The purpose of this thesis is: (i) to produce an in-depth data analysis and computer-based simulations of the market environment to investigate whether financial stability is affected by the presence of High-Frequency investors; (ii) to verify how High-Frequency Trading and financial stability interact with each other under non-linear conditions; (iii) whether non-illicit behaviours can still lead to potentially destabilising effects; (iv) to provide quantitative support to the theses, either from the audit trail data or resulting from simulations. Simulations are provided to test whether High-Frequency Trading: (a) has an impact on market volatility, (b) leads to market splitting into two tiers; (c) takes the lion's share of arbitrage opportunities. Audit trail data is analysed to verify some hypotheses on the dynamics of the Flash Crash. The simulation on the impact of High-Frequency Trading on market volatility confirms that when markets are under stress, High-Frequency Trading may cause volatility to significantly increase. However, as the number of ultra-fast participants increases, this phenomenon tends to disappear and volatility realigns to its standard values. The market tiering simulation suggests that High-Frequency traders have some tendency to deal with each other, and that causes Low-Frequency traders also to deal with other slow traders, albeit at a lesser extent. This is also a kind of market instability. High-Frequency Trading potentially allows a few fast traders to grab all the arbitrage-led profits, so falsifying the Efficient Market Hypothesis. This phenomenon may disappear as more High-Frequency traders enter the competition, leading to declining profits. Yet, the whole matter seems a dispute for abnormal gains only between few sub-second traders. All simulations have been carefully designed to provide robust results: the behaviours simulated have been drawn from existing literature and the simplifying assumptions have been kept to a minimum. This maximises the reliability of the results and minimizes the potential of bias. Finally, from the data analysis, the impact of High-Frequency Trading on the Flash Crash seems significant; other sudden crashes occurred since, and more can be expected over the next future. Overall, it can be concluded that High-Frequency Trading shows some controversial aspects impacting on financial stability. The results are at a certain extent confirmed by the audit trail data analysis, although only indirectly, since the details allowing the match between High-Frequency traders and their behaviour are confidential and not publicly available Nevertheless, the findings about HFT-induced volatility, market segmentation and sub-optimal market efficiency, albeit not definitive, suggest that careful monitoring by regulators and policy-makers might be required.

Many older bridges and tunnels were constructed using standards by now many decades out-of-date, at a time when trucks and other large vehicles were smaller. A bridge or tunnel strike is an incidence in which a vehicle, typically a lorry (truck) or double-decker bus, tries to pass under a bridge or tunnel that is lower than its height, subsequently colliding with the structure. These strikes lead to an increased cost of bridge repairs, clogged up roadways and increased potential for catastrophic events: hazardous spillage and/or total collapse. Today, Network Rail reports on average a strike every 4.5 hours. There are a number of reasons why strikes occur, and why drivers of heavy goods vehicles sometimes fail to recognise the warning signs, consequently striking the bridge or tunnel. At first glance, it may seem like the problem is a fairly easy one to solve; however, no matter how well planned the road system, human error is an ever-present risk. The research proposes to address the problem of bridge and tunnel strike prevention and management. The intent of the research is to develop an affordable, reliable and robust early warning over-height detection system bridge-owners can implement at locations with high strike occurrences. The research aims to test and validate a novel vision-based system using a single camera to accurately detect over-height vehicles using a set of optimised parameters. The system uses a camera installed at the offending height, which acts as an “over-height plane” formed by the averages of the maximum allowable heights across all lanes in a given traffic direction. Any vehicle exceeding this plane is analysed within a region of interest using a trigger-based approach for accurate detection and driver warning. If the vehicle is deemed to be over-height, a warning is issued to the driver. As a result, prolonging life expectancy of structures while decreasing the cost of repairs, maintenance and inspections.

