The oscillatory behavior of neutral differential equation with positive and negative coefficients is investigated by mathematics analysis technique and the fixed point principle. Some sufficient conditions for oscilla...The oscillatory behavior of neutral differential equation with positive and negative coefficients is investigated by mathematics analysis technique and the fixed point principle. Some sufficient conditions for oscillation of neutral differential equation with positive and negative coefficients are obtained.展开更多
Single-phase low current grounding faults areoften seen in power distribution system of coal mines.These faults are difficult to reliably identify.We propose a new method of single-phase ground fault protection based ...Single-phase low current grounding faults areoften seen in power distribution system of coal mines.These faults are difficult to reliably identify.We propose a new method of single-phase ground fault protection based upon a discernible matrix of the fractal dimension associated with line currents.The method builds on existing selective protection methods.Faulted feeders are distinguished using differences in the zero-sequence transient current fractal dimension.The current signals were first processed through a fast Fourier transform and then the characteristics of a faulted line were identified using a discernible matrix.The method of calculation is illustrated.The results show that the method involves simple calculations, is easy to do and is highly accurate.It is, therefore, suitable for distribution networks having different neutral grounding modes.展开更多
Grounded ship faces up exceptionally different stability forces unlike in her normal operating condition. This critical situation must be corrected as soon as can minimize hull stress, the risk of pollution and stabil...Grounded ship faces up exceptionally different stability forces unlike in her normal operating condition. This critical situation must be corrected as soon as can minimize hull stress, the risk of pollution and stability failure. Re-floating the ship need full understanding of the impact of ground reaction （R） on the ship buoyancy and stability. Re-floating the ship has different phases and there are several immediate actions that should be taken by ship＇s crew; one of these phases is re-calculation of ship stability conditions. In this paper, a guide to understanding the effect of the ground reaction （R）, determines the amount of ground pressure and its location. With consideration of the seabed form whether symmetric of asymmetric. Calculating the magnitude of the ground reaction （R） using different applicable methods, explaining the effect of using weight to re-float the ship by her own means, focusing on GM calculation after grounding.展开更多
文摘The oscillatory behavior of neutral differential equation with positive and negative coefficients is investigated by mathematics analysis technique and the fixed point principle. Some sufficient conditions for oscillation of neutral differential equation with positive and negative coefficients are obtained.
基金Project 50504015 supported by the National Natural Science Foundation of Chinathe Youth Science and Technology Research Program of China University of Mining and Technology (0C060996)
文摘Single-phase low current grounding faults areoften seen in power distribution system of coal mines.These faults are difficult to reliably identify.We propose a new method of single-phase ground fault protection based upon a discernible matrix of the fractal dimension associated with line currents.The method builds on existing selective protection methods.Faulted feeders are distinguished using differences in the zero-sequence transient current fractal dimension.The current signals were first processed through a fast Fourier transform and then the characteristics of a faulted line were identified using a discernible matrix.The method of calculation is illustrated.The results show that the method involves simple calculations, is easy to do and is highly accurate.It is, therefore, suitable for distribution networks having different neutral grounding modes.
文摘Grounded ship faces up exceptionally different stability forces unlike in her normal operating condition. This critical situation must be corrected as soon as can minimize hull stress, the risk of pollution and stability failure. Re-floating the ship need full understanding of the impact of ground reaction （R） on the ship buoyancy and stability. Re-floating the ship has different phases and there are several immediate actions that should be taken by ship＇s crew; one of these phases is re-calculation of ship stability conditions. In this paper, a guide to understanding the effect of the ground reaction （R）, determines the amount of ground pressure and its location. With consideration of the seabed form whether symmetric of asymmetric. Calculating the magnitude of the ground reaction （R） using different applicable methods, explaining the effect of using weight to re-float the ship by her own means, focusing on GM calculation after grounding.
