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333. Efektívnosť ílových minerálov pri znižovaní vooodpudivosti počas dlhého suchého a teplého obdobia

Creator:
Lichner, Ľubomír and Dlapa, Pavel
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
water repellency, sand, stearic acid, clay minerals, vodoodpudivosť, piesok, kyselina stearová, and ílové minerály
Language:
Slovak
Description:
The aim of this study was to evaluate an efficiency of clay minerals (kaolinite, illite, Na- and Ca-montmorillonite) in alleviating the water repellency of stearic acid sand during the course of long-term hot and dry spell. This spell was simulated by prolonged drying (incubation) of the samples in oven at 50°C. It was found that the kaolinite addition resulted in a drop in the persistence of water repellency of the stearic acid sand. On the contrary, the Ca-montmorillonite addition increased markedly the persistence of water repellency of the stearic acid sand. In most cases, the illite addition resulted in an increase in the persistence of water repellency, even though not so markedly as it was in the case of Ca-montmorillonite addition. In the case of Na-montmorillonite addition, the striking drop in the persistence of water repellency of the stearic acid sand was registered only after lowering the moisture below 5 %. An increase in the persistence of water repellency of the sand-clay mixture with an increase in the clay amount is another interesting finding, observed in case of kaolinite and Ca-montmorillonite. and Cieľom tejto štúdie bolo zhodnotenie efektívnosti ílových minerálov (kaolinitu, illitu, Na- a Camontmorillonitu) pri znižovaní stálosti vodoodpudivosti piesku pokrytého kyselinou stearovou počas dlhého suchého a teplého obdobia, simulovaného inkubáciou vzoriek pri teplote 50 °C. Zistili sme, že pridanie kaolinitu výrazne znížilo stálosť vodoodpudivosti piesku pokrytého kyselinou stearovou prakticky počas celého cyklu sušenia. Pridanie Ca-montmorillonitu naopak stálosť vodoodpudivosti piesku pokrytého kyselinou stearovou výrazne zvýšilo. Pridanie illitu vo väčšine prípadov zvýšilo stálosť vodoodpudivosti piesku pokrytého kyselinou stearovou, aj keď nie tak výrazne ako pridanie Ca-montmorillonitu. V prípade pridania Na-montmorillonitu sme výrazné zníženie vodoodpudivosti piesku pokrytého kyselinou stearovou zaznamenali až po poklese vlhkosti vzorky pod 5 %. Ďalším zaujímavým poznatkom je vzrast vodoodpudivosti so zvyšujúcim se obsahom ílu, ktorý sme zaregistrovali v prípade kaolinitu a Ca-montmorillonitu.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

334. Effect of drying on the sorption and desorption of copper in bottom sediments from water reservoirs and geochemical partitioning of heavy metals and arsenic

Creator:
Hiller, Edgar and Šutriepka, Michal
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
heavy metals, sorption, desorption, mobility, sequential extraction, dredged sediments, ťažké kovy, sorpcia, desorpcia, mobilita, sekvenčná extrakcia, and vyťažené sedimenty
Language:
Slovak
Description:
Bottom sediments can be significant sinks for a variety of heavy metals and metalloids coming from various anthropogenic sources. When these sediments are dredged and disposed of to land, drying and oxidation can lead to several changes in their physico-chemical properties, such as redox potential and pH, and hence to changes in metal mobility. Therefore, this work was conducted to study the adsorptiondesorption behaviour of one selected heavy metal - copper - in three bottom sediment samples before and after drying. Moreover, possible geochemical associations of As, Cd, Co, Cu, Hg, Ni, Pb and Zn in the airdried sediments were studied using a modified BCR sequential extraction protocol. Generally, redox state of the sediments changed from the highly anoxic to oxic and adsorption of Cu2+ decreased when the originally anoxic sediments were dried. On the other hand, the enhanced release of Cu2+ was observed from the air-dried sediments. The adsorption-desorption data showed that the changes in metal leachability occurred between originally anoxic and air dried sediments. In terms of water and soil pollution by Cu and likely other heavy metals, it appears that the dredged, air-dried sediments could represent somewhat greater contamination risks when compared with the originally anoxic sediments. Using the sequential extraction data, leaching potential of heavy metals and arsenic in the air-dried sediments was possible to evaluate with Cd, Co, Zn as the most mobile heavy metals, followed by Cu, Ni, As, Pb and Hg, respectively. and Dnové sedimenty sú významnými adsorbentmi celej rady ťažkých kovov a polokovov, ktoré pochádzajú z rôznych antropogénnych zdrojov. Po vyťažení týchto sedimentov z vodných nádrží na zemský povrch prechádzajú procesmi sušenia a oxidácie, ktoré menia niektoré ich vlastnosti, ako oxidačno-redukčný potenciál a pH, a teda môžu ovplyvňovať pohyblivosť potenciálne toxických kovov prítomných v sedimentoch. Z tohto dôvodu cieľom práce bolo štúdium adsorpcie a desorpcie jedného vybraného ťažkého kovu - medi - v troch vzorkách dnových sedimentov pred vysušením a po ňom. Okrem toho sme pomocou modifikovanej BCR metódy sekvenčnej extrakcie študovali možné geochemické interakcie ťažkých kovov (Cd, Co, Cu, Hg, Ni, Pb, Zn) a arzénu s jednotlivými zložkami dnových sedimentov. Ako ukázali experimentálne výsledky, počas sušenia sa zmenili redukčné podmienky v sedimentoch na oxidačné a adsorpčná kapacita vysušených sedimentov vzhľadom k Cu2+ bola výrazne nižšia ako u pôvodných sedimentov. Na druhej strane, množstvo uvoľneného Cu2+ z vysušených sedimentov bolo vyššie ako z pôvodných sedimentov. Uvedené zistenia teda poukazujú na zmenu v správaní a pohyblivosti potenciálne toxických prvkov medzi pôvodnými, redukčnými sedimentmi a tými, ktoré prešli procesom sušenia a oxidácie. Z hľadiska znečistenia prírodných vôd a pôd meďou a pravdepodobne aj ďalšími ťažkými kovmi sa zdá, že v porovnaní s pôvodnými kontaminovanými sedimentmi vyťažené a na vzduchu vysušené sedimenty môžu predstavovať vyššie riziko pre životné prostredie. Podľa výsledkov sekvenčnej extrakcie sa ukázalo, že Cd, Co a Zn sú po vysušení v skúmaných sedimentoch veľmi mobilnými prvkami, pričom pohyblivosť ostatných prvkov klesá v poradí Cu > Ni > As > Pb >> Hg.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

