Hydraulic system has a critical and important role in drilling machines.Any failure in this system leads to problems in power system and machine operation.Since the failure cannot be prevented entirely,it is important...Hydraulic system has a critical and important role in drilling machines.Any failure in this system leads to problems in power system and machine operation.Since the failure cannot be prevented entirely,it is important to minimize its probability.Reliability is one of the most effcient and important method to study safe operation probability of hydraulic systems.In this research,the reliability of hydraulic system of four rotary drilling machines in Sarcheshmeh Copper Mine in Iran has been analyzed.The data analysis shows that the time between failures(TBF)of Machines A and C obey the Weibull(2P)and Weibull(3P)distribution,respectively.Also,the TBF of Machines B and D obey the lognormal distribution.With regard to reliability plots of hydraulic systems,preventive reliability-based maintenance time intervals for 80%reliability levels for machines in this system are 10 h.展开更多
Sequential Monte Carlo simulation method is introduced to the reliability assessment of microgrid,and a Weibull distribution wind speed model is built to simulate the hourly wind speed of a specific site.Wind turbine ...Sequential Monte Carlo simulation method is introduced to the reliability assessment of microgrid,and a Weibull distribution wind speed model is built to simulate the hourly wind speed of a specific site.Wind turbine generator model combined with a two-state reliability model is applied to Monte Carlo simulation method,and results show that the wind turbine reliability model works well with sequential Monte Carlo simulation.A two-state reliability model of micro gas turbine and a load model from IEEE reliability test system （IEEE RTS） are also introduced to the reliability evaluation of microgrid.Case studies show that Monte Carlo simulation method is flexible and efficient dealing with microgrid consisting of renewable resources with fluctuation characteristics.展开更多
In recent years, a new kind of drilling fluid system with unique structure micro-foam has been developed. Compared with other drilling fluid systems, it possesses many advantages. And it has been successfully applied ...In recent years, a new kind of drilling fluid system with unique structure micro-foam has been developed. Compared with other drilling fluid systems, it possesses many advantages. And it has been successfully applied in hundreds of wells to drill depleted reservoirs in the world wide. The geological structure is very complex in Haita area, it is difficult to achieve the requirement of increasing drilling rate by conventional drilling methods, even can’t make footage. The micro-foam drilling fluid can apply to Haita area, and solve the drilling problems commendably, which is comprehended by studying the structure and plugging, prevent caving, speed mechanism of the micro-foam drilling fluid. Field practice indicates that micro-foam drilling fluid technology can resolve the drilling problem effectively in Haita basin. It has the extremely vital significance to improve drilling speed, discover and protect reservoir stratum, decrease the risk of circulation loss and save the drilling cost.展开更多
The on board computer system for a small satellite is required to be high in reliability, light in weight, small in volume and low in power consumption. This paper describes the on board computer system with the advan...The on board computer system for a small satellite is required to be high in reliability, light in weight, small in volume and low in power consumption. This paper describes the on board computer system with the advantages of both centralized and distributed systems, analyzes its reliability, and briefs the key techniques used to improve its reliability.展开更多
基金the R&D center of Iranian National Copper Company for its financial support
文摘Hydraulic system has a critical and important role in drilling machines.Any failure in this system leads to problems in power system and machine operation.Since the failure cannot be prevented entirely,it is important to minimize its probability.Reliability is one of the most effcient and important method to study safe operation probability of hydraulic systems.In this research,the reliability of hydraulic system of four rotary drilling machines in Sarcheshmeh Copper Mine in Iran has been analyzed.The data analysis shows that the time between failures(TBF)of Machines A and C obey the Weibull(2P)and Weibull(3P)distribution,respectively.Also,the TBF of Machines B and D obey the lognormal distribution.With regard to reliability plots of hydraulic systems,preventive reliability-based maintenance time intervals for 80%reliability levels for machines in this system are 10 h.
文摘Sequential Monte Carlo simulation method is introduced to the reliability assessment of microgrid,and a Weibull distribution wind speed model is built to simulate the hourly wind speed of a specific site.Wind turbine generator model combined with a two-state reliability model is applied to Monte Carlo simulation method,and results show that the wind turbine reliability model works well with sequential Monte Carlo simulation.A two-state reliability model of micro gas turbine and a load model from IEEE reliability test system （IEEE RTS） are also introduced to the reliability evaluation of microgrid.Case studies show that Monte Carlo simulation method is flexible and efficient dealing with microgrid consisting of renewable resources with fluctuation characteristics.
文摘In recent years, a new kind of drilling fluid system with unique structure micro-foam has been developed. Compared with other drilling fluid systems, it possesses many advantages. And it has been successfully applied in hundreds of wells to drill depleted reservoirs in the world wide. The geological structure is very complex in Haita area, it is difficult to achieve the requirement of increasing drilling rate by conventional drilling methods, even can’t make footage. The micro-foam drilling fluid can apply to Haita area, and solve the drilling problems commendably, which is comprehended by studying the structure and plugging, prevent caving, speed mechanism of the micro-foam drilling fluid. Field practice indicates that micro-foam drilling fluid technology can resolve the drilling problem effectively in Haita basin. It has the extremely vital significance to improve drilling speed, discover and protect reservoir stratum, decrease the risk of circulation loss and save the drilling cost.
文摘The on board computer system for a small satellite is required to be high in reliability, light in weight, small in volume and low in power consumption. This paper describes the on board computer system with the advantages of both centralized and distributed systems, analyzes its reliability, and briefs the key techniques used to improve its reliability.
