215 research outputs found
A Method for the Conceptual Design of Hybrid Electric Aircraft
No full textThe growing interest into hybrid electric propulsion as a possible solution to reduce in-flight emissions has led to the investigations of many innovative propulsive system architectures that couple higher system efficiency with improved aerodynamic propulsion integration strategies. The paper presents amethodology to model and size generic hybrid electric propulsion system at the conceptual level allowing for a rapid exploration of the vast design space. The generalization of the propulsive system using a basic propulsive power unit object is discussed highlighting the control parameters needed to fully define the propulsive system architecture. Three case studies for a 2035 turbo-prop regional aircraft using parallel, series/parallel and distributed series configurations showthat improvements to the fuel and energy consumption are affected by the system morphology, its control strategy and the maturity level assumed for its components. Using conservative estimations for the battery and electric components performances indicate that the best configurations can only provide a fuel reduction of around 5% while weighting 25% more than the reference design. Using more optimistic assumptions leads to a larger feasible design space where the best performing configuration, the series/parallel one, realizes more substantial fuel and energy reductions of 28% and 14% with a 24% higher take-off mass.Accepted Author Manuscript DOI: 10.2514/6.2019-1587.c1 Correction: A Method for the Conceptual Design of Hybrid Electric Aircraft Author(s) Name: Jacopo Zamboni(1); Roelof Vos(1); Mathias Emeneth(2); Alexander Schneegans(2) Author(s) Affiliations: 1. Delft University of Technology, Delft, Netherlands. 2. PACE America, Inc., Seattle, WA, United States. Correction Notice 1: In the first paragraph of section C.1 “Parallel Architecture” on page 13, the electric power ratio symbol should read φ, not ϕ. In the first paragraph of section C.1 “Parallel Architecture” on page 13, the shaft power ratio symbol should read ϕ, not φ. Correction Notice 2: In the third paragraph of section C.2 “Parallel/Series Architecture” on page 13, the inboard PPU is characterized by a constant shaft power ratio of 0, not 1; the outboard PPU is characterized by a shaft power ratio of 1 (fully electric shaft), not 0. Correction Notice 3: In the fifth paragraph of section C.3 “Distributed Series Architecture” on page 14, the shaft power ratio is set permanently to 1, not 0. Correction Notice 4: In the caption of Figure 13 on page 19, the upper right sub-figure refers to the results of the series/parallel configuration, not of the parallel configuration. The upper left sub-figure refers to the results of the parallel configuration, not of the series/parallel configuration.Flight Performance and Propulsio
Mutation status and homology modelling of acaricide-binding proteins in Rhipicephalus ticks
No full textDissertation (MSc (Biochemistry))--University of Pretoria, 2015.Rhipicephalus microplus is a tick with a one-host life cycle which
takes place on cattle. It has
three life stages during the host phase. Tropical and sub-tropical
regions around the world
make for an ideal climate for both R. microplus and R. decoloratus
ticks. Both tick species are
well documented as vectors for various tick-borne diseases. Several
target site resistance
markers are known for acaricide resistance in R. microplus and the
presence of these markers
in R. decoloratus is a focus of this study. The dieldrin resistance
marker was not observed in
R. decoloratus nor was the pyrethroid resistance marker in the
carboxylesterase gene. The
octopamine/tyramine receptor showed the presence of 49 different SNPs
as compared to with
the NCBI R. microplus entry (AJ010743.1). Maximum parsimony tree
analysis of this gene
segment which included locally sequenced R. decoloratus and R.
microplus tick samples
showed a mix grouping of both species. This would suggest that there
is not a significant
difference between R. decoloratus and R. microplus for the
octopamine/tyramine receptor to
group them as separate. Analysis of the voltage-gated sodium channel
revealed the presence of the resistance marker (L64I) in both R. microplus and R.
decoloratus ticks of South Africa.
