50 research outputs found
Scene-based nonuniformity correction for focal plane arrays by the method of the inverse covariance form
What is to our knowledge a new scene-based algorithm for nonuniformity correction in infrared focal-plane array sensors has been developed. The technique is based on the inverse covariance form of the Kalman filter (KF), which has been reported previously and used in estimating the gain and bias of each detector in the array from scene data. The gain and the bias of each detector in the focal-plane array are assumed constant within a given sequence of frames, corresponding to a certain time and operational conditions, but they are allowed to randomly drift from one sequence to another following a discrete-time Gauss-Markov process. The inverse covariance form filter estimates the gain and the bias of each detector in the focal-plane array and optimally updates them as they drift in time. The estimation is performed with considerably higher computational efficiency than the equivalent KF. The ability of the algorithm in compensating for fixed-pattern noise in infrared imagery and in reducing the computational complexity is demonstrated by use of both simulated and real data
Multi-Model Kalman Filtering for Adaptive Nonuniformity: Correction in Infrared Sensors
This paper presents an adaptive technique for the estimation of nonuniformity parameters of infrared focal-plane arrays that is robust with respect to changes and uncertainties in scene and sensor characteristics. The proposed algorithm is based on using a bank of Kalman filters in parallel. Each filter independently estimates state variables comprising the gain and the bias matrices of the sensor, according to its own dynamical-model parameters, which underly the statistics of the scene and the nonuniformity as well as the temporal drift in the nonuniformity. The supervising component of the algorithm then generates the final estimates of the state variables by forming a weighted superposition of all the estimates rendered by each Kalman filter. The weights are obtained according to the a posteriori -likelihood principle, applied to the family of models by considering the output residual errors associated with each filter. These weights are updated iteratively between blocks of data, providing the estimator the means to follow the dynamics of the scenes and the sensor. The performance of the proposed estimator and its ability to compensate for fixed-pattern noise are tested using both real and simulated data. The real data is obtained using two cameras operating in the mid- and long-wave infrared regime
Demonstration of a Bias Tunable Quantum Dots-in-a-well Focal Plane Array
Infrared detectors based on quantum wells and quantum dots have attracted a lot of attention in the past few years. Our previous research has reported on the development of the first generation of quantum dots-in-a-well (DWELL) focal plane arrays, which are based on InAs quantum dots embedded in an InGaAs well having GaAs barriers. This focal plane array has successfully generated a two-color imagery in the mid-wave infrared (i.e. 3â5 ÎŒm) and the long-wave infrared (i.e. 8â12 ÎŒm) at a fixed bias voltage. Recently, the DWELL device has been further modified by embedding InAs quantum dots in InGaAs and GaAs double wells with AlGaAs barriers, leading to a less strained InAs/InGaAs/GaAs/AlGaAs heterostructure. This is expected to improve the operating temperature while maintaining a low dark current level. This paper examines 320 Ă 256 double DWELL based focal plane arrays that have been fabricated and hybridized with an Indigo 9705 read-out integrated circuit using Indium-bump (flip-chip) technology. The spectral tunability is quantified by examining images and determining the transmittance ratio (equivalent to the photocurrent ratio) between mid-wave and long-way infrared filter targets. Calculations were performed for a bias range from 0.3 to 1.0 V. The results demonstrate that the mid-wave transmittance dominates at these low bias voltages, and the transmittance ratio continuously varies over different applied biases. Additionally, radiometric characterization, including array uniformity and measured noise equivalent temperature difference for the double DWELL devices is computed and compared to the same results from the original first generation DWELL. Finally, higher temperature operation is explored. Overall, the double DWELL devices had lower noise equivalent temperature difference and higher uniformity, and worked at higher temperature (70 K and 80 K) than the first generation DWELL device
Stratus 14 : fourteenth setting of the Stratus Ocean Reference Station cruise on board RV Cabo de Hornos April 14 - 30, 2015 Valparaiso, Chile
The Ocean Reference Station at 20°S, 85°W under the stratus clouds west of northern Chile is
being maintained to provide ongoing climate-quality records of surface meteorology, air-sea
fluxes of heat, freshwater, and momentum, and of upper ocean temperature, salinity, and velocity
variability. The Stratus Ocean Reference Station (ORS Stratus) is supported by the National
Oceanic and Atmospheric Administrationâs (NOAA) Climate Observation Program. It is
recovered and redeployed annually, with past cruises that have come between October and
January. This cruise was conducted on the Chilean research vessel Cabo de Hornos.
