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

Znaleziono wyników: 303

Liczba wyników na stronie
first rewind previous Strona / 16 next fast forward last
Wyniki wyszukiwania
Wyszukiwano:
w słowach kluczowych:  simulation model
help Sortuj według:

help Ogranicz wyniki do:
first rewind previous Strona / 16 next fast forward last
EN
The efficiency of border crossing services depends on a number of parameters, including the scope of control activities, the number of vehicles to be serviced and the human resources involved. The paper presents the mathematical model allowing the optimization of service parameters at the border crossing point. The queuing theory was implemented due to unbalanced nature of processes. Scientific interest of the model relates to the optimization of the parameters in international goods delivery under the conditions of random nature of vehicles arrival, and with the uneven intensity of servicing vehicles by state administrative services at the crossing border. The model takes into account the trade-off between the number of border staff and vehicle handling time. As a result of the application of the model, the handling process at the border crossing can be optimized, which will lead to a reduction of delivery costs in international traffic.
PL
W artykule przedstawiono analizę strat przełączeniowe w przekształtnikach energoelektronicznych z tranzystorami SiC MOSFET. Omówiono wpływ częstotliwości przełączania na generowanie ciepła oraz metody ograniczania strat, takie jak stosowanie gasików, optymalizacja sterowników bramkowych i wykorzystanie zaawansowanych technologii materiałowych (SiC, GaN). Badania teoretyczne i praktyczne wskazują na korzyści z wykorzystania symulacji komputerowych w projektowaniu przekształtników.
EN
The paper presents an analysis of switching losses in power electronic converters with SiC MOSFET transistors. The influence of switching frequency on heat generation and methods of reducing losses, such as the application of snubbers, gate driver optimization and the use of advanced material technologies (SiC, GaN) are discussed. Theoretical and practical studies indicate the benefits of using computer simulations in the design of power inverters.
EN
The aim of the article was to study the impact of various real-life factors determining the container train loading process duration. Various strategies of the crane operation were considered. Among the factors influencing the train loading duration, railcar hitching pin configuration, container weight, railcar capacity, and arrangement of containers in the storage yard were considered. The FlexSim simulation model of the container terminal was developed, covering the storage yard and the railway track. The analysis shows that the number of containers collected directly from the storage yard has the greatest impact on the train loading duration.
EN
This paper presents an analysis of the acceleration of a fast boat using a simulation model. Mathematical equations of ship motion dynamics with two types of propeller capabilities are developed using MATLAB and Simulink as simulation tools. The equations are extended to include the acting thrust, resistance, propeller’s performance curves, and the PID governor curve for the acceleration manoeuvre. The application models the dynamic differential equations representing the vessel dynamics in one degree of freedom. MATLAB code was used to develop the ship acceleration as a multibody system. Modules of hydrodynamic forces, resistance, moments, and propeller performances were implemented to simulate the ship manoeuvring process. A comparison of the results for the boat’s propulsion performance with two different propellers and the characteristics of the PID governor, which controls the fuel dose in the gas turbines, was carried out. We present a summary including a comparative analysis of the results for the boat dynamics with and without the PID governor. The results obtained here confirm significant discrepancies between the results of numerical simulations with and without the PID governor.
EN
Purpose: The purpose of this paper is to create a simulation model of a packing line in an e-commerce activity from the perspective of a logistics operator, along with identifying recommendations for further model improvement as part of digital transformation. Design/methodology/approach: This paper uses results obtained by simulation analysis of a computer model of a process built in BPMN 2.0 notation. Data for the model was collected from process analysis, analysis of data obtained from WMS and sensors on the packaging line and from participant observation in the process. Findings: Based on the analysis, it can be concluded that the logistics operator is able to create a simulation model of the process and optimise its operations using the simulation results. The model presented can also be the basis for building a Digital Twin in the distribution network for e-commerce flows. Practical implications: The logistics operator can extend its package of services to include the construction of simulation models and, in future, can also take on the task of creating value for the network on the basis of the Digital Twin created. Originality/value: The paper presents a real-life case study related to the first phase of Digital Twin implementation, namely the creation of a simulation model to create value in the flows and improve the logistics processes involved in serving the e-commerce market.
