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Dissertations / Theses on the topic 'Emiter'
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1
Tomešová, Tereza. "Autonomní jednokanálový deinterleaving." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2021. http://www.nusl.cz/ntk/nusl-445470.
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This thesis deals with an autonomous single-channel deinterleaving. An autonomous single-channel deinterleaving is a separation of the received sequence of impulses from more than one emitter to sequences of impulses from one emitter without a human assistance. Methods used for deinterleaving could be divided into single-parameter and multiple-parameter methods according to the number of parameters used for separation. This thesis primarily deals with multi-parameter methods. As appropriate methods for an autonomous single-channel deinterleaving DBSCAN and variational bayes methods were chosen. Selected methods were adjusted for deinterleaving and implemented in programming language Python. Their efficiency is examined on simulated and real data.
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Johnson, Eric (Eric M. ). "Self-installation of drip irrigation emitters for prototype emitter testing." Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/105700.
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Thesis: S.B., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2016.Cataloged from PDF version of thesis.
Includes bibliographical references (page 31).
In this thesis, I tested methods of adhering factory-made drip emitters to the interior of short segments of piping. Different types of adhesive and pipe material combinations were tested, and I selected three combinations for further testing. Performance similar to factory-installed drip emitters was achieved at low pressure, but the necessary watertight seals repeatedly burst at higher water pressures. Alterations to the drip emitter and installation procedure are recommended to increase reliability and resilience of the installation.
by Eric Johnson.
S.B.
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Weynand, Vance Leo. "Evaluation of the application uniformity of subsurface drip distribution systems." Thesis, Texas A&M University, 2003. http://hdl.handle.net/1969.1/211.
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The goal of this research was to evaluate the application uniformity of subsurface drip distribution systems and the recovery of emitter flow rates. Emission volume in the field, and laboratory measured flow rates were determined for emitters from three locations. Additionally, the effects of lateral orientation with respect to slope on emitter plugging was evaluated. Two different emitters were tested to evaluate slope effects on emitter plugging (type Y and Z). The emitters were alternately spliced together and installed in an up and down orientation on slopes of 0, 1, 2 and 4% and along the contour on slopes of 1 and 2%. The emitters were covered with soil and underwent a simulated year of dosing cycles, and then flushed with a flushing velocity of 0.6 m/s. Initial flow rates for the two emitter types were 2.38 L/hr with a C.V. of 0.07. There was no significant difference in flow rates among slopes for type Y emitters, but there was a significant difference between the 1% and 2 % contour slopes for type Z emitters. Application uniformity of three different laterals at each site was evaluated. Sections of the lateral from the beginning, middle and end were excavated and emission volumes were recorded for each emitter. Application uniformity of laterals ranged from 48.69 to 9.49%, 83.55 to 72.60%, and 44.41 to 0% for sites A, B, and C, respectively. Mean emitter flow rate was 2.21, 2.24, and 2.56 L/hr for sites A, B, and C, respectively under laboratory conditions. Application uniformity under laboratory conditions ranged from 70.97 to 14.91%, 86.67 to 79.99%, and 85.04 to 0.00% for sites A, B, and C, respectively. A flushing velocity of 0.15 m/s with no chlorination, shock chlorination of 3400 mg/L and flushing velocity of 0.15 m/s, and shock chlorination of 3400 mg/L and flushing velocity of 0.6 m/s treatment regiments were applied to all laterals collected to assess emitter flow rate recovery to the nominal flow rate published by the manufacturer. All laterals showed an increase in the number of emitters within 10% of the published nominal flow rate.
4
Keyes, Edward Patrick Carleton University Dissertation Engineering Electrical. "Emitter resistance and current gain in polysilicon emitter transistors." Ottawa, 1987.
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Mackay, Gary F. (Gary Francis) Carleton University Dissertation Engineering Electrical. "Emitter resistance and current gain in rapid thermal annealed polysilicon emitter transistors." Ottawa, 1991.
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6
Hartup, David Carl. "Emitter identification using optical processors." Diss., Georgia Institute of Technology, 1991. http://hdl.handle.net/1853/15672.
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Rowlandson, Michael Barry Carleton University Dissertation Engineering Electrical. "A true polysilicon emitter transistor." Ottawa, 1988.
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8
Post, Ian R. C. "PNP polysilicon emitter bipolar transistors." Thesis, University of Southampton, 1992. https://eprints.soton.ac.uk/394020/.
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Šimonová, Lucie. "SELEKTIVNÍ EMITOR PRO TERMOFOTOVOLTAICKÉ SYSTÉMY." Doctoral thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2021. http://www.nusl.cz/ntk/nusl-445179.
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The work is focused on research and development of a suitable method for creating a selective emitter for the visible and near infrared region so that they are able to work optimally together with silicon photovoltaic cells in a thermophotovoltaic system. The aim of the work was to develop a new method of creating very fine structures outside the current standard, which will increase the emissivity of the base material to meet the needs of a selective emitter for the VID and NIR region. The methods available to us for the creation of structures were chosen, from which we eliminated all unsuitable ones and we introduced the optimal procedure and parameters for their creation for the selected method. In this work, we focused on both ceramic and metallic materials, whose heat resistance and selective properties are key to this work. Part of the development of the emitter structures was also the need for pretreatment of the substrate itself, where great emphasis was placed on the purity of materials and surface roughness. Since ceramic materials cannot achieve a surface roughness so low that the desired structures can be formed, these materials have been purposefully used primarily for the purpose of combining the base material with thin layers of other high temperature material. Their compatibility and suitability were verified in terms of adhesion and subsequent heat resistance. The main material for the formation of fine structures was purposefully chosen tungsten, for which we verified the influence of the formed structure on the emissivity as well as the thermal stability during long-term exposure to high temperatures. The work thus represents not only a new method of creating very fine structures, which are not normally formed in such subtlety, but also opens the way to new possibilities of combining more materials to achieve the required selectivity of the thermophotovoltaic emitter.
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Constantinou, Marios, Michael Gehde, and Ronald Dietz. "Emitter - Material – A complex system." Universitätsbibliothek Chemnitz, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-198230.
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Der Vortrag zeigt die Komplexität der Wechselwirkungen zwischen Infrarotstrahler und Werkstoff beim Infrarotschweißen von Kunststoffen auf. Hierfür werden die Haupteinflüsse auf die Strahler-Werkstoff-Wechselwirkungen beschrieben. Diese sind das Emissionsverhalten des Infrarotstrahlers und das Absorptionsverhalten des Kunststoffs. Der Einfluss der Infrarotstrahlerart (Quarzglasstrahler, Metallfolienstrahler) und von Füllstoffen (Ruß, Glasfasern) im Kunststoff wird näher betrachtet. Zudem enthält der Vortrag eine Empfehlung für die Vorgehensweise beim Infrarotschweißen von Kunststoffen, die Vor- und Nachteile des Fügeverfahrens und einen Einblick in aktuelle Forschungsaktivitäten auf dem Gebiet des Infrarotschweißens von Kunststoffen.
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Mojrová, Barbora. "Solární články z monokrystalického křemíku typu n s vysokou účinností." Doctoral thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2019. http://www.nusl.cz/ntk/nusl-408053.
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Tato dizertační práce je zaměřena vývoj a ověřování nových postupů přispívajících ke zvýšení účinnosti bifaciálních solárních článků založených na monokrystalickém křemíku n-typové vodivosti. Tato práce přináší nové poznatky o vylepšených výrobních procesech a postupech použitých během výroby článků v ISC Konstanz. V rámci práce byly vyrobeny solární články typu n-PERT (Passivated Emitter Rear Totally diffused) s vysokou účinností, a to pomocí standartních procesů a zařízení používaných běžně při průmyslové výrobě. Zapojení těchto průmyslových postupů a metod umožnilo ověřit možnosti výroby n-typových článků za použití téměř totožného vybavení, jaké je potřeba pro výrobu p-typových článků. Zvýšení účinnosti bylo založeno především na vylepšení jednotlivých procesních kroků. Experimenty popsané v této práci dosvědčují zlepšení procesu difúze bóru, přizpůsobení parametrů pasivační a antireflexní vrstvy nově navrženému emitoru, zlepšení procesu metalizace ve smyslu využití past neobsahujících hliník, testování tisku rozličných motivů spolu s různými sekvencemi výpalu. V rámci práce byla testována možnost zamezení jevu potenciální indukované degradace (Potential Induced Degradation – PID) pomocí vhodného složení ARC a pasivační vrstvy. Vyrobené n-typové solární články dosáhly maximální hodnoty účinnosti 20,9 %.
