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Study of the Characteristics of DC and ICP Hybrid Discharge Plasmas

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Plasma Science and Technology 2015年第3期17卷 191-195页

作者：王战高巍张彭闫慧杰任春生 avic Shenyang aircraft Design & Research institute School of Physics and Optoelectronic Technology Dalian University of Technology

In this paper, the double-discharge plasma generated by radio frequency （RF） and direct current （DC） has been investigated. In comparison with their single-frequency counterpart, the interaction between the two excitations is significant and beneficial. The results show that the RF discharge can effectively increase the DC discharge current and decrease the DC voltage; meanwhile the DC discharge is favorable to feed abundant high energy seed electrons to the ICP discharge sustaining at 13.56 MHz for the latter to acquire higher plasma density and lower plasma potential by increasing the ionization rate. The innovative design has been demonstrated to facilitate more homogeneous performance with higher plasma density.

关键词： ICP DC discharge Langmuir probe plasma characteristic

Crystallization behavior in severely cold-drawn Ti_(50) Ni_(47) Fe_3 wire

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Rare Metals 2014年第3期33卷 258-262页

作者： Xin-Quan Zhang Hui-Fang Geng Fu-Shun Liu Wen Ma The Integrated Standard and Material Application Research Department AVIC The First Aircraft Institute School of Materials Science and Engineering Beijing University of Aeronautics and Astronautics Division of Science and Technology Information General Research Institute for Nonferrous Metals

The microstructures and crystallization behavior of Ti-47 at% Ni-3 at% Fe shape memory alloy wire under the condition of severe cold drawing at room temperature and different post-deformation annealing processes were intensively investigated using transmission electron microscope（TEM） and differential scanning calorimetry（DSC）. It is indicated that the amorphous phase is dominant in the Ti50Ni47Fe3 wire after the cold drawing of 78 % areal reduction. The critical temperature for recrystalization is determined at about 300 °C. The average grain size grows from 7 up to 125 nm when annealing temperature rises from300 to 500 °C. Post-deformation annealing process exerts significant influence on the crystallization temperature which climbs up with the increase of annealing temperature.

关键词： TisoNi47Fe3 wire Cold drawing Annealing Amorphous Crystallization

EMMAE failure detection system and failure evaluation over flight performance

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International Journal of Intelligent Computing and Cybernetics 2012年第3期5卷 401-420页

作者： Yueheng Qiu Weiguo Zhang Xiaoxiong Liu Pengxuan Zhao School of Automation Northwestern Polytechnical UniversityXi’anPeople’s Republic of China first aircraft Design institute of avic Xi’anPeople’s Republic of China

Purpose-The purpose of this paper is to present the research into fault detection and isolation(FDI)and evaluation of the reduction of performance after failures occurred in the flight control system(FCS)during its mission ***/methodology/approach–The FDI is accomplished via using the multiple models scheme which is developed based on the Extend Kalman Filter(EKF)*** this objective,the healthy mode of the FCS under different type of failures,including the control surfaces and structural,should be *** developed a bank of extended multiple models adaptive estimation(EMMAE)to detect and isolate the above mentioned failures in the *** addition,the performances including the flight envelope,the voyage and endurance in cruising are proposed to reference and evaluate the process of mission,especially for UAV under failure ***-The contribution of this paper is to provide the information not only about the failures,but also considering whether the UAV can accomplish the task for the ground ***/value-The main contribution of this paper is in the areas of the structural and control surface faults researching,which are occurred in the mission procedures and emphasized the identification of those failures’*** FDI scheme includes the performance evaluation,while the evaluation obtained through the extensive numerical simulations and saved in the offline *** a consequence,it is more accurate and less computationally demanding while evaluating the performance.

关键词： Fault detection and isolation(FDI) Extend Kalman Filter(EKF) Extended multiple models adaptive estimation(EMMAE) Flight envelope UAV Flight control Flight operations Failure(mechanical)

Reinforcement learning based UAV formation control in GPS-denied environment

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Chinese Journal of Aeronautics 2023年第11期36卷 281-296页

作者： Bodi MA Zhenbao LIU Feihong JIANG Wen ZHAO Qingqing DANG Xiao WANG Junhong ZHANG Lina WANG School of Civil Aviation Northwestern Polytechnical UniversityXi’an 710000China Research&Development institute in Shenzhen Northwestern Polytechnical UniversityShenzhen 518000China Flight Control Division AVIC The First Aircraft InstituteXi’an 710089China

