21. Bora wind, Wind speed vertical profile, Logarithmic law, Power lawMarija Bervida, Samo Stanič, Klemen Bergant, 2018, published scientific conference contribution Abstract: Bora is cold and gusty downslope wind with variable gust frequency and duration, appearing on the lee side of Dinaric Alps. Its flow characteristics are unique and theoretically still not fully described, especially for modeling purposes. We present an analysis of the wind speed vertical profiles at Razdrto, which lies in a gap between the Nanos and Javorniki plateau in southwest Slovenia and is strongly exposed to Bora. An analysis of the vertical wind speed profiles during Bora episodes is based on experimental wind data, provided by Helikopter energija, for six Bora events of different duration, appearing between April 2010 and May 2011. Average wind speed in 10-minute intervals was collected at four different heights (20, 31, 40 and 41.7 m above the ground)at the wind turbine site in Razdrto using cup anemometers. Wind direction data with same temporal resolution was obtained from a single wind vane placed at 40.9 m above the ground. Based on the collected data, the applicability of the empirical power-law and the logarithmic law profiles, commonly used for the description of neutrally stratified atmosphere, was investigated for the case of Bora. The parameters for the power-law and logarithmic law were obtained by fitting the wind speed data using linear regression method and are compared to standard values for that particular type of terrain. The quality of fits was very good with r2 above 0.9, indicating that both power-law and logarithmic law adequately describe mean horizontal Bora wind. The median value of the power-law coefficient was found to be 0.16±0.03, which is consistent with standard value for neutral atmosphere (0.143). The aerodynamic roughness varied from 0.003 m to 0.22 m with the median value of 0.09±0.07, which describes open level country terrain with some trees. The event in November 2010 with large roughness is expected to be due to specific wind direction and surface conditions.
Keywords: Bora wind, Wind speed vertical profile, Logarithmic law, Power law
Published in RUNG: 07.02.2019; Views: 4010; Downloads: 27
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22. Retrieval of Vertical Mass Concentration Distributions—Vipava Valley Case StudyLonglong Wang, Samo Stanič, Klemen Bergant, William Eichinger, Griša Močnik, Luka Drinovec, Janja Vaupotič, Miloš Miler, Mateja Gosar, Asta Gregorič, 2019, original scientific article Abstract: Aerosol vertical profiles are valuable inputs for the evaluation of aerosol transport models, in order to improve the understanding of aerosol pollution ventilation processes which drive the dispersion of pollutants in mountainous regions. With the aim of providing high-accuracy vertical distributions of particle mass concentration for the study of aerosol dispersion in small-scale valleys, vertical profiles of aerosol mass concentration for aerosols from different sources (including Saharan dust and local biomass burning events) were investigated over the Vipava valley, Slovenia, a representative hot-spot for complex mixtures of different aerosol types of both anthropogenic and natural origin. The analysis was based on datasets taken between 1–30 April 2016. In-situ measurements of aerosol size, absorption, and mass concentration were combined with lidar remote sensing, where vertical profiles of aerosol concentration were retrieved. Aerosol samples were characterized by SEM-EDX, to obtain aerosol morphology and chemical composition. Two cases with expected dominant presence of different specific aerosol types (mineral dust and biomass-burning aerosols) show significantly different aerosol properties and distributions within the valley. In the mineral dust case, we observed a decrease of the elevated aerosol layer height and subsequent spreading of mineral dust within the valley, while in the biomass-burning case we observed the lifting of aerosols above the planetary boundary layer (PBL). All uncertainties of size and assumed optical properties, combined, amount to the total uncertainty of aerosol mass concentrations below 30% within the valley. We have also identified the most indicative in-situ parameters for identification of aerosol type.