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Aslan, Mehmet Kadir. "Emitter Identification Techniques In Electronic Warfare." Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/12607675/index.pdf.
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In this study, emitter identification techniques have been investigated and a schema has been proposed to solve the emitter identification problem in Electronic Warfare systems.
Clustering technique, histogram based deinterleaving techniques and a continuous wavelet transform based deinterleaving technique have been reviewed. A receiver simulator software has been developed to test the performance of these techniques and to compare them against each other. To compensate the disadvantages of these techniques, a schema utilizing the beneficial points of them has been developed. With the modifications proposed a resultant schema has been obtained.
Proposed schema uses clustering and deinterleaving together with other proposed modifications. Tests made through out this study have shown that this usage improves performance of emitter identification system. Hence, proposed schema can be used to identify the emitters in real EW systems.
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Parker, Peter A., and Melina Lake. "Signal Emitter Localization Using Telemetry Assets." International Foundation for Telemetering, 2013. http://hdl.handle.net/10150/579671.
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ITC/USA 2013 Conference Proceedings / The Forty-Ninth Annual International Telemetering Conference and Technical Exhibition / October 21-24, 2013 / Bally's Hotel & Convention Center, Las Vegas, NVTelemetry ground stations spread over geographically diverse areas are well suited for use in passively locating the source of a distant transmitted signal. In a favorable positioning of receive sites, the accuracy of these passive localization techniques can compete with the accuracy of radars. In these cases, use of receive only assets is a less expensive alternative than the use of a radar's scarce resources. Until recently, the major technical challenge to implementation of the passive localization techniques of time-difference of arrival (TDOA) and frequency-difference of arrival (FDOA) has been the frequency and time stability of geographically separated receivers. Advances in GPS based timing and frequency references has made the implementation of TDOA and FDOA feasible. This paper shows how these limitations have been overcome using the current telemetry assets at the Reagan Test Site in Kwajalein Atoll.
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Wolstenholme, G. R. "A study of polysilicon emitter transistors." Thesis, University of Southampton, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.384186.
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Yang, Yujia S. M. Massachusetts Institute of Technology. "Development of optical field emitter arrays." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/84858.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2013.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 131-137).
Optical field emitters are electron emission sources actuated by incident light. Optically actuated field emitters may produce ultrafast pulses of electrons when excited by ultrafast optical pulses, thus making them of interest for specific applications such as ultrafast electron microscopy, diffraction and spectroscopy; and as electron sources for X-ray generation. Recently proposed intense, coherent, and compact X-ray sources require low emittance, high brightness and short duration electron bunches that form a periodic pattern in the transverse plane. This thesis theoretically developed optical field emitter arrays that are suitable for use as the electron source for this novel X-ray source. Studies of several optical field emitter array structures, including vertically-standing gold nanopillars and silicon tips, in-plane gold nanostructures, and metallic line gratings, were performed via theoretical analysis and numerical simulations. Enhancement of the optical nearfield and power absorption was achieved by geometrical and plasmonic effects, leading to enhanced charge yield from the optical field emitter arrays.
by Yujia Yang.
S.M.
16
Kolář, Jakub. "Analýza vlivu tepelných jevů na termofotovoltaický systém." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2014. http://www.nusl.cz/ntk/nusl-220993.
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This semestral thesis focuses on the description of specific renewable resources in the form of thermophotovoltaic cells using selective radiators with micro/nano structures. This work deals with an introduction of renewable resources and specifically focuses on thermophotovoltaic. Thesis describes basic principles, but also influences affecting the proper functioning of these systems. It also focuses on selective radiators, which are created by mikro/nano structures, and factors that can affect their implementation or simulation. Part of the work are also examples of calculations of basic parameters of the structures, which will be used in the simulations. Next chapters are dealing with simulations which are analyzing thermal effects on termophotovoltaic system. Except the analysis itself there is also partial optimalization solving some of the negative thermal effects.
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Li, Liurui. "Multiplexed Electrospray Emitters for Highly Conductive and Corrosive Fluids." Thesis, Virginia Tech, 2017. http://hdl.handle.net/10919/78199.
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This thesis reports the design, fabrication, and operation of silicone based multiplexed electrospray (MES) emitters. After reviewing the feasibility of utilizing electrospray as a scalable thin film deposition technique as well as the advantages and limitations of prior MES emitters, we present a design rationale for MES suitable for highly conductive and corrosive fluids. Then we customized a 1064nm fiber laser micromachining system to precisely and rapidly machine silicone sheet and silicon wafers. Laser energy and path are judicially chosen to create clean and round micro posts that form the external structure of the nozzles. For MES with low flow rate per nozzle, it is of vital importance to evenly distribute the liquid into each nozzle on the entire MES array by controlling the pressure drop inside each fluid flow channel. To this end, we modeled the dimension of microfluidic channels that introduce flow impedance overwhelming surface tension at the nozzle tip. We presented laser microfabrication techniques for fabricating two typical types of microfluidic channels: the through-hole array on conductive silicone sheets and the in-plane microfluidic channel on silicon wafers. Next, we developed a convenient assemble process for the integration of three layers (distributor layer, extractor layer, and collector layer) of the MES emitter. The uniformity of the flow rate among nozzles on MES emitters was investigated by observing the overall spray profiles and measuring the diameter of each jet. The results suggest that the silicone-based MES emitters are feasible for spraying highly conductive and corrosive liquids. The MES emitter developed in this thesis may become a promising tool in the scalable manufacturing of thin film perovskite solar cells.Master of Science
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Lee, Kon Jiun. "Current limiting of field emitter array cathodes." Diss., Georgia Institute of Technology, 1986. http://hdl.handle.net/1853/19629.
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Schädler, Kevin Gerd. "Single quantum emitter manipulation with 2D materials." Doctoral thesis, Universitat Politècnica de Catalunya, 2018. http://hdl.handle.net/10803/586168.
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Photonics aims to manipulate light by controlling its interactions with matter to enable novel optical technologies for communication, information processing and sensing. Current efforts strive to enter the regime of quantum nanophotonics, where light interacts with nanoscale photonic elements at the single photon level. The realisation of such systems is challenging due to weak light-matter interaction at the nanoscale, which motivates the quest for new strategies and nanomaterials with enhanced interaction.
In this context, nanoscale solid state quantum light emitters which mimic the efficient interactions of trapped atoms with light are a key element for implementing quantum optical devices on chip.
The coupling of these quantum emitters to their nanoscale environment has two important consequences: i) controlling the environment enables control of the emitter, while conversely ii) the emitter acts as a nanoprobe of its environment. Therefore, hybrid systems which integrate such emitters with a controllable nano-environment enable manipulation of nanoscale quantum light.
Two-dimensional (2D) materials are a particularly promising platform for this purpose due to their unique blend of optoelectronic and mechanical properties which enable efficient, tuneable light-matter interactions and sensitive nanomechanical resonators with ultra-low mass and high mechanical resonance frequency.
In this thesis, I will introduce two different hybrid systems which integrate nanoscale quantum emitters with two-dimensional (2D) materials such as atomically thin graphene and MoS2.
I will first present a hybrid nano-optomechanical system which harnesses efficient near-field interactions to couple the nano-motion of a 2D mechanical graphene resonator to the emission strength of a quantum emitter (nitrogen vacancy centre, NVC) at a separation below 40 nm.
In this system, electromechanical control of graphene's nano-motion enables high-frequency (100 MHz) emission modulation, while conversely, the NVC acts as a transducer which enables optical readout of nano-motion in the photon counting regime.
In the second part of the thesis, I demonstrate that single molecules embedded in organic nanocrystals in a polymer display bright single photon emission with ultra-narrow linewidth close to the lifetime-limited value (~ 40 MHz). I show that these emitters can be integrated with 2D materials at sub-wavelength separation in a hybrid optoelectronic device without emission perturbation. Using the 2D materials as transparent electrodes, the device's nanoscale dimensions enable ultra-broadband tuning (tuning range > 400 GHz) and fast modulation (frequency ~ 100 MHz) of the emission energy, which renders it an integrated, ultra-compact tuneable single photon source.
