Robust dissipative control for internet-based switching systems     

Magdi S. Mahmoud  Hazem N. Nounou 《Journal of The Franklin Institute》2010,347(1):154-172

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   

Towards a competency model: A review of the literature and the competency standards     

Maryam El Asame  Mohamed Wakrim 《Education and Information Technologies》2018,23(1):225-236

Competency-based approaches using information and communication technologies have been the main solution of the organization’s expectations in all fields (public and private) to increase the products’ quality and employees’ capacity. Furthermore, the concept of competency can have several different definitions, which may make it difficult to model. As a result, without a good representation of the knowledge and competency and reusable definitions of competence, an e- Learning system will be unable to adapt to its users, to personalize learning activities. In this paper, we present a view of some important competency definitions and the main competency specifications, like the HR-XML specification (Human Resources XML), and the IMS Reusable Definition of Competency or Educational Objective (IMS RDCEO). Moreover, we suggest a competency model for training and education based on these specifications.  相似文献   

Social media networks and pedagogy at the University of Jordan     

Huda Karajeh  Mahmoud Maqableh  Lama Rajab  Hiba Mohammad  Tahani Khatib  Nabeel Al-Qirim  Ali Tarhini 《Education and Information Technologies》2018,23(5):2073-2090

This study examined impact of a social media networks course on student use of SNSs performance. Moreover, it examined the associations among course design, course materials, learning experiences and a social media networks course. Survey instrument is used to examine the relationships in the proposed model. A total of 380 questionnaires have been collected from students at the University of Jordan who studied the social media networks course. A structural equation modelling approach based on AMOS 20.0 statistical software is used to study the causal relationships and test the hypotheses between the observed and latent constructs in the proposed research model. The analysis results revealed that course materials and learning experiences directly, positively and significantly impacted the social media networks course, which in turn had a significant impact on students’ use social networks sites performance. Course design, however, did not impact the social media networks course. Our findings have important implications as we demonstrated the validity of the joint two different models and provide information about impact of studying social media networks course on students’ academic performance.  相似文献   

Toxic effects of Litsea elliptica Blume essential oil on red blood cells of Sprague-Dawley rats     

Izatus Shima Taib  Siti Balkis Budin  Seri Maseran Siti Nor Ain  Jamaludin Mohamed  Santhana Raj Louis  Srijit Das  Sulaiman Sallehudin  Nor Fadilah Rajab  Othman Hidayatulfathi 《Journal of Zhejiang University. Science. B》2009,10(11):813-819

Litsea elliptica Blume leaves have been traditionally used as medicinal herbs because of its antimutagenicity, che-mopreventative and insecticidal properties. In this study, the toxic effects of L. elliptica essential oil against Sprague-Dawley rat's red blood cells (RBCs) were evaluated. L. elliptica essential oil was given by oral gavage 5 times per week for 3 treated groups in the doses of 125, 250, and 500 mg/(kg body weight), respectively, and the control group received distilled water. Full blood count, RBC osmotic fragility, RBC morphological changes, and RBC membrane lipid were analyzed 28 d after the treatment. Although L. elliptica essential oil administration had significantly different effects on hemoglobin (Hb), mean cell hemoglobin concentration (MCHC), mean cell volume (MCV), and mean cell hemoglobin (MCH) in the experimental groups as compared to the control group (P<0.05), the values were still within the normal range. L. elliptica induced morphological changes of RBC into the form of echinoeyte. The percentage of echinocyte increased significantly among the treated groups in a dose-response manner (P<0.001). The concentrations of RBC membrane phospholipids and cholesterol of all treated groups were significantly lower than those of control group (P<0.001). However, the RBC membrane osmotic fragility and total proteins of RBC membrane findings did not differ significantly between control and treated groups (P>0.05). It is concluded that structural changes in the RBC membrane due to L. elliptica essential oil administration did not cause severe membrane damage.  相似文献   

Flatness-based adaptive fuzzy output tracking excitation control for power system generators     

Hassan A. Yousef  Mohamed Hamdy  Muhammad Shafiq 《Journal of The Franklin Institute》2013

