Search results for "BAND"
showing 10 items of 2610 documents
Characterization of PP-cLT Waveguides for Second-Harmonic-Generation and Wavelength-Conversion in the C + L Band of Optical Communications
2010
We report the characterization of single-mode optical waveguides at telecom wavelength, realized in congruent lithium-tantalate. We demonstrate that waveguides realized by proton-exchange show a nonlinear coefficient matching that expected in a bulk crystal.
Comparison of downscaling techniques for high resolution soil moisture mapping
2017
Soil moisture impacts exchanges of water, energy and carbon fluxes between the land surface and the atmosphere. Passive microwave remote sensing at L-band can capture spatial and temporal patterns of soil moisture in the landscape. Both ESA and NASA have launched L-band radiometers, in the form of the SMOS and SMAP satellites respectively, to monitor soil moisture globally, every 3-day at about 40 km resolution. However, their coarse scale restricts the range of applications. While SMAP included an L-band radar to downscale the radiometer soil moisture to 9 km, the radar failed after 3 months and this initial approach is not applicable to developing a consistent long term soil moisture prod…
Intercomparison of soil moisture retrieved from GNSS-R and passive L-band radiometry at the Valencia Anchor Station
2016
In this paper, the SOMOSTA (Soil Moisture Monitoring Station) experiment on soil moisture monitoring by Global Navigation Satellite System Reflected signals(GNSS-R) at the Valencia Anchor Station is introduced.
Retrieval of Forest Water Potential from L-Band Vegetation Optical Depth
2021
A retrieval methodology for forest water potential from ground-based L-band radiometry is proposed. It contains the estimation of the gravimetric and the relative water content of a forest stand and tests in situ- and model-based functions to transform these estimates into forest water potential. The retrieval is based on vegetation optical depth data from a tower-based experiment of the SMAPVEX 19–21 campaign for the period from April to October 2019 at Harvard Forest, MA, USA. In addition, comparison and validation with in situ measurements on leaf and xylem water potential as well as on leaf wetness and complex permittivity are foreseen to understand limitations and potentials of the pro…
Analyzing the impact of using the SRP (Simplified roughness parameterization) method on soil moisture retrieval over different regions of the globe
2015
International audience; This paper focuses on a new approach to account for soil roughness effects in the retrieval of soil moisture (SM) at L-band in the framework of the SMOS (Soil Moisture and Ocean Salinity) mission: the Simplified Roughness Parameterization (SRP). While the classical retrieval approach considers SM and τ nad (vegetation optical depth) as retrieved parameters, this approach is based on the retrieval of SM and the TR parameter combining τ nad and soil roughness (TR τ nad + Hr /2). Different roughness parameterizations were tested to find the best correlation (R), bias and unbiased RMSE (ubRMSE) when comparing homogeneous retrievals of SM and in situ SM measurements carri…
A simple algorithm for retrieval of the optical thickness at L-band from SMOS data
2012
Vegetation indices are indicators for analyzing the properties of vegetation. The Normalized Difference Vegetation Index (NDVI) from optical remote sensing data is one of the most commonly used vegetation indices, which can exhibit the ecological characteristics of leafy materials, but lacks the ability to directly provide information on the woody materials. In this paper, we developed Microwave Vegetation Indices (MVIs) from the L-band Soil Moisture and Ocean Salinity (SMOS) data, which is an effective means to detect the information of branches and trunks. The theory of MVIs is derived from the tau-omega model. To minimize the influence from the uncertain soil surface radiation, a paramet…
La1-xSrxCo1-yFeyO3-delta perovskites: Preparation, characterization and solar photocatalytic activity
2015
Abstract LaCoO3 perovskites substituted by Sr at the A site and/or by Fe at the B site have been prepared by the citrate method. Characterizations by several techniques, such as specific surface area (BET method), XRD, TPR, SEM, UV–vis in DRS mode, XPS and TGA analyses, have been performed. The so prepared La1−xSrxCo1−yFeyO3−δ perovskites are semiconductor materials showing band gap energy values from 1.9 to 3.2 eV. They displayed solar photocatalytic activity for the 2-propanol degradation in gas–solid regime. The photocatalytic results suggest that the perovskites containing Fe are less active and the activity decreases by increasing the Fe content, however the presence of iron avoids the…
An FPGA based Topological Processor Prototype for the ATLAS Level-1 Trigger Upgrade
2012
By 2014 the LHC will collide proton bunches at 14TeV with an increased instantaneous luminosity up to 3·10³⁴cm⁻²s⁻¹. The resulting higher event rate will challenge the existing ATLAS trigger system. A reduction on the trigger rate can be achieved by selecting interesting channels based on their expected decay topology and thus reducing background. This will be achieved by introducing of a new FPGA based module in the Level-1 trigger: the Topological Processor L1Topo. With L1Topo it will be possible for the first time to concentrate detailed information from the entire calorimeters and the muon detector into a single module. L1Topo will receive a total aggregate bandwidth of 1Tb/s. The data …
Ultrascale+ for the new ATLAS calorimeter trigger board dedicated to jet identification
2018
To cope with the expected increase in luminosity at the Large Hadron Collider in 2021, the ATLAS collaboration is planning a major detector upgrade to be installed during Long Shutdown 2. As a part of this, the Level 1 trigger, based on calorimeter data, will be upgraded to exploit the fine granularity readout using a new system of Feature EXtractors (FEXs), which each reconstruct different physics objects for the trigger selection. The Jet FEX (jFEX) is one of three FEXs and has been conceived to identify small/large area jets, large area tau leptons, missing transverse energy and the total sum of the transverse energy. The use of the latest generation Xilinx Field Programmable Gate Array …