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91.
Qun Liu Daqing Jiang Tasawar Hayat Ahmed Alsaedi 《Journal of The Franklin Institute》2019,356(13):7466-7485
In this paper, we investigate the threshold dynamics of a stochastic delayed SIS epidemic model with vaccination and double diseases which make the research more difficult. We establish sufficient conditions for extinction and persistence in the mean of the two diseases. We also obtain the threshold between persistence in the mean and extinction of the stochastic system. It is shown that: (i) time delay and environmental white noise have important effects on the persistence and extinction of the two diseases; (ii) the two diseases can coexist under certain conditions. Finally, some numerical simulations are provided to demonstrate the analytical results. 相似文献
92.
Ashik Ahmed Md. Mehedi Hassan Galib Shafi Md. Kawsar Zaman Golam Sarowar 《Journal of The Franklin Institute》2018,355(1):197-217
In wind power system, low frequency oscillations are observed due to imbalance between mechanical input and electrical output. Hence, variable susceptance controllers are being adopted to mitigate these oscillations. However, improper modulation of control parameters also leads to system instability. Therefore, we propose an optimization methodology for mitigating low frequency oscillations in wind power generation system. To visualize our methodology, we use a lead-lag type variable susceptance controller for fixed speed induction generator (FSIG) based wind generation system. Then, we optimize gain and time constants of lead-lag controller using three optimization algorithms: particle swarm optimization (PSO), genetic algorithm (GA), and flower pollination algorithm (FPA). Later, we perform non-linear time domain simulation and quantitative analysis to find average fitness, standard deviation, run time, and iteration number for these optimization algorithms. Moreover, non-parametric statistical analysis, such as Kolmogorov–Smirnov and Wilcoxon signed-rank tests are employed for identifying statistically significant differences among these algorithms. 相似文献
93.
Ahmed Hassanien 《Higher Education in Europe》2007,32(2-3):135-150
The importance of group learning has increased significantly in higher education in the past two decades (Houldsworth and Mathews, 2000). The primary focus of this study is to explore the feelings and experience of students regarding group work and group assessment in higher education. The study is exploratory based on a qualitative focus group approach. Interestingly, students felt that group work is a significant method to foster the development of critical thinking through discussion, clarification of ideas, and evaluation of others' ideas. Students consider “poor communication” and “poor attendance at group meetings” as the main challenges they face when working within a group. Also, students identified “dedicated assignment seminars” as the most effective tool, which could be used to enhance the effectiveness of group work. This study reinforces the findings of previous research into group work suggesting that the experience is a generally positive one for students. Results are discussed in the context of current theoretical and empirical work on group‐based learning, education implications and areas for further research are discussed. 相似文献
94.
The major aim of power quality (PQ) enhancing techniques is to maintain a specified voltage magnitude at a desired frequency for sensitive loads irrespective of faults on the power distribution network. The dynamic voltage restorer (DVR) is a device used to mitigate voltage sags to regulate load voltage. This paper presents a mathematical model for leading series voltage injection to mitigate sags thereby achieving the improvement of the utility power factor as well as power sharing between the DVR and utility. The power sharing will be as per requirement to compensate the sags considering the available distributed generation (DG). The approach of mitigating voltage sags using the concept of leading series voltage injection is suitable for those locations where phase shift in the voltage will not cause any problem. The MATLAB/SIMULINK SimPowerSystem toolbox has been used to obtain simulation results to verify the proposed mathematical model. 相似文献
95.
The present study carries out an impact analysis of a conditional cash transfer (CCT) program for secondary-school girls in seven districts of Khyber Pakhtunkhwa province in Pakistan, including Battagram, Bonair, Hangu, Kohistan, Shangla, Tank, and Upper Dir. In 2012 we collected household-level primary data and used a probit model for quantitative analysis. Further, we conducted various focus group discussions and key informant interviews in the target areas. Results show that the chances of female schooling decrease with a rise in family size. The chances of female education increase by 1.8 and by 3.3 % if household heads and their spouses have one additional year of schooling, respectively. Better educational services and rises in family income increase the chances of female ecucation by 11 and 0.3 %, respectively. Finally, socioeconomic awareness, improved economic conditions, and CCTs increase the chances of female education by 5.2, 4.7, and 0.03 %, respectively. Overall, the stipend program (CCTs) shows a pareto improvement. Our results indicate that 35 % of girls will drop out in the absence of a stipend program. The present study recommends that to increase program effectiveness, local-level monitoring and program evaluation may be improved, delays in stipend payments to female students should be reduced, a grievance redressal mechanism for parents and guardians should be introduced, and clear synergies should be developed with other transfer programs. 相似文献
96.
This multiple case study examined pre-service teachers perceptions of effective post-secondary instruction. Pre-service teachers
were asked to write essays describing an effective teacher of their choice. Twenty-one essays were randomly selected. Data
analysis involved open coding of each essay, content analysis of each essay using Anderson and Burns’ (Research in classrooms:
The study of teachers, teaching, and instruction (1st ed.). Oxford, England; New York: Pergamon Press, 1989) empirically derived
dimensions of instruction, and effect size analysis of student and teacher roles. Instructional components were identified
that differentiate between effective inquiry instruction and effective instruction. Effective inquiry instruction was associated
with more and different teacher and student roles, more activities as part of instruction, and more student small group discussion
than was effective instruction. 相似文献
97.
