Emergency braking of a vehicle is bound with many factors, such as the behaviour of the driver, the drive of the vehicle braking system, the braking mechanisms, the condition of the tyres, and the properties of the pavement. This process involves all parameters of the system “the driver – the vehicle – the road”. In order to investigate the efficiency of braking process upon specific conditions, it is necessary to examine all physical processes that take place in the vehicle on pressing the brake pedal. Upon the completion of the experimental and theoretical investigation on emergency braking of vehicles a general mathematical model of vehicle with hydraulic braking system on its emergency braking had been developed. The dynamic, thermodynamic in solid systems and fluid hydrodynamic processes were assessed. The model enables to examine various cases of emergency braking with assessment of the driver’s reaction, parameters of the vehicle’ technical condition and the pavement condition. A general mathematical model of vehicle with hydraulic braking system that’s computing is realized in the system of the applied software Compaq Visual Fortran Professional system provides possibilities for research the hydrodynamic processes that take place in the system of braking; enables to define more closely the movement parameters of the vehicle in the emergency braking mode and may be applied for analysis of traffic events, improvement of vehicle braking systems as well as a manual for... [to full text]

Emergency braking of a vehicle is bound with many factors, such as the behaviour of the driver, the drive of the vehicle braking system, the braking mechanisms, the condition of the tyres, and the properties of the pavement. This process involves all parameters of the system “the driver – the vehicle – the road”. In order to investigate the efficiency of braking process upon specific conditions, it is necessary to examine all physical processes that take place in the vehicle on pressing the brake pedal. Upon the completion of the experimental and theoretical investigation on emergency braking of vehicles a general mathematical model of vehicle with hydraulic braking system on its emergency braking had been developed. The dynamic, thermodynamic in solid systems and fluid hydrodynamic processes were assessed. Model enables to examine various cases of emergency braking with assessment of the driver’s reaction, parameters of the vehicle’ technical condition and the pavement condition. A general mathematical model of vehicle with hydraulic braking system that’s computing is realized in the system of the applied software Compaq Visual Fortran Professional v 6.3 system provides possibilities for research the hydrodynamic processes that take place in the system of braking; enables to define more closely the movement parameters of the vehicle in the emergency braking mode and may be applied for analysis of traffic events, improvement of vehicle braking systems as well as a manual... [to full text]

Thesis (Ph. D.)--Murdoch University, 1997. / Thesis submitted to the School of Social Sciences. Includes bibliographical references (leaves 401-418).

<div>Cities face significant challenges in developing urban infrastructure systems in an inclusive, resilient, and sustainable manner, with rapid urbanization and increasing frequency of shocks (e.g., climate hazards, epidemics). The complex and dynamic interdependencies among urban social, technical, institutional, and natural components could cause disruptions to cascade across systems, and lead to heterogeneous recovery outcomes across communities and regions. Large scale data collected from mobile devices, including mobile phone GPS data, web search data, and social media data, allow us to observe urban dynamics before, during, and after disaster events in an unprecedented spatial-temporal granularity and scale. Despite these opportunities, we lack data-driven methods to understand the underlying mechanisms that govern the recovery and resilience of cities to shocks.</div><div>Such dynamical models, in contrast to static index based metrics of resilience, will allow us to test the effects of policies on the heterogeneous post-disaster recovery trajectories across space and time. </div><div><br></div><div>In this dissertation, I studied the recovery dynamics and resilience of urban systems to disasters using a large-scale human-centered data-driven modeling approach, with particular emphasis on the complex interdependencies among social, economic, and infrastructure systems. First, statistical analysis of large-scale human mobility data collected from over 1 million mobile phone devices in five major disaster events across the globe, revealed universal population recovery processes across regions and disasters, including disproportionate disaster effects based on income inequalities and urban-rural divide. Second, human mobility data are used to infer the recovery of various socio-economic systems after disasters. Using Bayesian causal inference models, regional and business sectoral inequalities in disaster recovery are quantified. Finally, the analysis on social, economic, and physical recovery were integrated into a dynamical model of coupled urban systems, which captures the bi-directional interdependencies among socio-economic and physical infrastructure systems during disaster recovery. Using the model and data collected from Puerto Rico during Hurricane Maria, a trade-off relationship in urban development is revealed, where developed cities with robust centralized infrastructure systems have higher recovery efficiency of critical services, however, have socio-economic networks with lower self-reliance during crises, which lead to loss of community resilience. Managing and balancing the socio-economic self-reliance alongside physical infrastructure robustness is key to resilience. </div><div><br></div><div>The proposed models and results presented in this dissertation lay the scientific foundations of urban complexity and resilience, encouraging us to move towards dynamical and complex systems modeling approaches, from conventional static index-based resilience metrics. Big data-driven, dynamical complex systems modeling approaches enable quantitative understanding of the underlying disaster recovery process (e.g., interdependencies, feedbacks, cascading effects) across large spatial and temporal time scales. The approach is capable of proposing community-based policies for urban resilience via cross-regional comparisons and counterfactual scenario testing of various policy levers. </div>

