Roadway surface friction along the West Virginia Division of Highways' roadway network is key to the safety of all traveling motorists. Being geographically located in the rugged Appalachian Mountains, the West Virginia Division of Highways' roadway network is flooded with innumerable geometric and design challenges, causing drivers to have to exercise the most care and attention when navigating the network. This dissertation introduces the concept of roadway surface friction management to this network. For decades, roadway surface friction has only been tested and checked on an as-needed basis at crash sites and intersections, in legal situations, and pavement acceptance on construction projects. It also seeks to use the acquired data through a case study to insure proper methodology of roadway surface friction management, to develop sample safety performance functions and best crash estimates, and to apply this decision-making data to provide assistance and guidance in the selection of projects in the West Virginia Highway Safety Improvement Program. This dissertation follows the manuscript format and is composed of three papers. The first chapter of the dissertation examines the usage of Method 3 of the AASHTO Guide for Pavement Friction and the modifications to this method to collect existing roadway surface friction data along the District Ten portion of the network. The second chapter of the dissertation discusses the development of sample safety performance functions to estimate the average number of crashes along each of the tested roadway categories: Interstate Routes, United States Routes, and West Virginia Routes. It also discussed the development of best crash estimates using the Empirical Bayes Method. This is essential to be able to forecast how crash counts should improve, given the application of various roadway improvements. The third and final chapter of the dissertation develops the case study based on the District Ten portion of the network and shows how to enhance project selection in the West Virginia Highway Safety Improvement Program. This is completed by applying the safety performance functions and best crash estimates from the second chapter to arrive at real friction numbers for the network and their project impacts. / Doctor of Philosophy / Roadway surface friction along the West Virginia Division of Highways' roadway network is key to the safety of all traveling motorists. Being geographically located in the rugged Appalachian Mountains, the West Virginia Division of Highways' roadway network is flooded with innumerable geometric and design challenges, causing drivers to have to exercise the most care and attention when navigating the network. This dissertation introduces the concept of roadway surface friction management to this network. For decades, roadway surface friction has only been tested and checked on an as-needed basis at crash sites and intersections, in legal situations, and pavement acceptance on construction projects. It also seeks to use the acquired data through a case study to insure proper methodology of roadway surface friction management, to develop sample safety performance functions and best crash estimates, and to apply this decision-making data to provide assistance and guidance in the selection of projects in the West Virginia Highway Safety Improvement Program. This dissertation follows the manuscript format and is composed of three papers. The first chapter of the dissertation examines the usage of Method 3 of the AASHTO Guide for Pavement Friction and the modifications to this method to collect existing roadway surface friction data along the District Ten portion of the network. The second chapter of the dissertation discusses the development of sample safety performance functions to estimate the average number of crashes along each of the tested roadway categories: Interstate Routes, United States Routes, and West Virginia Routes. It also discussed the development of best crash estimates using the Empirical Bayes Method. This is essential to be able to forecast how crash counts should improve, given the application of various roadway improvements. The third and final chapter of the dissertation develops the case study based on the District Ten portion of the network and shows how to enhance project selection in the West Virginia Highway Safety Improvement Program. This is completed by applying the safety performance functions and best crash estimates from the second chapter to arrive at real friction numbers for the network and their project impacts.

