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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.
81

Filling the gap Within Micromobility : Prototype of a Small Efficient Foldable Electric Vehicle With Long Range / Prototyp av ett litet effektivt el-fordon som kan uppnå lång räckvidd

Lien-Oscarsson, Fredrik January 2023 (has links)
Micromobility has been on the rise lately with a vast catalogue of electric vehicles reaching the market. Electric scooters, mopeds, bikes, one-wheelers and other vehicles have become the norm in everyday life. Most of these vehicles are meant to replace smaller modes of transport such as ordinary bicycles and skateboards. They are designed to complete the last part of one’s commute or for travelling shorter distances. There is; however, a gap within this segment. There is currently no electric micromobility vehicle on the market that is small and lightweight that has a long enough range to compete with ordinary two-tonne cars for longer commutes. This project aims to remedy this by presenting a solution as well as building a prototype of said solution. The electric vehicle that was built for this project is foldable. The design, when folded, is intended to resemble a large, rollable, suitcase. The overall size of the vehicle when folded is only 700x500x400 mm. When unfolded, it is large enough to seat one person fully enclosed. The top speed is limited to 25 km/h and the maximum range per charge is above 100 km. The prototype weighs 29 kg and is able to carry 95 kg. This thesis proves that it is possible to make small and lightweight electric vehicles that can rival traditional cars when it comes to commuting. These vehicles would reduce emissions, congestion and the need for parking space while also being a cheaper alternative for the end user. / Mikromobilitet segmentet har växt avsevärt de senaste åren. En stor samling av olika elektriska fordon så som elskotrar, mopeder, cyklar och enhjulingar, med fler, har blivit en del av vardagen. De flesta av dessa fordon är skapta för att tilryggalägga kortare sträckor. De är ämnade att ersätta cyklar eller att färdas till fots. Det finns dock ingen produkt inom det här segmentet tillgänglig på marknaden som är designad för att kunna tillryggalägga längre sträckor medans den fortfarande är liten och bärbar. Ett sådant fordon presenteras i denna avhandling som lösning på detta problem. Dessutom konstruerades en prototyp av det föreslagna fordonet för att bevisa att det är möjligt att göra små elektriska fordon med lång räckvidd. Prototypen som tillverkades i denna avhandling är vikbar, vilket gör den lätt att transportera när den inte är i bruk. Hela fordonet viks ihop till en resväska som kan dras på bakhjulen. Den har en ihopvikt storlek av 700x500x400 mm, maxhastighet på 25 km/h och väger 29 kg. Detta fordon kan fullständigt innesluta en person när den är utfälld, bära upp till 95 kg och har en räckvidd på över 100 km per laddning. Fordon likt prototypen i denna avhandling kan hjälpa till med att minska utsläpp, minska behovet av parkeringsplatser och minska stockning på vägarna. Dessutom skulle ett sådant fordon också vara mer ekonomisk för slutanvändaren när det kommer till pendling jämfört med en traditionell bil.
82

Breakdown Voltage Performances of Aluminum and Copper Conductor Wire Under Compression Stresses

Suchanek, Richard Donald, III 01 April 2016 (has links)
In the global, competitive market of energy transformation, increased operational expenses and depletion of raw materials have resulted in companies pursuing alternate materials to reduce consumer costs. In electrical applications, energy is transformed using materials with high electrical conductive properties. The conductive material used to transmit a signal is called conductor wire and is comprised of any material that has the ability to move charged particles from one point to another without propagation or delay. The conductor wire in many applications is encapsulated in epoxy resin called enamel. The enamel is the insulation system that provides necessary dielectric clearances to prevent voltage leakage. The most common form of energy transformation is the electric motor. Both copper and aluminum conductor wire are commonly used in electric motors, but copper is preferred due to thermal and electrical properties. However, there is a significant economic incentive to convert to aluminum conductor wire. Limited white papers are available comparing the performances of the two materials; the research is limited to physical and electrical performances of the raw material and does not take into considering the insulation. The conductor wire, which includes the insulation, is susceptible to damage during the manufacturing process and is an inherent risk if not fully understood. During the blocking process, the conductor wire is pushed and compressed into lamination slots. This process changes the conductor wire outer diameter to accommodate void spaces within the lamination slots. The percentage of slot area occupied by the conductor wire is known as slot fill. The higher the slot fill, the more wire occupying the available space. The higher the slot fill, the more force required to fill the slots. High slot fill motor designs provide a performance advantage with little associated cost. The more wire pressed into the slot, the higher the potential efficiency gains. However, high slot fill motors are more susceptible to damage. The study is designed to evaluate and measure the durability of aluminum and copper conductor wire under simulated compression stresses. Utilizing this information, electric motor manufacturers can push current design limits without affecting conductor wire quality and reliability.
83

