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Jones, Stephen T. "Experimental investigations, modelling and control of direct injection gasoline engines." Thesis, University of Nottingham, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.246313.
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Welgemoed, Frans Marx. "Shunt reactive compensation of voltage dips and unbalance." Thesis, Stellenbosch : University of Stellenbosch, 2010. http://hdl.handle.net/10019.1/5315.
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Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2010.ENGLISH ABSTRACT: The use of power electronic converters provides a more efficient, accurate and dynamic solution to reactive compensation. In this thesis the application of power electronic converters to shunt reactive compensation will be discussed. In particular voltage dips and voltage unbalance are considered as both can be mitigated by means of shunt reactive compensation. A pre-existing uninterruptible power supply is adapted to operate as a shunt reactive compensator. The uninterruptible power supply consists of a 250 kVA three phase voltage source inverter. The modifications are limited to software and control algorithms that do not alter the normal operation of the uninterruptible power supply. Control algorithms are designed and discussed in detail. A typical double loop control strategy is implemented on the power electronic converter. The inner loop consists of a dead-beat current controller. The outer loop consists of three proportional and integral controllers controlling the DC-bus voltage, AC voltage and voltage unbalance respectively. Voltage dips and unbalance are compensated for using only reactive power. Focus is placed on producing a result can be used easily in practice.
AFRIKAANSE OPSOMMING: Drywings elektroniese omsetters wat gebruik word vir newe reaktiewe kompensasie lewer meer effektiewe, akkurate en dinamiese resultate. In hierdie tesis word die toepassing van drywings elektroniese omsetters vir newe reaktiewe kompensasie bespreek. Daar word meer spesifiek na spannings duike en spannings wanbalans gekyk aangesien albei met newe reaktiewe kompensasie verminder kan word. ’n Bestaande nood kragbron is aangepas om as n newe reaktiewe kompenseerder te funksioneer. Die nood kragbron bestaan hoofsaaklik uit ’n 250 kVA drie fase omsetter spanningsbron. Die aanpassings is beperk tot sagteware en beheer algoritmes wat nie die oorspronklike funksionaliteit van die nood krag bron beinvloed nie. Beheer algoritmes word ontwerp en deeglik bespreek. ’n Tipiese dubbel lus beheer strategie word op die drywings elektroniese omsetter toegepas. Die binnelus bestaan uit ’n voorspellende stroom beheerder. Die buite-lus bestaan uit drie proportioneel en integraal beheerders wat onderskeidelik die GS-bus spanning, WS spanning en spanning wanbalans reguleer. Spannings duike en wanbalans is verminder deur slegs reaktiewe drywing te gebruik. Die doel was ook om ’n prakties bruikbare resultaat te lewer.
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Boyajian, Tabetha S., Roi Alonso, Alex Ammerman, David Armstrong, A. Asensio Ramos, K. Barkaoui, Thomas G. Beatty, et al. "The First Post-Kepler Brightness Dips of KIC 8462852." IOP PUBLISHING LTD, 2018. http://hdl.handle.net/10150/626540.
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We present a photometric detection of the first brightness dips of the unique variable star KIC 8462852 since the end of the Kepler space mission in 2013 May. Our regular photometric surveillance started in 2015 October, and a sequence of dipping began in 2017 May continuing on through the end of 2017, when the star was no longer visible from Earth. We distinguish four main 1%-2.5% dips, named "Elsie," "Celeste," "Skara Brae," and " Angkor," which persist on timescales from several days to weeks. Our main results so far are as follows: (i) there are no apparent changes of the stellar spectrum or polarization during the dips and (ii) the multiband photometry of the dips shows differential reddening favoring non-gray extinction. Therefore, our data are inconsistent with dip models that invoke optically thick material, but rather they are in-line with predictions for an occulter consisting primarily of ordinary dust, where much of the material must be optically thin with a size scale << 1 mu m, and may also be consistent with models invoking variations intrinsic to the stellar photosphere. Notably, our data do not place constraints on the color of the longer-term "secular" dimming, which may be caused by independent processes, or probe different regimes of a single process.
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Anastasio, Francesca. "Razionalizzazione dei processi manutentivi dei mezzi d'opera ferroviari: il caso DIPSA TECHNES s.r.l." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021.
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Oggetto del presente elaborato è stata un’analisi dei processi aziendali in DIPSA TECHNES s.r.l., condotta attraverso l’applicazione del ciclo di miglioramento continuo Plan-Do-Check-Act.
La fase di “PLAN” ha portato all’identificazione, tramite mappatura, dei macro-processi suddivisi in processi di management, processi chiave e processi di gestione delle risorse. Tra quelli chiave, secondo la matrice della variabilità di Hall e Johnson (2009), la manutenzione dei mezzi d’opera è risultata critica e la contrazione dei tempi di processo è emersa come obiettivo strategico. La fase successiva (“DO”) è consistita in un monitoraggio “sul campo”: l’indagine si è svolta con riferimento a due mezzi d’opera: un moto-carrello con gru e un carro pianale, entrambi soggetti a Verifica Periodica Quinquennale. L’output è stata la mappatura dello stato attuale (AS-IS) e una rappresentazione GANTT, per evidenziare le tempistiche. La fase di “CHECK” ha riguardato un’analisi che ha portato all’identificazione delle cause di inefficienza: elevati tempi di fornitura; procedure interne all’azienda limitanti; assenza di un sistema di assegnazione delle responsabilità; inefficace gestione del magazzino.
Le proposte di miglioramento avanzate nella fase “ACT”, da una parte riesaminano la sequenza delle attività e i momenti di contatto con il cliente; dall’altra, consistono in alcune proposte di sistema che promuovono il vendor rating, la gestione del magazzino e lo sviluppo di un sistema di assegnazione delle responsabilità con apposita matrice. Ribadendo l’intrinseca dinamicità del ciclo PDCA, vengono presentate infine alcune linee metodiche su cui strutturare i cicli successivi in DIPSA TECHNES, affinché le proposte avanzate prendano forma. In particolare, viene proposto un sistema di indicatori per il monitoraggio dei processi aziendali.
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Napolitano, Fabio <1975>. "Correlating Lightning with voltage dips and faults in power distribution networks." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2009. http://amsdottorato.unibo.it/1882/.
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Mopidevi, Vydik. "Video Quality Evaluation using NR metric with Detection of Frame Dips and Drops." Thesis, Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-4153.
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Wireless technology has become the most interesting field in the area of communications and networking. Video transmission plays a major role in this area. Data transmission via wireless communications is a major task, especially to send the data without loss of packets. The digital video decoder produces dropped or repeated frames from the encoded video due to packet loss. Brief frame drops of one frame duration are referred as dips. This research work investigates how to identify these frame dips and drops and also to measure the quality of the video which contain frame dips and frame drops. A dynamic threshold estimator is implemented to identify these frame dips. The qualitative analysis of a video is performed using a No Reference metric. In this metric the quality assessment can be achieved by identification of frame dips and drops and calculating Modified Fraction of Dropped Frames. Dips and abrupt temporal variation occurring at the end of frame freezing event of a video fluidity impairment caused by frame dropping will be taken into account using this metric. The parameters which are generated from Structural Similarity Index Metric (SSIM) analysis are efficient enough to compare the video quality and estimate the metric performance objectively. Our proposed metric has predicted the SSIM with a Pearson correlation coefficient of 0.99 in test1, 0.92 in test2 and 0.99 in test3. Therefore in terms of prediction accuracy the proposed metric has a good correlation with the deployed metric and obtained robustness to our approach.Trådlös teknik har blivit den mest intressanta fältet inom kommunikation och nätverk. Videoöverföring spelar en viktig roll på detta område. Dataöverföring via trådlös kommunikation är en stor uppgift, särskilt för att skicka data utan förlust av paket. Den digitala videoavkodare producerar tappade eller upprepade bildrutor från den kodade videon grund paketförluster. Kort ram droppar en ram varaktighet kallat dips. Denna forskning undersöker hur man identifierar dessa ram dips och droppar och även att mäta kvaliteten på video som innehåller ram dips och droppar ram. En dynamisk tröskel estimatorn genomförs för att identifiera dessa ram dips. Den kvalitativa analysen av ett videoklipp utförs med hjälp av en No Reference metrisk. I denna statistik kvalitetsbedömningen kan uppnås genom identifiering av ram nedgångar och droppar och beräkning modifierad Andel bildrutor. Dips och abrupt temporal variation inträffar i slutet av ramen frysning händelse av en video flytbarhet orsakats av ram släppa kommer att beaktas med denna metrik. De parametrar som genereras från strukturell likhet Index Metric (SSIM) analys är effektiva nog att jämföra videokvalitet och uppskatta det metriska prestanda objektivt. Vår föreslagna värdet har förutspådde SSIM med Pearson korrelationskoefficient av 0,99 i test1, 0,92 i test2 och 0,99 i test3. Därför gäller förutsägelse noggrannhet föreslagna måttet har en god korrelation med utplacerade metriska och fick robusthet till vår strategi.
Vydik Mopidevi, D.No: 5-162, Sri Vijetha Public School, Tallapudi, West Godavari District, Pin Code: 534341 Phone Number: Home: 00813282979 Work: 0046734784445 Email: vydik.mopidevi@gmail.com
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Bold, Kevin Charles. "Erosion control practices in managed forested watersheds : vegetation establishment and broad-based dips /." Available to subscribers only, 2007. http://proquest.umi.com/pqdweb?did=1407498271&sid=7&Fmt=2&clientId=1509&RQT=309&VName=PQD.
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Rani, Dipti [Verfasser]. "Label-free detection of biomolecules using silicon nanowire ion-sensitive field-effect transistor devices / Dipti Rani." Gießen : Universitätsbibliothek, 2018. http://d-nb.info/1156851343/34.
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Draper, S., Sherri Smith, and Jacek Smurzynski. "The Role of Temporal Fine Structure Processing in “Listening in the Dips” of Noise." Digital Commons @ East Tennessee State University, 2011. https://dc.etsu.edu/etsu-works/2215.
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Twiney, Benjamin W. G. "Investigation of combustion robustness in catalyst heating operation on a spray guided DISI engine." Thesis, University of Oxford, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.558407.
