The aim of this paper is to present a new method for flight flutter modal parameter identification in noisy environment. This method employs a time-frequency （TF） filter to reduce the noise before identification, wh...The aim of this paper is to present a new method for flight flutter modal parameter identification in noisy environment. This method employs a time-frequency （TF） filter to reduce the noise before identification, which depends on the localization property of sweep excitation in TF domain. Then, a generalized total least square （GTLS） identification algorithm based on stochastic framework is applied to the enhanced data. System identification with noisy data is transformed into a generalized total least square problem, and the solution is carried out by the generalized singular value decomposition （GSVD） to avoid the intensive nonlinear optimization computation. A nearly maximum likelihood property can be achieved by ＇optimally＇ weighted generalized total least square. Finally, the efficiency of the method is illustrated by means of flight test data.展开更多
天然气合成油(gas to liquid,GTL)以天然气为原料,具备优良的环保性能和电气性能,可用作新型变压器绝缘油。为更好地了解GTL绝缘油的产气规律,文中基于分子动力学仿真,构建GTL绝缘油微观体系,模拟其在电热联合故障下的分解过程。结合仿...天然气合成油(gas to liquid,GTL)以天然气为原料,具备优良的环保性能和电气性能,可用作新型变压器绝缘油。为更好地了解GTL绝缘油的产气规律,文中基于分子动力学仿真,构建GTL绝缘油微观体系,模拟其在电热联合故障下的分解过程。结合仿真结果,分析GTL绝缘油分解产物的种类和数量的变化趋势,并通过同位素标记法得到其产气路径和机理。仿真结果表明:GTL绝缘油分解的最终产物为C_(2)H_(4)、C_(2)H_(2)、CH_(4)、H_(2)、C_(2)H_(6)等小分子气体和自由基;随着故障温度的升高,GTL绝缘油的分解愈发充分;电热联合故障下,温度是影响GTL绝缘油分解的主要因素,强电场的存在会加速其分解;在相同故障条件下,GTL绝缘油分解产生的H_(2)和CH_(4)占比更高,相比传统矿物油提高了5%左右。文中研究成果将为GTL绝缘油变压器的故障诊断与状态评估提供理论支撑与参考。展开更多
文摘The aim of this paper is to present a new method for flight flutter modal parameter identification in noisy environment. This method employs a time-frequency （TF） filter to reduce the noise before identification, which depends on the localization property of sweep excitation in TF domain. Then, a generalized total least square （GTLS） identification algorithm based on stochastic framework is applied to the enhanced data. System identification with noisy data is transformed into a generalized total least square problem, and the solution is carried out by the generalized singular value decomposition （GSVD） to avoid the intensive nonlinear optimization computation. A nearly maximum likelihood property can be achieved by ＇optimally＇ weighted generalized total least square. Finally, the efficiency of the method is illustrated by means of flight test data.
文摘天然气合成油(gas to liquid,GTL)以天然气为原料,具备优良的环保性能和电气性能,可用作新型变压器绝缘油。为更好地了解GTL绝缘油的产气规律,文中基于分子动力学仿真,构建GTL绝缘油微观体系,模拟其在电热联合故障下的分解过程。结合仿真结果,分析GTL绝缘油分解产物的种类和数量的变化趋势,并通过同位素标记法得到其产气路径和机理。仿真结果表明:GTL绝缘油分解的最终产物为C_(2)H_(4)、C_(2)H_(2)、CH_(4)、H_(2)、C_(2)H_(6)等小分子气体和自由基;随着故障温度的升高,GTL绝缘油的分解愈发充分;电热联合故障下,温度是影响GTL绝缘油分解的主要因素,强电场的存在会加速其分解;在相同故障条件下,GTL绝缘油分解产生的H_(2)和CH_(4)占比更高,相比传统矿物油提高了5%左右。文中研究成果将为GTL绝缘油变压器的故障诊断与状态评估提供理论支撑与参考。
