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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.
1531

Utilization of a tailormade condition monitoring device for third party motors

Grahn, Pontus January 2018 (has links)
Our society moves towards digitalization and the industry is not an exception. Siemenshas developed a wireless condition monitoring device called Simotics Connect in order tohelp them to move forward in the world of digitalization. The Simotics Connect has threeinbuilt sensors. One for temperature, one for vibrations and one for magnetic flux density,a product that is new in the market. This master thesis has investigated its usability forthird party motors, which has not been done.Four areas were investigated, the status in the current market, creating a motorgeometry estimation based on nameplate data, presenting a temperature model to calculatea motor’s cross section temperature and, finally, proposed a stator current model using themagnetic field measurement.Market research has shown that a space for the Simotics Connect to thrive in mostdefinitely exists.The motor geometry estimation, that is based on preliminary electromagnetic sizing,creates a digital twin for the motor that has sufficient accuracy as a tool when calculatinge.g. temperature calculations but lacks accuracy for more advanced and sensitivecalculations e.g for magnetic flux density measurement usability.The temperature model that is presented shows great accuracy when calculating thecross section temperature in the stator but the accuracy decreases for the cross sectiontemperature in the rotor.A stator current model is proposed using a proportional relationship between themagnetic flux density and stator current. The results indicates a linear relationship, thoughusing the digital twin to calculate the proportional constant were concluded to not beaccurate enough. / Sammhället rör sig idag mot digitalisering och industrin är ej ett undantag. Siemens harutvecklat en trådlös underhållsmätare kallad Simotics Connect för att hjälpa dem strävamot en värld inom digitalisering. Simotics Connect hat tre inbyggda sensorer. En för temperatur,en för vibrationer och en för magnetisk flödestäthet, vilket är nytt på marknaden.Detta masterprojekt har undersökt användningen av Simotics Connect för tredjepartsmotorer,vilket ej har gjorts tidigare.Fyra områden undersöktes, statusen på den nuvarande marknaden, en motorgeometriuppskattningmodellbaserad på namnskylsdata, en temperaturmodell för att beräknamotorns tvärsnittstemperatur och, slutligen, en statorströmmodell som använder sig avmagnetiska flödestäthetsmätningen.Marknadsundersökningen har visat att det finns ett utrymme för Simotics Connectatt blomstra inom på den nuvarande marknaden.Motorns geometriska uppskattning, som är baserad i preliminär elektromagnetiskgeometribestämning, skapar en digital tvilling av motorn som är tillräckligt noggrann föratt aggera som ett verktyg vid t.ex. temperatursberäkningar men saknar noggrannhet förmer avancerade och känsliga beräkningar, t ex för användbarhet inom magnetisk flödestäthetsberäkningar.Temperaturmodellen som presenteras visar stor noggrannhet vid beräkning av statornstvärsnittstemperatur, men noggrannheten minskar för rotorns tvärsnittstemperatur.En statorströmmodell föreslås med ett proportionellt förhållande mellan magnetflödesdensitetenoch statorströmmen. Resultaten indikerar ett linjärt förhållande, men användandetav den digitala tvillingen för att beräkna proportionell konstant konstateras attinte vara tillräckligt noggrann metod.
1532

Infuence of the modelling of truss joints made of hollow tube sections in finite element models / Inverkan av modelleringen av fackverksleder uppbyggda av ihåliga rör proler i nita elementmetoden

