Academic literature on the topic 'THz emission sources'

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Journal articles on the topic "THz emission sources"

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Andronov, A. A., A. V. Ikonnikov, K. V. Maremianin, V. I. Pozdnjakova, Y. N. Nozdrin, A. A. Marmalyuk, A. A. Padalitsa, et al. "THz stimulated emission from simple superlattice in positive differential conductivity region." Физика и техника полупроводников 52, no. 4 (2018): 463. http://dx.doi.org/10.21883/ftp.2018.04.45812.01.

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AbstractNarrow band emissions at 2.6–2.8 THz are observed out of liquid helium cooled 1 mm disk chips prepared of a wafer with the very low n type doped weak barrier GaAs–GaAlAs superlattice of 1000 periods. The emissions are at about 8.0–18.0 V pulsed voltage applied to the chips in region of the chips positive DC differential conductivity that guaranties absence of inhomogeneous electric field domains in the chips. The emission frequency bands are estimated with a cyclotron resonance filter; the measurements show that the band width is of about that of the THz quantum cascade laser. By using long voltage pulses the chip heating above 100 K is achieved without substantial change in emission power. We speculate that the emission is super luminescence (amplification) of whispering gallery modes in the chips as a result of inverted Wannier-Stark level transitions under bias. The results are the first world demonstration of THz stimulated emission in a simple superlattice within region of positive DC differential conductivity; they give strong impetus for development of THz and higher frequency sources based on such simple superlattices; the sources should well compete with the THz quantum cascade lasers in particular at elevated temperatures.
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Wang, Maorong, Yifan Zhang, Leilei Guo, Mengqi Lv, Peng Wang, and Xia Wang. "Spintronics Based Terahertz Sources." Crystals 12, no. 11 (November 18, 2022): 1661. http://dx.doi.org/10.3390/cryst12111661.

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Terahertz (THz) sources, covering a range from about 0.1 to 10 THz, are key devices for applying terahertz technology. Spintronics-based THz sources, with the advantages of low cost, ultra-broadband, high efficiency, and tunable polarization, have attracted a great deal of attention recently. This paper reviews the emission mechanism, experimental implementation, performance optimization, manipulation, and applications of spintronic THz sources. The recent advances and existing problems in spintronic THz sources are fully present and discussed. This review is expected to be an introduction of spintronic terahertz sources for novices in this field, as well as a comprehensive reference for experienced researchers.
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Hu, Qing. "Generation of Terahertz Emission Based on Intersubband Transitions." International Journal of High Speed Electronics and Systems 12, no. 04 (December 2002): 995–1024. http://dx.doi.org/10.1142/s0129156402001897.

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In this chapter, we present our work on the development of coherent THz sources based on intersubband transition in quantum-well structures. The main focus is on electrically pumped or quantum-cascade structures, which have been quite successful in generating coherent radiation at mid-infrared frequencies. Relevant issues, such as various depopulation intersubband scattering rates, the role of complex phonon spectra, and coherent vs. incoherent tunneling are discussed in details. Optically pumped sources, including optical parametric amplifiers, and both intersubband and interband pumped THz emitters, are also investigated for their feasibility in generating coherent THz radiations.
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Wang, Suyun. "Terahertz Emission Modeling of Lunar Regolith." Remote Sensing 16, no. 21 (October 30, 2024): 4037. http://dx.doi.org/10.3390/rs16214037.

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We investigate the terahertz (THz) scattering and emission properties of lunar regolith by modeling it as a random medium with rough top and bottom boundaries and a host medium situated beneath. The total scattering and emission arise from three sources: the rough boundaries, the volume, and the interactions between the boundaries and the volume. To account for these sources, we model their respective phase matrices and apply the matrix doubling approach to couple these phase matrices to compute the total emission. The model is then used to explore insights into lunar regolith scattering and emission processes. The simulations reveal that surface roughness is the primary contributor to total scattering, while dielectric contrasts between the volume and the boundaries dominate total emission. The THz emissivity is highly sensitive to the regolith dielectric constant, particularly its imaginary part, making it a promising alternative for identifying previously undetected water ice in the lunar polar regions. The THz emissivity model developed in this study can be readily applied to invert the surface parameters of lunar regolith using THz observations.
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Minkevičius, Linas, Liang Qi, Agnieszka Siemion, Domas Jokubauskis, Aleksander Sešek, Andrej Švigelj, Janez Trontelj, Dalius Seliuta, Irmantas Kašalynas, and Gintaras Valušis. "Titanium-Based Microbolometers: Control of Spatial Profile of Terahertz Emission in Weak Power Sources." Applied Sciences 10, no. 10 (May 14, 2020): 3400. http://dx.doi.org/10.3390/app10103400.

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Terahertz (THz) imaging and spectroscopy set-ups require fine optical alignment or precise control of spatial mode profile. We demonstrate universal, convenient and easy-to-use imaging—resonant and broadband antenna coupled ultrasensitive titanium-based—dedicated to accurately adjust and control spatial mode profiles without additional focusing optical components of weak power THz sources. Versatile operation of the devices is shown using different kinds of THz—electronic multiplier sources, optical THz mixer-based frequency domain and femtosecond optoelectronic THz time-domain spectrometers as well as optically pumped molecular THz laser. Features of the microbolometers within 0.15–0.6 THz range are exposed and discussed, their ability to detect spatial mode profiles beyond the antennas resonances, up to 2.52 THz, are explored. Polarization-sensitive mode control possibilities are examined in details. The suitability of the resonant antenna-coupled microbolometers to resolve low-absorbing objects at 0.3 THz is revealed via direct, dark field and phase contrast imaging techniques as well.
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Chen, Yuxuan, Yuhang He, Liyuan Liu, Zhen Tian, Jianming Dai, and Xi-Cheng Zhang. "Backward THz Emission from Two-Color Laser Field-Induced Air Plasma Filament." Sensors 23, no. 10 (May 10, 2023): 4630. http://dx.doi.org/10.3390/s23104630.

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Two-color laser field-induced plasma filaments are efficient broadband terahertz (THz) sources with intense THz waves emitted mainly in the forward direction, and they have been investigated intensively. However, investigations on the backward emission from such THz sources are rather rare. In this paper, we theoretically and experimentally investigate the backward THz wave radiation from a two-color laser field-induced plasma filament. In theory, a linear dipole array model predicts that the proportion of the backward emitted THz wave decreases with the length of the plasma filament. In our experiment, we obtain the typical waveform and spectrum of the backward THz radiation from a plasma with a length of about 5 mm. The dependence of the peak THz electric field on the pump laser pulse energy indicates that the THz generation processes of the forward and backward THz waves are essentially the same. As the laser pulse energy changes, there is a peak timing shift in the THz waveform, implying a plasma position change caused by the nonlinear-focusing effect. Our demonstration may find applications in THz imaging and remote sensing. This work also contributes to a better understanding of the THz emission process from two-color laser-induced plasma filaments.
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Huang, Hsin-hui, Takeshi Nagashima, Wei-hung Hsu, Saulius Juodkazis, and Koji Hatanaka. "Dual THz Wave and X-ray Generation from a Water Film under Femtosecond Laser Excitation." Nanomaterials 8, no. 7 (July 13, 2018): 523. http://dx.doi.org/10.3390/nano8070523.

