Research of Acoustic Emission Testing Method with Application to Monitored for Wind Turbines

Qin Hongwu,Zhang Chao,Zhang Xian,Fan Qinyin 보안공학연구지원센터 2015 International Journal of Multimedia and Ubiquitous Vol.10 No.1

Acoustic Emission method of nondestructive check is based on exertion wave radiation and their registration during fast local material structure reorganization. It is used as a means of analysis of materials, constructions, productions control and diagnosis during operating time. In the article, it is applied to structural health monitoring of Wind Turbines. Acoustic emission testing is based condition monitoring system uses data already collected at the wind turbine controller. It is an effective way to monitor wind turbines for early warning of failures and performance issues. We used a number of measurements to develop anomaly detection algorithms and investigated classification techniques using clustering algorithms and principal components analysis for capturing fault signatures. When registering signal amplitude it is required to consider its frequency distribution connecting each amplitude rate with the corresponding vibration rate. The correlation and signal to noise ratio were evaluated by the algorithm based on frequency spectrum. Classical method of frequency distortion influence exclusion consists of FRF calculation with subsequent adjustment of received signals spectral characteristics.

Book Review - Introduction to Instructed Second Language Acquistition, by Shawn Loewen, New York, Routledge, 2015, 210pp,.￥543 (Paperback), ISBN 978-0-415-52954-9

Hongwu Zhang 아시아영어교육학회 2018 The Journal of Asia TEFL Vol.15 No.1

Control Strategies for a High-Performance 2x27 MVA Machine Test Bench with Multilevel IGCT Converters

Bo Qu,Jingkui Shi,Hongwu She,Jie Shen,Stefan Schroeder,Zhuohui Tan,Kunlun Chen,Jianmei Zhang,Yulong Li,Fan Zhang,Richard Zhang 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6

In this paper, control strategies of a 22 MW / 27 MVA machine test bench using pumpback topology are introduced. The current loop design at extremely low pulse ratios (e.g. 600 Hz carrier frequency / 80 Hz load frequency) is developed. The system stability and dynamic response are analyzed. The challenges for high-power machine control with a sine filter and a transformer connected between the voltage-source-inverter and the machine are listed and solutions are given. Afterwards, some specific test modes are introduced as well. Finally, the control strategy is validated with the motor test at the customer site.

HMFS : A Hybrid Message Ferrying Scheme for Clustered Opportunistic Networks

Zhang Yushu,Wang Huiqiang,LV Hongwu,Feng Guangsheng,Zhu Jinmei 보안공학연구지원센터 2015 International Journal of Future Generation Communi Vol.8 No.4

Opportunistic network is an evolution of MANETs to delivery messages in intermittent-ly connected or completely disconnected wireless networks. Message ferrying is an effec-tive routing mode in opportunistic networks. However, the single message ferry routing scheme leads a much higher delay as the increasing of the network scale, comparing with that in small scale opportunistic networks. It has been proved that multiple message fer-ries routing scheme can improve the performance of large scale networks, but the prob-lems of synchronization and coordinate between ferries have a bad effect on the routing efficiency. To solve these problems, a Hybrid Message Ferrying Scheme (HMFS) for clus-tered opportunistic networks is proposed. In HMFS, we divide the communication area into multiple regions based on clustering results and several cross zones containing the regions. A local ferry is deployed in each region to deliver messages in the region, and several global ferries are deployed according to horizontal and vertical zones to commu-nicate among the regions. Moreover, each region has a ferry relay node in it, which is used to orchestrate the local ferry and global ferries. Through the theoretical analysis and simulation results, we can see that HMFS can improve the effect of routing in oppor-tunistic networks in terms of network latency and delivery ratio.

Analysis Technique of Spectral Characteristics AE Signals with Application to Monitored for WT

Qin Hongwu,Zhang Xian,Chu Wei,Fan Qinyin,Peng Jincheng,Jia Tongli 보안공학연구지원센터 2016 International Journal of Multimedia and Ubiquitous Vol.11 No.1

The paper presents the results of an assessment with a range as real AE signals are received at destruction of spot welding, and imitated by means of a AE transducer are given in work, efficiency use of high-frequency area for recognition of AE signals against hindrances is shown. The actuator is excited by an impulse signal instead of a sinewave, and the responses are measured with the PE sensors. The spectral characteristics of AE signals should use broadband transducers with the rise in the PE side of the treble to compensate for PE of the sample, and partly of the signal spectrum, which is reduced the measurement error of the absolute values. The damage could be indicated in an experiment, but it turned out that the sensitivity is low if the damage is not in the path between actuator and sensor. When a machine has a mistake, it leads to energy loss and results in the transformation of sound, heat and the whole performance. The basis of most condition monitoring techniques WT has been constructed by the various features.

New generation software of structural analysis and design optimization--JIFEX

Gu, Yuanxian,Zhang, Hongwu,Guan, Zhenqun,Kang, Zhan,Li, Yunpeng,Zhong, Wanxie Techno-Press 1999 Structural Engineering and Mechanics, An Int'l Jou Vol.7 No.6

This paper presents the development and applications of the software package JIFEX, a new finite element system which can be used for structural analysis and optimum design by the modern computer hardware and software technologies such as MS Windows95/NT and Pentium PC platforms. The complete system of JIFEX is programmed with $C/C^{++}$ language to make full use of advanced facilities of MS Windows95/NT. In the system, the finite element data pre-processing, based on the most popular CAD package AutoCAD (R13, R14), has been implemented, so that the finite element modeling could be integrated with geometric modeling of CAD. The system not only has interactive graphics facility for data post-processing, but also realizes the real-time computing visualization by means of the Dynamic Data Exchange (DDE) technique. Running on the Pentium computers, JIFEX can solve large-scale finite element analysis problems such as the ones with more than 60000 nodes in the finite element model.