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The cold start catalyst warm-up operation is seen as one of the most important modes in Direct Injection Spark Ignition (DISI) Engine operation. When the catalyst is cold the engine out emissions become the tailpipe out emissions, so it is vital for the catalyst to obtain its working temperature as quickly as possible. A very high exhaust temperature can be achieved with a very retarded ignition - the engine can be made to operate at no load with a close to wide open throttle. With a retarded ignition, a split injection strategy has been shown to improve combustion stability which is critical for the trade-off between tailpipe emissions and vehicle idle stability. The spray guided DISI engine has a multi- hole injector centrally located in the chamber with the spark plug. For catalyst heating operation, the first injection occurs during induction, which forms a relatively well mixed but lean mixture in the cylinder before ignition, and the second injection occurs close to a retarded ignition, which produces a stratified fuel rich mixture in the central region of the combustion chamber near the spark plug. Combustion initialization is found to be sensitive to spark plug protrusion and orientation, injector orientation and 2nd injection timing relative to ignition. High tension current and voltage measurements have been taken in order to characterize the effect of the 2nd injection timing on both the breakdown and the glow phase of the arc discharge. Both phases are shown to be influenced by the timing of the 2nd injection. The richer mixture causes the breakdown voltage to increases while the airflow entrained in the 2nd injection has been shown to stretch the spark and in the worst case extinguish it prematurely. In-cylinder spray imaging by Mie scattering has been taken with frame rates up to 6000 fps, with high speed video photography of chemiluminescence and soot thermal radiation. Tests have studied the effect of the spark plug orientation and injector orientation, with timing sweeps for the phasing of the second injection. The images show interaction of a fuel jet with the earth electrode, stretching of the arc, variable location for the start of combustion and significant cycle-by-cycle variations with the same operating point leading to normal combustion, slow combustion and misfiring cycles. Spectroscopic measurements have confirmed the presence of OH *, CH * and C2*; emissions lines, and their relative magnitude compared to soot radiation. Filtering for CH * has been used with a photo-multiplier tube. These signals show the arc discharge, the delay between the arc and the kernel growth and (depending on the timing of the 2nd injection) small kernels which do not subsequently fully develop and can cause misfiring cycles. Unburned hydrocarbon emissions have been measured with a fast-response FID, so that emissions can be related to: misfiring cycles, slow burning cycles (0 < GMEP <0.5), and normal cycles. These measurements show that only the misfiring cycles lead to significant unburnt hydrocarbon emissions. The misfire mechanism depends on the timing of the 2nd injection. When the 2nd injection ends at the spark, no kernel is seen for a misfiring cycle. However, a kernel is shown to grow in the lean background mixture indicating that the misfire mechanism, when the 2nd injection ends close to the spark, is that the local air/fuel ratio is too rich for the onset of combustion. However, when the 2nd injection is significantly retarded from the spark a different misfire mechanism is present. A small kernel is shown to exist between the spark and the arrival of the fuel from the 2nd injection. For the misfiring cycle, this kernel is extinguished early, possibly due to an interaction between the kernel and the 2nd injection.
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Peng, Jinsheng. "Assessment of transformer energisation transients and their impacts on power systems." Thesis, University of Manchester, 2013. https://www.research.manchester.ac.uk/portal/en/theses/assessment-of-transformer-energisation-transients-and-their-impacts-on-power-systems(c32615d7-45c5-4eae-8465-62be67890adc).html.
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Transformers are essential components facilitating transmission and distribution of electric power. Energisation of transformers, however, can cause core operating at deep saturation region and thereby induce transient inrush currents of high magnitude and with rich harmonics. This can lead to undesirable effects including potential damage to the transformer itself, relay mal-operation, harmonic resonant overvoltages, and reduced power quality in the system (mainly in the form of voltage dips). This thesis investigates voltage dips caused by energising generator step-up (GSU) transformers and two types of generation connection are studied: one is a combine cycle gas turbine (CCGT) plant connected to a 400 kV transmission grid and the other is a large offshore wind farm connected to a 132 kV distribution grid. To carry out the investigation, detailed network models were developed in alternative transients program/electromagnetic transients program (ATP/EMTP) and validated with the help of field measurements. For the connection of generation in the transmission grid, deterministic assessment was conducted to comparatively analyse voltage dips caused by energising large GSU transformers under different energisation conditions and different network conditions; special attention was paid to the energisation cases involving sympathetic inrush between transformers by addressing its prolonging effects on voltage dips, with sensitivity studies further carried out to identify the key influential parameters. In addition, stochastic assessment was conducted by applying Monte Carlo method, which helps identify the dip frequency pattern and the likelihood of reaching the dip magnitude resulted from the commonly agreed worst case energisation condition; their sensitivities to the variation of circuit breaker closing time span, transformer core residual flux, system condition and the number of transformers being energized together were also investigated. Furthermore, possible cost-effective operational approaches to mitigate the voltage dips were explored and compared. For the connection of large offshore wind farm, voltage dips caused by energising wind turbine transformers under different scenarios were assessed; in particular, sympathetic inrush between wind turbine transformers were studied, and the energisation sequence resulting in less sympathetic inrush was deterministically identified and stochastically validated. The simulation results of deterministic studies indicate that, when carrying out energisation of a large GSU transformer in the transmission grid under the commonly agreed worst case energisation condition, the dip magnitude can reach 9.6% and the duration 2.7 seconds; moreover, when coupled with sympathetic inrush, the duration can be prolonged by 136%, lasting for 6.4 seconds. The sensitivity studies show that transformer core saturation inductance is the key parameter determining dip magnitude and transformer copper losses is the key parameter determining dip duration. Stochastic assessment of voltage dips shows that, out of 1000 stochastic dip events, less than 0.5% of the dips can reach the worst case dip magnitude and about 80% are of magnitudes less than 0.6 pu of the worst case dip magnitude; the dip frequency pattern is found to be insensitive to the circuit breaker closing time variation but can be considerably influenced by the residual flux distribution. In terms of mitigation measures, it was proven that, by adjusting tap changer position, applying static var compensator and even opening coupler circuit breaker in the substation, the degree of voltage dip especially the dip duration can be significantly reduced. Contrasting to those observed in the transmission grid, voltage dips resulted from energising wind turbine transformers in large offshore wind farms are of less concern; dip magnitudes are no more than 1% in the case of energising a stand-alone wind turbine transformer. However, sympathetic inrush between wind turbine transformers within one feeder was found to be significant and the energisation sequence resulting in less sympathetic inrush is to separately energise the wind turbine transformer from the one closest to the offshore platform to the one farthest away from the platform.
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Oh, Changhoon. "Assessment of the factors influencing PN emission in a DISI engine under cold-start condition." Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/106786.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2016.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 155-160).
Due to their advantages in higher fuel efficiency and torque compared to conventional port fuel injection (PFI) engines, direct injection spark ignition (DISI) engines have become dominant in gasoline-fueled engines. However, DISI engines have a significant drawback in particulate matter (PM) emission: the PM emission of DISI engines is at least an order of magnitude higher than that of PFI engines. The objective of this study is to investigate PM emission in DISI engines, mainly focusing on particulate number (PN) emission. The study aims to assess, respectively, the plausible PM formation mechanisms: non-fuel originated sources (e.g., lubricant), flame propagation in rich mixture and the pyrolysis of the vapor from liquid fuel film. Through a series of experiments, it has been found that non-fuel contribution is less important than the other two mechanisms. For all operating conditions, the absolute amount of the non-fuel contribution is much smaller than the total emission. In case of PM generated by flame propagation in rich mixture, there is a threshold air-fuel equivalence ratio below which PM starts to form rapidly. The threshold is influenced by the combustion temperature. PM starts to form at lower equivalence ratio when the combustion temperature was lower. Contrary to the PM generated from flame propagation in fuel-rich mixture case, that from the liquid fuel film is suppressed by lowering the combustion temperature. Transmission electron microscopy (TEM) imaging shows that the sizes of primary particles and agglomerated particles become larger as engine load increases, but particulates from different mechanisms have different morphology.
by Changhoon Oh.
Ph. D.
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Mahendar, Senthil Krishnan. "Numerical Analysis of Gas Exchange system requirements in Heavy Duty DISI process with Alternative fuels." Thesis, KTH, Maskinkonstruktion (Inst.), 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-193314.
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Kommersiella fordon som använder dieselmotorer har hög bränsleeffektivitet men kräver dyra efterbehandlingssystem och ökade driftskostnader. Ottomotorer har fördelen att använda en enkel trevägskatalysator vilket gör ägande- och driftkostnader mycket attraktiva. Knack är en begränsande faktor för användning av bensin i ottomotorer vilket begränsar deras effektivitet. I turboöverladdade motorer med "direct injection spark ignition" (DISI) skulle biobränslen som alkoholer minska knackning (och därigenom förbättra effektiviteten) och bränslen innehållande syre skulle också bidra till att minska sotbildning. I denna studie undersöks de förändringar som krävs för att byta bränsle från diesel till alkoholer i DISI motorer. En numerisk analys används för att välja ingångsparametrar sådana som inlopp och avgasventil fasning, EGR, förtändningen och laddtryck krav för att uppnå bästa verkningsgrad. Inparametrarna optimeras genom en genetisk algoritm med en GT-Power modell av motor som körs på bensin, etanol och metanol. Vid toppbelastning, har det visat sig att alkoholerna ger något bättre termisk verkningsgrad än bensin (33% bensin, 34% etanol och 35% metanol vid 1000 rpm full belastning) på grund av lägre knack tendens. Laddtryck och EGR krav härleds och turbomatchning utförs genom att skala tabellerna från Diesel VGT turboladdaren. Det visade sig att etanol och metanolfallet skulle kräva en VGT turboladdare medan bensinfallet bara skulle behöva en wastegate turboladdare. Med hjälp av informationen från denna studie är det möjligt att validera denna modell på en encylindrig motor för vidare studier.Commercial vehicles using diesel engines have high fuel efficiency but have a significant cost impact due to expensive aftertreatment system and increased running costs. Spark ignition engines have the advantage of using a simple three-way catalyst making cost of ownership and operation very attractive. Knock is a limiting factor for using gasoline spark ignition engines hence has poor efficiency. In turbocharged direct injection spark ignition (DISI) operation, bio-fuels like alcohols would reduce knock (thereby improving efficiency) and the oxygenated fuel would also help in reducing soot formation. In this study, the system modifications required to make a fuel change from diesel to alcohols in DISI mode is analysed. A numerical analysis is used to select input parameters such as inlet and exhaust cam phasing, EGR rate, spark advance and boost pressure requirements for best efficiency of the engine in full load operating conditions. The input parameters are optimised by a genetic algorithm in loop with a GT Power model of the engine with gasoline, ethanol and methanol. At peak load, it is found that the alcohols give slightly better thermal efficiency than gasoline (33% Gasoline; 34% Ethanol & 35% Methanol at 1000rpm full load) due to lower knock tendency. The boost pressure and EGR rate requirements are derived and turbo matching is performed by scaling diesel VGT maps. It was found that the ethanol and methanol case would require a VGT whereas gasoline would only need a wastegate turbocharger. Using the information from this study, a testing scheme on a single cylinder engine could be derived to validate this model for further study.
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Efthymiou, Petros. "An optical investigation of DISI engine combustion, fuel spray and emissions at cold-start temperatures." Thesis, Loughborough University, 2015. https://dspace.lboro.ac.uk/2134/19486.