Lucassen, Mattheüs January 2019 (has links)
Several boom segments form the crane boom. These segments are often truss structures formed out of circular hollow sections, which are welded together forming the truss joints. A adequate modelling of these truss joints is very important for operational strength and life. Due to the large boom sizes, efficient models are used in the finite element method, generally built of beam elements. These models have problems capturing the proper bending moments working in the truss joints. This is caused by a insufficient portrayal of the joint stiffness. In the literature several modelling techniques with beam elements are proposed, which capture the joint stiffness better. These different modelling methods are implemented in a parametric boom section and compared with a shell element FE model. From this comparison the most appropriate modelling method is selected, which improve the portrayal of internal loads and nominal stresses. With these improved nominal stress values, it is investigated to implement a different fatigue assessment. The structural stress can be calculated from the nominal stress in combination with stress concentration factor (SCF) equations. To implement the structural stress method as fatigue assessment, several modelling and extrapolation methods have been compared. Which lead to a method for evaluating the structural stress in a efficient matter. This method is compared with existing SCF K truss joint equations, from which a new set of SCF equations is derived. These equations are constructed from a larger dataset, hold a wider validity range and fit better with the FE models. When applying these SCF equations with the improved beam modelling method in a boom section, the structural stress is not adequately captured. This is caused by unsymmetrical stressed braces in the K truss joints. Both the modelling methods and SCF equations account for uniformly stressed braces forming the truss joints. More research needs to be conducted to this uneven behaviour. If the structural stress method needs to be implemented with efficient FE models, submodels out of shell elements combined with beam elements are recommended. For fatigue evaluation with the nominal stress method, beam models which account for the local joint flexibility give sufficient realistic results. / Flera kranarmsegment bildar kranarmen. Dessa segment är ofta fackverk utformade av cirkulära ihåliga profiler, som är sammansvetsade och bildar fackverkslederna. En ordentlig modellering av dessa fackförband är mycket viktig för dess driftsstyrka och livslängd. På grund av storleken används finita elementmetoden, vanligtvis uppbyggt av balkelement. Dessa modeller har problem med att beräkna de korrekta böjmomenten som uppstår i fackverkslederna. Detta orsakas av en otillräcklig beskrivning av ledstyvheten. I litteraturen föreslås flera modelleringstekniker med balkelement som tar hänsyn till ledens styvhet bättre. Dessa olika modelleringsmetoder implementeras i en parametrisk kranarmsektion och jämförs med en FE-modell med skalelement. Med denna jämförelse väljs den mest lämpliga modelleringsmetoden, vilket bör förbättra skildringen av interna belastningar och nominella spänningar. Med dessa förbättrade nominella spänningsvärden, undersöks det att genomföra en annan utmattningsbedömning. Den strukturella spänningen kan beräknas utifrån den nominella spänningen i kombination med spänningskoncentrationsfaktor- (SCF) ekvationerna. För att implementera strukturella spänningsmetoden som utmattningsbedömning, har flera modellerings- och extrapoleringsmetoder jämförts. Detta leder till en metod för att utvärdera den strukturella spänningen effektivt. Denna metod jämförs med befintliga SCF-ekvationer, från vilka en ny uppsättning SCF-ekvationer härleds. Dessa ekvationer är konstruerade från en större datauppsättning, har ett bredare giltighetsområde och passar bättre med FE-modellerna. När man applicerar dessa SCF-ekvationer med den förbättrade balkmodelleringsmetoden i en kranarmsektion, uppsamlas strukturella spänningar inte tillräckligt, detta orsakas av ojämna spänningar i diagonalelementen i fackverkslederna. Både modelleringsmetoderna och SCF-ekvationerna tar hänsyn till jämnt spända diagonalelement som uppstår i fackverkslederna. Mer forskning bör göras över detta ojämna beteende. Om den strukturella spänningsmetoden måste implementeras med effektiva FE-modeller, rekommenderas undermodeller av skalelement kombinerade med balkelement. För utmattningsutvärdering med den nominella spänningsmetoden, ger balkmodeller som tar hänsyn till den lokala ledflexibiliteten tillräckligt realistiska resultat.
1533

Reactivity Coefficients In A Thorium Oxide Fuelled, Heavy Water Moderated And Cooled Reactor (Part A); Validity of Bragg Stopping Cross-Section Additivity Rule For SiC (Part B)

