检索结果-内蒙古大学图书馆

Dynamic characteristics of a shrouded blade with impact and friction

Frontiers of Mechanical engineering 2020年第2期15卷 209-226页

作者： Xumin GUO Jin ZENG Hui MA Chenguang ZHAO Lin QU Bangchun WEN School of Mechanical Engineering and Automation Northeastern UniversityShenyang 110819China Key Laboratory of Vibration and Control of Aero-Propulsion System Ministry of Education Northeastern UniversityShenyang 110819China

A simplified computational model of a twisted shrouded blade with impact and friction is *** this model,the shrouded blade is simulated by a flexible Timoshenko beam with a tip-mass,and the effects of centrifugal stiffening,spin softening,and Coriolis force are *** force is simulated using a linear spring model,and friction force is generated by a tangential spring model under sticking state and a Coulomb friction model under sliding *** proposed model is validated by a finite element ***,the effects of initial gap and normal preload,coefficient of friction,and contact stiffness ratio(the ratio of tangential contact stiffness to normal contact stiffness)on system vibration responses are *** show that resonant peaks become inconspicuous and impact plays a dominant role when initial gaps are large between adjacent *** contrast,in small initial gaps or initial normal preloads condition,resonant speed increases sharply,and the optimal initial normal preloads that can minimize resonant amplitude becomes *** of friction affects the optimal initial normal preload,but it does not affect vibration responses when the contact between shrouds is under full *** resonant amplitude decreases with the increase of contact stiffness ratio,but the optimal initial normal preload is unaffected.

关键词： twisted shrouded blade dynamic analysis impact friction separate-stick-slip motion

来源：评论

学校读者我要写书评

暂无评论

Dynamic modeling and coupling characteristics of rotating inclined beams with twisted-shape sections

引用

Frontiers of Mechanical engineering 2020年第3期15卷 374-389页

作者： Jin ZENG Chenguang ZHAO Hui MA Bangchun WEN School of Mechanical Engineering and Automation Northeastern UniversityShenyang 110819China Key Laboratory of Vibration and Control of Aero-Propulsion System Ministry of Education Northeastern UniversityShenyang 110819China

In the existing literature, most studies investigated the free vibrations of a rotating pre-twisted cantilever beam;however, few considered the effect of the elastic-support boundary and the quantification of modal coupling degree among different vibration directions. In addition, Coriolis, spin softening, and centrifugal stiffening effects are not fully included in the derived equations of motion of a rotating beam in most literature, especially the centrifugal stiffening effect in torsional direction. Considering these deficiencies, this study established a coupled flapwise–chordwise–axial–torsional dynamic model of a rotating double-tapered, pre-twisted, and inclined Timoshenko beam with elastic supports based on the semi-analytic method. Then, the proposed model was verified with experiments and ANSYS models using Beam188 and Shell181 elements. Finally, the effects of setting and pre-twisted angles on the degree of coupling among flapwise, chordwise, and torsional directions were quantified via modal strain energy ratios. Results showed that 1) the appearance of torsional vibration originates from the combined effect of flapwise–torsional and chordwise–torsional couplings dependent on the Coriolis effect, and that 2) the flapwise–chordwise coupling caused by the pure pre-twisted angle is stronger than that caused by the pure setting angle.

关键词： elastic-support boundary pre-twisted beam semi-analytic method modal strain energy ratio torsional vibration

来源：评论

学校读者我要写书评

暂无评论

Omnidirectional Sound Wave Absorption Based on the Multipole Acoustic Meta-Materials

SSRN

引用

SSRN 2024年

作者： Bai, Xiaotian Xiao, Zhaoyang Shi, Huaitao Zhang, Ke Luo, Zhong Wu, Yuhou School of Mechanical Engineering Shenyang Jianzhu University Liaoning Shenyang110168 China Joint International Research Laboratory of Modern Construction Engineering Equipment and Technology Liaoning Shenyang110168 China Key Laboratory of Vibration and Control of Aero-Propulsion System Ministry of Education Northeastern University Liaoning Shenyang110167 China

