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排序方式: 共有75条查询结果,搜索用时 15 毫秒
1.
A new active R filter which realizes a second order bandpass transfer function is given. The network employs only resistors and two operational amplifiers. Sensitivities to all passive and active circuit components are very low. Design equations are given and experimental results are also included. 相似文献
2.
Mahmoud Mekadem Taha Chettibi Samir Hanchi Laurent Keirsbulck Larbi Labraga 《浙江大学学报(A卷英文版)》2012,13(2):105-120
The propulsive efficiency of a plunging NACA0012 airfoil is maximized by means of a simple numerical optimization method based
on the response surface methodology (RSM). The control parameters are the amplitude and the reduced frequency of the harmonic
sinusoidal motion. The 2D unsteady laminar flow around the plunging airfoil is computed by solving the Navier-Stokes equations
for three Reynolds number values (Re = 3.3×103, 1.1×104, and 2.2×104). The Nelder-Mead algorithm is used to find the best control parameters leading to the optimal propulsive efficiency over
the constructed response surfaces. It is found that, for a given efficiency level and regardless of the considered Re value, it is possible either to obtain high thrust by selecting a high oscillation frequency or to reduce the input power
by adopting a low plunging amplitude. 相似文献
3.
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. 相似文献
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Mahmoud E.F. Abdel-Haliem Mona F. Ali Mohamed F. Ghaly Akmal A. Sakr 《Journal of Cultural Heritage》2013,14(1):45-50
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. 相似文献
8.
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. 相似文献
9.
Mahmoud Abdulai Mahmoud Elizabeth Oppong Daniel Twimasie Mohammed Muniru Husseini Adelaide Naa Amerley Kastner Moses Oppong 《Journal of Marketing for HIGHER EDUCATION》2020,30(1):105-124
ABSTRACT This study seeks to examine the influence of the cultural elements on international students’ country choice. It also examines whether individual values moderate the influence of cultural elements on the country choice of international students. Drawing upon a sample size of 223, the data was analysed using structural equation modelling technique. Among the five cultural elements, education, language and social institutions were found to have a positive significant influence on the international student’s country choice. When moderated by individual values education was found to be the only key significant value to international students when selecting a country to further their education. The cultural elements should be given much attention by marketers, government and managers of academic institutions. An improvement in the standards of education in developing countries would attract more students from developed countries. 相似文献
10.
A class of hybrid multi-rate control models with time-delay and switching controllers are formulated based on combined remote control and local control strategies. The problem of robust dissipative control for this discrete system is investigated. An improved Lyapunov-Krasovskii functional is constructed and the subsequent analysis provides some new sufficient conditions in the form of LMIs for both nominal and uncertain representations. Several special cases of practical interests are derived. A numerical simulation example is given to illustrate the effectiveness of the theoretical result. 相似文献