Numerical investigation of two-phase flow characteristics in multiphase pump with split vane impellers

Yi Shi,Hongwu Zhu,Binbin Yin,Ruiting Xu,Jiate Zhang 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.4

Multiphase pump is a cost-effective option for subsea oil and gas field development. The ability to handle different inlet gas volume fractions (GVFs) especially high inlet GVF is critical to the development of pump performance. In this study, the two-phase flow characteristics in normal impeller and split vane impeller at different inlet GVFs were investigated by steady numerical simulations. The gas distribution on blade-to-blade plane and meridional flow channel at different inlet GVFs were analyzed and compared. Gas accumulation area and movement characteristics of the gas-liquid flow in impeller flow passage were also pointed out by unsteady simulations. Experimental results of the pump differential pressure were compared with the numerical simulation results, to validate the accuracy of numerical simulation method. The flow characteristics in pump with modified impeller and its performance at different inlet GVFs were both compared with that of the normal impeller. The steady simulation results of normal impeller in different inlet GVFs show that gas concentrating area in the flow passage increases as inlet GVF grows. The unsteady simulation results indicate that gas pocket firstly occurs on the pressure side of impeller, then moves to the suction side in the middle area of blade and finally transfers to outlet of impeller and disappears. The errors between numerical simulation results and experiment data are below 10 %, which validated the feasibility of the numerical simulation method. Simulation results on the split vane impeller demonstrate that the gas accumulation area in flow passage of the modified impeller is dramatically decreased compared to that of the normal impeller. The performance of the modified impeller is generally better than the normal impeller especially in high inlet GVF conditions.

Numerical investigation of heat transfer characteristics for Subsea Xmas tree assembly

Biao Hu,Hongwu Zhu,Kuang Ding,Fangling Xu,Youjiang Zhang 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.11

This study focuses on the heat transfer characteristic of a horizontal subsea Xmas tree assembly at a high spatial resolution. Computationalfluid dynamics (steady Reynolds-averaged Navier-Stokes) in combination with Low Reynolds number modelling (LRNM) isadopted for heat transfer analysis, which has been validated against a full scale underwater gate valve heat transfer experiment with goodagreements. The characteristics of cold sea water flowing through the subsea tree, and of convection heat transfer between the subsea treeand ambient cold water are obtained. The typical “hot spots,” which have high Convection heat transfer coefficient (CHTC) and creategreat large amounts of heat loss, are numerically determined. Under the designed water depth, the effects of installation orientation, seawater velocity, and inner oil temperature on convection heat transfer are investigated as well. Such work is significant for thermal designof the subsea tree to increase structural reliability and flow assurance level.

Optimal placement of piezoelectric curve beams in structural shape control

Jian Wang,Guozhong Zhao,Hongwu Zhang 국제구조공학회 2009 Smart Structures and Systems, An International Jou Vol.5 No.3

Shape control of flexible structures using piezoelectric materials has attracted much attention due to its wide applications in controllable systems such as space and aeronautical engineering. The major work in the field is to find a best control voltage or an optimal placement of the piezoelectric actuators in order to actuate the structure shape as close as possible to the desired one. The current research focus on the investigation of static shape control of intelligent shells using spatially distributed piezoelectric curve beam actuators. The finite element formulation of the piezoelectric model is briefly described. The piezoelectric curve beam element is then integrated into a collocated host shell element by using nodal displacement constraint equations. The linear least square method (LLSM) is employed to get the optimum voltage distributions in the control system so that the desired structure shape can be well matched. Furthermore, to find the optimal placement of the piezoelectric curve beam actuators, a genetic algorithm (GA) is introduced in the computation model as well as the consideration of the different objective functions. Numerical results are given to demonstrate the validity of the theoretical model and numerical algorithm developed.

Optimal placement of piezoelectric curve beams in structural shape control

Wang, Jian,Zhao, Guozhong,Zhang, Hongwu Techno-Press 2009 Smart Structures and Systems, An International Jou Vol.5 No.3

Shape control of flexible structures using piezoelectric materials has attracted much attention due to its wide applications in controllable systems such as space and aeronautical engineering. The major work in the field is to find a best control voltage or an optimal placement of the piezoelectric actuators in order to actuate the structure shape as close as possible to the desired one. The current research focus on the investigation of static shape control of intelligent shells using spatially distributed piezoelectric curve beam actuators. The finite element formulation of the piezoelectric model is briefly described. The piezoelectric curve beam element is then integrated into a collocated host shell element by using nodal displacement constraint equations. The linear least square method (LLSM) is employed to get the optimum voltage distributions in the control system so that the desired structure shape can be well matched. Furthermore, to find the optimal placement of the piezoelectric curve beam actuators, a genetic algorithm (GA) is introduced in the computation model as well as the consideration of the different objective functions. Numerical results are given to demonstrate the validity of the theoretical model and numerical algorithm developed.