For the safe and economical design and operation of freight pipelines it is necessary to know slurry flow behaviour in inclined pipe sections, which often form significant part of pipelines transporting solids. Fine-grained settling slurry was investigated on an experimental pipe loop of inner diameter D = 100 mm with the horizontal and inclined pipe sections for pipe slopes ranging from –45° to +45°. The slurry consisted of water and glass beads with a narrow particle size distribution and mean diameter d50 = 180 μm. The effect of pipe inclination, mean transport volumetric concentration, and slurry velocity on flow behaviour, pressure drops, deposition limit velocity, and concentration distribution was studied. The study revealed a stratified flow pattern of the studied slurry in inclined pipe sections. Frictional pressure drops in the ascending pipe were higher than that in the descending pipe, the difference decreased with increasing velocity and inclination. For inclination less than about 25° the effect of pipe inclinations on deposition limit velocity and local concentration distribution was not significant. For descending pipe section with inclinations over –25° no bed deposit
was observed.
Gravity-driven open-channel flows carrying coarse sediment over an erodible granular deposit are studied. Results of laboratory experiments with artificial sediments in a rectangular tilting flume are described and analyzed. Besides integral quantities such as flow rate of mixture, transport concentration of sediment and hydraulic gradient, the experiments include measurements of the one-dimensional velocity distribution across the flow. A vertical profile of the longitudinal component of local velocity is measured across the vertical axis of symmetry of a flume cross section using three independent measuring methods. Due to strong flow stratification, the velocity profile covers regions of very different local concentrations of sediment from virtually zero concentration to the maximum concentration of bed packing. The layered character of the flow results in a velocity distribution which tends to be different in the transport layer above the bed and in the sediment-free region between the top of the transport layer and the water surface. Velocity profiles and integral flow quantities are analyzed with the aim of evaluating the layered structure of the flow and identifying interfaces in the flow with a developed transport layer above the upper plane bed.
Snow accumulation and melt are highly variable. Therefore, correct modeling of spatial variability of the snowmelt, timing and magnitude of catchment runoff still represents a challenge in mountain catchments for flood forecasting. The article presents the setup and results of detailed field measurements of snow related characteristics in a mountain microcatchment (area 59 000 m2 , mean altitude 1509 m a. s. l.) in the Western Tatra Mountains, Slovakia obtained in winter 2015. Snow water equivalent (SWE) measurements at 27 points documented a very large spatial variability through the entire winter. For instance, range of the SWE values exceeded 500 mm at the end of the accumulation period (March 2015). Simple snow lysimeters indicated that variability of snowmelt and discharge measured at the catchment outlet corresponded well with the rise of air temperature above 0°C. Temperature measurements at soil surface were used to identify the snow cover duration at particular points. Snow melt duration was related to spatial distribution of snow cover and spatial patterns of snow radiation. Obtained data together with standard climatic data (precipitation and air temperature) were used to calibrate and validate the spatially distributed hydrological model MIKE-SHE. The spatial redistribution of input precipitation seems to be important for modeling even on such a small scale. Acceptable simulation of snow water equivalents and snow duration does not guarantee correct simulation of peakflow at shorttime (hourly) scale required for example in flood forecasting. Temporal variability of the stream discharge during the snowmelt period was simulated correctly, but the simulated discharge was overestimated.
Extensive experimental investigations were carried out to evaluate the rheological behaviour of fly ash (FA) slurry without and with the addition of bottom ash (BA) and BA slurry without and with the addition of FA. The FA slurries exhibited Bingham behaviour at solid mass concentrations ranging from 60-65% and mixing proportions from 10- 40%. A substantial reduction in yield stress was observed except for mixing proportion of 40% on which the yield stress and viscosity were increased drastically for all solid concentrations. Hence, it can be concluded that the yield stress and viscosity of FA slurry were very much influenced by adding BA up to the mixing proportion of 30%. The rheological behaviour of BA slurries with and without the addition of FA in proportions of 10-50% was investigated and exhibited Newtonian behaviours for solid mass concentrations ranging from 30-50% without and with the addition of FA. The viscosity increases with increasing the solid concentrations and proportion of FA. Based on these experimental data, a correlation was developed to predict the relative viscosity of BA slurries as a function of solid volume fraction and FA mass proportion of 0-50% and the RMSE and R2 values showed good agreement between the experimental and the predicted data.
