Search results for " Sensing"

Synthesis of tetrasubstituted-4,4'-biimidazoles with perspective heavy-metal sensing ability

2012

Urbanization and forest degradation in east Africa - a case study around Dar es Salaam, Tanzania

2016

In this paper we examine the impact of the growing urbanization of Dar es Salaam, Tanzania, on the forest areas around the city. Since 1990 the city has seen an annual population growth rate of over 4%. We document the expansion of the city over the last 30 using the Global Human Settlement Layers, derived from the global Landsat archive. At the same time we show the depletion, of the surrounding forests that has occurred to meet the growing demand for agricultural land, fuel wood and construction material over the same period. The impact on these forests as a result of the demand from an expanding urban conglomeration is higher than would be expected from a dispersed population increase. T…

Retrieving and broadcasting near-real-time biophysical parameters from MODIS and SEVIRI receiving stations at the global change unit of the Universit…

2015

We present here the automatic processing chains implemented at the Global Change Unit of the University of Valencia. These allow for a near-real-time retrieval of various biophysical parameters from both Sun-synchronous TERRA/AQUA Moderate Resolution Imaging Spectroradiometer MODIS and geostationary Meteosat Second Generation Spinning Enhanced Visible and Infrared Imager MSG SEVIRI sensors. Retrieved parameters, namely sea and land surface temperatures SST and LST, respectively, normalized difference vegetation index NDVI, and vegetation condition index VCI, are similar for both sensors, and specific approaches have been developed and implemented for near-real-time parameter retrievals: htt…

Comparison of aerosol optical thickness retrieval from spectroradiometer measurements and from two radiative transfer models

2000

Abstract The spectral values of the aerosol optical thickness τ a λ in the 400–670 nm band have been determined from 500 solar direct irradiance spectra at normal incidence registered at Valencia (Spain) in the period from July 1993 to March 1997. The τ a λ values obtained from experimental measurements have been compared with the boundary layer aerosol models implemented in the radiative transfer codes ZD-LOA and LOWTRAN 7. For the ZD-LOA code, the continental and maritime models have been considered and for the LOWTRAN 7 code the rural, maritime, urban and tropospheric models have been used. The obtained results show that the aerosol model that best represents the average turbidity of the…

Quorum Sensing effects on Pseudomonas corrugata plant interaction and antagonistic activity

2010

A new calibration of the effective scattering albedo and soil roughness parameters in the SMOS SM retrieval algorithm

2017

Abstract This study focuses on the calibration of the effective vegetation scattering albedo (ω) and surface soil roughness parameters (H R , and N Rp , p = H,V) in the Soil Moisture (SM) retrieval from L-band passive microwave observations using the L-band Microwave Emission of the Biosphere (L-MEB) model. In the current Soil Moisture and Ocean Salinity (SMOS) Level 2 (L2), v620, and Level 3 (L3), v300, SM retrieval algorithms, low vegetated areas are parameterized by ω = 0 and H R  = 0.1, whereas values of ω = 0.06 − 0.08 and H R  = 0.3 are used for forests. Several parameterizations of the vegetation and soil roughness parameters (ω, H R and N Rp , p = H,V) were tested in this study, tre…

A sun-induced vegetation fluorescence retrieval method from top of atmosphere radiance for the FLEX/Sentinel-3 TanDEM mission

2015

A new fluorescence retrieval method is proposed to support ESA's 8th Earth Explorer FLuorescence EXplorer/Sentinel-3 (FLEX-S3) candidate tandem mission. FLEX is the first mission specially dedicated to measure the Sun-Induced vegetation chlorophyll fluorescence (SIF) strongly related with the vegetation photosynthetic activity. Most hyperspectral fluorescence retrieval algorithms available in the literature are very sensitive to true reflectance modelization and/or they assume the atmospheric status as known. The proposed algorithm delivers the retrieval of full fluorescence spectrum at canopy level by using only Top Of Atmosphere (TOA) radiances from S3 and FLEX as input. Once the spatial …

Analysis of thermal infrared data from the Digital Airborne Imaging Spectrometer

2001

Thermal infrared data of the Digital Airborne Imaging Spectrometer (DAIS), whose channels 74-79 are in the 8-13 w m waveband region, were analysed with the aim of recovering land surface temperature (LST). DAIS images were acquired over an experimental site where field and laboratory emissivity measurements were performed, and these were used to recover the LST from the six DAIS thermal channels. Atmospheric correction of DAIS data was calculated by means of a nearby radiosounding and a radiative transfer model. DAIS derived LSTs were compared with ground measurements of LST made coincidentally for a few test fields, the central DAIS channels yielding temperatures up to 10°C higher than gro…

Conductive and Capacitive Properties of the Bipolar Membrane Junction Studied by AC Impedance Spectroscopy

2001

The complete ac impedance spectrum of four bipolar membranes is analyzed both theoretically and experimentally taking into account both ionic transport and water dissociation together with the structural aspects of the bipolar junction. A theoretical model based on the Nernst-Planck and Poisson equations for the conductive and capacitive properties of the junction provides a qualitative description of the bipolar membranes for a broad range of electric currents and temperatures. Special attention is paid to the characteristics of the bipolar junction structure and the contact region between the two ion-exchange layers. It is observed that the effective area of this region increases with the…

CMOS Capacitance-to-Time Converter-Based Interface for Differential Capacitive Sensors

2020

This paper presents pre-layout simulation results on a CMOS implementation of a capacitance-to-time converter-based electronic interface for differential capacitive sensors. Its simple architecture, comprising only three operational amplifiers (OA) and a digital mixer (inverted XOR gate) allows, by properly setting the values of seven biasing resistors, to fit the working range anywhere from few fF to hundreds of pF, giving the output quasi-digital signals (T and PW) in the useful μs-ms range (appropriate for direct interfacing with general purposes microcontrollers). A couple of illustrative examples are provided.