These results demonstrate the potential of 2D materials for controlling quantum emitters and the use of an atomically small object to probe optoelectronic and mechanical properties of atomically thin materials.La fotónica tiene como objetivo la manipulación de la luz y el control de la misma cuando interactúa con la materia con el fin de desarrollar nuevas tecnologías ópticas con aplicaciones en diferentes campos, como son el de la comunicación, procesado de información y detección. En la actualidad, es de gran interés poder desarrollar este tipo de tecnología pero en el ámbito de la nanofotónica cuántica, donde la luz interactúa con elementos fotónicos de dimensión nanométrica mediante fotones únicos. La realización de este tipo de sistemas representa un importante desafío debido a la débil interacción que existe entre la luz y la materia a escala nanométrica, por lo que resulta imprescindible la búsqueda de nuevas estrategias y materiales en estas dimensiones que aumenten dicha interacción. En este contexto, los emisores de luz cuántica de estado sólido a escala nanométrica, que imitan las interacciones eficientes de los átomos atrapados con la luz, son un elemento clave para la implementación de dispositivos ópticos cuánticos en el chip. La implementación de estos emisores cuánticos en el entorno de la nanoescala conlleva dos efectos de gran importancia: i) el control del entorno permite controlar el emisor, mientras que al mismo tiempo ii) el emisor actúa como una sonda nanométrica del entorno. De este modo, los sistemas híbridos que integren dichos emisores en un entorno nano-controlable van a permitir la manipulación de la luz cuántica en la nanoescala. Los materiales bidimensionales (2D) son una plataforma particularmente prometedora para este propósito debido al conjunto de propiedades únicas que presentan, especialmente optoelectrónicas y mecánicas, que permiten interacciones eficientes de luz regulable y resonadores nanomecánicos sensibles con masa ultrabaja y alta frecuencia de resonancia mecánica. En esta tesis, se van a presentar dos sistemas híbridos diferentes que integran los emisores cuánticos a escala nanométrica, que incluyen materiales bidimensionales (2D) como son el grafeno y MoS2. En primer lugar, se demostrará la realización de un sistema nano-optomecánico híbrido que aprovecha las interacciones eficientes de campo cercano para acoplar el nano-movimiento de un resonador mecánico bidimensional de grafeno a la fuerza de emisión de un emisor cuántico (centro de vacío de nitrógeno, NVC) con una separación inferior a 40 nanómetros. En este sistema, el control electromecánico del nano-movimiento de grafeno permite la modulación de emisión de alta frecuencia (100 MHz), mientras que, a la inversa, el NVC actúa como un transductor que permite la lectura óptica de nano-movimiento en el régimen de conteo de fotones. En la segunda parte de la tesis, se demostrará que las moléculas individuales que han sido incrustadas en nanocristales orgánicos, y que a su vez se incluyen en un polímero, son una fuente brillante de fotones individuales con un ancho de línea muy estrecho y próximo a su tiempo de vida límite (40 MHz). También, se muestra que los emisores se pueden integrar en dispositivos optoelectrónicos híbridos utilizando materiales 2D con una separación inferior a una longitud de onda sin causar perturbación en la emisión. El uso de materiales 2D como electrodos transparentes en dispositivos de tamaño nanométrico permite la sintonización de banda ultra ancha (rango de sintonía > 400 GHz) y la modulación rápida (frecuencia ~ 100 MHz) de la energía de emisión. Por ello, estos dispositivos actúan como una fuente integrada de fotones únicos que es sintonizable y ultra-compacta. Estos resultados demuestran el potencial de los materiales 2D para controlar los emisores cuánticos y el uso de un objeto atómico para comprobar las propiedades optoelectrónicas y mecánicas que poseen los materiales atómicamente delgados.
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Chik, Hope Wuming. "Emitter-up heterojunction bipolar transistor-compatible laser." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0014/MQ34129.pdf.
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Manning, James David. "Directional diffuse reflection from a polygon emitter." Thesis, University of Hull, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.445284.
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Browne, David C. "Theoretical aspects of polysilicon emitter bipolar transistors." Thesis, University of Southampton, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.328280.
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Mauersberg, Diane. "Rapid thermal processing of polysilicon emitter transistors /." Online version of thesis, 1994. http://hdl.handle.net/1850/11706.
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Adams, Andrew S. M. (Andrew C. )Massachusetts Institute of Technology. "An investigation of nafion electrospray emitter tips." Thesis, Massachusetts Institute of Technology, 2020. https://hdl.handle.net/1721.1/130179.
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Thesis: S.M., Massachusetts Institute of Technology, Department of Aeronautics and Astronautics, May, 2020Cataloged from student-submitted PDF of thesis.
Includes bibliographical references (pages 121-125).
Electrospray propulsion development is limited in large part by the materials with which emitters are manufactured. Emitters must transport ionic liquid to their apex and hold a shape which allows menisci to form and emit pure ions. The motivation for this work was to investigate Nafion, a perfluorinated sulfonic acid ionomer, as an alternative to the porous materials currently used for electrospray emitters. A common, repeatable method of manufacturing Nafion single emitter tips and arrays with different mixture ratios of Nafion and EMI BF₄ is developed and refined. This method utilizes 3D printed negatives with tungsten ILIS emitters to produce a master shape for reusable PDMS molds. Thirteen tips were made using the presented method. Defects are categorized and recorded. Three of the tips were also successfully attached to porous carbon substrates, all of which were mixtures. Molds for arrays were also tested, and an array of pure Nafion was made.
The Nafion emitter tips' hydraulic impedance is estimated from geometric parameters and separately calculated from emission characteristics. As part of the calculation, an estimation of (q/m)[subscript avg] is obtained using a previously obtained TOF curve. All tips exceeded the [mathematical expression] impedance threshold to emit pure ions. A tungsten ILIS emitter used as a master for tip shape is tested as a control. Four of thirteen tips were chosen for testing and all successfully emitted ions for a short period. Two emitted for >1 hr and displayed a decreasing emitted current over time, and the emitted current spanned over one order of magnitude (20 to 1000 nA). It is shown that this is likely due to the depletion of an externally wetted meniscus, and the mass flow thereafter was limited by the high hydraulic impedance of the Nafion bulk. The calculated impedance during steady-state emission was significantly lower than estimated for internal tranport alone.
Future study should improve understanding of Nafion-EMI BF₄ mixtures and their diffusivity given a pressure difference and a concentration of ionic liquid. In addition, to supplement previous work, an emission tests and an RPA curve are reported for a fifth Nafion tip.
by Andrew Adams.
S.M.
S.M. Massachusetts Institute of Technology, Department of Aeronautics and Astronautics
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Lourenço, Nuno Rafael Mendonça. "Communication systems using visible light : emitter/receiver." Master's thesis, Universidade de Aveiro, 2009. http://hdl.handle.net/10773/2097.
