Study on resembling simulation experiment of spontaneous combustion in goaf
To study the impact of different types of ventilation leakage on spontaneous combustion in goaf,and in accordance with the different states of ventilation leakage in goaf,the goaf is divided into different regions of the fire danger,in order to judge the location of spontaneous combustion in goaf.By developing the resembling simulation models,many experiments are carried out to research the spontaneous combustion in goaf.Then,the goaf ventilation pressure isoline and ventilation flow distribution are observed and drawn,which are also drawn after the air duct for gas releasing is placed in the upper corner of coal face and after the stowing strips are placed in goaf.
ABSTRACTWe utilize the Internet search data from Google Trends to provide short-term forecasts for the inflow of Japanese tourists to South Korea. We construct the Google variable in a systematic way by combining keywords to minimize mean squared or mean absolute forecasting errors. We augment the Google variable to the standard time-series forecasting models and compare their forecasting accuracies. We find that Google-augmented models perform much better than the standard time-series models in terms of short-term forecasting accuracy. In particular, Google models show better out-of-sample forecasting performance than in-sample forecasting.