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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.
191

RMS capacity utilisation: product family and supply chain

Abdi, M. Reza, Labib, A.W. 09 June 2016 (has links)
Yes / The paper contributes to development of RMS through linkage with external stakeholders such as customers and suppliers of parts/raw materials to handle demand fluctuations that necessitate information sharing across the supply chain tiers. RMS is developed as an integrated supply chain hub for adjusting production capacity using a hybrid methodology of decision trees and Markov analysis. The proposed Markov Chain model contributes to evaluate and monitor system reconfigurations required due to changes of product families with consideration of the product life cycles. The simulation findings indicate that system productivity and financial performance in terms of the profit contribution of product-process allocation will vary over configuration stages. The capacity of an RMS with limited product families and/or limited model variants becomes gradually inoperative whilst approaching upcoming configuration stages due to the end of product life cycles. As a result, reconfiguration preparation is suggested quite before ending life cycle of an existing product in process, for switching from a product family to a new/another product family in the production range, subject to its present demand. The proposed model is illustrated through a simplified case study with given product families and transition probabilities.
192

Těhlice vozu kategorie Formule SAE / Wheel Hub Carrier for car of Formule SAE

Vymazal, Roman January 2008 (has links)
This thesis deals with a mechanical design of a front wheel hub carrier and a rear wheel hub carrier for Formula SAE. It contains the main design as well as the control of a screw and computer loading solve process. The essential objectives of this thesis are the optimization of the mechanical design and following manufacturing of desired parts and their practical usage in a Formula SAE race car.
193

Design, comparison and experimental evaluation of non-overlap winding radial flux permanent magnet hub drives for electric vehicles

Rix, Arnold Johan 03 1900 (has links)
Thesis (PhD (Electrical and Electronic Engineering))--University of Stellenbosch, 2011. / ENGLISH ABSTRACT: The focus of this thesis is on the optimal design, control and evaluation of 3-phase permanent magnet radial flux synchronous machines with non-overlapping, concentrated-coil, double layer stator windings for EV hub drive applications. A simple analytical method is developed that can be used as a first design tool. The method uses and predicts the MMF harmonic content for a certain pole-slot combination as well as the harmonic content for the air gap permeance function. These harmonics are then used to calculate the torque and torque ripple of machines with large stator slot openings and surface mounted permanent magnets. A different approach to calculate the iron, stator copper eddy current and magnet losses is presented. This method specifically looks at the machine during field weakening operation when the flux paths are changing in the machine. Flux density information throughout the machine is extracted from a series of static FE solutions, to calculate the losses and to combine this with an empirical formula. Some machine topology choices are compared for use as hub drives in small electric ve- hicles. The parameters that influence the machine design are discussed and evaluated after a multidimensional design optimization is done and an efficient control algorithm is imple- mented. The algorithm works through the entire operating speed range and make use of, automatically generated, 2D look up tables to determine the correct current reference. A stator lamination design is proposed, that combines the use of rectangular preformed coils and semi-closed stator slots. Two prototype machines, one with a good winding factor and the other with a low winding factor, are built and compared. The manufacturing and testing of the two prototype machines are described and shown in detail. / AFRIKAANSE OPSOMMING: Die fokus van hierdie tesis is op die optimale ontwerp, beheer en evaluasie van 3-fase per- manent magneet radiale vloed sinchroon masjiene met nie-oorvleuelende, gekonsentreerde, dubbel laag stator wikkelinge vir EV hub motor toepassings. ’n Eenvoudige analitiese metode is ontwikkel wat as ’n eerste ontwerp gereedskap stuk gebruik kan word. Die metode gebruik en voorspel die MMF se frekwensie inhoud vir ’n sekere pool-gleuf kombinasie sowel as die frekwensie inhoud vir die lug spleet permeansie funksie. Hierdie frekwensie inhoud word dan gebruik om die draaimoment en draaimoment riffel van masjiene met groot stator gleuf openinge en oppervlak magnete te voorspel. ’n Ander benadering om yster, stator koper werwel stroom en magneet verliese te bepaal word voorgestel. Hierdie metode kyk spesifiek na masjiene onder veld verswakking beheer wanneer die vloed paaie verander vanaf die normale. Die vloeddigtheid, regdeur die masjien, word verkry deur om van ’n reeks statiese eindige element oplossings gebruik te maak en dit te kombineer met ’n empiriese verliesberekening. Die parameters wat die masjienontwerp beïnvloed, word bespreek en geëvalueer na ’n mul- tidimensionele ontwerp optimering gedoen is en ’n effektiewe beheer algoritme geïmplimen- teer is. Die algoritme werk vir enige spoed en is gebaseer op die outomaties gegenereerde 2D opsoek tabelle wat die korrekte stroomverwysing gee. ’n Stator laminasie ontwerp word voorgestel wat die gebruik van vooraf vervaardigde spoele en gedeeltelik toe stator gleuwe moontlik maak. Twee prototipe masjiene, een met ’n goeie windingsfaktor en een met ’n swakker windingsfaktor is gebou en vergelyk. Die ver- vaardiging en toetsing van die twee prototipe masjiene word in detail beskryf en gewys.
194

