National Repository of Grey Literature 40 records found  1 - 10nextend  jump to record: Search took 0.00 seconds. 
Specifics of accidents Agricultural Technology
Tamáši, Adam ; Polcar, Adam (referee) ; Vémola, Aleš (advisor)
Master’s thesis focuses on the specifics of agricultural machinery accidents. The introductory part defines agricultural machines and its basic characteristics. It also analyzes specific technical regulations that govern the use of these machines in traffic. The experimental part then describes the methodology and interprets the results of conducted experimental measurements on driving dynamics of a tractor with carried accessory. These measurements consist of a break test in straight line, evasion manoeuvre and acceleration while turning left. The focus was given to not just the acceleration values, but also to the influence of the carried accessory, the load on the front axle or the tire pressure. The analysis of the findings made compares the results with the driving dynamics of ordinary passenger cars and provides a detail dissection of the most frequent causes of agricultural machinery accidents.
Dynamic parameters of sports and conventional vehicles
Tesař, Michal ; Janoušek, Michal (referee) ; Vémola, Aleš (advisor)
This master´s thesis is focused on chosen dynamic parameters of a sport vehicle represented by student formula Dragon 7 and comparison of these parameters with conventional vehicles represented by two exemplars of ŠKODA Superb III. Driving tests used for the comparison are simulating the real driving situations from the roads in order to possibly use those for the road accident analysis in the future. All the measurements were taken under lower adhesion conditions which might help solving of the road accidents under such conditions in the future. There is also a description of vehicle driving systems and components which have an influence on the vehicle´s driving dynamics incorporated in the thesis.
Analysis of Non-Standard Braking Intervention into the Brake System
Kortán, Daniel ; Bradáč, Albert (referee) ; Vémola, Aleš (advisor)
This master’s thesis focused on the issue of the possible conversion of liquid brake systems, in the form of replacement of wheel brakes. The first part focused on the function and description of the construction of different types of brakes. The second part is focused on description the types of brake system testing and the regulations regarding brake systems. The last part focused on the measurement of both vehicles and comparison of the results with the calculations.
Analysis of set of factors affecting safe longitudinal distance between vehicles
Zemánek, Lukáš ; Kovanda, Jan (referee) ; Bradáč, Albert (referee) ; Vémola, Aleš (advisor)
The doctoral thesis deals with problems of a safe longitudinal distance between vehicles. It includes an analysis of a set of factors influencing the safe distance between vehicles and is concerned with a research of effect of many of these factors on observance of the safe longitudinal distance between vehicles. In connection with these factors, this work deals with the solution of this issue in neighbouring countries through statutory measures, then with statistical analysis of traffic accidents in the Czech Republic caused by non-observance of the safe distance, also problems of assistance systems operating in this area, and subsequently, based on the findings, there are recommended suggestions of actions to increase safety in this area of road transport.
Deceleration acting on the passengers in the frontal impact
Coufal, Tomáš ; Vémola, Aleš
The article is processed in sequence to article Mechanics of car frontal crash from conference (Expert Forensic Science) 2010 and deals with the deceleration acting on the passengers in the frontal impact. There is explained principle of obtaining the maximal deceleration acting on the passengers in the vehicle during the frontal impact from damage of the vehicle. From the point of view size of deceleration during the impact is obtained difference between restrained and unrestrained passenger. For an example about it what size achieves values of deceleration acting on the passengers during the frontal impact are processed and evaluated data from the dummy from the real crash test of the vehicle.
Analysis of impact of active safety elements in vehicles on pedestrian protection for traffic accident investigation
Vertaľ, Peter ; Kovanda, Jan (referee) ; Kropáč, František (referee) ; Vémola, Aleš (advisor)
Increase the probability of prevent road accidents by installing autonomous systems in a vehicles is the current trend in the field of active safety with a focus on pedestrian safety. The work deals with the evaluation of intervention of active safety systém for pedestrian detection assembled in series production. Benefit of active safety systems to prevent road accidents can be achieved, for example, early warning driver of a potential collision situation sufficiently in advance to reaction and post-maneuver (braking, yaw, ..). The evaluation of the intervention of active safety systems, which aim to prevent an accident with a pedestrian is necessary to experimentally evaluate the behavior of these systems. The main objective of this work is to test the selected systém based on different types of reál accidents. Atthe time of the measurements and present, are not for experts and specialists in the field of road traffic accidents publicly accessible data about the behavior of such a systém. The work aims to evaluate the behavior of the Volvo systém in inducing reál traffic situations. For the evaluation of this systém are precisely analyzed fatal traffic accidents with pedestrians in the urban area (speed of vehicles up to 60 km/h). Simulated traffic situations by their nature cover the most common critical situations in urban traffic. Expert community and the professionals who deal with the solution of traffic accidents receive this work valuable data to deal with such accidents. Based on these measurements give more expert input data to solve a collision with a pedestrian. The basis for understanding the behavior are created graphs of distance, speed and time at a key moment of the collision. These key moments include entry a pedestrians to driving corridor of the vehicle, system's response to conflict situations, warn the driver and then autonomously brake active safety systém
Processing of selected terminology at road accident analysis
Tokař, Stanislav ; Šachl, Jindřich (referee) ; Kropáč, František (referee) ; Drahotský, Ivo (referee) ; Vémola, Aleš (advisor)
The thesis deals with the terminology used in forensic engineering practice at the analysis of road accidents. It means defining the concepts describing specific expert research in the area of car accident analysis such as the option of evasive action and the possibility of preventing collision. Further on, the thesis focuses on the terminology used in areas closely related to analysis of road accidents namely dealing with cases of criminal activities in the field of motor vehicle insurance from an expert point of view. In this area, terms such as extent of the damage, character of the damage, correspondence of the damage and the technical acceptability of accident, are solved. These terms constitute a formal process that can serve as a tool for experts when dealing with such cases. In addition, selected terms from the technical-legal area, which the experts often encounter, are processed here. At the same time, there is no uniform approach to their evaluation from a technical perspective. Here, there is a possibility of setting the limits of a sudden change of speed and a sudden change of direction.
