dynamic characteristic
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2022 ◽  
pp. 0309524X2110671
Author(s):  
Shoutu Li ◽  
Qing Wang ◽  
Congxin Yang

One of the important challenges for Vertical Axis Wind Turbine (VAWT) is to fully understand its dynamic characteristics in different operating conditions. Meanwhile, it is necessary to seek a fast and accurate method to evaluate the dynamic characteristic of VAWT. In this study, we improve the LB model by considering the operating principle of VAWT to study the dynamic characteristics of the dedicated and commonly used VAWT airfoils in different operating conditions. The results show that the improved LB model is suitable for simulating the dynamic characteristic of VAWT with a thick airfoil. Although the asymmetric airfoil shows the higher lift coefficient, their dynamic characteristic appears huge fluctuation as the increases of tip speed ratio. Moreover, at a low tip speed ratio, the advantages of the asymmetric airfoil are not obvious. While the dynamic characteristic of the symmetric airfoil is relatively stable with the variation of tip speed ratio.


Author(s):  
Nikita I. Gushchin ◽  
Mikhail A. Aleksandrov

Modern processes of the evolution of ethnic identification of different nations require a constant search for new approaches to the explanation of emerging phenomena. The primordialist approach to the study of ethnicity, which is classical in Russian sociology, cannot explain many of the processes occurring within ethnic groups. One such group is the Chuvash people, whose ethnic identification has undergone significant changes since the late nineteenth century, associated with changes in writing, urbanization, and the emergence of their own political institutions. It is a constructivist approach to the study of ethnicity, which emphasizes the consideration of the dynamics of ethnic processes and their historical evolution, is appropriate which will help to explain this changes. The Chuvash people in this case represent a unique object for study. As the largest predominantly orthodox Turkic ethnic group, it differs greatly from its neighbors. The study of the ethnic identification of the Chuvash people from the perspective of the constructivist approach to ethnicity should be given closer attention, in order to solve the problems faced by the scientific community.


2021 ◽  
Vol 13 (12) ◽  
pp. 168781402110668
Author(s):  
Runlin Chen ◽  
Chen Du ◽  
Xiaotuan Wang ◽  
Yanchao Zhang ◽  
Kai Liu

Aiming at the dynamic characteristics test bench of sliding bearings, the dynamic model is established. Based on the forward and inverse dynamic problems of the bearing, a simulation evaluation method for the identification accuracy of the sliding bearing dynamic characteristics is proposed and the algorithm is verified. The identification errors of dynamic characteristic coefficients under different excitation frequencies are analyzed, the sensitivities of single frequency excitation method and dual-frequency excitation method to test error are contrastively analyzed, and the influence laws of dynamic characteristic identification accuracy of sliding bearing are evaluated. Based on which the traditional single frequency excitation method has been improved. The dynamic characteristic test should be carried out respectively in the low frequency range and the high frequency range. The main stiffness and cross damping are the average of two tests, the main damping is the identification value in the high frequency, and the cross stiffness is the identification value in the low frequency. That will effectively reduce the impact of test error. The obtained data and laws could support the improvement of the dynamic characteristics test method of sliding bearings and the confirmation of test parameters, thereby the accuracy of dynamic characteristics identification is improved.


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