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Sporttester with Bluetooth LE
Blažek, Vojtěch ; Komosný, Dan (referee) ; Krajsa, Ondřej (advisor)
This thesis deals with the design of a sporttester, which is a device capable of calculating the cadence of the taken steps and monitoring the impact force of foot on the ground while running. Exposure to long-term strong impacts while running can cause serious fatigue fractures of the hip, calf bone or the foot area. The purpose of the sporttester is to monitor and signal strong impacts to the runner, thus helping to prevent fatigue fractures. The aforementioned features are evaluated based on the change in acceleration measured by the accelerometer. The calculated values of step cadence, running speed and impact force are sent via Bluetooth Low Energy to a compatible mobile application.
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Analysis of dynamic strength of friction knots used in military climbing
Telvák, Radek ; Michalička, Vladimír (advisor) ; Braum, Zdeněk (referee)
Title: Analysis of dynamic strength of friction knots used in military climbing Objectives: The aim of this work is to determine the resulting impact force generated by selected friction systems at different values of the fall factor. To calculate what maximum values of auxiliary Reep cord length and maximum load weight can be achieved without system failure. Determine the correlation between the magnitude of the impact force and the slip length. Methods: This thesis describes an experiment in which the resulting impact force acting on a friction system at different drop factors was determined. A 6mm Reep cord and an 11mm rope and friction knots used in military climbing techniques were selected for analysis. Testing was carried out in a polygon on a drop tower. Each of the friction knots was subjected to 5 tests at the same fall factor. The individual knots were statistically compared with each other in terms of impact force and slip. Using direct proportionality, the maximum possible values of the auxiliary Reep cord length and the weight of the load were determined. A correlation analysis was used to establish a correlation between impact force and slip. Results: It was found that at all measured values of the fall factor, the Twist prusik achieved the lowest values of the resulting impact force...
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Comparison of impact force values amongst improvised and traditional rope fixed instalations
Kučera, Václav ; Michalička, Vladimír (advisor) ; Gajdošík, Jan (referee)
Title: Comparison of impact force values amongst improvised and traditional rope fixed instalations. Objectives: The aim of this work is to measure the resultant impact forces acting on a climber during a fall from an improvised fixed installation, using an improvised ferrata set, by means of an experiment. Furthermore, to compare the measured impact force values with those already measured for traditional fixed installation using ferrata fall arresters. Methods: This paper describes an experiment in which the actual impact force acting on a climber during a fall from an improvised fixed installation using an improvised ferrata set was determined. The aim of the first experiment was to determine the values of the impact forces for a given length of fall. At the same time, to determine the maximum value of the impact force at which the reep cord forming the improvised ferrata set will not break. The second test aimed to determine the resultant values acting on the load when falling into the sag from the dynamic rope, which were then used to compare with the results of the first test. The purpose of the last test was to compare the resultant values of improvised and traditional fixed installations. Each fall length was tested for ten trials whereby after each fall the textile material was replaced...
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Sporttester with Bluetooth LE
Blažek, Vojtěch ; Komosný, Dan (referee) ; Krajsa, Ondřej (advisor)
This thesis deals with the design of a sporttester, which is a device capable of calculating the cadence of the taken steps and monitoring the impact force of foot on the ground while running. Exposure to long-term strong impacts while running can cause serious fatigue fractures of the hip, calf bone or the foot area. The purpose of the sporttester is to monitor and signal strong impacts to the runner, thus helping to prevent fatigue fractures. The aforementioned features are evaluated based on the change in acceleration measured by the accelerometer. The calculated values of step cadence, running speed and impact force are sent via Bluetooth Low Energy to a compatible mobile application.
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Measurement of the impulsive force generated by colapsing bubble close to a solid boundary
Müller, M. ; Unger, J. ; Holata, J. ; Zima, Patrik
The article presents experimental results of the acoustical and optical study of cavitation bubble collapse close to a solid boundary in water. The bubble was generated by discharge of low-voltage capacitor into a couple of wires closing a simple circuit. Different distances from the solid wall and different maximum bubble radii were studied. The bubble radius was studied using time-resolved photography and by PVDF film sensor glued on the solid boundary. The illumination was provided by high-power led diode. Synchronization of the system was provided by pulse generator connected to an oscilloscope. The impact power of the bubble to the wall was estimated from the time-resolved photography of the bubble and from the PVDF film sensor signal. The PVDF film sensor calibration was performed by a pendulum test to estimate the impact force.
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