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   

Education in modern Egypt     

M. K. Harby  M. El -Hadi Affifi 《International Review of Education/Internationale Zeitschrift für Erziehungswissenschaft/Revue internationale l'éducation》1958,4(1):423-439

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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   

Problem‐based learning benefits for basic sciences education     

Amal A. El‐Moamly M.D.  Ph.D. 《Anatomical sciences education》2008,1(4):189-190

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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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Dargah libraries in India: a comparative study     

Mohamed Taher  Amin Ahmed Khan  Muhammed Burhanuddin 《International Information and Library Review》2013,45(4):337-345

This paper relates to the difficulty in retrieving precise information from big repositories of magazine articles in full text, and proposes an Extended Markup Language (XML) vocabulary for improving retrieval rates. The hypothesis tested was as follows: Magazine articles marked up with an XML vocabulary, indexed only by selected parts, give more precise search results than the same search using full text index.

The study was exploratory with the following characteristics: 29 magazine articles were tested for results, 8 scholars were interviewed for defining 23 search strategies and evaluating results. The data showed that precision improved from 40.72% with full text search to 62.84% using XML markup and searching only in specific labels.

Revision of the vocabulary and more testing has to be done by the library and information science community in order to obtain a valid vocabulary and provide more research results. Cultural characteristics and politics of librarians and information managers’ community are as important as technical issues in order to consider any technical proposal to be implemented successfully to achieve interoperability.  相似文献   

Factors Influencing Schoolchildren's Responses to a Questionnaire in Wildlife Conservation Education     

Jean-Marie Ballouard  Stephen J. Mullin  Rastko Ajtic  José Carlos Brito  El Hassan ElMouden  Mehmet Erdogan 《International Journal of Science Education》2013,35(3):469-483

Questionnaires are important tools for assessing attitudes regarding conservation issues. However, they are not easily comparable and their reliability has been insufficiently assessed. We examined factors influencing responses to open- and closed-ended questions about animal conservation to more than 600 schoolchildren (9 years old on average). We analysed the level of understanding, controllable (e.g. sample size) and less controllable factors (e.g. affectivity). Most children responded appropriately to the questions, but subtle changes in the phrasing influenced the answers. Affectivity towards endearing species and spontaneity also influenced the responses whereas small sample sizes (～50 children) provided relatively stable patterns. Overall, we suggest that standardization of questionnaires administered over large spatial and time scales is needed to accurately assess children's attitudes towards conservation issues.  相似文献   

Perceptions of the Nature and ‘Goodness’ of Argument among College Students,Science Teachers,and Scientists     

Issam Abi‐El‐Mona 《International Journal of Science Education》2013,35(4):573-605

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Cellular immune response to infection by different genotypes of hepatitis C virus     

Mohamed El-Shahat Ebeid  Kadry Abdel-Kader El-Bakry 《Indian journal of clinical biochemistry : IJCB》2009,24(3):234-240

The present study aimed to estimate the cellular immune response to infection by different HCV genotypes in some Egyptian patients with chronic liver disease. HCV-RNA and HCV genotypes were conducted using type-specific primers to amplify the core region of HCV genome. The levels of IFN-gamma and TNF-alpha, PIIINP, SOD enzyme were also determined. The results showed that genotype 4 was the prevalent one (88.57%).Genotype 3 was found mixed with genotype 2 and 4 (11.42% and 34.28% respectively). Genotype 1 was absent from patients under study. No significant differences were observed in the level of IFN-gamma interferon, SOD enzyme and ALT enzyme between those genotypes. On the other hand the level of TNF-alpha was greatly increased in patients infected with mixed HCV genotypes 3, 4 compared with patients with genotype 4 and those infected with mixed genotypes 2, 3. Otherwise PIIINP was decreased significantly of the same group compared with other groups.  相似文献