81 research outputs found
Wave Height Characteristics in the North Atlantic Ocean: A new approach based on Statistical and Geometrical techniques
Stochastic Environmental Research and Risk AssessmentThe article of record as published may be located at http://dx.doi.org/10.1007/s00477-011-0540-2The main characteristics of the significant wave
height in an area of increased interest, the north Atlantic
ocean, are studied based on satellite records and corresponding
simulations obtained from the numerical wave
prediction model WAM. The two data sets are analyzed by
means of a variety of statistical measures mainly focusing
on the distributions that they form. Moreover, new techniques
for the estimation and minimization of the discrepancies
between the observed and modeled values are
proposed based on ideas and methodologies from a relatively
new branch of mathematics, information geometry.
The results obtained prove that the modeled values overestimate
the corresponding observations through the whole
study period. On the other hand, 2-parameter Weibull distributions
fit well the data in the study. However, one cannot
use the same probability density function for describing the
whole study area since the corresponding scale and shape
parameters deviate significantly for points belonging to different regions. This variation should be taken into
account in optimization or assimilation procedures, which is
possible by means of information geometry techniques
Feasibility Study of Enhancing Microwave Brain Imaging Using Metamaterials
We present an approach to enhance microwave brain imaging with an innovative metamaterial (MM) planar design based on a cross-shaped split-ring resonator (SRR-CS). The proposed metasurface is incorporated in different setups, and its interaction with EM waves is studied both experimentally and by using CST Microwave Studio R and is compared to a âno MMâ case scenario. We show that the MM can enhance the penetration of the transmitted signals into the human head when placed in contact with skin tissue, acting as an impedance-matching layer. In addition, we show that the MM can improve the transceiversâ ability to detect useful âweakâ signals when incorporated in a headband scanner for brain imaging by increasing the signal difference from a blood-like dielectric target introduced into the brain volume. Our results suggest that the proposed MM film can be a powerful hardware advance towards the development of scanners for brain haemorrhage detection and monitoring
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Extreme dust storm over the eastern Mediterranean in September 2015: Satellite, lidar, and surface observations in the Cyprus region
A record-breaking dust storm originating from desert regions in northern Syria and Iraq occurred over the eastern Mediterranean in September 2015. In this contribution of a series of two articles (part 1, observations; part 2, atmospheric modeling), we provide a comprehensive overview of the aerosol conditions during this extreme dust outbreak in the Cyprus region. These observations are based on satellite observations (MODIS, moderate resolution imaging spectroradiometer) of aerosol optical thickness (AOT) and Ă
ngström exponent, surface particle mass (PM10) concentrations measured at four sites in Cyprus, visibility observations at three airports in southern Cyprus and corresponding conversion products (particle extinction coefficient, dust mass concentrations), EARLINET (European Aerosol Research Lidar Network) lidar observations of dust vertical layering over Limassol, particle optical properties (backscatter, extinction, lidar ratio, linear depolarization ratio), and derived profiles of dust mass concentrations. Maximum 550âŻnm AOT exceeded values of 5.0, according to MODIS, and the mass loads were correspondingly >ââŻ10âŻgâŻmâ2 over Larnaca and Limassol during the passage of an extremely dense dust front on 8 September 2015. Hourly mean PM10 values were close to 8000âŻÂ”gâŻmâ3 and the observed meteorological optical range (visibility) was reduced to 300â750âŻm at Larnaca and Limassol. The visibility observations suggest peak values of the near-surface total suspended particle (TSP) extinction coefficients of 6000âŻMmâ1 and thus TSP mass concentrations of 10âŻ000âŻÂ”gâŻmâ3. The Raman polarization lidar observations mainly indicated a double layer structure of the dust plumes (reaching to about 4âŻkm height), pointing to at least two different dust source regions. Dust particle extinction coefficients (532âŻnm) already exceeded 1000âŻMmâ1 and the mass concentrations reached 2000âŻÂ”gâŻmâ3 in the elevated dust layers on 7 September, more than 12âŻh before the peak dust front on 8 September reached the Limassol lidar station around local noon. Typical Middle Eastern dust lidar ratios around 40âŻsr were observed in the dense dust plumes. The particle depolarization ratio decreased from around 0.3 in the lofted dense dust layers to 0.2 at the end of the dust period (11 September), indicating an increasing impact of anthropogenic haze
