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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.
11

Preciznost nakládky krmiva u taženého velkoobjemového míchacího krmného vozu

FOJT, Miroslav January 2018 (has links)
The thesis deals with the breeding of cattle, especially the issue of distribution of feed, which is technologically solved in many variants. The second part is devoted to the selection of two mixing wagons of different constructions, their characteristics and description of the method of handling the feeds. The monitored data was then evaluated and processed into tables and graphs. Finally, the two different mixed feed wagons were compared and evaluated in terms of accuracy of loading and economy.
12

Desenvolvimento do aço microligado para rodas ferroviárias / Development of microalloyed steel for railway wheels

Villas Bôas, Renato Lyra 07 January 2010 (has links)
Orientador: Paulo Roberto Mei / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-16T10:24:52Z (GMT). No. of bitstreams: 1 VillasBoas_RenatoLyra_M.pdf: 13424471 bytes, checksum: c7a6d60275922ab9255b8f8e74fd29e1 (MD5) Previous issue date: 2010 / Resumo: Neste trabalho foi desenvolvido um aço microligado com 0,7% de carbono para fabricação de rodas ferroviárias. Tomou-se como base um aço classe C da norma AAR M-107 e adicionou-se nióbio e molibdênio. A pesquisa foi realizada em duas etapas distintas. A primeira etapa estudou-se o efeito da adição de nióbio e molibdênio no aço com 0,7% de carbono antes e após a deformação por laminação, simulando o forjamento real das rodas ferroviárias produzidas na MWL Brasil. Com os dados disponíveis passou-se à segunda etapa da pesquisa onde foram fabricadas e ensaiadas rodas ferroviárias na MWL Brasil usando um aço com composição química semelhante à utilizada na primeira etapa para observar o efeito do nióbio e molibdênio nas mesmas. Os aços foram austenitizados a 1250 °C para solubilização do nióbio na austenita e deformados a partir de 1200 °C. Na primeira etapa o aço foi laminado em 4 passes sofrendo uma deformação total na espessura de 67% e resfriado ao ar. Na segunda etapa, o aço foi forjado pelo processo de fabricação usado pela MWL Brasil. Após o tratamento térmico, foram realizados ensaios de dureza da perlita, tração, impacto, tenacidade à fratura, além de microscopia ótica e medida do tamanho de grão austenítico. Observou-se aumento no limite de escoamento (8,5%), ductilidade (15%), energia de impacto (29%), tenacidade à fratura (33%) e temperabilidade pela microadição de nióbio e molibdênio, mostrando que esses elementos podem melhorar o desempenho das rodas ferroviárias atualmente produzidas. / Abstract: In this work it was developed a microalloyed steel with 0.7% carbon to manufacture railway wheels. It was taken as basis a steel class C of standard AAR M-107 and added niobium and molybdenum. The research was conducted in two stages. The first step was studied the effect of the addition of niobium and molybdenum on 0.7% C steel before and after deformation by rolling, simulating the actual forging of railroad wheels process in MWL Brasil. With the available data the second stage of the research was conducted, manufacturing and testing railway wheels in MWL Brasil, using a steel with similar chemical composition to that was used in the first step to observe the effect of niobium and molybdenum in them. The steels were austenitized at 1250 °C for niobium solubilization in austenite and deformed from 1200 °C. In the first stage, the steels were rolled at 4 passes undergoing a total deformation of 67% in thickness and aircooled. In the second step, the steels were forged by MWL Brasil manufacturing process. After heat treatment, tests on pearlite hardness, tensile, impact, fracture toughness were performed. Microstructure was observed by optical microscopy and the austenite grain size was measured. It was observed an increasing on the yield strength (8,5%), ductility (15%), impact energy (29%), fracture toughness (33%) and hardenability by niobium and molybdenum microalloying, showing that these elements can improve the performance of railway wheels nowadays produced by MWL Brasil. / Mestrado / Materiais e Processos de Fabricação / Mestre em Engenharia Mecânica
13

