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61.
62.
(O)mür (O)cal 《国际自动化与计算杂志》2011,8(2):254-261
The coefficient diagram method (CDM) is one of the most effective control design methods. It creates control systems that
are very stable and robust with responses without the overshoot and small settling time. Furthermore, all control parameters
of the control systems are changed by varying some adjustment parameters in CDM depending on the demands. The model reference
adaptive systems (MRAS) are the systems that follow and change the control parameters according to a given model reference
system. There are several methods to combine the CDM with MRAS. One of these is to use the MRAS parameters as a gain of the
CDM parameters. Another is to directly use the CDM parameters as the MRAS parameters. In the industrial applications, the
system parameters can be changed frequently, but if the controller, by self-tuning, recalculates and develops its own parameters
continuously, the system becomes more robust. Also, if the poles of the controlled systems approach the jw axis, the response of the closed-loop MRAS becomes more and more insufficient. In order to obtain better results, CDM is
combined with a self-tuning model reference adaptive system. Systems controlled by a model reference adaptive controller give
responses with small or without overshoot, have small settling times, and are more robust. Thus, in this paper, a hybrid combination
of MRAS and CDM is developed and two different control structures of the control signal are investigated. The two methods
are compared with MRAS and applied to real-time process control systems. 相似文献
63.
Petra Punčochářová-Pořízková Jiří Fürst Jaromír Horáček Karel Kozel 《Mathematics and computers in simulation》2010
This study deals with a numerical solution of a 2D unsteady flow of a compressible viscous fluid in a channel for low inlet airflow velocity. The unsteadiness of the flow is caused by a prescribed periodic motion of a part of the channel wall with large amplitudes, nearly closing the channel during oscillations. The channel is a simplified model of the glottal space in the human vocal tract and the flow can represent a model of airflow coming from the trachea, through the glottal region with periodically vibrating vocal folds, and to the human vocal tract. 相似文献
64.
We consider a system of Maxwell’s and Landau-Lifshitz-Gilbert equations describing magnetization dynamics in micromagnetism. The problem is discretized by a convergent, unconditionally stable finite element method. A multigrid preconditioned Uzawa type method for the solution of the algebraic system resulting from the discretized Maxwell’s equations is constructed. The efficiency of the method is demonstrated on numerical experiments and the results are compared to those obtained by simplified models. 相似文献
65.
İbrahim Büyükyazıcı 《Computers & Mathematics with Applications》2010,59(1):274-282
In this paper, we investigate convergence and approximation properties of a Chlodowsky type generalization of Stancu polynomials (we called Stancu–Chlodowsky polynomials).The rates of convergence of this generalization are obtained by means of modulus of continuity and by using the -functional of Peetre. We also present and prove theorems on weighted approximation and the order of approximation of continuous functions by these operators on all positive semi-axis. 相似文献
66.
Yılmaz Yılmaz 《Computers & Mathematics with Applications》2010,59(6):1957-1964
Our aim in this article is to introduce and study the notion of weak and strong Schauder bases in fuzzy normed spaces. Further, we introduce strong and weak fuzzy approximation properties and set a relationship between these two new notions which may provide an acceleration to the structural analysis of fuzzy normed spaces. 相似文献
67.
Aylin Kantarcı 《Multimedia Systems》2010,16(6):381-397
Real-time delivery of medical videos requires high level of quality of service that shows no tolerance to loss and delay.
In this study, how content-adaptive streaming can aid to maintain high-quality streaming sessions is investigated. The proposed
strategy allocates a specific amount of bandwidth to streaming sessions and takes advantage of the general structure of instructional
medical videos to decrease bandwidth consumption below this limit. The main contribution of the proposed mechanism is that
it eliminates the need for rate adaptation which is common in traditional streaming by employing a proper bandwidth management
scheme that enables constant bandwidth consumption below the allocated capacity. A streaming system based on the proposed
mechanism has been implemented and its performance has been tested via emulation. Experimental results indicate that content-adaptive
streaming successfully eliminates the need of rate adaptation during the delivery of critical data and hence preserves viewers’
satisfaction. 相似文献
68.
In this paper, regression analyses (RA) are presented for the neutronic calculation of ThO2 mixed 244CmO2 fuel with different neutronic parameters for various coolants, natural lithium, Li20Sn80 and Flinabe, respectively. The tritium breeding ratio (TBR), energy multiplication factor (M), total fission rate (Σf) and 232Th(n, γ) reaction is computed by XSDRNPM. In addition, this numerical results are estimated by RA depends on neutronic parameters and the empirical equations for neutronic performance are acquired. The results obtained by using XSDRNPM and the results of the RA, obtained empirical equations, are compared. The empirical equations indicate that RA can successfully be used for the prediction of the neutronic performance parameters in the hybrid reactor with a high degree of accuracy. In addition, correlation matrix is calculated to determined statistical relationships between variables TBR, M, Σf, and 232Th(n, γ). 相似文献
69.
The interactive whiteboard (IWB) has become a popular technology for instructors over the last decade. Though research asserts that the IWBs facilitate learning in different ways, there is a lack of studies examining actual IWB use in classroom settings based on learners’ perspectives by means of valid instruments. The purpose of this study is to develop a valid and reliable interactive whiteboard student survey in order to evaluate the IWB use based on perceptions of students who have been taught with IWBs. In establishing the theoretical base of the survey, the Technology Acceptance Model (TAM) and constructivist learning theories were considered. In addition, with respect to IWB use in classrooms, a number of studies emanated from countries such as the UK, the USA, and Australia were examined, and similar research questionnaires and findings and also reflections of students about IWBs were utilized to create an item pool. A 39-item survey was conducted among middle school students (N = 263) from the city of Istanbul in Turkey. Collected data was exposed to exploratory factor analysis and resulted in a 26-item, three-factor survey, whose factors were named as the perceived efficiency of IWB, perceived learning contribution and motivation, and the perceived negative effects of IWB. The results of the analyses illustrated that this new IWB student scale, which explains 50% of the total variance with a good level of Cronbach’s Alpha coefficient (0.93) is a valid and reliable instrument designed specifically for measuring the use of IWBs in real classroom settings. Besides, theoretical foundations of interactive whiteboard use, the development process of the instrument, and results of validity and reliability analyses were discussed in detail. 相似文献
70.