98.
Judith Lederman Norman Lederman Selina Bartels Juan Jimenez Mark Akubo Shereen Aly Chengcheng Bao Estelle Blanquet Ron Blonder Mariana Bologna Soares de Andrade Catherine Buntting Mustafa Cakir Heba EL-Deghaidy Ahmed ElZorkani Estelle Gaigher Shuchen Guo Arvi Hakanen Soraya Hamed Al-Lal Cigdem Han-Tosunoglu Annemarie Hattingh Anne Hume Serhat Irez Gillian Kay Ozgur Kivilcan Dogan Kerstin Kremer Pi-Chu Kuo Jari Lavonen Shu-Fen Lin Cheng Liu Enshan Liu Shiang-Yao Liu Bin Lv Rachel Mamlok-Naaman Christine McDonald Irene Neumann Yaozhen Pan Eric Picholle Ana Rivero García Carl-Johan Rundgren David Santibáñez-Gómez Kathy Saunders Renee Schwartz Frauke Voitle Jakob von Gyllenpalm Fangbing Wei Jocelyn Wishart Zhifeng Wu Huang Xiao Yalcin Yalaki Qiaoxue Zhou 《科学教学研究杂志》2019,56(4):486-515
Although understandings of scientific inquiry (as opposed to conducting inquiry) are included in science education reform documents around the world, little is known about what students have learned about inquiry during their elementary school years. This is partially due to the lack of any assessment instrument to measure understandings about scientific inquiry. However, a valid and reliable assessment has recently been developed and published, Views About Scientific Inquiry (VASI; Lederman et al. [2014], Journal of Research in Science Teaching, 51, 65–83). The purpose of this large-scale international project was to collect the first baseline data on what beginning middle school students have learned about scientific inquiry during their elementary school years. Eighteen countries/regions spanning six continents including 2,634 students participated in the study. The participating countries/regions were: Australia, Brazil, Chile, Egypt, England, Finland, France, Germany, Israel, Mainland China, New Zealand, Nigeria, South Africa, Spain, Sweden, Taiwan, Turkey, and the United States. In many countries, science is not formally taught until middle school, which is the rationale for choosing seventh grade students for this investigation. This baseline data will simultaneously provide information on what, if anything, students learn about inquiry in elementary school, as well as their beginning knowledge as they enter secondary school. It is important to note that collecting data from all of the approximately 200 countries globally was not humanly possible, and it was also not possible to collect data from every region of each country. The results overwhelmingly show that students around the world at the beginning of grade seven have very little understandings about scientific inquiry. Some countries do show reasonable understandings in certain aspects but the overall picture of understandings of scientific inquiry is not what is hoped for after completing 6 years of elementary education in any country. 相似文献
99.
Hong-Li Li Jinde Cao Haijun Jiang Ahmed Alsaedi 《Journal of The Franklin Institute》2018,355(13):5771-5789
This paper considers the finite-time synchronization problem for a class of fractional-order complex dynamical networks (FOCDNs). By utilizing the properties of fractional calculus and fractional-order comparison principle, we propose a new lemma. Base on the new lemma, some analysis techniques and algebraic graph theory method, some novel criteria are given to ensure finite-time synchronization of FOCDNs, and the upper bound of the setting time for synchronization is estimated. At last, numerical simulations are given to verify the effectiveness of the obtained results. 相似文献
100.
Ahmed Yaqinuddin Muhammad Zafar Muhammad Faisal Ikram Paul Ganguly 《Anatomical sciences education》2013,6(2):125-133
Assessing teaching‐learning outcomes in anatomical knowledge is a complex task that requires the evaluation of multiple domains: theoretical, practical, and clinical knowledge. In general, theoretical knowledge is tested by a written examination system constituted by multiple choice questions (MCQs) and/or short answer questions (SAQ). The assessment of practical knowledge (three‐dimensional anatomical concepts) involves oral, spot, or objective structured practical examinations (OSPE). Finally, the application of anatomical knowledge to patients is tested mainly through objective structured clinical examinations (OSCE). The major focus of this study is the OSPE. Although many schools challenge students using this tool in practical examinations in the early phase of the curriculum, the true meaning of OSPE is frequently forgotten and it becomes, in reality, a spot examination. This article, for the first time, describes how the concept of the OSPE has evolved and is currently being used to assess the practical domain of anatomical knowledge in a problem‐based curriculum at Alfaisal University College of Medicine. In addition, it describes the main differences from the spot examination, which is normally used in traditional medical curricula. The authors believe that the OSPE remains the most efficient tool to assess the practical aspects of anatomical knowledge in a system where basic knowledge is integrated with the clinical or functional part of anatomy. However, this contention only holds true if the OSPE process revolves around structured objectives. Anat Sci Educ 6: 125–133. © 2012 American Association of Anatomists. 相似文献