Esta tese tem como finalidade propor um método de coleta, tratamento e análise de dados de acidentes de trânsito para aplicação no Brasil. Este método tem como um de seus objetivos reconhecer os fatores que contribuem para a ocorrência dos acidentes, visto que identificar as causas dos acidentes é fundamental na busca por soluções para o problema da acidentalidade. No Brasil as bases de dados de acidentes de trânsito são, em geral, estruturadas a partir dos registros policiais e carecem de informações adequadas para a análise da segurança viária. O método proposto neste trabalho permite registrar acidentes de modo a contemplar: as características do acidente, as circunstâncias do momento, a identificação e as características dos veículos e pessoas envolvidas. Além disso, o método permite relacionar essas informações com os fatores que contribuíram para a ocorrência dos acidentes. Nesse contexto, a criação de uma base de dados de acidentes e seus fatores contribuintes, vem suprir a carência de informações essenciais para o diagnóstico e encaminhamento de soluções adequadas para os problemas motivadores dos acidentes de trânsito. A proposta desta tese está baseada em uma abordagem que combina aspectos qualitativos e quantitativos, alinhada às melhores práticas internacionais na área de segurança viária. Como resultado do desenvolvimento do método, foram elaborados instrumentos de coleta de dados contendo um formulário, um manual e procedimentos para a coleta de dados. Como resultado da aplicação prática desses instrumentos, foi criada a estrutura de uma base de dados que permitiu a definição do método proposto para a análise das causas de acidentes de trânsito. Como meio de validar o método proposto, foi realizado um estudo aplicado e são apresentadas as análises de dados dos acidentes de trânsito observados. / This thesis has the purpose of presenting a method for collecting and processing data on traffic accidents to be applied in Brazil. This method aims to acknowledge the contributor factors for the occurrence of accidents, since identifying the causes of accidents is crucial on the search for effective solutions for the road safety problem. Traffic accidents database in Brazil are generally structured based on police reports, therefore lacking adequate information for the analyses of road safety. The method proposes a registry of the accidents comprising accident characteristics, scene circumstances, vehicle as well as involved people identification and characteristics. Moreover, it allows relating that information with the accident contributory factors. In this scenery, the creation of an accident database and its contributory factors emerge to supply the lack of essential information for the diagnosis and adequate solution for traffic accidents. This thesis’ proposal has an approach that combines both quantitative and qualitative aspects, seeking to level up to the best international practice on the road safety area. As a result of the development of the method, data collection instruments were elaborated: a form, a manual, and procedures for data collection. Besides, as a result of the practical application of these instruments, a database - which allowed the definition of the method proposed for analysis of the causes of traffic accidents - was created. As a mean of validation of the method, an applied study and the data analysis of the observed traffic accidents are presented.

The present study focused on evaluating some crash prediction models for two lane highways on Brazilian conditions. Also, the transferability of models was considered, specifically by means of a comparison between Brazil, HSM and Florida. The analysis of two lane highways crash prediction models was promising when the road characteristics were well known and there was not much difference from base conditions. This conclusion was attained regarding the comparison of results for all segments, non-curved segments and curved segments, confirming that a transferred model can be used with caution. In addition, two novel models for Brazilian two-lane highways segments were estimated. The model developed showed better results for non-curved segments in the calibration/validation sample. Thus, for a general analysis purpose of non-curved segments this model is recommended. Finally, there are many factors that could not be measured by these models and reflects road safety various condition. Even so, the study of crash predict models in Brazilian context could provide a better start point in safety road analysis. / O foco desta pesquisa foi avaliar a aplicação de alguns modelos de previsão de acidentes em rodovias de pista simples de três estados brasileiros. Ainda, a transferabilidade destes modelos foi abordada, especificamente por meio de uma comparação entre características do Brasil, Florida e aquelas recomendadas pelo Highway Safety Manual. O uso dos distintos modelos se mostrou promissor para situações nas quais as características da via se mantiveram semelhantes às condições para as quais os modelos foram desenvolvidos. A avaliação foi empreendida para todos os segmentos homogêneos, separados posteriormente segundo a existência de curvas horizontais. Adicionalmente, dois novos modelos foram equacionados para a amostra brasileira. O modelo de previsão de acidentes desenvolvido apresentou melhores medidas de desempenho para segmentos sem curvas horizontais, sendo recomendável para previsão de acidentes em análises preliminares. Por fim, foi constatado que outros fatores não contemplados pelos modelos podem ter impactado as condições de segurança dos locais estudados. Ainda assim, essa pesquisa representa no contexto do Brasil um ponto de partida em análises relacionadas à segurança de rodovias de pista simples.