Technological breakthroughs and productivity growth

Edquist, Harald January 2006 (has links)
This dissertation consists of four self-contained studies concentrating on the productivity development following major technological breakthroughs. All four studies are concerned with measurement issues of productivity. Three of the papers use a comparative historical perspective and primarily focus on some of the differences and similarities in productivity growth following each technological breakthrough. A fourth paper solely focuses on the ICT revolution and the problems associated with measuring productivity in the Swedish Radio, television and communication equipment (RTC) industry. Paper 1, Technological Breakthroughs and Productivity Growth (with Magnus Henrekson), examines productivity growth following three major technological breakthroughs: the steam power revolution, electrification and the ICT revolution. The distinction between sectors producing and sectors using the new technology is emphasized. A major finding for all breakthroughs is that there is a long lag from the time of the original invention until a substantial increase in the rate of productivity growth can be observed. There is also strong evidence of rapid price decreases for steam engines, electricity, electric motors and ICT products. However, there is no persuasive direct evidence that the steam engine producing industry and electric machinery had particularly high productivity growth rates. For the ICT revolution, the highest productivity growth rates are found in ICT-producing industries. It is argued that one explanation might be that hedonic price indexes are not used for the steam engine and the electric motor. Still, it is likely that the rate of technological development has been much more rapid during the ICT revolution as compared to any of the previous breakthroughs. In paper 2, Do Hedonic Price Indexes Change History? The Case of Electrification, I investigate whether hedonic price indexing would also have large effects on measured price and productivity during electrification. The hedonic methodology is used on historical data for electric motors in Sweden in 1900–35. The results show that PPI-deflated prices for electric motors decreased by 4.8 percent per year based on hedonic price indexes. This indicates that prices decreased considerably more for electric motors compared to total manufacturing. Annual labor productivity growth in Swedish electric machinery in 1919–29 becomes 12.1 percent if the hedonic deflators are used. Thus, there is strong evidence that productivity growth in the electric motor producing industry was very high during the 1920s. In contrast to Sweden, US annual labor productivity growth was only, according to current best estimates, 4.1 percent in electric machinery compared to 5.3 percent in manufacturing in 1919–29. However, hedonic price indexes were not used to calculate US productivity. Finally, it is shown that the price decreases for electric motors in the 1920s were not on par with the price decreases for ICT-equipment in the 1990s, even if hedonic indexing is used in both cases. Paper 3, Parallel Development? Productivity Growth Following Electrification and the ICT revolution, compares labor productivity growth and the contribution to labor productivity growth in Swedish manufacturing during electrification and the ICT revolution. The paper distinguishes between technology-producing, intensive and less intensive technology-using industries during these two technological breakthroughs. The results show that labor productivity growth and the overall contribution to labor productivity growth were considerably higher in technology-producing industries during the ICT revolution compared to electrification. For example, the relative contribution to labor productivity growth in manufacturing from the technology-producing industry was 3.4 percent in 1920–30 compared to 34.4 percent in 1993–2003. On the other hand, the relative contribution to aggregate labor productivity growth was considerably higher in intensive technology-using manufacturing industries during electrification. These findings have an important policy implication, namely that it is much more important how productivity is measured for ICT products in the 1990s than for electric motors in the 1920s. Paper 4, The Swedish ICT Miracle: Myth or Reality?, investigates productivity development in Sweden in the 1990s. The results show that much of the recorded Swedish surge in labor productivity was due to the spectacular growth of the Radio, television and communication equipment (RTC) industry. However, the productivity growth of the RTC industry is very sensitive to value added price deflators. Unlike Sweden, the US uses hedonic price indexes for semiconductors and microprocessors which are important intermediate inputs in the RTC industry. Estimates based on the US intermediate input price deflators for semiconductors and microprocessors suggest that the productivity growth of the Swedish RTC industry during the 1990s can be questioned. This implies that the productivity growth of total manufacturing has also been overestimated. The results for Sweden are also interesting for other countries such as Finland, Ireland and South Korea, where ICT-producing industries have contributed substantially to labor productivity growth / Diss. Stockholm : Handelshögskolan, 2006 S. 1-21: introduction and summary, s. 23-194: 4 papers
84

