检索结果-内蒙古大学图书馆

Research on Manipulation Strategy of Quad Tilt-Rotor

Transactions of Nanjing University of Aeronautics and Astronautics 2020年第S01期37卷 1-8页

作者： WANG Zhigang LYU Zhichao LI Jianbo Yangzhou Collaborative Innovation Research Institute Shenyang Aircraft Design&Research InstituteYangzhou 225000P.R.China National Key Laboratory of Science and Technology on Rotorcraft Aerodynamic College of Aerospace EngineeringNanjing University of Aeronautics and AstronauticsNanjing 210016P.R.China

Aiming at the complex tilting process of quad tilt-rotor(QTR)transition mode,this paper studies the manipulation strategy in transition mode to solve the problem of manipulation redundancy and coupling in transition mode of quad tilt *** variations of the manipulation derivative are analyzed in the tilting *** the flight control simulation and flight test of the quad tilt-rotor,the validity of the control system and the rationality of the manipulation strategy are verified.

关键词： quad tilt-rotor manipulation strategy flight test simulation

来源：评论

学校读者我要写书评

暂无评论

RepEC-Duet: Ensure High Reliability and Performance for Deduplicated and Delta-Compressed Storage systems

RepEC-Duet: Ensure High Reliability and Performance for Dedu...

引用

IEEE International Conference on Computer design: VLSI in Computers and Processors, (ICCD)

作者： Chunxue Zuo Fang Wang Ping Huang Yuchong Hu Dan Feng Wuhan National Laboratory for Optoelectronics Key Laboratory of Information Storage System (School of Computer Science and Technology Huazhong University of Science and Technology) Ministry of Education of China Wuhan China Huazhong University of Science and Technology Wuhan China Department of Computer and Information Sciences Temple University USA

Data deduplication is a widely deployed technique to remove duplicate content to save storage space, which is however incapable of eliminating the redundancy between nonidentical but similar data blocks. To achieve further space savings in deduplicated storage systems, delta compression is employed to compress post-deduplication data. Both deduplication and delta compression introduce content references among blocks, which inevitably undermines the reliability of deduplicated and delta compressed storage systems. To ensure better reliability, existing approaches utilize either replication or erasure codes to redundantly distribute data across multiple nodes. In deduplicated and delta compressed storage systems, we observe that delta compressed chunks (DCCs) are far smaller than regular chunks called non-DCCs. Motivated by this observation, we suggest a straightforward approach in which replication is used to protect DCCs and erasure code is deployed to protect non-DCCs. However, we need to address two critical challenges to ensure this solution effective. First, the random placement of DCCs replicas destroys cache locality. Second, the separate and individual recovery and restore cache could cause storage containers to be accessed repeatedly. To address these two challenges, in this paper, we propose RepEC-Duet which employs both replication and erasure codes to ensure high reliability and performance for deduplicated and delta-compressed storage systems. RepEC-Duet introduces a delta-utilization-aware filter to select and replicate containers based on the percentage of DCCs in the containers to maintain cache locality. Moreover, to avoid unnecessary container reads, we design a cooperative cache scheme that is aware of both failure recovery and regular restore cache. Our experimental results based on three real-world datasets demonstrate that RepEC-Duet significantly improves the restore performance by 26%-59%, and reduces the storage overhead by 54%-98% than the e

关键词： Containers Distributed databases Decoding Reliability engineering Redundancy system performance

来源：评论

学校读者我要写书评

暂无评论

Surrogate-based optimization method applied to multidisciplinary design optimziation architectures 31

Surrogate-based optimization method applied to multidiscipli...

