solutions to a large class of nonconvex constrained problems in a reflexive Banach space. The admissible sets are supposed to be star-shaped with respect to a ball. Due to a discontinuity property of the Clarke directional differential related to the corresponding distance functions, the proposed method permits one to attain the solution without passing to zero with the penalization parameter. Some applications to nonconvex constrained variational problems illustrate the theory. 相似文献
14.
H-V Seow 《The Journal of the Operational Research Society》2010,61(3):443-454
The advent of Internet broking pages allows customers to ‘apply’ to a number of different companies at one time, leading to multiple offers made to a customer. The saturated condition of the personal financial products has led to falling ‘take’ rates. Financial institutions are trying to increase the ‘take’ rates of their personal financial products. Applicants for credit will have to provide information for risk assessment, which can be used to assess the probability of a customer accepting an offer. Interactive channels such as the Internet and telephone allow questions that are asked to depend on previous answers. The questions selected need to provide information to assess the probability of acceptance of a particular variant of financial product. In this paper, we investigate a model to predict the best offer to extend next to a customer based on the response for the questions, as well as the question selection itself. 相似文献
15.
A new asymptotic expansion algorithm related to the Chapman-Enskog expansion in kinetic theory is applied to systems of linear evolution equations. The uniform convergence of the asymptotic solution to the exact one is shown. The algorithm is applied to the linearized Carleman model of the Boltzmann equation, to the neutron transport equation, and to the Fokker-Planck equation. 相似文献
16.
Elmar Ahle 《Mathematical and Computer Modelling of Dynamical Systems: Methods, Tools and Applications in Engineering and Related Sciences》2013,19(4):319-339
In this study, the application of a meta-modelling technique to structure complex environments is demonstrated with two examples. A special situation-operator model developed to model the human-machine-interaction is applied to automated supervision within the HMI context and to realize flexible and situated interaction of autonomous systems. A concept to automated monitoring of human operators is introduced to illustrate the structuring of complex environments as the first example. In the second example, this modelling technique is applied to a mobile robot to autonomously build and update a mental model of the interaction with the environment as an example of a cognitive technical system. 相似文献
17.
Gustavo Martínez-Sierra Marisa Miranda-Tirado 《International Journal of Mathematical Education in Science & Technology》2013,44(5):700-720
This paper reports a qualitative research that identifies Mexican high school students’ social representations of mathematics. For this purpose, the social representations of ‘mathematics’, ‘learning mathematics’ and ‘teaching mathematics’ were identified in a group of 50 students. Focus group interviews were carried out in order to obtain the data. The constant comparative style was the strategy used for the data analysis because it allowed the categories to emerge from the data. The students’ social representations are: (A) Mathematics is…(1) important for daily life, (2) important for careers and for life, (3) important because it is in everything that surrounds us, (4) a way to solve problems of daily life, (5) calculations and operations with numbers, (6) complex and difficult, (7) exact and (6) a subject that develops thinking skills; (B) To learn mathematics is…(1) to possess knowledge to solve problems, (2) to be able to solve everyday problems, (3) to be able to make calculations and operations, and (4) to think logically to be able to solve problems; and (C) To teach mathematics is…(1) to transmit knowledge, (2) to know to share it, (3) to transmit the reasoning ability, and (4) to show how to solve problems. 相似文献
18.
本文论述了高校科协在新形势下,如何落实“科学技术是第一生产力”的指导思想,在高校科技与经济发展的实践中,充分发挥广大科技工作者的作用,围绕着党的中心工作开展科学技术活动,为发展科技事业,推动科技进步,加强精神文明建设,做出应有的贡献。 相似文献
19.
Fernando O. Souza Reinaldo M. Palhares Petr Ya. Ekel 《Chaos, solitons, and fractals》2009,39(1):240-247
This paper presents a new linear matrix inequality (LMI) based approach to the stability analysis of artificial neural networks (ANN) subject to time-delay and polytope-bounded uncertainties in the parameters. The main objective is to propose a less conservative condition to the stability analysis using the Gu’s discretized Lyapunov–Krasovskii functional theory and an alternative strategy to introduce slack matrices. Two computer simulations examples are performed to support the theoretical predictions. Particularly, in the first example, the Hopf bifurcation theory is used to verify the stability of the system when the origin falls into instability. The second example is presented to illustrate how the proposed approach can provide better stability performance when compared to other ones in the literature. 相似文献
20.
卫贵武 《数学的实践与认识》2007,37(19):94-98
针对属性权重信息不完全且属性值确定的多属性决策问题,提出了一种灰色关联分析的决策方法.该方法依据一般的灰色关联分析方法的基本思路,给出了解决属性权重信息不完全的多属性决策问题的计算步骤,其核心是通过构建并求解一个单目标最优化模型,得到每个方案与正、负理想方案的关联度,进而计算出每个方案与正理想方案的相对关联度,即可得到所有方案的排序结果.最后给出了一个数值例子,结果表明方法简单,有效和易于计算. 相似文献