A Numerical Approach to the Dynamic Response of the Deployment System during a Circular Cylinder Crossing through the Wave Zone

The dynamic response of the deployment system while deploying a circular cylinder crossing wave surface and the following submerging process are investigated numerically. The present numerical approach is based on the combination of solution methods of cable dynamics and computational fluid dynamics (CFD). For the implementation of the numerical approach, a cosimulation platform based on a CFD code and MATLAB is developed to study the fluid-solid interaction problem in the process. To generate regular waves, a numerical wave tank is built based on a piston-type wave generation method and a wave damping method applying porous media. Numerical simulations are performed based on the cosimulation platform. The sensitivities of cable tension, velocity, and acceleration of deployed body to different input parameters are investigated, including phase angles, wave heights, and periods of regular waves and deploying velocities, and the effects of those input parameters on dynamic responses of the deployment system are also discussed

Minimal information for studies of extracellular vesicles (MISEV2023): From basic to advanced approaches

Extracellular vesicles (EVs), through their complex cargo, can reflect the state of their cell of origin and change the functions and phenotypes of other cells. These features indicate strong biomarker and therapeutic potential and have generated broad interest, as evidenced by the steady year-on-year increase in the numbers of scientific publications about EVs. Important advances have been made in EV metrology and in understanding and applying EV biology. However, hurdles remain to realising the potential of EVs in domains ranging from basic biology to clinical applications due to challenges in EV nomenclature, separation from non-vesicular extracellular particles, characterisation and functional studies. To address the challenges and opportunities in this rapidly evolving field, the International Society for Extracellular Vesicles (ISEV) updates its 'Minimal Information for Studies of Extracellular Vesicles', which was first published in 2014 and then in 2018 as MISEV2014 and MISEV2018, respectively. The goal of the current document, MISEV2023, is to provide researchers with an updated snapshot of available approaches and their advantages and limitations for production, separation and characterisation of EVs from multiple sources, including cell culture, body fluids and solid tissues. In addition to presenting the latest state of the art in basic principles of EV research, this document also covers advanced techniques and approaches that are currently expanding the boundaries of the field. MISEV2023 also includes new sections on EV release and uptake and a brief discussion of in vivo approaches to study EVs. Compiling feedback from ISEV expert task forces and more than 1000 researchers, this document conveys the current state of EV research to facilitate robust scientific discoveries and move the field forward even more rapidly

Evaluation of Optimal Policy on Environmental Change through Green Consumption

This paper explores the relationship between green consumption and the environment from a new perspective of green consumption on the demand side. This paper further investigates how to design an environmental policy package to achieve optimal social allocation. The results show that: first, green consumption can still improve the environment without supply-driven policy; second, demand-driven environmental change is better than supply-driven change in improving the environment and increasing social welfare; and third, a policy package which includes green consumption is more efficient

Effect of Multi-Joint Clearance Coupling on Shimmy of Nose Landing Gear

The existence of joint clearances in the nose landing gear (NLG) is inevitable and significantly affects shimmy. It was found that the interaction of each joint clearance is closely related to the analysis of shimmy stability. In this study, the shimmy model of NLG with three-dimensional joint clearance was established by using LMS VirtualLab Motion. Based on the method of multibody dynamics (MBD), the load transfer mechanism at the joints of the NLG was analyzed, and the oscillation characteristics with multiple joint clearances were investigated. The results indicate that the radial and axial contact force of the joint decreases from bottom to top, and the radial contact forces are relatively high at the end positions of the connection shafts, resulting in uneven wear. When the joint clearance reaches a certain value, periodic shimmy of the NLG will occur, and an increase in torsional damping can reduce the amplitude of the shimmy. Therefore, this study reveals the influence of multi-position joint clearance coupling on shimmy, and provides a valuable insight for the maintenance and design of landing gear joints

Numerical Modeling and Simulation of Wave Impact of a Circular Cylinder during the Submergence Process