引用

31st Congress of the International Council of the Aeronautical sciences, ICAS 2018

作者： Xu, Chen-Zhou Han, Zhong-Hua Zhang, Ke-Shi Song, Wen-Ping Aerodynamic and Multidisciplinary Design Optimization Group National Key Laboratory of Science and Technology on Aerodynamic Design and Research Northwestern Polytechnical University Xi'an710072 China

ISBN: (纸本)9783932182884

During the past three decades, various multidisciplinary design optimization (MDO) architectures have been developed, using different ways of dealing with interactions between disciplines, which can be solved by optimization algorithms. In the field of aircraft design optimization, as the complexity of system increases, conventional optimization algorithms applied in MDO architecture exhibit many drawbacks, such as low efficiency, poor robustness or easily getting trapped in a local extra. In this paper, a newly developed surrogate-based optimization (SBO) method is applied to replace traditional optimization algorithms in the MDO architectures so that the efficiency of solving MDO problems can be dramatically improved. To demonstrate its effectiveness, a benchmark MDO test case and Speed Reducer MDO case are employed. It shows that the efficiency of SBO is two-order higher than that of genetic algorithm and the optimization results are better than that obtained by gradient-based algorithm. Besides, SBO is applied to the aerodynamic/structural integrated design of a transport wing in MDF architecture. The weight of the wing is reduced by 30.32% while its aerodynamic performance is retained at a cruise condition. © 31st Congress of the International Council of the Aeronautical sciences, ICAS 2018. All rights reserved.

关键词： Efficiency

来源：评论

学校读者我要写书评

暂无评论

Low Profile Microsrip Antenna with Broadside Radiation Patterns and Low Cross Polarizations 4

Low Profile Microsrip Antenna with Broadside Radiation Patte...

引用

2019 4th International Conference on Intelligent Computing and Signal Processing, ICSP 2019

作者： Lai, Ping Xu, Chao Xu, Zhuo Luo, Kang Unit.32382 of PLA Wuhan Hubei430311 China China Fire Rescue College Beijing Province102230 China Comprehensive Information Guarantolice Corps Nanning Guangxi530308 China National Key Laboratory of Science and Technology Vessel Integrated Power System University Wuhan Hubei430030 China

A low profile microstrip antenna with adjustable bandwidth around 3 GHz is proposed. The compact antenna consists of a square patch with a square aperture to tune the resonance center frequency. The input impedance bandwidth is about 2.67% with stable gain around 3.2 dBi. Besides, the 3-dB beam width is about 100°. Both the side-fed and bottom-fed modes are analyzed. According to the simulation, good broadside radiation patterns with low cross polarizations are observed in the two principal planes. The detailed design considerations are described and discussed while the surface current distribution and radiation characteristics are analyzed. This design is suitable for mobile wireless communication. © 2019 IOP Publishing Ltd. All rights reserved.

关键词： Microstrip antennas

来源：评论

学校读者我要写书评

暂无评论

Inchworm-inspired soft climbing robot using microspine arrays

Inchworm-inspired soft climbing robot using microspine array...

引用

2019 IEEE/RSJ International Conference on Intelligent Robots and systems (IROS)

作者： Qiqiang Hu Erbao Dong Gang Cheng Hu Jin Jie Yang Dong Sun CAS Key Laboratory of Mechanical Behavior and Design of Materials University of Science and Technology of China Hefei China CAS Key Laboratory of Mechanical Behavior and Design of Materials University of Science and Technology of China Hefei PRC Anhui Beijing Key Laboratory of Intelligent Space Robotic Systems Technology and Applications Beijing Institute of Spacecraft System Engineering Beijing PRC Department of Biomedical Engineering City University of Hong Kong Hong Kong SAR

Animals in nature, such as geckos, inchworms, and felines can climb on various surfaces using different mechanisms and serve as references for the study of bio-inspired robots. This paper presents an inchworm-inspired climbing robot that consists of soft body and feet. The soft robot is actuated by shape memory alloy wires and utilizes microspine arrays to attach its feet to rough or soft surfaces. A series of experiments to test the functionality of the feet and torso of the designed robot have verified the theoretical feasibility of the robot. Results have shown that the designed bio-inspired robot can climb on inclined or vertical curved surfaces and flat surfaces. The robot can also adapt to the underwater environment. Thus, this robot has great potential for various applications such as pipeline inspection.

