Maciej Dwornik

Numerical Calculations for Geophysics Inversion Problem Using Apache Hadoop Technology

There are considerations on the problem of time-consuming calculations in this article. This type of computational problems concerns to multiple aspects of earth sciences. Distributed computing allows to perform calculations in reasonable time. This way of processing requires a cluster architecture.

Influence of initial water saturation in earthen levees on results of numerical modelling of infiltration processes

Levees in Poland are mostly earthen constructions. The stability of earthen levees depends largely on factors such as the construction material, meteorological conditions and natural elements. The influence of initial water saturation of pore space on levee stability is analysed in this paper. Analysis was performed using numerical modelling and water pore pressure results were compared against data obtained from sensors located in a levee. The numerical modelling shows the moderate influence of initial water level on distribution of water pore pressure during high water level.

Parallel implementation of stochastic inversion of seismic tomography data

In this paper parallel implementation of stochastic inversion of seismic tomography data was presented. Classical approach to travel time tomography assumes straight line of seismic rays between sources and receives points and isotropy of geological medium. Such simplifications are potential sources of inaccuracy of the obtained results of travel time tomography. Stochastic methods can be free from these simplifications. On the other hand, this kind of algorithms requires huge number of time consuming calculations. In this work parallelization of two stochastic methods is presented. Different parallel algorithms was applied to presented inversion problems. Obtained results show significant differences in parallel performance of presented inversion algorithms.

Analysis of annual temperature distribution inside the experimental embankment

The aim of this paper is analysis of temperatures distribution inside experimental embankment from August 2015 to September 2016. Analysis was carried out in order to interpretation of the results of the flood experiments performed on the experimental embankment. The reference for year temperature changes in the embankment at various depths was obtained. A simplified model of temperature changes depending on the depth was made. The model parameters which can be used for modelling the temperatures in the embankment during the experiments were estimated.

Optimal selection of numerical models for flood embankment pore pressure and temperature data

The aim of the ISMOP project is to study processes in earthen flood embankments: water filtration, pore pressure changes, and temperature changes due to varying water levels in the riverbed. Developing a system for continuous monitoring of flood embankment stability is the main goal of this project. A full-size earthen flood embankment with built-in sensors was built in Czernichow and used to conduct experiments involving the simulation of different flood waves, with parameters mostly measured at time intervals of 15 minutes. Numerical modelling—in addition to providing information about phenomena occurring in the embankment due to external factors and changes in water level—could be used to assess the state of the embankment. Modelling was performed using Itasca Flac 2D 7.0 with an assumed grid cell size of 10x10 cm. The water level in the embankment simulated the water flow in the Wisla River and the temperature of the air and water. Data about the state of the flood embankment was exported every hour. Using numerical models and real experiment data, a model-driven module was used to perform comparisons. Analyses of each half-section of the flood embankment were carried out separately using similarity measures and an aggregate window. For the tests, the North-West (NW) half cross-section of the embankment was chosen, which contains pore pressure and temperature sensors UT6 to UT10. The water level in the embankment was raised to a height of 3m; the best numerical model was considered the one that best matched the actual data recorded by the sensors during the experiment. The experiment period was from 9pm on 29/08/2016 to 9am on 03/09/2016. Seventeen numerical models of the water level rising to 2, 3, and 4 meters were compared against real experimental data from the NW half cross-section. The first step was to verify the similarity between the incoming data from the sensors. If the correlation value exceeded 0.8, the data from the sensors was averaged. The experimental data was then compared against the numerical models using least absolute deviations L1-Norm. The L1-Norm varied from 26 to 32, depending on window length and the numerical model used.

Preliminary results of a new polarimetric decomposition based on polarimetric signatures

The polarimetric decomposition is one of the key steps of SAR data processing and analysing. Its aim is to obtain maximum information about different scattering mechanisms that occur within each resolution cell of radar image. Since now, there has been a several decomposition methods proposed in the literature. The most widely used are H/A/α, Yamaguchi, Cameron and Huynen decompositions [1]. This paper presents the preliminary results of a new, currently being developed, decomposition method that is based on the idea of pattern recognition in the polarimetric signatures. This decomposition method is designated for quad-polarimetric X-band SAR data and considers four scattering mechanisms: single-bounce, double-bounce, helix scattering and volume scattering.