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1
Content available Influence of fuel injector holes diameter on parameters of combustion process in the cylinder of the marine 4-stroke Diesel engine
Kowalski J.
Journal of Polish CIMEEAC
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2016
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Vol. 11, no 1
95--102
EN
The paper presents an analysis of the influence of the fuel injector nozzle holes diameter on parameters of the brake-up, evaporation and combustion process in the cylinder of the marine 4-stroke Diesel engine. Presented analysis was prepared in the basis on computational fluid dynamic model. Initial and boundary conditions of the model as well as data used to model validation were collected during the laboratory study. Calculations were conducted for nominal fuel holes diameter equals 0.375mm and diameters increased and decreased by 50μm and 100μm respectively. According to presented results the increase of the diameter of fuel nozzle holes causes the increase of fuel Sauter’s mean diameter in the initial stage of the injection process and the decrease of fuel process evaporation. The result of this phenomenon is the slowdown of the initial stage of the combustion process and the decrease of both pressure and temperature of combustion.
2
Content available The theoretical study on influence of fuel injection pressure on combustion parameters of the marine 4-stroke engine
Kowalski J.
Journal of KONES
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2016
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Vol. 23, No. 1
161--168
EN
The manuscript presents the analysis of influence of fuel injection pressure on the combustion parameters of marine 4-stroke diesel engine. Analysis is based on computational fluid dynamic (CFD) model designed on the basis of the motion mesh of combustion chamber of the marine engine cylinder and air inlet and exhaust gas ducts. Presented model consists of models of fuel injection into combustion chamber, breaking-up and evaporation of the fuel, mixing with air and turbulent combustion with heat transfer to construction elements of the engine cylinder. Mentioned CFD model is validated according to boundary and initial conditions taken from direct measurements. The chosen research object is laboratory 4-stroke turbocharged Diesel engine with direct injection of the fuel and mechanically controlled of both cylinder valves and the injector. During the calculation the fuel dose, delivered into the engine cylinder was changed without any other changes in the initial and boundary conditions. This approach to the problem allows to the cause-effect analysis. The results of presented study are as follows: The increase of the fuel injection pressure causes the increase of fuel dose, delivered into the engine cylinder and the increase of intensity of both kinetic and diffusion stage of the combustion process. The result of this is the increase of pressure and temperature of the combustion and significant increase of the NOx fraction despite the decrease of the O2 content in the combustion chamber of the engine.
3
Content available The analysis of the ECFM-3Z combustion model in the marine 4-stroke engine for the exhaust gas composition
Kowalski J.
Journal of Polish CIMAC
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2014
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Vol. 9, no 1
95--102
EN
The paper presents ECFM-3Z combustion model analysis in the marine, 4-stroke diesel engine. The purpose of the modeling was to determine the composition of the exhaust gas. This composition depends on the composition of the combustible mixture, combustion time and thermodynamic conditions prevailing in the engine cylinder during the working process. Mentioned parameters are variable in time and space, and therefore require the use of 3-dimensional model based on the finite volume method, taking into account the fuel injection, brake-up and evaporation, mixing with air, auto-ignition and combustion. All models presented in the literature are adapted to the parameters of relatively small engines. Different marine engine parameters require significant modifications taking into account the heat exchange with the structural elements of the engine, leakage through piston rings and energy losses by riction. It should also be noted that dimensions of the marine engine require careful optimization of spatial moving meshes according to computation time and quality of results. Paper presents influence of mixing time, start of injection and autoignition delay on modeling results of the exhaust gas composition.
4
Content available Assessment of the 3-D combustion model in the marine 4-stroke engine
Kowalski J.
Journal of Polish CIMAC
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2014
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Vol. 9, no 1
79--86
EN
The aim of this research is to formation of the model of combustion process in the marine, 4 -stroke, diesel engine. The chosen object of research is a laboratory AL25/30 engine. For achievement of the aim, laboratory measurements are made and the results are used to determine the boundary and initial conditions. In addition, measurements of the fuel injection shape are made on the test bench and are made a faithful geometric model of structural components of the engine cylinder. The obtained data has been implemented in the three - dimensional model comprising the fuel injection phenomena, the brake - up and the evaporation of fuel, auto - ignition, flame propagation and heat exchange with the structural elements of the engine cylinder. As a result of activities succeeded in creating a model of the combustion process in the cylinder, which has been positively validated due to the maximum combustion pressure and the temperature of the exhaust gases. Obtained results of calculations also allowed verifying the assumption of negligible auto-ignition delay. The adopted ECFM - 3Z model of the ignition and combustion, used for modeling of combustion in diesel engines, showed the calculated size of the auto - ignition delay of 7 - 8 ° CA.
5
Content available remote Complex Object-Based Multidimensional Modeling and Cube Construction
Boukraa D., Boussaid O., Bentayeb F.
