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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.
51

Slöseri i anläggningsbranschen : En fallstudie av produktionsprocessen för vägentreprenader

Bergbom, Axel January 2020 (has links)
Det kommer ske stora investeringar inom den svenska infrastrukturen fram till år 2029. Detta leder till en stor möjlighet för entreprenadföretag inom branschen att växa på marknaden och få en ökad lönsamhet. För att generera en bra lönsamhet krävs det att tillgängliga resurser nyttjas på bästa sätt och slöseri minimeras så att en ökad effektivitet kan uppnås för processer. Ser man till hållbarhetsaspekten kan upp till 40% av de globala utsläppen av växthusgaser kopplas mot bygg- och anläggningsbranschen. För att anläggningsbranschen ska kunna bidra till en hållbar utveckling på sikt krävs det därför att slöseri minimeras och effektiva processer uppnås. Studien fokuserar på slöseri inom anläggningsbranschen då det idag är ett relativt outforskat område sett till antal publicerade arbeten inom problemområdet.   Studiens syfte har varit att undersöka slöseri för produktionsprocessen inom vägentreprenader. Detta har realiserats med hjälp av en fallstudie på ett anläggningsföretag. Genom att kartlägga slöseriet och dess orsaker har målet varit att ta fram ett effektiviseringsförslag för produktionsprocessen. Detta för att slöseriet ska reduceras och en effektivare produktionsprocess ska uppnås. Dessutom har målet varit att bidra till forskningen inom slöseri för anläggningsbranschen.   För att uppfylla studiens syfte har ett utforskande forskningssyfte tillämpats. Detta för att öka förståelsen inom problemområdet. Forskningsansatsen är av induktiv karaktär då studien utgår från observationer i verkligheten från intervjuer och fokusgrupp, till en generalisering av en teoretisk modell. En kvalitativ strategi har tillämpats för studien då fokus har legat på att skapa större förståelse för problemområdet och ge möjligheten att anpassa forskningen efter vad som uppkommit vid datainsamlingen. Datainsamlingsmetoderna som nyttjats för studien är litteraturstudie, intervjuer, fokusgrupp och kvalitativa sekundärdata. Triangulering och granskning från handledare har även nyttjats för att säkerställa studiens trovärdighet och kvalitet.   Studien visar att slöseri i form av väntan, onödiga transporter och felaktigt utförande återfinns i produktionsprocessen för vägentreprenader. Slöseriet uppstår primärt för aktiviteterna schaktning och avvattningsåtgärder, sprängning och transporter. Orsakerna till slöseriet kan delas in i två kategorier: externa och interna. Externa orsaker uppkommer från beställare, leverantör och geografiskt läge. Detta i form av långa körsträckor, resursbrist, tillhandahållande av beslut och bygghandlingar samt kompetens och rutin hos maskinförare. Interna orsaker uppkommer från entreprenören i form av begränsad styrning och kontroll över produktionen. Effektiviseringsförslaget togs fram genom programmet DynaRoad för att skapa massdisponeringsplaner för att minimera slöseriet onödiga transporter och få en bättre resurseffektivitet.   Den huvudsakliga rekommendationen till fallföretaget är att prioritera planeringen för sin entreprenadverksamhet. Detta ger fallföretaget bättre projektförutsättningar, vilket leder till att effektivare processer kan uppnås då slöseri minimeras. / The Swedish infrastructure will receive large investments until year 2029. This leads to big opportunities for construction companies within the industry to grow and increase their profitability. To generate good profit, it is important that the available resources are used in the best possible way so waste can be minimized, and efficient processes can be achieved. Taking the sustainability aspect in consideration, 40% of the global emissions can be linked to the construction sector. In order to reduce the environmental impact and contribute to sustainable development, the construction sector needs to minimize waste and achieve efficient processes. The focus of this thesis is regarding waste within construction industry and civil engineering projects, because of the limited research conducted within the field.   The aim of this thesis was to investigate waste for the production process regarding road projects. Further, their causes have also been investigated. This has been done by a case study on a construction company. By mapping the waste and their causes the aim has been to produce a recommendation to streamline the company´s operation. Further, the goal for this study has also been to contribute to the research on waste in the construction industry, with a focus towards road construction projects.   An exploratory researched been used for this thesis, to achieve the aim. This to increase the understanding for the field of study. The research approach is inductive hence, the study is based on observations from interviews and focus group, to a generalization of a theoretical model. A qualitative strategy has been applied for the thesis since the aim has been to create a deeper understanding for the field of study and give the possibility to adjust the research depending on what is found in the data collection. To collect data for this thesis a literature study, interviews, focus group and qualitative secondary data has been used. Further, triangulation and review by the supervisors has been used to ensure the credibility and quality for the thesis.   The study identifies waste in waiting, unnecessary transportation and improperly execution for the production process in road projects. The waste arises primarily for the activities excavation, blasting and transportation. The causes can be divided into two categories: external and internal. External causes emerge from clients, suppliers and geographical location. This in the form of long mass haul distances, resource shortage, provision of construction documents & decisions and competence & routine by the machine operators. Internal causes arise from guiding and control over the production. The proposal for the production process was developed through the software DynaRoad to be able to create a mass haul plan in order to reduce the unnecessary transports and increase the resource efficiency.   The recommendation for the company where this thesis has been conducted is to put a lot of effort into their planning process. This will result in better project basis, which leads to increased efficiency when the waste can be minimized.
52

