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1
Auestad, Øyvind Fidje. "Heave Control System For A Surface Effect Ship : Disturbance Damping of Wave Induced Motion at Zero Vessel Speed." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for teknisk kybernetikk, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-16781.
Повний текст джерела
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Šerlinskis, Gediminas. "Projektuojamo laivo hidrodinaminių savybių reguliariose bangose tyrimas." Master's thesis, Lithuanian Academic Libraries Network (LABT), 2013. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2013~D_20130626_140102-49911.
Повний текст джерелаАнотація:
Darbe tiriamos galimybės vertinti laivo supimosi intensyvumą taikant klasikinės ir hidrodinaminės laivo supimosi skaičiavimo metodikas. Prognozavimo galimybių įvertinimui atliekamas laivo DTMB 5415 supimosi eksperimentas reguliariose bangose – matuojamas laivo bortinis, kilinis ir vertikalusis supimasis laivui stovint lagu bangoms ir esant išilginiam bangavimui. Pateikiama informacija apie supimosi eksperimento eigą, paruošimą, naudojamą laboratorinę įrangą ir bandymo rezultatų apdorojimą. Laivo supimosi skaičiavimai atliekami taikant hidrodinaminę skaičiojamosios skysčių dinamikos kompiuterinę programą „FLOW-3D“, klasikinę supimosi skaičiavimų metodiką ir kompiuterine programa „Seakeeper“ paremta hidrodinamine plokščiųjų skerspjūvių teorija. Gauti rezultatai palyginami su eksperimento rezultatais.<br>Paper analysis the most popular classical and hyrodinamical seakeeping methods for preliminary seakeeping performance prediction. Seakeeping test in regular waves has been performed for validation of seakeeping prediction methods for model DTMB 5415. Roll, pitch and heave motions have been measured for beam and head seas wave headings. The paper supplys Information about seakeeping test procees, preparation instructions for test, required laboratory equipment and seakeeping test data analysis. Computational fluid dynamics software „FLOW - 3D“ have been used for motion response prediction in regular waves, classical seakeeping theory method and strip theory based software Seakeeper. Computed results have been compared with seakeeping eksperimental data.
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Bailey, Helen Louise. "Effect of a nonlinear power take off on a wave energy converter." Thesis, University of Edinburgh, 2011. http://hdl.handle.net/1842/5741.
Повний текст джерелаАнотація:
This thesis is titled The influence of a nonlinear Power Take Off on a Wave Energy Converter. It looks at the effect that having a nonlinear Power Take Off (PTO) has on an inertial referenced, slack moored, point absorber, Wave Energy Converter (WEC). The generic device studied utilizes relative heave motion between an axi-symmetric cylinder and an internal mass, for the PTO to operate between. The PTO is the part of the WEC that transforms the relative motion into electricity. In this work, three different types of nonlinear PTO and a linear PTO are presented, tested, analysed and compared. The three nonlinear PTO types are: • A PTO that extracts energy in only one direction, either in relative compression or expansion. • A linear PTO and an additional endstop or peripheral PTO, that can only extract energy when the relative position of the internal mass has reached a pre-determined position. • A PTO that has damping forces that are quadratically proportional to the relative velocity. A numerical simulation has been built based upon a Runge-Kutta time series progression. The model uses the summation of the excitation force from the waves, the radiation force from the movement of the cylinder, the buoyancy force and the PTO forces. These combine to cause acceleration of the mass of the external cylinder, with an equal and opposite PTO force acting on the internal mass. The excitation force and added mass values are obtained from the boundary element method software, WAMIT. Prony’s method is used to obtain an approximate radiation force, based upon the radiation time force history. This numerical model operates on both a 1:40 scale and a full sized model. The numerical model finds the optimal PTO parameters, for different PTO setups, in irregular sea states. This optimum is based on the power extracted as well as indications of the reliability and lifetime of the system. The numerical simulation presents results showing how the nonlinearity of the PTO influences the motions of the WEC, resulting in dissimilarities between the Response Amplitude Operator (RAO) results, obtained from regular seas, and the Linear Transfer Function (LTF), found from irregular sea testing. The experimental model has been tested in the Curved Wave Tank facility at the University of Edinburgh, with a 1:40 scaled model. It used a central rod both as a support structure and to limit the movement of the cylinder and internal mass to heave. Between the cylinder and internal mass a spring and pneumatic damper operate in parallel, in various setups. It was tested in regular and irregular sea states and the position of the internal mass and cylinder was monitored. The experimental model was tested to ascertain the time series motions, RAO, LTF, the relative phase between the bodies and the power extracted for different wave climates. The numerical and experimental work were compared to allow confidence in both models. They showed relatively good agreement for the RAOs, LTFs and predictions of the relative phase but there was discrepancies in the predicted power for both regular and irregular seas. This difference is due to the difficulties in obtaining the relative velocities in the experimental model, resulting in a significant error in power prediction, since the power is proportional to the square of the relative velocities. The conclusions show that having a mono-directional PTO as opposed to a bi-directional PTO results in an approximately equal or greater power extraction in a variety of different sea states. An additional endstop or peripheral damper can increase the total power that a WEC extracts, in some situations, and may be advantageous depending upon the other potential benefits it brings to the WEC.
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Zhen, Yi. "Numerical Simulation of Dropped Cylindrical Objects into Water in Two Dimensions (2D)." ScholarWorks@UNO, 2018. https://scholarworks.uno.edu/td/2568.
Повний текст джерелаАнотація:
The dropped objects are identified as one of the top ten causes of fatalities and serious injuries in the oil and gas industry. It is of importance to understand dynamics of dropped objects under water in order to accurately predict the motion of dropped objects and protect the underwater structures and facilities from being damaged. In this thesis, we study nondimensionalization of dynamic equations of dropped cylindrical objects. Nondimensionalization helps to reduce the number of free parameters, identify the relative size of effects of parameters, and gain a deeper insight of the essential nature of dynamics of dropped cylindrical objects under water. The resulting simulations of dimensionless trajectory confirms that drop angle, trailing edge and drag coefficient have the significant effects on dynamics of trajectories and landing location of dropped cylindrical objects under water.
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Dias, Thiago. "Análise da instabilidade paramétrica de risers retos via modelo de ordem reduzida baseado em modo não linear com função do tipo Bessel." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/3/3144/tde-21072016-110358/.
Повний текст джерелаАнотація:
Recentes descobertas de campos de petróleo e gás, a centenas de quilômetros da costa Sudeste do Brasil, em lâmina d\'água acima de 2.000m, demandam avanços científicos e tecnológicos para sua exploração segura. Entre os desafios para os engenheiros, a análise dinâmica de risers offshore é de extrema relevância devido à propensão à fadiga do material estrutural. Os movimentos de unidades flutuantes, que ocorrem devido às ondas de gravidade, impõem um tipo particular de carregamento dinâmico para os risers. Por uma questão de simplicidade, apenas o movimento de heave é considerado, embora pitch and roll também possam desempenhar um papel relevante na análise. De fato, o efeito de heave provoca a modulação de tensãoamplitude ao longo da estrutura tubular e flexível, o que pode conduzir à ressonância paramétrica como consequência da conhecida instabilidade de Mathieu. O riser vertical será o foco desse trabalho. A teoria bidimensional de vigas de Bernoulli-Euler é utilizada para se obter uma equação diferencial não linear de movimento para o riser submetido a uma carga axial e peso submerso. Modelos matemáticos - conhecidos como modelos de ordem reduzida (MORs) - com poucos graus de liberdade são adotados, mas com capacidade adequada para representar a resposta estrutural tanto qualitativa como quantitativamente. Utilizando os modos não lineares como funções de projeção no procedimento de Galerkin não linear, a interpretação física vem da igualdade dos trabalhos virtuais tanto no modelo de alta hierarquia quanto do MOR, com a consequente introdução de vínculos rígidos nos modos excluídos da análise. Aqui, a relação não linear entre as amplitudes modais e modos de vibração/frequências são levados em conta. Os resultados obtidos estão de acordo com os resultados dos testes experimentais de um modelo em escala reduzida realizado sob coordenação do LIFE&MO (Laboratório de Interação Fluido-Estrutura e Mecânica Offshore), fornecendo uma calibração do coeficiente de arrasto equivalente, para se levar em conta o sistema dissipativo que inclui tanto o amortecimento hidrodinâmico e estrutural. As respostas também são comparadas com as obtidas através do estudo de um modelo de elementos finitos, elaborado com o auxílio de um software comercial, o OrcaFlex®, e com funções clássicas de projecção, em particular, a função trigonométrica. Em seguida, variando-se os parâmetros de controle, as respostas do estado estacionário pós-crítica são mapeadas e plotadas em um diagrama policromático.<br>Recent discoveries of oil and gas fields, hundreds of kilometers off the Southeast coast of Brazil, in water depths above 2,000m, demand scientific and technological advances to support their safe exploitation. Among the challenges posed to engineers, the dynamic analysis of offshore risers is of utmost relevance, due to fatigue of the structural material. The motions of floating units, which occur due to gravity waves, impose a particular type of dynamic loading to the risers. As a matter of simplicity, only heave is considered herewith, although pitch and roll can also play a relevant role in the analysis. In fact, the effect of heave causes tension-amplitude modulation to the long and flexible tubular structure, which may drive parametric resonance as a consequence of the well-known Mathieus instability. The vertical riser will be the focus of this work. Bernoulli-Euler two-dimensional beam theory is used to obtain a nonlinear differential equation of motion for the riser subjected to an axial thrust and submerged weight. Mathematical models known as reduced-order models (ROMs) with few degrees of freedom are used, but with adequate capacity to represent the structural response both qualitatively and quantitatively. Using non-linear modes as projection functions within the non-linear Galerkins procedure, the physical interpretation of which being the identification of virtual works in both the high-hierarchy model and the ROM, with consequent introduction of rigid constraints in the modes excluded from the analysis. Here the non-linear relationship between modal amplitudes and mode shapes/frequencies are taken into account. The results obtained here agree well with those of experimental tests with a small-scale model carried out under coordination LIFE&MO (Laboratory of Fluid-Structure Interaction & Offshore Mechanics), provided calibration of the equivalent drag coefficient is carried out, to account for the overall system dissipation including both hydrodynamic and structural damping. The responses are also compared with those given by finite element models studied with the help of commercial software, the OrcaFlex® and with classical projection functions, in particular the trigonometric function. Then varying the control parameters, the responses of post-critical steady state are mapped and plotted in diagram polychromatic.
