Wyniki wyszukiwania - BazTech

1

New prediction of cracks propagation in repaired steel plate with bonded composite patch at cyclic loading

Maachou Sofiane, Mechab Belaïd, Bouiadjra Bel Abbes Bachir, Salem Mokadem

Acta Mechanica et Automatica

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2024

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Vol. 18, no. 4

579--584

EN

This study presents a numerical prediction of the fatigue life of steel panels repaired by a composite patch. The effect of length cracks, the stress ratio R and properties of the patch is presented. The obtained results show that the bonded composite repair significantly reduces the stress intensity factors at the tip of repaired cracks. The results are in a good agreement with those in the literature. The Monte Carlo method is used to predict the distribution function governing crack propagation in fatigue analysis. In computing the failure probability of the structure, we consider the statistical uncertainty associated with key variables, along with the previously discussed model uncertainty. The results obtained highlight the considerable impact of variations in crack length and stress ratio on the distribution function. Notably, uncertainty in these parameters significantly amplifies the probability of structural failure in plates, thereby diminishing overall structural durability.

2

Power system flexibility assessment for future flexibility needs: high-level screening method of the Macedonian power system

Malcheski Stojan, Kuzarevski Sime, Vuletic Jovica, Angelov Jordanco, Todorovski Mirko

Przegląd Elektrotechniczny

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2023

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R. 99, nr 6

138--141

EN

With the European aim to reduce the carbon footprint of the European energy sector by 2030 North Macedonia strategic framework set an ambitious goal to decommission its coal-fired power plants and replace them with renewable energy sources. The future flexibility and inertia states of the power system are assessed using a Monte Carlo market model calculation and multiple scenarios. On a mid-term planning horizon, this paper employs various metrics to derive a comprehensive estimation of the system's inertia and flexibility requirements for the Macedonian power system.

PL

Realizując europejski cel zmniejszenia śladu węglowego europejskiego sektora energetycznego do 2030 r., w ramach strategicznych Macedonii Północnej wyznaczono ambitny cel likwidacji elektrowni węglowych I zastąpienia ich odnawialnymi źródłami energii. Przyszłe stany elastyczności i bezwładności 138 ystemu elektroenergetycznego są oceniane za pomocą obliczeń modelu rynkowego Monte Carlo i wielu scenariuszy. W horyzoncie planowania średniookresowego niniejszy138ystem138tt wykorzystuje różne wskaźniki w celu uzyskania kompleksowego oszacowania wymagań dotyczących bezwładności i elastyczności 138 ystemu dla macedońskiego 138 ystemu elektroenergetycznego.

3

Monte Carlo simulation of polarization of light back-scattered from randomly rough surfaces

Jiang Yuxiang, Li Zhenhua

Optica Applicata

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2023

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Vol. 53, nr 1

65--85

EN

Laser detection devices obtain target information from back-scattered light, such as lidar. The recognition rate can be improved by analyzing intensity and polarization of echo signal. In this paper, Monte Carlo method is used to generate a large number of randomly rough surfaces to simulate targets. Every rough surface is discretized into a large number of micro-surface elements. Stokes parameters of back-scattered light are calculated by numerical integration. Incident light is p-, s-, 45° linearly polarized light and right-hand circularly polarized light, respectively. Numerical results show that when s- and p-linearly polarized light incident on a metal rough surface, back-scattered light appears circularly polarized component. Metal rough surface resembles a wave plate with phase difference, with the fast axis parallel or perpendicular to the 45° direction. When linearly polarized light is incident on dielectric rough surface, back-scattered light has no circularly polarized component. Experimental data are consistent with the numerical results. The above research provides a new basis for laser detection device to identify metal targets from the environmental background.

4

Co nieco o algorytmach szachowych

Słanina Piotr

MINUT Matematyka i Informatyka na Uczelniach Technicznych

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2023

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Nr 5

195-210

PL

Algorytmy szachowe i ich implementacja od wielu lat są istotną częścią szachowego świata. Artykuł przybliża historię i działanie podstawowych algorytmów, wykorzystywanych w silnikach szachowych.