Advanced Signal Processing for Fiber-Optic Communication Systems Scaling Capacity Beyond 100 Tb/s / 光ファイバ通信システムの100 Tb/s容量限界の克服へ向けた信号処理技術

Shibahara, Kohki 25 September 2017 (has links)
京都大学 / 0048 / 新制・課程博士 / 博士(情報学) / 甲第20740号 / 情博第654号 / 新制||情||113(附属図書館) / 京都大学大学院情報学研究科通信情報システム専攻 / (主査)教授 守倉 正博, 教授 大木 英司, 教授 梅野 健 / 学位規則第4条第1項該当 / Doctor of Informatics / Kyoto University / DFAM
53

TRUE UNMANNED TELEMETRY COLLECTION USING OC-12 NETWORK DATA FORWARDING

Bullers, Bill 10 1900 (has links)
International Telemetering Conference Proceedings / October 20-23, 2003 / Riviera Hotel and Convention Center, Las Vegas, Nevada / The cost of telemetry collection is significantly reduced by unmanned store and forward systems made possible using 622MHz OC-12 networks. Networks are readily available to telemetry system architects. The in-band control of remote unmanned collection platforms is handled through a Java browser interface. Data from many telemetry channels are collected and temporarily stored on a digital disk system designed around the OC-12 network. The I/O, storage, and network components are configured, set, and initialized remotely. Recordings are started and stopped on command and can be made round-the-clock. Files of stored, time stamped data are delivered at the rate of OC-12 to a distribution center.
54

Alocação dinâmica de recursos: aplicação ao transporte rodoviário de cargas em longa distância. / Dynamic resource allocation: application to long haul freight transportation.

Lima Filho, Antonio Martins 13 May 2011 (has links)
O planejamento operacional de um sistema de transporte de longa distância implica resolver um problema de otimização de rede dinâmica, visando a efetuar, de forma eficaz e eficiente, o atendimento às demandas de cargas, utilizando a capacidade de transporte disponível. A metodologia de solução proposta utiliza a abordagem de Rede de Filas Logísticas, a qual substitui o processo de otimização global da rede (usualmente utilizando Programação Linear Inteira) por um modelo de Programação Dinâmica Estocástica, Aproximada e Adaptativa, que permite a resolução de uma série de subproblemas delimitados no tempo, reduzindo sensivelmente a quantidade de variáveis envolvidas. Este método permite a utilização de modelos matemáticos mais realistas em horizontes de planejamento mais amplos. O presente trabalho estende os modelos encontrados na Literatura, aplicando o método a problemas de maior complexidade, incluindo a consideração de frotas heterogêneas de veículos, janelas de início de atendimento, utilização de terceiros transportadores e penalidades pelo não atendimento das demandas. São apresentados exemplos de problemas experimentais submetidos com sucesso à técnica desenvolvida. O trabalho inclui ainda o delineamento de um Sistema de Apoio à Decisão incorporando a metodologia proposta. / Operational planning of a long haul transportation system implies to solve a dynamic network optimization problem, aiming to perform the freight movements in an efficient and effective way, while utilizing the available transportation capacity. The proposed solution methodology utilizes the Logistic Queueing Network approach, replacing the network global optimization process through Integer Linear Programming by a model of Stochastic, Approximate and Adaptive Dynamic Programming, which allows the resolution of a sequence of sub- problems delimited in time, strongly reducing the quantity of variables involved. This method allows the utilization of more realistic mathematical models in a broader planning horizon. The research extends models found in the literature to solve more complex problems, including the consideration of heterogeneous fleet of vehicles, time windows, third party vehicles and penalties for not attendance of demands. Experimental problems solved successfully with the developed technique are presented. The work also presents the delineation of a Decision Support System incorporating the proposed methodology.
55

