Ograniczanie wyników
Czasopisma help
Autorzy help
Lata help
Preferencje help
Widoczny [Schowaj] Abstrakt
Liczba wyników

Znaleziono wyników: 2131

Liczba wyników na stronie
first rewind previous Strona / 107 next fast forward last
Wyniki wyszukiwania
Wyszukiwano:
w słowach kluczowych:  simulation
help Sortuj według:

help Ogranicz wyniki do:
first rewind previous Strona / 107 next fast forward last
EN
In this work, we propose a multi-server queuing system for modeling the processes that occur in a maritime container terminal. In our study, the main operations that take place at the quay and in the yard are first disaggregated into several elementary activities. Then we propose the step-by-step calculation of the times of each operation that influences both the unloading and the loading of a container. Next, we analyze the vessel cycle time while separately investigating the STS (ship to shore) crane cycle time, the RTG (rubber tyred gantry) cycle time, as well as the IMV (internal movement vehicle) transfer time. Finally, we apply two process-driven simulation experiments to the system analysis. The paper demonstrates the proposed model’s effectiveness with data from the BCT Gdynia container terminal. We show that, among others, even with properly planned work of STS cranes and RTGs, there is still a high probability that the quay will become a bottleneck of the described processes.
EN
Handling luggage systems is a critical component of a passenger terminal’s operations. The proposed study attempts to find the optimal solution for a manually operated terminal concerning the luggage offloading process from arrival flights carried by a limited number of ground handling agents. Handling agents start the offloading process from the aircraft to the cargo luggage containers carried by a cargo car that will take the containers’ trolleys to the cargo area to offload them into the reserved luggage belt carousel. This study aims to improve airport service quality by minimizing the baggage handling process time for arrival flights which leads to minimizing passenger waiting time in the baggage claim area. We proposed both a deterministic and stochastic approach. The integer programming method is provided to minimize the total number of flights assigned to the belt carousel under the realistic constraint of minimizing the luggage load on each belt carousel. Simulation tools were used so that the offloading process could be modeled to study the effects of various parameters such as the number of ground handling agents for different flights with different amounts of luggage.
EN
The article focuses on the role of modern logistics 4.0 technologies and lean management in optimizing ancillary processes in intralogistics. The literature review presents critical aspects of intralogistics, including using autonomous mobile robots (AMR) and the challenges associated with their successful implementation. The article also discusses the concepts of Industry 4.0 and Industry 5.0. highlighting the importance of synergies between workers and advanced technologies. In optimizing logistics processes, the authors emphasize the importance of lean management and tools such as 5S and Kaizen. The authors analyze the research gap related to the organization of auxiliary processes, intralogistics, and the introduction of modern technologies. The lack of good practices and strategies for implementing new technologies for ancillary processes makes this a critical issue for managers and production engineers. The article provides practical strategies that can be implemented in companies. It is a valuable resource for managers seeking to manage intralogistics and effectively improve support processes in manufacturing plants. In summary, the article provides a comprehensive look at modern approaches to optimizing support processes in internal logistics. It highlights the importance of integrating modern logistics technologies with lean management principles, which can increase companies' efficiency and competitiveness.
EN
This article presents the basic airfoil model with two degrees of freedom - the semi-rigid model, where its forced vibrations were considered, and the exciting force is the aerodynamic force, including its periodic changes, that is, gusts. Since the phenomenological model under study has a coupled form, its versions after decoupling are presented, which has an impact on the results of the final research. The airfoil model presented in this way was shown from the application side in the system of a simple energy harvester based on a deformable beam with piezoelectric elements. The result of the simulation tests is a preliminary analysis of the possibility of using the airfoil as a vibration generator for the energy harvesting system. Along with the application of the mechanical part, a numerical simulation of the electrical part was also implemented, related to the transformation of the voltage generated by piezoelectric elements into a constant voltage signal with a connected receiver with power consumption similar to the Atmega microcontroller with battery charging.