5

Determination of measurement uncertainty by a Monte Carlo method for an RF power sensor calibration system using a VNA

Jaworski Marek, Szatkowski Jarosław, Kossek Tomasz

Metrology and Measurement Systems

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2023

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Vol. 30, nr 4

703--720

EN

This work proposes a systematic assessment of measuring type A uncertainty (caused by random errors) used in RF power sensor calibration. To reduce A type uncertainty, several successive measurements are repeated. The uncertainty arises from repeatability errors in connectors caused by changes in their electrical properties during repeated mating. The suitability of the METAS UncLib software was analysed and we concluded that software should be developed to take into account the shape of probability density function (PDF) using a Monte Carlo method (MCM), which was lacking in METAS UncLib. The self-developed software was then tested on an example taken from the literature and the superiority of the MCM over the analytical method (GUM) was confirmed. During the calibration of the RF sensor using a vector network analyzer (VNA), a series of repeated measurements were performed and, after applying our MCM software, it was found that the measurement uncertainties calculated by the MCM method were several times larger than those by the GUM. The reason for this was that the correlation between the measured input quantities was not taken into account. When this was done using a covariance matrix and assuming a normal PDF of the input quantities, the results obtained with the GUM and the MCM converged. Our main objective was to investigate the influence of the PDF shape of the input measurement samples on the measurement uncertainty. Taking more than a dozen measurements is too costly, on the other hand, the small sample size prevents a reliable determination of the PDF shape. Finally, to overcome this inconvenience, we have developed a special method that uses the histograms of standardized input data taken at all measurement frequencies under fixed conditions without disconnecting the connectors, to increasing the total number of results which were needed to create the PDF histograms of input quantities.

6

The Method for Assessing the Impact of Variable Coal Demand on the Efficiency of Mine Operations

Fuksa Dariusz

Inżynieria Mineralna

|

2023

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no. 1

267--273

EN

The method presented in the article is based on Monte Carlo simulation and involves studying the impact of random demand fluctuations on the efficiency of mines and mine groups (companies). For random demand fluctuations, a normal distribution is assumed, and the analysis variants present-ed include: • Adopting the mean and variance values based on retrospective data, • Considering the most probable forecast error resulting from predictive formulas, • Taking into account correlated changes in demand. The results obtained are presented in the form of histograms of the degree of operational lever-age. These histograms allow for predicting how the degree of operational leverage of mines will develop, as well as estimating the direction and probability of these changes. The developed and veri-fied sensitivity analysis using real examples constitutes a useful element in rationalizing decision-making processes.

PL

Zaprezentowana w artykule metoda oparta jest na symulacji Monte Carlo i obejmuje badanie wpływu wahań losowych zapotrzebowania na efektywność kopalń oraz ich grup (spółek). Dla losowych wahań zapotrzebowania przyjęto rozkład normalny, a przedstawione warianty analizy uwzględniają: • przyjęcie wartości oczekiwanej i dyspersji według danych retrospektywnych; • przyjęcie najbardziej prawdopodobnego błędu prognozy wynikającego z formuł predykcyjnych; • uwzględnienie skorelowanych zmian zapotrzebowania. Uzyskane wyniki przedstawiono w postaci histogramów stopnia dźwigni operacyjnej. Pozwalają one przewidywać, jak będzie kształtował się stopień dźwigni operacyjnej kopalń, jak również umożliwia oszacować, w którym kierunku zmiany te będą postępować i z jakim prawdopodobieństwem. Opracowana i zweryfikowana na realnych przykładach analiza wrażliwości stanowi przydatny element racjonalizacji procesów decyzyjnych.

7

Investigation of exhaust emissions from the gasoline engine of a light duty vehicle in the Real Driving Emissions test

Andrych-Zalewska Monika, Chlopek Zdzislaw, Pielecha Jacek, Merkisz Jerzy

Eksploatacja i Niezawodność

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2023

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Vol. 25, no. 2

art. no. 165880

EN

The article contains the research results and analysis of the processes that take place as part of a gasoline engine light duty vehicle Real Driving Emissions test. Dimensionless characteristics of exhaust emission and fuel mass consumption in the RDE test were also determined: emission intensity, particle number emission intensity, fuel mass consumption intensity. An algorithm for determining the characteristics specific distance pollutant emission, specific distance particle number and specific distance fuel mass consumption in the vehicle speed domain in the RDE test was presented using the Monte Carlo method. The determined characteristics were approximated by polynomial functions in the form of sets of points. These relationships were characterized by a large dispersion of values, which was primarily due to the fact that the random values of the averaging limits contain very different engine operating conditions.

