The national standard--Safety Specifications for Power Driven VehiclesOperating on Roads--is the most basic technical regulation for safety and technical management ofmotor vehicles in China. It is the safety and tech...The national standard--Safety Specifications for Power Driven VehiclesOperating on Roads--is the most basic technical regulation for safety and technical management ofmotor vehicles in China. It is the safety and technical basis for the Public Security TrafficControl Dept. to register new vehicles, periodic inspection of vehicles under operation andinspection of vehicles involved in traffic accidents. It is also one of the important technicalbases of our country for compulsory inspection of new vehicles on fi-nalization of its model,ex-works inspection of new vehicles and the inspection of imported motor vehicles. Since the formalcountrywide implementation of GB7258-1997 Safety Specifications for Power Driven Vehicles Operatingon Roads on Jan. 1, 1998, the standard has played a very active role in strengthening the operatingsafety management of motor vehicles, improving the operating safety level of motor vehicles, and insafeguarding road traffic safety, etc. However, along with the rapid and sustainable growth of ournational economy, the number of motor vehicles has increased rapidly, especially privately-ownedautomobiles, so that the incidence of road traffic accidents rises yearly and the road trafficsafety situation is becoming increasingly serious. Therefore, the General Administration of QualitySupervision, Inspection and Quarantine of the People's Republic of China (AQSIQ) and theStandardization Administration of China (SAC) have issued the revised standard GB725 8-2004 SafetySpecifications for Power Driven Vehicles Operating on Roads, which will be put into effect onOctober 1, 2004. The timely revision of this standard is very necessary for upgrading the safety andtechnical requirements for motor vehicles in China.展开更多
The reliability of the on-wing aircraft Auxiliary Power Unit(APU)decides the cost and the comfort of flight to a large degree.The most important function of APU is to help start main engines by providing compressed ai...The reliability of the on-wing aircraft Auxiliary Power Unit(APU)decides the cost and the comfort of flight to a large degree.The most important function of APU is to help start main engines by providing compressed air.Especially on the condition of sudden shutdown in the air,APU can offer additional thrust for landing.Therefore,its condition monitoring has drawn much attention from the academic and industrial field.Among the on-wing sensing data which can reflect its condition,Exhaust Gas Temperature(EGT)is one of the most important parameters.To ensure the reliability of EGT,one kind of data-driven anomaly detection framework for EGT sensing data is proposed based on the Gaussian Process Regression and Kernel Principal Component Analysis.The situations of one-dimensional and two-dimensional input data for EGT anomaly detection are considered,respectively.The cross-validation experiments are carried out by utilizing the real condition data of APU,which are provided by China Southern Airlines Company Limited Shenyang Maintenance Base.The anomalous stuck condition of EGT sensing data is also detected.Experimental results show that the proposed EGT sensing data anomaly detection method can achieve better performance of false positive ratio,false negative ratio and accuracy.展开更多
This paper presents a cascode configuration synchronous rectifier device based on silicon MOSFET and Schottky diode,which can replace traditional power diode directly.This structure has self-driven ability with simple...This paper presents a cascode configuration synchronous rectifier device based on silicon MOSFET and Schottky diode,which can replace traditional power diode directly.This structure has self-driven ability with simple external circuit,and the conduction characteristic is preferable to a power diode.Static characterization and switching behavior analysis of proposed structure are conducted in this paper.The switching process is illustrated in detail using real model which considers the parasitic inductances and the nonlinearity of junction capacitors.The real time internal voltage and current value during switching transition are deduced with the equivalent circuit.To validate the analysis,two voltage specification rectifiers are built.Finally,double-pulse test results and the practical design example verify the performance advantages of proposed structure.展开更多
