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Determination of duration that driver needs to assess the situation behind the vehicle in course of turning or overtaking manoeuvres.
Belák, Michal ; Rábek,, Vlastimil (referee) ; Kolíbal, Zdeněk (referee) ; Semela, Marek (advisor)
The dissertation thesis deals mainly with determining of the duration that driver needs to assess the situation behind his vehicle at manoeuvers of turning and overtaking, based on the measurements made in real road traffic. These are common and frequent driving manoeuvers, which the driver performs while driving the vehicle in regular road traffic. For their safe execution the driver needs to have sufficient amount of information about the situation around the vehicle and especially behind the vehicle. This information can driver usually gain from devices for indirect vision, most often rear view mirrors. The time thus defined, suitable e.g for the needs of forensic engineering applications for the analysis of road accidents, has not been studied in detail yet. For the purpose of its determination, therefore, an extensive analysis of the current state of problematics related to the indirect vision from the vehicle was carried out. There were formulated influences on the time duration and with this related characteristics of humans as a part of the driver-vehicle-environment system in the thesis. The characteristics of human perception were investigated and the problematics of reaction time was discussed. Existing research focused on the duration of rear view mirrors glances was analyzed and possible methods of its measurement in detail were presented by author. Based on this, an experiment was designed and realized, the time necessary for rear view mirror glances was defined by the author. The results enable to quantify the time that the driver needs for assessing the situation behind the vehicle in connection of turning, overtaking and other driving manoeuvers when the driver needs to change the driving direction. The conclusions showed that the time needed to evaluate the situation behind the vehicle by means of the rear-view mirrors does not normally exceed duration 1 second.
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Analysis of the Speed of Cyclists Aged from 4 to 10 Years
Skanderová, Valentýna ; Semela, Marek (referee) ; Bradáč, Albert (advisor)
The diploma thesis Cyclists speed analysis at the age bracket of 4 to 10 deals with history and origin of bicycle, description and types of the contruction of bicycles for children at the age bracket mentioned above. The thesis includes the statistics of accidents involving cyclists and regulations providing for the ride on a bicycle on a carriageway. The practical part includes measuring cyclists speed when passing a measured section and the analysis of these data. The analysis of data is processed in terms of gear systems as the equipment. Complementary measuring was made in a slight rising. In the second part of the practical part is measured braking of cyclists at a particular age bracket and the evaluation of their deceleration. The conclusion includes comparison with measuring of other authors made so far.
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Development and use of non-destructive testing methods from the point of view of forensic engineering
Bílek, Petr ; Vala, Jiří (referee) ; Vodička, Jan (referee) ; Hobst, Leonard (advisor)
Concretes reinforced by, using distributed steel reinforcements (fibres) are known as fibre-concrete. In case of disturbances or accidents of concrete structures reinforced with wires, it is necessary to carefully examine the actual implementation of dispersed reinforcement. Fibre concretes belong to modern building materials whose possible applications have not been fully utilized so far. Have been mainly used for floor structures loaded with factory halls and warehouses. Recently, thanks to well-known physical and mechanical properties of fibre-concrete, there were numerous attempts of designers, and namely investors, to utilize this kind of materials for support structures either. Favorable properties of wire-concrete can be utilized if there is a necessity to increase the resistance of concrete to stresses exceeding its strength, cyclic stress or impact stress. Daily practice shows to prove that the applications of fibre-concrete in such structures lead to the economic success. Necessary condition for successful application of steel fiber reinforced concrete in constructions however consists in its uniform dispersion, a homogeneous distribution of the wires throughout the volume of the structure. In case of inappropriate processing and deposition of the mixture during the manufacturing process fiber-concrete structures, the fibers are often unevenly distributed. Wires itself represent unfavourably shaped mixture components and they are extremely deteriorating its workability. A grouping of wires may be encountered as well, which reduces the overall homogeneity and the quality of steel fiber-concrete structures. If the homogeneity of fibre-concrete is not kept, the material possess different properties in various parts of the structure (for example, tensile strength), which can lead to defects in the structure (generation and development of cracks). The relevant lower reliability of the structure which is caused by unequal distribution of fibres (wires) in concrete volume can lead to damage of the property as well as the safety and the human lives can be jeopardized. Hence it is necessary to secure the effective control of the fibre-concrete homogeneity in ready support fibre-concrete structures. Contemporary homogeneity control is still ongoing on fresh blends, but if the fibre-concrete hardened and is a part of the construction, no known reliable methods are currently in available to test the homogeneity of the fibre-concrete on the structure without its destruction. The methods developed to control the concentration of wires in wire-concrete structures are based mostly on magnetic or electromagnetic properties of wires. The thesis deals with the development of the magnetic method in situ using permanent magnets for monitoring the distribution of fibers in hardened steel fiber-concrete structures. The test principle is based on measurements of the changes in magnetic field strength of permanent magnets which are induced by a change in wire distribution in steel fibre-concrete structure. Test is characterized as a so called local- failure- test using a small diameter core drill. In this sense it is a semi-destructive method.