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Oliveira, Rui. "Motion Planning for Heavy-Duty Vehicles." Licentiate thesis, KTH, Reglerteknik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-252537.
Повний текст джерелаАнотація:
Autonomous driving is a disrupting technology that is expected to reshape transportation systems. The benefits of autonomous vehicles include, but are not limited to, safer transportation, increased economic growth, and broader access to mobility services. Industry and academia are currently researching a variety of topics related to autonomous driving, however, the focus seems to be on passenger vehicles. As a consequence, heavy-duty vehicles, which are a significant share of transportation systems, are overlooked, and the challenges associated with these vehicles are neglected. This thesis studies motion planning algorithms for heavy-duty vehicles. Motion planning is a fundamental part of autonomous vehicles, it is tasked with finding the correct sequence of actions that take the vehicle towards its goal. This work focuses on particular aspects that distinguish heavy-duty vehicles from passenger vehicles, and that call for novel developments within motion planning algorithms. We start by addressing the problem of finding shortest paths for a vehicle in obstacle-free environments. This problem has been studied since the fifties, but the addressed vehicle models are often simplistic. We propose a novel algorithm that is able to plan paths respecting complex vehicle actuator constraints associated with the slow dynamics of heavy vehicles. Using the previous method, we tackle the motion planning problem in environments populated with obstacles. Lattice-based motion planners, a popular choice for this type of scenario, come with drawbacks related to the sub-optimality of solution paths, and the discretization of the goal state. We propose a novel path optimization method, which is able to significantly reduce both problems. The resulting optimized paths contain less oscillatory behavior and arrive precisely at arbitrary non-discretized goal states. We then study the problem of bus driving in urban environments. It is shown how this type of driving is fundamentally different than that of other vehicles, due to the chassis configuration with large overhangs. To successfully maneuver buses, distinct driving objectives need to be used in planning algorithms. Moreover, a novel environment classification scheme must be introduced. The result is a motion planning algorithm that is able to mimic professional bus driver behavior, resulting in safer driving and increased vehicle maneuverability.<br><p>QC 20190603</p>
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Ushijima, Tatsuo. "The motion of heavy particles in turbulent flows." Thesis, University of Cambridge, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.625078.
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Oliveira, Rui. "Planning and Motion Control in Autonomous Heavy-Duty Vehicles." Thesis, KTH, Reglerteknik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-151022.
Повний текст джерелаАнотація:
Autonomous driving has been an important topic of research in recent years. In this thesis we study its application to Heavy Duty Vehicles, more specically, vehicles consisting of a truck and a trailer. An overview study is done on three fundamental steps of an autonomous driving system, planning, trajectory tracking and obstacle avoidance. In the planning part, we use RRT, and two other variants of the algorithm to nd trajectories in an unstructured environment, e.g., a mining site. A novel path optimization post-processing technique well suited for use with RRT solutions was also developed. For the trajectory tracking task several well-known controllers were tested, and their performance compared. An extension is proposed to one of the controllers in order to take into account the trailer. The performance evaluation was done on scaled truck systems in the Smart Mobility Lab at KTH. The obstacle avoidance is done with the aid of a simple, yet functional Model Predictive Controller. For this purpose, we developed dierent formulations of the optimization problem, corresponding to distinct optimization goals and vehicle models, in order to assess both the quality of the MPC, and of the assumed truck model. The outcome of this thesis is a fully autonomous system, able to plan and move in constrained environments, while avoiding unpredicted obstacles. It was implemented using a 1:32 scale remote controlled truck, commanded by a desktop computer.
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Kwon, Hyun Jung. "Simulating ingress and egress motion for heavy earthmoving machines." Diss., University of Iowa, 2011. https://ir.uiowa.edu/etd/2734.
Повний текст джерелаАнотація:
Design of heavy earthmoving equipment is based primarily on feedback from drivers. Most design studies on ingress and egress focus on the motion itself and rely heavily on experimental data. This process requires physical construction of expensive (in terms of time and money) mockups before any feedback can be obtained. Post-feedback design changes and the analysis of those changes are again expensive processes. Although the design of heavy vehicles requires consideration of human safety and comfort, very little attention has been given to simulating ingress and egress movement for these vehicles. This thesis describes the development of a virtual model to perform ingress and egress motions for heavy equipment and its applications to study the responses of operators with different anthropometries to different cab designs. Different performance measures are suggested and used with predictive dynamics to study human performance since human motion is not governed by a single performance measure. Optimizing multiple performance measures allows the full range of motion for all 55 degrees of freedom to be considered for simulating the task. Once the relevant performance measure was established, case studies were performed on seven different cab designs and digital human models with three different anthropometries. Finally, several different cab design metrics for propensity of injury, comfort, and accessibility were proposed. These design metrics were evaluated for each of the case studies. Finally, each cab design was ranked based on the design metrics to identify the best design for a range of anthropometries. These results help designers make decisions and plan further design changes.
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Evestedt, Niclas. "Sampling Based Motion Planning for Heavy Duty Autonomous Vehicles." Licentiate thesis, Linköpings universitet, Reglerteknik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-132769.
Повний текст джерелаАнотація:
The automotive industry is undergoing a revolution where the more traditional mechanical values are replaced by an ever increasing number of Advanced Driver Assistance Systems (ADAS) where advanced algorithms and software development are taking a bigger role. Increased safety, reduced emissions and the possibility of completely new business models are driving the development and most automotive companies have started projects that aim towards fully autonomous vehicles. For industrial applications that provide a closed environment, such as mining facilities, harbors, agriculture and airports, full implementation of the technology is already available with increased productivity, reliability and reduced wear on equipment as a result. However, it also gives the opportunity to create a safer working environment when human drivers can be removed from dangerous working conditions. Regardless of the application an important part of any mobile autonomous system is the motion planning layer. In this thesis sampling-based motion planning algorithms are used to solve several non-holonomic and kinodynamic planning problems for car-like robotic vehicles in different application areas that all present different challenges. First we present an extension to the probabilistic sampling-based Closed-Loop Rapidly exploring Random Tree (CL-RRT) framework that significantly increases the probability of drawing a valid sample for platforms with second order differential constraints. When a tree extension is found infeasible a new acceleration profile that tries to brings the vehicle to a full stop before the collision occurs is calculated. A resimulation of the tree extension with the new acceleration profile is then performed. The framework is tested on a heavy-duty Scania G480 mining truck in a simple constructed scenario. Furthermore, we present two different driver assistance systems for the complicated task of reversing with a truck with a dolly-steered trailer. The first is a manual system where the user can easily construct a kinematically feasible path through a graphical user interface. The second is a fully automatic planner, based on the CL-RRT algorithm where only a start and goal position need to be provided. For both approaches, the internal angles of the trailer configuration are stabilized using a Linear Quadratic (LQ) controller and path following is achieved through a pure-pursuit control law. The systems are demonstrated on a small-scale test vehicle with good results. Finally, we look at the planning problem for an autonomous vehicle in an urban setting with dense traffic for two different time-critical maneuvers, namely, intersection merging and highway merging. In these situations, a social interplay between drivers is often necessary in order to perform a safe merge. To model this interaction a prediction engine is developed and used to predict the future evolution of the complete traffic scene given our own intended trajectory. Real-time capabilities are demonstrated through a series of simulations with varying traffic densities. It is shown, in simulation, that the proposed method is capable of safe merging in much denser traffic compared to a base-line method where a constant velocity model is used for predictions.