Keywords: valley air pollution, aerosol vertical distributions, lidar remote sensing, in-situ measurements, aerosol identification
Published in RUNG: 09.01.2019; Views: 4211; Downloads: 113
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23. Aerosol monitoring over Vipava valley using Raman polarization lidarLonglong Wang, Samo Stanič, Klemen Bergant, William Eichinger, Asta Gregorič, Griša Močnik, Luka Drinovec, 2018, published scientific conference contribution abstract Abstract: Vipava valley in southwest Slovenia is a representative hot-spot for complex mixtures of different aerosol types of both anthropogenic and natural origin in mountainous terrain. An investigation of aerosol properties throughout the troposphere in different atmospheric conditions was made possible by a deployment of a two-wavelength polarization Raman lidar system combining with in-situ measurements in the valley (in the town of Ajdovščina) from September 2017. Using its aerosol identification capabilities, which are based on particle depolarization ratio and lidar ratio measurements, it was possible to identify predominant aerosol types in the observed atmospheric structures, for example in different atmospheric layers in the case of stratified atmosphere. Primary anthropogenic aerosols within the valley were found to be mainly emitted from two sources: individual domestic heating systems, which mostly use biomass fuel, and from traffic. A considerable fraction of natural aerosols (for example mineral dust and sea salt), transported over large distances, were observed both above and entering into the planetary boundary layer. According to the properties of different aerosol types, backscatter contribution of each aerosol type was evaluated and the corresponding extinction contribution was derived from lidar observations. Statistical analysis of the presence of different aerosol types was performed on the entire available dataset from 2017 and 2018.
Keywords: lidar, aerosol type, Vipava valley
Published in RUNG: 03.12.2018; Views: 4297; Downloads: 0
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24. Sulfur based batteries studied by in-operando S K-edge RIXS and XAS spectroscopyMatjaž Kavčič, Ana Robba, Janez Bitenc, Alen Vižintin, Iztok Arčon, Matjaž Žitnik, Klemen Bučar, Robert Dominko, 2018, published scientific conference contribution abstract Abstract: Sulfur based batteries are considered as very attractive energy storage devices. Sulfur is one of the most abundant elements in the earth, it is electrochemically active material which can accept up to two electrons per atom. In combination with alkali metals, sulfur forms electrochemical couples with much higher theoretical energy density compared to Li-ion batteries commonly available today. At the moment, the electrochemical couple with Li is most extensively studied. While the main principle of operation is known the relevant operation mechanism(s) is not completely clear. Even more promising is the electrochemical couple with Mg providing almost twofold higher volumetric energy density due to its ability to provide two electrons during oxidation. However, Mg-S batteries are still in the very early stage of research and development and the complex mechanism of sulfur conversion has been less extensively studied.
In order to improve the understanding of sulfur electrochemical conversion and its interactions within electrode, we need to apply new experimental approaches capable to provide precise information about local environment of S in the cathode during battery operation. In our work, resonant inelastic X-ray scattering (RIXS) and XAS measurements at the sulfur K-edge performed in operando mode were used to study the lithium-polysulfide formation during the discharge process. Measurements were performed at ID26 beamline of the ESRF synchrotron using tender X-ray emission spectrometer [1]. Resonant excitation condition enhanced the sensitivity for the lithium−polysulfide detection. On the other hand, the sulfate signal from the electrolyte was heavily suppressed and the self-absorption effects minimized due to fixed excitation energy.
This experimental methodology was used to provide quantitative analysis of sulfur compounds in the cathode of a Li−S battery cell during the discharge process [2]. The high-voltage plateau in the discharge curve was characterized by a rapid conversion of solid sulfur into liquid phase Li polysulfides reaching its maximum at the end of this plateau. At this point the starting point for the precipitation of the Li2S from the liquid polysulfide phase was observed. The same approach has been used also for the Mg-S battery revealing similar mechanism as in case of Li-S battery [3]. The electrochemical conversion of sulfur with magnesium proceeds through two well-defined plateaus, which correspond to the equilibrium between sulfur and Mg polysulfides (high-voltage plateau) and polysulfides and MgS (low-voltage plateau).