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New opportunities for the use of concrete structures sustainability assessment tools for a forensic engineering
Hrabová, Kristýna ; Kuda,, František (referee) ; Prostějovská,, Zita (referee) ; Vymazal, Tomáš (advisor)
In recent years, the European Union has been working to revise its climate, energy, and transport legislation to align existing legislation with the goals set for 2030 and 2050. These ambitions are closely related to the principles of sustainability. A growing population places increasing demands on the environment. Thus, improving living standards without damaging the environment is becoming a global challenge. The construction industry is an important segment of the world economy and contributes to environmental pollution. The concrete industry can also be counted among the main producers of CO2 emissions. The future of concrete construction design will be linked to new but also ongoing transformations of our society. The rapidity, speed, and frequency of the changes that are being implemented will also create a new urgency for knowledge and methodology in this field, whether for concrete producers, designers, or forensic experts. The focus of this thesis is the need to respond to new requirements in the field of concrete structures. In June 2016, the fib board approved activities to start working on the development of an updated fib Model Code 2020 (MC2020). This Model Code 2020 will form the source of new versions of the relevant Eurocodes and ISO standards, with sustainability as a fundamental requirement. Therefore, the design of a structure will now have to take into account not only durability considerations but also performance and overall environmental impact. Therefore, the dissertation focuses on the analysis of new trends in concrete structures to categorize the areas of change that may occur. The thesis deepens understanding of the areas of change as well as the methods of evaluation of building materials and concrete structures. Based on the identified shortcomings of the methods to assess the sustainability of materials, a sustainability indicator for CSB has been proposed. The changes brought about by the new fib Model Code 2020, whether in terms of performance-based design, use of recycled materials, or optimization of structures, may lead to defects and failures in building structures and new types of legal dispute for which there are no algorithms for resolution. In this paper, modern devices used for defectoscopy of defects and failure of concrete structures are also described.
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Analysis of driver’s conduct during solving of situations associated with pedestrians crossing the road
Maxera, Pavel ; Kolíbal, Zdeněk (referee) ; Rábek, Vlastimil (referee) ; Kledus, Robert (advisor)
The doctoral thesis analyses driver’s conduct while solving situations associated with crossing of pedestrians across the road in cases of various design of pedestrian crossings and at different conditions. The thesis deepens the knowledge of the human factor impact on the occurrence of a traffic accident involved vehicle and pedestrian and thesis also complements knowledge for the needs of the analysis of traffic accidents, especially in solving the pre collision phase and at assessment of possibilities for collision prevention by involved participants. The thesis deals with driver’s conduct, various models of the conduct as well as the thesis focuses on the visual perception, the process of information processing, the driver’s conduct and the reaction time. In terms of the solution suitable types of experiments were designed and implemented. Based on performed measurements a method of processing and evaluating data on drivers’ conduct was found as well as more significant data set was obtained for a detailed analysis of drivers' conduct in different driving situations. The assessed quantities of drivers' conduct were analysed with respect to the dangerousness of driving situations. For these purposes, the categories of the dangerousness of driving situations were defined (situations completely safe, with increased danger, dangerous and critical), into which the analysed driving situations were subsequently included. To enable the quantification of this classification of situations into the categories of the dangerousness, the coefficient of the dangerousness (so called K) was defined. From the detailed analysis of the obtained data, the limit values of this coefficient were determined, and these were subsequently verified using data from the solution of real traffic accidents. Concurrently the analysis verified the suitability of using this hazard coefficient in the analysis of traffic accidents, especially for a detailed assessment of the possibilities of collision prevention.
