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Littérature scientifique sur le sujet « Ionized media »

Auteur : Grafiati

Publié le 11 janvier 2025

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Articles de revues sur le sujet "Ionized media"

Abouelatta, Mohamed Anwar, et Abdelhadi R. Salama. « An Equivalent Electrode System for Efficient Charging of Filtration Media ». Indonesian Journal of Electrical Engineering and Computer Science 3, n^o 3 (1 septembre 2016) : 646. http://dx.doi.org/10.11591/ijeecs.v3.i3.pp646-654.

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<p>This paper concerns the influence of moving an auxiliary limiting cylinder in X-Y directions on the electrostatic field and corona onset voltage of the dual electrode system employed in the electrostatic filtration process resulting in a “Tri-electrode” system. The Tri-electrode system is applied in order to control the field around the ionized wire and on the ground plate. Accurate calculation of the electrostatic field is obtained using the charge simulation method coupled with genetic algorithms. The calculated field values are utilized in computing the corona onset voltage of the ionized electrode. Laboratory measurements of the onset voltage of the ionized electrode are applied. It is found that the limiting cylinder controls the onset voltage of the ionized wire such that the ionized wire may be in ionized or non-ionized state without changing the position of the ionized wire itself. The numerical onset voltage values agreed satisfactorily with those measured experimentally. </p>

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Hayakawa, K., Y. Okuno, K. Fujiwara et Y. Shimizu. « Effect of Iodinated Contrast Media on Ionic Calcium ». Acta Radiologica 35, n^o 1 (janvier 1994) : 83–87. http://dx.doi.org/10.1177/028418519403500117.

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This study was conducted to characterize the alterations in serum ionized calcium induced by contrast media (CM) and to determine the cause of the change. Fresh human blood samples as well as an electrolyte solution (ES) containing 1.2 mM calcium ions were diluted with CM and alterations in ionized calcium were measured using an electrometer. The CM tested were diatrizoate, iopamidol, iohexol, ioxaglate, isotonic saline, Na2-Ca-EDTA and pure meglumine. When CM were mixed with blood, ionic CM produced a greater decrease in ionized calcium than nonionic CM or saline. When mixed with ES, a significant reduction of ionized calcium was induced by ioxaglate and diatrizoate in comparison with saline. Na2-Ca-EDTA and meglumine caused no reduction in ionized calcium. Ioxaglate and diatrizoate caused calcium binding due to anions; binding induced by the latter was more prominent than that by the former. These observations suggest that a nonionic CM is more desirable for coronary arteriography of high-risk patients.

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Konigl, Arieh. « Magnetic braking in weakly ionized media ». Astrophysical Journal 320 (septembre 1987) : 726. http://dx.doi.org/10.1086/165590.

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JOHNSON, ROBERT W. « Macroscopic electromagnetic stress tensor for ionized media ». Journal of Plasma Physics 77, n^o 1 (22 décembre 2009) : 107–16. http://dx.doi.org/10.1017/s002237780999050x.

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AbstractFollowing the arguments presented by Mansuripur [Opt. Express, vol. 16, 2008, pp. 14821–14835], we suggest a form for the macroscopic electromagnetic stress tensor appropriate for ionized media. The generalized Lorentz force includes the effects of polarization forces as well as those on the free charge and current densities. The resulting tensor is written in terms of the fields D, B, E, and H. Its expression for a fully ionized medium subject to an external electromagnetic field is discussed, as are the plasma conservation equations. An apparatus is suggested for its experimental discrimination.

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Motojima, Kuniyuki, Makoto Ohki et Shogo Kozaki. « Estimation of electron density in inhomogeneous ionized media ». Electronics and Communications in Japan (Part I : Communications) 82, n^o 11 (novembre 1999) : 1–7. http://dx.doi.org/10.1002/(sici)1520-6424(199911)82:11<1 ::aid-ecja1>3.0.co;2-x.

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Abrosimov, I. N., N. I. Abrosimov, L. M. Makalsky et T. Y. Fokin. « Technologies of Atmospheric Electrodynamics Based on Ionized Dispersed Media ». Russian Journal of General Chemistry 91, n^o 12 (décembre 2021) : 2729–33. http://dx.doi.org/10.1134/s1070363221120501.

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Leprovost, Nicolas, et Eun-jin Kim. « Self-consistent Mean Field Theory in Weakly Ionized Media ». Astrophysical Journal 598, n^o 2 (21 novembre 2003) : L99—L102. http://dx.doi.org/10.1086/380894.

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van Hoof, P. A. M., J. C. Weingartner, P. G. Martin, K. Volk et G. J. Ferland. « Grain size distributions and photoelectric heating in ionized media ». Monthly Notices of the Royal Astronomical Society 350, n^o 4 (juin 2004) : 1330–41. http://dx.doi.org/10.1111/j.1365-2966.2004.07734.x.

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Smith, Gregory N. « Proton transfer in nonpolar solvents : an approach to generate electrolytes in aprotic media ». Physical Chemistry Chemical Physics 20, n^o 28 (2018) : 18919–23. http://dx.doi.org/10.1039/c8cp02349b.

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Dote, Toshihiko, et Masatoshi Shimada. « Transport Coefficients of Charged Particles in Weakly Ionized Gas Media ». IEEJ Transactions on Fundamentals and Materials 111, n^o 3 (1991) : 159–67. http://dx.doi.org/10.1541/ieejfms1990.111.3_159.

