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Zuber-Skerritt, Ortrun Dorothea, and mikewood@deakin edu au. "Action research in higher education: The advancement of university learning and teaching." Deakin University. School of Education, 1987. http://tux.lib.deakin.edu.au./adt-VDU/public/adt-VDU20050902.102949.
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This thesis aims to contribute to the improvement and advancement of university learning, teaching, and staff development; to integrate educational theory and the practice of university teaching; and to contribute to the establishment of a new, emerging paradigm in higher education. The strategy towards achieving these aims comprises (1) an alternative research methodology in the interpretive, non-positivist paradigm; (2) an integrated framework drawing on a variety of previously unrelated theories to form an alternative model of university education; and (3) reference to the dialectical relationship between educational theory and teaching practice and their integration through action research in higher education.
The thesis is not so much a critique of the traditional paradigm and of existing functionalist-structuralist approaches to higher education, but more a development and clarification of an alternative, dialectical, human action approach to higher education. The original contribution of this thesis to the theory and practice of higher education lies in the development (1) of an alternative model of university education based on an integration of previously unrelated domains of theory; (2) of a theoretical model of professional development as action research (the CRASP Model: Critical attitude, Research into teaching, Accountability, Self-evaluation, Professionalism); and (3) of action research projects in higher education.
Action research is research by the university teachers themselves into their teaching practice, i.e. into problems of the curriculum and student learning. The case studies included in and appended to this thesis show that in one educational setting at least it was possible to improve and advance university learning and teaching through action research. The evidence for this advancement is provided in a number of previously published case studies compiled in the Appendix.
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Martin, Michael T. "Christian Crash Course." Digital Commons at Loyola Marymount University and Loyola Law School, 2010. https://digitalcommons.lmu.edu/etd/116.
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Janeček, Milan. "Crash Analysis Portal." Master's thesis, Vysoké učení technické v Brně. Fakulta informačních technologií, 2008. http://www.nusl.cz/ntk/nusl-235982.
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This work presents problems of software products field failure analysis and introduces terms a field failure and a system for field failures analysis. Rest of this work contains requirements analysis and design of one part of the system for field failures analysis a central. A part of the central is then implemented and design correctness and practical usability of the central is evaluated.
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Argenta, Marshall. "Crash Tested: Galactic Modern." Kent State University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=kent1524434869769979.
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Uribe, Vidal José Patricio. "Opacidad, retorno y crash." Tesis, Universidad de Chile, 2015. http://repositorio.uchile.cl/handle/2250/134564.
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Tesis para optar al grado de Magíster en FinanzasSin lugar a dudas, la creciente preocupación por la eficiencia de los mercados1, tanto en el ámbito académico como entre profesionales y autoridades reguladoras, viene motivada por los múltiples escándalos financieros en las últimas décadas2 y se ha enfocado en cómo fortalecer este aspecto vía el mejoramiento de la transparencia de la información divulgada por las empresas. Particularmente, las autoridades reguladoras han tomado conciencia acerca del rol que cumple la información financiera y han promulgado una serie de reformas a los sistemas financieros, incluyendo aquellas relacionadas con el gobierno corporativo, las normativas contables y el papel que cumple la función de auditoría (Klapper y Love, 2004; Kothari et al., 2010; Baxter y Cotter, 2009). Casos como el de Worldcom (2002) y Enron (2001) en el contexto norteamericano y La Polar (2011) para el caso chileno han generado grandes pérdidas para accionistas y acreedores. Cabe señalar, que ex –ante al caso La Polar, Chile no había presentado mayores problemas relacionados con un engaño sistemático al mercado a través de información contable. Otros escándalos, como el de Enron, han traído consigo la promulgación de leyes como la Sarbanes-Oxley3, la cual introdujo muchos cambios a la regulación y prácticas financieras, así como al gobierno corporativo, lo que ha ayudado a disminuir el manejo arbitrario de los estados financieros respecto a los ingresos de las firmas (Cohen, Dey & Lys 2008). No cabe duda que la transparencia de los estados financieros es crucial, especialmente dado que en los últimos años el mercado Chileno ha crecido de forma sostenible. Según el Reporte de competitividad global del Foro Económico Mundial 2013-2014, Chile está en el lugar 20 de 148 países respecto al Desarrollo del Mercado Financiero y tiene el puesto 8 respecto al tamaño total de las firmas nacionales en bolsa (capitalización bursátil) como porcentaje del PIB (117,67%) para el año 2012 de la región, en ambos casos por sobre muchas economías desarrolladas, y con PIB parecido por lo que es un tema relevante para estudiar en Chile, tomando en cuenta que la literatura es relativamente nueva (1990 en adelante) y que en la región y el país existen muy pocas investigaciones al respecto.
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Alfallaj, Ibrahim Saleh. "Analysis of Crash Location and Crash Severity Related to Work Zones in Ohio." University of Dayton / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1406912337.
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Doohan, Isabelle. "Surviving a major bus crash : experiences from the crash and five years after." Doctoral thesis, Umeå universitet, Kirurgi, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-140198.
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Background Major road traffic crashes (RTCs) can have a significant impact on the survivors, their family, and their friends, as well as on emergency personnel, volunteers, and others involved. However, survivors’ perspectives are rare or missing in research on major RTCs in Sweden. A comprehensive understanding of the survivors and their experiences is also lacking. By studying what it is like to survive a major RTC, the care and support provided to survivors can be adapted and improved. The overall aim is to broaden the understanding of the short- and long-term consequences and experiences of surviving a major bus crash. Methods The contexts are two bus crashes that occurred in Sweden, in February 2007 and December 2014. In total, the participants are 110 out of the 112 survivors, and the data is collected through telephone interviews, official reports, and medical records at one month, three months, and five years after the crashes. Analysis methods include qualitative content analysis, descriptive statistics, thematic analysis, and mixed methods research analysis. Results One month after the crash, most of the survivors were experiencing minor or major physical and/or psychological stress in their everyday lives (Study I). Four main findings were identified regarding their experiences of immediate care (Study II): prehospital discomfort, lack of compassionate care, dissatisfaction with crisis support, and satisfactory initial care and support. The importance of compassion and being close to others was also highlighted. Five years after the bus crash in Rasbo (Study III), survivors were still struggling with physical injuries and mental problems. Other long-term consequences were a lasting sense of connectedness among fellow passengers, a gratitude for life, as well as feelings of distress in traffic, especially in regard to buses. The main findings from study IV indicated that injury severity did not seem to affect mental health, and that social aspects were important to the recovery process. There was an interconnection among survivors in which they seemed to be linked to each other’s recovery. Conclusion A strong need for short- and long-term social and psychological support in terms of compassion and community is evident in all the studies. The survivors ought to be acknowledged as capable and having the resources to contribute to their own and their fellow survivors’ recovery and health. There is a need for greater understanding of how different the survivors are, with each one of them having various physical, psychological, social, and existential needs.Bakgrund Stora trafikskadehändelser kan ha en betydande inverkan på de överlevande och deras närståendes liv, likaså på sjukvårdspersonal, vittnen, och andra som är involverade. Trots detta så är de överlevandes perspektiv sällsynta eller saknas i forskning om stora trafikskadehändelser i Sverige. Det saknas även en helhetsförståelse av överlevande och deras erfarenheter. Genom att studera hur det är att överleva en busskrasch kan omhändertagande och stöd anpassas och förbättras. Det övergripande syftet är att öka förståelsen av kort- och långsiktiga konsekvenser och erfarenheter av att överleva en stor busskrasch. Metod Kontexten är två busskrascher som inträffade i februari 2007 och december 2014 i Sverige. Antal deltagare är 110 av 112 överlevande och data samlades in en månad, tre månader och fem år efter krascherna, via telefonintervjuer, officiella rapporter och medicinska journaler. Analysmetoder inkluderar kvalitativ innehållsanalys, deskriptiv statistik, tematisk analys och mixad metod. Resultat En månad efter kraschen upplevde överlevande fysiskt obehag och/eller psykisk stress i varierande grad i sin vardag (Studie I). Gällande upplevelser av det initiala omhändertagandet (Studie II) identifierades fyra huvudresultat; obehag på skadeplats, brister i omhändertagande och bemötande, missnöje med krisstöd, och tillfredsställande initialt omhändertagande och stöd. Betydelsen av empati och medkänsla från personal och frivilliga samt samhörighet med medpassagerare lyftes fram av de överlevande. Fem år efter busskraschen i Rasbo (Studie III) fanns det överlevande som fortfarande kämpade med fysiska skador och psykiska problem. Andra tydliga långsiktiga konsekvenser var en bestående gemenskap mellan medpassagerare, en tacksamhet över livet, samt oro och rädsla i trafiken, speciellt vid bussåkande. Uppföljningen efter busskraschen i Tranemo (Studie IV) indikerade att sociala aspekter var betydelsefulla för återhämtningsprocessen hos överlevande och att skadornas svårighetsgrad inte var betydande för det psykiska välbefinnandet. En stark samhörighet upplevdes bland de närstående som reste tillsammans och de verkade följa varandras återhämtning. Slutsatser Ett starkt behov av kort- och långsiktigt socialt och psykologiskt stöd i form av gemenskap och empati är tydligt i samtliga studier. De överlevande bör uppmärksammas som aktörer med kapacitet och resurser till att bidra till sin egen och medpassagerares återhämtning och hälsa. Det behövs en ökad förståelse för hur olika de överlevande är, med varierande fysiska, psykologiska, sociala, och existentiella behov.
