Maneuvering a spacecraft in the cislunar space is a complex problem, since it is highly perturbed by the gravitational influence of both the Earth and the Moon, and possibly also the Sun. Trajectories minimizing the needed fuel are generally preferred in order to decrease the mass of the payload. A classical method to constrain maneuvers is mathematically modeling them using the Two Point Boundary Value Problem (TPBVP), defining spacecraft positions at the start and end of the trajectory. Solutions to this problem can then be obtained with optimization techniques like the nonlinear least squares conjugated with the Theory of Functional Connections (TFC) to embed the constraints, which recently became an effective method for deducing orbit transfers. In this paper, we propose a tangential velocity (TV) type of constraints to design orbital maneuvers. We show that the technique presented in this paper can be used to transfer a spacecraft (e.g. from the Earth to the Moon) and perform gravity assist maneuvers (e.g. a swing-by with the Moon). In comparison with the TPBVP, solving the TV constraints via TFC offers several advantages, leading to a significant reduction in computational time. Hence, it proves to be an efficient technique to design these maneuvers.
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http://dx.doi.org/10.1038/s41598-024-57986-z | DOI Listing |
ACS Omega
December 2024
School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, China.
As natural resources continue to be exploited, dense medium cyclones (DMCs) are increasingly utilized for the preconcentration of low-grade ores to meet the demands for higher feed grade, increased processing capacity, and reduced energy consumption. However, determining the optimal fineness of ferrosilicon remains ambiguous for different types of ores and is often described as more of an art than a science. This paper investigates the subtle effects of ferrosilicon fineness on flow field characteristics, medium classification, and the ore separation process using a validated numerical approach, which integrates a two-fluid model, a turbulence dispersion model, and a discrete phase model.
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December 2024
Jiangsu Key Laboratory of Oil-Gas Storage and Transportation Technology, Changzhou University, Changzhou, 213164, Jiangsu, China.
Bend pipe is a common part of long distance pipeline. There is very important to study the flow law of hydrate particles in the bend pipe, and pipeline design will be optimized. In addition, the efficiency and safety of pipeline gas transmission will be improved.
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December 2024
Guangdong Provincial Key Laboratory of Distributed Energy System, Dongguan University of Technology, Dongguan 523820, China.
To comprehensively explore syngas cocombustion technology, gasification experiments in a bench-scale circulating fluidized bed (CFB) and three-dimensional (3D) numerical simulations of a coal-fired boiler furnace have been conducted. In the amplification experiment of biomass gasification, sawdust has been gasified using air, oxygen-enriched air, and steam. The highest heating value of the syngas products reaches 12.
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December 2024
Engineering Technology Research Center of Henan Province for MEMS Manufacturing and Application, School of Mechanics and Safety Engineering, Zhengzhou University, Zhengzhou 450001, China.
Gas transport through nanochannels has aroused significant interest in many fields. Recently, "ballistic transport" of gas was observed through a two-dimensional graphene nanochannel, and it causes a peculiar enhancement compared to the predictions of the Knudson theory. Many studies attributed this effect to the specular reflection caused by the atomically smooth surface of the channel.
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November 2024
Department of Management Information Systems, College of Business and Economics, Qassim University, Buraydah, Saudi Arabia.
The main objective of the current endeavor is to monitor hypothetical processes utilizing a Sisko tri-hybrid fluid over a rotating disk with entropy generation suspended in Darcy-Forchheimer porous medium. Electro Magneto Hydro Dynamics (EMHD), non-linear thermal radiation and exponential and thermal- space dependent heat source/sink coefficients are considered with the intent of conceiving an Runge-Kutta-Fehlberg method with shooting procedures integrated with a combination of an Adaptive Neuro-Fuzzy Inference System (ANFIS) and Reptile Search Algorithm (RSA). Then, ANFIS-RSA, is used to predict the Nusselt number, skin friction co-efficient in radial and tangential velocities.
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