检索结果-内蒙古大学图书馆

Analysis of the Axial Fan Performance Mounted on a 4.5kW Aviation Motor

Analysis of the Axial Fan Performance Mounted on a 4.5kW Avi...

2021 International Conference on Mechanical Engineering, Intelligent Manufacturing and Automation technology, MEMAT 2021

作者： Liu, Bin Yu, Zhongjun Fu, Jia Chen, Zutao National Key Laboratory of Science and Technology on Vessel Integrated Power System Naval University of Engineering Wuhan430033 China

Integrating an axial flow fan with the rotor is a sufficient cooling method for high-speed and high power density motors. Different from the axial fan design work under ideal intake condition, i.e. the intake flow of the fan is axial and uniform, the flow in actual engineering is more complex, which means the flow characteristics of an integrated fan are changed and disturbed. It leads to a performance penalty of the fan, and in some conditions it makes the fan stall, so it is important to get a knowledge of the flow characteristics and the performance of the integrated fan. A certain 4.5kW aviation motor with integrated axial fan is taken as the research object. Firstly, the motor-fan coupling simulation model and ideal axial intake simulation model are established, in which the mass flow rates are same, then calculation is conducted. Secondly, the simulation results are analyzed and compared, focusing on the performance of the axial fan, especially the static pressure rise, and the conclusion is obtained that the static pressure rise in ideal axial intake situation is higher than that in coupling situation. Furthermore, the reasons for the characteristics change are explored, finding that the increase of flow turbulence due to the more complex wind road structure is the main cause for these changes. This paper investigates the flow characteristics and axial fan performance mounted a whole motor, making a contribution to better understand the changes in fan performance under motor-fan coupling situation. © Published under licence by IOP Publishing Ltd.

关键词： Fans

来源：评论

学校读者我要写书评

暂无评论

Research on Intelligent Fault Diagnosis Method of Planetary Gearbox Based on ITD and CNN

Research on Intelligent Fault Diagnosis Method of Planetary ...

引用

Prognostics and system Health Management Conference (PHM-Qingdao)

作者： Songsong Zhu Jiwei Chen Ruitong Xie Yuhao Song Mian Zhang Mengxiong Zhao Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control School of Mechanical Engineering Tianjin University of Technology Tianjin China National Demonstration Center for Experimental Mechanical and Electrical Engineering Education (Tianjin University of Technology) Tianjin China

ISBN: (数字)9798350354010

ISBN: (纸本)9798350354027

Accurate fault diagnosis of planetary gearboxes (PGs) is crucial for preventing equipment failures and extending their lifespan. To enhance the efficiency and accuracy of PG fault diagnosis, this paper proposes a novel method integrating intrinsic time scale decomposition (ITD) with convolutional neural network (CNN). The proposed method leverages the demodulation capability of ITD to decompose and reconstruct the original signal, effectively removing irrelevant noise and isolating core fault features, and the learning ability of CNN to accurately identify the fault features. Compared to methods relying on CNN only, the proposed method not only improves the computational efficiency but also achieves higher fault diagnosis accuracy.

关键词： Fault diagnosis Accuracy Computational modeling Noise Feature extraction Computational efficiency Convolutional neural networks Prognostics and health management Demodulation

来源：评论

学校读者我要写书评

暂无评论

In-Situ Study on Factors Impeding Dislocation Motion in Fe9cr1.5w0.4si F/M Steel During High Temperature Heating

SSRN

引用

SSRN 2023年

作者： Ding, Yifan Yuan, Fan Cao, Ziqi Ren, Jiacheng Li, Yuanmin Xin, Yong Ran, Guang College of Energy Xiamen University Xiamen361102 China Fujian Provincial Nuclear Energy Engineering Technology Research Center Xiamen361102 China Science and Technology on Reactor System Design Technology Laboratory Chengdu610213 China Nuclear Power Institute of China Chengdu610213 China

