Research on the sampling performance of a new bionic gravity sampler

Gravity sampling is of vital importance for sampling seabed sediments and understanding submarine sedimentary environments and resources.In this study,a new bionic sampler tube(BST)with non-smooth surface for low-disturbance and rapid sampling is presented.The BST with depressions and swellings on its surface was designed on the model of the non-smooth surface of the dung beetle.Sufficient theoretical calculations,numerical simulations,and experimental tests were carried out to study its sampling performance.The penetration depth,sample length,and frictional drag of the sampler tube were calculated.The finite element model and the coupled Eulerian-Lagrangian(CEL)method were used to analyze and compare its sampling performance.Laboratory and field gravity sampling tests were conducted and the results demonstrated the advantages of the BST in improving sampling performance and in reducing adhesion and drag.

Design and comparative analysis of self-propelling drill bit applied to deep-sea stratum drilling robot

Robotic subsea stratum drilling robot is a method for new subsea stratigraphic geological investigation and resource exploration.Resistance at the front end is the main source of resistance to the robot’s motion in the strata.Since there is no continuous and strong downward drilling force as in conventional drilling rigs,robot movement relies heavily on the drill bit to reduce the drilling resistance.In this study we propose a self-propelling drill bit that can discharge soil debris to provide propulsive force and reduce the resistance.The key parameter of the drill bit design,the spiral blade lead angle,was determined by theoretical analysis of the drill bit’s soil discharging effect.To verify the structural advantages of the self-propelling drill bit in reducing resistance,a comparative analysis with a conventional conical drill bit was conducted.The drilling process of both bits was simulated using finite element simulation at various rotation speeds,the penetration force and torque data of both drill bits were obtained,and tests prepared accordingly in subsea soil were conducted.The simulations and tests verified that the penetration force of the self-propelling drill bit was lower than that of the conventional conical drill bit.The self-propelling drill bit can reduce the resistance effectively,and may play an important role in the stratum movement of drilling robots.

Influence of urban morphological parameters on the distribution and diffusion of air pollutants: A case study in China

Air pollution has a serious fallout on human health,and the influences of the different urban morphological characteristics on air pollutants cannot be ignored.In this study,the relation-ship between urban morphology and air quality(wind speed,CO,and PM_(2.5))in residential neighborhoods at the meso-microscale was investigated.The changes in the microclimate and pollutant diffusion distribution in the neighborhood under diverse weather conditions were simulated by Computational Fluid Dynamics(CFD).This study identified five key urban morphological parameters(Building Density,Average Building Height,Standard Deviation of Building Height,Mean Building Volume,and Degree of Enclosure)which significantly im-pacted the diffusion and distribution of pollutants in the neighborhood.The findings of this study suggested that three specific strategies(e.g.volume of a single building should be re-duced,DE should be increased)and one comprehensive strategy(the width and height of the single building should be reduced while the number of single buildings should be in-creased)could be illustrated as an optimized approach of urban planning to relief the air pollution.The result of the combined effects could provide a reference for mitigating air pollution in sustainable urban environments.