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

  相似文献   

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   

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   

Transcoding numbers: A developmental approach of comprehension     

Mohamed Bernoussi  Abdelhamid Khomsi 《European Journal of Psychology of Education - EJPE》1997,12(3):293-304

The aim of this article is to study the development of transcoding ability using a comprehension task. We present the subject with a number written in the alphabetic code (e.g., Five) and we ask him to point out the equivalent in a set of four numbers written with the Arabic code (e.g., 5, 15, 50, 34). Results are discussed with regard to the cognitive and neuropsychological models of number transcoding.  相似文献   

Education in the Arab world     

Khalaf Mohamed Abdellatif 《Compare》2019,49(3):507-508

  相似文献   

Development and validation of Mobile Learning Acceptance Measure     

Sujeet Kumar Sharma  Mohamed Sarrab  Hafedh Al-Shihi 《Interactive Learning Environments》2017,25(7):847-858

The growth of Smartphone usage, increased acceptance of electronic learning (E-learning), the availability of high reliability mobile networks and need for flexibility in learning have resulted in the growth of mobile learning (M-learning). This has led to a tremendous interest in the acceptance behaviors related to M-learning users among the information systems researchers. Despite a large amount of significant research in the field of M-learning, the measurement of user acceptance of M-learning has not received attention. This research study intends to develop and validate a survey that measures users’ acceptance of M-learning. A total sample of 806 university and higher college students from different institutes in Oman participated in this study. This research study was conducted in two stages. The first stage using a sample size of 388 students initiated a generic questionnaire, and examined factorial validity and reliability. The second stage that was conducted using different sample of 418 students employed confirmatory factor analysis to establish factorial validity and measurement invariance. A correlated six-factor model (Flexibility, Suitability, Enjoyment, Efficiency, Economic and Social) was fit using maximum likelihood estimation. The internal consistency and item reliability of Mobile Learning Acceptance Measure was found to be at acceptable level for both samples.  相似文献   

The mental health and psychological well-being of refugee children and young people: an exploration of risk,resilience and protective factors     

Shaheen Mohamed  Miles Thomas 《Educational Psychology in Practice》2017,33(3):249-263

This research investigates the perceptions of refugee children, refugee parents and school staff regarding the positive adaptation of refugee children in a new social context and the effects on mental health and psychological well-being. This included an exploration of resilience and the role of risk and protective factors. Few studies have focused on views from a resilience perspective, and these have tended to use quantitative rather than qualitative measures. This mixed methods piece of “real world” research adopted a “what’s working well” perspective and explored the important voices of these children, parents and school staff. Staff, parent and child responses were triangulated to provide a rich picture of the potential protective factors operating within the school and family environment. Implications for practice are discussed.  相似文献