Fixed-object crashes have long time been considered as major roadway safety concerns. While previous relevant studies tended to address such crashes in the context of roadway departures, and heavily relied on police-reported accidents data, this study integrated the SHRP2 NDS and RID data for analyses, which fully depicted the prior to, during, and after crash scenarios. A total of 1,639 crash, near-crash events, and 1,050 baseline events were acquired. Three analysis methods: logistic regression, support vector machine (SVM) and artificial neural network (ANN) were employed for two responses: crash occurrence and severity level. Logistic regression analyses identified 16 and 10 significant variables with significance levels of 0.1, relevant to driver, roadway, environment, etc. for two responses respectively. The logistic regression analyses led to a series of findings regarding the effects of explanatory variables on fixed-object event occurrence and associated severity level. SVM classifiers and ANN models were also constructed to predict these two responses. Sensitivity analyses were performed for SVM classifiers to infer the contributing effects of input variables. All three methods obtained satisfactory prediction performance, that was around 88% for fixed-object event occurrence and 75% for event severity level, which indicated the effectiveness of NDS event data on depicting crash scenarios and roadway safety analyses. / Master of Science / Fixed-object crashes happen when a single vehicle strikes a roadway feature such as a curb or a median, or runs off the road and hits a roadside feature such as a tree or utility pole. They have long time been considered as major highway safety concerns due to their high frequency, fatality rate, and associated property cost. Previous studies relevant to fixed-object crashes tended to address such crashes in the contexture of roadway departures, and heavily relied on police-reported accident data. However, many fixed-object crashes involved objects in roadway such as traffic control devices, roadway debris, etc. The police-reported accident data were found to be weak in depicting scenarios prior to, during crashes. Also, many minor crashes were often kept unreported. The Second Strategic Highway Research Program (SHRP2) Naturalistic Driving Study (NDS) is the largest NDS project launched across the country till now, aimed to study driver behavior or, performance-related safety problems under real-world scenarios. The data acquisition systems (DASs) equipped on participated vehicles collect vehicle kinematics, roadway, traffic, environment, and driver behavior data continuously, which enable researchers to address such crash scenarios closely. This study integrated SHRP2 NDS and roadway information database (RID) data to conduct a comprehensive analysis of fixed-object crashes. A total of 1,639 crash, near-crash events relevant to fixed objects and animals, and 1,050 baseline events were used. Three analysis methods: logistic regression, support vector machine (SVM) and artificial neural network (ANN) were employed for two responses: crash occurrence and severity level. The logistic regression analyses identified 16 and 10 variables with significance levels of 0.1 for fixed-object event occurrence and severity level models respectively. The influence of explanatory variables was discussed in detail. SVM classifiers and ANN models were also constructed to predict the fixed-object crash occurrence and severity level. Sensitivity analyses were performed for SVM classifiers to infer the contributing effects of input variables. All three methods achieved satisfactory prediction accuracies of around 88% for crash occurrence prediction and 75% for crash severity level prediction, which suggested the effectiveness of NDS event data on depicting crash scenarios and roadway safety analyses.

Yes / This study examines the effect of carbon price uncertainty on stock price crash risk. Utilizing the dynamic panel model on the data of Chinese listed firms from 2011 to 2018, we find that high carbon price uncertainty increases stock price crash risk. The impact of carbon price uncertainty is more prominent in the heavily polluting industries and during the post-period of the Paris agreement. The two underlying channels through which carbon price uncertainty induces stock price crashes are managers' hoarding of bad news and investors' heterogeneity. Furthermore, reducing information asymmetry inside and outside the firms can mitigate the influence of carbon price uncertainty on stock price crash risk. Our findings demonstrate that carbon price uncertainty as a newly underexplored factor induced by the prevailing curb of catastrophe risks has unintended but important implications on stock prices. / This study was supported by the Project of Social Science Achievement Evaluation Committee of Hunan Province (Grant No. XSP22YBZ160), Hunan Provincial Natural Science Foundation of China (Grant No. 2022JJ40644 and No. 2022JJ40647). / The full-text of this article will be released for public view at the end of the publisher embargo on 24th Oct 2024.

