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Vibration-modal analysis model for multi-span pipeline with different support conditions

Computer Modelling and New Technologies 2014年第5期18卷 7-13页

作者： Liu, Jun He, Xing Liu, Qingyou Naibin, Jiang Chen, Huang School of Civil Engineering and Architecture Southwest Petroleum University Chengdu China Modern Design and Simulation Lab for Oil and Gas Equipment's Southwest Petroleum University Chengdu China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu China

Vibration characteristics analysis is important in the design of multi-span pipeline with different support conditions. In order to analyze the natural frequency and the vibration modal of the multi-span pipeline, a matrix transfer method is proposed in this paper. With the multi-span pipeline divided into single-span pipes, the transmission formulas for the deflection, angle, bending and shear between two adjacent spans are deduced, in combination with the Krylov function solution of the free vibration equation for the single-span pipe, and the constraint condition between the two adjacent spans of the multi-span pipeline. According to the boundary conditions on the starting and ending spans, the natural frequency equation and the vibration modal function between two adjacent spans of the multi-span pipeline are presented. The FORTRAN program based on the above principle is written, and the natural vibration frequencies and the vibration modals of two typical multi-span pipelines are investigated and compared with the results from ABAQUS. It is shown that the model presented in this paper is efficient in the analysis of multi-span pipeline and has the advantages of high computational efficiency and convenience for engineering practice application.

关键词： Natural frequencies

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A parameterized model of bolted joints in machine tools

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International Journal of Acoustics and Vibrations 2014年第1期19卷 10-20页

作者： Li, Hongqi Li, Bin Mao, Kuanmin Huang, Xiaolei Peng, Fangyu National NC System Engineering Research Center Huazhong University of Science and Technology Wuhan 430074 China State Key Laboratory of Digital Manufacturing Equipment and Technology Huazhong University of Science and Technology Wuhan 430074 China

A new dynamic model for bolted joints in heavy machine structures is proposed. The influence of the bolt pretightening force, the interface dimensions and the surface roughness on joint dynamics (i.e. the stiffness matrix of finite element) were analysed. Each stiffness coefficient in the matrix can be expressed by an exponential function of preload, and a quadratic polynomial function of geometric dimensions. Sixteen specimens were thoroughly designed and analysed. Then, the resulting stiffness matrices were saved as templates, based on which could establish dynamic models of joints with different influence factor values, using curve-fitting and Response Surface Methodology (RSM). The methodology was validated by experiments with a specimen of the new design and a heavy-duty cutting machine.

关键词： Stiffness matrix

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Analysis of electromagnetic torque of induction machines with the load torque changes suddenly

Analysis of electromagnetic torque of induction machines wit...

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International Conference on Electrical Machines and systems (ICEMS)

作者： Xinjian Cai Zhenxing Wu Le Sun State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology China School of Information Science and Engineering Fujian University of Technology China National Key Laboratory for Vessel Integrated Power System Technology China School of Electrical Engineering Xi'an Jiaotong University China

ISBN: (纸本)9781479951635

Since many Cascaded H-bridge multilevel (CHBML) inverters that are applied to drive high voltage machines can't transmit electric energy reversely, the electric energy transmitted from the machines may damage the inverters. This paper presents a transfer function to analyze the electromagnetic torque, when the load torque changes suddenly. Based on the achievements, the electric energy that flows between the machine and the inverter can be calculated. And then, a method is proposed to prevent the reversion of the direction of energy flow. Furthermore, the transfer function can be used to guide the design of the control system of induction machine. Simulation results verify the transfer function and the presented method.

关键词： Torque Electromagnetics Induction machines Stators Rotors Load modeling Mathematical model

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Establishment of mapping relationship between plasma actuator parameters and body force based on neural networks 52

Establishment of mapping relationship between plasma actuato...