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Burvall, Caroline, Mireille Elin Fumba, and Nina Koukara. "Crash Boom Bang : Tvärkulturell kommunikation." Thesis, University of Kalmar, Baltic Business School, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:hik:diva-1898.
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Can the lack of functional cross-cultural communication among individuals within an international organization be the reason for cultural clashes to occur, and lead to conflict between two cultures within the same organization?
Our aim is to try to create a potential model of how cross-cultural problems can be studied, in order to contribute to the solution of the problem. And to examine whether the theories, which form the basis of our model can be applied in reality.
The research have assumed from the hermeneutical approach for a holistic view of the problem area. The deductive approach has been used in order to distinguish whether the theories can be applied to reality, and qualitative research method for collecting data.
The focus lies within cross-cultural communications, which defines the various cultural factors that can affect organizational culture. Hofstede dimensions and the social structure are mentioned and cultural factors as language and religion. The piece includes the national and organizational culture theory and the establishment strategies. Subsequently the culture clashes, the international business relations and conflict resolution.
Our conclusion is that culture clashes occur and the further away from our own values, attitudes and norms, we get, the more tolerant we relate to other cultures. We note that organizational culture is influenced by individuals which constitutes in it and the theory and reality may not always correspond. That culture is a complexity to study, where tolerance, acceptance and understanding are the most important tools for cross-cultural communication.
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Svensson, Irene, and Tony Wingård. "Crash Memory : SAAB Automobile AB." Thesis, University West, Department of Technology, 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:hv:diva-402.
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Lieb, Claudia. "Crash der Unfall der Moderne." Bielefeld Aisthesis-Verl, 2006. http://d-nb.info/991115597/04.
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Turkoglu, Ata. "Natural time and crash risk." Thesis, University of Essex, 2015. http://repository.essex.ac.uk/16099/.
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The deviation of financial returns from normal distribution is a well‐documented stylized fact. Nonetheless, finance professionals and investors alike pay attention to these deviations almost only when a crisis erases years’ worth of gains. And despite decades’ worth of literature, the culprit for non‐normal distribution of financial returns is still not determined with certainty. In this research, I address the non‐normality of return distributions and financial crashes together. Specifically, I aim to identify the determinants of non‐normality in a high frequency setting and utilize these variables to forecast financial crashes. To this effect, multiple instruments and time horizons are considered. The contribution of this thesis is multifold. The “natural time” approach introduced here, uses order book variables to achieve normally distributed high frequency returns via subordination. In its essence, natural time is a two‐step procedure which uses high frequency order book variables as a gauge for variance while sampling in transaction time. Natural time provides the reader with a new lens to view the financial markets and underscores two important aspects of the high frequency world; sampling frequency affects the distributions we observe and order book variables such as liquidity are the key to heteroscedasticity in asset returns. So much so that subordination with order book variables under transaction time achieves the normal return distribution which underlies numerous financial theories we use today. I further extend the use of these order book variables by introducing the “market heat” metric. Market heat generates successful binary flash crash predictions and its success adds support to the claim that liquidity concerns may be the primary driver of price formation processes. Finally, I expand the findings of this research on high frequency asset returns to a macroeconomic setting by producing currency devaluation predictions for G10 currencies. The early warning systems produced here demonstrate that not only debt related macroeconomic variables but also liquidity related market variables are at play when it comes to currency fluctuations.
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Dias, Ishani Madurangi. "Work zone crash analysis and modeling to identify factors associated with crash severity and frequency." Diss., Kansas State University, 2015. http://hdl.handle.net/2097/20517.
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Doctor of PhilosophyCivil Engineering
Sunanda Dissanayake
Safe and efficient flow of traffic through work zones must be established by improving work zone conditions. Therefore, identifying the factors associated with the severity and the frequency of work zone crashes is important. According to current statistics from the Federal Highway Administration, 2,372 fatalities were associated with motor vehicle traffic crashes in work zones in the United States during the four years from 2010 to 2013. From 2002 to 2014, an average of 1,612 work zone crashes occurred in Kansas each year, making it a serious concern in Kansas. Objectives of this study were to analyze work zone crash characteristics, identify the factors associated with crash severity and frequency, and to identify recommendations to improve work zone safety. Work zone crashes in Kansas from 2010 to 2013 were used to develop crash severity models. Ordered probit regression was used to model the crash severities for daytime, nighttime, multi-vehicle and single-vehicle work zone crashes and for work zones crashes in general. Based on severity models, drivers from 26 to 65 years of age were associated with high crash severities during daytime work zone crashes and driver age was not found significant in nighttime work zone crashes. Use of safety equipment was related to reduced crash severities regardless of the time of the crash. Negative binomial regression was used to model the work zone crash frequency using work zones functioned in Kansas in 2013 and 2014. According to results, increased average daily traffic (AADT) was related to higher number of work zone crashes and work zones in operation at nighttime were related to reduced number of work zone crashes. Findings of this study were used to provide general countermeasure ideas for improving safety of work zones.
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Kusano, Kristofer Darwin. "Methodology for Determining Crash and Injury Reduction from Emerging Crash Prevention Systems in the U.S." Diss., Virginia Tech, 2013. http://hdl.handle.net/10919/23672.
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In order to prevent or mitigate the negative consequences of traffic crashes, automakers are developing active safety systems, which aim to prevent or mitigate collisions. These systems are expensive to develop and as a result automakers and regulators are motivated to forecast the potential benefits of a proposed safety system before it is widely deployed in the vehicle fleet. The objective of this dissertation was to develop a methodology for predicting fleet-wide benefits for emerging crash avoidance systems as if all vehicles were equipped with a system. Forward Collision Avoidance Systems (FCAS) were used as an example application of this methodology.The methodology developed for this research includes the following components: 1) identification of the target population, 2) development and validation of a driver model, 3) development of injury risk functions, 4) development of a crash severity reduction model, and 5) computation of fleet-wide benefits. This dissertation presents a general methodology for each of these components that could be used for any active safety system. Then a specific model is constructed for FCAS.
FCAS could potentially be applicable to 31% of all collisions, 6% of serious injury crashes, and 7% of fatal crashes. Annually, this accounts for 3.3 million collisions and 18,367 fatal crashes. We developed a model of driver braking in response to a forward collision warning. Next we used logistic regression to develop injury risk functions that predicted the probability of injury given the crash severity ("V) and occupant characteristics. Finally, we simulated 2,459 real-world rear-end collisions as if the driver had an FCAS with combinations of warnings, brake assist, and autonomous braking. We found that between 3.4% and 7.2% of crashes could be prevented and that many more could be mitigated in severity. These systems reduced the number of injured (MAIS2+) drivers in rear-end collisions between 32% and 55%. In total, the systems could prevent between $184 and $338 million in economic costs associated with crashes per year.