Frontiers of optical networking technologies: millimeter-wave radio-over-fiber and 100g transport system for next-generation high-data-rate applications

Hsueh, Yu-Ting 04 April 2012 (has links)
The enabling technologies and the issues of next-generation millimeter-wave wireless access network and 100G long-haul optical transport network were developed and identified. To develop a simple and cost-effective millimeter-wave optical-wireless system, all-round research on the technical challenges of optical millimeter-wave generation, transmission impairments compensation, and simple base station design were discussed. Several radio-over-fiber systems were designed to simultaneously deliver multi-band wireless services on a single optical infrastructure, enabling converged system control and quality maintenance in central office. For the 100G optical transport network, the issues related to successful implementations of transmitter, fiber link, and receiver of a 112-Gb/s polarization-division multiplexing-quadrature phase shift keying (PDM-QPSK) system were comprehensively explored. The experimental results based on the constructed 112-Gb/s testbed indicated that careful dispersion management can effectively increase nonlinearity tolerance. Furthermore, the special emphasis on the two impairments of the 100G network with reconfigurable optical add-drop multiplexers: passband narrowing and in-band crosstalk, was studied. The results demonstrated that these impairments can be readily predicted with proper experimental and simulation efforts.
56

Estudo da sobrecarga dinamica em caminões por meio de medições diretamente no veiculo / Study of the dynamic overload on trucks by direct measurements in the vehicle

Antonio, Sergio Francisco Dela 12 August 2018 (has links)
Orientador: Auteliano Antunes dos Santos Jr / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-08-12T19:38:01Z (GMT). No. of bitstreams: 1 Antonio_SergioFranciscoDela_M.pdf: 2654431 bytes, checksum: a9d019fe7f3a17bc52fb361d8113f727 (MD5) Previous issue date: 2005 / Resumo: As cargas dinâmicas que ocorrem em veículos de carga quando estes estão em movimento, são fortemente responsáveis pela deterioração precoce do piso asfáltico das rodovias e logradouros no Brasil. Também são umas das principais responsáveis pelo desgaste excessivo e prematuro dos componentes do veículo. Estes dois fatores fazem com que os custos de transporte rodoviário no Brasil, de mercadorias e bens, fiquem mais elevados. O objetivo deste trabalho é avaliar uma metodologia para medir as cargas dinâmicas que ocorrem em veículos de carga. Na metodologia proposta, utilizou-se a própria suspensão do veículo como parte do sistema de medição, no caso, veículos com suspensão com feixes de molas. O sistema de medida das cargas dinâmicas é composto pelos feixes de molas e um transdutor de deslocamento. Gerou-se a curva de resposta do feixe de molas com relação aos deslocamentos ocorridos através da aplicação das cargas. Após os estudos preliminares, implantou-se este sistema na suspensão dianteira de um veículo de carga de porte médio. Estimaram-se as cargas dinâmicas em várias condições de piso com o veículo carregado, a partir dos deslocamentos medidos. Os resultados mostram que o sistema funcionou satisfatoriamente, e foi possível quantificar os níveis de cargas dinâmicas ocorridas em casos mais críticos. O maior nível encontrado foi de 33,9% acima da carga estática no lado esquerdo da suspensão dianteira, no trecho com lombadas. / Abstract: The dynamical loads and forces occurring in cargo vehicles under movement are among the major causes of the early deterioration on highway and road pavement in Brazil. These dynamical loads are also responsible for the premature and excessive wear on several vehicle components. These two factors combined are among the main reasons why road transportation costs are so expensive in Brazil. The objective of this work is to suggest and evaluate a methodology for measuring the dynamical loads and forces on moving cargo vehicles. This methodology utilizes the suspension system of the vehicle itself as part of the measurement system. In the experimental part of this study a force measuring system was conceived using the leaf spring assembly of the vehicle suspension combined with a simple displacement transducer strategically installed in the vehicle suspension. This force measuring system was installed in a mid-range cargo truck. The characteristic curve of the suspension leaf spring set was determined by the application of static loads onto the vehicle. After calibration and fine adjustments of the system, several experimental runs were performed in the loaded vehicle, measuring the dynamic loads in several pavement types and traffic conditions. The results showed that the system worked satisfactorily, and it was possible to determine the dynamic loads occurred on all experimental runs. The greatest dynamic load found in the field was 33,9 % above the static load on the left front suspension. / Mestrado / Mecanica dos Sólidos e Projeto Mecanico / Mestre em Engenharia Mecânica
57

