Pressure distribution is important information for engineers during an aerodynamic design process. Pressure Distribution Oriented(PDO) optimization design has been proposed to introduce pressure distribution manipulat...Pressure distribution is important information for engineers during an aerodynamic design process. Pressure Distribution Oriented(PDO) optimization design has been proposed to introduce pressure distribution manipulation into traditional performance dominated optimization.In previous PDO approaches, constraints or manual manipulation have been used to obtain a desirable pressure distribution. In the present paper, a new Pressure Distribution Guided(PDG) method is developed to enable better pressure distribution manipulation while maintaining optimization efficiency. Based on the RBF-Assisted Differential Evolution(RADE) algorithm, a surrogate model is built for target pressure distribution features. By introducing individuals suggested by suboptimization on the surrogate model into the population, the direction of optimal searching can be guided. Pressure distribution expectation and aerodynamic performance improvement can be achieved at the same time. The improvements of the PDG method are illustrated by comparing its design results and efficiency on airfoil optimization test cases with those obtained using other methods. Then the PDG method is applied on a dual-aisle airplane’s inner-board wing design. A total drag reduction of 8 drag counts is achieved.展开更多
在配电网进行负荷转移或者线路检修时,传统方法是采用停电转供电的方式进行,随着社会经济发展及居民生活质量的提高,用户对电力供应的可靠性和不间断性的要求越来越高,现如今这种负荷转供方法已经不能满足用户需要。为此,需要采用合环...在配电网进行负荷转移或者线路检修时,传统方法是采用停电转供电的方式进行,随着社会经济发展及居民生活质量的提高,用户对电力供应的可靠性和不间断性的要求越来越高,现如今这种负荷转供方法已经不能满足用户需要。为此,需要采用合环操作的方法来实现不停电负荷转移,该文主要对10 k V配网合环转电的意义、操作条件、影响因素及风险管控的影响进行分析研究,以期能够为相关电力工作者提供借鉴和帮助。展开更多
Physical and mathematical models as well as calculation methods of nitrogen bed on porous media have been introduced to evaluate the structural parameters of mesoporous materials. Kelvin＇s equation is a link between ...Physical and mathematical models as well as calculation methods of nitrogen bed on porous media have been introduced to evaluate the structural parameters of mesoporous materials. Kelvin＇s equation is a link between the relative adsorbate pressure, the mean pore radius, and pore capillarity on the basis of macroscopic capillary condensation. However, Kelvin＇s equation has been identified that it underestimates the calculated pore size of a material especially in the boundary of pore size which is between 2 and 4 nm.Various modifications on Kelvin＇s equation were mentioned in order to develop a new model to improve the accuracy of pore size calculation. The problems on conventional mathematical models were analyzed and discussed. A number of calculation methods on physisorption and pore size, especially fundamental theories of physisorption, basis of models and their deficiencies are reviewed. It can provide guidance on developing a modified Kelvin＇s equation for pore size calculation.展开更多
基金co-supported by the National Key Basic Research Program of China(No.2014CB744806)Tsinghua University Initiative Scientific Research Program(No.2015Z22003)
文摘Pressure distribution is important information for engineers during an aerodynamic design process. Pressure Distribution Oriented(PDO) optimization design has been proposed to introduce pressure distribution manipulation into traditional performance dominated optimization.In previous PDO approaches, constraints or manual manipulation have been used to obtain a desirable pressure distribution. In the present paper, a new Pressure Distribution Guided(PDG) method is developed to enable better pressure distribution manipulation while maintaining optimization efficiency. Based on the RBF-Assisted Differential Evolution(RADE) algorithm, a surrogate model is built for target pressure distribution features. By introducing individuals suggested by suboptimization on the surrogate model into the population, the direction of optimal searching can be guided. Pressure distribution expectation and aerodynamic performance improvement can be achieved at the same time. The improvements of the PDG method are illustrated by comparing its design results and efficiency on airfoil optimization test cases with those obtained using other methods. Then the PDG method is applied on a dual-aisle airplane’s inner-board wing design. A total drag reduction of 8 drag counts is achieved.
文摘在配电网进行负荷转移或者线路检修时,传统方法是采用停电转供电的方式进行,随着社会经济发展及居民生活质量的提高,用户对电力供应的可靠性和不间断性的要求越来越高,现如今这种负荷转供方法已经不能满足用户需要。为此,需要采用合环操作的方法来实现不停电负荷转移,该文主要对10 k V配网合环转电的意义、操作条件、影响因素及风险管控的影响进行分析研究,以期能够为相关电力工作者提供借鉴和帮助。
文摘Physical and mathematical models as well as calculation methods of nitrogen bed on porous media have been introduced to evaluate the structural parameters of mesoporous materials. Kelvin＇s equation is a link between the relative adsorbate pressure, the mean pore radius, and pore capillarity on the basis of macroscopic capillary condensation. However, Kelvin＇s equation has been identified that it underestimates the calculated pore size of a material especially in the boundary of pore size which is between 2 and 4 nm.Various modifications on Kelvin＇s equation were mentioned in order to develop a new model to improve the accuracy of pore size calculation. The problems on conventional mathematical models were analyzed and discussed. A number of calculation methods on physisorption and pore size, especially fundamental theories of physisorption, basis of models and their deficiencies are reviewed. It can provide guidance on developing a modified Kelvin＇s equation for pore size calculation.