Ph. D.
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Daouacher, Maria. "Evaluation of occupant kinematics in crash using the PIPER model : in frontal and oblique crash simulations." Thesis, Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-74250.
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A child dies in road traffic crashes every fourth minute. Totally were 186 300 children under the age of 18 killed in vehicle accidents in 2012, even more were severely injured [1]. The World Health Organisation (WHO) could conclude that fatalities in traffic accidents are more likely to occur in low- to middle income countries compared to high income countries [1]. Finite element based human body models has enabled the increased understanding of kinematics and injury mechanisms of child occupants. These models sustain higher biofidelity than the previously used crash test dummies. The European project PIPER [6] had the aim to develop a model that, combined with a framework, would simplify positioning and also to offer a scalable HBM child model. The PIPER framework software and the scalable PIPER model offers child HBM:s within the ages 1.5-6-years old and is an useful tool for the analysis of child occupants. The present study evaluates the kinematics and dummy responses of the 4- and 6-year old PIPER model evaluated. The objective of this master thesis is to evaluate the PIPER model with respect to its sensitivity to seat belt geometries, child restraint system, load cases and child anthropometrics. The aim of the master thesis is to get an increased comprehension of the PIPER model and its capability to evaluate occupant kinematics relevant for safety developments, with a special focus on seat belt geometry and interaction in frontal impacts. The PIPER model showed good sensitivity to different seatbelt geometries regarding the abdominal part of the shoulder belt and to different CRS. The PIPER framework was perceived as hard to use and with the presence of errors. The kinematic response showed good accuracy compared to other previous studies with other crash test dummies however, reoccurring error termination could not be neglectable. The PIPER model is limited to its ease to positioning in desired sitting postures within the PIPER framework. It is regardless of its disadvantages believed to be a suitable tool to further understand occupant kinematics, as for different belt routings, child anthropometrics and dummy responses are further studies needed to validate the outputs that the model offers and to conclude its robustness in crashworthiness tests.
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Blåberg, Christian. "Chest Observer for Crash Safety Enhancement." Thesis, Linköping University, Department of Electrical Engineering, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-12229.
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Feedback control of Chest Acceleration or Chest Deflection is believed to be a good way of minimizing the risk of injury. In order to implement such a controller in a car, an observer estimating these responses is needed. The objective of the study was to develop a model of the dummy’s chest capable of estimating the Chest Acceleration and the Chest Deflection during frontal crashes in real time. The used sensor data come from car accelerometer and spindle rotation sensor of the belt, the data has been collected from dummies during crash tests. This study has accomplished the aims using a simple linear model of the chest using masses, springs and dampers. The parameters of the model have been estimated through system identification. Two types of black-box models have also been studied, one ARX model and one state-space model. The models have been tested and validated against data coming from different crash setups. The results show that all of the studied models can be used to estimate the dummy responses, the physical grey-box model and the black-box state-space model in particular.
Genom att använda återkoppling av storheterna bröstacceleration och bröstintryck antas man kunna minska risken för skador vid krockar i personbilar. För att kunna implementera detta behövs en observatör för dessa storheter. Målet med denna studie är att ta fram en modell för att kunna skatta accelerationen i bröstkorgen samt bröstintrycket i realtid i frontala krockar. Sensordata som använts kom från en accelerometer och en givare för att mäta rotationen i bältessnurran. Detta har gjorts genom att modellera bröstkorgen med linjära fjädrar och dämpare. Dess parametrar har skattats från data från krocktester från krockdockor. Två s.k. black-box-modeller har också tagits fram, en ARX-modell och en på tillståndsform. Modellerna har testats och validerats mha data från olika sorters krocktester. Resultaten visar att alla studerade modeller kan användas för att skatta de ovan nämnda storheterna, den fysikaliska modellen och black-box-modellen på tillståndsform fungerade bäst.
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Hua, Tan Cuong. "Uncertain crash model, theory and applications." Thesis, Imperial College London, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.440514.
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Hopkins, Roisin. "System identification for crash victim simulation." Thesis, Loughborough University, 1995. https://dspace.lboro.ac.uk/2134/7053.
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The work presented in this thesis concerns the identification of vehicle occupant models. Mathematical models of the vehicle occupant are used in the preliminary design and development phase of vehicle design. In the design phase, the model is used to guide the decision on restraint system feasibility. In the development phase the model is used to suggest solutions to problems associated with the dummy trajectory or restraint system performance. Current methods used -to determine such models involve independent component testing. The conditions under which the components are tested are often not typical of a crash test, hence iterations of the computer model are needed to successively improve model and test correlation. In order to address these problems which cause inaccurate specification of the mathematical models, an alternative method of data set assembly for crash victim models is suggested. This alternative method is based on the techniques of system identification which allow unknown system parameters to be determined from experimental input/output data. Initially the viability of using system identification techniques to develop a valid mathematical model of the vehicle occupant and restraint system was investigated. This initial study used input and output measurementsfr om computer simulations of the occupant in frontal impact, as source data for the identification. Effects of simulated disturbances (noise corrupted output signals) and the effects of simplified model structure on the identification are also investigated. Several methods for analysing the likely errors in the identified parameters are defined and discussed in this simulation study. Results relating to the identification of seat contact and seat belt characteristics from physical tests are also presented and these are interpreted in light of the simulation results.
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Chen, Haogang. "Certifying a crash-safe file system." Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/107325.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2016.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 93-99).
File systems are a cornerstone for storing and retrieving permanent data, yet they are complex enough to have bugs that might cause data loss, especially in the face of system crashes. FSCQ is the first file system that (1) provides a precise specification for the core subset of POSIX file-system APIs; and the APIs include fsync and fdatasync, which allow applications to achieve high I/O performance and crash safety, and that (2) provides a machine-checked proof that its I/O-efficient implementation meets this precise specification. FSCQ's proofs avoid crash-safety bugs that have plagued file systems, such as forgetting to insert a disk-write barrier between writing the data from the log and writing the log's commit block. FSCQ's specification also allows applications to prove their own crash safety, avoiding application-level bugs such as forgetting to invoke fsync on both the file and the containing directory. As a result, applications on FSCQ can provide strong guarantees: they will not lose data under any sequence of crashes. To state FSCQ's theorems, FSCQ introduces the Crash Hoare Logic (CHL), which extends traditional Hoare logic with a crash condition, a recovery procedure, and logical address spaces for specifying disk states at different abstraction levels. CHL also reduces the proof effort for developers through proof automation. Using CHL, the thesis developed, specified, and proved the correctness of the FSCQ file system. FSCQ introduces a metadata-prefix specification that captures the properties of fsync and fdatasync, based on Linux ext4's behavior. FSCQ also introduces disk sequences and disk relations to help formalize the metadata-prefix specification. The evaluation shows that FSCQ enables end-to-end verification of application crash safety, and that FSCQ's optimizations achieve I/O performance on par with that of Linux ext4.
by Haogang Chen.
Ph. D.
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Lavaud, Gael. "Optimisation robuste appliquée au crash automobile." Ecully, Ecole centrale de Lyon, 2007. http://bibli.ec-lyon.fr/exl-doc/TH_T2092_glavaud.pdf.