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Plus de sources

Thèses sur le sujet "Ionized media"

Altuntas, Emre. « Forecasting Of The Electromagnetic Waves In Ionized Media Related To Aerospace Applications ». Master's thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/12608781/index.pdf.

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The dominant natural electromagnetic (EM) radiation in the extremely low frequency (ELF) range is due to global lightning activity. Radio waves of ELF band traveling along the surface of the ground are able to circle the globe and return to the starting point. Schumann Resonances (SR) are the EM phenomena which occur in the cavity formed by the conducting Earth and the ionosphere, with peak frequencies close to 8, 14, 20, 26 Hz, etc. The spectral characteristics of the SR modes are defined by their resonant mode amplitudes, center frequencies and half-widths. The characteristics of the SR became important in aerospace, marine applications, atmospheric studies, in addition to their relevance to global lightning studies due to their frequency band. The objective of this work is two fold: (i) to investigate the characteristics of SR parameters obtained at Sarkoy in Turkey
(ii) to model the nonlinear characteristics of the Near Earth Space Processes by forecasting the 1st SR mode intensities different time steps in advance using neural network modeling approach. The results show that the SR amplitudes exhibit the characteristics of Tropical African lightning activity and have maxima around 1400 UT. The neural network results show that the proposed model is able to forecast SR amplitudes from 0,5 to 36 hours in advance within reasonable error limits. Furthermore, a fuzzy neural network model with a non&ndash
linear optimization algorithm for the training phase is proposed and tested for the future work.

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Ashmore, Ian. « Time dependent multifluid magnetohydrodynamic models of C-type shocks in weakly ionized, dusty media ». Thesis, University of Leeds, 2011. http://etheses.whiterose.ac.uk/13307/.

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During the star formation process, low mass protostars go through a period of mass loss which involves expelling as much as half of the material from the accretion disk along their polar axes. The ejected material affects the environment surrounding the protostar as it interacts with the quiescent material of the core. Some of the core material is entrained and accelerated above the local sound speed, ensuring that shocks are present at the interfaces with the undisturbed cloud. Because of the high densities, appreciable magnetic field and low fractional ionization in such regions, ambipolar diffusion allows the ram pressure of the flow to be dissipated over an extended distance instead of one or two collisions. This precludes collisional ionization and reduces molecular dissociation in the shock front and therefore guarantees efficient cooling. The entrained cloud material is known as a molecular outflow and the extended associated shocks are denoted C-type. In addition, the conditions in the shocks produce streaming velocities between the charged and neutral species. This allows the dust grains present to become negatively charged and facilitates collisions and chemical reactions both in the gas phase and on grain surfaces. Although previous work exists into the structure and processes in C-type shocks, computational limitations have restricted most studies to either shocks at steady state or ones which are perpendicular to the magnetic field. The conditions in molecular clouds make steady shocks unlikely and the outflows make an arbitrary angle with the magnetic field making it unlikely that an individual outflow is even nearly perpendicular to the upstream field. A new MHD scheme is available which allows numerical models the structures of non-steady oblique shocks to be made. This thesis details multifluid MHD models of the C-type shocks in molecular outflows using this scheme. Steady perpendicular and oblique C-type shock structures are obtained for suitable molecular outflow conditions and compared to previous models to confirm the schemes accuracy. The first non-steady simulations are undertaken to investigate the interaction of steady, oblique C-type shocks with perturbations in the upstream density which are chosen to simulate the clumpy nature of molecular cloud cores. Finally terms are developed to describe the systematic collisions between charged grains and neutrals which are thought to return icy mantle and refractory grain core material to the gas phase in a process known as sputtenng. A region of parameter space suitable for the molecular outflows from low mass protostars is explored. The results are compared to previous observations and theoretical investigations. Chemical segregations are noted along the outflow axis, most notably between HCO+, which is common in the upstream region and the edge of the precursor and water and SiO, which become common in the shock and remain so in the downstream region. It is found that the formation and sputtering of water directly causes the HCO+ abundance to fall. This finding is in harmony with recent observations. Further investigation also reveals a that the material sputtered from the grains has a dependence on the angle between the shock normal and the upstream magnetic field. Such a dependence follows from the expressions employed for the sputtering rates, but has not been previously noted or quantified. It is found that the angular dependance is important over a wide region of the parameter space and the insights gained are likely to affect the interpretation of observations of the gas phase products of sputtering in the future.

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Huang, Jeffrey. « Numerical solutions of continuous wave beam in nonlinear media ». PDXScholar, 1987. https://pdxscholar.library.pdx.edu/open_access_etds/3742.

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Deformation of a Gaussian beam is observed when it propagates through a plasma. Self-focusing of the beam may be observed when the intensity of the laser increases the index of refraction of plasma gas. Due to the difficulties in solving the nonlinear partial differential equation in Maxwell's wave equation, a numerical technique has been developed in favor of the traditional analytical method. Result of numerical solution shows consistency with the analytical method. This further suggests the validity of the numerical technique employed. A three dimensional graphics package was used to depict the numerical data obtained from the calculation. Plots from the data further show the deformation of the Gaussian beam as it propagates through the plasma gas.

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Ince, Sevi. « Analysis Of Preformed Plasma Condition Of Ni-like Mo X-ray Laser Media ». Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/12607586/index.pdf.

