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Wyszukujesz frazę "estimates" wg kryterium: Temat


Tytuł:
A Comparison of Small Area and Calibration Estimators via Simulation
Autorzy:
Hidiroglou, Michael A.
Estevao, Victor M.
Powiązania:
https://bibliotekanauki.pl/articles/465930.pdf
Data publikacji:
2016
Wydawca:
Główny Urząd Statystyczny
Tematy:
area level
unit level
calibration estimates
small area estimates
simulation
Opis:
Domain estimates are typically obtained using calibration estimators that are direct or modified direct. They are direct if they strictly use data within the domain of interest. They are modified direct if they use both data within and outside the domain of interest. An alternative way of producing these estimates is through small area procedures. In this article, we compare the performance of these two approaches via a simulation. The population is generated using a hierarchical model that includes both area effects and unit level random errors. The population is made up of mutually exclusive domains of different sizes, ranging from a small number of units to a large number of units. We select many independent simple random samples of fixed size from the population and compute various estimates for each sample using the available auxiliary information. The estimates computed for the simulation included the Horvitz-Thompson estimator, the synthetic estimator (indirect estimate), calibration estimators, and unit level based estimators (small area estimate). The performance of these estimators is summarized based on their design- based properties
Źródło:
Statistics in Transition new series; 2016, 17, 1; 133-154
1234-7655
Pojawia się w:
Statistics in Transition new series
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
$L^p$-convergence of Bernstein-Kantorovich-type operators
Autorzy:
Campiti, Michele
Metafune, Giorgio
Powiązania:
https://bibliotekanauki.pl/articles/1311141.pdf
Data publikacji:
1996
Wydawca:
Polska Akademia Nauk. Instytut Matematyczny PAN
Tematy:
Kantorovich operators
quantitative estimates
Opis:
We study a Kantorovich-type modification of the operators introduced in [1] and we characterize their convergence in the $L^p$-norm. We also furnish a quantitative estimate of the convergence.
Źródło:
Annales Polonici Mathematici; 1996, 63, 3; 273-280
0066-2216
Pojawia się w:
Annales Polonici Mathematici
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On the maximal function for rotation invariant measures in $ℝ^{n}$
Autorzy:
Vargas, Ana M.
Powiązania:
https://bibliotekanauki.pl/articles/1290316.pdf
Data publikacji:
1994
Wydawca:
Polska Akademia Nauk. Instytut Matematyczny PAN
Tematy:
maximal operators
weak type estimates
Opis:
Given a positive measure μ in $ℝ^n$, there is a natural variant of the noncentered Hardy-Littlewood maximal operator $M_{μ}f(x) = sup_{x ∈ B} 1/μ(B) ʃ_{B} |f|dμ$, where the supremum is taken over all balls containing the point x. In this paper we restrict our attention to rotation invariant, strictly positive measures μ in $ℝ^n$. We give some necessary and sufficient conditions for $M_μ$ to be bounded from $L^{1}(dμ)$ to $L^{1,∞}(dμ)$.
Źródło:
Studia Mathematica; 1994, 110, 1; 9-17
0039-3223
Pojawia się w:
Studia Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Inverse/observability estimates for Schroedinger equations with variable coefficients
Autorzy:
Triggiani, R.
Yao, P.
Powiązania:
https://bibliotekanauki.pl/articles/206775.pdf
Data publikacji:
1999
Wydawca:
Polska Akademia Nauk. Instytut Badań Systemowych PAN
Tematy:
równanie Schroedingera
Carleman estimates
exact controllability
inverse/observability estimates
Riemannian manifold
Schroedinger equation
Opis:
We consider a general Schroedinger equation defined on an open bounded domain [Omega is a subset of R^n] with variable coefficients in both the elliptic principal part and in the first-order terms as well. At first, no boundary conditions (B.C.) are imposed. Our main result (Theorem 3.5) is a reconstruction, or inverse, estimate for solutions w: under checkable conditions on the coefficients of the principal part, the H[sup l](Omega)-energy at time t = T, or at time t = 0, is dominated by the L[sub2](Sigma)-norms of the boundary traces [...] and w[sub t] modulo an interior lower-order term. Once homogeneous B.C. are imposed, our results yield - under a uniqueness theorem, needed to absorb the lower order term - continuous observability estimates for both the Dirichlet and Neumann case, with an arbitrarily short observability time ; hence, by duality, exact controllability results. Moreover, no artificial geometrical conditions are imposed on the controlled part of the boundary in the Neuman case. In contrast to existing literature, the first step of our method employs a Riemann geometry approach to reduce the original variable coefficient principal part problem in [Omega is a subset of R^n] to a problem on an appropriate Riemannian manifold (determined by the coefficients of the principal part), where the principal part is the Laplacian. In our second step, we employ explicit Carleman estimates at the differential level to take care of the va.riable first-order (energy level) terms. In our third step, we employ micro-local analysis yielding a sharp trace estimate to remove artificial geometrical conditions on the controlled part of the boundary in the Neumann case.
Źródło:
Control and Cybernetics; 1999, 28, 3; 627-664
0324-8569
Pojawia się w:
Control and Cybernetics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
New estimate for the curvature of an order-convex set and related questions
Autorzy:
Ramazanov, Ali B.
Powiązania:
https://bibliotekanauki.pl/articles/2050043.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Instytut Badań Systemowych PAN
Tematy:
gradient
estimates
curvature
convexity
algorithm
Opis:
It is well known that in discrete optimization problems, gradient (local) algorithms do not always guarantee an optimal solution. Therefore, the problem arises of finding the accuracy of the gradient algorithm. This is a fairly well-known problem and numerous publications have been devoted to it. In establishing accuracy, various approaches are used. One of these approaches is to obtain guaranteed estimates of the accuracy of the gradient algorithm in terms of the curvature of the admissible domain. With this approach, it is required to find the curvatures of the admissible region. Since finding the exact value of curvature is a difficult problem to solve, curvature estimates in terms of more or less simply calculated parameters of the problem are relevant. A new improved bound for the curvature of an order-convex set is found and is presented in this paper in terms of the steepness and parameters of strict convexity of the function.
Źródło:
Control and Cybernetics; 2020, 49, 2; 233-240
0324-8569
Pojawia się w:
Control and Cybernetics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Dispersion estimates for spherical Schrödinger equations: the effect of boundary conditions
Autorzy:
Holzleitner, M.
Kostenko, A.
Teschl, G.
Powiązania:
https://bibliotekanauki.pl/articles/255331.pdf
Data publikacji:
2016
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
Schrödinger equation
dispersive estimates
scattering
Opis:
We investigate the dependence of the [formula] dispersive estimates for one-dimensional radial Schrödinger operators on boundary conditions at 0. In contrast to the case of additive perturbations, we show that the change of a boundary condition at zero results in the change of the dispersive decay estimates if the angular momentum is positive, l ∈ (0,1/2). However, for nonpositive angular momenta, l ∈ (—1/2,0], the standard [formula] decay remains true for all self-adjoint realizations.
