A satellite communications system is based on antennas in a stable orbit above the earth. Satellites serve as relay stations in the sky. The basic idea of satellite communications is that two stations on earth discuss via one or more satellites. So a little bit of satellite-related terminology: 1. Earth station is an antenna on or near the surface of the earth. 2. Uplink is a transmission from ...

Minimum-mass tether designs are developed for a spinning human transport that not only provides artificial gravity, but also the potential for free-return aborts. The investigation reveals that severing the tether can provide a propellant-free boost to return astronauts to Earth in the event of an aborted landing on Mars. Earth–Mars–Earth, Earth–Mars–Venus–Earth, and Earth–Venus–Mars–Earth traj...

One of the main concerns to design earth dam is the stability of the upstream slope of the earth dam in phase of rapid drawdown. Confined pore water pressure reduces the effective stress in this mode, so possibility of the instability and slippage will be increased. The main goal of this research is to investigate changes in the pore water pressure by using horizontal drains in upstream slope o...

magnetotelluric (mt) method is an electromagnetic technique that uses the earth natural field to map the electrical resistivity changes in subsurface structures. because of the high penetration depth of the electromagnetic fields in this method (tens of meters to tens of kilometers), the mt data is used to investigate the shallow to deep subsurface geoelectrical structures and their dimensions....

International Journal of Digital Earth is concerned with the science and technology of Digital Earth and its applications in all major disciplines. The journal has a wide range of interest, but the principal topics are: Digital Earth Framework, Digital Earth Applications, Digital Earth Architecture and Standards, Digital Earth and Earth Systems, Geoinformatics, Geo-spatial Science, Mobile Mappi...

abstract the prediction of active earth pressures is essential to the design of retaining walls in case of reinforced and unreinforced soils. in this study, a new analytical method is presented to determine the coefficient of earth pressure. the horizontal slice method is used to compute the active earth pressure behind a rigid retaining wall in consideration of the granular soils. to verify th...

The earth dynamic system is one of the key scientific questions on the earth science. The thermodynamic behavior and gravity force of the earth and the rheology nature of the mantle prove that mantle convection is the main power source leading the lithosphere to break and move. Yet the directivity of both the structures in the crust and plate movement reminds of the earth rotation. Here we demo...

Using geographical information systems (GIS) has been of great interest lately. A lot of GIS applications are being introduced to regular and noncomputer-expert people through their everyday used machines such as cars (GPS), mobile (location systems), Internet (locating systems and direction guiders), and others. ”Google Earth,” a free online application, is one of those online geographical sys...

the nature of war (mühārebeh)   mehdi esmaeli [1]     abstract:   the verse 33 of ma’deh addresses criminalization of war (mühārebeh) and corruption on earth (efsad-fel-arz),  but has not provided any definition of such terms. some jurists consider such terms as one and the same while there are others who differentiate them. indications relevant to addictions to murder, igniting homes, witching...