Highly accurate positioning is a crucial prerequisite of multi Unmanned Aerial Vehicle close-formation flight for target tracking,formation keeping,and collision *** the position of a UAV can be obtained through the Global Positioning System(GPS),it is difficult for a UAV to obtain highly accurate positioning data in a GPS-denied environment(e.g.,a GPS jamming area,suburb,urban canyon,or mountain area);this may cause it to miss a tracking target or collide with another *** particular,UAV close-formation control in GPS-denied environments faces difficulties owing to the low-accuracy position,close distance between vehicles,and nonholonomic dynamics of a *** this paper,on the one hand,we develop an innovative UAV formation localization method to address the formation localization issues in GPS-denied environments;on the other hand,we design a novel reinforcement learning based algorithm to achieve the high-efficiency and robust performance of the ***,a novel Lidar-based localization algorithm is developed to measure the localization of each aircraft in the formation *** our solution,each UAV is equipped with Lidar as the position measurement sensor instead of the GPS *** k-means algorithm is implemented to calculate the center point position of UAV.A novel formation position vector matching method is proposed to match center points with UAVs in the formation and estimate their position ***,a reinforcement learning based UAV formation control algorithm is developed by selecting the optimal policy to control UAV swarm to start and keep flying in a close formation of a specific ***,the innovative collision risk evaluation module is proposed to address the collision-free issues in the formation ***,a novel experience replay method is also provided in this paper to enhance the learning *** results validate the accuracy,effectiveness,and robustness of the proposed scheme.

关键词： Close formation control GPS-denied environment Reinforcement learning Unmanned aerial vehicles(UAVs) Intelligent flight control

Aerodynamic optimization of rotor airfoil based on multi-layer hierarchical constraint method

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Chinese Journal of Aeronautics 2016年第6期29卷 1541-1552页

作者： Zhao Ke Gao Zhenghong Huang Jiangtao Li Quan The first aircraft institute of avic Xi’an 710089China National Key Laboratory of Aerodynamic Design and Research Northwestern Polytechnical UniversityXi’an 710072China China Aerodynamics Research and Development Center Mianyang 621000China

Rotor airfoil design is investigated in this paper. There are many difficulties for this highdimensional multi-objective problem when traditional multi-objective optimization methods are used. Therefore, a multi-layer hierarchical constraint method is proposed by coupling principal component analysis(PCA) dimensionality reduction and e-constraint method to translate the original high-dimensional problem into a bi-objective problem. This paper selects the main design objectives by conducting PCA to the preliminary solution of original problem with consideration of the priority of design objectives. According to the e-constraint method, the design model is established by treating the two top-ranking design goals as objective and others as variable constraints. A series of bi-objective Pareto curves will be obtained by changing the variable constraints, and the favorable solution can be obtained by analyzing Pareto curve spectrum. This method is applied to the rotor airfoil design and makes great improvement in aerodynamic performance. It is shown that the method is convenient and efficient, beyond which, it facilitates decision-making of the highdimensional multi-objective engineering problem.

关键词： Multi-layer hierarchical constraint method Multi-objective optimization NSGA II Pareto front Principal component analysis Rotor airfoil

Experimental investigation of unsteady attached cavitating flow induced pressure fluctuation

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Journal of Hydrodynamics 2022年第1期34卷 31-42页

作者： Hou-sheng Zhang Guang-hao Chen Qin Wu Biao Huang School of Mechanical Engineering Beijing Institute of TechnologyBeijing100081China avic Jincheng Nanjing Engineering institute of aircraft System Nanjing211106China

This paper experimentally investigates the pressure fluctuation induced by the unsteady attached cavitating flow, with special focus on the quasi-periodic cloud cavitation. A simultaneous sampling method is adopted for the synchronous measurement of the wall pressure signals and the cavitating flow images in a convergent-divergent channel. The results show that the pressure fluctuation is composed of three parts, the flow noise, the low-frequency fluctuation, and the cavity collapse induced impulse, and the pressure evolution of the quasi-periodic cloud cavitation is well consistent with the cavitation evolution. The statistical analysis of the pressure fluctuation shows that, when σ > 1.01, the probability density function (PDF) is nearly in the normal distribution, implying the randomness of the pressure fluctuation, when 0.84 1.01, when σ < 0.84, the PDF becomes narrow and asymmetric. In addition, the variance and the average value of the pressure indicate that the fluctuation intensity increases downstream along the cavity and reaches the maximum at the cavity closure and it also increases with the decrease of the cavitation number. The spectral analysis shows that the low-frequency pressure fluctuations mainly consist of two dominant components, the cavity shedding induced fluctuation and the lock-in fluctuation. The cavity shedding induced frequency decreases with the decrease of the cavitation number but the lock-in frequency is kept nearly constant. According to the spectral analysis of the cavity area fluctuation and the modal analysis of the flow system, the lock-in is possibly caused when the fluctuation frequency of the cavity volume approaches the natural frequency of the flow system.