335. Effect of river training on flood retention of the Bavarian Danube

Creator:
Skublics, Daniel, Blöschl, Günter, and Rutschmann, Peter
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
flood retention, flood plain, inundation areas, flood management, and hydrodynamic modelling
Language:
Slovak
Description:
The Bavarian Danube River has experienced numerous large flood events in recent years which make flood management an urgent matter. The propagation of flood waves along the river is heavily influenced by controlled and natural flood retention. Over the past centuries, natural flood retention areas were lost due to river training, and the hydraulic characteristics of the channel-flood plain system were modified. The purpose of this paper is to understand the effect of river training on the flood retention characteristics along the Bavarian Danube. Systematic two-dimensional hydrodynamic modelling shows that extreme floods are attenuated more strongly in the present state of the channel-flood plain system than they were historically. This is because the retention areas are filled later during the event, so the attenuation effect is much larger for the same magnitude of the retention volume. Natural flood retention is therefore not an effective management option for reducing extreme floods on the Bavarian Danube. Controlled flood retention measures provide a higher efficiency regarding peak attenuation to retention volume ratio. On the other hand, the delay of flood peaks due to natural retention may be beneficial for the superposition of the flood waves with contributions from downstream tributaries.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

336. Effect of the parameters of sand-water mixtures on the specific energy of hydrodynamic pumps

Creator:
Melichar, Jan
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
slurry transport, dredge pump, specific energy reduction, slurry flow, hydrodoprava substrátů, bagrovací čerpadlo, pokles měrné energie, and proudění suspenze
Language:
Slovak
Description:
The paper deals with the effect of the parameters of aqueous slurries of particulate matter on the functional relationship between the specific energy and the flow rate of hydrodynamic dredge pumps. The empirical conversion equations available from literature are reviewed. The methods of converting the pump characteristics at clear water to those which apply for slurries have been incorporated into a straightforward, user-friendly computer program which can be run on a PC. The program may be adopted in the design of hydro-transportation systems involving hydrodynamic dredge pumps. The program computes the specific pump energy as a function of flow rate at given rotary speed, for specific operating conditions of the pump, i.e., for specific parameters of the slurry.The paper deals with the effect of the parameters of aqueous slurries of particulate matter on the functional relationship between the specific energy and the flow rate of hydrodynamic dredge pumps. The empirical conversion equations available from literature are reviewed. The methods of converting the pump characteristics at clear water to those which apply for slurries have been incorporated into a straightforward, user-friendly computer program which can be run on a PC. The program may be adopted in the design of hydro-transportation systems involving hydrodynamic dredge pumps. The program computes the specific pump energy as a function of flow rate at given rotary speed, for specific operating conditions of the pump, i.e., for specific parameters of the slurry. and Článek pojednává o vlivu parametrů hydrosměsi písku na funkční vztah měrná energie - průtok hydrodynamických bagrovacích čerpadel. Uvádí přehled empirických přepočtových vztahů v dostupných literárních podkladech. Metody přepočtu charakteristik čerpadla z čisté vody na hydrosměs byly zapracovány do uživatelsky jednoduchého výpočtového programu pro osobní počítač. Program lze využít při návrhu hydrodopravních systémů s hydrodynamickými bagrovacími čerpadly. Výstupem programu jsou závislosti měrné energie čerpadla na průtoku při daných otáčkách pro konkrétní podmínky provozu čerpadla, resp. pro konkrétní parametry suspenze.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