The experimental basins in the Jizera Mountains were established at the beginning of the 1980th as a result of the forest devastation due to acid rain and repercussions of following human activities during its disposal with the aim to gain data for the quantification of runoff conditions changes in a changing environment. Seven small catchments with an area from 1.87 km2 to 10.6 km2 are situated in the spring regions in an elevation from 700 m a.s.l. to 1100 m a.s.l. in the catchments of the Černá Nisa, Kamenice, Jizerka and Směda streams. The long-term average annual temperature in the elevation of 780 m a.s.l. is +4.4°C, the long-term annual precipitation sum fluctuates between 1300 mm and 1800 mm. The Jizera Mountains are known for numerous intensive rainfalls in the summer period. The administrator of the experimental basins is the Czech Hydrometeorological Institute (CHMI), Department of Hydrological Research, Experimental Base Jablonec nad Nisou, which performs all operative activities and basic processing of data. In the basins, the monitored elements are water stages and discharges in rivers, surface water quality, rainfall, snow depth and snow water equivalent and climatological parameters. The following contribution gives an overview of information obtained from the hydrological research in the period 1981 - 2004. and Příspěvek se zabývá přehledem poznatků z hydrologického výzkumu v období let 1982-2005 v experimentálních povodích Českého hydrometeorologického ústavu (ČHMÚ) v imisně poškozené oblasti Jizerských hor. Základnu tvoří 7 malých povodí s rozlohou od 1,87 km2 do 10,6 km2 celkové plochy 37 km2 . Všechna povodí leží ve vrcholové části Jizerských hor v Chráněné krajinné oblasti Jizerské hory, na rozvodí řek Labe a Odry. Nadmořská výška povodí se pohybuje mezi 700 až 1100 m. Správcem povodí je Oddělení hydrologického výzkumu, pracoviště Jablonec nad Nisou. Zpočátku byly práce zaměřeny převážně na získání co největšího počtu informací o srážkách, sněhu, množství a jakosti povrchové vody. Po roce 1995 byl monitoring rozšířen na více parametrů hydrologické bilance, sledování klimatických prvků a složek hydrologického procesu. Následně byl upřesňován jejich režim i jejich prostorové rozložení. Byla studována problematika rozdílnosti akumulace a odtávání sněhu na mýtině a v lese a odtoková a kvalitativní odezva na srážkovou činnost a tání sněhu. Za pomoci hydrologických a chemických modelů byly hledány odhady změn jejich závislosti na změně vegetačního pokryvu.
An experimental study on initial water flow through an empty pipe under conditions of free level and steady inflow into the pipe. The study presents results of the analysis of experimental values of wave front velocity and outflow from a pipe and their experimental eqautions. and Experimentální studie pojednává o napouštění prázdného potrubí vodou s volnou hladinou a s konstantním přítokem do potrubí. Studie předkládá výsledky rozboru experimentálních hodnot rychlostí čela vlny a odtoku vlny z potrubí i jejich experimentální rovnice.
