检索结果-内蒙古大学图书馆

CSAA/IET International Conference on Aircraft Utility systems 2020, AUS 2020

作者： Jin, Lou Yang, Pin Hu, Xuepeng Li, Hui Zhang, Linling Cui, Dongyue Aviation Key Laboratory of Science and Technology on Life-support Technology Xianyang China AVIC Aerospace Life-support Industries Ltd. Xianyang China AVIC The First Aircraft Institute Institute of Mechanical and Electrical System Xi'an China

ISBN: (纸本)9781839535635

In this paper, the ALE fluid-solid coupling algorithm is used to realize the simulation of the dynamic opening process of a certain type of airplane drag parachute. Based on the drag parachute working principle and folding process, a finite element model of the main parachute in the installed state is established. In the LS-DYNA software, the parachute opening characteristics of the drag parachute were simulated and analyzed under no crosswind conditions and Stable crosswind conditions at speed 10m/s. The results show that, under the condition of no crosswind, the error of the important parameters such as parachute straightening force, parachute opening dynamic load, parachute deflection angle and test data is less than 15%, and the simulation accuracy meets the engineering development requirements. On this basis, the parameters such as the unfolding shape, deflection angle, and stress state of the parachute parachute under stable crosswind conditions, which are difficult to test and simulate, were studied. This will provide a theoretical basis and technical approach for drag chute design and other types of parachute product research. © 2020 Institution of Engineering and technology. All rights reserved.

关键词： Product design

来源：评论

学校读者我要写书评

暂无评论

Modeling and Precise Position Control of Flexible Joints with Harmonic Drives

Modeling and Precise Position Control of Flexible Joints wit...

引用

International Conference on Electrical Machines and systems (ICEMS)

作者： Yiwei Tang Xin Sun Qi He Xi Xiao Weihua Wang Tsinghua Univerisy Beijing China Aviation key Laboratory of Science and Technology on Aerospace Power System Shaanxi Aero Electric Co. Ltd. Xi’an China Foshan (Southern China) Institute for New Materials Foshan City China

Complex torsional behaviors of harmonic drives lead to performance degradation of flexible joint servo systems, raising the need for accurate models and suited control approaches. A comprehensive model is proposed in this paper considering the friction, the nonlinear stiffness, and the kinematic error. The torsional hysteresis phenomenon of the harmonic drive is represented using Preisach model and treated inside the stiffness submodel. Identification processes for the comprehensive model based on no-load tests and stall tests are elaborated, and a control method based on feedback linearizing is also put forward. Experiment results indicate that the comprehensive model matches the measurements well, and the proposed controller shows better dynamic responses than conventional PI controllers.

关键词： Degradation PI control Friction Process control Position control Kinematics Harmonic analysis

来源：评论

学校读者我要写书评

暂无评论

Topological prime

引用

science China(Technological sciences) 2020年第7期63卷 1314-1322页

作者： YANG XuXu YANG CanHui LIU JunJie YAO Xi SUO ZhiGang John A.Paulson School of Engineering and Applied Sciences Kavli Institute for Bionano Science and TechnologyHarvard UniversityCambridge MA 02138USA State Key Laboratory of Fluid Power&Mechatronic System Key Laboratory of Soft Machines and Smart Devices of Zhejiang ProvinceDepartment of Engineering Mechanics and Center for X-MechanicsZhejiang UniversityHangzhou 310027China Department of Mechanics and Aerospace Engineering Southern University of Science and TechnologyShenzhen 518055China Key Lab for Special Functional Materials of Ministry of Education Henan UniversityKaifeng 475004China

This paper describes a general method, called topological prime, to stitch functional groups to a substrate of entropic polymer network. The precursor of a topological primer contains polymers, crosslinkers, and coupling agents. When the precursor is applied on the surface of the substrate, the crosslinkers link the primer polymers into a primer network, in topological entanglement with the substrate network, while the coupling agents link the primer network to the functional groups. The use of topological prime is demonstrated by priming a hydrophobic elastomer of an arbitrary shape for hydrophilic coating. We describe an approach that fulfills two fundamental requirements: wetting and adhesion. The coated elastomer maintains hydrophilicity and lubricity after stretch, scratch, swell, and slide. As a further demonstration, a hydrogel substrate is primed for hydrophobic coating. Topological prime opens an enormous space for applications in engineering and biomedicine.

关键词： elastomer hydrogel hydrophilic coating topological prime functional groups

来源：评论

学校读者我要写书评

暂无评论

Study on rotor eddy current loss of double-winding permanent magnet fault-tolerant motor for electro-hydrostatic actuator applications

Study on rotor eddy current loss of double-winding permanent...

