Publication Date: 2023
Ieee Transactions On Fuzzy Systems (10636706)31(10)pp. 3543-3554
This article addresses the problem of fault-tolerant output tracking control for a class of Takagi-Sugeno (T-S) fuzzy systems with unmeasurable premise variables subject to additive and multiplicative actuator faults and external disturbances. In nominal conditions, utilizing a quadratic Lyapunov function and nonparallel distributed compensation technique, the suggested strategy delivers linear-matrix-inequality-based constraints. Simultaneously design of the proportional-integral (PI)-like state feedback controller and fuzzy antiwindup compensator is achieved with the aim of output tracking. In the faulty case, by considering the nominal system as a reference model, a direct adaptive projection-based approach is developed using the T-S fuzzy modeling and control techniques to supply the adaptive fault-tolerant controller components. An enhanced PI state/fault observer with unmeasurable premise variables is introduced only to provide the estimation of states to be used in the proposed controller. The overall closed-loop system ensures the uniformly ultimately bounded solutions for error dynamics. Two examples, subsuming an inverted pendulum and a chaotic power system, have been used to present the merits and efficiency of the suggested approach persuasively. © 1993-2012 IEEE.
Publication Date: 2022
Ieee Transactions On Fuzzy Systems (10636706)30(6)pp. 1914-1928
Active fault-tolerant control strategy aimed at tracking is studied for a class of discrete-time Takagi-Sugeno (T-S) fuzzy systems in the presence of input constraint and additive fault. In the fault-free case, the state space of the system is partitioned based on the presence or absence of inputs. Using the parallel distributed compensation technique, input-to-state stability is proved for the error dynamics. For input constraint satisfaction, a model predictive control based reference-management unit is proposed in the form of an online optimization module that solves a quadratic programming problem. In the faulty case, the fault-free system is used as a reference model that satisfies the input constraint. Then, the concept of virtual actuator is used to make the behavior of the faulty system similar to the behavior of the fault-free system by controlling the performance degradation. In this article, a full-order observer can be used for fault estimation. In order to keep the control input of the faulty system within the admissible range defined for the fault-free system, a constraint-change scenario is considered. After detecting the fault, the constraint on the input of the fault-free system is changed in a way to keep the control input of the faulty system in the specified range. All design criteria are formulated as a linear matrix inequality problem. In order to evaluate the proposed control approach, simulations are performed on two systems: a 3-DoF helicopter and a 2-D overhead crane. © 1993-2012 IEEE.
Publication Date: 2021
Journal of the Franklin Institute (00160032)358(18)pp. 9510-9541
A new control design approach is proposed for a class of nonlinear systems expressed by Takagi–Sugeno (T-S) fuzzy model, considering several objectives including robustness against input time-varying delay, input constraint satisfaction, and reference tracking. The proposed controller is designed on the basis of an augmented model, Lyapunov–Krasovskii functional, linear matrix inequality (LMI) tools, and parallel distributed compensation (PDC) approach. Proof of the input-to-state stability (ISS) criterion is provided for the error dynamics. Input constraint satisfaction is performed using a reference-management algorithm based on the linearized closed-loop system from the reference input to the constrained variables. In order to illustrate the effectiveness of the proposed control approach, simulations are performed on three practical examples, including a flexible-joint robot and a continuous stirred tank reactor (CSTR). © 2021 The Franklin Institute
In this paper, a supervisory active fault tolerant control (SAFTC) scheme is presented for linear systems with constraints. The SAFTC framework is composed of a fault diagnosis module, a reconfigurable controller and a pre-designed command governor. In the presence actuator faults, constraints are guaranteed by governing the setpoint to the nearest admissible value. The command governor is adopted in such a way that no recalculation and reconfiguration is needed even in the presence of actuator fault occurrence and reconfiguration of the main controller. The input redundancy assumption, needed to recover the closed-loop tracking performance of system with faulty constrained actuator, is relaxed. A simulation study on VTOL aircraft is performed to evaluate the effectiveness of the proposed method. © 2020 EUCA.