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Dans ce mémoire, nous abordons le problème de la conception robuste des systèmes complexes par simulations numériques. Nous menons une analyse rigoureuse des cycles de développement utilisés chez RENAULT et proposons des voies d’amélioration concrètes. Ces améliorations tirent leur inspiration de la stratégie FIRST DESIGN basée sur l’Ingénierie Système et le concept de robustesse décliné à toutes les étapes du cycle de développement du produit. Cette approche utilise les nouveaux outils de conception, tant statistiques que de modélisation. Cette stratégie permet d’éviter les coûteuses impasses de conception liées à un mauvais déploiement du cahier des charges. Pour étayer notre discours, deux cas concrets de conception en dynamique rapide sont étudiés. Une des particularités de ce domaine physique est le coût important de chaque simulation, ce qui nécessite la mise en place de stratégies d’économie des simulations. La première application concerne l’optimisation de forme d’un capot pour le choc piéton. Dans ce travail, nous développons un outil générique d’optimisation pour les concepteurs et le mettons en oeuvre pour trouver une forme de capot satisfaisant le cahier des charges. Pour réduire le nombre de simulations, nous proposons également un paramétrage adapté au problème et une stratégie de validation progressive des nouvelles géométries. La seconde application concerne la conception robuste en crash frontal. Les méthodes traditionnelles de conception robuste n’apportant pas complète satisfaction, nous développons une approche originale basée sur l’étude des scénarios de crash. En identifiant les éléments instables de la structure, cette méthode permet de stabiliser le comportement global de la structure en ne reconcevant qu’un minimum de pièces. L’ensemble des outils développés au cours de ces travaux vise à tirer le meilleur parti des nouveaux outils de conception, mais également du savoir faire des concepteurs. Les forts gains en prestation et en délai de conception constatés sur les exemples d’application attestent de la nécessité de remettre en cause l’approche traditionnelle de la conception et d’intégrer les nouveaux outils de conception numériquesThis PhD thesis deals with robust design of complex systems with numerical simulations. The analysis of RENAULT design strategy suggests us concrete improvements based on the FIRST DESIGN methodology. This strategy relies on Engineering System ant the concept of robustness applied to all design step of the product. It uses all new design tools, as well statistical as modeling. This strategy allows designers to avoid design resource consuming and time demanding iterations. We use two concrete case study to illustrate our work. These cases take place in the context of costly simulations, that is why we will have to save them. First case study is about shape optimization of a pedestrian hood panel. We develop an industrial optimization tool and use it to find a satisfying shape. To save simulations, we also develop a special parameterization and a progressive validation of new shapes. Second case study is about robust design of a frontal crash. As traditional approaches could not fit our problem, we develop an original strategy based on crash scenarios. This method allows designers to identify unstable structural elements and to stabilize their behavior during the crash in the best conditions. All the tools developed along this work tend to take the best advantage of both new simulations tools and designers experience. Improvements of performance and design time on both cases study prove the interest of modifying the traditional design strategy to incorporate new numerical design tools
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KASHAYI, NAGARAJU C. "MODELING BASE CRASH RATES FOR INTERSECTIONS." University of Cincinnati / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1163775240.
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Meadows, M. L. "Psychological correlates of road crash types." Thesis, University of Manchester, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.517146.
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The research reported in this thesis examines possible psychological correlates of road crash involvement, both that of car drivers in general and that of young drivers in particular. In Chapter One the importance of the prevention of road crashes is discussed. A brief review of the study of driver behaviour summarizes the range of previous research in this area. Various methods of studying driver behaviour are critically discussed. In Chapter Two the over-representation of young drivers in the crash statistics is examined. This chapter provides an overview of previous research into the correlates of young driver crashes. It is suggested that a previously overlooked, possible contributor to road crashes may be the influence of 'extra motives' on driving behaviour. Extra motives are defined as motives of the road user which do not involve the 'official' goals of safety and mobility on the road. Certain extra motives may be particularly salient to young drivers. Chapter Three reports Study One in which a measure of two extra motives was developed in the form of a Driving Motivation Questionnaire (D.M.Q.). This consisted of 50 items derived from Bliersbach and Dellen's (1978, 1980) description of five driving patterns. Bliersbach and Dellen's findings were not replicated. Two factors, driving for thrill and competitive driving, were established through factor analysis. In Chapters Six and Seven a second study is described. For Study Two a second questionnaire was produced to examine the relationship of the extra motives embodied in the D.M.Q. with self-reported commission of driving violations, errors and lapses in the form of the Driving Behaviour Questionnaire (D.B.Q.) (Reason, Manstead, Stradling, Baxter and Campbell, 1990; Reason, Manstead, Stradling, Parker and Baxter, 1991). Development and prior use of the D. B. Q. is di scussed in Chapter Four. The relationship of the D.M.Q. and the D.B.Q. to self-reported, overall crash frequency and to specific types of crashes was studied using a crash typology developed by West (1994). Development and previous use of the crash typology is discussed in Chapter Five. In Chapter Eight the results of the second study are discussed with particular reference to the following issues: 1. The replication of the three factor structure of the D.B.Q. The significant, independent prediction of specific types of crashes by the D.B.Q. factors. 2.The replication of the D.M.Q. Thrill factor obtained in Study One. The significant, independent prediction of specific types of crashes by the Thrill factor. 3.The failure to replicate the D.M.Q. Competition factor obtained in Study One. The attainment of a D.M.Q. Sedate driving factor. 4.The reliability and usefulness of West's classification scheme. 5. The association of varying driver characteristics with distinct crash types, particularly the roles of inexperience and age in young driver crashes. 6. The suggestion that; Driver errors may only have serious consequences when the driver making the error or a nearby driver is violating or thrill seeking; Thrill seeking may only lead to crashes when the driver seeking thrill or another nearby road user makes an error; Violations, on the other hand, may cause crashes no matter how skilful the driver or those drivers nearby.
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Williams, Brian. "Bicycle Crash Detection: Using a Voice-Assistant for More Accurate Reporting." Thesis, University of Oregon, 2018. http://hdl.handle.net/1794/23760.
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It is estimated that over half of bicycle crashes are not reported. There are various reasons for this,
such as no property damage or physical injuries sustained. In order to improve the likelihood
that bicycle riders will report a crash, I have developed Urban Bike Buddy, a smartphone application which
uses the internal sensors of the device to detect a crash. The application interacts with Alexa to help
guide the user through the crash reporting process.
The innovative features of my work are the ability to initiate communication with Alexa without user
interaction. In addition, there is an intersection controller that has been connected to extra hardware
that allows bicycle riders to request a crossing signal during their approach based on the speed that
they are riding. These features add value to bicycle riders, and will help contribute to a safer
environment for bicycle riders, automobiles, and pedestrians as well.
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Graziani, Luca. "Cosmological radiative transfer through metals in CRASH." Diss., lmu, 2012. http://nbn-resolving.de/urn:nbn:de:bvb:19-149355.
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Chiang, K. (Kuoning). "Parallel processing approach for crash dynamic analysis." Diss., Georgia Institute of Technology, 1989. http://hdl.handle.net/1853/17917.
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Al-Senan, Shukri Hasan. "A study of head-on crash sites." Diss., Georgia Institute of Technology, 1985. http://hdl.handle.net/1853/21466.
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Koether, Paul. "GARCH-like models with dynamic crash-probabilities." [S.l.] : [s.n.], 2005. http://deposit.ddb.de/cgi-bin/dokserv?idn=976610248.
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Mandavilli, Srinivas. "Data mining the Kansas traffic-crash database /." Search for this dissertation online, 2006. http://wwwlib.umi.com/cr/ksu/main.
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Kumblekere, Jaikanth B. "A parametric evaluation of vehicle crash performance." Ohio : Ohio University, 1996. http://www.ohiolink.edu/etd/view.cgi?ohiou1178299084.
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Cauchi, Savona Silvano. "Energy absorbing composites for crash energy management." Thesis, Queen Mary, University of London, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.409297.
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Pike, Scott Mason. "Distributed resource allocation with scalable crash containment." Connect to this title online, 2004. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1092857584.
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Thesis (Ph. D.)--Ohio State University, 2004.Title from first page of PDF file. Document formatted into pages; contains xiv, 154 p.; also includes graphics, map. Includes bibliographical references (p. 148-154). Available online via OhioLINK's ETD Center
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Bruch, Olaf. "Materialbeschreibungen für die Crash-Berechnung von Kunststoffbauteilen." Aachen Shaker, 2009. http://d-nb.info/994690061/04.
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Muthyala, Monica. "Design and Crash Analysis of Ladder Chassis." Thesis, Blekinge Tekniska Högskola, Institutionen för maskinteknik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-18475.
