Understanding and modelling the processes of flood runoff generation is still a challenge in catchment hydrology. In particular, there are issues about how best to represent the effects of the antecedent state of saturation of a catchment on runoff formation and flood hydrographs. This paper reports on the experience of mapping saturated areas using measured water table by piezometers and more qualitative assessments of the state of the moisture at soil surface or immediately under it to provide information that can usefully condition model predictions. Vegetation patterns can also provide useful indicators of runoff source areas, but integrated over much longer periods of time. In this way, it might be more likely that models will get the right predictions for the right reasons.
In the study of Tomlain (1997) a soil water balance model was applied to evaluate the climate change impacts on the soil water storage in the Hurbanovo locality (Southwestern Slovakia), using the climate change scenarios of Slovakia for the years 2010, 2030, and 2075 by the global circulation models CCCM, GISS and GFD3. These calculations did not take into consideration neither the various soil properties, nor the groundwater table influence on soil water content. In this study, their calculated data were compared with those monitored at the same sites. There were found significant differences between resulting soil water storage of the upper 100 cm soil layer, most probably due to cappilary rise from groundwater at sites 2 and 3. It was shown, that the soil properties and groundwater table depth are importat features strongly influencing soil water content of the upper soil layer; thus the application of the soil water balance equation (Eq. (1)), neglecting the above mentioned factors, could lead to the results far from reality. and V práci Tomlaina (1997) bol aplikovaný bilančný model vodného režimu pôd na ohodnotenie dopadu klimatickej zmeny na vodné zásoby pôdy v lokalite Hurbanovo (juhozápadné Slovensko), použijúc scenáre klimatickej zmeny pre Slovensko pre roky 2010, 2030 a 2075, založené na globálnych cirkulačných modeloch CCCM, GISS a GFD3. V týchto výpočtoch nebol braný do úvahy vplyv vlastností pôdy a hladiny podzemnej vody na vlhkosť pôdy. V práci boli porovnané vypočítané hodnoty zásob vody s monitorovanými v tej istej lokalite. Bol nájdený význačný rozdiel medzi zásobami vody v 100-cm hornej vrstve pôdy najpravdepodobnejšie spôsobený kapilárnym prítokom od hladiny podzemnej vody v monitorovacích miestach 2 a 3. Bolo ukázané, že pôdne vlastnosti a hĺbka hladiny podzemnej vody sú dôležitými faktormi, ktoré silno ovplyvňujú vlhkosť hornej vrstvy pôdy; z toho vyplýva, že aplikácia bilančnej rovnice (rov. (1)), ktorá zanedbáva vyššie uvedené faktory, nedáva reálne výsledky.
A key physical property used in the description of a soil-water regime is a soil water retention curve, which shows the relationship between the water content and the water potential of the soil. Pedotransfer functions are based on the supposed dependence of the soil water content on the available soil characteristics, e.g., on the relative content of the particle size in the soil and the dry bulk density of the soil. This dependence could be extracted from the available data by various regression methods. In this paper, artificial neural networks (ANNs) and support vector machines (SVMs) were used to estimate a drying branch of a water retention curve. The paper compares the mentioned methods by estimating the water retention curves on regional scale for the Záhorská lowland in the Slovak Republic, where relatively small data set was available. The performance of the models was evaluated and compared. These computations did not fully confirm the superiority of SVMs over ANNs as is often proclaimed in the literature, because the results obtained show that in this study the ANN model performs somewhat better and is easier to handle in determining pedotransfer functions than the SVM models. Nevertheless, the results from both data-driven models are quite close, and the results show that they provide a significantly more precise outcome than a traditional multi-linear regression does., Autori sa v príspevku venujú určovaniu pedotransferových funkcií (PTF), ktoré umožňujú stanoviť body vlhkostných retenčných kriviek pôdy z ľahšie merateľných pôdnych vlastností a sú dôležitým prvkom modelovania vodného režimu pôdy. Ešte v minulej dekáde sa objavili snahy využívať na ich určenie umelé neurónové siete (UNS). Multi-layer perceptron (MLP) čiže viacvrstvový perceptrón je najčastejšie používaný model doprednej umelej neurónovej siete s kontrolovaným typom učenia. Vstupné signály prechádzajú sieťou typu MLP iba dopredným smerom, teda postupne od vrstvy k vrstve. MLP používa tri a viac vrstiev neurónov rozdelených na vstupnú, skrytú a výstupnú vrstvu s nelineárnou aktivačnou funkciou a vie rozpoznať alebo modelovať informácie, ktoré nie sú lineárne oddeliteľné alebo závislé. Novší vývoj v oblasti učiacich algoritmov