This study examines two long-term time series of nitrate-nitrogen concentrations from the River Ouse and Stour situated in the Eastern England. The time series of monthly averages were decomposed into trend, seasonal and cyclical components and residuals to create a simple additive model. Residuals were then modelled by linear time series models represented by models of the ARMA (autoregressive moving average) class and nonlinear time series models with multiple regimes represented by SETAR (self-exciting threshold autoregressive) and MSW (Markov switching) models. The analysis showed that, based on the minimal value of residual sum of squares (RSS) of one-step ahead forecast in both datasets, SETAR and MSW models described the time series better than models ARMA. However, the relative improvement of SETAR models against ARMA models was low ranging between 1% and 4% with the exception of the three-regime model for the River Stour where the improvement was 48.9%. In comparison, the relative improvement of MSW models was between 44.6% and 52.5 for two-regime and from 60.4% to 75% for three-regime models. However, the visual assessment of models plotted against original datasets showed that despite a high value of RSS, some ARMA models could describe the analyzed time series better than AR (autoregressive), MA (moving average) and SETAR models with lower values of RSS. In both datasets MSW models provided a very good visual fit describing most of the extreme values. The results of this work could be used as a base for construction of other time series models used to describe or predict nitratenitrogen concentrations. and Štúdia sa zaoberá analýzou dlhých časových radov koncentrácií dusičnanového dusíka v rieke Ouse a Stour vo Východnom Anglicku. Časové rady priemerných mesačných koncentrácií dusičnanov boli rozložené na trendovú, sezónnu a cyklickú zložku a reziduá pripočítané k sebe a tvoriace jednoduchý aditívny model. Reziduá boli ďalej modelované zložitejšími lineárnymi modelmi reprezentovanými modelmi triedy ARMA a nelineárnymi viacrežimovými modelmi SETAR a MSW. Výsledky analýzy ukázali, že na základe minimálnej hodnoty sumy štvorcov reziduí (SSR) jednokrokovej predpovede, v oboch prípadoch SETAR aj MSW modely opísali časové rady lepšie ako modely triedy ARMA. Vo väčšine prípadov relatívne zlepšenie modelov SETAR oproti jednoduchým AR(1) modelom bolo malé v rozmedzí od 1 do 4 % s výnimkou trojrežimového modelu pre rieku Stour, kde to bolo až 48,9 %. Naopak, relatívne zlepšenie modelov MSW oproti AR(1) modelom bolo v rozmedzí 44,6 až 52,5 % pre dvojrežimové a 60,4 až 75 % pre trojrežimové modely. Vizuálne posúdenie jednotlivých modelov však ukázalo, že napriek vysokým hodnotám SSR, niektoré ARMA modely dokázali lepšie opísať dané časové rady ako modely AR, MA a SETAR s nižšími hodnotami SSR. V oboch prípadoch MSW modely dokázali dostatočne dobre opísať aj extrémne hodnoty oboch časových radov. Výsledky práce môžu byť použité pri tvorbe iných opisných alebo predpovedných modelov koncentrácie dusičnanového dusíka vo vodách.