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A chassis is known as the carrying unit of an automobile, like the engine, transmission shaft and other parts are mounted on it. Ladder chassis has longitudinal rails which are connected along the length with crossmembers through welding or mechanical fasteners. Rectangular box section is chosen for the longitudinal rails of ladder chassis. Design modifications are done in HyperMesh to improve torsional and bending stiffness of the chassis designed in steel and CFRP. Adding of the X- bracing cross-member and ribs are few of the techniques used to provide strength to chassis. This thesis aims to produce a light-weight chassis. A combination chassis of both steel and CFRP components is created by replacing heavy steel cross-members with CFRP cross-members, which resulted in the reduction of weight by 14.6%. Crash analysis is performed to all the chassis using Radioss. Depending on the result obtained from crash analysis and values of torsional and bending stiffness, the combination chassis is selected. Thickness optimization is performed to the combination chassis. It is observed that 7.91% of weight is further reduced in the combination chassis.
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Li, Yating. "Currency crash risk in the carry trade." Thesis, University of Glasgow, 2017. http://theses.gla.ac.uk/8393/.
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This thesis provides a systematic study of currency crash risk and funding liquidity risk in carry trade strategy in the foreign exchange (FX) market. Carry trade, which involves longing currencies with high interest rate and shorting currencies with low interest rate, is a popular currency trading strategy in the FX market for obtaining annualized excess return as high as 12%. This thesis studies exchange rates of 9 currencies over 13 years from a microstructure perspective. We identify a global skewness factor and use it to measure the currency crash risk. Applying a portfolio approach in cross-sectional asset pricing, we find that global skewness factor explains more than 80% of carry trade excess returns. On the other hand, funding liquidity is effective in predicting the future currency crash risk. Funding liquidity explains more than 70% of carry trade excess returns. We also use the coefficient of price impact from customer order flows to measure the liquidity, which reveals heterogeneous information content possessed by different types of customers. We find that the order flow implied liquidity risk factor can explain a fraction of carry trade excess returns but with small risk premium on quarterly basis. We provide empirical evidence to show that the excess return and crash risk in carry trade is endogenous; i.e., the crash risk premium is inherent in carry trade process. As the natural condition widely affects all investors, we argue that funding constraints are effective in explaining the excess returns of carry trade. When capital moves smoothly in a liquid condition and investor have sufficient funding supply, carry trade is prosperous in the FX market. When investors hit their funding constraints, market-wide liquidity drop, which force the carry trade positions diminishing. The exchange rates respond as that the low interest rate currencies appreciate and high interest rate currencies depreciate, which exacerbates currency crash risk and induces large loss to carry traders. Our cross-sectional analysis provides empirical evidence to show that funding constraints helps to explain the forward premium puzzle and push the exchange rate shift back to the direction the UIP expects.
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Biakeu, Guy. "Modélisation multicorps : application au crash des structures." Ecully, Ecole centrale de Lyon, 2000. http://www.theses.fr/2000ECDL0023.
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Les normes industrielles en matière de sécurité des passagers sont de plus en plus draconiennes et imposent aux constructeurs automobiles, ferroviaires, aéronautiques et navales des tests contraignants en ce qui concerne le crash. De plus, des notions comme la résistance aux chocs et le confort des passagers sont devenues auprès des consommateurs d'excellents arguments de vente. S'il y a quelques années les résultats de crash-tests suffisaient pour valider les structures, de nos jours la course vers la qualité, le souci de bien faire du premier coup et la réduction des coûts amènent les industriels à développer (et même à faire développer) des codes de calcul afin de simuler les structures et d'en optimiser les comportements en amont. Ainsi la technique développée dans ce mémoire entre dans cette immense catégorie de codes avant-projet Elle est basée sur une modélisation multicorps en grands déplacements des structures avec des éléments finis à grandes courbures de flexion et de torsion, que nous avons appelée description grandes courbures (DGC). Dans le plan, les éléments se déforment en arcs de cercle. Le passage à l'espace s'appuie sur une orientation avec les angles d'Euler. Nous introduisons des angles dits élémentaires qui permettent de représenter la déformée de la poutre en postulant une même évolution linéaire sur l'élément. Ces angles élémentaires se justifient d'autant plus qu'en 3D, la notion d'additivé des angles de rotation qui existe en 2D pour la composition de plusieurs rotations est perdue. Nous ajoutons à cette modélisation une représentation synthétique des zones plastiques par des rotules plastiques. Ces dernières sont modélisées par des lois analytiques de type exponentielle négative identifiées à partir d'essais ou de modèles cinématiques comme ceux de Kecman [68]. La localisation de ces dernières est assurée par une interpolation dans toute la structure des moments fléchissants et du moment de torsion. Nous nous sommes limités aux modes de déformation en flexion et en torsion mais cette formulation est extensible à la traction-compression et au cisaillement. Les contraintes géométriques ou structurelles sont analysées avec la technique des multiplicateurs de Lagrange et un schéma explicite de type PC est appliqué pour intégrer les équations du mouvement. Nous comparons les résultats issus de cette modélisation à des calculs sous ABAQUS/Explicit et à certains disponibles dans la littératureIndustrial norms in terms of security and comfort of the passengers cars, aiplanes or boats are becoming more and more draconian. The constructors are now obliged to succeed severe tests like the resistance of their products to crashes or their stability. Moreover, these aspects happenned to be excelent arguments for the marketing departements as consumers prefer solid cars or trains to beautifull ones. On another hand, economic reasons bring industrials to reduce the number of real tests on the full structure and to increase the use of numerical simulation during the conception of vehicules. In this thesis we develop a technique based on multibody modelling of beams. It takes large displacements and large rotations in charge. We called it the Large Curvature Description (LCD). In the plane, the shape of the beam are interpolated with arcs of circle. In the space, we use Euler angles to describe the orientation of the sections and we introduce elementary angles to keep the same linear evolution of the orientation as in the plane. Only bending and torsion deformations are studied but we can extend the formulation to traction and shear. Plastic regions are modelled as nonlinear hinges. The behaviour of these hinges is represented by a mathematical expression in which the collapse appears as a negative exponential The hinges are located with an interpolation of the bending moments and the torsion moment built as a norm on the structure. Constraints systems are solved with the Lagrange multipliers technique and we use an explicit scheme to solve the equations of motion. We compare our results to those of simulation under explicits codes as ABAQUS/Explicit or to techniques developped by authors in the literature
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Roussel, Stephane M. "Sensor Integration for Low-Cost Crash Avoidance." DigitalCommons@CalPoly, 2009. https://digitalcommons.calpoly.edu/theses/184.
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This report is a summary of the development of sensor integration for low-cost crash avoidance for over-land commercial trucks. The goal of the project was to build and test a system composed of low-cost commercially available sensors arranged on a truck trailer to monitor the environment around the truck. The system combines the data from each sensor to increase the reliability of the sensor using a probabilistic data fusion approach. A combination of ultrasonic and magnetoresistive sensors was used in this study. In addition, Radar and digital imaging were investigated as reference signals and possible candidates for additional sensor integration. However, the primary focus of this work is the integration of the ultrasonic and magnetoresistive sensors.
During the investigation the individual sensors were evaluated for their use in the system. This included communication with vendors and lab and field testing. In addition, the sensors were modeled using an analytical mathematical model to help understand and predict the sensor behavior. Next, an algorithm was developed to fuse the data from the individual sensors. A probabilistic approach was used based on Bayesian filtering with a prediction-correction algorithm. Sensor fusion was implemented using joint a probability algorithm. The output of the system is a prediction of the likelihood of the presence of a vehicle in a given region near the host truck trailer. The algorithm was demonstrated on the fusion of an ultrasonic sensor and a magnetic sensor. Testing was conducted using both a light pickup truck and also with a class 8 truck. Various scenarios were evaluated to determine the system performance. These included vehicles passing the host truck from behind and the host truck passing vehicles. Also scenarios were included to test the system at distinguishing other vehicles from objects that are not vehicles such as sign posts, walls or railroads that could produce electronic signals similar to those of vehicles and confuse the system. The test results indicate that the system was successful at predicting the presence and absence of vehicles and also successful at eliminating false positives from objects that are not vehicles with overall accuracy ranging from 90 to 100% depending on the scenario. Some additional improvements in the performance are expected with future improvements in the algorithm discussed in the report.