Rhipicephalus microplus showed allele frequencies of 58.8% homozygous
resistant and a
32.4% homozygous susceptible, while R. decoloratus had a 72%
heterozygous frequency. A
model for the R. microplus carboxylesterase (RmCaE) was constructed
using 4B0O as a
template (32.2% identity). The model was well within the expected
quality range for
carboxylesterase enzymes. Docking of cypermethrin showed that no
direct interactions were
possible between the resistance SNP site and cypermethrin, but the
loss of a stabilising
interaction in the secondary structure could be the main cause behind
resistance. A partial
model for the voltage-gated sodium channel (RmvNaCh) was constructed
using 4DXW as a
template (30% identity). Docking of the different stereoisomers for
cypermethrin identified two
key atoms (C4 and Cl-) of cypermethrin as interacting partners with
the SNP site. Cyp5 was
also identified as the one stereoisomer which didn’t show a difference
between WT and
mutant docked poses and was still capable of interacting with the SNP
site. This may show cyp5 [(R)-cyano (1S, 3S)] as an important stereoisomer for use on
pyrethroid resistance R.
microplus ticks. Experimental validation of in silico results must be
done in future.tm2015BiochemistryMSc (Biochemistry
Music for classical guitar by South African composers : a historical survey, notes on selected works and a general catalogue
No full textIncludes abstract.Includes bibliographical references (leaves 296-309).This is the first comprehensive investigation of music for, or including, the classical guitar by South African composers. The focus of this research has been, firstly, to uncover as much of the repertoire as possible, and, secondly, to collate, study, catalogue and report on the information. A brief historical survey of the guitar in South Africa provides the context within which this study was conducted. The primary sources of quantitative data collection were through the archival catalogues of the South African Music Rights Organisation and through personal contact with guitarists, composers and guitar teachers. Other sources consulted were publishers, broadcasting corporations, recording companies, libraries and the internet. The body of the dissertation comprises biographical sketches, background notes, analyses and technical notes on 17 selected solo and chamber works dating from 1947 to 2007 by some of South Africa's most prominent composers and guitaristcomposers. The repertoire ranges in style from the traditional and ethnically inspired to the experimental and abstract. As this is an empirical survey, each selected entry includes details on instrumentation, duration, level of difficulty, number of pages, scordatura, commissions or requests, sources or publishers, premières and recordings. A biography of each composer is provided as well as background notes which offer an overview of the selected work. The notes discuss historical, cultural, musical and extra-musical influences, and frequently include references to interview material. The commentaries on the selected works, with musical examples, include an analytical component describing structure, form, stylistic and compositional elements, while the technical observations include performance suggestions and a grading for each work
Comparing the environmental impact of different hydrometallurgical processes for the recycling of lithium-ion batteries using a life cycle assessment approach
No full textThesis (PhD)--Stellenbosch University, 2024.ENGLISH ABSTRACT: Lithium-ion batteries (LIBs) have become commonplace for everyday use in consumer electronics. These batteries have also gained a lot of popularity recently for usage in larger scale application such as electric vehicles (EV). The LIB market is projected to grow from 700 GWh in 2022 to 4.7 TWh in 2030 (Fleischmann et al., 2023). The consequence of this rapidly increasing demand for LIBs is the formation of a fast-growing end-of-life (EOL) LIB waste stream. This waste stream includes valuable metals such as lithium, cobalt, nickel, and manganese to potentially be recycled, thus providing benefits in terms of waste management and income from the sale of these recovered metals. There is thus a clear need for EOL LIB recycling and a necessity to find out what is the best process technology available to recycle EOL LIBs. Traditionally LIBs have been recycled using pyrometallurgy, but the recent industry focus has shifted towards alternative process technologies such as hydrometallurgy. There is, however, no clear consensus on how these hydrometallurgical flowsheets should be arranged. As such, the purpose of this study was to compare the environmental impacts of implementing different hydrometallurgical process flowsheets designed for the recovery of metals from EOL LIBs. This comparative environmental study was performed using the life cycle assessment (LCA) framework and considered the use of three lixiviants (hydrochloric-, sulphuric-, and citric acid) alongside the use of three flowsheet options (sequential metal precipitation, mixed metal precipitation, and hybrid sequential precipitation - solvent extraction systems). Lastly, the process was modelled based on a mixed feed of LiCoO2, LiFePO4, and NMC111 batteries. The potential environmental impacts of mineral acid-based processes were found to generally be lower than that of organic acid-based processes by 18 to 61 percentage