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Simultaneous emission of the THz wave and hard X-ray from thin water free-flow was induced by the irradiation of tightly-focused femtosecond laser pulses (35 fs, 800 nm, 500 Hz) in air. Intensity measurements of the THz wave and X-ray were carried out at the same time with time-domain spectroscopy (TDS) based on electro-optic sampling with a ZnTe(110) crystal and a Geiger counter, respectively. Intensity profiles of the THz wave and X-ray emission as a function of the solution flow position along the incident laser axis at the laser focus show that the profile width of the THz wave is broader than that of the X-ray. Furthermore, the profiles of the THz wave measured in reflection and transmission directions show different features and indicate that THz wave emission is, under single-pulse excitation, induced mainly in laser-induced plasma on the water flow surface. Under double-pulse excitation with a time separation of 4.6 ns, 5–10 times enhancements of THz wave emission were observed. Such dual light sources can be used to characterise materials, as well as to reveal the sequence of material modifications under intense laser pulses.
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Hawecker, J., E. Rongione, A. Markou, S. Krishnia, F. Godel, S. Collin, R. Lebrun, et al. "Spintronic THz emitters based on transition metals and semi-metals/Pt multilayers." Applied Physics Letters 120, no. 12 (March 21, 2022): 122406. http://dx.doi.org/10.1063/5.0079955.

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Spintronic terahertz (THz) emitters based on the inverse spin Hall effect in ferromagnetic/heavy metal (FM/HM) heterostructures have become important sources for THz pulse generation. The design, materials, and control of these interfaces at the nanometer level have become vital to engineer their THz emission properties. In this work, we present studies of the optimization of such structures through a multi-pronged approach, taking advantage of material and interface engineering to enhance THz spintronic emission. This includes the application of multi-stacks of HM/FM junctions and their application to trilayer structures, the use of spin-sinks to simultaneously enhance the THz emitted fields and reduce the use of thick Pt layers to reduce optical absorption, and the use of semi-metals to increase the spin polarization and, thus, THz emission. Through these approaches, significant enhancements of the THz field can be achieved. Importantly, taking into account the optical absorption permits to elucidate novel phenomena such as the relation between the spin diffusion length and the spin-sink using THz spectroscopy, as well as possibly distinguishing between self- and interface-spin-to-charge conversion in semi-metals.
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Lange, Simon Jappe, Matthias C. Hoffmann, and Peter Uhd Jepsen. "Lightwave-driven electron emission for polarity-sensitive terahertz beam profiling." APL Photonics 8, no. 1 (January 1, 2023): 016105. http://dx.doi.org/10.1063/5.0125947.

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The full exploitation of advanced light sources in the terahertz (THz) frequency range requires versatile experimental tools to fully characterize the spatial, temporal, and spectral shapes of the THz electric field. Several techniques for passive THz beam profiling exist that offer information about the temporally integrated intensity. Thus, any information about the electric field itself is lost. Here, we show that a UV–visible light emission produced via a lightwave-driven field emission from single-layer metasurfaces can be used to visualize the peak electric field distribution of THz beams in real time. Our technique is scalable up to frequencies approaching the plasma frequency of the metal used for the metasurface. Uniquely, our device is sensitive to the absolute polarity of the THz lightwave. These findings demonstrate a general pathway to designing metamaterial-based field-sensitive optical detectors suitable for the entire THz and IR spectral region.
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Consolino, Luigi, Malik Nafa, Michele De Regis, Francesco Cappelli, Saverio Bartalini, Akio Ito, Masahiro Hitaka, et al. "Direct Observation of Terahertz Frequency Comb Generation in Difference-Frequency Quantum Cascade Lasers." Applied Sciences 11, no. 4 (February 4, 2021): 1416. http://dx.doi.org/10.3390/app11041416.

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Terahertz quantum cascade laser sources based on intra-cavity difference frequency generation from mid-IR devices are an important asset for applications in rotational molecular spectroscopy and sensing, being the only electrically pumped device able to operate in the 0.6–6 THz range without the need of bulky and expensive liquid helium cooling. Here we present comb operation obtained by intra-cavity mixing of a distributed feedback laser at λ = 6.5 μm and a Fabry–Pérot device at around λ = 6.9 μm. The resulting ultra-broadband THz emission extends from 1.8 to 3.3 THz, with a total output power of 8 μW at 78 K. The THz emission has been characterized by multi-heterodyne detection with a primary frequency standard referenced THz comb, obtained by optical rectification of near infrared pulses. The down-converted beatnotes, simultaneously acquired, confirm an equally spaced THz emission down to 1 MHz accuracy. In the future, this setup can be used for Fourier transform based evaluation of the phase relation among the emitted THz modes, paving the way to room-temperature, compact, and field-deployable metrological grade THz frequency combs.
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Dissertations / Theses on the topic "THz emission sources"

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Abdul, Hadi Zeinab. "Terahertz emission spectroscopy of multiferroic bismuth ferrite : insights into ultrafast currents and phonon dynamics." Electronic Thesis or Diss., Le Mans, 2024. http://www.theses.fr/2024LEMA1030.