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Mestrado em Engenharia Electrónica e TelecomunicaçõesA presente dissertação aborda o design de um transdutor optoelectrónico para um sistema de comunicações sem fios que utiliza a luz visível como meio de transmissão. Estes sistemas tiram partido dos conhecimentos tecnológicos existentes sobre sistemas de comunicações sem fios utilizando o espectro dos infravermelhos, e da recente introdução em massa de díodos emissores de luz de elevado brilho em diversas aplicações de iluminação. O trabalho apresentado foi desenvolvido dentro do projecto VIDAS, tendo em conta os respectivos cenários de aplicação propostos. Este projecto visa aumentar a segurança rodoviária através da introdução de sistemas de comunicação com luz visível, para estabelecer ligações veículo-a-veículo e/ou veículo-a-semáforo. Através destas ligações, poderão ser antecipadamente fornecidos diversos avisos de segurança aos condutores. O estudo do transdutor proposto, começa com uma introdução ao conceito e evolução dos sistemas de comunicação com luz visível. Segue-se uma apresentação do canal de transmissão, na qual são definidos os modelos de emissor, receptor e propagação. São também discutidas as diversas fontes de ruído óptico e suas influências na aplicação pretendida. A restante análise é dividida em dois dispositivos principais, o emissor e o receptor ópticos. Sobre o emissor, são apresentados os principais blocos funcionais, seguidos de uma exposição das características de diversos díodos emissores de luz e da análise de diferentes topologias de receptor. Para a topologia mais viável de ser implementada, são apresentados diversos resultados de simulação do circuito electrónico. Do lado do receptor, de forma análoga, são apresentados os diferentes blocos funcionais e as características de diversos fotodíodos. No entanto a experiência do grupo de trabalho levou à escolha de uma topologia de receptor mais específica. Desta, fazem parte diversos módulos, cuja análise e resultados de simulação dos respectivos circuitos electrónicos são apresentados. De forma a avaliar a performance dos dispositivos propostos, foram efectuados diversos ensaios e respectivas medições. Estes resultados permitiram obter informações sobre o comportamento da componente óptica do sistema. Deste conjunto de informações, diferentes considerações sobre a performance de módulos individuais e do transdutor são apresentadas. Estas permitem concluir sobre a viabilidade do transdutor optoelectrónico num cenário de aplicação real. ABSTRACT: This dissertation addresses the design of an optoelectronic transceiver for a wireless communication system, using visible light as the transmission medium. These systems take advantage from the available technological expertise on wireless communication systems using the infrared spectrum, along with the recent massive introduction of high brightness light emitting diodes in several lighting applications. The present work was developed within the scope of project VIDAS, regarding the proposed application scenarios. This project aims at increasing road traffic safety by introducing visible light communication systems to establish vehicle-to-vehicle and vehicle-to-traffic light communications. Through these connections, early safety warnings can be provided to drivers. The study of the proposed transceiver begins with an introduction to the concept and evolution of visible light communication systems. This is followed by the presentation of the transmission channel, in which the emitter, receiver and transmission models are defined. Also, the sources and influences of the various optical noise sources are discussed. The remaining analysis is divided between the two major devices, the optical emitter and receiver. From the emitter, the main building blocks are presented, followed by an exposition of several light emitting diodes characteristics and the analysis of diverse receiver topologies. In the case of the most viable topology for implementation, several simulation results of the respective electronic circuit are presented. On the receiver, the main building blocks and the characteristics of several photodiodes are presented in a similar fashion. However, the workgroup experience led to the choice of a specific receiver topology. This is made up of several modules, whose analysis and simulation results for the electronic circuits are presented. In order to evaluate the performance of the proposed devices, several tests and measurements were made. These results also provided information on the system’s optical component behavior. From this assortment of information, different considerations on the performance of the individual modules, as well as the transceiver are presented. They allow for a conclusion on the viability of the optoelectronic transceiver in a real application scenari
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Revillon, Guillaume. "Uncertainty in radar emitter classification and clustering." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS098/document.
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En Guerre Electronique, l’identification des signaux radar est un atout majeur de la prise de décisions tactiques liées au théâtre d’opérations militaires. En fournissant des informations sur la présence de menaces, la classification et le partitionnement des signaux radar ont alors un rôle crucial assurant un choix adapté des contre-mesures dédiées à ces menaces et permettant la détection de signaux radar inconnus pour la mise à jour des bases de données. Les systèmes de Mesures de Soutien Electronique enregistrent la plupart du temps des mélanges de signaux radar provenant de différents émetteurs présents dans l’environnement électromagnétique. Le signal radar, décrit par un motif de modulations impulsionnelles, est alors souvent partiellement observé du fait de mesures manquantes et aberrantes. Le processus d’identification se fonde sur l’analyse statistique des paramètres mesurables du signal radar qui le caractérisent tant quantitativement que qualitativement. De nombreuses approches mêlant des techniques de fusion de données et d’apprentissage statistique ont été développées. Cependant, ces algorithmes ne peuvent pas gérer les données manquantes et des méthodes de substitution de données sont requises afin d’utiliser ces derniers. L’objectif principal de cette thèse est alors de définir un modèle de classification et partitionnement intégrant la gestion des valeurs aberrantes et manquantes présentes dans tout type de données. Une approche fondée sur les modèles de mélange de lois de probabilités est proposée dans cette thèse. Les modèles de mélange fournissent un formalisme mathématique flexible favorisant l’introduction de variables latentes permettant la gestion des données aberrantes et la modélisation des données manquantes dans les problèmes de classification et de partionnement. L’apprentissage du modèle ainsi que la classification et le partitionnement sont réalisés dans un cadre d’inférence bayésienne où une méthode d’approximation variationnelle est introduite afin d’estimer la loi jointe a posteriori des variables latentes et des paramètres. Des expériences sur diverses données montrent que la méthode proposée fournit de meilleurs résultats que les algorithmes standardsIn Electronic Warfare, radar signals identification is a supreme asset for decision making in military tactical situations. By providing information about the presence of threats, classification and clustering of radar signals have a significant role ensuring that countermeasures against enemies are well-chosen and enabling detection of unknown radar signals to update databases. Most of the time, Electronic Support Measures systems receive mixtures of signals from different radar emitters in the electromagnetic environment. Hence a radar signal, described by a pulse-to-pulse modulation pattern, is often partially observed due to missing measurements and measurement errors. The identification process relies on statistical analysis of basic measurable parameters of a radar signal which constitute both quantitative and qualitative data. Many general and practical approaches based on data fusion and machine learning have been developed and traditionally proceed to feature extraction, dimensionality reduction and classification or clustering. However, these algorithms cannot handle missing data and imputation methods are required to generate data to use them. Hence, the main objective of this work is to define a classification/clustering framework that handles both outliers and missing values for any types of data. Here, an approach based on mixture models is developed since mixture models provide a mathematically based, flexible and meaningful framework for the wide variety of classification and clustering requirements. The proposed approach focuses on the introduction of latent variables that give us the possibility to handle sensitivity of the model to outliers and to allow a less restrictive modelling of missing data. A Bayesian treatment is adopted for model learning, supervised classification and clustering and inference is processed through a variational Bayesian approximation since the joint posterior distribution of latent variables and parameters is untractable. Some numerical experiments on synthetic and real data show that the proposed method provides more accurate results than standard algorithms
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Jacobs, Kristof. "Development of resonant tunnelling diode terahertz emitter." Thesis, University of Sheffield, 2015. http://etheses.whiterose.ac.uk/9304/.
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This thesis reports on the development of high current density InGaAs/AlAs/InP resonant tunnelling diodes (RTDs) grown by metal-organic vapour phase epitaxy (MOVPE) for terahertz (THz) applications. A wide variety of characterisation techniques are employed to investigate the material properties and quality on the wafer level allowing future device and growth optimisation. An optical characterisation technique based on photoluminescence (PL) spectroscopy is developed to non-destructively map the doping and structural composition of the RTD on the wafer level. A new non-destructive optical characterisation technique to resolve the absolute energy level position of the first electron state of RTDs through low temperature PL spectroscopy is also reported. The absolute energy levels are resolved by a combination of type-I and type-II quantum well (QW) recombination, allowing an investigation into important scattering mechanisms affecting device performance, and monitor the QW alloy content and thickness non-destructively. Details of the growth process and the characterisation techniques are discussed. A new fabrication technique based on conventional i-line photolithography for micron scale high current density RTD devices is also developed with accurate control over the final device area (and hence characteristics). This is achieved by measuring the V-I characteristic of the RTD during the fabrication process, which has not been previously possible. This was made possible by guiding the emitter current through the full RTD structure by a large second contact electrode on the collector side and using an air-bridge contact to the collector. Important information about the RTD performance is extracted by using this method. Temperature dependent V-I characterisation is also carried out to investigate the valley current of the RTD. Details of the design, fabrication, and characterisation of a room temperature operating THz emitter in the 300 GHz band are reported.
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Werra, Julia Franziska Maria. "Probing plasmonic nanostructures." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät, 2016. http://dx.doi.org/10.18452/17658.