引用

CSAA/IET International Conference on Aircraft Utility systems 2020, AUS 2020

作者： Zhao, Qing Hu, Yaohua Zhang, Pengfei Yang, Le AVIC Aerospace System CO. LTD No.5 Yard Shuguang Xili Beijing China Aviation Key Laboratory of Science and Technology on Aero Electromechanical System Integration Nanjing Engineering Institute of Aircraft Systems No 33 Shuige Road Nanjing China

ISBN: (纸本)9781839535635

Rotor eddy current losses of a double-winding high-speed permanent magnet fault-tolerant motor for electro-hydrostatic actuator (EHA) applications are studied in this paper. Firstly, the rotor eddy current losses of dual-winding high-speed permanent magnet fault-tolerant motors with different winding modes are studied. Then, the rotor eddy current losses of different magnetic retaining sleeve materials such as stainless steel, titanium alloy and carbon fiber are calculated accurately. The problem of slot opening and slot segmentation in high speed permanent magnet motor with concentrated winding is analysed. Finally, a double-winding high-speed permanent magnet fault-tolerant motor prototype was fabricated to verify the analysis results. © 2020 Institution of Engineering and technology. All rights reserved.

关键词： Permanent magnets

来源：评论

学校读者我要写书评

暂无评论

Experimental and Numerical Study on the Plasma-Laser-Induced Ignition of Strut Stabilizer at Different Locations

SSRN

引用

SSRN 2023年

作者： Jia, Xin Hu, Bin Zhao, Wei Zeng, Wen Peng, Jiangbo Zhao, Qingjun Institute of Engineering Thermophysics Chinese Academy of Sciences Beijing100190 China National Key Laboratory of Science and Technology on Advanced Light-duty Gas-turbine Beijing100190 China School of Aeronautics and Astronautics University of Chinese Academy of Sciences Beijing100049 China School of Aero-engine Shenyang Aerospace University Shenyang110136 China School of Astronautics Harbin Institute of Technology Harbin150001 China Beijing Key Laboratory of Distributed Combined Cooling Heating and Power System Beijing100190 China

The ignition performance of the strut stabilizer is an important parameter in the design of integrated afterburners. The ignition location significantly affects the ignition performance and flame propagation, and therefore it should be deeply studied. The ignition performance and flame propagation at different axial ignition locations downstream of the strut stabilizer are studied in this paper. When the dimensionless ignition distance (L/D) is approximately 1, a lower ignition equivalence ratio is required for ignition, and the flame propagates faster to the entire combustion chamber. For different ignition locations, the generated flame kernel propagates to the shear layer, the flame rapidly then extends, and ultimately ignites the entire combustion chamber. The flame propagation trajectory depends on the ignition location controlled by the non-reacting flow field and the distribution of kerosene concentration. The flame propagation trajectory mainly includes three ways: (1) the flame kernel which is directly downstream the shear layer when the ignition location is close to the tail edge of the stabilizer, (2) the flame propagates upstream into the shear layer in a U-shape when the ignition location is far from the stabilizer but still in the recirculation zone, and (3) the flame propagates upstream into the recirculation zone and shear layer in a U-shape when the ignition location is outside the recirculation zone. In addition, the time for the flame propagating to the shear layer is directly related to the ignition performance when the ignition location is within the recirculation zone. If the flame reaches the shear layer for a longer time, there will be more energy loss during the flame propagation process, and the ignition performance will be deteriorated. The speed of the flame trailing edge extension is directly related to the ignition fuel-air-ratio, and the downstream extension of the flame is mainly affected by the turbulence velocity in the shear layer.

关键词： Ignition

来源：评论

学校读者我要写书评

暂无评论

Study on Rotor Eddy Current Losses in High-speed Permanent Magnet Motor for Aircraft Applications

Study on Rotor Eddy Current Losses in High-speed Permanent M...

引用

International Conference on Electrical Machines and systems (ICEMS)

作者： Yaohua Hu Shushu Zhu Yibo Ge Aviation Key Laboratory of Science and Technology on Aero Electromechanical System Integration Nanjing Engineering Institute of Aircraft Systems Nanjing China Center for More-electric-aircraft Power System Nanjing University of Aeronautics and Astronautics Nanjing China

The rotor eddy current loss of 30 kW/60000 r/min high speed permanent magnet motor for aviation applications is studied in this paper. According to the basic electromagnetic characteristics of the motor, the no-load air gap flux density and flux distribution, the output torque under rated load, the eddy current of the rotor with different stator slot openings and different permanent magnet sheath materials under rated load are studied. The results show that the smaller the stator slot opening is, the smaller the eddy current loss is, but the larger the stator core loss is. The smaller the permeability of the permanent magnet sheath material is, the smaller the eddy current loss of the rotor is. Carbon fiber or titanium alloy is recommended for high speed permanent magnet motors.

