A kind of new type three-phase magnetism valve type controllable reactor is proposed in this article, its structure and the principle are introduced. The article carried the electromagnetism analysis on the new type magnetism valve type controllable reactor, and established the three-phase magnetism valve type controllable reactor two-dimensional simulation model with Ansoft electric-magnetic field analysis software. Simulation results verified the feasibility of adjusting the reactor reactance smoothly by adjusting the thyristor's triggering angle. Lastly, it made an analysis about three-phase magnetism valve type controllable reactor's electromagnetism field distribution.
Regions of Karst landscape cover an estimated 12 percent of the world’s land space. South China Karst has been successful in its application to enter the World Heritage List as a natural heritage approved by UNESCO’s World Heritage Committee in 2007. The heritage site includes the Shilin Karst of Yunnan, Libo Karst of Guizhou and Wulong Karst of Chongqing, covering a total area of 146,016 ha. The present paper offers an analytical comparison as seen from global perspectives, and reveals the outstanding universal value of the South China site while highlighting its heritage resources properties. In addition, the paper also points to some of the major problems, even possible geological disasters devastating the site, including overdue exploitation and rocky desertification. Then the analysis proceeds to put forth relevant conservation strategies, which includes establishment and implementation of scientific management mechanism as well as a disaster monitoring system so as to promote the sustainable development of this natural heritage site.
In recent years, natural disasters occur frequently all around the world. Earthquakes and other geological disasters not only are destructive but also lead to serious secondary disasters. In south China’s Sichuan Province, on May the 12th 2008, an earthquake struck Wenchuan area followed by avalanches, landslides and debris flows, threatening the very existence of the 5 world heritage sites, designated by UNESCO, and reducing them to a vulnerable state. In this paper a summary is presented to show the characteristics of the geological disasters such as short duration, strong chain reactions, clear patterns, etc. Based on geological principles and methods and with the application of GIS and fuzzy comprehensive evaluation method, the potential damage and threats will be evaluated and analyzed together with the experience of heritage restoration and protection. With the ample analysis, this present thesis attempts to provide theoretical and practical basis for heritage conservation and management of geological disaster areas.
Since the 21st century, the number of people aged 65 and above in China has been increasing year by year. The aging population has grown faster and faster, and the aging of the population has become increasingly prominent. In order to explore the development trend of the elderly population aged 65 years and over in Gansu Province, this paper uses the gray system metabolism GM (1,1) model to predict the population aged 65 and above in Gansu Province from 2016 to 2022. The results show that the elderly population in Gansu Province will continue to rise in the next few years. In order to effectively alleviate this problem, this paper proposes three suggestions to improve the social pension security system in Gansu Province, establish an industrial base for the elderly, and promote the "two-child" policy.
Research Methods and Data Processing
Research MethodsThis paper uses the grey system GM(1,1) model prediction method to predict and analyze the population aged 65 and above in Gansu Province from 2016 to 2022.Construction and Test of GM(1,1) Model. Build steps. The GM(1,1) model is the basis for the grey prediction. The two "1"s represent the first-order equation and one variable, respectively. The steps for building this model are as follows:The first step is to set the original array with m observations:
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