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City buses are one of the main means of public transport in cities. As they move in a limited and densely populated area and are intensively exploited, it is particularly important that they are environmentally friendly. There are many ways to reduce emissions from city buses, including the use of hybrid propulsion. Another way is to use low-emission fuels. This article presents the results of the emission tests of an 18 m articulated city bus with a serial hybrid drive fuelled comparatively by conventional diesel fuel and oxygenated fuel containing 10% v/v of triethylene glycol dimethyl ether (TEGDME). The emission tests were carried out during the actual operation of the bus on a route in Poznań (Poland) and over the SORT cycles. The obtained test results were compared also with the results obtained for a conventional bus. The reduction in emissions of some exhaust components was found when the hybrid bus was fuelled with oxygenated fuel during its actual operation on the bus route. There was a reduction in CO emissions by ~50% and NOx emissions by ~10%. Almost identical levels of PM and HC emissions and smoke opacity were observed for both fuels. In the SORT cycles, the differences in the emissions obtained for both types of fuel were small. In general, for the hybrid bus, a lower influence of oxygenated fuel on emissions was recorded than for the conventional bus.

Transport is one of the most burdensome negative sources affecting the natural environment. Long-term exposure of the body to exhaust pollution can cause health problems and, in the worst case, even lead to death. In addition to exhaust emissions, traffic noise is another equally important issue. Due to its nature, variability over time or the design diversity of vehicles in the traffic flow, it is a phenomenon difficult to define. Like exhaust pollution, it affects people's health and quality of life. In addition to its direct impact on the human physical system, it can also cause psychosomatic disorders, which is why a detailed analysis of road noise taking into account the real operation of the vehicle is so important. The paper presents the basic concepts related to the problem of traffic noise in the world, determines the sources of noise in vehicles and the methodology of conducting acoustic road tests. At the final stage of the scientific paper, methods of reducing excessive noise levels in large urban agglomerations were also presented, and the effectiveness of using noise barriers on selected parts of the city road network using proprietary acoustic tests was assessed.

The aim of the publication was to present the effect of the full power characteristics of the internal combustion engine and the traction characteristics of the vehicle on its safety when moving in urban traffic. The movement of the vehicle in the city was characterized, the condition of its movement was presented and the indicators determining the active safety of the moving vehicle were determined. The characteristics of the full power of internal combustion engines with spark ignition and the vehicle traction diagram were analyzed and compared. Then, on the basis of the performed analyzes, the conditions have been defined which must be met in order to be able to recognize that the vehicle is moving safely.

Acoustic and vibration signals taken from engine often provide significant dynamic information on mechanical and thermodynamic system conditions. The failure characteristics with its quantity description point at the nature and intensity of an incorrectness during normal engine operation, giving the basic principles for more accurate process run monitoring and recognition of fault sources influenced on combustion process run. Problems of failure recognition for CI engine systems have been described. Attributes are created for a combustion run, also for malfunctions in a real engine work maps. The additional new feature of a method is connected with taking into account an empirical signal of combustion runs for each cylinder units and having applied advanced procedures of vibroacoustic signal measures. The way of quantification of combustion changes with accompanying process characteristics in different signal domains was approximated. Accurate recognition and separation of fault cases in normal engine work cycles is the first step of a signal qualification. Fault source detection for diesel engine was analyzed and its accuracy was considered to generate the features most sensible for a process changes. The obtained analyses prove that it is capable to extract fault components from vibroacoustic signal run and precisely calculate its intensity point estimators.

The subject of the considerations described in the paper is the problem of early detection of abnormalities and damages during operation process of the turbo diesel engine with small volume displacement and direct fuel injection, which is used in modern LDV vehicles dedicated especially for urban areas, in the context of present and future requirements for a technical object diagnostics, taking into account the criteria of optimizing overall efficiency, toxic compound emission and safety of the object in real conditions of its operation. The paper presents the results of empirical research of vibroacoustic signal application to the diagnostic evaluation of correctness of short-time engine main processes. The evaluation of the combustion process variability from structural and operational abnormalities by using dimensionless estimates of a vibration process was conducted, and functional characteristics necessary to built the diagnostic algorithm in accordance with the requirements of on-board diagnostics were obtained.