EN
Purpose: The aim of this paper is to present a combination of advanced algorithms for finding optimal solutions together with their tests for a permutation flow-shop problem with the possibilities offered by a simulation environment. Four time-constrained algorithms are tested and compared for a specific problem. Design/methodology/approach: Four time-constrained algorithms are tested and compared for a specific problem. The results of the work realisation of the algorithms are transferred to a simulation environment. The entire solution proposed in the work is composed as a parallel environment to the real implementation of the production process. Findings: The genetic algorithm generated the best solution in the same specified short time. By implementing the adopted approach, the correct cooperation of the FlexSim simulation environment with the R language engine was obtained. Research limitations/implications: The genetic algorithm generated the best solution in the same specified short time. By implementing the approach, a correct interaction between the FlexSim simulation environment and the R language engine was achieved. Practical implications: The solution proposed in this paper can be used as an environment to test solutions proposed in production. Simulation methods in the areas of logistics and production have for years attracted the interest of the scientific community and the wider industry. Combining the achievements of science in solving computationally complex problems with increasingly sophisticated algorithms, including artificial intelligence algorithms, with simulation methods that allow a detailed overview of the consequences of changes made seems promising. Originality/value: The original concept of cooperation between the R environment and the FlexSim simulation software for a specific problem was presented.
PL
Artykuł poświęcono ogólnej charakterystyce ochrony odgromowej pływającej elektrowni fotowoltaicznej wraz ze stacją transformatorową. Przedstawione zostało zagrożenie piorunowe dla poszczególnych struktur obiektu, a następnie dokonano analizy możliwych do zastosowania wariantów ochrony przed działaniem pioruna. Odniesiono się zarówno do: zwodów, przewodów odprowadzających, jak i systemu uziemiającego. Temu ostatniemu, jako elementowi najbardziej różnicującemu sposób wykonania pływającej elektrowni, poświęcono dodatkową analizę modelowo-symulacyjną obejmującą różne sposoby wykonania oraz wpływ zmian środowiskowych na skuteczność jego działania. Całość zamyka podsumowanie oraz wnioski.
EN
This article is devoted to the general characteristics of lightning protection of a floating photovoltaic power plant with a transformer station. The lightning hazard for individual structures of the facility was presented, and then the possible variants of lightning protection were analysed. Reference was made to the air terminals, the discharge wires and the grounding system. The last one was the subject of an additional model and simulation analysis covering various forms of execution and the impact of environmental changes on the effectiveness of its operation as the element that provides the most differentiation of a floating power plant construction method. The paper ends with a summary and conclusions.
EN
During the COVID-19 pandemic, public transport played a crucial role in maintaining essential services while ensuring the safety of both passengers and staff. As the world gradually resumes operations, the impact of the pandemic is expected to persist for some time. Existing studies focus on virus transmission in vehicles, with limited knowledge about post-pandemic passenger flow, safety, and satisfaction. This paper presents a model of passenger movement in public transport, considering factors like boarding times, movement within stops, and the impact of crowding and delays. To reduce transmission at bus stops, we developed a simulation-based passenger flow model using PTV Vissim. The program was used to simulate passenger exchange scenarios, using data collected from real data. The goal was to create a model that minimizes the risk of infection. By understanding passenger flow and interactions with the public transport system, effective measures can be implemented to mitigate the spread of COVID-19 and other infectious diseases.
PL
Podczas pandemii COVID-19 transport publiczny odegrał kluczową rolę w utrzymaniu podstawowych usług, zapewniając jednocześnie bezpieczeństwo zarówno pasażerów, jak i personelu. W miarę jak świat stopniowo wznawia działalność, oczekuje się, że skutki pandemii utrzymają się przez jakiś czas. Istniejące badania koncentrują się na przenoszeniu wirusów w pojazdach, przy ograniczonej wiedzy na temat przepływu pasażerów, bezpieczeństwa i satysfakcji po pandemii. W artykule przedstawiono model poruszania się pasażerów w transporcie publicznym, biorąc pod uwagę takie czynniki, jak czas wejścia do pojazdu, ruch w obrębie przystanków oraz wpływ zatłoczenia i opóźnień. Aby ograniczyć przekazywanie zakażeń na przystankach autobusowych, opracowaliśmy model przepływu pasażerów oparty na symulacji przy użyciu PTV Vissim. W programie przeprowadzono symulację scenariuszy wymiany pasażerów, wykorzystując dane zebrane z danych rzeczywistych. Celem było stworzenie modelu, który minimalizuje ryzyko infekcji. Rozumiejąc przepływ pasażerów i interakcje z systemem transportu publicznego, można wdrożyć skuteczne środki ograniczające rozprzestrzenianie się Covid-19 i innych chorób zakaźnych.
