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    Wyświetlanie 1-9 z 9
    Tytuł:
    The semi-Markov model of energy state changes of the main marine internal combustion engine and method for evaluating its operation during ship voyage
    Autorzy:
    Girtler, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/260072.pdf
    Data publikacji:
    2011
    Wydawca:
    Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
    Tematy:
    operation
    energy
    semi-Markov process
    piston internal combustion engine
    Opis:
    The article presents a method for evaluating the operation of internal combustion engines used as the main engines in the propulsion systems of sea-going ships in various operating conditions. This method enables calculating the engine operation value based on the theory of semi-Markov processes and mathematical statistics. What is noteworthy, the operation of the examined internal combustion engines is compared to a physical quantity which is expressed in the form of a number with the measure unit called joule-second. a model having the form of a semi-Markov process is proposed to describe the energy state changes taking place in the main engines during their operation. Also proposed is the use of the point and interval estimation at a given confidence level â for determining the value of the energy converted in the engine during its operation for the known and unknown standard energy deviation treated as the random variable. The semi-Markov model of changes of the energy converted in the engine during its operation is presented in a general form. The above model was used for determining the ship’s main engine operation, which is in the examined case a function of the energy converted in particular energy states, the expected value of the time of duration of these states and the probability of their existence. These probabilities compose the limiting distribution of the semi-Markov process, the values of which are the specified main engine energy states.
    Źródło:
    Polish Maritime Research; 2011, 4; 36-42
    1233-2585
    Pojawia się w:
    Polish Maritime Research
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Application of theory of semi-Markov processes to determining distribution of probabilistic process of marine accidents resulting from collision of ships
    Autorzy:
    Girtler, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/260618.pdf
    Data publikacji:
    2014
    Wydawca:
    Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
    Tematy:
    critical manoeuvre
    port
    probability
    semi-Markov process
    sea-going ship
    Opis:
    In this paper is presented possible application of the theory of semi-Markov processes to elaborating an eight-state model of the process of occurrence of serviceability state and unserviceability states of sea-going ships making critical manoeuvres during their entering and leaving the ports. In the analysis it was taken into account that sea-going ships are in service for a very long time t (t → ∞). The model was elaborated to determine the probability (P0) of correct execution of critical manoeuvres during ship’s entering and leaving the port as well as the probabilities Pj(j = 1, 2, 3, …, 7) of incorrect execution of critical manoeuvres by a ship, that leads to marine accidents. It was assumed that such accidents result from: ship’s grounding on port approaching fairway, collision with a ship on port approching fairway, collision with a pierhead during passing through port entrance, collision with a hydrotechnical structure during ship’s passing through port channels, collision with a port quay during coming alongside it and collision with a ship already moored to the quay. The probability (P0) was assumed a measure of safe execution of a critical manoeuvre. The probability characterizes possibility of avoiding any collision during ship’s entering and leaving the port. The probability Pa = 1 – P0 was assumed a measure of occurrence of a collsion and - consequently - marine accident. The probability Pa was interpreted as a sum of the probabilities Pj(j = 1, 2, 3, …, 7) of occurrence of all the selected events. In summing up the paper, attention was drawn to its merits which - in opinion of this author - are crucial for research on real process of accidents during entering the port and leaving it by sea-going ship in difficult navigation conditions.
    Źródło:
    Polish Maritime Research; 2014, 1; 9-13
    1233-2585
    Pojawia się w:
    Polish Maritime Research
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Identifying the issue of reducing the emission of harmful compounds in the exhaust gas from marine main engines and description of the emission process of these compounds in probabilistic approach
    Autorzy:
    Łosiewicz, Z.
    Powiązania:
    https://bibliotekanauki.pl/articles/258884.pdf
    Data publikacji:
    2017
    Wydawca:
    Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
    Tematy:
    ship’s main engine
    semi-Markov process
    Diesel engine
    harmful substance
    Opis:
    The article discusses the results of actions performed by marine engine manufacturers towards the reduction of emission of harmful substances in the exhaust gas from these engines. The discussion is limited to main engines produced by MAN B&W. A model is proposed to describe the process of emission of harmful substances from Diesel engines based on the semi-Markov process, discrete in states and continuous in the operating time. The states of this process are: engine ability state (s1) and engine inability state (s2). A method to calculate probabilities P1 and P2 of the appearance of states s1 and s2 is proposed. State s1 is interpreted as corresponding to the inequality ekek(dop), where ek represents the mass of harmful substances emitted by the engine during its operation and ek(dop) is the maximum mass of emission of these substances permitted by relevant regulations.
