One of the main concerns in Engineering nowadays is the development of aircrafts of low consumption and high performance. For this purpose, airfoils are studied and designed to have an elevated lift coefficient and a ...One of the main concerns in Engineering nowadays is the development of aircrafts of low consumption and high performance. For this purpose, airfoils are studied and designed to have an elevated lift coefficient and a low drag coefficient, thus generating a highly efficient airfoil. The higher the efficiency value is, the lower the aircraft fuel consumption will be; thus improving its performance. In this sense, this work aims to develop a tool for airfoil creation from some desired characteristics, such as the lift and drag coefficients and maximum efficiency rate, using an algorithm based on an ANN （artificial neural network）. In order to do so, a database of aerodynamic characteristics with a total of 300 airfoils was initially collected from the XFoil software. Then, through a routine implemented in the MATLAB software, network architectures of one, two, three and four modules were trained, using the back propagation algorithm and momentum. The cross-validation technique was applied to analyze the results, evaluating which network possesses the lowest value in RMS （root-mean-square） error. In this case, the best result obtained was from the two-module architecture with two hidden neuron layers. The airfoils developed by this network, in the regions with the lowest RMS, were compared to the same airfoils imported to XFoil. The presented work offers as a contribution, in relation to other works involving ANN applied to fluid mechanics, the development of airfoils from their aerodynamic characteristics.展开更多
算力网络(Computing Power Network,CPN)主要通过网络控制面板将资源信息分发,有机实现多维度、多资源的信息整合过程。在算力网络中,大量算力交易、网络订购业务也能相互关联起来并得以实现,形成相对统一的技术体系架构,满足多重类型...算力网络(Computing Power Network,CPN)主要通过网络控制面板将资源信息分发,有机实现多维度、多资源的信息整合过程。在算力网络中,大量算力交易、网络订购业务也能相互关联起来并得以实现,形成相对统一的技术体系架构,满足多重类型资源的优化分配。介绍了算力网络及其资源内涵,并就算力网络实现一体化服务的相关技术内容进行深层次分析,讨论算力网络交易系统的设计与实践具体技术过程。展开更多
现阶段,利用现代光纤通信技术完成同步数字体系(Synchronous Digital Hierarchy,SDH)架构自组网,有效解决信号交互不连续、数据共享效率低等问题,已经逐步应用于广播电视传输网建设。因此,从现代光纤通信系统的功能和技术特性出发,深入...现阶段,利用现代光纤通信技术完成同步数字体系(Synchronous Digital Hierarchy,SDH)架构自组网,有效解决信号交互不连续、数据共享效率低等问题,已经逐步应用于广播电视传输网建设。因此,从现代光纤通信系统的功能和技术特性出发,深入探析广播电视传输网设计原则和建设策略,提出一种新的远距离传输环网配置和通信模块搭建方案,并用模拟软件进行方案测试,结果验证了系统设计的有效性,具有一定的借鉴意义。展开更多
光伏系统接入配电网后,配电网供电模式发生变化,导致配电网部分继电保护设备不能正确动作。根据储能充放电原理,在光伏输出直流侧并入储能模块抑制光伏功率波动,确保配电网接受光伏功率保持恒定,进而提出适用于光伏接入配电网线路电流...光伏系统接入配电网后,配电网供电模式发生变化,导致配电网部分继电保护设备不能正确动作。根据储能充放电原理,在光伏输出直流侧并入储能模块抑制光伏功率波动,确保配电网接受光伏功率保持恒定,进而提出适用于光伏接入配电网线路电流保护的整定方法,该方法能够解决光伏接入点反向出口短路电流值大小随光伏输出功率波动的问题。在PSCAD/EMTDC中建立了储能型光伏接入10 k V配电网算例模型,通过仿真验证了该方法的正确性与有效性。展开更多
文摘One of the main concerns in Engineering nowadays is the development of aircrafts of low consumption and high performance. For this purpose, airfoils are studied and designed to have an elevated lift coefficient and a low drag coefficient, thus generating a highly efficient airfoil. The higher the efficiency value is, the lower the aircraft fuel consumption will be; thus improving its performance. In this sense, this work aims to develop a tool for airfoil creation from some desired characteristics, such as the lift and drag coefficients and maximum efficiency rate, using an algorithm based on an ANN （artificial neural network）. In order to do so, a database of aerodynamic characteristics with a total of 300 airfoils was initially collected from the XFoil software. Then, through a routine implemented in the MATLAB software, network architectures of one, two, three and four modules were trained, using the back propagation algorithm and momentum. The cross-validation technique was applied to analyze the results, evaluating which network possesses the lowest value in RMS （root-mean-square） error. In this case, the best result obtained was from the two-module architecture with two hidden neuron layers. The airfoils developed by this network, in the regions with the lowest RMS, were compared to the same airfoils imported to XFoil. The presented work offers as a contribution, in relation to other works involving ANN applied to fluid mechanics, the development of airfoils from their aerodynamic characteristics.
文摘算力网络(Computing Power Network,CPN)主要通过网络控制面板将资源信息分发,有机实现多维度、多资源的信息整合过程。在算力网络中,大量算力交易、网络订购业务也能相互关联起来并得以实现,形成相对统一的技术体系架构,满足多重类型资源的优化分配。介绍了算力网络及其资源内涵,并就算力网络实现一体化服务的相关技术内容进行深层次分析,讨论算力网络交易系统的设计与实践具体技术过程。
文摘现阶段,利用现代光纤通信技术完成同步数字体系(Synchronous Digital Hierarchy,SDH)架构自组网,有效解决信号交互不连续、数据共享效率低等问题,已经逐步应用于广播电视传输网建设。因此,从现代光纤通信系统的功能和技术特性出发,深入探析广播电视传输网设计原则和建设策略,提出一种新的远距离传输环网配置和通信模块搭建方案,并用模拟软件进行方案测试,结果验证了系统设计的有效性,具有一定的借鉴意义。
文摘光伏系统接入配电网后,配电网供电模式发生变化,导致配电网部分继电保护设备不能正确动作。根据储能充放电原理,在光伏输出直流侧并入储能模块抑制光伏功率波动,确保配电网接受光伏功率保持恒定,进而提出适用于光伏接入配电网线路电流保护的整定方法,该方法能够解决光伏接入点反向出口短路电流值大小随光伏输出功率波动的问题。在PSCAD/EMTDC中建立了储能型光伏接入10 k V配电网算例模型,通过仿真验证了该方法的正确性与有效性。
