Rafał Longwic

Recurrence Plots for Diesel Engine Variability Tests

Cycle-to-cycle variations of maximum pressure in a diesel engine are studied by using the methods of recurrence plots and recurrence quantification analysis. The pressure variations are found to exhibit strong periodicities in low frequency bands and intermittent oscillations at higher frequencies. The results are confirmed by wavelet analysis.

THE IMPACT OF THE ELEVATOR GUIDES CONTAMINATION ON THE BRAKING PROCESS DELAY FOR SELECTED PROGRESSIVE GEARS

The authors’ tests results on the impact of the guiding system (the guides) contamination in the friction lift on the delay of progressive gears braking process are presented in this article. The tests were conducted using a free fall method and a test bench built for that purpose. In order to render all working conditions the guiding system of tested gears was lubricated with the most commonly used lubricating agents. Solid grease (SM), mineral oil (OL), the mixture of solid grease and quartz sand (S50) as well as the mixture of mineral oil and quartz sand (O50) were used.

ANALYSIS OF VIBROACOUSTIC SIGNALS RECORDED IN THE PASSENGER LIFT CABIN

The analysis of private tests is presented in the article. The applicable tests refer to accelerations, the level of the sound pressure as well as to the sound power emitted by the passenger lift cabin at different technical conditions of the lift. For a group of lifting devices the accelerations were tested at three axes with the use of an accelerometer. The accelerometer was placed in the central part of the cabin with simultaneous measurement of the acoustic parameters with the sound analyzer equipped with sound volume double microphone probe. An attempt was made to determine the impact of the frame cabin system construction as well as the lift’s technical condition on the recorded parameters. It can allow to establish the limit values of the lift structure parameters under which a rapid drop of comfort takes place, while travelling in the lift as well as to indicate those construction elements the modification of which would affect the improvement of the operation noiselessness.

DIFFERENT MULTIDIMENSIONAL EXPLORATORY TECHNIQUES IN CLASSIFYING VARIABLES INTO QUALITATIVE CRITERIA OF SPARE PARTS SELECTION FOR PASSENGER CARS

The aim of the paper was (1) to compare cluster analysis and factor analysis applied in the classification of variables into quality criteria of spare parts selection for passenger cars and (2) to create a metamodel taking into account the similarities and differences between the results of the carried out analyses. To collect empirical data, a survey questionnaire was used. It was built on the basis of literature overview concerning quality management. Data was processed with the use of multi-dimensional exploratory techniques: cluster analysis and factor analysis. A theoretical implication is a proposed metamodel, which joins the results of both cluster and factor analysis. A practical implication is a possibility of taking an advantage on the obtained results when planning, designing, manufacturing, distributing, selecting and selling spare parts for passenger cars. Paper contribution is the use of exploratory data analysis techniques in the research area and the proposal of the metamodel formalizing quality criteria of spare parts selection for passenger cars. The research showed, that classifications of variables obtained with the use of two multi-dimensional exploitation techniques are different although there are distinct common elements. When using cluster analysis, the following clusters were identified: marketing, economy and utility one (arranged in accordance with the order of linking). While when using factor analysis, the following factors were discovered: utility, marketing, availability and cost factor (arranged in descending way in accordance with the explained variance).