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1

The Use of the XGBoost and Kriging Methods in the Prediction of the Microstructure of CGI Cast Iron

Sztangret Łukasz, Olejarczyk-Wożeńska Izabela, Regulski Krzysztof, Gumienny Grzegorz, Mrzygłód Barbara

Archives of Foundry Engineering

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2023

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Vol. 23, iss. 4

22--33

EN

Compacted Graphite Iron (CGI) is a unique casting material characterized by its graphite form and extensive matrix contact surface. This type of cast iron has a tendency towards direct ferritization and possesses a complex set of intriguing properties. The use of data mining methods in modern foundry material development facilitates the achievement of improved product quality parameters. When designing a new product, it is always necessary to have a comprehensive understanding of the influence of alloying elements on the microstructure and consequently on the properties of the analyzed material. Empirical studies allow for a qualitative assessment of the above-mentioned relationships, but it is the use of intelligent computational techniques that allows for the construction of an approximate model of the microstructure and, consequently, precise predictions. The formulated prognostic model supports technological decisions during the casting design phase and is considered as the first step in the selection of the appropriate material type.

2

Using monthly rainfall data to estimate rainfall erosivity factor of Iraq

Al-Shamarti Hasanain K., Manji Osamah B., Albw Jbianah Mohanad I. K.

Przegląd Naukowy Inżynieria i Kształtowanie Środowiska

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2019

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Vol. 28, No. 3

444--454

EN

The erosivity factor have a major effect on soil therefor a lot off researchers are interested about it. Actually, the erosivity depend on rainfall that could be a main source to water which effect on soil. To understand the erosivity factor in Iraq, we attempt to explain erosivity factor throughout 30 years (1980–2010). Because of daily data of interval 15 and 30 min are not provided in this area, we used the Fournier modifi ed index (MFI) that based on monthly date of rainfall. Also, we applied linear regression equation between annual rainfall and the MFI to predict the variables and coeff cient of determination was calculated. The study period divided to three decades and spatial distribution by Kriging method was used to interpolate the MFI of study area which calculate by ArcGIS 10.4.1. The results show that in the northern zone of Iraq MFI maximum values were recorded and in the range of MFI above 160. Moreover, in Emadiyah station the MFI excessed 250, which means the erosivity factor has a big effect on soil in this zone. Whereas, in middle zone, the MFI has range 0–120 but most of years of study period recorded 0–90 of the MFI. In southern zone, the MFI was 0–60 therefore the erosivity factor was moderated or law. The linear regression models were found for each station of study area and only Emadiyah, Teleafer, Khanqin and Nasiriya have weak coefficient determination.

3

Fatigue strength reliability assessment of turbo-fan blades by Kriging-based distributed collaborative response surface method

Gao Hai-Feng, Wang Anjenq, Zio Enrico, Ma Wei

Eksploatacja i Niezawodność

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2019

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Vol. 21, no. 3

530--538

EN

Fatigue crack propagation affects the operational reliability of engine turbo-fan blades. In this article, we integrate a Kriging regression model and a distributed collaborative response surface method (DCRSM) for the reliability assessment of turbo-fan blades, considering the relevant uncertainty. Following a series of deterministic analyses, such as steady-state aerodynamic analysis, harmonic response analysis and Campbell diagram, and based on the assumption that vibration stress is mainly from aerodynamic load, the fatigue strength is calculated for turbo-fan blades under coupling aerodynamic forces, according to a modified Goodman curve of titanium-alloy. Giving consideration to the uncertainty of the resonance frequencies and material properties, the fatigue strength of the turbo-fan blade is evaluated, including probabilistic analysis and sensitivity analysis. In the case study analyzed, the conclusions are that the fatigue strength reliability reaches 96.808% with confidence level of 0.95 for the turbo-fan blade under the coupling aerodynamic forces, and the first three-order resonant frequencies are found to have important influence on the fatigue performance of turbo-fan blades.