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Particulate number (PN) standards in current and future emissions legislation pose a challenge for designers and calibrators during the warm-up phases of cold direct injection spark ignition (DISI) engines. To achieve catalyst light-off conditions in the shortest time, engine strategies are often employed that inherently use more fuel to attain higher exhaust temperatures. These can lead to the generation of locally fuel-rich regions within the combustion chamber and hence the formation and emission of particulates. To meet these emissions requirements, further understanding of the DISI in-cylinder processes during cold-start are required. This thesis investigates the effect of cooling an optical research engine to temperatures as low as -7°C, one of the legislative test conditions. A high-speed 9 kHz optical investigation of the in-cylinder combustion and fuel spray along with in-cylinder pressure measurements was completed with the engine motored and fired at 1500 rpm during combustion conditions that were essentially homogeneous and stoichiometric. Results showed significant differences between the flame growth structures at various operating temperature conditions with the notable presence of fuel-rich regions, which are understood to be prominent areas of particulate formation. Measured engine performance parameters such as indicated mean effective pressure (IMEP) and mass fraction burned (MFB) times correlated with the observed differences in combustion characteristics and flame growth speed. It was shown that flash boiling of the fuel spray was present in the fully heated engine case and significantly reduced the penetration of the spray plume and the likelihood of piston crown and cylinder liner impingement. The flow and combustion processes of a transient production cold start-up strategy were analysed using high-speed particle image velocimetry (HSPIV). Results highlighted a broad range of flame structures and contrasting flame stoichiometry occurring at different times in the start-up process. Turbulent flow structures were identified that have an effect on the fuel spray development and combustion process as well as providing a path for cold-start emissions reduction. PN and transient hydrocarbon (HC) emissions were measured at cold conditions to further elucidate the effect of operating temperature and correlate emissions data with in-cylinder measurements. A clear link between the quantity and size range of particulate and HC emissions and operating temperature was shown and the precise in-cylinder location of HC emissions, caused by fuel impingement, was inferred from the HC emissions data.
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Bendazzoli, Claudio <1978>. "Il corpus DIRSI: creazione e sviluppo di un corpus elettronico per lo studio della direzionalità in interpretazione simultanea." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2010. http://amsdottorato.unibo.it/3081/.
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Con questa tesi abbiamo messo a punto una metodologia per l'applicazione del "corpus-based approach" allo studio dell'interpretazione simultanea, creando DIRSI-C, un corpus elettronico parallelo (italiano-inglese) e allineato di trascrizioni di registrazioni tratte da convegni medici, mediati da interpreti simultaneisti. Poiché gli interpreti professionisti coinvolti hanno lavorato dalla lingua straniera alla loro lingua materna e viceversa, il fattore direzionalità è il parametro di analisi delle prestazioni degli interpreti secondo i metodi di indagine della linguistica dei corpora.
In this doctoral thesis a methodology was developed to fully apply the corpus-based approach to simultaneous interpreting research. DIRSI-C is a parallel (Italian-English/English-Italian) and aligned electronic corpus, containing transcripts of recorded medical international conferences with professional simultaneous interpreters working both from and into their foreign language. Against this backdrop, directionality represents the research parameter used to analyze interpreters' performance by means of corpus linguistics tools.
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Dimou, Iason. "Particulate matter emissions from a DISI engine under cold-fast-idle conditions for ethanol-gasoline blends." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/67777.
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Thesis (Nav. E. and S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2011.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 81-83).
In an effort to build internal combustion engines with both reduced brake-specific fuel consumption and better emission control, engineers developed the Direct Injection Spark Ignition (DISI) engine. DISI engines combine the specific higher output of the spark ignition engine, with the better efficiency of the compression ignition engine at part load. Despite their benefits, DISI engines still suffer from high hydrocarbon, NO2 and particulate matter (PM) emissions. Until recently, PM emissions have received relatively little attention, despite their severe effects on human health, related mostly to their size. Previous research indicates that almost 80% of the PM is emitted during the first few minutes of the engine's operation (cold-start-fast-idling period). A proposed solution for PM emission reduction is the use of fuel blends with ethanol. The present research experimentally measures the effect of ethanol content in fuel on PM formation in the combustion chamber of a DISI engine during the cold-start period. A novel sampling system has been designed and combined with a Scanning Mobility Particle Sizer (SMPS) system, in order to measure the particulate matter number (PN) concentration 15 cm downstream from the exhaust valves of a DISI engine, for a temperature range between 0 and 40"C, under low load operation. Seven gasohol fuels have been tested with the ethanol content varying from 0% (EO) up to 85% (E85). For E10 to E85, PN modestly increases when the engine coolant temperature (ECT) is lowered. The PN distributions, however, are insensitive to the ethanol content of the fuel. The total PN for EQ is substantially higher than for the gasohol fuels, at ECT below 20'C. However, for ECT higher than 20'C, the total PN values (obtained from integrating the PN distribution from 15 to 350 nm) are approximately the same for all fuels. This sharp change in PN from EQ to E10 is confirmed by running the tests with E2.5 and E5; the midpoint of the transition occurs at approximately E5. Because the fuels' evaporating properties do not change substantially from EQ to E10, the significant change in PN is attributed to the particulate matter formation chemistry.
by Iason Dimou.
Nav.E.and S.M.
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Naranjo, Rafael Ricardo Avila. "Alternatives to the use of the crowbar circuit in DFIG based wind turbines during balanced voltage dips." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/3/3143/tde-30122014-112624/.
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Most of the modern wind turbines are based on doubly fed induction generators (DFIG), with a back to back power converter connecting the rotor to the network. It is known that voltage dips at the stator terminals can cause overcurrents in the rotor windings, which could threaten the converter integrity. In order to protect the converter, several strategies have been proposed in technical literature, requiring in some cases the converter deactivation, which disables the control that the converter has over the power transference between the generator and the system. This last is not a desirable behavior since it can put on risk the voltage stability of the electric system. It is the aim of this dissertation to introduce and compare five of those protection strategies, through the computational simulation of their performance in case of balanced voltage dips. In order to achieve this, the electromagnetic dynamic model of the DFIG was theoretically developed, as well as the models of the strategies of interest. Subsequently, the computational model of the system was assembled in the software Matlabs Simulink to finally perform the desired simulations and its corresponding analysis.A maioria das turbinas eólicas modernas é baseada em geradores de indução duplamente alimentados (GIDE), com um back to back conversor de energia que liga o rotor para a rede. Sabe-se que as quedas de tensão nos terminais do estator podem causar sobrecorrentes nos enrolamentos do rotor, que podem ameaçar a integridade do conversor. A fim de proteger o conversor, várias estratégias têm sido propostas na literatura técnica, exigindo, em alguns casos, a desativação do conversor, o qual desativa o controlo do conversor, que possui ao longo da transferência de energia entre o gerador e o sistema. Este último não é um comportamento desejável, uma vez que pode colocar em risco a estabilidade de tensão do sistema elétrico. É o objetivo desta dissertação apresentar e comparar cinco dessas estratégias de proteção, através da simulação computacional de seu desempenho em caso de quedas de tensão equilibrada. A fim de alcançar este objetivo, o modelo dinâmico eletromagnética do DFIG teoricamente foi desenvolvido, bem como os modelos das estratégias de interesse. Subsequentemente, o modelo computacional do sistema foi montado no software Simulink do Matlab para finalmente executar as simulações desejadas e sua análise correspondente.
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Kundu, Dipti Sankar Verfasser], and Siegfried [Akademischer Betreuer] [Blechert. "Synthesis of microporous polymeric BINOL-deríved phosphoric acids and applications in hetererogeneous asymmetric organocatalysis / Dipti Sankar Kundu. Betreuer: Siegfried Blechert." Berlin : Universitätsbibliothek der Technischen Universität Berlin, 2012. http://d-nb.info/1026483786/34.
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Rimmer, John E. T. "An optical investigation into the effect of fuel spray, turbulent flow and flame propagation on DISI engine performance." Thesis, Loughborough University, 2011. https://dspace.lboro.ac.uk/2134/8363.
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There is currently considerable interest in new engine technologies to assist in the improvement of fuel economy and the reduction of carbon dioxide emissions from automotive vehicles. Within the current automotive market, legislative and economic forces are requiring automotive manufacturers to produce high performance engines with a reduced environmental impact and lower fuel consumption. To meet these targets, further understanding of the processes involved in in-cylinder combustion is required. This thesis discusses the effect of fuel spray structure, flame propagation and turbulent flow on DISI engine combustion. To investigate these flow processes within the fired single cylinder Jaguar optical engine a number of optical measurement techniques have been used, including high speed laser sheet flow visualisation (HSLSFV) and high speed digital particle image velocimetry (HSDPIV). Results obtained from dual location flame imaging has provided further understanding of the relationship between flame growth, engine performance and cycle-to-cycle variation. Detailed correlation analysis between flame growth speed and engine performance parameters demonstrated that it is the flow conditions local to the spark plug at the time of spark ignition that have greatest influence on combustion. It was also demonstrated that further gains in engine performance and stability can be achieved by optimising the fuel injection timing. The temporal and spatial development of flow field structures within the pent-roof combustion chamber at the time of spark ignition were quantified using HSDPIV. Decomposition analysis of the raw velocity data enabled the relationship between specific scales of turbulent flow structure and engine performance parameters to be investigated. Correlations between the high frequency turbulence component and pressure derivatives are shown, demonstrating that it is the frequencies of motion >600 Hz that have the greatest influence on early flame development and therefore rate of charge consumption, engine performance and combustion stability. A series of double fuel injection strategies were devised to investigate the potential for using the fuel injection event to influence flow field structures within the cylinder. Results demonstrated that while the fuel injection event had limited impact on bulk flow structures, there was an increase in turbulence post fuel injection, depending on the timing of the second injection pulse. However, this advantage was not sustained throughout the compression stroke to have significant impact on combustion. The final stage of research investigated fuel spray structure, flame propagation and charge motion at fuel impingement locations, comparing a single and triple injection strategy. A triple injection strategy is proposed that results in an improvement in the levels of fuel impingement on combustion chamber walls and a reduction in the high luminosity regions within the flame. Consequently, adopting the multiple injection strategy highlighted the potential for reducing unburned HC emissions and soot formation within homogeneous charge DISI engines.
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Walker, L. J. "The effects of the disposal of organophosphate and synthetic pyrethroid sheep dips on non-target organisms on farmland." Thesis, Durham University, 2004. http://etheses.dur.ac.uk/2966/.
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The 1998 Groundwater Regulations required spent organophosphate and synthetic pyrethroid sheep dip to be disposed to farmland. The effects of dip disposal on soil invertebrates and the possible consequences for their bird predators were investigated on farms across Britain between 1999 and 2002.A preliminary survey of dip disposal practice on 42 hill farms on, or adjacent to SSSls that support breeding waders, exposed a wide variety of practices and considerable deviation from the recommended procedures in many cases. Paired disposal and control sites were sampled on a subset of the surveyed farms. Invertebrate abundance was estimated by taking soil samples, followed by Berlese extraction (or hand sorting for worms), pitfall trapping and suction sampling. Invertebrate densities on disposal sites were significantly lower than on control sites in 7 out of 15 cases and the multivariate analysis indicated significant effects of dip disposal on carabid, but not spider, species composition six months after application. Density reductions were greatest on areas that had been used for dip disposal over many years. Plots were set up in a "Latin-square" design on two experimental farms, allowing comparison of the effects of the two insecticides at two dilutions under controlled conditions. The same sampling methods were used as on the farm sites and densities of all invertebrate groups, except linyphiid spiders and carabid beetles, were significantly reduced on the disposal plots on one or more sampling occasion after application. Soil surface invertebrates taken by suction sampling showed the most severe and consistent reductions. A risk assessment suggests that spring disposal could compromise upland wading chick survival. However, the current scale of dip disposal in Britain does not pose a threat to whole bird populations.