Publication Date: 2013
Middle East Journal of Scientific Research (discontinued) (19998147)13(3)pp. 280-287
Tourism has many social, cultural and environmental effects which affects domestic people, so has produced many concerns. It is anticipated that tourist will travel too much in the next 20 years because of tourism's economical and social effects. Tourism play an important role in world economy and it is expected that it get more importance in the next years. Tourism affects occupation rate, payment balance and economical stability of many countries. This industry is an application one, so that is a potential to improve occupation situation, especially for low-skilled jobs. In Tajikistan, unemployment rate is focused in this area. In addition, tourism jobs are more dispersed than the other economical divisions, so they are parallel to decentralization policy of Tajikistan. According to the experts, one of the reasons for unsuccessfulness of Tajikistan in tourism is low notice to modern tourism market. A sample of 80 active persons in tourism industry in Tajikistan for four years (2007-2010) was selected. Binomial test, Freedman variance analysis test and correlation test were used to test assumptions. The results show that Suitable distribution channels strategies affect attraction of foreign tourists. © IDOSI Publications, 2013.
Publication Date: 2013
Middle East Journal of Scientific Research (discontinued) (19998147)18(7)pp. 1042-1047
In knowledge-based economy, intellectual capital is used to create and increase of organizational value and the position of any organization depends on managing these valuable and scarce resources. According to resource-based perspective of company, intellectual capitals are strategic resources that enable companies to create competitive advantage and better financial performance. So, the managers should measure intellectual capital as an important criterion for increasing business performance of organizations, determining the real value f intellectual capitals and even improving their control. In this paper we attempt to investigate the relationship between intellectual capital and increase of organizational value. In this research, firstly intellectual capital value of companies accepted in Tehran stock exchange in a 7 years period between 2006-2012 was calculated using VAIC model. Then, the relationship between intellectual capital and the elements of organizational value of companies was evaluated. In this study, the statistical methods used for data analysis are multiple regression and correlation coefficients. The selected sample includes 84 companies for a period of 7 years and company size, type of industry and investment intensity ratio have been considered as control variables. The findings show significant and positive relationship between intellectual capital and increase of organizational value and the positive effect of control variables on the relationship between intellectual capital and increase of organizational value. © IDOSI Publications, 2013.
Publication Date: 2013
Life Science Journal (discontinued) (10978135)10(SUPPL. 5)pp. 611-615
Accounting plays an important role in economical system. Precise decision-making is inevitable by individuals, companies, government, etc for proper distribution and efficiency of financial resources. To make such decisions, decision-makers must have reliable information. In fact, the goal of accounting is to help these decisionmakers. On the other hand, investment is essential in growth process and economical development of country. In this study, a number of accounting variables such as accounting profit, degree of operating leverage (DOL), degree of financial leverage (DFL) and degree of total leverage (DTL) were selected as symbols of accounting information. Then their relation with systematic risk of those companies accepted in Tehran Stock Exchange was investigated. In this research, a sample including 98 companies accepted in Tehran Stock Exchange were selected during a 6 years period (2005-2011). Regarding to nature and method, this is correlation research,In order to test the assumptions, linear regression was used and in order to test correlation of variables, p-value test was used. The results showed that there is a direct relation between accounting profit and DFL with systematic risk by 90% confident level. Also, there is not a significant relation between DOL and DTL with systematic risk.
Zare, I.,
Taheri, M.R.,
Nekounam, J.,
Fardi, K.,
Samaei baghbadorani, M.R. Publication Date: 2013
Life Science Journal (discontinued) (10978135)10(SUPPL. 5)pp. 616-619
Precise decision-making is inevitable by individuals, companies, government, etc for proper distribution and efficiency of financial resources. To make such decisions, decision-makers must have reliable information. In fact, the goal of accounting is to help these decision-makers. On the other hand, investment is essential in growth process and economical development of country. In this study, a number of accounting variables such as accounting profit, degree of financial leverage were selected as symbols of accounting information. Then their relation with systematic risk of those companies accepted in Tehran Stock Exchange was investigated. In this research, a sample including 98 companies accepted in Tehran Stock Exchange were selected during a 6 years period (2006-2012). Regarding to nature and method, this is correlation research,In order to test the assumptions, linear regression was used and in order to test correlation of variables, p-value test was used. The results showed that there is a direct relation between degree of financial leverage with systematic risk by 90% confident level.