Źródło:
Opuscula Mathematica; 2016, 36, 6; 769-786
1232-9274
2300-6919
Pojawia się w:
Opuscula Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The use of Estimated Values to Implement yhe "Big Bath" Strategy During the COVID-19 Pandemic on the Exanple of Selected Enterprise
Autorzy:
Białas, Małgorzata
Powiązania:
https://bibliotekanauki.pl/articles/17838831.pdf
Data publikacji:
2022
Wydawca:
Instytut Naukowo-Wydawniczy "SPATIUM"
Tematy:
big bath
accounting estimates
Covid-19
Opis:
The big bath strategy applies to a situation when enterprises intentionally show large losses in order to be able to boast a high profit in the next period. They often use estimates for this purpose. The aim of the paper is to check how often the chosen companies have used the Covid-19 pandemic to implement the big bath strategy in 2020.
Źródło:
Central European Review of Economics & Finance; 2022, 36, 1; 5-20
2082-8500
2083-4314
Pojawia się w:
Central European Review of Economics & Finance
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An exponential estimate for convolution powers
Autorzy:
Jones, Roger L.
Powiązania:
https://bibliotekanauki.pl/articles/1216222.pdf
Data publikacji:
1999
Wydawca:
Polska Akademia Nauk. Instytut Matematyczny PAN
Tematy:
maximal functions
exponential estimates
convolution powers
Opis:
We establish an exponential estimate for the relationship between the ergodic maximal function and the maximal operator associated with convolution powers of a probability measure.
Źródło:
Studia Mathematica; 1999, 137, 2; 195-202
0039-3223
Pojawia się w:
Studia Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Some eigenvalue estimates for wavelet related Toeplitz operators
Autorzy:
Nowak, Krzysztof
Powiązania:
https://bibliotekanauki.pl/articles/967338.pdf
Data publikacji:
1993
Wydawca:
Polska Akademia Nauk. Instytut Matematyczny PAN
Tematy:
Schrödinger representation
eigenvalue estimates
Toeplitz operators
Opis:
By a straightforward computation we obtain eigenvalue estimates for Toeplitz operators related to the two standard reproducing formulas of the wavelet theory. Our result extends the estimates for Calderón-Toeplitz operators obtained by Rochberg in [R2]. In the first section we recall two standard reproducing formulas of the wavelet theory, we define Toeplitz operators and discuss some of their properties. The second section contains precise statements of our results and their proofs. At the end of the second section we include some comments about the range of applicability of our estimates.
Źródło:
Colloquium Mathematicum; 1993, 65, 1; 149-156
0010-1354
Pojawia się w:
Colloquium Mathematicum
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Biomass estimates of commercial fishes in the South Georgia region (by "swept area" method)
Autorzy:
Mucha, Mirosław
Powiązania:
https://bibliotekanauki.pl/articles/2057457.pdf
Data publikacji:
1984
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Antarctic
South Georgia
commercial fishes estimates
Źródło:
Polish Polar Research; 1984, 5, 1-2; 107-111
0138-0338
2081-8262
Pojawia się w:
Polish Polar Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Convergence results for unbounded solutions of first order non-linear differential-functional equations
Autorzy:
Leszczyński, Henryk
Powiązania:
https://bibliotekanauki.pl/articles/1311094.pdf
Data publikacji:
1996
Wydawca:
Polska Akademia Nauk. Instytut Matematyczny PAN
Tematy:
error estimates
recurrence inequalities
difference scheme
Opis:
We consider the Cauchy problem in an unbounded region for equations of the type either $D_{t}z(t,x) = f(t,x,z(t,x),z_{(t,x)},D_{x}z(t,x))$ or $D_{t}z(t,x)= f(t,x,z(t,x),z,D_{x}z(t,x))$. We prove convergence of their difference analogues by means of recurrence inequalities in some wide classes of unbounded functions.
Źródło:
Annales Polonici Mathematici; 1996, 64, 1; 1-16
0066-2216
Pojawia się w:
Annales Polonici Mathematici
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Estimates of \(L_p\) norms for sums of positive functions
Autorzy:
Kayumov, Ilgiz
Powiązania:
https://bibliotekanauki.pl/articles/747077.pdf
Data publikacji:
2013
Wydawca:
Uniwersytet Marii Curie-Skłodowskiej. Wydawnictwo Uniwersytetu Marii Curie-Skłodowskiej
Tematy:
Simple partial fractions
\(L_p\) estimates.
Opis:
We present new inequalities of \(L_p\) norms for sums of positive functions. These inequalities are useful for investigation of convergence of simple partial fractions in \(L_p(\mathbb{R})\).
Źródło:
Annales Universitatis Mariae Curie-Skłodowska, sectio A – Mathematica; 2013, 67, 2
0365-1029
2083-7402
Pojawia się w:
Annales Universitatis Mariae Curie-Skłodowska, sectio A – Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A note on the strong consistency of least squares estimates
Autorzy:
da Silva, Joǎo
Powiązania:
https://bibliotekanauki.pl/articles/729980.pdf
Data publikacji:
2009
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
least squares estimates
linear models
strong consistency
Opis:
The strong consistency of least squares estimates in multiples regression models with i.i.d. errors is obtained under assumptions on the design matrix and moment restrictions on the errors.
Źródło:
Discussiones Mathematicae Probability and Statistics; 2009, 29, 2; 223-231
1509-9423
Pojawia się w:
Discussiones Mathematicae Probability and Statistics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Existence results and a priori estimates for solutions of quasilinear problems with gradient terms
Autorzy:
Filippucci, Roberta
Lini, Chiara
Powiązania:
https://bibliotekanauki.pl/articles/255859.pdf
Data publikacji:
2019
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
existence result
quasilinear problems
a priori estimates
Opis:
In this paper we establish a priori estimates and then an existence theorem of positive solutions for a Dirichlet problem on a bounded smooth domain in [formula] with a nonlinearity involving gradient terms. The existence result is proved with no use of a Liouviiie theorem for the limit problem obtained via the usual blow up method, in particular we refer to the modified version by Ruiz. In particular our existence theorem extends a result by Lorca and Ubilla in two directions, namely by considering a nonlinearity which includes in the gradient term a power of u and by removing the growth condition for the nonlinearity ∫ at u = 0.
Źródło:
Opuscula Mathematica; 2019, 39, 2; 195-205
1232-9274
2300-6919
Pojawia się w:
Opuscula Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Pseudospectral method for semilinear partial functional differential equations
Autorzy:
Czernous, W.
Powiązania:
https://bibliotekanauki.pl/articles/255893.pdf
Data publikacji:
2010
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
pseudospectral collocation
CFS condition
convergence
error estimates
Opis:
We present a convergence result for two spectral methods applied to an initial boundary value problem with functional dependence of Volterra type. Explicit condition of Courant-Friedrichs-Levy type is assumed on time step τ and the number N of collocation points. Stability statements and error estimates are written using continuous norms in weighted Jacobi spaces.
Źródło:
Opuscula Mathematica; 2010, 30, 2; 133-145
1232-9274
2300-6919
Pojawia się w:
Opuscula Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Galerkin proper orthogonal decomposition methods for parameter dependent elliptic systems
Autorzy:
Kahlbacher, Martin
Volkwein, Stefan
Powiązania:
https://bibliotekanauki.pl/articles/729447.pdf
Data publikacji:
2007
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
proper orthogonal decomposition
elliptic equations
error estimates
Opis:
Proper orthogonal decomposition (POD) is a powerful technique for model reduction of linear and non-linear systems. It is based on a Galerkin type discretization with basis elements created from the system itself. In this work, error estimates for Galerkin POD methods for linear elliptic, parameter-dependent systems are proved. The resulting error bounds depend on the number of POD basis functions and on the parameter grid that is used to generate the snapshots and to compute the POD basis. The error estimates also hold for semi-linear elliptic problems with monotone nonlinearity. Numerical examples are included.