The report includes a discussion of the mapping of the algorithm output with the implementation of current and future safety and crash avoidance technologies based on the level of confidence of the algorithm output and the seriousness of the impending crash scenario. For example, irreversible countermeasures such as firing an airbag or engaging the brakes should only be initiated if the confidence of the signal is very high, while reversible countermeasures such as warnings to the driver or nearby vehicles can be initiated with a relatively lower confidence.
The results indicate that the system shows good potential as a low cost alternative to competing systems which require multiple, high cost sensors. Truck fleet operators will likely adopt technology only if the costs are justified by reduced damage and insurance costs, therefore developing an effective crash avoidance system at a low cost is required for the technology to be adopted on a large scale.
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Vrachnou, Amalia. "An Analysis of Emergency Vehicle Crash Characteristics." Thesis, Virginia Tech, 2003. http://hdl.handle.net/10919/34612.
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Crash data suggests that intersections are areas producing conflicts among the various road users because of entering and crossing movements. Traffic signal control systems may not always be sufficient in preventing collisions at intersections between emergency and other vehicles. The Firefighter Fatality Retrospective Study of 2002 illustrates that the second leading cause of fatal injury for firefighters is vehicle collisions. Furthermore, the involvement of an emergency vehicle in a crash can negatively affect the overall efficiency of emergency response services. Thus, there is a need to facilitate the implementation of higher-payoff strategies to improve the safety of emergency vehicle passage through signalized intersections. This research aims to provide a basis for the transportation professionals to identify problem areas and take measures that will potentially enhance intersection safety for emergency vehicles. It includes the presentation and comparison of the EV crash situation in Northern Virginia. The results indicate that 49% of all EV accidents along U.S. Highways in Northern Virginia occurred at signalized intersections. This percentage is 75% along U.S. Highways in Fairfax County, the largest county in Northern Virginia, and it is 79% along U.S. 1 in Fairfax County. The analysis, also, illustrates that the major collision type at signalized intersections was of the angle type, which suggests that an appropriate warning sign may be absent. These findings enhance our understanding of emergency vehicle crash characteristics and thus, may facilitate the identification of possible warrants to be used in determining the appropriateness of installing signal preemption equipment at signalized intersections.Master of Science
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Kanke, Jennifer S. "Crash Course in the Philosophy of Passion." Ohio University / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1242835565.
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Jacot-Guillarmod, Paul. "Sobriety of crisp and fuzzy topological spaces." Thesis, Rhodes University, 2004. http://hdl.handle.net/10962/d1005228.
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The objective of this thesis is a survey of crisp and fuzzy sober topological spaces. We begin by examining sobriety of crisp topological spaces. We then extend this to the L- topological case and obtain analogous results and characterizations to those of the crisp case. We then brie y examine semi-sobriety of (L;M)-topological spaces.
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Abdullah, Ahmad Sufian. "Crash simulation of fibre metal laminate fuselage." Thesis, University of Manchester, 2014. https://www.research.manchester.ac.uk/portal/en/theses/crash-simulation-of-fibre-metal-laminate-fuselage(fd254489-243f-4071-8dea-ca9e2dd9d3bc).html.
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A finite element model of fibre metal laminate (FML) fuselage was developed in order to evaluate its impact response under survivable crash event. To create a reliable crash finite element (FE) model of FML fuselage, a ‘building block approach’ is adapted. It involves a series of validation and verification tasks in order to establish reliable material and damage models, verified impact model with structural instability and large displacement and verified individual fuselage structure under crash event. This novel development methodology successfully produced an FE model to simulate crash of both aluminium alloy and FML fuselage under survivable crash event using ABAQUS/Explicit. On the other hand, this allows the author to have privilege to evaluate crashworthiness of fuselage that implements FML fuselage skin for the whole fuselage section for the first time in aircraft research field and industry. The FE models consist of a two station fuselage section with one meter longitudinal length which is based on commercial Boeing 737 aircraft. For FML fuselage, the classical aluminium alloy skin was replaced by GLARE grade 5-2/1. The impact response of both fuselages was compared to each other and the results were discussed in terms of energy dissipation, crushing distance, failure modes, failure mechanisms and acceleration response at floor-level. Overall, it was observed that FML fuselage responded similarly to aluminium alloy fuselage with some minor differences which conclusively gives great confidence to aircraft designer to use FML as fuselage skin for the whole fuselage section. In terms of crushing distance, FML fuselage skin contributed to the failure mechanisms of the fuselage section that lead to higher crushing distance than in aluminium alloy fuselage. The existence of various failure modes within FML caused slight differences from the aluminium fuselage in terms of deformation process and energy dissipation. These complex failure modes could potentially be manipulated to produce future aircraft structure with better crashworthiness performance.
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Sharma, Sanjeev. "Sandwich steels for crash energy absorption applications." Thesis, University of Warwick, 2014. http://wrap.warwick.ac.uk/74157/.
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This thesis has examined the applicability of steel–polypropylene–steel sandwich materials for the role of axial energy absorbers, an application previously undescribed in the literature. The results show that energy absorption performance of steel–polypropylene–steel sandwich materials can be predicted to within –2% and +8%, as well as highlighting the potential for their use in automotive applications. The work has demonstrated that the deformation modes in the steel–polypropylene–steel sandwich mimic the monolithic metal crash structure, however, with smaller fold radii, hypothesised to be due to shear in the polypropylene core. It was observed that increasing the core thickness increased the radius of the folds in the structure when undergoing collapse. Though due to the variability in the folding patterns of sandwich material in the crash structures seen in this work, it could not be stated with certainty. From the physical testing, the effect of core thickness for a fixed skin thickness is also defined. The physical tests showed a linear relationship between increasing core thickness and mean crush force. Further, the effectiveness of increasing the core thickness on the specific energy absorption was identified. The testing also showed an unprecedented >60% increase in energy absorption from quasi–static to dynamic for all three thicknesses of Steelite sandwich material, a level not seen in monolithic metal crash structures. Hence, suggesting an increased strain rate sensitivity of steel in MPM sandwich materials over the monolithic steel, a property which has been suggested in the literature for tensile tests but unknown in axial crash deformation. The testing demonstrated the potential for the crushing mode to change from a desirable progressive crushing mode to an undesirable and difficult to predict progressive failure. This occurred with a 7:1 core to skin thickness ratio, though failure of the steel skin is seen at all ratios. A 70%:30% ratio of thickness for the polypropylene core to steel skin is shown to minimise steel skin failure, i.e. the individual steel skin thickness should be no less than 15% of the total sandwich thickness. Finite element analysis presented in this thesis shows a single shell element model with laminated shell theory invoked can be used in LS–DYNA to predict the performance of the steel–polypropylene–steel sandwich materials. However, there is a potential thickness limit for which the model is applicable for the single hat and backplate crash structure considered; further research would be required to increase the confidence in the model. The single shell element model was accurate to within +8% of the physical test results. An analytical solution fitted the LS–DYNA single shell element model well and showed increasing the core thickness is more effective at increasing the specific energy absorption than increasing the skin thickness. The analytical solution also shows the potential for a steel–polypropylene–steel sandwich with a core to skin ratio of 70%:30% ratio by thickness to equal the performance of high strength aluminium alloys.
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Křižák, Michal. "Využití počítačové podpory při řešení předstřetového pohybu vozidel." Master's thesis, Vysoké učení technické v Brně. Ústav soudního inženýrství, 2012. http://www.nusl.cz/ntk/nusl-232640.
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Thesis deals with comparison of influence of chosen solution method on pre crash movement of vehicles in one simulation program and on differences between calculations for one method in different programs. Compared solution methods are kinematics and dynamics solutions of pre crash movement, compared programs are Virtual CRASH and PC-Crash.
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Durrenberger, Laurent Molinari Alain. "Analyse de la pré-déformation plastique sur la tenue au crash d'une structure crash-box par approches expérimentale numérique." [S.l.] : [s.n.], 2007. ftp://ftp.scd.univ-metz.fr/pub/Theses/2007/Durrenberger.Laurent.SMZ0741.pdf.
