Wyniki wyszukiwania - BazTech

1

Imperfect maintenance in correlated bivariate Wiener model

Bautista Lucía, Castro Inma T., Bérenguer Christophe, Gaudoin Olivier, Doyen Laurent

Safety and Reliability of Systems and Processes

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2023

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Summer Safety and Reliability Seminar 2023

7--17

EN

A two-unit system subject to imperfect maintenance is analyzed in this chapter. The deterioration of the system follows a bivariate Wiener degradation process. This process is built from the trivariate reduction method by sharing a common noise that describes the dependence between both units. This dependence is measured through the Pearson’s correlation coefficient between both degradation trajectories of the bivariate Wiener process at time t. A maintenance strategy consisting of periodic inspections in which the accumulated deterioration of the system is reduced by a certain quantity is implemented. Some results on the monotonicity of the Pearson’s correlation coefficient in different scenarios are obtained.

2

Socio-economic factors associated with house prices. Evidence based on key macroeconomic aggregates globally

Lewandowska Gabriela, Taracha Michal, Maciuk Kamil

Budownictwo i Architektura

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2023

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Vol. 22, no 3

45--58

EN

The aim of this paper is to assess the association between macroeconomic factors and house prices in selected OECD countries. In this paper, authors describe selected socioeconomic factors, adapt a transparent methodology based on the OECD database and derive results shedding a light on the main drivers shaping the trends of the real estate prices. Two main economic aggregates, inflation and gross domestic product (GDP) were analysed for the OECD member and non-member countries for which complete data have been made available for the period of 1990-2020. The OECD provides data for 60 countries in total, out of which 38 are members of the organization. Nevertheless, due to missing observations in certain countries, the analysis was carried out in 19 of them. The aim of the study was to determine how GDP and inflation dynamics are correlated with changes in property prices. Among the analysed countries, Japan and South Africa could be distinguished as outliers in terms of inflation, whereas in the case of GDP, Italy, Japan, Ireland and Norway stood out. Additionally, 12 representative countries were described in detail. These countries comprised four groups of three countries divided across two dimensions: the first, based on the highest and the lowest correlation coefficient, and the second, based on the measure used to calculate the correlation coefficient (correlation of the house prices with GDP and correlation of the house price with inflation). On the basis of the analyses, it was shown that the association between GDP and house prices is stronger than that between inflation and house prices – in most cases, prices increased at a similar rate as GDP. A particularly high correlation between GDP and house prices was found for Norway, New Zealand and Sweden, indicating a potentially higher marginal housing consumption responsiveness to changes in housing wealth in these highly developed countries, characterised by particularly low housing transaction costs and efficient mortgage market. It was deduced that such characteristics lead to a higher wealth elasticity of demand for new houses.

3

Detection of various lung diseases including COVID-19 using extreme learning machine algorithm based on the features extracted from a lightweight CNN architecture

Nahiduzzaman Md., Faruq Goni Md Omaer, Robiul Islam Md., Sayeed Abu, Shamim Anower Md., Ahsan Mominul, Haider Julfikar, Kowalski Marcin

Biocybernetics and Biomedical Engineering

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2023

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Vol. 43, no. 3

528--550

EN

Around the world, several lung diseases such as pneumonia, cardiomegaly, and tuberculosis (TB) contribute to severe illness, hospitalization or even death, particularly for elderly and medically vulnerable patients. In the last few decades, several new types of lungrelated diseases have taken the lives of millions of people, and COVID-19 has taken almost 6.27 million lives. To fight against lung diseases, timely and correct diagnosis with appropriate treatment is crucial in the current COVID-19 pandemic. In this study, an intelligent recognition system for seven lung diseases has been proposed based on machine learning (ML) techniques to aid the medical experts. Chest X-ray (CXR) images of lung diseases were collected from several publicly available databases. A lightweight convolutional neural network (CNN) has been used to extract characteristic features from the raw pixel values of the CXR images. The best feature subset has been identified using the Pearson Correlation Coefficient (PCC). Finally, the extreme learning machine (ELM) has been used to perform the classification task to assist faster learning and reduced computational complexity. The proposed CNN-PCC-ELM model achieved an accuracy of 96.22% with an Area Under Curve (AUC) of 99.48% for eight class classification. The outcomes from the proposed model demonstrated better performance than the existing state-of-the-art (SOTA) models in the case of COVID-19, pneumonia, and tuberculosis detection in both binary and multiclass classifications. For eight class classification, the proposed model achieved precision, recall and fi-score and ROC are 100%, 99%, 100% and 99.99% respectively for COVID-19 detection demonstrating its robustness. Therefore, the proposed model has overshadowed the existing pioneering models to accurately differentiate COVID-19 from the other lung diseases that can assist the medical physicians in treating the patient effectively.