Acoustic meta-materials have become a hot topic in rotary equipment sound absorption with advantages of small size and additional mass, but the effectiveness is significantly limited by the incident angle and the absorption performance is not good in random sound fields. This paper proposes a multipole acoustic meta-material(MPAMM) that can be applied in omnidirectional sound wave absorption, which is composed of unit cells with different orientations. The single cell is designed as a double-cavity labyrinth structure, and the unit cells are distributed uniformly in a circumference to adapt to incident waves from different directions. The absorption performance is compared with the structure of same-oriented distribution, and parametric studies are carried out for the change of sound absorption performance of MPAMM. Results show that the sound absorption coefficient of MPAMM maintains over 0.8 when facing with sound waves from different directions, and the frequency range changes with the entrance width, channel width and cell size. Experimental results have verified the excellent performance of the proposed structure, which provides new approaches for effective control of sound radiation. © 2024, The Authors. All rights reserved.

关键词： Acoustic fields

来源：评论

学校读者我要写书评

暂无评论

Object relationship graph reasoning for object detection of remote sensing images 6

Object relationship graph reasoning for object detection of ...

引用

6th International Conference on Image, Vision and Computing, ICIVC 2021

作者： Li, Zeng Liu, Yifan Liu, Jingdong Yuan, Ye Raza, Asif Huo, Hong Fang, Tao Department of Automation Shanghai Jiao Tong University Shanghai China Key Laboratory of System Control and Information Processing Ministry of Education of China Shanghai China Shanghai Engineering Research Center of Intelligent Control and Management Shanghai China

ISBN: (纸本)9781665443685

In recent years, deep learning has been successfully applied in object detection of remote sensing images, due to its powerful feature extraction and representation capabilities. However, it usually ignores the relationships among different objects, which greatly hinders the further improvement of the detection precision. In this paper, a novel object relationship graph reasoning deep learning method is proposed for object detection of remote sensing images. The reasoning is carried out on a graph constructed by region proposals. It mainly contains three modules for relationship generation in consideration of different factors that related to object detection: 1) Location-based relationship generation module (LRGM) aims to find spatial relationships among objects according to their positions;2) Feature-based relationship generation module (FRGM) focuses on mining semantic relationships among objects according to their appearances that implied in feature maps and 3) Class-dependent relationship generation module (CRGM) introduces class dependencies into the relationship generation process. Class dependencies are the prior knowledge that is obtained by computing class co-occurrence. The experimental results on a public twenty-class remote sensing object detection dataset have shown that the proposed method has better detection performance compared to other object detection deep networks with no considering object relationships. © 2021 IEEE.

关键词： Object detection

来源：评论

学校读者我要写书评

暂无评论

Multi-target tracking control system of phased array antenna with mechanical scanning and beam scanning method

Multi-target tracking control system of phased array antenna...

引用

Fully Actuated system Theory and Applications (CFASTA), Conference on

作者： Jijun Ma Dewei Li Lianghai Li Shibei Xue Yuning Wang Jun Jia Department of Automation Key Laboratory of System Control and Information Processing Ministry of Education of China Shanghai Engineering Research Center of Intelligent Control and Management Shanghai Jiao Tong University Shanghai China Beijing Research Institute of Telemetry Beijing China

In the field of telemetry, track, and command system, this study presents a phased array antenna control system for achieving multi-target tracking tasks through a set of systems. Firstly, electric beam scanning of a planar array phased array antenna is used in this paper to implement multi-target tracking. In addition, the phased array antenna is mounted on the antenna pedestal, which can operate on the azimuth and elevation mechanical axes. Thirdly, the mechanical scanning method of the azimuth-elevation antenna pedestal and the beam scanning method of the phased array antenna are combined to realize multi-target tracking tasks. Finally, the experiments of flight tracking are completed by employing the technique of UAV tagging, and the results validate the viability of the system.