STIFFNESS ANALYSIS OF FRONT PART OF THE VEHICLE
Coufal, Tomáš ; Kovanda, Jan (referee) ; Kohút,, Pavol (referee) ; Vémola, Aleš (advisor)
The thesis deals with the front part stiffness of modern vehicles, especially for the use in the field of forensic engineering in the traffic accident analysis. During the traffic accident analysis, an inquiry into the collision between vehicles is carried out which is an integral part of determining the energy loss of the vehicle at the impact, or more precisely the deformation energy expressed in the form of Energy Equivalent Speed (EES). In case of known stiffness of given part of the vehicle and based on the depth of deformation, it is possible to calculate the deformation energy, or more precisely EES corresponding with given damage of the vehicle. In the field of forensic engineering, the values of stiffness of individual vehicle components are not known and therefore, alternative methods are used to calculate the EES, they are outlined in the research part of this dissertation. However, the current methods of EES determination have some limitations when it comes to usability, and therefore, new EES calculation for the front part of the vehicle was designed in the research. It was based on the real crash test results using real stiffness characteristics of the front part of a vehicle. The front part of the vehicle is divided into individual areas and each of these parts is characterised by its own stiffness coefficient. The designed EES calculation can thus be also used for collisions with partial overlapping, taking into account the real stiffness of the damaged part of the vehicle, which was not possible with existing methods. In the research part of this dissertation, a computer programme to calculate deformation energy and EES was processed. It works with individual stiffness characteristics in given areas where the input data are entered by the user and include the depth of permanent front part deformation in individual areas, vehicle weight, the direction of an impact force and the friction coefficient on the contact surface. Considering the fact that the vehicle stiffness is also one of the control parameters at solving collisions in the PC-Crash simulation programme, which is used in forensic engineering practice for the analysis of a collision process, a supplementary computer programme was designed. Based on the above-mentioned input data, the supplementary programme can further calculate data for collision solving in the simulation programme, namely stiffness, restitution coefficient and the vehicle damage stated in the output report of the simulation programme. Based on these data, the expert thus has the opportunity to solve the collision of two vehicles in the simulation programme with as much preciseness as if it was a real collision.
Problems of the Expert Analysis of the Vehicle Movement and Braking Action in General Spatial Curve at Speed Higher than 50 km/h
Panáček, Vladimír ; Šachl, Jindřich (referee) ; Drahotský, Ivo (referee) ; Vémola, Aleš (advisor)
The present apparatus for the technical analysis of road accidents has no well-integrated information, recommendations or procedures of how to solve comprehensively the analysis of road accidents involving vehicles equipped with stabilization system of driving dynamics. The problem in the investigation of a vehicle movement in a curve is the ignorance of the contributions of vehicle dynamics intervention of the electronic stability system. Although some of the simulation software used in the analysis of road accidents makes it possible to take into account the modelled vehicle movement impacted by a stabilization system in the examined process, but the experts do not know what parameters should be entered in the numerical models of stabilization system in a computer programme. Therefore, the thesis investigates the issue of the expert analysis of vehicle riding and braking in a general spatial curve at speeds exceeding 50 kph with simultaneous examining the impact of electronic stability system chassis on vehicle driving dynamics. The thesis first deals with the solutions based on classical analytical methods, then dwells on experimental measurements in real conditions on testing grounds and, finally, addresses the use of computer simulation software in expert practice. Nevertheless, it is important to realize that no computer simulation software can be an absolutely unambiguous solver, and it is not enough to generate a computer simulation, but so obtained results should be evaluated and justified technically. Road accident analyst needs to know the impact of vehicle electronic stability control systems on vehicle movement. The thesis investigated the mutual relationship between the vehicle speed limit in a curve specified by analytical calculation and the vehicle speed in a curve experimentally detected by measuring the parameters of driving dynamics of a vehicle equipped with electronic stability system. The impact of selected electronic stability control systems of the chassis on the vehicle movement in the investigated processes in the curve was detected and quantified by driving experiments. Finally, the input values of significant quantities of computational models of the ESP simulation programs were found consistent with the results of experimental measurements in defined curves for the vehicles equipped with electronic stability systems. The results of the thesis can be used both in the expert and in the teaching activities.
Detection of Braking Tracks using Laser-Induced Breakdown Spectroscopy (LIBS) and Laser-Induced Fluorescence Spectroscopy (LIBS + LIFS)
Prochazka, David ; Vémola, Aleš (referee) ; Pína,, Ladislav (referee) ; Kaiser, Jozef (advisor)
The aim of this work is to investigate the potential of Laser-Induced Breakdown Spectroscopy (LIBS) for identification of visually unrecognizable braking tracks. Identification of these tracks is based on different chemical composition of tire tread in comparison to road surface. The investigation was divided in several sequential steps – selection of suitable chemical element and its spectral line for break tracks identification; determination of the limits of detection and threshold intensity respectively for the selected chemical element; verification of LIBS ability to detect braking tracks on a real braking track. This testing braking track was prepared by exactly defined and described conditions. The detection was performed in two ways – laboratory analysis of tire treads particles collected via adhesive tape and in situ analysis via mobile apparatus. Results of both measurements showed that LIBS is able to detect visually unrecognizable braking tracks. Concepts of the devices capable of routine braking tracks identification for both possibilities were introduced.

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