Fundamenta Informaticae
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2014
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Vol. 132, nr 2
203--238
EN
This paper presents a multidimensional model and a language to construct cubes for the purpose of on-line analytical processing. Both the multidimensional model and the cube model are based on the concept of complex object which models complex entities of real world. The multidimensional model is presented at two layers: the class diagram layer and the package layer. Both layers are used by a projection operation that aims at extracting cubes: at the package diagram layer, the projection dynamically assigns the roles of fact and dimensions to the complex objects of the multidimensional model whereas at the class diagram layer, it allows designing the measures. We also provide operations that optimize the construction of new cubes by using existing ones. The set of operations for cube construction are expressed by formal operators, thus forming a language. To show the feasibility of our multidimensional model and operators, we present implementation details of a real case study.
6
Content available Zarządzanie dynamiczne : podejście wielowymiarowe
Rafało M.
Ekonomia i Zarządzanie
|
2013
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Vol. 5, no. 1
65--83
PL
Organizacje, chcąc utrzymać przewagę konkurencyjną, muszą stale poszukiwać innowacji w swoich działaniach. Nie dotyczy to tylko oferowania innowacyjnych produktów czy nowoczesnych metod wytwarzania. Są to ważne aspekty budowania przewagi, ale jak pokazują badania, innowacyjność ważna jest także w budowaniu relacji z otoczeniem czy w zarządzaniu operacyjnym. Szybkość działania, monitowanie otoczenia czy innowacyjność to wybrane narzędzia, które wykorzystują organizacje na dynamicznym rynku. Wielowymiarowy model zarządzania w turbulentnym otoczeniu pozwala na pomiar i śledzenie dojrzałości organizacji w poszczególnych aspektach (wymiarach) zarządzania dynamicznego.
EN
Organizations willing to sustain competitive advantage, must endeavor to innovation. Not only they need to offer innovative product or production method, they also must focus on relations with environment and effective operational management. Speed of acting, environmental scanning and innovation are tools used by organizations in turbulent environment. Multidimensional model of high speed management allows measuring and monitoring dynamic capabilities in all areas (dimensions).
7
Content available remote Analiza wybranych nieparametrycznych metod automatycznej klasyfikacji obiektów wielowymiarowych w aplikacji do nieniszczącej detekcji uszkodzeń
Giżewski T., Wac-Włodarczyk A., Goleman R., Czerwiński D.
Przegląd Elektrotechniczny
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2012
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R. 88, nr 9b
234-237
PL
Artykuł przedstawia problematykę nieparametrycznych metod klasyfikacji w odniesieniu do numerycznego modelu obiektu fizycznego. Głównym tematem jest analiza skuteczności algorytmów pod kątem zastosowań w nieniszczącej detekcji uszkodzeń. Szczególną uwagę zwrócono na parametryzację modelu, jako czynnika istotnego przy minimalizacji kosztów procesu uczenia.
EN
The article presents the discussion on nonparametric classification methods in relation to the numerical model of a physical object. The main theme is the analysis of algorithms in applications to non-destructive testing of ferromagnetic materials. The particular attention was given to model parameterization as a significant factor in minimizing the cost of the learning process.
8
Content available The vehicle ride comfort increase at the expense of semiactive suspension system
Podzorov A., Prytkov V., Cherkashina E., Liashenko M.
Journal of KONES
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2011
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Vol. 18, No. 1
463-470
EN
The problem of control by a semi-active suspension for increase a ride comfort of a vehicle is considered. On an example of multidimensional mathematical model of the bus, an efficiency of a semi-active suspension with controllable shock absorbers and pneumatic springs is analyzed. Results of computer simulation of movement of the bus with a semi-active suspension on road with a stochastic profile are presented. Calculations have been executed in the program of modelling of dynamics of systems solid and elastic bodies - FRUND. As conclusions it is possible to notice that the semiactive suspension with controlled under offered laws elastic and damper elements allows to depress considerably dynamic ability to loading spring vehicle parts, thereby, raising its stroke ride comfort, without deterioration of parameters influencing stability and movement roadability. Results of numerical experiment and offered laws of controlling can form a basis for creation structurally concerning simple semiactive suspension systems a not demanding for work of a significant amount of power. The semiactive suspension with controlled under offered laws elastic and damper elements allows depressing considerably dynamic ability to loading spring vehicle parts, thereby, raising its stroke ride comfort, without deterioration of parameters influencing stability and movement roadability.
9
Content available remote Wielowymiarowe modele sterowania zapasami i ich zastosowanie
Wojna A., Kłodzińska A.
Badania Operacyjne i Decyzje
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2005
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nr 2
83-90
PL
W artykule przeprowadzono matematyczną formalizację wielowymiarowych modeli sterowania zapasami z wykorzystaniem procesów sum zmiennych losowych określonych na łańcuchu Markowa. Na podstawie tej formalizacji określono funkcję ryzyka funkcjonowania wielowymiarowych modeli sterowania zapasami. Rozpatrzono również zagadnienie analizy niezawodności funkcjonowania oraz ustalenia optymalnej struktury specjalnego systemu obsługi Markowa za pomocą określenia jego funkcji ryzyka.
EN
The multidimensional stock control that functions in a random Markov environment is considered. The mathematical formalization of this model was considered with the use of sums of the random variables de-fmed on the Markov chains. The authors introduce a definition of risk function of the type of downside risk measures and find the explicit formulas for its determinations. The example of the application of these formulas is provided: the tasks of the reliability and optimal configuration for the queueing problem are regarded. The formulas defining the function by the system parameters were obtained
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