The purpose of this study is to develop and analyze the possibilities of implementing a new crash test method for child bike trailers based on StVZO §67 Explanation 19 Appendix 2 at Thule Test Center or use an alternative method. The study is based on the following three problem statements: can a new method based on StVZO §67 Explanation 19 Appendix 2 replace TÜV and RISE test methods? Is it possible to implement a new test method in Thule Crash Lab using the acceleration sled track or using a different approach? How can crash testing contribute to optimizing the development of child bike trailers? This study began with background information and the problem description of Thule’s lack of test method and their need for a new alternative. The theorical background provides information about testing for product development. It also provides information about StVZO §67 Explanation 19 Appendix 2 which will be the basis for the study and the previous test methods Thule has used, which were RISE and TÜV.  Observations, analyzes and an interview from the previous test methods established the foundation for the concept study which included brainstorming sessions to generate concepts for the new test method. The concepts consisted both of methods with and without the acceleration sled track. Several workshops served as concept selections which filtered out concepts that exceeded limitations of the facilities at Thule Test Center. The concepts that could not fulfill the requirements from StVZO §67 Explanation 19 Appendix 2 was also filtered out.  To find out if the acceleration sled could be used as a test method, different tests were involved which included evaluation of test impulses and crash tests with handmade fixtures for the child bike trailer. This was carried out to ensure that the crash sled could operate under the variables that was calculated in preparation for the test and that the fixtures could handle the accelerations.  The study also included discussions and conclusions with suggestions for modifications to the concepts that could not be directly implemented due to the limitations in Thule facilities. Some of the modifications were also taken up as suggestions for further research. The study also included comparison between internal and external testing. The comparison explained the importance for Thule to have an internal test method and generally an alternative for crash testing their child bike trailers. As presented in the study, crash testing is crucial for an optimized development of new child bike trailers to ensure safe, qualitative and durable child bike trailers. It is also crucial to stay competitive in the market. To validate stresses and forces subjected onto the construction of the final test method, static calculations were performed which gave an indication of what dimensions the beams for the construction could have. As discussed, dynamic calculations could have been done to achieve a more precise and accurate result.  The final test method is an example of what Thule could use for crash testing their child bike trailers with the requirements from StVZO §67 Explanation 19 Appendix 2. Design changes are possible if it were to be implemented and the new test method gives Thule an internally option.

Pedestrian countdown signals (PCSs) are viable traffic control devices that assist pedestrians in crossing intersections safely. Despite the fact that PCSs are meant for pedestrians, they also have an impact on drivers’ behavior at intersections. This study focuses on the evaluation of the safety effectiveness of PCSs to drivers in the cities of Jacksonville and Gainesville, Florida. The study employs two Bayesian approaches, before-and-after empirical Bayes (EB) and full Bayes (FB) with a comparison group, to quantify the safety impacts of PCSs to drivers. Specifically, crash modification factors (CMFs), which are estimated using the aforementioned two methods, were used to evaluate the safety effects of PCSs to drivers. Apart from establishing CMFs, crash modification functions (CMFunctions) were also developed to observe the relationship between CMFs and traffic volume. The CMFs were established for distinctive categories of crashes based on crash type (rear-end and angle collisions) and severity level (total, fatal and injury (FI), and property damage only (PDO) collisions). The CMFs findings, using the EB approach indicated that installing PCSs result in a significant improvement of driver’s safety, at a 95% confidence interval (CI), by a 8.8% reduction in total crashes, a 8.0% reduction in rear-end crashes, and a 7.1% reduction in PDO crashes. In addition, FI crashes and angle crashes were observed to be reduced by 4.8%, whereas a 4.6% reduction in angle crashes was observed. In the case of the FB approach, PCSs were observed to be effective and significant, at a 95% Bayesian credible interval (BCI), for a total (Mean = 0.894, 95% BCI (0.828, 0.911)), PDO (Mean = 0.908, 95% BCI (0.838, 0.953)), and rear-end (Mean = 0.920, 95% BCI (0.842, 0.942)) crashes. The results of two crash categories such as FI (Mean = 0.957, 95% BCI (0.886, 1. 020)) and angle (Mean = 0.969, 95% BCI (0.931, 1.022)) crashes are less than one but are not significant at the 95 % BCI. Also, discussed in this study are the CMFunctions, showing the relationship between the developed CMFs and total entering traffic volume, obtained by combining the total traffic on the major and the minor approaches. In addition, the CMFunctions developed using the FB indicated the relationship between the estimated CMFs with the post-treatment year. The CMFunctions developed in this study clearly show that the treatment effectiveness varies considerably with post-treatment time and traffic volume. Moreover, using the FB methodology, the results suggest the treatment effectiveness increased over time in the post-treatment years for the crash categories with two important indicators of effectiveness, i.e., total and PDO, and rear-end crashes. Nevertheless, the treatment effectiveness on rear-end crashes is observed to decline with post-treatment time, although the base value is still less than one for all the three years. In summary, the results suggest the usefulness of PCSs for drivers.