关键词： Cavitation pressure fluctuation statistical features lock-in phenomenon

Effect of Solution Treatment on Recrystallization,Texture and Mechanical Properties of 7A65-T74 Aluminum Alloy Super-thick Hot Rolled Plate

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Journal of Wuhan University of Technology(Materials Science) 2022年第3期37卷 460-469页

作者： LI Chen WANG Hao WANG Wenbo YE Chengtong JIN Zuheng ZHANG Xinquan ZHANG Hu JIA Lina The first aircraft of institute of avic Xi’an 710000China Department of Materials Science and Engineering Beihang UniversityBeijing 100191China Research Center for Lightweight Materials Ningbo Institute of TechnologyBeihang UniversityNingbo 315100China

The effects of the solution treatment on the microstructure,recrystallization,texture composition and properties of 7A65-T7451(120 mm)hot rolled plates at H/2(1/2 thickness)and H/4(1/4 thickness)were *** results show that the hot rolled microstructure mainly contains a large amount of MgZn_(2) phases and minor Al_(7)Cu_(2)Fe *** solid solution treatments,a large amount of MgZn_(2) phases are dissolved back into the aluminum *** main texture types at H/4 are R-Cube,Cube and part of Brass texture,and the main texture types at H/2 are Cube,R,and Copper *** qualitative analysis by Schmidt's law reveals that Copper texture at H/2 will deepen the anisotropy of plate metal *** the plate with the same thickness,the two-stage solution state has better mechanical properties due to the lower degree of recrystallization and stronger grain boundary strengthening *** the two-stage solution system of 460℃/165 min+477℃/165 min,the composite mechanical properties of the alloy plate at H/4 are the best and the anisotropy is not *** tensile strength,yield strength,and elongation along the rolling direction are 561.9 MPa,523.4 MPa,and 10.6%,respectively..

关键词： 7A65 thick plate solid solution treatment texture recrystallization anisotropic

Experimental investigation on boiling heat transfer characteristics of Al_2O_3-water nanofluids in swirl microchannels subjected to an acceleration force

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Chinese Journal of Aeronautics 2019年第5期32卷 1136-1144页

作者： Sujun DONG Hongsheng JIANG Yongqi XIE Xiaoming WANG Zhongliang HU Jun WANG School of Aeronautic Science and Engineering Beihang University avic Chengdu aircraft Design and Research institute School of Chemical and Process Engineering University of Leeds

Experiments were carried out to investigate the boiling heat transfer characteristics of Al_2O_3-water nanofluids in swirl microchannels under terrestrial gravity and acceleration fields. A centrifuge with a two-meter long rotational arm was used to simulate the acceleration magnitude up to 9 g and three various acceleration directions. Three test sections with different geometric parameters were applied. The volume concentration of Al_2O_3 nanoparticles with an average diameter of 13 nm was varied from 0.07% to 0.1%. The mass flow rate and vapor quality were in ranges of 3–6 kg/h and 0.4–1.0%, respectively. The effects of the mass flow rate, microchannel aspect ratio,vapor quality, nanoparticle volume concentration, and acceleration direction and magnitude were analyzed in a systematic manner. Experimental results showed that the acceleration direction and magnitude had significant influences on the boiling heat transfer. The heat transfer under configuration C was found to be superior to that under configurations A and B. Moreover, the heat transfer coefficient increased with increases of the mass flow rate and the volume concentration and decreased with the aspect ratio.

关键词： Acceleration Boiling heat transfer Microchannel Nanofluid Swirl microchannels

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大型飞机座舱温度控制系统控制律设计

航空学报 2017年第S1期38卷 14-22页

作者：任明波王娟李荣军党亚 Electro-mechanical System Design and Research Department AVIC The First Aircraft Institute Xi'an 710089 China

大型飞机座舱温度控制系统具有温度控制非线性、强耦合、大迟滞性等特点,对控制律设计提出很高要求。根据系统设计要求,结合执行机构动作特性,提出了一种新型座舱温度控制律。系统控制方案采用压气机出口温度控制、组件出口温度控制、... 详细信息

大型飞机座舱温度控制系统具有温度控制非线性、强耦合、大迟滞性等特点,对控制律设计提出很高要求。根据系统设计要求,结合执行机构动作特性,提出了一种新型座舱温度控制律。系统控制方案采用压气机出口温度控制、组件出口温度控制、座舱供气温度控制和座舱区域温度控制四级控制;压气机出口温度目标值根据大气环境温度确定,座舱供气温度目标值根据座舱区域温度控制误差确定,组件出口温度目标值根据座舱供气温度目标值中的最小值确定;使用专家比例-积分-微分(PID)控制方法设计各级温度控制器,温度控制器的设计融入了解耦控制算法和系统保护控制逻辑,控制周期由各级温度控制响应特性确定。系统地面试验与飞行试验结果显示,该座舱温度控制系统响应速度快,抗干扰能力强,控制精度高,满足系统设计要求。

关键词：环境控制系统座舱温度控制 PID控制解耦控制

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