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La technologie térahertz (THz) a suscité un intérêt significatif dans la communauté scientifique en raison de sa position unique dans le spectre électromagnétique, complétant le gap entre les régions des micro-ondes et de l'infrarouge. Cette radiation est non ionisante et peut pénétrer divers matériaux sans les endommager, ce qui la rend très attirante pour de nombreuses applications potentielles. Les avancées récentes dans la technologie des lasers ultra-rapides ont élargi l'exploration du rayonnement THz à un large éventail de technologies passionnantes. Elle est désormais utilisée dans des domaines tels que la médecine pour de nouvelles techniques d'imagerie, en spectroscopie pour l'analyse des matériaux, dans les technologies de l'information et de la communication pour le transfert de données plus rapide, et même dans la sécurité, l'agriculture, le contrôle de qualité et la science des matériaux fondamentaux.Par conséquent, le développement de sources THz efficaces et réglables est devenu un défi au sein de la communauté THz pour développer davantage ces applications, motivant l'exploration de nouveaux matériaux et mécanismes d'émission THz. Dans mon projet de doctorat, j'ai exploré un nouvel émetteur THz : le matériau multiferroïque le plus connu, le ferrite de bismuth (BiFeO3). Ce matériau multiferroïque est particulièrement intéressant en raison de ses propriétés multiferroïques distinctives. Le BiFeO3 présente à la fois une large polarisation ferroélectrique et un ordre antiferromagnétique à température ambiante, offrant une interaction unique des ordres ferroélectriques et magnétiques et faisant de ce matériau un candidat prometteur pour la génération de THz.En utilisant un montage de spectroscopie d'émission THz que j'ai construit, avec sa détection électro-optique, j'examine l'émission THz de trois échantillons de BiFeO3 distincts. Le premier avec une polarisation dans le plan, un autre avec une polarisation hors plan, et un troisième présentant deux domaines avec deux différentes orientations de polarisation. Cette technique permet l'observation et l'analyse directes du rayonnement THz émis par ces échantillons suite à l'excitation laser au-dessus du gap.Les études expérimentales impliquent une analyse détaillée des signaux THz émis par les échantillons de BiFeO3 dans des conditions expérimentales variées. En variant les longueurs d'onde de la pompe, les orientations des échantillons, les directions de polarisation de la lumière de la pompe, et la puissance de la pompe, nous pouvons explorer comment ces facteurs influencent l'émission THz. Ensuite, nous séparent la dynamique ultra-rapide des porteurs (courant ultra-rapide) et les vibrations du réseau (phonons optiques) contribuant à ce signal THz émis. Enfin, en analysant leur réponse aux changements des paramètres expérimentaux, nous pouvons approfondir notre compréhension des mécanismes physiques contribuant à ces dynamiques ultra-rapides et à l'émission THz dans BiFeO3
Terahertz (THz) technologies have attracted significant interest in the scientific community due to their unique position in the electromagnetic spectrum, bridging the gap between the microwave and infrared regions. This radiation is non-ionizing and can penetrate various materials without causing damage, making it highly attractive for numerous potential applications. Recent advances in ultrafast laser technology have expanded the exploration of THz radiation into a wide range of exciting technologies. It’s now being used in fields like medicine for new imaging techniques, in spectroscopy for analyzing materials, in information and communication technology for faster data transfer, and even in security, agriculture, quality control and fundamental material science. Consequently, the development of efficient and tunable THz sources has become a major focus within the THz community to expand these applications further, motivating the exploration of new materials and emission mechanisms. In my PhD project, I have explored a promising new THz emitter: the well-known multiferroic material ‘Bismuth Ferrite’ (BiFeO3). This multiferroic material is particularly interesting due to its distinctive multiferroic properties. BiFeO3 exhibits both a large ferroelectric polarization and a antiferromagnetic order at room temperature offering a unique interplay of ferroelectric and magnetic orders and making this material a promising candidate for THz generation. Using a THz emission spectroscopy setup that I constructed, with its electro-optical sampling detection, I examine THz emission from three distinct BiFeO3 samples. First one with in-plane polarization, another with out-of-plane polarization, and a third presenting striped domains with two orientations of polarization. This technique allows for the direct observation and analysis of THz radiation emitted by these samples upon above gap laser excitation. The experimental investigation involves a detailed study of the THz transient signals emitted from the BiFeO3 samples under varying experimental conditions. By varying the pump wavelengths, sample orientations, directions of pump light polarization, and pump power levels, we can explore how these factors influence the THz emission. Following this, we extract the carrier dynamics (ultrafast current) and lattice vibrations (optical phonons) contributions to this THz transient. And finally, by analyzing their response to experimental parameters changes, we can have a deeper understanding of the physical mechanisms contributing to these ultrafast dynamics and THz emission in BiFeO3
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Ayoub, Anas. "Sources laser ultrarapides performantes dans le moyen IR et le Tz." Thesis, Normandie, 2020. http://www.theses.fr/2020NORMR044.

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La sonde atomique tomographique est un instrument d’analyse de la matière à trois dimensions avec une résolution atomique. Cet instrument s’appuie sur l’effet de champ électrique généré à l’extrémité d’un échantillon taillé sous la forme d’une aiguille nanométrique pour faire évaporer les atomes de surface qui sont collectés par un détecteur à deux dimensions. La mesure du temps de vol des ions dont l’évaporation est déclenchée par une impulsion électrique ou optique permettent de remonter à la composition chimique en plus de la localisation 3D des atomes. Dans les sondes atomiques actuelles, l’évaporation atomique est déclenchée par un laser ultrarapide émettant dans l’UV. Cependant, l’interaction de la lumière UV avec la matière induit un échauffement thermique qui limite la résolution en masse de l’instrument et empêche son exploitation pour l’analyse de matériaux fragiles comme les composants biocompatibles. Ces travaux de thèse visent à étudier des solutions pour favoriser l’évaporation rapide tout en inhibant les effets thermiques indésirables dans le cadre d’une sonde atomique laser. Notre approche consiste à exploiter des impulsions ultracourtes dans le domaine du moyen infrarouge ou du THz en raison de leur grande énergie pondéromotrice associée à une faible énergie de photon. Ce manuscrit rapporte sur le développementd’un banc de génération et caractérisation d’impulsions THz intenses. Le couplage de ces rayonnements avec une nano-pointe métallique polarisée négativement a permis de caractériser le champ proche induit à la surface de la nano-pointe qui est fortement modifié par l’effet d’antenne de cette dernière. La deuxième partie rapporte sur le développement d’une source laser ultrarapide de haute cadence accordable dans le moyen infrarouge autour de 3 mm en exploitant des fibres en verre fluoré
The atome probe tomography is an instrument for analyzing matter in three dimensions with atomic resolution. This instrument relies on the effect of an electric field generated at the end of a sample cut into the shape of a nanoscale needle to evaporate the surface atoms which are collected by a two-dimensional detector. The measurement of the time of flight of the ions whose evaporation is triggered by an electrical or optical pulse makes it possible to measure the chemical composition in addition to the 3D localization of the atoms. In current atome probes, atomic evaporation is triggered by a high-speed laser emitting in the UV. However, the interaction of UV light with matter induces thermal heating which limits the mass resolution of the instrument and prevents its use for the analysis of fragile materials such as biocompatible components. This thesis work aims to study solutions to promote rapid evaporation while inhibiting unwanted thermal effects of the laser in atome probe. Our approach consists in exploiting ultrashort pulses in the mid-infrared or THz domain due to their high ponderomotive energy associated with low photon energy. This manuscript reports on the development of a bench for the generation and characterization of intense THz pulses. Coupling these radiations with a negatively polarized metallic nanotip has made it possible to characterize the near field induced at the surface of the nanotip, which is strongly modified by the antenna effect. The second part reports on the development of an ultra-fast laser source tunable in the mid-infrared around 3 mm using fluoride glass fibers
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Copperwheat, C. M. "The optical emission from ultraluminous X-ray sources." Thesis, University College London (University of London), 2007. http://discovery.ucl.ac.uk/1445395/.

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Ultraluminous X-ray sources (ULXs) are point-like, non-nuclear sources which exceed the Eddington luminosity for a stellar mass black hole (BH). The emission from these sources might be beamed or super-Eddington, but it has also been pro posed that the compact object in these sources are intermediate mass BHs (IMBHs), which fit in the mass range between the two known populations of BH in the galaxy. The existence of IMBHs is under intense debate, and study of the X-ray data has been unable to resolve this issue. This thesis describes a model I have constructed in order to examine the optical/IR emission from these sources: an alternative channel by which their nature may be understood. I assume a binary model with a black hole accreting matter from a Roche lobe filling companion star. I consider the effects of radiative transport and radiative equilibrium in the irradiated surfaces of both the star and a thin accretion disc. I use current stellar evolutionary models as an input component in this model, and hence determine the mass, radius and age of the donor stars in a range of ULX systems, and in some cases provide limits on the BH mass. In addition I determine the mass transfer rate in these systems from the X-ray luminosity and compare this to transfer rate calculations based on the stellar evolutionary models. Since this method is independent of the optical data it is a powerful additional constraint on the parameter space. For systems where optical observations are available at multiple epochs, I make further determinations of the binary parameters based on the optical variability. Where it is possible to constrain the masses of the BHs, I find them to be consistent with BHs of up to 100A . I find that in general the donor stars are older and less massive than previously thought, and are consistent with being of spectral type B. I discuss how these results affect our understanding of the evolution and history of ULXs. I discuss how future studies of ULX optical counterparts will be even more revealing, and I make predictions for these optical campaigns, estimating binary periods, variability and the results of IR observational campaigns, which my results suggest will be a important tool in future studies of the nature of this class of sources.
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Xiu, Meng. "Evaluating the emission of air pollutants from different sources." Thesis, Queensland University of Technology, 2022. https://eprints.qut.edu.au/235386/1/Meng%2BXiu%2BThesis%284%29.pdf.

