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Goman, Anna. "Waveform Generator Implemented in FPGA with an Embedded Processor." Thesis, Linköping University, Department of Electrical Engineering, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-2026.
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Communication and digital signal processing applications of today are often developed as fully integrated systems on one single chip and are implemented as application specific integrated circuits using e.g. VLSI technology. As the systems are getting more and more complex in terms of speed and performance the chip size and the design time tend to increase rapidly. This will result in search for cheaper and less time consuming alternatives. One alternative is field programmable gate arrays, so called FPGAs. The FPGAs are getting faster, cheaper and the number of gates increases all the time. A long list of ready to use functional blocks so called intellectual property (IP) blocks can be used in FPGAs. The latest FPGAs can also be bought with one or more embedded processors, in form of hard processor cores or as licenses for soft processor cores. This will speed up the design phase and of course also decrease the crucial time to market even more.
The purpose of this master’s thesis was to develop a waveform generator to generate a sine signal and a cosine signal, I and Q, used for radio/radar applications. The digital signals should have an output data rate of at least 100 MHz. The digital part of the system should be implemented in hardware using e.g. an FPGA. To convert the digital signals to analog signals two D/A converters are used. The analog signals, I and Q, should have a bandwidth of 1 MHz - 11 MHz.
The waveform generator was developed and implemented using a Virtex II FPGA from Xilinx. An embedded microprocessor within the FPGA, MicroBlaze, in form of a soft processor core was used to control the system. A user interface program running on the microprocessor was also developed. Testing of the whole system, both hardware and software, was done. The system is able to generate digital sine and cosine curves of an output data rate of 100 MHz.
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Shen, Baike 1972. "Slip frequency phase lock loop (PLL) for decoupled P-Q control of doubly-fed induction generator (DFIG)." Thesis, McGill University, 2004. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=81568.
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The term "sensor-less" in power electronic drives refers to measurement of mechanical shaft position and/or speed from the currents and voltages of the electrical machine. This thesis presents innovative sensor-less means (a Slip Frequency Phase Lock Loop (PLL) and a gamma-delta Axes Aligner) for implementing decoupled P-Q control of a doubly-fed induction generator (DFIG) for wind-turbine application. Proofs of concepts are by digital simulations.The accuracy of the Slip Frequency Phase Lock Loop in speed estimation is evaluated; the origin of a shortcoming (small phase lag) located and compensated for.
The Slip Frequency Phase Lock Loop (PLL) and a gamma-delta Axes Aligner are then evaluated as parts of the decoupled P-Q control of a wind turbine driven doubly-ed induction generator. The research succeeds in realizing robust decoupled P-Q control, that is one in which the generator parameters do not have to be known precisely and can have minor variations such as drifts with temperature. The system has been successfully tested for optimal wind power acquisition.
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Chen, Jian. "Nonlinear adaptive control of permanent magnet synchronous generator based wind turbine : a perturbation estimation approach." Thesis, University of Liverpool, 2014. http://livrepository.liverpool.ac.uk/2007963/.
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This thesis deals with the modeling and control of permanent magnet synchronous generator based wind turbines (PMSG-WTs). The PMSG-WTs are widely used in wind energy conversion systems(WECSs), due to their merits such as high reliability, high efficiency, low noise, high torque to weight ratio and fast dynamic response. Usually, a PMSG-WT is connected to the power grid via an AC-DC-AC converter system. The PMSG-WT can rotate at varying speed based on variable wind power input and thus achieve high efficiency as it dose not need to synchronise its rotational speed with the grid frequency. An overview of the modeling of the PMSG-WT is give at first, with conventional vector control (VC) strategies applied for machine-side and grid-side converter. The VC strategy is a popular method widely used in industry due to its decoupled control of active/reactive power, but it may not provide satisfactory performance for the PMSG-WT as it is required to operate at varying speed in an operation envelope with wide operating range rather than one operation point. The feedback linearisation control (FLC) strategy can improve the performance of the VC with a global optimal controller crossing a wide region and variable operation points, but it has weak robustness against parameter uncertainties and external disturbances, and requires full state measurements. To improve performance of the VC and the FLC, nonlinear adaptive controllers (NACs) designed based on FLC and perturbation estimation and their applications in machine-side and grid-side converter control of the PMSG-WT, and speed control of a permanent magnet synchronous motor (PMSM) have been studied. In the design of the proposed NAC, by defining a lumped perturbation term to present coupling nonlinear dynamics, parameter uncertainties, and other unknown disturbance, then a perturbation observer is designed to estimate the perturbation which is used to compensate the real perturbation and realise an adaptive linearising of the original nonlinear system, without requiring the accurate system model and parameters and full state measurements, and still considering all system nonlinearities and unknown time-varying dynamics, such as tower shadow, grid faults and intermittent wind power inputs. In this thesis, the proposed control schemes are applied for control of PMSGWT in Region 2, Region 3 and integration with the grid. A NAC is developed for a PMSG-WT to extract maximum wind power in Region 2. Simulation and experiment studies are carried out to verify the design and results show that the proposed NAC can provide better performance in MPPT and robustness against parameter uncertainties and time-varying wind power inputs, in comparison with a convention VC and FLC. NACs are designed for control of the pitch angle and generator control of a PMSG-WT to limit the extracted power from time varying wind in Region 3. Simulation results of the proposed NACs are compared to a conventional VC and FLC. The fault ride-through capability (FRTC) of the PMSG-WT at different voltage dip’s levels has been enhanced by a novel NAC applied at the grid-side converter. Simulation results have shown that the proposed NAC can provide satisfactory performances with smaller inrush current and voltage overshoots during grid fault and better robustness against uncertainties. A coordinated nonlinear adaptive control (CNAC) of the machine-side and grid-side converter in the PMSG-WT were studied. The NACs are designed based on state and perturbation observers for control of subsystems. Simulation results show that the CNAC can coordinate each other to achieve the objectives of different operating regions and enhance the FRTC of the PMSG-WT. Finally, the proposed control schemes are applied for control of PMSM. NAC is developed for PMSM to track mechanical rotation speed and provide high robustness against system parameter uncertainties and unknown time-varying load disturbances. Simulation results show that the proposed NAC provides better performance and robustness against system parameter uncertainties and unknown time-varying load disturbances, in comparison with a nonlinear controller with an extended nonlinear observer and a conventional VC.
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Gogas, Kyriakos. "Design of a robust speed and position sensorless decoupled P-Q controlled doubly-fed induction generator for variable-speed wind energy applications." Thesis, McGill University, 2007. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=99762.
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Wind energy is a relatively young but rapidly expanding industry. In order for wind generation to be cost effective, it must produce energy at a minimum cost per dollar of investment. Performance characteristics such as power output versus wind speed must be optimized in order to compete with other energy sources. Also, if the utility uses wind power for a part of its generation, the output power of these turbines must have the same high quality and reliability when it enters the utility grid. The ability to vary operating speed is important in wind generation because it allows for an optimization of the transfer of power from the wind to the turbine shaft. Doubly-fed induction generators (DFIG) are an interesting solution for variable-speed systems with limited variable speed range, and are typically used in wind energy conversion systems.The objectives of this thesis are to implement a decoupled P-Q control of a DFIG that does not rely on mechanical sensors and to design a speed and position sensorless algorithm that is robust to variations of the values of the machine parameters. The sensorless DFIG control algorithm presented in this thesis is based on a modified phasedlock loop with an improved positioning algorithm. With the measured stator voltages, stator and rotor currents, the speed and position of the DFIG are estimated. The speed is estimated independent of machine parameters, which results in a significant improvement in speed control robustness to parameter variations. In addition, the algorithm avoids using differentiation, which significantly improves its immunity to noise and does not require the measurement of the rotor voltages. Also, it is shown that the positioning algorithm has an improved operation in generator mode. Although the accuracy of the positioning algorithm is depended on machine parameters; it is shown with the designed controller that the P-Q decoupled control is robust to changes of machine parameters. Theoretical and simulation results are validated on an experimental setup.
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Strudwick, Scott David. "A trend analysis expert system for the remote condition monitoring of diesel generators." Thesis, University of Greenwich, 1993. http://gala.gre.ac.uk/8704/.
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Nguyen, Phuong. "Ethnic gap, household businesses and social networks in Vietnam The role of Social Networks on Household Business Performance in Vietnam: A qualitative assessment." Thesis, Paris Sciences et Lettres (ComUE), 2018. http://www.theses.fr/2018PSLED080.
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Au cours des deux dernières décennies, les deux groupes vulnérables des ethnies minoritaires et des entreprises familiales ont contribué à la croissance économique, mais n’ont pas été en mesure de bénéficier de la croissance économique autant que d’autres groupes au Vietnam. Le caractère moins inclusif de ces deux groupes dans la croissance économique demande une étude sur l'écart ethnique de bien être et des performances des entreprises familiales au point de vue des réseaux sociaux. Cette recherche étudie le rôle des réseaux sociaux en utilisant la méthode Q-square sur une base de données originale, les données quantitatives et qualitatives des relations sociales d'une entreprise familiale, et avec un instrument innovant: être le fils l'aîné. Le chapitre 1 mesure et analyse les déterminants principaux de l’écart ethnique pendant les dix ans derniers. Le chapitre 2 identifie les effects de cause entre les réseaux sociaux et la performance des entreprises familiales. Enfin, le chapitre 3 présente une étude qualitative de l'impact des réseaux sociaux sur les performances des entrepreneurs informels. Cette étude se centre sur une dimension particulière des réseaux qui est la force des liens. Elle distingue par ailleurs l’utilisation des réseaux à la création de l’entreprise et à un stade plus avancé de son développementOver the past two decades, the two vulnerable groups of ethnic minorities and household businesses have participated in the economic growth but could not benefit from the growth process as much as the other groups in Vietnam. The inadequate inclusiveness of these two groups in the economic growth calls for an investigation of the ethnic gap and household businesses' performance with a lens of social networks. This study aims to examine the role of social networks, using a Q-squared method to analyze an original dataset, which combined both the quantitative and qualitative datasets on social networks of household businesses. In doing so, the study employs an innovative instrument of being the first son in the family. Chapter 1 measures and analyses the main drivers of the ethnic gap over the last ten years. Chapter 2 identifies the causal effects of social networks on household businesses' performance. Chapter 3 presents a qualitative analysis of the impact of social networks on business performance by the content and the strength of social relationships, and the business phase
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Koppula, Sreedevi. "Automated GUI Tests Generation for Android Apps Using Q-learning." Thesis, University of North Texas, 2017. https://digital.library.unt.edu/ark:/67531/metadc984181/.
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Mobile applications are growing in popularity and pose new problems in the area of software testing. In particular, mobile applications heavily depend upon user interactions and a dynamically changing environment of system events. In this thesis, we focus on user-driven events and use Q-learning, a reinforcement machine learning algorithm, to generate tests for Android applications under test (AUT). We implement a framework that automates the generation of GUI test cases by using our Q-learning approach and compare it to a uniform random (UR) implementation. A novel feature of our approach is that we generate user-driven event sequences through the GUI, without the source code or the model of the AUT. Hence, considerable amount of cost and time are saved by avoiding the need for model generation for generating the tests. Our results show that the systematic path exploration used by Q-learning results in higher average code coverage in comparison to the uniform random approach.
