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Artykuły w czasopismach na temat "Bronze type compound"
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Ma, Hongqiang, Kun Lin, Longlong Fan, Yangchun Rong, Jun Chen, Jinxia Deng, Laijun Liu, Shogo Kawaguchi, Kenichi Kato i Xianran Xing. "Structure and oxide ion conductivity in tetragonal tungsten bronze BaBiNb5O15". RSC Advances 5, nr 88 (2015): 71890–95. http://dx.doi.org/10.1039/c5ra10635d.
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Tetragonal tungsten bronze compound, BaBiNb5O15, is found to be a new type of oxide ion conductor with a total electrical conductivity of 3 × 10−4 S cm−1 at 600 °C.
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Jouffret, Laurent, Jerome Lhoste, Annie Hemon-Ribaud, Marc Leblanc i Vincent Maisonneuve. "(H3O)2NaAl3F12, isostructural with A 2NaAl3F12 (A = K+, Rb+, Cs+) fluorides having HTB-type sheets". Acta Crystallographica Section C Structural Chemistry 70, nr 5 (30.04.2014): 512–16. http://dx.doi.org/10.1107/s205322961400919x.
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The title compound, (H3O)2NaAl3F12 [dihydronium sodium trialuminum(III) dodecafluoride], was obtained by solvothermal synthesis from the reaction of aluminium hydroxide, sodium hydroxide, 1,2,4-triazole and aqueous HF in ethanol at 463 K for 48 h. The structure consists of AlF6 octahedra organized in [AlF4 −] n HTB-type sheets (HTB is hexagonal tungsten bronze) separated by H3O+ and Na+ cations.
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Guyot, H., H. Balaska i J. Marcus. "Electronic structure of the Peierls compound K0.9Mo6O17". Journal de Physique IV 12, nr 9 (listopad 2002): 95–96. http://dx.doi.org/10.1051/jp4:20020368.
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The purple potassium bronze of molybdenum is a quasi two-dimensional compound showing a Peierls transition at 120 K. This transition is driven by the properties of the conduction electrons. In order to confirm the nature of the transition, we have investigated at room temperature the electronic structure of this oxide and established its band structure in the ΓK direction. A weak conduction band is detected, well separated from the valence band by a depleted region. The valence band shows several structures attributed to oxygen-type states and to the K3p shallow core level. The structures of the conduction band reveal the presence of at least two bands crossing the Fermi level, in relatively good agreement with the calculated band structure.
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Roussel, P., G. Mather, B. Domengès, D. Groult i P. Labbé. "Structural Investigation of P4W24O80: A New Monophosphate Tungsten Bronze". Acta Crystallographica Section B Structural Science 54, nr 4 (1.08.1998): 365–75. http://dx.doi.org/10.1107/s0108768197013785.
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The crystallographic study of the tungsten phosphate bronze P4W24O80 was performed from three-dimensional single-crystal X-ray diffraction data and electron microscopy. This compound crystallizes in the orthorhombic system with unit-cell dimensions a = 5.312 (1), b = 6.5557 (8), c = 42.196 (8) Å and space group P212121. The crystal structure was solved by direct methods and Fourier techniques, and refined to the reliability factor R = 0.0284 (wR = 0.0272). Its determination confirms that it belongs to the monophosphate tungsten bronze family of the general formula (PO2)4(WO3)2m with the value m = 12. Large empty cages surrounded by 18 O atoms are built up of eight WO6 octahedra and four PO4 tetrahedra sharing corners. They are located between two WO3-type slabs forming pentagonal-shaped tunnels running in the a direction. Electron microscopy investigations confirm that the studied crystal does not imply modulation phenomena when other crystals of the same composition exhibit satellite reflections with a modulation vector q* involving a doubling of a. The observations also reveal the existence of a monoclinic form of the m = 12 compound, which is a regular intergrowth of m = 11 and m = 13 members in a similar way to the m = 5 member of the series where the same feature has already been observed. On each edge of a WO3-type slab, a large variation (from 1.73 to 2.09 Å) of the six W—O distances within the WO6 octahedron is noted, which yields an oxidation state of W near 6, whereas for the WO6 octahedra located in the middle part of the slab the six W—O distances are gathered about their mean value (1.92 Å), which involves a more important electronic delocalization. The thermal motion of the W atoms is described. The absolute structural configuration is tested on the basis of some calculated structure factors, which are more sensitive to the x, y, z → −x, −y, −z change of atomic positions.
