Wyniki wyszukiwania - BazTech

1

Conditional simulation of spatiotemporal random fields of environmental contamination

Jankowski R., Walukiewicz H.

TASK Quarterly : scientific bulletin of Academic Computer Centre in Gdansk

|

2006

|

Vol. 10, No 1

21-26

EN

The paper considers a method of conditional simulation of spatiotemporal scalar random fields of certain environmental phenomena. The method can be used to predict field values at given space points at specified time, on the basis of field values at other locations and data on second order moment functions in the domain. This approach has been applied to a space-time prognosis of soil contamination fields. The assessment of the spatiotemporal variability of heavy metals' concentrations provides the knowledge needed to monitor and control soil contamination. Empirical data of heavy metal (viz. chromium) concentration in the soil of northern Poland have been used in the study. The acceptance-rejection method has been applied to generate covariance matrices and vectors of discrete field values, taking into account conditional probability distributions. The results of the study show that the considered method can be successfully used to model conditional, spatiotemporal random fields of contamination with relatively small simulation errors.

2

Współpraca konstrukcji zabytkowej wieży Twierdzy Wisłoujście z niepewnym podłożem

Walukiewicz H., Tomaszewska A.

Inżynieria i Budownictwo

|

2006

|

R. 62, nr 5

267-270

PL

Przedstawiono model i wyniki pomiarów drgań wieży przy wymuszeniach środowiskowych. Szczególną uwagę poświęcono identyfikacji parametrów niepewnego podłoża na podstawie pomierzonych częstotliwości drgań swobodnych wieży. Wykonano analizę wpływu rozrzutów wartości parametrów sztywności podłoża na te częstotliwości.

EN

The paper analyses a model and vibration measurements under environmental excitations performed in the tower of the Wisłoujście Fortress. An attention is focused on identification of uncertain subsoil parameters, based on the measured natural frequencies of the tower. In addition, an influence of subsoil parameters variations on the tower's natural frequencies has been studied.

3

Informational entropy in simulation of one-dimensional random fields

Opoka Sz., Walukiewicz H.

TASK Quarterly : scientific bulletin of Academic Computer Centre in Gdansk

|

2002

|

Vol. 6, No 3

379-385

EN

The entropy H of a continuous distribution with probability density function f* is defined as a function of the number of nodes (n) in a one-dimensional scalar random field. For the second order theory this entropy is expressed by the determinants of the covariance matrices and simulated for several types of correlation functions. In the numerical example the propagation of the entropy for the static response of linear elastic, randomly loaded beam has been considered. Two unexpected results have been observed: - function H(n) is entirely different for differentiable (m.s.) and non-differentiable fields, with the same parameters in the correlation functions, - in some cases, the greater randomness at the input (measured by the entropy) does not lead to the greater randomness at the output.