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Felgate, Nigel Stephen. "Efficient blue generation from all-solid-state Q-switched Nd:YAG lasers." Thesis, University of Southampton, 2002. https://eprints.soton.ac.uk/41527/.
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This thesis describes work carried out at Southampton University that has been directed towards achieving high-power all-solid-state blue sources using two low-gain transitions of Nd:YAG. Diode-end-pumping is used to obtain efficient laser performance. The thesis attempts to tackle some of the obstacles to power scaling Q-switched low-gain lasers that use diode-end-pumping schemes. A 1319nm Q-switched Nd:YAG laser is described that produces a 17KHz pulse train consisting of 353 watt peak power pulses delivering an average power of 780mW for doubling. Periodically poled lithium niobate (PPLN) is used to double to 659.5nm. A 54% second harmonic conversion efficiency produces 360mW of red average power. Sum frequency mixing of the red and infra-red in a second PPLN sample is achieved with a third order grating. A pulsed blue output (13.7 watts peak) at 439.7nm is achieved with good beam quality and an average power of 35mW. A technique is described to aid power-scaling of polarised laser sources. Analysis of the quarter wave-plate technique demonstrates that the technique will be highly beneficial in reducing the depolarisation loss in low-gain solid-state lasers. The technique is applied to a 946nm laser and a 1319nm laser. Depolarisation of the 946nm source is reduced from 1.66% to 0.0006% and depolarisation of the 1319nm laser is reduced from 1.2% to 0.015%. The quarter wave-plate technique is implemented in a high power 946nm laser that is Q-switched for low repetition rates. 0.53mJ is extracted with a 5.3KW peak pulse power at 1 kHz repetition rate. The 946nm output is used to generate 473nm blue light via second harmonic generation in non-critically phase-matched LBO at 329° centigrade. An average power of 370mW is demonstrated with a conversion efficiency of 21% at 4kHz repetition rate.
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Tjörnhammar, Staffan. "Pulsed Yb:KYW laser and UV generation." Thesis, KTH, Laserfysik, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-51595.
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In this master thesis project, a pulsed UV laser was designed and constructed. Also, the effects of absorption in a volume Bragg grating were investigated. The laser was diode pumped and constructed with Yb:KYW as gain medium. The lasing was at a wavelength of 1029.2 nm with a spectral bandwidth of 0.23 nm, locked by a volume Bragg grating that was used as input coupler for spectral control. Passive Q‑switching was used to generate pulses by placing a Cr:YAG saturable absorber inside the cavity. The laser generated radiation with a maximum peak power of 3.8 kW at an average power of 0.35 W, a repetition rate of 4 kHz and a pulse width of 16 ns. The maximum average power was 1.3 W with a peak power of 2 kW at a repetition rate of 20 kHz and with a pulse width of 20 ns. Through extra‑cavity second harmonic generation using an LBO crystal, green light at a wavelength of 514.7 nm was generated. The maximum average power was 130 mW with an optical conversion efficiency from the fundamental of around 10 %. Then, the second harmonic and the fundamental wave were mixed to generate UV light, at a wavelength of about 343 nm, by using a second LBO crystal. The maximum average power of UV was about 23 mW with an optical efficiency, with respect to the green, of approximately 20 %. One limitation of the laser was that the Cr:YAG was bleached not only by the circulating laser field, but also by remaining pump light. This resulted in decreasing peak power with increasing pump power, thus limiting the nonlinear conversion efficiencies. Thermal fracture of the Cr:YAG was a limiting factor for the intra-cavity average power, while burning of the coating on the Yb:KYW crystal limited the maximum peak power. The effects on a laser when using too high power for the level of absorption in a volume Bragg grating were also investigated. The effects of both resonant and non-resonant beams were investigated. Since the intensity of a resonant beam decreases approximately exponentially in a volume Bragg grating, due to absorption, an uneven temperature distribution along the propagation axis is formed. This results in different thermal expansion and hence, results in a longitudinal chirp of the grating. The chirp caused a decrease in both reflectivity and spectral selectivity. The reflectivity of the particular grating used in these experiments decreased from 99.4 % to 93 %. In addition, it was experimentally shown that if a volume Bragg grating absorbs a non-negligible amount of a non-resonant beam, the thermal load will deform the volume Bragg grating. Therefore, it is not suitable to use such a grating the as input coupler of a laser cavity.I detta examensarbete utformades och konstruerades en pulsad UV-laser. Dessutom undersöktes effekterna av absorption i ett volymbraggitter. Som laserkristall användes Yb:KYW vilken pumpades med en diodlaser. Lasring skedde vid 1029,2 nm med en bandbredd av 0,23 nm genom att ett volymbraggitter användes som inkopplingsspegel för att kontrollera spectrumet. Pulser generades genom passiv Q-switching med en Cr:YAG som mättnadsbar absorbator inne i kaviteten. Den maximala toppeffekten var 3,8 kW vid 0.35 W medeleffekt, 4 kHz repetitionsfrekvens och en pulsbredd på 16 ns. Den maximala medeleffekten var 1.3 W med en toppeffekt på 3,8 kW, 20 kHz repetitionsfrekvens och en pulsbredd på 20 ns. Genom frekvensdubbling i en LBO kristall genererades grönt ljus vid våglängden 514,7 nm. Den maximala medeleffekten var 130 mW med en optisk verkningsgrad från den fundamentala våglängden på 10 %. Sedan blandades det infraröda och det gröna ljuset i en andra LBO kristall för att generera UV-ljus, vid en våglängd om 343 nm. Den högsta medeleffekten av UV var cirka 23 mW med en optisk verkningsgrad, med avseende på det gröna ljuset, på ungefär 20%. En begränsning av laser var att Cr:YAG kristallen blektes inte enbart av lasern utan även av pumpen. Detta resulterade i fallande toppeffekt med ökande pumpeffekt, vilket begränsade effektiviteten i den ickelinjära konverteringen. Termisk fraktur på Cr:YAG kristallen var en begränsande faktor för cirkulerande medeleffekten i kaviteten, medan brännskador på Yb-kristallens antireflexbehandling begränsade toppeffekten. Effekterna i en laser vid användning av en alltför hög effekt i förhållande till nivån av absorption i ett volymbraggitter studerades också. Effekterna av både resonanta och ickeresonanta strålar undersöktes. Eftersom intensiteten av en resonant ståle minskar ungefär exponentiellt i ett volymbraggitter kommer temperaturen, på grund av absorption, fördelas ojämnt i propageringsriktningen. Detta resulterar i olika termiska expansion med en längsgående varierad gitterperiod som följd. Detta orsakar en minskning utav både reflektiviteten och den spektrala selektiviteten. Reflektiviteten i gittret som användes i dessa experiment minskade från 99,4 % till 93 %. Dessutom visades det experimentellt att om ett volymbraggitter absorberar en icke försumbar del av en ickeresonant stråle kommer värmebelastning att deformera volymenbraggittret. Därför är det inte lämpligt att använda ett sådant gitter som inkopplingsspegel i en laser.
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Gugler, Klaus, Adhurim Haxhimusa, Mario Liebensteiner, and Nora Schindler. "Investment under Uncertainty in Electricity Generation." WU Vienna University of Economics and Business, 2016. http://epub.wu.ac.at/5177/1/wp234.pdf.
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The recent transformation of European electricity markets with increasing generation from intermittent renewables brings about many challenges. Among them, decaying wholesale prices, partly due to support schemes for renewables, may send insufficient investment signals for other technologies. We investigate the investment decision in a structural equation based on the Tobin's q-model, which we extend by both industry- and firm-technology-specific uncertainty. We utilize rich and novel data at the disaggregated firm generation technology level of European electricity generating firms for the period 2006-2014. Our results show that investment in any generation technology follows market incentives despite sunk and irreversible capital, confirming the implications of the q-model. Moreover, while firm-technology-specific uncertainty decreases firms' investment activity, especially in coal and gas, aggregate uncertainty triggers firms' investment. Our results raise concerns about system reliability in the long run since conventional technologies still serve as a flexible system back-up. (authors' abstract)Series: Department of Economics Working Paper Series
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Baker, Shelley Louise. "Use of a direct, positive selection strategy to generate improved prodrug-activating enzymes for cancer gene therapy." Thesis, University of Birmingham, 2011. http://etheses.bham.ac.uk//id/eprint/1443/.
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E. coli NfsB nitroreductase (NTR) is currently being studied in combination with the prodrug CB1954, as a gene directed enzyme prodrug therapy. NTR reduces CB1954 at either the 2- or 4-nitro groups to produce highly cytotoxic hydroxylamine derivatives, using either NADH or NADPH as cofactor. Initial clinical trials suggest activity, with reduction in PSA and apparent delayed progression in some patients. This thesis is concerned with engineering the NTR enzyme to improve the efficiency of CB1954 activation, since this would be expected to improve the potential clinical efficacy. Site directed mutagenesis has been used to generate four libraries of NTR mutants with three small libraries having a maximum diversity of 6.4 x101 – 8.2 x 103 and a large library of 6.3 x 106 possible nucleotide combinations. A direct positive selection strategy, which utilises bacteriophage lambda and the SOS response, was used to select NTR variants with increase sensitivity for CB1954 from each library. NTR mutants with greatest sensitivity were analysed by bacterial IC50 assays. Despite considerable work to generate and optimise the large library, only one NTR enzyme was improved over WT. However the best mutant (T41G N71S) came from a small library, with an IC50 of 8 µM. The most promising NTR enzyme variants were column purified and their kinetic parameters and activity determined. T41G N71S showed good activity for CB1954 (0.52 µM s-1), being the second best mutant to date behind T41L N71S (0.90 µM s-1). Adenoviral vectors were generated and their ability to sensitise SKOV3 cancer cells tested. T41G N71S was ~2-fold improved relative to WT NTR. Purified enzymes were also tested with SKOV3 cells, with T41G N71S being ~2.6-fold improved relative to WT NTR. My best enzyme should be considered when planning future clinical trials using prodrug activation gene therapy with NTR.
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Walker, John R. "Investigation of isoform-specific fruitless mutants generated by gene targeting in Drosophila melanogaster." Thesis, University of Glasgow, 2009. http://theses.gla.ac.uk/1283/.