poskytuje ďalšie možnosti, z ktorých sa v tomto príspevku venujeme tzv. mechanizmom podporných vektorov (Support Vector Machines - SVM). SVM využíva pri svojom kalibrovaní na riešený problém princíp tzv. štrukturálnej minimalizácie namiesto iba minimalizácie chyby - (Vapnik, 1995). Pri trénovaní siete MLP je jediným cieľom minimalizovať celkovú chybu. Pri SVM sa simultánne minimalizuje chyba aj zložitosť modelu. Použitie tohto princípu vedie zvyčajne k vyššej schopnosti generalizácie, t.j. umožneniu presnejších predpovedí pre dáta, ktoré neboli použité pri trénovaní SVM. Vhodnosť štandardnej umelej neurónovej siete, SVM a viacnásobnej lineárnej regresie sa v článku vyhodnocuje na základe údajov získaných z pôdnych vzoriek odobratých v lokalite Záhorskej nížiny. Pôvodné údaje a ich aplikáciu pri vyhodnocovaní vodného režimu pôd uvádza Skalová (2001, 2007), odkiaľ boli prevzaté vstupné dáta a to percentuálny obsah zrnitostných kategórií (I až IV podľa Kopeckého), redukovaná objemová hmotnosť (ρd) a vlhkosti pre vlkostné potenciály hw= -2.5, -56, -209, -558, -976, -3060, -15300 cm, ktoré boli stanovené laboratórne pre potreby určenia a testovania regresných závislostí. Vzhľadom na to, že pri odvodzovaní regionálnych PTF je častým prípadom nedostatok dát pre odvodenie dátovo riadených modelov, autori navrhli riešiť úlohu pomocou ansámblu MLP resp. SVM. Ansámbel dátovo riadených modelov bol vytvorený variabilným rozdelením údajov na trénovacie a validačné (validačnými údajmi sa testuje presnosť modelu vo fáze jeho tvorby, ešte sa používajú konečné testovacie dáta, ktoré neboli pri tvorbe modelu použité). Výsledky ukázali lepšie regresné schopnosti oboch dátovo riadených modelov (SVM aj MLP) voči multilineárnej regresii a o niečo lepšie výsledky boli získané z viacvrstvového perceptrónu než zo SVM., and Keďže v niektorých iných prácach mal zvyčajne vyššiu výpočtovú presnosť model založený na SVM než na UNS, autori odporúčajú pre budúci výskum preveriť vhodnosť kombinácie SVM a MLP modelov v dátovo riadenom skupinovom modeli.
The heterogeneity of water flow and solute transport was assessed during radioactive tracer infiltration experiment in a black clay loam soil using modified methods to estimate the effective cross section (ECS) and the degree of preferential flow (DPF). The results of field and numerical experiments showed that these parameters characterized the heterogeneity of water flow in the soils unequivocally. The ECS decreases non-linearly and the DPF increases linearly with an increase of the bypassing ratio (ratio of macropore flow rate to total flow rate). The ECS decreased and the DPF increased with depth, which suggests an increase in the heterogeneity of water flow with depth. The plot of the DPF against ECS values calculated from the tracer experiment data was consistent with the relationship obtained by the numerical simulation assuming preferential flow in the neighbourhood of three probes.
The paper describes qualitative analysis of contaminant transport in a homogeneous, isotropic aquifer where first order chemical reaction at the boundary and nonlinear decay act simultaneously. In order to analyze the relative merits, two types of disposal scheme are considered; (i) Scenario I: longer duration with low input concentration and (ii) Scenario II: short duration with higher input concentration. The governing advective-dispersion equation is solved numerically by employing ADI scheme under finite difference method. We apply the method of moments to investigate mean concentration distribution and other statistical parameters such as central moment, coefficients of skewness (β2 ) and kurtosis (β 3 ). The mean concentration distribution ( Cm ) is computed by applying Edgeworth’s asymptotic series for non-Gaussian curves involving Hermite polynomials ( Hn ). The forward displacement of centroid ( Xg ) with time, deviations of mean concentration distribution from Gaussianity and breakthrough curves have been examined. and Príspevok obsahuje kvalitatívnu analýzu transportu kontaminantov v homogénnej, izotropnej zvodni, na hraniciach ktorej simultánne prebiehajú chemické reakcie prvého rádu a nelineárny rozpad. Aby sme mohli posúdiť relatívne výhody spôsobu analýzy, použili sme dva typy schém; (i) Scenár I: nízka koncentrácia vstupov a ich dlhšie trvanie; (ii) Scenár II: krátko trvajúce vysoké koncentrácie vstupov. Advektívnodisperzná rovnica je riešená numericky, s využitím schémy ADI v rámci metódy konečných rozdielov. Na určovanie rozdelenia priemerných koncentrácií a iných štatistických parametrov, ako je centrálny moment, koeficient šikmosti (β2 ) a strmosť (β 3 ) , použili sme metódu momentov. Rozdelenie priemerných koncentrácií ( Cm ) sme vypočítali aplikáciou Edgeworthových asymptotických radov negaussovských kriviek, obsahujúcich Hermitove polynómy ( Hn ). Študovali sme dopredný posun centroidu ( Xg ) v závislosti od času, odchýlky od priemerných hodnôt rozdelenia priemerných koncentrácií od gaussovských, a určili sme tiež prienikové krivky.