Alocação dinâmica de recursos: aplicação ao transporte rodoviário de cargas em longa distância. / Dynamic resource allocation: application to long haul freight transportation.

Antonio Martins Lima Filho 13 May 2011 (has links)
O planejamento operacional de um sistema de transporte de longa distância implica resolver um problema de otimização de rede dinâmica, visando a efetuar, de forma eficaz e eficiente, o atendimento às demandas de cargas, utilizando a capacidade de transporte disponível. A metodologia de solução proposta utiliza a abordagem de Rede de Filas Logísticas, a qual substitui o processo de otimização global da rede (usualmente utilizando Programação Linear Inteira) por um modelo de Programação Dinâmica Estocástica, Aproximada e Adaptativa, que permite a resolução de uma série de subproblemas delimitados no tempo, reduzindo sensivelmente a quantidade de variáveis envolvidas. Este método permite a utilização de modelos matemáticos mais realistas em horizontes de planejamento mais amplos. O presente trabalho estende os modelos encontrados na Literatura, aplicando o método a problemas de maior complexidade, incluindo a consideração de frotas heterogêneas de veículos, janelas de início de atendimento, utilização de terceiros transportadores e penalidades pelo não atendimento das demandas. São apresentados exemplos de problemas experimentais submetidos com sucesso à técnica desenvolvida. O trabalho inclui ainda o delineamento de um Sistema de Apoio à Decisão incorporando a metodologia proposta. / Operational planning of a long haul transportation system implies to solve a dynamic network optimization problem, aiming to perform the freight movements in an efficient and effective way, while utilizing the available transportation capacity. The proposed solution methodology utilizes the Logistic Queueing Network approach, replacing the network global optimization process through Integer Linear Programming by a model of Stochastic, Approximate and Adaptive Dynamic Programming, which allows the resolution of a sequence of sub- problems delimited in time, strongly reducing the quantity of variables involved. This method allows the utilization of more realistic mathematical models in a broader planning horizon. The research extends models found in the literature to solve more complex problems, including the consideration of heterogeneous fleet of vehicles, time windows, third party vehicles and penalties for not attendance of demands. Experimental problems solved successfully with the developed technique are presented. The work also presents the delineation of a Decision Support System incorporating the proposed methodology.
58

Surf the roads? : An interview study aiming to investigate truck driver’s needs for a web browser in the truck cab

Johansson, Regina January 2011 (has links)
Long haul drivers spend a lot of time in their trucks which consequently serves as both a work place and a second home. The Internet, and communication and information technology can be used for both personal uses by the drivers, and lead to major savings for the haulage firms and provide high level service to the customers. This study investigates what needs long haul drivers have for using the Internet in their trucks, and which devise that best would suit their needs. A questionnaire study was held including 35 drivers, and an interview study including 30 drivers. The results show that almost all drivers want to perform work related tasks through the Internet, and several of them also want to use personal applications online. Work tasks online needs to be performed during the day, whereas private use of the Internet mostly would take place at nights. Several drivers are positive to an integrated system for using the Internet in the truck, and the study presents a possible concept for such a system, and discusses the results related to present research and applicable theories.
59