Séries temporais financeiras, como índices de mercado e preços de ativos, são produzidas por interações complexas dos agentes que participam do mercado. As propriedades fractais e multifractais destas séries fornecem evidências para detectar com antecedência a ocorrência de movimentos bruscos de mercado (crashes). Tais evidências são obtidas ao aplicar o conceito de Calor Específico Análogo C(q), proveniente da equivalência entre a Multifractalidade e Termodinâmica. Na proximidade de um crash, C(q) apresenta um ombro anômalo à direita de sua curva, enquanto que na ausência de um crash, possui o formato parecido com uma distribuição gaussiana. Com base neste comportamento, o presente trabalho propõe um novo indicador temporal IA(i), definido como a taxa de variação da área sob a curva de C(q). O indicador foi construído por intermédio de uma janela temporal de tamanho s que se movimenta ao longo da série, simulando a entrada de dados na série ao longo do tempo. A análise de IA(i) permite detectar com antecedência a ocorrência de grandes movimentos, como os famosos crashes de 1929 e 1987 para os índices Dow Jones, S&P500 e Nasdaq. Além disso, a análise simultânea de medidas como a Energia Livre, a Dimensão Multifractal e o Espectro Multifractal, sugerem que um crash de mercado se assemelha a uma transição de fase. A robustez do método para diferentes ativos e diferentes períodos de tempo, demonstra a importância dos resultados. Além disso, modelos estatísticos não lineares para a volatilidade foram empregados no trabalho para estudar grandes flutuações causadas por crashes e crises financeiras ao longo do tempo. / Financial time series such as market index and asset prices, are produced by complex interactions of agents that trade in the market. The fractal and multifractal properties of these series provides evidence for early detection of the occurrence of sudden market movements (crashes). This evidence is obtained by applying the concept of Analog Specific Heat C(q), from the equivalence between the Multifractal Analysis and Thermodynamics. In the vicinity of a crash, C(q) exhibits a shoulder at the right side of its curve, while in the absence of a crash, C(q) presents a form similar to a Gaussian distribution curve. Based on this behavior, it is proposed in this work a new temporal indicator IA(i) defined here as the area variation rate over the Specific Heat function. We have constructed the mentioned indicator from a window of data with the first points (size s), that moves throughout the series, simulating the actual input of data over time. The indicator IA(i) allows one detecting in advance the occurrence of large financial market movements, such as those occurred in 1929 and 1987 for the marked indexes Dow Jones, Nasdaq and S&P500. Moreover, the simultaneous analysis of measures such as the Free Energy, Multifractal Dimension and Multifractal Spectrum suggest that a market crash resembles a phase transition. The robustness of the method for others assets and different periods of time demonstrates the importance of the results. Moreover, nonlinear statistical models for volatility have been employed in the work to study large fluctuations caused by crashes and financial crises over time.