points. Furthermore, mixed metal precipitation provided the greatest environmental benefit of the flowsheet options considered by 46 to 117 percentage points when compared to the closest competitor. The LCA system was subsequently subjected to multivariate uncertainty analysis and a discernability analysis regarding process feed sensitivity which served to confirm the trends already observed. The LCA system was also subjected to a weak point analysis, where the consumption of NaOH and electricity were listed as the main concerns for process improvement. The process solutions recommended to address both weak points involve the integration of membrane technology and antisolvent crystallisation. Furthermore, the LCA system was compared for a South African and a European context, where it was determined that South Africa’s overreliance on hard coal for energy generation is the main difference between the two regions. Finally, the hydrometallurgical EOL LIB recycling processes were subjected to an additional LCA study regarding the use of recycled metals for resynthesizing NMC cathode materials. This additional study showed that integrating the sequential precipitation recycling process with solid-state synthesis of NMC622 cathode could save up to 70% on energy consumption during cathode synthesis. Meanwhile, integrating the mixed NMC precipitation recycling process with the solid-state synthesis of NMC622 cathode could reduce the environmental impact of NMC cathode production by up to 67%.AFRIKAANSE OPSOMMING:Litium-ioon batterye (LIB) het alledaags geword vir implementasie in verbruikerselektronika en het onlangs ook gewildheid verwerf vir gebruik in grootskaalse toepassings soos elektroniese voertuie. Die LIB mark is geprojekteer om te groei vanaf 700 GWh in 2022 na 4.7 TWh in 2030 (Fleischmann et al., 2023). Die gevolg van hierdie vining toenemende aanvrag na LIBs is die ontstaan van ‘n vining groeiende LIB afval stroom. Hierdie afval stroom sluit waardevolle metale soos litium, kobalt, nikkel, en mangaan in wat dan moontlik herwin kan word om voordele aan te bied soos afval vermindering en inkomste vanaf die verkope van die herwinde metale. Daar is dus ‘n groot aanvraag na die herwinning van afval LIBs en govolglik ‘n nood om uit te vind wat die beste beskikbare prosestegnologie is om afval LIBs te herwin. Tradisioneel is LIBs herwin deur pirometallurgie, maar onlangs het die industrie se fokus geskyf na alternatiewe prosestegnolgieë soos hidrometallurgie. Daar is egter geen duidelike konsensus oor hoe hierdie hidrometallurgiese prossese uitgelê moet word nie en as sulks was die doel van hierdie navorsing om ‘n vergelyking te doen van die omgewingsimpak wat ontstaan vanaf die implementasie van verskillende hidrometallurgiese prosesse vir die herwinning van metale vanaf afval LIBs. Hierdie vergelykende navorsing is voltooi aan hand van die lewenssiklus assesseringsraamwerk en het die gebruik evalueer van drie logingsmiddels (kloorsuur, swaelsuur, en sitroensuur) tesame met die gebruik van drie verskillende prosesuitlegte (opeenvolgende metaal presipitasie, gemengde metaal presipitasie, en ‘n geïntegreerde prosess van opeenvolgende presipitasie en organiese ekstraksie). Daarby is die proses gemodelleer gebasseer op ‘n gemengde voer van LiCoO2, LiFePO4, and NMC111 batterye. Die potensiële omgewingsimpak van die mineral suur-gebasseerde prosesse is oor die algemeen laer as die van die organiese suur-gebasseerde prossese met tussen 18 tot 61 persentasiepunte. Verder is dit gevind dat die gemengde metaal presipitasie process the grootste omgewingsvoordeel bydrae van al die prosesuitlegte met tussen 46 tot 117 persentasie punte wanneer dit vergelyk word met die naaste kompeteerder. Die resultate van die lewenssiklus assessering is gevolglik onderwerp an veelveranderlike onsekerheidsanalise en onderskeidbaarheidsanalise aangaande prosesvoer sensitiwiteit waarby dit ontdek was dat daar geen merkwaardige bewyse was om die resultate van die aanvanklike lewenssiklus assessering te ontken nie. Die lewenssiklus assessering sisteem is ook onderwerp aan swakpunt-analise, waar die verbruik van NaOH en elektrisiteit gelys is as the hoof ondernewmings vir prosesontwikkeling. Die prosesoplossings wat aanbeveel word for beide swakpunte betrek die integrasie van membraan-tegnologie en anti-oplosmiddel kristallisasie. Verder is die lewenssiklus assessering sisteem vergelyk vir die Suid-Afrikaanse en Europese kontekste, waarby dit vasgestel is dat Suid-Afrika se oorvertroue op steenkool vir kragopwekking die hoof verskil is in die prestasie van die herwinningsprosesse in die twee streke. Uiteindelik is die hidrometallurgiese herwinningsprosesse vir afval LIBs geïntegreer met ‘n bykomende lewenssiklus assessering wat gefokus het op die omgewingsimpak van herwinde metale gebruik vir die hersintese van NMC katode materiale. Die addisionele studie het bevind dat as die opeenvolgende presipitasie herwinningsproses geïntegreer word met die vaste-toestand sintese van NMC622 katode material dan kan daar tot en met 70% gespaar word op energieverbuik tydens die sintese van NMC katodes. Terselfde tyd kan die gemengde metaal presipitasie herwinningsproses die omgewingsimpak van NMC katode sintese met omtrent 67% verminder as dit geïntegreer word met die vaste-toestand sintese van NMC622 katode materiaal.Doctora
Experimental Investigation of Over-the-Wing Propeller–Boundary-Layer Interaction