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fruitless (fru) is a pleiotropic gene which produces an array of variant transcription factor isoforms to fulfil a range of developmental and behavioural roles, from the regulation of axonal pathfinding during embryogenesis, all the way to the precise orchestration of individual steps of the Drosophila melanogaster male courtship ritual. Much of the transcriptional differentiation is achieved through the use of multiple promoters, sex-specific splicing and variant C-termini. Alternative splicing at the 3′ end enables generation of transcripts containing one of at least three zinc finger (Zn-F) domains (A, B or C). Due to the close proximity of these Zn-F–encoding exons at the fru locus, almost all extant fru mutants reduce or eliminate expression of all isoforms from a given promoter(s). This has prevented genetic dissection of their individual roles, and limited functional assignment to the zinc finger triumvirate as a whole. Using gene targeting by homologous recombination, this project set out to generate precise null mutations for type-A and -B Fru isoforms in an attempt to determine which aspects of fru function are conferred by these isoforms. Isoform-specifc antibodies were also generated to confirm the loss of individual isoforms within the generated mutants, and to investigate the expression of different isoforms throughout development. Generation of such an antibody to FruB proteins enabled the developmental expression pattern of this isoform to be assessed for the first time, and expression in the male-specific serotonergic neurons of the abdominal ganglion suggested a possible role for male-specifc FruB isoforms in male fertility. Investigation of the developmental expression patterns of FruC revealed a novel immunostaining pattern for this isoform in a group of coalescing cells which appear towards the end of embryonic development. Isolation of specific-isoform mutants was achieved, giving rise to multiple mutant phenotypes, varying in severity between mutant lines. Analysis of mutants lacking type-A and -B Fru isoforms demonstrated the importance male-specific type-A and/or type-B isoforms in establishing male fertility, and suggested essential roles for sex-non-specifc type-A and/or type-B isoforms in the viability and morphology of both sexes.
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Slavinskis, Nerijus. "Short pulse q-switched longitudinally diode pumped solid state minilasers: generation, characterization and application." Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2011. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2011~D_20110630_134119-87467.
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The dissertation is dedicated to the detailed numerical modelling of generation dynamics of actively and/or passively Q-switched diode laser longitudinally pumped solid-state lasers, characterization of spatial and temporal laser properties and for the demonstration of application possibility of created minilasers. A detailed theoretical model for the description of generation dynamics using travelling wave approach is presented. In this model more parameters of active laser medium, pump sources and resonator architecture are taken into account. In this thesis the results which show the principal difference between results obtained using the laser travelling wave model and point laser model are presented. Using point laser model the problems of generated pulse timing jitter in passively Q-switched lasers are described and its lowering possibilities using different pumping methods are suggested. In this thesis new, based by the second order moment, laser beam characterisation by knife-edge method is presented. Also laser pulse compression possibilities in tetrachloride CCL4 medium are described. It is showed that using seed signal it is possible to obtain shorter (< 60 ps) and more stable optical pulses. In this thesis application possibilities of created minilasers are presented: the experimental results of the Z-scan measurements obtained using pulses with different pulse shapes for fused silica are presented; also experiments, in which, created minilasers for paper cleaning... [to full text]Disertacija skirta diodais kaupinamų kietojo kūno lazerių su aktyviąja ir pasyviąja kokybės moduliacija generacijos dinamikos detalesnei skaitmeninei analizei, lazerio impulsų laikinių ir erdvinių parametrų charakterizavimui ir sukurtų minilazerių panaudojimo galimybių demonstracijai. Generacijos dinamikos detalesniai skaitmeniniai analizei, darbe pristatomas sukurtas bėgančiųjų bangų modelis, kuriame atsižvelgiama ne tik į daugelį procesų vykstančių lazerio aktyviajame elemente, bet ir į rezonatoriaus konfigūraciją bei kaupinimo šaltino parametrus. Pateikiami skaitinio modeliavimo rezultatai demonstruojantys šio modelio privalumus lyginant su dažniausiai naudojamu taškiniu lazerio modeliu. Naudojant taškinį lazerio modelį yra nagrinėjama generuojamų impulsų laikinio tirtėjimo problema pasyvios kokybės moduliacijos lazeriuose ir pasiūlyti mažinimo būdai naudojant skirtingus kaupinimo būdus. Darbe taip pat pateiktas naujas, antraisiais momentais pagrįstas, pluošto charakterizavimo judančiu peiliu metodas. Nagrinėjamos lazerių impulsų spūdos galimybės tetrachlorido CCL4 skystyje ir pademonstruota, kad naudojant užkrato signalą galima gauti trumpesnius (< 60 ps) ir stabilesnius optinius impulsus. Darbe pademonstruotos sukurtų minilazerių pritaikymo galimybės: aprašomas netiesinio lūžio rodiklio kvarciniame stikle matavimas Z-skenavimo metodu ir gautų duomenų apdorojimo procedūra įskaitant naudojamų impulsų erdvinę ir laikinę formą; aprašomi eksperimentai, kuriuose sukurti... [toliau žr. visą tekstą]
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Koçak, Murat. "The Application of Q Methodology to Generate A Functional Typology of Terrorist Organizations in Turkey." Kent State University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=kent1286681075.
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Di, Silvestre Olga. "Rappresentazioni LGBTQI+ nelle serie televisive americane: i casi di ‘Transparent’, ‘Pose’ e ‘The L World: Generation Q’." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021.
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La tesi tratta di come le rappresentazioni LGBTQI+ si siano evolute all'interno delle serie televisive americane. Attraverso una prima parte teorica ed una seconda parte analitica è stato evidenziato in che modo si è passati da un'assenza di rappresentazione ad una rappresentazione vera e propria di questa comunità. Tale evoluzione è stata possibile grazie al cambiamento a cui sono state sottoposte sia la televisione che la società nel corso degli anni. Le tre serie analizzate: Transparent, Pose e The L Word: Generation Q, hanno avuto il compito di mostrare in che modo le serie televisive contemporanee trattino i diversi aspetti delle vite delle persone LGBTQI+, arrivando a naturalizzare i loro personaggi, processo che in passato era considerato impensabile.
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Shakely, Yar. "«Jajaja es q son para comerselos…» : - Ortografía de actualizaciones de estado en Facebook." Thesis, Umeå universitet, Institutionen för språkstudier, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-99877.
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The explorative and descriptive study looks at Facebook statuses from the year 2013, and revises the orthographic status of the texts. The orthographic deviations are presented in categories and discussed and analyzed with the objective to possibly see some general tendencies to be able to add knowledge about user-generated written Spanish on Internet. The result shows that there are a lot of orthographic deviations in Facebook statuses, and some of the tendencies are the omission of accentuation marks, the incorrect usage of punctuation signs, influences from other languages in the lexicon and orthographic signs such as exclamation- and question marks and quotation marks and the informal orthography in informal statuses. Nevertheless, the study also shows that the language used on Internet is difficult to generalize since it demonstrates an individualistic, experimental and creative characteristic.
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Longhi-Browne, Cassandra W. "Using Caenorhabditis elegans as a novel expression system for the generation of recombinant Teladorsagia circumcincta vaccine candidates." Thesis, University of Glasgow, 2014. http://theses.gla.ac.uk/5547/.
Full textAbstract:
Teladorsagia circumcincta is a common abomasal parasite of sheep in temperate regions and is one of the major causes of parasitic gastroenteritis (PGE) in growing lambs. Control of infection is achieved using anthelmintic drugs; however, this practice is rapidly becoming unsustainable due to widespread anthelmintic resistance within the T. circumcincta population. Sheep can acquire protective immunity against this parasite; immunity involves local and systemic antibodies and immune cells which can impair worm growth and fecundity and lead to expulsion of the parasites from the abomasum. Vaccination against this parasite is therefore a feasible option of control. A recent study showed that a recombinant vaccine cocktail containing 8 T. circumcincta antigens significantly reduced the faecal egg count and worm burdens of immunised sheep, compared to an adjuvant-only control group. However, the recombinant antigens induced a suboptimal antibody response to the recombinant antigens. This suggests that differencies between the native antigens and their recombinant versions may exist, possibly due to variations in structure and/or post-translational modifications (PTMs). The main aim of this work was to use a novel expression system, the free living nematode Caenorhabditis elegans, to generate alternative recombinant versions of two of the T. circumcincta antigens used in the 8-antigen vaccine, cathepsin F (Tci-CF-1) and monocyte Migration Inhibitory Factor (Tci-MIF-1). This was achieved by micro-injection of C. elegans worms with plasmids containing the cDNA sequences of Tci-cf-1 and Tci-mif-1 followed by purification of recombinant Tci-CF-1 and Tci-MIF-1 from the transformed worms. Immune recognition, enzyme activity and biological effects on sheep cells of the recombinant antigens were characterised. The results show that immunisation-induced antibodies bind to native Tci-CF-1 purified from T. circumcincta L4 ES, whereas infection-induced antibodies were unable to bind the recombinant Tci-CF-1 versions. Further characterisation of recombinant Tci-CF-1 versions expressed in C. elegans or Pichia pastoris showed that in order to be enzymically active, these proteins require cleavage of the pro-peptide by an exogenous enzyme and that some differences were present in the glycosylation of the recombinant versions and native Tci-CF-1. Characterisation of both recombinant Tci-MIF-1 versions showed that although both are enzymically active, neither showed a significant inhibitory effect on the migration of sheep monocytes or on the activation of sheep macrophages in vitro compared to unstimulated controls. It is speculated that Tci-MIF-1 may be involved in T. circumcincta larval development rather than host immunosuppression.
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Ok, Ali Ozgun. "Accuracy Assessment Of The Dem And Orthoimage Generated From Aster." Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/12606588/index.pdf.
Full textAbstract:
In this study, DEMs and orthoimages were generated from ASTER imagery and their accuracies were assessed. The study site covers an area of approximately 60 x 60 km and encloses the city of Ankara.
First, DEMs were generated from stereo ASTER images. In order to find the best GCP combination, different number of GCPs (8, 16, 24, and 32) was used. The accuracies of the generated DEMs were then assessed based on the check points (CP), slopes and land cover types. It was found that 16 GCPs were good compromise to produce the most accurate DEM. The post processing and blunder removal increased the overall accuracy up to 38%. It was also found that there is a strong linear relationship between the accuracies of DEMs and the slopes of the terrain. The accuracies computed for water, urban, forest, mountainous, and other areas were found to be 5.01 m, 8.03 m, 12.69 m, 17.14 m, and 10.21 m, respectively. The overall accuracy was computed as 10.92 m.
The orthorectification of the ASTER image was carried out using 12 different mathematical models. Based on the results, the models First Order 2D Polynomial, Direct Linear Transformation and First Order Polynomial with Relief have produced the worst results. On the other hand, the model Second Order Rational Function appears to be the best model to orthorectify the ASTER images. However, the developed model Second Order Polynomial with Relief provides simplicity, consistency and requires less number of GCPs when compared to the model Second Order Rational Function.
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Leigh, Matthew. "HIGH POWER PULSED FIBER LASER SOURCES AND THEIR USE IN TERAHERTZ GENERATION ." Diss., The University of Arizona, 2008. http://hdl.handle.net/10150/193797.
Full textAbstract:
In this dissertation I report the development of high power pulsed fiber laser systems. These systems utilize phosphate glass fiber for active elements, instead of the industry-standard silica fiber. Because the phosphate glass allows for much higher doping of rare-earth ions than silica fibers, much shorter phosphate fibers can be used to achieve the same gain as longer silica fibers.This single-frequency laser technology was used to develop an all-fiber actively Q-switched fiber lasers. A short cavity is used to create large spacing between longitudinal modes. Using this method, we demonstrated the first all-fiber Q-switched fiber laser in the 1 micron region.In addition to creating high peak powers with Q-switched lasers, created even higher powers using fiber amplifier systems. High power fiber lasers typically produce spectral broadening through the nonlinear effects of stimulated Raman scattering, stimulated Brullion scattering, and self-phase modulation. The thresholds for these nonlinearities scale inversely with intensity and length. Thus, we used a short phosphate fiber gain stage to reduce the length, and a large core fiber final stage to reduce intensity. In this way we were able to generate high peak power pulses while avoiding visible nonlinearities, and keeping a narrow bandwidth.The immediate goal of developing these high power fiber laser systems was to generate narrowband terahertz radiation. Two different wavelengths were combined into the final amplifier stage at orthogonal polarizations. These were collimated and directed into a GaSe crystal, which has a very high figure of merit for THz generation. The two wavelengths combined in the crystal through the process of nonlinear difference frequency generation. This produced a narrowband beam of THz pulses, at higher powers than previous narrowband THz pulses produced by eyesafe fiber lasers.