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The aim of this work is to produce X-ray laser source from a plasma produced by focusing a pulsed laser beam on a solid target. Preformed Molybdenum plasma is created by using Nd:YAG laser pulses with a pulse duration 6 ns and pulse intensity 5.09x1011 W/cm2. Detailed simulations of Ni-like Mo X-ray laser media are undertaken using the EHYBRID code which is a hydrodynamic code. X-ray resonance lines between 25 Å
and 40 Å
emitted from the molybdenum plasma have been obtained and analysed. EHYBRID code also gives an information about the electron temperature, electron density, efficient ionization degree and plasma expansion distance of the Ni-like Mo X-ray laser media. An experimental set-up to produce preformed Mo plasma for x-ray laser has been designed for a future work.

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Hernoux-Villière, A. (Audrey). « Catalytic depolymerisation of starch-based industrial waste:use of non-conventional activation methods and novel reaction media ». Doctoral thesis, Oulun yliopisto, 2013. http://urn.fi/urn:isbn:9789526201634.

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Abstract The rapid increase of energy demand for transportation generates a rise of environmental pollution, stimulating the development of alternative sources of energy. Biomass is considered as the main organic carbon source of energy to substitute petroleum permitting sustainable production of chemicals and transportation fuels. Biowastes, residues and non-edible feedstock possess high potential resources avoiding food competition. This research aims to convert starch-based industrial waste, potato peels, into reducing sugars and platform molecules, such as glucose. These high added-value chemicals can further be transformed into chemicals and fuels. Catalytic conversion of starch, the main constituent of potato peels, was activated with non-conventional technologies to enhance the depolymerisation rate and to reduce energy consumption according to the principles of green chemistry. Depolymerisation of starch was first performed in acidic water as reaction medium assisted with ultrasonic and/or microwave irradiation. Ultrasonic irradiation enhanced mass transfer of heterogeneous system, whereas the use of microwaves improved heat transfer in the reaction medium. The frequency applied leads to different effects on heterogeneous systems: low frequencies irradiation (below 100 kHz) generates turbulences resulting in enhanced transport properties, whereas higher frequencies produce chemical effects. Catalytic conversion of starch into reducing sugars required more energy than individual irradiation could provide. Simultaneous irradiation, combining ultrasound and microwave or several ultrasonic frequencies, on potato peels led to 50% yield of sugars without former separation processes, at moderate temperature. A weak synergetic effect was only observed with potato peels. The second part of this research is dedicated to study the effect of catalytic reaction medium (acids, ionic liquids). More appropriate systems possess the ability to dissolve and hydrolyse carbohydrates: specific ionic liquids. A room-temperature ionic liquid and a task-specific ionic liquid were selected for their solvability properties to dissolve and depolymerise starch present in potato peels. The depolymerisation of starch in the task-specific ionic liquid generated a yield of 43% of sugars, without former separation process
Tiivistelmä Liikenteen energiantarpeen nopea kasvu on johtanut päästöjen sekä ympäristösaasteiden lisääntymiseen. Biomassa on merkittävä raaka-ainevaihtoehto fossiiliselle hiilelle energian, kemikaalien ja liikenteen polttonesteiden tuotannossa. Erityisesti jätebiomassoilla on suuri merkitys biomassaraaka-aineena, koska ne eivät kilpaile ruoantuotannon kanssa. Väitöskirjatutkimuksen tavoitteena on tärkkelyspohjaisen teollisen jätteen, perunan kuorilietteen, katalyyttinen muuttaminen pelkistäviksi sokereiksi ja ns. platform-kemikaaleiksi, kuten glukoosiksi. Näistä korkean lisäarvon omaavista välituotteista voidaan edelleen valmistaa uusia biomassapohjaisia kemikaaleja ja polttoaineita. Tärkkelyksen, perunankuoren keskeisimmän aineosan, muuttaminen tehtiin tässä työssä mm. ultraääni- ja mikroaaltoavusteisella hajotuksella. Tavoitteena oli parantaa perunan kuorilietteen liukenemis- ja hajoamisnopeutta, lisätä saantoa sekä vähentää energian kulutusta vihreän kemian periaatteiden mukaisesti. Tärkkelyksen depolymerointi tehtiin ensin happokatalysoidussa liuoksessa ultraäänen ja/tai mikroaaltojen avulla. Ultraäänihajotus lisäsi aineensiirtoa heterogeenisessä reaktioväliaineessa, kun taas mikroaallot lisäsivät lämmönsiirtoa reaktioseoksessa. Eri ultraäänitaajuuksilla havaittiin olevan erilaisia vaikutuksia reaktioseokseen: alhaisilla taajuuksilla (alle 100 kHz) muodostuneet pyörteiset virtaukset edistivät aineensiirtoa ja korkeammat taajuudet kemiallisia ilmiöitä. Tärkkelyksen katalyyttinen depolymerointi vaatii enemmän energiaa kuin perinteisillä menetelmillä, kuten lämmittämällä, voidaan tuottaa. Yhdistämällä ultraäänen ja mikroaaltojen säteilytystä tai eri taajuuden omaavia ultraääniä, yli 50% perunajätteen tärkkelyksestä saadaan hajotettua pelkistyneiksi sokereiksi alhaisissa lämpötiloissa. Sen sijaan, ainoastaan perunankuorijätteellä havaittiin heikko synenerginen efekti mitä ei havaittu vertailunäytteellä (perunajauho). Toisena tavoitteena oli tutkia katalyyttisen reaktioseoksen (hapot, ioniset liuottimet) vaikutusta perunan kuorijätteen ja sen sisältämän tärkkelyksen liuottamiseen ja hajottamiseen. Erityisesti keskityttiin uusiin, spesifisiin ionisiin liuottimiin, jotka kykenevät samanaikaisesti sekä liuottamaan että hydrolysoimaan hiilihydraatteja. Huoneenlämpötilassa toimiva spesifinen ioninen liuotin valittiin sen katalyyttisten ominaisuuksien vuoksi. Tässä liuottimessa kuorilietteen sisältämästä tärkkelyksestä pelkistyneiden sokerien saanto oli 43%
Résumé La forte demande en énergie, la conscience sociale sur les changements climatiques mondiaux et l'épuisement à moyen terme des réserves d’énergies fossiles stimulent le développement de ressources alternatives. Considérée comme la principale source de carbone organique renouvelable, la biomasse peut être utilisée pour remplacer les carburants d’origine fossile tout en étant plus respectueuse de l’environnement. Des déchets biosourcés ainsi que des végétaux d’origine agricole ou forestière, appelés biomasse végétale, possèdent de fort potentiels évitant la concurrence alimentaire. Cette recherche a pour objectif de convertir un déchet industriel amidonné, des pelures de pommes de terre, en sucres réducteurs et molécules plateformes, tels que le glucose, qui par la suite peuvent être transformées en carburants de transport. L’utilisation des ultrasons ainsi que des micro-ondes, méthodes non-conventionnelles, en milieu acide ont permis d’améliorer le rendement ainsi que de réduire la consommation énergétique en accord avec les principes de la chimie verte. L’irradiation ultrasonore améliore le transfert de masse de systèmes hétérogènes, alors que les micro-ondes renforcent le transfert de chaleur dans le milieu réactionnel. De plus, la fréquence ultrasonore appliquée induit différents effets sur le système : les ultrasons de basse fréquence (en dessous de 100 kHz) génèrent des turbulences améliorant les propriétés de transport de la matière, alors que les ultrasons de plus haute fréquence produisent des effets chimiques, tels que la formation de radicaux libres. L’apport énergétique fourni par les ultrasons et micro-ondes seuls étant insuffisant, l’utilisation d’irradiations simultanées et combinées a conduit à un rendement de 50% de sucres depuis l’amidon, ne nécessitant aucun procédé de séparation pré-réactionnel. Un faible effet synergique a pu être observé sur la dépolymérisation de la pelure de pommes de terre. L’étude d’un milieu réactionnel permettant simultanément la dissolution ainsi que l’hydrolyse des glucides présents dans la matière première est développée dans la seconde partie de ce mémoire. Certains liquides ioniques possèdent les propriétés recherchées. La dépolymérisation de l'amidon dans un liquide ionique à tâches spécifiques a permis d’obtenir un rendement de 43% de sucres, sans aucun procédé de séparation pré-réactionnel