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SAHOO, P. S., S. K. PATRI, R. N. P. CHOUDHARY i A. PANIGRAHI. "STRUCTURAL AND DIELECTRIC PROPERTIES OF Ba2Sr3SmTi3V7O30". Modern Physics Letters B 22, nr 30 (10.12.2008): 2999–3005. http://dx.doi.org/10.1142/s0217984908017448.
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The polycrystalline sample of Ba 2 Sr 3 SmTi 3 V 7 O 30, a member of the tungsten bronze structural family, was prepared by a high-temperature solid-state reaction technique. Preliminary X-ray diffraction analysis suggests the formation of a single-phase compound with orthorhombic structure. Detailed studies of the dielectric constant and tangent loss as a function of frequency (100 Hz to 1 MHz) and temperature (32°–500°C) show that this compound has a diffused-type of ferroelectric phase transition at 230°C. Study of the surface morphology by SEM showed uniform grain distribution on the surface of the sample with less porosity. The activation energy, calculated from the plot of temperature dependence of AC conductivity, of the compound was found to be 0.11 eV and 0.14 eV at 500 kHz and 1 MHz respectively. The nature of the variation of conductivity and value of activation energy suggest that the conduction process is of a mixed-type.
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Babaryk, A. A., I. V. Odynets, S. Khainakov i N. S. Slobodyanik. "Synthesis and X-ray powder diffraction data of Ba2.64Ta11.25O30.81". Powder Diffraction 29, nr 4 (15.10.2014): 385–88. http://dx.doi.org/10.1017/s0885715614000748.
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The Ba2.64Ta11.25O30.81was prepared by conventional solid-state reaction technique as a single phase. It was found that the compound crystallizes in the tetragonal system, space group P4/mbm (No. 127) and unit-cell parameters are a = 12.508 59(8) Å, c = 3.912 81(2) Å, V = 612.218(7) Å3, and Z = 1. The crystal structure of the Ba2.64Ta11.25O30.81 phase is found to be closely related to the tetragonal tungsten bronze structure type, comprising interstitial (TaO)+ inclusions. Reference data were derived from the Rietveld analysis and reported here.
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Chebabe, Driss, Ahmed Dermaj, Hamid Erramli i Najat Hajjaji. "Corrosion inhibition of bronze alloy B66 by 4-amino-3-methyl-1,2,4-triazole-5-thione in 3 per cent NaCl solution". Anti-Corrosion Methods and Materials 61, nr 5 (26.08.2014): 281–86. http://dx.doi.org/10.1108/acmm-05-2013-1265.
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Purpose – The purpose of this study is to study corrosion inhibition of Bronze alloy B66 by 4-amino-3-methyl-1,2,4-triazole-5-thione (MTSNH) in 3 per cent NaCl solution. Archaeological bronze artefacts often are stored or displayed in uncontrolled conditions and may suffer from dangerous active corrosion processes that can lead to their destruction. The most dangerous form of archaeological bronze degradation is due to a cyclic reaction that involves copper from the pure alloy and chlorine as a pathogenic agent. A protection treatment can be used to protect them from the corrosion environment and stabilise them to avoid further degradation during exhibition or storage. Starting from its initial assessment as a corrosion inhibitor for pure copper, nowadays benzotriazole (BTA) is in widespread use for the conservation of copper-based artefacts, but unfortunately, BTA is toxic and a suspected carcinogen. The development of new and safe protection systems would offer a choice of alternative products to conservation-restoration professionals for the effective and safe stabilization and protection of metal artefacts. In this investigation, a new organic compound, namely, MTSNH, was synthesized, characterized and tested as a corrosion inhibitor for Bronze B66 (similar to archaeological bronze) in 3 per cent NaCl solution using potentiodynamic polarization studies and electrochemical impedance spectroscopy (EIS) at room temperature. It has been observed from the corrosion rate that the inhibition efficiency increased with increasing concentration of MTSNH. Potentiodynamic polarisation results revealed that the compound acted as a mixed-type inhibitor. Impedance studies indicated that protection occurs through adsorption of the inhibitor on the metal surface, with important modification to the mechanism of corrosion. Surface analysis was carried out using scanning electron microscopy scanning electron microscopy (SEM)/energy dispersive spectrometry (EDX) techniques to verify the electrochemical results. Design/methodology/approach – The inhibition efficiency of MTSNH is investigated by potentiodynamic polarization, EIS and surface analysis. Findings – The synthesized MTSNH act a good inhibitor in 3 per cent NaCl and inhibition efficiency increases with inhibitor concentration. Polarisation curves showed that the inhibitor is mixed. The EIS measurements showed that the inhibitor acted throughout the formation of film at the bronze surface. The surface analysis confirms this result. Originality/value – The adsorption of the MTSNH on the metal surface can markedly change the corrosion resisting property of metal. Therefore, the study of the relation between adsorption and corrosion inhibiting is of a great importance.
