This paper deals with the theory and calculation methods for compensation of the gradient in railway tunnels through theoretical analysis, numerical calculation, and statistic regression methods. On the basis of the p...This paper deals with the theory and calculation methods for compensation of the gradient in railway tunnels through theoretical analysis, numerical calculation, and statistic regression methods. On the basis of the principle that the resultant force is zero, the formula of the maximum calculated gradient was derived for the freight and passenger line and high-speed passenger special line. The formula of aerodynamic drag in tunnel is provided using the domestic and foreign relevant experimental investigations, and revised with modem train and engineering parameters. A calculation model of aerodynamic drag when the train goes through a single-tracked tunnel was built. Finally, the concept of maximum calculated gradient was adopted to revise the formula for compensation of the gradient in railway tunnels.展开更多
To ensure safe drilling with narrow pressure margins in deepwater, a new deepwater dual-gradient drilling method based on downhole separation was designed. A laboratory experiment was conducted to verify the effective...To ensure safe drilling with narrow pressure margins in deepwater, a new deepwater dual-gradient drilling method based on downhole separation was designed. A laboratory experiment was conducted to verify the effectiveness of downhole separation and the feasibility of realizing dual-gradient in wellbore. The calculation of dynamic wellbore pressure during drilling was conducted. Then, an optimization model for drilling parameters was established for this drilling method, including separator position, separation efficiency, injection volume fraction, density of drilling fluid, wellhead back pressure and displacement. The optimization of drilling parameters under different control parameters and different narrow safe pressure margins is analyzed by case study. The optimization results indicate that the wellbore pressure profile can be optimized to adapt to the narrow pressure margins and achieve greater drilling depth. By using the optimization model, a smaller bottom-hole pressure difference can be obtained, which can increase the rate of penetration(ROP) and protect reservoirs. The dynamic wellbore pressure has been kept within safe pressure margins during optimization process, effectively avoiding the complicated underground situations caused by improper wellbore pressure.展开更多
面向高维复杂的电力量测数据,现有攻击定位检测方法存在定位精度差的问题。为此该文提出一种基于最大信息系数-双层置信极端梯度提升树的电网虚假数据注入攻击定位检测方法。所提方法引入最大信息系数对量测数据进行特征选择,能够非线...面向高维复杂的电力量测数据,现有攻击定位检测方法存在定位精度差的问题。为此该文提出一种基于最大信息系数-双层置信极端梯度提升树的电网虚假数据注入攻击定位检测方法。所提方法引入最大信息系数对量测数据进行特征选择,能够非线性地衡量数据特征之间的关联性,且公平地根据一个特征变量中包含另一个特征变量的信息量来去除冗余特征,有效解决虚假数据注入攻击定位检测方法普遍面临的量测数据高维冗余问题;同时提出一种具有正反馈信息传递作用的双层置信极端梯度提升树来对各节点状态进行分类,通过结合电网拓扑关系学习标签相关性,从而有选择性地利用前序标签有效预测信息,来减少后续分类器学习到的前序标签预测信息中包含的错误,最终实现对受攻击位置的精确定位。在IEEE-14、IEEE-57节点系统上进行大量仿真,算例结果验证了所提方法的有效性,且相较于其他方法具有更高的准确率、精度、召回率、F1值和AUC(area under curve)值。展开更多
为确保光伏分压注水泵在各种油气管环境条件下都能以最大功率输出,保持油气田注水管网分压的稳定性,提出基于最大功率点跟踪(Maximum Power Point Tracking,MPPT)算法的油气田注水管网分压闭环控制方法。设计油气田注水管网分压技术,以...为确保光伏分压注水泵在各种油气管环境条件下都能以最大功率输出,保持油气田注水管网分压的稳定性,提出基于最大功率点跟踪(Maximum Power Point Tracking,MPPT)算法的油气田注水管网分压闭环控制方法。设计油气田注水管网分压技术,以光伏分压注水泵为基础,通过分压压力缸对管网来水做功,实现高低压井能量转换;分析光伏分压注水泵的电流环、电压环,利用最优梯度的MPPT算法令光伏分压注水泵持续处于最大功率点状态下,当光伏分压注水泵运行功率产生变化时,调节电流环输出、控制主开关管占比、调节光伏分压注水泵的输出功率;通过实时监测和调整PWM脉冲宽度调制信号占空比,实现光伏分压注水泵闭环控制,由此提高水泵的能量转换效率。实验表明,该方法可以有效使水泵运行稳定性得以增强,并实现油气田管网注水量的合理有效控制,且有效提升油气田注水管注水效率。展开更多
文摘This paper deals with the theory and calculation methods for compensation of the gradient in railway tunnels through theoretical analysis, numerical calculation, and statistic regression methods. On the basis of the principle that the resultant force is zero, the formula of the maximum calculated gradient was derived for the freight and passenger line and high-speed passenger special line. The formula of aerodynamic drag in tunnel is provided using the domestic and foreign relevant experimental investigations, and revised with modem train and engineering parameters. A calculation model of aerodynamic drag when the train goes through a single-tracked tunnel was built. Finally, the concept of maximum calculated gradient was adopted to revise the formula for compensation of the gradient in railway tunnels.