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Frisch, Norbert. "Verfahren zur Unterstützung der Arbeitsabläufe bei der Crash-Simulation im Fahrzeugbau." [S.l. : s.n.], 2004. http://www.bsz-bw.de/cgi-bin/xvms.cgi?SWB11051841.
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Mannila, Kranthi Kiran. "ANALYSIS OF VARIOUS CAR-TRUCK CRASH TYPES BASED ON GES AND FARS CRASH DATABASES USING MUTLINOMIAL AND BINARY LOGIT MODEL." Master's thesis, University of Central Florida, 2006. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2583.
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Each year about 400,000 trucks are involved in motor vehicle crashes. Crashes involving a car and truck have always been a major concern due to the heavy fatality rates. These types of crashes result in about 60 percent of all fatal truck crashes and two-thirds of all police-reportable truck crashes. Car-truck crashes need to be analyzed further to study the trends for a car-truck crash and develop some countermeasures to lower these crashes. Various types of car-truck crashes are analyzed in this study and the effects of various roadway/environment factors and variables related to driver characteristics in these car-truck crashes are investigated. To examine the crash characteristics and to investigate the significant factors related to a car-truck crash, this study analyzed five years of data (2000-2004) of the General estimates system of National Sampling System (GES) and the Fatality Analysis Reporting system database (FARS). All two vehicle crashes including either a car or truck (truck-truck cases excluded because of their low percentage composition) were obtained from these databases. Based on the five year data (GES/FARS) the percentage of car-truck angle collisions constituted the highest percent of frequency of all types of car-truck collisions. Furthermore, based on the 2004 GES data there is a clear trend that the frequency of angle collision increases with the increase in driver injury severity. When analyzing the GES data it was observed that the percentage of angle collisions was the highest followed by the rear end and sideswipe (same direction) collisions respectively. When the fatalities were considered (FARS database used), the percentage of angle collisions was the highest followed by head-on and rear-end collisions. The nominal multinomial logit model and logistic regression models were utilized for this analysis. Divided section, alcohol involvement, adverse weather conditions, dark lighting condition and old age of drivers had a significant effect on the car-truck crashes and were likely to increase the likelihood of a car-truck crash. Whereas dark but light conditions, young aged drivers showed a less likelihood of involving in a car-truck crash. This research is significant in providing an insight into various car-truck crash types and provides with results, which have impacted the car-truck crashes. A better understanding of the factors impacting these crashes will help in providing better countermeasures, which would result in reducing the car-truck crashes.M.S.
Department of Civil and Environmental Engineering
Engineering and Computer Science
Civil Engineering
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Durrenberger, Laurent. "Analyse de la pré-déformation plastique sur la tenue au crash d'une structure crash-box par approches expérimentale et numérique." Thesis, Metz, 2007. http://www.theses.fr/2007METZ041S/document.
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Préserver l’intégrité des occupants d’un véhicule lors d’un accident constitue un enjeu majeur pour les constructeurs automobiles depuis de nombreuses années. L’objectif de cette thèse est d’analyser l’effet de la pré-déformation plastique sur la tenue au crash d’une structure de type crash-box. L’histoire du chargement est composée de deux phases. La première est le processus de mise en forme qui est généralement réalisé sous chargement quasi-statique. La seconde phase est caractérisée par un évènement de type crash. Le comportement de trois aciers fréquemment utilisés dans l’industrie automobile a été étudié (BH260, DP600, TRIP800). Des essais en traction uni-axiale ont permis de mettre en évidence l’effet d’un pré-chargement quasi-statique sur la réponse en rechargement dynamique. Une large campagne expérimentale d’écrasement de structures a par ailleurs révélé que le processus de pré-déformation a un effet bénéfique sur la tenue au crash malgré la réduction de l’épaisseur des structures. Deux modèles phénoménologiques sont ensuite proposés pour décrire les effets d’écrouissage et de sensibilité à la vitesse de déformation des métaux. Les prédictions des modèles montrent une très bonne correspondance avec les données expérimentales dans une large gamme de vitesse de déformation et les effets d’histoire de vitesse de déformation peuvent être très bien pris en compte par l’un des modèles. Enfin, une démarche numérique de couplage emboutissage-crash est présentée où les variables calculées lors de la mise en forme (contraintes résiduelles, déformation plastique équivalente, épaisseur finale) sont prises en compte lors de l’écrasement sous chargement dynamiqueTo preserve the integrity of vehicle passengers during a crash constitutes a major goal for the automotive manufacturers since many years. The aim of this Ph-D thesis is to analyze the effect of a plastic prestrain on crash properties of a crash-box structure. The loading history is composed of at least two phases. The first phase is the forming process, in general under quasi-static conditions. The subsequent loading is due to a crash event. The behavior of three steels frequently used in the automotive industry has been studied (BH260, DP600, TRIP800). The experimental characterization of the steels shows the effect of a quasi-static prestrain on subsequent dynamic tensile curves. In addition, a large experimental crushing campaign of structures revealed that the prestrain process improves the crash behavior despite a reduction of the wall thickness. Two phenomenological models are then proposed to describe the strain-hardening effects and strain-rate sensitivity of metals. The model predictions show a very good agreement with experimental results for a wide range of strain-rate. Strain-rate history effects are well accounted for by one of the models. Finally, a numerical approach is performed where the variables calculated during the stamping (residual stress, equivalent plastic deformation, final thickness) are taken into account during the crash simulation under dynamic loading
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Vuong, Thi Thanh Thuy. "Réduction de modèle de crash automobile : application en optimisation." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSEC025.
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La simulation numérique est de plus en plus utilisée dans l’industrie pour réduire le coût lié aux essais physiques. Une simulation de crash (préparation + soumission au solveur + traitement) dure environ une à deux journées. Renault utilise l’optimisation, donc de nombreuses simulations de crash, pour dimensionner ses véhicules. Afin de réduire le coût total d’un ensemble de simulations crash, le but de cette thèse est de proposer une ou des méthodes de réduction de modèle applicables dans un espace paramétrique. Les méthodes proposées dans cette thèse sont non-intrusives et n’obligent donc pas à modifier le solveur ni le modèle. La première méthode testée est la Proper Orthogonal Decomposition. Elle permet de réduire le comportement d’une simulation et de comprendre les propriétés du crash mais l’interpolation dans l’espace paramétrique est plus difficile. La deuxième méthode, ReCUR, est une variante de la décomposition CUR classique. Elle sera montrée comme une forme générale des méthodes non-intrusives. Elle permet de surmonter les deux limites importantes des méthodes de réduction actuelles : taille du modèle élevée et interpolationThe numerical simulation is more and more applied in the industry in order to reduce the physical tests costs. A crash simulation (pre-processing, processing and post-processing) takes about one or two days. Renault uses the optimization, so numerous crash simulations, to size cars. To cut back the total cost of a whole crash simulations, the aim of this thesis is to propose a or some Reduced-Order Model (ROM) methods that can be applied in a parametric space. The suggested methods in this thesis are nonintrusive and neither the solver nor the model should not be modified . The first tested method is the Proper Orthogonal Decomposition. This method allows reducing the behavior of a crash simulation and understanding the crash properties but not interpolating in a parametric space. The second method, ReCUR, is a variant of the classical decomposition CUR. It will be demonstrated as a general form of the non-intrusive methods. It allows overcoming two important limits of actual ROM methods : size of the model and the interpolation
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Schönebeck, Kai. "Ein Inertialmesssystem zur Bewegungserfassung von Dummypuppen in Kfz-Crashtests." Aachen Shaker, 2009. http://d-nb.info/994908539/04.
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Kieliszewski, Cheryl A. "Twisted Metal: An Investigation into Observable Factors that Lead to Critical Traffic Events." Diss., Virginia Tech, 2005. http://hdl.handle.net/10919/29859.