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BEHERA, BANARJI, P. NAYAK i R. N. P. CHOUDHARY. "IMPEDANCE SPECTROSCOPY STUDY OF NaCa2Nb5O15 CERAMICS". Modern Physics Letters B 23, nr 01 (10.01.2009): 97–109. http://dx.doi.org/10.1142/s0217984909017765.
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Polycrystalline sample of NaCa 2 Nb 5 O 15 was prepared by a high-temperature solid-state reaction technique. Preliminary X-ray structural analysis exhibits the orthorhombic crystal structure of the compound at room temperature. Detailed dielectric studies of NaCa 2 Nb 5 O 15 over a wide range of temperature (31–500°C) and frequency (102–106 Hz) did not show any dielectric anomaly (or ferroelectric phase transition) as observed in other members of the tungsten bronze structural family. However, the low loss tangent and dielectric constant increase with increasing temperature. Complex impedance and modulus plots (at different temperature and frequency) show the existence of non-Debye type of relaxation process in the compound. Complex modulus spectrum shows only grain contribution in the compound. Electric modulus analysis suggests that a possible hopping mechanism is evident for electrical transport processes in the system. Studies of AC conductivity with frequency suggest that the material obeys Jonscher's universal power law.
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Jin, Xingxing, Lijie Luo, Yongjun Chen, Jianbao Li i Chunfu Lin. "BiNb5.4O15: A new Li+-storage material with a tetragonal tungsten bronze crystal structure". Functional Materials Letters 14, nr 02 (luty 2021): 2150005. http://dx.doi.org/10.1142/s1793604721500053.
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Niobates with tungsten bronze crystal structures are regarded as prospective Li[Formula: see text]-storage anode candidates due to the rich chemistry of niobium and structural openness. However, the exploration of this type of materials is still insufficient. Here, BiNb[Formula: see text]O[Formula: see text] with a tetragonal tungsten bronze crystal structure (Cmmm space group) is explored. Abundant large-sized tunnels and a large interlayer spacing of [Formula: see text]3.97 Å are found in this open structure, enabling fast Li[Formula: see text] diffusivity (3.25 × 10[Formula: see text]/1.68 × 10[Formula: see text] cm2 ⋅ s[Formula: see text] during lithiation/delithiation). Additionally, this structure is very stable after the first lithiation process, resulting in excellent cyclability (95.4%/[Formula: see text]100% capacity retention after 100/1000 cycles at 1C/10C). BiNb[Formula: see text]O[Formula: see text] further exhibits a safe Li[Formula: see text]-storage potential ([Formula: see text]1.55 V) and a large reversible capacity (309.7 mAh ⋅ g[Formula: see text]@ 0.1C). Therefore, BiNb[Formula: see text]O[Formula: see text] can be a practical Li[Formula: see text]-stora ge anode compound for large-scale energy-storage applications.
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Islak, S., D. Kir i H. Çelik. "Investigation of the Usability of Cubic Boron Nitride Cutting Tools as an Alternative to Diamond Cutting Tools for the Aircraft Industry". Archives of Metallurgy and Materials 58, nr 4 (1.12.2013): 1119–23. http://dx.doi.org/10.2478/amm-2013-0135.