The paper presents review of occurrence frequency of extreme hydrological events in a small agricultural basin in the flysh region over the period of 40 years (1964/65 - 2003/04). No human alterations were carried out in the basin over the period studied and hence influence of climatic changes on intensification of water cycle could be evaluated. Peaks over threshold (POT) method was applied separately to winter and summer hydrological events. In comparison with annual maximum series, all mean daily discharge values over a certain thresholds were taken into account for POT frequency analysis. The frequency of POT events has decreased in the past two decades (1984/85 - 1993/94 and 1994/95 - 2003/04). The results reveal that the most extreme values occurred in the 1964/65 - 1973/74 decade, mostly caused by summer rainfall. High event frequency also emerges in the 1974/75 - 1983/84 decade, especially in winter seasons as the consequence of snow melting. It is most likely that influence of climatic changes has not resulted yet in increase of occurrence frequency of POT events in the basin studied over the 40 years period. and Príspevok sa zaoberá frekvenciou výskytu extrémnych hydrologických udalostí na malom poľnohospodárskom povodí vo flyšovom pásme počas 40-ročnej periódy (1964/65-2003/04). Počas tohto obdobia nebolo povodie ovplyvnené významnými zmenami ľudskej činnosti a preto mohol byť zhodnotený vplyv klimatických zmien na intenzifikáciu hydrologického cyklu. POT metóda bola aplikovaná zvlášť pre zimné a letné hydrologické udalosti. V porovnaní so sériami ročných maxím, všetky priemerné denné prietoky nad určitou prahovou hodnotou boli zahrnuté do POT frekvenčných analýz. Frekvencia POT udalostí (nad zvolenou prahovou hodnotou) klesla v posledných dvoch dekádach (1984/85-1993/94 a 1994/95- 2003/04). Výsledky ukazujú, že najextrémnejšie hodnoty priemerných denných prietokov, spôsobené prevažne letnými prívalovými zrážkami sa objavili v dekáde 1964/65-1973/74. Vysoké hodnoty prietokov, spôsobené prevažne topením snehovej pokrývky sa vyskytli tiež v dekáde 1974/75-1983/84. Je nanajvýš pravdepodobné, že v študovanom povodí za obdobie 40-tich rokov klimatické zmeny nemali zatiaľ vplyv na zvyšovanie frekvencie extrémnych udalostí.
The paper contains a sensitivity analysis of the influence of uncertainties in input hydrological, morphological and operating data required for a proposal for active reservoir conservation storage capacity and its achieved values. By introducing uncertainties into the considered inputs of the water management analysis of a reservoir, the subsequent analysed reservoir storage capacity is also affected with uncertainties. The values of water outflows from the reservoir and the hydrological reliabilities are affected with uncertainties as well. A simulation model of reservoir behaviour has been compiled with this kind of calculation as stated below. The model allows evaluation of the solution results, taking uncertainties into consideration, in contributing to a reduction in the occurrence of failure or lack of water during reservoir operation in low-water and dry periods.
Time series of the daily total precipitation, daily wastewater discharges and daily concentrations and pollution loads of BOD5, COD, SS, N-NH4, Ntot and Ptot were analyzed at the inflow to the wastewater treatment plant (WWTP) for a larger city in 2004-2009 (WWTP is loaded by pollution from 435,000 equivalent inhabitants). The time series of the outflow from a WWTP was also available for 2007. The time series of daily total precipitation, daily wastewater discharges, concentrations and pollution loads at the inflow and outflow from the WWTP were standardized year by year to exclude a long-term trend, and periodic components with a period of 7 days and 365 days (and potentially also 186.5 days) were excluded from the standardized series. However, these two operations eliminated only a small part of the variance; there was a substantial reduction in the variance only for ammonium nitrogen and total nitrogen at the inflow and outflow from a WWTP. The relationship between the inflow into a WWTP and the outflow from a WWTP for the concentrations and pollution loads was described by simple transfer functions (SISO models) and more complicated transfer functions (MISO models). A simple transfer function (SISO model) was employed to describe the relationship between the daily total precipitation and the wastewater discharge.