关键词：

来源：评论

学校读者我要写书评

暂无评论

Enhancing Plasticity in BCC Mg-Li-Al Alloys Through Controlled Precipitation at Grain Boundaries

SSRN

引用

SSRN 2024年

作者： Ji, Fan Xin, Tongzheng Zhao, Yuhong Yang, Wenkui Bai, Guoning Tang, Song Guo, Enyu Zhou, Mengran Shi, Qingyu Cui, Luqing Chen, Long-Qing He, Binbin Department of Mechanical and Energy Engineering Southern University of Science and Technology Shenzhen518055 China Instrumental Analysis Center Dalian University of Technology Dalian116024 China School of Materials Science and Engineering Dalian University of Technology Dalian116024 China Beijing Advanced Innovation Center for Materials Genome Engineering University of Science and Technology Beijing Beijing100083 China School of Materials Science and Engineering Collaborative Innovation Center of Ministry of Education Shanxi Province for High-performance Al/Mg Alloy Materials North University of China Taiyuan030051 China Institute of Materials Intelligent Technology Liaoning Academy of Materials Shenyang110004 China Herbert Gleiter Institute of Nanoscience School of Materials Science and Engineering Nanjing University of Science and Technology Jiangsu210094 China State Key Laboratory of Clean and Efficient Turbomachinery Power Equipment Department of Mechanical Engineering Tsinghua University Beijing100084 China Key Laboratory for Advanced Materials Processing Technology Ministry of Education Beijing100084 China The National Key Laboratory of Aerospace Power System and Plasma Technology Xi'an Jiaotong University Xi’an710049 China School of Mechanical Engineering Xi'an Jiaotong University Xi’an710049 China Department of Materials Science and Engineering The Pennsylvania State University University ParkPA16802 United States

This study investigates the improvement of plasticity in body-centered cubic magnesium (Mg)-lithium (Li)-aluminum (Al) alloys, crucial for lightweight structural applications. The ternary Mg-Li-Al alloys exhibits high strength but low ductility. Precipitates at grain boundaries in these alloys, linked to reduced plasticity, are examined for their crystal structure and composition. Advanced microscopic techniques reveal the transformation of precipitates and the development of specific structures at grain boundaries. Thermodynamics of element diffusion at grain boundaries are explored through first-principles calculations, and a phase-field simulation models precipitate evolution. Molecular dynamics simulations elucidate nanoscale mechanisms governing the transition from brittle to ductile fracture modes during artificial aging. The D03-Mg3Al at grain boundaries is a brittle phase, and through a 170°C aging treatment, it induces the precipitation of lamellar α-Mg phase with D03-Mg3Al as nucleation sites. The occupancy energy of Al atoms at Li sites in α-Mg is found to be lower than that in D03-Mg3Al, leading to the dissolution of D03-Mg3Al. The α-Mg, characterized by a stronger metallic nature, exhibits a better-matched modulus with the matrix and enhanced dislocation mobility. The precipitation of α-Mg plays a pivotal role in significantly improving the ductility of the alloy. This work contributes to the understanding of the complex interplay between alloy composition, grain boundary precipitates, and plasticity, as well as brings insights to guide interfacial control in the development of advanced Mg-Li-Al alloys for structural applications. © 2024, The Authors. All rights reserved.

关键词： Grain boundaries

来源：评论

学校读者我要写书评

暂无评论

Deadbeat Current Predictive Control for PMSM Drives Based on a Single FPGA with Digital Implementation Optimization

Deadbeat Current Predictive Control for PMSM Drives Based on...

引用

Workshop on Predictive Control of Electrical Drives and power Electronics (PRECEDE)

作者： Zhe Chen Haiyi Fang Donghua Wu Ming Yan Xuxuan Zhang Guangzhao Luo School of Automation Northwestern Polytechnical University Xi'an China Aviation Key Laboratory of Science and Technology on Aerospace Power Systems Avic Shaanxi Aero Electric Co. Ltd. Xi'an China

ISBN: (纸本)9781665425582

This paper proposes a field programmable gate arrays (FPGA) digital implementation of the deadbeat current predictive control (DCPC) of permanent magnet synchronous motor (PMSM) with a sliding mode disturbance observer (SMDO). To fulfill the fast sampling and controller-integration requirements of the proposed control algorithm, a FPGA is preferred. With the flexible structure of FPGA, the motor system realizes one-step delay compensation conveniently and improves the dynamic performance as well. The designed maximized parallel pipeline architecture optimizes the computational time of the proposed current control method. The experimental in PMSM drives results that the proposed FPGA implementation achieves high performance with balanced resources consumption.