During the 2015 cruise on the Cabo de Hornos to the ORS Stratus site, the primary activities
were the recovery of the previous (Stratus 13) WHOI surface mooring, deployment of the new
Stratus 14 WHOI surface mooring, in-situ calibration of the buoy meteorological sensors by
comparison with instrumentation installed on the ship and CTD casts near the moorings. Surface
drifters were also launched along the track.Funding was provided by the National Oceanic and Atmospheric Administration
under Grant No. NA140AR432015
A Social Platform for Fostering Ethical Education through Role-Playing
Nowadays the complexity of knowledge, the specialization of labor and the pervasiveness of ICT in human activity, lead individuals to frequently make complex decisions with ethical implications. The educational system has a fundamental role in preparing specialized human capital in every discipline, however, it also faces the challenge of educating individuals with ethical discernment capabilities and behavior. In this book chapter, we describe the design, implementation and validation of EthicApp-RP, a social platform aimed at higher education settings, for fostering reflection and moral reasoning around ethical cases through a role-playing activity. We present an application of EthicApp-RP involving a cohort of undergraduate business students (NÂ =Â 85), based on a case in which students play political and public leadership roles in the midst of the COVID-19 crisis. The results indicate that students and teachers acknowledge the learning environmentâs capacity to stimulate reflection and argumentation around ethical issues, while providing all students with equal opportunities for participation. In addition, the tool offers high technical and pedagogical usability, based on the Systems Usability Scale and the Pedagogically Meaningful Learning Questionnaire. EthicApp-RP can contribute to the improvement of ethics education, especially in scientific and technological disciplines, wherein students are quantitatively inclined by nature, in spite that ethics, a humanistic subject often foreign to them, must live at the core of their preparation
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Ship Observations of the Tropical Pacific Ocean along the Coast of South America
In October 2007 the NOAA ship Ronald H. Brown sailed southward within 300 km of the coast of Ecuador and Peru, sampling surface meteorology, airâsea turbulent and radiative fluxes, cloud properties, and upper-air soundings from the equator to 20°S. Two distinct water masses characterize the coastal region: cold-pool water below 19°C in the Southern Hemisphere, and warm-pool water above 20°C to the north, with a transition between the water masses at 2.5°S. Net turbulent and radiative fluxes warm the cool water south of 2.5°S by 100 W mâ»ÂČ but do not warm the equatorial water significantly. Winds blow parallel to the shore, about 5 m sâ»Âč over the cold pool and 7 m sâ»Âč over the equator. Stratocumulus clouds are remarkably solid over the coastal cold pool, with only brief periods of partial clearing, mostly in the afternoon. Lower aerosol concentrations and thicker clouds observed farther from the coast on 22â23 October are coincident with a pocket of open cells seen to the west and southwest of the ship. Observations from this cruise and other NOAA Stratus cruises (2001 and 2003â07) are suitable for comparison with model simulations and provide context for future field experiments. These datasets are publicly available.Keywords: Pacific Ocean, South America, Ship observations, Tropic
Stratus Ocean Reference Station (20ËS, 85ËW), mooring recovery and deployment cruise R/V Ronald H. Brown cruise 05-05, September 26, 2005âOctober 21, 2005
The Ocean Reference Station at 20°S, 85°W under the stratus clouds west of northern Chile is being maintained to provide
ongoing, climate-quality records of surface meteorology, of air-sea fluxes of heat, freshwater, and momentum, and of upper ocean
temperature, salinity, and velocity variability. The Stratus Ocean Reference Station (ORS Stratus) is supported by the National
Oceanic and Atmospheric Administrationâs (NOAA) Climate Observation Program. It is recovered and redeployed annually, with
cruises that have come between October and December. During the October 2005 cruise of NOAAâs R/V Ronald H. Brown to the
ORS Stratus site, the primary activities were recovery of the WHOI surface mooring that had been deployed in December 2004,
deployment of a new WHOI surface mooring at that site, in-situ calibration of the buoy meteorological sensors by comparison
with instrumentation put on board by staff of the NOAA Environmental Technology Laboratory (ETL), and observations of the
stratus clouds and lower atmosphere by NOAA ETL. The ORS Stratus buoys are equipped with two Improved Meteorological
(IMET) systems, which provide surface wind speed and direction, air temperature, relative humidity, barometric pressure,
incoming shortwave radiation, incoming longwave radiation, precipitation rate, and sea surface temperature. The IMET data are
made available in near real time using satellite telemetry. The mooring line carries instruments to measure ocean salinity,
temperature, and currents. The ETL instrumentation used during the 2005 cruise included cloud radar, radiosonde ballons, and
sensors for mean and turbulent surface meteorology. In addition, two technicians from the University of Concepcion collected
water samples for chemical analysis. Finally, the cruise hosted a teacher participating in NOAAâs Teacher at Sea Program.Funding was provided by the National Oceanic and Atmospheric Administration
under Grant No. NA17RJ1223 and the Cooperative Institute for Climate and Ocean Research (CICOR)
Stratus 16 Sixteenth Setting of the Stratus Ocean Reference Station Cruise on Board RV Ronald H. Brown May 5 - 20, 2017 Rodman, Panama - Arica, Chile
The Ocean Reference Station at 20°S, 85°W under the stratus clouds west of northern Chile is being maintained to provide ongoing climate-quality records of surface meteorology, air-sea fluxes of heat, freshwater, and momentum, and of upper ocean temperature, salinity, and velocity variability. The Stratus Ocean Reference Station (ORS Stratus) is supported by the National
Oceanic and Atmospheric Administrationâs (NOAA) Climate Observation Program. It is recovered and redeployed annually, with past cruises that have come between October and May. This cruise was conducted on the NOAA research vessel Ronald H. Brown.