A Multi-layered Routing Technique for Sensing Train Integrity and Composition

Pulugurtha, Satya Venkata Sidhi Vinayak, Atragadda, Kishore Kumar January 2020 (has links)
This thesis deals with an approach to monitor the integrity and composition of cargo wagons withthe help of Wireless Sensor Network (WSN). The WSN is to be fully automated that does notneed any human intervention for gathering information about the composition and integrity ofcargo trains, which are the most necessary factors for Cargo Logistics. The nodes are deployed inevery wagon along with the master node in the main locomotive. The master node in thelocomotive gets the information from the slave nodes placed in the cargo wagons in successivesessions. If there are any unexpected changes in the composition of the wagon, theacknowledgments to the locomotive will be terminated. This approach mainly focuses ondesigning energy-efficient as well as cost-efficient WSN. The designed WSN can accommodateto changes, which are caused by external conditions. The designed approach is also scalable. TheWSN is designed with the usage of Zigbee mesh protocol with Arduino Microcontroller as thebrain of the system that is validated and verified in the indoor, imitating the railway environment.
14

Modelling and laboratory investigations on freight wagon link suspensions with respect to vehicle-track dynamic interaction

Jönsson, Per-Anders January 2004 (has links)
The link suspension is the most prevailing suspension system for freight wagons in central and western Europe. The system design is simple and has existed for more than 100 years. However, still its characteristics are not fully understood. This thesis emphasizes freight wagon dynamics and comprises three parts: In the first part a review of freight wagon running gear is made. The different suspension systems are described and their advantages and disadvantages are discussed. The review covers the running gear standardized by UIC and the conventional so-called three-piece bogie. Additionally five improved three-piece bogies and twelve novel running gear designs are presented. The second part focuses on the lateral force-displacement characteristics in the link suspension. Results from stationary measurements on freight wagons and laboratory tests of the link suspension characteristics are presented. To improve understanding of the various mechanisms and phenomena in link suspension systems a simulation model is developed. Link suspension systems have strongly nonlinear characteristics including a hysteresis loop. The loop exhibits usually three characteristic sections with different tangential stiffnesses. The actual contact geometry of the links and end bearings has a significant influence on the characteristics. By wear in ordinary service - as well as by geometric tolerances on new components - the contact geometry may deviate considerably from nominal geometry. Further, it seems that elastic deformation in the contact surfaces has considerable effects on the suspension characteristics, in particular on the initial rolling stiffness for small displacements. Also, flexibilities in links and end bearings influence the characteristics. It is also observed that new components after a short period of dynamic testing can exhibit a very low amount of energy dissipation, a phenomenon that is also indicated in some stationary measurements on wagons. To summarize the second part, it appears that the link suspension characteristics are very sensitive to several factors being hard to control in the real world of freight wagon operations. The various stiffnesses and hysteresis loops have a considerable variation and may have a strong influence on the ride qualities of vehicles. As long as the characteristics can not be controlled within closer limits than found in this study, there is a strong need for sensitivity analysis to be made, both in predictive multibody simulations of vehicle dynamics, as well as in verification and acceptance tests. In the third part a study on the possibility to improve ride qualities of freight wagons with link suspensions is presented. Parametric studies with multibody dynamic simulations on freight wagons equipped with link-suspension bogies are performed. The effect of supplementary friction and hydraulic damping is investigated under various running conditions: speed, loading, tangent and curved track, wheel-rail contact geometry, track gauge and track irregularities. Substantial improvements of the lateral running behaviour of wagons with link suspension bogies can be achieved - both at ordinary speeds and at increased speeds - by using a proper combination of supplementary hydraulic dampers. Speeds up to 160 km/h could be realistic.
15

