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  • Author: Stanislav Petr x
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Abstract

The aim of this paper is to design, implement, test and compare several tracking filtration methods for predictive maintenance of a jet engine. Based on literature review multiple possible methods are described. Appropriate ones selected for further implementation are peak filtration, coherent demodulation, Vold-Kalman filtration and order analysis. Methods are tested to meet criteria set by an aircraft manufacturer and compared using simulated signals.

Abstract

Although the orthogonal systems are predominantly employed within modern technologies, some general systems can be found principally in nature. Progress in the field of nanotechnologies based on a condensed matter will reach its limit at a certain moment, which may be caused by material limits or limits of manufacturing technologies. This limitation will affect both approaches, the top-down as well as the bottom-up. Another way to obtain a nanostructure will be based purely on nature and its ability to grow, which requires a deep understanding of the world of biology. This natural approach is closely connected with a precise mathematical description which is necessary for employment of both the analytical and synthetic tools which are presently available within the frame of current technological methods. In this paper, we present an analysis of a model based on a spiral arrangement on a series of elements.

Abstract

Norway spruce (Picea abies [L.] Karst.) and silver fir (Abies alba Mill.) are main tree species of Central Europe that are currently highly vulnerable in times of global climate change. The research deals with the effect of climate and air pollution on radial growth of silver fir and Norway spruce in mixed age-varied (56 – 146 years) forests in the Jeseníky Protected Landscape Area, the Czech Republic. The objectives were to evaluate biodiversity, structure and production, specifically interaction of radial growth of fir and spruce to air pollution (SO2, NOX, tropospheric ozone) and climatic factors (precipitation, air temperature). Concentration of SO2 and NOX had negative effect on radial growth of fir, while radial growth of spruce was more negatively influenced by tropospheric ozone. Fir showed higher variability in radial growth and was more sensitive to climatic factors compared to spruce. On the other hand, fir was relatively adaptable tree species that regenerated very well when the pressure of stress factors subsided (air pollution load, Caucasian bark beetle, frost damage). Low temperature was a limiting factor of radial growth in the study mountainous area, especially for fir. Fir was significantly sensitive to late frost, respectively, spruce to winter desiccation and spring droughts with synergism of air pollution load. Generally, older forest stands were more negatively influenced by air pollution load and climatic extremes compared to young trees.

Abstract

The aim was to investigate the antimicrobial susceptibility of most frequently isolated streptococci from Czech dairy herds. A total of 3,719 quarter milk samples were collected and cultivated between January 2017 and June 2018 from cows with clinical or subclinical mastitis from 112 farms. Only one isolate of each species, collected from the same farm per six-month period, was included in the susceptibility testing. The susceptibilities of Streptococcus uberis (163 isolates) and S. dysgalactiae (25 isolates) to 10 antimicrobials (penicillin – PEN, amoxicillin/clavulanic acid – AMC, ceftiofur – EFT, clindamycin – CLI, gentamicin – GEN, streptomycin – STR, trimethoprim/sulfamethoxazole – SXT, enrofloxacin – ENR, tetracycline – TET, rifampicin – RIF) from 9 groups were determined by measuring their minimum inhibitory concentrations. The percentages of resistant S. uberis isolates to the antimicrobials were as follows: TET (63.2%), STR (52.1%), CLI (30.1%), and RIF (2.5%). Intermediate susceptibility was found to RIF (63.2%), PEN (35%), ENR (2.5%), EFT (1.8%), and AMC (1.2%). All the S. uberis isolates were susceptible to GEN and SXT (100%). However, only 6.7% of S. uberis isolates were susceptible to all tested antimicrobials, and 38.7% of isolates were multidrug resistant (≥ 3 groups of antimicrobials). All the S. dysgalactiae isolates were susceptible to PEN, AMC, EFT, GEN, SXT, and ENR (100%). Resistant S. dysgalactiae isolates were found to TET (60%), STR (28%), CLI (12%), and intermediate to TET (24%) and RIF (20%). Sixteen percent of S. dysgalactiae isolates were multidrug resistant. The relatively high occurrence of (multiple) resistance, relative to mastitis pathogens, highlights the importance of monitoring this condition in dairy herds.