Źródło:
Discussiones Mathematicae, Differential Inclusions, Control and Optimization; 2007, 27, 1; 95-117
1509-9407
Pojawia się w:
Discussiones Mathematicae, Differential Inclusions, Control and Optimization
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Norm estimates for solutions of matrix equations AX-XB=C and X-AXB=C
Autorzy:
Gil', Michael
Powiązania:
https://bibliotekanauki.pl/articles/729497.pdf
Data publikacji:
2014
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
matrix equations
norm estimates
perturbations
invariant subspaces
Opis:
Let A, B and C be matrices. We consider the matrix equations Y-AYB=C and AX-XB=C. Sharp norm estimates for solutions of these equations are derived. By these estimates a bound for the distance between invariant subspaces of matrices is obtained.
Źródło:
Discussiones Mathematicae, Differential Inclusions, Control and Optimization; 2014, 34, 2; 191-206
1509-9407
Pojawia się w:
Discussiones Mathematicae, Differential Inclusions, Control and Optimization
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Even coefficient estimates for bounded univalent functions
Autorzy:
Prokhorov, D.
Powiązania:
https://bibliotekanauki.pl/articles/1311781.pdf
Data publikacji:
1993
Wydawca:
Polska Akademia Nauk. Instytut Matematyczny PAN
Tematy:
coefficient estimates
univalent function
Pick function
Koebe function
Opis:
Extremal coefficient properties of Pick functions are proved. Even coefficients of analytic univalent functions f with |f(z)| < M, |z| < 1, are bounded by the corresponding coefficients of the Pick functions for large M. This proves a conjecture of Jakubowski. Moreover, it is shown that the Pick functions are not extremal for a similar problem for odd coefficients.
Źródło:
Annales Polonici Mathematici; 1993, 58, 3; 267-273
0066-2216
Pojawia się w:
Annales Polonici Mathematici
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Quantifying the uncertainty in the ultimate recoverable oil reserves using the Monte Carlo simulation techniques from ‘OWA’ Marginal Field, Onshore Niger Delta, Nigeria
Autorzy:
Adeigbe, O. C.
Odedere, I. F.
Amodu, O. I.
Powiązania:
https://bibliotekanauki.pl/articles/184699.pdf
Data publikacji:
2018
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
marginal field
EUR
Monte Carlo
stochastic estimates
reserve
Opis:
A review on the development of marginal oil fields in Nigeria has now become an important strategic issue if it is to remain amongst the top producers in the global market, and these fields are vast, available all over the Niger Delta. One of the factors that makes a field marginal is the size of its reserves. Stochastic estimation gives a certainty in terms of the possible number of outcomes within the range of input parameters. In this work, four (4) deviated wells and 3D seismic volume (362 inlines and 401 traces) were interpreted for the evaluation of the field. The petrophysical evaluations were interpreted using the Power Log software and the Seismic, Geographix and Petrel softwares. Stochastic reserve estimation was done using Monte Carlo sampling techniques and subjected to uncertainty quantification using the Crystal Ball software by varying distributions and measuring sensitivity impact on the overall reserves. The production profile was predicted based on some assumptions and history matching which result in the overall Expected Ultimate Recovery (EUR). The petrophysical analysis shows the reservoirs to be within the unconsolidated continental Benin Formation denoted as ‘Intra-Benin’ sands, an unconventional reservoir as supposed the normal reservoir rocks within the Agbada Formation. This indicated high porosity (0.28), water resistivity (7 Ω∙m), and water saturation and also inferred Heavy Oil (low API). Nine hydrocarbon sands were identified but only three (B1, D and E), representing shallow, mid and deep reservoirs were further evaluated. 1P and 2P reserve estimates were 4.8 MMBO and 5.7 MMBO for B1; 15.2 MMMscf and 16.4 MMMscf for D; 8.4 MMMscf and 8.8 MMMscf for E respectively. The Monte Carlo simulation of 1,000,000 trials with mainly triangular distribution assumption generated P10, P50, P90 were 6.5 MMBO, 5.6 MMBO and 4.4 MMBO for B1; 17.5 MMMscf, 13.7 MMMscf and 10.8 MMMscf for D; 10.4 MMMscf, 8 MMMscf and 6.1 MMMscf for E respectively. The sensitivity impact of the input parameters were estimated and ranked, and the coefficient of variability ranges within 15% to 20% for the reservoirs indicating that there is a very low level uncertainty of reserve estimation around the P10, P50 and P90 percentiles which could be positive for investment decisions. ‘OWA’ marginal field reflects a typical low reserve (EUR) category found within the Niger Delta basin.
Źródło:
Geology, Geophysics and Environment; 2018, 44, 4; 401-412
2299-8004
2353-0790
Pojawia się w:
Geology, Geophysics and Environment
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Record data from Kies distribution and related statistical inferences
Autorzy:
Al-Olaimat, Nesreen M.
Bayoud, Husam A.
Raqab, Mohammad Z.
Powiązania:
https://bibliotekanauki.pl/articles/1917056.pdf
Data publikacji:
2021-12-08
Wydawca:
Główny Urząd Statystyczny
Tematy:
Bayesian estimates
Kies distribution
maximum likelihood estimation
records
Opis:
The Kies probability model was proposed as an alternative to the extendedWeibull models as it provides a more efficient fit to some real-life data sets in comparison to the aforementioned models. The paper proposes classical and Bayesian inferences for the Kies distribution based on records. Maximum likelihood estimates are studied jointly with asymptotic and bootstrap confidence intervals. Moreover, Bayes estimates, along with credible intervals are discussed assuming squared and LINEX loss functions. The proposed estimation methods have been investigated and compared via simulation studies. A real data set has been analysed for illustrative purposes.
Źródło:
Statistics in Transition new series; 2021, 22, 4; 153-170
1234-7655
Pojawia się w:
Statistics in Transition new series
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Wage Flexibility across EMU Members: How Endogenous is the Currency Union?
Autorzy:
Buscher, Herbert
Gabrisch, Hubert
Powiązania:
https://bibliotekanauki.pl/articles/659699.pdf
Data publikacji:
2010
Wydawca:
Uniwersytet Łódzki. Wydawnictwo Uniwersytetu Łódzkiego
Tematy:
convergence
wage dynamics
European Union
cross section estimates
Opis:
Abstract. The authors test whether the introduction of a common currency and the single monetary policy in the European Monetary Union might have increased the need for nominal wage flexibility. They try to find out whether wage dynamics between euro member countries became more synchronized through the adoption of the common currency. They run a model of endogenously induced changes of bilateral correlation coefficients of wage dynamics, where trade intensity, sector specialization and financial integration are assumed to be the driving forces for endogeneity on the labor markets. They use a panel data structure to allow for cross-section weights for country-pair observations. Regressions are with instrument variables in order to disentangle exogenous from endogenous influences. They apply these techniques to the dynamics of nominal wages, real wages and unit labor costs. They find evidence of persistent asymmetries in nominal wage formation, despite a single currency and monetary policy, which is responsible for diverging unit labor costs and emerging trade imbalances among the EMU member countries.