Analyzing Black Cloud Dynamics over Cairo, Nile Delta Region and Alexandria using Aerosols and Water Vapor Data
Cairo is the largest city of Africa and one of the worldâs megacities, with a population of more than 20 million people and containing more than one third of the national industry. It is a rapidly expanding city which leads to many associated environmental problems. As a result, it is also one of the most air polluted megacities in the world (Molina and Molina, 2004). It suffers from high ambient concentrations of atmospheric pollutants including particulates (PM), carbon monoxide, nitrogen oxides, ozone and sulfur dioxide (Abu-Allaban et al., 2007, Abu-Allaban et al., 2002, El-Metwally et al., 2008). The pollution phenomenon locally known as âBlack cloudâ over Cairo has been attributed to many reasons among which are biomass burning, local emission and long range transport during the fall season.Several studies have been conducted to address and discuss the forth mentioned reasons for the increased pollution levels over Cairo and the greater Delta region using ground-based and satellite air quality data as compared to other megacities.https://digitalcommons.chapman.edu/sees_books/1000/thumbnail.jp
Metamaterial designs to enhance microwave imaging applications
This paper presents an innovative metasurface design for emerging microwave brain imaging applications, such as stroke detection and monitoring. We have modelled different metamaterial designs in diverse setups, and have simulated their interactions with EM waves using CST Microwave Studio. Our results have shown an enhancement of penetration for the transmitted signals when the metamaterial film is placed in contact with the skin tissue. These results suggest that our design can be a significant hardware advance towards scanners for brain imaging
A Glucose Sensing System Based on Transmission Measurements at Millimetre Waves using Micro strip Patch Antennas
AbstractWe present a sensing system operating at millimetre (mm) waves in transmission mode that can measure glucose level changes based on the complex permittivity changes across the signal path. The permittivity of a sample can change significantly as the concentration of one of its substances varies: for example, blood permittivity depends on the blood glucose levels. The proposed sensing system uses two facing microstrip patch antennas operating at 60âGHz, which are placed across interrogated samples. The measured transmission coefficient depends on the permittivity change along the signal path, which can be correlated to the change in concentration of a substance. Along with theoretical estimations, we experimentally demonstrate the sensing performance of the system using controlled laboratory samples, such as water-based glucose-loaded liquid samples. We also present results of successful glucose spike detection in humans during an in-vivo Intravenous Glucose Tolerance Test (IVGTT). The system could eventually be developed into a non-invasive glucose monitor for continuous monitoring of glucose levels for people living with diabetes, as it can detect as small as 1.33âmmol/l (0.025âwt%) glucose concentrations in the controlled water-based samples satisfactorily, which is well below the typical human glucose levels of 4âmmol/l.</jats:p
Short-term Wind Power Forecasting Using Advanced Statistical Methods
Disponible sur : http://anemos.cma.fr/download/publications/pub_2006_paper_EWEC06_WP3statistical.pdfInternational audienceThis paper describes some of the statistical methods considered in the ANEMOS project for short-termforecasting of wind power. The total procedure typically involves various steps, and all these steps are described in the paper. These steps include downscaling from reference MET forecasts to the actual wind farm, wind farm power curve models, dynamical models for prediction of wind power or wind speed, estimating the uncertainty of the wind power forecast, and finally, methods for upscaling are considered. The upscaling part considers how a total regional production can be estimated using a small number of reference wind farms. Keywords: Forecasting, power curve, wind farmpower curve, upscaling, uncertainty estimation, probabilistic forecasts, adaptation
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