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Ormond, Adam. "The influence of valve timing and other features on the combustion and emissions characteristics of a DISI engine." Thesis, University of Nottingham, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.442289.
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Avadhany, Sareena. "Analysis of various fuels in DISI and PFI engines : separating mixing effects from crevice and quench layer effects." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/86269.
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Thesis: S.B., Massachusetts Institute of Technology, Department of Mechanical Engineering, June 2013.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 43-44).
The United States consumes billions of gallons of gasoline per year, threatening national security and causing environmental problems. Research in automotive research aims to resolve such problems. Solutions include turbocharged direct injection, spark ignition (DISI) engines for higher output and efficiency. But this comes at the cost of greater concentrations of unburned hydrocarbons (UBHC) in the exhaust during cold start, when the catalytic converter is further away from the engine. The time the catalytic converter takes to heat to an optimum efficiency is longer. UBHC can also accumulate in the cylinder chambers and can be caused by quenching effects or poor mixing. A system was set up to determine the significance of mixing in producing high concentrations of UBHC. A GM 2009 LNF Ecotec was modified to run PFI and DISI under operating conditions representative of cold start for isopentane, and gasoline with varying concentrations of ethanol. Results were inconclusive, indicating no relationship between neither the UBHC count in the exhaust of increasing ethanol concentration, nor differences between PFI and DISI. To make test results more reliable, more ethanol containing fuel types should be tested, and a sweep of spark times should be assessed. The set up does provide a good foundation for further studies in mixing research.
by Sareena Avadhany.
S.B.
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Hindi, Gustavo de Queiroz. "3D numerical investigation of mixture formation and combustion in a DISI engine at part-load under stratified operation." Instituto Tecnológico de Aeronáutica, 2011. http://www.bd.bibl.ita.br/tde_busca/arquivo.php?codArquivo=2022.
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This work investigates through numerical simulation, the operation of a big bore direct fuel injection spark ignition engine, at part load under stratified operation. It evaluates fuel-air mixture preparation and combustion process with the adoption of detailed chemical kinetics mechanisms for both Isooctane and Ethanol, and applying adaptive mesh refinement to capture the turbulent flame brush. The investigation is split in 3 main parts. In the first part, with Isooctane as fuel, the impact of in-cylinder turbulence level induced by squish has shown that the attempt to isolate the squish ratio, maintaining the bowl shape, for the evaluated cases have led to a scenario not more appropriate for flame initiation and propagation for 2 of the 3 geometries. But the observations made during this initial stage have led to the proposal of a fourth geometry to improve the mixture formation and combustion process. As it was seen the combustion process was about 11.5 deg faster with the new piston bowl proposed. In the second part, still with Isooctane and maintaining the new proposed piston, evaluates the influence of two types of hollow cone fuel injectors, an inwardly and an outwardly opening types, where maintain fixed spark timing, the end of injection is varied and compared among the two cases, while targeting for the same gross IMEP output. The main results are that the outwardly opening injector case resulted in better fuel-air mixture preparation, even with a late end of injection. This led to higher combustion efficiency and lower unburned hydrocarbon, CO and soot emissions, while increasing NOx emissions. The 10-90% MFB burn
duration is higher for the outwardly opening injector case. In the last part the outwardly opening spray injector from the previous part, but using Ethanol as fuel has shown that to attain the same IMEP level the injected fuel mass is increased with Ethanol, and with its higher latent heat of vaporization, the time required to have an ignitable fuel-air mixture more than doubled that for the Isooctane case. Another important effect of these is the excessive increase of THC emissions. The overall combustion duration was faster for the Ethanol, mainly as the last part of the combustion was almost twice as fast as for the Isooctane case. It may be a consequence of a more homogeneous fuel-air mixture cloud as the fuel has more time to diffuse as the EOI is more advanced. The in-cylinder charge cooling effect of Ethanol led to a reduction in the in-cylinder temperature, leading to a reduction in NOx formation. CO emissions was also lowered, which is maybe attributed to either the reduced chemical dissociation with the lower temperatures, or reduced fuel rich regions. The reduced fuel rich regions also explain the reason for lower soot emissions.
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Behringer, M. K. "Effect of ethanol and butanol content in future fuel blends on spray and combustion characteristics in DISI engines." Thesis, University College London (University of London), 2014. http://discovery.ucl.ac.uk/1426613/.
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Direct Injection Spark Ignition has become popular within the automotive industry due to the flexibility in injection strategies. This, along with the introduction of novel fuels such as mixtures of ethanol or butanol with gasoline, requires new understanding of the air-fuel mixture preparation and combustion as fuel properties vary greatly. The motored engine flow field of an optical research engine was characterised using Laser Doppler Velocimetry and Particle Image Velocimetry and analysed regarding turbulence properties at the world wide mapping point. The intake flow effect on the spray of a pressure swirl injector was investigated using the base fuels gasoline, isooctane, ethanol and butanol. Furthermore, low percentage splash blended mixtures of 25 % ethanol and 16 % or 25 % butanol with the reference fuels were created and geometrical spray features were obtained from high speed imaging along with the droplet sizes using Phase Doppler Anemometry. Spray investigations were also under taken in a quiescent environment with a more modern spark eroded multi hole injector and its direct replacement featuring a novel Laser drilled nozzle. The results highlight the strong effect of the fuel type, where especially pure butanol showed largest difference to the baseline fuels in terms of shape along with a significant increase of the droplet size. Ethanol also showed an increase in droplet size but only small differences to gasoline’s spray shape at 80 bar or 120 bar fuel pressure into 0.5 bar or 1 bar ambient air at 20 °C, for fuel temperatures of 20 °C or 80 °C. The ethanol mixture was typically more similar to gasoline than the butanol blends. Thermodynamic parameters were derived using incylinder pressure analysis for stoichiometric (λ=1) and lean (λ=1.2). Additionally, high speed chemiluminescence imaging was used at gasoline’s maximum break torque spark timing, calculating flame radii, radius growth, roundness and centroid development. Further analysis was using flame tomography for better insight into the early stages after ignition and the flame front characteristics for the base fuels only. Overall, the analysis showed little difference between gasoline and the blends, but showed changes for the pure alcohols with typically much faster flame progression of ethanol and issues with the combustion of butanol at low engine temperatures. The tomography analysis returned similar flame structures for the pure fuels, what is confirmed by their location in combustion diagrams.
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Bartolucci, Alberto. "Morphological characterization of ZnS thin films for photovoltaic applications." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amslaurea.unibo.it/10540/.
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Le celle solari a film sottile sono tra le alternative più promettenti nel campo fotovoltaico. La ricerca di materiali non tossici ed economici per la passivazione delle superfici è di fondamentale importanza. Il presente è uno studio sulla morfologia di film sottili di ZnS. I campioni analizzati sono stati cresciuti tramite DC sputtering a diversa potenza (range 50-150W) per studiare le connessioni tra condizioni di deposizione e proprietà strutturali. Lo studio è stato condotto mediante acquisizione di mappe AFM. E' stata effettuata un'analisi dei buchi (dips) in funzione della potenza di sputtering, per individuare il campione con la minore densità di dips in vista di applicazioni in celle solari a film sottile. I parametri strutturali, quali la rugosità superficiale e la lunghezza di correlazione laterale sono stati determinati con un'analisi statistica delle immagini. La densità e dimensione media dei grani sono state ricavate da una segmentazione delle immagini. Le analisi sono state svolte su due campioni di ZnO per fini comparativi. Tramite EFM sono state ottenute mappe di potenziale di contatto. Tramite KPFM si è valutata la differenza di potenziale tra ZnS e un layer di Al depositato sulla superficie. La sheet resistance è stata misurata con metodo a quattro punte. Dai risultati la potenza di sputtering influenza la struttura superficiale, ma in maniera non lineare. E' stato individuato il campione con la minore rugosità e densità di dips alla potenza di 75 W. Si è concluso che potenze troppo grandi o piccole in fase di deposizione promuovono il fenomeno di clustering dei grani e di aumentano la rugosità e densità di dips. E' emersa una corrispondenza diretta tra morfologia e potenziale di contatto alla superficie. La differenza di potenziale tra Al e ZnS è risultata inferiore al valore noto, ciò può essere dovuto a stati superficiali indotti da ossidi. Il campione risulta totalmente isolante.
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Cardoso, Suleimy Marinho Fernandes. "AVALIAÇÃO DE VETORES DA DOENÇA DE CHAGAS NA ÁREA DE INFLUÊNCIA DIRETA DA USINA HIDRELÉTRICA CORUMBÁ IV, GOIÁS." Pontifícia Universidade Católica de Goiás, 2006. http://localhost:8080/tede/handle/tede/3055.
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Previous issue date: 2006-08-30The objective of this study was to evaluate the diversity of found vectors as well as their habitat preference and apatial distribution in a region around Brasília within the area of direct influence of the reservoir of the Corumbá IV hydroelectric power plant (UEH Corumbá IV) comparing the data with the history of occurrence and prevalence of the Chagas disease in the region and the environmental impact of the power plant. In canopies of guariroba palm trees (Syagrus oleraceae) and graveteiro nests (Phacellodomus rufifrons) 1981 triatomines (barbeiros) were collected belonging to the species Rhodnius neglectus, Panstrongylus neglectus, Panstrongylus diasi and Psammolestes tertius within February 19th 2005 and January 21st 2006. The triatomines were also searched for in armadillo holes, hen houses, and rural houses but no specimens were found. A parasitological examination was performed and none of the triatomines analyzed were contaminated by Trypanosoma cruzi despite the notification of Chagas disease cases in the surrounding cities of the study area. In conclusion, despite the presence of R. neglectus, pontecial vector, it was not possible to detect T. cruzi in the analyzed insects. However, the risk of human and triatomines infection should be carefully evaluated.