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Abstract Diamond and cubic boron nitride (cBN) cutting segments were produced using hot pressing technique for this study to be used in cutting natural stone. cBN grains were added to bronze powder, the chosen matrix, at a rate of 0%, 20%, 40%, 60%, 80%, and 100% (according to percentage by weight). Segments were produced under a pressure of 35 MPa, at a sintering temperature of 600°C, over a sintering time of 3 minutes. The cutting properties of the produced segments were determined by cutting Ankara andesite. A Scanning Electron Microscope (SEM) and an X-Ray Diffractometer (XRD) were used to analyse the microstructure, phase compound, and wear surfaces of each segment type.
Rozprawy doktorskie na temat "Bronze type compound"
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ZAWILSKI, BARTOSZ. "Mise en evidence et etude d'une nouvelle phase dans la famille des bronzes de molybdene". Université Joseph Fourier (Grenoble), 1998. http://www.theses.fr/1998GRE10210.
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Dans la physique des solides, nous pouvons rencontrer les materiaux qui possedent certaines caracteristiques beaucoup plus prononcees dans une direction plutot que dans une autre. Pour fixer les idees, nous parlerons des metaux dont la conductivite est au moins dix fois superieure suivant une direction plutot que dans les deux directions perpendiculaires. Dans les annees cinquante peirls et, independamment, frohlich etablirent la possibilite de la formation d'un etat module dans les metaux unidimensionnels encore appele onde a densite de charge (odc). L'existence de cet etat present dans les composes quasi unidimensionnels est etabli maintenant depuis un certain temps. Cependant, les proprietes basses temperature et basses frequences de cet etat restent encore relativement mal comprises. Nous etudions plus particulierement la susceptibilite electrique des bronzes bleus et rouges de molybdene (k#0#,#3moo#3 et rb#0#,#3moo#3 et k#0#,#3#3moo#3) ainsi que quelques proprietes electriques et magnetiques de ces materiaux. Pour des temperatures inferieures a la temperature de la formation de l'odc, la partie reelle de presente un maximum en fonction de la temperature. Ce maximum qui depend de la frequence de mesure presente un comportement caracteristique a des etats vitreux. D'autres anomalies sont signalees dans des bronzes bleus au tour de la temperature t = 40 k. Apres un traitement thermique, ce n'est plus une anomalie qui est observable dans les bronzes de molybdene mais une veritable transition. En effet, la resistivite des bronzes bleus et rouges de molybdene recuits ne diverge pas a basse temperature mais se stabilise donnant lieu a un plateau. Nombreux changements des proprietes visibles dans les bronzes bleus a basse temperature etant attribues au passage de l'etat semi-conducteur a l'etat isolant, c'est-a-dire a l'absence des porteurs normaux, nous avons profite de l'opportunite et cherche a comparer les bronzes bleus classiques aux bronzes bleus recuits. Ces derniers presentant un leger comportement metallique a basses temperatures, nous sommes en droit de supposer la presence des porteurs normaux meme a tres basse temperature.
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Lamire, Mohammed. "Adaptation de groupements tetraedriques xo4 aux edifices octaedriques : etude structurale des deformations de la charpente et des possibilites d'insertion cationique". Caen, 1987. http://www.theses.fr/1987CAEN2035.
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Plusieurs types structuraux ont servi de base aux investigations. Dans chaque cas, un compose nouveau a ete synthetise et sa structure etablie par diffraction rx : pwo::(5), bronze monophosphate a tunnels pentagonaux; na::(x)p::(4)w::(14)o::(50), bronze monophosphate a tunnels hexagonaux; ba::(2)p::(8)w::(32)o::(112), bronze diphosphate a tunnels hexagonaux; rb::(x)p::(8)w::(8)o::(40), bronze diphosphate a tunnels octagonaux et deux formes de mo::(4)p::(6)si::(2)o::(25), silicophosphate. La description des coordinences, les calculs de potentiels de sites et l'ecoulement de ces proprietes au sein des cages et des tunnels permettent de prevoir les possibilites d'accueil par insertion cationique
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Masbah, Hacène. "Synthese, structure et proprietes electroniques de quelques bronzes organiques de v : :(2)o::(5) colloidal". Orléans, 1987. http://www.theses.fr/1987ORLE2012.
