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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
461

Indicators and predictors of sleepiness

van den Berg, Johannes January 2006 (has links)
Sleep is a basic need as important as physical fitness and good nutrition. Without enough sleep, we will create a sleep debt and experience sleepiness. Sleepiness can be defined as the inability to stay awake, a condition that has become a health problem in our 24-hour-7-day-a-week society. Estimates suggest that up to one-third of the population suffers from excessive sleepiness. Among other interactions, sleepiness affects our performance, increasing the risk of being involved in accidents. A considerable portion of work related accidents and injuries are related to sleepiness resulting in large costs for the individuals and society. Professional drivers are one example of workers who are at risk of sleepiness related accidents. Up to 40% of heavy truck accidents could be related to sleepiness. A better knowledge about reliable indicators and predictors of sleepiness is important in preventing sleepiness related accidents. This thesis investigates both objective and subjective indicators of sleepiness, how these relate to each other, and how their pattern changes over time. The indicators investigated were electroencephalography, heart rate variability, simple reaction time, head movement, and subjective ratings of sleepiness (Study I-IV). In Study V, a questionnaire study was conducted with professional drivers in northern Sweden. This study mainly deals with predictors of sleepiness. When subjects were sleep deprived both objective and subjective ratings indicated a rapid increase in sleepiness during the first hour of the test followed by a levelling off. This change in pattern was evident for all the indicators except heart rate and heart rate variability. On the other hand, HRV was correlated with the increase of EEG parameters during the post-test sleep period. The changes in pattern of the indicators included in the thesis are analysed in the perspective of temporal patterns and relationships. Of the tested indicators, a subjective rating of sleepiness with CR-10 was considered to be the most reliable indicator of sleepiness. Of the investigated predictors of sleepiness, prior sleep habits were found to be strongly associated to sleepiness and the sleepiness related symptoms while driving. The influences of driving conditions and individual characteristics on sleepiness while driving were lower. A multidisciplinary approach when investigating and implementing indicators and predictors of sleepiness is important. In addition to their actual relations to the development of sleepiness, factors such as technical and practical limitations, work, and individual and situational needs must be taken into account.
462

Rapid Exchange Solution (RES) : En mekanisk omlastningslösning för horisontell överföring av containrar mellan olika transportmedel / Rapid Exchange Solution (RES) : A mechanical solution for horizontal transferring of containers between different means of transportation

Bovin, Jimmy January 2013 (has links)
Detta examensarbete genomfördes våren 2013 på Karlstads universitet där TD Rail & Industry i Västerås stod som uppdragsgivare. Projektet innefattade att kartlägga nuvarande omlastningslösningar av enhetslaster mellan järnvägstransporter och vägtransporter, och utarbeta en konceptuell omlastningslösning med fokus på att öka järnvägstransporternas flexibilitet gentemot vägtransporterna. Där vikten lades på att utarbeta ett välarbetat helhetskoncept. Projektet genomfördes med designprocessen som grund och innehöll bland annat momenten; förstudie, kravspecificering, idégenerering, konceptval m.m. Resultatet blev en vidareutveckling av det redan befintliga systemet CCT som bygger på horisontell överföringsteknik och möjliggör därför omlastning av enhetslaster direkt under kontaktledning. Skillnaden mellan RES och CCT är att man tagit bort ombyggnationen av tågvagn och lastbilschassi, som var en av CCTs stora svagheter, genom två hydrauliska ”teknikplattor”. Tack vare detta tillsammans med sin låga investeringskostnad/driftkostnad öppnar RES nya möjligheter för omlastning på fler strategiska punkter direkt utmed järnvägsnätet och därmed ökar järnvägstransporternas flexibilitet. Som vidareutveckling av RES föreslås ett samarbete med CCT där man initialt utför mer detaljerade beräkningar på teknikplattorna. / This Bachelor of Science thesis was carried out in spring 2013 at Karlstad University for a company called TD Rail and Industry placed in Västerås, Sweden. The project included mapping of current transferring solutions of unit loads between railway and road transports, and the development of a conceptual transferring solution with the focus to increase the flexibility of the railway transport. The importance was to develop a well-made overall concept rather than small detailed parts of it. The project followed the design process methodology and included parts like: pre-study, requirements specification, idea generation, concept selection etc.The result was a further development of an already existing system called CCT based on horizontal transferring technology and therefore allow transferring of units directly under the overhead contact line. Thanks to this, together with its low investment / operating costs RES opens new opportunities for additional strategic transferring places along the railway, thereby increasing the flexibility of rail transports. The difference between RES and CCT is that you no longer need to rebuild the railway cars or the truckchassis , which was one of CCTs major weaknesses, instead the lifting mechanism is replaced by two hydraulic "technique plates". As a further development of the RES a partnership with CCT is proposed.
463