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New opportunities for the use of concrete structures sustainability assessment tools for a forensic engineering
Hrabová, Kristýna ; Kuda,, František (referee) ; Prostějovská,, Zita (referee) ; Vymazal, Tomáš (advisor)
In recent years, the European Union has been working to revise its climate, energy, and transport legislation to align existing legislation with the goals set for 2030 and 2050. These ambitions are closely related to the principles of sustainability. A growing population places increasing demands on the environment. Thus, improving living standards without damaging the environment is becoming a global challenge. The construction industry is an important segment of the world economy and contributes to environmental pollution. The concrete industry can also be counted among the main producers of CO2 emissions. The future of concrete construction design will be linked to new but also ongoing transformations of our society. The rapidity, speed, and frequency of the changes that are being implemented will also create a new urgency for knowledge and methodology in this field, whether for concrete producers, designers, or forensic experts. The focus of this thesis is the need to respond to new requirements in the field of concrete structures. In June 2016, the fib board approved activities to start working on the development of an updated fib Model Code 2020 (MC2020). This Model Code 2020 will form the source of new versions of the relevant Eurocodes and ISO standards, with sustainability as a fundamental requirement. Therefore, the design of a structure will now have to take into account not only durability considerations but also performance and overall environmental impact. Therefore, the dissertation focuses on the analysis of new trends in concrete structures to categorize the areas of change that may occur. The thesis deepens understanding of the areas of change as well as the methods of evaluation of building materials and concrete structures. Based on the identified shortcomings of the methods to assess the sustainability of materials, a sustainability indicator for CSB has been proposed. The changes brought about by the new fib Model Code 2020, whether in terms of performance-based design, use of recycled materials, or optimization of structures, may lead to defects and failures in building structures and new types of legal dispute for which there are no algorithms for resolution. In this paper, modern devices used for defectoscopy of defects and failure of concrete structures are also described.
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Analysis of driver’s conduct during solving of situations associated with pedestrians crossing the road
Maxera, Pavel ; Kolíbal, Zdeněk (referee) ; Rábek, Vlastimil (referee) ; Kledus, Robert (advisor)
The doctoral thesis analyses driver’s conduct while solving situations associated with crossing of pedestrians across the road in cases of various design of pedestrian crossings and at different conditions. The thesis deepens the knowledge of the human factor impact on the occurrence of a traffic accident involved vehicle and pedestrian and thesis also complements knowledge for the needs of the analysis of traffic accidents, especially in solving the pre collision phase and at assessment of possibilities for collision prevention by involved participants. The thesis deals with driver’s conduct, various models of the conduct as well as the thesis focuses on the visual perception, the process of information processing, the driver’s conduct and the reaction time. In terms of the solution suitable types of experiments were designed and implemented. Based on performed measurements a method of processing and evaluating data on drivers’ conduct was found as well as more significant data set was obtained for a detailed analysis of drivers' conduct in different driving situations. The assessed quantities of drivers' conduct were analysed with respect to the dangerousness of driving situations. For these purposes, the categories of the dangerousness of driving situations were defined (situations completely safe, with increased danger, dangerous and critical), into which the analysed driving situations were subsequently included. To enable the quantification of this classification of situations into the categories of the dangerousness, the coefficient of the dangerousness (so called K) was defined. From the detailed analysis of the obtained data, the limit values of this coefficient were determined, and these were subsequently verified using data from the solution of real traffic accidents. Concurrently the analysis verified the suitability of using this hazard coefficient in the analysis of traffic accidents, especially for a detailed assessment of the possibilities of collision prevention.
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Determination of duration that driver needs to assess the situation behind the vehicle in course of turning or overtaking manoeuvres.