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Latroche, Michel. "Caracterisations physico-chimiques des bronzes de titane en relation avec leur stoechiometrie". Nantes, 1988. http://www.theses.fr/1988NANT2019.
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Ces bronzes de titane de type hollandite sont des composes a vfalence mixte de formule generale a::(x)tio::(2), avec a=k, rb, cs et 0,125
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Hess, Christoph. "Propriétés de transport des bronzes oxygénés quasi-bidimensionnels à ondes de densité de charge, (PO2)4(WO3)2m(m=4 à 14)". Université Joseph Fourier (Grenoble), 1997. http://www.theses.fr/1997GRE10117.
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Nous avons etudie les proprietes de transport des bronzes quasi-bidimensionnels (po#2)#4(wo#3)#2#m (m=4 a 14). Ces composes subissent des transitions de peierls vers un etat a onde de densite de charge (odc) constituee d'une modulation de la densite electronique couplee a une distorsion periodique du reseau. Le parametre m est associe a l'epaisseur des feuillets conducteurs wo#6. Avec un nombre d'electrons de conduction constant par maille primitive, on peut etudier l'influence de la variation de la densite electronique et du caractere bidimensionnel sur les instabilites de peierls. Les mesures de magnetotransport dans les composes m=4 et m=6 ont ete interpretees a l'aide d'un modele a deux bandes indiquant que la surface de fermi (sf) dans l'etat odc est plus petite dans le compose m=6 que dans m=4. La destruction de la sf semble etre plus complete dans m=6 probablement par suite d'un caractere bidimensionnel plus accentue. Nous avons caracterise le compose m=5 par des mesures de proprietes de transport. Des oscillations quantiques de grande amplitude ont ete observees a basse temperature (t0. 3k) et sous fort champ magnetique (b27t). Leur analyse indique que la sf dans l'etat odc est quasicylindrique d'une taille superieure a celle des composes m=4 et 6. L'apparition de nouvelles frequences d'oscillation sous fort champ (b>18t) pourrait etre liee a un effet de rupture magnetique. Des etudes sur le compose m=7 ont conduit a la mise en evidence d'un etat supraconducteur a t#c=0. 3k. Le comportement galvanomagnetique de m=7 et m=8 a ete interprete dans le cadre d'un modele d'interferences quantiques, associe un desordre cristallin important dans la plupart des echantillons a grand m. Nous anvons compare les proprietes physiques a travers la serie : l'augmentation considerable des temperatures de transition de peierls et de la resistivite electrique en fonction de m a ete attribuee a un renforcement des correlations electroniques et du couplage electron-phonon.
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Rezrazi, El Mustafa. "Obtention par voie électrochimique et étude de quelques propriétés électrochromes de l'oxyde de tungstène WO3". Besançon, 1987. http://www.theses.fr/1987BESA2004.
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Preparation des couches electrochromes de wo::(3) par oxydation anodique sous courant pulse. Caracteristiques electrooptiques. Proprietes thermodynamiques des bronzes h::(x)wo::(3) et li::(x)wo::(3) responsables du phenomene coloration-decoloration
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Rötger, Antonia. "Etude par magnétotransport de l'état d'onde de densité de charge dans les bronzes oxygénés quasi-bidimensionnels KMo6O17 et (PO2)4(WO3)2m". Grenoble 1, 1993. http://www.theses.fr/1993GRE10036.
