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Geomagnetically induced currents through the transformer windings produce biases of transformers, increase transformer reactive power losses, and lead to a significant lack of reactive power support in the power system. As a result, the geomagnetically induced currents cause voltage fluctuations and affect the safe and stable operation of the power network. This study focuses on the problem of multi-objective reactive power optimization strategy to mitigate the negative effects of geomagnetically induced current on the power network. Using the stochastic response surface method, this article establishes a model of the probabilistic power flow calculation, combines a particle swarm optimization algorithm based on the niche chaotic mutation, and sets up a multi-objective reactive power optimization model. The introducing of chaos mutation avoids the result falling into a local optimal solution and improves the global search ability. The geomagnetically induced current–benchmark simulation verified the accuracy and effectiveness of the model and algorithm, and proved that the strategy can effectively reduce the voltage deviation caused by the geomagnetically induced current.

A heat pump is a kind of energy saving equipment. It can effectively improve the grade of low temperature renewable and waste energy. Because of the increasing demands for higher temperature energy in many industrial processes and other fields, the development and research of high temperature heat pumps have been becoming more and more pressing and significant. This paper briefly summarizes the development status in two aspects: the development of working fluids and system features and characteristics of different cycle types.

This paper analyzes the current mainstream open-source Open Stack cloud platform resource scheduling mechanism, and proposes an extensible resource optimization scheduling framework based on Open Stack. The framework divides the physical hyper visor host into multiple logical resource pools. It not only can configure global resources optimization strategy for individual resource pool, but also specify local resources optimization strategies for each resource pool. The results show that the multi-resource pool resource optimization scheduling optimization framework proposed in this article is good for Open Stack resource optimization, performance isolation and security isolation, and has a good extension.

Thermal characteristics of AlGaInP thin-film LED with transparent conducting ITO p-type contact by electrical method are presented and discussed. Samples without ITO fabricated from the same AlGaInP /GaAs epitaxial material are also prepared as references. The temperature coefficients of the samples are measured firstly and they are used as temperature sensitive parameters to determine the temperature rise. Heating response curves show that the temperature of chip in the sample with ITO is about 9K lower than the sample without ITO when the time of applying 60mA operation current exceeds 105µs. It can be also calculated that thermal resistance(from chip to ambient condition) of the sample with ITO is about 40K/W lower than the one without ITO. Finally we make the conclusion that the ITO layer is helpful for the thermal management of LED and it can improve the reliability the AlGaInP thin-film LED effectively.