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Elektrische und magnetische Emitter können zur Erforschung unterschiedlicher plasmonischer Nanostrukturen genutzt werden. Indem wir die Änderung der Abstrahldynamik und in der Lebensdauer bestimmen, detektieren wir die photonische lokale Zustandsdichte. Diese Zustandsdichte, die eine Eigenschaft der Umgebung ist, ermöglicht uns nicht nur Rückschlüsse auf die elektronischen und andere physikalische Eigenschaften dieser zu treffen sondern auch die allgemeinen Eigenschaften der plasmonischen Nanostruktur im Bezug auf Licht-Materie Kopplung zu bestimmen. Eine starke Licht-Materie-Kopplung ist für die zukünftige Anwendung im Bereich der Quantentechnologien wichtig. Wenn Emitter hierbei mit plasmonischen Nanostrukturen koppeln, fokussieren letztere nicht nur das emittierte Lichts an der Oberfläche im Subwellenlängenbereich sondern ermöglichen durch die Feldüberhöhung an der Oberfläche auch eine starke Licht-Materie-Kopplung. In der Arbeit konzentrieren wir uns auf zwei grundlegend unterschiedliche plasmonische Systeme: zunächst untersuchen wir analytisch den Einfluss von Graphen auf elektrische und magnetische Emitter und diskutieren dann die Lebensdaueränderungen und Strahlungsdynamiken in der Nähe von Silber- und Goldnanostrukturen. Im ersten Teil der Arbeit analysieren wir den Einfluss von Graphen mit einer Bandlücke auf den Emitter und zeigen Möglichkeiten zur experimentellen Bestimmung der Bandlücke auf. Im zweiten Teil modellieren wir die Propagation elektromagnetischer Felder im dreidimensionalen Raum mit Hilfe der Diskontinuierlichen Galerkin Zeitraum Methode mit erweiterten Funktionalitäten. Diese verwenden wir sowohl zur theoretischen Modellierung des ersten dreidimensionalen Fluoreszenlebensdauerabbildungsmikroskopie mit einem einzelnen Quantenemitter als auch zur selbstkonsistent Beschreibung von Emittern in der Nähe eines Goldpentamers. Die Kombination der Studien betont die Stärke von Emittern elektrische, optische und magnetische Eigenschaften zu detektieren.Electric and magnetic emitters can be used to probe different plasmonic nanostructures. By determining the modification of the radiation dynamics and the lifetimes, we can measure the photonic local density of states. This, being a property of the enviroment, does not only allow us to draw conclusions regarding the electronic and other physical properties of the latter but also regarding the general light-matter coupling properties of the plasmonic nanostructure. A strong light-matter coupling is important for future applications in quantum technology. If emitters couple specifically to plasmonic nanostructure, the latter do not only focus the emitted light at the sub-wavelength scale at the surface of the structure but also allow for such a strong light-matter coupling due to the field enhancement at the surface. In this work, we focus on two different basic plasmonic systems: first, we study analytically the influence of graphene on electric and magnetic emitters, and second we discuss lifetime modifications and radiation dynamics close to silver and gold nanostructures. In the first part of this work, we specifically focus on the influence of graphene exhibiting a finite band gap on the emitter. In the second part, we model the propagation of electromagnetic fields in three-dimensional space making use of the discontinuous Galerkin time-domain method with extended functionalities. This framework we apply to model the first three-dimensional scanning-probe fluorescence-lifetime imaging microscopy by use of a single quantum-emitter as well as for a self-consistent description of emitters in the proximity of a gold pentamer. The combination of these studies stress that the strength of emitters lies in the detection of electronic, optical and magnetic properties.
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Mouni, Emile Bowendnéré. "Contribution à l'amélioration des performances des génératrices synchrones : nouvelle structure d'excitation basée sur une machine à aimants et combinée à des lois de commande avancées." Poitiers, 2008. http://theses.edel.univ-poitiers.fr/theses/2008/Mouni-Emile-Bowendnere/2008-Mouni-Emile-Bowendnere-These.pdf.
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Dans cette thèse une contribution a été faite sur l’étude et l’amélioration des performances de la génératrice synchrone (GS). C’est ainsi qu’une nouvelle structure d’excitation de la GS, basée sur l’utilisation d’une machine à aimants permanents combinée avec un pont redresseur à thyristors, a été proposée en vue d’alimenter directement l’inducteur de celle-ci. Afin de tirer un grand avantage de cette structure d’excitation dont la dynamique est par nature plus rapide que celle des structures classiques, deux lois de commande ont été mise en place : la commande prédictive et la commande H∞ et elles ont fourni des résultats assez similaires et très satisfaisants en simulation. Pour la validation expérimentale, une implantation en temps réel via une interface Dspace, nous a permis de conclure quant à la validité de notre approche. Une comparaison avec une structure d’excitation industrielle a été faite afin d’évaluer aussi bien quantitativement que qualitativement l’apport effectif de ce travail. Ainsi en termes de chutes/dépassement de tension, de temps de réponse et de taux de distorsion des signaux de sortie, la nouvelle approche combinée à une loi de commande moderne apporte une meilleure réponse par rapport aux structures classiquesThe works presented in this dissertation are focussed on the study and the performances improvement of the synchronous generator. Then, a new excitation structure is proposed to directly feed the SG’s main armature. This exciter is based on a permanent magnet generator and thyristors bridge. In order to take real advantage of the new excitation structure, two modern and efficient control laws have been used: the predictive control and H∞ control. Both provide similar and very satisfactory results in simulation. Thanks to the real time implementation using the Dspace 1104, the effectiveness and the high performances of the new excitation approach have been proved. At the same time, an already used industrial excitation structure has been involved in the comparative study in order to quantify and qualify the real advantage of the new approach. Then, as regards voltage overshoots and drops, the time response and the output signal total harmonic distortion, the new excitation approach combined with modern control law gives better satisfaction than classical one
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Celebi, M. bahadir. "Radar Emitter Emulation For Research And Experimental Purposes." Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/3/12610847/index.pdf.
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The scope of this thesis is to implement radar emitter emulator in a low cost, portablehardware for operational and educational purposes. The model enables pulse train generation in real environment belonging to radar emitters for military exercises. The motivation comes from another research area which is to design effective algorithms for
deinterleaving mixed pulse sequences in a suitable hardware and this thesis, covers the work done for implementing a hardware that generates mixed pulse sequences. First of
all, a basic radar emitter model is built up using laboratory instruments by considering basic radar emitter models. Technical specs of these instruments have to be known well
to find out how many emitters can be emulated simultaneously and what the limits of these emulations are. After giving emulation results, trigging signal generator externally to obtain complex mixed pulse sequences is mentioned. In the following section related schematics are given about implementing radar emitters. Cost efficient way of emitter emulation is mentioned by using wideband RF synthesizer/VCO with integrated RF mixers and some microwave components in the following section. A board is designed including all required components to implement radar emitter emulation. Tests are implemented in laboratory environment. Finally test results and technical specifications
of the design are given. Also cost calculations of the implemented designs are done in the final section and some examples related to the use of emulators in environmental
scenarios are given. Future work is also explained again in this final section.
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Papadopoulos, George 1961 Carleton University Dissertation Engineering Electrical. "Development and characterization of polysilicon emitter solar cells." Ottawa.:, 1989.
Find full text
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Pflug, David George. "Low voltage field emitter arrays through aperture scaling." Thesis, Massachusetts Institute of Technology, 2000. http://hdl.handle.net/1721.1/8804.
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Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2000.Includes bibliographical references (p. 215-223).
by David George Pflug.
Ph.D.
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Sykora, Benedikt Reinhold. "Influence of emitter orientation in perylene based OLEDs." Master's thesis, Universidade de Aveiro, 2013. http://hdl.handle.net/10773/11828.