In this paper, we deal with sentences containing time references like ''five years ago'', ''three years older'', ''in five seconds''. It turns out that such sentences are pragmatically incomplete, because there is an elliptic reference to a calendar that makes it possible to determine the length of the time interval associated with a time duration like a year, month, day, or to compute the time interval denoted by terms like ''February 29, 2016''. Since Transparent Intensional Logic (TIL) takes into account two modal parameters, namely possible worlds of type ω and times of type τ, and this system is particularly apt for the analysis of natural language expressions, our background theory is TIL. Within this system, we define time intervals, calendar time durations, and last but not least a method for adding and multiplying time durations in a way that takes into account the leap days and leap seconds. As sample applications, we analyse two sentences, to wit, ''A year has 365 days'' and ''Adam is 5 years older than Bill''. and V tomto článku se zabýváme věty obsahujícími časové odkazy jako ''před pěti lety'', ''o tři roky starší'', ''za pět sekund''. Ukazuje se, že takové věty jsou pragmaticky neúplné, protože existuje eliptický odkaz na kalendář, který umožňuje určit délku časového intervalu spojeného s časovým obdobím jako rok, měsíc, den nebo vypočítat časový interval označované slovy ''29. února 2016''. Vzhledem k tomu, že Transparentní Intenzivní Logika (TIL) zohledňuje dva modální parametry, jmenovitě možné světy typu ω a časy typu τ, a tento systém je obzvláště vhodný pro analýzu přirozených jazykových výrazů, je naší teorií pozadí TIL. V rámci tohoto systému definujeme časové intervaly, trvání kalendáře, a v neposlední řadě metoda pro přidání a násobení doby trvání způsobem, který bere v úvahu skokové a skokové sekundy. Jako vzorové aplikace analyzujeme dvě věty s názvem ''rok má 365 dní'' a ''Adam je o 5 let starší než Bill''.
This paper proposes a non-trivial definition of the notion of analytic method. Working within the so-called instructional model of method, I distinguish three kinds of instructions which occur in methods: selective, executive, and declarative instructions. I discuss the relation between each of these and the analyticity of a method. Then I define the notions of an analytic use of an instruction and of an analytic instruction, which are at the basis of the proposed definition of an analytic method. Finally, I discuss the issue of circularity in the presented model which arises if we consider a finite agent testing a method for analyticity., Tato práce navrhuje netriviální definici pojmu analytická metoda. V rámci tzv. Instruktážního modelu metody rozlišuji tři druhy instrukcí, které se vyskytují v metodách: selektivní, exekutivní a deklarativní . Diskutuji o vztahu mezi každou z nich a analytičnosti metody. Dále definuji pojmy analytického použití instrukce a analytické instrukce , které jsou základem navrhované definice analytické metody. Závěrem se zabývám otázkou kruhovitosti v prezentovaném modelu, která vzniká, pokud uvažujeme konečný agent testující metodu analyticity., and Miloš Kosterec
Study about the mechanical energy balance and the energy loss of 3-D turbulent flows in open-channels has its own complexities. The governing equation of the mechanical energy in turbulent flows has been previously known and includes turbulence parameters that their calculations or measurements are not easy. In this study, a form of the total mechanical energy equation that leads to a number of significant physical insights is analytically investigated, from which analytical relationships for the energy loss estimation in 3-D turbulent flows are defined. The effect of different turbulence parameters is reflected on the new relationships and analyzed by equalizations replacing unknown correlations with closure approximations using the numerical turbulence simulation. In order to investigate the application of the analytical relationships, numerical simulations are performed by using OpenFOAM software to solve the Navier-Stokes equations with the RSM turbulence model in open-channels with different geometries. Then, the contribution of the turbulence parameters to the total mechanical energy balance is evaluated in uniform and nonuniform turbulent flows and their difference is analyzed, that leads to identify the parameters affecting the friction and local losses. The results demonstrate that the magnitudes of the turbulent diffusion, the work done by the viscous stresses pertaining to the mean motion and the viscous diffusion of the turbulence energy are substantially smaller than the other terms of the total energy equation for turbulent flows in open-channels with different geometries, while the effect of the variations of the turbulence kinetic energy and the work done by the turbulence stresses, that has not been considered in the previous mechanical energy equations, is more important in complex flows. From a practical viewpoint, in order to study the details of the total mechanical energy balance and the energy loss in 3-D turbulent flows with the presence of the secondary currents, the proposed method can be useful.
