Abstract There were two calculation methods of network system reliability: stochastic simulation algorithm and the analytical method. This paper performed stochastic simulation to a certain system on the uncertainty of its reliability degree applying random simulation algorithm and, meanwhile to the probability density distribution, point estimation and confidence interval of the reliability, which has proved the validity of stochastic simulation algorithm... There were two calculation methods of network system reliability: stochastic simulation algorithm and the analytical method. This paper performed stochastic simulation to a certain system on the uncertainty of its reliability degree applying random simulation algorithm and, meanwhile to the probability density distribution, point estimation and confidence interval of the reliability, which has proved the validity of stochastic simulation algorithm when analyzing the reliability and uncertainty of network system. What’s more, the method was verified as capable of getting more information of the system. Read More Read Less

Abstract This study deduced a set of theory computational formula, and optimized and improved the heat-conductivity of vias in printed circuit board (PCB) of electrical power apparatus. We adopted numerical simulation and experimental measurement to verify the reliability of this formula. Through the theory computational formula, this paper studied the influence of aperture of vias, filled materials and thickness of copper... This study deduced a set of theory computational formula, and optimized and improved the heat-conductivity of vias in printed circuit board (PCB) of electrical power apparatus. We adopted numerical simulation and experimental measurement to verify the reliability of this formula. Through the theory computational formula, this paper studied the influence of aperture of vias, filled materials and thickness of copper plated on vias on thermal conductivity. Research result showed that 0.45mm was the optimal diameter of bore of vias; the conductivity had no obvious improvement when filling material was FR4 or Rogers, but if it was filled with texture of high thermal conductivity like soldering tine, the conductivity would improved a lot; the plating thickness of vias had greater influence on thermal conductivity. The adoption of three optimization scheme of vias recommended by the result could respectively improve 6.5%, 35% and 51% of thermal conductivity. Read More Read Less

Abstract The physical activities are helpful for the health of teenagers as it can strengthen constitution and bone health and lower risks of cardiovascular disease and metabolic disease. Actigraph sensor can more accurately evaluate energy expenditure of teenagers during physical activities. This study observes and researches energy expenditure indexes of human body in physical activities combining Actigraph sensor, in order to... The physical activities are helpful for the health of teenagers as it can strengthen constitution and bone health and lower risks of cardiovascular disease and metabolic disease. Actigraph sensor can more accurately evaluate energy expenditure of teenagers during physical activities. This study observes and researches energy expenditure indexes of human body in physical activities combining Actigraph sensor, in order to provide a basis for studying the relationship between physical activities and health. Read More Read Less