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HU Jia-bing HE Yi-kang 《浙江大学学报(A卷英文版)》2006,7(10):1757-1764
INTRODUCTION Due to concerns about emissions from fossil fuels and the depletion of fossil fuel resources, re- newable energy systems are becoming a topic of great interest and investment in the world. In particular, wind energy has been the subject of much recent research and development. In order to overcome the problems associated with fixed-speed wind-turbine system and to maximize the wind energy capture, many new wind farms will employ wind turbines based on Doubly-Fed Induction Ge… 相似文献
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Induction of diabetes by Streptozotocin in rats 总被引：1，自引：0，他引：1
A. Akbarzadeh D. Norouzian M. R. Mehrabi Sh. Jamshidi A. Farhangi A. Allah Verdi S. M. A. Mofidian B. Lame Rad 《Indian journal of clinical biochemistry : IJCB》2007,22(2):60-64
The objective of this study is to induce experimental diabetes mellitus by Streptozotocin in normal adult Wistar rats via
comparison of changes in body weight, consumption of food and water, volume of urine and levels of glucose, insulin and C-peptide
in serum, between normal and diabetic rats. Intra-venous injection of 60mg/kg dose of Streptozotocin in adult wistar rats,
makes pancreas swell and at last causes degeneration in Langerhans islet beta cells and induces experimental diabetes mellitus
in the 2–4 days. Induction of experimental diabetes mellitus is indeed the first step in the plan of purification of pancreatic
Langerhans islet cells of normal rats for transplanting under the testis subcutaneous of experimentally induced diabetic rats.
Streptozotocin induces one type of diabetes which is similar to diabetes mellitus with non-ketosis hyperglycemia in some animal
species. For induction of experimental diabetes in male adult rats weighted 250–300 grams (75–90 days), 60mg/kg of Streptozotocin
was injected intravenously. Three days after degeneration of beta cells, diabetes was induced in all animals. The diabetic
and normal animals were kept in the metabolic cages separately and their body weight, consumption of food and water, urine
volume, the levels of serum glucose, insulin and C-peptide quantities in all animals were measured and then these quantities
were compared. For a microscopic study of degeneration of Langerhans islet beta cells of diabetic rats, sampling from pancreas
tissue of diabetic and normal rats, staining and comparison between them, were done. Induction of diabetes with Streptozotocin
decreases Nicotinamide-adenine dinucleotide (NAD) in pancreas islet beta cells and causes histopathological effects in beta
cells which probably intermediates induction of diabetes. In this study, we used Streptozotocin for our experiments in induction
of experimental diabetes mellitus. After Induction of diabetes, consumption of food and water, volume of urine and glucose
increased in the diabetic animals in comparison with normal animals, but the weight of body and the volume of insulin and
C-peptide decreased in the diabetic animals. Sampling and staining of pancreas tissue of diabetic and normal rats showed that
the Langerhans islet beta cells of diabetic rats have been clearly degenerated. In three days, Streptozotocin makes pancreas
swell and at last causes degeneration in Langerhans islet beta cells and induces experimental diabetes. It also changes normal
metabolism in diabetic rats in comparison with normal rats. Consumption of water and food, volume of urine, serum glucose
increases in diabetic animals in comparison with normal rats but the levels of serum insulin, C-peptide and body weight decreases. 相似文献
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The purpose of this paper is to extract features from vibration signals measured from motors subjected to accelerated bearing fluting aging and to detect the effects of bearing fluting at each aging cycle of induction motors. This trending of bearing degradation is achieved by monitoring the changes in the vibration signals at various sub-band levels. This is accomplished by the application of wavelet transforms and multi-resolution analysis in order to extract information from selected frequency bands with minimum signal distortion. 相似文献
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采用维持磁通始终恒定的方法对电机转矩直接控制，可解决交流异步电机控制精度和系统复杂性之间的矛盾，在电机状态变量观测及位置控制中应用了现代控制理论，和传统的矢量控制方法相比，在相同的性能指标下，该系统便于用微机来完成实时控制。 相似文献
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This paper presents a novel mega-Hz-level super high frequency zero-voltage soft-switching converter for induction heating power supplies. The prominent advantage of this topology is that it can absorb both inductive and capacitive parasitic components in the converter. The switch devices operate in a zero-voltage soft-switching mode. Consequently, the high voltage and high current spikes caused by parasitic inductors or capacitors oscillation do not occur in this circuit, and the high power loss caused by high frequency switching can be greatly reduced. A large value inductor is adopted between the input capacitor and the switches, thus, this novel converter shares the benefits of both voltage-type and current-type circuits simultaneously, and there are no needs of dead time between two switches. The working principles in different modes are introduced. Results of simulation and experiments operated at around 1 MHz frequency verify the validity of parasitic components absorption and show that this convener is competent for super high frequency applications. 相似文献
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A mentor’s aid in developing the competences of teacher trainees 总被引：1，自引：0，他引：1
The induction period is a very important time in the career of a teacher and has a long‐term influence on the teacher’s professional development, efficacy, job satisfaction and the length of his/her career. One of the key roles in this period is played by the trainee’s mentor. This paper presents the results of the extensive project ‘Partnership of Faculties and Schools’, carried out at the Pedagogical Faculty, University of Ljubljana, with the financial support of the European Social Fund and the Slovenian Ministry of Education, Science and Sport. We studied an induction project involving 361 teacher trainees and 331 mentors. The study reveals the trainees’ expectations towards their mentors and the mentors’ and trainees’ evaluations of how the mentor aids a teacher trainee in developing their competences. 相似文献
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休厄尔的科学哲学思想主要有三方面：他的哲学基础是“事实一观念”学说;他的哲学核心是作为真理发现理论的归纳学说;他的真理学说将符合说、融贯说结合起来。休厄尔的哲学思想不仅开启了科学哲学的先河,而且在英国哲学史上,他成功地摆脱了苏格兰常识主义哲学的影响,将哲学重新拉回到理论分析的道路上来。 相似文献
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The purpose of this paper is to describe the school-based contextual constraints perceived by beginning elementary teachers as they attempted to enact their visions of effective mathematics teaching and the components of a mathematics-specific, university-based induction program designed to support elementary teachers in their teaching of mathematics. A significant number of beginning teachers in the program indicated that curriculum pacing guides and grade level teachers often discouraged their enactment of effective mathematics teaching. We describe the components of the induction program in general and then discuss the specific ways that program mentors, who were elementary teachers with expertise in mathematics teaching, supported beginning teachers in navigating the constraints identified. Data suggest that supporting teachers’ pedagogical agency to navigate local school contexts should be an additional consideration in teacher preparation and induction programs. 相似文献