No full textThis experimental study focuses on the aerodynamic interaction between an over-the-wing (OTW) propeller and a wing boundary layer. An OTW propeller is positioned above the hinge line of a wing with a trailing-edge flap. Measurements are carried out with and without axial pressure gradients by deflecting the flap and by extending the flat upper surface of the wing in the streamwise direction, respectively. Surface-pressure taps, microphones, and particle image velocimetry are combined to quantify both the time-averaged and unsteady interaction effects. Results show that the propeller generates an adverse pressure gradient on the wing surface that scales linearly with thrust and decreases with increasing blade-tip clearance. The pressure gradient is partially caused by slipstream contraction, which decelerates the flow near the wall. Additionally, the surface-pressure fluctuations generated beneath the propeller blades and slipstream are stronger than the time-averaged pressure increase due to flow deceleration. Consequently, the propeller triggers flow separation over the hinge line when the flap is deflected. A parametric study of different propeller locations indicates that increasing the tip clearance is not an effective way to mitigate flow separation. However, displacing the propeller half a radius upstream of the hinge line creates a Coandă effect, which allows the flow to remain attached.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Flight Performance and PropulsionWind Energ
System-level assessment of tail-mounted propellers for regional aircraft
No full textThree regional transport aircraft of different configuration are synthesized for the same design specification using an automated design routine. The first aircraft features wing-mounted propellers, the second aircraft features propellers mounted on the horizontal tail plane, while the last configuration replaces the horizontal and vertical tail with two ducted propellers mounted near the rear of the fuselage. These last two innovative configurations have the potential to reduce the cabin noise, while the ducted propeller could also reduce community noise. The analysis and design methods to size and analyze these configurations include weight and balance, stability and control, aerodynamic performance, and mission performance. Propeller slipstream effects are taken into account and demonstrated to play an important role in the sizing of the horizontal tail surface. A comparison study between the three aircraft for a harmonic mission of 1530km and 7500kg payload demonstrates that the aircraft with wing-mounted propellers has the lowest maximum take-off mass and burns the least amount of fuel. The two innovative configurations have slightly less performance, which is ultimately attributed to the large center-of-gravity excursion that stems from an aft-mounted propulsion system. A 3% increase in maximum takeoff weight is predicted along with a fuel burn increase between 5% and 10% for the innovative configurations, respectively. Further investigation of the underlying assumptions might improve these results in future studies.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Flight Performance and Propulsio
Aerodynamic Interaction Between an Over-the-Wing Propeller and the Wing Boundary-Layer in Adverse Pressure Gradients
No full textThis experimental study focuses on the aerodynamic interaction effects that occur between an over-the-wing (OTW) propeller and a wing boundary-layer. An OTW propeller is positioned above the hinge-line of a wing featuring a plain flap. The measurements are carried out with and without axial pressure gradients by deflecting the flap and by extending the wing in streamwise direction to simulate a flat-plate configuration, respectively. Wing pressure taps and phase-free particle-image-velocimetry (PIV) are used to quantify the time-averaged interaction effects, while embedded microphones and phase-locked PIV are used to analyze unsteady interaction effects. Results show that the propeller generates an adverse pressure gradient on the wing surface which increases linearly with thrust and decreases as the blade tipclearance is increased. The pressure gradient is partially caused by the slipstream contraction, which creates a streamwise velocity deficit near the wall immediately behind the propeller disk. Moreover, the rotation of the propeller blades generates pressure fluctuations on the surface, the amplitude of which exceeds both the pressure fluctuations produced by the tip-vortices and the time-averaged pressure effect of the slipstream. Consequently, the propeller triggers flow separation when the flap is deflected. A parametric study of different propeller locations indicates that increasing the tip-clearance is not an effective way to mitigate flow separation. However, displacing the propeller half a radius upstream induces a Coanda effect which allows the flow to remain attached
A novel approach incorporating Gibbs free energy of mixing to model the environmental impact of industrial brine treatment processes: a case study of hydrometallurgical recycling of lithium-ion batteries