Plastic deformation is driven by the movement of dislocations on a microscopic scale, and the mobility of these dislocations determine the strength of the material. Forest dislocations and dislocation loops are often considered to be important factors that impede dislocation movement, but their effectiveness is called into question at high temperature. Here, in-situ heating was performed on irradiated Fe9Cr1.5W0.4Si ferritic martensitic steel in the temperature range of 873-923 K, and the interaction between dislocation lines and obstacles was investigated to reveal the mechanism that led to easier dislocation gliding. Dislocations tended to glide in several planes at the same time and only glided as a whole in one plane occasionally. It was discovered that dislocations usually glided in high index planes such as {123} planes. When moving dislocations intersected with forest dislocations, a new mechanism was found where the segments for different dislocations with the same Burgers vector could exchange, which was important for the moving dislocation to cut through the forest dislocations without decreasing their mobility. The reactions between dislocations and loops included absorption, break away and rebound. Meanwhile, statistical results indicated that the highest ratio was about 48% for the case where loops were restored and dislocations broke away, demonstrating that the loops were not strong obstacles when interacting with moving dislocations at high temperature. © 2023, The Authors. All rights reserved.

关键词： Chromium alloys

来源：评论

学校读者我要写书评

暂无评论

A Review of Circuit Models for GaN Power Devices

A Review of Circuit Models for GaN Power Devices

引用

china International Electrical and Energy Conference (CIEEC)

作者： Di Luo Xiaohu Liu Ruitian Wang Xin Li National Key Laboratory of Science Technology on Vessel Integrated Power System Naval University of Engineering Wuhan China Military Electrical Science and Technology Institute Naval University of Engineering Wuhan China

GaN devices offer superior performance over Si devices, such as higher mobility, breakdown voltage, switching speed and per-width power density. In the future, GaN devices are expected to surpass Si devices in almost all performance indicators, thereby achieving high-speed and efficient power electronic systems (PES). The model of GaN device is a useful and necessary tool to analyze and evaluate its impact on circuit and system performance, which can help researchers design new PES. This paper reviews latest advances on the models of GaN power devices, and discusses the working principles of GaN, the classification and contributions of GaN model, for understanding the significance of these recent developments. In addition, this paper also considers the challenges and problems encountered in the modeling and application of GaN devices, such as self-heating effect, trap effect and short channel effect, providing guidance for future modeling. This review helps readers understand and use the GaN model to achieve more effective design of GaN-based converters.

关键词：

来源：评论

学校读者我要写书评

暂无评论

Application of automated laser seam tracking straight seam welding technology in production

Application of automated laser seam tracking straight seam w...

引用

2024 International Conference on Precision Instruments and Optical Engineering, PIOE 2024

作者： Qin, Jingchuan Liu, Yongkai Hu, Haoran Liu, Xian Beijing AriTime Intelligent Control Co. Ltd. 6 Fufeng Road Fengtai District Beijing Science and Technology Park Beijing100070 China Automation Research And Design Institute Of Metallurgical Industry Co. LTD. 72 South Fourth Ring Road Fengtai District Beijing100070 China National Key Laboratory of Metallurgical Intelligent Manufacturing System Beijing100081 China Shanxi Limin Industrial Co. Ltd. TaiGu030812 China

ISBN: (纸本)9781510686120

In the manufacturing process of a specific type of conical cylinder, high-frequency argon arc welding is employed for butt welding. The uncertainty of the butt weld position relative to the welding gun results in excessive manual labor during production, leading to suboptimal product qualification rates;Consequently, the implementation of a fusion laser welding seam tracking automated control system was initiated. This system utilizes a PLC to gather various sensor data signals, control servomotors, valves, and motors, thereby establishing a comprehensive automated butt welding tracking control system. Ultimately, this achieves the goals of reducing labor costs, diminishing labor intensity, and enhancing both production efficiency and product quality. © 2024 SPIE.

关键词： Butt welding

来源：评论

学校读者我要写书评

暂无评论

Kinematic analysis and trajectory planning of two-limb 4-DOF high-speed parallel robot

Kinematic analysis and trajectory planning of two-limb 4-DOF...

引用

IEEE International Conference on Mechatronics and Automation

作者： Weihua Sun Yue Ma Changrui Li Bin Li Yansen Zhao Qi Liu Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control School of Mechanical Engineering Tianjin University of Technology Tianjin China National Demonstration Center for Experimental Mechanical and Electrical Engineering Education Tianjin University of Technology Tianjin China

