Schizophyllum commune: The main cause of dying trees of the Banja Luka arbored walks and parks

In the frame of investigation of the main cause of dying trees of the main arbored walks (Mladena Stojanovića Aley and Park), the investigation of the presence and diversity of macrofungi in Banja Luka City were undertaken in the period 2006-2011. Relatively poor generic diversity of lignicolous (pathogenic or potentially pathogenic and saprotrophic) macrofungi with only 16 species representing this group (13 basidiomycets: Schizophyllum commune, Fomes fomentarius, Stereum hirsutum, Coriolus versicolor, Flammulina velutipes, Pseudotrametes gibbosa, Ganoderma applanatum, G. lucidum, G. adspersum, Polyporus squamosus, Meripilus giganteus, Laetiporus sulphureus, Auricu­laria auricula-judae, and 3 ascomycets: Nectria cinnabarina, Xylaria hypoxylon, X. poly­morpha) were recorded. Such a poor qualitative composition of this very important fungal group could be explained by the reduction in the number of plant species in arbored walks and alleys, as well as the reduction in the number of fungi resistant to heavy air pollution caused by nearby (1-5m) fuel combustion in engines. Although only preliminary, our results pointed to the necessity of conservation and protection of the most beautiful features of Banja Luka and its alleys and arbored walks, by undertaking the measures of curing damaged trees and treating them with fungicides in order to wipe out the epiphytia caused in more than 95% of cases (dated May 2011) by Split-gill (Schizophyllum commune), present on dead wood but also on damaged trees of Aesculus hyppocastaneum (127 trees), Tilia cordata (124 trees), Tilia platyphyllos (36 trees), Tilia argentea (40 trees), Acer negundo (20 trees), Platanus acerifolia (2 trees), Robinia pseudoacacia (3 trees), Fraxinus ornus (1 tree), Betula pendula (1 tree), Catalpa sp. (2 trees), etc. Altogether, during the last decade, around 200 trees collapsed or were sanitary cut in Banja Luka arbored walk from the Malta site to the Green bridge, a total length around 5 km. The reason for this was primarily due to Split-gill fungus and the restoration of arbored walks in the streets extremely polluted by engine fuel consumption in the zone of Mladena Stojanovića street. By analyzing the trees along the City of Banja Luka main street it could be concluded that, besides the appearance of suffocation of plants, due to wide asphalt surfaces that are located immediately next to the tree-trunks and heavy air pollution, fungi caused illnesses are the most important cause of the decline of trees. With its great adaptation to arid climate and ability to resist to the air pollution, Schizophyllum commune turned out to be the most aggressive and successful universal fungal invader of trees from old alleys, even threatening immuno­compromised human individuals. However, man and his direct or indirect impacts contrib­ute to the dying of trees much faster than the fungal pathogens in the busiest and most polluted Mladena Stojanovića street

The first multi-model ensemble of regional climate simulations at kilometer-scale resolution. Part I: Evaluation of precipitation

Here we present the first multi-model ensemble of regional climate simulations at kilometer-scale horizontal grid spacing over a decade long period. A total of 23 simulations run with a horizontal grid spacing of ∼ 3 km, driven by ERA-Interim reanalysis, and performed by 22 European research groups are analysed. Six different regional climate models (RCMs) are represented in the ensemble. The simulations are compared against available high-resolution precipitation observations and coarse resolution (∼ 12 km) RCMs with parameterized convection. The model simulations and observations are compared with respect to mean precipitation, precipitation intensity and frequency, and heavy precipitation on daily and hourly timescales in different seasons. The results show that kilometer-scale models produce a more realistic representation of precipitation than the coarse resolution RCMs. The most significant improvements are found for heavy precipitation and precipitation frequency on both daily and hourly time scales in the summer season. In general, kilometer-scale models tend to produce more intense precipitation and reduced wet-hour frequency compared to coarse resolution models. On average, the multi-model mean shows a reduction of bias from ∼ −40 at 12 km to ∼ −3 at 3 km for heavy hourly precipitation in summer. Furthermore, the uncertainty ranges i.e. the variability between the models for wet hour frequency is reduced by half with the use of kilometer-scale models. Although differences between the model simulations at the kilometer-scale and observations still exist, it is evident that these simulations are superior to the coarse-resolution RCM simulations in the representing precipitation in the present-day climate, and thus offer a promising way forward for investigations of climate and climate change at local to regional scales. © 2021, The Author(s)