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52nd AIAA Aerospace sciences Meeting - AIAA science and technology Forum and Exposition, SciTech 2014

作者： Wu, Bin Gao, Chao Wang, Yushuai Wang, Yuling Zheng, Borui Liu, Feng Luo, Shijun Northwestern Polytechnical University Department of Fluid Mechanics Xi'an 710072 China Northwestern Polytechnical University National Key Laboratory of Science and Technology on Aerodynamic Design and Research Xi'an 710072 China University of California Department of Mechanical and Aerospace Engineering Irvine CA 92697-3975 United States

ISBN: (数字)9781624102561

ISBN: (纸本)9781624102561

The velocity field and pressure field induced by Dielectric-Barrier-Discharge (DBD) plasma actuation (DBD) are accurately measured based on PIV and transient differential pressure sensors. A micro lens is mounted on PIV system to capture the critical region of plasma-induced flow. The transient differential pressure sensors with 0.1 Pa resolutions, respond effectively to the inconspicuous change of pressure gradient in the low speed flow. The neural network model is established, revealing the complex nonlinear mapping of external and internal information, while trained by large numbers of experimental samples. The electrical parameters of the plasma generator, the shape parameters of plasma actuator and coordinate parameters are input into the neural network as external information. On the other hand, the velocity field and pressure field serve as internal information to be output. The obtained velocity field and pressure field through the neural network model are regarded as the source terms and are substituted into momentum equilibrium equations and Navier-Stokes equations to calculate the body force field, thus building the mapping relationship between extrinsic plasma actuator parameters and the body force.

关键词： Neural network models

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Study on flow induced vibration characteristics of wo inline tubes and two parallel tubes

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Hedongli Gongcheng/Nuclear Power Engineering 2014年第1期35卷 87-91页

作者： Feng, Zhipeng Zhang, Yixiong Zang, Fenggang Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu 610041 China

In order to investigate the fluid structure interaction problems occurring in tube bundles, a numerical model is presented. The unsteady three-dimensional Navier-Stokes equation and LES turbulence model are computed with finite volume approach on structured grids combined with the technique of dynamic mesh. The model presents a three dimensional fully coupled approach with solving the fluid flow and the structure vibration simultaneously, for the tube bundles in cross flows. The results show that, the presented model is validated with experimental data and compared with existing models in the literature. Trajectory of single tube is "8" shape at "locked in". The two parallel tubes oscillate in opposite phase and both have the same amplitude. For pitch higher than 1.5D, there is no mutual influence of the tubes and response is close to the case of single tube. The lift force and amplitude of downstream tube of two inline tubes are increasing as the pitch increases. The upstream tube is almost not influenced by the downstream one when the pitch is larger than 2D. The fluid force and response are close to the case of single tube.

关键词： Large eddy simulation

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Attitude Coordinated Tracking of Multiple Spacecraft with Control Input Saturation

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IFAC Proceedings Volumes 2014年第3期47卷 9203-9208页

作者： Qingling Wang Huijun Gao Jiahu Qin Changbin Yu State Key Laboratory of Robotics and System (HIT) Harbin Institute of Technology Harbin China Australian National University Canberra Australia University of Science and Technology of China King Abdulaziz University Jeddah Saudi Arabia Shandong Computer Science Center Jinan China

The attitude coordinated tracking problem of multiple spacecraft with control input saturation is studied in this paper. We first construct a decentralized attitude coordinated tracking algorithm with input saturation, such that spacecraft can track a time-varying desired trajectory and align their attitudes. We then introduce a novel auxiliary dynamical systems to present an attitude coordinated tracking algorithm with input saturation and without angular velocity measurements. Throughout this paper, the information flow between spacecraft is assumed to be undirected. Finally, design examples are given to show the effectiveness of the proposed attitude coordinated tracking algorithms.

关键词：

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Theoretical framework for innovation design with optimised customization

Theoretical framework for innovation design with optimised c...

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4th International Conference on Frontiers of Manufacturing science and Measuring technology, ICFMM 2014

作者： Wang, Huan Huan Yang, Qing Ping College of Mechanical Engineering Tianjin University of Science and Technology Tianjin 300222 China Micro Optics Electronic Machine System Education Ministry Key Laboratory Tianjin University Tianjin 300072 China School of Engineering and Design Brunel University Uxbridge Middlesex UB8 3PH United Kingdom

ISBN: (纸本)9783038351924

design is the core of innovation activity, and it aims to establish better and comprehensive qualities of products. It is also a process to explore and enhance the human experience. During decades of exploration and practice, designers have developed many effective design methods and methodologies. However, users always have more needs and higher expectations. How will the human needs develop in the future? What will the future design is? This paper discusses the relationship between the development of human needs and the process of product evolution, explores the future design trends and presents a theoretical framework for innovation design with optimised customization. © (2014) Trans Tech Publications, Switzerland.