Dynamic Decision Support for Regional LTL Carriers

Warier, Prashant 18 May 2007 (has links)
This thesis focuses on decision support for regional LTL carriers. The basic operating characteristics of regional LTL carriers are similar to those of national LTL carriers, i.e., they operate linehaul networks with satellites, breakbulks, and relays to consolidate freight so as to be able to cost-effectively serve their customers. However, there are also key differences. Most importantly, because the area covered by a regional carrier is smaller, a regional carrier handles less freight (sometimes significantly less) and therefore typically has fewer consolidation opportunities, which results in higher handling and transportation costs per unit of freight. Consequently, competing with national carriers on price is difficult. Therefore, to gain or maintain market share, regional carriers have to provide better service. To be able to provide better service, regional carriers have to be more dynamic, e.g., they have to be able to deviate from their load plan when appropriate, which creates challenges for decision makers. Regional carriers deliver about 60% of their shipments within a day and almost all of their shipments within two days. Furthermore, most drivers get back to their domicile at the end of each day. Therefore, the focus of the thesis is the development of effective and efficient decision models supporting daily operations of regional LTL carriers which provide excellent service at low cost. This thesis presents an effective solution approach based on two optimization models: a dynamic load planning model and a driver assignment model. The dynamic load planning model consists of two parts: an integer program to generate the best paths for daily origin-destination freight volumes and an integer program to pack freight into trailers and trailers into loads, and to determine dispatch times for these loads. Techniques to efficiently solve these integer program solution are discussed in detail. The driver assignment model is solved in multiple stages, each stage requiring the solution of a set packing models in which columns represent driver duties. Each stages determines admissible driver duties. The quality and efficiency of the solution approach are demonstrated through a computational study with real-life data from one of the largest regional LTL carriers in the country. An important "technique" for reducing driver requirements is the use of meet-and-turn operations. A basic meet-and-turn operation involves two drivers meeting at a location in between terminals and exchange trucks. A parking lot or a rest area suffices as a meet-and-turn location. This ensures that drivers return to the terminal where they started. More sophisticated meet-and-turn operations also exist, often called drop and hook operations. In this case, drivers do not exchange trucks, but one of their trailers. The motivation in this case is not to get drivers back to their domicile, but to reduce load- miles. The thesis presents analytical results quantifying the maximum benefits of using meet and turn operations and optimization techniques for identifying profitable meet-and-turn opportunities.
464

Schließringbolzen ohne Sollbruchstelle für wartungsfreie Verbindungen im Nutzfahrzeug- und Stahlbau

