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91.
Jamy Stillman Kathryn Struthers Ahmed Erika Castañeda-Flores 《The Educational forum》2013,77(4):432-452
In this article, we share findings from a 3-year project in which novice teacher educators participated in Freirean culture circles and Boalian Theatre of the Oppressed (teatro) in order to critically explore the work of justice-oriented teacher education. Anchored in one of the project’s most resonant scenarios, the article illustrates how teatro cultivated among participants courage to confront injustice, while also shedding light on the complexities teacher educators may face when attempting to facilitate teacher learning, particularly when such learning is centered on equity and justice. 相似文献
92.
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
93.
Asma Ahmed Banishree Saha Anand Patwardhan Shwetha Shivaprasad Dipankar Nandi 《Resonance》2009,14(6):610-621
Our immune system, by and large, does a fine job in protecting us from opportunistic and infectious microbes, potential carcinogens and allergens. It is therefore crucial to understand the organization of the immune network. This article focuses on some important features and key players involved in adaptive immune response. The first part of the article dealt with the humoral immune response mediated mainly by immunoglobulins produced by the B cells. The second part deals with T cells, the Major Histocompatibility Complex (MHC)-encoded molecules, and Recombination Activating Genes (RAG) responsible for generating diverse B-cell receptors (BCR) and T-cell receptors (TCR). With the advent of newer and smarter infectious agents, it is important to understand the working of the immune network as more research in this area may facilitate the development of better protective strategies. 相似文献
94.
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
95.
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
96.
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
97.
Rahidzab Talib Razidah Ismail Roziah Mohd. Janor Azni Zain Ahmed Syed Abdul Kader Aljunid 《Assessment & Evaluation in Higher Education》1999,24(2):205-213
Since its inception 30 years ago, the then Department of Engineering Science, Institut Teknologi MARA (ITM) was given the responsibility of preparing all the students in the first year engineering programmes by giving enough knowledge in basic science and mathematics. The nation's vision to become a fully‐industrialised economy by the year 2020 required all institutes of higher learning (IHLs) in Malaysia to increase their intake of students in the science and technology courses, especially in engineering. However, at the upper secondary education level, students have the freedom to choose between the science‐based or non‐science combination of subjects. This has led to a dearth of science‐based students enrolling in IHLs. Because ITM believes that it is possible to educate individuals from various backgrounds, the engineering courses are open to students with a variety of academic qualifications. Special bridging courses were designed and created for such students since late 1996. The success or failure of the new courses can be assessed after the students have gone through the proper first year engineering courses which consist of Mathematics, Physics and Chemistry. This paper reports on a pilot study on the pioneer groups of students with variable entry qualifications to assess the effectiveness of the courses. The study involved the analysis of the students’ examination results as a performance indicator, and it was found that the bridging programme for non‐science students needed to be redesigned. It is also proposed that to improve the quality of the programme, and hence students’ performance, a regular review be conducted, student support activities be continued and to expand the use of self‐study materials. 相似文献
98.
99.
The relation between emotional and social development and family structure in the Sudanese capital, Khartoum, was examined. Children between the ages of 4 and 9 living in extended and nuclear families were compared on mothers' ratings of a range of childhood problems. Analysis revealed that children in nuclear families had more conduct, emotional, and sleep problems, poorer self-care, and were more likely to be overdependent than those living in extended families. They were also less likely to be breast fed, to be weaned later, and to have grandmothers involved in child care. Linear multiple regression revealed that, of these 3 childcare factors, grandmother's involvement was the strongest predictor of normal social and emotional adjustment. The possible protective characteristics of the extended family are discussed in relation to the importance of the grandmother as maternal advisor, social support, and socialization agent. 相似文献
100.
The present drinking water purification system in Egypt Uses surface water as a raw water supply without a pre-liminary filtration process.On the other hand,chlorine gas iS added as a disinfectant agent in two steps,pre- and post.chlorination.Due to these reasons most of water treatment plants suffer low fltering effectiveness and produce the trihalomethane (THM) species as a chlorination by-product.The Ismailia Canal represents the most distal downstream of the main Nile Rivet.ThUS its water contains all the proceeded pollutants discharged into the Nile.In addition.the downstream reaches of the canal act as an agricultural drain during the closing period of the High Dam gates in January and February every year.Moreover,the wide in-dustrial zone along the upstream course of the carlal enriches the canal water with high concentrations of heavy metals.The obtained results indicate that the canal gains up to 24.06×106m3 of water from the surrounding shallow aquifer during the closing period ofthe High Dam gates,while during the rest ofthe year,the callal acts as an influent stream losing about 99.6×106m3 of its water budget.The reduction oftotaI organic carbon(TOC) and suspended particulate mattes(SPMs)should be one of the central goals of any treatment plan to avoid the disinfectants by-products.The combination of sedimentation basins.gravel pre-filtration and slow sand filtration,and underground passage with microbiological oxidation-reduction and adsorption criteria showed good removal of parasites and bacteria and complete elimination of TOC.SPM and heavy metals.Moreover,it reduces the use of disinfectants chemicals and lowers the treatment costs.However,this purification system under the arid climate prevailing in Egypt should be tested and modified prior to application. 相似文献