检索结果-南通市图书馆

Novel supervised classification approach for multifrequency polarimetric SAR data

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Systems Engineering and Electronics 2015年第6期26卷 1216-1221页

作者： Biao You Bin Xu Jian Yang Chunmao Yeh Jianshe Song Department of Electronic Engineering Tsinghua University Beijing Institute of Radio Measurement Xi'an Research Institute of Hi-Technology

A novel method is proposed for the supervised classification of multifrequency polarimetric synthetic aperture radar （PolSAR） images. The coherency matrices in P-, L-, and C-bands are mapped onto a 9×9 matrix Ω based on the eigenvalue decomposition of the coherency matrix of each band. A boxcar filter is then performed on the matrix Ω. The filtered data are put into a complex Wishart classifier. Finally, the effectiveness of the proposed method is demonstrated with JPL/AIRSAR multifrequency PolSAR data acquired over the Flevoland area.

关键词： synthetic aperture radar (SAR) polarimetry classifi-cation multifrequency.

Design and analysis of a novel hybrid cooling method of high-speed high-power permanent magnet assisted synchronous reluctance starter/generator in aviation applications

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2023年第3期36卷 285-302页

作者： Hong GUO Xu HE Jinquan XU Wei TIAN Xiaofeng DING Laicai JU Dehong LI School of Automation science and Electrical Engineering Beihang UniversityBeijing 100083China science and Technology on Aircraft Control Laboratory Beihang UniversityBeijing 100083China Ningbo Innovation Research Institute Ningbo 315800China School of Electrical and Information Engineering Jiangsu UniversityZhenjiang 212013China Beijing Shuguang Aviation Electric Co.LTD Beijing 101300China Aviation Industry Helicopter Design and Research Institute Jingdezhen 333001China

To improve the heat dissipation performance,this paper proposes a novel hybrid cooling method for high-speed high-power Permanent Magnet assisted Synchronous Reluctance Starter/Generator(PMa Syn R S/G)in aerospace *** hybrid cooling structure with oil circulation in the housing,oil spray at winding ends and rotor end surface is firstly proposed for the PMa Syn R S/*** the accurate loss calculation of the PMa Syn R S/G is proposed,which includes air gap friction loss under oil spray cooling,copper loss,stator and rotor core loss,permanent magnet eddy current loss and bearing *** parameter sensitivity analysis of the hybrid cooling structure is proposed,while the equivalent thermal network model of the PMa Syn R S/G is established considering the uneven spraying at the winding ***,the effectiveness of the proposed hybrid cooling method is demonstrated on a 40 k W/24000 r/min PMa Syn R S/G experimental platform.

关键词： Air gap friction loss Oil spray cooling Permanent magnet assisted synchronous reluctance starter/generator Thermal analysis Thermal network model

Robust adaptive compensation control for unmanned autonomous helicopter with input saturation and actuator faults

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2019年第10期32卷 2299-2310页

作者： Kun YAN Mou CHEN Qingxian WU Ronggang ZHU College of Automation Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016China Luoyang Institute of Electro-Optical Equipment of AVIC Luoyang 471000China

This paper studies a robust adaptive compensation Fault Tolerant Control(FTC)for the medium-scale Unmanned Autonomous Helicopter(UAH)in the presence of external disturbances,actuator faults and input *** improve the disturbance rejection capacity of the UAH system in actuator healthy case,an adaptive control method is adopted to cope with the external disturbances and a nominal controller is proposed to stabilize the ***,compensation control inputs are designed to reduce the negative effects derived from actuator faults and input *** on the backstepping control and inner-outer loop control technologies,a robust adaptive FTC scheme is developed to guarantee the tracking errors *** the presented FTC controller,the uniform ultimate boundedness of all closed-loop signals is ensured via Lyapunov stability *** results demonstrate the effectiveness of the proposed control algorithm.