Städler, Hans-Albert 05 November 2012 (has links) (PDF)
Die Auswahl einer zweckmäßigen Verbindungstechnik hat großen Einfluss auf die Kosten für die Herstellung und Wartung von Gütern. Das mechanische Verbinden von Bauteilen mit Schließringbolzen gehört zum umformtechnischen Fügen. Damit werden kostengünstig unlösbare und mechanisch hoch beanspruchbare, punktförmige Verbindungen erzeugt. Die vorliegende Arbeit hatte das Ziel, in umfassender Form den Nachweis zu erbringen, dass mit Schließringbolzensystemen ohne Sollbruchstelle wartungsfreie Verbindungen hergestellt werden können. Diese Wartungsfreiheit bezieht sich auf den Erhalt der mechanischen Eigenschaften der Verbindung und des Korrosionsschutzes bis zur beabsichtigten Grenznutzungsdauer. Aus einer Analyse des Standes der Technik wurde der Forschungsbedarf hinsichtlich der Wartungsfreiheit von Schließringbolzenverbindungen aus mechanischer und korrosiver Sicht abgeleitet. In einem mehrstufigen Prüfprogramm, unterteilt nach Anwendungen im Nutzfahrzeugbau und Stahlbau, wurde nach maschinenbaulichen und stahlbaulichen Konzepten die mechanische Leistungsfähigkeit der Verbindungen untersucht. Die Forschungsergebnisse aus diesem Programm und der Test neu entwickelter Beschichtungssysteme für die Bolzen und die Schließringe bestätigten die Eingangsthese über die Wartungsfreiheit. Metallografische Analysen und FEM Rechnungen ergänzen die Arbeit. Sie ist in sechs Abschnitte unterteilt und enthält 135 Abbildungen, 25 Tabellen, 3 Anlagen. Es wurden 118 Literaturquellen berücksichtigt. Mit der Arbeit steht dem Ingenieur ein umfangreiches Auskunftsmaterial zum Vergleich von Schließringbolzenverbindungen mit anderen Fügeverfahren, besonders jedoch zur Verschraubung zur Verfügung. Die durchgeführten Untersuchungen und Aussagen sollten in zukünftiger Forschung zu einem ganzheitlichen Konzept für die rechnerische Auslegung und Dimensionierung von Schließringbolzenverbindungen nach dem Vorbild der VDI 2230 und der EN 1993 weitergeführt werden.
465

Individualisation of a Driver Coaching Service : Combining Design Ethnography and Service Design to Gain Insights About the Coaches’ Role and Activities

Rosenqvist, Rebecka, Wikström, Maria January 2018 (has links)
Services surround us every day and companies all over the world have to adapt to the demand of services to make their products more successful and attractive. This master thesis has, on behalf of Scania in Södertälje, Sweden, focused on the service Driver coaching, a service where drivers are dedicated a personal coach who gives regular calls to the drivers. The aim of the thesis was to explore how a driver coaching service could be individualised to each driver. Furthermore, the aim was to develop a design proposal for Driver coaching that creates value for both coaches and drivers. Three coaches from Sweden, Finland and Norway were observed and interviewed to identify what role the coaches have in the service and all the activities they perform. During the analysis of the ethnographic findings, explorations were made on whether valuable insights can be found by interpreting the data with service design visualisations. A customer journey was created which catalysed the analysis phase and helped to generate insights in which pain points could be identified. Three important themes that emerged from the insights were individualisation, trust and communication. Insights from the ethnographic findings and the literature review show that a driver coaching service should, in fact, be individualised. The design proposal that was developed enables different arrangements of the service, which fit each driver’s needs and goals, with the help of a driver profile. Conclusions include information about what is important to think about when designing a driver coaching service that is individualised. Lastly, the thesis contributes to research with lessons learned about how ethnographic data can be used in a generative service design process.
466

Rankine cycle based waste heat recovery system applied to heavy duty vehicles : topological optimization and model based control / Récupération de chaleur par cycle de Rankine dans un véhicule poid lourd : optimisation topologique et commande