337. Effects of olive mill wastewater disposal on soil: Interaction mechanisms during different season

Creator:
Tamimi, Nisreen, Diehl, Dörte, Njoum, Mohand, Marei, Amer, and Schaumann, Gabriele E.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
olive mill wastewater, soil water repellency, acidification, salinity, soluble phenolic compounds, and leaching
Language:
Slovak
Description:
Environmental conditions play a major role for effects of olive mill wastewater (OMW) application to soil. Choosing a different season for OMW application than the commonly practiced winter, may help avoid negative effects. However, understanding of the OMW-soil interaction during different seasons is still incomplete due to the lack of comparative data. In this study, an 18 months field experiment was carried out in an olive orchard in West Bank. Degree and persistence of soil salinization, acidification, accumulation of phenolic compounds and soil water repellency were investigated as a function of soil depth and time elapsed after OMW application, which was performed either in spring, summer (with and without irrigation) or winter. The persistence of negative effects increased with duration of the hot and dry period following the application due to accumulation and polymerization of OMW. On the other hand, leaching of OMW components to groundwater is favored during the rainy season and by formation of preferential flow paths before the rain season starts. The risks of groundwater contamination and persistent negative effects decrease with increasing time under conditions favoring biological activity. Therefore, OMW application in spring if improved by a careful irrigation is considered as the most suitable under semiarid conditions for clay loam soils.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

338. Effects of patterned Artemisia capillaris on overland flow resistance under varied rainfall intensities in the Loess Plateau of China

Creator:
Zhang, Guanhua, Liu, Guobin, Yi, Liang, and Zhang, Pingcang
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
overland flow, Darcy-Weisbach friction coefficient, patch pattern, vegetation structure, simulated rainfall, and Loess Plateau
Language:
Slovak
Description:
In this paper simulated rainfall experiments in laboratory were conducted to quantify the effects of patchy distributed Artemisia capillaris on spatial and temporal variations of the Darcy-Weisbach friction coefficient (f). Different intensities of 60, 90, 120, and 150 mm h-1 were applied on a bare plot (CK) and four different patched patterns: a checkerboard pattern (CP), a banded pattern perpendicular to slope direction (BP), a single long strip parallel to slope direction (LP), and a pattern with small patches distributed like the letter ‘X’ (XP). Each plot underwent two sets of experiments, intact plant and root plots (the above-ground parts were removed). Results showed that mean f for A. capillaris patterned treatments was 1.25-13.0 times of that for CK. BP, CP, and XP performed more effectively than LP in increasing hydraulic roughness. The removal of grass shoots significantly reduced f. A negative relationship was found between mean f for the bare plot and rainfall intensity, whereas for grass patterned plots fr (mean f in patterned plots divided by that for CK) increased exponentially with rainfall intensity. The f -Re relation was best fitted by a power function. Soil erosion rate can be well described using f by a power-law relationship.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

339. Effects of relative submergence and bed slope on sediment incipient motion under decelerating flows

Creator:
Bolhassani, Ramin, Afzalimehr, Hossein, and Dey, Subhasish
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
fluvial hydraulics, open channel flow, river beds, sediment transport, shear stress, and streamflow
Language:
Slovak
Description:
This paper presents the results of an experimental study to quantify the effects of bed slope and relative submergence on incipient motion of sediment under decelerating flows. Experiments were conducted in an experimental tilting-flume of 8 m long 0.4 m wide and 0.6 m deep with glass-walls. Three uniform sediments with median grain sizes of 0.95, 1.8 and 3.8 mm and three bed slopes of 0.0075, 0.0125 and 0.015 were used under decelerating flow. The main conclusion is that the Shields diagram, which is commonly used to evaluate the critical shear stress, is not suitable to predict the critical shear stress under decelerating flows.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

340. Elektronický sborník příspěvků multioborové konference LASER62: hotel Galant, Lednice, 9.-11. listopad 2022

Creator:
Růžička, Bohdan
Publisher:
Ústav přístrojové techniky AV ČR,v.v.i.
Format:
electronic, electronic resource, remote, bez média, online zdroj, and 87 stran : ilustrace, tabulky, grafy.
Type:
model:monograph and TEXT
Subject:
Elektrotechnika, lasery, mezioborový kontext, lasers, interdisciplinary context, 621.375.826, 681.7.069.24, 535.8, 001.2, (062.534), (0.034.2:08), 19, and 621.3
Language:
Czech, English, and Slovak
Description:
editor: Bohdan Růžička., Obsahuje bibliografie, České, anglické a slovenské příspěvky, and born digital
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public