Architektūrinė-urbanistinė Klaipėdos miesto stočių terminalo koncepcija / Urban-architectural conception of the terminal station in Klaipeda

Tamkvaitytė, Otilija 22 June 2010 (has links)
Baigiamajame magistro darbe nagrinėjama Klaipėdos miesto istorinio centro prieigų erdvinės struktūros ir kompozicijos tobulinimo principai. Pagrindinis darbo tikslas – teritorijos, esančios šalia transporto mazgo ir geležinkelio linijos, potencialo išryškinimas miesto kontekste bei artikuliuotos urbanistinės struktūros sukūrimas. Identifikuojami vertingi ir nevertingi miesto plano struktūros elementai, jų poveikis nagrinėjamai teritorijai. Sprendžiamos susisiekimo, erdvinio karkaso formavimo problemos. Vykdoma naujų traukos objektų paieška. Remiantis atlikta urbanistine analize, pasaulinių analogų tyrimu, pateikiamas galimas plėtros modelis. Akcentuojant transporto mazgą, geležinkelio liniją, upės pakrantę ir svarbiausias trasas, kompozicinėmis priemonėmis pateikiama teritorijos urbanistinė koncepcija ir detalizuojamo komplekso architektūrinė išraiška. Siūlomas naujas visuomeninis miesto traukos centras – stočių terminalas, – kuris diktuoja teritorijos užstatymo paskirtį, susisiekimo ir viešųjų erdvių organizavimo galimybes. Detalizuojamas urbanistinis-architektūrinis akcentas – stočių terminalas. Baigiamojo darbo rezultatas - nauja nagrinėjamos teritorijos urbanistinės struktūros, įprasminančios Klaipėdos miesto istorinio centro prieigas, koncepcija. Darbo pabaigoje pateikiamos išvados ir rekomendacijos. / The thesis examines the accesses of historical center of Klaipeda city, its spatial structure and development of the new principles of composition. The main aim of the work is to articulate the urban structure of the territory situated near the transport hub, railway lines and to highlight its potential of urban context in Klaipėda‘s city.Identifying useful and lightweight structural elements of the urban plan and its impact on the site, forming spatial structure and transportation problems, ongoing search for new attractions highlights the possibilities of concept. The possible development model derives from the urban analysis and the global analogue of the investigation. The concept, its composite means of urban areas and the architectural idea is based on the main elements such as transport hub, the railway lines, river coastline and the main roads. The proposed new civic center of gravity - the station terminal - applies opportunities to organize the use of the transportation and public spaces in the territory. The urban-architectural accent - the station terminal - is detailed. Final result is a concept of a new urban structure of the site, which represents the access to Klaipeda city's historical center in the new point of wiev. In the end the conclusions and recommendations.
195