Zare, I.,
Ghandehari, F.,
Nekounam, J.,
Malak hossini, H.R.,
Fardi, K. Publication Date: 2013
Life Science Journal (discontinued) (10978135)10(SUPPL. 5)pp. 620-626
Analyzing expected rate of return according to the assets and estimations of value at enormously help the company in optimum use of financial and physical resources. if an assortment of investments is organized in such a way to be the best possible set, investors, by minimizing the attendant risks, can approach the optimum rate of return that is close to the market value. In this study, Capital Assets Pricing Model (CAPM), Fama and French three factor model and Value-at-Risk (VaR) model and their forecasting capabilities are thoroughly analyzed. Investors are aptly informed to make a conscious decision in extracting the best portfolio set. The study sample consisted of 118 companies listed in Tehran Stock Exchange, on a monthly basis during 2003-2010 and was selected. This study is based on assumptions that each model is efficient enough to forecast the arrangement of optimum portfolios. The regressiontest of out hypotheses indicates that CAPM model and Fama and French model are competent enough to forecast the structure of portfolios but VaR model's estimations must be cautiously applied. In this essay we analyze the power of estimation of CAPM, F&F and VaR models in determining the optimum portfolio to be helpful for investors.
Zare, I.,
Nekounam, J.,
Pirzad, A.,
Sedaghatjoo, F.,
Mosavimotahar, S. Publication Date: 2013
Life Science Journal (discontinued) (10978135)10(SUPPL.3)pp. 589-592
Accounting is an information system and managers should obtain high-quality and suitable information from formal and informal channels for decision-making. Accounting information system (AIS) is a part of this system that registers and summarized financial events. Then it reports information as accounting information to support managers in decision-making the question is that whether AIS affects relevance of accounting information in financial statements? To do this research, a sample of 105 confidant auditors from Tehran Stock Exchange and professors of Islamic Azad University, region 5, was selected by Simple Random Sampling (SRS) method as questionnaires. Inferential statistical method, Clemogrov-Smironov test, and t-student test were used. It was found that accounting information systems highly affect on relevance of financial statement.
Zare, I.,
Nekounam, J.,
Baghbadorani, M.R.S.,
Hossini, H.R.M. Publication Date: 2013
Life Science Journal (discontinued) (10978135)10(SUPPL. 5)pp. 511-514
Software packages as computer AIS, and regarding to the continuous changes and rapid developments of economical units, provision of relevant, reliable, financial information is necessary. To investigate this, the question is that whether softwares of accounting affects on relevance and reliability of accounting information in financial statements? To do this research, a sample of 105 confidant auditors from Tehran Stock Exchange and professors of Islamic Azad University, region 5, was selected by Simple Random Sampling (SRS) method as questionnaires. Inferential statistical method, Clemogrov-Smironov test, and t-student test were used. It was found that accounting information systems and softwares highly affect on relevance of financial statement, but they lowly affect on reliability of them.
Zamani, N.B.,
Zare, I.,
Nekounam, J.,
Farahani, M.S.,
Mohammadi, S.M. Publication Date: 2013
Life Science Journal (discontinued) (10978135)10(SUPPL. 5)pp. 515-521
Devolution of governmental companies to private sector is one of the most important problems in Iranian economy. This research studies the effects of privatization of governmental companies in Iran in Tehran Stock Exchange. Stock return was analyzed by an analytical-experimental method. Data was gathered through financial documents for stocks return of companies in the previous periods, private companies, and governmental companies for 1997-2005. Then non-parametric tests were applied on the data by SPSS software. It was found by statistical analyses that there is not a significant difference between stocks return of private and governmental companies. There is a significant difference between stocks return of private companies before and after privatization. There is a significant difference between stocks return of private companies in the five sub-periods. The most increment was in the first three years and the most decrement was in the fourth year after privatization.
Zare, I.,
Aghjehkandi, M.O.,
Aghjehkandi, G.O. Publication Date: 2012
Middle East Journal of Scientific Research (discontinued) (19998147)11(1)pp. 32-38
Reliability and relevance are the most important qualitative characteristic of accounting information. Goodwill and intangible assets are among reported items in financial statements under title of fixed assets, which they have different nature from other assets or other items of financial statements. In this research, we study reliability and relevance of reported values of goodwill and intangible assets in financial statements. If accounting items have two characteristic of relevance and reliability, they should be used in decision-making and must affect market value. To do this research, a sample including 88 member companies in Tehran Stock Exchange for 5 years (2005-2010) was selected and studied. Also, to study reliability and relevance of goodwill and intangible assets of reported items in financial statements, correlation of these two factors with market value of companies was studied by regression. After fulfillment of this research and confirmation of research Hypothesis, it was found that there is a positive and significant relation between reported values of intangible assets and goodwill as independent variable and qualitative characteristic of information as dependent variable. © IDOSI Publications, 2012.
