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- ItemLas Pailas geothermal field - Central America case study: Deciphering a volcanic geothermal play type through the combination of optimized geophysical exploration methods and classic geological conceptual models of volcano-tectonic systems(London [u.a.] : Institute of Physics, 2019) Salguero, Leonardo SolÃs; Rioseco, Ernesto MenesesSustainable exploitation strategies of high-enthalpy geothermal reservoirs in a volcanic geothermal play type require an accurate understanding of key geological structures such as faults, cap rock and caldera boundaries. Of same importance is the recognition of possible magmatic body intrusions and their morphology, whether they are tabular like dikes, layered like sills or domes. The relative value of those magmatic bodies, their age, shape and location rely on the role they play as possible local heat sources, hydraulic barriers between reservoir compartments, and their far-reaching effect on the geochemistry and dynamics of fluids. Obtaining detailed knowledge and a more complete understanding at the early stages of exploration through integrated geological, geophysical and geochemical methods is essential to determine promising geothermal drilling targets for optimized production/re-injection schemes and for the development of adequate exploitation programs. Valuable, extensive geophysical data gathered at Las Pailas high-enthalpy geothermal field at northwestern Costa Rica combined with detailed understanding of the geological structures in the underground may represent a sound basis for an in-depth geoscientific discussion on this topic. Currently, the German cooperation for the identification of geothermal resources in Central America, implemented by the Federal Institute for Geosciences and Natural Resources (BGR), supports an international and interdisciplinary effort, driven by the Instituto Costarricense de Electricidad (ICE) with different international and national research institutions, including the Leibniz Institute for Applied Geophysics (LIAG). The discussions and joint studies refer to the optimized utilization of geophysical and geological methods for geothermal exploration in the Central American region, using the example of Las Pailas Geothermal Field. The results should contribute to a better understanding of the most appropriate geothermal exploration concepts for complex volcanic field settings in Central America.
- ItemInfluence of microwave plasma treatment on the surface properties of carbon fibers and their adhesion in a polypropylene matrix(London [u.a.] : Institute of Physics, 2016) Scheffler, C.; Wölfel, E.; Förster, T.; Poitzsch, C.; Kotte, L.; Mäder, G.; Madsen, Bo; Biel, A.; Kusano, Y.; Lilholt, H.; Mikkelsen, L.P.; Mishnaevsky Jr., L.; Sørensen, B.F.A commercially available carbon fiber (CF) with an epoxy-based sizing (EP-sized CF) and an unsized CF have been plasma treated to study the effect on the fiber-matrix adhesion towards a polypropylene matrix. The EP-sized fiber was chosen because of its predictable low adhesion in a polypropylene (PP) matrix. The fibers have been modified using a microwave low-pressure O2/CO2/N2-gas plasma source (Cyrannus®) developed at IWS in a batch process. One aim of this study was the evaluation of parameters using high energies and short time periods in the plasma chamber to see the effect on mechanical performance of CF. These results will be the fundamental work for a planned continuous plasma modification line. The CF surface was characterized by determining the surface energies, single fiber tensile strength and XPS analysis. The adhesion behavior before and after plasma treatment was studied by single fiber pull-out test (SFPO) and scanning electron microscopy (SEM). It was shown that the CO2- and O2-plasma increases the number of functional groups on the fiber surface during short time plasma treatment of 30 s. Carboxylic groups on the unsized CF surface resulting from O2-plasma treatment lead to an enhanced fiber-matrix adhesion, whereas the fiber strength was merely reduced.
- ItemRaman imaging to study structural and chemical features of the dentin enamel junction(London [u.a.] : Institute of Physics, 2015) Alebrahim, M.A.; Krafft, C.; Popp, J.; El-Khateeb, Mohammad Y.The structure and chemical features of the human dentin enamel junction (DEJ) were characterized using Raman spectroscopic imaging. Slices were prepared from 10 German, and 10 Turkish teeth. Raman images were collected at 785 nm excitation and the average Raman spectra were calculated for analysis. Univariate and multivariate spectral analysis were applied for investigation. Raman images were obtained based on the intensity ratios of CH at 1450 cm-1 (matrix) to phosphate at 960 cm-1 (mineral), and carbonate to phosphate (1070/960) ratios. Different algorithms (HCA, K-means cluster and VCA) also used to study the DEJ. The obtained results showed that the width of DEJ is about 5 pm related to univariate method while it varies from 6 to 12 μm based on multivariate spectral technique. Both spectral analyses showed increasing in carbonate content inside the DEJ compared to the dentin, and the amide I (collagen) peak in dentin spectra is higher than DEJ spectra peak.
