Physical Basis of Power Transmission Wire’s Deicing by Electrodynamic Method

In this paper a new method of power transmission wire’s deicing is described. Deicing process is divided into three independent sub-processes, namely the process of melting the thin inner layer of ice cover, the process of ice cylinder fracturing into components due to bending deformations; the process of shaking off the fractured ice cylinder elements by inertial forces. Mathematical description of each sub-process is shown

ENERGY-EFFICIENT PHOTOVOLTAIC INSTALLATION

Abstract In this paper R&D basics for photovoltaic installation development are presented. Efficiency of energy conversion process depending on the azimuth and zenith angles of the installation's rotation is investigated. Recommendations on the installations' class design are given. Technical and economic assessments of the proposed solutions are made. Key words: solar tracker, solar cell, acrylic concentrator, efficiency, photovoltaic modules. Currently in Russia there is an acute problem of the lack of cheap electricity in the areas with decentralized electric power supply. Now that area is embracing about 70 % of the country with a population of 20 million people [1]. Currently stand-alone diesel systems use allowы to get only a very expensive electric power, which in some towns costs under 56 rubles per kW·h and above. It is therefore very important in such areas to use autonomous renewable energy sources, which include solar energy. Now solar power engineering development is progressing at a rapid speed -30% per year. In 2013 the solar power plants of total power about 30 GW were put into operation, whereas the total power in 2012 was 102 GW. In addition, taking into account the purity and the prevalence of renewable energy sources, solar energy is one of the most promising. But at the present moment solar power plants have two weighty drawbacks, delaying their mass distribution. The drawbacks are the high price of solar cells and relatively low efficiency of conversion the solar energy into electric energy during the entire day. The aim of this work is to search the appropriate methods of increasing the efficiency of solar energy conversion into electric energy and to develop the experimental sample of the installation. The high price of solar power plants is determined primarily by high cost of photocells per kW of electric power. If the efficiency of photocells is increased using, for example, instead of single-crystal cell (efficiency 15-17%) gallium arsenide cells (efficiency 30-35%), the cost is increased many times (about 40 times) -from about 2,5$to 100$ per kW, respectively. Therefore it is more promising not to increase the efficiency of photovoltaic cells, but to amplify the incident solar energy since the output power of photocell is almost directly proportional to the incident solar energy. There are 2 ways to do this: to orient the solar panel on the sun by using a solar tracker or to concentrate solar energy by using a solar concentrator. Solar concentrator is a device that allows to collect solar energy from a larger area and direct it to a smaller area. Now solar concentrators are mainly represented by parabolic mirrors and Fresnel lenses. There are also other various mirror systems with different degree of concentration, but they are not widely used due to various weighty drawbacks. Parabolic mirrors are very large and heavy because of their design, which does not allow to make them smaller. Hence the system is subjected to an increased risk of breakage. The mirrors also require very precise orientation to the sun and powerful cooling systems, otherwise their efficiency is extremely reduced. Fresnel lenses have a smaller, but still substantial thickness, and also require more precise orientation and more powerful cooling. Moreover they are quite expensive. In the present work a unique acrylic solar concentrator that solves the problems mentioned above is proposed. 39

Physical Basis of Power Transmission Wire’s Deicing by Electrodynamic Method

In this paper a new method of power transmission wire’s deicing is described. Deicing process is divided into three independent sub-processes, namely the process of melting the thin inner layer of ice cover, the process of ice cylinder fracturing into components due to bending deformations; the process of shaking off the fractured ice cylinder elements by inertial forces. Mathematical description of each sub-process is shown

ENERGY-EFFICIENT PHOTOVOLTAIC INSTALLATION

In this paper R&D basics for photovoltaic installation development are presented. Efficiency of energy conversion process depending on the azimuth and zenith angles of the installation\u27s rotation is investigated. Recommendations on the installations\u27 class design are given. Technical and economic assessments of the proposed solutions are made

Learning outcomes evaluation based on mixed diagnostic tests and cognitive graphic tools

In this paper, we discuss the relevance of students’ learning outcomes evaluation using computer-based testing. The learning process is based on mixed diagnostic tests. For the purpose of evaluation, we use the threshold, fuzzy logic and cognitive graphic tools. The construction of mixed diagnostic tests, representing a compromise between unconditional and conditional components, in order to develop students’ knowledge evaluation is proposed for a number of disciplines. We suggest a technique for optimal mixed diagnostic tests construction based on the expert knowledge of the subjects for effective learning. The developed approach is used for a number of both the humanities and technical disciplines. One of useful outcomes of mixed diagnostic tests application is the learning trajectory design for each individual. We construct students’ learning trajectory using the intelligent learning and testing system and suggest defining their inherent approach to the learning process within the problem area

Learning outcomes evaluation based on mixed diagnostic tests and cognitive graphic tools

In this paper, we discuss the relevance of students’ learning outcomes evaluation using computer-based testing. The learning process is based on mixed diagnostic tests. For the purpose of evaluation, we use the threshold, fuzzy logic and cognitive graphic tools. The construction of mixed diagnostic tests, representing a compromise between unconditional and conditional components, in order to develop students’ knowledge evaluation is proposed for a number of disciplines. We suggest a technique for optimal mixed diagnostic tests construction based on the expert knowledge of the subjects for effective learning. The developed approach is used for a number of both the humanities and technical disciplines. One of useful outcomes of mixed diagnostic tests application is the learning trajectory design for each individual. We construct students’ learning trajectory using the intelligent learning and testing system and suggest defining their inherent approach to the learning process within the problem area