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Boffelli, Jeoffrey. « Cοllisiοns réactives entre électrοns et catiοns d'hydrures : apprοches théοriques et applicatiοns dans les milieux iοnisés hοrs-équilibre ». Electronic Thesis or Diss., Normandie, 2024. http://www.theses.fr/2024NORMLH19.

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Les collisions de molécules par impact d'électrons sont présentes dans les milieux ionisés froids tel que les nuages interstellaire, les atmosphères de planètes et les plasma froids. Avec assez d'énergie pour se déplacer et s'extraire, les électrons collisionnent et réagissent avec d'autres espèces dans leur environnement formant des précurseurs de molécules plus complexes ainsi que détruisant d’autres espèces, permettant la redistribution d’énergie et de matière. Les chercheurs expérimentaux et théoriques travaillent main dans la main pour améliorer en continue leur capacité de mesure et de description de la cinétique de ces milieux. Des appareils de mesures tel que les anneaux de stockage (e.g. CSR) sont maintenant capables de produire des mesures avec une résolution d’état à état. D’autre part, les études théoriques, elles, ne sont pas restreintes par des limitations physiques (e.g. finance) ou chimiques (e.g. toxicité) mais restent, comme les expériences, longues à mener.Ce travail de thèse porte sur deux approches théoriques et leurs applications pour étudier différents processus de trois cations moléculaires diatomiques. Premièrement, nous étendons l’étude précédente de notre groupe sur la recombinaison dissociative de CF+ en prenant en compte plus d’états dissociatives (venant de la symétrie neutre 4Π), en produisant des rapports de branchements et en calculant des sections efficaces et des vitesses de réactions pour l’excitation vibrationnelle (en utilisant l’approche SW-MQDT). Malgré que la structure rotationnelle soit négligée, et qui devrait être étudié dans un travail future, on observe un bon accord avec les résultats expérimentaux des anneaux de stockage pour les rendements venant du processus de recombinaison dissociative. Deuxièmement, nous étendons à haute énergie, l’étude de BeH+ précédente de notre groupe à basse énergie en incluant le processus d’excitation dissociative à travers la discrétisation des continuum d’ionisation et en prenant en compte des états dissociatives plus haut énergétiquement, permettant la production de sections efficaces et de vitesses de réactions pour la recombinaison dissociative, l’excitation dissociative et les transitions vibrationnelles (en utilisant l’approche SW-MQDT). En fin, nous étudions la recombinaison dissociative de CF+ en utilisant une approche différente appelée RMT-MQDT, où les couplages électroniques et les états dissociatives n’ont pas besoin d’être calculés de manière explicite, basée sur la théorie de la R-matrice pour calculer la matrice de diffusion à géométrie fixée électronique et aussi basée sur la théorie de la MQDT --- pour traiter le mouvement nucléaire (changement de repère) et prenant en compte les séries d’états de Rydberg (défaut quantiques avec CCEP). Un bon accord est trouvé avec l’expérience des anneaux de stockage lorsque la structure rotationnelle de la molécule est pris en compte
Electron-impact collisions of molecules are present in cold ionized media such as interstellar clouds, planetary atmospheres and cold plasma. With enough energy to move about and escape from capture, electrons collide and react with other species in their environment forming precursors of more complex molecules and destroying species, allowing for redistribution of energy and material. Experimental and theoretical researchers are working hand-in-hand to continuously improve their respective ability to probe and to describe the kinetic of such media. Experimental devices such as storage-rings (e.g. CSR) are now able to produce measurements with state-to-state resolution. On the other hand, theoretical studies are not restricted by physical (e.g. finance) or chemical (e.g. toxicity) limitations while still being time-consuming. This work is about two theoretical approaches and their applications to investigate different processes for three diatomic molecular cations. Firstly, we extend our group previous dissociative recombination study of SH+ by accounting for more dissociative states (coming from the 4Π neutral symmetry), by producing branching ratios and by calculating vibrational excitation cross sections and rate coefficients (using the SW-MQDT approach). While the rotational structure of the molecule is neglected and should be investigated in a future work, good agreement is found with the storage-ring measurements for the yields from the dissociative recombination process. Secondly, we also extend our group previous low energy study BeH+ to high energy including the dissociative excitation process through discretized ionization continua and by accounting for higher-lying dissociative states, allowing the production of cross sections and rate coefficients for the dissociative recombination, dissociative excitation and vibrational transitions (using the SW-MQDT approach). Finally, we investigate the dissociative recombination of CF+ using a different approach called RMT-MQDT, where electronic couplings and neutral dissociative states do not need to be explicitly calculated, based on R-matrix theory to calculate the electronic fixed-geometry scattering matrix and based also on MQDT theory --- for the treatment of the nuclear motion (frame transformation) and accounting for the Rydberg series of states (quantum defect with CCEP). Good agreement is found with the storage-ring experiment when accounting for the rotational structure of the molecule