Esta tese tem como finalidade propor um método de coleta, tratamento e análise de dados de acidentes de trânsito para aplicação no Brasil. Este método tem como um de seus objetivos reconhecer os fatores que contribuem para a ocorrência dos acidentes, visto que identificar as causas dos acidentes é fundamental na busca por soluções para o problema da acidentalidade. No Brasil as bases de dados de acidentes de trânsito são, em geral, estruturadas a partir dos registros policiais e carecem de informações adequadas para a análise da segurança viária. O método proposto neste trabalho permite registrar acidentes de modo a contemplar: as características do acidente, as circunstâncias do momento, a identificação e as características dos veículos e pessoas envolvidas. Além disso, o método permite relacionar essas informações com os fatores que contribuíram para a ocorrência dos acidentes. Nesse contexto, a criação de uma base de dados de acidentes e seus fatores contribuintes, vem suprir a carência de informações essenciais para o diagnóstico e encaminhamento de soluções adequadas para os problemas motivadores dos acidentes de trânsito. A proposta desta tese está baseada em uma abordagem que combina aspectos qualitativos e quantitativos, alinhada às melhores práticas internacionais na área de segurança viária. Como resultado do desenvolvimento do método, foram elaborados instrumentos de coleta de dados contendo um formulário, um manual e procedimentos para a coleta de dados. Como resultado da aplicação prática desses instrumentos, foi criada a estrutura de uma base de dados que permitiu a definição do método proposto para a análise das causas de acidentes de trânsito. Como meio de validar o método proposto, foi realizado um estudo aplicado e são apresentadas as análises de dados dos acidentes de trânsito observados. / This thesis has the purpose of presenting a method for collecting and processing data on traffic accidents to be applied in Brazil. This method aims to acknowledge the contributor factors for the occurrence of accidents, since identifying the causes of accidents is crucial on the search for effective solutions for the road safety problem. Traffic accidents database in Brazil are generally structured based on police reports, therefore lacking adequate information for the analyses of road safety. The method proposes a registry of the accidents comprising accident characteristics, scene circumstances, vehicle as well as involved people identification and characteristics. Moreover, it allows relating that information with the accident contributory factors. In this scenery, the creation of an accident database and its contributory factors emerge to supply the lack of essential information for the diagnosis and adequate solution for traffic accidents. This thesis’ proposal has an approach that combines both quantitative and qualitative aspects, seeking to level up to the best international practice on the road safety area. As a result of the development of the method, data collection instruments were elaborated: a form, a manual, and procedures for data collection. Besides, as a result of the practical application of these instruments, a database - which allowed the definition of the method proposed for analysis of the causes of traffic accidents - was created. As a mean of validation of the method, an applied study and the data analysis of the observed traffic accidents are presented.

This thesis aims to improve the cross-platform reliability of software components tested on distributed CI systems. More specifically, it is centered on extracting crash information from cross-platform crashes. Crash information was generated and parsed on Mac, Linux and Windows. The crash information proved to be valuable for developers in their day-to-day job, especially the raw crash information. However, the graph visualizations that were created out of this information proved to be less than satisfactory for developers.

En France, en 2015 les motocyclistes représentent 43% des blessés graves victimes d'accidents de la circulation routière. Au même moment, même si les accidents de chocs de motocyclistes contre les dispositifs de retenue routiers ne représentent en moyenne que 10% des accidents de la circulation routière, les motocyclistes présentent un risque de décès 30 à 80 fois supérieur au risque de décès des usagers de véhicules impliqués dans le même type d'accidents.Pour renforcer la sécurité des motocyclistes, les dispositifs de retenue pour automobiles (dispositifs traditionnels) sont équipés à leur partie inférieure d'écran de protection motards. Les écrans motards ont pour but d'amortir de manière progressive les chocs des motocyclistes en les empêchant dans le même temps de passer à travers la partie inférieure des dispositifs de retenue pour automobiles, de percuter un poteau et d'être sévèrement blessés. Les écrans motards doivent subir des essais de chocs normatifs et répondre à certaines exigences afin de pouvoir être installés sur le bord des routes européennes et de garantir surtout la sécurité des motards. Cependant, il n'existe que des procédures normatives pour tester ces dispositifs, la procédure LIER dans le contexte Français et la procédure normative EN 1317-8 dans le contexte Européen. Afin d'évaluer ces deux procédures normatives et de proposer de nouvelles dispositions pouvant servir de procédure normative plus avancée sur le protocole d'essais d'évaluation de performances d'écrans motards, des simulations numériques ont été réalisées. Un modèle numérique complet de dispositif de retenue routier équipé d'écran motard en acier a été développé et corrélé sur un essai de choc réel sur un dispositif de même type. Une fois corrélé,le modèle a été utilisé afin d'évaluer l'influence des conditions d'essais et des caractéristiques mécaniques matériaux de l'écran sur les performances de l'écran motard. Enfin, une nouvelle démarche d'évaluation de performances d'écran de protection motard a été mise en place / In France, in 2015,motorcyclists represent 43% of seriously injured accident victims in road traffic. At the same time, even though motorcyclists impact crashes against the road restraint systems represent on average 10% of accidents in road traffic, motorcyclists present a risk of death from30 to 80 times upper than the risk of death for users of vehicles involved in the same type of accidents. To enhance the safety of motorcyclists, Vehicle Restraints Systems (VRS) arefitted to the lower part of restraint systems for motorcyclists. Motorcyclist’s Restraint Systems (MRS) are designed to absorb shocks gradually and to preventmotorcyclists to pass through the lower part of VRS, to hit a post and be severely injured. Before being installed on the roadsides, MRS have to be crash-tested according to standards in order to evaluate their safety and ensure motorcyclists safety. However, there are only normative procedures to testMRS, the LIER procedurein the French context and the procedure EN1317-8 in the European context. To assess both normative procedures and propose new provisions which can be used as normative procedure more advanced on the protocol of MRS performances evaluation tests, numerical simulations were performed. A numerical model of MRS was developed and correlated on one real impact test on other device of same type. Once correlated, the model was used to conduct a parametric study on the test conditions and thematerialsmechanical properties of the MRS. Finally, a new demarche of MRS performances evaluation was developed