ISBN: (数字)9798350388077

ISBN: (纸本)9798350388084

Focusing on the pick-and-place operation in the electronic, packaging, and other light industries, this paper proposed a new type 3T1R (T-Translation, R-Rotation) high-speed parallel robot with two limbs. Compared with other 4-DOF high-speed parallel robots with four limbs, its structure is simpler while the working space is larger, such that the potential for cheaper usage in the industry is achieved. The robot's kinematic analysis and trajectory planning, including key aspects, are also outlined here. Firstly, the robot's closed-loop constraint equation is established using the vector chain method. The displacement, velocity, and acceleration models are derived, and the Jacobian matrix is obtained. On this basis, the gate shape trajectory is planned using the 3-4-5 polynomial motion rule, such that the displacement, velocity, and acceleration of the driving joint are obtained using the kinematic models above. Ultimately, the accuracy of the kinematic models is confirmed by comparing the theoretical outcomes with the simulations carried out in SolidWorks. The study presented in this paper establishes a firm basis for the dimensional integration and the creation of a physical model of the robot.

关键词： Industries Solid modeling Parallel robots Trajectory planning Kinematics Logic gates Vectors

来源：评论

学校读者我要写书评

暂无评论

Progress of the unified wave-particle methods for non-equilibrium flows from continuum to rarefied regimes

引用

Acta Mechanica Sinica 2022年第6期38卷 1-25,I0001页

作者： Sha Liu Kun Xu Chengwen Zhong Institute of Extreme Mechanics Northwestern Polytechnical UniversityXi’an 710072China National Key Laboratory of Science and Technology on Aerodynamic Design and Research Northwestern Polytechnical UniversityXi’an 710072China Department of Mathematics Hong Kong University of Science and TechnologyHong KongChina Shenzhen Research Institute Hong Kong University of Science and TechnologyShenzhen 518057China

The predictions of the multiple-regime flows from continuum regime to free molecular regime are crucial for the aerodynamic design in a large number of engineering applications,such as the near-space craft,the ultra-low orbit spacecraft and the micro-electro-mechanical systems(MEMS).Since the essence of this multiple-regime problem is a complex system composed by different scales and mechanics,the modeling and numerical prediction of these multiple-regime flows are very challenging at both theoretical and practical ***,the single flow field with multiple flow regimes will make the problem extremly ***,this typical flow field is very common in hypersonic application and important for the development of multiple-regime *** the other hand,both the constructions of the low density wind tunnel with high enthalpy and the high altitude flight experiment are also very challenging at the present ***,the researches on the multiple-regime flows and the corresponding complex science hit a worldwide *** paper reviews the breakthroughs in the computational methods for multiple-regime flows in the last ten years,which can be used as numerical experimental tools for studying the multiple-scale flow mechanism and providing data for aerodynamic designs and thermal *** paper focuses on the progress of the unified wave-particle methods established in recent years,which are proved to be both accurate and efficient for multiple-regime flows with extremly high speed.

关键词： Direct modeling Multiple flow regimes Multiple scales Hypersonic flow Transitional flow Complex science

来源：评论

学校读者我要写书评

暂无评论

A Micromagnetic-Mechanically Coupled Phase-Field Model for Fracture and Fatigue of Magnetostrictive Alloys

SSRN

引用

SSRN 2024年

作者： Sun, Shen Gong, Qihua Ni, Yong Yi, Min Nanjing210016 China CAS Key Laboratory of Mechanical Behavior and Design of Materials Department of Modern Mechanics CAS Center for Excellence in Complex System Mechanics University of Science and Technology of China Hefei230026 China

Magnetostrictive alloys are usually brittle materials with micromagnetic structures. Their structural reliability and durability depend on the complex micromagnetic-mechanical coupling at smaller length scales encompassing the evolution of micromagnetic structures. Herein we propose a micromagnetic-mechanically coupled phase-field model for fracture and fatigue behavior of magnetostrictive alloys with evolution of the micromagnetic structure. The thermodynamically-consistent model is derived from microforce theory, laws of thermodynamics, and Coleman–Noll analysis. The evolution of crack phase-field and magnetization-vector order parameters that are fully coupled is governed by history field dependent Allen–Cahn and Landau–Lifshitz–Gilbert equations, respectively. The model is extended to fatigue by introducing a degradation prefactor for the fracture energy as a function of positive elastic energy. One-dimensional analyses are then presented to anatomize the crack driving forces in terms of fully coupled micromagnetic-mechanical and pure mechanical driving force. We demonstrate the model capabilities by finite-element numerical studies on the micromagnetic domain evolution during the crack propagation and the influence of external magnetic field for type-I, type-II, and three-point bending fracture, as well as for the fracture of a single-edge notched specimen with an elliptical inclusion. The simulation result shows that depending on how micromagnetic domains are switched under micromagnetic-mechanical coupling, the magnetic field can enhance or decrease the critical load. In the presence of inclusion with larger fracture toughness, a crack is found to nucleate in the tri-junction of multi-domain micromagnetic structure owing to the high elastic strain around the tri-junction point. It is further found that a suitable magnetic field promoting magnetization-vector rotation around the crack tip could remarkably improve the fracturing load and fatigue life. The resul