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Livres sur le sujet "Ionized media"

Melrose, D. B. Electromagnetic processes in dispersive media : A treatment based on the dielectric tensor. Cambridge [England] : Cambridge University Press, 1991.

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Kalluri, Dikshitulu K. Electromagnetics of time varying complex media : Frequency and polarization transformer. 2^e éd. Boca Raton, FL : CRC Press, 2010.

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Stanton, Bonita. Physics and technology of high current discharges in dense gas media and flows. Hauppauge, N.Y : Nova Science Publishers, 2009.

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McPhedran, R. C., et D. B. Melrose. Electromagnetic Processes in Dispersive Media. Cambridge University Press, 2005.

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McPhedran, R. C., et D. B. Melrose. Electromagnetic Processes in Dispersive Media. Cambridge University Press, 2011.

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McPhedran, R. C., et D. B. Melrose. Electromagnetic Processes in Dispersive Media. Cambridge University Press, 2009.

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Kalluri, Dikshitulu K. Electromagnetics of Time Varying Complex Media. Taylor & Francis Group, 2010.

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Electromagnetics of time varying complex media : Frequency and polarization transformer. 2^e éd. Boca Raton : Taylor & Francis, 2010.

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Kalluri, Dikshitulu K. Electromagnetics of Time Varying Complex Media : Frequency and Polarization Transformer, Second Edition. Taylor & Francis Group, 2018.

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Kalluri, Dikshitulu K. Electromagnetics of Time Varying Complex Media : Frequency and Polarization Transformer, Second Edition. Taylor & Francis Group, 2018.

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Chapitres de livres sur le sujet "Ionized media"

Thompson, A. Richard, James M. Moran et George W. Swenson. « Propagation Effects : Ionized Media ». Dans Astronomy and Astrophysics Library, 725–66. Cham : Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-44431-4_14.

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Kraaijeveld, F., et J. M. Huyghe. « Propagating Cracks in Saturated Ionized Porous Media ». Dans Multiscale Methods in Computational Mechanics, 425–42. Dordrecht : Springer Netherlands, 2010. http://dx.doi.org/10.1007/978-90-481-9809-2_21.

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Huyghe, Jacques M., Charles F. Janssen, Yoram Lanir, Corrinus C. van Donkelaar, Alice Maroudas et Dick H. van Campen. « Experimental measurement of electrical conductivity and electro-osmotic permeability of ionised porous media ». Dans Porous Media, 295–313. Berlin, Heidelberg : Springer Berlin Heidelberg, 2002. http://dx.doi.org/10.1007/978-3-662-04999-0_10.

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Ferrante, G., et P. I. Porshnev. « Quasi-Steady States of Ionised Media in Intense Laser Fields ». Dans Super-Intense Laser-Atom Physics IV, 535–46. Dordrecht : Springer Netherlands, 1996. http://dx.doi.org/10.1007/978-94-009-0261-9_50.

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Brambilla, Marco. « Plasma Electrodynamics ». Dans Kinetic Theory of Plasma Waves, 12–57. Oxford University PressOxford, 1998. http://dx.doi.org/10.1093/oso/9780198559566.003.0002.

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Abstract In principle, the phenomenological description of electromagnetic wave propagation in plasmas can be regarded as a chapter of the electrodynamics of material media. Plasmas differ from usual materials in several respects, however, which can be traced to the fact that all charge carriers are free. Hence the distinction between polarization and conduction current, which is of fundamental importance for non-ionized media, becomes irrelevant. On the other hand, the influence of the thermal motion of ions and electrons on the propagation of electromagnetic waves cannot always be neglected; as a consequence spatial dispersion, which is a rather exotic phenomenon in ordinary dielectrics or metals, plays an important role in plasmas. Finally, a magnetized plasma is anisotropic, but the resulting birefringence is of a different nature from that of typical crystals. In this chapter, therefore, we will introduce the electrodynamics of plasmas from a macroscopic, or phenomenological, point of view. We will limit ourselves to the case of linear wave propagation, although a plasma is, strictly speaking, a nonlinear medium. Nonlinear effects will be briefly considered in Chapter 11.