No full textThe water quality of different industrial effluent streams, produced by various chemical and metallurgical processes, is liable to vary greatly which makes it difficult to compare the environmental impact of unique industrial effluent streams. When performing life cycle assessment studies for chemical processes, researchers are often left using generalised effluent treatment datasets to model their effluent streams. This approach disregards the thermodynamic properties of the effluent streams and only considers the volume of effluent being treated. The aim of this investigation was to develop a simplified, consistent methodology for modelling the environmental impact of unique industrial effluent streams. The proposed method primarily involves calculating the Gibbs free energy of mixing which can then be analysed as either a regular- or a specific energy value, thereby highlighting the importance of both improving effluent quality and reducing effluent quantity to minimise the environmental impact of treating industrial effluent. Subsequently, to approximate the actual energy requirement for treating each individual effluent stream, the Gibbs free energy of mixing may be divided by the exergetic efficiency of the appropriate effluent treatment technology for that specific effluent stream. To illustrate the utilisation of this methodology, a case study was performed which compared the environmental impact of effluent streams produced by different hydrometallurgical lithium-ion battery recycling plants. The process with the lowest specific effluent impact made use of citric acid as leaching reagent in comparison to a more traditional sulphuric acid-based lithium-ion battery recycling process. However, the citric acid-based process had a larger volume of effluent to treat and ultimately required more energy to achieve complete theoretical separation of the contaminants from the effluent than the sulphuric acid-based process
Modelling the Propeller Slipstream Effect on the Longitudinal Stability and Control
No full textAs the aviation industry continues to strive for improvements in fuel efficiency throughout the entire aircraft design, interest has been renewed in propeller engines. New research into advanced turboprop engines, so-called open rotor engines, seems promising as they combine the inherent high propulsive efficiency of ordinary turboprop engines, with the capability of delivering higher thrust. Unfortunately, the implementation of propeller engines does have significant implications on the stability and controllability of an aircraft. These implications are primarily caused by the propeller slipstream, the complex streamtube behind the propeller with strong gradients in various flow quantities both in streamwise and radial direction. The objective of this thesis was to develop, implement, and validate a prediction method for the propeller slipstream effect on the longitudinal stability and control of conventional aircraft configurations in the Initiator. During the investigation of the propeller slipstream effect, an existing prediction method was found which was based on calculating the four major effects caused by the propeller slipstream on the longitudinal stability and control. These four effects are, an additional normal force at the propeller disk, an increase in lift over the wing due to the slipstream, a change in the tail-off pitching moment, and a change in tail contribution to the pitching moment due to increased downwash and dynamic pressure. This method seemed ideal as it not only gives relatively accurate results, but does so with computationaly inexpensive calculations. During the implementation of this method in the Initiator, additional changes were made to calculate aerodynamic variables which were previously estimated using an extended vortex lattice method program. This implemented prediction method was validated using the only available wind tunnel data for the Fokker 50 and a special Saab 340 with T-tail configuration. Through this validation, the prediction method proved to maintain an acceptable accuracy for all configurations with minimal computation time. Further analysis of the results showed that the propeller slipstream effect reduces the tail effectiveness due to an increase in downwash angle at the tail. This was especially the case for the Fokker 50, which due to its low wing configuration, has a further increase in downwash caused by an inflow effect of the outer flow into the streamtube.Flight Performance and PropulsionFlight Performance and PropulsionAerospace Engineerin
Formalizing Technology Descriptions for Selection During Conceptual Design
No full textEvaluation and assessment of novel technologies for aerospace applications is essential for business strategy and decision making regarding development efforts. However, technology evaluation and assessment are challenging to perform objectively using a structured approach. As a first step towards a more objective and structured approach a graph-based description of engineering systems is described herein. Analyses can be applied to such a description through pattern matching, after which the quantities of interest can be computed by an automated algorithm using a dependency graph. The approach is applied to a simplified aircraft model, to perform a mission analysis and compute fuel burn. It is shown the method successfully computes the required parameter and is easily adapted to analyze an electric aircraft as well.Accepted Author Manuscript “New title: Formalizing Technology Descriptions for Selection During Conceptual Design”Flight Performance and Propulsio
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