<p>Inefficient traffic operations have far-reaching consequences in not just travel mobility but also public health, social equity, and economic prosperity. Congestion, a key symptom of inefficient operations, can lead to increased emissions, accidents, and productivity loss. Therefore, advancements and policies in transportation engineering require careful scrutiny to not only prevent unintended adverse consequences but also capitalize on opportunities for improvement. In spite of significant efforts to enhance traffic mobility and safety, human control of vehicles remains prone to errors such as inattention, impatience, and intoxication. Connected and autonomous vehicles (CAVs) are seen as a great opportunity to address human-related inefficiencies. This dissertation focuses on connectivity and automation and investigates the synergies between technologies. First, a deep reinforcement learning based strategy is proposed herein to enable agents to address the dynamic nature of inputs in traffic environments and to capture proximal and distant information, and to facilitate learning in rapidly changing traffic. The strategy is applied to alleviate congestion at highway bottlenecks by training a small number of CAVs to cooperatively reduce congestion through deep reinforcement learning. Secondly, to address congestion at intersections, the dissertation introduces a fog-based graphic RL (FG-RL) framework. This approach allows traffic signals across multiple intersections to form a cooperative coalition, sharing information for signal timing prescriptions. Large-scale traffic signal optimization is computationally inefficient, so the proposed FG-RL approach breaks down networks into smaller fog nodes that function as local centralization points within a decentralized system Doing so allows for a bottom-up solution approach for decomposing large traffic networks. Furthermore, the dissertation pioneers the notion of using a small CAV fleet, selected from any existing shared autonomous mobility services (SAMSs) to assist city road agencies to achieve string-stable driving in locally congested urban traffic. These vehicles are dispersed throughout the network to perform their primary function of providing ride-share services. However, when they encounter severe congestion, they act cooperatively with each other to be rerouted and to undertake traffic-stabilizing maneuvers to smoothen the traffic and reduce congestion. The smoothing behavior is learned through DRL, while the rerouting is facilitated through the proposed constrained entropy-based dynamic AV routing algorithm (CEDAR).</p>

<p>  </p> <p>The major concern about vehicle crashes has led to a great amount of research on the topic in the road safety area. Nevertheless, real-world crash data collection periods are often extensive and they result in a great delay in improving safety. Therefore, surrogate measures of safety, such as traffic conflicts, are considered for safety management.</p> <p>The definition of a traffic conflict has evolved over the course of half a century. One of the current definitions encompasses a failure-based road event that inevitably results in a crash if no evasive action is taken by involved road users. This counterfactual concept was validated with specific road events datasets, including rear-end events and vehicle-bicycle encounters. However, observing conflicts for an extended period is still a major difficulty. For example, a LIDAR-based technique applicable to intersections can collect conflict data for a relatively short period of several days. The LiDAR-collected data are then converted to the corresponding expected crash frequency during the observation period, which eventually must be expanded to the corresponding annual value. The conversion step has not been sufficiently addressed in the past research. Thus, an important task of estimating the annual expected crash frequency based on a short-term estimate remains unanswered. Addressing this need is the research objectives and contribution of this study.</p> <p>Advanced statistical methods allow developing models to estimate expected crash frequencies for annual and short periods. The ratio of such two estimates is defined as an expansion factor in this study. This thesis presents the modeling effort and its results for different types of crashes at signalized and unsignalized intersections in Indiana. Traditional and emerging data, such as traffic volume, speed, road characteristics, weather, and other features were collected and assembled at randomly selected 194 intersections. Then, they were used to estimate the logistic models of hourly crash probability. The models were then utilized to calculate expansion factors for a specific intersection.to evaluate the method.</p>

<p>  </p> <p>Most new vehicles manufactured in the last two years are connected vehicles (CV) that transmit back to the original equipment manufacturer at near real-time fidelity. These CVs generate billions of data points on an hourly basis, which can provide valuable data to agencies to improve the overall mobility experience for users. However, with this growing scale of CV big data, stakeholders need efficient and scalable methodologies that allow agencies to draw actionable insights from this large-scale data for daily operational use. This dissertation presents a suite of applications, illustrated through case studies, that use CV data for assessing and managing mobility and safety on surface transportation systems.</p> <p>A systematic review of construction zone CV data and crashes on Indiana’s interstates for the calendar year 2019, found a strong correlation between crashes and hard-braking event data reported by CVs. Trajectory-level CV data analyzed for a construction zone on interstate 70 provided valuable insights into travel time and traffic signal performance impacts on the surrounding road network. An 11-state analysis of electric and hybrid vehicle usage in proximity to public charging stations highlighted regions under and overserved by charging infrastructure, providing quantitative support for infrastructure investment allocations informed by real-world usage trends. CV data were further leveraged to document route choice behavior during active freeway incidents providing stakeholders with a historical record of observed routing patterns to inform future alternate route planning strategies. CV trajectory data analysis facilitated the identification of trip chaining activities resulting in improved outlier curation and realistic estimation of travel time metrics.</p> <p>The overall contribution of this thesis is developing analytical big data procedures to process billions of CV data records to inform engineering and public policy investments in infrastructure capacity, highway safety improvements, and new EV infrastructure. These scalable and efficient analysis techniques proposed in this dissertation will help agencies at the federal, state and local levels in addition to private sector stakeholders in assessing transportation system performance at-scale and enable informed data-driven decision making.</p>

