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732. Accretion disks in soft potential wells
- Creator:
- Duschl, Wolfgang J.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- astrophysics and accretion
- Language:
- Czech
- Description:
- The softer a potential is, the closer the corresponding Keplerian rotation is to a rigid rotation law. Because of the small radial coupling in such a situation the radial mass flow due to viscosity in an α-accretion disk is very inefficient. Here a model is presented in which the mass of an accretion disk in a soft potential well changes this potential in a sense that an efficient mass flow in radial direction becomes possible, thus making the formation of a centra! mass condensation possib!e. This mechanism is of interest in the context of galactic central regions since it is capable of explaining the existence of centra! masses such as observed in the cores of norma! galaxies; it might aiso be of relevance for the explanation of the activity in AGNs.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
733. Accuracy of ANN based day-ahead load forecasting in Turkish power system: degrading and improving factors
- Creator:
- Tanidir , Ö. and Tör, O. B.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- absolute percentage error, artificial neural networks, day aheadd load forecasting, mean absolute percentage error, secondary reserve, and sensitivity
- Language:
- English
- Description:
- This paper presents development of a day ahead load forecasting (DALF) model for Turkish power system with an artificial neural network (ANN). Effects of special holidays including national and religious days, and hourly random load deviations observed in Turkish power system due to significant arc furnace loads are discussed. Performance of the ANN is investigated in the sense of both DALF performance - in terms of both daily mean absolute percentage error (MAPE) and hourly absolute percentage error (APE) - and hourly secondary reserves required to ensure supply/demand adequacy of the system. The most sensitive cities to DALF in terms of daily city temperature forecasts are ranked in order to reduce the input of the developed ANN and thereby to improve execution of the model. Candidate cities are determined based on both their placement with respect to climatic zones of the country and their contribution to the system load during peak hours. The results show that, although a well-trained ANN could provide very satisfactory daily MAPEs at non-special days, such as ~1%, the hourly absolute percentage errors (APE) could be significant due to large random load disturbances, which necessitate special attention during the day ahead allocation of hourly secondary reserves. By limiting the temperature data set with major cities, the input of ANN reduces significantly while not disturbing the MAPEs. Main contributions of the study are; addressing both benefits of the prioritizing the cities in a power system in the sense of their temperature forecast effects on the DALF performance and assessing the performance of DALF in the sense of necessary amount of secondary reserves in power systems which include significant random load deviations (e.g., large arc furnace loads).
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
734. Accuracy of Earth gravity field models as a function of order of harmonic coefficients and a draft of laser geodynamic twin-satellite
- Creator:
- Klokočník, J.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- Earth gravity models, harmonic coefficients, and twin-satellite
- Language:
- Czech
- Description:
- The information on the accuracy of harmonic coefficients C1m, S1m as about a non-monotonic function of order m has been obtained from analysis of standard deviations of athe lumped coefficients compited from standart deviations of harmonic coefficients of various recent Earth gravity models as well as from resonant solutions for the individual orders. It is shown that the acuracy is lower for 8< m < 11 than for 12 < m < 15. A draft of new laser geodynamic twin-satellite is presented. The aim of the experiment, theoretical basis and suggestions to orbit selection - with ~8 to 11 revs. „day^-1 - are described; some comments to a possible design of the satellites and to their separation are also given.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
735. Accurate reduction of a model of circadian rhythms by delayed quasi-steady state assumptions
- Creator:
- Vejchodský, Tomáš
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- biochemical networks, gene regulatory networks, oscillating systems, periodic solutions, model reduction, and accurate approximation
- Language:
- English
- Description:
- Quasi-steady state assumptions are often used to simplify complex systems of ordinary differential equations in the modelling of biochemical processes. The simplified system is designed to have the same qualitative properties as the original system and to have a small number of variables. This enables to use the stability and bifurcation analysis to reveal a deeper structure in the dynamics of the original system. This contribution shows that introducing delays to quasi-steady state assumptions yields a simplified system that accurately agrees with the original system not only qualitatively but also quantitatively. We derive the proper size of the delays for a particular model of circadian rhythms and present numerical results showing the accuracy of this approach.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
736. Accusative resumptive pronoun in the Czech relative clauses with absolutive relativizer co
- Creator:
- Fried, Mirjam
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- relative clause, relativizer, resumptive pronoun, corpus analysis, vztažná věta, relativizátor, absolutní relativum, and korpusová analýza
- Language:
- Czech
- Description:
- This paper addresses the poorly understood patterning in the presence vs. absence of the accusative resumptive pronoun in the Czech relative clauses (RC) introduced by the absolutive relativizer co. Using both qualitative and frequency-based quantitative analysis, I investigate the distribution of the resumptive pronoun in authentic usage as attested in the Czech National Corpus. The study leads to the conclusion that the criteria that determine the distribution of the accusative resumptive pronoun go well beyond the traditionally invoked need for expressing agreement categories (gender, number) and grammatical relations (accusative object) or that the presence vs. absence of the pronoun should depend exclusively on the animacy of the relativized noun. Instead, the distribution appears to depend on the semantic compatibility between the relativized noun and the proposition expressed by the RC, reflecting a functional distinction between a determinative and non-determinative (explicative) interpretation of the RC; the former is unambiguously signaled by the bare relativizer co, the latter is available with the analytic co + resumptive pronounACC pattern as one of the interpretive options. and Článek se zabýv| problémem akuzativního z|jmena ve vztažných větách uvozených nesklonným co v češtině a hled| odpověď na dosud nezodpovězenou otázku, čím je v těchto větách přítomnost či nepřítomnost anaforického akuzativu podmíněna. Na základě kvalitativní i frekvenční analýzy korpusového materiálu docházíme k závěru, že korpus nijak nepotvrzuje tradičně postulovaná kritéria pro používání akuzativního zájmena, jimiž má být nutnost vyj|dřit gramatickou shodu s řídícím substantivem (v rodu a čísle) a gramatickou funkci ve vztažné větě (předmět) či role, kterou m| hr|t životnost řídícího substantiva (preferenční souvýskyt akuzativního z|jmena a neživotných substantiv). Rozbor autentického materi|lu naopak nasvědčuje tomu, že distribuce akuzativního z|jmena ve vztažných vět|ch s co je podmíněna sémantickou kompatibilitou mezi řídícím substantivem a propozičním obsahem vztažné věty, což se promítá do funkčního rozlišení mezi determinační a nedeterminační (explikativní) platností dané věty. Nepřítomnost anaforického akuzativu jednoznačně signalizuje funkci determinační, zatímco použití anaforického zájmena umožňuje obojí interpretaci.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
737. Acharňané: komoedie Aristofanova
- Creator:
- Aristofanés and Augustin Krejčí
- Publisher:
- Nákladem České akademie císaře Františka Josefa pro vědy, slovesnost a umění
- Format:
- print, svazek, and 88 stran.
- Type:
- model:monograph and TEXT
- Subject:
- Řecké antické drama, 821.14’02-2, (0:82-22), 25, and 821.14'02-2
- Language:
- Czech and Ancient Greek (to 1453)
- Description:
- přeložil Augustin Krejčí., KČSN (sg. S-N 398), and Obsahuje bibliografické odkazy
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
738. Achillova pata současné české antropologie. Obhajoba Lenky Budilové a Marka Jakoubka
- Creator:
- Hirt, Tomáš
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Language:
- Czech
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
739. Achromatic number of $K_5 \times K_n$ for small $n$
- Creator:
- Horňák, Mirko and Pčola, Štefan
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- complete vertex colouring, achromatic number, Cartesian product, and complete graph
- Language:
- English
- Description:
- The achromatic number of a graph $G$ is the maximum number of colours in a proper vertex colouring of $G$ such that for any two distinct colours there is an edge of $G$ incident with vertices of those two colours. We determine the achromatic number of the Cartesian product of $K_5$ and $K_n$ for all $n \le 24$.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
740. Acknowledgement to reviewers
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Language:
- English
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public