Full textAbstract:
The purpose of this research was to explore traffic event severity relationships, evaluate the potentiality of a hazardous event, and develop a framework of observable event factors. Data was collected from three regions in Virginia, each assumed to exemplify a unique driving environment due to amount of traffic and infrastructure characteristics. In combination, a broad spectrum of site, traffic, and driver performance variables were accounted for. Observational techniques of surveillance, incident reporting, and inventorying were used to collect site, traffic, and driver data. This effort resulted in 368 observed traffic events that were evenly distributed among the three regions that represented metropolitan, mid-sized city, and town/rural driving environments. The 368 events were evaluated for severity and contributing variables where 1% of the events were non-injury crashes, 10% were serious, near-crashes, 24% were near-crashes, and the remaining 65% were serious errors with a hazard present. Exploratory analyses were performed to understand the general relationship between event severity levels. Binary logistic regression analyses (α = 0.05) were performed to further scope predictor variables to identify traffic event characteristics with respect to severity level, maneuver type, and conflict type. The results were that 69 of 162 observed predictor variables were valuable in characterizing traffic events based on severity. It was found that variables could be grouped to create event severity signatures for crashes, serious near-crashes, and near-crashes. Based on these signatures, it was found that there is a trend between severity levels that included a propensity for problems with straight path maneuvers, lateral and longitudinal vehicle control, and information density within the driving environment as contributing to driver error and hence crashes and near-crashes. There were also differences between the severity levels. These differences were evident in the degree of control the driver appeared to have of the vehicle, type of control regulating the driving environment, and type of road users present in the driving environment. Modifications to roadway evaluative techniques would increase awareness of additional variables that impact drivers to make more informed decisions for roadway enhancements.Ph. D.
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Tatem, Whitney M. "The Crash Injury Risk to Rear Seated Passenger Vehicle Occupants." Diss., Virginia Tech, 2020. http://hdl.handle.net/10919/96550.
Full textAbstract:
Historically, rear seat occupants have been at a lower risk of serious injury and fatality in motor vehicle crashes than their front seat counterparts. However, many passive safety advancements that have occurred over the past few decades such as advanced airbag and seatbelt technology primarily benefit occupants of the front seat. Indeed, safety for front seat occupants has improved drastically in the 21st century, but has it improved so much that the front seat is now safer than the rear? Today, rear-seated occupants account for 10% of all passenger vehicle fatalities. In this era focused on achieving zero traffic deaths, the safety of rear-seated occupants must be further addressed.
This dissertation analyzed U.S. national crash data to quantify the risk of injury and fatality to rear-seated passenger vehicle occupants while accounting for the influence of associated crash, vehicle, and occupant characteristics such as crash severity, vehicle model year, and occupant age/sex. In rear impacts, the risk of moderate-to-fatal injury was greater for rear-seated occupants than their front-seated counterparts. In high-severity rear impact crashes, catastrophic occupant compartment collapse can occur and carries with it a great fatality risk. In frontal impacts, there is evidence that the rear versus front seat relative risk of fatality has been increasing in vehicle model years 2007 and newer. Rear-seated occupants often sustained serious thoracic, abdomen, and/or head injuries that are generally related to seatbelt use. Seatbelt pretensioners and load limiters – commonplace technology in the front seating positions – aim to mitigate these types of injuries but are rarely provided as standard safety equipment in the rear seats of vehicles today. Finally, in side impacts, injury and fatality risks to rear- and front-seated occupants are more similar than in the other crash modes studied, though disparities in protection remain, especially in near-side vehicle-to-vehicle crashes. Finally, this work projects great injury reduction benefits if a rear seat belt reminder system were to be widely implemented in the U.S. vehicle fleet.
This dissertation presents a comprehensive investigation of the factors that contribute to rear-seated occupant injury and/or fatality through retrospective studies on rear, front, and side impacts. The overall goal of this dissertation is to better quantify the current risk of injury to rear-seated occupants under a variety of crash conditions, compare this to the current risk to front-seated occupants, and, when possible, identify how exactly injuries are occurring and ways in which they may be prevented in the future. The findings can benefit automakers who seek to improve the effectiveness of rear seat safety systems as well as regulatory agencies seeking to improve was vehicle tests targeting rear seat passenger vehicle safety.Doctor of Philosophy
Historically, if a passenger vehicle such as a sedan or SUV is in a crash, occupants who are rear-seated were less likely to be hurt than someone who was front-seated. In other words, rear-seated occupants have been at a lower risk of injury than front-seated occupants. Indeed, safety for front seat occupants has improved drastically in the 21st century due to advancements in airbag and seatbelt technologies, among others, but has it improved so much that the front seat is now safer than the rear? Today, of all vehicle occupants who are killed in crashes on U.S. roadways, 10% are rear-seated. During this time when conversations surrounding vehicle safety are focused on achieving zero traffic deaths, the safety of rear-seated occupants must be further studied. This dissertation looked at national databases of all police-reported crashes that occur each year in the United States. The risk of injury to rear-seated passenger vehicle occupants was quantified and compared to that of front-seated occupants. Factors that may increase or decrease this risk of injury and fatality such as crash type, vehicle type, and occupant demographics were further explored and reported. In vehicles that were rear-ended, the risk of injury was greater for rear-seated occupants than their front-seated counterparts. When a vehicle crashes into something front-first (the most common type of impact in a vehicle crash), evidence is presented that the risk of fatality is greater in the rear seats than the front seats in model year 2007 and newer vehicles which generally are equipped with the most recent airbag and seatbelt technology. When a vehicle is hit on either of its sides, the risk of injury is closer between rear- and front-seated occupants than it was in the rear-end or frontal crashes previously studied. That said, differences in occupant protection were still observed between the rear and front seats, especially when the occupants studied were seated on the closest side of impact, or the near-side, and the vehicle was struck by another vehicle rather than sliding into an object such as a pole. Finally, this work projects great injury reduction benefits if a rear seat belt reminder system were to be widely implemented in the U.S. vehicle fleet. This dissertation presents a comprehensive investigation of the factors that contribute to rear-seated occupant injury and/or fatality through retrospective studies on rear, front, and side impacts. The overall goal of this dissertation is to better quantify the current risk of injury to rear-seated occupants under a variety of crash conditions, compare this to the current risk to front-seated occupants, and, when possible, identify how exactly injuries are occurring and ways in which they may be prevented in the future. The findings can benefit automakers who seek to improve the effectiveness of rear seat safety systems as well as regulatory agencies seeking to improve was vehicle tests targeting rear seat passenger vehicle safety.
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Baltacioglu, Cem. "Production Of Chips And Crisp From Jerusalem Artichoke." Phd thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614084/index.pdf.
Full textAbstract:
Jerusalem artichoke has been cultivated in various regions without any special breeding technique. On the other hand, in food industry it does not have a wide usage area. Hence, in food industry its use as a potato substitute in some products is believed to be increasing its economical value. As a first attempt chips and crisps produced from Jerusalem artichoke was analyzed for texture, sensory, color, oil and moisture content.
Jerusalem artichoke chips were fried in a bench top deep fat fryer for 120s, 180s and 240s at 160°C, 170°
C, 180°
C and 190°
C. When microwave oven was used samples were cooked for 60s, 75s, 90s, 105s, 120s, 135s and 150s at 600 Watt and 900 Watt. Rheological properties of Jerusalem artichoke puree were investigated and Xanthan gum (2%wb) and sodium metabisulphite (1%wb) added for the desired puree consistence and color. After the production of puree Jerusalem artichoke flour was produced and water added to this flour then dough obtained again. Rheological behaviour of the original puree and these prepared from the containing 1- 4.5 and 1 - 5.0 part water were quite similar. In the light of the experimental results obtained as frying temperature and treatment time increased, moisture content and lightness of the Jerusalem artichoke products have decreased but a*and b* values, hardness, fracture and oil content increased. The best results for frying of Jerusalem artichoke seem to be 180°
C with about 240s treatment time for the chips and the same temperature for 180s for the crisps. As microwave power level and duration of treatment increased, moisture content and lightness of the microwave cooked Jerusalem artichoke products have decreased, but a* and b* values increased. Hardness and fracturability values of the products first increased with time and then decreased. When microwave oven was used, the best results were obtained for about 105s treatment time at 600W for the Jerusalem artichoke chips and about 60s processing time at 900W for the crisp. Since treatment time for cooking was significantly reduced when microwave cooking was used, this method could be recommended as an alternative to conventional deep fat frying, as oil is not used as well.