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Showing 1 to 12 of 12 for “"refractivity"”.
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Analysis and modelling of the impact of anomalous propagation on terrestrial microwave links in a subtropical region, based on long-term measurements. Statistical analysis of long-term meteorological and signal strength measurements in a subtropical region and investigation of the impact of anomalous refractivity profiles on radio propagation in terrestrial microwave wireless systems
… wireless systems performance. Vertical refractivity profile below 1 km is a critical parameter for designing reliable systems; noting that there is a shortage of upper-air data worldwide. Anomalous phenomena may cause severe signal fading and interference beyond the horizon. The …
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SIGNAL ANALYSIS AND RADIOHOLOGRAPHIC METHODS FOR AIRBORNE RADIO OCCULTATIONS
… direction and delay of the GPS signal to measure refractivity, which provides information on temperature and humidity. The GPS-RO technique is now operational on several Low Earth Orbiting (LEO) satellite missions. Nevertheless, when observing localized transient events, such as tropical storms, …
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An empirical potential for hydrogen bond energies determination of the orientation of anthracene molecules in the unit cell by means of a refractivity method: some ab initio calculations involving acetonitrile exchange reaction
… cell by matching calculated and experimental refractivity ellipsoids using a simplex algorithm. The calculated refractivity ellipsoid is determined by use of an empirical formula using bond directional polarizabilities. Optimization of the molecular orientations to provide the best fit to the …
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Atmospheric water vapour tomography for DInSAR application and effect of volcanic plume on the microwaves
… useful to extrapolate information about the wet refractivity ?eld. Because of its height and the quite variable weather conditions, the estimation of Mount Etna atmospheric anomalies using GPS measurements have noticeable importance to calibrate the SAR interferograms and to establish the …
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Rough Surface Scattering and Propagation over Rough Terrain in Ducting Environments
… formed by the presence of a linear-square refractivity profile is derived using the asymptotic methods of stationary phase and steepest descents. This Green's function is then modified to more closely model the one associated with a physical ducting medium, in which the refractivity profile …
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Forecasting the nighttime evolution of radio wave ducting in complex terrain using the MM5 numerical weather model
… compaction drives changes in the electromagnetic refractivity of the atmosphere that can trap radio waves near the Earth's surface. The sensitivity tests show that increasing the model's horizontal resolution increases the area of predicted ducting significantly. Increasing the vertical resolution …
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Laboratory Measurements of the Millimeter Wavelength Opacity of Phosphine (PH3) and Ammonia (NH3) Under Simulated Conditions for the Cassini-Saturn Encounter
… to measure the microwave absorptivity and refractivity of phosphine and ammonia at Ka-band (32-40 GHz) and W-band (94 GHz), under conditions characteristic of the atmosphere of Saturn. The results were used to verify the accuracy of the phosphine formalism created by Hoffman et. al (2001) …
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Piezo-optical study of the behaviour of short chain liquid polymers
… equation applies with constant molar refractivity. Viscosity is exponentially, and hypersonic phonon velocity linearly, dependent on density, though Schaaff's equation is incorrect. A relaxation of 10(to the power of -11) was observed for the polyisobutenes. In all cases, the important …
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Assessment of taxol activity: Bioavailability in human physiological fluids and QSAR of taxol analogues based on a neural network design
… are calculated descriptors (lipophilicity, molar refractivity, dipole moment plus dipole vectors, steric plus conformation energies, and heat of formation). High antitumor activity is predicted for taxol analogues with a substituent propionic, 1-methyl-2-pyrrolecarboxylic, or crotonic acid in …
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Three-dimensional water vapor retrieval using a network of scanning compact microwave radiometers
… on the magnitude of the path-integrated refractivity. Microwave radiometers in low-earth orbit provide reasonable vertical resolution (2 km) and mesoscale horizontal resolution (20 km) with long repeat times. Both the prediction of convective initiation and quantitative precipitation …
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Effects of the troposphere upon radio communications and implications for weather measurement
The aim of this research is to use observations of Very High Frequency (VHF) radio wave propagation to estimate the refractive index of air over a propagation path and subsequently the pressure, temperature, and water vapour. This can be accomplished by transmitting a known signal from one spatial …
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ΣΥΜΒΟΛΗ ΣΤΗ ΜΕΛΕΤΗ ΤΗΣ ΕΠΙΔΡΑΣΗΣ ΤΗΣ ΑΤΜΟΣΦΑΙΡΙΚΗΣ ΔΙΑΘΛΑΣΗΣ ΚΑΤΑ ΤΗ ΧΡΗΣΗ ΡΑΔΙΟΚΥΜΑΤΩΝ ΣΤΙΣ ΣΥΓΧΡΟΝΕΣ ΓΕΩΔΑΙΤΙΚΕΣ ΜΕΘΟΔΟΥΣ ΜΕΤΡΗΣΕΩΝ ΜΕΓΑΛΩΝ ΑΠΟΣΤΑΣΕΩΝ
THE THREE MAIN EFFECTS OF THE ATMOSPHERE ON RADIOWAVE PROPAGATION ARE: ATTENUATION, TIME DELAY AND ANGULAR BENDING. THE TIME DELAY CAN BE SEPARATED INTO HYDROSTATIC AND WET DELAY. DEVELOPED HERE ARE MODELS FOR THE ZENTH WET DELAY ESTIMATION AND FOR THE ELEVATION DEPENDENCE OF THE HYDROSTATIC AND …