Keywords: Mg-Sulphur batteries, XANES, RIXS
Published in RUNG: 13.09.2018; Views: 4481; Downloads: 0
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25. Fluorinated ether based electrolyte for high-energy lithium-sulfur batteries : Li [sup] + solvation role behind reduced polysulfide solubilitySara Drvarič Talian, Steffen Jeschke, Alen Vižintin, Klemen Pirnat, Iztok Arčon, Giuliana Aquilanti, Patrik Johansson, Robert Dominko, 2018, published scientific conference contribution abstract Keywords: Li-žveplive baterije, XANES, polisulfidi
Published in RUNG: 12.09.2018; Views: 3215; Downloads: 0
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26. Cadmium associates with oxalate in calcium oxalate crystals and competes with calcium for translocation to stems in the cadmium bioindicator Gomphrena clausseniiPaula Pongrac, Tania Serra, Hiram Castillo Michel, Katarina Vogel-Mikuš, Iztok Arčon, Mitja Klemen, Boštjan Jencic, Anja Kavčič, Mina T. Villafort Carvalho, Mark G. M. Aarts, 2018, original scientific article Abstract: Cadmium (Cd) was shown to co-localise with calcium (Ca) in oxalate crystals in the stems and leaves of
Cd tolerant Gomphrena claussenii, but Cd binding remained unresolved. Using synchrotron radiation
X-ray absorption near edge spectroscopy we demonstrate that in oxalate crystals of hydroponically
grown G. claussenii the vast majority of Cd is bound to oxygen ligands in oxalate crystals (488%;
Cd–O–C coordination) and the remaining Cd is bound to sulphur ligands (Cd–S–C coordination). Cadmium
binding to oxalate does not depend on the amount of Ca supplied or from which organs the crystals
originate (stems and mature leaves). By contrast, roots contain no oxalate crystals and therein Cd is
bound predominantly by S ligands. The potential to remove Cd by extraction of Cd-rich oxalate crystals
from plant material should be tested in phytoextraction or phytomining strategies.
Keywords: Cd XANES, Cd oxalate, Gomphrena claussenii
Published in RUNG: 06.09.2018; Views: 3319; Downloads: 0
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27. Vertical profiling of aerosol properties with two-wavelength polarization Raman lidar over the Vipava valleyLonglong Wang, Samo Stamoč, Asta Gregorič, Griša Močnik, Luka Drinovec, Klemen Bergant, William Eichinger, 2018, published scientific conference contribution abstract Abstract: Presence of atmospheric aerosols affects the Earth’s radiation budget and thus also atmospheric thermal structure,
which in turn affects cloud and planetary boundary layer (PBL) dynamics. We combine in-situ and remote
measurements to determine aerosol properties in a representative hot-spot for air pollution in a complex terrain
configuration. Vertical profiles of aerosol properties were investigated using a two-wavelength polarization
Raman lidar system in the Vipava valley. Using lidar-obtained particle depolarization ratio, lidar ratio and
backscatter Ångström exponent (355 nm / 1064 nm), which depend on aerosol shape, size and refractive index,
thus the aerosols can be identified and the roles of different aerosol types in the observed atmospheric processes
were investigated. In addition, aerosol absorption coefficients were measured in-situ by Aethalometers (AE33,
Magee Scientific / Aerosol d.o.o.) on the valley floor and on the adjacent mountain range, 850 m above the lidar site.
Our primary goal was to study the variability of aerosol types within and above the Vipava valley, which
was performed using the entire lidar dataset from August – December 2017. Primary anthropogenic aerosols
within the valley is mainly emitted from two sources: individual domestic heating systems, which mostly use
biomass fuel and traffic. Natural aerosols, transported by long-range transport, such as mineral dust and sea salt,
were observed both above the PBL and entering into the PBL. Vertical distributions of aerosol properties, in par-
ticular the particle depolarization ratio, indicated atmospheric stratification with different aerosol types occupying
different height ranges. In the presence of Bora (strong down-slope wind), Kelvin-Helmholtz instabilities were
observed between the PBL and the free troposphere. Using aerosol type identification capability of our system,
we discovered that this instability was responsible for ejecting aerosols from the PBL up to 2 km into the free
troposphere.