EN
The reliability, safety and economy of the electric vehicle depend on the operation of the electric drive. Diagnosing malfunctions at startup avoid an accident by turning off the system power. Idle testing prevents an accident that may occur while driving. Monitoring the technical states of the electric power supply during the transport process provides an emergency operation mode by redistributing power between its elements. This model presents the results of testing the method of spectral analysis of electrical processes occurring in the power circuit of the electric power supply simulation model. The information content of spectrograms, as a characteristic of the diagnostic parameter, is determined by the options for setting up the FFT analyzer. These options are configured to a maximum frequency switching converter. And other is the sampling period of the spectral characteristic, and the fundamental frequency is selected as multiples of the rotation speed of the electric motor and the switching frequency of the inverter, taking into account the number of phases of the machine. This paper deals with faulty states of electric drive. It is associated with the failure of a functional element, the circuit (breakage or closure) or the deviation of the element parameters from the nominal values. In the first case, the structural identification problem, the system's state, is considered the second - parametric.
PL
Od działania napędu elektrycznego zależy niezawodność, bezpieczeństwo i ekonomia pojazdu elektrycznego. Diagnozowanie usterek podczas uruchamiania pozwala uniknąć wypadku, wyłączając zasilanie systemu. Testy na biegu jałowym zapobiegają wypadkom, które mogą wystąpić podczas jazdy. Monitorowanie stanów technicznych zasilania elektrycznego podczas procesu transportu zapewnia awaryjny tryb pracy poprzez redystrybucję mocy pomiędzy jej elementy. Model ten przedstawia wyniki badań metody analizy spektralnej procesów elektrycznych zachodzących w obwodzie mocy modelu symulacyjnego zasilania elektrycznego. Zawartość informacyjna spektrogramów, jako cecha parametru diagnostycznego, jest określona przez opcje konfiguracji analizatora FFT. Opcje te są skonfigurowane do maksymalnej przetwornicy częstotliwości przełączania. Drugim jest okres próbkowania charakterystyki spektralnej, a częstotliwość podstawowa jest wybierana jako wielokrotność prędkości obrotowej silnika elektrycznego i częstotliwości przełączania falownika z uwzględnieniem liczby faz maszyny. Artykuł dotyczy stanów wadliwych napędu elektrycznego. Jest to związane z uszkodzeniem elementu funkcjonalnego, obwodu (przerwanie lub zamknięcie) lub odchyleniem parametrów elementu od wartości nominalnych. W pierwszym przypadku problem identyfikacji strukturalnej, stan systemu, jest uważany za drugi - parametryczny.
EN
One of the priority tasks in the country's energy economy is the improvement of energy efficiency. Sectoral energy consumption indicators enable the monitoring of the country's energy economy. The analysis of sectoral ODEX indicators is essential for predicting energy savings. The courses of the ODEX indicators and energy efficiency indicators were modeled with stochastic differential equations. Solving the equations using the Euler method enables the simulation of curves in the medium-term horizon. The results of simulation were presented.
PL
Jednym z priorytetowych zadań w gospodarce energetycznej kraju jest poprawa efektywności energetycznej. Sektorowe wskaźniki zużycia energii umożliwiają monitorowanie gospodarki energetycznej kraju. Analiza sektorowych wskaźników ODEX jest niezbędna do prognozowania oszczędności energii. Przebiegi wskaźników ODEX i wskaźników sektorowych efektywności modelowano stochastycznymi równaniami różniczkowymi. Rozwiązanie równań metodą Eulera umożliwia symulację krzywych w horyzoncie średniookresowym. Przedstawiono wyniki symulacji.
