Recent Patents on Space Technology - Current Issue
Volume 4, Issue 2, 2014
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High Energy Particle Generation in Cosmic Rays and Solar Particle Events
More LessIt is assumed that cosmic rays and other high-energy particles of extraterrestrial origin can be produced by first-order Fermi diffusive shock acceleration in plasma up to 5x1019 eV, the point where they interact with the cosmic microwave background (CMB). First-order Fermi shock acceleration is due to a supersonic shock with a Mach number dependent on the index (or logarithmic slope) of the shock-induced power-law spectrum. The local all-particle interstellar cosmic-ray spectrum can be obtained from the solution of a Fredholm integral equation in rigidity, yielding both the “knee” and the “ankle” of the primary spectrum. The effect of the maximum galactic acceleration mechanism at high energies near the ankle is to increase the relative number of heavy nuclei relative to protons. Multiple cutoffs of heavier nuclei due to interactions with the CMB have the opposite effect just below the Greisen-Zatsepin-Kuz’min (GZK) cutoff, resulting in fluxes enriched in protons. Earthward-directed supersonic coronal mass ejections are responsible for the great bulk of high-energy solarparticle events because of diffusive shock acceleration in the heliosphere.
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Lorentz Invariance and the Global Positioning System
More LessAn example is considered (clock riddle) which demonstrates that opposite results are obtained for the length of an object depending on whether FitzGerald-Lorentz contraction (FLC) is assumed or instead the determination is based on the elapsed time required for a light pulse to traverse between its endpoints. This lack of internal consistency in relativity theory is traced to an undeclared assumption Einstein made regarding a normalization factor appearing in his original derivation of the Lorentz transformation (LT). If the empirical relationship between clock rates employed in the methodology of the Global Positioning System (GPS) is used to fix the value of this factor, an alternative Lorentz transformation (ALT) is shown to result that removes the above inconsistency, while still satisfying Einstein’s two postulates of relativity and remaining compatible with Einstein’s relativistic velocity transformation (VT) as well.
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Thermal Systems Engineering Design and Analysis of a High Usability Host Spacecraft
Authors: Kevin R. Anderson, Daniel Forgette, Matthew DeVost, Austin Smith and Donald EdbergRecent efforts in space exploration have focused on budget solutions for monitoring Earth’s climate and astrophysics. Implementing such a satellite requires thermal design in order to maintain the scientific instruments and bus components within their ideal operating temperatures. This paper outlines the thermal system’s engineering design and thermal analysis for a High Usability Host Spacecraft. Preliminary thermal engineering results suggest that the High Usability Host Spacecraft concept proposed herein is viable for low-cost scientific instrumentation satellite based missions.
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Robust Aligned Carbon Nanotube Tape with Excellent Piezoelectric Properties
Authors: Dennis S. Tucker, Xin Wang, Kelly Stano, Philip D. Bradford, Mike Allen, Mohan Sanghadasa and Yuntian ZhuWe report a highly aligned multiwalled carbon nanotube (MWCNT) tape with a P(VDF-TrFE) matrix that is mechanically robust and has excellent piezoelectric properties for sensor applications, including, but not limited to vibration gyroscopes and accelerometers. The tapes were tested for piezoelectric response via hysteresis measurements and d33 measurements. It was found that 10 weight percent P(VDF-TrFE) in a solution of DMSO resulted in increased values of dielectric constant, piezoelectric coefficient and mechanical properties. The d33 value for the CNT/P(VDF-TrFE) was 70 pm/V, which is approximately twice that for pure P(VDF-TrFE) film. Adding 10 weight percent BaTiO3 nanoparticles (100nm) increased the piezoelectric d33 value to 81 pm/V. These results are attributed to Maxwell-Wagner-Sillars polarization. This material has a tensile strength of 120 MPa and a Young’s modulus of 17.8 GPa.
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Space-borne Passive Microwave Remote Sensing of Soil Moisture: A Review
More LessSoil moisture (SM) plays an important role in groundwater recharge, runoff, air moisture, atmospheric temperature, land degradation, geo-chemical process, surface and sub-surface biota including agriculture, etc. Several studies have reported comparable results of space-borne passive microwaves remote sensing of surface (2 to 5 cm) SM using relationship between volumetric SM and brightness temperature, dielectric constant, polarimetry, roughness parameter, mathematical inferences, etc. However, reported success studies are very site-, image -, overpass time-, model- and situation specific and insufficient to reach at global conclusions. Therefore, reported methods, techniques and algorithms should thoroughly be tested in different biophysical environments to assess applicability in SM retrievals using microwave data captured at different frequencies, polarization, angle, time, etc.
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