Electromagnetic interference shielding and radiation absorption in thin polypyrrole films

Results of permittivity measurements, electromagnetic interference shielding effectiveness, and heat generation due to microwave absorption in conducting polymer coated textiles are reported and discussed. The intrinsically conducting polymer, polypyrrole, doped with anthraquinone-2-sulfonic acid (AQSA) or para-toluene-2-sulfonic acid (pTSA) was applied on textile substrates and the resulting materials were investigated in the frequency range 1&ndash;18 GHz. The 0.54 mm thick conducting textile/polypyrrole composites absorbed up to 49.5% of the incident 30&ndash;35 W microwave radiation. A thermography station was used to monitor the temperature of these composites during the irradiation process, where absorption was confirmed via visible heat losses. Samples with lower conductivity showed larger temperature increases caused by microwave absorption compared to samples with higher conductivity. A sample with an average sheet resistivity of 150 &Omega;/sq. showed a maximum temperature increase of 5.27 &deg;C, whilst a sample with a lower resistivity (105 &Omega;/sq.) rose by 3.85 &deg;C.<br /

Parametrization of relative humidity- and wavelength-dependent optical properties of mixed Saharan dust and marine aerosol

Aerosol particles interact with sunlight through scattering and absorption and have therefore a direct radiative effect. Hygroscopic aerosol particles take up water and are able to grow in size below 100% relative humidity, which involves the change of optical properties and the direct radiative effect. The change of aerosol optical properties for aerosol mixtures under humidification is presently not well understood, especially for the largest particle sources worldwide. The present PhD-thesis quantifies wavelength- and humidity-dependent aerosol optical properties for a mixture of Saharan mineral dust and marine aerosol. For quantification, an aerosol model was developed, which based on in-situ measurements of microphysical and optical properties at Cape Verde. With this model, aerosol optical properties were calculated from the dry state up to 90% relative humidity. To validate the model, a measure of the total extenuated light from particles under ambient conditions was used. Finally, the humidity dependence of aerosol optical properties for marine aerosol, Saharan dust aerosol, and a mixture of both species was described by two empirical equations. With the wavelength of the incident visible solar radiation, relative humidity, and dry dust volume fraction, the humidity dependence of optical properties can be calculated from tabulated values. To calculate radiative effects, aerosol optical properties were used as input parameters for global circulation models including radiative transfer. Due to the complexity of aerosol related processes, they have been treated implicitly, meaning in parameterized form. For modelling purposes, the present PhD-thesis provides a solution to include humidity effects of aerosol optical properties.Aerosolpartikel wechselwirken durch Streu- und Absorptionsprozesse mit der einfallenden Sonnenstrahlung und haben somit einen direkten Strahlungseffekt. Bei relativen Feuchten bis 100% können Aerosolpartikel aufquellen und somit ihre Größe ändern. Im Zuge des Aufquellens, ändern sich die optischen Eigenschaften und somit auch der direkte Strahlungseffekt der Aerosolpartikel. Speziell für Mischungen von verschiedenen Aerosolspezies ist die Änderung der optischen Eigenschaften des Aerosols durch Feuchte Einfuss noch nicht ausreichend verstanden. Gegenstand der vorliegenden Arbeit ist daher die Quantifizierung der wellenlängen- und feuchteabhängigen optischen Eigenschaften einer Mischung von Saharastaub- und marinen Aerosol. Die zur Quantifizierung notwendigen Daten wurden im Rahmen einer Feldmessung von mikrophysikalischen- und optischen Aerosol-Eigenschaften auf den Kapverdischen Inseln gesammelt. Auf Grundlage dieser Messungen wurde ein Aerosol-Modell entwickelt. Dieses Modell wurde daraufhin verwendet, um Berechnungen von optischen Aerosol-Eigenschaften bei relativen Feuchten bis 90% durchzuführen. Eine Messung der Lichtschwächung durch Aerosolpartikel unter Umgebungsbedingungen wurde verwandt, um das Modell bei Umgebungsfeuchten zu validieren. Die Wellenlängen- und Feuchteabhängigkeit der optischen Eigenschaften des Aerosols wurde parametrisiert und konnte anhand von zwei Parametergleichungen bestimmt werden. Unter Benutzung von tabellierten Werten und der Wellenlänge des einfallenden sichtbaren Sonnenlichtes, der relativen Feuchte, sowie der Staubvolumenfraktion, kann die Feuchteabhängigkeit von wichtigen Aerosol-optischen Eigenschaften für Saharastaub, marinen Aerosol und einer Mischung aus beiden Komponenten bestimmt werden. Globale Zirkulationsmodelle, die auch eine Berechnung von Strahlungseffekten durch Aerosolpartikel beinhalten, nutzen Aerosol-optische Eigenschaften als Eingabeparameter. Durch zunehmende Komplexitiät zur Beschreibung von Wechselwirkungen in der Atmosphäre, sind einfache Parametrisierungen unabdingbar. Die vorliegende Arbeit liefert daher einen wichtigen Beitrag für die Modellierung von Strahlungseffekten durch Aerosolpartikel und somit zum Verständnis des Strahlungshaushaltes der Erde