    Źródło:
    Polish Maritime Research; 2017, 2; 89-95
    1233-2585
    Pojawia się w:
    Polish Maritime Research
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Probabilistic concept of defining the situations possible to occur during operation of floating docks
    Autorzy:
    Girtler, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/260295.pdf
    Data publikacji:
    2005
    Wydawca:
    Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
    Tematy:
    floating dock
    safety
    model
    reliability
    technical object
    semi-Markov process
    technical state
    Opis:
    In this paper possibility to assess safety of floating docks as a result of application of the theory of semi-Markov processes both in the phase of their designing and operating, is outlined. Formal description of the situations which may occur during service of floating docks both those intended for building and repairing the ships, was presented. The following situations were distinguished : normal, complicated, hazardous, emergency and disastrous. A model of changing the distinguished situations was proposed in the form of a semi - Markov process with discrete set of states, and continuous with time. The mentioned situations are values of the process. An operational safety measure for dock was formulated in the form of the probability of the event consisting in occurrence of normal or complicated situation. It was proved that assessment of probability of occurrence of particular situations is possible.
    Źródło:
    Polish Maritime Research; 2005, S 1; 34-38
    1233-2585
    Pojawia się w:
    Polish Maritime Research
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Limiting distribution of the three-state semi-Markov model of technical state transitions of ship power plant machines and its applicability in operational decision-making
    Autorzy:
    Girtler, Jerzy
    Powiązania:
    https://bibliotekanauki.pl/articles/258958.pdf
    Data publikacji:
    2020
    Wydawca:
    Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
    Tematy:
    decision
    probability
    ship power plant machine
    semi-Markov process
    ship internal combustion engine
    Opis:
    The article presents the three-state semi-Markov model of the process {W(t): t > 0} of state transitions of a ship power plant machine, with the following interpretation of these states: s1 – state of full serviceability, s2 – state of partial serviceability, and s3 – state of unserviceability. These states are precisely defined for the ship main engine (ME). A hypothesis is proposed which explains the possibility of application of this model to examine models of real state transitions of ship power plant machines. Empirical data concerning ME were used for calculating limiting probabilities for the process {W(t): t > 0}. The applicability of these probabilities in decision making with the assistance of the Bayesian statistical theory is demonstrated. The probabilities were calculated using a procedure included in the computational software MATHEMATICA, taking into consideration the fact that the random variables representing state transition times of the process {W(t): t > 0} have gamma distributions. The usefulness of the Bayesian statistical theory in operational decision-making concerning ship power plants is shown using a decision dendrite which maps ME states and consequences of particular decisions, thus making it possible to choose between the following two decisions: d1 – first perform a relevant preventive service of the engine to restore its state and then perform the commissioned task within the time limit determined by the customer, and d2 – omit the preventive service and start performing the commissioned task.
    Źródło:
    Polish Maritime Research; 2020, 2; 136-144
    1233-2585
    Pojawia się w:
    Polish Maritime Research
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    A model of fuel combustion process in the marine reciprocating engine work space taking into account load and wear of crankshaft-piston assembly and the theory of semi-Markov processes
    Autorzy:
    Girtler, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/259557.pdf
    Data publikacji:
    2016
    Wydawca:
    Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
    Tematy:
    engine load
    marine internal combustion engine
    probability
    semi-Markov process
    crankshaft-piston assembly
    Opis:
    The article analyses the operation of reciprocal internal combustion engines, with marine engines used as an example. The analysis takes into account types of energy conversion in the work spaces (cylinders) of these engines, loads of their crankshaft-piston assemblies, and types of fuel combustion which can take place in these spaces during engine operation. It is highlighted that the analysed time-dependent loads of marine internal combustion engine crankshaftpiston assemblies are random processes. It is also indicated that the wear of elements of those assemblies resulting from their load should also be considered a random process. A hypothesis is formulated which explains random nature of load and the absence of the theoretically expected detonation combustion in engines supplied with such fuels as Diesel Oil, Marine Diesel Oil, and Heavy Fuel Oil. A model is proposed for fuel combustion in an arbitrary work space of a marine Diesel engine, which has the form of a stochastic four-state process, discrete in states and continuous in time. The model is based on the theory of semi-Markov processes.