Publication Date: 2011
European Journal of Scientific Research (discontinued) (1450202X)66(4)pp. 643-652
The purpose of this study is to review the relationship between changes in dividends, earnings per share and changes in earnings per share with changes in future earnings. The sample included 100 active companies in Tehran Stock Exchange during the financial years 2005 to 2010. To clarify the relationship, 12 hypotheses have been established and to examine them, the tests of correlation and regression were used. Hypothesis were established based on correlations relation among changes in dividends, earnings per share and changes in earnings per share with changes in future earnings for companies able to predict cash flow ,different market value to book value ratio and equity rerun. The results show strong relationship (correlations) among changes in dividends, earning per share and changes in earnings per share for companies with higher market to book value ratio , higher equity return and lower cash flow predictability. Among main variables, earnings per share and among virtual variables, market value to book value had better effect on changes in future earnings. The correlation coefficient (R) of 0.490 for three main variables has changed to 0.621 for both main and virtual variables. © EuroJournals Publishing, Inc. 2011.
Talebnia, G.,
Zare, I.,
Abadi, F.A.N.,
Fathi, M. Publication Date: 2011
International Research Journal of Finance and Economics (discontinued) (14502887)80pp. 94-104
If investment is just demarcated to specific assets, investment process may come cross considerable risk of losing the capital; but if an assortment of investments is organized in such a way to be the best possible set, investors, by minimizing the attendant risks, can approach the optimum rate of return that is close to the market value. In this study, Capital Assets Pricing Model (CAPM), Fama and French three factor model and Value-at-Risk (VaR) model and their forecasting capabilities are thoroughly analyzed. Investors are aptly informed to make a conscious decision in extracting the best portfolio set. The study sample consisted of 109 companies listed in Tehran Stock Exchange, on a monthly basis (96 months) during 2001-2008 and was selected. This study is based on assumptions that each model is efficient enough to forecast the arrangement of optimum portfolios. The regression test of out hypotheses indicates that CAPM model and Fama and French model are competent enough to forecast the structure of portfolios but VaR model's estimations must be cautiously applied. © EuroJournals Publishing, Inc. 2011.
Publication Date: 2011
European Journal of Economics, Finance and Administrative Sciences (discontinued) (14502275)(43)pp. 44-49
Capital market investors with a better understanding of the effects of earnings per share and earnings per share of changes in future profits of various industries to invest instocks that them to obtain maximum efficiency. This study factors of influencing in changes of firms future earnings for predicting future earnings changes include earningsper share is discussed. Statistical community in this study consists of all companies listed securities Tehran. To perform this study, the sample consisted of 110 companieslisted in Tehran Stock Exchange during the duration (2004-2010) was evaluated and selected. This study design a model using multiple regression and error level of 5% waspaid to test these assumptions. Research findings indicate that between " earnings per share " and future earnings changes and positive significant relationship exists. Theresults of the test sub-hypothesis states that research for companies that market to book value of equity yields higher and higher change of dividends factor have therelationship between future earnings changes is stronger. © EuroJournals, Inc. 2011.
Publication Date: 2011
International Research Journal of Finance and Economics (discontinued) (14502887)77pp. 95-101
Provide information essential to a correct and informed decisions on different groups of investors are particularly,This information is important for investors and others should be able to provide adequate disclosure and to be useful in deciding them.The purpose of this study is that Companies in the Tehran Stock Exchange on admission rates and information disclosure in the financial statements are the effects? The study sample consisted of 72 members participated in the Tehran Stock Exchange's 10-year period (1997 -2007) were selected. It uses normality test Kolomugorof - Simonov to review level of information disclosure and it uses t-test for comparison rate of disclosure before and after company acceptance in Tehran Stock Exchange and it uses p- test to reject or accept assumption. With regard to above cases, the following results obtain: Presentation and disclosure of information between companies in the financial statements of the companies in the stock and then there is a significant difference so member companies in the stock market has considerable effect on the amount of information in financial statements. © EuroJournals Publishing, Inc. 2011.