关键词： Current control Pipelines Computer architecture Logic gates Synchronous motors Permanent magnet motors Prediction algorithms

来源：评论

学校读者我要写书评

暂无评论

Design and performance analysis of an airborne miniature vapor compression refrigerator for extreme temperature environments

引用

Applied Thermal Engineering 2025年 274卷

作者： Mou, Xinzhu Li, Yexiang Zhong, Hao Xu, Sheng Zhang, Jingyang College of Astronautics Nanjing University of Aeronautics and Astronautics Nanjing210016 China Aviation Key Laboratory of Science and Technology on Aero Electromechanical System Integration Nanjing211102 China Beijing Aerospace Technology Research Institute Beijing100074 China

High-performance aircraft encounter dynamic temperature fluctuations during missions, necessitating reliable thermal management systems. This study presents a miniature vapor compression refrigeration (MVCR) system designed for high-performance aircraft, which are subjected to extreme temperature variations during missions. The MVCR system is crucial for maintaining the reliability of onboard precision components, such as infrared detectors and high-power electronics, under harsh conditions. Addressing the limitations of existing systems, such as large size and low performance, this paper introduces a compact, lightweight MVCR system with dimensions of 350 mm × 200 mm × 100 mm and a weight of 2 kg. It delivers a cooling capacity of over 150 W and a coefficient of performance (COP) of 1.76, ensuring effective temperature control in extreme environments (-20 to 70 °C). The study investigates the effects of compressor speed, thermal load, and ambient temperature on the system's performance, analysing both steady and transient cooling processes. The reliability and temperature control capabilities of MVCR system are evaluated across a wide temperature range, with a focus on elevated and extreme conditions. Control strategies are developed to optimize temperature regulation under varying environmental temperatures, and their effectiveness is validated through experiments. The results confirm the system's ability to maintain equipment temperatures within operational limits under diverse thermal loads and ambient conditions. This study offers pivotal insights into ensuring the reliable operation of temperature-sensitive equipment within complex thermal environments, specifically catering to the needs of aerospace and refrigeration industries. © 2025

关键词： Vapor compression refrigeration

来源：评论

学校读者我要写书评

暂无评论

Innovative SAR-optical data fusion for reflectance time series reconstruction in vegetation-covered regions

引用

International Journal of Applied Earth Observation and Geoinformation 2025年 140卷

作者： Liu, Shuaijun Chen, Hui Tang, Kai Chen, Yang Shu, Hongtao Zan, Tianyu Xue, Yong Chen, Jin Emergency Management College Nanjing University of Information Science and Technology Jiangsu Nanjing 210044 China State Grid Electric Power Engineering Research Institute Co. LTD Beijing 100069 China State Key Laboratory of Remote Sensing Science Institute of Remote Sensing Science and Engineering Faculty of Geographical Science Beijing Normal University Beijing 100875 China Aerospace Information Research Institute Chinese Academy of Sciences Beijing 100875 China Institute of Land Surface System and Sustainable Development Faculty of Geographical Science Beijing Normal University Beijing 100875 China

Frequent cloud cover leads to gaps in remote sensing image time series, posing significant challenges for agriculture, grassland, and forest monitoring applications. This study proposes an innovative method to generate reflectance time series to address this issue, enhancing data reliability and application scope. We adopted a lightweight reconstruction model based on the architecture of deep learning. This model integrates the gapped Sentinel-2 reflectance time series caused by cloud cover with Sentinel-1 synthetic aperture radar (SAR) data to produce continuous high-density time series data. During the model training and evaluation, we selected time series image data from Sentinel-1 and Sentinel-2 in China and the United States, covering various typical geographical and climatic environments. The experimental results indicate that the proposed method performs excellently, significantly improving the completeness and accuracy of reflectance data, especially under conditions of prolonged cloud contamination leading to data gaps. To further validate the practical application of the model, we conducted a test in the grassland region of Mongolia to restore surface burnt areas. The results showed that this method performs excellently in restoring and detecting changes in burnt areas, significantly improving the accuracy and efficiency of detection. In summary, the method proposed in this study provides an effective solution to the problem of gaps in remote sensing image time series caused by cloud cover. This method not only enhances the reliability and practicality of remote sensing data but also demonstrates its broad potential and application prospects in various downstream applications, especially in fields such as agricultural monitoring and grassland disturbance detection. © 2025 The Author(s)

关键词： Convolutional network Long shot term memory Reconstruction Reflectance data SAR Time Series Vegetation-Covered

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：