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Future Power Generation And the Environment
Published in Anco S. Blazev, Power Generation and the Environment, 2021
To monitor the weather at large scales and high frequency, it is convenient for a satellite to be in a geostationary orbit. In such an orbit a satellite is able to continuously view almost an entire hemisphere. However, as the orbit is very high (approximately 36,000 km above the Earth) a high spatial resolution is difficult to attain. But for such applications as the tracking of clouds over continents, a high spatial resolution is not necessary.
Orbits and trajectories
Published in Jonathan Allday, Apollo in Perspective, 2019
Figure 4.7 shows three possible paths around a planet. A satellite placed in an equatorial orbit circles around the planet's equator and will be visible directly overhead by people living at this latitude. A geostationary orbit is an equatorial orbit in which a satellite turns about the Earth in the same time period that the Earth requires to turn about its axis.
Satellite Systems
Published in Jerry D. Gibson, The Communications Handbook, 2018
The primary purpose of communication satellites in geostationary orbit is to receive and retransmit signals from the Earth. Transponders provide the electronic equipment needed to accomplish this objective. A communication satellite is capable of receiving and retransmitting one or more independent signals. Each uplink signal is amplified and translated to a lower downlink carrier frequency by electronic circuits in the satellite. The electronic equipment used to amplify and shift the frequency of each signal is called a transponder. Typically, each satellite has 16-24 active transponders plus 6-8 spares.
Environing technologies: a theory of making environment
Published in History and Technology, 2018
Here, we use the example of remote sensing satellites which collect data by circling the Earth, often in near polar orbits at 700 or 800 km above the Earth’s surface, or from a position in the geostationary orbit, around 36,000 km above the Earth’s equator. Through different kinds of instruments, signals are picked up from the area that the satellite covers. The received signals can either be just passively emitted from Earth, like heat or light, or they can be reflections of a signal that the satellite instrument itself actively emits. The registered signals are stored in the on-board computer and are regularly downloaded to Earth stations where they can be processed. Remote sensing satellites were envisioned as early applications of space technology, both in Europe and the US, even though implementing them was not always easy.39
Co-kriging based multi-fidelity uncertainty quantification of beam vibration using coarse and fine finite element meshes
Published in International Journal for Computational Methods in Engineering Science and Mechanics, 2022
R. Julian Rohit, Ranjan Ganguli
In the MF context, kriging and co-kriging are gaining popularity among researchers. Huang et al. [30] constructed two surrogate models, a kriging based MF (KMF) model and a co-kriging based MF (CKMF) model, for drag reduction optimization of a wing-body design. The full potential coupled with boundary layer (BLFP) method was the LF model, and the Reynolds-averaged Navier-Stokes (RANS) method was the HF model. When built using the same HF data, it was observed that the CKMF model was far more accurate than the KMF model. Also, the optimization results showed that the cost of using the CKMF model was only half of that of using the KMF model. Yong et al. [31] performed structural optimization of an aircraft engine by constructing a co-kriging model using mixed-dimensional FE models. Whole engine models (WEMs) with a 3 D tetrahedral mesh and a 2 D medial mesh were taken as the HF and LF models, respectively. The co-kriging model was compared with an HF kriging model. It was found that the co-kriging model was able to find optimum designs at a mere 57% of the cost of the HF kriging model. Shi et al. [32] performed design optimization of an all-electric geostationary orbit (GEO) satellite system—a multidisciplinary design optimization (MDO) problem. An MF co-kriging model, developed with data from low and high fidelity multidisciplinary analysis (MDA) models, was used in place of the HF MDA model to minimize computational cost. They also used an adaptive infill sampling strategy [33] to improve the MF model. Within the limited computational budget, optimization using the MF model yielded a design having a significantly reduced total mass.