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Nous avons etudie la magnetoresistance des bronzes oxygenes de metaux de transition, le bronze violet kmo#6o#1#7 et les composes m=4, 6, 7 de la famille (po#2)#4(wo#3)#2#m. Ces composes ont des proprietes quasi-bidimensionnelles. Ils subissent des transitions de peierls a une temperature t#p. La magnetoresistance de kmo#6o#1#7 a ete mesuree a des temperatures comprises entre 1. 8 k et 300 k en champ magnetique jusqu'a 37 t. Des oscillations quantiques ont ete observees. Base sur le concept du nesting cache, nous proposons un modele de la surface de fermi dans l'etat d'onde de densite de charge. Elle serait constituee de petites poches lesquelles seraient a l'origine de la magnetoresistance elevee au-dessous de t#p. La temperature de peierls, observee par des mesures de resistivite electrique sous pression hydrostatique, augmente avec la pression. La compressibilite des parametres du reseau est anisotrope. La resistivite et la magnetoresistivite ont ete etudiees a des temperatures comprises entre 4. 2 k et 300 k en champ magnetique jusqu'a 6 t dans les composes m=4, 6, 7 de la famille (po#2)#4(wo#3)#2#m. La temperature de peierls augmente avec m. La magnetoresistivite diminue, ainsi que l'anisotropie quand m augmente. Nous discutons ce comportement en considerant le caractere de basse dimensionnalite, la densite de porteurs et la densite de defauts cristallins
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Le, Touze Christophe. "Etude des propriétés associées aux ondes de densité de charge dans les bronzes oxygénés quasi-bidimensionnels (PO2)4(WO3)2m". Université Joseph Fourier (Grenoble), 1996. http://www.theses.fr/1996GRE10183.
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Nous avons etudie les proprietes associees aux ondes de densite de charge dans les bronzes quasi-bidimensionnels (po#2)#4(wo#3)#2#m (m=4, 5, 6, 7, 10, 11 et 12). Ces composes subissent des transitions de peierls a des temperatures t#p vers un etat d'onde de densite de charge caracterise par une distorsion periodique de reseau couplee a une modulation de la densite electronique. La chaleur specifique a ete mesuree pour les composes 4m entre 1,7k et 300k. Nous avons obtenu des termes lineaires en temperature anormalement eleves et qui augmentent avec m. Les temperatures de debye se situent autour de 250k et diminuent lorsque m augmente. Ce comportement pourrait etre du a la diminution de la liaison metallique ou (et) a l'augmentation du caractere bidimensionnel quand le parametre m croit. Des oscillations quantiques shubnikov-de haas et de haas-van alphen ont ete observees dans les composes m=4 et m=6 lors de mesures de magnetoresistance (m=4 et m=6) et de couple magnetique (m=6) effectuees a tres basse temperature et sous fort champ magnetique. Nous avons attribue ces phenomenes a l'existence de petites poches cylindriques subsistant sur la surface de fermi dans l'etat onde de densite de charge, plus petites pour le compose m=6 que pour le compose m=4: la surface de fermi est plus detruite dans le compose m=6 que dans le compose m=4. Le caractere de basse dimensionnalite pourrait donc augmenter avec m. Enfin, nous avons mesure la resistivite electrique des composes 10m2 en fonction de la temperature entre 4k et 800k. Cette etude nous a permis de differencier les composes a petit m des composes a grand m: contrairement aux premiers, dans le domaine des basses temperatures, les seconds ont une resistivite qui decroit a temperature croissante. Nous avons attribue l'augmentation en fonction de m de la resistivite a 300k (p(300k)) et du rapport de resistivite p(300k)/p(4k) a l'augmentation des interactions electrons-electrons via la diminution du nombre moyen d'electrons de conduction par atome de tungstene. D'autre part, nous pensons que l'absence d'anomalie tres marquee, caracteristique d'une transition de peierls, pour la plupart des composes a grand m, est due a des phenomenes de desordre empechant l'apparition d'un ordre a grande distance dans l'etat onde de densite de charge
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Boujida, Mohamed. "Contribution à l'étude des propriétés de transport de quelques oxydes métalliques et supraconducteurs de basse dimensionnalité". Grenoble 1, 1988. http://www.theses.fr/1988GRE10157.
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Les proprietes de transport (magnetoconductivite, effet hall, ondes de densite de charge, ondes de densite de spin, transitions supraconductrices) des oxydes metalliques et supraconducteurs quasi-bidimensionnels sont etudiees a basse temperature
Części książek na temat "Bronze type compound"
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Gagou, Yaovi, Yassine Amira, Nadir Aliouane, Aimad Belboukhari, Billal Allouche, Abderrahim Menny, Jean-Luc Dellis i in. "Characterization and Phase Diagram of the Tetragonal Tungsten Bronze Type Ferroelectric Compounds Pb2(1−x)GdxK1+xNb5O15 for Energy Storage Applications". W Encyclopedia of Renewable and Sustainable Materials, 401–12. Elsevier, 2020. http://dx.doi.org/10.1016/b978-0-12-803581-8.10539-9.