Źródło:
Acta Universitatis Lodziensis. Folia Oeconomica; 2010, 241
0208-6018
2353-7663
Pojawia się w:
Acta Universitatis Lodziensis. Folia Oeconomica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ukraińscy migranci zarobkowi w Polsce – dlaczego tak trudno ich policzyć?
Ukrainian labour migrants in Poland. Why is it so difficult to count them?
Autorzy:
Brunarska, Zuzanna
Powiązania:
https://bibliotekanauki.pl/articles/14727498.pdf
Data publikacji:
2014
Wydawca:
Kancelaria Sejmu. Biuro Analiz Sejmowych
Tematy:
labour migration
migration
Polska
numerical estimates
Ukrainians
migration pattern
Opis:
The article discusses the characteristics of the Ukrainian labour migration to Poland. The author tries to answer the question of why it is so difficult to estimate the actual number of Ukrainians working in Poland. The first section provides a brief overview of available data and estimates. The following sections focus on selected elements of the migration patterns which cause difficulties in estimating the size of the population of Ukrainian workers. The analyses concern, inter alia, the imperfection of the system of employers’ declarations, alternative channels of legalization of stay, the temporality of migration, preferred job search and remittances sending methods, and the specificity of the main sectors of employment.
Źródło:
Studia BAS; 2014, 4(40); 155-174
2080-2404
2082-0658
Pojawia się w:
Studia BAS
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Processes in Transborder Areas – Significant Impact on the Economic Growth
Autorzy:
Cierpiał-Wolan, Marek
Powiązania:
https://bibliotekanauki.pl/articles/465804.pdf
Data publikacji:
2014
Wydawca:
Główny Urząd Statystyczny
Tematy:
research system for transborder areas
improvement in GDP estimates
Opis:
Dynamics and interdependence of socio-economic phenomena in the contemporary world require the appropriate instruments to be developed to monitor them. This becomes especially evident in the case of transborder areas, which are differentiated in terms of the socio-economic potentials, on the one hand, along with a growing gap in the data system for transborder areas, on the other. Therefore, it seems to be essential (especially in countries in transition) to create a coherent research system that collects, processes and disseminates information for such areas. Recognizing these needs, the Polish official statistics has initiated works towards establishing a suitable infrastructure. The results of this research (based on household surveys, border traffic surveys, entrepreneurship surveys, etc.) have shown, rather unexpectedly, that estimates of some items in Balance of Payment (BoP) are being changed. Consequently, they should be taken into account in the calculation of Gross Domestic Product (GDP), as discussed in this article.
Źródło:
Statistics in Transition new series; 2014, 15, 3; 399-428
1234-7655
Pojawia się w:
Statistics in Transition new series
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Global existence for strong solutions of viscous Burgers equation. (1) The bounded case
Autorzy:
Unterberger, J.
Powiązania:
https://bibliotekanauki.pl/articles/206077.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Instytut Badań Systemowych PAN
Tematy:
viscous Burgers equation
conservation laws
maximum principle
Schauder estimates
Opis:
We prove that the viscous Burgers equation (∂t−∆)u(t, x)+( u •∇)u(t, x) = g(t, x), (t, x) ∈ R+ × Rd (d ≥ 1) has a globally defined smooth solution in all dimensions provided the initial condition and the forcing term g are smooth and bounded together with their derivatives. Such solutions may have infinite energy. The proofdoes not rely on energy estimates, but on a combinationof the maximumprinciple and quantitative Schauder estimates. We obtain precise bounds on the sup norm of the solution and its derivatives, making it plain that there is no exponential increase in time. In particular, these bounds are time-independent if g is zero. To get a classical solution, it suffices to assume that the initial condition and the forcing term have bounded derivatives up to order two.
Źródło:
Control and Cybernetics; 2017, 46, 2; 109-136
0324-8569
Pojawia się w:
Control and Cybernetics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Existence, uniqueness and ergodicity for the stochastic quantization equation
Autorzy:
Gątarek, Dariusz
Gołdys, Beniamin
Powiązania:
https://bibliotekanauki.pl/articles/1287572.pdf
Data publikacji:
1996
Wydawca:
Polska Akademia Nauk. Instytut Matematyczny PAN
Tematy:
Wick powers
Nelson estimates
stochastic quantization
stationary measure
ergodicity
Opis:
Existence, uniqueness and ergodicity of weak solutions to the equation of stochastic quantization in finite volume is obtained as a simple consequence of the Girsanov theorem.
Źródło:
Studia Mathematica; 1996, 119, 2; 179-193
0039-3223
Pojawia się w:
Studia Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Prezentacja informacji o założeniach, osądach i szacunkach w sprawozdaniach finansowych – przegląd i ocena rozwiązań stosowanych przez największe spółki giełdowe w Polsce
Reporting on Accounting Estimates, Assumptions and Discretionary Judgements in Financial Statements – Review of Solutions Used by the Largest Public Companies in Poland
Autorzy:
Klimczak, Katarzyna
Powiązania:
https://bibliotekanauki.pl/articles/597023.pdf
Data publikacji:
2016
Wydawca:
Łódzkie Towarzystwo Naukowe
Tematy:
założenia
osądy
szacunki
sprawozdanie finansowe
assumptions
estimates
judgements
financial statements
Opis:
W artykule przedstawiono wyniki badania poświęconego raportowaniu na temat założeń, osądów i szacunków w sprawozdaniach finansowych spółek wchodzących w skład indeksu WIG-20. Celem badania była analiza sposobu i zakresu prezentacji informacji w rocznych sprawozdaniach finansowych. W ramach badania analizie poddano miejsce prezentacji informacji, zawartość wstępnej informacji o oszacowaniach i osądach oraz zakres i jakość prezentowanej informacji na temat zidentyfikowanych obszarów osądów i szacunków w sprawozdaniach finansowych. Z przeprowadzonego badania wynika, że we wszystkich przeanalizowanych sprawozdaniach finansowych uwzględniono informacje na temat szacunków oraz osądów przyjmowanych na potrzeby ich sporządzenia. Spółki prezentują bardzo ogólne i podobne wstępne informacje na temat szacunków i osądów. Podobne obszary są uznawane za szczególnie podlegające osądom i szacunkom przez większość spółek, jednak są one wyodrębniane w sprawozdaniach finansowych z różną szczegółowością. Opisy zidentyfikowanych obszarów osądów i szacunków prezentowane przez spółki są zróżnicowane – zarówno pod względem objętości, jak i jakości.
The article presents the results of the research devoted to reporting on accounting estimates, assumptions and discretionary judgements in financial statements by public companies listed on Warsaw Stock Exchange. The aim of the research was the analysis of the scope and content of disclosures in consolidated annual reports. The analysis included the place of presentation of information, the contents of the preliminary information on the estimates and judgments and the scope and quality of the presented information on identified areas of judgments and estimates in the financial statements. The results of the research indicate that all financial reports included information on the estimates and judgments made for the purpose of the their preparation. Companies present a very general and similar preliminary information on estimates and judgments. Similar areas are considered particularly subject to judgments and estimates by the majority of companies, however, they presented in more detail by some companies than the others. Descriptions of the identified areas of judgments and estimates presented by the company are diverse – both in terms of scope and quality.
