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  • Author: Tomasz Bartkowiak x
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Multi-scale curvature tensor analysis of machined surfaces

Abstract

This paper demonstrates the use of multi-scale curvature analysis, an areal new surface characterization technique for better understanding topographies, for analyzing surfaces created by conventional machining and grinding. Curvature, like slope and area, changes with scale of observation, or calculation, on irregular surfaces, therefore it can be used for multi-scale geometric analysis. Curvatures on a surface should be indicative of topographically dependent behavior of a surface and curvatures are, in turn, influenced by the processing and use of the surface. Curvatures have not been well characterized previously. Curvature has been used for calculations in contact mechanics and for the evaluation of cutting edges. In the current work two parts were machined and then one of them was ground. The surface topographies were measured with a scanning laser confocal microscope. Plots of curvatures as a function of position and scale are presented, and the means and standard deviations of principal curvatures are plotted as a function of scale. Statistical analyses show the relations between curvature and these two manufacturing processes at multiple scales.

Open access
Kinematic model of multiple trailers on a tractor system for production logistics applications

Abstract

This paper demonstrates kinematic analysis of multiple trailers on a tractor system for production logistics. The analysis concerned three different steering systems of the trailers: virtual clutch and drawbar system, conventional clutch and drawbar system, double Ackermann steering system. Designed kinematic models contain various variants of paths: turning at a constant value of the steering angle, changing the steering angle as a result of an approaching collision. Each of these variants also included driving in a straight line after a 90° turn. The validation of the developed kinematic model was done by using a real logistic train, which path was registered via aerial drone. For each of the developed kinematic models, a visualization of drive through the 90° turn was created.

Open access
Validation of simulation model of the filling line failures / Walidacja modelu symulacyjnego uszkodzeń linii napełniania

Abstract

The main objective of the article is to present the methodology of validating a simulation model of failures of serial production line. In case of the investigated object, the simulation model was tested to find technological solutions which could compensate for the impact of failures on the operation of important objects present on the line before a failures occurs. A possible solution may be to introduce a new buffer or to adjust the size of existing buffers. Validation is one of the most significant stages in the process of constructing simulation models, as it concerns the credibility of the model. The article presents the use of disturbances modeling, especially breakdowns and micro-stoppages, in the simulation model. It also shows the statistical distribution applied in the model and defines the validation measurement instrument as well as evaluation criteria. All these features are the major strengths of the article.

Open access
Hypothesised and Actual Changes in the General Motor Parameters of Field Hockey Players During the Training Cycle

Abstract

Introduction. The aim of the study was to determine the changes in selected motor parameters of highly skilled field hockey players during the training macrocycle. It was assumed that the changes in the parameters examined in the study would correspond with the hypothesised variation related to the adaptive changes that were expected to take place. Material and methods. The study involved eleven field hockey players from the KS AZS-AWF Poznań club (age = 22.3 ± 1.1 years; height = 176.5 ± 4.0 cm; weight = 75.2 ± 6.3 kg; %FM = 12.2 ± 3.9%; VO2max = 55.4 ± 4.85 ml/kg/min). The dates of the measurements were agreed on with the trainers, who played an active role in the study, and were consistent with the cycle of planned measurements that were aimed at assessing the implementation of training/competition loads (two measurements during the preparatory period and one during the competition period). We examined the fundamental elements of motor preparation that are considered important in field hockey, that is speed endurance, running speed, and aerobic endurance. These assessments were supplemented by the measurements of lactate concentration in capillary blood as well as those of jumping ability and agility. Results. In most cases, the changes in the actual results corresponded with the hypothesised values adopted for the training. The relationships between the levels of particular parameters of the players’ motor skills were adequate to a great extent. Conclusion. The effects of the training observed both for the entire team and for individual players were generally in line with the goals of the training/ competition loads implemented. Any discrepancies that were found were identified and corrected by regulating individual exercise loads and were monitored in subsequent measurements.

Open access