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This thesis is an evaluative study of air pollution emissions from different sources in Australia and overseas. It investigates indoor and outdoor sources, including indoor combustion, electric equipment, asphalt pavement, forest fires and vehicular traffic. Based on evaluating sources, a simple practical method is proposed to identify pollution sources. This research has important scientific implications and potential for future practical applications, given the paucity of quantitative air quality studies available for pollution control.
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Domański, Grzegorz. "The contribution of different sources to the total CO2 emission from soils /." Stuttgart : Inst. für Bodenkunde und Standortslehre, 2003. http://bvbr.bib-bvb.de:8991/F?func=service&doc_library=BVB01&doc_number=012802754&line_number=0001&func_code=DB_RECORDS&service_type=MEDIA.

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Lohmann, Rainer. "Studies on the atmospheric sources, fate and behaviour of dioxins and furans." Thesis, Lancaster University, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.322093.

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Holt, Joanna. "An observational study of the emission line systems in compact radio sources." Thesis, University of Sheffield, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.419256.

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Hunter, Gillian C. "The behaviour of plumes from point sources in stratified flows." Thesis, Open University, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.315334.

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Ursini, Francesco. "Constraining the high energy emission sources in the environment of supermassive black holes." Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAY062/document.

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Des trous noirs supermassifs de plusieurs centaines de millions de masses solaires résident au centre de la plupart des galaxies massives. Dans 90% des cas, ces trous noirs sont dans état quiescent, très peu lumineux. Cependant, dans les 10% restant, des processus extrêmement violents sont observés, avec la libération d'énorme quantités d'énergie no- tamment en UV, X et gamma. On observe aussi parfois des jets puissants de matière pouvant s'étendre sur plusieurs centaines de kpc. Le coeur de ces galaxies sont appelés Noyaux Actifs de Galaxie (NAG). Ce sont parmis les objets les plus lumineux de l'univers. L'accrétion de la matière environnante sur le trou noir supermassif central est unanimement reconnue comme la source d'énergie la plus plausible pour expliquer la puissance phénoménale observée. L'énergie gravitationelle serait ainsi en partie libérée dans un disque d'accrétion, sous forme de rayonnement thermique piquant dans l'optique/UV, et en partie rayonnée en X/gamma par une couronne de plasma chaud présente dans l'environnement proche du trou noir.De nombreux phénomènes sont néanmoins encore très mal connus et beaucoup de ques- tions n'ont toujours pas de réponses satisfaisantes: quelles sont la dynamique et la structure des flots d'accrétion et d'éjection dans les NAG? Quels sont les processus radiatifs produisant le rayonnement UV/X? Quelle est l'origine des différentes composantes spectrales présentes dans ces domaines d'énergie? Cette thèse a pour objectif d'apporter de nouvelles contraintes observationnelles pour meux répondre à ces questions. Son originalité réside dans le développement et l'utilisation de modèles réalistes de Comptonisation thermique permettant d'une part de mieux contraindre les propriétés physiques et géométriques des régions d'émission UV/X et d'autre part de mieux comprendre l'origine des différentes composantes spectrales observées. Nous nous sommes notamment intéressés, au cours de cette thèse, à l'excès d'émission X-mou (<2 keV), présent dans un grand nombre de NAG, et dont l'origine est toujours inconnue.Ces travaux s'articulent autour de deux axes principaux. Le premier est l'étude spectrale détaillée de longues campagnes d'observation multi-longueur d'ondes de trois galaxies de Seyfert (NGC 5548, NGC 7213 et NGC 4593). La qualité des données ont ainsi permis de révéler les paramètres physiques (notamment la température et la profondeur optique) et géométriques de la couronne thermique à l'origine du continuum X. Le second axe porte sur l'analyse de données d'archives (en provenance du satellite XMM-Newton) d'un échantillon important de galaxies de Seyfert. Cela a permis d'apporter, cette fois ci, des contraintes plus générales sur les processus d'émission haute énergie observés dans ces objets. Ces deux approches ont notamment montré que l'exces d'émission X-mou pouvait provenir des couches supérieures chaudes du disque d'accrétion, suggérant un chauffage plus efficace en surface plutôt que dans les régions internes
Supermassive black holes of several hundred million solar masses lie at the centre of most massive galaxies. In 90% of cases, these black holes are in quiescent, very low luminous states. Nevertheless, in the remaining 10%, extremely violent processes are seen, with the liberation of huge amounts of energy especially in the UV, X-ray and gamma-ray bands. We also sometimes observe powerful jets, extending up to several hundred kpc scales. The cores of these galaxies are called Active Galactic Nuclei (AGNs). These are among the most luminous objects in the Universe. The accretion of surrounding matter onto the central supermassive black hole is generally considered as the most likely energy source to explain the extraordinary observed luminosity. The gravitational energy would be partly liberated into an accretion disc as thermal radiation peaking in the optical/UV band, and partly radiated in the X-ray/gamma-ray band by a corona of hot plasma lying in the environment close to the black hole.However, several phenomena are still poorly understood and a number of questions lacks satisfactory answers: what are the dynamics and the structure of the accretion and ejection flows in AGNs? What are the radiative processes producing the UV/X-ray radiation? What is the origin of the different spectral components present in those energy bands? The goal of this thesis is to derive new observational constraints to better answer to these questions. Its originality resides in the development and application of realistic models of thermal Comptonization, allowing on the one hand to better constrain the physical and geometrical properties of the UV and X-ray-emitting regions, and on the other hand to better understand the origin of the different observed spectral components. In particular, we studied the excess of the soft (<2 keV) X-ray emission, seen in a great number of AGNs, and whose origin is still unknown.This work is structured along two main branches. One is the detailed spectral analysis of long, multiwavelength observational campaigns on three Seyfert galaxies (NGC 5548, NGC 7213 and NGC 4593). The quality of the data permitted to reveal the geometrical and physical parameters (in particular the temperature and optical depth) of the thermal corona producing the X-ray continuum. The second branch is based on the analysis of archival data (from the XMM-newton satellite) of a large sample of Seyfert galaxies. This allowed us to derive more general constraints on the high-energy emission processes observed in these objects. These two approaches have shown, in particular, that the soft X-ray emission excess may arise in the warm upper layers of the accretion disc, suggesting a more effective heating of the surface rather than the inner regions
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Falcetelli, Francesco. "Modelling of Pencil-Lead Break Acoustic Emission Sources using the Time Reversal Technique." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2018. http://amslaurea.unibo.it/16554/.