Noninvasive Solution for Electrochemical Impedance Spectroscopy on Metallic Works of Art

Metallic works of art of cultural relevance are continuously subjected to corrosion as the environment becomes increasingly polluted. A fast and simple method to in situ assess the conservation conditions is therefore required. This paper describes the development and performance of dry and gel-based electrodes which can be used to assess the surface conservation state without the need to move the artifacts and which do not cause any damage to them. The electrodes can be used with a portable electrochemical impedance spectroscopy system, without employing electrochemical cells. The proposed solution does not provide all the information that one can obtain using an electrochemical cell, but it can discriminate between protective coatings. It can be used to assess the protective capability of corrosion product layers and natural patinas, and it can therefore enable a noninvasive routine surface assessment to be conducted that could be extremely useful for people working in the field of conservation of cultural heritag

Caractérisation de films d'huile de la bande X à la bande K, expérimentation en bassin à vagues

This paper depicts an experiment conducted in a wind-wave pool in Brest, France, to characterize oil films when observed at moderate incidence from a X-to-K-band radar. Simultaneous measurements of surface elevation and radar backscattered field were carried out for various sea water surface states and incident angles. From this meaningful dataset (mainly lying in simultaneous acquisitions in X-, Ku-and K-band), an inversion method is proposed to characterize some properties of the oil film: its origin (mineral or biogenic) and its fractional coverage indicator. This process is based on the minimization of the cost function correlating the values given by a physical model of the wave damping ratio and the measured ones. The resulting oil parameters are found in overall good agreement with the three different released oils (two mineral and one biogenic) and it is observed that the fractional filling indicator of the oil slick decreases with increasing the roughness surface state whatever the considered oil.Ce papier décrit une expérimentation menée dans un bassin à vagues à Brest, France. L'objectif est de caractériser les films d'huile observés au moyen d'un système radar à des angles d'incidence modérée de la bande X à la bande K. Des mesures simultanées de l'élévation de la surface et du champ électromagnétique rétro-diffusé furent réalisées pour différents états de surface et divers angles d'incidence. A partir de cette base de données, une méthode d'inversion est proposée pour caractériser plusieurs propriétés du film d'huile: son origine (minérale ou biogénique) ainsi que sa fraction de couverture surfacique. Ce processus repose sur la minimisation d'une fonction coût liant la modélisation physique du coefficient d'atténuation des vagues avec la mesure. Les paramètres estimés sont en accord avec les trois huiles différentes déversées (deux minérales et une biogénique). Il est également observé que la fraction de couverture surfacique de la nappe d'huile décroît avec l'augmentation de la rugosité de surface et ce, quelle que soit l'huile considérée

Maritime environmental security

This article analyzes environmental security in the sphere of sea navigation, safety of navigation and tourism on the Adriatic Sea, bearing in mind that keeping marine environment healthy is one of fundamental factors of today’s national and international security. Likewise, secure underwater environment strengthens public security from hazards deriving from seafloor caused by human negligence and environmental degradation – by disposing and submerging dangerous goods in particular. The article focuses on the underwater environment mapping by using bathymetric charts where “dangerous underwater objects” would be recorded. Furthermore, it concentrates on the latest underwater technology (Autonomous Underwater Vehicles) able to detect and digitally record the object’s position, georeferencing it in coordinates. At the same time, the article aims at raising the awareness of marine environment protection and conservation, as well as the realization of the UN Environment Program