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Kneis, Christian. "Investigation of mid-infrared supercontinuum generation in soft-glass fibers from a Q-switched mode-locked 2 mm fiber laser." Thesis, Bordeaux, 2016. http://www.theses.fr/2016BORD0135/document.
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Cette thèse est dédiée à l’étude de la génération de supercontinuum (SCG) deforte puissance moyenne dans le domaine spectral entre 2 mm et 5,5 mm. Un laser à fibredopée thulium (Tm3+) opérant dans un régime simultanément déclenché et à verrouillage demodes (QML) a été développé. En régime continu ce laser a délivré 70 W et en régime QML,26Wmoyens ont été obtenus pour des taux de répétition en QS de 180 kHz ou plus. L’énergiela plus élevée contenue dans une enveloppe QS a été évaluée à 166 mJ avec 66 mJ contenuedans la sous-impulsion à verrouillage de mode la plus énergétique. L’émission du laser àfibre correspondait toujours à un facteur de qualité M2 excellent, entre 1,1 et 1,2. La SCGcouvrant la plage spectrale de 2 mm à 5,5 mm a été réalisée en implémentant différentes fibresen cascade. Des supercontinua jusqu’à environ 4 mm ont été générés dans des fibres en fluorurepuis pour la plage spectrale complémentaire entre 4 mm et 5,5 mm, des fibres en chalcogénureont été utilisées.La puissance moyenne maximale de 7,8 W a été démontrée pour un supercontinuum dans unefibre en ZBLAN. Le spectre s’étend jusqu’à 4,2 mm. Au total, 69%/43%/30%/16,5% de lapuissance totale ont été mesurés au-delà de 2,15 mm/2,65 mm/3,1 mm/3,5 mm respectivement.La fibre en InF3 a permis d’atteindre une puissance moyenne de 0,8 W et le supercontinuums’étend jusqu’à 2,95 mm.Pour les essais d’élargissement spectral complémentaire, trois fibres en chalcogénure ont étéutilisées. L’élargissement spectral a été démontré pour toutes les fibres en chalcogénure.Jusqu’à 20 mW de puissance ont été obtenus avec une fibre As2Se3. Le spectre a été étendujusqu’à 4,9 mmThis thesis reports about the investigation of high power supercontinuum (SC)generation between 2 mm and 5.5 mm. A Q-switched mode-locked (QML) thulium (Tm3+)-doped fiber laser has been developped to pump different nonlinear fibers. The fiber laserprovided in continuous wave regime an output power of 70 W. In QML operation, 26 W havebeen obtained with Q-switched repetition rates of 180 kHz or higher. The highest energy of theQS envelopes has been 166 mJ with 66 mJ contained in the most-energetic ML pulses, whichhave been surrounded by Gaussian-like pedestals with temporal widths around 2.5 ns. On topof these pedestals, very short temporal peaks with pulse durations around 15 ps appeared. Thehighest achieved peak power of a pedestal has been 25 kW. The beam parameter product M2of the fiber laser has been measured in different operational regimes and resulted always in anexcellent value around 1.2.The highest SC output power level from a ZBLAN fiber has been 7.8 W. In total, 69%/43%/30%/16.5% of the transmitted SC output radiation could be converted beyond the wavelengthof 2.15 mm/2.65 mm/3.1 mm/3.5 mm, respectively, with the broadest output spectrum from theZBLAN fiber exceeding 4.2 mm. The InF3 fiber provided a total output power of 0.8 W withan output spectrum up to 2.95 mm.Successful broadening of the wavelength-limited SC output from the ZBLAN fibers has beenachieved with all three investigated chalcogenide fibers with as much as 20 mW of outputpower by using an arsenic selenide fiber. The output spectrum exceeded 4.9 mm
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Kavanaugh, Karen Kavanaugh. "Gamification Techniques and Millennial Generation Philanthropy." ScholarWorks, 2017. https://scholarworks.waldenu.edu/dissertations/3455.
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Beginning in 2015 a major demographic shift in the majority income producers in the United States has moved from Baby Boomers to Millennials. At the same time, many nonprofits are not equipped to engage with Millennials and lack the knowledge and resources to tap into their philanthropic preferences. Using the theories of planned behavior, reciprocal altruism, social status, and warm glow theory, the purpose of this qualitative study was to explore opportunities for U.S. based nonprofit organizations to interact more effectively with members of the Millennial generation in terms of philanthropic behavior. Data were collected and analyzed using Q Methodology and included 36 Millennials attending the University of Arkansas, Fayetteville. Overall the researcher found that Millennials embrace the idea of using gamification to further fundraising. Five factors or profiles of potential donors were extracted from the Q-sort results: (a) the nongaming, knowledge seeker; (b) the high engagement, needs recognition donor; (c) the philanthropist gamer; (d) the gamer, let's play but not compete; and, (e) the transparent gamer. The findings of this study have the potential to create positive social change by providing information to nonprofits who may use it to cultivate, educate, and solicit individual charitable donations from members of Gen Y. The positive social change implications of this study include advice to nonprofit organizations on ways to increase revenue streams through donations from Millennials that could enable nonprofit organizations to better fulfill their mission and serve their constituents
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Kadwani, Pankaj. "Pulsed Tm-Fiber Laser for Mid-IR Generation." Doctoral diss., University of Central Florida, 2013. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5955.
Full textAbstract:
Thulium fiber lasers have attracted interest based on their long emission wavelength and large bandwidth (~1.8 – 2.1 &"181;m) relative to more established ytterbium and erbium fiber lasers. In addition, Tm:fiber lasers offer the potential for high efficiencies (~60 %) and high output power levels both in cw as well as pulsed regimes. These attributes are useful particularly in applications such as remote sensing, materials processing and mid-infrared generation. This dissertation describes the development of novel nanosecond pulsed thulium fiber laser systems with record high peak power levels in order to pump nonlinear mid-infrared generation.
The peak power scaling in thulium fiber lasers requires new fiber designs with ultra large mode field area (MFA). Two different classes of prototype thulium doped photonic crystal fibers (PCF) were investigated for high peak power generation. The first prototype is a flexible-PCF with 50 ?m core diameter, and the second is a rod-type PCF with 80 ?m diameter core. A robust single stage master oscillator power amplifier (MOPA) source based on flexible-PCF was developed. This source provided narrow linewidth, tunable wavelength, variable pulse duration, high peak power, and high energy nanosecond pulses. The PCF-rod was implemented as a second stage power amplifier. This system generated a record level of ~1 MW peak power output with 6.4 ns pulse-duration at 1 kHz repetition rate. This thulium doped PCF based MOPA system is a state of the art laser source providing high quality nanosecond pulses.
The single stage MOPA system was successfully implemented to pump a zinc germanium phosphide (ZGP) crystal in an optical parametric oscillator (OPO) cavity to generate 3 - 5 &"181;m wavelengths. The MOPA source was also used to demonstrate backside machining in silicon wafer.
The PCF based laser system demonstrated an order of magnitude increase in the peak power achievable in nanosecond thulium doped fiber laser systems, and further scaling appears possible. Further increases in the peak power will enable additional capabilities for mid-IR generation and associated applications.Ph.D.
Doctorate
Optics and Photonics
Optics and Photonics
Optics
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Chamas, Ibrahim. "The Analysis and Design of Phase-tunable Low-Power Low-Phase-Noise I/Q Signal Sources for Analog Phase Calibrated Transceivers." Diss., Virginia Tech, 2008. http://hdl.handle.net/10919/102076.
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Due to the demand for low-cost, small-form factor and large-scale integration of system-on-chip wireless transceivers, the image-reject, zero-IF and low-IF receiver architectures have become the main topologies used in mainstream wireless communication systems. Consequently, signal sources with quadrature phase outputs [quadrature oscillators (QOs)] are therefore essential, and their phase noise, driving capability, tuning range, oscillation frequency, and power consumption have a major impact on the overall receiver performance. Additionally, it is required that the QO synthesize precise I/Q waveforms across the signal bandwidth over process, voltage, and temperature variations for adequate image-rejection and signal modulation/demodulation. While the use of symmetrical layout and large inter-digitated devices minimize both systematic and random mismatches, this solution alone may not succeed in achieving the stringent performance requirements dictated by modern wireless standards particularly as the technology scales into the sub-100nm regime, necessitating both phase and gain calibration of the mismatched I/Q channels post-fabrication. Given the necessity for precise RF quadrature signal synthesis, the goal of this work is to investigate low-power low-phase-noise quadrature oscillator (QVCO) topologies with an integrated phase calibration feature.
The first part of this work focuses on the analysis and modeling of cross-coupled LC QVCOs. The analysis focuses on understanding the oscillator basic performance characteristics, design trade-offs, phase-noise performance, effect of including phase shift in the coupling paths, and on examining the quadrature accuracy in presence of process variations. New design parameters and circuit insight are developed and a generalized first order linear model and a one-port model are proposed. Particularly, we introduce the concept of an effective core and coupling transconductances to explain various oscillator properties. Additionally, a new incremental circuit element — the quadrature resistance — is introduced to evaluate the effect of coupling on the open-loop quality factor and hence on the oscillator phase noise performance. Mechanisms affecting the mode selectivity are identified and modeled. A qualitative and quantitative study of the effect of mismatch on the phase imbalance and amplitude error is presented. Particularly, closed-form intuitive expressions of the phase imbalance and amplitude error are derived and verified via circuit simulation.
Based on our understanding of the various mechanisms affecting the quadrature accuracy, the second part of this work introduces a very efficient quadrature phase calibration technique based on the disconnected-source parallel-coupled LC QVCO topology. The phase-tunable LC QVCO (PT-QVCO) achieves an ultra-wide I/Q phase tuning range without affecting the relative amplitude error or consuming additional power or chip area. Additionally, in restoring the phase balance, it is observed that the proposed method restores the phase noise performance to its optimal value which presents a potential advantage over classical calibration techniques. Time domain measurements performed on a 5 GHz prototype show that I/Q signals with phase error up to ~±30°, beyond which the VCO cores are unlocked, can be driven to perfect quadrature phase. The PT-QVCO can be tuned from 3.87-4.45 GHz at the negative mode and 4.4-5.4 GHz at the positive mode, a total of ~1.5 GHz. The fabricated circuit including pad structures occupies an area of 1.1x0.7 mm² and drains 18mW (excluding buffer circuits) from a 1.8 V supply voltage.