Sea Level Compensation System for Wave Energy Converters

Castellucci, Valeria January 2016 (has links)
The wave energy converter developed at Uppsala University consists of a linear generator at the seabed driven by the motion of a buoy on the water surface. The energy absorbed by the generator is negatively affected by variations of the mean sea level caused by tides, changes in barometric pressure, strong winds, and storm surges. The work presented in this doctoral thesis aims to investigate the losses in energy absorption for the present generation wave energy converter due to the effect of sea level variations, mainly caused by tides. This goal is achieved through the modeling of the interaction between the waves and the point absorber. An estimation of the economic cost that these losses imply is also made. Moreover, solutions on how to reduce the negative effect of sea level variations are discussed. To this end, two compensation systems which adjust the length of the connection line between the floater and the generator are designed, and the first prototype is built and tested near the Lysekil research site. The theoretical study assesses the energy loss at about 400 coastal points all over the world and for one generator design. The results highlight critical locations where the need for a compensation system appears compelling. The same hydro-mechanic model is applied to a specific site, the Wave Hub on the west coast of Cornwall, United Kingdom, where the energy loss is calculated to be about 53 %. The experimental work led to the construction of a buoy equipped with a screw jack together with its control, measurement and communication systems. The prototype, suitable for sea level variations of small range, is tested and its performance evaluated. A second prototype, suitable for high range variations, is also designed and is currently under construction. One main conclusion is that including the compensation systems in the design of the wave energy converter will increase the competitiveness of the technology from an economic point of view by decreasing its cost per kWh. The need for a cost-effective wave energy converter with increased survivability emphasizes the importance of the presented research and its future development.
196

Untersuchungen zur Ermüdungsfestigkeit von Pressverbindungen / Investigations on fatigue strength of shrink fits

Hofmann, Stefan 08 March 2017 (has links) (PDF)
Pressverbindungen gehören zu den klassischen Maschinenelementen und werden insbesondere in der Antriebstechnik häufig eingesetzt. Zur sicheren und zugleich wirtschaftlichen Auslegung derartiger Verbindungen unter zyklischen Lasten fehlen generell gültige sowie abgesicherte normative Vorgaben bzw. Richtlinien für den Anwender. Insbesondere ist dies dann zutreffend, wenn Geometrien vorkommen, für welche keine Tabellen- bzw. Erfahrungswerte existieren. In dieser Arbeit werden ausführliche experimentelle Untersuchungen zur Ermüdungsfestigkeit von Pressverbindungen einer Standardgeometrie vorgestellt. Im Fokus der Untersuchungen steht die Dauer-, Zeit- und Betriebsfestigkeit der biege- sowie torsionsbelasteten Verbindung. Auf Basis der erzielten Festigkeiten und Lebensdauerwerte erfolgt die Ableitung normspezifischer Kennwerte für die Praxis. Weiterhin steht die Übertragung der erzielten Ergebnisse auf andere Pressverbindungs-Geometrien, wie beispielsweise die Verbindung mit Wellenabsatz, im Vordergrund. Hierbei wird das Verhalten hinsichtlich der Kerbwirkung im Vergleich zu gekerbten Wellen sowie zu anderen reibdauerbeanspruchten Verbindungen untersucht. Zudem erfolgt eine ausführliche Analyse simulationsspezifischer Einflussgrößen auf die Beanspruchungshöhe der Pressverbindung. Auf Grundlage dieser Erkenntnisse wird ein neues Auslegungskonzept erarbeitet und an Ergebnissen aus der Literatur gespiegelt.
197

Beitrag zur Integration eines elektrischen Einzelradantriebes in eine Landmaschine

