The thermodynamic system consists of the entropy flow and entropy product.This paper is to define the entropy flow and to apply it to determinig the minimal work in air-exhausting processes.It is found that the minimu...The thermodynamic system consists of the entropy flow and entropy product.This paper is to define the entropy flow and to apply it to determinig the minimal work in air-exhausting processes.It is found that the minimum work depends only on the pressure at the negative-pressure space.展开更多
The path equation describing the minimum drag work first proposed by Pakdemirli is reconsidered （Pakdemirli, M. The drag work minimization path for a fly- ing object with altitude-dependent drag parameters. Proceedin...The path equation describing the minimum drag work first proposed by Pakdemirli is reconsidered （Pakdemirli, M. The drag work minimization path for a fly- ing object with altitude-dependent drag parameters. Proceedings of the Institution of Mechanical Engineers, Part C, Journal of Mechanical Engineering Science 223（5）, 1113- 1116 （2009））. The Lie group theory is applied to the general equation. The group classi- fication with respect to an altitude-dependent arbitrary function is presented. Using the symmetries, the group-invariant solutions are determined, and the reduction of order is performed by the canonical coordinates.展开更多
为了给500 k V带电作业用绝缘斗臂车的安全使用提供技术依据,通过试验研究确定了绝缘斗臂车带电作业的安全距离。首先结合实际线路和车辆,针对使用绝缘斗臂车在500 k V单回线路直线塔进行带电作业时的各典型工作位置的安全距离进行了1:...为了给500 k V带电作业用绝缘斗臂车的安全使用提供技术依据,通过试验研究确定了绝缘斗臂车带电作业的安全距离。首先结合实际线路和车辆,针对使用绝缘斗臂车在500 k V单回线路直线塔进行带电作业时的各典型工作位置的安全距离进行了1:1模拟工况的操作冲击放电试验研究。结果表明,作为大型导电悬浮体的工作斗降低了组合间隙的击穿电压约15%。依据试验结果,通过危险率计算分析确定了海拔1 000 m地区500 k V绝缘斗臂车带电作业的中相最小安全距离和组合间隙分别为3.8 m和4.7 m,边相最小安全距离和组合间隙分别为3.2 m和3.8 m。考虑到工作斗的长度和导线距塔身的间隙,当工作斗的位于导线和塔身的间隙之中时,安全距离和组合间隙难以满足要求。因此当使用绝缘斗臂车在500 k V直线杆塔上开展带电作业时,工作斗不应进入边相导线和杆塔之间以及中相塔窗。展开更多
文摘The thermodynamic system consists of the entropy flow and entropy product.This paper is to define the entropy flow and to apply it to determinig the minimal work in air-exhausting processes.It is found that the minimum work depends only on the pressure at the negative-pressure space.
文摘The path equation describing the minimum drag work first proposed by Pakdemirli is reconsidered （Pakdemirli, M. The drag work minimization path for a fly- ing object with altitude-dependent drag parameters. Proceedings of the Institution of Mechanical Engineers, Part C, Journal of Mechanical Engineering Science 223（5）, 1113- 1116 （2009））. The Lie group theory is applied to the general equation. The group classi- fication with respect to an altitude-dependent arbitrary function is presented. Using the symmetries, the group-invariant solutions are determined, and the reduction of order is performed by the canonical coordinates.
文摘为了给500 k V带电作业用绝缘斗臂车的安全使用提供技术依据,通过试验研究确定了绝缘斗臂车带电作业的安全距离。首先结合实际线路和车辆,针对使用绝缘斗臂车在500 k V单回线路直线塔进行带电作业时的各典型工作位置的安全距离进行了1:1模拟工况的操作冲击放电试验研究。结果表明,作为大型导电悬浮体的工作斗降低了组合间隙的击穿电压约15%。依据试验结果,通过危险率计算分析确定了海拔1 000 m地区500 k V绝缘斗臂车带电作业的中相最小安全距离和组合间隙分别为3.8 m和4.7 m,边相最小安全距离和组合间隙分别为3.2 m和3.8 m。考虑到工作斗的长度和导线距塔身的间隙,当工作斗的位于导线和塔身的间隙之中时,安全距离和组合间隙难以满足要求。因此当使用绝缘斗臂车在500 k V直线杆塔上开展带电作业时,工作斗不应进入边相导线和杆塔之间以及中相塔窗。