The key and bottleneck of research on the tip-jet rotor compound helicopter lies in the power system. Computational Fluid Dynamics (CFD) was used to numerically simulate the gas generator and rotor inner passage of th...The key and bottleneck of research on the tip-jet rotor compound helicopter lies in the power system. Computational Fluid Dynamics (CFD) was used to numerically simulate the gas generator and rotor inner passage of the tip-jet rotor composite power system, studying the effects of intake mode, inner cavity structure, propellant components, and injection amount on the characteristics of the composite power system. The results show that when a single high-temperature exhaust gas enters, the gas generator outlet fluid is uneven and asymmetric;when two-way high-temperature exhaust gas enters, the outlet temperature of the gas generator with a tilted inlet is more uniform than that with a vertical inlet;adding an inner cavity improves the temperature and velocity distribution of the gas generator's internal flow field;increasing the energy of the propellant is beneficial for improving the available moment.展开更多
A novel direct-drive type wind power generation system based on hybrid excitation synchronous machine（HESM）is introduced in this paper.The generator is connected to an uncontrollable rectifier,and a fully controlled...A novel direct-drive type wind power generation system based on hybrid excitation synchronous machine（HESM）is introduced in this paper.The generator is connected to an uncontrollable rectifier,and a fully controlled voltage-sourceinverter is used to connect the system to utility grid.An intermediate DC bus exists between the rectifier and inverter.A new control strategy is proposed which achieves the maximum power point tracking（MPPT） with the control of excitation current of HESM and stabilizes the DC link voltage with the control of inverter output current simultaneously.Specially-designed buck circuit is used to control the excitation current of HESM,and grid voltage-oriented vector control strategy is employed to realize the decoupling of the inverter output power.Simulation results and experiment in 3 kW lab prototype show an excellent static and dynamic performance of the proposed system.展开更多
既有谐波源建模方法在应用于内部拓扑未知与机理不明场景时,难以有效兼顾谐波源的频域稳态特征与动态时变特征,致使所构建模型的准确性与鲁棒性难以提升。为此,该文提出一种基于时-频特征联合提取的谐波源数据驱动建模方法。首先,根据...既有谐波源建模方法在应用于内部拓扑未知与机理不明场景时,难以有效兼顾谐波源的频域稳态特征与动态时变特征,致使所构建模型的准确性与鲁棒性难以提升。为此,该文提出一种基于时-频特征联合提取的谐波源数据驱动建模方法。首先,根据谐波源历史电压电流的频域分量确定谐波源的主导谐波频次;其次,构建谐波源稳态电压时-频特征矩阵并对其进行伪彩色编码以实现特征升维;最后,将动态时变信号与稳态特征分量彩色图组合输入所构建的多重卷积神经网络(multiple convolutional neural network,MCNN)与双向长短时记忆网络(bi-directional long short term memory network,BiLSTM)组合模型,构建反映谐波源动态时变特征与频域稳态特征的电压-电流映射关系。经仿真与实测数据验证,相较于其他数据驱动建模方法,所提方法不仅在单一谐波源建模场景下具有明显的优势,在复杂多谐波源场景下也具备较高的准确率与较强的鲁棒性。展开更多
文摘The national standard--Safety Specifications for Power Driven VehiclesOperating on Roads--is the most basic technical regulation for safety and technical management ofmotor vehicles in China. It is the safety and technical basis for the Public Security TrafficControl Dept. to register new vehicles, periodic inspection of vehicles under operation andinspection of vehicles involved in traffic accidents. It is also one of the important technicalbases of our country for compulsory inspection of new vehicles on fi-nalization of its model,ex-works inspection of new vehicles and the inspection of imported motor vehicles. Since the formalcountrywide implementation of GB7258-1997 Safety Specifications for Power Driven Vehicles Operatingon Roads on Jan. 1, 1998, the standard has played a very active role in strengthening the operatingsafety management of motor vehicles, improving the operating safety level of motor vehicles, and insafeguarding road traffic safety, etc. However, along with the rapid and sustainable growth of ournational economy, the number of motor vehicles has increased rapidly, especially privately-ownedautomobiles, so that the incidence of road traffic accidents rises yearly and the road trafficsafety situation is becoming increasingly serious. Therefore, the General Administration of QualitySupervision, Inspection and Quarantine of the People's Republic of China (AQSIQ) and theStandardization Administration of China (SAC) have issued the revised standard GB725 8-2004 SafetySpecifications for Power Driven Vehicles Operating on Roads, which will be put into effect onOctober 1, 2004. The timely revision of this standard is very necessary for upgrading the safety andtechnical requirements for motor vehicles in China.
基金partially supported by the National Natural Science Foundation of China(No.61803121)China Postdoctoral Science Foundation(No.2019M651277).
