Bibliografie tematiche / Metallic medium

Letteratura scientifica selezionata sul tema "Metallic medium"

Autore: Grafiati

Pubblicato: 8 giugno 2024

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Articoli di riviste sul tema "Metallic medium":

POPA, OLGA, ANDREI-VLAD CIUBOTARIU, COSMIN CONSTANTIN GRIGORAȘ, ANA-MARIA ROȘU e VALENTIN ZICHIL. "STUDY REGARDING THE INFLUENCE OF CORROSIVE AGENTS ON THE SURFACE OF METALLIC MATERIAL LIKE STEEL". Journal of Engineering Studies and Research 28, n. 2 (1 settembre 2022): 92–99. http://dx.doi.org/10.29081/jesr.v28i2.010.

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Corrosion is a process that involves the action of different agents on material surfaces. Corrosive agents in corrosion field can be ambient, saline and microbiological mediums. These agents can influence the mechanical properties of metallic material like steel. The aim of this research is to present the mechanic properties of sheet steel submitted at the action of corrosive agents. The metallic samples were analyzed in order to determinate the resistance at corrosion by stress-strain curves, deformation limit curves and (Atomic Force microscopy) AFM images. Relative results are obtained in the case of saline medium corrosion, meaning that the saline medium corrosion influences the metallic sample, in proportion to the degree of salinity. Also, the AFM images and topographies of metallic surface confirm this conclusion.

Ryabov, A. V. "Medium-Carbon Free-Cutting Steel". Materials Science Forum 946 (febbraio 2019): 47–52. http://dx.doi.org/10.4028/www.scientific.net/msf.946.47.

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The paper presents theoretical and experimental studies of the formation processes of boron nitride, aluminium nitride, aluminium oxide and manganese sulphide inclusions in a free-cutting steel. Fact Sage software was used to model the behaviour of non-metallic inclusions. Formation temperatures and the amount of key inclusions in steel were calculated. Formation order of inclusions is as follows: aluminium oxide > boron nitride > manganese sulphide > aluminium nitride. The object of study was the A45AR grade steel in 1.1–1.2 kg ingots. It was melted in an induction furnace, and aluminium, nitrided ferrosilicon and ferroboron were added after deoxidation before tapping. Quality estimation included chemical composition, macro-and microstructure, the character and shape of non-metallic inclusions. The finished metal contained fine and uniformly distributed inclusions of boron nitride. Qualitative and quantitative analysis of boron nitrides distribution in metal matrix showed that they were present both as individual and complex compounds, mostly of spherical shape. The size of BN inclusions varied from 0.18 to 6.52 μm. The amount of boron added to steel did not affect the size of MnS non-metallic inclusions.

Ye, Dexin, Ling Lu, John D. Joannopoulos, Marin Soljačić e Lixin Ran. "Invisible metallic mesh". Proceedings of the National Academy of Sciences 113, n. 10 (16 febbraio 2016): 2568–72. http://dx.doi.org/10.1073/pnas.1600521113.

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A solid material possessing identical electromagnetic properties as air has yet to be found in nature. Such a medium of arbitrary shape would neither reflect nor refract light at any angle of incidence in free space. Here, we introduce nonscattering corrugated metallic wires to construct such a medium. This was accomplished by aligning the dark-state frequencies in multiple scattering channels of a single wire. Analytical solutions, full-wave simulations, and microwave measurement results on 3D printed samples show omnidirectional invisibility in any configuration. This invisible metallic mesh can improve mechanical stability, electrical conduction, and heat dissipation of a system, without disturbing the electromagnetic design. Our approach is simple, robust, and scalable to higher frequencies.

Slawska-Waniewska, A., M. Kuzminski, M. Gutowski e H. K. Lachowicz. "Nanocrystalline metallic glass-an unusual particulate medium". IEEE Transactions on Magnetics 29, n. 6 (novembre 1993): 2628–30. http://dx.doi.org/10.1109/20.280844.