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Bassler, Christopher Colby. "Analysis and Modeling of Hydrodynamic Components for Ship Roll Motion in Heavy Weather." Diss., Virginia Tech, 2013. http://hdl.handle.net/10919/23258.
Повний текст джерелаАнотація:
Ship roll motion has been the subject of many studies, because of the complexities associated with this mode of ship motion, and its impact on operability, safety, and survivability. Estimation and prediction of the energy transfer and dissipation of the hydrodynamic components, added inertia and damping, is essential to accurately describe the roll motions of a ship. This is especially true for ship operations in moderate to extreme sea conditions. In these conditions, a complex process of energy transfer occurs, which alters the physical behavior of the hydrodynamic components, and ultimately affects the amplitude of ship roll motion. <br />Bilge keels have been used on ships for nearly two centuries, to increase damping and reduce the severity of roll motions experienced by a ship in waves. Because ship motions are more severe in extreme sea conditions, large roll angles may occur. With the possibility of crew injury, cargo damage, or even capsize, it is important to understand the behavior of the roll added inertia and damping for these conditions. Dead ship conditions, where ships may experience excitation from beam, or near beam, seas present a worst case scenario in heavy weather. The behavior of a ship in this condition should be considered in both the design and assessment of seakeeping performance. <br />In this study, hydrodynamic component models of roll added inertia and roll damping were examined and assessed to be unsuitable for accurate prediction of ship motions in heavy weather. A series of model experiments and numerical studies were carried out and analyzed to provide improved understanding of the essential physical phenomena which affect the hydrodynamic components and occur during large amplitude roll motion. These observations served to confirm the hypothesis that the existing models for roll added inertia and damping in large amplitude motions are not sufficient. The change in added inertia and damping behavior for large roll motion is largely due to the effects of hull form geometry, including the bilge keels and topside geometry, and their interactions with the free surface. Therefore, the changes in added inertia and damping must be considered in models to describe and predict roll motions in severe wave environments. <br />Based on the observations and analysis from both experimental and numerical methods, several time-domain model formulations were proposed and examined to model hydrodynamic components of large amplitude roll motions. These time-domain formulations included an analytical model with memory effects, a piecewise formulation, and several possibilities for a bilge keel force model. Although a piecewise model for roll damping was proposed, which can improve the applicability of traditional formulations for roll damping to heavy weather conditions, a further attempt was undertaken to develop a more detailed model specifically for the bilge keel force. This model was based on the consideration of large amplitude effects on the hydrodynamic components of the bilge keel force. Both the piecewise and bilge keel force models have the possibility to enable improved accuracy of potential flow-based numerical prediction of ship roll motion in heavy weather. However, additional development remains to address issues for further practical implementation.<br>Ph. D.
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Xu, Jinsong. "Identification of ship coupled heave and pitch motions using neural networks." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp04/mq25902.pdf.
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Kollberg, Christian. "Radar-Based Two-Dimensional Ego-Motion Estimation for Heavy Duty Vehicles." Thesis, KTH, Skolan för elektro- och systemteknik (EES), 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-192378.
Повний текст джерелаАнотація:
The development of Advanced Driver Assistance Systems (ADASs) has during recent years paved the way for important improvements within the industry of long haulage driving. Never have heavy duty vehicles been that safe and efficient as they are today and one may argue that high-level competition among manufacturers and strongly regulated legislations are the major underlying causes of contribution. Further on, driver support is currently taking further steps towards autonomous driving which makes vehicle ego-motion estimation a more crucial task to deal with. Novel estimation techniques should guarantee robustness, precision and redundancy to further increase the level of performance in tomorrow’s driver support systems. This thesis presents a multi-sensor approach for two-dimensional ego-motion estimation based on a sensor set-up comprised by the above-ground type sensors Doppler radar and accelerometer along with the conventional inductive wheel encoder and yaw-rate sensor. A decentralized Kalman filter architecture with radar-based fusion state feedback and incorporated outlier detection has been implemented to gain robust long-term accuracy. Estimation of instantaneous longitudinal speed and yaw-rate are delivered by system, developed to suit a modern Scania produced heavy duty vehicle with standard specifications. The Proposed ego-motion estimation system has been, in estimation of longitudinal speed, shown to perform better than currently employed system. The proposed system is, based on tests in estimation of longitudinal speed on highway, shown capable to reduce Maximum Absolute Error (MAE) and Root Mean Square Error (RMSE) with up to 27 % and 45 %, respectively. Further on, increased sensitivity at low-speed start-stop driving has been achieved.<br>Tillverkningsindustrin för tunga fordon har på senare år tagit stora steg framåt i utvecklingen av avancerade förarassistansfunktioner. Dagens system möjliggör effektivare transportlösningar som är både säkrare och mer miljövänliga än någonsin tidigare. Tänkbara orsaker till grund för denna utveckling är hårt åtstramade lagkrav, tuff konkurrens samt ett allt tydligare fokus på automatisering. För att i framtiden nå fulländad autonomi spås krav på högre precision och robusthet samt en utvecklad funktionalitet i framtida fordonssystem. Som ett led i denna utvecklingsprocess har estimering av fordonsdynamik i form av hastighetsskattning fått en alltmer betydande roll som indata för flertalet essentiella fordonssystem. Utfört arbete har genererat ett nytt hastighetsskattningssystem för tunga fordon. Med, för sammanhanget nya givare såsom accelerometer och dopplerradar samt de mer konventionella givartyperna, hjulsensor och rotationsgivare, estimeras hastighet i två dimensioner. Longitudinell hastighet och rotationshastighet kring fordonets vertikala axel. Föreslaget system utgörs av en decentraliserad och kalmanfilterbaserad arkitektur med radarfusionerad återkoppling och inbyggd feldetektion i syfte passa dagens tunga fordon tillverkade av Scania. Det visar sig att föreslaget system är kapabelt till konkurrenskraftig hastighetsskattning, varvid longitudinell hastighet skattas med bäst resultat. Test av motorvägskörning i tät traffik visar att maximalt absolutfel och kvadratiskt medelvärdesfel kan reduceras med upp till 27 % respektive 45 % mätt relativt dagens metodik. Vidare, signifikanta prestandaförbättringar har påvisats vid test av start- och stoppdetektion under låghastighetstester.
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Pandit, Yadav. "AZIMUTHAL ANISOTROPY IN HEAVY ION COLLISIONS." Kent State University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=kent1353871180.
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Alwakiel, Heba Naguib. "Leveraging Weigh-In-Motion (WIM) Data to Estimate Link-Based Heavy-Duty Vehicle Emissions." PDXScholar, 2011. https://pdxscholar.library.pdx.edu/open_access_etds/247.
Повний текст джерелаАнотація:
This research examines the use of archived weigh-in-motion (WIM) data to estimate link-based heavy-vehicle emissions for Oregon highways. This research combined data on vehicle speed, highway grade, and gross vehicle weight and relationship between these elements in published research to estimate the carbon dioxide (CO2) and nitrogen oxide (NOx) emissions from trucks. Sensitivity analysis was conducted on the impact of uphill grade and gross vehicle weight on truck speed and emissions. The results suggest that with the data available in the weigh-in-motion archive and with a reasonable set of assumptions, link-based emissions for heavy-duty vehicles can be estimated. The carbon dioxide (CO2) and nitrogen oxide (NOx) emissions are found to increase when the speed, gross vehicle weight, or road grade increases. The relationship between nitrogen oxide (NOx) emissions and vehicle weight was estimated to be linear. The potential to estimate the link-based heavy-vehicle emissions for Oregon highways using the weigh-in-motion data archive, which was mainly designed to estimate truck counts, has a great value in setting new measures to mitigate the heavy-vehicle emissions.
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Grambo, Laura B. "Heavy elastic vs. white tape : the effect of ankle taping on ankle range of motion /." Online version, 2010. http://content.wwu.edu/cdm4/item_viewer.php?CISOROOT=/theses&CISOPTR=340&CISOBOX=1&REC=5.
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Lindesvik, Warma Simon. "Reinforcement Learning of Repetitive Tasks for Autonomous Heavy-Duty Vehicles." Thesis, Uppsala universitet, Avdelningen för systemteknik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-426123.