Pełny tekst źródłaStreszczenia konferencji na temat "Bronze type compound"
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Plekhanova, Liudmila. "SOILS OF SMALL ARCHAEOLOGICAL SETTLEMENTS IN THE STEPPE ZONE AS A RESULT OF BRONZE AGE ANTHROPOGENIC IMPACT". W GEOLINKS Conference Proceedings. Saima Consult Ltd, 2021. http://dx.doi.org/10.32008/geolinks2021/b1/v3/43.
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"The contemporary direction of natural pedogenesis/soil science is ancient anthropogenic impact and climate fluctuations changes. A large number of settlements in the river valleys are unique objects with a long history of development and modern soil cover formation. We studied the soil between the dwellings for a small settlement Zarya of the Bronze Age. The settlement was part of the economic zone of cattle breeding (horses and cows and sheep) of the large early Bronze Age fortified city Sarym-Sakla, one of the country's Proto-Iranian Cities of the Trans-Ural Plateau. The activity of ancient societies changed the terrestrial ecosystem functioning at macro and microscales. Increased heterogeneity of microrelief forms led to the diversity of soil cover. We found the unusual soil types on microelevations and microdepressions. The enrichment of the cultural layer with phosphorus compounds was revealed, and the hypothesis of the formation of a ""reverse"" ratio of chernozems-solonetzes of the soil cover of the low above-floodplain terrace as a consequence of several stages of ancient anthropogenic pressure and climatic aridization was confirmed in this area. We focused on the determination of organic carbon content, magnetic susceptibility, salt composition, cation exchange capacity, and the distribution of mobile phosphates along the soil profile as possible indicators of ancient anthropogenic influence. The degree of soil properties changes during the anthropogenic impact is commensurate with their transformation in the natural evolution of centuries and even several millennia. Past anthropogenic changes leave a mark in the history of the development of the soil cover predetermining the modern danger of the degradation phenomena. Moreover, we draw parallels in the history of ecosystems formation and outlined tasks for further research."
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Kang, Xiao, i Alan Palazzolo. "Dynamic and Thermal Analysis of Rotor Drop on Sleeve Type Catcher Bearings in Magnetic Bearing Systems". W ASME Turbo Expo 2017: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/gt2017-63662.
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The catcher bearing is a crucial part of the magnetic bearing system. It can support the rotor when the magnetic bearing is shut down or malfunctioning and limit the rotor’s position when large vibration occurs. The sleeve bearing has the advantages of a relatively large contact surface area, simple structure and an easily replaced surface. There are already many applications of the sleeve type catcher bearings in the industrial machinery supported by the magnetic bearings. Few papers though provide thorough investigations into the dynamic and thermal responses of the sleeve bearing in the role of a catcher bearing. This paper develops a coupled elastic deformation — heat transfer finite element (FEM) model of the sleeve bearing acting as a catcher bearing. The FEM model investigates the dynamic and thermal behavior when a flexible rotor drops onto the sleeve catcher bearing. The thermal load caused by the thermal expansion is also considered. The flexible rotor is composed of Timoshenko beam elements. A coulomb friction model is used to model the friction force between the rotor and the sleeve bearing surface. The contact force and 2-D temperature distribution of the sleeve bearing are obtained by numerical integration. To validate the FEM code developed by the author, firstly, both the mechanical and thermal static analysis results of the sleeve bearing model are compared with the results calculated by the commercial software, “SolidWorks Simulation”. Secondly, the transient analysis numerical results are compared with the rotor drop test results in reference 13. Additionally, this paper explores the influences of different surface lubrication conditions, different materials, such as stainless steel, bronze, and aluminum, on rotor-sleeve bearing’s dynamic and thermal behavior. This paper lays the foundation of the fatigue life calculation of the sleeve bearing and provides the guideline for the sleeve type catcher bearing design.