Geißler, Mike 21 February 2017 (has links) (PDF)
Am Beispiel einer Landmaschine wurde die Integration eines dieselelektrischen Einzelradantriebes unter der Berücksichtigung der spezifischen Anforderungen nachgewiesen. Die Integration des elektrischen Antriebes in die Fahrzeugfelge führt zu einem abgeschlossenen System mit definierten Schnittstellen. Zur Umsetzung des Antriebssystems werden unterschiedliche Lösungen diskutiert und die Vorzugsvariante realisiert. Für das Antriebssystem und das Fahrzeug werden die Funktionsnachweise mittels Simulationsergebnissen, Prüfstands- und Fahrversuchen erbracht. Ebenso wird der Nutzen eines elektrischen Einzelradantriebssystems diskutiert.
198

[en] HUB LOCATION STRATEGIES FOR THE BRAZILIAN AIR TRANSPORTATION SYSTEM / [pt] ESTRATÉGIAS DE LOCALIZAÇÃO DE HUBS PARA O SISTEMA DE TRANSPORTE AÉREO BRASILEIRO

GUINA GUADALUPE SOTOMAYOR ALZAMORA 17 July 2014 (has links)
[pt] O problema de localização de hubs visa encontrar pontos de concentração de fluxo numa rede, de modo que a soma das distâncias das ligações compartilhadas entre pontos da rede seja minimizada. Neste trabalho, o problema fundamental de localização de hubs com alocação simples para o sistema de transporte aéreo brasileiro é abordado, através da identificação de hubs regionais e hubs centrais, a fim de minimizar o fluxo na rede via a resolução primeiramente de um modelo integrado. A seguir, é proposto um método heurístico de duas fases em vista de reduzir o tempo de resposta e superar a limitação de memória. Na primeira fase da heurística proposta são identificados hubs regionais via resolução do modelo da p-mediana. Utilizando os resultados da primeira fase na segunda fase, procede-se à identificação de hubs centrais resolvendo-se o modelo q-hub-mediana numa rede de aeroportos menor, porém de mesmo fluxo de passageiros. Experimentos computacionais com as duas estratégias propostas para o problema de localização de hubs são realizados, tendo como instância base o sistema de transporte aéreo brasileiro com 150 aeroportos. Para estratégia via modelo integrado é considerado um total de 24 aeroportos no sistema, com o número de hubs regionais variando de 10 a 19 e o de hubs centrais variando de 2 a 6; para a estratégia via método heurístico é considerado um total de 150 aeroportos no sistema, com o número de hubs regionais variando de 10 a 40 na primeira fase, e o de hubs centrais variando de 2 a 6, na segunda fase. Ainda, recursos gráficos são usados na visualização dos resultados obtidos. / [en] The hub location problem aims to find points of concentration in a ow network, such that the sum of the distances of the connections shared between grid points is minimized. In this work, the fundamental problem of locating hubs with simple allocation for the Brazilian air transportation system is approached, by identifying regional and central hubs, in order to minimize the network ow by solving first an integrated model. Then, a two-phase heuristic method is proposed in order to reduce the response time and overcome the memory limitation. In the first phase of the proposed heuristic the regional hubs are identifed through the resolution of the p- median model. Using the results of the first phase in the second one, the identification of central hubs is proceeded by solving a q-hub-median model in a smaller airport grid, but of the same passenger ow. Computational experiments with the two proposed strategies for the hub location problem are performed, having as basic instance the Brazilian air transportation system with 150 airports. For the integrated model strategy a total of 24 airports in the system is considered, with the number of regional hubs varying from 10 to 19 and the number of central hubs varying from 2 to 6; and for the heuristic method strategy a total of 150 airports in the system is considered, with the number of regional hubs varying from 10 to 40 in the first stage, and the number of central hubs varying from 2 to 6 in the second stage. Further, graphical features are used in the visualization of the results.
199

Arkitektonisk utformning av en lagringsplattform för Business Intelligence : En litteratur- och fallstudie riktad mot små och medelstora företag