Źródło:
Studia Prawno-Ekonomiczne; 2016, CI; 255-271
0081-6841
Pojawia się w:
Studia Prawno-Ekonomiczne
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Estimates of some probabilities in multidimensional convex records
Autorzy:
Kałuszka, Marek
Powiązania:
https://bibliotekanauki.pl/articles/1340347.pdf
Data publikacji:
1995
Wydawca:
Polska Akademia Nauk. Instytut Matematyczny PAN
Tematy:
estimates of probabilities
geometric probability
convex records in Euclidean space
Opis:
Convex records in Euclidean space are considered. We provide both lower and upper bounds on the probability $p_n(k)$ that in a sequence of random vectors $X_1$,..., $X_n$ there are exactly k records.
Źródło:
Applicationes Mathematicae; 1995-1996, 23, 1; 1-11
1233-7234
Pojawia się w:
Applicationes Mathematicae
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On the fully discrete approximations of the MGT two-temperatures thermoelastic problem
Autorzy:
Baldonedo, J.
Fernández, J. R.
Quintanilla, R.
Powiązania:
https://bibliotekanauki.pl/articles/38695700.pdf
Data publikacji:
2022
Wydawca:
Instytut Podstawowych Problemów Techniki PAN
Tematy:
two-temperatures thermoelasticity
finite elements
priori error estimates
numerical simulations
Opis:
We consider a one-dimensional two-temperatures thermoelastic model. The corresponding variational problem leads to a coupled system which is written in terms of the mechanical velocity, the temperature speed and the inductive temperature. An existence and uniqueness result is recalled. Then, fully discrete approximations are introduced by using the finite element method and the implicit Euler scheme. A priori error estimates are proved and the linear convergence of the approximations is deduced under suitable additional regularity conditions. Finally, some numerical simulations are shown to demonstrate the accuracy of the proposed algorithm and the behavior of the discrete energy.
Źródło:
Archives of Mechanics; 2022, 74, 5; 391-407
0373-2029
Pojawia się w:
Archives of Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Uniqueness of solutions of a generalized Cauchy problem for a system of first order partial functional differential equations
Autorzy:
Netka, M.
Powiązania:
https://bibliotekanauki.pl/articles/952848.pdf
Data publikacji:
2009
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
functional differential equations
comparison methods
nonlinear estimates of Perron type
Opis:
The paper is concerned with weak solutions of a generalized Cauchy problem for a nonlinear system of first order differential functional equations. A theorem on the uniqueness of a solution is proved. Nonlinear estimates of the Perron type are assumed. A method of integral functional inequalities is used.
Źródło:
Opuscula Mathematica; 2009, 29, 1; 69-79
1232-9274
2300-6919
Pojawia się w:
Opuscula Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Surrogate and clinical endpoints for studies in peripheral artery occlusive disease: Are statistics the brakes?
Autorzy:
Waliszewski, Matthias W
Redlich, Ulf
Breul, Victor
Tautenhahn, Jörg
Powiązania:
https://bibliotekanauki.pl/articles/1393189.pdf
Data publikacji:
2017
Wydawca:
Index Copernicus International
Tematy:
peripheral artery occlusive disease
clinical endpoints
surrogate endpoints
biometric estimates
Opis:
Background: The aim of this review is to present the available clinical and surrogate endpoints that may be used in future studies performed in patients with peripheral artery occlusive disease (PAOD). Importantly, we describe statistical limitations of the most commonly used endpoints and offer some guidance with respect to study design for a given sample size. The proposed endpoints may be used in studies using surgical or interventional revascularization and/or drug treatments. Methods: Considering recently published study endpoints and designs, the usefulness of these endpoints for reimbursement is evaluated. Based on these potential study endpoints and patient sample size estimates with different non-inferiority or tests for difference hypotheses, a rating relative to their corresponding reimbursement values is attempted. Results: As regards the benefit for the patients and for the payers, walking distance and the ankle brachial index (ABI) are the most feasible endpoints in a relatively small study samples given that other non-vascular impact factors can be controlled. Angiographic endpoints such as minimal lumen diameter (MLD) do not seem useful from a reimbursement standpoint despite their intuitiveness. Other surrogate endpoints, such as transcutaneous oxygen tension measurements, have yet to be established as useful endpoints in reasonably sized studies with patients with critical limb ischemia (CLI). Conclusions: From a reimbursement standpoint, WD and ABI are effective endpoints for a moderate study sample size given that non-vascular confounding factors can be controlled.
Źródło:
Polish Journal of Surgery; 2017, 89, 2; 39-48
0032-373X
2299-2847
Pojawia się w:
Polish Journal of Surgery
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Some remarks on the coincidence set for the Signorini problem
Autorzy:
Benito Delgado de, Miguel
Diaz, Jesus Ildefonso
Powiązania:
https://bibliotekanauki.pl/articles/255769.pdf
Data publikacji:
2019
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
Signorini problem
coincidence set
location estimates
free boundary problem
contact problems
Opis:
We study some properties of the coincidence set for the boundary Signorini problem, improving some results from previous works by the second author and collaborators. Among other new results, we show here that the convexity assumption on the domain made previously in the literature on the location of the coincidence set can be avoided under suitable alternative conditions on the data.
Źródło:
Opuscula Mathematica; 2019, 39, 2; 145-157
1232-9274
2300-6919
Pojawia się w:
Opuscula Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A note on variational discretization of elliptic Neumann boundary control
Autorzy:
Hinze, M.
Matthes, U.
Powiązania:
https://bibliotekanauki.pl/articles/969695.pdf
Data publikacji:
2009
Wydawca:
Polska Akademia Nauk. Instytut Badań Systemowych PAN
Tematy:
elliptic optimal control problem
error estimates
Neumann boundary control
variational discretization
Opis:
We consider variational discretization of Neumann-type elliptic optimal control problems with constraints on the control. In this approach the cost functional is approximated by a sequence of functionals, which are obtained by discretizing the state equation with the help of linear finite elements. The control variable is not discretized. Error bounds for control and state are obtained both in two and three space dimensions. Finally, we discuss some implementation issues of a generalized Newton method applied to the numerical solution of the problem class under consideration.
Źródło:
Control and Cybernetics; 2009, 38, 3; 577-591
0324-8569
Pojawia się w:
Control and Cybernetics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Error estimates for the finite element discretization of semi-infinite elliptic optimal control problems
Autorzy:
Merino, Pedro
Neitzel, Ira
Tröltzsch, Fredi
Powiązania:
https://bibliotekanauki.pl/articles/729230.pdf
Data publikacji:
2010
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
elliptic optimal control problem
state constraints
error estimates
finite element discretization
Opis:
In this paper we derive a priori error estimates for linear-quadratic elliptic optimal control problems with finite dimensional control space and state constraints in the whole domain, which can be written as semi-infinite optimization problems. Numerical experiments are conducted to ilustrate our theory.
