A hydraulic pipe is a basic component of the aero hydraulic system, while high pressure and high speed lead to the enhancement of multiple field coupling effects, such as the structure, fluid, heat, and sound of the aero hydraulic pipe. A larger elastic deformation of the pipe and the more common unsteady flow of fluid can aggravate the vibration and noise of the hydraulic pipe system. Based on the 14-equation model of fluid-structure-interaction (FSI) vibration of aero hydraulic pipe, a model suitable for a wide Reynolds number range is proposed by comparing and analyzing various kinds of friction coupling models. This model is used for the FSI dynamic behavior analysis of aero hydraulic pipes, which improves the accuracy of FSI frequency-domain solutions under high Reynolds number conditions. Second, based on the 14-equation model of FSI vibration of aero hydraulic pipe and the transfer matrix method, the mathematical model of airframe deformation load of an aero hydraulic pipe is established, and the evolution law of the FSI dynamic behavior of the aero hydraulic pipe under different airframe deformation loads is analyzed. All the above analysis results were verified by the experimental analysis. The error of the analysis results of the FSI vibration frequency is smaller than 5% compared with the experimental results. The results show that the proposed method is feasible and effective for predicting the hydrodynamic behavior of the aero hydraulic pipes under load conditions. INDEX TERMS Hydraulic systems, vibrations, pipelines, fluid-structure-interaction (FSI).

As population ages, ensuring that the elderly get their due rights has become a common concern of scholars in many fields. However, as an important public service facility in daily life of elderly, the research on the equity of urban parks is mostly based on the evaluation of accessibility. The equity of the elderly's access to urban parks services has been rarely discussed from the perspective of supply and demand balance. In the context of the concept of spatial equity, we used urban parks in the main city of Harbin as a case study, the actual travel mode of the elderly was considered in the evaluation, adopted an Integrated Spatial Equity Evaluation (ISEE) framework, quantitative evaluation of the equity of different levels of urban park under multiple traffic modes. In this study, the results showed that under the three modes of travel, the degree of spatial equity was higher for non-motorized trips than for the other two modes. In terms of urban parks hierarchy, the spatial equity of urban parks at district level were much higher than those at the neighborhood level and street level. The inequity between supply and demand for urban park for elderly people was significant and varies between administrative districts. The empirical evidence in this research may provide references and suggestions for urban parks planning and decision-making. In cities where the scale of land use is basically stable, such as Harbin, we can start from the spatial configuration of park green space system and public transportation system to improve the efficiency of urban parks provision. Thereby promoting the construction and development of an “old age-friendly” society.

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