The third part of this work introduces a new low-power, low-phase-noise super harmonic injection-coupled LC QVCO (IC-QVCO) topology. Analysis of the waveform accuracy reveals an inverse dependence of the quadrature error on the tank quality factor thus allowing circuit optimization for both low phase noise and precise quadrature synthesis. Additionally, a tunable tail filter (TTF) is incorporated to calibrate the residual quadrature imbalance in presence of a 3-σ variation in the device parameters. An X-band IC-QVCO prototype with a TTF implemented in a 0.18μm RF CMOS process, achieves a measured phase noise figure-of-merit ranging from 177.3 to 182.6 dBc/Hz along the 9.0 to 9.6 GHz frequency tuning range while dissipating only 9mW from the 1.8V supply. The TTF reduces both the 1/f² and 1/f³ phase noise and calibrates the residual phase error within ±11° post-fabrication without affecting the relative amplitude error or the phase noise performance. The circuit performance compares favorably with recently published work.
In the fourth part of this work, we explore the implementation of LC QVCOs as potential I/Q sources at millimeter-wave (MMW) frequencies. Among the several design challenges that emerge as the oscillator frequency is scaled into the MMW band, precise quadrature synthesis and adequate frequency tuning range are among the hardest to achieve. After describing the limitation of using an MOS varactor and a digitally controlled switch capacitor array for frequency tuning, we propose an alternative frequency tuning technique based on the fundamental operation of LC QVCOs. The off-resonance operation, which is defined by the coupling network, suggests varying the coupling current to achieve frequency tuning. In essence, by modifying the bias current of the coupling transistors (GMc-tuning), a wide and linear frequency tuning range can be achieved. Extensive simulation results of a 60 GHz prototype, implemented in a 90 nm commercial RF CMOS process, demonstrates a 5 GHz of frequency tuning range (57.5 GHz → 62.5 GHz), a tuning sensitivity of 1GHz/mA, and a 4dB improvement in the phase noise compared to a varactor solution.
Finally, the Appendix includes recent research work on the analysis and design of gPh.D.
While resting in bed due to illness, the Dutch scientist Christiaan Huygens keenly observed that the pendulums of two clocks hanging on the wall moved synchronously when the clocks were hung close to each other. He concluded that these two oscillatory systems were forced to move in unison by virtue of mechanical coupling through the wall. In essence, each pendulum injected mechanical vibrations into the wall that was strong enough to lock the adjacent pendulum into synchronous motion. Injection locking of oscillatory systems plays a critical role in communication systems ranging from frequency division, to generating clocks (oscillators) with finer phase separation, to the synthesis of orthogonal (quadrature) clocks. All communication systems have the same basic form. Firstly, there will some type of an information or data source which can be a keyboard or a microphone in a smartphone. The source is connected to a receiver by some sort of a channel. In wireless systems, the channel is the air medium. Moreover, to comply with the FCC and 3GPP requirements, data can only be transmitted wirelessly within a predefined set of frequencies and with stringent emission requirements to avoid interference with other wireless systems. These frequencies are generated by high fidelity clock sources, also known as oscillators. Consider a group of people sharing the same room and hence the same channel want to share information. Without regulating the “loudness” of each communicating ensemble, the quality of communication can be severely impaired. Moreover, it is to be expected that information can be shared more efficiently if each pair is allocated non-overlapping timeslots – speak when others are quiet. Called time orthogonality, all wireless systems require precise orthogonal (quadrature) clock sources to improve the communication efficiency. The precision of quadrature clocks is determined by the amplitude and phase accuracy. This dissertation takes a deep dive into the analysis and implementation of high accuracy quadrature (I/Q) clock sources using the concept of injection locking. These I/Q clocks or oscillators, also known as quadrature voltage controlled oscillators (QVCOs), have gained enormous popularity in the last decade. The first part of this work focuses on the analysis and modeling of QVCOs. The analysis focuses on understanding the oscillator basic performance characteristics, and on examining the quadrature accuracy in presence of process variations. New design parameters and circuit insight are developed and a generalized first order linear model and a one-port model are proposed. A qualitative and quantitative study of the effect of mismatch on the phase imbalance and amplitude error is presented. Particularly, closed-form intuitive expressions of the phase imbalance and amplitude error are derived and verified via circuit simulation. Based on our understanding of the various mechanisms affecting the quadrature accuracy, the second part of this work introduces a very efficient quadrature phase calibration technique based The phase-tunable QVCO (PT-QVCO) achieves an ultra-wide I/Q phase tuning range without affecting the oscillator other performance metrics. The proposed topology was successfully verified in silicon using a 5GHz prototype. The third part of this work introduces a new low-power, low-phase-noise injection coupled QVCO (IC-QVCO) topology. An X-band IC-QVCO prototype was successfully verified in a 0.18m RF CMOS process. In the fourth part of this work, we explore the implementation of QVCOs as potential I/Q sources at millimeter-wave (MMW) frequencies. Among the several design challenges that emerge as the oscillator frequency is scaled into the MMW band, precise quadrature synthesis and adequate frequency tuning range are among the hardest to achieve. After describing the limitation of using an conventional frequency tuning techniques, we propose an alternative approach based on the fundamental operation of QVCOs that outperforms existing solutions.
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Gezer, Dogan. "A Proposed Rule For The Interconnection Of Distributed Generation And Its Economic Justification." Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/12611242/index.pdf.
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Distributed generation (DG) is electricity generation by small generating units, which are interconnected at distribution level with capacity less than 50 MW. Environmental concerns and the idea of using cheap and domestic renewable resources increased the popularity of DG following the developments in equipment technology. In Turkey, interconnection of DG is realized through the distribution busbars of 154/36 kV substation. The interconnection of DG at 36 kV feeders is not allowed by distribution system authority. This thesis proposes an interconnection rule which includes technical analyses to be conducted before the permission of interconnection of DG at 36 kV feeders. Moreover, the protection functions and operational requirements needed for the proper and safe operation of distribution system in presence of DG are introduced. A sample distribution system with relevant parameters is used for the simulation studies in Digsilent software. In order to determine the operational reserve requirement against the variations in wind generation, a statistical method including Weibull distribution, standard deviation and monthly average wind speeds is used. Convenience of hydropower plants&rsquoresponse for being backup generation against the fluctuations in wind generation is analyzed by a mid-term dynamic model of the power system. A secondary control mechanism for the integration of wind power is suggested. Finally, an economic comparison between the interconnection alternatives of hydropower and photovoltaic power plants at the distribution busbar of the 154/36 kV substation and the 36 kV feeder is done by present worth analysis using the up to date power plant costs and incentives.
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Yilmaz, Ozge. "Hazardous Waste Inventory Of Turkey." Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/12607041/index.pdf.
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In this study, hazardous waste inventory for Turkey is developed based on wastes identified as hazardous in European Waste Catalogue and Regulation on Control of Hazardous Wastes, Annex 7 Necessity of such inventory arises from importance of acquiring information on the amount of hazardous wastes generated and on their countrywide distribution for a sound hazardous waste management system for Turkey. Hazardous waste inventory is constructed by using waste generation factors obtained from literature which are coefficients that relate production with environmental emissions. Whenever possible, direct information obtained from generators was utilized. Both absolute and minor entries are covered.
It is estimated that 4,940,000 &ndash5,110,000 t/yr of hazardous wastes are being generated in Turkey. 1,790,000 &ndash
2,252,000 t/yr of these are classified as absolute entries and 3,146,000 &ndash
3,160,000 t/yr of hazardous wastes are minor entries. It is observed that highest generation occurs from mining and thermal processes which involve high amounts of minor entries. Beside these industries highest generation occurs from wood preservation. Per capita hazardous waste generation is estimated as 30 &ndash
77 kg/capita/yr which is in accordance with per capita generation range of EU. Highest hazardous waste generation occurs from Marmara Region with 527,730 t/yr followed by Aegean (524,580 t/yr), Central Anatolia (481,820 t/yr), Black Sea Region (277,850 t/yr), Mediterranean (211,580 t/yr), Southeast Anatolia (58,290 t/yr) and Eastern Anatolia (36,520 t/yr) excluding minor entries from mining industry and thermal processes. The trends in hazardous waste generation and GDP from manufacturing industry show the same trend. Contribution of regions are in the same order both in hazardous waste generation and GDP.
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Keser, Saniye. "Investigation Of The Spatial Relationship Of Municipal Solid Waste Generation In Turkey With Socio-economic, Demographic And Climatic Factors." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/3/12611575/index.pdf.
Full textAbstract:
This thesis investigates the significant factors affecting municipal solid waste (MSW) generation in Turkey. For this purpose, both spatial and non-spatial tech¬niques are utilized. Non-spatial technique is ordinary least squares (OLS) regression while spatial techniques employed are simultaneous spatial autoregression (SAR) and geographically weighted regression (GWR). The independent variables include socio-economic, demographic and climatic indicators. The results show that nearer provinces tend to have similar solid waste generation rate. Moreover, it is shown that the effects of independent variables vary among provinces. It is demonstrated that educational status and unemployment are significant factors of waste generation in Turkey.
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Mariotto, Lenois. "Avaliação da segurança da operação de sistemas elétricos de potência considerando os limites de estabilidade angular e de tensão." Universidade Federal de Santa Maria, 2008. http://repositorio.ufsm.br/handle/1/3653.