Повний текст джерелаАнотація:
Many industrial applications of heavy-duty autonomous vehicles include repetitive manoeuvres, such as, vehicle parking, hub-to-hub transportation etc. This thesis explores the possibility to use the information from previous executions, via reinforcement learning, of specific manoeuvres to improve the performance for future iterations. The manoeuvres are; one straight line path, and one constantly curved path. A proportional-integrative control strategy is designed to control the vehicle and the controller is updated, between each iteration, using a policy gradient method. A rejection sampling procedure is introduced to impose the stability of the control system. This is necessary since the general reinforcement learning framework and policy gradient framework do not consider stability. The performance of the rejection sampling procedure is improved using the ideas of simulated annealing. The performance improvement of the vehicle is evaluated through simulations. Linear and nonlinear vehicle models are evaluated on a straight line path and a constantly curved path. The simulations show that the vehicle improves its ability to track the reference path for all evaluation models and scenarios. Finally, the simulations also show that the controlled system is kept stable throughout the learning process.<br>Autonoma fordon är en viktig pusselbit i framtidens transportlösningar och industriella miljöer, både klimat- och säkerhetsmässigt. Många manövrar industriella fordon utför är repetetiva, exempelvis parkering. Det här arbetet utforskar möjligheten att lära sig av tidigare försök av manövern för att förbättra fordonets förmåga att utföra den. En proportionelig-integrerande reglerstruktur används för att styra fordonet. Reglerstrukturen är en tillståndsåterkoppling där regulatorn består av två proportionelig-integrerende regulatorer. Reglersystemet är initialiserat stabilt och fordonet låts utföra en iteration av manövern. Regulatorn updateras mellan varje iteration av manövern med hjälp av förstärkningsinlärning. Förstärkningslärning innebär att man använder informationen från tidigare försök av manövern för att förbättra fordonets förmåga att följa referensbanan. Förstärkningslärningen ger alltså instruktioner om hur regulatorn ska uppdateras baserat på hur fordonet presterade under förra iterationen. En samplings procedur implementeras för att försäkra stabiliteten av reglersystemet eftersom förstärkningslärandet inte tar hänsyn till detta. Syftet med samplings proceduren är också att minimera de negativa effekterna på lärningsprocessen. Algoritmen är analyserad genom att simulera fordonet med hjälp av både linjära- och olinjära utvärderingsmodeller på två olika scenarion; en rak bana och en bana med konstant kurvatur. Simuleringarna visar att fordonet förbättrar sin förmåga att följa referensbanorna för alla utvärderingsmodeller av fordonet. Simuleringarna visar också att reglersystemet hålls stabilt under lärningsprocessen.
18
Patterson, James J. "Effect of Conicity and Ply Steer on Long Combination Vehicle Yaw Plane Motion." University of Akron / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=akron1310573055.
Повний текст джерела
19
Henning, H. L. "A numerical investigation into the heave, sway and roll motions of typical ship like hull sections using RANS numerical methods." Thesis, Stellenbosch : Stellenbosch University, 2011. http://hdl.handle.net/10019.1/18033.
Повний текст джерелаАнотація:
Thesis (MScEng)--Stellenbosch University, 2011.<br>ENGLISH ABSTRACT: The hydrodynamic characteristics of three typical ship-like hull sections, in
different motions, are numerically investigated using FLUENT, 2009. These
simple shapes, namely a v-bottom (triangle) hull, a at-bottom (square) hull
and a round-bottom (semi-circle) hull, are investigated in uncoupled heave,
sway and roll. The problem is described in two dimensions. A combination of
numerical methods and models, found in literature, are used to conduct this
investigation. Hull characterisation is achieved through the use of hull mass
and damping coe cients. These numerically determined coe cients are compared
to experimental work conducted by Vugts (1968). A good correlation
between the numerical and experimental results exists for the heave and sway
cases. By normalising the coe cients, different hulls are comparable to one
another. The numerical models used are validated and veri ed. Roll motion
remains largely unsolved for very large angles of roll (in excess of 11°). Different
uid ow phenomena occurring around the hull sections have varying
degrees of in uence on the motions of a hull. It is found that not one of the
turbulence models investigated can be employed to globally solve each type
of hull-motion case. Also, forced oscillations in computational simulations require
considerably more computational time than free-decay oscillating hull
simulations.<br>AFRIKAANSE OPSOMMING: Die hidrodinamiese karakteristieke van verskillende skeepsrompvorms, in verskeie
bewegingswieë, is numeries ondersoek met behulp van FLUENT, 2009.
Drie eenvoudige vorms ('n v-bodem (driehoek), plat-bodem (reghoek) en rondebodem
(semi-sirkel) romp) is onderskeidelik ondersoek in opwieg, dwarswieg en
rol. Die probleem is twee-dimensioneel. Daar is gebruik gemaak van 'n kombinasie
van numeriese metodes en modelle, uit die literatuur, om die ondersoek
uit te voer. Die rompe is gekarakteriseer met behulp van massa- en dempingskoëffi siënte. Hierdie numeries bepaalde koë ffisiënte is vergelyk met die
eksperimentele werk van Vugts (1968). Daar bestaan 'n goeie korrelasie tussen
die numeriese en eksperimentele resultate vir die opwieg en dwarswieg gevalle.
Die koë ffisiënte is genormaliseer om die verskeie rompvorms te vergelyk. Die
numeriese modelle is geverifi eer en valideer. Rolbewegings is onopgelos vir
groot rolhoeke (groter as 11°). Die mate waartoe die romp se beweging beïnvloed
word deur die verskillende vloei verskynsels wat om die rompe ontstaan,
verskil. Daar is bevind dat geen van die turbulensie modelle gebruik kan word
om alle skeepsbeweging-gevalle op te los nie. Gedwonge-ossilasie numeriese
simulasies benodig meer berekeningstyd as vrye-verval ossilasie gevalle.
20
Rybin, Steven M. "The Historical Thought of Film: Terrence Malick and Philosophical Cinema." View abstract, 2009. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:3375107.
Повний текст джерела
21
Törnroth, Oscar, and Truls Nyberg. "Design and Implementation of a Strategy for Path Tracking on Autonomous Heavy-Duty Vehicles." Thesis, Linköpings universitet, Fordonssystem, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-149266.
Повний текст джерелаАнотація:
In this thesis, a combined feedforward and feedback controller for improved path tracking on autonomous heavy-duty vehicles is designed and implemented. The steering wheel is controlled in order to follow a reference curvature, computed by a higher-level MPC, responsible for minimizing the distance to a planned path. The steering dynamics, from steering wheel via wheel angles, to a measurable vehicle curvature, is modeled, and a conversion from desired curvature gain to input angle to the steering wheel is derived. Tests with an autonomous Scania R580 show that the desired curvature can be followed with satisfactory small error, both in a designed slalom path and on a more generic test track. By utilizing future curvature values computed by the MPC, a non-causal feedforward controller can reduce the delay from input to the steering wheel to a measured response in curvature, by almost two thirds, compared to the currently implemented solution. Compared to an open-loop control design, tests in simulation show that a feedback controller can reduce errors in curvature gain. However, with the identified steering dynamics and the improved conversion from steering wheel angle to curvature, no further improvement in the curvature gain was seen when implementing the feedback controller in the test vehicle. Care must also be taken not to introduce instability in the system when the feedback controller is implemented in series with a high-level MPC.<br>Den här rapporten beskriver design och implementering av en regulator med kombinerad framkoppling och återkoppling för förbättrad banföljning av autonoma tunga fordon. Fordonets ratt styrs för att följa en kurvaturreferens beräknad av en överordnad MPC, ansvarig för att minimera avståndet till en planerad bana. Dynamiken i styrningen, från ratten via hjulvinklarna till en mätbar kurvatur för fordonet, är modellerad. En översättning från önskad förstärkning av kurvatur till insignal för rattvinkeln är också framtagen. Tester utförda med en autonom Scania R580 visar att den önskade kurvaturen kan följas med tillfredsställande litet fel, både i en egendesignad slalombana och i en mer generisk testbana. Genom att utnyttja framtida referensvärden för kurvatur beräknade av MPC:n, kan en icke-kausal framkopplande regulator minska fördröjningen från insignal till ratten till en mätbar respons i fordonets kurvatur. Jämfört med den nuvarande lösningen minskas fördröjningen med nästan två tredjedelar. Jämfört med en öppen styrning visar tester i simulering att en återkoppling i regulatorn kan minska stationära fel i kurvatur. Med implementeringen av den identifierade styrdynamiken och den förbättrade översättningen från rattvinkel till kurvatur, syntes dock med återkoppling ingen ytterliggare förbättring i testfordonet. Implementering av den återkopplande regulatorn i serie med den överordnade MPC:n behöver också göras med omsorg för att inte introducera instabilitet i systemet.
22
Pesee, Chatchai. "Stochastic modelling of financial processes with memory and semi-heavy tails." Thesis, Queensland University of Technology, 2005. https://eprints.qut.edu.au/16057/2/Chatchai%20Pesee%20Thesis.pdf.
Повний текст джерелаАнотація:
This PhD thesis aims to study financial processes which have semi-heavy-tailed marginal distributions and may exhibit memory. The traditional Black-Scholes model is expanded to incorporate memory via an integral operator, resulting in a class of market models which still preserve the completeness and arbitragefree conditions needed for replication of contingent claims. This approach is used to estimate the implied volatility of the resulting model. The first part of the thesis investigates the semi-heavy-tailed behaviour of financial processes. We treat these processes as continuous-time random walks characterised by a transition probability density governed by a fractional Riesz- Bessel equation. This equation extends the Feller fractional heat equation which generates a-stable processes. These latter processes have heavy tails, while those processes generated by the fractional Riesz-Bessel equation have semi-heavy tails, which are more suitable to model financial data. We propose a quasi-likelihood method to estimate the parameters of the fractional Riesz- Bessel equation based on the empirical characteristic function. The second part considers a dynamic model of complete financial markets in which the prices of European calls and puts are given by the Black-Scholes formula. The model has memory and can distinguish between historical volatility and implied volatility. A new method is then provided to estimate the implied volatility from the model. The third part of the thesis considers the problem of classification of financial markets using high-frequency data. The classification is based on the measure representation of high-frequency data, which is then modelled as a recurrent iterated function system. The new methodology developed is applied to some stock prices, stock indices, foreign exchange rates and other financial time series of some major markets. In particular, the models and techniques are used to analyse the SET index, the SET50 index and the MAI index of the Stock Exchange of Thailand.