Einstein-Barbarossa velocity or resistance equation (1952) is widely used to find resistance to flow in alluvial channel. In order to validate the equation in all ranges (smooth to rough); they introduced a correction factor based on the Nikuradse measurement. This correction factor is determined from the graphical method, which can be erroneous. Present work reanalyzes the Nikuradse measurements and gives an analytical formulation for the correction factor. and Einsteinova-Barbarossova rovnica (1952) sa často používa na určenie odporu voči prúdeniu v kanáloch. Autori do nej zaviedli korekčný faktor, založený na meraniach Nikuradzeho, aby overili platnosť rovnice v celom rozsahu drsností (od hladkých stien po drsné). Tento korekčný faktor sa určuje grafickou metódou, ktorá môže viesť k chybným výsledkom. V tejto práci sa znova analyzujú výsledky Nikuradzeho meraní a je navrhnutá analytická formulácia na výpočet korekčného faktora.
This paper presents closed form solution for unsteady flow equation corresponding to the transient hydraulic head, flow rate and volumetric exchange of a confined aquifer which is in contact with a constant piezometric head at one end and a stream whose water level is rising at a constant rate at the other end. The aquifer is also subjected to receive constant inflow due to rain infiltration. The unsteady groundwater flow equation is solved using Laplace transform to get analytical expressions for the transient hydraulic head and flow rate at the left and right interfaces and the net volumetric exchange of water at the aquifer-stream interface. The analytical results presented here show the effect of recharge due to rain infiltration on the net volumetric exchange and reveal the conditions for which net inflow in the aquifer could be positive, negative or zero. The results obtained have the capability to determine transient hydraulic head for two extreme scenarios: (i) very slow rise and (ii) very fast rise in the stream water. Analytical result show that the net volumetric exchange could be positive, zero or negative depending on the surface infiltration and stream water rise rate. and Príspevok obsahuje analytické riešenie rovnice neustáleného prúdenia vzhľadom na neustálenú hydraulickú výšku, rýchlosť prúdenia a objemové toky vo zvodnenom kolektore s napätou hladinou, ktorý je v kontakte s konštantnou piezometrickou výškou na jednej strane a s tokom s konštantne sa zvyšujúcou hladinou vody na strane druhej. Zvodnený kolektor je tiež napájaný konštantnou rýchlosťou infiltrovanou vodou zo zrážok. Rovnica neustáleného prúdenia podzemnej vody je riešená s použitím Laplaceovej transformácie, aby sme získali neustálenú tlakovú výšku na ľavej aj pravej strane a objemový prítok vody na rozhraní zvodnený kolektor - tok. Výsledky analytického riešenia, ktoré predkladáme, ukazujú vplyv infiltrácie zrážok na doplňovanie podzemnej vody a odhaľujú podmienky, za ktorých prítok do zvodneného kolektora môže byť kladný, negatívny, alebo nulový. Získané výsledky umožňujú určiť neustálené hydraulické výšky pre dva extrémne scenáre: (i) veľmi pomalé a (ii) veľmi rýchle zvýšenie hladiny vody v toku. Analytické riešenie ukazuje, že objem vody, ktorou je zvodnený kolektor doplňovaný, môže byť kladný, záporný, alebo nulový, v závislosti na intenzite infiltrácie a rýchlosti zvyšovania sa hladiny vody v toku.
An analytical solution for the two-dimensional tension leg platform (TLP) interacting with ocean wave is presented. The legs of TLP are considered as elastic springs. The flow is assumed to be irrotational and single-valued velocity potentials are defined. The effects of radiation and scattering are considered in the boundary value problem. Because of linear behavior of legs during wave excitation, ignoring coupling effects with other degrees of freedom, the analytical solution of heave response has good agreement with the real behavior of the structure. and Práce uvádí analytické řešení působení vln na dvoudimenzionální pevně ukotvenou plošinu (TLP). Úchyty plošiny jsou uvažovány jako elastické pružiny. Předpokládá se nevírový tok a je definováno jednoznačné rychlostní pole. Okrajové podmínky zahrnují vlivy radiace a rozptylu. Předpoklad lineárního chování úchytů při excitaci mořskými vlnami i zanedbání některých dalších efektů v analytickém řešení odezvy TLP na vznášení ukázaly, že existuje soulad mezi naším řešením a skutečným chováním konstrukce.