EN
The aim of the paper is to present the concept of a digital twin (DT) as part of the Industry 4.0 strategy. In the form of a case study, a digital twin of a production line for the processing of engine blocks is presented, which will serve as a starting point for further research in the field of digitization of production processes. The research part describes the simulation model of the production line with the representation of the material flow as a basis for the creation of a digital twin. The simulation model was used to optimize the production processes of the engine block and to verify the increase in its productivity. A case study implemented through a digital twin enables testing and analysis of changes before they are introduced into real production.
EN
Biodiesel is regarded as a clean fuel alternative to fossil diesel fuel for fewer pollutant emissions of internal combustion engines. The biodiesel type can be made from waste frying oil, thus it has to be done right. Waste vegetable oil can be provided for free or at a low cost by restaurants and food processors that often use frying oils. Animal fat is also available for free or for a nominal fee from grocery stores, restaurants, and butchers who use lots of fats in their cooking. The methyl ester of oleic acid methyl ester (OAME) biodiesel was produced from used vegetable oil using the transesterification process in order to compare the performance of the 67 kW KUBOTA tractor diesel engine when utilizing OAME and fossil diesel. OAME biofuel was used without being mixed. The engine’s reliability metrics and important indicators, including the brake torque, indicated power, brake-specific fuel consumption (BSFC) and burn duration, were identified. Optimal implementation was met by fossil diesel and the tested characteristics were very close. The OAME biofuel performs better in terms of volumetric efficiency and duration of combustion than the conventional diesel. The decision to choose a specific biofuel that is produced from a particular source so largely hinges on its availability and economic feasibility wherever it is used.
PL
Modele symulacyjne systemów transportowych są kluczowym narzędziem do rozwiązywania wielu zagadnień z zakresu zarządzania tymi systemami. Metodologie tworzenia tych modeli wykorzystują zestawy danych zarówno o infrastrukturze transportowej, jak i o popycie na dostawę towarów lub przewozy pasażerów, jednak w tym zakresie wiele czynników uwzględniano na podstawie przypuszczeń z powodu złożoności modelowanych obiektów. W niniejszym artykule opisano podejście do modelowania systemu przewozów towarowych transportem drogowym w skali całej Polski, w oparciu o dane uzyskiwane przez Główny Urząd Statystyczny na podstawie badania TD-E. Takie podejście pozwala uniknąć wielu przypuszczeń dotyczących popytu na przewozy towarowe, ponieważ parametry tego popytu są oszacowywane w oparciu o próbkę reprezentującą populację generalną – zbiór wszystkich podmiotów gospodarczych kraju generujących ruch towarowy. Podstawowe procedury w opracowanym podejściu do modelowania systemu transportu towarowego zaimplementowano w postaci skryptów w języku Python. W wyniku wykorzystania proponowanej metodologii uzyskano model ciężarowego transportu drogowego w skali całego kraju na podstawie danych badania TD-E z roku 2018. Ocenę adekwatności opracowanego modelu przeprowadzono w oparciu o wyniki Generalnego Pomiaru Ruchu z roku 2015 na podstawie współczynnika determinacji jako miary jakości. Uzyskany model charakteryzuje się zadowalającą jakością (wartość współczynnika determinacji wyniosła 0.62), która może być poprawiona po kalibracji funkcji oporu przestrzeni oraz udoskonalenia procedury rozkładu ruchu na sieć drogową.
EN
Simulation models of transport systems are a key tool for addressing many issues in the field of management of these systems. The methodologies for creating such models use data sets on both transport infrastructure and demand for the freights or passenger transport, however, many factors are considered based on assumptions due to the complexity. This article describes the approach to modeling the cargo transportation system for road transport in Poland based on data obtained by the Central Statistical Office from the TD-E survey. This approach avoids many assumptions about the demand as the demand parameters are estimated based on a sample representing the general population – a set of all economic entities generating freight traffic. Basic procedures in the developed approach have been implemented as Python scripts. As a result of the use of the proposed methodology, a country-wide road transport model was obtained based on the TD-E survey from 2018. The adequacy of the developed model was assessed based on the results of the General Traffic Survey from 2015. The obtained model is of satisfactory quality (the coefficient of determination equals 0.62), which can be improved after calibrating the space resistance functions and improving the traffic distribution procedure.