EN
This article presents a Train on Railway Track simulation model and program developed by the authors. The model implements the module for multiple-criteria optimization with a set of proposed objective functions allowing reductions in train passing time, total costs, energy consumption, and adverse environmental impacts. The Train on Railway Track simulator has been developed to allow both the simulation itself and the ride optimization. The main achievement is the development of an algorithm that simulates the passage of a train over 500 km, the duration of which did not exceed two minutes. We present an analysis of the impact of model changes on the duration of the simulation and the accuracy of the results obtained. This allows the use of these achievements in simulations carried out for the railway, automotive, or aviation industries as well. Changes in the classical approach to optimization proposed by the authors made it possible to obtain results directly by solving classical systems of equations. The change in the approach to the optimization and system algorithm has reduced the operating time of the optimization system from thousands of simulations to a single simulation with an additional optimization process that takes several minutes to calculate. This article is a continuation of the description of the work performed, and basic information about the developed simulation model and software functionality is included in a separate publication [13].
EN
We present a novel study concerning the attitudes of road transport enterprises towards a broad application of telematics in operational management in road transportation. The study aims to assess telematics application in road transport and its changes over time while showing the factors most likely to determine the systems’ use. Unobserved categories defined in the technology acceptance model (TAM) are adjusted to measure perceived usefulness, perceived ease of use, and attitudes toward using telematics systems by road transport managers. The study is based on 323 transport enterprises analyzed in two waves in 2020 and 2021. The use of two different time points is motivated by an observed increase in the digitalization of transport documents caused by the COVID-19 pandemic. The empirical findings support the TAM’s usefulness in evaluating IT in transport business management. The findings also reveal that the significantly increased telematics use in 2020 was observed while it was endured. The results are checked for robustness and used for simulations. The study compares managers’ behaviors over time and simulates the effect of individual (observed) variables on unobserved TAM categories.
EN
The aim of this paper was to describe the random phase of the E6 signal, the Galileo satellite navigation system. Based on the available information, mathematical models of the measurement signals of the Galileo system were created. The frequencies of individual signals were determined and their structure visualized. A block diagram of the generation of individual signals is also shown. The main contribution of the paper is the creation of a random phase model of the E6 signal from the Galileo system. In accordance with the technical data of the Galileo system, the parameters of the random phase model were determined. The simulation results confirmed that the frequency instability of the continuous signal E6 n received from the satellite is a stationary process. The short-term stability of the frequency ranges from 10-13 to 10-14. The simulation results confirmed that the Doppler effect significantly affects the random phase of the E6 signal. This phenomenon can affect the results of navigation measurements using the E6 signal. The modeling and simulation results of the random phase of the E6 signal presented in the paper can be used to evaluate the immunity of the Galileo navigation system to interference.
EN
Selective laser melting (SLM) is one of the most effective methods of additive manufacturing (AM). It is used to manufacture products with very complex geometries using a wide range of materials. Practical process conditions are limited by the occurrence of undesirable melting instabilities that degrade the surface quality and lead to product defects. These disadvantages are related to the thermal limitations of the SLM process. The lower thermal limit is due to the need to completely melt the powder layer and partially remelt the underlying layer again to ensure proper bonding between the layers. Exceeding the upper thermal limit in the molten metal pool may cause extensive evaporation, boiling and ejection of molten metal droplets outside the melting area. The article presents an approach and methodology that enable the determination of thermal limits and the operating window of SLM/selective laser sintering (SLS) processes in a relatively simple way. The studies have been performed using various settings of SLM process parameters. The usefulness of the preliminary determination of thermal limitations and approximate prediction of operating window of SLM has been confirmed experimentally and by more accurate computer simulation.
EN
The article describes issues related to creating discrete simulation models for the implementation of the furniture manufacturing and assembly process in a furniture company. The methodology of the manufacturing system analysis was presented, which is aimed to support the appropriate approach to the construction of simulation models. The scope of the work includes the technological identification of the furniture manufacturing and assembly process in real production conditions, on the basis of which the appropriate simulation model was built. The course of the process was analyzed in the Arena software on the basis of a computer simulation based on reports. As a result of the simulation of the manufacturing process with the use of information from report of usage, an area for improvement was located. The re-analysis of the material flow made it possible to propose a change in the input parameters for the simulation model in the indicated area. The results of the second simulation show significant changes in the effective use of workstations and increase in the efficiency of the production line. In practice, it can be the basis for introducing simulated changes in the production system.
