Experiencing equivalence but organizing order     

Amir H. Asghari 《Educational Studies in Mathematics》2009,71(3):219-234

The notion of equivalence relation is arguably one of the most fundamental ideas of mathematics. Accordingly, it plays an important role in teaching mathematics at all levels, whether explicitly or implicitly. Our success in introducing this notion for its own sake or as a means to teach other mathematical concepts, however, depends largely on our own conceptions of it. This paper considers various conceptions of equivalence, in history, in mathematics today, and in mathematics education. It reveals critical differences in the notion of equivalence at different points in history and a meaning for equivalence proposed by mathematicians and mathematics educators that is at variance with the ways that learners may think. These differences call into question the most popular view of the subject: that the mathematical notion of equivalence relation is the result of spelling out our experience of equivalence. Moreover, the findings of this study suggest that the standard definition of an equivalence relation is ill-chosen from a pedagogical point of view but well-crafted from a mathematical point of view.  相似文献   

An integrated group decision-making process for supplier selection and order allocation using multi-attribute utility theory and linear programming     

Amir Sanayei  S. Farid Mousavi  Ali Mohaghar 《Journal of The Franklin Institute》2008,345(7):731-747

Supplier selection is a complex multi-criteria problem including both quantitative and qualitative factors. In order to select the best suppliers it is necessary to make a trade-off between these factors, some of which may be in conflict and may also be uncertain. In this problem if suppliers have capacity or other different constraints, two problems will exist: which suppliers are best and how much should be purchased from each selected supplier.In this paper an integrated approach of multi-attribute utility theory (MAUT) and linear programming (LP) is proposed for rating and choosing the best suppliers and defining the optimum order quantities among selected ones in order to maximize total additive utility. A numerical example is proposed to illustrate an application of the proposed method.  相似文献   

Robust simultaneous fault detection and control for a class of nonlinear stochastic switched delay systems under asynchronous switching     

Hossein Shokouhi-Nejad  Amir Rikhtehgar Ghiasi  Mohammad Ali Badamchizadeh 《Journal of The Franklin Institute》2017,354(12):4801-4825

This paper concerns the simultaneous fault detection and control (SFDC) problem for a class of nonlinear stochastic switched systems with time-varying state delay and parameter uncertainties. The switching signal of detector/controller unit (DCU) is assumed to be with switching delay, which results in the asynchronous switching between the subsystems and DCU. By constructing a switching strategy depending on the state and switching delays, new sufficient conditions expressed by a set of linear matrix inequalities (LMIs) is derived to design DCU gains. This problem is formulated as an H_∞ optimization problem and both mean square exponential stability and fault detection of augmented system are considered. A numerical example is finally exploited to verify the effectiveness and potential of the achieved scheme.  相似文献   

Group status and attitude change in desegregated classrooms     

Yehuda Amir  Shlomo Sharan  Miriam Rivner  Rachel Ben-ari  Aharon Bizman 《Int J Intercult Relat》1979,3(2):137-152

One thousand thirty-three ninth-grade students from Western and Middle-Eastern ethnic background in 30 classrooms responded to a questionnaire assessing ethnic attitudes. The questionnaire was administered at the beginning and again at the end of these students' first year in ethnically desegregated classrooms. No marked changes in ethnic attitudes were noted as a function of the students' individual academic or social status in the classroom, but there were noteworthy changes associated with the relative status in the classroom occupied by the students' ethnic groups. Positive attitude change among Western (majority) students occurred when both ethnic groups in the classroom were of equal status, and when the MiddleEastern (minority) group was of superior academic status to the Western group. Positive change among the Middle-Eastern group occurred when it occupied superior status in the classroom.  相似文献   

AFAR: adaptive fuzzy ant-based routing for communication networks     

Seyed Javad Mirabedini  Mohammad Teshnehlab  M. H. Shenasa  Ali Movaghar  Amir Masoud Rahmani 《浙江大学学报(A卷英文版)》2008,9(12):1666-1675

We propose a novel approach called adaptive fuzzy ant-based routing （AFAR）, where a group of intelligent agents （or ants） builds paths between a pair of nodes, exploring the network concurrently and exchanging obtained information to update the routing tables. Routing decisions can be made by the fuzzy logic technique based on local information about the current network state and the knowledge constructed by a previous set of behaviors of other agents. The fuzzy logic technique allows multiple constraints such as path delay and path utilization to be considered in a simple and intuitive way. Simulation tests show that AFAR outperforms OSPF, AntNet and ASR, three of the currently most important state-of-the-art algorithms, in terms of end-to-end delay, packet delivery, and packet drop ratio. AFAR is a promising alternative for routing of data in next generation networks.  相似文献   

Preparation,Characterization and Cytotoxic Effects of Pegylated Nanoliposomal Containing Carboplatin on Ovarian Cancer Cell Lines     

Meysam Ebrahimifar  Amir Nili-Ahmadabadi  Azim Akbarzadeh  Hasan Ebrahimi Shahemabadi  Majid Hasanzadegan  Hemen Moradi-Sardareh  Hassan Madadizadeh  Jalal Rezaee-diyan 《Indian journal of clinical biochemistry : IJCB》2017,32(2):230-234

Carboplatin is a chemotherapeutic agent used against various malignancies such as ovarian carcinoma. The aim of this study is to improve the therapeutic efficacy of carboplatin using pegylated liposomal nanocarriers. Nanoparticles were synthesized using thin film hydration technique and characterized for shape morphology, particle size, zeta potential and drug-release properties. In the next step, A2780S and A2780CP ovarian cancer cell lines were used to determine the efficacy of nanodrug by MTT assay. The particle size and zeta potential of nanodrug were measured 244.3 ± 19.6 nm and ?22.9 ± 1.7 mV, respectively. High encapsulation capacity (78.6 ± 3.7 %) confirmed the efficiency of technique. The cytotoxicity results also showed that nanodrug compared to free drug improve the efficacy of carboplatin against both A2780S (P < 0.01) and A2780CP (P < 0.05) cell lines. In conclusion, the findings of our study suggested pegylated liposomal nanocarriers are proper for carboplatin delivery to ovarian cancer cell lines A2780S and A2780CP.  相似文献