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  • Author: Aleš Kučera x
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Morphology Analysis of Friction Particles Generated in Tractor Transmission Oils

Abstract

The aim of the study was the examination of the morphological and compositional attributes of wear particles of tested universal tractor transmission oil (UTTO) samples by means of automatic particle counter and classifier LaserNetFinesTM-C, which is an ideal tool to establish the dynamic equilibrium concentration and hence to set the alarm limits for any type of machine. Such limits can be based on wear type and particle size ranges. The samples of two UTTO (mineral oil and biodegradable fully synthetic oil) were taken from the rear gearboxes of the wheel tractor during a long-term experiment. The measurement results showed that there was faster increase in the particle wear of mineral oil in comparison to biodegradable transmission oil. Considering the increase in the percentage of particles over 20 μm, the biodegradable oil seems to be more favourable for usage. Regardless of this, it can be concluded that the biodegradable oil is equivalent to petroleum-based oils.

Open access
Soil Heterogeneity Reflected in Biogeography of Beech Forests in the Borderland Between the Bohemian Massif and the Outer Western Carpathians

Abstract

Soil environment characteristics naturally affect the biogeographical classification of forests in central Europe. However, even on the same localities, different systems of vegetation classification de-scribe the forest types according to the naturally dominant tree species with different accuracy. A set of 20 representative natural beech stands in the borderland between the Bohemian Massif (Hercyni-an biogeographical subprovince) and the Outer Western Carpathians (Westcarpathian subprovince) was selected in order to compare textural, hydrostatic, physico-chemical and chemical properties of soils between the included geomorphological regions, bioregions and biotopes. Differences in the soils of the surveyed beech stands were mainly due to volume weight and specific weight, maximum capillary capacity (MCC), porosity, base saturation (BS), total soil nitrogen (Nt) and fulvic acids. Specifics in the relations between these soil characteristics indicated that transient trans-Hercynian beech forests developed in the borderland between the two compared subprovinces. Soils of the investigated Hercynian beech forests were generally characterized by lower BS and lower Nt. Soils of the trans-Hercynian beech forests were more similar to the Carpathian beech forest soils than soils in the other Hercynian beech forests. Soils of the trans-Hercynian and Carpathian beech forests showed similarly higher BS, deeper occurrence of humic substances, lower specific weight and also higher MCC. Higher content of humic substances as well as MCC indicated an equal effect on forest ecology, which may contribute to more accurate classification of forests.

Open access
Monitoring of Environment in a Flashover Container in the Course of Enclosure Fire Simulation

Monitoring of Environment in a Flashover Container in the Course of Enclosure Fire Simulation

This article presents the results of experimental determination of temperature field and heat flux density in a flashover container used for the training of firefighters. Experimental measurements were carried out in a chamber No. 1 of a firefighting trainer of Fire and Rescue Service of the Czech Republic at Zbiroh. The article describes the design and equipment of this chamber, used method of measurement and test procedure. Measured values of temperature field and heat flux density are stated and discussed. In conclusion, recommendations for further measurements in this chamber aimed at acquiring other findings concerning thermal loads on firefighters in the course of training are presented.

Open access
Seasonal dynamics of arginine ammonification in forest soils of Norway spruce pure stands under different silvicultural practices

Abstract

Effects of seasonal dynamics and silvicultural practice on ammonification of arginine, one of the proteinogenic amino acids, were assessed in surface organic H-horizon of three Norway spruce pure stands in medium altitudes (600 - 660 m a.s.l.). Contents of ammonium ions NH4 + measured monthly in the field and contents of NH4 + after laboratory incubation of these samples with arginine were taken as dependent variables in ANOVA and in linear regression model using generalised linear model. The aim of the analyses was to determine the significance of decomposition of this amino acid in H-horizon of forest soils and to determine categorical and continuous predictors which influence intensity of the ammonification. Laboratory experiments confirmed its close link to seasonal dynamics, as well as to forest management; however the last mentioned was firstly found as less significant when compared within whole season. As regards to seasonal dynamics in forest soils, the highest amount of ammonium ion was released in May and the lowest in July. As regards to the silvicultural practice applied, more ammonium ion was released under mature spruce monoculture, especially in August and May; in the young stands, the method of thinning had no effect on the ammonium ion release. However, the arginine ammonification was found to be influenced by ammonium nitrogen content (slight, less significant negative correlation) and by soil water content (stronger positive significance), especially in the stand with thinning from below. This was concluded to be caused by changes in stand microclimate in function of the silvicultural practice.

Open access
Comparison of modern and traditional methods of soilsorption complex measurement : the basis of long -term studies and modelling

Abstract

This paper presents the correlations between two different analytical methods of assessing soil nutrient contents. Soil nutrient content measurements measured using the flame atomic absorption spectrometry (FAAS ) method, which uses barium chloride extraction, were compared with those of the now-unused Gedroiz method, which uses ammonium chloride extraction (calcium by titration, magnesium, potassium and sodium by weighing). Natural forest soils from the Ukrainian Carpathians at the localities of Javorník and Pop Ivan were used. Despite the risk of analysis errors during the complicated analytical procedure, the results showed a high level of correlation between different nutrient content measurements across the whole soil profile. This allows concentration values given in different studies to be linearly recalculated on results of modern method. In this way, results can be used to study soil’s chemical changes over time from the soil samples that were analysed in the past using labour-intensive and time-consuming methods with a higher risk of analytic error.

Open access