O objetivo deste trabalho foi fazer um levantamento de vetores encontrados, bem como sua preferência de habitat e a sua distribuição espacial, numa região do entorno de Brasília, dentro da área de influência direta da usina hidrelétrica Corumbá IV (UHE Corumbá IV), relacionando os dados com a história de ocorrência e prevalência da doença de Chagas na região e o provável impacto ambiental. Em copas de palmeiras guariroba (Syagrus oleracea) e ninhos de graveteiro (Phacellodomus rufifrons) foram coletados 1.981 triatomíneos (barbeiros), pertencentes às espécies Rhodnius neglectus, Panstrongylus geniculatus, Panstrongylus diasi e Psammolestes tertius, no período de 19 de fevereiro de 2005 a 21 de janeiro de 2006. Os triatomíneos também foram procurados em buracos de tatu, galinheiros e em residências rurais, mas nenhum espécime foi encontrado. Foi realizado exame parasitológico e nenhum dos triatomíneos analisados estavam contaminados pelo Trypanosoma cruzi, embora ocorra notificação de casos da doença de Chagas nas cidades vizinhas da região em estudo. Concluindo assim que, apesar da presença de R. neglectus potencial vetor, não foi possível constatar a presença do T. cruzi nos insetos examinados, porém o risco de infecção humana e de triatomíneos deve ser cuidadosamente avaliado.
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Wang, Disi [Verfasser], and Heinz Ulrich [Akademischer Betreuer] Hoppe. "A Model-driven Approach to Developing a Web-based Environment to Support Problem-based Learning / Disi Wang ; Betreuer: Heinz Ulrich Hoppe." Duisburg, 2019. http://d-nb.info/1191694283/34.
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Bdeir, Najat [Verfasser]. "A system for production of pure Influenza A virus defective interfering particles (DIPs) and assessment of their antiviral activity / Najat Bdeir." Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2021. http://nbn-resolving.de/urn:nbn:de:gbv:7-21.11130/00-1735-0000-0008-5900-4-1.
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Liu, Quan. "Planar laser induced fluorescence imaging and analysis with ethanol blended fuels in a direct injection spark ignition engine." Thesis, Brunel University, 2017. http://bura.brunel.ac.uk/handle/2438/14786.
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The currently reported thesis was concerned with visualisation of the charge homogeneity and cyclic variations within the planar fuel field near the spark plug in an optical spark ignition engine fitted with an outwardly opening central direct fuel injector. Specifically, the project examined the effects of fuel type and injection settings, with the overall view to understanding some of the key mechanisms previously identified as leading to particulate formation in such engines. The three fuels studied included a baseline iso-octane, which was directly compared to two gasoline fuels containing 10% (E10) and 85% (E85) volume of ethanol respectively. The engine was a bespoke single cylinder with Bowditch style optical access through a flat piston crown. Charge stratification was studied over a wide spectrum of injection timings using the Planar Laser Induced Fluorescence (PLIF) technique, with additional variation in charge temperature due to injection also estimated when viable using a two-line PLIF approach. Overall, both gasoline-ethanol fuels generally exhibited a higher degree of stratification, albeit at least partly alleviated with elevated rail pressures. Under both warm and cold liner conditions the E10 fuel showed clear evidence of fuel droplets persisting up until ignition. Interestingly, with late injection timing the repeatability of the injection was superior (statistically) with higher ethanol content in the fuel, which may have been associated with the higher charge temperatures aiding control of the evaporation of the main mass of alcohol. The findings were corroborated by undertaking a comprehensive study of the influence of varying fuel type and injection settings on thermodynamic performance and engine-out emissions during firing operation, with additional gas exchange effects also influencing the optimum fuel injection timings.
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Keller, Andrea. "Die Klassifikation psychischer Störungen nach DSM-IV mit Hilfe eines strukturierten Interviews (F-DIPS) eine Untersuchung der Retest-Reliabilität und der Validität /." [S.l. : s.n.], 2001. http://www.bsz-bw.de/cgi-bin/xvms.cgi?SWB9142824.
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Keller, Andrea. "Die Klassifikation psychischer Störungen nach DSM-IV mit Hilfe eines strukturierten diagnostischen Interviews (F-DIPS) eine Untersuchung der Retest-Reliabilität und der Validität /." [S.l.] : [s.n.], 2000. http://deposit.ddb.de/cgi-bin/dokserv?idn=961457236.
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Neuschwander, Murielle [Verfasser], Silvia [Gutachter] Schneider, and Tina [Gutachter] In-Albon. "Diagnostik und Klassifikation psychischer Störungen im Kindes- und Jugendalter : Anwendung des Kinder-DIPS / Murielle Neuschwander ; Gutachter: Silvia Schneider, Tina In-Albon ; Fakultät für Psychologie." Bochum : Ruhr-Universität Bochum, 2019. http://d-nb.info/1199613940/34.
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Stansfield, Phillip A. "The control of an unthrottled homogeneous DISI engine through reduced intake valve lift and duration : a study of the in-cylinder flows and charge formation." Thesis, Loughborough University, 2009. https://dspace.lboro.ac.uk/2134/12298.
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This research investigated a novel combustion system for gasoline direct injection spark ignition (DISI) engines. This combustion system burned an unthrottled, stoichiometric, homogenous charge at part load, in comparison to the unthrottled,lean, stratified charge burned by conventional DISI engines. Unthrottled homogeneous operation, enabled by the use of variable valve timing. allowed high fuel efficiencies to be achieved while addressing the particulate emissions, poor combustion stabilities and NOx after-treatment issues associated with stratified charge DISI engines, when compared to the port fuel injection (PFI) engines they are replacing. Experiments were performed to quantifY the bulk in-cylinder air motions, determine their effect on the fuel spray, and examine the resulting air-fuel mixture preparation of various early inlet valve closing (EIVC) and late inlet valve opening (LIVO) strategies that were suitable for controlling engine load under homogeneous engine conditions. A broad matrix of engine conditions has been investigated, with engine speeds ranging from idle (750 rpm) to 5000 rpm, and engine loads ranging from 2.7 bar indicated mean effective pressure (!MEP) to wide open throttle (WOT). Particle Image Velocimetry (PIV) was used to record mean in-cylinder flow fields in the tumble and swirl planes for a range of engine conditions and valve profiles. This included measurements at higher engine speeds (3500rpm) than previously published. Air flows in the difficult-to-access cylinder head were measured with Laser Doppler Anemometry (LDA) and the effect of these air flows on the fuel spray produced by a latest generation multi-stream fuel injector was investigated with Mie imaging. The resulting mixture preparation was then investigated over a crank angle period ranging from the start ofinjection (SOl) to the time of spark with Laser Induced Exciplex Fluorescence (LIE F). Supporting data from a thermodynamic sister engine with identical combustion chamber geometry was recorded at University College London. Unthrottled, homogeneous operation with low lift EIVC valve profiles improved engine fuel consumption by up to 20% compared to throttled operation with conventional, full-lift profiles. This was a consequence of a reduction in the throttling losses and improvements in air-fuel mixing. The intake air momentum was more significant than the fuel spray momentum from the injection system in determining the air-fuel mixing process. This resulted in engine performance being strongly affected by engine speed, intake valve lift and injection timing. The greatest benefits in ISFC occurred when only one of the two inlet valves was operated. This was attributed to an overall increase in the level ofin-cylinder swirl. However, the choice of which inlet valve was opened was critical, with greater gains occurring if the fuel spray from the centrally mounted injector was directed towards the spark plug than when the spray was directed away from the plug. EIVC combustion also exhibited significantly longer burn times than throttled operation. This was due to lower cylinder pressures that reduced the laminar flame speed and lower levels of turbulence around the spark plug at the time of ignition. Flame front measurements on the optical engine showed that during the longer early heat release phase (0-10% mass fraction burned), the flame kernel was transported away from the spark plug and towards the combustion chamber wall beneath the inlet valves. Investigations into the fuel mixture preparation using Laser Induced Exciplex Fluorescence (LIE F) demonstrated that, under high load conditions, a source of particulate emissions from PFI engines was large droplets in the vicinity of the spark plug around the time of ignition. These fuel rich regions were precursors in the generation of soot and were all but eliminated with direct injection fuelling strategies. Late Intake Valve Opening (LIVO) valve strategies generated a sub-atmospheric cylinder pressure of between 0.5 to 0.3bar (absolute). Spray images obtained under these conditions showed greater penetration of the fuel spray and a poorly defined spray cone boundary. Due to the increased momentum and increased shear forces of the inducted air, and the cylinder pressure falling below the saturation vapour pressure of some components of the gasoline fuel at the temperature of the mixture, flash evaporation of those components was seen to occur. The improvement in atomisation and faster burn rate with LIVO compensated to some extent for the increase in irrecoverable pumping work of this operating strategy over conventional EIVC. However, a practical disadvantage of LIVO was poor control of the trapped air mass, arising from the intake air momentum supercharging the engine cylinder at the conditions tested.
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Gianessi, Mattia. "Sviluppo di una app di ausilio per persone non vedenti per Android." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amslaurea.unibo.it/11653/.
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La tesi prevede lo sviluppo di una app di ausilio per persone non vedenti per ambiente Android.
L'applicazione ha due scopi principali: rilevazione degli ostacoli che l'utente incontra nel proprio cammino, tramite un apposito visore, con successivo invio di informazioni sugli ostacoli rilevati tramite output audio e tattili e realizzazione di una versione personalizzata di Google Maps che l'utente può utilizzare nella maniera più comoda e sicura possibile.
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Silva, Carlos Vinicius Machado. "Afundamentos de tensão na presença de geração distribuída." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2014. http://hdl.handle.net/10183/109163.
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A inserção de fontes de geração distribuída (GD) traz a possibilidade de diversificação da matriz energética e a redução de perdas elétricas no transporte de EE – porque as fontes localizam-se próximas aos clientes finais. Entre elas destacam-se as fontes fotovoltaicas, eólicas, pequenas centrais hidrelétricas (PCH) e termelétricas à biomassa. As duas primeiras, apresentam a peculiaridade de normalmente serem conectadas à rede através de inversores de frequência. As outras duas costumam ser conectadas diretamente ao sistema. Todavia, a GD também propicia consequências ao SEP, muitas vezes indesejadas, como variações nos parâmetros da qualidade da energia elétrica (QEE). O compromisso que se deve manter com a QEE entregue aos consumidores é de vital importância para as empresas transmissoras e distribuidoras de energia elétrica, bem como para os utilitários dessa EE. Além disso, para que haja o correto funcionamento de equipamentos eletrônicos e de diversos processos industriais é necessário que a energia elétrica permaneça em uma faixa de tensão aceitável. Entre os fenômenos de interesse da área de qualidade de energia elétrica, os quais devem ser eliminados ou mitigados para a melhor operabilidade do SIN, pode-se citar: harmônicos, flutuação de tensão, subtensão, sobretensão e afundamentos de tensão. Devido a observabilidade rotineira e aos prejuízos (financeiros e/ou técnicos) associados ao fenômeno, o interesse desse estudo consiste nos afundamentos de tensão. Nesse contexto, apresenta-se uma proposta para análise dos afundamentos de tensão em um ambiente com geração distribuída (fotovoltaica, eólica, PCH e termelétrica à biomassa) através de simulações de curtos-circuitos. Os resultados obtidos através da metodologia proposta mostram que a inserção de GD pode trazer uma variação no número de afundamentos de tensão e melhorar os níveis de tensão nas barras, sobretudo nos locais onde foram inseridas bem como em suas proximidades. Também, há redução no número de afundamentos de maior severidade os quais causam mais prejuízos e preocupação a operabilidade do SEP.The insertion of distributed generation (DG) sources brings the possibility of diversification of energy sources types and the reduction of electrical losses in the transport of EE - because the sources are located close to end users. Among these sources are photovoltaic, wind, small hydropower and biomass-fired power plants. The first two, are usually connected to the network through frequency inverters. The other two are usually connected directly to the system. However, DG also provides consequences to the electrical power system, often unwanted, such as variations in the parameters of power quality (PQ). The commitment should be retained with the power quality delivered to customers. Moreover, for the correct operation of electronic equipment and various industrial processes it is necessary that the voltage remains within an acceptable range. Among the phenomena of interest to electric power quality, which must be eliminated or mitigated, we can mention: harmonics, voltage fluctuation, undervoltage, overvoltage and voltage sags (dips). Due to losses (financial and/or technical) associated with the phenomenon, the interest of this study consists of the voltage sags. In this context, we present a proposal for analysis of voltage sags in an environment with distributed generation (photovoltaic, wind, thermal and biomass-fired power plants) through simulations of short circuits. The results obtained through the proposed methodology shows that the inclusion of DG can bring a change in the number of voltage sags and improve voltage levels in bars, especially in places where they were inserted and in its vicinity. Also, there is a reduction in the number of severe voltage sags which cause more harm and concern to end-users and utilities.