Séries temporais financeiras, como índices de mercado e preços de ativos, são produzidas por interações complexas dos agentes que participam do mercado. As propriedades fractais e multifractais destas séries fornecem evidências para detectar com antecedência a ocorrência de movimentos bruscos de mercado (crashes). Tais evidências são obtidas ao aplicar o conceito de Calor Específico Análogo C(q), proveniente da equivalência entre a Multifractalidade e Termodinâmica. Na proximidade de um crash, C(q) apresenta um ombro anômalo à direita de sua curva, enquanto que na ausência de um crash, possui o formato parecido com uma distribuição gaussiana. Com base neste comportamento, o presente trabalho propõe um novo indicador temporal IA(i), definido como a taxa de variação da área sob a curva de C(q). O indicador foi construído por intermédio de uma janela temporal de tamanho s que se movimenta ao longo da série, simulando a entrada de dados na série ao longo do tempo. A análise de IA(i) permite detectar com antecedência a ocorrência de grandes movimentos, como os famosos crashes de 1929 e 1987 para os índices Dow Jones, S&P500 e Nasdaq. Além disso, a análise simultânea de medidas como a Energia Livre, a Dimensão Multifractal e o Espectro Multifractal, sugerem que um crash de mercado se assemelha a uma transição de fase. A robustez do método para diferentes ativos e diferentes períodos de tempo, demonstra a importância dos resultados. Além disso, modelos estatísticos não lineares para a volatilidade foram empregados no trabalho para estudar grandes flutuações causadas por crashes e crises financeiras ao longo do tempo. / Financial time series such as market index and asset prices, are produced by complex interactions of agents that trade in the market. The fractal and multifractal properties of these series provides evidence for early detection of the occurrence of sudden market movements (crashes). This evidence is obtained by applying the concept of Analog Specific Heat C(q), from the equivalence between the Multifractal Analysis and Thermodynamics. In the vicinity of a crash, C(q) exhibits a shoulder at the right side of its curve, while in the absence of a crash, C(q) presents a form similar to a Gaussian distribution curve. Based on this behavior, it is proposed in this work a new temporal indicator IA(i) defined here as the area variation rate over the Specific Heat function. We have constructed the mentioned indicator from a window of data with the first points (size s), that moves throughout the series, simulating the actual input of data over time. The indicator IA(i) allows one detecting in advance the occurrence of large financial market movements, such as those occurred in 1929 and 1987 for the marked indexes Dow Jones, Nasdaq and S&P500. Moreover, the simultaneous analysis of measures such as the Free Energy, Multifractal Dimension and Multifractal Spectrum suggest that a market crash resembles a phase transition. The robustness of the method for others assets and different periods of time demonstrates the importance of the results. Moreover, nonlinear statistical models for volatility have been employed in the work to study large fluctuations caused by crashes and financial crises over time.

L’essai de type simple recouvrement est très largement utilisé dans l’industrie automobile pour évaluer la compatibilité entre une tôle d’acier et une colle. Dans ce cadre, deux critères de validation ont été définis par les constructeurs automobiles : un chargement à rupture minimum, et un facies de rupture cohésif. La rupture au niveau de l’interface colle/acier (rupture interfaciale), ne permet pas d’attester d’une bonne adhésion entre la colle et la tôle, elle n’est donc pas acceptée. Ainsi dans certains cas, l’assemblage n’est pas validé à cause de son faciès de rupture, même s’il démontre une résistance mécanique élevée. Une meilleure compréhension du phénomène de rupture interfaciale permettrait d’adapter le cahier des charges des constructeurs automobiles. Le premier objectif de la thèse a été de comprendre les mécanismes de rupture qui peuvent engendrer une rupture interfaciale. Des études expérimentales et numériques ont montré que la rigidité de la tôle a une forte influence sur la cinématique de déformation de l’éprouvette (rotation, plasticité de la tôle, effet de bords), et qu’elle influe beaucoup sur le faciès de rupture. La déformation plastique de la tôle semble être un paramètre-clef favorisant la rupture interfaciale. En effet, une étude à l’échelle microscopique sur la structure hétérogène du revêtement galvanique de la tôle a mis en évidence la présence de déformations localisées très importantes, qui semblent capable d’endommager l’interface collée. Le second objectif de la thèse a été de caractériser mécaniquement une interface tôle/adhésif. Deux méthodes complémentaires ont été proposées. La première consistait à caractériser l’interface dans des conditions « pures » de sollicitation, grâce à l’essai Arcan modifié. La seconde méthode a permis d’évaluer la capacité de l’interfaces à résister à un effet de bord, grâce à un essai de flexion trois points sur une éprouvette en coin. / The single lap-shear test is widely used by carmakers to characterize the adhesion of bonded joints. Two criteria govern the validation of the adhesion properties in the bonded joints: the shear strength and the failure mode which has to be cohesive. However, in some special cases, particularly when thin mild galvanized steel substrates were bonded with structural toughened adhesive, an interfacial pattern is obtained instead of cohesive failure. So the bonded assembly is not accepted even if its shear load at failure is high. A better understanding of the interfacial failure is required to adapt the carmakers specifications. The first objective of the PhD thesis was to analyze the critical phenomenon which favor the interfacial failure during single lap test. Substrate rigidity has significant effect on the failure pattern, because it influences the kinematic of deformation of the sample (rotation, steel plasticity, edge effect). Steel plasticity has been identified as a key factor for interfacial failure. The galvanized coating of the steel has a heterogeneous structure, which generate significant heterogeneous strain that could damage the interface. The second objective was to characterize the strength of the substrate-adhesive interface. Two methods have been proposed. The first one enable to measure the strength of an interface which homogeneous loading without edge effect (modified Arcan test). In the second method, the interface capability to resist to edge effects has been assessed. Thus, three different interfaces have been characterized using a three point bending test and thanks to an optical microscopy in situ analysis.