8

The f.c.c. Crystals of Hard Spheres with an Array of [001]-Nanochannel Inclusions Filled by the Simplest Hard Sphere Molecules

Narojczyk Jakub W.

Computational Methods in Science and Technology

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2023

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Vol. 29, No. 1-4

37--44

EN

In this work the systems composed of particles interacting with hard potential are investigated. These systems feature certain modifications to the crystal structure – selected particles are replaced with ones that differ slightly in their diameters. Such modifications, which can be thought of as “inclusions”, concern particles located in cylindrical nanochannels, oriented in [001] direction. In this study, for the first time, additional constrains have been imposed on the particles forming the inclusions. Namely, the replaced spheres have been randomly grouped into neighbouring pairs which were connected to form simple, di-atomic molecules. The results have been compared with previously investigated systems with similar inclusions but without the connections, i.e. filled only by spheres. The comparison of elastic properties between these systems is presented. It is shown that inclusions filled with dimers have different impact on the values of elastic compliances. It has been demonstrated that by introducing a small number of molecules made of spheres whose diameters differ from the rest of the particles forming the crystal, one is able to modify the hardness and shear resistance of the f.c.c. crystal without changing the Poisson’s ratio (with respect to the analogous system without additional constrains imposed on the inclusion particles).

9

Subdiffusive Behavior in Crowded Environments: Impact of Obstacle Mobility and Spatial Restrictions

Polanowski Piotr, Sikorski Andrzej

Computational Methods in Science and Technology

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2023

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Vol. 29, No. 1-4

27--35

EN

Biological systems are generally dense reaction-diffusion systems. Therefore, determining the mechanism of motion in such systems is of crucial importance in understanding their dynamics. Subdiffusive behavior is very common in biological systems but its origin usually does not have a clear explanation. One attempt to explain this behavior is the presence of randomly placed stationary obstacles in a medium filled with molecules of a certain medium. With an appropriate concentration of obstacles, the molecules of the medium cease to perform classic Brownian motions and motion becomes subdiffusive. This mechanism seems to be well documented in both simulations and experiments. The question arises whether a similar effect can be obtained in systems where obstacles are not stationary, but their mobility is drastically reduced comparing to medium molecules, or the reduction in mobility is combined with a limitation in movement (the movement of obstacles resembles, for example, the Orestein-Ulhenbeck movement). Is it possible to observe subdiffusion behavior in such a situation? We try to answer this question on the basis of Monte Carlo simulations based on the Dynamic Lattice Liquid (DLL) model. Based on the concept of cooperative movements, this model has a unique feature that allows one to take into account the correlation of movements between the elements that make up the examined system, which is important in the case of high densities due to the strict correlation of movements between the moving elements. The tests concern systems where obstacles were single beads whose mobility was changed with additional restrictions imposed on the displacement. It was shown that no entrapment of medium molecules was observed and a slight deviation from normal diffusion was also shown.

10

Risk assessment in railway rolling stock planning

Gołębiowski Piotr, Góra Ignacy, Bolzhelarskyi Yaroslav

Archives of Transport

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2023

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Vol. 65, iss. 1

137--154

EN

Rolling stock planning is one of the steps in the traffic planning process considered from the railway undertaking's point of view. It is directly related to the efficiency of rolling stock utilisation, which should be ensured at the highest possible level in the case of rail transport. The planning work stage is subject to certain risks (threats and opportunities), which, if they materialise, will impact it. It, therefore, makes sense to carry out analyses that can anticipate specific events in good time and introduce appropriate countermeasures in advance. This article aims to conduct a risk assessment process concerning rolling stock planning. It was assumed that the considerations were carried out based on the M_o_R (Management of Risk) methodology. Based on this methodology, risk identification and risk analysis (estimation of risk impact) were carried out. Risk assessment was carried out using the Monte Carlo simulation method. The work identified sixteen risks that represent threats. The principle of risk description was used to identify risks. It requires indicating for each risk the reason for its occurrence and the effect it may have. As a part of risk estimation, variables were selected to assess each risk's impact on the objectives of the stage. Publicly available statistical data were used to define the variables. The variables were expressed in monetary units. The work identified five variables describing impact, which were assigned to the individual risks. As a triangular probability distribution was used for the variability of impact description, the variable's minimum, most likely, and maximum value was identified. A risk assessment was carried out for only two impact description variables (for those variables used to describe the impact of the most significant number of risks). For each variable, statistical parameters were indicated and analysed. The resulting value of the variable describing the impact was then read out for each percentile, and the expected value of the risk was calculated. A detailed risk assessment was made for the lower, middle and upper quartiles. A histogram of the incidence of each variable value was presented, and an assessment was made.