Modelling of sustainable empty-wagon allocation at Green Cargo

Hansson, David January 2024 (has links)
The Swedish railway industry faces a predicted increase in demand, a demand shift in each railway product, new noise regulation, and the problem with attaining the right personnel. This creates new operating conditions that railway operators must adapt to. The planning process for allocating empty-wagons from one geographical area to another to fulfill customer demand is manually performed by three experienced Wagon Managers after the discontinuation of a fully automatic system called New VADIS. Green Cargo needs to streamline operations through a standardized empty-wagon allocation process to increase delivery precision, the utilization of the wagon fleet, and to promote cost-efficiency. The thesis will evaluate Green Cargo’s usage of wagons, provide a framework for how to standardize the allocation process, discuss benefits of wagon fleet rationalization, and expand upon the current method to eliminate flaws and internal waste. Literature reviews relating to the New VADIS project, intermodal load unit assignment, and transport fleet standardization were reviewed to provide the theoretical basis of the study. An evaluation of current KPIs resulted in the introduction of the Wagon Fleet Scorecard. Interviews with representatives from the Customer Service and Operations Center departments at Green Cargo formed the basis for necessary operative conditions needed to ensure the success of a future automatic allocation system. An attempt at solving the intermodal demand translation flaw of New VADIS was done through a new mixed-integer-linear programming optimization model for optimal loading of load units on ten intermodal wagon types. The model was evaluated on real-life production data from three intermodal terminals resulting in a significantly better assignment compared to the manual process, with an 11.26% shorter cumulative train length and 10.44% less loaded wagons. An indirect effect was the reduction of the cumulative tare weight of the departing loaded wagons with 11.49%. A new standardized process is presented that includes an operative implementation of the mathematical model using a common Visual Loading Plan. Furthermore, new allocation principles were formulated to maximize wagon capacity and fleet utilization as well as minimize allocation costs. The results indicate benefits towards Green Cargo’s continuous work with sustainable business practices. The proposed process results in a 1.5% reduction of Green Cargo’s total annual Scope 2 CO2 emissions through reduced energy consumption. It gives potential for extra revenue and reduces lean wastes from overproduction, unnecessary transports, extra processing, and waiting by providing better utilization of train capacities. It also results in enhanced social sustainability during loading operations at terminals by decreasing risk of human error, decreasing risks of wagon derailment, and by providing better conditions for terminal personnel to ensure proper load safety. / Den svenska järnvägsindustrin står inför en förutspådd efterfrågansökning, en efterfrågeförskjutning av varje järnvägsprodukt, ny bullerreglering och problem med att anställa personal med rätt kompetens. Detta skapar nya operativa förutsättningar som svenska järnvägsoperatörer måste anpassa sig till. Planeringsprocessen för att allokera tomma vagnar från ett överskottsområde till ett underskottsområde för att realisera kunders transportbehov utförs manuellt av tre erfarna Vagnledare, efter att det automatiserade systemet Nya VADIS avvecklades. Green Cargo behöver effektivisera verksamheten genom en standardiserad vagnförsörjningsprocess för att öka leveransprecisionen, nyttjandet av vagnsflottan och för att främja kostnadseffektivitet. Examensarbetet utvärderar Green Cargos användning av vagnar, tillhandahåller ett ramverk för hur vagnförsörjningsprocessen kan standardiseras, diskuterar fördelarna med en rationalisering av vagnflottan samt utökar den nuvarande metoden för att eliminera brister och internt slöseri. Litteraturgenomgångar relaterade till Nya VADIS-projektet, optimal lastning av intermodala lastbärare och standardisering av vagnflottan utfördes för att ge den teoretiska grunden för examensarbetet. En utvärdering av aktuella nyckeltal resulterade i skapandet av ett Wagon Fleet Scorecard. Intervjuer med representanter från avdelningarna Kundservice och Driftcenter på Green Cargo utgjorde grunden för nödvändiga operativa förutsättningar för att säkerställa framgången för ett framtida automatiskt vagnförsörjningssystem. Ett försök att lösa bristerna i den intermodal efterfrågeöversättningen i Nya VADIS genomfördes genom en ny linjär heltalsoptimeringsmodell för optimal lastning av lastbärare på tio intermodala vagntyper. Modellen utvärderades på verkliga produktionsdata från tre intermodala terminaler vilket resulterade i en betydligt mer optimal lastning jämfört med den manuella processen, med 11,26 % kortare ackumulerad tåglängd och 10,44 % färre lastade vagnar. En indirekt effekt var minskningen av den ackumulerade egenvikten av de avgående lastade vagnarna med 11,49 %. En ny standardiserad process presenteras som inkluderar en operativ implementering av den matematiska modellen med hjälp av en gemensam Visual Loading Plan. Vidare formulerades nya vagnstyrningsprinciper för att maximera nyttjandet av vagnars kapacitet, hela vagnflottans nyttjande samt minimera allokeringskostnaderna. Resultaten indikerar fördelar för Green Cargos kontinuerliga arbete med hållbara affärsmetoder. Den föreslagna processen innebär en 1,5 % minskning av Green Cargos totala årliga Scope 2 CO2 utsläpp genom minskad energiförbrukning. Det ger potential för extra intäkter och minskar lean slöserierna överproduktion, onödiga transporter, överarbete och väntan genom bättre nyttjande av tågkapaciteten. Det resulterar även i förbättrad social hållbarhet under lastning vid terminaler genom att minska risken för mänskliga fel, minska riskerna för urspårning av vagnar samt skapa bättre förutsättningar för terminalpersonal att säkerställa god lastsäkring.
16