23
Pesee, Chatchai. "Stochastic Modelling of Financial Processes with Memory and Semi-Heavy Tails." Queensland University of Technology, 2005. http://eprints.qut.edu.au/16057/.
Повний текст джерелаАнотація:
This PhD thesis aims to study financial processes which have semi-heavy-tailed marginal distributions and may exhibit memory. The traditional Black-Scholes model is expanded to incorporate memory via an integral operator, resulting in a class of market models which still preserve the completeness and arbitragefree conditions needed for replication of contingent claims. This approach is used to estimate the implied volatility of the resulting model. The first part of the thesis investigates the semi-heavy-tailed behaviour of financial processes. We treat these processes as continuous-time random walks characterised by a transition probability density governed by a fractional Riesz- Bessel equation. This equation extends the Feller fractional heat equation which generates a-stable processes. These latter processes have heavy tails, while those processes generated by the fractional Riesz-Bessel equation have semi-heavy tails, which are more suitable to model financial data. We propose a quasi-likelihood method to estimate the parameters of the fractional Riesz- Bessel equation based on the empirical characteristic function. The second part considers a dynamic model of complete financial markets in which the prices of European calls and puts are given by the Black-Scholes formula. The model has memory and can distinguish between historical volatility and implied volatility. A new method is then provided to estimate the implied volatility from the model. The third part of the thesis considers the problem of classification of financial markets using high-frequency data. The classification is based on the measure representation of high-frequency data, which is then modelled as a recurrent iterated function system. The new methodology developed is applied to some stock prices, stock indices, foreign exchange rates and other financial time series of some major markets. In particular, the models and techniques are used to analyse the SET index, the SET50 index and the MAI index of the Stock Exchange of Thailand.
24
Gulyuk, Vasyl, and Василь Ярославович Гулюк. "Evaluation of the inertia of the change in the speed of rotation of the lifting rotors on the dynamics of the motion of a heavy quadrocopter." Thesis, National Aviation University, 2021. https://er.nau.edu.ua/handle/NAU/50743.
Повний текст джерелаАнотація:
1. Rogozhin V.A., Sineglazov V.M., Filyashkin N.. Automated aircraft control systems: K .: NAU, 2003, - 502 p.
2. Geng K., Chulin N. A. Stabilization algorithms for automatic control of the trajectory motion of a quadcopter. // Electronic journal «Science and education». Proceedings of MSTU. - 2015- № 83, pp. 218–235.<br>Unlike a helicopter, which uses a swashplate for control, which changes direction of the lifting rotor thrust, and the total pitch and adequately the magnitude of the rotor thrust, in the quadcopter (QC) the thrust direction relative to the body and the pitch of the rotor blades are unchanged. To change the flight trajectory or angular orientation of the quadcopter, the rotation speed and, accordingly, the magnitudes of the thrust of all four rotors change in a certain way. Thus, the control of QC is reduced to the control of the rotor rotation speed, which greatly simplifies the design of the control system.<br>На відміну від вертольота, який використовує для керування стрілку, яка змінює напрямок тяги підйомного ротора, а також загальний крок і адекватно величину тяги ротора, у квадрокоптері (КК) напрям тяги щодо корпусу та крок лопаті ротора незмінені. Для зміни траєкторії польоту або кутової орієнтації квадрокоптера певним чином змінюються швидкість обертання і, відповідно, величини тяги всіх чотирьох роторів. Таким чином, керування контролем якості зводиться до контролю швидкості обертання ротора, що значно спрощує конструкцію системи керування. При аналізі динаміки керованого руху мініатюрного КК зазвичай ігнорується зміна швидкості обертання ротора.
25
Måhl, Anna. "Separation of variables for ordinary differential equations." Thesis, Linköping University, Department of Mathematics, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-5620.
Повний текст джерелаАнотація:
<p>In case of the PDE's the concept of solving by separation of variables</p><p>has a well defined meaning. One seeks a solution in a form of a</p><p>product or sum and tries to build the general solution out of these</p><p>particular solutions. There are also known systems of second order</p><p>ODE's describing potential motions and certain rigid bodies that are</p><p>considered to be separable. However, in those cases, the concept of</p><p>separation of variables is more elusive; no general definition is</p><p>given.</p><p>In this thesis we study how these systems of equations separate and find that their separation usually can be reduced to sequential separation of single first order ODE´s. However, it appears that other mechanisms of separability are possible.</p>
26
Tidy, Samantha Ellen, and samtidy@iprimus com au. "In Heaven, as it is on Earth: Representations of literary heavens in contemporary literature, with a focus on Alice Sebold's The Lovely Bones." RMIT University. Creative Media, 2009. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20090721.145607.
Повний текст джерелаАнотація:
This exegesis examines the landscape of heaven depicted in the contemporary novel, The Lovely Bones by Alice Sebold. I examine the various characteristics of the heaven (or 'afterlife') depicted in Sebold's novel, with the aim of ascertaining the narrative effects of using this device. Using Ingrid Daemmrich's analysis of the paradisiacal motif in literature as a framework (Daemmrich, I 1997, Studies on Themes and Motifs in Literature: Enigmatic Bliss, The Paradise Motif in Literature, Peter Lang, New York), I reveal characteristics in The Lovely Bones that are both consistent with and challenge traditional literary representations of heaven and which therefore demonstrate that the text utilises the established literary motif of heaven for symbolism and meaning, but in a contemporary context. I explore the growing trend of contemporary literary heavens by reviewing two other literary heavens that are relevant to this scholarship. I examine where as writers and readers, we ascertain our concept of heaven (in society's religious foundations and from prior literature), and for the relevance of the key text, I briefly discuss the author's likely cultural influences. Having established the novel's lack of alignment with a religious version of heaven, I then examine the nature of and the narrative effect of, the personalised heaven depicted in the novel, The Lovely Bones. In doing so, I explore one of the new portraits of heaven in literature, an example which represents a growing trend away from portraying a classic edenic heaven shared by all humanity (and traditional to literary representations of heaven), toward a contemporary, personalised heaven that seeks to meet the wants and desires of the individual in our modern society. With reference to literature's ability to reflect back to us, our society's beliefs and values, I examine what this new portrait of heaven reveals about society. Access to the project examined in conjunction with this exegesis has been restricted due to copyright.
27
Dunn, Ashley L. "Jackknife stability of articulated tractor semitrailer vehicles with high-output brakes and jackknife detection on low coefficient surfaces." The Ohio State University, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=osu1061328963.
Повний текст джерела
28
Tanriverdi, Vedat. "Nuclear Dissipative Dynamics In Langevin Approach." Master's thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/12605034/index.pdf.
Повний текст джерелаАнотація:
In this thesis Langevin approach is applied to analyze the nuclear
dissipative dynamics in fission and fusion reactions. In these
investigations, the nuclear elongation coordinate and the
corresponding momentum are chosen as collective variables. By
considering changes in these variables the decay rate of fission
and the formation probability of fusion for heavy ion reactions
are calculated. These calculations are performed using simulation
techniques and the results thus obtained are compared with the
corresponding results of analytic solutions.
29
Newbury, James. "Limit order books, diffusion approximations and reflected SPDEs : from microscopic to macroscopic models." Thesis, University of Oxford, 2016. https://ora.ox.ac.uk/objects/uuid:825d9465-842b-424b-99d0-ff4dfa9ebfc5.
Повний текст джерелаАнотація:
Motivated by a zero-intelligence approach, the aim of this thesis is to unify the microscopic (discrete price and volume), mesoscopic (discrete price and continuous volume) and macroscopic (continuous price and volume) frameworks of limit order books, with a view to providing a novel yet analytically tractable description of their behaviour in a high to ultra high-frequency setting. Starting with the canonical microscopic framework, the first part of the thesis examines the limiting behaviour of the order book process when order arrival and cancellation rates are sent to infinity and when volumes are considered to be of infinitesimal size. Mathematically speaking, this amounts to establishing the weak convergence of a discrete-space process to a mesoscopic diffusion limit. This step is initially carried out in a reduced-form context, in other words, by simply looking at the best bid and ask queues, before the procedure is extended to the whole book. This subsequently leads us to the second part of the thesis, which is devoted to the transition between mesoscopic and macroscopic models of limit order books, where the general idea is to send the tick size to zero, or equivalently, to consider infinitely many price levels. The macroscopic limit is then described in terms of reflected SPDEs which typically arise in stochastic interface models. Numerical applications are finally presented, notably via the simulation of the mesocopic and macroscopic limits, which can be used as market simulators for short-term price prediction or optimal execution strategies.