11

Determination of exhaust emission characteristics in the RDE test using the Monte Carlo method

Andrych-Zalewska Monika, Chłopek Zdzisław, Merkisz Jerzy, Pielecha Jacek

Archives of Transport

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2023

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Vol. 66, iss. 2

45--60

EN

The article presents a method of determining the characteristics of exhaust emissions and fuel mass consumption in real driving conditions based on a single test using the Monte Carlo method. The exhaust emission characteristics used are the relations between the emissions and the average vehicle speed, and the characteristic of the fuel mass consumption is the dependence of the fuel mass consumption at the average vehicle speed. The results of empirical research of a passenger car with a spark-ignition engine in the RDE test were used. The use of the Monte Carlo method made it possible to select the initial and final moments of averaging the process values, thanks to which it was possible to determine the discrete values of the characteristics for various values of average vehicle speeds. The determined discrete characteristics of the particulate mass and number emissions and fuel mass consumption relative to the average vehicle speed were approximated by polynomial functions of the second and third degree. The determined discrete characteristics, presented as sets of points, were characterized by a relatively small dispersion in relation to their polynomial approximations. The average relative deviation of the points of discrete characteristics from the value of the polynomial was in most cases small – less than 4%, only in the case of the number of particles emitted deviated from this, as the average relative deviation of the measured points from the determined polynomial was nearly 14%. Combined with the results of RDE empirical studies, the Monte Carlo method proved to be an effective method for determining the characteristics of exhaust emissions, measured in real vehicle operating conditions. The main advantage of the proposed method was a significant reduction in the actual workload necessary to carry out the empirical research – where it became possible to determine the characteristics in a large range of vehicle average speed values with just one drive test. Using standard methods of measuring this type of data, it would be necessary to conduct multiple tests, driving at different average vehicle speeds.

12

Identification of the Parameters of the Model Generating the Microstructure in the Integrated Heating-Remelting-Cooling Process

Marynowski Przemysław, Hojny Marcin, Dębiński Tomasz, Cedzidło D.

Archives of Foundry Engineering

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2023

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Vol. 23, iss. 2

72--79

EN

This paper identifies and describes the parameters of a numerical model generating the microstructure in the integrated heating-remelting-cooling process of steel specimens. The numerical model allows the heating-remelting-cooling process to be simulated comprehensively. The model is based on the Monte Carlo (MC) method and the finite element method (FEM), and works within the entire volume of the steel sample, contrary to previous studies, in which calculations were carried out for selected, relatively small areas. Experimental studies constituting the basis for the identification and description of model parameters such as: probability function, initial number of orientations, number of cells and number of MC steps were carried out using the Gleeble 3800 thermo-mechanical simulator. The use of GPU capabilities improved the performance of the numerical model and significantly reduced the simulation time. Thanks to the significant acceleration of simulation times, it became possible to comprehensively implement a numerical model of the heating-transformation-cooling process in the entire volume of the test sample. The paper is supplemented by results of performance tests of the numerical model and results of simulation tests.

13

Monte Carlo simulations of the fracture resistance degradation of asphalt concrete subjected to environmental factors

Szydłowski Cezary, Smakosz Łukasz, Stienss Marcin, Górski Jarosław

Archives of Civil Engineering

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2023

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Vol. 69, nr 1

245--257

EN

The paper presents the results of laboratory tests of SCB (semi-circular beam) samples of asphalt concrete, subjected to the destructive effect of water and frost as well as the aging processes. The determined values of material parameters show significant dispersions, which makes the design of mixtures difficult. Statistical analysis of the test results supplemented by computer simulations made with the use of the proprietary FEM model was carried out. The main distinguishing feature of the model is the assignment of material parameters of coarse aggregate and bituminous mortar to randomly selected finite elements. The parameters of the mortar are selected by trial and error to match the numerical results to the experimental ones. The stiffness modulus of the bituminous mortar is, therefore, a substitute parameter, taking into account the influence of many factors, including material degradation resulting from the aging and changing environmental conditions, the influence of voids, and contact between the aggregate and the bituminous mortar. The use of the Monte Carlo method allows to reflect the scattering of the results obtained based on laboratory tests. The computational algorithm created in the ABAQUS was limited only to the analysis of the global mechanical bending response of the SCB sample, without mapping the failure process in detail. The combination of the results of laboratory tests usually carried out on a limited number of samples and numerical simulations provide a sufficiently large population of data to carry out a reliable statistical analysis, and to estimate the reliability of the material designed.