PL

Propagacja pęknięć zmęczeniowych wpływa na niezawodność pracy łopatek turbowentylatora w silnikach samolotowych. W przedstawionej pracy, niezawodność łopatek turbo-wentylatora oceniano za pomocą techniki która łączy rozproszoną metodę powierzchni odpowiedzi (ang. distributed collaborative response surface method, DCRSM) z krigingiem, z jednoczesnym uwzględnieniem niepewności. Po przeprowadzeniu serii analiz deterministycznych, w tym analizy aerodynamicznej w stanie ustalonym, analizy harmonicznej i wyznaczeniu wykresu Campbella, oraz przyjmując założenie, że naprężenia wibracyjne powstają głównie na skutek obciążeń aerodynamicznych, obliczono wytrzymałość zmęczeniową łopatek turbowentylatora w warunkach sprzęgających sił aerodynamicznych, zgodnie ze zmodyfikowaną krzywą Goodmana dla stopu tytanu. Biorąc pod uwagę niepewność częstotliwości rezonansowych i właściwości materiału, wytrzymałość zmęczeniową łopatki turbowentylatora określano na podstawie analizy probabilistycznej i analizy czułości. W omawianym studium przypadku wykazano, że niezawodność wytrzymałości zmęczeniowej łopatki turbowentylatora w warunkach sprzęgających sił aerodynamicznych sięga 96,808% przy poziomie ufności 0,95, a trzy pierwsze postacie drgań rezonansowych mają istotny wpływ na jej wydajność zmęczeniową.

4

Supervised Machine Learning with Control Variates for American Option Pricing

Mu G., Godina T., Maffia A., Sun Y. C.

Foundations of Computing and Decision Sciences

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2018

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Vol. 43, No. 3

207--217

EN

In this paper, we make use of a Bayesian (supervised learning) approach in pricing American options via Monte Carlo simulations. We first present Gaussian process regression (Kriging) approach for American options pricing and compare its performance in estimating the continuation value with the Longstaff and Schwartz algorithm. Secondly, we explore the control variates technique in combination with Kriging to further improve the estimation of the continuation value. This method allows to reduce dramatically the standard errors and to improve the stability of the Kriging approach. For illustrative purposes, we use American put options on a stock whose dynamics is given by Heston model, and use European options on the same stock as control variates.

5

The choice of optimal lag for Kriging interpolation of NWP model forecast

Katsalova L. M., Shpyg V. M.

Meteorology Hydrology and Water Management. Research and Operational Applications

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2016

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Vol. 4, iss. 2

23--28

EN

. In this paper a Kriging method is reviewed and a way of its application in numerical weather prediction is proposed. The basic principles of the Kriging are shown; the main advantage is its accuracy, but at the same time a disadvantage is its large computational complexity. The construction stage of the variographical model is highlighted, as it is the most important stage and has a significant impact on the accuracy of interpolation. The algorithm for the construction of the variographical model is described. Special attention is paid to averaging an experimental variogram by introducing a special interval, called “lag”. Precisely this issue, according to the authors has a significant impact on the effectiveness of the practical application of Kriging for the interpolation of meteorological parameters. The advantages of averaging an experimental variogram by the administration of lag are presented, and the error that arises in this case is estimated. A theoretical study for the determination of the optimal lag was conducted. The lag proposed for the determination is guided by the criteria of accuracy and the economy of computer time. The twocriteria problem is solved, and the formula, which makes it possible to determine the optimal lag on these criteria, is received. An example shown here is the application of the obtained results for solving the applied task associated with meteorological parameters forecast by the COS MO model.

6

Interpolation of Data Gaps of SLC-off Landsat ETM+ Images Using Algorithm Based on the Differential Operators

Singh R.

Journal of Applied Computer Science Methods

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2014

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Vol. 6 No. 2

93--100

EN

The scan-line corrector (SLC) of the Landsat 7 Enhanced Thematic Mapper Plus (ETM+) sensor failed in May 2003, and this abnormal functioning of SLC resulted in about 22% of the pixels per scene without being scanned. By filling the un-scanned gap by a good technique will help in more use of ETM+ data for many scientific applications. While there have been a number of approaches developed to fill in the data gaps in ETM+ imagery, each method has shortcomings, especially they require SLC-on (images acquired before SLC-off anomaly) imagery for the same location to fill the gaps in SLC-off (images acquired after SLC anomaly) image. To overcome such shortcomings this study proposes an alternative interpolation method based on the partial derivative. This case study shows that this technique is very much useful to interpolate the missing pixel values in the SLC-off ETM+ data.