关键词：

来源：评论

学校读者我要写书评

暂无评论

Computation and investigation of mode characteristics in nonlinear system with tuned/mistuned contact interface

引用

Frontiers of Mechanical engineering 2020年第1期15卷 133-150页

作者： Houxin SHE Chaofeng LI Qiansheng TANG Hui MA Bangchun WEN School of Mechanical Engineering and Automation Northeastern UniversityShenyang 110819China Key Laboratory of Vibration and Control of Aero-Propulsion System(Ministry of Education) Northeastern UniversityShenyang 110819China

This study derived a novel computation algorithm for a mechanical system with multiple friction contact interfaces that is well-suited to the investigation of nonlinear mode characteristic of a coupling *** procedure uses the incremental harmonic balance method to obtain the nonlinear parameters of the contact ***,the computed nonlinear parameters are applied to rebuild the matrices of the coupling system,which can be easily solved to calculate the nonlinear mode characteristics by standard iterative ***,the derived method is applied to a cycle symmetry system,which represents a shaft–disk–blade system subjected to dry ***,this study analyzed the effects of the tuned and mistuned contact features on the nonlinear mode *** results prove that the proposed method is particularly suitable for the study of nonlinear characteristics in such nonlinear systems.

关键词： coupling vibration nonlinear mode original algorithm contact interface

来源：评论

学校读者我要写书评

暂无评论

Nash Equilibrium Estimation of Non-Cooperative Games with Time-Varying Delay

Nash Equilibrium Estimation of Non-Cooperative Games with Ti...

引用

Chinese Automation Congress (CAC)

作者： Ziqi Liu Chao Zhai China University of Geosciences Wuhan Campus School of Automation Hubei Key Laboratory of Advanced Control and Intelligent Automation for Complex Systems Engineering Research Center of Intelligent Technology for Geo-Exploration Ministry of Education Wuhan China

Time delay has great impacts on the stability and the reliability and real-time of the communication of multi-agent systems. In multi-agent communication network, due to network congestion, transmission distance and other factors, there are various communication delays. In this paper, we study the deviation of convergence value after adding time-varying delays under gradient descent method, and the upper bound related to delay time is estimated. This upper bound can be used to analyze the magnitude of deviation under different time delays and minimize the loss caused by delays, and provide more explicit information for system optimization and resource allocation. Numerical simulation is conducted to verify the proposed approach.

关键词：

来源：评论

学校读者我要写书评

暂无评论

Diving into underwater: segment anything model guided underwater salient instance segmentation and a large-scale dataset 24

Diving into underwater: segment anything model guided underw...

引用

Proceedings of the 41st International Conference on Machine Learning

作者： Shijie Lian Ziyi Zhang Hua Li Wenjie Li Laurence Tianruo Yang Sam Kwong Runmin Cong Hainan University The Hong Kong University of Science and Technology (Guangzhou) Hainan University and Key Laboratory of New Generation Artificial Intelligence Technology & Its Interdisciplinary Applications (Southeast University) Ministry of Education China Hainan University and Huazhong University of Science and Technology and St. Francis Xavier University LIngnan University School of data science Hong Kong Shandong University School of Control Science and Engineering and Key Laboratory of Machine Intelligence and System Control Ministry of Education Jinan China

With the breakthrough of large models, Segment Anything Model (SAM) and its extensions have been attempted to apply in diverse tasks of computer vision. Underwater salient instance segmentation is a foundational and vital step for various underwater vision tasks, which often suffer from low segmentation accuracy due to the complex underwater circumstances and the adaptive ability of models. Moreover, the lack of large-scale datasets with pixel-level salient instance annotations has impeded the development of machine learning techniques in this field. To address these issues, we construct the first large-scale underwater salient instance segmentation dataset (USIS10K), which contains 10,632 underwater images with pixel-level annotations in 7 categories from various underwater scenes. Then, we propose an Underwater Salient Instance Segmentation architecture based on Segment Anything Model (USIS-SAM) specifically for the underwater domain. We devise an Underwater Adaptive Visual Transformer (UA-ViT) encoder to incorporate underwater domain visual prompts into the segmentation network. We further design an out-of-the-box underwater Salient Feature Prompter Generator (SFPG) to automatically generate salient prompters instead of explicitly providing foreground points or boxes as prompts in SAM. Comprehensive experimental results show that our USIS-SAM method can achieve superior performance on USIS10K datasets compared to the state-of-the-art methods. Datasets and codes are released on Github.