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Šlezingr, Jan. "Parametrizace mezních křivek odolnosti elektrických spotřebičů na krátkodobé poklesy a výpadky napětí." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2008. http://www.nusl.cz/ntk/nusl-217724.
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This master’s thesis work deal with diagnosis parameters immunity curves uniphase appliance on short - term voltage dips a interuption. Immunity curve is dependence smallest possible sizes RMS voltage for performance given to criteria function on time continuation voltage event. Curves of resistance is different for each electric appliance, and depending on the size and over-voltage network, the burden on resources and voltage during the event.. The goal of this work is to devise a methodology for measuring the implementation of parametric measurement limit curves of resistance for selected types of appliances.
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Axelberg, Peter. "On Tracing Flicker Sources and Classification of Voltage Disturbances." Doctoral thesis, Högskolan i Borås, Institutionen Ingenjörshögskolan, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:hb:diva-3416.
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Developments in measurement technology, communication and data storage have resulted in measurement systems that produce large amount of data. Together with the long existing need for characterizing the performance of the power system this has resulted in demand for automatic and efficient information-extraction methods. The objective of the research work presented in this thesis was therefore to develop new robust methods that extract additional information from voltage and current measurements in power systems. This work has contributed to two specific areas of interest.The first part of the work has been the development of a measurement method that gives information how voltage flicker propagates (with respect to a monitoring point) and how to trace a flicker source. As part of this work the quantity of flicker power has been defined and integrated in a perceptionally relevant measurement method. The method has been validated by theoretical analysis, by simulations, and by two field tests (at low-voltage and at 130-kV level) with results that matched the theory. The conclusion of this part of the work is that flicker power can be used for efficient tracing of a flicker source and to determine how flicker propagates.The second part of the work has been the development of a voltage disturbance classification system based on the statistical learning theory-based Support Vector Machine method. The classification system shows always high classification accuracy when training data and test data originate from the same source. High classification accuracy is also obtained when training data originate from one power network and test data from another. The classification system shows, however, lower performance when training data is synthetic and test data originate from real power networks. It was concluded that it is possible to develop a classification system based on the Support Vector Machine method with “global settings” that can be used at any location without the need to retrain. The conclusion is that the proposed classification system works well and shows sufficiently high classification accuracy when trained on data that originate from real disturbances. However, more research activities are needed in order to generate synthetic data that have statistical characteristics close enough to real disturbances to replace actual recordings as training data.
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Moda, Sunil Udaya Simha. "Computational Modeling and Analysis of Heavy Fuel Feasibility in Direct Injection Spark Ignition Engine." Wright State University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=wright1300120730.
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Ditrych, Marek. "Problematika vyhodnocování blokovacích podmínek rozvodny pomocí GOOSE zpráv." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2019. http://www.nusl.cz/ntk/nusl-400562.
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This master thesis focuses on problematics of GOOSE messages used for evaluation of blocking conditions of substations in the electrical power plant in Opatovice (EOP). Firstly, the thesis describes the multifunctional electrical protection relay 7SJ64 as well as GOOSE messages, that are run by protocol IEC 61850. Next, it contains a brief description of the energy consumption of EOP itself, since the project was written for its protection relays. In the practical part of the thesis, an experimental network consisting of two distinct substations with three 7SJ64 multifunctional protection relays was designed together with simple blocking conditions. These require information about the state of circuit breakers. The whole communication is carried by GOOSE messages. Moreover, to inform about the loss of GOOSE messages, the logical function SI_GET_S (decoder) was used inside the coding interface of DIGSI programme called CFC. This function was then tested in the experimental network using each different condition, that experienced interruptions of communication caused either by simulated defect of optical cabels, or by „user‘s mistakes“ in the settings of communication parameters in DIGSI. Finally, the system protecting from the loss of GOOSE messages was incorporated into the existing project evaluating blocking conditions in the block substation of EOP.
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Olufe, Oludare Joseph. "Study of Production Drifts Stability and Assessment of Reinforcement Requirements at LKAB Konsuln Test-Mine Levels 436 and 486 Using Geologic Structures Data, and Modelling Software – Dips and Unwedge: a Part of dp1 Project (Mine Layout and Technology) of the Sustainable Underground Mining (Sum) Project." Thesis, Uppsala universitet, Institutionen för geovetenskaper, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-434644.
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Study of Production Drifts Stability and Assessment of Reinforcement Requirements at LKAB Konsuln Test-Mine Levels 436 and 486 Using Geologic Structures Data, and Modelling Software - Dips and Unwedge: a Part of dp1 Project (Mine Layout and Technology) of the Sustainable Underground Mining (Sum) Project Oludare Joseph Olufe Global population has been on exponential increase over the past half century. The population explosion is driving massive urbanization and infrastructure developments across the globe, which result in huge demand for metals, especially steel. The trend is forecasted to continue to rise steeply in for the next two decades. This is putting enormous strain on metals mining, especially because new surface economic deposits are rare to come by. Therefore, mining is steadily going deeper in many of the mining destinations across the world. Mining at great depths present unique challenges, particularly regarding stability of excavations at depths. Rock falls, rock burst, excavation collapse are common occurrences associated with deep mining. In regions with high seismicity potentials the frequency and consequences could be very high. Over the past decade ground instability has become a significant challenge confronting mining at LKAB deep mines. There had been incidents that resulted in long term closure of sections of the mines, with resultant adverse economic impacts. More undesirable is loss of live of personnel. The study was conducted at the Konsuln test mine levels 436 and 486, aimed to investigate the impacts of geologic structures on excavations instability at depths, at the Kiruna iron ore mines, on one hand. And on the other hand, evaluate the influence of geologic structures on ground reinforcements at the mine. Structural data were collected and analysed using Dips program to define orientation of major structures. The results were used for wedge analysis and excavations stability modelling using Unwedge program. Important rock mechanical parameters were defined based on data provided, and others based on literatures. A design factor of safety of 1.5 was used. Results from the study established that structures have significant impact on excavations instability at the Konsuln mine. 100% of the production drifts studied has minimum of four wedges formed in its perimeters. Out of this approximately 37% has factor of safety lower than 1.5. Evaluation of reinforcements (shotcrete and rock bolts) implemented in the mine found that approximately 15% of the total wedges formed in the production drifts has factor of safety less that 1.5 after both shotcrete and rock bolt reinforcements had been implement. Also, approximately 5% of the total wedges has apex height longer the rock bolt length. It was therefore concluded that structurally induced instability is a major contributor to excavations instability at the Kiruna mine. The study approach presented a new methodology to understand and provide robust solution to ground instability problem at the mine.
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Švindrych, Jan. "Vyhodnocování napěťových událostí s ohledem na odolnost spotřebičů." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2008. http://www.nusl.cz/ntk/nusl-217198.
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This diploma thesis deals with evaluation of voltage events regarding to immunity of electric appliances. This thesis is divided into three logical sections. In the first part are shown the voltage events, their definitions, causes and spreading in the mains. The second part deals with measurements and existing possibilities of evaluation of voltage events. The third part deals with suggestion of new evaluation of voltage events regarding to immunity of electric appliances and verification in practice.
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Pérez, Fernández Enrique. "Nuevo método de detección y análisis en tiempo real de eventos en la tensión de suministro de energía eléctrica empleando un modelo combinado wavelets-filtro de Kalman extendido." Doctoral thesis, Universidad de Cantabria, 2006. http://hdl.handle.net/10803/10634.
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La tesis doctoral presenta un nuevo método de detección y análisis de eventos en la tensión de suministro de energía eléctrica que utiliza simultáneamente el análisis wavelet y un filtro de Kalman extendido actuando en paralelo sobre las muestras de la tensión. El análisis wavelet proporciona la mejor precisión en la determinación de las características temporales del evento y el filtro de Kalman extendido permite, por un lado confirmar la existencia del evento, descartando aquellas detecciones erróneas que puede producir el análisis wavelet debido a su muy alta sensibilidad, así como determinar con la mayor exactitud la magnitud y fase de la tensión durante el evento.El método desarrollado se ha implementado un tiempo real sobre un sistema DSP, de forma que se adquieren las muestras de la tensión y se analizan sus valores dentro del intervalo de muestreo, para poder detectar y analizar eventos en el menor tiempo posible y poder desarrollar estrategias de protección de los distintos equipos conectados a la red de distribuciónThe thesis presents a new method for detection and analysis of voltage events in power systems using wavelet analysis and an extended Kalman filter acting in parallel on the voltage samples. The wavelet analysis provides the best estimation of the time-related parameters of the voltage event and the extended Kalman filter enables, on the one hand the confirmation of the beginning and the end of the voltage event, avoiding the erroneous detections that can be produced due to the very high sensitivity of the wavelet analysis, and on the other hand, the estimation of the magnitude and phase angle of voltage supply during the event. The method proposed has been implemented in a DSP-based system, where the voltage samples are analyzed within the sampling period for real-time detection of voltage events.
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Arnett, Natalie Yolanda. "Synthesis and Characterization of Disulfonated Poly(Arylene Ether Sulfone) Random Copolymers as Multipurpose Membranes for Reverse Osmosis and Fuel Cell Applications." Diss., Virginia Tech, 2009. http://hdl.handle.net/10919/26662.