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Holmes-Siedle, Andrew, et Len Adams. « Polymers and other organics ». Dans Handbook of Radiation Effects, 365–84. Oxford University PressOxford, 2002. http://dx.doi.org/10.1093/oso/9780198507338.003.0010.

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Abstract Organic compounds are sensitive to radiation by virtue of the irreversible chemical processes which take place when covalent bonds, in this case mainly C-C, C-O, O-H and C-H bonds, are excited or ionized by irradiation. Frequently, the bonds are ruptured and the reactive fragments then form new compounds, a process known as radiolysis. We have not met this process in our discussion of electronic devices and optics because the inorganic materials which largely make up such devices do not undergo decomposition in this way. The exceptions are radiolytic hydrogen in some Metal-Oxide-Semiconductor structures and radiolytic halogen in some halide salts. Organics in the form of plastics now play an indispensable role in conventional product engineering, examples being moulded structures, packets, fibre-reinforced boards, insulating sheathing, insulating and hydraulic oils, and so on. In more advanced engineering, organics, again mainly polymeric, are also extremely diverse, examples being photoresists, protective, encapsulating and passivating layers, inert binders for pigments and photographic media, active media for sensing light, force or temperature and in the millennium some active electronic switches and light emitters. Further, there is a huge volume and variety of non-polymeric, often finely-divided organic solid which come into our lives as foods, drugs, papers, dyes, explosives, and myriad natural products. Finally, organic liquids play a part in most of the above fields, including drinks, solvents, synthetic intermediates, lubricants, and insulating oils. An unexpected proportion of this diverse list may be exposed to radiation in industrial processes. For example, plant material may be used as a filler in radiation reprocessing, foods are irradiated as a preservation measure, and a toxic material such as dioxin vapour may be irradiated to destroy it. The diversity of the above list of materials makes it clear that, while all are likely to have some reactions in common (e.g. generation of hydrogen), it is a large task to list and categorize accurately the changes in physical parameters or to develop broad prediction schemes in the same way as for silicon devices.

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Chipperfield, John R. « Chemistry in non-aqueous solvents ». Dans Non-Aqueous Solvents. Oxford University Press, 1999. http://dx.doi.org/10.1093/hesc/9780198502593.003.0002.

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This chapter explains how non-aqueous solvents are used as media for carrying out reactions and as carriers to deliver solutes to their point of use. It looks at the various classes of reaction in which the solvent can participate, such as acid-base reactions that can take place in the gas phase. It also talks about the acid-base reactions in water, which have been extensively studied to provide an insight into the nature of acidity. The chapter discusses acid as a substance that either alone or through reaction with the solvent gives the caution formed in the self-ionization of the solvent. It mentions solvents, such as hexane, acetone, acetonitrile, DMSO, and liquid sulfur dioxide, which do not self-ionize.

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Kumar, Gaurav, Apurbba Kumar Sharma et Mukund Kumar. « Microwave Drilling of Polymer Based Composite : Challenges and Opportunities ». Dans Manufacturing and Processing of Advanced Materials, 90–101. BENTHAM SCIENCE PUBLISHERS, 2023. http://dx.doi.org/10.2174/9789815136715123010012.

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Microwave drilling is an advanced machining process in which electromagnetic energy converted into thermal energy with the help of a metallic concentrator is used to create the desired shape in the work material. High strength electric field developed around the tooltip ionizes the dielectric media around the tooltip and results in plasma formation. High-temperature plasma ablates the material just beneath the tool tip to create the desired hole in the workpiece. In the present research work, micro-hole drilling on thermoset and thermoplastic-based composites using microwave energy in the air and transformer oil has been investigated. The drilling characteristics have been investigated in terms of the heat-affected zone, and overcut; a comparison has been made in air and transformer oil. The study revealed that drilling in the presence of dielectric-like transformer oil reduces the defects like HAZ and overcut significantly. It was also observed that thermal damage was more in thermoset-based composites as compared to thermoplastic-based composites.

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Actes de conférences sur le sujet "Ionized media"

Sato, Kentaro, Takafumi Kuroda, Haruka Ohno, Kyohei Suzuki et Akira Suda. « Non-collinear high-order harmonic generation in ionized media ». Dans 2015 11th Conference on Lasers and Electro-Optics Pacific Rim (CLEO-PR). IEEE, 2015. http://dx.doi.org/10.1109/cleopr.2015.7375826.

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Sezemsky, Petr, Marcin Koba, Robert Bogdanowicz, Vitezslav Stranak et Mateusz Śmietana. « Direct Monitoring of Plasma with Lossy-Mode Resonance Probe ». Dans Optical Fiber Sensors. Washington, D.C. : Optica Publishing Group, 2022. http://dx.doi.org/10.1364/ofs.2022.th2.5.

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A lossy-mode resonance optical fiber sensor operating as an electro-optical transducer for analysis of ionized gas media, such as plasma, is introduced. Comparison of the sensor performance with an electrical Langmuir probe is discussed.