Grelet, Vincent 18 January 2016 (has links)
L’évolution croissante du prix des carburants ainsi que les normes antipollution de plus en plus drastiques obligent les fabricants de véhicules commerciaux à développer des solutions innovantes pour réduire la consommation de carburant. Dans cet objectif, comme une grande partie de l’énergie contenue dans le carburant est directement relâchée à l’ambient sous forme de chaleur, celle-ci peut être valorisée et transformée via un cycle thermodynamique secondaire. Dans ce cadre, l’importante utilisation du cycle de Rankine à travers le monde en font un candidat naturel pour une implémentation dans un véhicule. Mais contrairement à une utilisation stationnaire, de nombreux obstacles se dressent pour une intégration totale dans un poids lourd. De nombreuses études ont été menées ces trente dernières années afin de déterminer le potentiel réel d’un tel système une fois embarqué à bord d’un véhicule. Les nombreuses sources de chaleur valorisables, les contraintes inhérentes à l’application embarquée ou encore les forts régimes transitoires induits par l’utilisation du camion doivent mener à une optimisation à la fois de l’architecture du système ainsi que de son système de contrôle. L’optimisation du système mène à un choix en terme de sources chaudes et froides, de topologie, de fluide de travail ainsi que de dimensionnement des composants afin de maximiser les performances. Le système de contrôle joue lui un rôle primordial afin de tirer un bénéfice maximum d’un tel système connaissant ses limites physiques ainsi que d’assurer une utilisation efficace. Dans cette thèse, une méthodologie de conception d’un système de valorisation des rejets thermiques est proposée. En se basant sur des simulations du véhicule complet basées sur un modèle détaillé, les thématiques de la sélection du fluide de travail, des sources chaudes et froides ainsi que l’optimisation des composants et du cycle sont approchées. Par la suite, le problème de contrôle en ligne de la surchauffe à la sortie de l’évaporateur est formalisé. En tenant compte des contraintes numériques d’implémentation, différentes stratégies de commande sont mises en place, allant du contrôleur PID à des structures plus avancées telle que la commande prédictive par modèle ou une loi de commande basée sur un observateur. La plupart de ces stratégies sont validées expérimentalement sur un banc d’essai mis en place durant la thèse / The constant evolution of oil prices and the more and more stringent automotive emission standards force the original engine manufacturers to search for innovative solutions in order to reduce oil consumption. As an important part of the energy contained in the primary carrier (the fuel) is lost to the ambient through heat, it seems convenient to recover a part of this thermal energy and to turn it into fuel consumption reduction. Thermodynamic bottoming cycle such as the Rankine cycle could be used to meet this objective. Its popular use throughout the world for electricity generation makes it a natural candidate for on-board implementation in vehicles. However, a certain number of hurdles are still present before the system can be efficiently applied to heavy-duty trucks. In the last thirty years, numerous studies heave been carried out to evaluate the real potential of that kind of system on a vehicle but nothing has yet been commercialized. The heat sources to recover from, the constraints relative to the on-board application and the long and frequent transient behavior of the vehicle mean both the system architecture and its control strategy need to be optimized. The system optimization leads to a choice in terms of working fluid, heat sources and sinks, and components sizing in order to maximize power recovery and hence the fuel saving. The control plays a major role by using the capability of such a system to ensure an efficient and safe operation and limiting the interactions with the other vehicle sub-systems. In this thesis, a system design methodology is introduced to optimize the system architecture using complete model-based vehicle simulation. The constraints relative to the mobile application are taken into consideration to evaluate the potential of such a system. Modelbased control strategies for on controlled variable, namely the superheat level, are developed. Constrained by the implementation platform, different control frameworks ranging from PID to model predictive controllers or observer based controllers are developed to fit into a normal automotive electronic control unit. Most of these novel strategies were experimentally validated on a test rig developed during the thesis
467

Perfil dos riscos cardiovasculares em motoristas profissionais de transporte de cargas da Rodovia BR-116 no trecho Paulista-Régis Bittencourt / Cardiovascular risk profile observed in professional truck drivers who work on Highway BR116 within the area of the state of São Paulo-Régis Bittencourt

