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| 1 | Diagnosis of the Forcing of Inertial-gravity Waves in a Severe Convection System显示文摘The non-hydrostatic wave equation set in Cartesian coordinates is rearranged to gain insight into wave generation in a mesoscale severe convection system. The wave equation is characterized by a wave operator on the lhs, and forcing involving three terms—linear and nonlinear terms, and diabatic heating—on the rhs. The equation was applied to a case of severe convection that occurred in East China. The calculation with simulation data showed that the diabatic forcing and linear and nonlinear forcing presented large magnitude at different altitudes in the severe convection region. Further analysis revealed the diabatic forcing due to condensational latent heating had an important influence on the generation of gravity waves in the middle and lower levels. The linear forcing resulting from the Laplacian of potential-temperature linear forcing was dominant in the middle and upper levels. The nonlinear forcing was determined by the Laplacian of potential-temperature nonlinear forcing. Therefore, the forcing of gravity waves was closely associated with the thermodynamic processes in the severe convection case. The reason may be that, besides the vertical component of pressure gradient force, the vertical oscillation of atmospheric particles was dominated by the buoyancy for inertial gravity waves. The latent heating and potential-temperature linear and nonlinear forcing played an important role in the buoyancy tendency. Consequently, these thermodynamic elements influenced the evolution of inertial-gravity waves. | Lingkun RAN Changsheng CHEN | 2016 | Advances in Atmospheric Sciences2016，33，11： | 2 |
| 2 | A multi-location joint field observation of the stratosphere and troposphere over the Tibetan Plateau显示文摘The unique geographical location and high altitude of the Tibetan Plateau can greatly influence regional weather and climate.In particular, the Asian summer monsoon(ASM) anticyclone circulation system over the Tibetan Plateau is recognized to be a significant transport pathway for water vapor and pollutants to enter the stratosphere. To improve understanding of these physical processes, a multi-location joint atmospheric experiment was performed over the Tibetan Plateau from late July to August in 2018, funded by the fiveyear(2018–2022) STEAM(stratosphere and troposphere exchange experiment during ASM) project, during which multiple platforms/instruments—including long-duration stratospheric balloons, dropsondes, unmanned aerial vehicles, special sounding systems, and ground-based and satellite-borne instruments—will be deployed. These complementary methods of data acquisition are expected to provide comprehensive atmospheric parameters(aerosol, ozone, water vapor, CO_2, CH_4, CO, temperature, pressure,turbulence, radiation, lightning and wind); the richness of this approach is expected to advance our comprehension of key mechanisms associated with thermal, dynamical, radiative, and chemical transports over the Tibetan Plateau during ASM activity. | JinQiang Zhang Yi Liu HongBin Chen ZhaoNan Cai ZhiXuan Bai LingKun Ran Tao Luo Jing Yang YiNan Wang YueJian Xuan YinBo Huang XiaoQing Wu JianChun Bian DaRen Lu | 2019 | Earth and Planetary Physics2019，3，2： | 1 |
| 3 | Bionic Flapping Pectoral Fin with Controllable Spatial Deformation显示文摘This paper presents the design of a bionic pectoral fin with fin rays driven by multi-joint mechanism.Inspired by the cownose ray,the bionic pectoral fin is modeled and simplified based on the key structure and movement parameters of the cownose ray's pectoral fin.A novel bionic propulsion fin ray composed of a synchronous belt mechanism and a slider-rocker mechanism is designed and optimized in order to minimize the movement errors between the designed fin rays and the spanwise curves observed from the cownose ray,and thereby reproducing an actively controllable flapping deformation.A bionic flapping pectoral fin prototype is developed accordingly.Observations verify that the bionic pectoral fin flaps consistently with the design rule extracted from the cownose ray.Experiments in a towing tank are set up to test its capability of generating the lift force and the propulsion force.The movement parameters within the usual propulsion capabilities of the bionic pectoral fm are utilized:The flapping frequency of 0.2 Hz-0.6 Hz,the flapping amplitude of 3°-18°,and the phase di^rence of 10°-60°.The results show that the bionic pectoral fin with actively controllable spatial deformation has expected propulsion performance,which supports that the natural features of the cownose ray play an important role in designing and developing a bionic prototype. | Yueri Cai Lingkun Chen Shusheng Bi Guoyuan Li Houxiang Zhang | 2019 | Journal of Bionic Engineering2019，16，5： | 1 |
| 4 | Analysis of Heading Stability due to Interactions between Pectoral and Caudal Fins in Robotic Boxfish Locomotion显示文摘Investigating the interaction between fins can guide the design and enhance the performance of robotic fish.In this paper,we take boxfish as the bionic object and discuss the effect of coupling motion gaits among the two primary propulsors,pectoral and caudal fins,on the heading stability of the body.First,we propose the structure and control system of the bionic boxfish prototype.Second,using a one/two-way fluid–structure interaction numerical method,we analyse the key parameters of the prototype and discuss the influence of pectoral and caudal motion gaits on the hydrodynamic performance.Finally,effect of the pectoral and caudal interactions on heading stability of the prototype is systematically analyzed and verified in experiments.Results show that the course-deviating degree,oscillation amplitudes of yawing,rolling,and pitching exhibited by the prototype are smaller than that caused by single propulsor when the motion gaits of both pectoral and caudal fins are coordinated in a specific range.This paper reveals for the first time the effect of interactions between pectoral and caudal fins,on the stability of body's course by means of Computational Fluid Dynamics and prototype experiments,which provides an essential guidance for the design of robotic fish propelled by multi-fins. | Hongcheng Qiu Lingkun Chen Xinshuo Ma Shusheng Bi Bo Wang Tiefeng Li | 2023 | Journal of Bionic Engineering2023，20，1： | 1 |
| 5 | Thermal modification of brittle CoFeNi_(2)(Ti_(3)Si_(5))_(0.16) eutectic high-entropy alloy by annealing treatment显示文摘Adopting the idea of thermal modification of conventional Si-containing eutectic alloys,this study performed heating of the brittle CoFeNi_(2)(Ti_(3)Si_(5))_(0.16) eutectic high-entropy alloy under various annealing conditions to attempt the fragmentation and spheroidization of eutectic microstructure and improve fracture plasticity.Results reveal that the as-cast alloy exhibited fine eutectic microstructures with lamellar+network morphologies,consisting of face-centered cubic(FCC)and M_(16)Ti_(6)Si_(7)-type silicide.After annealing at 1100℃×120 h,the lamellar+network eutectic morphologies were effectively fragmented and spheroidized into granular+irregular morphologies.The resulting alloy featured excellent mechanical properties with an ultimate compressive strength(UCS)of 1980±50 MPa,fracture plasticity of~16.6%±1%,and hardness of~448±15 HV.Compared with the as-cast specimen,the fracture plasticity of the specimen annealed for 120 h increased by 12.7 times,with no UCS reduction.With a further increase in the annealing time,the hard M_(16)Ti_(6)Si_(7)-type silicide was seriously coarsened,deteriorating the alloy’s room-temperature mechanical properties but improving its high-temperature ones. | ZHANG LingKun WANG MingLiang HUANG Rui CHEN XiaoHu REN Zheng HE Tao LU YiPing | 2023 | Science China(Technological Sciences)2023，66，4： | 0 |
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