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Li, Jing, Xiaofeng Gu e T. C. Hufnagel. "Medium-Range Order in Metallic Glasses Studied by Fluctuation Microscopy". Microscopy and Microanalysis 7, S2 (agosto 2001): 1260–61. http://dx.doi.org/10.1017/s1431927600032372.

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Atomic structure on the 1-2 nm scale, often referred to as “medium-range order” (MRO), is of great importance for understanding the properties of disordered materials. It is, however, difficult to adequately characterize medium-range order. Fluctuation microscopy is a newly developed TEM technique that has successfully been employed to characterize MRO in amorphous semiconductors. The predominance of highly directional covalent bonds leads naturally to the presence of MRO in amorphous semiconductors. For metallic glasses, however, the bonding is primarily metallic and nondirectional. Thus, it is not readily apparent whether MRO would exist, or whether fluctuation microscopy is a useful tool for studying the structure of metallic glasses. in this work we report the use of fluctuation microscopy to identify differing degrees of MRO in Zr-based bulk metallic glasses; the MRO depends on the alloy content and the method of TEM specimen preparation.

Miracle, Daniel B., Takeshi Egami, Katharine M. Flores e Kenneth F. Kelton. "Structural Aspects of Metallic Glasses". MRS Bulletin 32, n. 8 (agosto 2007): 629–34. http://dx.doi.org/10.1557/mrs2007.124.

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AbstractA recent structural model reconciles apparently conflicting features of randomness, short-range order, and medium-range order that coexist in metallic glasses. In this efficient cluster packing model, short-range order can be described by efficiently packed solute-centered clusters, producing more than a dozen established atomic clusters, including icosahedra. The observed preference for icosahedral short-range order in metallic glasses is consistent with the theme of efficient atomic packing and is further favored by solvent-centered clusters. Driven by solute—solute avoidance, medium-range order results from the organization in space of overlapping, percolating (via connected pathways), quasi-equivalent clusters. Cubic-like and icosahedral-like organization of these clusters are consistent with measured medium-range order. New techniques such as fluctuation electron microscopy now provide more detailed experimental studies of medium-range order for comparison with model predictions. Microscopic free volume in the efficient cluster packing model is able to represent experimental and computational results, showing free volume complexes ranging from subatomic to atomic-level sizes. Free volume connects static structural models to dynamic processes such as diffusion and deformation. New approaches dealing with “free” and “anti-free” microscopic volume and coordinated atomic motion show promise for modeling the complex dynamics of structural relaxations such as the glass transition. Future work unifying static and dynamic structural views is suggested.

Zhang, Jinmin, Vijay K. Varadan e Vasundara V. Varadan. "Acoustic scattering of metallic springs in elastic medium". Journal of the Acoustical Society of America 108, n. 5 (novembre 2000): 2574. http://dx.doi.org/10.1121/1.4743564.

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Rahmani, Babak, Amirmasood Bagheri, Amin Khavasi e Khashayar Mehrany. "Effective medium theory for graphene-covered metallic gratings". Journal of Optics 18, n. 10 (20 settembre 2016): 105005. http://dx.doi.org/10.1088/2040-8978/18/10/105005.

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Yeyati, Alfredo Levy, e Mariana Weissmann. "Effective-medium calculations for an amorphous metallic alloy". Physical Review B 38, n. 15 (15 novembre 1988): 10929–32. http://dx.doi.org/10.1103/physrevb.38.10929.

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Alonso, J. A., M. D. Glossman e M. P. Iñiguez. "Atomic structure of metallic clusters of medium size". International Journal of Modern Physics B 06, n. 23n24 (dicembre 1992): 3613–21. http://dx.doi.org/10.1142/s0217979292001687.

