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Article ; Online: Selection of Production Reliability Indicators for Project Simulation Model

László Péter Pusztai / Lajos Nagy / István Budai

Applied Sciences, Vol 12, Iss 5012, p

2022 Volume 5012

Abstract: Due to technological enhancements, traditional, qualitative decision-making methods are usually replaced by data-driven decision-making even in smaller companies. Process simulation is one of these solutions, which can help companies avoid costly ... ...

Abstract	Due to technological enhancements, traditional, qualitative decision-making methods are usually replaced by data-driven decision-making even in smaller companies. Process simulation is one of these solutions, which can help companies avoid costly failures as well as evaluate positive or negative effects. The reason for this paper is twofold: first, authors conducted a Quality Function Deployment analysis to find the most vital reliability indicators in the field of production scheduling. The importance was acquired from the meta-analysis of papers published in major journals. The authors found 3 indicators to be the most important: mean time between failure (MTBF), mean repair time and mean downtime. The second part of the research is for the implementation of these indicators to the stochastic environment: possible means of application are proposed, confirming the finding with a case study in which 100 products must be produced. The database created from the simulation is analyzed in terms of major production KPIs, such as production quantity, total process time and efficiency of the production. The results of the study show that calculating with reliability issues in production during the negotiation of a production deadline supports business excellence.
Keywords	production reliability ; reliability ; mean time between failure (MTBF) ; mean time to repair (MTTR) ; process simulation ; project production ; Technology ; T ; Engineering (General). Civil engineering (General) ; TA1-2040 ; Biology (General) ; QH301-705.5 ; Physics ; QC1-999 ; Chemistry ; QD1-999
Subject code	670
Language	English
Publishing date	2022-05-01T00:00:00Z
Publisher	MDPI AG
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article ; Online: Artificial Aging Experiments of Neat and Contaminated Engine Oil Samples

András Lajos Nagy / Jan Rohde-Brandenburger / Ibolya Zsoldos

Lubricants, Vol 9, Iss 63, p

2021 Volume 63

Abstract: This study highlights how the results from an artificial engine oil aging method compare to used engine oil samples collected from a vehicle fleet. Additionally, this paper presents the effect of contaminating the oil during aging with synthetic fuel ... ...

Abstract	This study highlights how the results from an artificial engine oil aging method compare to used engine oil samples collected from a vehicle fleet. Additionally, this paper presents the effect of contaminating the oil during aging with synthetic fuel alternatives on the physical and chemical properties of artificially aged engine oil samples. A laboratory-scale artificial thermo-oxidative aging experiment was conducted on multiple samples of commercially available formulated fully-synthetic SAE 0W-30 engine oil. The goal of the experiment was to establish the validity of the artificially aged samples as well as the validity of the underlying process in reproducibly fabricating small batches of aged engine oil with comparable chemical and physical properties to real-life used oils. Eight samples were subjected to distinct load cases (temperature, air flow rate, sample volume and aging time). Six additional samples were subjected to an intermediate load case, with five of them contaminated with selected conventional fuels and novel automotive fuel candidates. Conventional oil analysis was conducted on each sample to determine oxidation, residual additive content, kinematic viscosity and total base number. Additionally, analysis results were compared to in-use engine oil samples through PCA. The resulting oil condition after aging is in accordance with independently published results in terms of zinc dialkyldithiophosphate content and kinematic viscosity. Contaminated aging with OME 3-5 resulted in a drop in antioxidant content and elevated kinematic viscosity. Based on the comparison with in-use samples, artificial aging of 200 mL engine oil at 180 °C with 1 L/min air flow for 96 h can produce similar oil conditions as mixed vehicle use for 7000 km.
Keywords	engine oil ; artificial aging ; method development ; oil analysis ; Science ; Q
Subject code	660
Language	English
Publishing date	2021-06-01T00:00:00Z
Publisher	MDPI AG
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article ; Online: A Review on Friction Reduction by Laser Textured Surfaces in Internal Combustion Engines

Gabor Laki / András Lajos Nagy / Jan Rohde-Brandenburger / Barna Hanula

Tribology Online, Vol 17, Iss 4, Pp 318-

2022 Volume 334

Abstract: The internal combustion engine will be required as a bridge-technology in the upcoming decades to achieve a significant reduction in local emissions in the mobility, and logistics sector. Alternative fuel technologies will present new mechanical ... ...