关键词： Product design

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design of power management chip for piezoelectric energy harvesting

Design of power management chip for piezoelectric energy har...

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IEEE Conference on Electron Devices and Solid-State Circuits

作者： Hua Yu Shibo Yang Wei Wang College of Optoelectronic Engineering Chongqing University Chongqing China Ministry of Education of China The Key Laboratory for Optoelectronic Technology & Systems Chongqing China National Key Laboratory of Fundamental Science of Micro/Nano-Device and System Technology Chongqing China

ISBN: (纸本)9781479923366

The paper proposes a complete energy harvesting solution integrated with a low-loss AC/DC rectifier and a high efficiency low dropout regulator (LDO) optimized for micro piezoelectric energy harvester. The AC/DC module converts AC into DC and then supplies power for the following LDO circuit module, through which the whole chip can obtain a stable 3.3V output voltage. A dynamic compensation mechanism is presented to improve the loop stability of LDO, which is easier to achieve high phase margin than traditional compensation strategy. The simulation results of LDO indicate that the typical dropout is 0.4mV with 1mA load current and 61mV with 150mA load current respectively, and the typical voltage line regulation error is 0.025%/V. In addition, the typical load regulation error was 0.00018%. The results demonstrate that the proposed chip meets the requirements of power supply for wireless sensor node (WSN).

关键词： Photonic band gap

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Algorithm for Directional Projection of Parametric Curves onto B-spline Surfaces

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Computer-Aided design and Applications 2014年第4期11卷 468-477页

作者： Song, Hai-Chuan Yong, Jun-Hai School of Software Tsinghua University Beijing 100084 China Department of Computer Science and Technology Tsinghua University Beijing 100084 China Key Laboratory for Information System Security Ministry of Education of China Beijing 100084 China Tsinghua National Laboratory for Information Science and Technology Beijing 100084 China

This paper proposes an algorithm for calculating the directional projection of parametric curves onto B-spline surfaces. It consists of a second order tracing method with which we construct a polyline to approximate the pre-image curve of the directional projection curve in the parametric domain of the base surface. The final 3D approximate curve is obtained by mapping the approximate polyline onto the base surface. The Hausdorff distance between the exact directional projection curve and the approximate curve is controlled less than the user-specified distance tolerance. And the continuity of the approximate curve is Ε{lunate}T-G1, where Ε{lunate}T is the user-specified angle tolerance. Experiments demonstrate that our algorithm is faster than the existing first order algorithm. © 2014 CAD Solutions, LLC.

关键词： Approximation algorithms

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Path Pattern Query Processing on Large Graphs

Path Pattern Query Processing on Large Graphs

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IEEE International Conference on Big Data and Cloud Computing (BdCloud)

作者： Yiyuan Bai Chaokun Wang Xiang Ying Meng Wang Yunqing Gong School of Software Tsinghua University Beijing China Tsinghua National Laboratory for Information Science and Technology Key Laboratory for Information System Security Ministry of Education

ISBN: (纸本)9781479967209

There are plentiful and diverse applications of graph data management and mining in the real-world scientific research and business activities. As one of the most basic operations, uniform path pattern query processing on graph data faces three big challenges. In this paper, we deal with these challenges by the following points. Firstly, a new query language on graph, called G-Path, is presented, which focuses on complex path pattern query processing on a very large graph. Also, the design of a system called HDGL is proposed, which is based on a BSP-like model as well as MapReduce model, and can effectively handle distributed graph data operations and queries. Secondly, the implementation of HDGL on the de facto cloud platform - Hadoop - is brought forward. Based on the concept of distributed state machine, the query processing of a G-Path statement in HDGL is detailed. In addition, as the query optimization of G-Path queries, several tricks are utilized to improve dramatically the performance of query execution. Finally, extensive experiments on several graph data sets are conducted to show the usability of G-Path query language and the effectiveness of HDGL.

关键词： Indexes Query processing Database languages Writing Pattern matching Data models Data mining

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