A Computational Tool for Evaluating THz Imaging Performance in Brownout Conditions at Land Sites throughout the World

This study quantifies terahertz (THz) or sub-millimeter imaging performance during simulated rotary-wing brownout or whiteout environments based on geographic location and recent/current atmospheric weather conditions. The atmospheric conditions are defined through the Air Force Institute of Technology Center for Directed Energy (AFIT/CDE) Laser Environmental Effects Definition and Reference or LEEDR model. This model enables the creation of vertical profiles of temperature, pressure, water vapor content, optical turbulence, and atmospheric particulates and hydrometeors as they relate to line-by-line layer extinction coefficient magnitude at wavelengths from the UV to the RF. Optical properties and realistic particle size distributions for the brownout and whiteout particulates have been developed for and incorporated into LEEDR for this study. The expected imaging performance is assessed primarily at a wavelength of 454 μm (0.66 THz) in brownout conditions at selected geographically diverse land sites throughout the world. Seasonal and boundary layer variations (summer and winter) and time of day variations for a range of relative humidity percentile conditions are considered to determine optimum employment techniques to exploit or defeat the environmental conditions. Each atmospheric particulate/hydrometeor is evaluated based on its wavelength-dependent forward and off-axis scattering characteristics and absorption effects on the imaging environment. In addition to realistic vertical profiles of molecular and aerosol absorption and scattering, correlated optical turbulence profiles in probabilistic (percentile) format are used

Quantifying the Direct Radiative Effect of Absorbing Aerosols for Numerical Weather Prediction: A Case Study

We conceptualize aerosol radiative transfer processes arising from the hypothetical coupling of a global aerosol transport model and a global numerical weather prediction model by applying the US Naval Research Laboratory Navy Aerosol Analysis and Prediction System (NAAPS) and the Navy Global Environmental Model (NAVGEM) meteorological and surface reflectance fields. A unique experimental design during the 2013 NASA Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys (SEAC4RS) field mission allowed for collocated airborne sampling by the high spectral resolution Lidar (HSRL), the Airborne Multi-angle SpectroPolarimetric Imager (AirMSPI), up/down shortwave (SW) and infrared (IR) broadband radiometers, as well as NASA A-Train support from the Moderate Resolution Imaging Spectroradiometer (MODIS), to attempt direct aerosol forcing closure. The results demonstrate the sensitivity of modeled fields to aerosol radiative fluxes and heating rates, specifically in the SW, as induced in this event from transported smoke and regional urban aerosols. Limitations are identified with respect to aerosol attribution, vertical distribution, and the choice of optical and surface polarimetric properties, which are discussed within the context of their influence on numerical weather prediction output that is particularly important as the community propels forward towards inline aerosol modeling within global forecast systems

Estimation of Hydraulic Parameters from Dar-zarrouk Parameters for Aquiferous Zone Characterization in Iyesi Axis, Ota, Ogun State Nigeria

The cost of estimating hydraulic parameters from slug test, pumping test, soil sample analysis etc is expensive. However, these parameters such as transverse resistance and longitudinal conductance can be estimated from geophysical parameters which are cost effective, noninvasive and inexpensive. In this present study, twenty (20) geoelectric sounding were carried out in Iyesi- Jackross axis with the use of ABEM 1000 series terrameter using schlumberger array and AB/2 ranges from 240m to 420m. The result revealed that there are six lithological layers in the study area namely; topsoil, lateritic clay, clayey sand, kaolitic clay, clayey sand (low yield aquifer) and sand (Main aquifer). The aquifer’s depth ranges from 45.1m to 114.7 m with resistivity values ranges from 19.5 Ωm to 850.8 Ωm. Furthermore, transverse resistance and longitudinal conductance were estimated from geophysical parameters and it was observed that longitudinal conductance is low which ranges from 0.0127 Ω−1 to 0.0941 Ω −1 . Consequently, the aquiferous unit is characterized with high transmissivity and hydraulic conductivity. Transverse resistance ranges from 12246.00 Ωm2 to 124878.61 Ωm2 and increase in transverse resistance that was observed generally indicating high transmissivity and high yield of the aquiferous units. It is therefore signifies that the study area is characterized with good groundwater potential. Further study can be carried out to estimate the boundary of aquifer thickness and the possible intrusion of Basement complex using magnetic technique

Effect of Open Dumpsite on Undeground Water in Ganmo,Ifelodun LGA, Kwara State, North Central Nigeria.