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In Acoustic Emissions (AE), Hsu-Nielsen Pencil-Lead Breaks (PLB) are used to generate sound waves enabling the characterization of acoustic wave speed in complex structures. The broadband signal of a PLB represents a repeatable emission, which can be applied at different regions of the structure, and therefore can be used to calibrate the localization algorithms of the AE system. In recent years, the use of Finite Element Method (FEM) has flourished for modelling acoustic Lamb wave propagation, which is present in thin plate-like structures. The primary challenge faced by the AE community is the lack of a well-known mathematical function of a PLB signal that can be applied in numerical simulations. This study makes use of a Time Reversal (TR) approach to identify the emission source of the PLB on a 7075-T651 aluminum plate. An ABAQUS CAETM model with piezoelectric actuators and sensors was developed. In order to avoid edge reflections, absorbing boundaries based on the Stiffness Reduction Method (SRM) were considered. The captured PLB signals were used as input to the FEM and was time-reversed. Furthermore, a band-limited white noise signal was used to calibrate the contribution of the broadband frequencies found in the transmitted wave packet. Preliminary results indicate that the TR approach can be used to understand the shape and function of the original transmitted signal.
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Books on the topic "THz emission sources"

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California Environmental Protection Agency. Air Resources Board. Stationary Source Division., California Environmental Protection Agency. Air Resources Board. Mobile Source Division., and California Environmental Protection Agency. Air Resources Board., eds. Mobile source emission reduction credits: Guidelines for the generation and use of mobile source emission reduction credits. [Sacamento]: State of California, California Environmental Protection Agency, Air Resources Board, 1993.

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F, Jones B., and United States. National Aeronautics and Space Administration., eds. Optical spectroscopy of IRAS sources with the infrared emission bands. [Washington, DC: National Aeronautics and Space Administration, 1987.

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United States. Environmental Protection Agency. Office of Air Quality Planning and Standards. Technical Support Division and Atmospheric Research and Exposure Assessment Laboratory (U.S.). Quality Assurance Division, eds. Protocol for the field validation of emission concentrations from stationary sources. Research Triangle Park, NC: Technical Support Division, Office of Air Quality Planning and Standards and Quality Assurance Division, Atmospheric Research and Exposure Assessment Laboratory, U.S. Environmental Protection Agency, 1991.

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Daywitt, William C. 10-60 GHz G/T measurements using the sun as a source: A preliminary study. [Washington, D.C.]: National Bureau of Standards, Dept. of Commerce, 1986.

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Daywitt, William C. 10-60 GHz G/T measurements using the sun as a source: A preliminary study. [Washington, D.C.]: National Bureau of Standards, Dept. of Commerce, 1986.

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Daywitt, William C. 10-60 GHz G/T measurements using the sun as a source: A preliminary study. [Washington, D.C.]: National Bureau of Standards, Dept. of Commerce, 1986.

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Daywitt, William C. 10-60 GHz G/T measurements using the sun as a source: A preliminary study. [Washington, D.C.]: National Bureau of Standards, Dept. of Commerce, 1986.

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Kananaskis Centre for Environmental Research. Results of the emission source surveys: Emission inventory of sulphur oxides and nitrogen oxides in Alberta. S.l: s.n, 1987.

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Anuradha, Koratkar, and United States. National Aeronautics and Space Administration., eds. The nature of the energy source in LINERs. [Washington, DC: National Aeronautics and Space Administration, 1996.

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International Vacuum Electron Sources Conference (5th 2004 Beijing, China). IVESC2004: The 5th International Vacuum Electron Sources Conference : proceedings : September 6-10, 2004, the Media Center Hotel, Beijing, China. Piscataway, N.J: IEEE, 2004.

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Book chapters on the topic "THz emission sources"

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Zaman, M., K. Kleineidam, L. Bakken, J. Berendt, C. Bracken, K. Butterbach-Bahl, Z. Cai, et al. "Methane Production in Ruminant Animals." In Measuring Emission of Agricultural Greenhouse Gases and Developing Mitigation Options using Nuclear and Related Techniques, 177–211. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-55396-8_6.

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AbstractAgriculture is a significant source of GHGsglobally and ruminant livestock animals are one of the largest contributors to these emissions, responsible for an estimated 14% of GHGs (CH4and N2O combined) worldwide. A large portion of GHG fluxes from agricultural activities is related to CH4 emissions from ruminants. Both direct and indirect methods are available. Direct methods include enclosure techniques, artificial (e.g. SF6) or natural (e.g. CO2) tracer techniques, and micrometeorological methods using open-path lasers. Under the indirect methods, emission mechanisms are understood, where the CH4 emission potential is estimated based on the substrate characteristics and the digestibility (i.e. from volatile fatty acids). These approximate methods are useful if no direct measurement is possible. The different systems used to quantify these emission potentials are presented in this chapter. Also, CH4 from animal waste (slurry, urine, dung) is an important source: methods pertaining to measuring GHG potential from these sources are included.
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Bikam, Peter Bitta. "Technology Innovations in Green Transport." In Green Economy in the Transport Sector, 37–49. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-86178-0_4.

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AbstractThe paper uses the case study of Limpopo province to discuss technology innovations in green transport in South Africa with respect to the reduction of global greenhouse emission through technology innovation. South Africa’s emission from fuel combustion is the world’s 15th largest in forms of CO emission because it contributes about 1.2% of global emissions. In a submission from the Department of Environmental Affairs (DEA) on the impact of greenhouse emissions stated that companies are required to be innovative to reduce the carbon emission levels in South Africa. Literature on road transport in South Africa shows that road transport is the fastest growing source of greenhouse gas emissions, accounting for 19% of global energy consumption. The policy to promote an integrated public transport in municipalities is in line with the National Development Plan and the White Paper on National Climate Change Response. This requires innovative technology that promotes carbon trading markets such as taxi recapitalisation programmes and carbon tax on new vehicles. The study analysed the factors influencing green technology innovations in South Africa with specific reference to Limpopo province green transportation study. The methodology used to unpack innovative technology in South Africa discusses green technology in Limpopo province in the context of greenhouse gases emission reduction innovative technologies in the transport sector with respect to sustainable fuels, energy efficient systems and smart information as well as hybrid technologies. The study advances arguments on technologies for engine and propulsion systems, alternative energy sources, navigation technologies, cargo handling systems, heating and cooling vehicles, road and rail vehicles and maritime transportation with respect to innovations as well as battery charging systems, engine oil disposal etc. The findings shows that no single trajectory of technology innovation in green transport will suffice but technological innovations that improve fuel economy and transition from fossil fuels to cleaner fuel alternatives. The study in Limpopo province showed that green transport innovations must not obscure the role of non-technological innovations in reducing emissions, but the two should be tackled with green transport value chain as a whole.
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Zaman, M., K. Kleineidam, L. Bakken, J. Berendt, C. Bracken, K. Butterbach-Bahl, Z. Cai, et al. "Greenhouse Gases from Agriculture." In Measuring Emission of Agricultural Greenhouse Gases and Developing Mitigation Options using Nuclear and Related Techniques, 1–10. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-55396-8_1.