Improved lubrication parameters of lubricating oils due to the addition of carbon nanotubes (CNT) have been demonstrated in the past. This benefit, however, is short-lived due to self-induced re-agglomeration of CNTs in large concentrations in the oil. In this work the authors investigate the friction effects at trace amounts of CNT (as low as 0.03%). At such level the re-agglomeration effects are efficiently suppressed. Surprisingly, at such extreme low CNT concentration levels, a relatively large engine friction reduction of 6% was still observed. Moreover, a very strong vibration reduction of up to 30% was measured in the fired engine test. Full understanding of these results will require extensions/revisions of the existing models, which will pave the way to a new class of improved lubricants.

The possibilities of the vibration accelerations signals parameters application for the assessment of thermodynamic processes in the turbojet engine of the F-16 airplane given in its real work conditions have been presented in the paper. The aim is early detection of negative changes in the mixture formation and combustion processes taking place at the aircraft turbojet engine to maintain the high overall efficiency and safety of aviation tasks. Diagnostics of combustion and injection processes have been conducted for stationary engine investigations in the way to obtain quantity measures (dimensional and non-dimensional) and characteristics for these phenomena in the process value domain. The quality of the fuel injection and combustion, expressed in engine operation parameters of the best sensitivity, has been linked to the particular vibration impulse and energy representations, giving the important functional relations for building a diagnostic system for turbojet F-16 airplane engines for real operating conditions. The results show the proposed method assures early and accurate diagnostics for engine dynamic characteristics, making possible diagnostic system application. The diagnostic system design for combustion and injection processes monitoring and malfunctions detections has been proposed.

The issues of monitoring the processes of combustion and fuel injection in a turbojet engine of a multi-purpose aircraft in real conditions of its use with the use of selected characteristics and measures of acoustic signal processes have been described in the paper. The aim is early detection of sources and parametric assessment of the intensity of negative changes in the above-mentioned main processes and in the components of the aircraft propulsion system, taking into account contemporary criteria for improving the safety of the implementation of the aviation task. Appropriate functional relations have been built for acoustic characteristics that are a response to specific sources of changes in the creation of a combustible mixture and its combustion process, which can be used in their continuous diagnostics, in accordance with the criteria of the highest operational efficiency of the thermodynamic and mechatronic system, including ensuring safety improvement. Operational indicators of the highest sensitivity for both processes have been linked to the particular acoustic impulse and energy parameters and frequency spectra, for which specified energy quantum is transferred by means of vibrating particles. The results demonstrate the proposed method assures early and accurate diagnostics for engine dynamic characteristics. The built procedures for combustion and injection projections in the acoustic discrete and continuous representations, both in process value and frequency domains, make the obtained findings valid for on-board fault-diagnosis system building.

The paper describes the assessment of the main processes taking place in a IC engine. The article concerns vibroacoustic processes. Authors chosen vibration ones to the research. In view of the characteristics that the above processes have for the diagnosis of the slow andfast processes taking place during combustion, it was necessary to take into account them for periodic and on-line analyses of technical state and correctness of the engine dynamic processes run. Evaluations of the possibility of the method application were performed in the point of view of the diagnostic analysis and its use in the diagnostic system for combustion process and in the aspect of the limitation of excessive emission sources (occurred by incorrect processes runs or by functional characteristics decrease of the object or by potential failures of the elements and subassemblies during exploitation). Method analysis of vibration acceleration generated in an engine, basing on diagnostics theory use, with the help of which quantitive components obtained from the frequency-domain processes runs were searched. Diagnostic estimators were the measures of the quantity assessment, changes of which were the subject ofpresented analyses. Limits and qualification guidelines of an incorrect process are also in a paper. Diagnostic algorithms of misfire detection for the present and future vehicles combustion engines (also for hybrid vehicles) and in the aspect of OBDIII or OBMsystems application are taken into account.