The first multi-model ensemble of regional climate simulations at kilometer-scale resolution, part I: evaluation of precipitation

Here we present the first multi-model ensemble of regional climate simulations at kilometer-scale horizontal grid spacing over a decade long period. A total of 23 simulations run with a horizontal grid spacing of ∼3 km, driven by ERA-Interim reanalysis, and performed by 22 European research groups are analysed. Six different regional climate models (RCMs) are represented in the ensemble. The simulations are compared against available high-resolution precipitation observations and coarse resolution (∼ 12 km) RCMs with parameterized convection. The model simulations and observations are compared with respect to mean precipitation, precipitation intensity and frequency, and heavy precipitation on daily and hourly timescales in different seasons. The results show that kilometer-scale models produce a more realistic representation of precipitation than the coarse resolution RCMs. The most significant improvements are found for heavy precipitation and precipitation frequency on both daily and hourly time scales in the summer season. In general, kilometer-scale models tend to produce more intense precipitation and reduced wet-hour frequency compared to coarse resolution models. On average, the multi-model mean shows a reduction of bias from ∼ −40% at 12 km to ∼ −3% at 3 km for heavy hourly precipitation in summer. Furthermore, the uncertainty ranges i.e. the variability between the models for wet hour frequency is reduced by half with the use of kilometer-scale models. Although differences between the model simulations at the kilometer-scale and observations still exist, it is evident that these simulations are superior to the coarse-resolution RCM simulations in the representing precipitation in the present-day climate, and thus offer a promising way forward for investigations of climate and climate change at local to regional scales

Internal arc testing of medium voltage switchgear

Text in Russia

Internal arcing : issues related to testing and standardization

Internal arc tests are intended to verify the effectiveness of switchgear design in protecting personnel in case of an internal arc. With the IEC 62271-200 & 201 in 2003, new methods and criteria for testing metal / insulation enclosed switchgear under conditions of an internal arc have been formulated. KEMA's experiences with the new standards will be highlighted, including statistics on the failure rates (approx. 20%), differentiated to the various acceptance criteria. A comparison with experiences related to the prior standard (IEC 60298) will be presented. Various problems around certification are highlighted, among which reproducibility of results, initiation and an adequate definition of relevant design features in the stage of verification of drawings. With switchgear having an increasing rated voltage coming on the market, there is an increased tendency to perform internal arc testing with reduced voltage, because of lack of sufficient short-circuit power. With actual examples, it will be demonstrated to what extent such "reduced voltage testing" is acceptable, the main problem being the uncertainty of the arc motion inside the enclosure, and its effect on the current (asymmetry) through its arc voltage. From environmental point of view, internal arc testing in SF6 filled installations is accepted less and less, tempting to replace SF6 (in SF6 insulated MV switchgear) by air in the regular testing of SF6 insulated MV switchgear. A literature overview is presented of several earlier investigations on the differences between arcing in SF6 and air in MV switchgear. New arcing tests are presented with the arcing in an SF6 and air filled model (0.5 m3, 14 kA and arc duration of 0.5 and 1 s). Arc voltage, current and pressure measurements, as well as high-speed infrared and optical imaging are used to demonstrate the differences between arcing in SF6 and air. It is observed that internal pressure rise as a result of arcing in air proceeds significantly faster than in SF6, and reaches higher values than in SF6. After pressure relief, however, the amount of energy supplied to the environment is higher by arcing in SF6 than in air. Concluding, all experimental results suggest that when replacing SF6 (of SF6 insulated switchgear) with air for internal arc testing, the mechanical stress on the switchgear itself is too severe because of higher and faster rising pressure in air. The effects on the environment (indicators as used in testing, pressure and temperature in switchgear compartments & -room) after pressure relief are distinctly different in SF6 and air, but are not part of IEC tests. Results suggest that adequate test procedures need to be designed that should justify replacement of SF6 by air for internal arc testing

