In this paper, a method to detect a decrease in the output power of photovoltaic systems is proposed. This method is based on using satellite irradiance data. In addition, fault detection is carried out with only one day's data in this method. Thus, the time elapses since the decrease in output is shorter than with the other methods. In order to mitigate the error in satellite data and improve the accuracy of fault detection, data extraction is carried out, which consists of two steps. In the first step, effective data are extracted by setting a lower irradiance limit. In the second step, "Calculation day" is determined depending on the number of effective data in one day. Fault detection, which is only conducted on the Calculation day, is conducted by comparing the expected power and the measured power. The parameters used in this study were optimized by testing 45 systems that appear normal. Subsequently, 340 systems were analyzed with the proposed method, using optimized parameters. The results showed the effectiveness of our method from the viewpoints of both accuracy and time required. In addition, three data extraction methods were considered to distinguish between the permanent decrease caused by failure, and the temporary decrease caused by partial shade. Fuzzy cluster analysis showed the best result among the three methods used.
This study discusses current state of medical service and issues for reconstruction of medical care provision system in 12 municipalities affected nuclear disaster in Fukushima. It clarifies that (1) the number of medical facilities and medical staffs is decreasing significantly, (2) the number of patients is decreasing, (3) most of the managers of medical facilities faces with problems concerning securement of profitability and medical staffs, (4) most of the managers of medical facilities point out the necessity of financial support system for continuation of medical service and securement of medical staffs. This study concludes that it is important to promote reconstruction of the medical care provision system while considering population structure and regional structure in the future.
The Fukushima Daiichi Nuclear Power Plant Accident caused by the Great East Japan Earthquake of March 11, 2011 resulted in serious radiation damage in Fukushima Prefecture. Although evacuation orders were enforced in 11 municipalities, they were lifted by April 1, 2017 with the exception of "difficult-to-return zone" in 9 of them. This study aims to analyze population and household trends, restoration situation of the living environment, and living conditions of residents in the town center of Namie Town as of September 2018, that is, approximately one and a half years after evacuation orders caused by the Fukushima Daiichi Nuclear Power Plant Accident were lifted, based on the official judgement that the living environment had been restored since decontamination and restoration of infrastructure were completed. This study clarifies that the living environment has not been restored to the extent that most disaster victims are able to choose returning, and that returnees are still disaster victims in that they are living in the environment with hardship. This study concludes that it is necessary to shift to Fukushima revitalization policies based on the actual conditions of disaster victims and affected areas.
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