The study presents the evaluation and comparative analysis of engine shaft line performance in maritime transport ships of the same type. During its operation, a technical system performs functions for which it was designed. It goes through different states. Dynamic state changes of a rotational system can be identified by means of its vibration measurement. For this purpose, a research was carried out which involved recording vibrations of the analysed rotational systems. The recordings were used for calculating selected characteristics in the time-domain, where one of the most unique is the value of the normalized mutual correlation function. On the basis of the concentration values, the characteristics which unambiguously determine the ability state were selected for further studies. Then an identification method for rotational system non-coaxiality was proposed. The method involves using fuzzy clustering. According to this method the values of input signal characteristics were used to formulate fuzzy clusters of system ability and inability states. The method can be used for identifying the current state of the system. The study presents the results of the application of this method in engine turbine shaft lines of minesweepers, with the rotational system selected as an example. It needs to be noted that the efficiency of identifying the operating state of the system with this method is higher than with other methods described in the literature by authors who deal with this issue. The research results have a significant impact on the evaluation of mechanical properties of the studied objects and directly affect operational states of mechanical systems, including those installed in minesweepers, thus determining their reliability.

The application of fuels from renewable energy sources for combustion engine powering involves a great demand for this kind of energy while its production infrastructure remains underdeveloped. The use of this kind of fuel is supposed to reduce the emission of greenhouse gases and the depletion of natural resources and to increase the share of renewable energy sources in total energy consumption and thus support sustainable development in Europe. This study presents the results of research on selected performance parameters of transport by internal combustion engines including: power, torque, the emission of sound generated by the engine, the content of exhaust components (oxygen O 2 , carbon monoxide CO, carbon dioxide CO 2 , nitrogen dioxide NO 2 ), and the content of particulate matter (PM) in exhaust emission. Three self-ignition engines were tested. The fuel injection controllers of the tested internal combustion engines were additionally adjusted by increasing the fuel dose and the load of air. The material used in the tests were mixtures of diesel oil and fatty acid methyl esters of different concentration. A statistical analysis was performed based of the results. The purpose of the work was to develop a resulting model for assessing the operation of engines fueled with biofuel and diesel mixtures while changing the vehicle's computer software. A computer simulation algorithm was also developed for the needs of the tests which was used to prognose the state of the test results for variable input parameters. Author Contributions: Conceptualization: Ł.M., M.M.; formal analysis: Ł.M., M.M.; investigation: M.M.; methodology: Ł.M., M.M.; resources: M.M.; visualization: M.M.; writing-original draft: M.M.; writing-review and editing: M.M.Funding: The research did not receive external financing. Conflicts of Interest:The authors declare no conflict of interest.

The structure of combustion engines enables their modernization and, consequently, a return to the idea of plant fuels. Running out of petroleum fuels is an argument opting for resuming the plant fuel concept. Crude oil occupies the first place in the structure of the natural energy sources' consumption [1]. Diesel oil, the share of which in the total processing amounts to from 34% to 41%, while petrol is 20% [2], is the main product of the crude oil's refinement. The European Union predictions indicate an increase in diesel oil use in the transportation sector and maintaining its constant use as an engine fuel. The legal conditionings of the European Union, which determine the biofuel's path of development, have an impact on

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Abstract. The problems discussed in the study are connected with evaluation of complex technical systems functioning, in particular, transport systems. It was assumed that evaluation of their functioning depends on fulfilment degree of selected criteria. Therefore, it is important to determine a set of criteria including their type, number and importance. Since the research object is a public city transport system considered to be a sociotechnical system of the type: human (driver) -machine (vehicle) and the environment , the criteria to be used for the assessment must include behavior of humans, operation of transport means, and the environmental impact. Thus, selection and determination of importance of significant, time variable, measurable and independent characteristics whose values, in a given time moment or a given time interval, define fulfillment degree of the criteria provide the basis for evaluation of such systems functioning. The quality of technical systems functioning in time is assessed on the basis of the criteria fulfilment degree or comparison and classification of different systems of the same type. It needs to be emphasized that the choice of optimal methods for selection of relevant criteria and determination of their impact on the analyzed system functioning is the research subject of study.

Ship large-power steam boiler may serve as an example of complex critical technical system. A basis for rational control of operation of such system is knowledge on its capability of fulfilling the tasks to which it was intended. In order to make

The study deals with the problems connected with modeling and simulation of technical objects operation processes carried out within a certain class of complex technical systems. The analyzed system is a city bus transport system. The study presents a method for assessment of unit costs involved in a technical object’s being in selected operational states. One of the subsets of data to be used for modeling the process of a technical object operational state changes, includes data concerning the costs borne by the system when the object is in the analyzed operational states. In order to determine this data, it is often necessary to modify the system of costs registration used in a given operation system. Since it is a very expensive and log process, a method of initial assessment of indispensable data has been proposed, on the basis of a costs registration method and simulation of the operation process. The study also includes basic assumptions of the operation process model, being an important element of the developed method. The assumptions of the operation model have been formulated on the basis of identification of a real operation system of city bus transport system and experimental tests carried out in system.