Abstract

The variety of post-socialist agricultural transitions in four different rural regions located in South Bohemia (Czech Republic), with respect to the utilisation of the older premises, is subject to analysis in this article. A complete database was constructed, containing the identification of agricultural premises in 1989 and their use in 2004 and 2017. From 1989 to 2004, a number of agricultural brownfields emerged, and many sites had been utilised for non-agricultural purposes. After 2004, the acreage of agricultural brownfields was reduced and new land-use utilisation for housing and, especially other non-agricultural activities, significantly increased. The transition in the utilisation of pre-1989 agricultural premises is strongly influenced by the social and economic contexts in which particular sites are located. Proximity to an upper-level regional centre is of crucial importance for decisions with respect to how (and if) the site will be reused. The peripheral location of the site also affects the level and the selection of options for the ways in which particular pre-1989 agricultural premises are used. In the case studies reported here, the marginality of particular regions is increased by their location in the border regions of outer peripheries, where the probability of the presence of agricultural brownfields and the probability of long-term abandonment of agricultural premises is higher. For the traditional developed countryside, we found a typical low level of the share of long-term agricultural brownfields. After 2004, the re-use of pre-1989 agricultural brownfields for agriculture was ascertained, which is complemented by their use for housing.

Abstract

The assessment of changes in the population spread of individual ichthyofauna species (lampreys and fishes) as well as the identification of unfavourable impacts is the necessary prerequisite for the correct selection of corrective measures. The river network in the Czech Republic belongs to the three sea-drainage areas (North Sea, Baltic Sea, and Black Sea). The species composition of the original ichthyofauna and the extent of the threat to some species differs in the individual sea-drainage areas. The original ichthyofauna in the Czech Republic consists of 4 lamprey species and 55 fish species. Out of this, only one lamprey species and 31 fish species originate in all three sea-drainage areas. There are 37 fish species considered as the original ones in the North Sea drainage area, there of 4 species are EX, 1 species EW, and 11 species (29.7%) are threatened. In the Baltic Sea drainage area, there are 4 species EX, 1 species EW, and 8 species (22.8%) threatened out of the total 35 assessed species. Out of 49 species in the Black Sea drainage area, there are 4 species EX and 23 species (46.9 %) threatened.

The most important reasons considered as the causes of the disappearance or reduction in the presence of some fishes are the water pollution, adjustments to water flow beds, the limitation of floods in alluvial areas, the permanent river basin fragmentation, and the spread of invasive species. Out of these factors, the only positive change has been noticed in the pronounced decrease in water flow pollution after 1990. Angling is also considered as the set of targeted bio manipulation which purposefully and often one-sidedly influences fish populations for the benefit of species being interesting for the angling sport.

Abstract

Reduction of nitrogen and phosphorus inputs into surface waters from nonpoint agricultural sources requires targeted application of differentiated measures. In the study focused on soil and water conservation in the Jihlava river basin upstream of the Dalešice reservoir, we identified areas at potential risk of soil erosion, elevated infiltration and nutrient leaching, tile-drained areas and vulnerable riparian zones of water bodies. We then designed a system of complex protective measures for this river basin in more variants, and their effectiveness was estimated using simple empirical model calculations and research findings. Application of the measures defined by optimal variant 3 in the studied watershed could lead to reduction of the soil erosion effects on the surface water quality by 26.5 %, with simultaneous reduction of the amount of washed out total nitrogen by 22.8 %. The results of our study constitute a partial component of the Qualitative Model of the Jihlava River Basin and they were provided for use to the Vysočina Region authorities and the State Land Office.

Abstract

Extreme ultraviolet (XUV) capillary-discharge lasers (CDLs) are a suitable source for the efficient, clean ablation of ionic crystals, which are obviously difficult to ablate with conventional, long-wavelength lasers. In the present study, a single crystal of cesium iodide (CsI) was irradiated by multiple, focused 1.5-ns pulses of 46.9-nm radiation delivered from a compact XUV-CDL device operated at either 2-Hz or 3-Hz repetition rates. The ablation rates were determined from the depth of the craters produced by the accumulation of laser pulses. Langmuir probes were used to diagnose the plasma plume produced by the focused XUV-CDL beam. Both the electron density and electron temperature were sufficiently high to confirm that ablation was the key process in the observed CsI removal. Moreover, a CsI thin film on MgO substrate was prepared by XUV pulsed laser deposition; a fraction of the film was detected by X-ray photoelectron spectroscopy.

Abstract

In this paper the authors attempt to answer the question of which location and site-specific factors have a decisive influence on the successful regeneration of brownfields. Using data from the South Moravian Region (Czech Republic), we analyze the spatial and functional distribution of brownfields, and test the correlation between the development potential of municipalities and the distribution of the brownfields that have already been regenerated. We then compare the structure and characteristics of existing and regenerated brownfields to identify significant drivers and barriers in the regeneration process. The findings indicate that regenerated brownfields are more likely located in municipalities with a higher local development potential (represented by the rate of local business activities, spatial peripherality - proximity to the regional centre and the main road network, and the quality of local infrastructure). It is also demonstrated that the large size of brownfields, their previous industrial use and the existence of contamination are not determinative barriers for regeneration if the brownfields are located in attractive areas and their ownership relations are not complicated.