The main objective of this thesis is construction of crash test dummy for vehicle-pedestrian crash tests. There is review of nowadays used crash test dummies types in the introduction of this thesis. This is followed by part describing construction itself. Chapter about construction begins by characterizing of used materials features in relation with real human body physiology. Main part of chapter is describing construction of crash test dummy’s skeleton and its individual components including 3D modelling and strength analysis. Thesis is finished by cost assessment.

The strive for lower fuel consumption and downsizing in the automotive industry has led to the use of alternative high performance materials, such as fibre composites. Designing chassis components with composite materials require accurate simulation models in order to capture the behaviour in car crashes. By simplifying the development process of a B-pillar with a new dynamic test method, composite material products could reach the market faster. The setup has to predict a cars side impact crash performance by only testing the B-pillar in a component based environment. The new dynamic test method with more realistic behaviour gives a better estimation of how the B-pillar, and therefore the car, will perform in a full-scale car side impact test. With the new improved tool for the development process, the search for a lighter product with better crash worthiness is done by optimising a steel carbon fibre hybrid structure in the B-pillar. The optimisation includes different carbon fibre materials, composite laminate lay-up and stiffness analysis. By upgrading simulation models with new material and adhesive representation physical prototypes could be built to verify the results. Finally the manufactured steel carbon fibre hybrid B-pillar prototypes were tested in the developed dynamic test method for a comparison to the steel B-pillar. The hybrid B-pillars perform better than the reference steel B-pillar in the dynamic tests also being considerably lighter. As a final result a hybrid B-pillar is developed that will decrease fuel consumption and meet the requirements of any standardized side impact crash test. / Strävan efter lägre bränsleförbrukning och minimalistiskt tänkande inom bilindustrin har lett till användning av alternativa högpresterande material, såsom fiberkompositer. Vid design av chassi-komponenter utav kompositer krävs noggranna simuleringsmodeller för att fånga upp bilens beteende vid en krock. Genom att förenkla utvecklingsprocessen för en B-stolpe med en ny dynamisk testmetod kan produkter bestående av fiberkompositer nå marknaden snabbare. Provuppställningen skall förutse bilens prestanda vid ett sidokrocktest genom att endast testa B-stolpen i en komponentbaserad miljö. Den nya dynamiska testmetoden med ett mer realistiskt beteende skall ge en bättre uppskattning om hur B-stolpen, och därmed bilen, kommer att prestera i ett fullskaligt sidokrocktest. Med utvecklingsprocessens nya förbättrade verktyg kan strävan mot lättare produkter med bättre krocksäkerhet utvecklas genom optimering av en hybrid B-stolpe i stål och kolfiber. Optimeringen innefattar olika kolfibermaterial, laminatvarianter och styvhetsanalyser. Genom att uppgradera simuleringsmodeller med nya material och adhesiva metoder kunde fysiska prototyper tillverkas för att verifiera resultaten. Slutligen testades de tillverkade prototyperna utav stål och kolfiber i den nyutvecklade dynamiska testmetoden för jämförelse mot den ursprungliga stål B-stolpen. Hybrid B-stolparna presterade bättre än referensstolpen utav stål i de dynamiska provningarna och är samtidigt betydligt lättare. Det slutgiltigt resultatet är en utvecklad hybrid B-stolpe som både ger minskad bränsleförbrukningen och uppfyller kraven för ett standardiserat sidokrocktest.