    Źródło:
    Polish Maritime Research; 2016, 3; 50-57
    1233-2585
    Pojawia się w:
    Polish Maritime Research
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Identification of damages of tribological associations in crankshaft and piston systems of two-stroke internal combustion engines used as main propulsion in sea-going vessels and proposal of probabilistic description of loads as causes of these damages
    Autorzy:
    Girtler, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/259908.pdf
    Data publikacji:
    2015
    Wydawca:
    Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
    Tematy:
    probability
    friction associations
    crankshaft and piston system
    semi-Markov process
    marine internal combustion engine
    wear
    Opis:
    The article discusses damages of essential tribological associations in crankshaft and piston systems of large power two-stroke engines used as main engines, which take place during transport tasks performed by those ships. Difficulties are named which make preventing those damages impossible, despite the fact that the technical state of engines of this type is identified with the aid of complex diagnostic systems making use of advanced computer technology. It is demonstrated that one of causes of the damages is the lack of research activities oriented on recognising random properties of the loads leading to those damages. A proposal is made for the loads acting at a given time ton tribological associations in crankshaft and piston systems of internal combustion engines used as main engines to be considered as random variables Qt. At the same time the loads examined within a given time interval tr ≤ t ≤ tz would be considered stochastic processes {Q(t): t ≥ 0}. Essential properties of the loads of the abovementioned tribological associations are named and explained by formulating hypotheses which need empirical verification. Interval estimation is proposed for estimating the expected value E(Qt) of the load Qt acting at time t. A relation is indicated between the mechanical load and the thermal load acting on tribological associations in the ship main engine crankshaft and piston system. A suggestion is formulated that a stochastic form of the relation between these types of load is to be searched for, rather than statistic relation, and a proposal is made to measure the intensity (strength) of the stochastic relation using the Czuprow’s convergence coefficient.
    Źródło:
    Polish Maritime Research; 2015, 2; 44-54
    1233-2585
    Pojawia się w:
    Polish Maritime Research
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The semi-Markov model of the process of appearance of sea-going ship propupsion system ability and inability states in application to determining the reliablity of these systems
    Autorzy:
    Girtler, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/259071.pdf
    Data publikacji:
    2013
    Wydawca:
    Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
    Tematy:
    reliability
    semi-Markov process
    state of ability
    state of inability
    sea-going ship
    ship propulsion system
    Opis:
    The article presents possible application of the theory of semi-Markov processes in creating the eight-state model of the process of appearance of the propulsion systems ability and inability states on sea-going vessels performing transportation tasks in a relatively long operating time t (t → ∞). The model has been proved to be able to be successfully used for determining the reliability of the abovementioned systems. The probability of faultless operation in time t was assumed the measure of system reliability. Operating situations of sea-going vessels were characterised, with special attention being paid to the fact that the loads of propulsion system components of these vessels are of random nature. These loads lead to damages which for this reason were also considered random events. It was also assumed that the damages provoke the appearance of states of inability of particular ship propulsion system components which means that these states are random events as well. The states of ability of a given ship propulsion system have been assumed to exist when all components of this system are in the state of ability. In case when at least one component is in the state of inability, the entire system is in the state of inability. Conditions were formulated for the reliability model of an arbitrary system to be able to be worked out in the form of the semi-Markov process. The need for the use of technical diagnostics in reliability examination of sea-going ship propulsion systems was indicated. In conclusions, certain qualities of the article were highlighted which are, in author’s opinion, of highest importance in reliability examination of sea-going ship propulsion systems.
    Źródło:
    Polish Maritime Research; 2013, 4; 18-24
    1233-2585
    Pojawia się w:
    Polish Maritime Research
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The matter of decision-making control over operation processes of marine power plant systems with the use of their models in the form of semi-Markov decision-making processes
    Autorzy:
    Girtler, Jerzy
    Rudnicki, Jacek
    Powiązania:
    https://bibliotekanauki.pl/articles/1551829.pdf
    Data publikacji:
    2021
    Wydawca:
    Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
    Tematy:
    semi-Markov model
    ship main engine
    operation process
    stochastic process
    operational state
    technical state
    marine power plant equipment
    Opis:
    The article presents the possibility to control the real operation process of an arbitrary device installed in the marine power plant based on the four-state semi-Markov process, being the model of the process, which describes the transition process of operational states of the device (ek , k = 1, 2, 3, 4), and the transition process of its technical states (sl , l = 1, 2, 3). The operational states ek (k = 1, 2, 3, 4) have the following interpretation: e1 – active operation state resulting from the task performed by the device, e2 – state of ready-to-operate stop of the device, e3 – state of planned preventive service of the device, e4 – state of unplanned service of the device, forced by its damage. Whereas the interpretation of the technical states sl (l = 1, 2, 3) is as follows: s1 – state of full serviceability of the device, s2 – state of partial serviceability of the device, and s3 – state of unserviceability of the device. All these states are precisely defined for the ship main engine (SG). A hypothesis is proposed which justifies the use of this model to examine real state transitions in marine power plant device operation processes. The article shows the possibility to make operating decisions ensuring a rational course of the device operation process when the proposed model of this process and the dynamic programming method based on the Bellman’s principle of optimality are applied. The optimisation criterion adopted when making operating decisions is the expected profit to be gained as a result of functioning of the device in the time interval [τ0 , τm], being the sum of the expected profit gained in interval [τ0 , τ1 ] and to be gained in interval [τ1 , τm].
    Źródło:
    Polish Maritime Research; 2021, 1; 116-126
    1233-2585
    Pojawia się w:
    Polish Maritime Research
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-9 z 9

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