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
Objective: The purpose of this study is to analyse Iranian scientific publications in the neuroscience subfields by librarians and neuroscientists, using Science Citation Index Expanded (SCIE) via Web of Science data over the period, 2002–2008. Methods: Data were retrieved from the SCIE. Data were collected from the ‘subject area’ of the database and classified by neuroscience experts into 14 subfields. To identify the citation patterns, we applied the ‘impact factor’ and the ‘number of publication’. Data were also analysed using HISTCITE, Excel 2007 and SPSS. Results: Seven hundred and thirty‐four papers have been published by Iranian between 2002 and 2008. Findings showed a growing trend of neuroscience papers in the last 3 years with most papers (264) classified in the neuropharmacology subfield. There were fewer papers in neurohistory, psychopharmacology and artificial intelligence. International contributions of authors were mostly in the neurology subfield, and ‘Collaboration Coefficient’ for the neuroscience subfields in Iran was 0.686 which is acceptable. Most international collaboration between Iranians and developed countries was from USA. Eighty‐seven percent of the published papers were in journals with the impact factor between 0 and 4; 25% of papers were published by the researchers affiliated to Tehran University of Medical Sciences. Conclusion: Progress of neuroscience in Iran is mostly seen in the neuropharmacology and the neurology subfields. Other subfields should also be considered as a research priority by health policymakers. As this study was carried out by the collaboration of librarians and neuroscientists, it has been proved valuable for both librarians and policymakers. This study may be encouraging for librarians from other developing countries. 相似文献
The study seeks to determine the underlying factors contributing to the overrepresentation of minorities in school disciplinary programs. Data from 207 Disciplinary Alternative Education Programs (DAEPs) in Texas are analyzed. The data represent more than 62 % of the student population of Texas school districts. Results support the hypothesis that the ‘whiteness’ of school district undesirably affects the overrepresentation of Black students (but not Hispanic students) in DAEP. Overrepresentation of Black students in disciplinary programs is significantly higher in urban school districts than in rural districts. The findings, however, add a new layer of complexity to the debate on the overrepresentation of minorities in disciplinary programs. This is because not only White school districts are more likely than other districts to exercise their discretionary authority to punish minorities but they also more frequently subject their minority students to mandatory disciplines that are well defined by the state. Plausible explanations of such overrepresentation is offered for future research. Neither wealth nor the districts’ type (urban, suburban, rural and mid-size) have been found to have significant impact on discretionary or mandatory disciplinary actions against minority students. 相似文献
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
Purpose: The aim of this study was to review the effect of school-based physical activity interventions on children’s wellbeing.
Method: A systematic search of school-based physical activity studies was conducted using EBSCOhost PsycInfo, EBSCOhost Medline and Web of Science. Initially 995 studies were retrieved and, following the removal of duplicates, the titles and abstracts of 984 studies were screened. This screening identified 53 relevant studies from which 42 were excluded, resulting in 11 articles being reviewed.
Results: Three studies reported a positive increase in wellbeing; however, only one of those studies also significantly increased physical activity. It was apparent that the measurement of wellbeing and physical activity was inconsistent across studies, making conclusions difficult to draw. The wellbeing measures used neglected to account for the children’s perspectives of wellbeing.
Conclusions: The effect of a physical activity intervention on increasing wellbeing appears to be more complex than originally believed. The complexity may in part be due to methodological issues and the choice of wellbeing and physical activity measurement. We recommend that future physical activity interventions include a measure of wellbeing developed from the child’s perspective, and that future reviews narrow the search to only interventions that have had success at increasing physical activity before exploring effects on wellbeing. 相似文献
ABSTRACTSpiritual health is one of the most important aspects of the elders’ health. The aim of this study was to develop and evaluate psychometric properties of a scale for evaluating spiritual health of older adults in Iran. This is a mixed research, consisted of two phases. First, the perception of elder people regarding the spiritual health was explored, using directed content analysis, and the scale items generated based on the results. Second, the content, face and construct validity were determined. Exploratory factor analysis was used for the construct validity. To determine the reliability, Cronbach’s alpha and test-retest were used. Preliminary designed questionnaire included 94 items, which were reduced to 38 following the content and face validity processes. Exploratory factor analysis demonstrated that 20 items loaded on five factors determined about 66% of variance. The total internal consistency of the scale was 0.89. Results of test-retest indicated a Pearson correlation coefficient of 0.85 while intra-class correlation coefficient of scale was 0.92. The ESHS is a short, user-friendly valid and reliable tool which can be used for assessing the spiritual health of older adults. 相似文献
The phenomenon of adopting a religious lifestyle is growing worldwide in general and in Israel in particular. In the Israeli context, the transition from a secular lifestyle to a religious one is defined as “repentance”. Sociologists define the repentant as someone who has changed his or her beliefs, opinions and behaviours in the direction of the religious-ritualistic establishment. The aim of this research was to examine the attitudes of homeroom teachers in secular state high schools towards the phenomenon of becoming religious among their students. A qualitative methodology was employed for gathering and analysing the data. The findings show that most of the teachers (79%) claimed that the phenomenon of becoming religious is taking place in their classes to some degree or other. Most of the teachers mentioned the features of adolescence (forming an identity, seeking meaning, and peer influence) as the main reasons for becoming religious. At this era of radicalisation, teachers, with the support of the entire education system, are expected to provide a suitable response to those adolescents seeking their way, and help them navigate their path. 相似文献
This paper attempts to critically review theories of learning from the perspective of engineering education in order to align relevant assessment methods with each respective learning theory, considering theoretical aspects and practical observations and reflections. The role of formative assessment, taxonomies, peer learning and educational policy as regards promoting the learning of engineering is discussed. It is suggested that an integrated learning method in which cognitive levels, social factors and teamwork and behaviouristic elements are integrated will optimise the learning process on an engineering course. Moreover, assessment of learning should not be isolated from views of teaching and the learning methods employed by the university teacher. 相似文献
OBJECTIVE: This study examines the determinants of three types of child maltreatment: physical maltreatment, mental maltreatment, and child neglect among school children in the Kurdistan Province of Iran. The analysis examines the impact of socioeconomic, familial, demographic, and household dynamic factors on the three child maltreatment outcomes, and compares the differential impact of these factors across the three types of child maltreatment. A greater understanding of the factors associated with child maltreatment has the potential to inform public health interventions aimed at reducing specific forms of maltreatment and at identifying at risk populations. METHODS: Data were collected from 1,370 school students, age 11-18. Separate logistic models are fitted for six binary outcomes examining self-reported experiences of physical maltreatment in the home or school, mental maltreatment in the home or school, and child neglect in the home or school. RESULTS: Male children were more likely to report experiencing any kind of child maltreatment than girls. Residency in a rural area, poor parental relationships and the use of addictive substances by household members were associated with increased odds of reporting child maltreatment. Poor school performance was associated with the reporting of experiencing maltreatment at school. CONCLUSION: Each of the forms of child maltreatment is highly correlated with socioeconomic, demographic, and living condition factors. The results point to the strong influence that familial factors have in shaping a child's likelihood of reporting maltreatment. Characteristics of the mother were associated with maltreatment, but not characteristics of the father. The results highlight a number of mechanisms through which public health interventions may seek to reduce the prevalence of child maltreatment in Kurdistan; different approaches are needed to reduce child maltreatment in the home and school environments. 相似文献