EN
Icing on the overhead contact line exclude the possibility of efficient current collection from the overhead contact line. The effects oficing can result in losses for carriers due to delay or cancellation of trains and also cases of damage to the traction infrastructure and pantographs. Th e existing methods of de-icing the traction network (mechanical, chemical and electrical) are currently ineffective. Therefore, it is necessary to develop a new electrical method that takes into account the detailed current flow in the overhead contact line. This article presents a model for calculating the current flow in the overhead contact line and the resistances of droppers, suspension elements, and distance holders measured on the basis of actual measurements.
EN
This paper presents a quick-and-dirty method to assess the risk of negative aeration effects occurring in twin-tube hydraulic shock absorbers used in passenger cars at the early design stage. The method is intended to be implemented as an engineering calculation tool based on the computational fluid dynamics (CFD) two-dimensional (2D)/three-dimensional (3D) steady-state single-phase model. The CFD model was previously validated with the use of the particle image velocimetry (PIV) experiment. The negative aeration effect is a wellknown issue for automotive and railway shock absorbers manufacturers. It results in uncontrolled on-vehicle vibrations and the deteriorated shock absorber damping characteristic. The major aeration contributor in twin-tube hydraulic shock absorbers is the sliding shim intake valve, which requires design optimization to avoid a negative aeration effect. The method validation was conducted with the customized test rig equipped with a transparent cylinder where the specific sliding intake valve was assembled. The proposed method also requires a lumped-parameter model of a twin-tube shock absorber, which allows to simulate boundary conditions in assessing particular reservoirs of a shock absorber, i.e., pressures and flow balance. The method is implemented as a calculation routine that converts CFD pressure regions into a gas concentration indicator (GCI) using the pressure-density characteristic of an oil-gas emulsion of a shock absorber. GCI is calculated based on the sum of particular 2D/3D grid elements. The method application is to minimize the risk of occurrence of negative aeration effects by avoiding expensive and time-consuming experimental tests. This method can also be used for in-production shock absorbers projects as a part of a continuous improvement cycle or in the case of inefficient shock absorbers claimed by a vehicle manufacturer. The application scope of the method can be extended for arbitrary twin-tube designs of shock absorbers in the automotive and railway industries.
EN
The introduction of environmentally friendly technologies is becoming increasingly necessary to combat global warming and air pollution in cities. The concept of ecologistics is seen as an effective approach to the management of materials and related flows in order to reduce environmental and economic damage to the environment. The sustainable development of green supply chains is based on the use of environmentally friendly types of vehicles, reduction of energy and other resources consumption, optimization of transport and technological processes in delivery systems. As part of the development of green supply chain, it is proposed to transport goods by freight trams, which eliminates the need for heavy trucks in the city, improves traffic conditions and reduces the environmental impact of transport. The research was conducted for the city of Poznan. The distribution system of the city of Poznan operates in conditions of stochastic demand for deliveries from clients and the risk of lack of sufficient supplies in distribution centers. To take into account the specificity of the distribution system of cargo delivery in conditions of uncertainty and risk, a simulation model of the organization of the material flows within the transport system of the city of Poznan has been proposed. The result of simulation is the optimal assignment of clients to the distribution centers, as well as the value of total mileage with the load, which is a random variable. It is assumed that the random variable is distributed according to the normal distribution law. The results were calculated and compared for two variants, i.e. for constant demand and sufficient quantity of cargo in distribution centers, and for variable demand and uncertainty conditions, e.g. insufficient cargo quantity in distribution centers. The purpose of the paper is to develop a simulation model for planning supplies of small consignments of goods by trams implementing green logistics concept with variable demand for transportation. After a short introduction of the problem, the literature review related to the concept of green logistics and requirements of transport and distribution system are presented in section 2. In section 3, the research problem and research methodology are described. Section 4 provides the results of assignment of clients to distribution centers. The paper ends with concluding remarks.