PL

Odziaływanie czynników środowiskowych zmienia parametry mieszanek mineralno-asfaltowych mających wpływ na odporność na pękanie. W celu oceny zjawiska wykonano badania laboratoryjne z uwzględnieniem niszczącego oddziaływania wody i mrozu oraz procesów starzenia eksploatacyjnego mieszanek. Weryfikacji poddano również wpływ obu czynników występujących jednocześnie. Wyniki badań laboratoryjnych charakteryzują się rozrzutami. Zmienność cech powinna być uwzględniona w modelu materiałowym. Zaproponowany autorski model materiałowy pozwala uwzględnić tę cechę w symulacjach numerycznych poprzez wykorzystanie losowego rozkładu kruszywa grubego oraz zaprawy asfaltowej. Na podstawie otrzymanych wyników laboratoryjnych stworzono algorytm losowo zmieniający parametry materiałowe zaprawy asfaltowej. W rezultacie umożliwiło to uzyskanie rozwiązań numerycznych uwzględniających jednocześnie rozrzuty wyników spowodowane niejednorodnością materiału oraz degradacją betonu asfaltowego pod wpływem oddziaływania czynników środowiskowych. Z uwagi na różne metody oceny odporności na oddziaływanie wody i mrozu badania przeprowadzono według kilku wybranych wariantów kondycjonowania próbek. Oceny wpływu starzenia mieszanek na odporność na pękanie dokonano na podstawie metody AASHTO R 30-02. Dla oceny jednoczesnego wpływu obu czynników część próbek poddano starzenieu długoterminowemu przed symulacją oddziaływania wody i mrozu. Badania zostały przeprowadzone na próbkach betonu asfaltowego do warstwy ścieralnej AC 11 S 50/70 KR3÷4. Ocenę zmian odporności na pękanie przeprowadzono na podstawie badania próbek SCB z nacięciem 10 mm w temperaturze +10°C, przy prędkości deformacji 1 mm/min.

14

Improving the Environmental Safety Risk Assessment in Construction Using Statistical Analysis Methods

Smirnova Elena, Mamedov Shirali, Shkarovskiy Alexander

Rocznik Ochrona Środowiska

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2022

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Tom 24

110--128

EN

The article aims to assess risk for substantiating the economic and organizational efficiency of construction in the context of ecologic safety. A quantitative risk estimation was made through the Monte Carlo way for negative and positive choices to avoid ecological harm. The simulation algorithm imitated the distribution obtained from the evidence-based fit. The outcomes of a sensitivity investigation are also prepared to verify the suggestion. This risk analysis technique has a digital computer implementation. The simulation data outputs demonstrate the alternative of the general norm of validation and the acceptance of the solution, which is not harmful to the environment. In situations of uncertainty, the decision to select the optimistic flavor with high spending (to retain the reliability of the technics) but less risk pretends to be a decisive factor in the eco-friendly protection strategies of the construction project.

15

Risk assessment in railway traffic planning - assumptions for the method

Gołębiowski Piotr

Prace Naukowe Politechniki Warszawskiej. Transport

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2022

|

z. 134

109--123

EN

Every activity, including within the railway system, is subject to risk, i.e., the possibility of uncertain phenomena that may affect it (both positively and negatively). One of the operational subsystems of the Union Railway System is railway traffic. It consists of four processes - the second is traffic planning. This process is also subject to risk. As it directly relates to traffic safety, conducting research and analyzing the risks involved makes sense. This article aims to develop the assumptions for a risk assessment method in railway traffic planning. This method, once created, will be used to carry out a risk assessment of the indicated process from two points of view: the railway undertaking and the infrastructure manager. As a result of the considerations, it was assumed that risk identification would be performed using the risk description principle from the M_o_R methodology. The risk estimation will be adapted to use a probabilistic risk assessment model. This assessment will be performed using the Monte Carlo simulation method, which is strongly recommended for use by the Office of Railway Transport (the national railway safety body).