Plus d'un million de personnes meurent dans des accidents sur les routes du monde et beaucoup de millions sont gravement blessés chaque année. Selon les études, ‘Run-Off-Road accidents (ROR)’, c'est-à-dire que le véhicule a au moins une collision avec des équipements routiers, représentent environ 10% des accidents routières, mais 45% de tous les accidents mortels sont des ROR. Les dispositifs de retenue des véhicules (DDR) sont les infrastructures installées sur la route pour fournir un niveau de confinement du véhicule ‘hors de contrôle’. La barrière de sécurité routière est un DDR continu installé à côté ou sur la réserve centrale d'une route pour empêcher les véhicules errants de s'écraser sur les obstacles routiers et de les conserver en toute sécurité. Les résultats statistique montrent que l'existence des barrières peut réduire les morts jusqu'à un facteur de 4 par rapport aux collisions contre d'autres obstacles routiers. Les performances de sauvetage d'un DDR dépendent de la conception de l'appareil. Des normes telles que EN1317 ont normalisé les conditions des essais de chocs sous lesquelles une conception de DDR doit être testée et ont défini les critères pour l'évaluation des performances d'une conception. En fait, un DDR ne puisse pas vraiment être optimisé: il existe des critères multiples pour l'évaluation de la performance d'un DDR et tous les critères ne peuvent pas être optimisés en même temps; les conditions de travail d’un DDR, c'est-à-dire les conditions d'impact d’un DDR avec un véhicule errant, sont nombreuses; les facteurs incertains du DDR peuvent dégrader les performances d'une conception. La thèse vise à définir une approche qui peut servir : l'analyse de sensibilité (AS) et la conception robuste du DDR ; enrichissement des normes existantes dans la conception du DDR. Le cas d'une barrière de sécurité routière est spécifié dans l'étude : une barrière a été testée expérimentalement, le programme Ls-Dyna est utilisé pour la simulation de choc de l'appareil ; en tenant compte des propriétés du modèle de choc, les efficacités de différentes méthodes de l’AS ont été étudiées ; les influences des facteurs critiques dont les incertitudes contribuent le plus à l'instabilité de la barrière ont été quantifiées avec les approches d’AS sélectionnées ; compte tenu des incertitudes des facteurs critiques, l’optimisation robuste de multi-objectif de la barrière est réalisée ; des simulations d'impact de la barrière optimisée ont été effectuées sous des conditions d'impact différentes pour évaluer ses performances dans les véritables accidents. Les approches présentées dans l'article peuvent être utiles pour la conception d'autres DDR ou plus largement d'autres systèmes d'ingénierie complexes. On peut espérer que l'analyse de robustesse et l'analyse de la généralisation (c'est-à-dire l'évaluation de la performance du DDR sous différentes conditions d'impact) du DDR pourraient enrichir les normes de la conception des DDR / More than 1 million people die in crashes on the world’s roads and many millions are seriously injured each year. According to the studies: Run-Off-Road accidents (ROR), i.e. the vehicle run-off the road into the roadside and has at least one collision with either roadside equipment or the roadside itself, “represent about 10% of the total road accidents, while 45% of all fatal accidents are ROR”. Vehicle Restraint Systems (VRS) are the infrastructures installed on the road to provide a level of containment for an errant vehicle. Safety barrier is “continuous VRS installed alongside, or on the central reserve, of a road to prevent errant vehicles from crashing on roadside obstacles, and to retain them safely”. Statistic results show that “the existence of protective barriers on road can reduce fatalities up to a factor of 4 when compared to collisions against other road obstacles.” The life-saving performances of a VRS depend on the design of the device. Standards such as EN1317 normalized the impact conditions under which a design of VRS must be tested by crash tests, and defined the criteria for performance evaluation of a design. While a VRS cannot really be optimized: Multi-criteria exist for performance evaluation of a VRS and all the criteria cannot be optimized in the same time; the impact conditions of the VRS with the errant vehicle are numerous; uncertain factors of the VRS may degrade the performances of a design. The thesis aims to define an approach that can serve: sensitivity analysis (SA) and robust design of the VRS; Enrichment for the existing standards in the design of VRS. The case of a safety barrier is specified in the study: a safety barrier has been test experimentally, the program Ls-Dyna was used for crash simulation of the device; considering properties of the crash model, efficiencies of different SA methods were studied and influences of the critical factors whose uncertainties contribute the most to the instability of the barrier were quantified with the selected SA approaches; considering the uncertainties of the critical factors, Multi-Objective robust optimization of the tested barrier were realized; under different impact conditions, crash simulations of the optimized barrier were carried out to evaluate its performances in the real crash accidents. The approaches presented in the article can be useful for the design of other VRS or more broadly, other complex engineering systems. Hopefully, the robustness analysis and generalization analysis (i.e. performance evaluation of the VRS under different impact conditions) of the safety barrier could enrich the standards for the design of VRS