30
Gaigalas, Raimundas. "A Non-Gaussian Limit Process with Long-Range Dependence." Doctoral thesis, Uppsala : Matematiska institutionen, Univ. [distributör], 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-3993.
Повний текст джерела
31
Horák, Miroslav. "Konstrukční návrh lineární osy pro těžký obráběcí stroj." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2019. http://www.nusl.cz/ntk/nusl-400950.
Повний текст джерелаАнотація:
This diploma thesis deals with the design of linear axis for heavy machine tool. The thesis describes the definition of heavy machine tool and its basic construction nodes. The next chapter describes the components of the linear feed assemblages, the basic principles of use and their advantages and disadvantages. On the basis of this research part there are selected variants of the solution and in the last part of the thesis there is a design of the axis X of the gantry machine tool. Part of the work is a 3D model of the proposed feed assemblages and part of the drawing documentation.
32
Jalkebo, Charlotte. "Placement of Controls in Construction Equipment Using Operators´Sitting Postures : Process and Recommendations." Thesis, Linköpings universitet, Maskinkonstruktion, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-108980.
Повний текст джерелаАнотація:
An ergonomically designed work environment may decrease work related musculoskeletal disorders, lead to less sick leaves and increase production time for operators and companies all around the world. Volvo Construction Equipment wants to deepen the knowledge and investigate more carefully how operators are actually sitting whilst operating the machines, how this affects placement of controls and furthermore optimize controls placements accordingly. The purpose is to enhance their product development process by suggesting guidelines for control placement with improved ergonomics based on operators’ sitting postures. The goal is to deliver a process which identifies and transfers sitting postures to RAMSIS and uses them for control placement recommendations in the cab and operator environments. Delimitations concerns: physical ergonomics, 80% usability of the resulted process on the machine types, and the level of detail for controls and their placements. Research, analysis, interviews, test driving of machines, video recordings of operators and the ergonomic software RAMSIS has served as base for analysis. The analysis led to (i) the conclusion that sitting postures affect optimal ergonomic placement of controls, though not ISO-standards, (ii) the conclusion that RAMSIS heavy truck postures does not seem to correspond to Volvo CE’s operators’ sitting postures and (iii) and to an advanced engineering project process suitable for all machine types and applicable in the product development process. The result can also be used for other machines than construction equipment. The resulted process consists of three independent sub-processes with step by step explanations and recommendations of; (i) what information that needs to be gathered, (ii) how to identify and transfer sitting postures into RAMSIS, (iii) how to use RAMSIS to create e design aid for recommended control placement. The thesis also contains additional enhancements to Volvo CE’s product development process with focus on ergonomics. A conclusion is that the use of motion capture could not be verified to work for Volvo Construction Equipment, though it was verified that if motion capture works, the process works. Another conclusion is that the suggested body landmarks not could be verified that they are all needed for this purpose except for those needed for control placement. Though they are based on previous sitting posture identification in vehicles and only those that also occur in RAMSIS are recommended, and therefore they can be used. This thesis also questions the most important parameters for interior vehicle design (hip- and eye locations) and suggests that shoulder locations are just as important. The thesis concluded five parameters for control categorization, and added seven categories in addition to those mentioned in the ISO-standards. Other contradictions and loopholes in the ISO-standards were identified, highlighted and discussed. Suggestions for improving the ergonomic analyses in RAMSIS can also be found in this report. More future research mentioned is more details on control placement as well as research regarding sitting postures are suggested. If the resulted process is delimited to concern upper body postures, other methods for posture identification may be used.
33
Long, Michael Thomas. "On the Statistical Correlation between the Heave, Pitch and Roll Motion of Road Transport Vehicles." Thesis, 2016. https://vuir.vu.edu.au/32281/.
Повний текст джерелаАнотація:
A global economy is reliant on the movement of a great variety of goods on a large scale. Because the vast majority of goods are not sufficiently robust, protective packaging is needed to mitigate the adverse effects of shock and vibration that occur during distribution.
In Australia and many other countries the predominant method for the transportation of goods is via a well-developed road network. To date, the vast majority of research into vibrations experienced during road distribution focuses only on the vertical motion of the transport vehicle as it has been shown to be the most severe. However, the pitching and rolling motions of the vehicle can contribute significant energy to the overall excitation of the vehicle and payload, and excite vibratory modes which are not stimulated by vertical vibration alone.
This research focuses on investigating the heave, pitch and roll motions of light transport vehicles, and the relationships which exist between the vibratory modes. Two different approaches were used to investigate the relationships, a series of in-service field experiments and a complementary series of numerical experiments. The field experiments were designed to identify the influence of key parameters upon the relationships. The parameters investigated included; vehicle speed, road roughness, payload mass and payload inertial properties (CG location and MOI). Since the in-service experiments are, to a large extent, uncontrolled, numerical experiments were required to further investigate the vehicle parameters in greater detail. Numerical experiments allowed for controlled investigation of individual parameters which, in practice, are difficult or impossible to vary in isolation.
34
Rodriguez, Marijuan Alberto. "Offshore Floating Platforms : Analysis of a solution for motion mitigation." Thesis, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-215507.
Повний текст джерелаАнотація:
Recent events regarding energy policies throughout the globe and advances in technology are making offshore wind farms become a reality. Most offshore wind farms are still, however, built close to land masses, and need to be rigidly attached to the seabed in one way or another. In many countries, both public and private entities are developing new concepts of floating platforms to overcome the thirty to thirty-five-metre depth limit. Some of these new platforms use and adapt previous Oil and Gas platform concepts, while others are built up from scratch. This Master Thesis covers a hydrodynamic and structural analysis of a new concrete floating platform concept developed for medium to deep waters. This work is based on data from experimental model-scale tests performed in a wave tank and from numerical models using linear potential theory, limited here only to regular wave trains. The study focused on the behavior of the heave plates attached to the platform: test data was analyzed in order to find indicators of the largest dynamic pressures on the plates when only motion data was available, and the structural behavior of the plates was studied under different static pressure distributions using a commercial Finite Element Method software. The results from these analyses show that the normal accelerations of the plates -assumed rigid- strongly correlate with the dynamic pressures measured; and that the general structural behavior of the plate, in terms of deformations and bending moments, is well captured when the hydrodynamic load distribution is simplified into a uniformly distributed load of the same magnitude. The results obtained will help reduce the computational effort currently needed in the design of these floating structures, especially at some stages, when numerous scenarios, load cases and combinations need to be studied.
35
Crema, Ilaria. "OSCILLATING WATER COLUMN WAVE ENERGY CONVERTERS INTEGRATED IN VERY LARGE FLOATING STRUCTURES." Doctoral thesis, 2017. http://hdl.handle.net/2158/1152946.
Повний текст джерелаАнотація:
The increasing population density and the industrial expansion significantly affect the availability of land. In this context, the high modularity of Very Large Floating Structures (VLFSs) may indeed represent a promising alternative for multipurpose use. Furthermore, the interest for the sea as a source of renewable marine energy, particularly for wave energy, has tremendously increased in the last decade and years. Among the large diversity of Wave Energy Converters (WECs), the Oscillating Water Column (OWC) is one of the most promising concept. Moreover, when an OWC is incorporated in a VLFS, its efficiency in terms of wave energy absorption is not only increased, but also it has additionally the benefit of attenuating the heave motion of the floating structure. Hence, there is a growing interest in the development of an innovative VLFS equipped with OWC devices. In this scope, the mitigating effect of the OWC on the heave motion of the VLFS can be combined with an increased efficiency of the OWC, thus better contributing to supply energy for the facilities located on the floating system.
The main goal of this PhD research is the investigation of a VLFS-OWC System conceived for a hypothetical installation in a Mediterranean area, characterized by a moderate wave climate. For this purpose, small-scale experiments have been carried out in the wave-current flume of the Maritime Engineering Laboratory (LABIMA) of Florence University.
The laboratory tests focused on the effect of:
(i) the OWC design parameters (i.e., OWC geometry);
(ii) the incident wave conditions (i.e., regular and irregular wave trains);
(iii) the damping induced by a non-linear air turbine (i.e., a self-rectifying impulse turbine) idealised by vents with different diameters in the OWC chamber roof;
(iv) the length and the heave motion of the VLFS
on the performance of the OWC, including the attenuating effect of the incorporated OWC on the heave motion of the VLFS-OWC system.
The design of the fixed OWC, VLFS and VLFS-OWC models as well as the testing programme and laboratory procedures, are based on an extensive literature review of the available numerical and physical models on OWC devices and VLFS technologies.