Lundström, Adam January 2018 (has links)
BI, business intelligence, which means to collect and analyse data to inform business decisions, is a concept that has grown to be a significant part of business development. In most cases, a storage platform is necessary to provide data from the companies’ different data sources to the BI-tools. There are different ways of doing this. Some of them are by the help of a data lake, a data warehouse or a combination of both. By taking this into consideration the purpose of this study is to create an architectural design of a storage platform for small and medium-sized enterprises (SME). To be able to formulate a result which holds as high validity and reliability as possible, this study conducts both a literature and a case study. The case study has taken place at an IT service company which classifies as a SME and the working methodology has been an agile approach with scrum as reference. This method was chosen to be able to efficiently follow the customer demands.  The architecture provided consists of a combination of a data hub, which acts as a data lake, and a data warehouse. The data hub differs from a data lake by harmonizing and indexing data, which makes it easier to handle. Regarding the intension of the data warehouse, it is to yield relevant and processed data to BI-tools. The architecture design of the platform that has been developed in this study cannot be said to be applicable by all companies. Instead, it can be a basis for companies that are thinking about creating a data platform. / BI, Business intelligence, vilket betyder att samla och analysera data som beslutsstöd, har växt till att vara en betydande del inom företagsutveckling. För att möjliggöra för BI krävs ofta att en datalagringsplattform tillhandahåller data från verksamhetens datakällor. Det finns olika sätt att göra detta, men några av dem är med hjälp av en datasjö, ett datalager eller en kombination av båda. Mot bakgrund av detta, har den här studien syftat till att framställa en övergripande arkitektur som lämpar sig till små  och medelstora företag (SMF). För att frambringa ett resultat med så  hög validitet och reliabilitet som mö jligt baseras studien på  både en litteraturstudie och en fallstudie. Fallstudien har genomförts på  ett IT-konsultföretag som klassas som SMF och arbetsmetodiken har varit agil och baserats pa  scrum. Denna metod valdes för att på  ett effektivt sä tt säkerställa att kundens krav uppfylldes. Den arkitektur som föreslagits är en kombination mellan en datahubb, vilket verkar som en datasjö , och ett datalager. Datahubben skiljer sig från datasjön eftersom den harmoniserar och indexerar data, vilket gör den enklare att hantera. Rörande datalagret, ämnar det tillgodose bearbetad och relevant data för BI-verktyg. Den övergripande arkitektur som presenteras anses inte vara applicerbar för alla verksamheter, men kan användas som en grund för verksamheter som tänker implementera en lagringsplattform.
200

Aktuoekologie krytének ve sladkovodním a půdním prostředí v interakci s houbami a jejich analýza novými mikroskopickými technikami. / Actuoecology of testate amoebae in fresh water and soil environment in enteraction with fungi and their analysis with new microscopic techniques

Burdíková, Zuzana January 2012 (has links)
4 Abstract The present thesis focuses on testate amoebae (TA) and their relationship to their natural environment, as well as on relevant microscopic imaging methods. The bulk of the data has been published in original scientific papers and is compiled into three separate chapters (Pt I, Pt II and Pt III), each annotated by a brief introduction. (Pt I) The methods section is devoted to specialized microscopic techniques employed to broaden the scope of the ecological analyses. In particular, precise discrimination between live and dead individuals, biomass determination inside individual tests and a multi-modal visualization of the cytoplasm and organelles enhance the data. Laser scanning confocal microscopy and two-photon microscopy are the main imaging modalities employed to study TA morphology in detail. The data have implications for taxonomy and ecophysiology, including the use of TA as bioindicators of pollution. (Pt II) An actuoecological analysis focuses on the seasonal variability of TA species composition in a freshwater ecosystem, namely the Komo any ponds in Prague, during the course of the year. The species composition variation is correlated to simultaneously recorded limnological parameters such as temperature, pH, contamination by (heavy) metals (As, Cd, Mn, Ni, Fe, Pb), polycyclic aromatic...

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