Contribution à la modélisation prédictive des comportements hautes fréquences des moteurs de traction / Contribution to a predictive model of high frequency behaviours of traction motors

Medard, Fabien 09 March 2015 (has links)
La diminution drastique des temps de commutation des convertisseurs MLI, due aux technologies émergentes comme le SiC (Carbure de Silicium), engendre un nombre important de phénomènes hautes fréquences dans les moteurs électriques notamment des tensions inter-spires et des courants de paliers. Ces travaux portent sur l'établissement d'un modèle impédant prédictif, valable sur une large bande de fréquence, fournissant les valeurs des tensions et des courants dangereux pour les moteurs. Pour cela, une maquette à échelle réduite a été étudiée dans un premier temps pour comprendre les phénomènes et offrir un cas simplifié de modélisation. Un bobinage en circuit imprimé a été fabriqué à cet effet. Un modèle de ligne a été développé et offre des résultats satisfaisants en prenant en compte les effets dus à la montée en fréquence. La même démarche de modélisation a été adoptée dans le cas du moteur réel dans la suite des travaux. Des campagnes de mesures sur un moteur instrumenté ont permis d'observer la propagation des ondes dans le bobinage. Une bobine a également été instrumentée pour offrir un accès au potentiel de chaque spire. Un modèle présenté dans la littérature a été approfondi en proposant une méthode d'identification des paramètres à partir de quelques points de mesures. Ce modèle sert de comparaison avec le modèle prédictif établi à la fin de ces travaux. La dernière partie de ces travaux s'intéresse à la modélisation du même moteur de traction. Un modèle de ligne dont les valeurs de paramètres ont été issues de calculs analytiques ou de simulations numériques a été réalisé tout en évitant d'avoir recours à des mesures. Ce modèle a donc un comportement prédictif puisque les données d'entrées sont pour la plus grande majorité uniquement géométriques. Il donne accès aux valeurs de tensions dans le bobinage et à l'amplitude des éventuels courants de paliers. Ce modèle peut alors servir d'outil d'aide à la conception des machines électriques en montrant les conséquences des choix de géométries. / In PWM converter, emerging technologies, like Sic and GAN, tend to decrease the rise time commutation which increases the occurrence of high frequency phenomenon such as bearing currents and voltage between coils. In this thesis, we aim to develop a predictive model able to give the currents and voltages amplitudes of those parasites. To simplify the understood of the phenomenon, a mock-up was built. It consists of a winding coil in a flexible PCB which represents the wave propagation in a real winding. Therefore, a first model was developed taking into account the effects produced by an increasing frequency. The model gives good results. It will be used in the real traction motor. Measures on a modified motor allowed observing the wave propagation across the coil. Those measures results will be compared to our motor model ones. A model found in the literature has also been studied. For this model, we built a parameters identification method based on several measurement points. This model will also be a compared to our motor model. The last part of this work explains the method used to build the predictive model. A line model is used to give an access to the winding. All parameters have been found with analytical formulations or with numerical simulations to avoid the use of measures. This model gives an access to a voltage between coils and to bearings currents. It can be used during the conception of motor to predict those problems.
85

Modélisation des écoulements confinés entre un stator et un rotor ultra-rapide / Flow modeling confrined between a stator and a high-speed rotor