PL
W artykule opisano zagadnienia związane z tworzeniem dyskretnych modeli symulacyjnych dla realizacji procesu wytwarzania i montażu mebli w przedsiębiorstwie branży meblarskiej. Przedstawiono metodykę analizy systemu wytwarzania, która ma za zadanie wspierać właściwe podejście dla budowy modeli symulacyjnych. Zakresem praca obejmuje identyfikację technologiczną procesu wytwarzania i montażu mebli w rzeczywistych warunkach produkcyjnych, w oparciu o którą zbudowano właściwy model symulacyjny na przykładzie procesu wytwarzania w rzeczywistych warunkach produkcyjnych. Analizę przebiegu procesu na podstawie symulacji komputerowej w oparciu o raporty przeprowadzono w oprogramowaniu Arena. W wyniku przeprowadzonej symulacji procesu wytwarzania z wykorzystaniem informacji z raportu obciążeń stanowiskowych zlokalizowano obszar do doskonalenia. Powtórna analiza przepływu materiałowego pozwoliła zaproponować zmianę parametrów wejściowych dla modelu symulacyjnego we wskazanym obszarze. Wyniki drugiej symulacji wskazują istotne zmiany w zakresie efektywnego wykorzystania stanowisk pracy oraz zwiększenia wydajności linii produkcyjnej. W praktyce może to stanowić podstawę do wprowadzenia symulowanych zmian w omawianym systemie produkcyjnym.
EN
Currently, the topic of automation of logistic processes in warehouses is relevant. The article considers a control system of high level for a mobile robot with a differential drive with a maximum payload of 200 kg with motion simulation in the Matlab Simulink software product. Optimal control of drives based on brushless DC motors at the lower level has been developed. The transient time of low level control system is 1.067 seconds. The mobile robot control system in the minimum version consists of ten ultrasonic distance sensors located along the perimeter of the mobile robot body and of eight contrast band sensors.
14
PL
Przedstawiono techniczno-ekonomiczną analizę produkcji wodoru z biogazu przez parowy reforming biometanu. Kompleksowa analiza obejmuje bilans masowo-energetyczny instalacji, analizę finansową oraz ekologiczną. Poddano ocenie potencjał utylizacji odpadów (obornika) w kierunku przetworzenia na wodór poprzez reforming parowy biometanu. Wyniki przeprowadzonej analizy pokazują atrakcyjny sposób produkcji biowodoru z biogazu jako ekonomiczną technologię przetwarzania odpadów połączoną z ograniczeniem emisji zanieczyszczeń powodujących efekt cieplarniany.
EN
A numerical model of a pilot plant producing H₂ from biogas by steam reforming of biomethane was developed using Chemcad. The anal. covered the mass and energy balance of the installation, as well as financial and ecological estimation. The results of the anal. showed that the method of H₂ production is economical and reduces pollutant emissions.
EN
The article presents the results of the simulation of the work process of the electromagnetic apparatus of the vortex layer with ferromagnetic working elements on the example of the processing of liquid pig manure. As a result of analytical studies of the process of interaction of cylindrical ferromagnetic elements with a magnetic field in the working chamber of the vortex layer apparatus, the appropriate physical and mathematical apparatus was improved, which is the basis of numerical modeling in the STAR-CCM+ software package.
PL
W artykule przedstawiono wyniki symulacji procesu pracy aparatury elektromagnetycznej warstwy wirowej z ferromagnetycznymi elementami roboczymi na przykładzie procesu przetwarzania gnojowicy świńskiej. W wyniku badań analitycznych procesu oddziaływania cylindrycznych elementów ferromagnetycznych z polem magnetycznym w komorze roboczej aparatu warstwy wirowej ulepszono odpowiednią aparaturę fizyko-matematyczną, która jest podstawą modelowania numerycznego w programie STAR-CCM+ pakiet oprogramowania.
EN
In this paper, a model of solutions to the heat equation with initial conditions from the Orlicz space Lp(Ω) of random variables is built. The constructed model approximates the solution of a homogeneous parabolic equation with given reliability and accuracy in some Orlicz space.
PL
W pracy zbudowano model rozwiązan równania ciepła z warunkami początkowymi z przestrzeni Orlicza Lp(Ω) zmiennych losowych. Skonstruowany model przybliza rozwiązanie jednorodnego równania parabolicznego z zadaną niezawodnoscią i dokładnoscią w pewnej przestrzeni Orlicza.
