Search results for "e-passi"
showing 5 items of 5 documents
PHYSICS-based retrieval of scattering albedo and vegetation optical depth using multi-sensor data integration
2017
Vegetation optical depth and scattering albedo are crucial parameters within the widely used τ-ω model for passive microwave remote sensing of vegetation and soil. A multi-sensor data integration approach using ICESat lidar vegetation heights and SMAP radar as well as radiometer data enables a direct retrieval of the two parameters on a physics-derived basis. The crucial step within the retrieval methodology is the calculus of the vegetation scattering coefficient KS, where one exact and three approximated solutions are provided. It is shown that, when using the assumption of a randomly oriented volume, the backscatter measurements of the radar provide a sufficient first order estimate and …
Analysis of the radar vegetation index and assessment of potential for improvement
2018
The Radar Vegetation Index (RVI) is widely applied to indicate vegetation cover. The index includes the backscattering intensities of co- and cross-polarization that do not only contain information coming from vegetation scattering at longer wavelength (L-band), but also from the soil underneath. A forward modelling approach using active and passive microwave-derived parameters to obtain the scattering contribution of the soil is pursued. The idea of this research study is a subtraction of the attenuated soil scattering contribution from the measured backscattering intensities, to provide a clean vegetation-based solution, called improved RVI (RVII). For latter analysis, the vegetation volu…
The SMAP and Copernicus Sentinel 1A/B microwave active-passive high resolution surface soil moisture product
2019
Abstract Soil Moisture Active Passive (SMAP) mission of NASA was launched in January 2015. Currently, SMAP has an L-band radiometer and a defunct L-band radar with a rotating 6-m mesh reflector antenna. On July 7th, 2015, the SMAP radar malfunctioned and became inoperable. Consequently, the production of high-resolution active-passive soil moisture product got hampered, and only ~2.5 months (April 15th, 2015 to July 7th, 2015) of data remain available. Therefore, during the SMAP post-radar phase, many ways were examined to restart the high-resolution soil moisture product generation of the SMAP mission. One of the feasible approaches was to substitute the SMAP radar with other available SAR…
E-passin teknologiaratkaisu
2017
Tutkielmassa kerrotaan passin kehitys tavallisesta matkustusasiakirjasta e-passiksi. Työssä esitellään e-passin sovelluksen tekniset ratkaisut. Teknologiaratkaisuun kuuluu olennaisena RFID -mikrosiru ja sille tallennettu biometrinen tunniste. Tutkimuksessa selvitetään yleisemmät biometriset tunnisteet ja niiden käsittelyvaiheet. Työ on tieteellisiin artikkeleihin perustuva kirjoitelma. Yhdysvaltojen e-passiin toteutettiin RFID-tunniste ja se sai aikanaan arvostelua teknologiavalinnoista. Euroopan ja Suomen e-passien kehitykseen on vaikuttanut kokemukset Yhdysvaltojen e-passin käyttöönottoprojektista. Tutkielmassa pyritään löytämään eroja Yhdysvaltojen, Euroopan ja Suomen e-passien tietoturv…
Modeling and Mitigating Errors in Belief Propagation for Distributed Detection
2021
We study the behavior of the belief-propagation (BP) algorithm affected by erroneous data exchange in a wireless sensor network (WSN). The WSN conducts a distributed multidimensional hypothesis test over binary random variables. The joint statistical behavior of the sensor observations is modeled by a Markov random field whose parameters are used to build the BP messages exchanged between the sensing nodes. Through linearization of the BP message-update rule, we analyze the behavior of the resulting erroneous decision variables and derive closed-form relationships that describe the impact of stochastic errors on the performance of the BP algorithm. We then develop a decentralized distribute…