The flow of a mixture of liquid and solid particles at medium and high volume fraction through an expansion in a rectangular duct is considered. In order to improve the modelling of the phenomenon with respect to a previous investigation (Messa and Malavasi, 2013), use is made of a two-fluid model specifically derived for dense flows that we developed and implemented in the PHOENICS code via user-defined subroutines. Due to the lack of experimental data, the two-fluid model was validated in the horizontal pipe case, reporting good agreement with measurements from different authors for fully-suspended flows. A 3D system is simulated in order to account for the effect of side walls. A wider range of the parameters characterizing the mixture (particle size, particle density, and delivered solid volume fraction) is considered. A parametric analysis is performed to investigate the role played by the key physical mechanisms on the development of the two-phase flow for different compositions of the mixture. The main focuses are the distribution of the particles in the system and the pressure recovery.
In this paper a problem of multiple solutions of steady gradually varied flow equation in the form of the ordinary differential energy equation is discussed from the viewpoint of its numerical solution. Using the Lipschitz theorem dealing with the uniqueness of solution of an initial value problem for the ordinary differential equation it was shown that the steady gradually varied flow equation can have more than one solution. This fact implies that the nonlinear algebraic equation approximating the ordinary differential energy equation, which additionally coincides with the wellknown standard step method usually applied for computing of the flow profile, can have variable number of roots. Consequently, more than one alternative solution corresponding to the same initial condition can be provided. Using this property it is possible to compute the water flow profile passing through the critical stage.
Concentration and particle size distribution has been experimentally measured in a 2D rectangular duct under near iso-kinetic conditions for multi-sized particulate slurry. Measurements have been made at different flow velocities for various efflux concentrations in the range of 10 to 50 % by weight. It is observed that the concentration profile is highly skewed towards the bottom of the duct, which reduces with increase in efflux concentration and velocity. Similar phenomenon is observed in the distribution of individual particle size fractions with the effect being more pronounced for the coarser particles. and Rozdělení koncentrace a velikosti částic bylo měřeno ve 2D pravoúhlém kanále při proudění disperze různě velkých částic za téměř iso-kinetických podmínek. Experimenty byly provedeny při různých rychlostech s dopravními koncentracemi v rozsahu 10 až 50 hmotnostních procent. Bylo zjištěno, že koncentrační profil je výrazně zešikmený ke dnu kanálu, což se však zmenšuje s růstem koncentrace a rychlosti. Podobný jev byl pozorován u distribuce částic jednotlivých velikostních frakcí. Jev se projevuje tím výrazněji, čím větší jsou částice.
In his book (2021) Trueman attempts to provide a solution to the problem of the concept horse, which according to Frege’s published writings is an object, not a concept. In the course of doing so Trueman rejects Wright’s response (1998) according to which some objects are also concepts, for example, the concept horse, so the categories are not exclusive. Trueman’s argument for exclusivity (Chapter 4) is the heart of the book, and as he says, it is his response to holders of differing views, like Wright. I think that there is a gap in Trueman’s argument which needs to be filled if Wright is to be considered refuted.
Conclusions of theoretical reasoning are assertions—or at least speech acts belonging to the class of assertives, such as hypotheses, predictions or estimates. What, however, are the conclusions of practical reasoning? Employing the concepts of speech act theory, in this paper I investigate which speech acts we perform when we’re done with an instance of a practical argument and present its result in a linguistic form. To this end, I first offer a detailed scheme of practical argument suitable for an external pragmatic account (rather than an internal cognitive account). Resorting to actual examples, I then identify a class of action-inducing speech acts as characteristic conclusions of practical argument. I argue that these speech acts—promises, orders, pieces of advice, proposals, and others—differ chiefly depending on the agent of the action induced (me, us, you, them) and their illocutionary strength.