关键词： Compensation control Fault tolerant control Input saturation Tracking control Unmanned autonomous helicopter

Modeling and analysis of oil frictional loss in wet-type permanent magnet synchronous motor for aerospace electro-hydrostatic actuator

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2023年第11期36卷 328-341页

作者： Jinquan XU Wenbo JIN Hong GUO Tian YU Wenhu FAN Zongxia JIAO School of Automation science and Electrical Engineering Beihang UniversityBeijing 100191China Ningbo Institute of Technology Beihang UniversityNingbo 315800China Research Institute for Frontier science Beihang UniversityBeijing 100191China

To improve the power density and simplify the seal structure,the Wet-Type Permanent Magnet Synchronous Motor(WTPMSM)technique has been applied to aerospace Electro-Hydrostatic Actuators(EHA).In a WTPMSM,the stator and the rotor are both immersed in the aviation hydraulic *** the heat dissipation performance of the WTPMSM can be enhanced,the aviation hydraulic oil will cost an extra oil frictional loss in the narrow airgap of the *** paper proposes an accurate oil frictional loss model for the WTPMSM,in which the wide speed range(0–20 kr/min)and the narrowness of the airgap(0.5–1.5 mm)are its ***,the mechanism of the oil frictional loss in the airgap of the WTPMSM is *** an accurate oil frictional loss model is proposed considering the nonlinear influence caused by the Taylor ***,the influence of motor dimensions on oil frictional loss is ***,the proposed oil frictional loss model is verified by experiments,which provides a guideline for engineers to follow in the WTPMSM design.

关键词： Electro-hydrostatic actuator Motor dimensions Oil frictional loss Taylor vortex Wet-type permanent magnet synchronous motor

Flow Characteristics of Double-Cruciform Parachute at Inflating and Inflated Conditions

在线全文

学校读者我要写书评

暂无评论

Transactions of Nanjing University of Aeronautics and Astronautics 2018年第6期35卷 992-999页

作者： Fang Ming Sun Jianhong Zhang Tong Hou Bin Zhang Yantai Key Laboratory of Aircraft Environment Control and Life Support of MIIT College of Aerospace EngineeringNanjing University of Aeronautics and Astronautics

The fluid-structure interaction (FSI) between the canopy and flow field on the inflating and inflated conditions is investigated based on the arbitrary Lagrange-Euler (ALE) method,in both a single-and double-cruciform parachute *** projection area of canopy is calculated in the inflation *** flow field characteristics and the interaction between canopies are *** showed that,with free stream velocity of 50m/s,overinflation phenomenon would not occur during the inflation process of the double-cruciform-parachute system,because the collision and extrusion of the two canopies during inflation obstructed the oscillation of the inner ***,compared with the single-cruciform parachute,the vortex motion in the wake of double-cruciform-parachute is more *** the double-cruciform parachute system oscillated at a velocity of 50 m/s with an angle of less than 6.8°.By comparison,the oscillation angle of the single-cruciform parachute was within 3.5° at the velocity of 50m/*** results are consistent with those of the wind tunnel test.

关键词： process of inflation arbitrary Lagrange-Euler(ALE) Lamb vector divergence cruciform parachute

Virtual target guidance-based distributed model predictive control for formation control of multiple UAVs

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2020年第3期33卷 1037-1056页

作者： Zhihao CAI Longhong WANG Jiang ZHAO Kun WU Yingxun WANG School of Automation science and Electrical Engineering Beihang UniversityBeijing 100083China Flying College Beihang UniversityBeijing 100083China

The paper proposes a Virtual Target Guidance(VTG)-based distributed Model Predictive Control(MPC) scheme for formation control of multiple Unmanned Aerial Vehicles(UAVs).First, a framework of distributed MPC scheme is designed in which each UAV only shares the information with its neighbors, and the obtained local Finite-Horizon Optimal Control Problem(FHOCP) can be solved by swarm intelligent optimization ***, a VTG approach is developed and integrated into the distributed MPC scheme to achieve trajectory tracking and obstacle ***, an event-triggered mechanism is proposed to reduce the computational burden for UAV formation control, which takes into consideration the predictive state errors as well as the convergence of cost *** simulations show that the proposed VTG-based distributed MPC scheme is more computationally efficient to achieve formation control of multiple UAVs in comparison with the traditional distributed MPC method.