The main findings of this study may be summarized as follows:
- the most dominant parameters affecting the performance of a fixed OWC are the chamber width (in wave propagation direction), the front wall draught and the damping induced by the air turbine;
- the additional parameters affecting the efficiency of an OWC integrated in a VLFS are the length of the structure and the heave motion;
- formulae are developed for predicting the heave motion of the VLFS-OWC system respectively, for regular waves and irregular waves;
- formulae are developed for improving the prediction of the performance of a fixed OWC for a floating OWC (integrated in a VLFS) respectively, for regular irregular waves.
These findings have contributed to improve the understanding of the functioning of the OWC device and the relative importance of the aforementioned parameters affecting the device under moderate wave climate.
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Holmes, Michael W. R. "Effects of a simulated motion environment upon the physical demands of heavy materials handling operators /." 2005.
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Wellington, Claudia M. "Musculoskeletal disorders in Connecticut dental hygienists related to repetitive motion trauma from heavy work-load, posture, job mechanics and psychosocial factors." 1998. http://catalog.hathitrust.org/api/volumes/oclc/48206680.html.
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"Hydrodynamic Study of a Suction Stabilized Float (SSF)." Master's thesis, 2014. http://hdl.handle.net/2286/R.I.25934.
Повний текст джерелаАнотація:
abstract: In this work, the hydrodynamics of Suction Stabilization is studied. Suction stabilization was found to stabilize floating platforms/floats in a much better way as compared to the conventional methods. This was achieved by an effective increment in the metacentric height due to the Inverse Slack Tank (IST) effect. The study involves the analysis of the existing designs and optimizing its performance. This research investigates the stability of such floats and the hydrodynamic forces acting on the same for offshore applications, such as wind turbines. A simple mathematical model for the condition of parametric resonance is developed and the results are verified, both analytically and experimentally.<br>Dissertation/Thesis<br>Real time working of SSF in heavy wind and rain conditions<br>Animation explaining working of SSF<br>Experiment with patio umbrella mounted on SSF<br>Masters Thesis Mechanical Engineering 2014
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Baumgartner, Thomas Peter. "Fuel Consumption and Emissions of Turnpike Doubles in the Canadian Prairie Region." 2011. http://hdl.handle.net/1993/4447.
Повний текст джерелаАнотація:
This research analyzes fuel consumption and emissions of Turnpike double trailer combinations (Turnpikes) on a regional network in the Canadian Prairies. The research: (1) establishes current benchmarks for fuel consumption of Turnpikes and five-axle tractor semitrailers (3-S2s) with van trailers; (2) develops fuel consumption models for these vehicle types; (3) establishes an understanding of current operating characteristics of Turnpikes in the region; and (4) estimates their system-wide effects in terms of fuel consumption and emissions in Manitoba by applying the developed models. Canadian Prairie region-based carriers revealed an increase in Turnpike travel (from 2007-2009) of 44 percent after the twinning of the Trans-Canada Highway between Winnipeg and Regina in 2007 was completed. Turnpikes can save one third of fuel consumed when compared to 3-S2s; have higher fuel consumption in the winter months; and their use in 2009 reduced fuel consumption and CO2 emissions by five percent compared to 3-S2s.
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陳信安. "The Exploration of Serious Recreational Participating Motive, Lasting Factor, Recreational Benefit, Cost and Risk－Taking the Northern Area Large Heavy-Duty Motorcycle Association Members as the Example." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/19680120906355261659.
Повний текст джерелаАнотація:
碩士<br>國立體育大學<br>體育研究所<br>95<br>ABSTRACT
This study took the association members who like to ride large heavy-duty motorcycle in the northern area as the example. The theme was to explore 「hobby style」 serious recreational participant’s participating motive, lasting factor, recreational benefit, cost, etc. In addition, the similarity and difference between serious recreation and casual recreation were compared. This study belonged to qualitative research and used Stebbins serious recreational theory as the structure to write the interview outline. The method was structural and open in-depth interview. The interviewee must be the large heavy-duty motorcycle association member for at least 3 years. Moreover, this member must participate the association’s activity more than 18 times in the past half year. The interviewees included 10 members.
The result of this study indicates: 1. the interviewee’s participating motives included self-interest, social behavior, unconventionality, pure recreation, peer invitation. The analysis of the interviewee’s talking content and proportion indicated unconventionality and peer invitation were the stronger participating motives. 2. The interviewee’s main reason of lasting factor: good experience, gaining recognition, peer interaction, family’s support, releasing pressure, and advancing skills. 3. Regarding to the analysis of recreational benefit, the findings of this study included: (1) in the individual section: self-enrichment, self-actualization, self-performance, achievement, advancing self-image, self-satisfaction. (2) in the social section: social attraction, team cooperation, extending human relationship, additional benefit. (3) others: career and family both could be helpful. 4. Regarding the analysis of recreational cost, the findings of this study indicated the interviewee who participates the riding of heavy-duty motorcycle had to pay the following cost: (1) negative emotion, for example: worry, pressure, anxiety, fatigue, heartache, nervousness. (2) spending more money and more time, and risking the injury and death. However, all the interviewees took the positive attitude to face the recreational cost and risk. Furthermore, they recognized that the benefit from participating recreational activity was far more than the cost. Thus, they were willing to continue to participate. This was the reason for us to advocate and popularize serious recreation. 5. This study found the differences between serious recreation and casual recreation were: (1) having more achievement; (2) designed group activity; (3) climate and road condition have significant impact; (4) unique (speed and adventure); (5) high recreational cost (time and money); (6) abundant additional benefit (in-depth travel). Some interviewees stated that enjoying the speed and bearing the risk were the more unique part comparing riding heavy-duty motorcycle recreational activity with other recreational activities.
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Girão, Mariana Pereira dos Reis Cação. "O uso da simulação de veículos pesados na definição de fatores de agressividade." Master's thesis, 2017. http://hdl.handle.net/10316/83302.
Повний текст джерелаАнотація:
Dissertação de Mestrado Integrado em Engenharia Civil apresentada à Faculdade de Ciências e Tecnologia<br>O fluxo de tráfego de veículos pesados é um dos parâmetros que mais influencia o dimensionamento de pavimentos rodoviários. Em Portugal, esse fluxo é convertido num número equivalente de eixos-padrão, através de fatores de agressividade. Contudo, os fatores de agressividade mantêm-se inalterados desde, pelo menos 1995, pelo que se apresentam alheios à evolução que se tem vindo a verificar relativamente à frota de veículos pesados de mercadorias. Adicionalmente, novas metodologias de dimensionamento têm surgido, as quais se baseiam em espetros de carga contruídos através de dados coletados em estações de pesagem dinâmica (WIM – Weigh-in-motion), dados estes que nem sempre estão disponíveis.Com o intuito de superar a indisponibilidade de dados WIM, a presente dissertação avalia o uso da simulação de veículos pesados na definição dos fatores de agressividade. Para o efeito, analisaram-se os veículos que compõem o parque automóvel em Portugal, em termos de pesados de mercadorias. Posteriormente, os veículos que se verificaram ser os mais predominantes foram simulados para diferentes pesos de carga, obtendo-se as cargas aplicadas por cada pneu à estrutura do pavimento. Com essas cargas, calculou-se a agressividade para diferentes pesos de carga, construíram-se regressões e definiu-se uma metodologia que permite o cálculo da agressividade considerando apenas o número de veículos e o fator de carga. Em paralelo, usaram-se dados WIM e calculou-se a agressividade do tráfego coletado num ano. Finalmente, procedeu-se à validação da metodologia, através da comparação da agressividade simulada com a agressividade do tráfego coletado.Do trabalho realizado concluiu-se que os fatores de agressividade determinados através de simulação de veículos eram bastante aproximados dos fatores de agressividade obtidos através dos dados de tráfego coletados. Assim sendo, é possível afirmar-se que a indisponibilidade dos dados WIM pode ser ultrapassada recorrendo à simulação de veículos pesados. O mesmo trabalho permitiu também concluir que a definição de fatores de agressividade é influenciada por diversos parâmetros, dos quais apenas se considerou na presente dissertação o tipo de pneu e a área de contacto pneu-pavimento, o fator de carga e os mecanismos de deterioração.<br>The traffic flow of heavy vehicles is one of the parameters that most influence the design of road pavements. In Portugal, this flow is converted into a number of equivalent standard axle load, through aggressiveness factors.However, the aggressiveness factors have remained unchanged since at least 1995 and have therefore not kept pace with the evolution of the heavy goods vehicle fleet. In addition, new design methodologies have emerged, which are based on load spectra built through data collected in weigh-in-motion (WIM) stations. However, these data are not always available.In order to overcome the unavailability of WIM data, the present dissertation evaluates the use of heavy vehicle simulation to define aggressiveness factors. For this purpose, the Portuguese heavy goods vehicles fleet was analyzed. Subsequently, the most representative fleet’s vehicles were simulated for different load weights, obtaining the loads applied by each tyre to the pavement structure. With these loads, the aggressiveness was calculated for different load weights, regressions were constructed and a methodology was defined that allows the calculation of the aggressiveness considering only the number of vehicles and the load factor. In parallel, WIM data were used and the aggressiveness of the traffic collected in a year was calculated. Finally, the methodology was validated by comparing the simulated aggressiveness with the aggressiveness of the collected traffic.From the work carried out, it was concluded that the aggressiveness factors determined through vehicle simulation were quite close to the aggressiveness factors obtained through traffic data collected. Therefore, it can be stated that the unavailability of the WIM data can be overcomed by using heavy vehicle simulation.The same work also allowed us to conclude that the definition of aggressiveness factors is influenced by several parameters, of which only the tyre type and the tire-pavement contact area, the load factor and the deterioration mechanisms were considered in the present dissertation.