Antoun labib, Joseph 16 December 2016 (has links)
Le projet e-MECA : electro-Mécanique Embarquée à Compacité Améliorée, dont l’objectif est de concevoir une machine ultra compacte et ultra rapide à une puissance utile de 12Kw, trouve son application dans les véhicules mild et full hybrides. Ce type de machine présente en effet un fort potentiel de déploiement industriel en très grandes séries à des prix abordables. Pour ces machines, les pertes de charge liées aux écoulements dans le jeu constituent des enjeux essentiels pour les constructeurs. La présente étude porte sur le moyen d’identifier de ces pertes des machines électriques ultra-compactes et ultra-rapides (50 000 rpm).Cette thèse a pour objet l’étude des pertes aérauliques dans l’espace entre le rotor et le stator d’une machine électrique ultra-rapide (≈ 250 m/s) et ultra-compacte (0,5mm - 2mm d’entrefer), en cherchant à répondre aux spécifications élaborées par nos partenaires dans le cadre du projet e-MECA. / The project e-MECA: electromechanical engineering Embarked in Improved Compactness, the objective of which is to design a machine with a small gap and high speed rotor with a useful power of 12Kw, finds its application in mild and hybrid vehicle. This type of machine indeed presents a high potential in the industrial deployment in very big series to affordable prices. The losses in these machines are linked to the flow in the gap has a significant importance for the manufacturers. This study aims to identify these losses for the ultra-compact and ultrafast electric machines (50 000 rpm).This thesis is a study of the air losses in the space between the rotor and the stator of an ultra-fast electric machine (≈ 250 m/s) and ultra-compact (0,5mm - 2mm of air-gap). This study was done to meet the specifications that had been elaborated by our partners in the e-MECA project.
86

Návrh nákladního výtahu / Project of service lift

Nguyen, Huy Long Unknown Date (has links)
Task of this diploma thesis is to design service lift which is driven by unordinary mechanism using thrust chain. Main parts of this diploma are design and description of main construction parts, strength analysis and drive design.
87

Zařízení pro testování malých elektrických motorů a lineárních aktuátorů / Testing equipment for small electrical motors and linear actuators

Červínek, David January 2018 (has links)
Aktuální postup testování je příliš zdlouhavý a nepřesný, zároveň není měření některých vlastností motoru vůbec možné. Hlavním úkolem zařízení je zrychlení a zjednodušení procesu testování spolu s možností otestovat všechny vlastnosti motorů. Realizace zařízení začala definováním požadavků zákazníka, dalším krokem byla analýza daných požadavků a návrh zařízení. Následovala výroba a programovaní firmwaru spolu se softwarem. Výsledkem práce je funkční přístroj schopný automatického testování sedmi základních typů motorů, měření všech požadovaných funkcí spolu s novou možností měření počtu tiků enkodéru, periody FG signálu z řídící elektroniky BLDC motorů a napěťové úrovně těchto signálů. Dalšími rozšířeními jsou možnost uložení výsledků z uskutečněných testů pro možné budoucí využití a možnost vizualizace proudu motorem. Uživatel je tedy schopný otestovat velké množství motorů v kratším časovém úseku a zároveň se o testovaných motorech dozvědět mnohem více informací než doposud.
88

Porovnání koncepcí hybridního pohonu v režimu denního dojíždění do práce / Comparison of Hybrid Powertrain Topologies in Daily Commuting Regime

Ušiak, Michal January 2020 (has links)
The master’s thesis deals with modelling of various architectures of hybrid powertrains for three vehicle sizes in GT-SUITE and compares them in daily commuting operating mode. On top of making of the hybrid vehicle simulation models, control algorithms had to be created to manage the energy split between the internal combustion engine and the electric motor for each of the architectures. Routes to work and back were logged using the GPS and postprocessed to obtain the speed and the road grade profiles. Resulting data was used as an input in simulations of daily commuting. To compare all hybrid powertrain architectures, fuel economy and electricity consumption were evaluated for WLTP and daily commuting operating modes. Finally, the environmental impact of each topology was assessed based on an estimation of corresponding well-to-wheel emissions.
89

Design of Generalized Powertrain Model / Design of Generalized Powertrain Model

Borkovec, Tomáš January 2015 (has links)
In this work is proposed the generalized powertrain of the parallel hybrid car. The powertrain is composed from the sub-models of the power sources. Each sub-model is described by the quasi-static modeling. For given routes is computed the power demand. Based on the derived power demand, three energy management systems are tested. First system is based on heuristic rules. The second one use more sophisticated control algorithms - the optimization method. Main idea is based on minimum principle, when the control algorithm tries to minimize the cost function (fuel use, emission). The last one is based on the equivalent consumption minimization strategy.
90

Nákladní manipulační výtah / Freight Elevator

Málek, Ondřej January 2010 (has links)
This diploma thesis is dealing with rebuilding of a lift with load 1000 kg into lift with load 1500 kg. This thesis is mainly intent on dimensioning of propulsion and choosing of traction means. The frame cage of a lift is counted by MKP analysis.

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