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We have used Density Functional Theory and the Spherically Averaged Pseudopotential (SAPS) model to study the relative stabilities of sodium clusters with. different atomic arrangements in the size range N ≤340. Starting with perfect crystalline clusters with filled atomic shells we find that small distortions of the geometry strongly enhance their stability. However in the size range studied in this work the distorted crystalline structures are not the absolute energy minima. These are, instead, non-crystalline structures obtained by energy minimization without any structural constraints. In particular, non-crystalline clusters with a number of electrons able to give filled electronic shells are the most stable clusters. The crossover between magic numbers of electronic origin (clusters with filled electronic shells) and magic numbers of atomic origin (crystalline structures with filled atomic shells) has not yet taken place in the size range studied here and should occur for larger sizes.

Più fonti

Tesi sul tema "Metallic medium":

Carsbring, Amanda. "Heat Treatment and Secondary Phase Formation in FeCrNi Medium Entropy Alloys". Thesis, KTH, Materialvetenskap, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-291251.

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The topics of high entropy alloys (HEA) and medium entropy alloys (MEA) have been heavily researched in recent years. A HEA usually consists of five or more base elements, and a MEA would have three or four base elements. These types of alloys are multi-principal element alloys (MPEA) that have been thought to have interesting properties due to their high configurational entropy, which was thought to be the reason for stabilized simple solid solution phase in the HEA. The high entropy effect contributing to stable single phase in these alloys has been discussed and has not been found to be a predicament to which MPEA that will present as single phase at lowered temperatures. Still, some of the HEA and MEA investigated have interesting properties such as high ductility and good thermal properties, as is the case for the commonly researched CoCrFeMnNi HEA and the CoCrNi MEA which are both solid solution FCC phase at lower temperatures. This master thesis aims to investigate one of the less commonly researched MEA: equimolar FeCrNi. This alloy has been studied previously, and it was found there might be a possibility of precipitation hardening the alloy. To further study this alloy system, three FeCrNi alloys in the close-to equimolar range were produced and underwent a series of aging heat treatments to study the amount of precipitated secondary phase with composition changes and different aging temperatures. The objective is to evaluate and interpret the data found in the different CALPHAD databases used in Thermo-Calc and FactSage software and make comparisons to the experimental results. This to discuss the possibilities of hardening this alloy through aging treatment. The alloys selected and produced are 33Fe33Cr33Ni, 40Fe30Cr30Ni and 45Fe30Cr25Ni, all in mol%. Through experimental investigation using x-ray diffraction (XRD) analysis, it is found that Cr-rich BCC phase is formed in all alloys after most of the aging treatments performed. The volume fraction of BCC was quantified through the reference intensity ratio (RIR) method. From quantification, the largest volume fraction