In this paper, a novel approach for the design of an indirect adaptive fuzzy output tracking excitation control of power system generators is proposed. The method is developed based on the concept of differentially flat systems through which the nonlinear system can be written in canonical form. The flatness-based adaptive fuzzy control methodology is used to design the excitation control signal of a single machine power system in order to track a reference trajectory for the generator angle. The considered power system can be written in the canonical form and the resulting excitation control signal is shown to be nonlinear. In case of unknown power system parameters due to abnormalities, the nonlinear functions appearing in the control signal are approximated using adaptive fuzzy systems. Simulation results show that the proposed controller can enhance the transient stability of the power system under a three-phase to ground fault occurring near the generator terminals.  相似文献   

Polymorphisms of the <Emphasis Type="Italic">IGF1</Emphasis> gene and their association with growth traits,serum concentration and expression rate of <Emphasis Type="Italic">IGF1</Emphasis> and <Emphasis Type="Italic">IGF1R</Emphasis> in buffalo     

Mohammed A. El-Magd  Ayman A. Saleh  Abeer A. Nafeaa  Shymaa M. El-Komy  Mohamed A. Afifi 《Journal of Zhejiang University. Science. B》2017,18(12):1064-1074

The insulin-like growth factor 1 (IGF1) gene is a member of the group of somatotropin axis genes that play a significant role in cell proliferation and growth of muscles. Here, we searched for polymorphisms in buffalo IGF1 and found two novel single nucleotide polymorphisms (SNPs), G64A and G280A, in the noncoding sequences of exon 1 and exon 4, respectively. Statistical analysis of different genotypes showed that the individuals with GG genotypes had significantly (P<0.05) higher body weight (BW) and average daily gain (ADG) than those with other genotypes at ages of 3–6 months in G64A SNP and 6–9 months in G280A SNP. The combined genotypes of these two SNPs produced three haplotypes, GG/GG, AG/AG, and AA/AA, which were significantly associated (P<0.0001) with BW and ADG at an age from 3 to 12 months. Buffaloes with the homozygous GG/GG haplotype showed higher growth performance than other buffaloes. The two SNPs were correlated with mRNA levels of IGF1 and IGF1 receptor (IGF1R) in semitendinosus muscle as well as with the serum concentration level of IGF1. Also, buffaloes with GG/GG haplotype showed higher mRNA and serum concentration levels. The data revealed that these two SNPs could be valuable genetic markers for selection of Egyptian buffaloes for better performance in the population.  相似文献   

Effects of segmenting,signalling, and weeding on learning from educational video     

Mohamed Ibrahim  Carmen M. Greenwood  Denna Wheeler 《Learning, Media and Technology》2012,37(3):220-235

Informed by the cognitive theory of multimedia learning, this study examined the effects of three multimedia design principles on undergraduate students' learning outcomes and perceived learning difficulty in the context of learning entomology from an educational video. These principles included segmenting the video into smaller units, signalling to direct students' attention to relevant information, and weeding to remove any non-essential content (SSW). It was hypothesized that the SSW treatment would decrease perceived learning difficulty and facilitate the transfer of knowledge and the structural knowledge acquisition. Results of the study demonstrate that participants in the SSW group outperformed the non-SSW group on the tests of knowledge transfer and structural knowledge acquisition and reported lower levels of learning difficulty. These findings support the use of SSW to help novice learners organize and integrate knowledge from complex, dynamic audio-visual media like video.  相似文献   

Level of Students＇ Achievement in Mathematics at the End of Elementary Education in Yemen     

Tarig Mohamed  Ali Mohamed  Khair Ahmad  Zamri Khairani  Tahra Aisa  Elrofai 《美中教育评论》2012,(6):588-593

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Kinematic optimization of 2D plunging airfoil motion using the response surface methodology     

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   

Contextual and pedagogical considerations in teaching for forgiveness in the Arab world     

Ilham Nasser  Mohammed Abu-Nimer  Ola Mahmoud 《Compare》2014,44(1):32-52

This study was conducted among Arab teachers in four countries in the Middle East (Jordan, Lebanon, Egypt and Palestine) to examine their views and methods on teaching for forgiveness in their classrooms. A total of 87 teachers in K-12 classrooms participated in semi-structured interviews as part of a larger study on teaching for forgiveness in the region. Thematic analyses of interviews suggested that teachers created opportunities to model and teach forgiveness as part of their civics education curriculum. They also expressed eagerness for instructional guidance and curriculum materials to systematically teach forgiveness in schools. The strength of religion and historical religious figures as positive sources for teaching forgiveness was also evident. Findings highlight the need to integrate education for peace and forgiveness in the education system, especially as a result of recent political developments in the Middle East, and to provide methods to assist teachers to do so in their classrooms.  相似文献