This study imbibes Geophysical survey involving electrical resistivity methods (Electrical Re- sistivity Tomography and Vertical Electrical Sounding), Physico-chemical analysis and Bacte- ria Analysis of the underground water samples. Geophysical survey were conducted around a 35 years old solid waste dumpsite in Ganmo, one of the districts in Ifelodun LGA, Kwara State, North Central Nigeria, located between latitude 8�2502500 to 8�2504100N and longitude 4�3603600 to 4�3606200E, with the view to assessing the extent of impact of the waste dumpsite on the quality of the groundwater in the study area. Electrical Resistivity Pro�ling and vertical elec- trical sounding stations were established using Werner and Schlumberger con�guration with half { currents electrode spacing that ranged from 1 to 100 m. A digital read out resistivity meter was used to acquire data in the area. A contaminant leachate plume was delineated in 2-D resistivity sections as low resistivity zones. The 2-D resistivity imaging was identi�ed as bluish zones of low resistivity 20.9 m with the depth ranging from 0.25 to 3.96 m in the entire inverse model sections. The low resistivity value of 20.9 m revealed that the groundwater around the dumpsite has been contaminated to the depth of 3.19 m compare to the measured water levels. The VES results were presented in terms of resistivity, thickness and depth. The VES interpreted results delineated three subsurface layers comprising topsoil, weathered layer and the fresh basement of which the three (3) layer geo-electric sections are both H-type and A-type sounding curve. The result indicated that the 3rd layer VES has high resistivity value ranging from 650.0 to 2264.3 m whose depth and thickness could not be reached. Three (3) water samples were collected, two samples from the closest hand dug wells and one sample from bore-hole for analysis. The hydro-physicochemical analysis conducted showed that wells are in good conditions actually the concentration of various parameters tested are below the WHO and FEPA standard. The result of the bacterial analysis of the water samples collected showed presence of bacterial species load of E. coli and Klebsiella which can cause severe health hazards. It is concluded that the water is not safe for domestic consumption. However water treatment is hereby recommended on all wells around the study area

Light absorption of atmospheric soot particles over Central Europe

Soot particles are a major absorber of shortwave radiation in the atmosphere. They exert a rather uncertain direct and semi-direct radiative effect, which causes a heating or in some cases a cooling of the atmosphere. The mass absorption coefficient is an essential quantity to describe this light absorption process. This work presents new experimental data on the mass absorption coefficient of soot particles in the troposphere over Central Europe. Mass absorption coefficients were derived as the ratio between the light absorption coefficient determined by multi angle absorption photometry (MAAP), and the soot mass concentration determined by Raman spectroscopy. The Raman method is sensitive to graphitic structures present in the particle samples, and was calibrated in the laboratory using Printex90 model particles. The mass absorption coefficients were determined for a number of seven observation sites, ranging between 3.9 and 7.4 m²/g depending on measurement site and observational period. The highest values were found in an continentally aged air mass in winter, where we presumed soot particles to be present mainly in internal mixture. The regional model WRF-Chem was used in conjunction with a high resolution soot emission inventory to simulate soot mass concentrations and absorption coefficients for the Central European Troposphere. The model was validated using soot mass concentrations from Raman measurements and absorption coefficients. Simulated soot mass concentrations were found to be too low by around 50 %, which could be improved by scaling the emissions by a factor of two. In contrast, the absorption coefficient was positively biased by around 20%. Adjusting the modeled mass absorption coefficient to measurements, the simulation of soot light absorption was improved. Finally, the positive direct radiative forcing at top of the atmosphere was found to be lowered by up to 70% for the model run with adjusted soot absorption behaviour, , indicating a decreased heating effect on the atmosphere