Internal arcing : issues related to testing and standardization

Internal arc tests are intended to verify the effectiveness of switchgear design in protecting personnel in case of an internal arc. With the IEC 62271-200 & 201 in 2003, new methods and criteria for testing metal / insulation enclosed switchgear under conditions of an internal arc have been formulated. KEMA's experiences with the new standards will be highlighted, including statistics on the failure rates (approx. 20%), differentiated to the various acceptance criteria. A comparison with experiences related to the prior standard (IEC 60298) will be presented. Various problems around certification are highlighted, among which reproducibility of results, initiation and an adequate definition of relevant design features in the stage of verification of drawings. With switchgear having an increasing rated voltage coming on the market, there is an increased tendency to perform internal arc testing with reduced voltage, because of lack of sufficient short-circuit power. With actual examples, it will be demonstrated to what extent such "reduced voltage testing" is acceptable, the main problem being the uncertainty of the arc motion inside the enclosure, and its effect on the current (asymmetry) through its arc voltage. From environmental point of view, internal arc testing in SF6 filled installations is accepted less and less, tempting to replace SF6 (in SF6 insulated MV switchgear) by air in the regular testing of SF6 insulated MV switchgear. A literature overview is presented of several earlier investigations on the differences between arcing in SF6 and air in MV switchgear. New arcing tests are presented with the arcing in an SF6 and air filled model (0.5 m3, 14 kA and arc duration of 0.5 and 1 s). Arc voltage, current and pressure measurements, as well as high-speed infrared and optical imaging are used to demonstrate the differences between arcing in SF6 and air. It is observed that internal pressure rise as a result of arcing in air proceeds significantly faster than in SF6, and reaches higher values than in SF6. After pressure relief, however, the amount of energy supplied to the environment is higher by arcing in SF6 than in air. Concluding, all experimental results suggest that when replacing SF6 (of SF6 insulated switchgear) with air for internal arc testing, the mechanical stress on the switchgear itself is too severe because of higher and faster rising pressure in air. The effects on the environment (indicators as used in testing, pressure and temperature in switchgear compartments & -room) after pressure relief are distinctly different in SF6 and air, but are not part of IEC tests. Results suggest that adequate test procedures need to be designed that should justify replacement of SF6 by air for internal arc testing

Rapid Method for Small Grain and Corn Flour Authentication Using GC/EI-MS and Multivariate Analysis

The aim of this study was the application of the gas chromatography-mass spectrometry system (GC/EI-MS) system and multivariate data analysis to investigate the possibility of chemical differentiation between small grain flour (wheat, barley, oat, triticale, rye) and corn flour samples. All cereal flour samples were first defatted with hexane, after which the extraction with ethanol was performed. Extracted simple sugars (monosaccharides, disaccharides, trisaccharides, and sugar alcohols) were analyzed in the form of their corresponding trimethylsilyl oximes. Peaks of simple sugar derivatives were selected in total ion current (TIC) chromatograms by monitoring exclusively the following characteristic abundant ions: 204, 217, and 361 m/z. The total surface areas under the selected peaks were subjected to multivariate analysis. Applying principal coordinate analysis and hierarchical cluster analysis to obtained data, samples of corn flour could be very clearly distinguished from all samples of small grain flour, which presented a weaker separation among each other. This method circumvents common analytical procedures by excluding simple sugar identifications, quantitative analysis, the use of analytical standards, and calibration curves. Results are applicable in the quality assurance of mixed flour on the market, considering the increased popularity of their consumption in human nutrition

The added value of simulated near-surface wind speed over the Alps from a km-scale multimodel ensemble

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