基金Supported by the Key Program of National Natural Science Foundation of China(51734010)
文摘To ensure safe drilling with narrow pressure margins in deepwater, a new deepwater dual-gradient drilling method based on downhole separation was designed. A laboratory experiment was conducted to verify the effectiveness of downhole separation and the feasibility of realizing dual-gradient in wellbore. The calculation of dynamic wellbore pressure during drilling was conducted. Then, an optimization model for drilling parameters was established for this drilling method, including separator position, separation efficiency, injection volume fraction, density of drilling fluid, wellhead back pressure and displacement. The optimization of drilling parameters under different control parameters and different narrow safe pressure margins is analyzed by case study. The optimization results indicate that the wellbore pressure profile can be optimized to adapt to the narrow pressure margins and achieve greater drilling depth. By using the optimization model, a smaller bottom-hole pressure difference can be obtained, which can increase the rate of penetration(ROP) and protect reservoirs. The dynamic wellbore pressure has been kept within safe pressure margins during optimization process, effectively avoiding the complicated underground situations caused by improper wellbore pressure.
文摘面向高维复杂的电力量测数据,现有攻击定位检测方法存在定位精度差的问题。为此该文提出一种基于最大信息系数-双层置信极端梯度提升树的电网虚假数据注入攻击定位检测方法。所提方法引入最大信息系数对量测数据进行特征选择,能够非线性地衡量数据特征之间的关联性,且公平地根据一个特征变量中包含另一个特征变量的信息量来去除冗余特征,有效解决虚假数据注入攻击定位检测方法普遍面临的量测数据高维冗余问题;同时提出一种具有正反馈信息传递作用的双层置信极端梯度提升树来对各节点状态进行分类,通过结合电网拓扑关系学习标签相关性,从而有选择性地利用前序标签有效预测信息,来减少后续分类器学习到的前序标签预测信息中包含的错误,最终实现对受攻击位置的精确定位。在IEEE-14、IEEE-57节点系统上进行大量仿真,算例结果验证了所提方法的有效性,且相较于其他方法具有更高的准确率、精度、召回率、F1值和AUC(area under curve)值。
文摘为确保光伏分压注水泵在各种油气管环境条件下都能以最大功率输出,保持油气田注水管网分压的稳定性,提出基于最大功率点跟踪(Maximum Power Point Tracking,MPPT)算法的油气田注水管网分压闭环控制方法。设计油气田注水管网分压技术,以光伏分压注水泵为基础,通过分压压力缸对管网来水做功,实现高低压井能量转换;分析光伏分压注水泵的电流环、电压环,利用最优梯度的MPPT算法令光伏分压注水泵持续处于最大功率点状态下,当光伏分压注水泵运行功率产生变化时,调节电流环输出、控制主开关管占比、调节光伏分压注水泵的输出功率;通过实时监测和调整PWM脉冲宽度调制信号占空比,实现光伏分压注水泵闭环控制,由此提高水泵的能量转换效率。实验表明,该方法可以有效使水泵运行稳定性得以增强,并实现油气田管网注水量的合理有效控制,且有效提升油气田注水管注水效率。
文摘地铁线路穿越山岭或跨江渡河时,适当提高正线最大坡度标准有利于减少建设成本、降低设计和施工难度.为了研究地铁正线40.0‰最大坡度取值的可行性,结合苏州市轨道交通8号线车线系统特点,采用理论分析、列车纵向动力学、车辆-线路系统动力学以及有限元等方法,从动车功率、列车起动与制动能力、故障列车救援、列车运行状态与动力特性、轨道力学特性等方面分析了地铁正线40.0‰最大坡度对行车特性的影响.研究结果表明:当采用4动2拖B2型车时,地铁正线最大坡度值可采用40.0‰;列车通过40.0‰大坡道地段时,行车安全性、平稳性、列车起动制动以及故障救援能力均能满足要求;钢轨所受最大应力仅为容许应力的37%,纵向最大位移值仅为0.443 mm.
