Temat: random field - Prolib Integro

Skocz do pozycji: 1.

Tytuł:: Generation of realizations of Gaussian random functions on digital computers
Autorzy:: Huk, J.
Tematy:: random numbers generator
random field
simulation; Pokaż więcej
Wydawca:: Polskie Towarzystwo Matematyczne
Powiązania:: https://bibliotekanauki.pl/articles/748609.pdf Link otwiera się w nowym oknie
Opis:: Artykuł nie zawiera streszczenia
This is an extensive survey of methods for simulation of Gaussian random functions and fields on digital computers. The methods are classified as follows: generation of Gaussian random sequences with a given covariance function and spectral density function of a special type, and by discrete Fourier transform of uniform random numbers; generation of stationary and non-stationary Gaussian processes by filtration; and generation of stationary Gaussian processes, Gaussian fields and vector-valued fields by summing harmonics. (MR0488619)
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: On some methods in safety evaluation in geotechnics
Autorzy:: Puła, W.
Zaskórski, Ł.
Tematy:: reliability index
random field
Eurocode 7; Pokaż więcej
Wydawca:: Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Powiązania:: https://bibliotekanauki.pl/articles/178170.pdf Link otwiera się w nowym oknie
Opis:: The paper demonstrates how the reliability methods can be utilised in order to evaluate safety in geotechnics. Special attention is paid to the so-called reliability based design that can play a useful and complementary role to Eurocode 7. In the first part, a brief review of first- and second-order reliability methods is given. Next, two examples of reliability-based design are demonstrated. The first one is focussed on bearing capacity calculation and is dedicated to comparison with EC7 requirements. The second one analyses a rigid pile subjected to lateral load and is oriented towards working stress design method. In the second part, applications of random field to safety evaluations in geotechnics are addressed. After a short review of the theory a Random Finite Element algorithm to reliability based design of shallow strip foundation is given. Finally, two illustrative examples for cohesive and cohesionless soils are demonstrated.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: On the rate of strong mixing in stationary Gaussian random fields
Autorzy:: Cheng, Raymond
Tematy:: stationary random field
strong mixing
prediction theory; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Matematyczny PAN
Powiązania:: https://bibliotekanauki.pl/articles/1293383.pdf Link otwiera się w nowym oknie
Opis:: Rosenblatt showed that a stationary Gaussian random field is strongly mixing if it has a positive, continuous spectral density. In this article, spectral criteria are given for the rate of strong mixing in such a field.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

Tytuł:: Simulation and discretization of random field in the slip-line method
Autorzy:: Przewłócki, J.
Tematy:: bearing capacity
method of characteristics
random field; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Budownictwa Wodnego PAN
Powiązania:: https://bibliotekanauki.pl/articles/240960.pdf Link otwiera się w nowym oknie
Opis:: The paper deals with the problem of bearing capacity of a strip footing based on the random subsoil. The solution has been obtained in a framework of the slip-line method. In order to include randomness of the soil medium, a modification of the method of characteristics is proposed. In such an approach, the stochastic finite difference method based on the Monte Carlo technique has been adopted. It enables including a spatial variability of soil properties into the analysis and to determine its influence on the variance of the ultimate collapse load. It is assumed that the soil medium is purely cohesive and only its cohesion can be considered as a random field. The simulation algorithm of multi-dimensional random field, based on the diagonalisation of the covariance matrix by a transformation using a lower-triangle matrix is described. The problems of the medium discretization and stabilization of the solution are discussed.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 5.

Tytuł:: A strong mixing condition for second-order stationary random fields
Autorzy:: Cheng, Raymond
Tematy:: stationary random field
prediction theory
strong mixing; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Matematyczny PAN
Powiązania:: https://bibliotekanauki.pl/articles/1293378.pdf Link otwiera się w nowym oknie
Opis:: Let ${X_{mn}}$ be a second-order stationary random field on Z². Let ℳ(L) be the linear span of ${X_{mn}: m ≤ 0, n ∈ Z}$, and ℳ(R_N) the linear span of ${X_{mn}: m ≥ N, n ∈ Z}$. Spectral criteria are given for the condition $lim_{N→∞} c_N = 0$, where $c_N$ is the cosine of the angle between ℳ(L) and $ℳ(R_N)$.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 6.

Tytuł:: Numerical simulations of the effect of time-dependent random mass density field on frequencies of sound waves
Autorzy:: Murawski, K.
Tematy:: numerical simulations
convection - Sun
oscillations - turbulence
time-dependent random mass density field
space-dependent random field; Pokaż więcej
Wydawca:: Politechnika Gdańska
Powiązania:: https://bibliotekanauki.pl/articles/1955804.pdf Link otwiera się w nowym oknie
Opis:: Numerical simulations of the effect of random mass density field on frequencies of sound waves are considered for driven and impulsive sound waves which are described by one-dimensional hydrodynamic equations, with the ponderomotive force which depends stochastically both on space and time. The numerical results reveal frequency increase for short waves and both wave damping and amplification for the overall range of wavenumbers. Moreover, a space- and time-dependent random field leads to a generation of a wide frequency spectrum which contains both retarded and speeded up waves.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 7.

