Les matériaux composites organiques pour garniture de frein à friction sont le fruit d’une élaboration complexe, composée d’une succession d’étapes (mélange de constituants, préformage à froid, moulage à chaud, post-cuisson) ce qui rend difficile la maitrise du lien entre procédé, propriétés et comportement de ces matériaux en particulier du fait des synergies entre les constituants formant le mélange d’une part, et entre la composition et le procédé de fabrication d’autre part. Les travaux de thèse se sont focalisés sur deux étapes de fabrication, le moulage à chaud et la post cuisson, avec l’objectif de mieux comprendre l’influence de certains paramètres du procédé de fabrication sur les performances des matériaux : la température et la durée de moulage à chaud, la durée de post cuisson. L’analyse a porté sur la compréhension des liens entre la microstructure, les propriétés, le comportement tribologique et les mécanismes de frottement et d’usure, par le biais d’une démarche expérimentale fondée sur des formulations matériaux simplifiées ainsi que sur des essais d’usure élémentaires, spécifiques aux sollicitations de freinage / Organic composite friction materials for brake lining result from a complex elaboration made up of successive stages (mixture of constituents, cold preforming, hot molding, post-curing) that makes difficult the mastery of the link between process, properties and behaviour of friction material, especially because of synergies between constituents on one hand, and between composition and manufacturing process on the other hand. Two manufacturing stages were involved in this study, the hot molding and the post-curing, with the aim of a better understanding of the influence of certain parameters of the manufacturing process: the temperature and the duration of hot molding, and the duration of post curing. The analysis has focused on the understanding the relationship between microstructure, properties, tribological behaviour and friction and wear mechanisms of materials.The experimental approach was based on the development of simplified formulations of friction material, and on an elementary wear test specifically designed for braking loadings

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.

This thesis is concerned with ABS algorithm project for commercial vehicles. In the first part the reader is introduced to the history and first usage of the anti-blocking system, its principles and main functions. There are also driving algorithms and functionality system control. The second part is dedicated to the dynamic model, programs and ADAMS Car and MATLAB Simulink interfaces. It also contains the description of the algorithm, its parameters and basic functionality assay. Simulation, program interlink, testing and tuning are also described. The concluding part deals with results and their assessment.

The subject of this thesis is the analysis of the negative effects associated with the operation of a trailer for a personal vehicle with respect to the design speed, technical checks and analysis related legislation. Its work is drawn from the measurement, cooperation with leading Czech production plant trailers Vezeko s.r.o., an organization engaged in the implementation of engineering controls DEKRA Automobil a.s. and available literature, including electronic resources. Results of the work end with proposals for specific measures to minimize the identified adverse effects.

This thesis is dealing with a detailed analysis of electromechanical brake used in emergency situations to stop the electric motor. Environmental influences, bad material proposal or bad design parameters can significantly limit the behaviour of a brake. The thesis presents several approaches to avoid these limitations, to limit the reaction time and achieve better results. The attached programs can be used either for innovation, or for the new brake design based on the entry requirements.

No description available.

Durch das I-FAS der TU Chemnitz wurde im Rahmen des AKTIV-Projektes eine Probandenstudie zur Akzeptanz von Systemausprägungen einer Aktiven Gefahrenbremsung (AGB) bei PKW durchgeführt. Unter Verwendung eines stehenden Hindernisses wurden sechs Systemausprägungen verglichen, die von den AGB-Partnern in zwei Versuchsträger implementiert wurden. Die sechs Systemausprägungen werden nahezu identisch bewertet, solange Probanden keine Vergleichsmöglichkeit zu anderen Systemausprägungen haben. Wenn es zu einem Fahrereingriff kommt, ist der Eingriffszeitpunkt des Fahrers unabhängig von der gefahrenen Systemausprägung.

