幅度均衡器被广泛应用于各类微波组件,是其重要的组成部分。对定阻型的幅度均衡器设计进行分析,利用Ga As MMIC标准工艺制作了一款22~32 GHz单片幅度均衡器,该芯片尺寸为0.8 mm×0.7 mm×0.1 mm。经装架测试,在工作频段实现5 d ...幅度均衡器被广泛应用于各类微波组件,是其重要的组成部分。对定阻型的幅度均衡器设计进行分析,利用Ga As MMIC标准工艺制作了一款22~32 GHz单片幅度均衡器,该芯片尺寸为0.8 mm×0.7 mm×0.1 mm。经装架测试,在工作频段实现5 d B的负斜率幅度均衡量,驻波良好,插损2.53 d B@32 GHz,基本实现了设计目标。展开更多
The corrosion resistance of electroless Ni-P deposits with phosphorous contents from 12% to 14% in sodium chloride solutions was studied. The deposits were immersed in 3.5% NaCl solutions for 29 d to obtain the electr...The corrosion resistance of electroless Ni-P deposits with phosphorous contents from 12% to 14% in sodium chloride solutions was studied. The deposits were immersed in 3.5% NaCl solutions for 29 d to obtain the electrochemical parameters and were examined in a standard salt spray test for 15 d respectively. The corrosion resistance of the deposits was studied by poten- tio-dynamic scan, electrochemical impedance spectroscopy (EIS), X-ray diffraction (XRD) and cold-field emission scanning electron microscopy (FE-SEM) equipped with an energy dispersive X-ray detector (EDX). The patterns of XRD and the results of FE-SEM showed that the prepared deposits were amorphous. But after a 15 d standard salt spray test, a few pinholes appeared on the surface of the deposit and the weight content of phosphorus on the surface of the deposit was higher (which was beneficial to the formation of the passivation films) than that before the standard salt spray test when the nickel content was lower because the dissolved weight of nickel was greater than that of phosphorus. The results from potentio-dynamic scan and EIS showed that passivation films formed on the Ni-P deposit after immersion in the NaCl solutions, which decreased the corrosion rate of Ni-P samples. The results of this work show their potential applications in marine corrosion.展开更多
In terms of our new exact definition of partial Lagrangian and approximate Euler-Lagrange-type equation, we investigate the nonlinear wave equation with damping via approximate Noether-type symmetry operators associat...In terms of our new exact definition of partial Lagrangian and approximate Euler-Lagrange-type equation, we investigate the nonlinear wave equation with damping via approximate Noether-type symmetry operators associated with partial Lagrangians and construct its approximate conservation laws in general form.展开更多
Electrifying the on-board subsystems of aircraft becomes an inevitable process as being faced with the environmental pollution,along with the proposed concept called more electric aircraft(MEA).With the increasing num...Electrifying the on-board subsystems of aircraft becomes an inevitable process as being faced with the environmental pollution,along with the proposed concept called more electric aircraft(MEA).With the increasing number of on-board power electronic based devices,the distribution system of the aircraft can be regarded as an onboard microgrid.As it is known that the load power electronic converters can exhibit constant power load(CPL)characteristics and reduce the system stability,it is necessary to accurately predict and enhance the system stability in designing process.This paper firstly analyzes the stability of an on-board DC microgrid with the presence of CPL.Then,discusses the reasons behind instability and proposes a control strategy to enhance system stability.Finally,the simulation results are worked out to validate the analysis and the effect of the proposed control strategy.展开更多
This paper proposes a multi-layer multi-agent model for the performance evaluation of powersystems,which is different from the existing multi-agent ones.To describe the impact of the structureof the networked power sy...This paper proposes a multi-layer multi-agent model for the performance evaluation of powersystems,which is different from the existing multi-agent ones.To describe the impact of the structureof the networked power system,the proposed model consists of three kinds of agents that form threelayers:control agents such as the generators and associated controllers,information agents to exchangethe information based on the wide area measurement system (WAMS) or transmit control signals tothe power system stabilizers (PSSs),and network-node agents such as the generation nodes and loadnodes connected with transmission lines.An optimal index is presented to evaluate the performance ofdamping controllers to the system's inter-area oscillation with respect to the information-layer topology.Then,the authors show that the inter-area information exchange is more powerful than the exchangewithin a given area to control the inter-area low frequency oscillation based on simulation analysis.展开更多