Luciane Cesira Cavagioni 14 December 2006 (has links)
Introdução: As doenças cardiovasculares constituem a principal causa demorbimortalidade nacional. Nesse sentido realizou-se estudo com o objetivo de caracterizar o perfil para riscos cardiovasculares em motoristas profissionais de transporte de cargas que trafegam pela Br-116. Casuística e Método: Estudo transversal, descritivo e exploratório com 258 motoristas profissionais de transporte de cargas com obtenção de informações socioeconômicas; avaliações antropométricas: índice de massa corporal (IMC), circunferência abdominal e medida da pressão arterial; realização de exames laboratoriais: triglicérides, colesterol total e frações, proteína C reativa e creatinina. Analisou-se o risco para doenças cardiovasculares pelo Escore de Risco de Framingham, consumo de bebidas alcoólicas pelo Alcohol Use Disorders Identification-AUDIT, distúrbios psiquiátricos comuns pelo Self Report Questionnaire-SRQ-20, Síndrome Metabólica e angina pectoris pelo Teste de Rose. Os dados foram processados no sistema SPSS v.7.5. O nível de significância adotado foi p<0,05, utilizou-se análise univariada e multivariada. Resultados: A caracterização os motoristas estudados mostrou idade 37,5±10,1 anos, 91% de etnia branca, renda mensal 1.431,3±644,4 reais, 19% tabagistas, 55% referiram ingestão de bebidas alcoólicas, 74% não realizavam atividade físicas, 14% relataram uso de medicamentos inibidores do sono, tempo profissão de 14±10 anos e percorriam 782,9±229,6 km/dia, dirigiam 10 horas por dia e repousavam 06 horas diárias. Verificou-se pelos dados antropométricos que 46% tinham sobrepeso, 36% obesidade e 58% circunferência abdominal alterada (_94 cm). Os exames laboratoriais mostraram 33% com nível de colesterol total _ 200mg/dL, 10% LDL-c _ 160 mg/dL; HDL-c < 40 mg/dL 23%, triglicérides acima de 150 mg/dL 38%, glicemia _ 110mg/dL 7% e proteína C reativa > 0,5 mg/dL 19%, creatinina >1,5 mg/dL 1%. A prevalência da hipertensão arterial foi de 37% e da Síndrome metabólica 24%. O Questionnaire Rose foi positivo em 8,0% dos motoristas, Escore de Risco de Framingham médio/alto em 9%, presença de distúrbios psiquiátricos comuns em 33% e AUDIT 16% no escore que sugere intervenção e aconselhamento. A análise de regressão logística indicou associação independente para as seguintes variáveis (OD Odds ratio, IC intervalo de confiança a 95%): 1-Síndrome Metabólica: IMC (OR=1,40 IC 1,192-1,661); hábito de verificar o colesterol total (OR= 0,102 IC 0,017-0,589); e escore de risco de Framingham médio/alto (OR= 26,389 IC 2,520-276,374). 2-Hipertensão arterial: IMC (OR=1,183 IC 1,065-1,314); glicemia (OR=1,039 IC 1,004-1,076); e hábito de ingerir medicamento para inibir o sono (OR= 0,322 IC 0,129-0,801). 