4

The influence of economic factors on world copper production

Černý Igor, Vaněk Michal, Kubesa Jiří

Inżynieria Mineralna

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2022

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no. 1

51--56

EN

Copper is a very important mineral that has a wide application in industry, especially in the electrical industry and energy industry. With the increase in electromobility, its potential will grow in the future. Any shortage of copper on the world market could thus endanger modern industry. Therefore, the authors decided to deal with the influence of economic factors (price, population, GDP and cumulative inflation) on copper production and with creation of suitable econometric models that best expressing the relationship between production and economic factors for the period 2010-2019 in their article. The influence of economic factors on world copper production is examined using the Pearson correlation coefficient. It was found that copper production is inversely proportional to the price of copper, it is a strong dependence. In contrast, the correlation between copper production and other factors is very strong and positive. Using econometric modeling, it was discovered that exponential regression is the best expression for the relationship between copper production and its price and logarithmic regression most appropriate for the relationship between copper production and all other economic factors.

PL

Miedź jest bardzo ważnym minerałem, który ma szerokie zastosowanie w przemyśle, zwłaszcza w elektrotechnice i energetyce. Wraz ze wzrostem elektromobilności jej potencjał będzie rósł w przyszłości. Wszelki niedobór miedzi na rynku światowym mógłby zatem zagrozić nowoczesnemu przemysłowi. W związku z tym autorzy postanowili zająć się wpływem czynników ekonomicznych (cena, ludność, PKB i skumulowana inflacja) na produkcję miedzi oraz stworzyć odpowiednie modele ekonometryczne, wyrażające zależność między produkcją a czynnikami ekonomicznymi dla okresu 2010-2019. Wpływ czynników ekonomicznych na światową produkcję miedzi badany jest za pomocą współczynnika korelacji Pearsona. Stwierdzono, że produkcja miedzi jest odwrotnie proporcjonalna do ceny miedzi, jest to silna zależność. Natomiast korelacja między produkcją miedzi a innymi czynnikami jest bardzo silna i pozytywna. Korzystając z modelowania ekonometrycznego, odkryto, że regresja wykładnicza jest najlepszym wyrażeniem relacji między produkcją miedzi a jej ceną, a regresja logarytmiczna najbardziej odpowiada relacji między produkcją miedzi a wszystkimi innymi czynnikami ekonomicznymi.

5

Preliminary assessment of ADIS16470AMLZ sensor for monitoring of seismic activity in mining area

Śmieja Michał, Banach Jakub, Majkusiak Tomasz, Rapiński Jacek

Diagnostyka

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2022

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Vol. 23, No. 4

art. no. 2022404

EN

Seismic activity monitoring in the mining exploitation area is an important factor, that has an effect on safety and infrastructure management. The introduction sections presents the outline of mining interference into rock mass structure and selected parameters and methods of observation related to its effects. Further in the article an alternative to currently seismic measurement devices was proposed, and an preliminary research of its metrological quality was carried out based on experimental data. Assessment was based on short time Fourier transform (STFT) and Pearson cross-correlation coefficient.

6

Comparative analysis of different trust metrics of user-user trust-based recommendation system

Roy Falguni, Hasan Mahamudul

Computer Science

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2022

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T. 23 (3)

335--373

EN

Information overload is the biggest challenge nowadays for any website – especially e-commerce websites. However, this challenge has arisen due to the fast growth of information on the web (WWW) along with easier access to the internet. A collaborative filtering-based recommender system is the most useful application for solving the information overload problem by filtering relevant information for users according to their interests. However, the current system faces some significant limitations such as data sparsity, low accuracy, cold-start, and malicious attacks. To alleviate the above-mentioned issues, the relationship of trust incorporates in the system where it can be among users or items; such a system is known as a trust-based recommender system (TBRS). From the user perspective, the motive of a TBRS is to utilize the reliability among users to generate more-accurate and trusted recommendations. However, the study aims to present a comparative analysis of different trust metrics in the context of the type of trust definition of TBRS. Also, the study accomplishes 24 trust metrics in terms of the methodology, trust properties & measurements, validation approaches, and the experimented data set.

7

Receivables management : the importance of financial indicators in assessing the creditworthiness

Siekelova A., Kliestik T., Svabova L., Androniceanu A., Schonfeld J.

Polish Journal of Management Studies

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2017

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Vol. 15, No. 2

217--228

EN

Trade credit is a strategic tool in the hands of the company. Favourable payment terms are the competitive advantage for the company. On the other hand, negatives of providing trade credits have to be seen. This is particularly the risk of late payments or non-payments, also additional costs associated with the receivables management and the fact that the capital tied in receivables does not bring a yield to the company. Receivables management is an important tool for the elimination of payment risk. Thus it constitutes an essential part of the financial management of each company. Trade receivables are an inherent part of the current assets. Provision trade credits should not be granted. It should be a premeditated move on the basis of credit standing of potential clients. Credit evaluation is performed on the basis of recommended indicators. The aim of the paper is to test the existence of a statistically significant relationship between the quick ratio and selected financial indicators.