BCC is found in the equimolar 33Fe33Cr33Ni alloy, and the lowest fraction BCC is shown in the 40Fe30Cr30Ni alloy. The increased volume fraction of BCC coincides with an elevated hardness in all three alloys. It is also found that out of the three equilibrium phase calculations used in this project, the ThermoCalc steel database TCHEA4 seems to give results that are in closest agreement with the experimental results. For future studies in this subject, the recommendation is to further study the mechanical properties of the FeCrNi MEA and assess possibilities for application.
Högentropilegeringar och mediumentropilegeringar har studerats närmre de senaste åren på grund av deras intressanta mekaniska egenskaper. En högentropilegering består vanligtvis av fem eller flera baselement, och en mediumentropilegering har tre eller fyra baselement. Detta skiljer dem från konventionella legeringar som i regel har ett, maximalt två, baselement. Dessa typer av multi-baslegeringar har ansetts ha intressanta egenskaper på grund av deras höga konfigurationsentropi, vilken tros vara orsaken till stabilisering av fast lösningsfas i legeringarna. Högentropieffekten som bidrar till stabil enfas i dessa legeringar har diskuterats och har emellertid inte visat sig vara tillförlitligt för att förutsäga vilka multi-baslegeringar som blir fast lösningsfas vid ett lägre temperaturintervall. Ändå har några av de undersökta legeringarna intressanta egenskaper som hög duktilitet och goda termiska egenskaper, vilket är fallet för högentropilegeringen CoCrFeMnNi och mediumentropilegeringen CoCrNi som båda är enkel FCC-fas vid lägre temperaturer. Detta examensarbete syftar till att undersöka en av de mindre omnämnda mediumentropilegeringarna: ekvimolär FeCrNi. Denna legering har studerats tidigare, och det visade sig att det kan finnas en möjlighet att utskiljningshärda legeringen. För att ytterligare studera detta legeringssystem producerades tre FeCrNi-legeringar i ett sammansättningsintervall nära ekvimolär sammansättning, som sedan genomgick en serie åldringsbehandlingar för att studera mängden utskild sekundär fas beroende på sammansättning och åldringstemperatur. Målet är att utvärdera och tolka data som finns i de olika CALPHAD-databaserna som används i beräkningsverktygen Thermo-Calc och FactSage, och därefter göra jämförelser med experimentresultaten. Detta för att diskutera möjligheterna att härda dessa legeringar med partikelutskiljning. De legeringar som valts och tillverkats är 33Fe33Cr33Ni, 40Fe30Cr30Ni och 45Fe30Cr25Ni, alla angivna i molprocent. Genom experimentella undersökningar med röntgendiffraktionsanalys hittades att BCC-fas med höga halter Cr bildats i alla legeringar efter majoriteten av åldringsbehandlingarna som utförts. Volymfraktionen av BCC kvantifierades genom beräkningar från referensintensitetsförhållande (RIR). Från kvantifiering fås den största volymfraktionen BCC i den ekvimolära 33Fe33Cr33Ni-legeringen, och den lägsta fraktionen BCC i 40Fe30Cr30Ni-legeringen. Högre volymfraktion BCC sammanfaller med en förhöjd hårdhet i alla tre legeringarna. Det visar sig också att utav de tre jämviktsfasberäkningarna som används i detta projekt så är det ThermoCalc-ståldatabasen TCFE10 som gett resultat som överensstämmer med experimentresultaten. För framtida undersökningar inom detta område rekommenderas att studera de mekaniska egenskaperna hos FeCrNi och bedöma möjligheterna för tillämpning av materialet.