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Gueneli, Berna. "Challenging European borders : Fatih Akın's filmic visions of Europe." Thesis, 2011. http://hdl.handle.net/2152/ETD-UT-2011-05-3035.
Повний текст джерелаАнотація:
In my dissertation, I discuss three of Akın’s feature films: Im Juli (In July, 2000), Gegen die Wand (Head-On, 2004), and Auf der anderen Seite (The Edge of Heaven, 2007) in order to investigate Akın’s filmic visions of Europe. Through close textual readings, I analyze three aspects of his films in particular: the spatial conceptions of Europe (city- and landscapes), the sounds of Europe (music and languages) as well as the display of ethnic minorities and the changing urban demography in Germany and Europe. I argue that Akın employs an “aesthetic of heterogeneity” to portray his filmic Europe as a diverse space, in which multiethnic and multilingual music, people, and sceneries are juxtaposed with regions that often have been perceived historically and politically as distinct and complicated.
My first chapter discusses Akın’s conceptions and depictions of European Space in In July. By analyzing city- and landscapes, soundscapes, and dynamic spaces in In July, I argue that Akın provides a dynamic, fluctuating, and interconnected European space, including Eastern Europe and Turkey. In my second chapter, I scrutinize language use and dialogue in Head-On to map out the changing demographics in European urban spaces. Ultimately, I argue that Akın moves beyond Hamid Naficy’s theory of “accented cinema” by including accented languages and dialects for all protagonists, including Western Europeans. Through this linguistic polyphony, multilingualism and a diversity of accents are depicted as integral elements of today’s Europe. In my final chapter, I discuss the sound of Europe as depicted in The Edge of Heaven. Looking particularly at music (and music lyrics) in the film, I argue that Akın’s use of dubbed and remixed music (especially by the artist Shantel) underscores Akın’s filmic challenges to (national) European borders. By foregrounding the mixed styles of music, where an “original” becomes hard to decipher, the director shows, on an aural level, that blurring boundaries and multidirectional movement are the predominant components of today’s Europe.<br>text
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Barr, Neill G. "Aspects of nitrogen metabolism in the green alga Ulva: developing an indicator of seawater nitrogen loading." 2007. http://hdl.handle.net/2292/2522.
Повний текст джерелаАнотація:
The following research has focused on the utility of Ulva as an indicator of seawater nitrogen loading. Evaluation was made in three ways: 1) Observation of large-scale geographic variation in nitrogen status in natural populations around New Zealand in summer and winter, 2) Laboratory-based experimental assessment of the biochemical responses of N-indices in Ulva to nitrogen enrichment, and 3) Culturing standardized test-Ulva under low nutrient conditions which could be deployed into a variety of field situations. Seawater inorganic nutrient (nitrate, nitrite, ammonium and phosphate) concentrations and nitrogen (N)-indices (free amino acids, chlorophyll and total tissue nitrogen) in natural Ulva populations from 32 sites around New Zealand were compared. Sites were divided into 6 environmental categories: sheltered rural, exposed rural, rock pools, sheltered urban, exposed urban, and nitrogen-enriched urban sites. Seawater nutrient concentrations were highly variable between all sites in summer and winter. However, in the summer enriched urban sites had the highest mean total inorganic nitrogen concentrations and Ulva with the highest mean levels of all N-indices compared with any other environmental category. In the winter, Ulva contained more nitrogen (reflected in all N-indices) compared with Ulva in the summer, particularly in populations growing in colder southern seawater on more exposed coasts. The increase in Ulva N-status was not explained by increased seawater inorganic nitrogen concentrations. With univariate and multivariate statistical approaches it was shown that there was a significant effect of seawater temperature and site exposure on N-status in Ulva. Compared with other N-indices, stable nitrogen isotopes (δ15N) from Ulva growing in enriched urban sites had the widest range (4.77 ± 0.04 ‰ to 15.16 ± 0.03 ‰) of values compared with all other categories in both summer and winter. Conversely, Ulva from exposed rural sites had the lowest range of δ15N values compared with any other category (6.7 ± 0.1 to 8.8 ± 0.1 ‰) and showed no seasonal change in mean values (7.8 ‰ and 7.6 ‰ for summer and winter, respectively). In addition, δ15N values in Ulva were the only N-index that showed a significant difference between urban and rural categories. To test the relationship between inorganic nitrogen concentration in seawater and the responses of biochemical nitrogen indices in Ulva pertusa, several experiments were conducted in an outdoor, flow-through culture apparatus, in summer and winter. In this apparatus effects of ammonium concentration, nitrogen source (nitrate and ammonium), light and seawater motion were investigated. Of the same three N-indices examined in natural Ulva populations (free amino acids, chlorophyll and total tissue nitrogen), increases in free amino acids, particularly asparagine, provided the strongest indicator of increases in nitrogen availability. In addition, while tissue nitrogen and chlorophyll also increased with seawater nitrogen concentration, it was apparent that these indices were also strongly influenced by light, and probably season. Rates of ammonium assimilation provided no overall measure of the availability of nitrogen in seawater and were clearly affected by season. Similarly, growth rates in Ulva only showed a response to nitrogen addition in summer months. Stable isotopes of nitrogen (δ15N) in Ulva provided a clear distinction between natural and synthetic nitrogen sources, but more importantly, showed only minor fractionation (ranging from 1.3 ‰ to -1.9 ‰) of 15N supplied from synthetic nitrate and ammonium under both light-saturating and light-limiting conditions. To further develop Ulva as a standardized test-organism it was cultured in low-nutrient (non-polluted) seawater to deplete internal storage pools of nitrogen. Each month the resulting test-Ulva was then placed in surface-moored growth enclosures at a range of coastal sites around Auckland and then monitored for one year. In winter there were increases in seawater inorganic nitrogen concentrations and concomitant increases in free amino acid content. However, tissue nitrogen and chlorophyll content in test-Ulva showed similar increases (possibly saturating) across all sites suggesting that seasonal increases in these N-indices were also due to other seasonal factors (e.g., surface irradiance and / or seawater temperature). On the other hand, the total free amino acid pool showed strong differences between a low-nitrogen reference site and the other study sites all year round. It was probable that test-Ulva was integrating differences in tidally-averaged nitrogen loading that were not reliably detected in instantaneous seawater samples. In addition to N-indices in test-Ulva, levels of tissue heavy metals and stable isotopes of nitrogen showed strong differences with higher values of both typically found in urban environments compared with values found in non-polluted reference sites. It is concluded that several abiotic and biotic factors affect nitrogen status in Ulva, but the average nitrogen concentration in seawater, and the physical factors of temperature, light and water motion, appear to be the overarching determinants. It is further suggested that in combination with Ulva tissue δ15N values, tissue nitrogen and the free amino acid pool, as quantitative biochemical measures of nitrogen availability, are likely to provide useful information on both the amount and composition of nitrogen entering coastal environments.<br>Foundation for Research, Science and Technology. Auckland Regional Council.
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El-Khatib, Mayar. "Highway Development Decision-Making Under Uncertainty: Analysis, Critique and Advancement." Thesis, 2010. http://hdl.handle.net/10012/5741.
Повний текст джерелаАнотація:
While decision-making under uncertainty is a major universal problem, its implications in the field of transportation systems are especially enormous; where the benefits of right decisions are tremendous, the consequences of wrong ones are potentially disastrous.
In the realm of highway systems, decisions related to the highway configuration (number of lanes, right of way, etc.) need to incorporate both the traffic demand and land price uncertainties. In the literature, these uncertainties have generally been modeled using the Geometric Brownian Motion (GBM) process, which has been used extensively in modeling many other real life phenomena. But few scholars, including those who used the GBM in highway configuration decisions, have offered any rigorous justification for the use of this model.
This thesis attempts to offer a detailed analysis of various aspects of transportation systems in relation to decision-making. It reveals some general insights as well as a new concept that extends the notion of opportunity cost to situations where wrong decisions could be made. Claiming deficiency of the GBM model, it also introduces a new formulation that utilizes a large and flexible parametric family of jump models (i.e., Lévy processes). To validate this claim, data related to traffic demand and land prices were collected and analyzed to reveal that their distributions, heavy-tailed and asymmetric, do not match well with the GBM model. As a remedy, this research used the Merton, Kou, and negative inverse Gaussian Lévy processes as possible alternatives.
Though the results show indifference in relation to final decisions among the models, mathematically, they improve the precision of uncertainty models and the decision-making process. This furthers the quest for optimality in highway projects and beyond.