New approaches to positive observer design for discrete-time positive linear systems     

Li-Juan Liu  Hamid Reza Karimi  Xudong Zhao 《Journal of The Franklin Institute》2018,355(10):4336-4350

This paper aims at providing new design approaches for positive observers of discrete-time positive linear systems based on a construction method of linear copositive Lyapunov function for positive systems. First, an efficient positive observer design approach is proposed by using linear programming such that the observer error system is exponentially stable. Furthermore, an interval observer design is proposed for uncertain positive systems. Then, the results are extended to positive time delay systems. In contrast with the previous design approaches, the new design method provides a general observer design with lower computational burden. Finally, three comparison examples are given to show the merit of the new design approach.  相似文献   

Anti-disturbance control based on disturbance observer for nonlinear systems with bounded disturbances     

Huifeng Zhang  Xinjiang Wei  Hamid Reza Karimi  Jian Han 《Journal of The Franklin Institute》2018,355(12):4916-4930

A composite anti-disturbance control problem for a class of nonlinear systems is studied in this paper. There are two types of disturbances in the systems, one is the matched disturbance with bounded variation rate, the other is the unmatched time-varying disturbances. A nonlinear disturbance observer is designed to estimate the matched disturbances, which can be presented separately from the controller design. By integrating DOBC with back-stepping method, a composite DOBC and back-stepping controller is proposed, and the disturbance estimations are introduced into the design of virtual control laws to compensate the unmatched disturbances. In addition, it is proved that all the states in the closed-loop system are uniformly ultimate bounded (UUB). Finally, a numerical example is given to demonstrate the feasibility and effectiveness of the proposed method.  相似文献   

The Role of Students’ Characteristics and Family Background in Iranian Students’ Mathematics Achievement     

Ali?Reza?KiamaneshEmail author 《Prospects》2005,35(2):161-174

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Crack Saturation as a Mechanism of Acclimatization of Panel Paintings to Unstable Environments     

Łukasz Bratasz  Mohammad Reza Vaziri Sereshk 《文物保护研究》2018,63(5):22-27

ABSTRACT

This paper analyzes the process of crack saturation, which is fundamental to understanding why panel paintings have survived remarkably well in the uncontrolled environments of historic houses or places of worship for several centuries. The process of crack saturation was analyzed using finite element modeling. A double layer elastic model with fractured overlying paint layer was subjected to uniaxial tension. The critical separation between cracks was determined and compared with patterns observed in real paintings. In addition, the generation and propagation of delamination were studied to elucidate the effect of their propagation on the saturation distance of cracks, as well as the load carrying ability of the paint layer. Contributing modes of crack propagation and their significance are also discussed. The results demonstrate that shearing fracture mode dominates the process of delamination. The impact of crack saturation on the degree of relative humidity variation that is allowable is also discussed.  相似文献   

Education in Europe and Muslim Demands for Competitive and Moral Education     

Holger Daun  Reza Arjmand 《International Review of Education/Internationale Zeitschrift für Erziehungswissenschaft/Revue internationale l'éducation》2005,36(1):403-426

While European education systems fundamentally rest on a rather monolithic world-view, some of them are explicitly oriented towards Christianity and others are comparatively secular. Apart from this, they differ in the way that they offer opportunities for Muslim minorities to enjoy a modern and competitive as well as religious-moral education. Principally, there are three approaches. The first allows private Muslim schools which are neither subsidized nor controlled or regulated by the state. Other countries require Muslim schools to apply for approval, and such schools are then subsidized and regulated; but they do not have to teach a national curriculum. In a third group of countries, only schools that teach the national curriculum are permitted, and they are subsidized and controlled by the state. In the latter case, because Islamic matters are not taught in these schools, many Muslim parents send their children to non-formal Qur’anic schools in the evening or during weekends. This study examines some typical arrangements in a number of countries.  相似文献   

Construction of some hypergroups from combinatorial structures     

Ali?Reza?AshrafiEmail author  Ahmad?Reza?Eslami-Harandi 《浙江大学学报(A卷英文版)》2003,4(1):76-79

Jajcay's studies(1993; 1994) on the automorphism groups of Cayley maps yielded a new product of groups, which he called, rotary product. Using this product, we define a hyperoperation ⊙ on the groupSym _e(G), the stabilizer of the identitye∈G in the groupSym(G). We prove that (Sym _e (G), ⊙) is a hypergroup and characterize the subhypergroups of this hypergroup. Finally, we show that the set of all subhypergroups ofSym _e (G) constitute a lattice under ordinary join and meet and that the minimal elements of order two of this lattice is a subgroup ofAut (G).  相似文献   

Shared teaching culture in different forms: a comparison of expert and novice teachers’ practices     

Mohammad Reza Sarkar Arani 《Educational Research for Policy and Practice》2017,16(3):235-255

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Construction of some hypergroups from combinatorial structures     

Ali Reza Ashrafi  Ahmad RezaEslami-Harandi 《Journal of Zhejiang University. Science. B》2003,(1)

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Authenticity in teaching and teachers’ emotions: a hermeneutic phenomenological study of the classroom reality     

Akram Ramezanzadeh  Seyyed Mohammad Reza Adel  Gholamreza Zareian 《Teaching in Higher Education》2016,21(7):807-824

This study probed the conceptualization of authenticity in teaching and its link to teachers’ emotional life through critical emotional praxis because emotions are integral to discovering who we really are (McCarthy, E. D. 2009. “Emotional Performances as Dramas of Authenticity.” In Authenticity in Culture, Self, and Society, edited by P. Vannini, and J. P. Williams, 241–255. London: Ashgate). The participants were 20 Iranian university teachers. Data were collected using interviews, field notes, and observation and were analyzed through the lens of hermeneutic phenomenology. The results revealed that authenticity in teaching consisted of themes of being one’s own self, horizon of significance, and contestation resulted from the sense of responsibility, authentic relations, and de-constructive thinking which confirmed the dialogical nature of authenticity. The emotions connected to authenticity in teaching were Transition-Anger, love, and caring indicating that authenticity in teaching was a practice toward socially just teaching.  相似文献   

Some Properties of Matrices with 1, -1 and 0 Entries     

Reza Hashemian 《Journal of The Franklin Institute》1973,295(5):383-394

A class of matrices with 1, -1 and 0 entries, called the H-matrices, is introduced and properties of such matrices are investigated. It is shown that for an H-matrix K the matrix G = KDK^T, where D is a diagonal matrix with nonnegative diagonal entries, has certain properties applicable to topological synthesis of networks. A technique for decomposing a particular symmetrical matrix G, called the Q-matrix, into KDK^T, where K is an H-matrix and D is a diagonal matrix with positive diagonal entries, is also developed.  相似文献