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Mestrado em Ciência e Engenharia de MateriaisOs díodos orgânicos emissores de luz (organic light-emitting diodes ou OLEDs) têm como elemento funcional um filme fino de um semicondutor orgânico para a criação de excitões (pares electrão-lacuna), que emitem luz quando relaxam. O objetivo desta dissertação de mestrado é investigar o efeito da orientação dipolar de filmes baseados em perilenos de tetraphenyldibenzoperiflanthene (DBP) e diindenoperylene ( DIP), e das mesmas moléculas dispersas numa ma matriz de 5,6,11,12- tetraphenylnaphthacene (rubreno). O estudo tenta identificar uma possível relação entre o comportamento destes filmes e a eficiência do respetivo OLED. Observa-se que os filmes de DBP são amorfos, apresentam uma superfície lisa e absorvem mais luz do que os filmes de DIP, que se caracterizam por uma estrutura cristalina e uma superfície irregular. Os resultados combinados de simulações e de medições de fotoluminescência com dependência angular revelam que as moléculas de DBP apresentam orientação horizontal, estando as moléculas de DIP orientadas verticalmente. Este facto pode explicar o acoplamento mais forte das moléculas de DIP aos plasmões de superfície, em comparação com o DBP. As características gerais dos filmes de DBP ou DIP mantêm-se mesmo quando estes são depositados nos substratos de N, N '-di(1-naftil-N,N-difenil-(1,1'- bifenil)-4,4' –diamina utilizados ma preparação dos OLEDs, o que permite a comparação direta entre as duas configurações. Os resultados obtidos com os OLEDs baseados em filmes puros de DBP ou DIP apresentam valores de eficiência quântica externa (EQE) da ordem de 0,2 e 0,04 %, respetivamente. Estes valores baixos podem explicar-se pela orientação vertical dos dipolos do DIP, conduzindo a um fator de emissão de 27% (light outcoupling), claramente superior ao obtido com o OLED baseado no DBP (16%). Estas diferenças acentuam-se quando na comparação destes filmes com o comportamento dos filmes rubreno equivalentes dopados com 1% de DBP e DIP. Se por um lado não se observa nenhuma orientação dipolar preferencial no caso do DIP, as moléculas de DBP na matriz de rubreno estão quase na sua totalidade orientadas horizontalmente, o que aumenta o factor de emissão. A forte orientação preferencial no caso do DBP pode igualmente justificar o aumento de EQE de 0,2 % e 0,04% nos OLEDs com os filmes puros de DBP e DIP, para 3% e 0,5% no caso dos OLEDs com os filmes dopados. O aumento da eficiência pode também dever-se ao aumento da transferência energética da matriz de rubreno para os centros emissores. O forte efeito da orientação horizontal do emissor na eficiência dos OLEDs manifesta-se igualmente no notável aumento do factor de emissão de luz observado entre os filmes de DBP (fortemente orientados) e DIP (pouco orientados), que é de cerca de 70% no caso das camadas de emissão baseadas nos filmes puros, e de 44 % no caso dos filmes dopados.
Organic light-emitting diodes (OLEDs) contain thin films of organic semiconductors to create excitons (electron-hole-pairs), which will emit light if they de-excite. The aim of this master thesis is to investigate a possible link between the dipole orientation of perylene based films of tetraphenyldibenzoperiflanthene (DBP) and diindenoperylene (DIP), and of the same molecules dispersed in a 5,6,11,12-tetraphenylnaphthacene matrix. The study also compares the behavior of these films with that of the corresponding OLEDs. It is shown that DBP neat films are essentially amorphous, with a rather smooth surface and they absorb more light than the DIP films, which are crystalline and have a rough surface. Simulation results and angle-dependent p-polarised photoluminescence measurements reveal that the DBP molecules have a horizontal orientation, while the DIP molecules are vertically oriented. This explains the stronger coupling of DIP molecules to the surface plasmons, when compared to the DBP molecules. The general characteristics of the DBP or DIP films do not change when these are deposited onto N,N’-di(1-naphtyl-N,N’-diphenyl-(1,1’-biphenyl)-4,4’diamine hole transport layers used as substrates in OLEDs, thus allowing a direct comparison between both configurations. The OLEDs comprising neat films of DBP or DIP have small external quantum efficiency (EQE) values of 0.2 and 0.04%, respectively. This is probably due to the strong vertical molecular orientation of the DBP, leading to a high lightoutcoupling factor of 27%, when compared to 16% of the DIP OLED. These differences are accentuated when comparing the behavior of the neat films with equivalent rubrene films doped with 1% of DBP or DIP. While the DIP exhibits a rather isotropic orientation, the DBP molecules are fully horizontal within the doped film, thus improving the light-outcoupling. This may partly justify the increase of EQE from 0.2% and 0.04% of the neat film OLEDs to 3% and 0.5% for the doped DBP and DIP OLEDs, respectively. The improvement of the efficiency may also be due to the enhancement of the energy transfer from the rubrene matrix to the emitter dyes. The horizontal orientation of the emitter has a huge effect on the efficiency of perylene-based OLEDs, apparent also on the remarkable increase of the lightoutcoupling of strongly oriented DBP dipoles in comparison to the weakly oriented DIP, which is of the order of 70% in the case of the neat emission layers, and of 44% in the case of the doped counterparts.
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Liu, Yin. "Design and Fabrication of the Emitter Controlled Thyristor." Thesis, Virginia Tech, 2001. http://hdl.handle.net/10919/33671.
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The Emitter Controlled Thyristor (ECT) is a new MOS-Gated Thyristor (MGT) that combines the ease of a MOS gate control with the superior current carrying capability of a thyristor structure for high-power applications. An ECT is composed of an emitter switch in series with the thyristor, an emitter-short switch in parallel with the emitter junction of the thyristor, a turn-on FET and the main thyristor structure. Numerical analysis shows that the ECT also offers superior high voltage current saturation capability even for high breakdown voltage ratings. Two different ECT structures are investigated in this research from numerical simulations to experimental fabrications.
A novel ECT structure that utilizes IGBT compatible fabrication process was proposed. The emitter short FET, emitter switch FET and turn-on FET are all integrated with a high voltage thyristor. Numerical simulation results show that the ECT has a better conductivity modulation than that of the IGBT and at the same time exhibits superior high voltage current saturation capability, superior FBSOA and RBSOA. The technology trade-off between turn-off energy loss and forward voltage drop of the ECT is also better than that of the IGBT because of the stronger conductivity modulation. A novel self-aligned process is developed to fabricate the device. Experimental characteristics of the fabricated ECT devices show that the ECT achieves lower forward voltage drop and superior high voltage current saturation capability.
A Hybrid ECT (HECT) structure was also developed in this research work. The HECT uses an external FET to realize the emitter switching function, hence a complicated fabrication issue was separated into two simple one. The cost of the fabrication decreases and the yield increases due to the hybrid integration. Numerical simulations demonstrate the superior on-state voltage drop and high voltage current saturation capability. A novel seven-mask process was developed to fabricate the HECT. Experimental results show that the HECT could achieve the lower forward voltage drop and superior current saturation capability. The resistive switching test was carried out to demonstrate the switching characteristics of the HECT.Master of Science
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Godbole, Soumitra Kumar. "Stability of Field Emitter Arrays to Oxygen Exposures." Thesis, University of North Texas, 2002. https://digital.library.unt.edu/ark:/67531/metadc3346/.
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The purpose of these experiments was to determine the degradation mechanisms of molybdenum based field emitter arrays to oxygen exposures and to improve the overall reliability. In addition, we also evaluated the emission current stability of gold-coated field emitter arrays to oxygen exposures. oxygen at 1x10-6 torr was introduced into the chamber through a leak valve for different lengths of time and duty cycles.
To ensure identical oxygen exposure and experimental measurement conditions, tips on half the area of the FEA were fully coated with gold and the other half were left uncoated. The emission current from the gold coated half was found to degrade much less than that from the uncoated half, in the presence of oxygen. Also in the absence of oxygen, the emission current recovery for the gold-coated side was much quicker than that for the uncoated side.
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Schucker, Thomas Douglas, and Thomas Douglas Schucker. "Emitter Source Geolocation from Imparted Rotor Blade Modulation." Thesis, The University of Arizona, 2016. http://hdl.handle.net/10150/623262.
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In RF communications with a rotorcraft such as a helicopter, the rotor blades can impart a modulation onto the received signal called Rotor Blade Modulation (RBM). This modulation is caused by the reflection of a signal off the rotating blades. The reflected signal is Doppler shifted based on where the signal is reflected along the length of the blade as well as the angle between the axis of rotation and the emitter. RBM is known to degrade the performance of RF communications on rotorcraft and can be used in radar applications to detect and classify aircraft, but there is little on its usefulness in other areas. This thesis looks at the ability to utilize the RBM phenomenon on the rotorcraft itself to geo-locate and track a signal emitter on the ground. To do this a 3D RF ray tracing program was developed in C++ to produce simulations of RBM signals. The developed program is based on optical ray tracing algorithms with modified physical propagation effects for RF signals, and swapping lights and cameras for RF transmitters and receivers respectively. The ray tracer was then run over a realistic set of physical parameters to determine their effects on the received signal; this includes transmitter azimuth and elevation angle, receiver position, blade pitch, etc. along with their combinations. The simulations of the azimuth and elevation angle produce predictable modulations on the received signal. Based on the trends in the signal's modulation, a DSP algorithm was distilled down that accurately determines the azimuth and elevation angle of the transmitter from simulated signal data.