Źródło:
Discussiones Mathematicae, Differential Inclusions, Control and Optimization; 2010, 30, 2; 221-236
1509-9407
Pojawia się w:
Discussiones Mathematicae, Differential Inclusions, Control and Optimization
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Singular quasilinear convective systems involving variable exponents
Autorzy:
Moussaoui, Abdelkrim
Nabab, Dany
Vélin, Jean
Powiązania:
https://bibliotekanauki.pl/articles/29519640.pdf
Data publikacji:
2024
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
p(x)-Laplacian
variable exponents
fixed point
singular system
gradient estimates
regularity
Opis:
The paper deals with the existence of solutions for quasilinear elliptic systems involving singular and convection terms with variable exponents. The approach combines the sub-supersolutions method and Schauder’s fixed point theorem.
Źródło:
Opuscula Mathematica; 2024, 44, 1; 105-134
1232-9274
2300-6919
Pojawia się w:
Opuscula Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Regularization error estimates and discrepancy principle for optimal control problems with inequality constraints
Autorzy:
Wachsmuth, D.
Wachsmuth, G.
Powiązania:
https://bibliotekanauki.pl/articles/206129.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Instytut Badań Systemowych PAN
Tematy:
source condition
discrepancy principle
nonsmooth optimization
convex constraints
sparsity
regularization error estimates
Opis:
In this article we study the regularization of optimization problems by Tikhonov regularization. The optimization problems are subject to pointwise inequality constraints in L²(Ω). We derive a-priori regularization error estimates if the regularization parameter as well as the noise level tend to zero. We rely on an assumption that is a combination of a source condition and of a structural assumption on the active sets. Moreover, we introduce a strategy to choose the regularization parameter in dependence of the noise level. We prove convergence of this parameter choice rule with optimal order.
Źródło:
Control and Cybernetics; 2011, 40, 4; 1125-1158
0324-8569
Pojawia się w:
Control and Cybernetics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Energy Method for Elastic Problems With Non-Homogeneous Boundary Conditions
Autorzy:
Quintanilla, R.
Powiązania:
https://bibliotekanauki.pl/articles/907887.pdf
Data publikacji:
2002
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
matematyka
weighted energy method
decay estimates
Navier equations
non-homogeneous boundary conditions
Opis:
In this paper we propose the weighted energy method as a way to study estimates of solutions of boundary-value problems with non-homogeneous boundary conditions in elasticity. First, we use this method to study spatial decay estimates in two-dimensional elasticity when we consider non-homogeneous boundary conditions on the boundary. Some comments in the case of harmonic vibrations are considered as well. We also extend the arguments to a class of three-dimensional problems in a cylinder. A section is devoted to the study of an ill-posed problem. Some remarks are presented in the last section of the paper.In this paper we propose the weighted energy method as a way to study estimates of solutions of boundary-value problems with non-homogeneous boundary conditions in elasticity. First, we use this method to study spatial decay estimates in two-dimensional elasticity when we consider non-homogeneous boundary conditions on the boundary. Some comments in the case of harmonic vibrations are considered as well. We also extend the arguments to a class of three-dimensional problems in a cylinder. A section is devoted to the study of an ill-posed problem. Some remarks are presented in the last section of the paper.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2002, 12, 1; 91-100
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Estimation of fertility in Poland and of Polish born women in the United Kingdom
Autorzy:
Gołata, Elżbieta
Powiązania:
https://bibliotekanauki.pl/articles/1827714.pdf
Data publikacji:
2016-06-10
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Population Census Quality
Population Estimates
Polish Migration
Migrant Fertility
Usually Resident Population
Opis:
The aim of research presented in the paper is to explore the comparison of Total Fertility Rates of Polish women in England and Wales, with the rates for Polish women who are residents in Poland. Population censuses in Poland and the United Kingdom in 2011 provide information for such comparisons and show higher fertility rates of Polish women abroad than in Poland. Two specific questions were investigated. The first one is the question of the number of children born in Poland. It was observed that the number estimated on the basis of census data was not consistent with birth records in the register. The second question concerns the number of the usually resident population in Poland. We provide quality assessment of 2011 population census in Poland, estimates of actual and usually resident population. Based on thorough evaluation, a correction of the population estimates is proposed (RAF). Due to non-response and data omissions, the idea of Small Domain Estimation is applied with two a priori age and sex distributions: from the Polish Census Survey and upon the UK census. Fertility in Poland is estimated with regard to usually resident population published on the Census Hub, our RAF estimates and LFS data. The estimates of women at reproductive age differ for over 495,000, what cause certain discrepancies in TFR. Additionally we analyse changes in timing of birth and provide tempo adjusted TFR. The paper shows consequences of population estimates for measuring fertility. It was found that depending on the population estimates TFR in Poland differs from 1.31 for actual population to 1.45 for RAF estimates and 1.63 for tempo-adjusted TFR. Via detailed empirical examination of the usually resident population estimates in Poland we show inconsistencies resulting from the flexibility in interpretation of definitions given by EU 1260/2013 and specific regulations of individual countries.
Źródło:
Studia Demograficzne; 2016, 169, 1; 13-38
0039-3134
Pojawia się w:
Studia Demograficzne
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical approximations of parabolic functional differential equations on unbounded domains
Autorzy:
Baranowska, Anna
Powiązania:
https://bibliotekanauki.pl/articles/745298.pdf
Data publikacji:
2007
Wydawca:
Polskie Towarzystwo Matematyczne
Tematy:
functional differential equations
stability and convergence
nonlinear estimates of the Perron type
Opis:
The paper is concerned with initial problems for nonlinear parabolic functional differential equations. A general class of difference methods is constructed. A theorem on the error estimate of approximate solutions for difference functional equations of the Volterra type with an unknown function of several variables is presented. The convergence of explicit difference schemes is proved by means of consistency and stability arguments. It is assumed that given function satisfy nonlinear estimates of the Perron type with respect to a functional variable. Results obtained in the paper can be applied to differential integral problems and equations with retarded variables. Numerical examples are presented.
Źródło:
Commentationes Mathematicae; 2007, 47, 2
0373-8299
Pojawia się w:
Commentationes Mathematicae
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Error estimates for finite element approximations of elliptic control problems
Autorzy:
Alt, Walter
Bräutigam, Nils
Rösch, Arnd
Powiązania:
https://bibliotekanauki.pl/articles/729441.pdf
Data publikacji:
2007
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
Linear quadratic optimal control problems
elliptic equations
finite element approximations
error estimates
Opis:
We investigate finite element approximations of one-dimensional elliptic control problems. For semidiscretizations and full discretizations with piecewise constant controls we derive error estimates in the maximum norm.
Źródło:
Discussiones Mathematicae, Differential Inclusions, Control and Optimization; 2007, 27, 1; 7-22
1509-9407
Pojawia się w:
Discussiones Mathematicae, Differential Inclusions, Control and Optimization
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Convergence of power series along vector fields and their commutators; a Cartan-Kähler type theorem
Autorzy:
Jakubczyk, B.
Powiązania:
https://bibliotekanauki.pl/articles/1207968.pdf
Data publikacji:
2000
Wydawca:
Polska Akademia Nauk. Instytut Matematyczny PAN
Tematy:
control systems
Cartan-Kähler theorem
power series
convergence
commutators
Cauchy estimates
vector fields
Opis:
We study convergence of formal power series along families of formal or analytic vector fields. One of our results says that if a formal power series converges along a family of vector fields, then it also converges along their commutators. Using this theorem and a result of T. Morimoto, we prove analyticity of formal solutions for a class of nonlinear singular PDEs. In the proofs we use results from control theory.