EN
This study aims to design and improve the plant layout of a ceramic factory by adopting Systematic Layout Planning (SLP) and the simulation technique. A ceramic company in northern Thailand is selected as a case study. Three ceramic products including roof tiles, wall tiles and dishware are studied due to their highest production volume. Through the SLP approach, information regarding the number of departments and machines, the area of the plant, the frequency of movement and the distance between each department is collected for the analysis of the relationship between departments. Two plant layout designs are then proposed; the first one is derived from the Computerized Relationship Layout Planning algorithm (CORELAP), and the second one is the process layout. For selecting the most appropriate layout design, five criteria are considered including total distance, the average total process time of each unit produced, ease of movement, material flow and safety. To determine the distance and the average total process time per unit, Distance-Based Scoring and simulation techniques are conducted while the ease of movement, material flow and safety are rated based on whether the company satisfies each criterion. Employing the weight scoring technique, the results report that the CORELAP layout is the most suitable for further implementation due to its highest weighted score equal to 2.536 while the process layout receives 2.386. Implementing the CORELAP layout can reduce the total distance by 16.76% while the average total process time per unit of the CORELAP layout is not significantly different at the significance level of 0.05 as compared to the existing layout.
EN
The paper presents the application of the pantograph-overhead contact line interaction simulation, which is carried out to assess the fulfillment of the essential interoperability requirements for the interoperability component, which is the overhead contact line. According to the paper's authors, carrying out model validation according to the EN 50318:2002 standard indicated in the technical specification for interoperability does not exhaust the question of the correctness of the method used. This fact is also confirmed in the literature discussed in the paper. To substantiate the above thesis, a numerical simulation was carried out in MATLAB/Simulink using a two-mass model of the pantograph and overhead contact line. As a result of the sensitivity analysis of the influence of the input data on the simulation results, conclusions were formulated to confirm the thesis in question.
PL
W pracy przedstawiona została problematyka zastosowania symulacji współpracy pantografu z siecią trakcyjną, która realizowana jest w celu oceny spełnienia wymagań zasadniczych interoperacyjności dla składnika interoperacyjności, jakim jest sieć trakcyjna. Zdaniem autorów pracy, przeprowadzenie walidacji modelu według wskazanej w technicznej specyfikacji interoperacyjności normy EN 50318:2002, nie wyczerpuje kwestii prawidłowości zastosowanej metody. Fakt ten jest również potwierdzony w literaturze, która została omówiona w pracy. Dla potrzeb uzasadnienia powyższej tezy, przeprowadzona została w programie MATLAB/Simulink symulacja numeryczna z wykorzystaniem dwu-masowego modelu pantografu i sieci trakcyjnej. W wyniku analizy wrażliwości wpływu danych wejściowych na wyniki symulacji zostały sformułowane wnioski potwierdzające przedmiotową tezę.
EN
Mineral processing applications increasingly use recycled water to preserve freshwater natural resources and comply with environmental regulations. However, accumulating anions, cations, and reagents in the process water may affect plant flotation performance and production continuity. Therefore, many cost actions may be needed to mitigate the recycled water effects. Typically, the process water properties and their effects on flotation performance are unknown for a greenfield project. Often, the result is an over-scaling up of the process plant with an additional financial cost. The experimental methodology in the paper focuses on creating water for testing that is closer to the actual process water during the comminution and flotation process for any greenfield project. The scope of the study consists of creating possible process water, conducting flotation experiments, and simulation. In order to validate the dissolution loop method, refractory gold flotation plant conditions were selected in our Finland laboratory. The simulation results of dissolution loop flotation kinetics were compared with the actual plant mass balance. According to the comparative results, the process water created by the dissolution loop method has the same physical and chemical properties as the actual process water at the site except for SO4 -concentration. Moreover, comparing the simulation results of the experimental data and plant mass balance studies shows that the gold grade and recovery results in the simulation were lower than the actual plant mass balance.
EN
The verification of the desired capacity increase in the grinding circuits is performed by simulation studies as they suggest accurate and fast alternatives compared to expensive and labor-intensive methods, particularly for the evaluation of situations that require investment. In this study, simulation was used to evaluate the alternatives that can be made to increase the capacity from 38.86 tph to 90 tph in a grinding circuit where copper slag is autogenously milled. The slag sample was characterized by drop weight and abrasion tests to describe the breakage in autogenous (AG) milling. The performances of the existing circuit and equipment were determined by a comprehensive sampling study, and modeling studies were carried out to form the basis of the simulations. Simulation scenarios were evaluated as investment free and investment requiring alternatives. In the investment free option changing fresh feed size distribution was examined however, capacity could be increased up to only 42 tph. In investment option, increasing the mill motor capacities was simulated and 90 tph target throughput was provided. This result was validated in the plant by replacement of mill motors of AG and pebble mill for 1000 kW and 750 kW, respectively.
first rewind previous Strona / 107 next fast forward last
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.