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AbstractThe rapidly changing global climate due to increased emission of anthropogenic greenhouse gases (GHGs) is leading to an increased occurrence of extreme weather events such as droughts, floods, and heatwaves. The three major GHGs are carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O). The major natural sources of CO2 include ocean–atmosphere exchange, respiration of animals, soils (microbial respiration) and plants, and volcanic eruption; while the anthropogenic sources include burning of fossil fuel (coal, natural gas, and oil), deforestation, and the cultivation of land that increases the decomposition of soil organic matter and crop and animal residues. Natural sources of CH4 emission include wetlands, termite activities, and oceans. Paddy fields used for rice production, livestock production systems (enteric emission from ruminants), landfills, and the production and use of fossil fuels are the main anthropogenic sources of CH4. Nitrous oxide, in addition to being a major GHG, is also an ozone-depleting gas. N2O is emitted by natural processes from oceans and terrestrial ecosystems. Anthropogenic N2O emissions occur mostly through agricultural and other land-use activities and are associated with the intensification of agricultural and other human activities such as increased use of synthetic fertiliser (119.4 million tonnes of N worldwide in 2019), inefficient use of irrigation water, deposition of animal excreta (urine and dung) from grazing animals, excessive and inefficient application of farm effluents and animal manure to croplands and pastures, and management practices that enhance soil organic N mineralisation and C decomposition. Agriculture could act as a source and a sink of GHGs. Besides direct sources, GHGs also come from various indirect sources, including upstream and downstream emissions in agricultural systems and ammonia (NH3) deposition from fertiliser and animal manure.
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Goodrick, Scott L., Leland W. Tarnay, Bret A. Anderson, Janice L. Coen, James H. Furman, Rodman R. Linn, Philip J. Riggan, and Christopher C. Schmidt. "Fire Behavior and Heat Release as Source Conditions for Smoke Modeling." In Wildland Fire Smoke in the United States, 51–81. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-87045-4_3.

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AbstractModeling smoke dispersion from wildland fires is a complex problem. Heat and emissions are released from a fire front as well as from post-frontal combustion, and both are continuously evolving in space and time, providing an emission source that is unlike the industrial sources for which most dispersion models were originally designed. Convective motions driven by the fire’s heat release strongly couple the fire to the atmosphere, influencing the development and dynamics of the smoke plume. This chapter examines how fire events are described in the smoke modeling process and explores new research tools that may offer potential improvements to these descriptions and can reduce uncertainty in smoke model inputs. Remote sensing will help transition these research tools to operations by providing a safe and reliable means of measuring the fire environment at the space and time scales relevant to fire behavior.
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Brunetti, G., G. Setti, and A. Comastri. "On the X-Ray Emission from the Powerful Radio Galaxies." In Extragalactic Radio Sources, 407–8. Dordrecht: Springer Netherlands, 1996. http://dx.doi.org/10.1007/978-94-009-0295-4_145.

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Carvalho, Joel C. "On the Age of GPS Radio Sources." In Multi-Wavelength Continuum Emission of AGN, 424. Dordrecht: Springer Netherlands, 1994. http://dx.doi.org/10.1007/978-94-010-9537-2_134.

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Ruijing, Shi, Ren Peng, Fan Xiaochao, and Wang Jianglei. "Study on Optimization Operation of Micro-energy Network Considering Electro-ammonia Conversion." In Proceedings of the 10th Hydrogen Technology Convention, Volume 1, 452–64. Singapore: Springer Nature Singapore, 2024. http://dx.doi.org/10.1007/978-981-99-8631-6_44.

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AbstractMicro energy networks are an important way to achieve the “carbon neutrality” goal. To further explore the potential of energy conversion in reducing carbon emissions, this article proposes an optimized operation model for micro energy networks with refined power-to-ammonia conversion. Based on the operation model considering carbon trading and comprehensive demand response, an optimization model for micro energy networks with refined power-to-ammonia conversion is established, with the objective of minimizing the system’s operating cost and carbon emissions. Utilizing examples, various micro-source energy dispatch conditions are analyzed and the carbon emission costs, as well as the overall operating costs of the micro energy network, are calculated. The results show that compared with power-to-hydrogen conversion, using power-to-ammonia conversion in micro energy networks can effectively reduce system carbon emissions, with a decrease of 7.88% and a total operating cost reduction of 5.36%. This verifies the feasibility of the model and demonstrates that improving energy utilization can achieve the synergistic operation of the system’s economy and low-carbon emissions.
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Röttgering, Huub. "Distant Radio Galaxies: The Strong Link between the Radio and Optical Emission." In Extragalactic Radio Sources, 583–84. Dordrecht: Springer Netherlands, 1996. http://dx.doi.org/10.1007/978-94-009-0295-4_208.

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Bicknell, G. V., M. A. Dopita, and C. P. O’dea. "Shock Excitation of Emission Lines and the Relation to GPS Sources." In Extragalactic Radio Sources, 469–70. Dordrecht: Springer Netherlands, 1996. http://dx.doi.org/10.1007/978-94-009-0295-4_169.

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Meyer, Henry J., and Robert R. Alfano. "Conical Emission Produced from Femtosecond Laser Pulses." In The Supercontinuum Laser Source, 445–56. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-031-06197-4_11.

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Conference papers on the topic "THz emission sources"

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Oqbi, Manar Y., and Dhabia M. Al-Mohannadi. "Deciphering the Policy-Technology Nexus: Enabling Effective and Transparent Carbon Capture Utilization and Storage Supply Chains." In Foundations of Computer-Aided Process Design, 844–52. Hamilton, Canada: PSE Press, 2024. http://dx.doi.org/10.69997/sct.185903.

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In response to the global imperative to address climate change, this research focuses on enhancing the transparency and efficiency of the Carbon Capture Utilization and Storage (CCUS) supply chain under carbon tax. We propose a decision-making framework that integrates the CCUS supply chain's optimization model, emphasizing carbon tax policies, with a blockchain network. Smart contracts play a pivotal role in automating the exchange and utilization of carbon emissions, enhancing the digitalization of the CCUS supply chain from source to sink. This automation facilitates seamless matching of carbon sources with sinks, efficient transfer of emissions and funds besides record-keeping of transactions. Consequently, it improves the monitoring, reporting, and verification processes within the CCUS framework, thereby simplifying compliance with regulatory mandates for net emission reductions and carbon taxation policies. By eliminating reliance on third-party verifiers, our blockchain-based CCUS system reduces verification costs and ensures reliable tracking of emissions, mitigating the risk of carbon leakage. Policymakers and stakeholders gain valuable insights to optimize the CCUS network design, specifically considering the impact of carbon tax. This study represents an advancement in sustainable practices, providing a robust tool for decision-makers engaged in climate change mitigation efforts.
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Kunkel, William M., Christopher P. Donahue, Dominic T. Altamura, Cameron Dudiak, Benjamin Moscona-Remnitz, Nelson C. Goldsworth, Brandon Kennedy, and Michael J. Thorpe. "Aerial Gas Mapping Lidar for Methane Emission Source Localization, Quantification, and Large-Scale Statistical Characterization." In CLEO: Applications and Technology, ATh1E.6. Washington, D.C.: Optica Publishing Group, 2024. http://dx.doi.org/10.1364/cleo_at.2024.ath1e.6.