Full textAbstract:
This work presents new analytical and computational methods for operation security assessment of electric power systems by considering Angle and Voltage Stability Limits. In the context of Angle Stability, it was developed a method for estimating transient security margins based on equivalent network reduction techniques and coherent generators. The angle speed deviation was the criterion used to identify generators that swing together. The reduced order was accomplished by replacing two clusters of coherent generators by an One-Machine Infinite Bus equivalent system. With this equivalent, critical fault clearing times and security margins are calculated with the aid of the Equal Area Criterion. The results were in a good agreement when compared with others methods, especially those based on Transient Energy Function used as a Lyapunov function. The method was also applied for estimating security margins and critical fault clearing times of power systems in the presence of wind power generation. It was demonstrated that the proposed method can be used to select critical contingencies, where detailed power system models are needed such that it can reproduce the actual behavior of the system. With respect to Voltage Stability, it was developed an analytical and computational method for steady state voltage stability analysis on a P-Q plane. First of all, it was applied on a simple two-bus power system, and the analytical and computational results were compared. Then, a Voltage Stability Index was derived, in order to obtain the security margins of each bus for any operational state of an n-bus power system. It was carried out by using a power
system reduction technique. With the Voltage Stability Index, it is possible to identify critical buses and the regions that are prone to voltage collapse. The voltage stability limits of a distribution power system was also analyzed by means of the P-Q curves, by considering different operation scenarios of wind power generation. It was demonstrated that the wind power can contribute to improve the voltage security margins. Finally, the method was applied to a real power system of Companhia Estadual de Distribuição de Energia Elétrica, in the presence of wind power generation. The methods are computationally efficient and suitable for planning, operation and real-time operation of electric power systems.Este trabalho apresenta novos métodos analíticos e computacionais para a avaliação da segurança da operação de sistemas elétricos de potência considerando os Limites de Estabilidade Angular e de Tensão. No tema Estabilidade Angular, desenvolveu-se um método para a estimativa de margens de segurança transitória baseado em técnicas de redução de redes e geradores coerentes. O desvio de velocidade angular foi o critério usado para identificar geradores que oscilam juntos. A redução foi realizada substituindo-se dois grupos de geradores coerentes por um sistema Equivalente Máquina-Barra Infinita. Com este equivalente, os tempos críticos de abertura de falta e as margens de segurança são calculados com auxílio do Critério das Áreas Iguais. Os resultados encontrados foram muito satisfatórios quando comparados com aqueles obtidos por outros métodos, especialmente os que utilizam a função energia como função de Lyapunov. O método também foi aplicado para a estimativa de margens de segurança e tempos críticos de abertura de falta, em sistemas de potência na presença de geração eólica. Foi demonstrado que o método proposto é capaz de selecionar contingências críticas que precisam ser estudadas com modelos completos de modo a reproduzir o comportamento real do sistema elétrico. Com relação à Estabilidade Tensão, foi desenvolvido um método analítico e computacional para análise de estabilidade estática de tensão no plano P-Q. Primeiramente, o método foi aplicado em um sistema de potência simples com duas barras, e os resultados analíticos e computacionais foram comparados. Então, um Índice de Estabilidade de Tensão foi deduzido, para determinar a margem de segurança de cada barra para qualquer estado de operação de um sistema de potência com n-barras. Com o Índice de Estabilidade de Tensão, é possível identificar barras críticas e regiões com tendência ao colapso de tensão. Os limites de estabilidade de tensão de um sistema de distribuição foram analisados através das curvas P-Q , no qual foram considerados diferentes cenários de operação da geração eólica. Deste modo, foi demonstrado que a geração eólica pode contribuir para melhorar as margens de segurança de tensão. Finalmente, o método foi aplicado em um sistema de potência real pertencente à Companhia Estadual de Distribuição de Energia Elétrica. Os métodos desenvolvidos são computacionalmente eficientes e adequados para o planejamento da expansão e operação, bem como na operação em tempo real dos sistemas elétricos de potência.
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Britz, Andreas. "Hidden in Plain Sight: John Berryman and the Poetics of Survival." Ohio University Honors Tutorial College / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=ouhonors1274991004.
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Chakrabarty, Shantanu. "Algorithms for Adjusted Load Flow Solutions using the Complementarity Principle." Thesis, 2016. http://etd.iisc.ac.in/handle/2005/4161.
Full textAbstract:
The state of a given power system i.e. voltage magnitudes and angles at all the buses can be computed using the Newton-Raphson Load Flow (NRLF) method when active power and reactive power loads are specified at all the buses of the system. This computation can be carried out more e ciently(in terms of computer memory and time) using the Fast Decoupled Load Flow(FDLF) method for a large class of systems. These methods are the most widely used methods in power system studies.
NRLF and FDLF methods require modifications, if voltage magnitude is spec-i ed at some of the generator buses instead of the reactive power load. In such situations, generator reactive power outputs(manipulated by adjusting the field excitation) have to be adjusted to meet this specification. This necessitates the determination of the value of these additional control variables. There are some more similar adjustments that are required to be made in a practical load flow. Sometimes, the voltage at some load buses may be specified. They are to be maintained at the scheduled value using the taps on in-phase transformers(OLTC transformers). Similarly, it is possible in some situations that the active power flow in some lines are specified to be kept at a particular value. The device which facilitates such a control is the phase shifting transformer(PSTs) and the PST tap value is the additional control variable to be determined. The other operation of interest in interconnected power systems is the area interchange control(AIC). This requires that the sum of active power flow between two areas of the system is maintained at the specified value. The control variable value that enables this adjustment is the active generation in a particular generator bus in the area referred to as a swing bus. The load flow problem is referred to as a adjusted load flow problem in cases where in, some of these control variables must also be determined in addition to the state of the system.
It must be pointed out here that the control variables must be strictly kept within their limits while bringing the controlled variables to their specified values. If a control variable tends to reach a value beyond its limits, then it is to be set at the limit and the corresponding controlled variable will not be at its scheduled value. Adjusted load flow problems generally involve many control variables of the same type or multiple control variables of different types. The challenge in finding adjusted load flow solutions stems from the fact that the relation between the controlling and controlled variables is not one to one; each controlling variable affects many of the controlled variables.
The existing approaches of adjusted load flow solutions generally consider only one type of these adjustments. There are only a very few attempts where more than one type of adjustment is considered. The two broad directions pursued for developing algorithms for adjusted solutions, by the earlier researchers are (1) Introducing additional equations in order to include control variable(between iterations) and (2) Adjusting the controlling variables between unadjusted load flow solution iterations based on the local sensitivity of the controlled variable with respect to a particular controlling variable. The schemes in use for finding adjusted load flow solutions have a flavour of trial and error type of algorithms. Their success in any situation is known to depend on specific details of implementation. Implementation details that guarantee success are not in the public domain. Many times they exhibit oscillatory convergence behaviour requiring very large number of iterations or fail to converge. It is also known that in some situations these algorithms could converge to anomalous solutions(solutions that are inconsistent with practical system behaviour). Such limitations of the existing approaches and also the need for developing better methods is well documented in the literature.
Some recent work has shown the promise of the formulation of the adjusted load flow problem in the complementarity framework considering a few of the adjustments. This thesis is intended to further explore this promising direction of investigation. In particular, in this thesis, we develop new algorithms in complementarity framework for the following situations and demonstrate their attractive features as compared with the existing approaches.
In this thesis, the following algorithms have been proposed, developed, tested and their performance compared with the existing algorithms. .
Two algorithms for including OLTC adjustments, in the FDLF method as Mixed Complementarity Problem(MCP) and Non-linear Complementarity(NCP) formulations.
In addition, the above algorithms are further extended to incorporate generator bus Q-limit adjustments simultaneously with the OLTC adjustments.
Two new algorithms(two each in MCP and NCP formulations) are developed to handle generator Q-limits and OLTC adjustments individually as well as together in the NRLF formulation in rectangular coordinates.
Four algorithms(two in MCP and two in NCP) to handle PST constraints in NRLF and FDLF methods.
Four algorithms(two in MCP and two in NCP) to handle AIC constraints in NRLF and FDLF methods.
In addition, the PST and AIC adjustment algorithms above are combined to simultaneously carry out PST and AIC adjustments in NRLF as well as FDLF methods.
Four algorithms(two for NRLF and two for FDLF) to simultaneously incorporate all the four adjustments simultaneously using MCP and NCP formulations. These algorithms are also shown to be capable of incorporating simultaneously any subset of these four adjustments
The thesis focusses only on incorporating adjustments in the NRLF and FDLF methods as they are the most widely used schemes in the industry as well as the academia. It is also pointed out that the investigations here consider the adjustment problem in the traditional framework and hence, none of the power electronics based control equipment or the modern distributed generation sources are considered here.
Results of extensive computational experiments are presented and the attractive performance of the new algorithms as compared with the traditional ones are high-lighted. All the new algorithms developed here are fundamentally different from the existing adjusted load flow approaches(not based on complementarity framework) in that they meet the specifications on the system variables and limits on the controlling variables automatically; without requiring either heuristic algorithmic choices or problem specific algorithm manipulation - a fairly common feature in all the existing approaches. This extremely desirable feature of the proposed algorithms is due to the fact that the pro-posed formulations for the adjusted load flow problems in complementarity framework, transform these problems to that of solving a fixed set of non-linear equations.
The results in the thesis provide strong evidence of the promise of the new methods for adoption into the widely used NRLF and FDLF programs so as to make solving the adjusted load flow problem as simple as solving the unadjusted load flow problem.
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Lin, Tzung-Feng, and 林宗鋒. "A Q-Learning with Continuous Action Generation in Multi-agent Cooperation." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/00581160591686023927.
Full textAbstract:
碩士國立中正大學
機電光工程研究所
92
In this thesis, we propose a Q-learning with continuous action generation and extend this algorithm to multi-agent systems. We implement this algorithm in a task that there are two robots taking action independently and both are connected with a straight bar. The goal of them is to cooperate with each other to pass through a gate in the middle of the grid environment. Conventional Q-learning needs pre-defined quantized state space and action space. It is not practical on real robot applications since discrete and finite numbers of action sets could not precisely identify the variances of the different positions on the same state element which the robot located on. We utilize the fuzzy-based cerebellar model controller (FCMAC) and its ability of categorization to calculate the weighting distribution of the state the robot located in and the states all surrounded. This provides better resolution of the weighting distribution for the state space where the robot located in. We can have a continuous action generation by linear combination of the weighting distribution of the state space which we calculated with FCMAC and the optimal policy of each state excited by robot derived from Q-learning. This continuous action value is more practical and has better performance than the method which has only discrete and finite numbers of action sets.
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Huang, Kuan-Hao, and 黃冠皓. "Q-switched and mode-locked pulse generation from ytterbium doped fiber." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/4vs5e2.
Full textAbstract:
碩士國立臺北科技大學
光電工程系研究所
104
In this work, I investigated the Q-switched and mode-locked pulse generation in all-normal dispersion passively mode-locked Yb-doped fiber laser (PML-YDFL) based on the Bi2Se3/Polyvinyl alcohol (PVA) film or fiber-compatible topological insulator saturable absorber (TI-SA). First, we synthesized the Bi2Se3 nano-plates (NPs) via a polyol method and then dissolved the PVA into Bi2Se3 solution to produce the Bi2Se3/PVA solution. Through the drying of the Bi2Se3/PVA solution in standard cell within the oven, the dark and light Bi2Se3/PVA films were produced with high and low transmittance. After insertion the dark Bi2Se3/PVA films into an Yb-doped fiber laser laser (YDFL), the Q-switched pulse can be generated after properly adjusting of the polarization controller. As pump power increased from 105 to 182 mW, the repetition rate of Q-switched pulses was increased from the 86 KHz to 138 KHz. In addition, the mode-locked pulses with 16 MHz repetition rate and the shortest pulsewidth about 380 ps were demonstrate through the light Bi2Se3/PVA film with the pump power at 380 mw. We also fabricate the fiber-compatible TI-SA by depositing the Bi2Se3 NPs onto the fiber end facet. In comparing to the PVA film, the PML-YDFL can be mode locking at lower threshold power and higher slope efficiency. With the pump power at 131 mw, the mode-locked pulses with 13 MHz repetition rate and the shortest pulsewidth about 331 ps were demonstrate through the fiber-compatible TI-SA. Our experimental results indicate that the TI-SA made by the Bi2Se3 can be exploited for the pulsed laser applications.
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許展榕. "Supercontinuum Generation from Microstructured Fibers by a Q-Switched Mode-Locked Laser." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/35800535089038726158.
Full text
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Wang, Wei-Hsiang, and 王韋翔. "Optical Harmonic Generation of High-Power Q-switched Nd:YAG laser in Argon." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/50990426874705204959.
Full text
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Ya-tingChan and 詹雅婷. "A study on Q-switched Ince-Gaussian laser generation with acousto-optic modulator." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/57199672130697982997.