Abstract	The internal combustion engine will be required as a bridge-technology in the upcoming decades to achieve a significant reduction in local emissions in the mobility, and logistics sector. Alternative fuel technologies will present new mechanical engineering challenges, including increasing efficiency and reducing mechanical losses. Textured surfaces with appropriate manufacturing parameters can enhance lubrication, and reduce friction in sliding and rolling contacts, e.g., journal bearings, or the piston ring – cylinder subsystem. This paper gives an overview of 80 scientific works related to laser surface technologies, with an emphasis on surface texturing for friction reduction from the viewpoint of engine development. The most common texture types, further directions, and general challenges are highlighted in the summary.
Keywords	laser ablation ; surface texturing ; texture shapes ; internal combustion engines ; friction reduction ; Physics ; QC1-999 ; Engineering (General). Civil engineering (General) ; TA1-2040 ; Mechanical engineering and machinery ; TJ1-1570 ; Chemistry ; QD1-999
Subject code	670
Language	English
Publishing date	2022-12-01T00:00:00Z
Publisher	Japanese Society of Tribologists
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article ; Online: Crop production structure optimization with considering risk

Lajos Nagy

Agrárinformatika Folyóirat, Vol 3, Iss 2, Pp 61-

2012 Volume 71

Abstract: The effects of global climate change are occurring more and more sharply, and because of it – amongst the indisputable genetic and technological development – the yield fluctuation has increased in the crop production past years. Otherwise, this sector ... ...

Abstract	The effects of global climate change are occurring more and more sharply, and because of it – amongst the indisputable genetic and technological development – the yield fluctuation has increased in the crop production past years. Otherwise, this sector is one of the riskiest, so it is obvious to consider risk during the planning, in the phase of decision preparation. Risk programming models are usually applied in agriculture, which take the attitude of the decision-maker to risk into consideration, i.e. these are utility maximization models. First of all, in case of risk programming models the character of risk must be decided. For determining the degree of risk – among others – dispersion indicators are also suitable. If financial portfolios are optimized, most frequently risk is given by the variance of the portfolio. Variance is also applied in the expected value – variance (E-V) models. If variance is minimized, the model has a quadratic object function. An alternative for variance in the linear programming model is the application of mean absolute deviation (MAD). The purpose of this article is to present the application of a portfolio model for optimizing crop production structure and minimizing risk that is generally used in financial investment calculations."
Keywords	Döntés-előkészítés ; kockázat ; kvadratikus programozás ; portfolió ; vetésszerkezet-optimalizálás ; Agriculture (General) ; S1-972 ; Agriculture ; S ; DOAJ:Agriculture (General) ; DOAJ:Agriculture and Food Sciences
Subject code	330
Language	English
Publishing date	2012-12-01T00:00:00Z
Publisher	Hungarian Association of Agricultural Informatics
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article ; Online: The Major Driving Forces of the EU and US Ethanol Markets with Special Attention Paid to the COVID-19 Pandemic

Tamás Mizik / Lajos Nagy / Zoltán Gabnai / Attila Bai

Energies, Vol 13, Iss 5614, p

2020 Volume 5614

Abstract: Ethanol is a widely produced fuel, as well as a fuel additive. Its price is closely related to the price of gasoline, its major substitute. This paper focuses on the impacts of the related variables on regional ethanol prices. Additionally, the length of ...