Tytuł:: On a strongly consistent estimator of the squared L_2-norm of a function
Autorzy:: Różański, Roman
Tematy:: strong consistency
stochastic integral with respect to a p-parameter martingale
Poisson random field
Wiener random field
asymptotic unbiasedness
kernel estimator; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Matematyczny PAN
Powiązania:: https://bibliotekanauki.pl/articles/1340253.pdf Link otwiera się w nowym oknie
Opis:: A kernel estimator of the squared $L_2$-norm of the intensity function of a Poisson random field is defined. It is proved that the estimator is asymptotically unbiased and strongly consistent. The problem of estimating the squared $L_2$-norm of a function disturbed by a Wiener random field is also considered.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 8.

Tytuł:: Evaluation of bearing capacity of strip footing using random layers concept
Autorzy:: Kawa, M.
Łydżba, D.
Tematy:: random field theory
reliability
bearing capacity
random layers concept
kinematic approach; Pokaż więcej
Wydawca:: Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Powiązania:: https://bibliotekanauki.pl/articles/178972.pdf Link otwiera się w nowym oknie
Opis:: The paper deals with evaluation of bearing capacity of strip foundation on random purely cohesive soil. The approach proposed combines random field theory in the form of random layers with classical limit analysis and Monte Carlo simulation. For given realization of random the bearing capacity of strip footing is evaluated by employing the kinematic approach of yield design theory. The results in the form of histograms for both bearing capacity of footing as well as optimal depth of failure mechanism are obtained for different thickness of random layers. For zero and infinite thickness of random layer the values of depth of failure mechanism as well as bearing capacity assessment are derived in a closed form. Finally based on a sequence of Monte Carlo simulations the bearing capacity of strip footing corresponding to a certain probability of failure is estimated. While the mean value of the foundation bearing capacity increases with the thickness of the random layers, the ultimate load corresponding to a certain probability of failure appears to be a decreasing function of random layers thickness.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 9.

Tytuł:: On determining the undrained bearing capacity coefficients of variation for foundations embedded on spatially variable soil
Autorzy:: Chwała, Marcin
Tematy:: spatial averaging
random field
random bearing capacity
fluctuation scale
failure mechanism; Pokaż więcej
Wydawca:: Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Powiązania:: https://bibliotekanauki.pl/articles/178626.pdf Link otwiera się w nowym oknie
Opis:: This paper presents an efficient method and its usage for the three-dimensional random bearing capacity evaluation for square and rectangular footings. One of the objectives of the study is to deliver graphs that can be used to easily estimate the approximated values of coefficients of variations of undrained bearing capacity. The numerical calculations were based on the proposed method that connects three-dimensional failure mechanism, simulated annealing optimization scheme and spatial averaging. The random field is used for describing the spatial variability of undrained shear strength. The proposed approach is in accordance with a constant covariance matrix concept, that results in a highly efficient tool for estimating the probabilistic characteristics of bearing capacity. As a result, numerous three-dimensional simulations were performed to create the graphs. The considered covariance matrix is a result of Vanmarcke’s spatial averaging discretization of a random field in the dissipation regions to the single random variables. The matrix describes mutual correlation between each dissipation region (or between those random variables). However, in the presented approach, the matrix was obtained for the expected value of undrained shear strength and keep constant during Monte Carlo simulations. The graphs were established in dimensionless coordinates that vary in the observable in practice ranges of parameters (i.e., values of fluctuation scales, foundation sizes and shapes). Examples of usage were given in the study to illustrate the application possibility of the graphs. Moreover, the comparison with the approach that uses individually determined covariance matrix is shown.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 10.

Tytuł:: Bearing capacity of eccentrically loaded strip footing on spatially variable cohesive soil
Autorzy:: Dobrzański, Jędrzej
Kawa, Marek
Tematy:: random field
scale of fluctuation
eccentric load
cohesive soil
probabilistic analysis; Pokaż więcej
Wydawca:: Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Powiązania:: https://bibliotekanauki.pl/articles/2041290.pdf Link otwiera się w nowym oknie
Opis:: The study considers the bearing capacity of eccentrically loaded strip footing on spatially variable, purely cohesive soil. The problem is solved using the random finite element method. The anisotropic random field of cohesion is generated using the Fourier series method, and individual problems within performed Monte Carlo simulations (MCSs) are solved using the Abaqus finite element code. The analysis includes eight different variants of the fluctuation scales and six values of load eccentricity. For each of these 48 cases, 1000 MCSs are performed and the probabilistic characteristics of the obtained values are calculated. The results of the analysis indicate that the mean value of the bearing capacity decreases linearly with eccentricity, which is consistent with Meyerhof's theory. However, the decrease in standard deviation and increase in the coefficient of variation of the bearing capacity observed are non-linear, which is particularly evident for small eccentricities. For one chosen variant of fluctuation scales, a reliability analysis investigating the influence of eccentricity on reliability index is performed. The results of the analysis conducted show that the value of the reliability index can be significantly influenced even by small eccentricities. This indicates the need to consider at least random eccentricities in future studies regarding probabilistic modelling of foundation bearing capacity.
Dostawca treści:: Biblioteka Nauki

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