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Merts, A. L. « Application of XUV Free-Electron Radiation for Opacities of Highly Ionized Atoms ». Dans Free-Electron Laser Applications in the Ultraviolet. Washington, D.C. : Optica Publishing Group, 1988. http://dx.doi.org/10.1364/fel.1988.sa2.

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The primary requirement for transport of radiation through a material media is to have estimates for the absorption coefficients at the appropriate wavelengths. For many applications, the appropriate wavelengths are determined by the temperature of the material in question. In many other cases where the source of radiation is not characterized by the local temperature, one needs a versatile source of radiation continuously covering a wavelength interval appropriate for the problem at hand.

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Ajlouni, Abdul-Wali M. S. « Deep Atomic Binding (DAB) Hypothesis : A New Approach of Fission Product Chemistry ». Dans 14th International Conference on Nuclear Engineering. ASMEDC, 2006. http://dx.doi.org/10.1115/icone14-89054.

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Former studies assumed that, after fission process occurs, the highly ionized new born atoms (20–22 positive charge), ionize the media in which they pass through before becoming stable atoms in a manner similar to 4-MeV-particles. Via ordinary chemical reactions with the surroundings, each stable atom has a probability to form chemical compound. Since there are about 35 different elemental atoms created through fission processes, a large number of chemical species were suggested to be formed. But, these suggested chemical species were not found in the environment after actual releases of FP during accidents like TMI (USA, 1979), and Chernobyl (former USSR, 1986), also the models based on these suggested reactions and species could not interpret the behavior of these actual species. It is assumed here that the ionization states of the new born atoms and the long term high temperature were not dealt with in an appropriate way and they were the reasons of former models failure. Our new approach of DEEP ATOMIC BINDING (DAB) based on the following: 1. The new born atoms which are highly ionized, 10–12 electrons associated with each nucleus, having a large probability to create bonds between them to form molecules. These bonds are at the L, or M shells, and we call it DAB. 2. The molecules stay in the reactor at high temperatures for long periods, so they undergo many stages of composition and decomposition to form giant molecules. By applying DAB approach, field data from Chernobyl, TMI and nuclear detonations could be interpreted with a wide coincidence resulted.

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Shin, Daniel D., et Gregory P. Carman. « Operating Frequency of Thin Film NiTi in Fluid Media ». Dans ASME 2001 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2001. http://dx.doi.org/10.1115/imece2001/mems-23832.

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Abstract For the present paper, the operating frequencies for thin film Nickel-Titanium (NiTi) shape memory alloy were investigated. The results thus far have shown that careful delivery of power to NiTi membrane increased the operating frequency by an order of magnitude. The method of power delivered to the membrane seemed to depend on the thermal conductivity of the fluid in contact. Stagnant air and mineral oil required shorter heating times and less power due to then-low conducting characteristics. De-ionized water on the other hand required greater power and longer heating time. Although heat dissipation to the surrounding was inevitable, it was determined that delivering large bursts of energy in a short heating time can minimize such loss. This way, more energy was used to heat the membrane rather than dissipating to the surroundings. While only 60Hz was measured using the thin film membrane, higher operating frequencies are achievable if power delivery to the membrane is carefully controlled.

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Gu, Claire, et Pochi Yeh. « Scattering due to random space-charge field in photorefractive crystals ». Dans OSA Annual Meeting. Washington, D.C. : Optica Publishing Group, 1991. http://dx.doi.org/10.1364/oam.1991.mj6.

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The fluctuation of refractive index introduced by the random space-charge field via the Pockels effect is one of the noise sources in photorefractive media. In EO crystals, including photorefractive crystals, charge particles such as ionized dopants and defects are randomly distributed. The space-charge electric field generated by these charge particles induces a fluctuation in dielectric constant (or equivalently index of refraction) from the Pockels effect. Such fluctuation exists even in the presence of hologram recording and two-wave mixing. When the crystal is illuminated by light, scattering occurs in a manner similar to that of Rayleigh scattering. This kind of scattering exists in all photorefractive crystals, where ionized dopants and/or defects are responsible for the formation of index gratings. Such scattering leads to statistical noise in photorefractive devices. In this paper, we consider the scattering from randomly distributed charge particles in photorefractive crystals. The scattering cross section is analyzed in terms of the fluctuation of refractive index induced by the random space-charge field via Pockels effect. We also discuss the noise due to scattering from these noisy index gratings. The signal to noise ratio and the minimum modulation depth for an index grating are discussed. The analysis can be extended to cover all EO media.

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Sergeev, A. M., A. V. Kim, E. V. Vanin et M. C. Downer. « Rapidly Ionized Atoms as a Tunable Source of Ultra-Short Coherent VUV Radiation ». Dans High Resolution Fourier Transform Spectroscopy. Washington, D.C. : Optica Publishing Group, 1994. http://dx.doi.org/10.1364/hrfts.1994.tub5.

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Our paper addresses the problem of nonlinear conversion of high intensity femtosecond laser pulse spectra, during the process of rapid multiphoton gas ionization. Previously, various modifications of laser spectra resulting from the nonlinear response of media have been observed in investigations of intense laser beam interactions with rarefied gases. The observed "elemental” modifications include blue shifting of the pulse frequency produced by temporal variations in the refractive index due to gas ionization [1-3], superbroadening of the focused laser pulse spectrum caused by avalanche gas ionization [4,5], and high-order optical field harmonic emission [6-9]. In investigations of the last process, the atom ionization has usually been treated as a negative effect that breaks the phase matching conditions between the fundamental and excited waves. However, in the recent paper of Corkum [10] and in our paper [11] it has been demonstrated that ionization itself is precisely the mechanism which is responsible for high-order harmonic coherent pulse generation. Hence, atoms ionized in the strong laser field constitute a. nonlinear medium which has attractive potential for producing supershort (spectrum broadening), tunable (blue-shifting), ultrashort wave (higher harmonics) radiation. The question arises: can these possibilities be exploited simultaneously to create a unique source of coherent radiation? Our paper proves theoretically this possibility and defines the relevant conditions for experimental demonstration.