Full textAbstract:
碩士國立成功大學
物理學系
103
The purpose of this study is to generate pulsed Ince-Gaussian(IG) lasers in end-pumped solid-state lasers and to reach different modes of selection and application of Q-switched pulsed lasers. The active Q-switch we adopting in this study is the acousto-optic (AO) modulator. However, we also adopt the chopper in this study. In the first part of the experiment, both of laser systems can be used to generate pulsed IG laser and observe the relaxation oscillation (RO). The second part of the experiment, we study on Q-switched Ince-Gaussian laser generation with AO modulator. Experimental result shows that, using AO Q-switched laser system, this study successfully generates pulsed IG lasers of several different modes. Besides, by classifying IGMs into even and odd groups, this study gives discussions on the relation between pulsed Ince-Gaussian lasers of different modes.
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Holzer, Patrick. "Recovering Short Generators of Principal Fractional Ideals in Cyclotomic Fields of Conductor p^\alpha q^\beta." Master's thesis, 2017. http://tuprints.ulb.tu-darmstadt.de/6155/1/Master%20Thesis%20Patrick%20Holzer.pdf.
Full textAbstract:
Some recent cryptographic schemes rely on the hardness of finding a shortest generator of a principal (fractional) ideal in an algebraic number field $K$ in the logarithmic embedding with some guaranteed small generator, given some $\mathbb{Z}$-basis of the principal ideal. This problem can be split into two parts. First, recover some arbitrary generator of the ideal, which is known as the principal ideal problem (PIP).
Second, transform this generator into some shortest generator.
The first part is known to be solvable in polynomial time on quantum computers for cyclotomic fields of prime-power conductor and for arbitrary number fields under the generalized Riemann hypothesis, see Campbell, Biasse et al.
The second part is known to be solvable in polynomial time on classical computers for cyclotomic number fields of prime-power conductor, see Cramer, Ducert Peikert and Regev.
In this work we entirely focus on the second task and extend the work of Cramer, Ducas, Peikert and Regev to cyclotomic fields $K=\Q(\xi_m)$ of conductor $m=p^\alpha q^\beta$, where $p,q$ are distinct odd primes.
Their algorithmic approach mainly relies on the fact that there is a well suited basis of the group of cyclotomic units which are a subgroup of $\OK^\times=\mathbb{Z}[\xi_m]^\times$ with small enough finite index. We consider the group generated by these elements in the case that $m=p^\alpha q^\beta$ and introduce a new notion for odd prime pairs $(p,q)$, named generator prime pairs, which provides a criterion to check whether the index of this subgroup in $\OK^\times$ is finite or not.
We prove, that this basis is well suited to recover some shortest generator of a principal ideal in quantum polynomial time in the finite case, i.e., if $m=p^\alpha q^\beta$ for some generator prime pair $(p,q)$ with sufficiently large $\alpha,\beta \in \mathbb{n}$ with bounded distance.
Further, we consider the approximate ideal shortest vector problem in cyclotomic fields $\Q(\xi_m)$, where the task is to find short elements in arbitrary ideals $\mathfrak{a}$ in $\OK$ in the Minkowski embedding. In our second main contribution, we generalize the results of Cramer and argue, that one can efficiently solve the ideal shortest vector problem with an approximation factor $\exp(O(\sqrt{m}))$ in cyclotomic fields of conductor $m=p^\alpha q^\beta$ on quantum computers, if $(p,q)$ is an $(\alpha,\beta)$-generator prime pair.
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Wang, Chun-lin, and 王俊霖. "Single aperiodically poled lithium niobate for simultaneous laser Q-switching and optical parametric generation in a Nd:YVO4 laser." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/08345317865791381606.
Full textAbstract:
碩士國立中央大學
光電科學研究所
98
Optical parametric oscillators (OPOs) can produce wavelength tunable coherent light sources and have been widely used in various applications including the remote sensing, spectroscopy, nonlinear optics, range finder, optical communications, and bio-medicine. Several high-efficiency intracavity wavelength converters have been developed via the use of a nonlinear crystal in an acousto-optic or electro-optic (EO) Q-switched solid-state laser. However, a more compact integrated system performing the same device functions is still rare. In this thesis, we have devoted to integrate two device functions in a monolithic LiNbO3 crystal. These two devices are an EO Q-switching and an optical parametric generator (OPG). An aperiodically poled lithium niobate (APLN) crystal has been designed and fabricated in this work to simultaneously satisfy the phase-matching conditions required for functioning the two devices. We further inserted this APLN crystal in a Nd:YVO4 laser system to simultaneously function as a laser Q switch and an intracavity optical parametric amplifier. We have successfully demonstrated an efficient EO Q-switched IOPO in a compact diode-pumped 1064-nm Nd:YVO4 laser achieved using a single intracavity APLN.The APLN device was designed using the SA optimization method. It can simultaneously function as an EO Q-switch and an OPG.The OPO efficiency achieved with the system using the APLN device has been ~1.67 times higher than that with a system using a cascade PPLN device of the same device length and under the same system operating conditions. When the intracavity APLN was driven with a ~ 360-V pulse train at 1 kHz, we observed ~ 33 % energy depletion in fundamental laser pulses, yielding ~ 5-ns, ~ 1029W peak-power 1550-nm OPO laser pulses from this compact laser system pumped at 8.4-W diode power.
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Huang, Chi-Chung, and 黃啟創. "Q-switched and mode-locked pulses generation in a c-cut Nd:LuVO4 laser by simultaneous acousto-optic modulator and GaAs." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/946929.
Full textAbstract:
碩士國立臺北科技大學
光電工程系研究所
98
In this thesis, we investigate the characteristics of Q-switched and mode-locked (QML) pulses generation in c-cut Nd:LuVO4 laser by using an acousto-optic modulator (AOM) and GaAs wafer. In only using the AOM, the periodic QML envelope with relative high energy pulses has been experimentally demonstrate. However, the shape of generate Q-switched envelope is asymmetric that has longer falling time than rising time. This result is opposite to the Q-switching envelope generated by the GaAs wafer that has longer rising time. Besides, the period of the Q-switching envelope is un-regular and has relative large amplitude fluctuation. In order to generation periodic and symmetric Q-switched envelope, we combine AOM and GaAs wafer in laser cavity and demonstrate the more symmetric shape can be produced at lower pump power. However, the falling time of Q-switched envelope shrinkage seriously at relative higher pump power that is due to the two photon absorption of the GaAs
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Sukhoy, Kostyantyn. "Generation of green second harmonic radiation in LBO, BiBO, KTP, and PPLN crystals using passively Q-switched sub-nanosecond microchip laser." 2011. http://hdl.handle.net/1993/4744.
Full textAbstract:
A sub-nanosecond green laser source has big demand in such fields like spectroscopy, micromachining, fluorescence imaging, and laser displays. Most often green light is produced by frequency doubling of pulsed laser sources based on Nd3+-ion or Yb3+-ion doped gain media that oscillate in the near-IR range. For creating compact and relatively small source of green light suitable for broad type of applications a passively Q-switched Nd:YAG microchip laser (Teem Photonics) operating at 1064 nm with 6.9 kHz repetition rate was chosen. It delivers 560 ps long pulses with 10 μJ energy, corresponding to an average output power of 69 mW. Crystals of BiBO, KTP, LBO, and PPLN were chosen for frequency doubling. Main goal of this work was to study the characteristics of these crystals under similar experimental conditions and to select the most efficient one for this task. To optimize second harmonic generation (SHG) process, different focusing conditions were used during the experiments. In this work we measured the second harmonic output power as a function of the incident power, beam profile for fundamental and second harmonic radiation for all crystals, and second harmonic output power as a function of temperature for PPLN crystal. Crystal of PPLN was found to be the most suitable for SHG process and produced it with up to 60% conversion efficiency.
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Gaspar, Ulisses Emanuel Rodrigues. "Aplicação de metodologia Next Generation Sequencing na pesquisa de determinantes genéticos da febre Q crónica na via de sinalização IL12-IFNy." Master's thesis, 2021. http://hdl.handle.net/10400.6/11506.
Full textAbstract:
A febre Q é uma zoonose causada por Coxiella burnetii, na qual cerca de 60% dos doentes
apresentam quadros clínicos de infecção aguda, com recuperação após intervenção
clínica. No entanto, nos casos de febre Q crónica, a infecção culmina em complicações
graves, frequentemente endocardites. Mesmo com medidas preventivas, a incidência da
febre Q tem vindo a aumentar, principalmente na Península Ibérica. A fisiopatologia da
infecção por C. burnetii assemelha-se à do Mycobacterium tuberculosis. Em ambas as
infecções, a via interleucina12—interferão gama (IL12-IFN?) desempenha um papel
importante na sobrevivência e replicação intracelular bacteriana. As doenças causadas
por micobactérias apresentam homogeneidade fisiológica inerente à deficiência de
interferão gama (IFN?), o que é fundamentado pela identificação de determinantes
genéticos dessas infecções na via IL12-IFN?. No entanto, esta via permanece
praticamente inexplorada em termos de associação genética com a febre Q crónica,
enaltecendo a necessidade destes estudos. Assim, nesta investigação procurou-se
identificar variantes associadas a febre Q crónica através de uma abordagem por estudos
populacionais de associação genótipo fenótipo com base em genes candidatos
(Candidate Gene Association Studies - CGAS).
Esta abordagem insere-se numa arquitetura de estudo caso-controlo. Selecionaram-se
genes candidatos e optou-se pela utilização de uma estratégia de sequenciação de nova
geração (Next Generation Sequencing – NGS) para a genotipagem das regiões 5’UTR e
os exões dos genes candidatos. Após consentimento informado, foram recrutados 34
indivíduos saudáveis e 60 doentes com febre Q (43 formas agudas e 17 formas crónicas).
Os genes do receptor ß1 de interleucina-12 (IL12RB1), receptor 1 de interferão gama
(IFN?R1) e receptor 2 de interferão gama (IFN?R2), com fragmentos de 2kb a 17kb,
foram amplificados por polimerase de reação em cadeia (PCR) de longo alcance com
ácido desoxirribonucleico (ADN) polimerase Takara LA Taq® para construção de
bibliotecas Nextera e sequenciação com tecnologia da Illumina®. Uma vez que a NGS
trabalha com milhares de milhões de dados em simultâneo requer a aplicação de várias
métricas de controlo de qualidade de modo a garantir resultados fidedignos. Para além
destas métricas foram ainda implementadas métricas específicas para CGAS que têm por
objectivo diminuir a obtenção de erros por falsos positivos na análise estatística.
Do presente trabalho de investigação resultou uma lista de polimorfismos de nucleótido
único (Single Nucleotide Polymorphism - SNP) dos genes IL12RB1, IFN?R1 e IFN?R2
em indivíduos com febre Q crónica, aguda e numa amostra de conveniência de indivíduos saudáveis. Estes dados têm a necessária qualidade para constituir uma mais valia,
podendo ser aplicados a diferentes estudos.