Abstract	Ethanol is a widely produced fuel, as well as a fuel additive. Its price is closely related to the price of gasoline, its major substitute. This paper focuses on the impacts of the related variables on regional ethanol prices. Additionally, the length of the price dataset made it possible to isolate the impacts of COVID-19 on the ethanol prices. Using multiple regression and Confirmatory Factor Analyses, we found no significant correlation between the European and US ethanol prices because the major influencing factors were regionally different. In the case of the European ethanol markets, the positive factors were wheat, maize, and potassium chloride prices, while the European sugar and diammonium phosphate prices were negative. In the US markets, gasoline, sugar, and most of the artificial fertilizer prices were positive, while wheat prices were negative. Based on factor analysis, artificial fertilizers and maize factors proved to be important to the European markets, while US ethanol prices were driven by the crude oil-gasoline and raw materials factors. The COVID variable showed no significant connection with the EU prices, but negatively affected the US ethanol prices. This is explained by the different market characteristics, as the US is not only the major consumer, but also the major producer of the different oil products. Therefore, COVID-19 had a double effect on their oil and ethanol markets.
Keywords	ethanol ; oil ; price analysis ; correlation ; COVID ; Technology ; T ; covid19
Subject code	330
Language	English
Publishing date	2020-10-01T00:00:00Z
Publisher	MDPI AG
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article ; Online: Increased symmetric dimethylarginine, but not asymmetric dimethylarginine, concentrations are associated with transient myocardial ischemia and predict outcome

Zsuzsanna Szabo / Eva Bartha / Lajos Nagy / Tihamer Molnar

Journal of International Medical Research, Vol

2020 Volume 48

Abstract: Objective Asymmetric and symmetric dimethylarginines (ADMA and SDMA) are endothelial dysfunction markers. ADMA inhibits synthesis of nitric oxide. We aimed to analyze both markers in patients with coronary artery disease (CAD) who were referred for ... ...

Abstract	Objective Asymmetric and symmetric dimethylarginines (ADMA and SDMA) are endothelial dysfunction markers. ADMA inhibits synthesis of nitric oxide. We aimed to analyze both markers in patients with coronary artery disease (CAD) who were referred for stress/rest myocardial perfusion scintigraphy (MPS). Methods All patients underwent a 2-day dipyridamole (DP) stress/rest protocol. Thereafter, patients with transient myocardial perfusion abnormality were followed up and their coronary blood flow was quantitatively assessed. Venous blood was taken before and after DP stress to measure markers. Results Baseline ADMA and SDMA concentrations were significantly higher in patients with CAD compared with healthy subjects. Pre- and post-stress SDMA concentrations were significantly higher in patients with transient myocardial perfusion abnormality compared with those with negative MPS results. However, ADMA and L-arginine concentrations were not significantly different between the two groups. None of the markers were significantly different between patients with angiographically proven low coronary flow and those with normal coronary flow. Pre-stress SDMA concentrations were an independent predictor of cardiovascular mortality during a 8-year follow-up. Conclusions Elevated serum SDMA concentrations may be helpful for selecting high-risk patients with CAD if there is any doubt in interpreting MPS. SDMA concentrations may also predict cardiovascular outcome.
Keywords	Medicine (General) ; R5-920
Subject code	610
Language	English
Publishing date	2020-06-01T00:00:00Z
Publisher	SAGE Publishing
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article ; Online: Some possibilities for risk analysis in the decision support of crop production

Lajos Nagy

Apstract: Applied Studies in Agribusiness and Commerce, Vol 3, Iss 1-

2009 Volume 2

Abstract: This article has been made according to my dissertation in which I present some opportunity of risk analysis and risk management in the decision support of crop production. Plant production is one of the most hazardous agricultural enterprises. Among ... ...