关键词： Distributed Model Predictive Control(MPC) Event-triggered mechanism Formation control Obstacle avoidance Unmanned Aerial Vehicles(UAVs) Virtual Target Guidance(VTG)

C-HMAX: Artificial Cognitive Model Inspired by the Color Vision Mechanism of the Human Brain

在线全文

学校读者我要写书评

暂无评论

Tsinghua science and Technology 2013年第1期18卷 51-56页

作者： Bo Yang Lipu Zhou Zhidong Deng the State Key Laboratory of Intelligent Technology and Systems Tsinghua National Laboratory for Information Science and TechnologyDepartment of Computer Science and TechnologyTsinghua University

Artificial cognitive models and computational neuroscience methods have garnered great interest from both neurologist and leading analysts in recent years. Among the cognitive models, HMAX has been widely used in computer vision systems for its robustness shape and texture features inspired by the ventral stream of the human brain. This work presents a Color-HMAX （C-HMAX） model based on the HMAX model which imitates the color vision mechanism of the human brain that the HMAX model does not include. C-HMAX is then applied to the German Traffic Sign Recognition Benchmark （GTSRB） which has 43 categories and 51 840 sample traffic signs with an accuracy of 98.41%, higher than most other models including linear discriminant analysis and multi-scale convoiutional neural network.

关键词： artificial cognitive model machine learning traffic sign recognition

Multi-layer collaborative optimization fusion for semi-supervised learning

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2023年第11期36卷 342-353页

作者： Quanbo GE Muhua LIU Jianchao ZHANG Jianqiang SONG Junlong ZHU Mingchuan ZHANG School of Automation Nanjing University of Information Science and TechnologyNanjing 210044China School of Information Engineering Henan University of Science and TechnologyLuoyang 471023China Qiandao Lake Institute of science Hangzhou 311799China

Recently,the Cooperative Training Algorithm(CTA),a well-known Semi-Supervised Learning(SSL)technique,has garnered significant attention in the field of image ***,traditional CTA approaches face challenges such as high computational complexity and low classification *** overcome these limitations,we present a novel approach called Weighted fusion based Cooperative Training Algorithm(W-CTA),which leverages the cooperative training technique and unlabeled data to enhance classification ***,we introduce the K-means Cooperative Training Algorithm(km-CTA)to prevent the occurrence of local optima during the training ***,we conduct various experiments to verify the performance of the proposed *** results show that W-CTA and km-CTA are effective and efficient on CIFAR-10 dataset.

关键词： Collaborative training Fusion Image classification K-means algorithm Semi-supervised learning

MTTSNet:Military time-sensitive targets stealth network via real-time mask generation

在线全文

学校读者我要写书评

暂无评论

Defence Technology（防务技术） 2024年第3期33卷 601-612页

作者： Siyu Wang Xiaogang Yang Ruitao Lu Zhengjie Zhu Fangjia Lian Qing-ge Li Jiwei Fan PLA Rocket Force University of Engineering Xi'an 710025China

The automatic stealth task of military time-sensitive targets plays a crucial role in maintaining national military security and mastering battlefield dynamics in military *** propose a novel Military Time-sensitive Targets Stealth Network via Real-time Mask Generation(MTTSNet).According to our knowledge,this is the first technology to automatically remove military targets in real-time from *** critical steps of MTTSNet are as follows:First,we designed a real-time mask generation network based on the encoder-decoder framework,combined with the domain expansion structure,to effectively extract mask ***,the ASPP structure in the encoder could achieve advanced semantic feature *** decoder stacked high-dimensional information with low-dimensional information to obtain an effective mask ***,the domain expansion module guided the adaptive expansion of mask ***,a context adversarial generation network based on gated convolution was constructed to achieve background restoration of mask positions in the original *** addition,our method worked in an end-to-end manner.A particular semantic segmentation dataset for military time-sensitive targets has been constructed,called the Military Time-sensitive Target Masking Dataset(MTMD).The MTMD dataset experiment successfully demonstrated that this method could create a mask that completely occludes the target and that the target could be hidden in real time using this *** demonstrated the concealment performance of our proposed method by comparing it to a number of well-known and highly optimized baselines.

关键词： Deep learning Military application Targets stealth network Mask generation Generative adversarial network