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Simeonsson, Josef B., Randy J. Locke, Jeffrey B. Morris, Brad E. Forch et Andrzej W. Miziolek. « Spectroscopic Studies of Laser-Generated Microplasmas ». Dans Laser Applications to Chemical Analysis. Washington, D.C. : Optica Publishing Group, 1992. http://dx.doi.org/10.1364/laca.1992.wc6.

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The ability of pulsed lasers to cause breakdown in gaseous media has been observed and studied nearly as long as lasers have been available. A breakdown microplasma is initiated at the focus of a laser when atomic and molecular species are ionized following the resonant and/or nonresonant absorption of laser radiation. Free electrons that are initially produced absorb laser radiation through a process known as inverse bremsstrahlung. After absorbing enough energy, the electrons collide with other species causing them to ionize and the process is repeated until a cascade ionization occurs. When the electron density is sufficiently high, the microplasma becomes opaque to the laser radiation which results in a very rapid heating of the plasma for the duration of the laser pulse. Temperatures in laser produced microplasmas have been estimated as high as 104 to 105 K with electron densities on the order of 1015 to 1019 per cm3. Studies of microplasmas produced using laser radiation from the ultraviolet to the far infra-red have shown that the intensity required for optical breakdown to occur (the breakdown threshold) generally decreases as the laser wavelength decreases (1-5). Similarly, the "rise time" of the microplasma, or the time it takes for the plasma emission intensity to reach a maximum value, has been found to decrease as the laser wavelength decreases.

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Shaffer, James, Saeid Zare et Omid Askari. « Modeling Discharge Spark Ignition Using Zero Dimension Thermodynamic Model and Experimental Power Measurements at Various Pressures ». Dans ASME 2021 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/imece2021-73235.

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Abstract Laminar burning speed calculation at high pressures is challenging because of unstable surface conditions at large flame kernel diameters. It is therefore desired to take these measurements at small dimensions (i.e., during and immediately after the ignition discharge process) when the flame kernel is smooth and stable. Taking accurate measurements at these sizes is challenging because the kernel growth rate does not only depend on the chemical reaction but also on other phenomena such as energy discharge, as well as radiative and conductive energy losses. The effect of these events has not been adequately assessed, due to the generation of ionized gas (i.e., plasma). In order to better understand the effect of the ignition plasma in this work, spark ignition in air for 1–5 atm of pressure is studied. Understanding the ignition event and modeling its behavior is important to capture accurate combustion measurements at pressures pertinent to the advanced high-pressure engines and technologies. The relationship between the electrical energy supplied to the spark and the thermal energy dissipated within a gas mixture has been studied. This work relates the electrical discharge power to the volume of the ignition kernel measured via schlieren imagery. Voltage and current data are also captured as the input to a thermodynamic model which is used to predict the volume versus time data of the spark event. The model, which utilizes measured electrical power, thermodynamic properties of ionized air, and radiation losses in air show agreement with the experimental kernel measurements in terms of overall shape of the volume data within the measured kernel uncertainty. With these results and further experimental validation the present model is considered to represent the relationship between the electrical spark power and the measured ignition kernel volume. Future work will be done to determine inaccuracies present in the arc discharge regime as well as the effectiveness of the model in combustible media.

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Pop, N., E. Djuissi, J. Z. Mezei et I. F. Schneider. « Reactive collisions between electrons and molecular cations. Applications in astrophysics and cold plasmas modelling ». Dans International Meeting on Data for Atomic and Molecular Processes in Plasmas : Advances in Standards and Modelling, 23–24. Belgrade, Serbia : Institute of Physics Belgrade, 2024. https://doi.org/10.69646/aob241104.

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Dissociative recombination (DR) of molecular cations with electrons is a major elementary process in the kinetics and in the energy balance of astrophysical ionized media (supernovae, interstellar molecular clouds, planetary ionospheres), fusion plasmas in the divertor region, hypersonic entry plasmas and in many other cold media of technological interest.Using Multichannel Quantum Defect Theory (MQDT), cross sections and Maxwell rate coefficients have been obtained for DR and ro-vibrational transition (RVT) as ro-vibrational excitation (RVE, inelastic collisions), ro-vibrational de- excitation (RVdE, super-elastic collisions) of H2+ and HD+ for numerous ro- vibrational states of the ion. The computational results obtained are in reasonable agreement with experimental data (Motapon et al., 2014; Epée et al., 2016).A complete set of vibrationally resolved rate coefficients for BeH+ cation and its isotopomers: BeD+, BeT+ reactive collisions with electrons below the ion dissociation threshold has been provided (Niyonzima et al., 2017; Niyonzima et al., 2018; Pop et al., 2021).The resulting data are useful for the modeling of the kinetics of the Early Universe and of the magnetic-confinement-fusion-edge plasma.Our previous studies of DR, vibrational excitation/de-excitation and dissociative excitation (DE) of the BeH+ ion, based on the MQDT, are extended to collision energies above the dissociation threshold (up to 12 eV) by increasing the number of dissociative states for all molecular symmetries (Djuissi et al., 2024). - FULL TEXT available in PDF.

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