Collision avoidance is an essential component of autonomous shipping. As ships begin to advance towards autonomy, developing an advisory system is one of the first steps. An advisory system with a strong collision avoidance component can help the crew act more quickly and accurately in dangerous situations. One way to avoid colission is to make the vessel stop as fast as possible. In this work, two scenarios are studied, firstly, stopping along a predefined path, and secondly, stopping within a safe area defined by surrounding obstacles. The first scenario was further worked with to formulate a real-time solution. Movements of a vessel, described in three degrees of freedom with continuous dynamics, were simulated using mathematical models of the forces acting on the ship. Nonlinear optimal control problems were formulated for each scenario and solved numerically using discretization and a direct multiple shooting method. The results for the first problem showed that the vessel could stop without much deviation from the path. Paths with different curvatures were tested, and it was shown that a slightly longer distance was traveled when the curvature of the path was greater. The results for the second problem showed that the vessel stays within the safe area and chooses a relatively straight path as the optimal way of stoping. This results in a shorter distance traveled compared to the solution of the first problem. Two different real-time approaches were formulated, firstly a receding-horizon approach and secondly a lookup-based approach. Both approaches were solved with real-time feasibility, where the receding-horizon approach gave a better solution while lookup-based approach had a shorter computational time.

No description available.

<p>  </p> <p>Advancements in technology have propelled the availability of enriched and more frequent information about traffic conditions as well as the external factors that impact traffic such as weather, emergency response etc. Most newer vehicles are equipped with sensors that transmit their data back to the original equipment manufacturer (OEM) at near real-time fidelity. A growing number of such connected vehicles (CV) and the advent of third-party data collectors from various OEMs have made big data for traffic commercially available for use. Agencies maintaining and managing surface transportation are presented with opportunities to leverage such big data for efficiency gains. The focus of this dissertation is enhancing the use of CV data and applications derived from fusing it with other datasets to extract meaningful information that will aid agencies in data driven efficient decision making to improve network wide mobility and safety performance.   </p> <p>One of the primary concerns of CV data for agencies is data sampling, particularly during low-volume overnight hours. An evaluation of over 3 billion CV records in May 2022 in Indiana has shown an overall CV penetration rate of 6.3% on interstates and 5.3% on non-interstate roadways. Fusion of CV traffic speeds with precipitation intensity from NOAA’s High-Resolution Rapid-Refresh (HRRR) data over 42 unique rainy days has shown reduction in the average traffic speed by approximately 8.4% during conditions classified as very heavy rain compared to no rain. </p> <p>Both aggregate analysis and disaggregate analysis performed during this study enables agencies and automobile manufacturers to effectively answer the often-asked question of what rain intensity it takes to begin impacting traffic speeds. Proactive measures such as providing advance warnings that improve the situational awareness of motorists and enhance roadway safety should be considered during very heavy rain periods, wind events, and low daylight conditions.</p> <p>Scalable methodologies that can be used to systematically analyze hard braking and speed data were also developed. This study demonstrated both quantitatively and qualitatively how CV data provides an opportunity for near real-time assessment of work zone operations using metrics such as congestion, location-based speed profiles and hard braking. The availability of data across different states and ease of scalability makes the methodology implementable on a state or national basis for tracking any highway work zone with little to no infrastructure investment. These techniques can provide a nationwide opportunity in assessing the current guidelines and giving feedback in updating the design procedures to improve the consistency and safety of construction work zones on a national level.  </p> <p>CV data was also used to evaluate the impact of queue warning trucks sending digital alerts. Hard-braking events were found to decrease by approximately 80% when queue warning trucks were used to alert motorists of impending queues analyzed from 370 hours of queueing with queue trucks present and 58 hours of queueing without the queue trucks present, thus improving work zone safety. </p> <p>Emerging opportunities to identify and measure traffic shock waves and their forming or recovery speed anywhere across a roadway network are provided due to the ubiquity of the CV data providers. A methodology for identifying different shock waves was presented, and among the various case studies found typical backward forming shock wave speeds ranged from 1.75 to 11.76 mph whereas the backward recovery shock wave speeds were between 5.78 to 16.54 mph. The significance of this is illustrated with a case study of  a secondary crash that suggested  accelerating the clearance by 9 minutes could have prevented the secondary crash incident occurring at the back of the queue. Such capability of identifying and measuring shock wave speeds can be utilized by various stakeholders for traffic management decision-making that provide a holistic perspective on the importance of both on scene risk as well as the risk at the back of the queue. Near real-time estimation of shock waves using CV data can recommend travel time prediction models and serve as input variables to navigation systems to identify alternate route choice opportunities ahead of a driver’s time of arrival.   </p> <p>The overall contribution of this thesis is developing scalable methodologies and evaluation techniques to extract valuable information from CV data that aids agencies in operational decision making.</p>