The paper describes the method of a sea boats online diagnostic with the use of the main and accompanying processes analyses. The paper concerns injection and combustion processes taking place in internal combustion engines of the military boats. Authors chosen vibroacoustic processes in the research to obtain the important diagnostic information on the above processes runs and their correctness in the sources of a drive of the HDV off-road water transport vehicles. The specified method of a digital data acquisition for dynamic processes in such combustion engines and sort of diagnostic parameters taken into account were basis of the required empirical research process and further signal analyses. High accuracy of the measurement methodology and process with additional conditions caused the authors could take the obtained signals to the parallel, combustion engineering and vibroacoustic engineering process, according to which they extract important information on the combustion processes runs and their problems. Identification of such problems and its type was helpful to build algorithm of the diagnostic assessment of such processes in the point of view of building diagnostic system for such military boats with the regime of the efficiency of the energy changes and emission control in the all exploitation period.

The paper describes the problem of the combustion process diagnostics in diesel engines of HDV vehicles in the aspect of the environment protection and misfire detection as well as its use in the OBD/EOBD systems. Vibroacoustic processes were taken into consideration and the chosenparameters ofthe vibration signals obtainedfrom the specified locations in the engine were the diagnostic estimators of the process changes. The paper discusses the diagnosis of the course of the process from the point of view of the OBD system requirements, in order to check the possibility of using the deterministic chaos method and vibroacoustic processes in on-line diagnostic processes and in the design of combustion monitors in diesel locomotive engines. This stage of the scientific studies was done to check the sensitivity of selected non-linear methods for the process changes or their lack. The paper also presents the signal analyses, limitations of the method, criteria of the process qualification and its accuracy. Diagnostic algorithms of misfire detection and possibility of its practical use in contemporary vehicle drivertrains have been described as well.

Niniejszy artykuł dotyczy możliwości zastosowania metody oceny procesu spalania i jego braku w silnikach spalinowych pojazdów szynowych, bazującej na wykorzystaniu parametrów sygnału drganiowego. Zamieszczono w nim wyniki badań silnika spalinowego lokomotywy w warunkach jej eksploatacji. Wykazano możliwość zastosowania estymat sygnału drganiowego do oceny braku spalania w silniku spalinowym oraz dużą wiarygodność diagnostyki procesu spalania za pomocą powyższej metody.

The article concerns the possibilities of use of the method being able to assess of the combustion process and its lack in internal combustion engines of railway traction vehicles, that bases on the use of vibration signal parameters. The paper includes the results of research conducted on the engine test bench with a single cylinder research and compression-ignition engine with direct injection, and tests for the engine of a diesel locomotive in the exploitation condition. Possibility of the vibration signal estimators application to the assessment of a combustion process lack in an internal combustion engine and a high reliability of combustion process diagnostics basing on the above method have been proved.

The proper strategy of internal combustion engine operation is one of the basic aims being taken into account in a design process, in a phase of building the first design of a specified engine, verification of geometrical and operational parameters for a real object (comparing to a brief foredesign) to the moment when one obtains the final design of the engine. This particular purpose of such process is also important during combustion engine operation in a stationary or traction applications. Undoubtedly, the assessment of the main processes taking place in such engines, especially combustion processes runs, in the point of view of the correct diagnosis and engine operation management, is convergent with present and future combustion engines design trends and with the world environment protection requirements. That is why the paper concerns the assessment of a combustion process correctness in a direct injection compression-ignition engine on the basis of vibration signal runs and their digital processing. The method of such diagnosis was implemented to identify quality and quantity changes of main processes characteristics and diagnostic parameters regarding with engine work conditions, operation time and with some problems appearing in specified engine working cycles. The paper gives scientific solutions for precise diagnosis of combustion process correctness and some failures that could take place in combustion of compression-ignition and direct injection engines. Reliability of a method for these scientific tasks was checked for research conducted in stationary engine operation conditions.