Wave slamming loads on a circular cylinder during water entry and the subsequence submergence process are predicted based on a numerical wave load model. The wave impact problems are analyzed by solving Reynolds-Averaged Navier-Stokes (RANS) equations and VOF equations. A finite volume approach (FV) is employed to implement the discretization of the RANS equations. A two-dimensional numerical wave tank is established to simulate regular ocean waves. The wave slamming problems are investigated by deploying a circular cylinder into waves with a constant vertical velocity. The present numerical method is validated using other numerical or theoretical results in accordance with varying free surface profiles when a circular cylinder sinks in calm water. A numerical example is given to show the submergence process of the circular cylinder in waves, and both free surface profiles and the pressure distributions on the cylinder of different time instants are obtained. Time histories of hydrodynamic load on the cylinder during the submergence process for different wave impact angles, wave heights, and wave periods are obtained, and results are analyzed in detail

A Numerical Approach to the Dynamic Response of the Deployment System during a Circular Cylinder Crossing through the Wave Zone

The dynamic response of the deployment system while deploying a circular cylinder crossing wave surface and the following submerging process are investigated numerically. The present numerical approach is based on the combination of solution methods of cable dynamics and computational fluid dynamics (CFD). For the implementation of the numerical approach, a cosimulation platform based on a CFD code and MATLAB is developed to study the fluid-solid interaction problem in the process. To generate regular waves, a numerical wave tank is built based on a piston-type wave generation method and a wave damping method applying porous media. Numerical simulations are performed based on the cosimulation platform. The sensitivities of cable tension, velocity, and acceleration of deployed body to different input parameters are investigated, including phase angles, wave heights, and periods of regular waves and deploying velocities, and the effects of those input parameters on dynamic responses of the deployment system are also discussed

A Numerical Approach to the Dynamic Response of the Deployment System during a Circular Cylinder Crossing through the Wave Zone

The dynamic response of the deployment system while deploying a circular cylinder crossing wave surface and the following submerging process are investigated numerically. The present numerical approach is based on the combination of solution methods of cable dynamics and computational fluid dynamics (CFD). For the implementation of the numerical approach, a cosimulation platform based on a CFD code and MATLAB is developed to study the fluid-solid interaction problem in the process. To generate regular waves, a numerical wave tank is built based on a piston-type wave generation method and a wave damping method applying porous media. Numerical simulations are performed based on the cosimulation platform. The sensitivities of cable tension, velocity, and acceleration of deployed body to different input parameters are investigated, including phase angles, wave heights, and periods of regular waves and deploying velocities, and the effects of those input parameters on dynamic responses of the deployment system are also discussed

Land supply marketization, economic fluctuations and welfare: A quantitative analysis for China

Land supply in China is planned by governments, and the supply ratios of various types of land are in relatively rigid administrative control. This paper constructs a DSGE model to study the relationship between land supply marketization in China and economic fluctuations. Moreover, this paper evaluates the social welfare gains from land marketization. We document that the government’s land planning constraint impacts consumption and social welfare through the land price and final output, causing resource misallocation losses in aggregate investment and output. Quantitatively, the optimal upper limit of industrial land supply is about 40% to achieve the maximum social welfare. This paper stresses the necessity of revitalizing China’s land market, and simultaneously speeding up the marketization of collectively operated construction land

Study on gas-liquid flow characteristics of buffers in the landing gear of a certain type of UAV landing gear lowering stage

When designing the retractable landing gear of an aircraft oil-gas mixed type，the medium flow characteristics between the inner cavities should be fully considered. The damping aperture and fuel filling amount of a certain UAV landing gear buffer is taken as the research object，and the single factor experimental method is used to analyze the changes of gas-liquid flow inside the buffer caused by each factor. The gas-liquid characteristics of the buffer under different damping apertures and oil filling amounts in the lowering stage are simulated and calculated by Fluent software. The results show that the damping hole oil flow during the landing gear lowering process is only related to the size of the pore size，not affected by the oil filling amount of the buffer. Under the 637 mL oil filling required by this type of UAV，the buffer damping aperture should be greater than 6 mm. For other types of landing gear buffers，when the oil filling amount is determined，the gas-liquid filling of the buffer that meets the lowering stage should be used as one of the buffer damping hole design criteria