3- Colesterol Total (_ 200 mg/dL): LDL-c (OR=1,157 IC 1,100-1,216);triglicérides (OR=1,012 IC 1,004-1,021) 4- Glicemia (_ 110 mg/dL): IMC (OR=1,153 IC 1,024-1,298); maior tempo de profissão (OR=1,154 IC 1,057-1,259) 5-Proteína C reativa (>0,5 mg/dL): escore de risco de Framingham médio/alto (OR=4,692 IC 1,912-11,515). Conclusão: Verificou-se presença expressiva de fatores de risco cardiovasculares, nesse sentido os profissionais de saúde devem implementar estratégias para estimular mudanças de estilos de vida nos motoristas de transporte de cargas, visando a prevenção primária e secundária / Introduction: Cardiovascular diseases are the main cause of morbidity and mortality in Brazil. Therefore, a study aiming at characterizing the cardiovascular risk profile observed in professional truck drivers who work on Highway Br-116 was carried out. Population and Method: An exploring, descriptive and transversal study with 258 professional truck drivers, social economical information, both body mass index (BMI) and waist circumference evaluations, blood pressure measurement, as well as laboratory test performance: triglycerides, total and fraction cholesterol, and C reactive protein. The risk for cardiovascular diseases was assessed by Framingham scores; alcohol intake by Alcohol Use Disorders Identification-AUDIT; common psychiatric disorders by Self Report Questionnaire-SRQ-20; and angine pectoris by Rose´s test Data were processed in the SPSS system v.7.5, considering that the significance level adopted was 0,05, and univaried and multivaried analyses were used. Results: The characterization of the drivers studied revealed age of 37.5±10.1 years, 91% of them were white, monthly income 1.431,3 ± 644,4 reais (Brazilian currency), 19% were smokers, 55% referred alcohol intake, 74% did not make physical exercises, 14% referred using sleeping inhibitor drugs, professional time 14±10 years and used to drive 782,9±229,6 Km/day. It was observed that 46% of them were overweight and 36% were obese and 58% had altered waist circumference (_ 94 cm) by the anthropometric data. The lab tests showed 33% with total cholesterol level _200 mg/dL, 10% LDLc _160 mg/dL, HDL-c <40 mg/dL 23%, triglycerides over 150 mg/dL 38%, glycemy _110mg/dL 7%, and C reactive protein >0.5 mg/dL 19%. The prevalence of hypertension was 37% and of Metabolic Syndrome, 24%. Rose’s test was positive for 8% of the drivers, Medium/High Framingham scores for 9%, presence of common psychiatric disturbs in 33% and 16% with AUDIT score suggesting intervention and advisory. The logistical regression analysis indicated independent association for the following variables: (OR Odds ratio, CI confidence interval at 95%): 1- Metabolic Syndrome: BMI (OR=1,40 CI 1,192-1,661); the habit of checking the total cholesterol (0,102 IC 0,017-0,589); Medium/high Framingham score (OR=26,389 IC 2,520-276,374); 2-Hypertension: BMI (OR=1,183 IC 1,065-1,314); glycemy (OR=1,039 IC 1,004-1,076); the habit of taking sleeping pills (OR=0,322 IC 0,129-0,801). 3- Total Cholesterol (_ 200 mg/dL): LDL-c (OR=1,157 IC 1,100-1,216); triglycerides (OR=1,012 IC 1,004-1,021). 4- Glycemy (_ 110 mg/dL): BMI (OR=1,153 IC 1,024-1,298); professional time (OR=1,154 IC 1,057-1,259). 5- C reactive protein (>0,5 mg/dL): Medium/high Framingham score (OR=4,692 IC 1,912-11,515). Conclusion: It was observed an expressive presence of cardiovascular risk factors. Therefore health professionals should implement strategies to stimulate changes in truck drivers’ lifestyle, aiming at primary and secondary prevention
468