Abstract	This article has been made according to my dissertation in which I present some opportunity of risk analysis and risk management in the decision support of crop production. Plant production is one of the most hazardous agricultural enterprises. Among risk sources seasonal fluctuation of average yields plays an important role in the assessment of enterprises. Therefore, I analyzed the production risk of the produced crops in Hungary compared to the European Union’s, after that I took into consideration the production site’s circumstances as well. Decision-makers must possess such means, by which they can measure, oversee and manage the effects and consequences of risk. In crop production linear programming models can be used to determine the optimal crop structure, by which income-sensitivity can be taken into account, but it does not reflect the behavior to risk. This deficiency can be avoided by using risk programming models. By the complementary usage of linear programming and risk programming models the optimizing and adaptive planning can be executed. It often causes a problem for the producers to decide when and how much to sell to realize a maximum turnover. The decision is mostly influenced by the selling prices, but also important factors are the financial status of the business, the amount of credit and its conditions, the stock piling opportunities and costs, and the short-term investment opportunities as well. For the resolution of the problem I set up a dynamic, simultaneous financial model by which the system-conceptual analysis of the above mentioned factors and a sound decision-making can be executed.
Keywords	risk ; crop production ; decision support ; Agriculture ; S ; Regional planning ; HT390-395
Subject code	330
Language	English
Publishing date	2009-05-01T00:00:00Z
Publisher	University of Debrecen
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article ; Online: Conversion of Isocyanide to Amine in The Presence of Water and Hg(II) Ions

Anita Adamoczky / Lajos Nagy / Miklós Nagy / Miklós Zsuga / Sándor Kéki

International Journal of Molecular Sciences, Vol 21, Iss 5588, p

Kinetics and Mechanism as Detected by Fluorescence Spectroscopy and Mass Spectrometry

2020 Volume 5588

Abstract: Aromatic isocyanides including isocyanonaphthalene derivatives have been proven to be very effective fluorescent sensors for the quantification of Hg(II) ions in water. Thus, the reaction of 1,5-isocyanoaminonaphthalene (1,5-ICAN), which is one of the ... ...

Abstract	Aromatic isocyanides including isocyanonaphthalene derivatives have been proven to be very effective fluorescent sensors for the quantification of Hg(II) ions in water. Thus, the reaction of 1,5-isocyanoaminonaphthalene (1,5-ICAN), which is one of the most important members of this family, with water and HgCl 2 as the oxidation agents, was studied by fluorescence spectroscopy and mass spectrometry in order to get deeper insight into the kinetics and mechanistic details of this complex reaction. The reactions of 1,5-ICAN with water and HgCl 2 were performed in various water/co-solvent mixtures of different compositions. The co-solvents used in this study were both aprotic solvents including tetrahydrofuran, acetonitrile and N,N-dimethylformamide and protic solvents, such as ethanol and 2-propanol. It was found that in aprotic solvents the conversion of the isocyano group to amino moiety takes place, while in protic solvents the corresponding carbamate (urethane) group is formed in addition to the amino moiety. The variation of the resulting fluorescence intensities versus time curves were described using an irreversible, consecutive reaction model, in which the formation of isocyanate and carbamic acid intermediates, as well as diamino and carbamate (in the case of protic solvents) products were assumed. The formation of these intermediates and products was unambiguously confirmed by mass spectrometric measurements. Furthermore, by fitting the model to the experimental fluorescence versus time curves, the corresponding rate coefficients were determined. It was observed that the overall rate of transformation of the isocyano group to amino moiety increased with the water concentration and the polarity of the co-solvent. It was also supported that formation of diamino and carbamate derivatives in protic solvents takes place simultaneously and that the ratio of the amino to the carbamate function increased with the increasing water concentration. In addition, with an extension, the model presented herein proved to ...
Keywords	steady-state fluorescence ; kinetics ; isocyanoaminonaphthalenes ; HgCl 2 ; carbamic acid ; carbamate ; Biology (General) ; QH301-705.5 ; Chemistry ; QD1-999
Subject code	660
Language	English
Publishing date	2020-08-01T00:00:00Z
Publisher	MDPI AG
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article ; Online: Kinetically Equivalent Functionality and Reactivity of Commonly Used Biocompatible Polyurethane Crosslinking Agents

Lajos Nagy / Bence Vadkerti / Csilla Lakatos / Péter Pál Fehér / Miklós Zsuga / Sándor Kéki

International Journal of Molecular Sciences, Vol 22, Iss 4059, p

2021 Volume 4059

Abstract: In this paper, the kinetics of the reaction of phenyl isocyanate with crosslinking agents such as sucrose, sorbitol, and glycerol are reported. Crosslinking agents were used in high molar excess to isocyanate to obtain pseudo-first-order rate ... ...