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Patra, Soumyadip. "Distributed Emitter Detector Design under Imperfect Communication Channel." ScholarWorks@UNO, 2017. http://scholarworks.uno.edu/td/2391.
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We consider the distributed detection of an emitter using multiple sensors deployed at deterministic locations. The signal from the emitter follows a signal attenuation model dependent on the distance between the sensor and the emitter. The sensors transmit their decisions to the fusion center through a parallel access Binary Symmetric Channel (BSC) with a cross-over probability. We seek to optimize the detection performance under a prescribed false alarm at the sensor level and at the system level. We consider the triangular topology structure and using the least favorable emitter range study the impact of the BSC on the system level detection fusion rules. The MAJORITY fusion rule is found to be optimal under certain conditions.
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Culham, Stacey. "Polymetallic triplet emitters." Thesis, Northumbria University, 2013. http://nrl.northumbria.ac.uk/36124/.
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This work is concerned with the synthesis and property investigation of a relatively new class of cyclometallated Ir(III) and Pt(II) complexes in which two metal centres are coordinated to a common heterocycle resulting in a rigid polymetallic assembly. Highly luminescent materials which can emit and absorb in a red region of the spectrum were targeted. There are three main parts of the thesis. The first part investigates how luminescent properties of the diplatinum systems are affected by the bridging ligand. A series of novel mono- and dinuclear Pt(II) complexes has been prepared and their luminescent and redox properties investigated. The main observation is that the introduction of the second metal centre leads to a substantial red-shift in absorption and emission. In the second part the role of changing the ligand substituents in a cyclometallated complex has been investigated to determine the extent to which luminescence is affected by the nature of the substituents. A series of mono- and dinuclear Pt(II) complexes have been prepared using substituted pyrazine bridging ligands. It was found that electron donating substituents such as –OMe in the benzene cyclometallating ring cause a red-shift, while electron withdrawing substituents such as –F cause a blue-shift in emission. The final part of the work describes the synthesis of cyclometallated homometallic bis Ir(III) complexes. A series of bis- Ir(III) complexes have been prepared using a terdentate cyclometallating N^C^N coordinating 1,3-di(2-pyridyl)benzene derivative as an auxiliary ligand. It was found that the nature of the bridging ligand determines the overall stability of the complex. Pyrimidine-linked systems were found to be the most stable, while pyrazine analogues readily photodecompose/isomerise. Pyridazine-linked systems lead to ionic complexes where one chloride ligand is shared by two Iridium metal centres.
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Wootten, Michael. "Superluminescence diodes at 2.4 microns from GaInAsSb/AlGaAsSb quantum well heterostructures for optical glucose sensing." Thesis, University of Iowa, 2013. https://ir.uiowa.edu/etd/2427.
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High power, broadband light sources emitting in the 2-2.5 um wavelength range important for optical sensing of important biomolecules in aqueous solutions such as glucose. Here we demonstrate and analyze superluminescent diodes with output centered at 2.4 ums (range ~2.2-2.5 ums) from GaInAsSb/AlGaAsSb quantum wells in a separate confinement structure. Quasi-continuous wave output of 1 mW is achieved at room temperature for 40m x 2mm devices. Superluminescence is evidenced in superlinear growth, spectral narrowing, and angular narrowing of light output with increasing current injection. The output is analyzed and modeled with semiconductor rate equations, and by varying parameters, potential routes for future improvements are explored, such as additional Auger suppression and photonic mode engineering.
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Liu, Kendrick Xuong. "Photo-excitation of gated p-silicon field emitter arrays /." For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2005. http://uclibs.org/PID/11984.
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Tilston, Nina M. "Common emitter augmentation : a linearisation technique for RF amplifiers." Thesis, Heriot-Watt University, 2005. http://hdl.handle.net/10399/219.
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Bradley, Susan Margaret. "The numerical simulation of polysilicon-contacted emitter bipolar transistors." Thesis, Queen's University Belfast, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.317060.
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De, La Torre James David. "Modeling of cone deposition process for field emitter displays." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/40598.
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Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1996.Includes bibliographical references (leaf 58).
by James David De La Torre.
M.Eng.
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Dias, Stiven Schwanz. "Collaborative emitter tracking using distributed sequential Monte Carlo methods." Instituto Tecnológico de Aeronáutica, 2014. http://www.bd.bibl.ita.br/tde_busca/arquivo.php?codArquivo=3137.
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We introduce in this Thesis several particle filter (PF) solutions to the problem of collaborative emitter tracking. In the studied scenario, multiple agents with sensing, processing and communication capabilities passively collect received-signal-strength (RSS) measurements of the same signal originating from a non-cooperative emitter and collaborate to estimate its hidden state. Assuming unknown sensor noise variances, we derive an exact decentralized implementation of the optimal centralized PF solution for this problem in a fully connected network. Next, assuming local internode communication only, we derive two fully distributed consensus-based solutions to the problem using respectively average consensus iterations and a novel ordered minimum consensus approach which allow us to reproduce the exact centralized solution in a finite number of consensus iterations. In the sequel, to reduce the communication cost, we derive a suboptimal tracker which employs suitable parametric approximations to summarize messages that are broadcast over the network. Moreover, to further reduce communication and processing requirements, we introduce a non-iterative tracker based on random information dissemination which is suited for online applications. We derive the proposed random exchange diffusion PF (ReDif-PF) assuming both that observation model parameters are perfectly known and that the emitter is always present. We extend then the ReDif-PF tracker to operate in scenarios with unknown sensor noise variances and propose the Rao-Blackwellized (RB) ReDif-PF. Finally, we introduce the random exchange diffusion Bernoulli filter (RndEx-BF) which enables the network of collaborative RSS sensors to jointly detect and track the emitter within the surveillance space.
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Zhang, Bin. "Development of the Advanced Emitter Turn-Off (ETO) Thyristor." Diss., Virginia Tech, 2005. http://hdl.handle.net/10919/26095.
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Advancements in the power electronics systems have been directly related to the availability of improved power semiconductor devices. The device performance greatly determines the efficiency, reliability, volume, and cost of the power electronics system. This dissertation is dedicated to develop an advanced high power semiconductor device, the emitter turn-off (ETO) thyristor, which is targeted to improve the limitations of the present high power devices.
Major improvements in electrical and mechanical designs of the ETO for high power and high frequency operation are proposed which result in improved snubberless turn-off capability, low conduction loss, and low gate drive power consumption of the new generation ETO.
A revolutionary self-power generation method of the ETO is proposed. Different from the conventional high power devices which require the external power input for their gate drivers, ETO achieves complete optically controlled turn-on and turn-off and all the internal power required is self-generated. This advancement will have a major impact to high power converter designs.
A novel integrated method to eliminate the dead-time requirement is proposed for ETO. This method not only improves the output waveform quality but also increases the reliability and reduces the cost of the high power PWM voltage source converters. With this unique function, the upper and the lower ETO's within a converter phase leg can receive the ideal complementary (without dead-time) PWM signals and solve shoot-through problems.
Method to measure the ETO current and transfer the current information to a PWM signal is proposed. Based on the ETO's built-in current sensor, the over-current protection function of the ETO is designed as well. The experimental results show that the built-in current sensor has a very high precision, and the over-current protection function can effectively protect the ETO during the short circuit faults.
In order to improve ETO's turn-off capability, a comprehensive investigation of the turn-off failure mechanism of the ETO was performed. A series of simulations and experiments are carried out to study the ETO turn-off operation. The detail turn-off failure mechanisms are presented. The conditions to cause the ETO failure are addressed. The approaches to improve the ETO's turn-off capability are discussed.Ph. D.
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Cicek, Kenan. "Characterisation of orbital angular momentum beam emitter and receiver." Thesis, University of Bristol, 2016. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.702751.
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This thesis presents theoretical, simulation and experimental based studies on emission/detection of orbital angular momentum (OAM) beams for the newly emerging integrated OAM photonics technology. The number of applications that utilise the OAM technology has been increasing since the time it has been discovered. Optical communication is one of the high potential applications of OAM beams because of the possibility of providing infinite number of states. This has been considered as the perfect solution for the increasing data load. In order to process the OAM concept in such optical systems, a number of methods have been proposed. In addition to these methods, a new PICs OAM interpretation method has been discussed in this study. The obtained results show that this method has the potential especially for high-capacity optical data transmission. Moreover, the purity of beams (in terms of reflection within the ring resonator) generated by an integrated vortex beam emitter which was proposed by our group-has been investigated for the first time in this study. The investigation showed that there is a disrupting feed-back beam exist within the system. However, its effect on the generated beam's purity is considerably low.