关键词：

来源：评论

学校读者我要写书评

暂无评论

Long-range chaotic Brillouin optical correlation domain analysis with more than one million resolving points

引用

Advanced Photonics Nexus 2023年第3期2卷 104-113页

作者： Yahui Wang Xinxin Hu Lintao Niu Hui Liu Jianzhong Zhang Mingjiang Zhang Taiyuan University of Technology Ministry of EducationKey Laboratory of Advanced Transducers and Intelligent Control SystemTaiyuanChina Taiyuan University of Technology College of PhysicsTaiyuanChina Shanxi-Zheda Institute of Advanced Materials and Chemical Engineering TaiyuanChina

We propose and experimentally demonstrate a long-range chaotic Brillouin optical correlation domain analysis by employing an optimized time-gated scheme and differential denoising configuration,where the number of effective resolving points largely increases to more than one *** deterioration of the chaotic Brillouin gain spectrum(BGS)and limitation of sensing range owing to the intrinsic noise structure,resulting from the time delay signature(TDS)and nonzero background of chaotic laser,is theoretically *** optimized time-gated scheme with a higher extinction ratio is used to eliminate the TDS-induced *** signal-to-background ratio of the measured BGS is enhanced by the differential denoising scheme to furthest remove the accumulated nonzero noise floor along the fiber,and the pure chaotic BGS is ulteriorly obtained by the Lorentz ***,distributed strain sensing along a 27.54-km fiber with a 2.69-cm spatial resolution is experimentally demonstrated,and the number of effective resolving points is more than 1,020,000.

关键词： chaos distributed fiber sensing stimulated Brillouin scattering long-range sensing

来源：评论

学校读者我要写书评

暂无评论

Study on the thermal hazards of anionic surfactant AES on lignite via experiments and calculations

引用

Journal of Molecular Liquids 2024年 416卷

作者： Jiang, Bingyou Cui, Leyun Yu, Chang-Fei Lu, Kunlun Zhou, Yu Su, Mingqing Zhang, Yuqian Key Laboratory of Industrial Dust Prevention and Control & Occupational Health and Safety Ministry of Education Anhui University of Science and Technology Huainan232001 China School of Safety Science and Engineering Anhui University of Science and Technology Huainan232001 China China Academy of Safety Science and Technology Beijing100012 China Key Laboratory of Major Hazard and Chemical Industry Park System Safety Ministry of Emergency Management of China Beijing100012 China

Spray dust reduction is a commonly used dust reduction method in coal mines and has been widely adopted. However, the thermal stability of coal dust after being wetted by dust suppressants remains unknown. The work aimed to investigate the potential environmental hazards posed by the secondary dust dispersion resulting from the cracking of lump coal dust after being wetted by surfactants and subsequently air-dried. Lignite and AES were used as experimental samples. Use thermodynamic equations to analyze, calculate, and compare the changes in the average apparent activation energy of lignite before and after AES solution wetting. Compared with lignite before AES solution wetting, the combustion characteristic index of lignite decreased by 1.93 % after wetting, and before and after AES solution wetting, the average apparent activation energy of lignite calculated by reaction kinetics methods decreased by 7.6 %, 6.7 %, and 17.1 % respectively. FTIR analysis shows the proportion of aliphatic hydrocarbons in lignite after AES solution wetting has decreased compared with before wetting, and the proportion of oxygen-containing functional groups has shown an upward trend. The work elucidated the complex microscopic mechanisms underlying hazards caused by secondary dust dispersion, providing new scientific evidence for preventing and controlling coal dust explosion accidents. © 2024 Elsevier B.V.

关键词： Coal dust

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：