The structure of rotating polytropes (second order)

In order to carry out a numerical study of the structure of rotationally distorted polytropes, the Monaghan and Roxburgh (1965) method is extended to include the second-order term in the perturbation parameter, .     

Explosive hydrogen-burning model of solar flares

A model of solar flare is proposed, taking into account the high temperature (10⁹K) produced by the shock wave generated by the hydromagnetic wave at the junction of sunspot and the area just outside it and subsequent explosive hydrogen burning, producing the desired 10^28–29 ergs of a solar flare.     

Copula-based risk evaluation of droughts across the Pearl River basin, China

Daily precipitation data for the period of 1960–2005 from 42 precipitation gauging stations in the Pearl River basin were analyzed using the Mann–Kendall trend test and copula functions. The standardized precipitation index method was used to define drought episodes. Primary and secondary return periods were also analyzed to evaluate drought risks in the Pearl River basin as a whole. Results indicated that: (1) in general, the drought tendency was not significant at a 95 % confidence level. However, significant drought trends could be found in November, December, and January and significant wetting trends in June and July. The drought severity and drought durations were not significant at most of the precipitation stations across the Pearl River basin; (2) in terms of drought risk, higher drought risk could be observed in the lower Pearl River basin and lower drought risk in the upper Pearl River basin. Higher risk of droughts of longer durations was always corresponding to the higher risk of droughts with higher drought severity, which poses an increasing challenge for drought management and water resources management. When drought episodes with higher drought severity occurred in the Pearl River basin, the regions covered by higher risk of drought events were larger, which may challenge the water supply in the lower Pearl River basin. As for secondary return periods, results of this study indicated that secondary return periods might provide a more robust evaluation of drought risk. This study should be of merit for water resources management in the Pearl River basin, particularly the lower Pearl River basin, and can also act as a case study for determining regional response to drought changes as a result of global climate changes.     

Consistent seasonal snow cover depth and duration variability over the Western Himalayas (WH)

Precipitation in solid form, i.e., snow, during winter season over the Western Himalayas (WH) leads to the build-up of seasonal snow cover. Seasonal snow cover build-up (snow cover depth and duration) largely depends on atmospheric variables such as temperature, precipitation, radiation, wind, etc. Integrated (combined) influence of atmospheric variables on seasonal snow cover gets reflected in terms of spatial and temporal variability in seasonal snow cover build-up pattern. Hence spatial and temporal variability of seasonal snow cover build-up can serve as a good indicator of climate change in high altitude mountainous regions like the WH. Consistent seasonal snow cover depth and duration, delay days and early melt days of consistent seasonal snow cover at 11 stations spread across different mountain ranges over the WH were analyzed. Mean, maximum and percentiles (25th, 50th, 75th, 90th and 95th) of consistent seasonal snow cover depth and duration show decline over the WH in the recent past 2–3 decades. Consistent seasonal snow cover is found to melt early and snow cover build-up pattern is found to show changes over the WH. Decline in consistent seasonal snow cover depth, duration and changing snow cover build-up pattern over the WH in recent decades indicate that WH has undergone considerable climate change and winter weather patterns are changing in the WH.     

Investigation of Cycle Time Segments of Dragline Operation in Surface Coal Mine: A Statistical Approach

Dragline is highly capital intensive equipment to procure, operate and maintain in any surface mining operation. Given this, every second of operation of this capital intensive equipment is absolutely important. Improvement of even a single second in the total cycle time has a tremendous bearing on the overall performance of this equipment. In this light, the present paper is an endeavour to critically analyze the cycle time of dragline operations in a major surface coal mine in India. Rigorous statistical analysis has been performed on individual cycle time segments, of complete dragline cycle. The segmental cycle times have been found to be statistically significant and appear to be best represented by lognormal, normal and beta distributions. Furthermore, the mean time of the statistical distribution for segmental cycle time of dragline has revealed the dependence of cycle time on cut geometry and depth. Results have been illustrated in the form of figures, graphs and tables.