- ItemPromoting access to and use of seismic data in a large scientific community(Les Ulis : EDP Sciences, 2017) Michel, Eric; Belkacem, Kevin; Samadi, Reza; de Assis Peralta, Raphael; Renié, Christian; Abed, Mahfoudh; Lin, Guangyuan; Christensen-Dalsgaard, Jørgen; Houdek, Günter; Handberg, Rasmus; Gizon, Laurent; Burston, Raymond; Nagashima, Kaori; Pallé, Pere; Poretti, Ennio; Rainer, Monica; Mistò, Angelo; Panzera, Maria Rosa; Roth, Markus; Monteiro, Mário J. P. F. G.; Cunha, Margarida S.; Ferreira, João Miguel T. S.The growing amount of seismic data available from space missions (SOHO, CoRoT, Kepler, SDO,…) but also from ground-based facilities (GONG, BiSON, ground-based large programmes…), stellar modelling and numerical simulations, creates new scientific perspectives such as characterizing stellar populations in our Galaxy or planetary systems by providing model-independent global properties of stars such as mass, radius, and surface gravity within several percent accuracy, as well as constraints on the age. These applications address a broad scientific community beyond the solar and stellar one and require combining indices elaborated with data from different databases (e.g. seismic archives and ground-based spectroscopic surveys). It is thus a basic requirement to develop a simple and effcient access to these various data resources and dedicated tools. In the framework of the European project SpaceInn (FP7), several data sources have been developed or upgraded. The Seismic Plus Portal has been developed, where synthetic descriptions of the most relevant existing data sources can be found, as well as tools allowing to localize existing data for given objects or period and helping the data query. This project has been developed within the Virtual Observatory (VO) framework. In this paper, we give a review of the various facilities and tools developed within this programme. The SpaceInn project (Exploitation of Space Data for Innovative Helio- and Asteroseismology) has been initiated by the European Helio- and Asteroseismology Network (HELAS).
- ItemConversion of carbon dioxide into storable solar fuels using solar energy(London [u.a.] : Institute of Physics, 2019) Ennaceri, Houda; Abel, BerndNowadays, there are two main energy and environmental concerns, the first is the risk of running out of fossil fuels in the next few decades, and the second is the alarming increase in the carbon dioxide concentrations in the atmosphere, causing global warming and rise of see levels. Therefore, solar-driven technologies represent a substantial solution to fossil fuels dependence, global warming and climate change. Unlike most scientific research, which aim to use solar energy to generate electricity, solar energy can also be harnessed by recycling the carbon dioxide in the atmosphere through high-tech artificial photosynthesis with the objective of producing storable and liquid solar fuels from CO2 and water. There are two types of solar fuels, the first being hydrogen, which can be produced by mean of water splitting processes. The combustion of hydrogen generates water, which is a completely clean option for the environment. The second type of solar fuels consists of carbon-based fuels, such as methane (CH4), carbon monoxide (CO), or alcohols such as methanol (CH3OH) and ethanol (C2H5OH). The production to liquid solar fuels liquid fuels is of great interest, since they can be used in the current industrial infrastructures such as the automobiles' sector, without substantial changes in the vehicles' internal combustion engines. Therefore, guaranteeing a smooth transition from fossil fuel energy to renewable energy without radical economic consequences. Also, and most importantly, when these solar fuels are burned, they will only release the exact amount of CO2 which was initially used, which represents an optimal process for sustainable transport.
- ItemMagnetic field dynamos and magnetically triggered flow instabilities(London [u.a.] : Institute of Physics, 2017) Stefani, F.; Albrecht, T.; Arlt, R.; Christen, M.; Gailitis, A.; Gellert, M.; Giesecke, A.; Goepfert, O.; Herault, J.; Kirillov, O.N.; Mamatsashvili, G.; Priede, J.; Rüdiger, G.; Seilmayer, M.; Tilgner, A.; Vogt, T.; Gerbeth, Gunther; Stieglitz, RobertThe project A2 of the LIMTECH Alliance aimed at a better understanding of those magnetohydrodynamic instabilities that are relevant for the generation and the action of cosmic magnetic fields. These comprise the hydromagnetic dynamo effect and various magnetically triggered flow instabilities, such as the magnetorotational instability and the Tayler instability. The project was intended to support the experimental capabilities to become available in the framework of the DREsden Sodium facility for DYNamo and thermohydraulic studies (DRESDYN). An associated starting grant was focused on the dimensioning of a liquid metal experiment on the newly found magnetic destabilization of rotating flows with positive shear. In this survey paper, the main results of these two projects are summarized.