Monitoring energy efficiency of heavy haul freight trains with energy meter data / Uppföljning av energieffektiviteten för tunga godståg med hjälp av elmätardata

Geiberger, Philipp January 2021 (has links)
In this MSc thesis, it is investigated what parameters are relevant for describing energy consumption of heavy haul freight trains and how these can be used to develop key performance indicators (KPIs) for energy efficiency. The possible set of KPI is bounded by data available from energy meters used in electric IORE class locomotives hauling iron ore trains in northern Sweden. Furthermore, the analysis is only concerned with energy efficiency at the rolling stock level, excluding losses in the electric power supply network. Based on a literature study, parameters of interest describing driver, operations and rolling stock energy efficiency have been identified. By means of simulation, a parametric study is performed, simulating a 30 ton axle load iron ore train with 68 wagons. Train modelling input is obtained from technical documentation or estimated through measurements and statistical analysis. A multi-particle representation of the train is used to calculate gradient resistance for the simulation, which is also applied to determine the curve resistance.  Results show that the motion resistance is simulated quite accurately, while the lack of a driver model in the simulation tool leads to overestimation of energy consumption. Taking this into account, the importance of the driver for energy efficiency can still clearly be showcased in the parametric study. Especially on long steep downhill sections, prioritising the electric brakes over mechanical brakes is demonstrated to have a huge influence on net energy consumption, as has the amount of coasting applied. With the same driver behaviour in all simulations, the savings in specific energy from increasing axle load to 32.5 tons is estimated. Moreover, a comparison of increased train length and axle load points towards higher savings for the latter. In the end, parametric study results are used to recommend a structure for a monitoring system of energy efficiency based on a set of KPIs. With a sufficiently high sampling rate of energy meter data, it is adequate for calculating driver related KPIs and some additional KPIs. More KPIs can be tracked with access to additional data, e.g. cargo load. / I detta examensarbete undersöks vilka parametrar som är relevanta för att beskriva energiförbrukning för tunga godståg och hur dessa kan nyttjas för att utveckla nyckeltal för energieffektivitet. Antalet möjliga nyckeltal avgränsas till sådana som kan beräknas med data från elmätare som används i elektriska littera IORE lok som drar tunga malmtåg i norra Sverige. Vidare så tar analysen endast hänsyn till energieffektivitet för rullande materiel, vilket utesluter förluster i elektriska kraftmatningsnätet. Baserad på en litteraturstudie har relevanta parametrar som beskriver förare, drift och rullande materiel identifierats. Med hjälp av simuleringar av ett malmtåg med 30 tons axellast och 68 vagnar så utförs en parameterstudie. Indata för tågmodelleringen erhålls från teknisk dokumentation respektive uppskattas genom mätningar och statistisk analys. En representation av tåget som flertalet partiklar tillämpas i simulering för att beräkna lutningsmotståndet. Dessutom används densamma för att ta fram kurvmotståndet. Resultaten visar att gångmotstånd simuleras ganska exakt, medan avsaknad av en förarmodell i simuleringsvertyget leder till överskattad energiförbrukning. Med hänsyn tagen till detta så kan betydelsen av föraren för energieffektivitet fortfarande påvisas mycket tydligt i parameterstudien. I synnerhet i långa branta nedförsbackar har prioritering av den elektriska bromsen framför den mekaniska bromsen mycket stor påverkan på nettoenergiförbrukningen, likaväl som hur mycket tåget frirullar. Med samma förarbeteende i samtliga simuleringar har besparingar i specifik energiförbrukning kunnat uppskattats för en ökning av axellasten till 32,5 ton. Dessutom pekar en jämförelse av ökad tåglängd och axellast mot att sistnämnda ger större besparingar. Slutligen så har resultaten från parameterstudien nyttjats för att rekommendera en struktur för ett uppföljningssystem av energieffektivitet baserad på en uppsättning av nyckeltal. Med tillräckligt hög samplingsfrekvens på data från elmätare är den adekvat för att beräkna vissa nyckeltal, framförallt relaterad till förare. Fler nyckeltal kan följas upp med mer tillgänglig data så som lastvikter.
60