During the 2017 cruise on the Ronald H. Brown to the ORS Stratus site, the primary activities were the recovery of the previous (Stratus 15) WHOI surface mooring, deployment of the new Stratus 16 WHOI surface mooring, in-situ calibration of the buoy meteorological sensors by comparison with instrumentation installed on the ship, CTD casts near the moorings. Surface drifters and ARGO floats were also launched along the track.Funding was provided by the National Oceanic and Atmospheric Administration under Grant No. NA14OAR432015
WHOI Hawaii Ocean Timeseries Station (WHOTS) : WHOTS-8 2011 mooring turnaround cruise report
Note: author "Ludovic Bariteau" is incorrectly listed as "Bariteau Ludovic" on the Cover and Title Page.The Woods Hole Oceanographic Institution (WHOI) Hawaii Ocean Timeseries (HOT) Site
(WHOTS), 100 km north of Oahu, Hawaii, is intended to provide long-term, high-quality air-sea
fluxes as a part of the NOAA Climate Observation Program. The WHOTS mooring also serves
as a coordinated part of the HOT program, contributing to the goals of observing heat, fresh
water and chemical fluxes at a site representative of the oligotrophic North Pacific Ocean. The
approach is to maintain a surface mooring outfitted for meteorological and oceanographic
measurements at a site near 22.75°N, 158°W by successive mooring turnarounds. These
observations will be used to investigate airâsea interaction processes related to climate
variability.
This report documents recovery of the seventh WHOTS mooring (WHOTS-7) and deployment
of the eighth mooring (WHOTS-8). Both moorings used Surlyn foam buoys as the surface
element and were outfitted with two AirâSea Interaction Meteorology (ASIMET) systems. Each
ASIMET system measures, records, and transmits via Argos satellite the surface meteorological
variables necessary to compute airâsea fluxes of heat, moisture and momentum. The upper 155
m of the moorings were outfitted with oceanographic sensors for the measurement of
temperature, conductivity and velocity in a cooperative effort with R. Lukas of the University of
Hawaii. A pCO2 system was installed on the WHOTS-8 buoy in a cooperative effort with Chris
Sabine at the Pacific Marine Environmental Laboratory. A set of radiometers were installed in
cooperation with Sam Laney at WHOI.
The WHOTS mooring turnaround was done on the NOAA ship Hiâialakai by the Upper Ocean
Processes Group of the Woods Hole Oceanographic Institution. The cruise took place between 5
July and 13 July 2011. Operations began with deployment of the WHOTS-8 mooring on 6 July.
This was followed by meteorological intercomparisons and CTDs. Recovery of WHOTS-7 took
place on 11 July 2011. This report describes these cruise operations, as well as some of the in-port
operations and pre-cruise buoy preparations.Funding was provided by the National Oceanic and Atmospheric Administration under Grant No.
NA090AR4320129 and the Cooperative Institute for the North Atlantic Region (CINAR)
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A Motion-Stabilized W-Band Radar for Shipboard Observations of Marine Boundary-Layer Clouds
Cloud radars at X, Ka and W-bands have been used in the past for ocean studies of clouds, but the lack of suitable stabilization has limited their usefulness in obtaining accurate measurements of the velocity structure of cloud particles and the heights of cloud features. A 94 GHz (W-band) radar suitable for use on shipboard studies of clouds has been developed that is small and lightweight and can maintain the radarâs beam pointing in the vertical to reduce the affects of the pitch and roll of the ship. A vertical velocity sensor on the platform allows the effects of the shipâs heave to be removed from the measured cloud particle motions. Results from the VAMOS Ocean-Cloud-Atmosphere-Land Study Regional Experiment (VOCALS-Rex) field program on the NOAA vessel Ronald H. Brown demonstrate the improvements to the cloud measurements after the shipâs motion effects are removed. The compact design of the radar also makes it suitable for use in aircraft studies. The radar is being repackaged to fit in an aft bay of a NOAA P3 aircraft to observe sea-spray profiles during ocean storms.Keywords: VOCALS 2008, Shipboard motion stabilization, Marine boundary-layer clouds, Cloud rada