PL

Każda działalność, także w obrębie systemu kolejowego, obarczona jest ryzykiem, czyli możliwością wystąpienia niepewnych zjawisk, które mogą mieć na nią wpływ (zarówno pozytywny jak i negatywny). Jednym z podsystemów eksploatacyjnych systemu kolei Unii jest ruch kolejowy. Składa się on z czterech procesów – drugi to planowanie ruchu. Proces ten także jest obarczony ryzykiem. Ze względu na to, że ma on bezpośredni związek z bezpieczeństwem ruchu, to zasadnym jest prowadzenie badań i analiz nad ryzykiem z nim związanym. Celem artykułu jest opracowanie założeń do metody oceny ryzyka w planowaniu ruchu kolejowego. Metoda ta, po jej opracowaniu, zostanie wykorzystana do przeprowadzenia oceny ryzyka wskazanego procesu z dwóch punktów widzenia: przewoźnika kolejowego oraz zarządcy infrastruktury. W wyniku przeprowadzonych rozważań przyjęto, że identyfikacja ryzyka zostanie dokonana z wykorzystaniem zasady opisu ryzyka z metodyki M_o_R. Szacowanie ryzyka zostanie dostosowane do wykorzystania probabilistycznego modelu oceny ryzyka. Ocena ta zostanie wykonana przy pomocy metody symulacyjnej Monte Carlo, która jest jedną ze zdecydowanie zalecanych do wykorzystania przez Urząd Transportu Kolejowego (krajowy organ bezpieczeństwa ruchu kolejowego).

16

Niepewność w analizach wypadków na przykładzie zdarzeń z udziałem pieszych

Guzek Marek

Paragraf na Drodze

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2022

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Nr 2

31--45

PL

W opiniowaniu dotyczącym wypadków drogowych zawsze będziemy mieli do czynienia z niepewnością wyników obliczeń. Celem artykułu jest przedstawienie wybranych aspektów związanych z oceną niepewności na przykładzie sytuacji zagrożenia potrącenia pieszego. Wykorzystując wyniki badań eksperymentalnych prowadzonych w symulatorze jazdy samochodem wskazano typowe zachowania kierowców w sytuacji zagrożenia w postaci wtargnięcia pieszego przed nadjeżdżający pojazd. Wykorzystując analogiczny scenariusz zdarzenia, prosty model analityczny i założone, ale realistyczne wartości parametrów opisujących kierowcę, pojazd i drogę przedstawione są obliczenia wybranych wskaźników opisujących sytuację biorąc pod uwagę niepewność. Do obliczeń niepewności wykorzystano metodę probabilistyczną Monte Carlo. Wyniki przedstawiono w postaci charakterystyk probabilistycznych długości drogi zatrzymania. Pokazano możliwość określenia przedziałów odległości potrzebnej do zatrzymania pojazdu z określonym poziomem ufności. Pokazano także prawdopodobieństwa wystąpienia potrącenia pieszego. Przedstawione wyniki wskazują z jednej strony na potrzebę uwzględniania niepewności w obliczeniach dotyczących analiz wypadkowych, a z drugiej na duże możliwości i korzyści przy stosowaniu metod probabilistycznych do oceny niepewności.

EN

When preparing expert opinions on road accidents, we will always deal with the uncertainty of calculations results. The aim of the article is to present selected aspects related to the assessment of uncertainty, illustrated by the situation of the risk of hitting a pedestrian. Based on the results of experiments conducted in a car driving simulator, typical behaviors of drivers in the event of accident risk as in the case of a pedestrian’s intrusion in front of an oncoming vehicle are shown. Using an analogous event scenario, a simple analytical model, and assumed but realistic values of the parameters describing the driver, vehicle, and road, the calculations of selected indicators relating to the situation are presented, taking into account the uncertainty. The Monte Carlo probabilistic method was used to calculate the uncertainty. The results are presented as probabilistic characteristics of the stopping distance. The possibility of determining the distance intervals needed to stop the vehicle with a certain confidence level has been shown. The probabilities of hitting a pedestrian are also given. The presented results indicate, on the one hand, the need to take into account the uncertainty in the calculations of the analyses of accidents, and on the other hand, the great opportunities and benefits of using probabilistic methods to assess uncertainty.