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The results described in this dissertation focus on the synthesis and utilization of several disulfonated poly(arylene ether) random copolymer membranes in fuel cell and reverse osmosis applications. Poly(arylene ether)s were prepared by direct step copolymerization using a third monomer 3,3–-disulfonated 4,4–-dichlorodiphenylsulfone. The membrane properties of a 4,4–-biphenol-based disulfonated poly (arylene ether sulfone) random copolymer (BPS-35), optionally blended with various fluorine containing polymers or unsulfonated biphenol-based poly (arylene ether sulfone)s (Radel R) were investigated for fuel cell applications. Fluorine containing copolymers used included with 2,2–-hexafluoroisopropylidene 4,4–-biphenol based unsulfonated (6F-00) or disulfonated (6FS-35 and 6FS-60) PAES, hexafluoroisopropylidene biphenol based 4,4–-difluoro phenyl phosphine oxide) (6FPPO), and poly(vinylidene fluoride) (Kynar®). Tapping mode atomic force microscopy (TM-AFM) images of the membranes with 10 wt% of fluorinated copolymers showed macroscopic phase separation. Good miscibility between the copolymers at low concentrations was also confirmed by the observation of only one glass transition temperature. Compared to the benchmark Nafion 1135, the 10wt% blends of the fluorinated copolymers afforded a considerable reduction in the methanol permeabilities, which is important for direct methanol fuel cells (DMFC). The best DMFC performance with 0.5 M methanol fuel was illustrated with blends containing 10 wt% 6FS-00. At higher methanol concentrations (up to 2.0 M) BPS-35/6FS-00 (90/10) membranes outperformed both Nafion membranes.
Blends of BPS-35 blends with 6FS-35 or Radel R were also used as RO membranes. The highest salt rejections of 97.2 and 98.0% were obtained from BPS35/Radel R (90:10) and BPS-35/6FS-35 (95:5) blends, respectively in the salt form.
A systematic study of the preparation of BPS-20 random copolymer skin-core asymmetric membranes by diffusion induced phase separation (DIPS) from various polar aprotic solvent or cosolvent systems is reported. The best aprotic solvents to generate an asymmetric structure were NMP and DMAc whereas tetrahydrofuran (THF)/ formamide (FAm) (80/20 v/v) mixtures proved to be the best co-solvent systems. Acetone was the best non-solvent to prepare asymmetric membranes from both aprotic solvents and co-solvent mixtures. Overall, asymmetric membranes prepared from THF/FAm co-solvent mixtures illustrated the most stable phase separated morphology that was free of macrovoids. However, thicker skins (~5 μM) were formed due to the high volatility of THF. Therefore, ultra-thin skin thin film composites (TFC) based on BPS-20 in diethylene glycol (Di(EG) were prepared. Thermal treatment of these TFC was conducted at 90 °C and the addition of 20 wt% glycerin to the casting formulation helped to prevent pore collapse in the porous Udel polysulfone. A minimum of three coats was required to obtain a dense, smooth, and pinhole free skin layer. The generation of three dimensional (ternary) solubility parameter phase diagrams based on experimental data was formulated and a region of solubility based on the solubility parameters of the aprotic solvents and the different co-solvent systems was established for BPS-20.Ph. D.
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Sadeghi, Mehdi. "Potential of the Empirical Mode Decomposition to analyze instantaneous flow fields in Direct Injection Spark Ignition engine : Effect of transient regimes." Thesis, Orléans, 2017. http://www.theses.fr/2017ORLE2069/document.
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Cette étude introduit une nouvelle approche appelée Bivariate 2D-EMD pour séparer le mouvement organisé à grande échelle, soit la composante basse fréquence de l’écoulement des fluctuations turbulentes, soit la composante haute fréquence dans un champ de vitesse instantané bidimensionnel.Cette séparation nécessite un seul champ de vitesse instantané contrairement aux autres méthodes plus couramment utilisées en mécanique des fluides, comme le POD. La méthode proposée durant cette thèse est tout à fait appropriée à l’analyse des écoulements qui sont intrinsèquement instationnaires et non linéaires comme l'écoulement dans le cylindre lorsque le moteur fonctionne dans des conditions transitoires. Bivariate 2D-EMD est validé à travers différents cas test, sur un écoulement turbulent homogène et isotrope (THI) expérimental, qui a été perturbé par un tourbillon synthétique de type Lamb-Ossen, qui simule le mouvement organisé dans le cylindre. Enfin, Il est appliqué sur un écoulement expérimental obtenu dans un cylindre et les résultats de la séparation d'écoulement sont comparés à ceux basés sur l'analyse POD. L’évolution d’écoulement dans le cylindre pendant le fonctionnement du moteur transitoire, c’est à dire une accélération du régime moteur de 1000 à 2000tr/min en différentes rampes, sont mesurée en utilisant de PIV 2D-2C haute cadence. Les champs de vitesse sont obtenus dans le plan de tumble dans un moteur un moteur GDI mono-cylindre transparent et forment une base de données nécessaire pour valider les résultats de simulation numériqueThis study introduces a new approach called Bivariate 2D-EMD to separate large-scale organizedmotion i.e., flow low frequency component from random turbulent fluctuations i.e., high frequency onein a given in-cylinder instantaneous 2D velocity field. This signal processing method needs only oneinstantaneous velocity field contrary to the other methods commonly used in fluid mechanics, as POD.The proposed method is quite appropriate to analyze the flows intrinsically both unsteady and nonlinearflows as in in-cylinder. The Bivariate 2D-EMD is validated through different test cases, by optimize itand apply it on an experimental homogeneous and isotropic turbulent flow (HIT), perturbed by asynthetic Lamb-Ossen vortex, to simulate the feature of in-cylinder flows. Furthermore, it applies onexperimental in-cylinder flows. The results obtained by EMD and POD analysis are compared. Theevolution of in-cylinder flow during transient engine working mode, i.e., engine speed acceleration from1000 to 2000 rpm with different time periods, was obtained by High speed PIV 2D-2C. The velocityfields are obtained within tumble plane in a transparent mono-cylinder DISI engine and provide a database to validate CFD
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van, Rensburg Karel Jensen. "Analysis of arcing faults on distribution lines for protection and monitoring." Queensland University of Technology, 2003. http://eprints.qut.edu.au/15800/.
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This thesis describes an investigation into the influences of arcing and conductor deflection due to magnetic forces on the accuracy of fault locator algorithms in electrical distribution networks. The work also explores the possibilities of using the properties of an arc to identify two specific types of faults that may occur on an overhead distribution line. A new technique using the convolution operator is introduced for deriving differential equation algorithms. The first algorithm was derived by estimating the voltage as an array of impulse functions while the second algorithm was derived using a piecewise linear voltage signal. These algorithms were tested on a simulated single-phase circuit using a PI-model line. It was shown that the second algorithm gave identical results as the existing dynamic integration operator type algorithm. The first algorithm used a transformation to a three-phase circuit that did not require any matrix calculations as an equivalent sequence component circuit is utilised for a single-phase to ground fault. A simulated arc was used to test the influence of the non-linearity of an arc on the accuracy of this algorithm. The simulations showed that the variation in the resistance due to arcing causes large oscillations of the algorithm output and a 40th order mean filter was used to increase the accuracy and stability of the algorithm. The same tests were performed on a previously developed fault locator algorithm that includes a square-wave power frequency proximation of the fault arc. This algorithm gave more accurate and stable results even with large arc length variations. During phase-to-phase fault conditions, two opposing magnetic fields force the conductors outwards away from each other and this movement causes a change in the total inductance of the line. A three dimensional finite element line model based on standard wave equations but incorporating magnetic forces was used to evaluate this phenomenon. The results show that appreciable errors in the distance estimations can be expected especially on poorly tensioned di stribution lines.New techniques were also explored that are based on identification of the fault arc. Two methods were successfully tested on simulated networks to identify a breakingconductor. The methods are based on the rate of increase in arc length during the breaking of the conductor. The first method uses arc voltage increase as the basis of the detection while the second method make use of the increase in the non-linearity of the network resistance to identify a breaking conductor. An unsuccessful attempt was made to identifying conductor clashing caused by high winds: it was found that too many parameters influence the separation speed of the two conductors. No unique characteristic could be found to identify the conductor clashing using the speed of conductor separation. The existing algorithm was also used to estimate the voltage in a distribution network during a fault for power quality monitoring purposes.
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Gibelli, Gerson Bessa. "Resposta dinâmica dos motores de indução trifásicos a afundamentos de tensão na rede de alimentação." Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/18/18154/tde-06072009-092748/.
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Esta pesquisa apresenta um estudo da resposta dinâmica dos motores de indução trifásicos submetidos a afundamentos de tensão. As simulações computacionais sobre um sistema de distribuição, assim como a modelagem dos motores de indução trifásicos baseada em dados reais, foram realizadas utilizando-se do software ATP (Alternative Transients Program). Estas tiveram por objetivo gerar situações representativas da operação do sistema elétrico de potência (SEP), caracterizando afundamentos de tensão, fenômenos estes pertencentes à classe de variações de tensão de curta duração (VTCD), no contexto da qualidade da energia elétrica (QEE). Da observação destes afundamentos, verificaram-se as situações que vieram ou não, a comprometer a alimentação do equipamento analisado e, conseqüentemente, seu desempenho. Pelos resultados observados, evidencia-se que a metodologia de análise aplicada é satisfatória e condizente com o encontrado em situações reais de operação dos motores de indução trifásicos, denotando certas características intrínsecas no contexto das VTCDs.This research shows a study on the dynamic response of three-phase induction motors submitted to voltage sags. Computer simulations about a distribution system, as well as the modeling of three-phase induction motors based on actual data, were made using ATP (Alternative Transients Program) software. These simulations intended to generate representative situations of the electrical power system (EPS) operation, characterizing voltage sags, which is a phenomenon belonging to the class of short duration voltage variations (SDVV), in the electrical power quality context (EPQ). From the observation of these sags, we verified the situations that jeopardized or not the supply of the analyzed equipment and, consequently, its performance. From the observed results, it becomes evident that the methodology of the applied analysis is satisfactory and in agreement with the one found in actual situations of three-phase induction motors operations, indicating certain characteristics intrinsic to the SDVV context.
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Baroni, Riccardo. "Limitazione delle emissioni di particolato nei motori ad accensione comandata." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2017.
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Le grandi quantità di particolato emesse dai motori a combustione interna possono essere fonte di malattie cardiovascolari e respiratorie oltre a possedere un ancora indefinito potere cancerogeno.
Lo sviluppo nel tempo della normativa dei trasporti ha portato ad un abbattimento significativo del particolato nei motori ad accensione per compressione, ritenuti i principali produttori di polveri nel panorama dei veicoli europei, trascurando così la controparte ad accensione comandata, reputata sicura da questo punto di vista.
La continua ricerca per migliorare i consumi e limitare le emissioni di gas clima-alteranti ha favorito lo sviluppo dei motori ad accensione comandata ad iniezione diretta, tecnologia che garantisce un miglioramento del rendimento termodinamico, una maggior potenza specifica oltre che una miglior elasticità di erogazione del motore stesso. Purtroppo questa scelta aumenta significativamente le polveri emesse dai motori alimentati a benzina (oltre a diminuirne il diametro e quindi aumentarne la pericolosità), che fino ad una decina di anni fa, con l’esclusivo utilizzo di iniezione nei collettori di aspirazione, producevano una quantità di particolato trascurabile.