Velkoobjemový překládací vůz se šnekovým dopravníkem / Large-loading wagon with a screw conveyor

Peterka, Jaroslav January 2014 (has links)
This thesis deals with analysis of constructional solution of large-loading wagons used nowadays. In the first part of this thesis is my own construction design of large-loading wagon, furthermore there is a design of screw conveyor. In the following part stress strain analysis of the chassis of large-loading wagon was made using the finite element method. On the basis of these results were suggested modifications of the chassis. Finally the stress strain analysis of the adapted chassis was made. Attachments of the thesis include deformation results of the chassis and design documentation of the large-loading wagon. This thesis was created in cooperation with ZDT spol. s.r.o. Nové Veselí.
17

Vliv jednotlivých komponent směsných krmných dávek u krmných míchacích vozů (bez vybírací frézy) na přesnost nakládek

JENŠÍ, Lukáš January 2016 (has links)
The diploma thesis entitled The effect of individual components of mixed feed rations in the mixer feeder wagon (without a cutter) on the accuracy of loading is divided into two separate parts. In the first (theoretical) part, the issue of livestock together with preparation and distribution of feed with the mixing feeder wagons are analyzed. The second (practical) part of my work is focused on specific selection of a mixing feeder truck, diet components characteristic and way of their loading including evaluation of their loading accuracy. The main objective of the thesis is to specify evaluation of loading accuracy of each component in the mixed feed rations of a mixing feeder wagon in the selected agricultural companies that specialize in milk and meat production.
18

Preciznost nakládky komponent směsné krmné dávky u samojízdného míchacího krmného vozu

HORÁČEK, Adam January 2018 (has links)
The diploma thesis deals with the accuracy of loading individual components of mixed feed dose into a self-propelled mixing feed wagon using a milling cutter. The theoretical part of the thesis defines the mixed feed used for cattle breeding, then the selected world leading producers of self-propelled mixing feed wagons are listed and finally the current technological trends and innovations in this field. The practical part is firstly focused on selecting a particular company equipped with a self-propelled mixing wagon with a programmable weight calculator and a computer program. Secondly, the characteristics of feed rations and the average dairy production of dairy groups in the selected holding is mentioned. The main aim is to compare the ratio of the actually loaded weights with the required weights in the individual feed ration components for the groups of production dairy cows.
19

Přesnost nakládky do závěsného vertikálního míchacího krmného vozu

KADLEC, Ondřej January 2018 (has links)
The theoretical part features an overview of the historical development of dairy cows feeding and introduces currently used trends in feeding. This part also outlines basic technologies in the production of roughage and describes modern feed distribution machinery. The practical part evaluates the accuracy of loading of individual components and the total weight of a feed ration loaded into a vertical suspension mixer feeder wagon by a front-end loader tractor. The observation was carried out at Mr. Kadlec's family farm in Velký Bor near Netolice and lasted four months. During this period, the actual weight of loaded components (grass-clover haylage, maize silage, grains meal) was being monitored daily. The evaluation came to a conclusion that grass-clover haylage stored in bales is loaded with a greater accuracy than maize silage stored in a clamp silo.
20

Propriedades mecânicas e micromecanismos de fratura de corpos-de-prova usinados de rodas ferroviárias fundidas e forjadas / Mechanical properties and fracture micromechanisms of machined specimens from the cast and forged railway wheels

