Risk precontrol management system of coal mines safety( RPMSCS) provides a set of preventive safety management strategy for high-risk coal industries, which has captured extensive attentions. Fundamentally,there are s...Risk precontrol management system of coal mines safety( RPMSCS) provides a set of preventive safety management strategy for high-risk coal industries, which has captured extensive attentions. Fundamentally,there are several membership systems with subsystems in the management system, and the subsystem reliability has an important influence on the management system performance. Through analyzing the structure characteristics of the management system,the phase type distribution was employed to analyze its subsystem reliability by considering repair process and three states including working,fail-abnormal,and fail-emergency states. The reliability indices of the subsystem were derived respectively,including the probabilities that the subsystem in three states,mean time to the first failure, mean time to first failemergency,mean working time to first fail-emergency,and mean maintenance time to the first fail-emergency, are derived respectively. The probabilities of the membership systems and the management system in three states were also derived. Some numerical examples were used to show the procedures. The result is important for better understanding the management system operation and improving its operational performance from the respect of system reliability.展开更多
The Tension Leg Platform(TLP)is a hybrid,compliant platform designed to sustain springing and ringing responses that are correlated to short-period motion.Since the period of short-period motion is within the wave ene...The Tension Leg Platform(TLP)is a hybrid,compliant platform designed to sustain springing and ringing responses that are correlated to short-period motion.Since the period of short-period motion is within the wave energy concentration region,TLPs may experience sensitive short-period motion,such as resonance and green water,that usually cause serious damage to TLPs.In this study,a precontrol methodology is presented as a solution to prevent TLP-sensitive short-period motion.By applying the precontrol methodology,the parameters of TLP can be predetermined,allowing TLP motion performance to meet the requirements of short-period motion before sensitive motions actually occur.For example,the damping coefficient should be less than 4.3,the tendons’stiffness should be larger than 0.91×10^(8),and the dimensionless draft should be less than 0.665.The development of a precontrol methodology is based on a solid theoretical foundation.First,a series of simple and high-fidelity numerical models are proposed to simulate the natural period of roll,natural period of heave,and green water height.Second,a constraint regime is generated based on the numerical models and the sensitive motion range of short-period motion.The constraint regime is divided into two parts:the control range(corresponding to sensitive shortperiod motion)and the feasible range(the complementary set of control ranges in the whole parameter constraint domain).Finally,TLP parameters are derived from the calculated feasible range.The precontrol methodology goes beyond the conventional approach of real-time control by changing the control from a remedial action to a preventive action.展开更多
为提高地区电网的电压无功调节能力,构建了以实时电压无功优化控制为主,以各供电区域校正控制为备用的自动电压控制(Automatic Voltage Control,AVC)体系。提出了基于负荷预测的预先控制方案,根据负荷预测结果自动划分负荷变化趋势,并...为提高地区电网的电压无功调节能力,构建了以实时电压无功优化控制为主,以各供电区域校正控制为备用的自动电压控制(Automatic Voltage Control,AVC)体系。提出了基于负荷预测的预先控制方案,根据负荷预测结果自动划分负荷变化趋势,并结合负荷变化趋势确定无功设备的调节方向。福州电网的闭环运行结果表明,该方案可有效提高电压和功率因数的合格率,避免无功设备的频繁调节。展开更多
文摘Risk precontrol management system of coal mines safety( RPMSCS) provides a set of preventive safety management strategy for high-risk coal industries, which has captured extensive attentions. Fundamentally,there are several membership systems with subsystems in the management system, and the subsystem reliability has an important influence on the management system performance. Through analyzing the structure characteristics of the management system,the phase type distribution was employed to analyze its subsystem reliability by considering repair process and three states including working,fail-abnormal,and fail-emergency states. The reliability indices of the subsystem were derived respectively,including the probabilities that the subsystem in three states,mean time to the first failure, mean time to first failemergency,mean working time to first fail-emergency,and mean maintenance time to the first fail-emergency, are derived respectively. The probabilities of the membership systems and the management system in three states were also derived. Some numerical examples were used to show the procedures. The result is important for better understanding the management system operation and improving its operational performance from the respect of system reliability.
基金supported by Kuaisu-Fuchi Project(Grant No.80912020201)Qingnian Yingcai Qihang Program.
文摘The Tension Leg Platform(TLP)is a hybrid,compliant platform designed to sustain springing and ringing responses that are correlated to short-period motion.Since the period of short-period motion is within the wave energy concentration region,TLPs may experience sensitive short-period motion,such as resonance and green water,that usually cause serious damage to TLPs.In this study,a precontrol methodology is presented as a solution to prevent TLP-sensitive short-period motion.By applying the precontrol methodology,the parameters of TLP can be predetermined,allowing TLP motion performance to meet the requirements of short-period motion before sensitive motions actually occur.For example,the damping coefficient should be less than 4.3,the tendons’stiffness should be larger than 0.91×10^(8),and the dimensionless draft should be less than 0.665.The development of a precontrol methodology is based on a solid theoretical foundation.First,a series of simple and high-fidelity numerical models are proposed to simulate the natural period of roll,natural period of heave,and green water height.Second,a constraint regime is generated based on the numerical models and the sensitive motion range of short-period motion.The constraint regime is divided into two parts:the control range(corresponding to sensitive shortperiod motion)and the feasible range(the complementary set of control ranges in the whole parameter constraint domain).Finally,TLP parameters are derived from the calculated feasible range.The precontrol methodology goes beyond the conventional approach of real-time control by changing the control from a remedial action to a preventive action.
文摘为提高地区电网的电压无功调节能力,构建了以实时电压无功优化控制为主,以各供电区域校正控制为备用的自动电压控制(Automatic Voltage Control,AVC)体系。提出了基于负荷预测的预先控制方案,根据负荷预测结果自动划分负荷变化趋势,并结合负荷变化趋势确定无功设备的调节方向。福州电网的闭环运行结果表明,该方案可有效提高电压和功率因数的合格率,避免无功设备的频繁调节。