Howe, Christopher J. "Medium-energy ions scattering studies of ultrathin metallic films on the face-centred cubic (111) surface". Thesis, Loughborough University, 2008. https://dspace.lboro.ac.uk/2134/35637.

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An experimental investigation of ultrathin metallic films on face centred cubic(111) surfaces using medium energy ion scattering as a primary experimental technique is reported. A suite of custom software written for data-processing, calibration and analysis has also been described. The specific experimental systems investigated are 0.25 ML to 3.89 ML of palladium on copper(111) and 0.23 ML to 3.74 ML of silver on aluminium(111). The Pd CU(111) system was shown to exhibit 42% twinning at 0.25 ML through 4.74 ML. At 0.25 ML coverage it has been shown that the Pd migrates into the top three layers of the substrate. The Pd was shown to be distributed 27% ± 3%, 67% ± 3% and 6% ± 3% in the 1st, 2nd and 3rd layers. The first and second interlayer spacings we also found to contract by 4% and expand by 4% respectively for the 0.25 ML coverage.

Vernon, Kristy C. "Strongly localised plasmons in metallic nanostructures". Thesis, Queensland University of Technology, 2008. https://eprints.qut.edu.au/19318/2/Kristy_Vernon_Citation.pdf.

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Strongly localised plasmons in metallic nano-structures offer exciting characteristics for guiding and focusing light on the nano-scale, opening the way for the development of new types of sensors, circuitry and improved resolution of optical microscopy. The work presented in this thesis focuses on two major areas of plasmonics research - nano-focusing structures and nano-sized waveguides. Nano-focusing structures focus light to an area smaller than the wavelength and will find applications in sensing, efficiently coupling light to nano-scale devices, as well as improving the resolution of near field microscopy. In the past the majority of nano-focusing structures have been nano-scale cones or tips, which are capable of focusing light to a spot of nano-scale area whilst enhancing the light field. The alternatives are triangular nano-focusing structures which have received far less attention, and only one type of triangular nano-focusing structure is known – a sharp V-groove in a metal substrate. This structure focuses light to a strip of nano-scale width, which may lead to new applications in microscopy and sensing. The difficulty with implementing the V-groove is that the structure is not robust and is quite difficult to fabricate. This thesis aims to develop new triangular nano-focusing devices which will overcome these difficulties, whilst still producing an intense light source on the nano-scale. The two proposed structures presented in this thesis are a metallic wedge submerged in uniform dielectric and a tapered metal film lying on a dielectric substrate, the latter being the easier to fabricate and the more structurally sound and robust. The investigation is performed using the approximation of continuous electrodynamics, the geometrical optics approximation and the zero-plane method. The second aim of this thesis is to investigate plasmonic waveguides and couplers for the development of nano-optical circuitry, more compact photonic devices and sensors. The research will attempt to fill the gaps in the current knowledge of the V-groove waveguide, which consists of a sharp triangular groove in a metal substrate, and the gap plasmon waveguide, which consists of a rectangular slot in a thin metal film. The majority of this work will be performed using the author’s in house finite-difference time-domain algorithm and FEMLAB as well as the effective medium method and geometric optics approximation. The V-groove may be used as either a nano-focusing or waveguiding device. As a waveguide the V-groove is one of the most promising plasmonic waveguides in the optical regime. However, there exist quite a number of gaps in the current knowledge of V-groove waveguides which this thesis will attempt to fill. In particular, the effect of rounded groove tip on plasmon propagation has been assessed for the V-groove. The investigation of rounded groove tip is important, as due to modern fabrication processes it’s not possibly to produce an infinitely sharp groove, and the existing literature has not considered the impact of this problem. The thesis will also investigate the impacts of the inclusion of dielectric filling in the groove on plasmon propagation parameters. This research will be important for optimising the propagation characteristics of the mode for certain applications, but it may also lead to easier methods of fabricating the V-groove device and prevent oxidation of the metal film. The gap plasmon waveguide is easier to fabricate than the V-groove, and is a new type of sub-wavelength waveguide which displays many advantages over other types of plasmon waveguides, including ease of fabrication, almost 100% transmission around sharp bends, sub-wavelength localisation and long propagation distances of the guided mode, etc. This waveguide may prove invaluable in the development of compact photonic devices. In the past the modes supported by this structure were not thoroughly analysed and the possibility of using this structure to develop sub-wavelength couplers for sensing and nano-optical circuits was not considered in detail. This thesis aims to resolve these issues. In conclusion, the results of this thesis will lead to a better understanding of Vgroove and gap plasmon waveguide devices for the development of nano-optical circuits, compact photonic devices and sensors. This thesis also proposes two new nano-focusing structures which are easier to fabricate than the V-groove structure and will lead to applications in sensing, coupling light efficiently into nano-scale devices and improving the resolution of near-field microscopy.

Vernon, Kristy C. "Strongly localised plasmons in metallic nanostructures". Queensland University of Technology, 2008. http://eprints.qut.edu.au/19318/.

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Zhao, Sicheng. "Interactive dynamics of fluid flow and metallic alloys solidification". Thesis, Aix-Marseille 3, 2011. http://www.theses.fr/2011AIX30010.