- ItemSurface, interphase and tensile properties of unsized, sized and heat treated basalt fibres(London [u.a.] : Institute of Physics, 2016) Förster, T.; Sommer, G.S.; Mäder, E.; Scheffler, C.Recycling of fibre reinforced polymers is in the focus of several investigations. Chemical and thermal treatments of composites are the common ways to separate the reinforcing fibres from the polymer matrices. However, most sizings on glass and basalt fibre are not designed to resist high temperatures. Hence, a heat treatment might also lead to a sizing removal, a decrease of mechanical performance and deterioration in fibre-matrix adhesion. Different basalt fibres were investigated using surface analysis methods as well as single fibre tensile tests and single fibre pull-out tests in order to reveal the possible causes of these issues. Heat treatment in air reduced the fibre tensile strength in the same level like heat treatment in nitrogen atmosphere, but it influenced the wetting capability. Re-sizing by a coupling agent slightly increased the adhesion strength and reflected a decreased post-debonding friction.
- ItemAn automatic aerosol classification for earlinet: Application and results(Les Ulis : EDP Sciences, 2018) Papagiannopoulos, Nikolaos; Mona, Lucia; Amiridis, Vassilis; Binietoglou, Ioannis; D’Amico, Giuseppe; Guma-Claramunt, P.; Schwarz, Anja; Alados-Arboledas, Lucas; Amodeo, Aldo; Apituley, Arnoud; Baars, Holger; Bortoli, Daniele; Comeron, Adolfo; Guerrero-Rascado, Juan Luis; Kokkalis, Panos; Nicolae, Doina; Papayannis, Alex; Pappalardo, Gelsomina; Wandinger, Ulla; Wiegner, Matthias; Nicolae, D.; Makoto, A.; Vassilis, A.; Balis, D.; Behrendt, A.; Comeron, A.; Gibert, F.; Landulfo, E.; McCormick, M.P.; Senff, C.; Veselovskii, I.; Wandinger, U.Aerosol typing is essential for understanding the impact of the different aerosol sources on climate, weather system and air quality. An aerosol classification method for EARLINET (European Aerosol Research Lidar Network) measurements is introduced which makes use the Mahalanobis distance classifier. The performance of the automatic classification is tested against manually classified EARLINET data. Results of the application of the method to an extensive aerosol dataset will be presented.
- ItemPollyNET - an emerging network of automated raman-polarizarion lidars for continuous aerosolprofiling(Les Ulis : EDP Sciences, 2018) Baars, Holger; Althausen, Dietrich; Engelmann, Ronny; Heese, Birgit; Ansmann, Albert; Wandinger, Ulla; Hofer, Julian; Skupin, Annett; Komppula, Mika; Giannakaki, Eleni; Filioglou, Maria; Bortoli, Daniele; Silva, Ana Maria; Pereira, Sergio; Stachlewska, Iwona S.; Kumala, Wojciech; Szczepanik, Dominika; Amiridis, Vassilis; Marinou, Eleni; Kottas, Michail; Mattis, Ina; Müller, Gerhard; Nicolae, D.; Makoto, A.; Vassilis, A.; Balis, D.; Behrendt, A.; Comeron, A.; Gibert, F.; Landulfo, E.; McCormick, M.P.; Senff, C.; Veselovskii, I.; Wandinger, U.PollyNET is a network of portable, automated, and continuously measuring Ramanpolarization lidars of type Polly operated by several institutes worldwide. The data from permanent and temporary measurements sites are automatically processed in terms of optical aerosol profiles and displayed in near-real time at polly.tropos.de. According to current schedules, the network will grow by 3-4 systems during the upcoming 2-3 years and will then comprise 11 permanent stations and 2 mobile platforms.
- ItemEarlinet single calculus chain: New products overview(Les Ulis : EDP Sciences, 2018) D’Amico, Giuseppe; Mattis, Ina; Binietoglou, Ioannis; Baars, Holger; Mona, Lucia; Amato, Francesco; Kokkalis, Panos; RodrÃguez-Gómez, Alejandro; Soupiona, Ourania; Kalliopi-Artemis, Voudouri; Nicolae, D.; Makoto, A.; Vassilis, A.; Balis, D.; Behrendt, A.; Comeron, A.; Gibert, F.; Landulfo, E.; McCormick, M.P.; Senff, C.; Veselovskii, I.; Wandinger, U.The Single Calculus Chain (SCC) is an automatic and flexible tool to analyze raw lidar data using EARLINET quality assured retrieval algorithms. It has been already demonstrated the SCC can retrieve reliable aerosol backscatter and extinction coefficient profiles for different lidar systems. In this paper we provide an overview of new SCC products like particle linear depolarization ratio, cloud masking, aerosol layering allowing relevant improvements in the atmospheric aerosol characterization.