In the first part of the paper, I argue that explicating systems which fall under the simple theory of types are limited in explicating our conceptual scheme. Such limitation is avoided if one utilizes, instead, a ramified type theory, especially the one developed by Pavel Tichý. In the third part of the paper, I explain the role of so-called constructions and derivation systems within such a framework, elucidating how deduction demonstrates properties of objects., V první části příspěvku tvrdím, že vysvětlující systémy, které spadají pod jednoduchou teorii typů, jsou omezeny na vysvětlování našeho konceptuálního schématu. Tomuto omezení se vyhýbáme, pokud místo toho využijeme teorii rozvětveného typu, zejména teorii vyvinutou Pavlem Tichým. Ve třetí části práce vysvětluji roli takzvaných konstrukcí a derivačních systémů v takovém rámci, objasňujícím, jak dedukce demonstruje vlastnosti objektů., and Jiří Raclavský
The concept of expressivity of a theory or a system ́(for example a system of concepts or - derivatively - of basic expressions) is surely important: a theory (system) is the more expressive the more problems it allows to be solved. We will try to formulate or at least to suggest an explication of this notion. We will, of course, assume that an appropriate explication of the notion of problem has been given., Pojem expresivity teorie nebo systému ́ (např. Systém pojmů nebo - derivativně - základních výrazů) je jistě důležitý: teorie (systém) je výraznější, čím více problémů umožňuje řešit. Pokusíme se formulovat nebo alespoň navrhnout vysvětlení tohoto pojmu . Samozřejmě budeme předpokládat, že byl poskytnut vhodný výklad pojmu problému ., and Pavel Materna
In this paper, I focus on the notion of expressive completeness in Robert Brandom’s Making It Explicit. For Brandom as a normative pragmatist, a theory of meaning is expressively complete if it specifies a human practice that is sufficient to confer on expressions conceptual contents so rich that the very conferring practice can be described by means of these expressions. I put the notion of expressive completeness in contrast with the related, but non-identical notion of self-referentiality of a semantic theory. Further, I examine the position of the concept in Brandom’s philosophical project: I assess the justification Brandom provides for his claim of expressive completeness of the presented theory, and I outline the consequences he can draw for his overall project provided that expressive completeness is achieved. Whether it is actually achieved, remains however an open question., V tomto příspěvku se zaměřuji na pojetí expresivní úplnosti v tom, jak to dělá Robert Brandom. Pro Brandom jako normativní pragmatist, teorie významu je výslovně kompletní jestliže to specifikuje lidskou praxi to je dostačující, aby udělil výrazy pojmový obsah tak bohatý že velmi svěřující praxe může být popsána pomocí těchto výrazů. Pojem expresivní úplnost jsem postavil do kontrastu s příbuzným, ale ne identickým pojmem sebekontroly sémantické teorie. Dále zkoumám pozici konceptu ve filosofickém projektu Brandomu: Posuzuji, že ospravedlnění Brandom poskytuje jeho vyjádření výrazové úplnosti předložené teorie, a nastíním následky, které může čerpat pro jeho celkový projekt za předpokladu, že je dosaženo výrazné úplnosti. Ať už je skutečně dosaženo, zůstává otevřenou otázkou., and Radek Ocelák
The extent (determined by the repellency indices RI and RIc) and persistence (determined by the water drop penetration time, WDPT) of soil water repellency (SWR) induced by pines were assessed in vastly different geographic regions. The actual SWR characteristics were estimated in situ in clay loam soil at Ciavolo, Italy (CiF), sandy soil at Culbin, United Kingdom (CuF), silty clay soil at Javea, Spain (JaF), and sandy soil at Sekule, Slovakia (SeF). For Culbin soil, the potential SWR characteristics were also determined after oven-drying at 60°C (CuD). For two of the three pine species considered, strong (Pinus pinaster at CiF) and severe (Pinus sylvestris at CuD and SeF) SWR conditions were observed. Pinus halepensis trees induced slight SWR at JaF site. RI and RIc increased in the order: JaF < CuF < CiF < CuD < SeF, reflecting nearly the same order of WDPT increase. A lognormal distribution fitted well to histograms of RIc data from CuF and JaF, whereas CiF, CuD and SeF had multimodal distributions. RI correlated closely with WDPT, which was used to develop a classification of RI that showed a robust statistical agreement with WDPT classification according to three different versions of Kappa coefficient.