Networked feedback control for nonlinear systems with random varying delays

This paper discusses the controller synthesis problem of a nonlinear networked controlled system subject to delays in the measurement and actuation channels. The communication through the network also suffers non-stationary packet dropouts. The bounded nonlinearities in the plant state satisfy Lipschitz conditions. A Lyapunov function is developed for the closed-loop system considering dynamic output feedback and the resulting stabilization conditions are drawn in the form of linear matrix inequalities to ensure that the system is exponentially stable in the mean-square sense. The developed conditions are represented in the form of a convex optimization problem and the results are tested by simulation on a quadruple-tank process.     

A self-determination theory into the psychological needs of CALL: Probing EFL teachers’ autobiographical narratives

Education and Information Technologies - Addressing psychological needs in computer-assisted language learning (CALL) has a critical role in developing learners’ motivation to use...     

An investigation of the Gregorian chronology of early Islamic history : A Pilot Study

This pilot study presents a lunar and Gregorian chronology of the Sira, that is the biography of the prophet Muhammad. The paper discusses the problems surrounding the chronology of very early Islamic history, namely, the pre‐Hijra era. This history is not covered by the Hijra calendar, and therefore, historians dated its events using other primitive dating systems, resulting in considerable difficulties and inaccuracies when comparing Gregorian dates of this early Islamic history. In order to overcome this problem and establish an accurate chronology of the early Islamic history, the introduction of a new lunar calendar (the Muhammadi calendar) which starts with the birth month and year of the prophet Muhammad, and covers all Islamic history including the pre‐Hijra era, is suggested. The Muhammadi calendar was used to study the earliest three versions of the Sira. All dated events of the Sira were compiled from these sources and presented, for the first time, according to their historical order. The Muhammadi dates of these events were then calculated. For the first time, a computer program was designed to convert the Muliammadi dates to their Christian equivalent. The program was then used to compute the Gregorian dates of the events of the Sira.     

Finite-time analysis and H∞ control for switched stochastic systems

This paper is concerned with the finite-time stability, boundedness and H_∞ control problems for a class of switched stochastic systems. Using the average dwell time method and the multiple Lyapunov-like function technique, some sufficient conditions are proposed to guarantee the finite-time properties for the switched stochastic systems in the form of matrix inequalities. Also, a state feedback controller for the finite-time H_∞ control problem is obtained. An example is employed to verify the effectiveness of the proposed method.     

Efficiency of antibiotics and gamma irradiation in eliminating Streptomyces strains isolated from paintings of ancient Egyptian tombs

Forty-six Streptomyces strains were isolated from paintings and stone surfaces from Tell Basta and Tanis tombs (80 km south-east Cairo, Egypt). Eight of these strains were selected to determine their sensitivity against 13 antibiotics. In general, high levels of resistance could be observed. Gentamycin, spiramycin and doxycycline were the most effective antibiotics against the majority of strains under study. Due to the observed antibiotic resistances, gamma irradiation was studied as a possible alternative to inhibit microbial growth. Isolated bacteria were exposed to different doses of gamma irradiation (5, 10, 15, 20 and 25 kGy). The growth of all Streptomyces isolates except S. canarius was completely inhibited at 25 kGy. The applied doses of gamma irradiation did not cause any observable alterations or colour changes to pigments and binding media (arabic gum, animal glue and egg-yolk) used in the paintings.     

Robust packet-based nonlinear fuzzy networked control systems

A class of networked nonlinear control systems with norm-bounded uncertainties is presented in this paper. The class is represented by Takagi–Sugeno (T-S) fuzzy models with packet processing. The network loop delay is considered either as known delay or random delay. For the former case, we develop conditions that guarantee the robust asymptotic stability and state-feedback stabilization with strict dissipativity and cast the results in linear matrix inequality (LMI) framework. Next employing a probabilistic-based delay partitioning method to deal with random delay, we establish novel LMI criteria for strict dissipative stability analysis and feedback synthesis. The efficacy of the ensuing techniques is demonstrated by numerical solution of typical examples and Mont Carlo simulation.