EN
This paper is oriented on very important topics, which nowadays simulation and optimization surely are. First part of this paper is oriented on simulation software Plant Simulation, because this software is one of the best software on the market. Second section deals in detail with the procedure of saw blades production. Third section presents creation of simulation model for selected production process, which is production of saw blades. Final fourth section is about proposals for improvement of saw blade production.
EN
Article presents the simulation model and the study of the basic mechanisms of the GSh-23 aviation autocannon. The research made use of Solid Edge ST9 software and the multibody systems method implemented in it. Simulation of functioning cannon mechanisms was carried out for two variants of forcing a piston mechanism movement by the gunpowder gases. The results obtained are time courses of a bolt and a cartridge belt drive mechanism elements movement. Assumed variants of a piston mechanism movement and elaborated simulation model will be verified in the next (planned) stage of studies basing on the results of the measurements of the experimental kinematic parameters utilising high-speed camera (Phantom) and TEMA software.
EN
The following paper presents a simulation model of a electric battery locomotive dedicated for mining. The mathematical models of a rail vehicle has been shown, with a analytical models describing an electric motor drive train, including battery system, traction and rolling losses. A set of key data for design and validation has been obtained in a simple drive cycle.
EN
Investigations involving the experimental and numerical analysis of inkjet (powder-based) 3DP are relatively limited for cement mortar materials. This study, by using cement mortar specimens, aimed to determine the optimum strength of 3D printed structural members in all three planes by identifying the compressive strength of cubes, the modulus of elasticity and Poisson’s ratio. In addition, this study aimed to analyse and verify the numerical model for 3D printed cementitious mortar (CP) prisms and beams using an inkjet 3D printer by considering the mechanical behaviour of the printed prisms under compression. Robust and optimal mechanical properties of the 3D printed cementitious mortar obtained from laboratory testing were utilised in the simulation of structural components using ABAQUS software. As inputs for simulation, the strength properties of the printed objects in all three cartesian planes were obtained from test results. The obtained results showed that the printed cementitious materials have orthotropic properties and that the results of experiments were consistent with the analytical solutions and hypothesised model for the different geometric shapes. This finding is extremely valuable in determining the optimum features of 3D printed structures.
EN
The present article aims to describe the design of a fuzzy controller used for automated control of the thickness of the extruded polyethylene film effected by the adjustment of the actuator in the cooling ring. In order to determine whether the designed controller operates properly, a model extruder was created and a simulation study was carried out. The Simulink programming environment integrated with Matlab was used for the development of the fuzzy controller and the simulation. The conducted simulation study demonstrated that the implementation of the designed controller would enable the adjustment of thickness on the perimeter of the film tube and quick reaction to possible departure in the assumed film thickness in mass production.
19
EN
This paper presents a dynamic model of a palletised load unit during a static tilt test. The stability (also called rigidity) of a load unit was evaluated. The palletised load unit was built of packages forming layers and protected against disintegration by stretch film. The aim of this study was to compare the results of a static tilt test with a commonly used and recommended dynamic acceleration test.
EN
The article is devoted to the issue of the negative effect of delays in the movement of special rescue vehicles on the effectiveness of their mission. The dependence of the area of fire on the delay of the arrival of firefighters using a fire-rescue vehicle is shown. The cascading graph of route options of special vehicle movement to the place of an emergency call is given. The algorithm of the optimal route choice of the special vehicle motion with given projected delays is offered. Based on the graph theory, probability theory, and the basic principles of traffic organization, the article proposes a new way to determine the optimal route.
first rewind previous Strona / 16 next fast forward last
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.