PL

Kredyt handlowy jest strategicznym narzędziem w rękach firmy. Korzystne warunki płatności to przewaga konkurencyjna przedsiębiorstwa. Z drugiej strony należy zauważyć negatywy w dostarczaniu kredytów handlowych. Związane jest to w szczególności z ryzykiem opóźnień w płatnościach lub brakiem płatności, dodatkowymi kosztami związanymi z zarządzaniem wierzytelnościami oraz faktem, że kapitał powiązany z należnościami nie przynosi zysku spółce. Zarządzanie należnościami jest ważnym narzędziem eliminacji ryzyka płatności. Stanowi zatem zasadniczą część zarządzania finansami każdej firmy. Należności handlowe są nieodłączną częścią aktywów obrotowych. Nie należy pochopnie przyznawać kredytów handlowych, powinien to być przemyślany ruch na podstawie zdolności kredytowej potencjalnych klientów. Ocena kredytowa przeprowadzana jest na podstawie zalecanych wskaźników. Celem pracy jest sprawdzenie istnienia statystycznie istotnego związku pomiędzy wskaźnikiem szybkiej płynności a wybranymi wskaźnikami finansowymi.

8

Adsorpcja chromu z wód o różnym składzie chemicznym

Lach J.

Inżynieria i Ochrona Środowiska

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2016

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T. 19, nr 3

353--362

EN

The effectiveness of the Cr(VI) anions or Cr(III) cations adsorption depends, among others, on the chemical composition of the solution. The study analyzed the impact of the composition of 8 natural waters (spring, low-, medium-, and highly mineralised) on the effectiveness of the adsorption of Cr(VI) and Cr(III) on WG-12 carbon. The adsorption capacity of carbon against the hexavalent chromium from a single-component solution of 1 mg/dm3 concentration (the carbon mass to the weight of the solution 1:250) was 240 mg/kg, while from the medium-carbonized water - 195 mg/kg. In the case of trivalent chromium, under similar conditions, the effect of the presence of competing ions was much more pronounced (the capacity for a monovalent solution was 140 mg/kg, and for medium-carbonized water only 30 mg/kg). There was a negative correlation observed between the adsorption efficiency of Cr(III) and Cr(VI) (average, or at maximum concentration), and the amount of anions, cations and general mineralization. Analysing the adsorption of solutions of different composition and degree of mineralization, but of similar solution pH values, very high correlations are observed (by the Pearson correlation coefficient).

PL

Skuteczność adsorpcji anionów Cr(VI) lub kationów Cr(III) zależy m.in. od składu chemicznego roztworu. W pracy przeanalizowano wpływ składu 8 naturalnych wód (źródlanych, nisko-, średnio- i wysokozmineralizowanych) na skuteczność adsorpcji Cr(VI) i Cr(III) na węglu WG-12. Pojemność adsorpcyjna węgla wobec chromu sześciowartościowego z roztworu jednoskładnikowego o stężeniu 1 mg/dm3 (masa węgla do masy roztworu 1:250) wynosiła 240 mg/kg, podczas gdy z wody średniozmineralizowanej 195 mg/kg. W przypadku chromu trójwartościowego w analogicznych warunkach wpływ obecności konkurencyjnych jonów był znacznie bardziej widoczny (pojemność dla roztworu jednowartościowego wynosiła 140 mg/kg, a dla wody średniozmineralizowanej tylko 30 mg/kg). Między skutecznością adsorpcji Cr(III) i Cr(VI) (średnią lub przy maksymalnym stężeniu) a ilością anionów, kationów i mineralizacją ogólną zachodzi ujemna korelacja. Jeśli analizuje się adsorpcję z roztworów o różnym składzie (stopniu mineralizacji), ale o podobnych wartościach pH roztworu, otrzymuje się bardzo wysokie zależności (wg współczynnika korelacji Pearsona).

9

GOP Structure Adaptable to the Location of Shot Cuts

Krulikovská L., Polec J.

International Journal of Electronics and Telecommunications

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2012

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Vol. 58, No. 2

129-134

EN

In this paper we present a novel two stage algorithm for improving video coding efficiency. The proposed method combines video cut detection and adaptive GOP structure. At first, we have proposed a new technique of frames' comparison for the shot cut detection. The majority of existing methods compare pairs of successive frames. We compare actual frame with its motion estimated prediction. We also present adaptive threshold. The efficiency of novel technique for video cut detection was confirmed through experiment and compared to the commonly used ones in the terms of recall and precision. The next step is to situate I frames to the positions of detected cuts during the process of video encoding. Finally the proposed method is verified by simulations and the obtained results are compared with fixed GOP structures of sizes 4, 8, 12, 16, 32, 64, 128 and GOP structure with length of entire video. Proposed method achieved the gain in bit rate from 15,33% to 50,59%, while not degrading PSNR in comparison to simulated fixed GOP structures.