Understanding the Impacts of Aerodynamic Uncertainty on Optimal Trajectories for Hypersonic Vehicles

2021 ◽  
Author(s):  
Kieran Mackle ◽  
Ingo Jahn ◽  
Rowan Gollan
Keyword(s):  
Optimal Trajectories ◽  
Hypersonic Vehicles

Synthesis of Compromise-Optimal Trajectories of Mobile Objects in Conflict Environment

2002 ◽  
Vol 34 (2) ◽  
pp. 8 ◽  
Author(s):  
Albert N. Voronin ◽  
Alexander G. Yasinsky ◽  
Sergey A. Shvorov
Keyword(s):  
Optimal Trajectories ◽  
Mobile Objects

scholarly journals Hydrodynamics can determine the optimal route for microswimmer navigation

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Abdallah Daddi-Moussa-Ider ◽  
Hartmut Löwen ◽  
Benno Liebchen
Keyword(s):  
Flow Field ◽  
Hydrodynamic Interactions ◽  
Optimal Trajectories ◽  
Optimal Route ◽  
Active Particles ◽  
Navigation Strategy ◽  
Navigation Strategies

AbstractAs compared to the well explored problem of how to steer a macroscopic agent, like an airplane or a moon lander, to optimally reach a target, optimal navigation strategies for microswimmers experiencing hydrodynamic interactions with walls and obstacles are far-less understood. Here, we systematically explore this problem and show that the characteristic microswimmer-flow-field crucially influences the navigation strategy required to reach a target in the fastest way. The resulting optimal trajectories can have remarkable and non-intuitive shapes, which qualitatively differ from those of dry active particles or motile macroagents. Our results provide insights into the role of hydrodynamics and fluctuations on optimal navigation at the microscale, and suggest that microorganisms might have survival advantages when strategically controlling their distance to remote walls.

scholarly journals Oxidation behavior of non-stoichiometric (Zr,Hf,Ti)Cx carbide solid solution powders in air

2021 ◽  
Author(s):  
Huilin Lun ◽  
Yi Zeng ◽  
Xiang Xiong ◽  
Ziming Ye ◽  
Zhongwei Zhang ◽  
...  
Keyword(s):  
Solid Solution ◽  
Oxidation Resistance ◽  
Oxidation Behavior ◽  
Group Iv ◽  
Hypersonic Vehicles ◽  
Metal Carbides ◽  
Initial Oxidation ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Kinetics Of

AbstractMulti-component solid solutions with non-stoichiometric compositions are characteristics of ultra-high temperature carbides as promising materials for hypersonic vehicles. However, for group IV transition-metal carbides, the oxidation behavior of multi-component non-stoichiometric (Zr,Hf,Ti)Cx carbide solid solution has not been clarified yet. The present work fabricated four kinds of (Zr,Hf,Ti)Cx carbide solid solution powders by free-pressureless spark plasma sintering to investigate the oxidation behavior of (Zr,Hf,Ti)Cx in air. The effects of metallic atom composition on oxidation resistance were examined. The results indicate that the oxidation kinetics of (Zr,Hf,Ti)Cx are composition dependent. A high Hf content in (Zr,Hf,Ti)Cx was beneficial to form an amorphous Zr-Hf-Ti-C-O oxycarbide layer as an oxygen barrier to enhance the initial oxidation resistance. Meanwhile, an equiatomic ratio of metallic atoms reduced the growth rate of (Zr,Hf,Ti)O2 oxide, increasing its phase stability at high temperatures, which improved the oxidation activation energy of (Zr, Hf, Ti)Cx.

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