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Bridger Photonics measures methane emissions throughout the oil and natural gas supply chain. We describe sensor operation and requirements for large-scale emission inventories, including equipment identification, emission rate quantification accuracy, detection sensitivity, and sample coverage.
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TANI, Masahiko, Masayoshi TONOUCHI, Kiyomi SAKAI, Zhen WANG, Noriaki ONODERA, Masanori HANGYO, Yoshishige MURAKAMI, and Shin-ichi NAKASHIMA. "Emission Properties of YBCO-Film Photo-Switches as THz Radiation Sources." In 1996 International Conference on Solid State Devices and Materials. The Japan Society of Applied Physics, 1996. http://dx.doi.org/10.7567/ssdm.1996.d-5-5.

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Manohara, Harish, Wei Lien Dang, Peter H. Siegel, Michael Hoenk, Ali Husain, and Axel Scherer. "Field emission testing of carbon nanotubes for THz frequency vacuum microtube sources." In Micromachining and Microfabrication, edited by Danelle M. Tanner and Rajeshuni Ramesham. SPIE, 2004. http://dx.doi.org/10.1117/12.531403.

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Klimov, A. S. "THE SYNTHESIS OF BULK CERAMIC PRODUCTS USING FOREVACUUM PLASMA ELECTRON SOURCE." In Plasma emission electronics. Buryat Scientific Center of SB RAS Press, 2018. http://dx.doi.org/10.31554/978-5-7925-0524-7-2018-139-142.

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Baldanov, B. B., A. P. Semenov, and Ts V. Ranzhurov. "SURROUND THE SOURCE OF THE PLASMA JET ON THE BASIS OF LOW-VOLTAGE NONSTATIONARY DISCHARGE." In Plasma emission electronics. Buryat Scientific Center of SB RAS Press, 2018. http://dx.doi.org/10.31554/978-5-7925-0524-7-2018-92-97.

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Koval, T. V., V. I. Shin, M. S. Vorobyev, P. V. Moskvin, V. N. Devyatkov, and N. N. Koval. "CONDITIONS FOR ENSURING MINIMAL INHOMOGENEITY OF THE ELECTRON BEAM ON THE COLLECTOR IN SOURCES WITH A GRID PLASMA CATHODE." In Plasma emission electronics. Buryat Scientific Center of SB RAS Press, 2023. http://dx.doi.org/10.31554/978-5-7925-0655-8-2023-71-76.

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Mamedov, N. V., M. S. Lobov, I. M. Mamedov, A. Yu Presnyakov, and N. N. Shchitov. "CALCULATION OF THE VAC OF A PENNING ION SOURCE FOR A MINIATURE LINEAR ACCELERATOR." In Plasma emission electronics. Buryat Scientific Center of SB RAS Press, 2023. http://dx.doi.org/10.31554/978-5-7925-0655-8-2023-77-82.

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Shin, V. I., M. S. Vorobyev, P. V. Moskvin, V. N. Devyatkov, and N. N. Koval. "COMBINED CONTROL OF THE ELECTRON BEAM CURRENT IN A SOURCE WITH A GRID PLASMA CATHODE." In Plasma emission electronics. Buryat Scientific Center of SB RAS Press, 2023. http://dx.doi.org/10.31554/978-5-7925-0655-8-2023-97-100.

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Moiseenko, I. "Waveguide Modes in the AKR Source." In Planetary Radio Emissions VII. Vienna: Austrian Academy of Sciences Press, 2011. http://dx.doi.org/10.1553/pre7s253.

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Reports on the topic "THz emission sources"

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Panek, Jeffrey, Adrian Huth, James McCarthy, and Alan Krol. PR-312-18208-E01 Statistical Technique for Estimating NOx Emissions from Infrequently Operated Units. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), June 2020. http://dx.doi.org/10.55274/r0011681.

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This white paper presents a new approach for modeling emission inputs for dispersion modeling assessments. The approach is a paradigm shift from the current practice, which requires the simulation of source emissions by including all sources operating simultaneously for every hour during the year. This longstanding overly conservative approach does not adequately represent source emissions in some cases, especially from infrequent, non-continuously operated sources.
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Chepeliev, Maksym. Development of the Air Pollution Database for the GTAP 10A Data Base. GTAP Research Memoranda, June 2020. http://dx.doi.org/10.21642/gtap.rm33.

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The purpose of this note is to document data sources and steps used to develop the air pollution database for the GTAP Data Base Version 10A. Emissions for nine substances are reported in the database: black carbon (BC), carbon monoxide (CO), ammonia (NH3), non-methane volatile organic compounds (NMVOC), nitrogen oxides (NOx), organic carbon (OC), particulate matter 10 (PM10), particulate matter 2.5 (PM2.5) and sulfur dioxide (SO2). The dataset covers four reference years – 2004, 2007, 2011 and 2014. EDGAR Version 5.0 database is used as the main data source. To assist with emissions redistribution across consumption-based sources, IIASA GAINS-based model and IPCC-derived emission factors are applied. Each emission flow is associated with one of the four sets of emission drivers: output by industries, endowment by industries, input use by industries and household consumption. In addition, emissions from land use activities (biomass burning) are estimated by land cover types. These emissions are reported separately without association with emission drivers.
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Chepeliev, Maksym. Development of the Non-CO2 GHG Emissions Database for the GTAP 10A Data Base. GTAP Research Memoranda, March 2020. http://dx.doi.org/10.21642/gtap.rm32.

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The purpose of this note is to document data sources and steps used to develop the non-CO2 greenhouse gas (GHG) emissions database for the GTAP Data Base Version 10A. Emissions are reported for three types of non-CO2 GHGs – CH4 (methane), N2O (nitrous oxide) and the group of fluorinated gases (F-gases), and cover four reference years – 2004, 2007, 2011 and 2014. FAOSTAT dataset is used for sourcing agricultural non-CO2 emissions, EDGAR v5.0 and v4.2 databases are used to source non-agricultural emissions. Each emission flow is associated with one of the four sets of emission drivers: output by industries, endowment by industries, input use by industries and consumption by households.
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McGrath, Tom, Wendy Coulson, and James McCarthy. PR-312-18209-E01 Methane Emissions from Compressors in Transmission and Storage Subpart W Sources. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), November 2019. http://dx.doi.org/10.55274/r0011630.

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This white paper provides a step-by-step review of the methodology and data sources for development of compressor methane emission factors (EFs), and develops updated EFs based on Subpart W compressor measurement and leak survey data. The methodology is analogous to that used in a previous GRI/EPA Methane Emissions Study. In all cases, updated T and S compressor emission factors are lower than historical emission factors, and significantly lower in some cases. The updated emission factors provide a current best-estimate of T and S compressors emissions, and can be used to update emission estimates in the EPA Annual GHG Inventory Report, and to provide an alternative method for the annual estimate of compressor emissions for Subpart W.
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Coulson, Wendy, Tom McGrath, and James McCarthy. PR-312-16202-R03 Methane Emissions from Transmission and Storage Subpart W Sources. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), September 2019. http://dx.doi.org/10.55274/r0011619.