Ghoniem, Nasr. M. 08 1900 (has links)
<p> Part A Abstract </p> <p> Temperature coefficients of reactivity for an 37-element reference design of a thorium oxide fuelled, heavy water moderated and cooled reactor, are calculated. The physical processes which determine magnitude and sign of the coefficients are identified and discussed. Results are given for fresh fuel containing equilibrium concentrations of the fission product Xe-135 and with boron control in the moderator. Results are. also -given for fresh fuel with the equilibrium concentration of Xe-135 but without boron contorl for fuel with an exposue of 1.513 n/k barn and for fuel with an exposure of 3.13 n/k barn; each containing appropriate concentrations of 50 separate nuclides and one-pseudo fission product. The fuel temperature coefficient of reactivity is negative for all the cases studied, while the coolant temperature coefficient of reactivity is positive for all the cases studied. The void effect is an increase in reactivity for all cases studied. </p> ////////////////////// <p> Part B Abstract </p> <p> This work has been done with the purpose of studying the validity of Bragg Kleeman rule which states that for combinations of elements, the atomic stopping cross-sections are additive. The validity of Bragg Kleeman rule for low energy He ions has not been conclusively tested for solids. In this work, the comparison with the experimental stopping power of SiC with the additive stopping powers of Si and C has been made experimentally. </p> <p> A thick target technique in the experimental evaluation of the stopping powers is used. This method has some simplicity over the thin target techniques. </p> <p> A calibration of the McMaster University Van-de Graff accelerator was done. Experiments were conducted later using the calibration curves produced. </p> <p> The report contains a brief account on different sources of errors due to the Van-de-Graff accelerator calibration and due to stopping power experiments. </p> / Thesis / Doctor of Philosophy (PhD)
1534

Исследование многоэтажных рамных каркасов с двутаврами с гофрированными стенками : магистерская диссертация / Investigation of multi-storey frame structures consisted of I-sections with corrugated webs

Баязитова, Ю. А., Bayazitova, Yu. A. January 2020 (has links)
Работа посвящена изучению работы сварных двутавров с гофрированной стенкой в качестве элементов многоэтажных рамных каркасов различного назначения. Проанализированы существующие практические решения таких конструкций, обобщены теоретические подходы и методики расчета изгибаемых и внецентренно-сжатых элементов с гофрированной стенкой. Приведен пример численного расчета многоэтажного рамного каркаса, состоящего из ригелей и колонн с гофрированными стенками. Разработаны узлы крепления элементов каркаса друг к другу и к смежным конструкциям. В рамках исследования установлено, что применение сварных двутавров с гофрированной стенкой позволяет снизить металлоемкость реализации решения как для ригелей, так и для колонн многоэтажных рам зданий без снижения требуемой несущей способности и эксплуатационной надежности конструкции. / Present work is devoted to the study of the operation of welded I-sections with a corrugated web as elements of multi-storey frame structures for various purposes. The existing practical solutions for such structures are analyzed, theoretical approaches and methods for calculating of bending and eccentrically compressed elements with a corrugated web are generalized. An example of a numerical calculation of a multi-storey frame structure consisting of girders and columns with corrugated webs is given. The joints for fastening the frame elements to each other and to adjacent structures have been developed. Within the framework of the study, it was found that the use of welded I-sections with a corrugated webs makes it possible to reduce the metal consumption of the solution as for girders and as columns of multi-storey building frames without reducing the required bearing capacity and operational reliability of the structure.
1535

Большепролетные рамные конструкции промышленных зданий из сварных двутавров с гофрированными стенками переменного сечения : магистерская диссертация / Large-span frame structures of industrial buildings from welded I-beams with corrugated walls of variable cross section

Уточкина, Д. А., Utochkina, D. A. January 2023 (has links)
Были получены результаты, которые обосновывают эффективность использования рамных каркасных конструкций из сварных двутавров переменного сечения с гофрированными стенками в строительстве большепролетных промышленных зданий. / Results were obtained that substantiate the effectiveness of the use of frame frame structures made of welded I-beams of variable cross section with corrugated walls in the construction of large-span industrial buildings.
1536

PEREGRINATION: A MUSICAL SKETCH OF EUROPE IN FOUR MOVEMENTS

Schellhas, Daniel H. 26 March 2007 (has links)
No description available.
1537

MITIGATION of BACKGROUNDS for the LARGE UNDERGROUND XENON DARK MATTER EXPERIMENT

Lee, Chang 03 June 2015 (has links)
No description available.
1538

The Impact of Sexist Rhetoric on Women's Participation in News Comments Sections

Poland, Bailey 18 August 2017 (has links)
No description available.
1539

Effect of Convection Associated with Cross-section Change during Directional Solidification of Binary Alloys on Dendritic Array Morphology and Macrosegregation

Ghods, Masoud 17 July 2017 (has links)
No description available.
1540

Influence Of Cross-Section Change During Directional Solidification On Dendrite Morphology, Macrosegregation And Defect Formation In Pb-6 wt Sb Alloy

Lacdao, Claudine 25 August 2017 (has links)
No description available.

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