Unconventional windings for traction motors in electric vehicles

In this dissertation, combined star-delta windings and single-layer fractional-slot distributed windings are mainly evaluated, which are incorporated within a cage-induction machine and an electrically excited synchronous machine, respectively. Both electrical machines were de-signed as prototypes for automotive applications. The combined star-polygon windings feature an increased fundamental winding factor and a decreased harmonic leakage factor. These characteristics make them suitable for traction appli-cations to increase the torque density of electrical machines, to widen the field-weakening region and to reduce the noise, vibration, and harshness (NVH). Almost every winding, in-cluding some single-layer fractional-slot distributed windings, can be connected in combined star-polygon. Due to the undesired magnetic coupling between the additional spatial harmonics generated by the winding and the low-resistance rotor circuit, the single-layer fractional-slot distributed windings are only suitable for synchronous machines without electrically conductive solid rotors or damper windings. Besides, they do not need an additional insulation layer inside the slots to isolate different coil sides compared to the double-layer windings. This provides an additional space inside the slots, which can be used to increase the slot-filling factor. Moreo-ver, an increased slot-filling factor and a reduced number of insulation layers improve the ef-fectiveness of the cooling system. Nevertheless, a single-layer compared to a double-layer fractional-slot distributed windings excites additional spatial harmonics, which can affect the performance and the NVH behavior of synchronous machines. Therefore, the performance and the NVH results measured on com-parable electrically excited synchronous machines are studied in detail. In contrast to other winding types, the star of slots is found being insufficient to design some single-layer fractional-slot distributed windings. Thus, part of this work deals with the sys-tematic design method of fractional-slot distributed windings based on the winding index. Through the analyses of this work, some analytical methods such as calculation equations of the winding factor are developed and the harmonic leakage factor of the zero sequence is de-rived. Besides, the rotating field theory is integrated with the winding function approach to consider the possible unipolar flux densities, the stator and rotor slotting, the static and dy-namic air-gap eccentricities, the magnetic saturation and the stator and rotor magnetic aniso-tropies. The Fourier series of the measured terminal currents, voltages and accordingly the instantaneous powers bring some additional information, which can be applied to the rotating field theory to explain the corresponding magnetic NVH excitations

Predicting amine mist formation based on aerosol number concentration and size measurements in flue gas

Amine based solvent used for CO2 capture can be lost during the process due to: degradation, vaporization, mechanical losses and aerosol (mist) formation. Only recently, studies have appeared pointing out that aerosols can dominate the total amine emission at pilot plant scale behind coal fired power plants. Future full scale amine scrubber installations will be imposed emission limit values (ELV) for a number of components including NH3 and the amine itself. Most likely these ELV will be expressed as maximum concentrations tolerated in the CO2 poor flue gas leaving the stack so it is important to prevent or cure amine aerosol emission. The study presents a novel combination of two existing measurement techniques, that measure: (i) amine emissions from the top of the absorber using FTIR and (ii) PSD of the incoming flue gas using the ELPI+. The study is the first to show how combining these two measurement techniques allows to predict the presence or absence of mist formation. This hypothesis is based on information obtained during several measurement campaigns on different pilot plants. (C) 2014 The Authors. Published by Elsevier Ltd

Inverter design for future electrified aircraft propulsion systems under consideration of wear-out failure and random failure

To reduce the wear-out effect and minimize the Single Event Burnout effect of the power semiconductor, several hardware design rules for inverters in electric aircraft propulsion systems are posed and implemented in this work. These strategies include scalable chip area and derated DC-link voltage. It is observed in a short-range reference aircraft case study that these rules could result in a conflict of objectives: reducing the risk of wear-out failure while simultaneously minimizing the risk of random failure. Therefore, it is recommended to consider random failures, wear-out failures, and their mutual impacts in a comprehensive analysis of system reliability. A reliability-oriented design rule is proposed in this work

Power Distribution and Propulsion System for an All-Electric Short-Range Commuter Aircraft—A Case Study

To participate in the transition towards a sustainable use of energy, the aircraft sector needs to be transformed with respect to the energy carrier and propulsion methods. For smaller aircraft, a battery-electric approach is promising. While this will require extensive research and design together with the application of advanced components which are partly not available to this date, general design rules and key parameters and critical components can already be deduced. This publication presents the example design of the full propulsion system for a small commuter aircraft. This serves as a case study to highlight the influence of components and parameters on the overall efficiency and weight of the system. By that, future research can be directed towards the areas of high impact on the realization of all-electric aircraft. A optimization of several motor variants, inverter topologies and power supply grid parameters is performed. The weight of the fully electric propulsion system is dominated by the battery. Therefore, all subsequent components need to be designed towards a high efficiency in opposition to high power density