关键词：

来源：评论

学校读者我要写书评

暂无评论

MRPB 1.0: A unified benchmark for the evaluation of mobile robot local planning approaches

arXiv

引用

arXiv 2020年

作者： Wen, Jian Zhang, Xuebo Bi, Qingchen Pan, Zhangchao Feng, Yanghe Yuan, Jing Fang, Yongchun The Institute of Robotics and Automatic Information System College of Artificial Intelligence Nankai University Tianjin300350 China The Tianjin Key Laboratory of Intelligent Robotics Nankai University Tianjin300350 China The School of Marine Science and Technology Northwestern Polytechnical University Xi'an710072 China The Faculty of Robot Science and Engineering Northeastern University Shenyang110000 China The College of Systems Engineering National University of Defense Technology Changsha410073 China

Local planning is one of the key technologies for mobile robots to achieve full autonomy and has been widely investigated. To evaluate mobile robot local planning approaches in a unified and comprehensive way, a mobile robot local planning benchmark called MRPB 1.0 is newly proposed in this paper. The benchmark facilitates both motion planning researchers who want to compare the performance of a new local planner relative to many other state-of-the-art approaches as well as end users in the mobile robotics industry who want to select a local planner that performs best on some problems of interest. We elaborately design various simulation scenarios to challenge the applicability of local planners, including large-scale, partially unknown, and dynamic complex environments. Furthermore, three types of principled evaluation metrics are carefully designed to quantitatively evaluate the performance of local planners, wherein the safety, efficiency, and smoothness of motions are comprehensively considered. We present the application of the proposed benchmark in two popular open-source local planners to show the practicality of the benchmark. In addition, some insights and guidelines about the design and selection of local planners are also provided. The benchmark website [1] contains all data of the designed simulation scenarios, detailed descriptions of these scenarios, and example code. Copyright © 2020, The Authors. All rights reserved.

关键词： Mobile robots

来源：评论

学校读者我要写书评

暂无评论

LBE simulation of impinging stream inside a T-junction mixer

引用

science China(Technological sciences) 2018年第7期61卷 1038-1055页

作者： XU WenKai ZHANG QingChen GUI Nan ZHANG ZiWei College of Mechanical and Transportation Engineering China University of PetroleumBeijing 102249China Beijing National Railway Research&Design Institute of Signal&Communication Co. Ltd Institute of Nuclear and New Energy Technology Collaborative Innovation Center of Advanced Nuclear Energy TechnologyKey Laboratory of Advanced Reactor Engineering and Safety of Ministry of EducationTsinghua UniversityBeijing 100084China

Lattice Boltzmann Equation(LBE) method is utilized to simulate impinging stream(IS) in a T-junction mixer using a TD2G9 model. It aims to investigate the influence of Reynolds number(Re), aspect ratio of outlet diameter to inlet diameter, ratio of opposite inlet velocities, and the thermal boundary conditions on flow, mixing and heat transfer characteristics. In particular, the vortex evolution, velocity distribution, mixing index and Nusselt number(Nu) distribution in the T-junction mixer are explored in details. Four types of vortices and flow regimes are observed. The instantaneous and time-averaged flow and thermal fields,including vortex structure, transition of flow regimes, streamline and the Nusselt number distribution are discussed. Distinct quantitative transitions, even for dramatic change, are observed near the critical Re. At a low or moderate aspect ratio, the symmetric coherent structure is observed in an unstable flow regime. At a larger aspect ratio, the flow in the T-mixer becomes turbulent and asymmetric. The unequal injections velocities of the nozzles impose significant influence on the flow structure,mixing and heat transfer in vertical tube. Using larger difference between the two inlet velocities can result in more obvious change in flow characteristics. Moreover, mixing index is found to be valid in evaluating the mixing degree under a sinusoidal inlet velocity.

关键词： impinging flow lattice Boltzmann method T-junction heat transfer flow characteristics

来源：评论

学校读者我要写书评

暂无评论

Characteristic Analysis of Monobit Signal

引用

Journal of Physics: Conference Series 2021年第1期1738卷

作者： Pengfei Ji Xiao Yang Chenglong Xia Huan Lv State Key Laboratory of Complex Electromagnetic Environment Effects on Electronics and Information System Technology National University of Defense Technology Changsha Hunan 410073 China. School of Electronic Science National University of Defense Technology Changsha Hunan 410073 China. Military Representative Office of Rocket Force in Changsha Changsha Hunan 4100205 China.