Abstract	In this paper, the kinetics of the reaction of phenyl isocyanate with crosslinking agents such as sucrose, sorbitol, and glycerol are reported. Crosslinking agents were used in high molar excess to isocyanate to obtain pseudo-first-order rate dependencies, and the reaction products were separated by high-performance liquid chromatography and detected by UV spectroscopy and mass spectrometry. It was found that the glycerol’s primary hydroxyl groups were approximately four times reactive than the secondary ones. However, in the case of sorbitol, the two primary OH groups were found to be the most reactive, and the reactivity of hydroxyl groups decreased in the order of k OH(6) (8.43) > k OH(1) (6.91) > k OH(5) (1.19) > k OH(2) (0.98) > k OH(3) (0.93) > k OH(4) (0.64), where the numbers in the subscript and in the brackets denote the position of OH groups and the pseudo-first-order rate constants, respectively. The Atomic Polar Tenzor (APT) charges of OH groups and dipole moments of monosubstituted sorbitol derivatives calculated by density functional theory (DFT) also confirmed the experimental results. On the other hand, the reactions of phenyl isocyanate with crosslinking agents were also performed using high excess isocyanate in order to determine the number of OH-groups participating effectively in the crosslinking process. However, due to the huge number of derivatives likely formed in these latter reactions, a simplified reaction scheme was introduced to describe the resulting product versus reaction time distributions detected by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-TOF MS). Based on the results, the kinetically equivalent functionality (f k ) of each crosslinking agent was determined and found to be 2.26, 2.6, and 2.96 for glycerol, sorbitol, and sucrose, respectively.
Keywords	glycerol ; sorbitol ; sucrose ; phenyl-isocyanate ; reactivity ; kinetics ; Biology (General) ; QH301-705.5 ; Chemistry ; QD1-999
Subject code	540
Language	English
Publishing date	2021-04-01T00:00:00Z
Publisher	MDPI AG
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article ; Online: Energiamenedzsment térhódítása Magyarországon

Margit Csipkés / László Pusztai / Lajos Nagy

International Journal of Engineering and Management Sciences, Vol 3, Iss

2018 Volume 1

Abstract: Mindennapi életünk egyik legfontosabb eleme az energia, azonban, ennek mértéke folyamatosan csökken. Ezért tanácsos a hagyományos energia mellett megújuló energiákat alkalmazni. A megújuló energiaforrások több figyelmet érdemelnek az energiamenedzsment ... ...

Abstract	Mindennapi életünk egyik legfontosabb eleme az energia, azonban, ennek mértéke folyamatosan csökken. Ezért tanácsos a hagyományos energia mellett megújuló energiákat alkalmazni. A megújuló energiaforrások több figyelmet érdemelnek az energiamenedzsment területén, ugyanis a részarányuk egyre növekszik, bár százalékuk kicsi. Jelenleg, Magyarország és az Európai Unió energiapolitikájának iránymutatásai azt a célt tűzték ki, hogy a megújuló energiaforrások felhasználását növeljék. Ezek a direktívák hozzájárulnak a környezeti és éghajlatvédelmi célok eléréséhez, munkahelyek teremtéséhez, területi- és városfejlesztéshez, valamint az energia importtól való függőség csökkentéséhez. A cikkemben be szeretném mutatni az energiagazdálkodás területén alkalmazott számításokat, valamint fel szeretném térképezni azokat az energiagazdálkodási összefüggéseket, amelyek előtérbe kerültek a lakossági energiafogyasztás vizsgálatakor.
Keywords	Industries. Land use. Labor ; HD28-9999 ; Industrial engineering. Management engineering ; T55.4-60.8 ; Engineering (General). Civil engineering (General) ; TA1-2040 ; Mechanical engineering and machinery ; TJ1-1570 ; Economics as a science ; HB71-74
Language	English
Publishing date	2018-02-01T00:00:00Z
Publisher	Faculty of Engineering, University of Debrecen
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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