Airborne Wind Energy : Flugwindenergieanlagen zur Nutzung von Höhenwind

[no abstract available

Rapid dispersal of a hydrothermal plume by turbulent mixing

Author Posting. © The Author(s), 2010. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Deep Sea Research Part I: Oceanographic Research Papers 57 (2010): 931-945, doi:10.1016/j.dsr.2010.04.010.The water column imprint of the hydrothermal plume observed at the Nibelungen field (8°18' S 13°30' W) is highly variable in space and time. The off-axis location of the site, along the southern boundary of a non-transform ridge offset at the joint between two segments of the southern Mid-Atlantic Ridge, is characterized by complex, rugged topography, and thus favorable for the generation of internal tides, subsequent internal wave breaking, and associated vertical mixing in the water column. We have used towed transects and vertical profiles of stratification, turbidity, and direct current measurements to investigate the strength of turbulent mixing in the vicinity of the vent site and the adjacent rift valley, and its temporal and spatial variability in relation to the plume dispersal. Turbulent diffusivities Kp were calculated from temperature inversions via Thorpe scales. Heightened mixing (compared to open ocean values) was observed in the whole rift valley within an order of Kp around 10-3 m2 s-1. The mixing close to the vent site was even more elevated, with an average of Kp = 4 x 10-2 m2 s-1. The mixing, as well as the flow field, exhibited a strong tidal cycle, with strong currents and mixing at the non-buoyant plume level during ebb flow. Periods of strong mixing were associated with increased internal wave activity and frequent occurrence of turbulent overturns. Additional effects of mixing on plume dispersal include bifurcation of the particle plume, likely as a result of the interplay between the modulated mixing strength and current speed, as well as high frequency internal waves in the effluent plume layer, possibly triggered by the buoyant plume via nonlinear interaction with the elevated background turbulence or penetrative convection.This work was supported by the Priority Program SPP1144 of the Deutsche Forschungsgemeinschaft; this is SPP 1144 contribution number 51. Funding for the ABE team from WHOI was provided by Grant # OE-2006-218 from NOAA's Ocean Exploration Program; funding for the MAPR work was provided by NOAA's Vents Program

The natural thermostat of nitric oxide emission at 5.3 μm in the thermosphere observed during the solar storms of April 2002

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95236/1/grl17165.pd

Adding new pieces to the Azadinium (Dinophyceae) diversity and biogeography puzzle: Non-toxigenic Azadinium zhuanum sp. nov. from China, toxigenic A. poporum from the Mediterranean, and a non-toxigenic A. dalianense from the French Atlantic

The marine planktonic dinophyceaen genus Azadinium is a primary source of azaspiracids, but due to their small size its diversity may be underestimated and information on its biogeography is still limited. A new Azadinium species, A. zhuanum was obtained from the East China Sea and Yellow Sea of China by incubating surface sediments. Five strains were established by isolating single germinated cells and their morphology was examined with light microscopy and scanning electron microscopy. Azadinium zhuanum was characterized by a plate pattern of Po, cp, X, 4′, 2a, 6′′, 6C, 5S, 6′′′, 2′′′′, by a distinct ventral pore at the junction of Po, the first and fourth apical plates, and a conspicuous antapical spine. Moreover, Azadinium poporum was obtained for the first time from the Mediterranean by incubating surface sediment collected from Diana Lagoon (Corsica) and a new strain of Azadinium dalianense was isolated from the French Atlantic. The morphology of both strains was examined. Small subunit ribosomal DNA (SSU rDNA), large subunit ribosomal DNA (LSU rDNA) and internal transcribed spacer (ITS) sequences were obtained from cultured strains. In addition, LSU sequences were obtained by single cell sequencing of two presumable A. poporum cells collected from the French Atlantic. Molecular phylogeny based on concatenated SSU, LSU and ITS sequences revealed that A. zhuanum was closest to A. polongum. French A. poporum from Corsica (Mediterranean) and from the Atlantic showed some genetic differences but were nested within one of the A. poporum ribotypes together with other European strains. Azadinium dalianense from France together with the type strain of the species from China comprised a well resolved clade now consisting of two ribotypes. Azaspiracid profiles were analyzed for the cultured Azadinium strains using LC–MS/MS and demonstrate that the Mediterranean A. poporum strain produced AZA-2 and AZA-2 phosphate with an amount of 0.44 fg cell−1. Azadinium zhuanum and A. dalianense did not produce detectable AZA. Results of the present study support the view of a high diversity and wide distribution of species belonging to Azadinium. The first record of AZA-2 producing A. poporum from the Mediterranean suggests that this species may be responsible for azaspiracid contaminations in shellfish from the Mediterranean Sea

Full Genome Characterisation of Bluetongue Virus Serotype 6 from the Netherlands 2008 and Comparison to Other Field and Vaccine Strains

In mid September 2008, clinical signs of bluetongue (particularly coronitis) were observed in cows on three different farms in eastern Netherlands (Luttenberg, Heeten, and Barchem), two of which had been vaccinated with an inactivated BTV-8 vaccine (during May-June 2008). Bluetongue virus (BTV) infection was also detected on a fourth farm (Oldenzaal) in the same area while testing for export. BTV RNA was subsequently identified by real time RT-PCR targeting genome-segment (Seg-) 10, in blood samples from each farm. The virus was isolated from the Heeten sample (IAH “dsRNA virus reference collection” [dsRNA-VRC] isolate number NET2008/05) and typed as BTV-6 by RT-PCR targeting Seg-2. Sequencing confirmed the virus type, showing an identical Seg-2 sequence to that of the South African BTV-6 live-vaccine-strain. Although most of the other genome segments also showed very high levels of identity to the BTV-6 vaccine (99.7 to 100%), Seg-10 showed greatest identity (98.4%) to the BTV-2 vaccine (RSAvvv2/02), indicating that NET2008/05 had acquired a different Seg-10 by reassortment. Although Seg-7 from NET2008/05 was also most closely related to the BTV-6 vaccine (99.7/100% nt/aa identity), the Seg-7 sequence derived from the blood sample of the same animal (NET2008/06) was identical to that of the Netherlands BTV-8 (NET2006/04 and NET2007/01). This indicates that the blood contained two different Seg-7 sequences, one of which (from the BTV-6 vaccine) was selected during virus isolation in cell-culture. The predominance of the BTV-8 Seg-7 in the blood sample suggests that the virus was in the process of reassorting with the northern field strain of BTV-8. Two genome segments of the virus showed significant differences from the BTV-6 vaccine, indicating that they had been acquired by reassortment event with BTV-8, and another unknown parental-strain. However, the route by which BTV-6 and BTV-8 entered northern Europe was not established