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Ureten, Suzan. "Single and Multiple Emitter Localization in Cognitive Radio Networks." Thesis, Université d'Ottawa / University of Ottawa, 2017. http://hdl.handle.net/10393/35692.
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Cognitive radio (CR) is often described as a context-intelligent radio, capable of changing the transmit parameters dynamically based on the interaction with the environment it operates. The work in this thesis explores the problem of using received signal strength (RSS) measurements taken by a network of CR nodes to generate an interference map of a given geographical area and estimate the locations of multiple primary transmitters that operate simultaneously in the area. A probabilistic model of the problem is developed, and algorithms to address location estimation challenges are proposed. Three approaches are proposed to solve the localization problem. The first approach is based on estimating the locations from the generated interference map when no information about the propagation model or any of its parameters is present. The second approach is based on approximating the maximum likelihood (ML) estimate of the transmitter locations with the grid search method when the model is known and its parameters are available. The third approach also requires the knowledge of model parameters but it is actually based on generating samples from the joint posterior of the unknown location parameter with Markov chain Monte Carlo (MCMC) methods, as an alternative for the highly computationally complex grid search approach.
For RF cartography generation problem, we study global and local interpolation techniques, specifically the Delaunay triangulation based techniques as the use of existing triangulation provides a computationally attractive solution. We present a comparative performance evaluation of these interpolation techniques in terms of RF field strength estimation and emitter localization. Even though the estimates obtained from the generated interference maps are less accurate compared to the ML estimator, the rough estimates are utilized to initialize a more accurate algorithm such as the MCMC technique to reduce the complexity of the algorithm. The complexity issues of ML estimators based on full grid search are also addressed by various types of iterative grid search methods. One challenge to apply the ML estimation algorithm to multiple emitter localization problem is that, it requires a pdf approximation to summands of log-normal random variables for likelihood calculations at each grid location. This inspires our investigations on sum of log-normal approximations studied in literature for selecting the appropriate approximation to our model assumptions. As a final extension of this work, we propose our own approximation based on distribution fitting to a set of simulated data and compare our approach with Fenton-Wilkinson's well-known approximation which is a simple and computational efficient approach that fits a log-normal distribution to sum of log-normals by matching the first and second central moments of random variables. We demonstrate that the location estimation accuracy of the grid search technique obtained with our proposed approximation is higher than the one obtained with Fenton-Wilkinson's in many different case scenarios.
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Igarza, Sanchez Kiara Pierina, and Celis Jean Miguel Oscorima. "Propuesta de mejoramiento de capacidad hidráulica del emisor submarino de la PTAR La Chira mediante el uso del coeficiente de contracción de las válvulas de retención tipo Duckbill en el tramo difusor." Bachelor's thesis, Universidad Peruana de Ciencias Aplicadas (UPC), 2020. http://hdl.handle.net/10757/654021.
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Los emisores submarinos son preferibles para la descarga de aguas residuales domesticas tratadas, debido a la capacidad de asimilación del mar como una opción más económica. Si se eligen los sistemas de salida al mar, la ubicación es fundamental para evitar el retorno de las aguas residuales a la zona costera y la recuperación del ecosistema marino. Sobre la base de la regulación del control de descarga de efluentes que exige la Autoridad Nacional del Agua (ANA) de la República Democrática del Perú, la concentración de bacterias debe estar por debajo de un cierto valor en el área protegida. Esta tesis está basada en el método de investigación aplicativo, debido a que en el Perú no existe mucha información científica con respecto a los emisores submarinos. Por ello, esta investigación busca aumentar información científica de tal modo que para los siguientes proyectos que tengan que ver con emisores submarinos sean más eficientes a nivel hidráulico. Por otra parte, los efectos principales que influyen en la dilución son las corrientes costeras generadas por el viento y el transporte de aguas residuales en regiones costeras abiertas, como se encuentra en La Chira. Las predicciones del modelo de dispersión son precisas si cuentan con las características físicas del emisor submarino, del efluente y del océano, ya que nos brindan una perspectiva clara para la planificación del emisor submarino. En este estudio, se compara el caudal de diseño con el método de crecimiento geométrico, el cual es recomendado por la Organización Mundial de la Salud (OMS), con el caudal real del proyecto, donde se verifica que ambos caudales se aproximan. También, se verificó la capacidad hidráulica del emisor submarino para identificar las pérdidas de cargas totales que se producen a lo largo de todo el emisor. Además, el Visual Plumes, el cual es un software que genera modelos de dispersión de efluente en un cuerpo de agua, se utilizó para la dilución de campo cercano y la dilución de campo lejano del contaminante. Los resultados del modelo de dilución de campo cercano y de campo lejano muestran que el emisor submarino de La Chira cumple con las regulaciones legales ambientales.The submarine outfalls are the preferred solution for discharging treated domestic wastewaters due to the ocean’s assimilative capacity, as a cheaper option. If the exit systems to the sea are chosen, location is key to avoid the return of the wastewaters to the coastal area and for the marine ecosystem restoration. According to the effluent discharge control regulations dictated by the National Water Authority (Autoridad Nacional del Agua, ANA) of the Republic of Peru, the bacteria concentration level must be under a certain level in the protected area. This thesis is based on the applied research methodology, since there is not much scientific information available regarding submarine outfalls in Peru. For this reason, this research seeks to increase the scientific information so that the next projects involving submarine outfalls are more efficient in hydraulically. In the other hand, the main effects impacting dilution are coastal currents generated by the wind and the wastewaters flow into open coastal regions, as found in La Chira. The dispersion model predictions are accurate if they have the physical characteristics of the submarine outfall, the effluent and the ocean, since they provide a clear perspective for the submarine outfall planning. In this study, we compared the design flow rate with the geometric increase method recommended by the World Health Organization (WHO) with the real flow rate of the project, and it was verified that both flow rates are similar. Also, the submarine outfall hydraulic capacity was verified to identify the losses of total loads produced throughout the outfall. Furthermore, the Visual Plumes, a software that generates dispersion models of effluents in body of water, was used for the near-field and far-field dilutions of the contaminant. The results of near-field and far-field dilutions model show that the submarine outfall of La Chira meets the legal environmental regulations.
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Bates, R. "Silicon heterostructure intersubband emitters." Thesis, University of Cambridge, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.596474.
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It is believed that the Silicon Germanium (SiGe) materials system offers numerous benefits over GaAs/AlGaAs for operation within the THz gap - absorption coefficients are lower due to the non-polar nature of the SiGe lattice and the potential for integration with Si chips exists. Furthermore, operating within the valence band allows surface normal emission to be observed and vertical cavity surface emitting lasers to be fabricated using transitions between light (LH) and heavy (HH) hole subbands and poly-Si/silicon dioxide Bragg reflectors. This dissertation reports upon recent advances made in FIR Quantum Cascade Emitters (QCEs) based within the SiGe materials system. Initial measurements were designed purely to demonstrate the ability of the vertical intersubband transition to absorb radiation. Such structures were also observed to emit and spectroscopy was performed allowing the origin of such emission to be verified as being due to intersubband transitions. QCEs were then designed and processed, allowing the observation of the first surface-normal emission from a QCE in the absence of a grating to be observed. Further designs demonstrated the primary dependence upon the strain within the quantum wells of the energy of the LH1-HH1 transition. The scalability of the active regions has also been demonstrated - the strain symmeterised growth allowing hundreds of layers to be grown at a uniformly high standard. A shift from vertical (intrawell) to diagonal (interwell) transitions using photon assisted tunnelling lead to the theoretical observation of population inversion within the system. One of the key requirements for lasing, the existence of population inversion demonstrates both the potential and feasibility for a QCL to be fabricated in SiGe.
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Mróz, Izabela Magdalena. "Verkapselung von Mehrphotonen-Emittern." Clausthal-Zellerfeld Papierflieger-Verl, 2006. http://d-nb.info/987482750/04.
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