Current Issue : October - December Volume : 2020 Issue Number : 4 Articles : 5 Articles
The scheduling of Earth Observation Satellite (EOS) data transmission is a complex combinatorial optimization problem. With the\ndevelopment of remote sensing applications, a new special requirement named data transmission oriented to topics has appeared. It\nsupposes that the data obtained from each observation activity by satellites belong to certain observation data topics, and every\nobservation data topic has completeness and timeliness requirements. Unless all of the observation data belonging to one topic\nhas been transmitted to the ground before the expected time, the value of the observation data will be decayed sharply and only\na part of the rewards (or even no reward) for the data transmission will be obtained. Current researches do not meet the new\ndata topic transmission requirements well. Based on the characteristics of the problem, a mathematic scheduling model is\nestablished, and a novel hybrid scheduling algorithm based on evolutionary computation is proposed. In order to further\nenhance the performance and speed up the convergence process of our algorithm, a domain-knowledge-based mutation\noperator is designed. Quantitative experimental results show that the proposed algorithm is more effective to solve the satellite\nobservation data topic transmission scheduling problem than that of the state-of-the-art approaches....
The project of â??Mercuryplaneâ?â??a spacecraft for regular delivery of astronauts\nto the planet Mercury is considered. In the first stage of the flight, with\nthe help of a carrier rocket, equipped with a chemical rocket engine, astronauts\nare delivered to the international space station ISS. A design consisting\nof an interorbital module and a takeoff-landing capsule has been developed to\ndeliver astronauts from Earthâ??s orbit into Mercuryâ??s orbit. The interorbital\nmodule is an electric rocket equipped with 8 superconductor magnetoplasma\nelectric engines MARS type. The electric power supply for the engines is provided\nby a collapsible solar panel made of gallium arsenide. The design of the\ntakeoff-landing capsule has been developed for landing and take-off from the\nsurface of Mercury. A device has been developed to refuel in Earthâ??s orbit the\nelectric rocket engines with nitrogen, and chemical rocket engines with oxygen\nand hydrogen, which are in liquid state The developed spacecraft is able\nto regularly deliver three astronauts from Earth orbit to the surface of Mercury\nwithin 35 days....
Unpolarized sunlight becomes polarized by atmospheric scattering and produces a skylight polarization pattern in the sky,\nwhich is detected for navigation by several species of insects. Inspired by these insects, a growing number of research studies\nhave been conducted on how to effectively determine a heading angle from polarization patterns of skylight. However, few\nresearch studies have considered that the pixels of a pixelated polarization camera can be easily disturbed by noise and\nnumerical values among adjacent pixels are discontinuous caused by crosstalk. So, this paper proposes a skylight compass\nmethod based upon the moment of inertia (MOI). Inspired by rigid body dynamics, the MOI of a rigid body with uniform\nmass distribution reaches the extreme values when the rigid body rotates on its symmetry axes. So, a whole polarization\nimage is regarded as a rigid body. Then, orientation determination is transformed into solving the extreme value of MOI.\nThis method makes full use of the polarization information of a whole polarization image and accordingly reduces the\ninfluence of the numerical discontinuity among adjacent pixels and measurement noise. In addition, this has been verified\nby numerical simulation and experiment. And the compass error of the MOI method is less than 0.44 degree for an actual\npolarization image....
The existing sparse imaging observation error estimation methods are to usually estimate the error of each observation position by\nsubstituting the error parameters into the iterative reconstruction process, which has a huge calculation cost. In this paper, by\nanalysing the relationship between imaging results of single-observation sampling data and error parameters, a SAR observation\nerror estimation method based on maximum relative projection matching is proposed. First, the method estimates the precise\nposition parameters of the reference position by the sparse reconstruction method of joint error parameters. Second, a relative\nerror estimation model is constructed based on the maximum correlation of base-space projection. Finally, the accurate error\nparameters are estimated by the Broyden-Fletcher-Goldfarb-Shanno method. Simulation and measured data of microwave\nanechoic chambers show that, compared to the existing methods, the proposed method has higher estimation accuracy, lower\nnoise sensitivity, and higher computational efficiency....
The lack of water resources in many regions is the main challenge for the\nhuman being and to extended investigations. Water resources controlling and\nmanagement is essential in the areas depending on the seasonal rainfall. This\nresearch aims to estimate the surface water runoff for Basin of Alrakhmah\nValley located in the southwestern part of Kirkuk Province in northeastern of\nIraq. Analyzing of Spatial data and Digital Elevation Model (DEM) data has\nbeen conducted using Geographic Information System (GIS) to estimate the\nhydrological properties for the watershed valley with 158.5 km2 surface area.\nThe results showed that watershed valley type is from the fifth rank with a\nlongitudinal shape and topography percentage of 0.568. The watershed textures\nfound to be 3.24 and the drain density 1.5 at 3.49 river branching. Finally,\nthe annual estimated surface water retreat according to the morpho-\nhydro climatic elements found to be 0.01286233 milliard cubic meter....
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