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Abstract:The paper presents a method for processing acoustic signals which allows the extraction, from a very noisy signal, of components which contain diagnostically useful information on the increased valve clearance of a combustion engine. This method used two-stage denoising of the acoustic signal performed by means of a discrete wavelet transform. Afterwards, based on the signal cleaned-up in this manner, its entropy was calculated as a quantitative measure of qualitative changes caused by the excessive clearance. The testing and processing of the actual acoustic signal of a combustion engine enabled clear extraction of components which contain information on the valve clearance being diagnosed.

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Vehicle fuel consumption is one of the most important operational characteristics of road vehicles. The fuel consumption can be determined by different methods under laboratory conditions or by carrying out drive tests. One of the possibilities to quantify a way of vehicle driving is to analyse the selected parameters of the fuel mixture electronic control system. The objective of the paper is to predict fuel consumption via parameters of throttle position and engine speed. The measurement was carried out in the laboratory of the Department of Road and Urban Transport by using a MAHA roller dynamometer. The result is an estimation of accuracy of such fuel consumption determination and its possible utilisation for a system of assessing the vehicle driving style of drivers.

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Abstract. The article aims to measure the intensity of the exterior noise of a vehicle in motion. It provides the results of the measurements of the external noise of selected vehicles in motion and the impact of selected factors on the sound level of driving. There are done two measurements in the paper. Results from the first one are comparing noise level of 9 passenger cars according to the Directive 71/157/EEC. The second one shows the road surface influence on the exterior noise of moving vehicle where the sound level was measured by a road whose surface was made of slightly degraded concrete, and at a different place of the same road, where the surface was renovated by applying asphalt mix onto it.

The road safety depends on many factors, including the efficiency of the technical system and the disposal of the driver of the vehicle. As wear of most of the vehicle assemblies threatened only with a breakdown, excessive wear of the braking system components may pose a risk of a traffic accident. The article presents a study on the quality of the brake fluid conductivity as a function of temperature and water content conducted for a selected group of vehicles. This group of vehicles was characterized by different production date and had a different of vehicle mileage. We presented the methodology of statistical analysis of the quality of brake fluid tests in selected 38 passenger vehicles in operation.