17

Dendrimers vs. Hyperbranched Polymers: Studies of the Polymerization Process Based on Monte Carlo Simulations

Polanowski Piotr, Hałagan Krzysztof, Sikorski Andrzej

Computational Methods in Science and Technology

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2022

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Vol. 28, No. 3

109--117

EN

A simple model was developed for studies of the polymerization process of branched polymers. Monte Carlo simulations were carried out by means of the Dynamic Lattice Liquid algorithm. A living polymerization in bulk of dendrimers and hyperbranched polymers was studied. The mass and structure of both types of macromolecules were investigated. The influence of the functionality of well-defined cores on the structure of the system was also examined. The differences in the kinetics in the formation of both architectures and changes to their structures were discussed. It was shown that both architecture exhibit low dispersity which was found to be higher for hyperbranched macromolecules.

18

Determination of characteristics of pollutant emission from a vehicle engine under traffic conditions in the engine test

Andrych-Zalewska Monika, Chłopek Zdzisław, Merkisz Jerzy, Pielecha Jacek

Combustion Engines

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2022

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R. 61, nr 4

58--65

EN

The paper describes the method of determination of exhaust emission characteristics from a vehicle engine based on the results obtained in a driving test simulated on an engine dynamometer. These characteristics are the relations between the specific distance emissions and the zero-dimensional characteristics of the process of vehicle velocity: the average velocity value and the average value of the absolute value of the product of vehicle velocity and acceleration. The exhaust emission characteristics are used to simulate the emissions from vehicles operating in different types of traffic conditions. The engine operating states in the engine dynamometer tests were determined by the operating conditions of the vehicle during the test. The authors applied the Monte Carlo method in order to determine the characteristics of different values of the zero-dimensional characteristics of the vehicle velocity process. This enabled the determination of the characteristics based on the test results from a single realization of the process of vehicle velocity. Additionally, the developed method allowed a replacement of the empirical research on the chassis dynamometer with the one performed on the engine dynamometer. The obtained exhaust emission characteristics are in line with the characteristics obtained on the chassis dynamometer in multiple tests.

19

Computer Simulation of the Dynamic Behavior of Double Polymer Brush-Solvent Systems

Hałagan K., Banaszak M., Jung J., Polanowski P., Sikorski A.

Computational Methods in Science and Technology

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2021

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Vol. 27, No. 4

141--149

EN

Opposing polymer brush systems were investigated by computer simulations. In a coarse-grained model, chains were restricted to a face-centered cubic lattice with the excluded volume interactions only. The macromolecules were grafted onto two parallel impenetrable surfaces. The dynamic properties of these systems were studied by means of Monte Carlo simulations. The Dynamic Lattice Liquid model and a highly efficient parallel machine ARUZ were employed, which enabled studying large systems at long time scales. The influence of the surface grating density on the system dynamic was shown and discussed. It was demonstrated that the self-diffusion coefficient of solvent depended strongly on the grafting density.

20

Modelowanie rynku energii elektrycznej dla analiz finansowych projektów inwestycyjnych w sektorze wytwórczym

Krupiński Sebastian, Kuszewski Piotr, Paska Józef

Rynek Energii

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2020

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Nr 3

3--9

PL

W artykule przedstawiono metodykę modelowania fundamentalnego polskiego rynku energii jako narzędzie niezbędne do dostarczenia warunków brzegowych dla późniejszych analiz efektywności finansowej projektów inwestycyjnych w sektorze wytwórczym energetyki. W tym celu, w pierwszej kolejności dokonano krótkiej charakterystyki czynników cenotwórczych na rynku energii elektrycznej, po czym omówiono strukturę modelu oraz sposób działania jego składowych. W artykule przedstawiono także najważniejsze założenia oraz sposób zamodelowania poszczególnych zmiennych. W ramach pracy przeprowadzono także symulacje funkcjonowania polskiego rynku energii elektrycznej w perspektywie do 2053 roku oraz zaprezentowano ich wyniki.

EN

The article presents the methodology of fundamental modelling of the Polish energy market as a tool necessary to provide the boundary conditions for later analyses of the financial effectiveness of investment projects in the power generation sector. For this purpose, a short description of price-generating factors on the electricity market was first performed, followed by a brief description of the model’s structure and the way its components work. The article also highlights the most im-portant assumptions and explains how individual variables were modelled. As a final part of the work, simulations of the functioning of the Polish electricity market up to 2053 were conducted and theirs results were presented.