Queiroz, Syme Regina Souza 20 August 2018 (has links)
Orientador: Itamar Ferreira / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-20T17:14:11Z (GMT). No. of bitstreams: 1 Queiroz_SymeReginaSouza_D.pdf: 5101982 bytes, checksum: 1143c4b43c52ed713ed719367ce07ead (MD5) Previous issue date: 2012 / Resumo: A tendência mundial das estradas de ferro é utilizar carga elevada por vagão no transporte de produtos e alta velocidade no setor de passageiros. Em ambas as situações, as rodas ferroviárias são muito solicitadas mecanicamente e, em função disso, as propriedades mecânicas dessas rodas devem ser rigorosamente controladas, tendo em vista que as principais causas de acidentes envolvendo trincas nas rodas, ou a retirada da roda antes do final de sua vida, estão direta ou indiretamente associadas a baixos níveis de resistência mecânica, resistência à fadiga e tenacidade à fratura. O conhecimento do comportamento mecânico das rodas ferroviárias com base nas suas propriedades mecânicas é imprescindível para o projeto de rodas ferroviárias e para o aprimoramento de seu processo de fabricação. Este trabalho tem como objetivo caracterizar e analisar a microestrutura, as propriedades mecânicas e os micromecanismos de fratura de cinco rodas ferroviárias, duas fundidas e três forjadas, a partir de corpos-de-prova usinados dos aros e discos dessas rodas. As propriedades mecânicas analisadas são as básicas (limite de escoamento, limite de resistência à tração, alongamento específico até à fratura, redução de área, dureza e energia de impacto Charpy), a resistência à fadiga e a tenacidade à fratura, de corpos-de-prova usinados das rodas ferroviárias. Além das microestruturas e das propriedades mecânicas, foram também caracterizados e analisados os micromecanismos de fratura dos corpos-de-prova dos ensaios de fadiga e impacto, por meio de microscopia eletrônica de varredura. Os resultados dos ensaios indicam, em relação aos limites de escoamento e de resistência à tração, que não houve diferenças significativas entre as rodas fundidas e forjadas analisadas. Quanto à dureza (HRC), ductilidade (alongamento específico e redução de área) e tenacidade à fratura, as rodas forjadas apresentaram valores superiores. Em relação à resistência à fadiga, uma propriedade importante no caso de rodas ferroviárias, os corpos-de-prova usinados das rodas forjadas apresentaram melhores resultados em relação às rodas fundidas. Pode-se também concluir que, tanto para as propriedades mecânicas básicas e nobres como também para os micromecanismos de fratura, os resultados obtidos são compatíveis aos encontrados na literatura especializada, validando e comprovando que a metodologia de análise pode ser utilizada para melhorar os projetos e os processos de fabricação de rodas ferroviárias de aço fundidas e forjadas / Abstract: The word wide tendency of railroads is to use high load per wagon in cargo transport and high-speed in passenger sector. In both situations, the railway wheels are very mechanically requered, and as a result, the mechanical properties of these wheels should be controlled strictly in order that the main causes of accidents involving wheels cracks, or withdrawal of the wheel before end of its life, are directly or indirectly associated with low levels of strength, fatigue resistance and fracture toughness. Knowledge of the mechanical behavior of railway wheels based on their mechanical properties is essential for the design of railway wheels and the improvement of its manufacturing process. This work aims to characterize and analyze the microstructure, mechanical properties and fracture micromechanisms of five railway wheels, two cast and three forged, from the machined specimens of the rim and web of these wheels. The analyzed mechanical properties are the basics (yield strength, tensile strength, elongation, reduction in area, hardness and Charpy impact energy) the fatigue resistance and the fracture toughness, from the specimens machined of railway wheels. In addition to the microstructures and mechanical properties were characterized and analyzed the micromechanisms of fracture of the specimens of fatigue and impact tests, using scanning electron microscopy. The test results indicate, with respect to the yield strength and tensile strength, there were no significant differences between cast and forged wheels analyzed. The hardness (HRC), ductility (elongation and reduction in area) and fracture toughness of the forged wheels showed higher values. Regarding resistance to fatigue, an important property in the case of railway wheels, the forged wheels machined specimens shown better results compared to cast wheels. One can also conclude that, for both the basic and noble mechanical properties as well as for the micromechanisms of fracture, the results are compatible with those found in the literature, validating and verifying that the method of analysis can be used to improve the castings and forgings steel railway wheels and manufacturing processes and projects / Doutorado / Materiais e Processos de Fabricação / Doutora em Engenharia Mecânica

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