关键词： Magnetic fields

来源：评论

学校读者我要写书评

暂无评论

Stability of selenium and its speciation analysis in water using automatic system separation and HR-ICP-MS measurement

引用

Chinese Chemical Letters 2022年第7期33卷 3444-3450页

作者： Junqiang Yang Yawen Chen Keliang Shi Kesheng Hu Run Li Xiaoqing Gao Qian Wang Weibo Zhang Yun Zhou Yanyun Wang Jiangang He Tonghuan Liu Xiaolin Hou Frontier Science Center for Rare Isotopes Lanzhou UniversityLanzhou 730000China School of Nuclear Science and Technology Lanzhou UniversityLanzhou 730000China Beijing National Laboratory for Molecular Sciences Fundamental Science Laboratory on Radiochemistry&Radiation ChemistryCollege of Chemistry and Molecular EngineeringPeking UniversityBeijing 100871China Key Laboratory of Special Function Materials and Structure Design Ministry of EducationLanzhou UniversityLanzhou 730000China CNNC Lanzhou Uranium Enrichment Co. Ltd.Lanzhou 730000China Environmental Monitor Center of Gansu Province Lanzhou 730000China

A simple and convenient method has been developed for the pre-concentration and separation of inorganic selenium species from environmental water samples using anion exchange chromatographic column combined with high resolution inductively coupled plasma mass spectrometry(HR-ICP-MS)measurement.^(75)Se(Ⅳ) and ^(75)Se(Ⅵ)were prepared and used as tracers during the *** volatility of selenium during solution evaporation was investigated to establish a reliable water samples pretreatment *** parameters which affect the uptake of Se(Ⅳ)and Se(Ⅵ)on Dowex1×8 resin was optimized and the procedure for Se(Ⅳ)and Se(Ⅵ)separation was *** Se(Ⅳ)and Se(Ⅵ)are retained on the column in natural or alkaline solution with high distribution *** successive gradient elution of pre-concentrated species of selenium with HNO_(3)solution allows to differentiate between ***(Ⅳ)and Se(Ⅵ)finally were eluted with 0.05 mol/L HNO_(3) and 5.0 mol/L HNO_(3),*** proposed method has been successfully verified using the certified reference materials(CRMs)of real water samples,and spiked recoveries for real samples were 98%-104%with 5%relative standard deviations(RSDs).The developed procedure is proved to be reliable and can be used for the rapid determination of selenium species in environmental water samples.

关键词： Inorganic selenium Speciation Automatic system separation Rapid determination Water sample

来源：评论

学校读者我要写书评

暂无评论

Experimental Study of Coherent Structures Downstream Mixing Vaned Spacer Grid of Different Inclination Angles in a 5×5 Rod Bundle by Tr-Piv

SSRN

引用

SSRN 2022年

作者： Qu, Wenhai Xie, Hao Shen, Danhong Wang, Zefeng Xiong, Jinbiao School of Nuclear Science and Engineering Shanghai Jiao Tong University Shanghai China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu China

Experimental study of coherent structures downstream of a spacer grid with different inclination angles of mixing vanes in a 5×5 rod bundle was conducted by TR-PIV under four Reynolds *** coherent structures downstream of spacer grid change with several patterns. The developments of lateral time-averaged velocity, Reynolds stress, dominant frequency, integral spatial length scales and integral temporal length scales are determined by coherent structures. Smaller coherent structures are generated with Reynolds number increasing, and time-averaged velocity, Reynolds stress, St numbers, spatial and temporal length scales decrease. Larger inclination angle generates larger coherent structures, and spatial and temporal length scales increase with inclination angle increasing. The coherent structures indicate strong anisotropy of turbulent flow in rod *** experimental findings provide valuable information for understanding sub-channel mixing phenomena caused by mixing vaned spacer grids. The experimental data can be used for sub-channel mixing model developments and validations of turbulent models. © 2022, The Authors. All rights reserved.

关键词： Reynolds number

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：