Soil Erosion from Forest Haul Roads at Stream Crossings as Influenced by Road Attributes

Lang, Albert Joseph 01 July 2016 (has links)
Forest roads and stream crossings can be important sources of sediment in forested watersheds. The purpose of this research was to compare trapped sediment and forestry best management practice (BMP) effectiveness from haul road stream crossing approaches and ditches. The three studies in this dissertation provide a quantitative assessment of sediment production and potential sediment delivery from forest haul roads in the Virginia Piedmont and Ridge and Valley regions. Sediment production rates were measured and modeled to evaluate and compare road and ditch segments near stream crossings with various ranges of road attributes, BMPs, and management objectives. Sediment mass delivered to traps from 37 haul road stream crossing approaches ranged from <0.1 to 2.7 Mg for the one year collection. Collectively, five approaches accounted for 82% of the total sediment mass trapped. Approaches were categorized into Low, Standard, and High road quality rankings according to road attributes. Seventy-one percent (5 of 7) of Low ranked approaches delivered sediment to traps at rates greater than 11.2 Mg ha-1 yr-1. Nearly 90% of Standard or High road quality approaches generated less than 0.1 Mg of sediment over one year. Among approaches with less than 0.1 Mg of trapped sediment, road gradients ranged from 1% to 13%, bare soil ranged from 2% to 94%, and distances to nearest water control structures ranged from 8.2 to 427.0 m. Such a wide spectrum of road attributes with relatively low levels of trapped sediment indicate that contemporary BMPs can mitigate problematic road attributes and reduce erosion and sediment delivery. Three erosion models, USLE-forest, RUSLE2, and WEPP were compared to trapped sediment data from the 37 forest haul road stream crossing approaches in the first study. The second study assessed model performance from five variations of the three erosion models that have been used in previous forest operations research, USLE-roadway, USLE-soil survey, RUSLE2, WEPP-default, and WEPP-modified. The results suggest that these soil erosion models could estimate erosion and sediment delivery within 5 Mg ha-1 yr-1 for most approaches with erosion rates less than 11.2 Mg ha-1 yr-1, while model estimates varied widely for approaches that eroded above 11.2 Mg ha-1 yr-1. Based on the results from the 12 evaluations of model performance, the modified version of WEPP consistently performed better compared to all other model variations tested. However, results from the study suggest that additional field evaluations and improvement of soil erosion models are needed for stream crossings. The soil erosion models evaluated are not an adequate surrogate for informing policy decisions. The third study evaluated sediment control effectiveness of four commonly recommended ditch BMPs on forest haul road stream crossing approaches. Sixty ditch segments near stream crossings were reconstructed and four ditch BMP treatments were tested. Ditch treatments were bare (Bare), grass seed with lime fertilizer (Seed), grass seed with lime fertilizer and erosion control mat (Mat), rock check dams (Dam), and completely rocked (Rock). Mat treatments had significantly lower erosion rates than Bare and Dam, while Rock and Seed produced intermediate levels. Findings of this study suggest Mat, Seed, and Rock ditch BMPs were effective at reducing erosion, but Mat was most effective directly following construction because Mat provided immediate soil protection measures. Any BMPs that reduce bare soil can provide reduction in erosion and even natural site condition, including litterfall and invasive vegetation can provide erosion control. However, ditch BMPs cannot mitigate inadequate water control structures. Overall, forest roads and stream crossings have the potential to be major contributors of sediment in forested watersheds when roads are not designed well or when BMPs are not properly implemented. Forestry BMPs reduce stormwater runoff velocity and volume from forest roads, but can have varying levels of effectiveness due to site-specific conditions. Operational field studies provide valuable information regarding erosion and sediment delivery rates, which helps guide BMP recommendations and subsequently enhances water quality protection. / Ph. D.

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