Baigiamajame magistro darbe nagrinėjama Lietuvos geležinkelių transporto sektoriaus reforma, geležinkelių transporto sistemos reformai įtakos turintys veiksniai, reformos poreikis, tikslai, užsienio šalių geležinkelių transporto reformų patirtis. Įvardijama geležinkelių transporto sektoriaus reformos problematika. Nagrinėjami moksliniai straipsniai, kuriuose aptariama geležinkelių transporto reforma bei vežimų liberalizavimas, kita mokslinė literatūra, tyrimai bei studijos. Atlikti Lietuvos geležinkelių transporto sektoriaus reformos poreikio tyrimai, o tyrimo pagrindu įvardytos reformos pasekmės, pateiktos tyrimų išvados. Baigiamajame magistro darbe įvardijami galimi Lietuvos geležinkelių transporto sektoriaus valdymo modeliai ir šių modelių taikymo galimybės. Įvardijami Lietuvos Respublikos Vyriausybės programos nuostatai, susiję su geležinkelių transportu, nuostatų įgyvendinimas ir laukiami rezultatai. Išnagrinėjus teorinius ir praktinius Lietuvos geležinkelių transporto sektoriaus reformos ir vežimų liberalizavimo aspektus, įvardijamas Lietuvos geležinkelio sektoriui taikytinas valdymo modelis, pateikiamos baigiamojo darbo išvados ir siūlymai. / The subject of the Master Thesis is to study the reform of the Lithuanian railway transport sector, factors influented reformation processes, demand and aims of the reform, experience of other countries. The Thesis also describes problems the reform confronts with. The Master Thesis is a review of wide range of literature sources: scientific articles on the issues of railway transport’s reforms and liberalisation, other scientific sources, researches and studies. The Master Thesis also contains researche on the necessity of the reform, based on that certain conclusions have been made together with indications on the reform’s effect. In the Thesis there are presented different Lithuanian railway sectors’ management models and their feasibility. The are also describtion of provisions related to railway transport within Lithuania’s Governmental Programme, their implementation and effect expected. After reviewing theoretical and practical aspects of the railway transport sector’s reform and liberalisation there are indications on the most acceptable management model for Lithuanian railway sector, conclusions and proposals are being presented.

Šiame magistriniame darbe nagrinėjama gyvavimo ciklo metodika, kuri pritaikoma KU statomo Mokslinių tyrimo laivo korpuso suvirinimo metu išsiskiriančių emisijų skaičiavimui GaBi 6 programinės įrangos pagalba. Nagrinėjami du suvirinimo būdai, kurie buvo naudojami statant KU Mokslinių tyrimo laivą, t. y. lankinis suvirinimas po fliusu (SAW) ir lankinis suvirinimas lydžiuoju elektrodu apsauginėse dujose (MIG, MAG). / This master thesis examines the life cycle methodology that adjusts constructed KU research vessel shell weld calculation of emissions released from 6 GaBi software. Analyzed two welding techniques that have been used in the construction of KU research vessel - submerged arc welding (SAW) and arc welding electrode deposits for gas shielded (MIG, MAG).

M. Beniušis „Kelto „Victoria Seaways“ šilumokaičio ir aušinimo vamzdyno virpesių tyrimas“. Laivų projektavimo ir statybos magistratūros studijų programos baigiamasis darbas. Darbo vadovas dr. P. Mažeika, Klaipėdos universitetas: Klaipėda, 2014. Raktažodžiai: virpesiai, laivas, keltas, virpesių tyrimai, šilumokaitis. Baigiamojo darbo teorinėje dalyje aprašoma virpesių klasifikacija, pagrindiniai virpesių žadintojai ir analizuojami įvairūs virpesių lygio mažinimo laive, virpesių skaičiavimo būdai. Eksperimentinėje dalyje pateikiama keltų „Victoria Seaways“ ir „Athena Seaways“ aušinimo sistemos dalies virpesių matavimo metodika. Nagrinėjami reiso Klaipėda-Kylis-Klaipėda metu atliktų matavimų rezultatai, bei nustatomos tiriamos aušinimo sistemos dalies padidintų virpesių lygio priežastys. Paskutinėje darbo dalyje pateikiamos išvados ir rekomendacijos. / M. Beniušis “Vibration research of heat exchanger and cooling piping in Victoria Seaways ferry”. Final work of the master studies of ship design and building program. Academic supervisor Dr. P. Mažeika, Klaipeda University: Klaipėda, 2014. Keywords: vibrations, ship, ferry, vibration research, heat exchanger. The theoretical part of the final work describes the classification of vibration, main excitations of vibration and analyses various methods for reduction of the vibration level on board and vibration calculation. The experimental part presents the vibration measurement methodology in the cooling systems of Victoria Seaways and Athena Seaways ferries. It examines the results of measurements carried out during Klaipėda-Kiel-Klaipėda trip and identifies the reasons for the recent level of vibration in the analysed cooling system. The final part of the work contains the conclusions and recommendations.