Futuramente, esta lista de SNPs será usada em estudos de associação genótipo-fenótipo
para compreender se existem variantes na via IL12-IFN? associadas à apresentação
clínica doença. Assim, estes resultados poderão vir a ser um importante avanço clínico
não só para antecipar formas crónicas da doença como para o desenvolvimento de
estratégias de prevenção e para prestação de melhores cuidados de saúde a estes doentes.Q fever is a zoonosis caused by Coxiella burnetii, in which about 60% of the affected patients develop acute Q fever, recovering after clinical intervention. However, in chronic Q fever cases, the disease is accompanied with serious complications, mainly manifested as endocarditis. Even with preventive measures, the incidence of Q fever has been increasing, namely in the Iberian Peninsula. The pathophysiology of C. burnetii infection resembles that of Mycobacterium tuberculosis, both characterized by granuloma formation. In this context, the interleukin 12 - interferon ? (IL12-IFN?) pathway plays a major role in intracellular bacterial survival and replication. Diseases caused by mycobacteria display physiological homogeneity inherent to interferon ? (IFN-?) deficiency, since genetic determinants of these infections have been identified in the IL12-IFN? pathway. Despite of the above mentioned, the association between genetic variants this pathway and chronic Q fever remains practically unexplored. Thus, in this investigation we seek to establish a list of variants within the IL12-IFN? pathway with pathogenic potential associated with the development of chronic Q fever. therefore, we sought to identify variants associated with chronic Q fever resorting to candidate-gene, population association analysis in a Candidate Gene Association Studies (CGAS) approach. This approach is part of a case-control study architecture. Candidate genes were selected and a Next Generation Sequencing (NGS) strategy was chosen for the genotyping of the 5’UTR region and exons of candidate genes. After informed consent, 34 healthy individuals and 60 Q fever patients (43 acute and 17 chronic forms) were recruited. The genes interleukin-12 receptor ß1 (IL12RB1), interferon ? receptor 1 (IFN?R1) and interferon ? receptor 2 (IFN?R2), were amplified in 2kb to 17kb fragments, by long-range polymerase chain reaction (PCR) with Takara LA Taq® deoxyribonucleic acid (DNA) polymerase for Nextera library construction and Illumina® sequencing. Since NGS works simultaneously with billions of data points, it requires the application of several quality control metrics in order to guarantee reliable results. In addition to these metrics, specific metrics for CGAS were also implemented to reduce possible false positives in the statistical analysis of the data. The present research work provided a list of single nucleotide polymorphisms (SNPs) of the IL12RB1, IFN?R1 and IFN?R2 genes, observed in patients with chronic Q fever, acute Q fever and in a convenience sample of healthy individuals. These data have the necessary quality to constitute an asset and can be applied to different studies. In the future, this list of SNPs will be used in genotype-phenotype association studies to understand whether there are variants in the IL12-IFN? pathway associated with the clinical presentation of the disease. Thus, these results could prove to be an important clinical advance not only to anticipate chronic forms of the disease but also to develop prevention strategies and to provide better health care to these patients.
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Huang, Yao-Hsien, and 黃耀賢. "Monolithic aperiodically and periodically poled lithium niobate for simultaneous laser Q-switching and intracavity sum-frequency generation in a dual-wavelength Nd:YVO4 laser." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/95673719412115824709.
Full textAbstract:
碩士國立中央大學
光電科學研究所
100
Abstract Bragg condition is very sensitive to incident wavelength. With this characteristic, we can diffract wavelength with appropriate Bragg structure. In this letter, we first design an aperiodic structure with the help of simulated anneal algorism which compensates reciprocal vectors of dual wavelength emitted in Nd doped solid state laser system. Lithium Niobate is a great electro-optic crystal. With the high electric field poled, we can generate the structure we calculate previously on LN crystal. Thus, a 25 mm long, 5 mm in width and thickness of 0.5 mm aperiodic poled Lithium Niobate Bragg diffraction cascade 15mm long periodical poled Lithum niobate sum frequency Generation device is fabricated successfully. In experiment, we measured the high diffraction efficiency both on 1064 nm and 1342 nm, 96% and 87% respectively, at –250 and -350 volt applied voltage. Furthermore, we put our chip into the Nd:YVO4 slid sate laser system and applied a periodic electric field to the chip, we can turn it into a cavity Q-switch device. With the sum frequency crystal BIBO, we can generate narrowand high peak power 593 nm output from dual emission wavelength of Nd 1064 nm and 1342 nm. In results, the yellow-orange light output with the pulse width of 8 ns and peak power of 430 W under 8.142 W of Nd absorption power at tempature 73℃.
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Chou, Pin-yu, and 周䓵譽. "Monolithic two dimension aperiodically poled lithium niobate for simultaneous laser Q-switched and intracavity sum frequency generation in a dual wavelength Nd:YVO4 laser." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/59303410051352864747.
Full textAbstract:
碩士國立中央大學
光電科學與工程學系
102
Compact, high-repetition-rate pulsed visible coherent light sources are attractive for many applications, such as biomedicine, remote sensing, astronomy, and displays. The Q-switched all-solid-state laser technique can be a promising approach to attain such light sources. Moreover, due to the high nonlinearity and highly engineerable characteristics of the quasi-phase-matching(QPM) material, a device as simultaneous a Q-switch and wavelength converter can be realized in a two-dimensional aperiodically poled lithium niobate (APPLN). In this thesis, we have designed and fabricated a unique 2D APPLN device integrating the functionalities of the Q-switch for two laser lines(1064nm and 1342 nm) simultaneously and sum frequency generator in a Nd:YVO4 laser system to generate pulsed yellow-orange laser, the such device was designed by aperiodic optical superlattice(AOS) technique and optimized by simulated annealing(SA) method. In operation, 350 volts at repetition rate of 1 KHz drove the device, while the diffraction efficiencies of 1064 nm and 1342 nm of 60 % and 55 % were measured, respectively. At diode pump power of 5.7 watts, a yellow-orange pulse with pulse width of 8.4 ns, bandwidth of 0.4 nm, and peak power of 512 can be obtained, meanwhile, the peak-to-peak fluctuation of 8.9% was also found.
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See, Chan H., Raed A. Abd-Alhameed, and Peter S. Excell. "Mathematical model for calibration of nonlinear responses in biological media exposed to RF energy." 2014. http://hdl.handle.net/10454/10784.
Full textAbstract:
noThis paper presents a circuit model which is used to calibrate the performance of nonlinear RF energy conversion inside a high quality factor resonant cavity with a known nonlinear loading device. The nonlinear radiofrequency energy conversion can be detected by exciting the fundamental operating frequency and observing the second harmonic resonant frequency within a doubly resonant cavity. By implementing the proposed mathematical model, the required input power can be estimated to maximise the chance of detecting the weak second harmonic signal prior to carry out the measurement.
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Rodrigues, Inês Branco de Paiva de Jesus. "Geração Z: uma geração de consumo sustentável na indústria da roupa?" Master's thesis, 2021. http://hdl.handle.net/10071/24348.
Full textAbstract:
O tema desta dissertação permite averiguar qual é a perceção que existe na geração Z sobre a compra
de roupa sustentável, os seus padrões de consumo e as principais barreiras existentes para o
desenvolvimento sustentável na indústria da roupa.
Esta geração é considerada a geração do digital, onde o poder das redes sociais e das
denominadas influencers traz pressão social inerente aos seus estilos de vida, sobretudo no que toca
à compra de roupa, existindo ainda desafios que determinam o gap evidente entre a atitude e intenção
de compra. Estes jovens não têm um poder de compra avultado e têm pouca facilidade em
encontrarem lojas de roupa sustentável, remetendo-os quase sempre para as lojas de fast fashion.
Os nossos objetivos da investigação passam por compreender, de forma generalizada, de que
forma os jovens da geração Z se percecionam enquanto consumidores sustentáveis na indústria da
roupa e quais os principais entraves que levam à existência do gap mencionado anteriormente. Foi
desenvolvido um estudo qualitativo de natureza exploratória (focus groups) que permitiu apurar a
perceção desta geração face à temática em estudo.
Os resultados revelam que de facto esta geração apresenta uma consciencialização desta
temática. No entanto é influenciada, de forma significativa, através das redes sociais no que toca aos
seus padrões de consumo. Assim, esta geração apresenta características que potenciam sua
suscetibilidade à compra de roupa sustentável, mas, para que tal aconteça, é ainda preciso que sejam
tomadas muitas ações por parte das empresas/marcas que potenciem o consumo da roupa
sustentável.The theme of this dissertation allows us to investigate the perception that exists in the Z generation about the purchase of sustainable clothing, their consumption patterns and the main existing barriers to sustainable development in the clothing industry. This generation is considered the digital generation, where the power of social networks and the so-called influencers bring inherent social pressure to their lifestyles, especially when it comes to buying clothes, and there are still challenges that determine the evident gap between purchase attitude and intention. These young people don't have a lot of purchasing power and find it difficult to find sustainable clothing stores, almost always referring them to fast fashion stores. Our research objectives are to understand, in a generalized way, how young people of generation Z perceive themselves as sustainable consumers in the clothing industry and what are the main barriers that lead to the existence of the gap mentioned above. A qualitative exploratory study was developed (focus groups) that allowed us to ascertain the perception of gen Zers regarding the topic under study. The results show that in fact this generation is aware of this issue. However, they are significantly influenced by social networks in terms of their consumption patterns. Thus, this generation presents characteristics that increase its susceptibility to buying sustainable clothing, but for that to happen, it is still necessary that many actions are taken by companies/brands that promote the consumption of sustainable clothing.
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Oliveira, Margarida Ramalho Almeida. "The effect of feed-in tariffs on the deployment of renewable energies." Master's thesis, 2020. http://hdl.handle.net/10071/21157.
Full textAbstract:
This study intends to evaluate the relationship between the use of feed-in tariffs and the deployment of renewable energies. We collected a sample of 28 EU countries for the period 1990-2017. Following a panel data approach, we performed a random effects estimation. Among the several explanatory variables, feed-in tariffs, discriminated
by different renewable energies’ technologies, are defined as the variables of interest in explaining the share of the
electricity capacity generated by non-hydro renewable sources. The results suggest that only Wind and Waste
impact the dependent variable allied to the share of electricity produced from both nuclear and fossil fuel sources and the prices of traditional energy sources. The previous findings are robust for OECD member countries and also for countries where feed-in tariffs are applied at least once in the period considered.Este estudo pretende avaliar a relação entre as tarifas feed-in e o desenvolvimento das energias renováveis. Selecionamos uma amostra de 28 países da UE cobrindo o período de 1990-2017. Para analisar os dados, adotamos uma abordagem de dados em painel realizando uma estimativa de efeitos aleatórios. Entre as diversas variáveis explicativas, os valores de tarifas feed-in discriminadas pelos diferentes tipos de tecnologia são definidos como as variáveis de interesse em explicar a parcela da capacidade elétrica gerada a partir de uma fonte renovável não hídrica. Os resultados sugerem que, das diferentes tecnologias em análise, apenas o Vento e os Resíduos impactam variável dependente, aliados à parcela da eletricidade gerada a partir de uma fonte de combustível nuclear e fóssil e dos preços das fontes tradicionais de energia. As conclusões anteriores são robustas para os países membros da OCDE e também para os países onde a tarifa feed-in é aplicada a pelo menos uma das tecnologias em análise.