Źródło:
Annales Polonici Mathematici; 2000, 74, 1; 117-132
0066-2216
Pojawia się w:
Annales Polonici Mathematici
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A finite difference method for quasi-linear and nonlinear differential functional parabolic equations with Neumann’s condition
Autorzy:
Sapa, Lucjan
Powiązania:
https://bibliotekanauki.pl/articles/962640.pdf
Data publikacji:
2009
Wydawca:
Polskie Towarzystwo Matematyczne
Tematy:
parabolic differential functional equations
difference methods
nonlinear estimates of the generalized Perron type
Opis:
Classical solutions of nonlinear second-order partial differential functional equations of parabolic type with Neumann’s condition are approximated in the paper by solutions of associated explicit difference functional equations. The functional dependence is of the Volterra type. Nonlinear estimates of the generalized Perron type for given functions are assumed. The convergence and stability results are proved with the use of the comparison technique. These theorems in particular cover quasi-linear equations, but such equations are also treated separately. The known results on similar difference methods can be obtained as particular cases of our simple result.
Źródło:
Commentationes Mathematicae; 2009, 49, 1; 83-106
0373-8299
Pojawia się w:
Commentationes Mathematicae
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical approximations of difference functional equations and applications
Autorzy:
Kamont, Z.
Powiązania:
https://bibliotekanauki.pl/articles/255105.pdf
Data publikacji:
2005
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
functional differential equations
stability and convergence
interpolating operators
nonlinear estimates of Perron type
Opis:
We give a theorem on the error estimate of approximate solutions for difference functional equations of the Volterra type. We apply this general result in the investigation of the stability of difference schemes generated by nonlinear first order partial differential functional equations and by parabolic problems. We show that all known results on difference methods for initial or initial boundary value problems can be obtained as particular cases of this general and simple result. We assume that the right hand sides of equations satisfy nonlinear estimates of the Perron type with respect to functional variables.
Źródło:
Opuscula Mathematica; 2005, 25, 1; 109-130
1232-9274
2300-6919
Pojawia się w:
Opuscula Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Global solutions via partial information and the Cahn-Hilliard equation
Autorzy:
Cholewa, Jan
Dłotko, Tomasz
Powiązania:
https://bibliotekanauki.pl/articles/1359015.pdf
Data publikacji:
1996
Wydawca:
Polska Akademia Nauk. Instytut Matematyczny PAN
Tematy:
a priori estimates
Cahn-Hilliard equation
global existence
compact semigroups
higher order parabolic equations
Opis:
Global solutions of semilinear parabolic equations are studied in the case when some weak a priori estimate for solutions of the problem under consideration is already known. The focus is on the rapid growth of the nonlinear term for which existence of the semigroup and certain dynamic properties of the considered system can be justified. Examples including the famous Cahn-Hilliard equation are finally discussed.
Źródło:
Banach Center Publications; 1996, 33, 1; 39-50
0137-6934
Pojawia się w:
Banach Center Publications
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Classical solutions of mixed problems for quasilinear first order PFDEs on a cylindrical domain
Autorzy:
Czernous, W.
Powiązania:
https://bibliotekanauki.pl/articles/255887.pdf
Data publikacji:
2014
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
partial functional differential equations
classical solutions
local existence
characteristcs
cylindrical domain
a priori estimates
Opis:
We abandon the setting of the domain as a Cartesian product of real intervals, customary for first order PFDEs (partial functional differential equations) with initial boundary conditions. We give a new set of conditions on the possibly unbounded domain Ω with Lipschitz differentiable boundary. Well-posedness is then reliant on a variant of the normal vector condition. There is a neighbourhood of ∂Ω with the property that if a characteristic trajectory has a point therein, then its every earlier point lies there as well. With local assumptions on coefficients and on the free term, we prove existence and Lipschitz dependence on data of classical solutions on (0,c)×Ω to the initial boundary value problem, for small c. Regularity of solutions matches this domain, and the proof uses the Banach fixed-point theorem. Our general model of functional dependence covers problems with deviating arguments and integro-differential equations.
Źródło:
Opuscula Mathematica; 2014, 34, 2; 291-310
1232-9274
2300-6919
Pojawia się w:
Opuscula Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fish biomass and species composition in the Malta Reservoir, Poland
Biomasa i struktura gatunkowa ichtiofauny Zbiornika Maltańskiego
Autorzy:
Andrzejewski, W.
Szlakowski, J.
Mastyński., J.
Mazurkiewicz, J.
Godlewska, M.
Powiązania:
https://bibliotekanauki.pl/articles/293014.pdf
Data publikacji:
2010
Wydawca:
Instytut Technologiczno-Przyrodniczy
Tematy:
ichtiofauna
struktura gatunkowa
zagęszczenie biomasy
Zbiornik Maltański
biomass estimates
ichthyofauna
Malta Reservoir
species structure
Opis:
In the Malta Reservoir a total of 16 fish species belonging to six families were recorded in 2008. In the Nordic multi-mesh gillnets 4528 fish belonging to 11 species, with the total weight of 149.5 kg, were caught. The total beach seine catch was 34348.9 kg, which in terms of the reservoir area of 64 ha amounted to biomass density 536.7 kg·ha-¹. Of 11 species caught with the beach seine roach (Rutilus rutilus) was the most abundant species (485031 fish, 7578 individuals·ha-¹) with the highest share in biomass (24283.4 kg, 70.7%). The average electric catch at two sampling sites in the Cybina River running in the reservoir bowl was 105 kg (which gave estimate of 2.6 ton in all), with a marked dominance of the roach, which constituted 65.4% of fish catch in weight and 93% in numbers. Taking under consideration the results of electrofishing the estimated fish density in the Malta Reservoir in 2008 could reach as much as 577.7 kg·ha-¹. The proportion of predatory fish in the fish assemblage biomass was 20.1%.
Badania ichtiofauny w Zbiorniku Maltańskim przeprowadzono w 2008 r. w trzech etapach: (1) we wrześniu i w październiku z wykorzystaniem palenowych wontonów badawczych (Nordic gillnets); (2) w październiku i listopadzie w trakcie kolejnego odwodnienia zbiornika ryby były odławiane przez brygadę rybacką za pomocą przywłoki; (3) w listopadzie, po całkowitym odwodnieniu zbiornika, na dwóch stanowiskach w korycie Cybiny, biegnącym w czaszy zbiornika przeprowadzono elektropołowy. W trakcie badań każdorazowo oznaczano gatunki ryb, ich liczbę i masę. W Zbiorniku Maltańskim w 2008 r. stwierdzono występowanie 16 gatunków ryb, należących do sześciu rodzin. W wontony nordyckie złowiono 4528 sztuk ryb, należących do 11 gatunków, o łącznej masie 149,5 kg. Udział płoci, gatunku dominującego w tych połowach, wyniósł 64,5% liczebności połowu i 38,8% jego masy. Udział kolejnych dwóch gatunków, tj. okonia i jazgarza, wyniósł odpowiednio 16,8 i 11,5% liczebności oraz 25,8 i 4,5% masy. W odłowach przywłoką łącznie pozyskano 34 348,9 kg ryb, co w przeliczeniu na hektar powierzchni zbiornika, wyniosło 536,7 kg·ha-¹ (powierzchnia 64 ha). Dominantem pod względem liczebności (485 031 szt., 7578 szt.·ha-¹) i biomasy (24 283,4 kg, 70,7%) była płoć. Udział drugiego pod względem liczebności i biomasy okonia wyniósł 8,9% (3062,5 kg), a jego zagęszczenie wyniosło 1590 szt.·ha-¹. Masa ryb z elektropołowów w korycie Cybiny wynosiła średnio 105 kg. W połowach dominowała płoć, stanowiąc 93% liczebności i 65,4% jego masy. Udział okonia i sandacza wyniósł odpowiednio 3% i 0,6% liczebności oraz 4,7% i 27,8% masy. Zagęszczenie biomasy ichtiofauny Zbiornika Maltańskiego podczas całkowitego odwodnienia w 2008 r. wyniosło 536,7 kg·ha-¹, a po uwzględnieniu wyników elektropołowów - 577,7 kg·ha-¹. Było ono znacznie większe, w stosunku do średniej ze wszystkich dotychczasowych odwodnień (362,2 kg·ha-¹). Udział ryb drapieżnych w biomasie ichtiofauny wyniósł 20,1%, natomiast gatunków niedrapieżnych - 79,9%.