This thesis merges the fields of Heterogeneous Agent Models (HAMs) and Be- havioural Finance in order to bridge the main deficiencies of both approaches and to examine whether they can complement one another. Our approach suggests an alternative tool for examining HAM price dynamics and brings an original way of dealing with problematic empirical validation. First, we present the original model and discuss various extensions and attempts at empirical estimation. Next, we develop a unique benchmark dataset, covering five par- ticularly turbulent U.S. stock market periods, and reveal an interesting pattern in this data. The main body applies a numerical analysis of the HAM extended with the selected Behavioural Finance findings: herding, overconfidence, and market sentiment. Using Wolfram Mathematica we perform Monte Carlo sim- ulations of a developed algorithm. We show that the selected findings can be well modelled via the HAM and that they extend the original HAM consider- ably. Various HAM modifications lead to significantly different results and HAM is also able to partially replicate price behaviour during turbulent stock market periods. Bibliographic Record Kukačka, J. (2011): Behavioural Breaks in the Heterogeneous Agent Model. Master thesis, Charles University in Prague, Faculty of Social Sciences,...

The Highway Safety Manual (HSM) estimates roadway safety performance based on predictive models that were calibrated using national data. Calibration factors are then used to adjust these predictive models to local conditions for local applications. The HSM recommends that local calibration factors be estimated using 30 to 50 randomly selected sites that experienced at least a total of 100 crashes per year. It also recommends that the factors be updated every two to three years, preferably on an annual basis. However, these recommendations are primarily based on expert opinions rather than data-driven research findings. Furthermore, most agencies do not have data for many of the input variables recommended in the HSM. This dissertation is aimed at determining the best way to meet three major data needs affecting the estimation of calibration factors: (1) the required minimum sample sizes for different roadway facilities, (2) the required frequency for calibration factor updates, and (3) the influential variables affecting calibration factors. In this dissertation, statewide segment and intersection data were first collected for most of the HSM recommended calibration variables using a Google Maps application. In addition, eight years (2005-2012) of traffic and crash data were retrieved from existing databases from the Florida Department of Transportation. With these data, the effect of sample size criterion on calibration factor estimates was first studied using a sensitivity analysis. The results showed that the minimum sample sizes not only vary across different roadway facilities, but they are also significantly higher than those recommended in the HSM. In addition, results from paired sample t-tests showed that calibration factors in Florida need to be updated annually. To identify influential variables affecting the calibration factors for roadway segments, the variables were prioritized by combining the results from three different methods: negative binomial regression, random forests, and boosted regression trees. Only a few variables were found to explain most of the variation in the crash data. Traffic volume was consistently found to be the most influential. In addition, roadside object density, major and minor commercial driveway densities, and minor residential driveway density were also identified as influential variables.