文摘The reliability of the on-wing aircraft Auxiliary Power Unit(APU)decides the cost and the comfort of flight to a large degree.The most important function of APU is to help start main engines by providing compressed air.Especially on the condition of sudden shutdown in the air,APU can offer additional thrust for landing.Therefore,its condition monitoring has drawn much attention from the academic and industrial field.Among the on-wing sensing data which can reflect its condition,Exhaust Gas Temperature(EGT)is one of the most important parameters.To ensure the reliability of EGT,one kind of data-driven anomaly detection framework for EGT sensing data is proposed based on the Gaussian Process Regression and Kernel Principal Component Analysis.The situations of one-dimensional and two-dimensional input data for EGT anomaly detection are considered,respectively.The cross-validation experiments are carried out by utilizing the real condition data of APU,which are provided by China Southern Airlines Company Limited Shenyang Maintenance Base.The anomalous stuck condition of EGT sensing data is also detected.Experimental results show that the proposed EGT sensing data anomaly detection method can achieve better performance of false positive ratio,false negative ratio and accuracy.
基金supported in part by the National Natural Science Foundation of China (No.51777093)
文摘This paper presents a cascode configuration synchronous rectifier device based on silicon MOSFET and Schottky diode,which can replace traditional power diode directly.This structure has self-driven ability with simple external circuit,and the conduction characteristic is preferable to a power diode.Static characterization and switching behavior analysis of proposed structure are conducted in this paper.The switching process is illustrated in detail using real model which considers the parasitic inductances and the nonlinearity of junction capacitors.The real time internal voltage and current value during switching transition are deduced with the equivalent circuit.To validate the analysis,two voltage specification rectifiers are built.Finally,double-pulse test results and the practical design example verify the performance advantages of proposed structure.
文摘The key and bottleneck of research on the tip-jet rotor compound helicopter lies in the power system. Computational Fluid Dynamics (CFD) was used to numerically simulate the gas generator and rotor inner passage of the tip-jet rotor composite power system, studying the effects of intake mode, inner cavity structure, propellant components, and injection amount on the characteristics of the composite power system. The results show that when a single high-temperature exhaust gas enters, the gas generator outlet fluid is uneven and asymmetric;when two-way high-temperature exhaust gas enters, the outlet temperature of the gas generator with a tilted inlet is more uniform than that with a vertical inlet;adding an inner cavity improves the temperature and velocity distribution of the gas generator's internal flow field;increasing the energy of the propellant is beneficial for improving the available moment.
基金Project supported by Delta Power Electronic Science and Education Development (Grant No.DRES2007002)
文摘A novel direct-drive type wind power generation system based on hybrid excitation synchronous machine（HESM）is introduced in this paper.The generator is connected to an uncontrollable rectifier,and a fully controlled voltage-sourceinverter is used to connect the system to utility grid.An intermediate DC bus exists between the rectifier and inverter.A new control strategy is proposed which achieves the maximum power point tracking（MPPT） with the control of excitation current of HESM and stabilizes the DC link voltage with the control of inverter output current simultaneously.Specially-designed buck circuit is used to control the excitation current of HESM,and grid voltage-oriented vector control strategy is employed to realize the decoupling of the inverter output power.Simulation results and experiment in 3 kW lab prototype show an excellent static and dynamic performance of the proposed system.
文摘既有谐波源建模方法在应用于内部拓扑未知与机理不明场景时,难以有效兼顾谐波源的频域稳态特征与动态时变特征,致使所构建模型的准确性与鲁棒性难以提升。为此,该文提出一种基于时-频特征联合提取的谐波源数据驱动建模方法。首先,根据谐波源历史电压电流的频域分量确定谐波源的主导谐波频次;其次,构建谐波源稳态电压时-频特征矩阵并对其进行伪彩色编码以实现特征升维;最后,将动态时变信号与稳态特征分量彩色图组合输入所构建的多重卷积神经网络(multiple convolutional neural network,MCNN)与双向长短时记忆网络(bi-directional long short term memory network,BiLSTM)组合模型,构建反映谐波源动态时变特征与频域稳态特征的电压-电流映射关系。经仿真与实测数据验证,相较于其他数据驱动建模方法,所提方法不仅在单一谐波源建模场景下具有明显的优势,在复杂多谐波源场景下也具备较高的准确率与较强的鲁棒性。