Belák, Michal ; Rábek,, Vlastimil (referee) ; Kolíbal, Zdeněk (referee) ; Semela, Marek (advisor)
The dissertation thesis deals mainly with determining of the duration that driver needs to assess the situation behind his vehicle at manoeuvers of turning and overtaking, based on the measurements made in real road traffic. These are common and frequent driving manoeuvers, which the driver performs while driving the vehicle in regular road traffic. For their safe execution the driver needs to have sufficient amount of information about the situation around the vehicle and especially behind the vehicle. This information can driver usually gain from devices for indirect vision, most often rear view mirrors. The time thus defined, suitable e.g for the needs of forensic engineering applications for the analysis of road accidents, has not been studied in detail yet. For the purpose of its determination, therefore, an extensive analysis of the current state of problematics related to the indirect vision from the vehicle was carried out. There were formulated influences on the time duration and with this related characteristics of humans as a part of the driver-vehicle-environment system in the thesis. The characteristics of human perception were investigated and the problematics of reaction time was discussed. Existing research focused on the duration of rear view mirrors glances was analyzed and possible methods of its measurement in detail were presented by author. Based on this, an experiment was designed and realized, the time necessary for rear view mirror glances was defined by the author. The results enable to quantify the time that the driver needs for assessing the situation behind the vehicle in connection of turning, overtaking and other driving manoeuvers when the driver needs to change the driving direction. The conclusions showed that the time needed to evaluate the situation behind the vehicle by means of the rear-view mirrors does not normally exceed duration 1 second.
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Development and use of non-destructive testing methods from the point of view of forensic engineering
Bílek, Petr ; Vala, Jiří (referee) ; Vodička, Jan (referee) ; Hobst, Leonard (advisor)
Concretes reinforced by, using distributed steel reinforcements (fibres) are known as fibre-concrete. In case of disturbances or accidents of concrete structures reinforced with wires, it is necessary to carefully examine the actual implementation of dispersed reinforcement. Fibre concretes belong to modern building materials whose possible applications have not been fully utilized so far. Have been mainly used for floor structures loaded with factory halls and warehouses. Recently, thanks to well-known physical and mechanical properties of fibre-concrete, there were numerous attempts of designers, and namely investors, to utilize this kind of materials for support structures either. Favorable properties of wire-concrete can be utilized if there is a necessity to increase the resistance of concrete to stresses exceeding its strength, cyclic stress or impact stress. Daily practice shows to prove that the applications of fibre-concrete in such structures lead to the economic success. Necessary condition for successful application of steel fiber reinforced concrete in constructions however consists in its uniform dispersion, a homogeneous distribution of the wires throughout the volume of the structure. In case of inappropriate processing and deposition of the mixture during the manufacturing process fiber-concrete structures, the fibers are often unevenly distributed. Wires itself represent unfavourably shaped mixture components and they are extremely deteriorating its workability. A grouping of wires may be encountered as well, which reduces the overall homogeneity and the quality of steel fiber-concrete structures. If the homogeneity of fibre-concrete is not kept, the material possess different properties in various parts of the structure (for example, tensile strength), which can lead to defects in the structure (generation and development of cracks). The relevant lower reliability of the structure which is caused by unequal distribution of fibres (wires) in concrete volume can lead to damage of the property as well as the safety and the human lives can be jeopardized. Hence it is necessary to secure the effective control of the fibre-concrete homogeneity in ready support fibre-concrete structures. Contemporary homogeneity control is still ongoing on fresh blends, but if the fibre-concrete hardened and is a part of the construction, no known reliable methods are currently in available to test the homogeneity of the fibre-concrete on the structure without its destruction. The methods developed to control the concentration of wires in wire-concrete structures are based mostly on magnetic or electromagnetic properties of wires. The thesis deals with the development of the magnetic method in situ using permanent magnets for monitoring the distribution of fibers in hardened steel fiber-concrete structures. The test principle is based on measurements of the changes in magnetic field strength of permanent magnets which are induced by a change in wire distribution in steel fibre-concrete structure. Test is characterized as a so called local- failure- test using a small diameter core drill. In this sense it is a semi-destructive method.
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Analysis of the Speed of Cyclists Aged from 4 to 10 Years
Skanderová, Valentýna ; Semela, Marek (referee) ; Bradáč, Albert (advisor)
The diploma thesis Cyclists speed analysis at the age bracket of 4 to 10 deals with history and origin of bicycle, description and types of the contruction of bicycles for children at the age bracket mentioned above. The thesis includes the statistics of accidents involving cyclists and regulations providing for the ride on a bicycle on a carriageway. The practical part includes measuring cyclists speed when passing a measured section and the analysis of these data. The analysis of data is processed in terms of gear systems as the equipment. Complementary measuring was made in a slight rising. In the second part of the practical part is measured braking of cyclists at a particular age bracket and the evaluation of their deceleration. The conclusion includes comparison with measuring of other authors made so far.
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