Źródło:
Journal of Water and Land Development; 2010, 14; 67-82
1429-7426
2083-4535
Pojawia się w:
Journal of Water and Land Development
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Error analysis of discrete approximations to bang-bang optimal control problems: the linear case
Autorzy:
Veliov, V. M.
Powiązania:
https://bibliotekanauki.pl/articles/970563.pdf
Data publikacji:
2005
Wydawca:
Polska Akademia Nauk. Instytut Badań Systemowych PAN
Tematy:
liniowy system sterowania
aproksymacja dyskretna
szacowanie błędów
linear control systems
discrete approximations
error estimates
Opis:
The paper presents an error estimate for Runge-Kutta direct discretizations of terminal optimal control problems for linear systems. The optimal control for such problems is typically discontinuous, and Lipschitz stability of the solution with respect to perturbations does not necessarily hold. The estimate (in terms of the optimal controls) is of first order if certain recently obtained sufficient conditions for structural stability hold, and of fractional order, otherwise. The main tool in the proof is the established relation between the local convexity index of the reachable set and the multiplicity of zeros of appropriate switching functions associated with the problem.
Źródło:
Control and Cybernetics; 2005, 34, 3; 967-982
0324-8569
Pojawia się w:
Control and Cybernetics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optimality system POD and a-posteriori error analysis for linear-quadratic problems
Autorzy:
Volkwein, S.
Powiązania:
https://bibliotekanauki.pl/articles/206100.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Instytut Badań Systemowych PAN
Tematy:
optimal control
model reduction
proper orthogonal decomposition
a-posteriori error estimates
optimality system POD
Opis:
In this paper an abstract linear-quadratic optimal control problem governed by an evolution equation is considered. To solve this problem numerically a reduced-order approach based on proper orthogonal decomposition (POD) is applied. The error between the POD suboptimal control and the optimal control of the original problem is controlled by an a-posteriori error analysis. However, if the POD basis has bad approximation properties, a huge number of POD basis function is required to solve the reduced-order problem with the desired accuracy. To overcome this problem, optimality system POD (OS-POD) is utilized, where the POD basis is chosen with respect to the optimization criteria.
Źródło:
Control and Cybernetics; 2011, 40, 4; 1109-1124
0324-8569
Pojawia się w:
Control and Cybernetics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Experimental Evidence That Hubble’s Parameter Could Be Reflected in Local Physical and Chemical Reactions: Support for Mach’s Principle of Imminence of the Universe
Autorzy:
Persinger, M.A.
Powiązania:
https://bibliotekanauki.pl/articles/412010.pdf
Data publikacji:
2013
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
Hubble constant
Planck's length expansions
protons and electrons
point durations
Mach’s principle
local estimates
Opis:
Mach’s principle of immanence of the universe requires the behavior of local matter to depend upon the remainder of the universe. Hubble’s constant could be employed to calculate the inference of this condition. More than a decade ago specific types of temporally patterned magnetic fields generated by serial 3 ms point durations were shown to produce conspicuous biochemical effects. When the product of this duration and the diameter of a proton was divided into Planck’s Length the estimated Hubble’ parameter was 66.7 ±1.3 km∙ s-1•MParsec-1 which is remarkably similar to the current value of 67.8 km∙ s-1. Photon emissions from chemoluminescent reactions and discrete shifts in pH within spring water during exposure to specific patterns of magnetic fields revealed optimal responses with remarkably similar z-transformations when point durations of the constructive voltages were 3 ms or 1 ms but not 2, 4, or 5 ms. Cumulative results indicate proton (3 ms) and electron (~1.5 ms) processes. These results support Mach’s contention and indicate that relatively accurate inferences of the Hubble parameter might be obtained with more precise instrumentation on the terrestrial surface.
Źródło:
International Letters of Chemistry, Physics and Astronomy; 2013, 11; 86-92
2299-3843
Pojawia się w:
International Letters of Chemistry, Physics and Astronomy
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
$L^p$-$L^q$-Time decay estimate for solution of the Cauchy problem for hyperbolic partial differential equations of linear thermoelasticity
Autorzy:
Gawinecki, Jerzy
Powiązania:
https://bibliotekanauki.pl/articles/1313322.pdf
Data publikacji:
1991
Wydawca:
Polska Akademia Nauk. Instytut Matematyczny PAN
Tematy:
decay estimates
partial differential equations
Cauchy problem
symmetric hyperbolic system of first order
linear thermoelasticity
Opis:
We prove the $L^p$-$L^q$-time decay estimates for the solution of the Cauchy problem for the hyperbolic system of partial differential equations of linear thermoelasticity. In our proof based on the matrix of fundamental solutions to the system we use Strauss-Klainerman's approach [12], [5] to the $L^p$-$L^q$-time decay estimates.
Źródło:
Annales Polonici Mathematici; 1991, 54, 2; 135-145
0066-2216
Pojawia się w:
Annales Polonici Mathematici
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysis and numerical approximation of an elastic frictional contact problem with normal compliance
Autorzy:
Han, Weimin
Sofonea, Mircea
Powiązania:
https://bibliotekanauki.pl/articles/1338688.pdf
Data publikacji:
1999
Wydawca:
Polska Akademia Nauk. Instytut Matematyczny PAN
Tematy:
normal compliance
finite element approximation
Coulomb's law
error estimates
frictional contact
variational inequality
fixed point
Opis:
We consider the problem of frictional contact between an elastic body and an obstacle. The elastic constitutive law is assumed to be nonlinear. The contact is modeled with normal compliance and the associated version of Coulomb's law of dry friction. We present two alternative yet equivalent weak formulations of the problem, and establish existence and uniqueness results for both formulations using arguments of elliptic variational inequalities and fixed point theory. Moreover, we show the continuous dependence of the solution on the contact conditions. We also study the finite element approximations of the problem and derive error estimates. Finally, we introduce an iterative method to solve the resulting finite element system.
Źródło:
Applicationes Mathematicae; 1999, 26, 4; 415-435
1233-7234
Pojawia się w:
Applicationes Mathematicae
Dostawca treści:
Biblioteka Nauki
Artykuł

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