In addition, we improved the reliability of aerosol identification in vertical profiles using absorption coeffi-
cient measured by Aethalometer. Combining it with the aerosol extinction coefficient at 355 nm derived from
lidar data, we derived aerosol single scattering albedo (SSA), which is an important parameter for aerosol
characterization.
Keywords: Aerosol, Vipava valley, lidar
Published in RUNG: 23.04.2018; Views: 4348; Downloads: 0
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28. EIQAS, Enhancing Internal Quality Assurance Systems, Training Event 1, Publication on European Standards and Guidelines for Quality Assurance (Part 1 ESG) and Internal Quality Assurance (IQA) : Erasmus+ Project 2014-20162016, treatise, preliminary study, study Keywords: higher education, internal quality assurance, European Higher Education Area, standards and guidelines for quality assurance, university
Published in RUNG: 13.02.2018; Views: 4542; Downloads: 0
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29. THE INCIDENCE OF NEW ECOSYSTEMS (EE – EMERGING ECOSYSTEMS) IN THE KARST BIOSPHERE RESERVE : GROUP PROJECT, FINAL REPORTKlemen Cotič, Matej Pogorelc, Matjaž Reya, Barbara Šavli, Nika Feigina, Merisa Kapić, Ӧzkan Karaçam, Mariya Perepelytsya, 2017, other monographs and other completed works Abstract: The need of wood for building and heating, the extensive grazing and population growth in the 18th and 19th centuries led to turning the Karst area in Slovenia into a bare land. In the 19th century organised reforestation started which was successfully performed with Black pine (Pinus nigra J. F. Arnold). Later on, the reforestation was replaced by the process of spontaneous afforestation. The successfulness of reforestation with Black pine also made it possible for the native tree species to grow. The abandoning of the use of agricultural land also contributes to the spontaneous afforestation. In this project we determined the changes in forest cover through time. We used aerial photographs from the years 1957, 1975, 1985 and 2015. By drawing polygons on the maps in the QGIS programme on the areas that are covered with forests, are overgrown or are used for agricultural purpose we compared the areas from the maps of different years. We found out that the area covered with forest had increased by more than 50 % from the year 1957 to 2015. The increase in the area of forest cover due to afforestation provides new habitats for fauna and flora to live in.
Keywords: Karst, afforestation, new habitat, Black pine, human impact
Published in RUNG: 07.11.2017; Views: 5015; Downloads: 0
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30. A Mechanistic Study of Magnesium Sulfur BatteriesAna Robba, Alen Vižintin, Jan Bitenc, Gregor Mali, Iztok Arčon, Matjaž Kavčič, Matjaž Žitnik, Klemen Bučar, Giuliana Aquilanti, Charlotte Martineau-Corcos, Anna Randon-Vitanova, Robert Dominko, 2017, original scientific article Abstract: Magnesium sulfur batteries are considered as attractive energy storage devices due to the
abundance of electrochemically active materials and high theoretical energy density. Here we
report the mechanism of a Mg-S battery operation, which was studied in the presence of
simple and commercially available salts dissolved in a mixture of glymes. The electrolyte
offers high sulfur conversion into MgS in the first discharge with low polarization. The
electrochemical conversion of sulfur with magnesium proceeds through two well-defined
plateaus, which correspond to the equilibrium between sulfur and polysulfides (high-voltage
plateau) and polysulfides and MgS (low-voltage plateau). As shown by XANES, RIXS and
NMR studies, the end discharge phase involves MgS with Mg atoms in a tetrahedral
environment resembling the wurtzite structure, while chemically synthesized MgS crystalizes
in the rock-salt structure with octahedral coordination of magnesium.
Keywords: magnesium, sulfur, rechargeable batteries, XAS, NMR
Published in RUNG: 19.10.2017; Views: 4422; Downloads: 0
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