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1

Parameter estimation of non-stationary random media driven by partially stacked seismic data

Lin Ying, Zhang Guangzhi, Chen Siyuan, Huang Minmin, Wang Baoli

Acta Geophysica

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2022

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Vol. 70, no 5

2119--2133

EN

The estimation of non-stationary random medium parameters is the key to the application of random medium theory in fine seismic exploration. We propose a method for estimating non-stationary random medium parameters from partially stacked seismic data. To begin with, the relationship between seismic data and random medium p-wave velocity, s-wave velocity, density model in random medium is described, and the principle and method of estimating the parameters of autocorrelation function of random medium are introduced in this paper. Subsequently, the specific steps of applying the power spectrum method for non-stationary random media parameter estimation are also presented. The feasibility and correctness of the method are verified through the estimation test of the two-dimensional theoretical model. Eventually, the estimation test of non-stationary random medium parameters is carried out by field seismic data. The results show that the non-stationary random medium parameters can better describe the elastic parameter information of the subsurface media and provide a reference for the initial model construction of the elastic parameters, reflecting that the method has good application prospects. Compared with previous studies, this method extends the random medium parameter estimation from stationary to non-stationary and from single wave impedance random medium parameter to multi-elastic parameter random medium parameters. It provides a basis for the in-depth application of random media theory in field data. Meanwhile, this estimation method based on the power spectrum method has the advantage of being intuitive and easy to interpret. However, there are also problems in smoothing effect, which needs further improvement and refinement.

2

New type of Piezoresistive Pressure Sensors for Environments with Rapidly Changing Temperature

Tykhan M., Ivakhiv O., Teslyuk V.

Metrology and Measurement Systems

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2017

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Vol. 24, nr 1

185--192

EN

The theoretical aspects of a new type of piezo-resistive pressure sensors for environments with rapidly changing temperatures are presented. The idea is that the sensor has two identical diaphragms which have different coefficients of linear thermal expansion. Therefore, when measuring pressure in environments with variable temperature, the diaphragms will have different deflection. This difference can be used to make appropriate correction of the sensor output signal and, thus, to increase accuracy of measurement. Since physical principles of sensors operation enable fast correction of the output signal, the sensor can be used in environments with rapidly changing temperature, which is its essential advantage. The paper presents practical implementation of the proposed theoretical aspects and the results of testing the developed sensor.

3

Around and about an application of the GAMLSS package to non-stationary flood frequency analysis

Debele S. E., Bogdanowicz E., Strupczewski W. G.

Acta Geophysica

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2017

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Vol. 65, no. 4

885--892

EN

The non-stationarity of hydrologic processes due to climate change or human activities is challenging for the researchers and practitioners. However, the practical requirements for taking into account nonstationarity as a support in decision-making procedures exceed the up-todate development of the theory and the of software. Currently, the most popular and freely available software package that allows for nonstationary statistical analysis is the GAMLSS (generalized additive models for location, scale and shape) package. GAMLSS has been used in a variety of fields. There are also several papers recommending GAMLSS in hydrological problems; however, there are still important issues which have not previously been discussed concerning mainly GAMLSS applicability not only for research and academic purposes, but also in a design practice. In this paper, we present a summary of our experiences in the implementation of GAMLSS to non-stationary flood frequency analysis, highlighting its advantages and pointing out weaknesses with regard to methodological and practical topics.

4

A comparison of three approaches to non-stationary flood frequency analysis

Debele S. E., Strupczewski W. G., Bogdanowicz E.

Acta Geophysica

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2017

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Vol. 65, no. 4

863--883

EN

Non-stationary flood frequency analysis (FFA) is applied to statistical analysis of seasonal flow maxima from Polish and Norwegian catchments. Three non-stationary estimation methods, namely, maximum likelihood (ML), two stage (WLS/TS) and GAMLSS (generalized additive model for location, scale and shape parameters), are compared in the context of capturing the effect of non-stationarity on the estimation of time-dependent moments and design quantiles. The use of a multimodel approach is recommended, to reduce the errors due to the model misspecification in the magnitude of quantiles. The results of calculations based on observed seasonal daily flow maxima and computer simulation experiments showed that GAMLSS gave the best results with respect to the relative bias and root mean square error in the estimates of trend in the standard deviation and the constant shape parameter, while WLS/TS provided better accuracy in the estimates of trend in the mean value. Within three compared methods the WLS/TS method is recommended to deal with non-stationarity in short time series. Some practical aspects of the GAMLSS package application are also presented. The detailed discussion of general issues related to consequences of climate change in the FFA is presented in the second part of the article entitled “Around and about an application of the GAMLSS package in non-stationary flood frequency analysis”.

5

Application of projection-based interpolation algorithm for non-stationary problem

Woźniak M., Paszyński M.

Computer Science

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2016

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Vol. 17 (3)

297--319

EN

In this paper, we present a solver for non-stationary problems using L 2 projec- tion and h -adaptations. The solver utilizes the Euler time integration scheme for time evolution mixed with projection-based interpolation techniques for solving the L 2 projection problem at every time step. The solver is tested on the model problem of a heat transfer in an L-shape domain. We show that our solver delivers linear computational cost at every time step.

6

Development of approach to modelling and optimization of non-stationary catalytic processes in oil refining and petrochemistry

Dolganova I.O., Dolganov I.M., Ivashkina E.N., Ivanchina E.D., Romanovskiy R.V.

Polish Journal of Chemical Technology

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2012

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Vol. 14, nr 4

22-29

EN

An approach to modelling of non-stationary catalytic processes of oil refi ning and petrochemistry is proposed. The computer modelling systems under development take into account the physical and chemical reaction laws, raw materials composition, and catalyst nature. This allows using the software for the optimization of process conditions and equipment design. The models created can be applied for solving complex problems of chemical reactors design; calculation of different variants of industrial plants reconstruction; refi ning and petrochemicals catalysts selection and testing; catalyst service life prolongation; determination of optimum water supply into the alkanes dehydrogenation reactor; optimization of products separation in the benzene alkylation process.