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Insight into coupled forced vibration method to identify bridge flutter derivatives
Fuyou Xu,Xuyong Ying,Zhe Zhang 한국풍공학회 2016 Wind and Structures, An International Journal (WAS Vol.22 No.3
The flutter derivatives of bridge decks can be efficiently identified using the experimentally and/or numerically coupled forced vibration method. This paper addresses the issue of inherent requirement for adopting different frequencies of three modes in this method. The aerostatic force components and the inertia of force and moment are mathematically proved to exert no influence on identification results if the signal length (t) is integer (n=1,2,3...) times of the least common multiple (T) of three modal periods. It is one important contribution to flutter derivatives identification theory and engineering practice in this study. Therefore, it is unnecessary to worry about the determination accuracy of aerostatic force and inertia of force and moment. The influences of signal length, amplitude, and frequency ratio on flutter derivative are thoroughly investigated using a bridge example. If the signal length t is too short, the extraction results may be completely wrong, and particular attention should be paid to this issue. The signal length (N>5) is strongly recommended for improving parameter identification accuracy. The proposed viewpoints and conclusions are of great significance for better understanding the essences of flutter derivative identification through coupled forced vibration method.
Insight into coupled forced vibration method to identify bridge flutter derivatives
Xu, Fuyou,Ying, Xuyong,Zhang, Zhe Techno-Press 2016 Wind and Structures, An International Journal (WAS Vol.22 No.3
The flutter derivatives of bridge decks can be efficiently identified using the experimentally and/or numerically coupled forced vibration method. This paper addresses the issue of inherent requirement for adopting different frequencies of three modes in this method. The aerostatic force components and the inertia of force and moment are mathematically proved to exert no influence on identification results if the signal length (t) is integer (n=1,2,3...) times of the least common multiple (T) of three modal periods. It is one important contribution to flutter derivatives identification theory and engineering practice in this study. Therefore, it is unnecessary to worry about the determination accuracy of aerostatic force and inertia of force and moment. The influences of signal length, amplitude, and frequency ratio on flutter derivative are thoroughly investigated using a bridge example. If the signal length t is too short, the extraction results may be completely wrong, and particular attention should be paid to this issue. The signal length t=nT ($n{\geq}5$) is strongly recommended for improving parameter identification accuracy. The proposed viewpoints and conclusions are of great significance for better understanding the essences of flutter derivative identification through coupled forced vibration method.
Dynamic Seal Friction Heat Characteristics Analysis of Hydraulic Servo Swing Motor
Yannan Zhu,Qiang Zhang,Jianfeng Tao,Dun Tan,Xuyong Wang 한국유체기계학회 2018 International journal of fluid machinery and syste Vol.11 No.3
Hydraulic swing motor’s dynamic seal friction heat is a direct factor leading to motor’s temperature rise. To study the key factors in motor’s dynamic seal friction heat, therefore, reducing motor’s temperature rise, the contact stress model and friction model were established. Based on the swing motor of a three-axis turntable system, the relationship between three key factors was analyzed. Motor’s friction heat characteristics in two conditions were simulated, and simulation results show that with the increase of three factors, the friction heat increases obviously. Further experimental research validated the theoretical analysis and indicated that friction heat can be significantly reduced when reducing combined gasket’s compression ratio, motor’s working pressure and spindle’s speed appropriately. Furthermore, improving the machining precision of motor’s seal structure and combined seal’s installation precision also work.
Tao Yang,Sibo Wang,Xuyong Zhang,Jie Xia,Jun Guo,Jixue Hou,Hongwei Zhang,Xueling Chen,Xiangwei Wu 대한기생충학열대의학회 2016 The Korean Journal of Parasitology Vol.54 No.2
Human and animal alveolar echinococcosis (AE) are important helminth infections endemic in wide areas of the Northern hemisphere. Monitoring Echinococcus multilocularis viability and spread using real-time fluorescent imaging in vivo provides a fast method to evaluate the load of parasite. Here, we generated a kind of fluorescent protoscolices in vivo imaging model and utilized this model to assess the activity against E. multilocularis protoscolices of metformin (Met). Results indicated that JC-1 tagged E. multilocularis can be reliably and confidently used to monitor protoscolices in vitro and in vivo. The availability of this transient in vivo fluorescent imaging of E. multilocularis protoscolices constitutes an important step toward the long term bio-imaging research of the AE-infected mouse models. In addition, this will be of great interest for further research on infection strategies and development of drugs and vaccines against E. multilocularis and other cestodes.