Questo elaborato si propone di capire perché è necessario limitare le emissioni di PM analizzando i suoi effetti sul corpo umano; alla luce dei risultati riscontrati si propongono alcune soluzioni per la limitazione delle polveri nei motori GDI per garantire il rispetto della più recente normativa EURO 6c (settembre 2017). Le soluzioni proposte coinvolgono gli apparati di iniezione, di accensione e di scarico; queste sono attuate attraverso la modifica dei set up dei vari organi e grazie all’introduzione di apparati aggiuntivi come quello del GPF, un filtro antiparticolato appositamente studiato per l’implementazione nei motori alimentati a benzina.
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Mojsilovic, Ognjen. "Estimating bioaccessibility, phytoavailability and phytotoxicity of contaminant arsenic in soils at former sheep dip sites." Lincoln University, 2009. http://hdl.handle.net/10182/1142.
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Recognition that the bioavailability of soil As (As) is influenced by its soil dynamics has initiated research into development of more accurate, site-specific soil guideline values, departing from the assumption that the total soil As content is bioavailable. With the aim of deriving predictive models, the relationship between soil properties and As bioavailability (bioaccessibility and phytotoxicity) was examined on a set of naturally contaminated sheep dip soils (n = 30). Sampled soils were extensively characterised, bioaccessibility was estimated through an in vitro procedure, and soil As toxicity and availability to plants were evaluated using an early growth wheat bioassay. The in vitro bioaccessibility was consistently less than the total soil As content. Arsenic bioaccessibility was negatively correlated to soil iron (Fe), manganese (Mn) and aluminium (Al) contents, and it was positively related to the soil As loading. The in vitro extractable soil As concentrations were successfully modelled using linear combinations of soil As content, soil Fe and Mn determinations and soil pH. Differences in As phytotoxicity, expressed in terms of effective toxic concentration (EC50), between soils were directly related to soil Fe, Mn and Al contents. Available soil phosphorous (P) exerted an ameliorating effect on As toxicity, with the available soil As/P ratio representing the single best predictor of plant growth suppression. Plant P nutrition appeared to influence the relative selectivity for As and P by wheat, with greater selectivity for P demonstrated under P deficient conditions. Plant As uptake, its distribution, and also the plant nutrient status were all adversely affected by increasing soil As exposure. Co-contamination by Zn corresponded to a substantial elevation in proportion of the plant As allocated in shoots. Plant As levels exhibited a saturation-dependent relationship with increasing soil As. The best linear predictors of plant As levels in the non-toxic range were RHIZO-extractable and effective soil As concentrations, the latter based on the diffusive gradients in thin films (DGT) technique. Despite the complexity of soil As dynamics, large proportions in the variances exhibited by the two measures of bioavailability were explained using a small set of readily-available soil properties.
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Nicolau, González Guillermo. "Cortocircuitos en redes AT e impactos en distribución MT." Doctoral thesis, Universitat Ramon Llull, 2012. http://hdl.handle.net/10803/83709.
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L’extensa implantació del control digital als entorns industrials, científics, comercials, professionals i domèstics ha revelat, d’ençà dues dècades, la gran sensibilitat d’aquests dispositius davant sobtats i breus descensos de tensió al subministrament elèctric de xarxa: aturades de plantes a processos productius, re – arrancades a processadors i sistemes de telecomunicació, etc.; i la causa sol esdevenir aparentment inexplicable pels usuaris. La normalització de les conseqüències, però, pot equivaler a un dia sencer de producció nul•la.
L’ínfima correlació mostrada pels fenòmens esmentats amb anomalies al sistema elèctric proper (un client pot patir sèries conseqüències, per bé que el client veí només ha percebut una oscil•lació a l’enlluernat, i tots dos comparteixen la mateixa escomesa) sumada amb l’absència contrastada d’interrupció elèctrica suposà, al començament, un major grau d’incertesa, no només pels consumidors; també per a les empreses elèctriques.
Fou necessari analitzar el problema en les seves vessants “microscòpica” i “macroscòpica” per a determinar la causa eficient: registrar la forma d’ona al punt de subministrament afectat i fer l’inventari de tots els incidents al Sistema Elèctric del mateix moment.
La causa: els sots de tensió produïts per incidents elèctrics a xarxes remotes respecte el subministrament. Davallades sobtades (entre el 80 i el 10% del valor nominal) i ràpides (entre 10 ms i 1 s) al valor eficaç de la tensió subministrada, sense pas per “Zero”, produïdes, principalment, per curt - circuits perfectament detectats i eliminats a xarxes d’Alta Tensió (AT), molt allunyats de la conseqüència observada. A Catalunya, hom comptabilitzen afectacions davant curt - circuits a les interconnexions amb l’Aragó, Castelló i França.
La present Tesi Doctoral estableix:
• La metodologia per a modelar el Sistema Elèctric de Potència;
• La sistematització del binomi causa (curt - circuit) – efecte (sot de tensió);
• La personalització estadística de risc pel sot de tensió segons comarques;
• Un sistema de protecció eficaç per a limitar la durada dels sots.
La metodologia ha estat enfocada a la utilització sistemàtica, tal que per a cada curt - circuit esdevingut a la xarxa AT es pugui establir, en temps real, las capçaleres de subministrament afectades pel sot de tensió, així com la magnitud i la durada del mateix.
L’entorn d’aplicació triat ha estat el Sistema Elèctric de Catalunya, per bé que la metodologia i sistemàtica són exportables, de forma natural, a qualsevol altre sistema elèctric trifàsic de corrent altern.La implantación masiva del control digital en entornos industriales, científicos, comerciales, profesionales y domésticos ha puesto de manifiesto, durante los últimos veinte años, la gran sensibilidad de los mismos ante súbitos y breves descensos de tensión en la alimentación eléctrica procedente de la red: paradas de planta en procesos productivos, re – arranques en procesadores y sistemas de telecomunicación tienen lugar; y la causa de los mismos suele ser aparentemente inexplicable para los usuarios. La normalización de las consecuencias, en ocasiones, equivale a un día de producción nula. La escasa correlación mostrada por dichos fenómenos con anomalías en el sistema eléctrico cercano (un cliente padece consecuencias serias, mientras que el cliente vecino solamente ha percibido una oscilación en el alumbrado y ambos se alimentan del mismo tramo eléctrico) sumada con la ausencia contrastada de interrupción eléctrica supuso, en los inicios, un mayor grado de incertidumbre tanto para los consumidores como para las empresas eléctricas. Fue necesario analizar el problema a nivel “microscópico” y “macroscópico” para determinar la causa eficiente: registrar la forma de onda en el punto de suministro afectado y revisar todos los incidentes habidos en el Sistema Eléctrico en dicho instante. La causa: los huecos de tensión producidos por incidentes eléctricos en redes alejadas del suministro. Descensos súbitos (entre el 80 y el 10% del valor nominal) y rápidos (entre 10 ms y 1 s) en el valor eficaz de la tensión suministrada, sin paso por “cero” de la misma, producidos, principalmente, por cortocircuitos perfectamente detectados y eliminados en redes de Alta Tensión (AT), y situados muy lejos de la consecuencia observada. En el caso de Catalunya, se han contabilizado afectaciones ante cortocircuitos en interconexiones con Aragón, Castellón de la Plana y Francia. La presente Tesis Doctoral establece: • La metodología para modelar el Sistema Eléctrico de Potencia; • La sistematización para el binomio causa (cortocircuito) – efecto (hueco); • La personalización del riesgo estadístico de hueco vs. comarcas; • Un sistema protectivo eficaz para limitar duración de los huecos. Dicha metodología se ha orientado a la utilización sistemática, tal que para cada cortocircuito que tenga lugar en la red AT pueda establecerse, en tiempo real, las cabeceras de suministro afectadas por hueco de tensión, la magnitud y la duración del mismo. Como entorno de aplicación, se ha utilizado el Sistema Eléctrico de Catalunya, si bien la metodología y sistematización son exportables, de forma natural, a cualquier otro sistema eléctrico trifásico de corriente alterna.
The massive introduction of digital control in industrial, scientific, commercial, professional and domestic environments has revealed, over the last twenty years, the great sensitivity of them to sudden and short voltage dips in the electrical power grid: shutdowns of productive process plants, re - starts of processors and telecommunications systems take place, and the cause of them is often apparently inexplicable to the users. The normalization of the consequences sometimes is equivalent to a day without production. The weak correlation shown by these phenomena with anomalies in the nearby electrical system (i.e. in the same portion of a common distribution network, a customer may suffer serious consequences, while the adjacent customer has only percept a swing in the lighting) together with the absence of electrical power interruption represented, in the beginning, a great degree of uncertainty for both consumers and utilities. It was necessary to analyze the problem at the "microscopic" and "macroscopic" levels to determine the efficient cause: record the waveform at the affected plants and review all the disturbances occurred in the Power System at the same instant of time. The cause: voltage dips caused by electrical disturbances away from the supply. Sudden decreases (between 80 and 10% of the nominal value) and fast (between 10 ms and 1 s) in the supplied rms voltage, produced mainly by short-circuits perfectly detected and eliminated in High Voltage (HV) networks, and located far away from the observed consequence. In the case of Catalonia, affectations due to short-circuits in interconnects with Aragon, Castellón de la Plana and France have been recorded. This thesis provides: • A methodology useful to model the Power System; • A systematic analysis for cause – effect: from short – circuit to voltage dip; • A particularization voltage dip statistic risk for each county; • A reliable protective system to ensure time – limitation for voltage dips. The presented methodology is oriented to the systematic use, such that for every short - circuit that takes place in the HV network, the magnitude and duration of voltage dips that appear in the distribution can be established in real-time. As the application framework, the Catalan Power System is used, although the methodology and systematization are exportable, to any other alternating three-phase power system.
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Ivanova, Anna. "Initial Examination of the English-language Dimensional Personality Symptom Item Pool." Thesis, 2009. http://hdl.handle.net/1807/18769.
Full textAbstract:
Dimensional models of personality pathology present a promising approach to the assessment of maladaptive personality in adults and children (eg. De Clercq, De Fruyt, & Widiger, 2009). In addition, recent findings show that some childhood maladaptive traits can be predictive of adulthood personality disorders (eg. Mervielde, De Clercq, De Fruyt, & Van Leeuwen, 2005). The Dimensional Personality Symptom Item Pool (DIPSI) is a questionnaire designed to measure maladaptive lower and higher order traits in children and adolescents. This study aims to examine the DIPSI’s scales and to replicate several previous findings of maladaptive trait patterns in children. The results indicate that the DIPSI’s lower and higher order trait scales are high in reliability and show many of the trait relationships suggested by previous literature. A successful outcome of this study serves as the first step towards establishing the DIPSI as a valid and useful measure of personality pathology in children.