Logistika firmy Gefco / Logistics of company GEFCO

Severová, Petra January 2008 (has links)
My graduation work is focused on logistics aplication at specific provider of logistics services. In theoretical part I describe development of logistics, types and links of supply chain and supply chain in automotive industry. In my application part I describe company GEFCO and car producer TPCA. I analyse present situation, standard and non-standard activities solved by department GEFCO Overland. Next I appreciate questionnaire survey, where I find out hot company's problems and try to give their solution that can increase effectivity, decrease costs and provide more valuable services to company's customers.
469

Modelling and control of an articulated underground mining vehicle

Kohlmeyer, Rolf Reimar 12 July 2012 (has links)
The automation of the tramming or load, haul and dump (LHD) procedure, performed by a LHD vehicle, holds the potential to improve productivity, efficiency and safety in the mining environment. Productivity is mainly increased by longer working hours; efficiency is improved by repetitive, faultless and predictable work; and safety is improved by removing the human operator from the harsh environment. However, before the automation of the process can be addressed, a thorough understanding of the process and its duty in the overall mining method is required. Therefore, the current applicable mining methods and their areas of potential automation are given. Since the automation of the LHD vehicle is at the core of this project, its implementation in the tramming process is also justified. Also, the current underground navigation methods are given and their shortcomings are named. It is concluded that infrastructure-free navigation is the only viable solution in the ever-changing mining environment. With that in mind, the feasibility of various navigation sensors is discussed and conclusions are drawn. Both kinematic and dynamic modelling of LHD vehicles are introduced. Various forms of kinematic models are given and their underlying modelling assumptions are named. The most prominent assumptions concern the vehicle’s half-length and the inclusion of a wheel-slip factor. Dynamic modelling techniques, with a strong emphasis on tyre modelling, are also stated. In order to evaluate the modelling techniques, field tests are performed on the articulated vehicles, namely the Wright 365 LHD and the Bell 1706C loader. The test on the Wright 365 LHD gives a good impression of the harsh ergonomics under which the operator has to work. A more thorough test is performed on the Bell 1706C articulated loader. The test results are then compared to simulation results obtained from the kinematic models. Also, the above-named assumptions are tested, evaluated and discussed. A dynamic model is also simulated and discussed. Lastly, two localization and control methods are given and evaluated. The first method is an open-loop nonlinear optimal control strategy with periodic position resetting and the second method is a pathtracking controller. AFRIKAANS : Automatisering van die laai-, vervoer- en dompel- (LVD) prosedure het die potensiaal om die produktiwiteit, effektiwiteit en veiligheid van die mynbedryf te verbeter. Produktiwiteit word hoofsaaklik deur langer werksure verhoog, effektiwiteit word deur herhalende, foutlose en voorspelbare werk verbeter en veiligheid word verbeter omdat menslike operateurs uit die gevaarlike ondergrondse omgewing verwyder word. Voordat aandag aan die automatisering van die prosedure geskenk kan word, moet die prosedure en die algemene mynbedrywighede rakende die prosedure deeglik bestudeer en verstaan word. As gevolg hiervan word die huidige, toepaslike mynboumetodes hier gedokumenteer. Die implementering van ʼn gekoppelde LVD-voertuig in die LVD-prosesword ook geregverdig. Verder word die huidige metodes van ondergrondse navigasie genoem en hulle tekortkominge aangedui. Die gevolgtrekking dat infrastruktuur-vrye navigasie die enigste lewensvatbare navigasiemetode in die immer veranderende ondergrondsemynbouomgewing is, word ook gemaak. In die lig daarvan word ʼn verskeidenheid sensors genoem en bespreek. Kinematiese en dinamiese modellering van ʼn LVD-voertuig word bekendgestel. Verskeie kinematiese modelle en hulle onderliggende aannames word genoem. Die mees prominente aannames is die lengte van die gekoppelde voertuig se hoofdele en die insluiting van ʼn wielglipfaktor. Die tegnieke van dinamiese modellering, met die klem op bandmodellering, word ook gegee. Praktyktoetse op gekoppelde voertuie is ook gedoen om die verskillende modelle te evalueer. Die toets op die Wright 365-LVD bied goeie insig in die strawwe ergonomiese toestande waaronder die operateurs moet werk. ʼn Deeglike toets is op ʼn BELL 1706C- gekoppelde laaier, wat kinematies identies aan ʼn LVD-voertuig is, uitgevoer. Die bevindinge van die toets word met bogenoemde modelsimulasies vergelyk en gevolgtrekkings word gemaak. Laastens word lokalisiering en beheer van ʼn LVDvoertuig behandel. Twee beheermetodes, opelus- nie-lineêre optimale beheer met periodieke herstel en padvolgingbeheer word geëvalueer en bespreek. Copyright / Dissertation (MEng)--University of Pretoria, 2012. / Electrical, Electronic and Computer Engineering / unrestricted
470

Predictive Energy Management of Long-Haul Hybrid Trucks : Using Quadratic Programming and Branch-and-Bound

Jonsson Holm, Erik January 2021 (has links)
This thesis presents a predictive energy management controller for long-haul hybrid trucks. In a receding horizon control framework, the vehicle speed reference, battery energy reference, and engine on/off decision are optimized over a prediction horizon. A mixed-integer quadratic program (MIQP) is formulated by performing modelling approximations and by including the binary engine on/off decision in the optimal control problem. The branch-and-bound algorithm is applied to solve this problem. Simulation results show fuel consumption reductions between 10-15%, depending on driving cycle, compared to a conventional truck. The hybrid truck without the predictive control saves significantly less. Fuel consumption is reduced by 3-8% in this case. A sensitivity analysis studies the effects on branch-and-bound iterations and fuel consumption when varying parameters related to the binary engine on/off decision. In addition, it is shown that the control strategy can maintain a safe time gap to a leading vehicle. Also, the introduction of the battery temperature state makes it possible to approximately model the dynamic battery power limitations over the prediction horizon. The main contributions of the thesis are the MIQP control problem formulation, the strategy to solve this with the branch-and-bound method, and the sensitivity analysis.

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