7

The structure of the crust in TESZ area by kriging interpolation

Majdański M.

Acta Geophysica

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2012

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Vol. 60, no. 1

59-75

EN

A precise 3D model of the crust is necessary to start any tectonic or geodynamic interpretation. It is also essential for seismic interpretations of structures lying below as well as for correct analysis of shallow structures using reflection seismics. During the last decades, a number of wide-angle refraction experiments were performed on the territory of central and eastern Europe (POLONAISE’97, CELEBRATION 2000, SUDETES 2003), resulting in many high quality 2D models. It is an interesting and complicated transition zone between Precambrian and Palaeozoic Platforms. This paper presents 3D model of the velocity distribution in the crust and upper mantle interpolated from 2D models of the structure along 33 profiles. The obtained model extends to a depth of 50 km and accurately describes the main features of the crustal structures of Poland and surrounding areas. Different interpolation techniques (Kriging, linear) are compared to assure maximum precision. The final model with estimated uncertainty is an interesting reference of the area for other studies.

8

Simulation and optimization of heavy-duty semitrailer dynamic model

Korta J., Martowicz A., Gallina A., Uhl T.

Journal of KONBiN

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2011

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No. 4 (20)

85--106

EN

This paper presents an optimization of a multibody truck semitrailer model; its purpose was to find the best values of suspension parameters in order to minimize the disadvantageous influence of force distribution in the high risk areas. A number of simulations with different parameters and under different load cases have been carried out, combined with a parametric and structural sensitivity analysis, and in this way individual factors influencing particular forces have been estimated. The stiffness and damping coefficients of the construction suspension system have been adjusted by applying metamodeling techniques, using two different approaches: Kriging and polynomial regression. Finally, using a desirability function, the most optimal solution has been found.

PL

Artykuł przedstawia proces optymalizacji systemu zawieszenia wirtualnego modelu dynamicznego naczepy samochodowej, przeznaczonej dla pojazdów transportu ciężkiego. Celem podjętych prób było znalezienie wartości charakteryzujących odpowiedź układu na wymuszenia dynamiczne, minimalizujących ich niekorzystny wpływ na punkty konstrukcyjne, będące narażone na nadmierne obciążenia. Przeprowadzono szereg symulacji numerycznych, w oparciu o wyniki których określono wrażliwość systemu na zmieniające się parametry konstrukcyjne oraz użytkowe. Optymalne wartości współczynników tłumienia oraz sztywności badanego systemu obliczono z wykorzystaniem konwersji zagadnienia na monokryterialny problem decyzyjny, w oparciu o skonstruowane dwiema metodami (tj. Kriging i regresją wielomianową) powierzchnie odpowiedzi.

9

Forging preform shape optimization using surrogate models

Repalle J., Grandhi R. V.

Computer Assisted Mechanics and Engineering Sciences

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2007

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Vol. 14, No. 1

53-66

EN

Forging of practical products from simple billet shapes is a complex and nonlinear process due to the multi-disciplinary phenomenon of material flow and processing conditions. General forgings are usually produced in a number of stages in order to avoid defects such as underfill, extra flash, voids, and folds. In spite of advancements in analysis techniques, forging process simulations do not provide function sensitivity information. Hence, the research focuses on exploring efficient non-gradient based preform shape optimization methods. In this research, an attempt is made to develop a preform shape design technique based on interpolative surrogate models, namely Kriging. These surrogate models yield insight into the relationship between output responses and input variables and they facilitate the integration of discipline-dependent analysis codes. Furthermore, error analysis and a comparison between Kriging and other approximation models (response surface and multi-point approximations) are presented. A discussion about what the results mean to a designer is provided. A case study of an automotive component preform shape design is presented for demonstration.