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A 2018 PRCI report evaluated related emissions from compressor seals, isolation valves, and blowdown valves based on direct measurements required by Subpart W of the GHG Reporting Program. This report presents the methane emissions data from 2011 - 2016 for the balance of the Subpart W emission sources, including: facility leaks (other than from compressor isolation valves and blowdown valves), pneumatic controller venting, condensate tank dump valve leakage, and blowdown emissions from stations. Transmission pipeline blowdown emission reporting was added to the EPA regulation in late 2015, and 2016 and 2017 pipeline blowdown data are presented in this report. The objective of the project is to evaluate and analyze the dataset, and compare methane emission estimates from these sources to historical data used by EPA, primarily the emission factors (EFs) from the mid-1990s EPA/Gas Research Institute (GRI) study used by EPA in its annual GHG inventory (GHGi) report. The results and related EFs and analysis of relative contribution from different sources can be used: (1) as an alternative to GHGi EFs for estimating methane emissions for Transmission and Storage (T and S) operations; (2) to document the relative contribution of different T and S methane emission sources; and (3) to identify reductions relative to historical estimates and support more efficient methane mitigation strategies. The Subpart W data for leaks and pneumatic devices are consistently lower than GHGi estimates, and blowdown emissions from compressor stations and transmission pipelines are similar in magnitude to GHGi estimates.
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6

McGrath, Panek, and McCarthy. L52356 Nomenclature for Natural Gas Transmission and Storage Greenhouse Gas Emissions. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), May 2012. http://dx.doi.org/10.55274/r0010015.

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A compilation of harmonized terminology and standardized nomenclature for natural gas transmission and storage (T and S) equipment and operations associated with greenhouse gas (GHG) emission sources and emission estimates. Criteria for natural gas industry (per segments in 40 CFR 98) for GHG inventories are also addressed. This living document is intended to be a detailed reference for practitioners and managers developing GHG inventories. The document's primary purpose is to support T and S facilities GHG emissions reporting for 40 CFR 98 Mandatory Greenhouse Gas Reporting�; however, information is also provided to support the development of GHG emission inventories for other purposes. Standardized nomenclature used in the estimation and reporting of greenhouse gas emissions and provide a single living document to be used as a reference to enhance consistency within the natural gas industry. This document may also serve to form a more accurate basis for consistent reporting of emission sources through an enhanced common understanding of industry and regulatory terminology, synonyms and sector boundaries. Consistent terminology will promote higher fidelity emission inventories and focus subsequent EPA control strategies and requirements.
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McCarthy, James. PR-312-18209-E05 Compressor and Facility Leak EFs for T and S - Clarifying Different Program Approaches. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), January 2024. http://dx.doi.org/10.55274/r0000050.

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Emission factors are often used to estimate methane leak emissions for natural gas transmission and storage facilities, such as compressor leak EFs and station leak EFs. However, different approaches are used in the literature for grouping compressor and other facility leak data, which can cause confusion when comparing estimates from different reports or data sources. It is also important to understand these differences when selecting EFs to use for purposes such as facility or system methane inventory development for a particular company or within a particular state. This white paper discusses the different the approaches used for T and S leak EFs based on Subpart W data reporting, and the historical and current EPA Annual GHG Inventory Report and tabulates the EFs to assist in understanding source-specific differences, and also to understand how EFs should be used to ensure all leak sources are included within an estimate, while not double-counting compressor station and storage facility leak emissions.
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Coulson, Wendy, and James McCarthy. PR-312-16202-R02 GHG Emission Factor Development for Natural Gas Compressors. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), May 2018. http://dx.doi.org/10.55274/r0011488.

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The U.S. EPA Greenhouse Gas (GHG) Reporting Program (GHGRP) requires compressor stations and underground storage facilities to measure compressor vent, rod packing, and seal emissions for facilities subject to 40 CFR, Part 98, Subpart W. The objective of the project is to gather and evaluate 2011 - 2016 Subpart W compressor vent and seal methane emissions data from site measurements, and present final results of an analysis to develop methane Emission Factors (EFs) based on these data. The EFs and analysis of relative contribution from different sources can be used: (1) as alternatives to current emission factors for compressor methane emissions used for Transmission and Storage (T and S) operations in EPA's annual GHG inventory; (2) to provide an EF based emission estimate for Subpart W that replaces ongoing annual GHGRP vent measurements; and (3) to document the relative contribution of different compressor leak/seal sources and support alternative leak mitigation strategies. Comparisons of the EPA Annual GHG Inventory EFs to Subpart W based EFs in this report show consistently lower compressor emissions than estimates based on historical data or reports. Large leaks, which stem from less than 3% of the compressor measurements, increase the EFs by 26% to 194%, thus greatly impacting the EF results. Alternative EFs are provided for transmission and storage compressor methane emissions.
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Stulen. L51628 A Transient Far-Field Model of the Acoustic Emission in Buried Pipelines. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), January 1986. http://dx.doi.org/10.55274/r0011317.

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This report describes the development of an analytical model to generate synthetic acoustic emission (AE) propagating in a buried gas transmission pipeline in response to a source. The sources are assumed to be transient forces acting at a point in the pipe wall. The solution of the model is the set of displacements at a given location relative to the point source. These displacements are the representations of the AE waveforms.
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10

Crocker, Raju, and Yang. L51796 Document CEM Experience in Natural Gas Transmission Industry. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), March 1999. http://dx.doi.org/10.55274/r0010426.

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Since passage of the 1990 Clean Air Act Amendments (CAAA), continuous emission monitoring system (CEMS) vendors, manufacturers, research organizations, parametric emissions monitoring system (PEMS) vendors, consultants, and source owner/operators have been developing strategies to satisfy compliance monitoring requirements that may eventually apply to many gas turbines and engines. A variety of CEMS and PEMS approaches have been developed, and evaluated to determine overall performance and cost. In addition, a few natural gas transmission companies have been required to install and operate CEMS on specific engines and turbines in order to comply with existing State permitting requirements or emissions trading programs.Within the next five years, the Environmental Protection Agency (EPA) is expected to promulgate a series of stationary source, air emission regulations that will have a significant impact on many industrial sources. In addition, EPA will be issuing regulatory revisions, policy manuals and guidance documents to further clarify the implementation and enforcement of rules recently promulgated - e.g., Title V Permitting, Compliance Assurance Monitoring (CAM) and Credible Evidence rules. As a part of each of these anticipated rules, revisions, and supporting documents, EPA will require and continue to refine corresponding compliance monitoring procedures and performance specifications. For the natural gas transmission industry, the anticipated regulatory changes could result in substantial increases in the cost of environmental compliance. Costs associated with pollution control (including reductions in engine/turbine efficiency), compliance monitoring, emissions reporting and recordkeeping may all increase as a result of pending regulatory requirements. This report has been prepared to document the natural gas transmission industry's experience operating continuous emission monitoring systems (CEMS) on reciprocating engines and stationary gas turbines and to discuss some of the more critical, technical issues that will have to be addressed if pending regulatory changes require the use of CEMS. In particular, this report provides technical discussions regarding the performance, operation, maintenance and costs of a CEMS program for compliance monitoring of nitrogen oxides emissions.
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