文摘幅度均衡器被广泛应用于各类微波组件,是其重要的组成部分。对定阻型的幅度均衡器设计进行分析,利用Ga As MMIC标准工艺制作了一款22~32 GHz单片幅度均衡器,该芯片尺寸为0.8 mm×0.7 mm×0.1 mm。经装架测试,在工作频段实现5 d B的负斜率幅度均衡量,驻波良好,插损2.53 d B@32 GHz,基本实现了设计目标。
文摘The corrosion resistance of electroless Ni-P deposits with phosphorous contents from 12% to 14% in sodium chloride solutions was studied. The deposits were immersed in 3.5% NaCl solutions for 29 d to obtain the electrochemical parameters and were examined in a standard salt spray test for 15 d respectively. The corrosion resistance of the deposits was studied by poten- tio-dynamic scan, electrochemical impedance spectroscopy (EIS), X-ray diffraction (XRD) and cold-field emission scanning electron microscopy (FE-SEM) equipped with an energy dispersive X-ray detector (EDX). The patterns of XRD and the results of FE-SEM showed that the prepared deposits were amorphous. But after a 15 d standard salt spray test, a few pinholes appeared on the surface of the deposit and the weight content of phosphorus on the surface of the deposit was higher (which was beneficial to the formation of the passivation films) than that before the standard salt spray test when the nickel content was lower because the dissolved weight of nickel was greater than that of phosphorus. The results from potentio-dynamic scan and EIS showed that passivation films formed on the Ni-P deposit after immersion in the NaCl solutions, which decreased the corrosion rate of Ni-P samples. The results of this work show their potential applications in marine corrosion.
基金Supported by the National Natural Science Foundation of China under Grant No.10671156the Natural Science Foundation of Shaanxi Province of China under Grant No.SJ08A05
文摘In terms of our new exact definition of partial Lagrangian and approximate Euler-Lagrange-type equation, we investigate the nonlinear wave equation with damping via approximate Noether-type symmetry operators associated with partial Lagrangians and construct its approximate conservation laws in general form.
基金supported by Ministry of Science&Technology under National Key R&D Program of China(No.2021YFE0108600)Ningbo Science and Technology Bureau under S&T Innovation 2025 Major Special Program(No.2019B10071)Key International Cooperation of National Natural Science Foundation of China(No.51920105011)。
文摘Electrifying the on-board subsystems of aircraft becomes an inevitable process as being faced with the environmental pollution,along with the proposed concept called more electric aircraft(MEA).With the increasing number of on-board power electronic based devices,the distribution system of the aircraft can be regarded as an onboard microgrid.As it is known that the load power electronic converters can exhibit constant power load(CPL)characteristics and reduce the system stability,it is necessary to accurately predict and enhance the system stability in designing process.This paper firstly analyzes the stability of an on-board DC microgrid with the presence of CPL.Then,discusses the reasons behind instability and proposes a control strategy to enhance system stability.Finally,the simulation results are worked out to validate the analysis and the effect of the proposed control strategy.
基金supported in part by the National Natural Science Foundation of China under Grants Nos. 50707035, 50595411, 60425307, 60221301 and 50607005, in part by the 111 project (B08013)Program for Changjiang Scholars and Innovative Research Team in University (IRT0515)in part by the Program for New Century Excellent Talents in University (NCET-05-0216)
文摘This paper proposes a multi-layer multi-agent model for the performance evaluation of powersystems,which is different from the existing multi-agent ones.To describe the impact of the structureof the networked power system,the proposed model consists of three kinds of agents that form threelayers:control agents such as the generators and associated controllers,information agents to exchangethe information based on the wide area measurement system (WAMS) or transmit control signals tothe power system stabilizers (PSSs),and network-node agents such as the generation nodes and loadnodes connected with transmission lines.An optimal index is presented to evaluate the performance ofdamping controllers to the system's inter-area oscillation with respect to the information-layer topology.Then,the authors show that the inter-area information exchange is more powerful than the exchangewithin a given area to control the inter-area low frequency oscillation based on simulation analysis.