This paper analyzes the characters of monobit signals and gives the reason why the spurious free dynamic ranges (SFDR) of monobit signals is much lower than those of multi-bit signals. According to our analysis and simulation, if the third harmonic of a monobit signal can be filtered, the SFDR of it can be improved well. Therefore, we give the way to obtain the desired band, which do not contain any third harmonics, and the simulation results are in agreement with our design. Such way can be used to improve the performance of monobit digital receivers in engineering.

关键词：

来源：评论

学校读者我要写书评

暂无评论

Processing of a comprehensive windowed multipole library via vector fitting

Processing of a comprehensive windowed multipole library via...

引用

2018 International Conference on Physics of reactors: reactor Physics Paving the Way Towards More Efficient systems, PHYSOR 2018

作者： Liang, Jingang Peng, Xingjie Liu, Shichang Josey, Colin Forget, Benoit Smith, Kord Department of Nuclear Science and Engineering Massachusetts Institute of Technology CambridgeMA02139 United States Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China ChengduSichuan610000 China Department of Engineering Physics Tsinghua University Beijing100084 China

ISBN: (纸本)9781713808510

The windowed multipole method is a promising technique to efficiently perform Doppler broadening of nuclear cross section data and has so far been based on the conversion of resolved resonance parameters to the pole representation. However, 40% of ENDF/B-VII. 1 nuclides cannot be directly converted in windowed multipole format because some nuclides are provided directly as point-wise data in the evaluation or the presence of non-smooth point-wise data that prevents the transformation. A new approach based on Vector Fitting technique was recently investigated to convert point-wise cross section data to poles and residues. This paper presents a generalized Vector Fitting algorithm which is able to generate optimized multipole parameters from ENDF point-wise data and applicable to a wide range of nuclides. Using this algorithm, a comprehensive windowed multipole library which contains all ENDF/B-VII.l nuclides was produced for the first time. Accuracy of the library was demonstrated by microscopic cross section comparisons at different temperatures, and calculation results of the BEAVRS benchmark were performed to demonstrate its applicability to realistic problems. © 2018 International Conference on Physics of reactors, PHYSOR 2018: reactor Physics Paving the Way Towards More Efficient systems. All rights reserved.

关键词： Doppler effect

来源：评论

学校读者我要写书评

暂无评论

Research on Active Disturbance Rejection Control Method for Electro-hydraulic Servo Loading system with Considering Clearance Disturbance

Research on Active Disturbance Rejection Control Method for ...

引用

International Conference on Fluid Power and Mechatronics (FPM)

作者： Qiang Chen Fang Yang Dan-dan LIU Yu-jun Xue School of Mechatronics Engineering Henan University of Science & Technology Luoyang China Henan Key Laboratory of Mechanical Design and Transmission System Henan University of Science & Technology Luoyang China Luoyang LYC Rearing Co. Ltd Luoyang China

ISBN: (数字)9781728103112

ISBN: (纸本)9781728103129

In the test of high-speed rail bearings, the electro- hydraulic servo-loading system is commonly used to simulate the actual alternating loading for the bearing. Due to the existence of the loading mechanism clearance and the transmission shaft system matching clearance, the loading system has a certain nonlinear displacement disturbance. Combined with the nonlinear characteristics of the electro-hydraulic servo system, the dynamic response characteristics and steady-state control accuracy of the force loading are seriously affected. To this end, the Active Disturbance Rejection control (ADRC) method is used to identify and compensate the gap disturbances using the feedback information of the extended state observer, and the tracking differentiator and feedback control rate are designed to improve the system response speed and suppress overshoot. The control method is applied to the control model of high-speed rail bearing electro-hydraulic servo-loading system. The simulation results show that the control method can achieve good control effect, and the anti-disturbance capability, response speed and steady-state performance of the system are significantly improved.

关键词： Loading Force Servomotors Laser excitation Electron tubes Hydraulic systems Pressure sensors

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：