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Nous avons étudié les phénomènes convectifs et leur interaction dynamique avec la formation des microstructures pendant la solidification dirigée d’alliages étalliquesbinaires.La méthode post-mortem a été utilisée d’abord pour étudier la Transition olonnaire-Equiaxe pendant la solidification dirigée d’échantillons cylindriques d’Al-3,5wt%Ni non affiné sous la Technique de Rotation Accélérée de Creuset. La simulation numérique a été éffectuée et acquérie les résultats en concordance avec les manipulations.La technique in-situ a été appliquée pour comprendre l’évolution en fonction de temps des grains pendant solidification d’Al-4wt%Cu. La caractéstiques tatistiques des grains ont été discutées.La convection d’instabilité déclenchée par la poussée ou la tension superfaciale sous les gradients thermiques verticale et horizontale dans un système de double couches liquide-zone poreuse ont réspectivement étudié par analysis d’instabilité linéaire.L’inhomogénéité de la perméabilité de zone pateuse dendritique a été tenue en compte afin de comprendre son influence sur le début de convection pendant la solidification dirigée d’Al-3,5wt%Li
We studied the convective phenomena and their dynamical interaction with the formation of the microstructurs during directional solidification of binary metallic alloys.The post-mortem method was used first to study the Columnar-Equiaxed-Transition during the directional solidification of unrefined Al-3.5wt%Ni in cylindric samples under the Accelerated Crucible Rotation Technique. The numerical imulation was carried out and achieved the results in agreement with experiments.The in-situ technique was applied to understand the evolution of equiaxed grains during solidification of Al-4wt%Cu in function of time. The statistical characteristics of equiaxed grains were discussed.The buoyancy-driven and surface-tension-driven instability convection under vertical and horizontal thermal gradients in a liquid-porous double-layered system were respectively investigated through linear instability analysis.The inhomogeneity of the dendritic mush permeability was taken into account in order to understand its influence on the triggering of convection during the directional solidification of Al-3.5wt%Li

Espinoza-Camino, P., I. Macassi-Jaurequi, C. Raymundo-Ibañez e F. Dominguez. "Warehouse management model using FEFO, 5s, and chaotic storage to improve product loading times in small- and medium-sized non-metallic mining companies". Institute of Physics Publishing, 2020. http://hdl.handle.net/10757/656393.

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This article addresses one of the main problems faced by small- and medium-sized business in the non-metallic mining sector in Peru. These companies own warehouses and face the major problem of failing to deliver orders correctly and in a timely manner. This problem usually occurs when the business grows from a small- to medium-sized company in a short span of time; this situation leads to new processes within warehouses that are mostly not standardized. Besides, facilities are no longer optimal in space and the workers are not properly trained. The case study shows that the orders were not delivered on time due to factors such as lack of product identification, although the products have an expiration date and a warehouse without signaling and surrounded by traffic. To tackle this situation, a labeling process has been designed for the products, an adequate distribution technique is used in the warehouse through a newly designed warehouse layout, and a First Expired, First Out system has been implemented. Similarly, the design is accompanied by the 5s tool to provide a basis for order and continuous improvement. The results show that deliveries with delays were reduced from 38% to 10%. These results show that companies can grow rapidly and maintain quality of service through orderly management.

Lecoq, Marie. "Étude du colmatage de filtres métalliques par un aérosol liquide". Electronic Thesis or Diss., Université de Lorraine, 2023. http://www.theses.fr/2023LORR0006.

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Le confinement des installations industrielles susceptibles de contenir des matières dangereuses est assuré en grande partie par des filtres à très haute efficacité (THE) intégrés dans les réseaux de ventilation. Dans les procédés, mis en œuvre dans l'industrie nucléaire, certains scénarios accidentels peuvent conduire au dégagement de liquide sous forme de gouttelettes en suspension (aérosol liquide). Dans ce cas de figure, leur présence peut affecter les performances des filtres THE en engendrant une élévation rapide et importante de leur perte de charge pouvant conduire à une diminution notable du débit de ventilation, voire atteindre la limite de leur résistance mécanique et leur capacité à retenir les contaminants aéroportés. Pour pallier ce problème, une des solutions envisagées est l'utilisation d'un préfiltre à fibres métalliques (plus résistant mécaniquement mais moins efficace) pour protéger le filtre THE constituant le dernier niveau de filtration ou pour à minima augmenter sa durée de vie en cas de scénarios accidentels. Afin de valider cette solution, il est nécessaire d'étudier, face à un aérosol liquide, le comportement de ces préfiltres composés par un empilement de plusieurs monocouches de médias de caractéristiques différentes. Les différents médias métalliques testés ont été caractérisés, dans un premier temps, en termes d'épaisseur, de compacité et de distribution granulométrique de fibres. L'évolution de l'efficacité de collecte et de la perte de charge au cours du colmatage par un aérosol liquide DEHS a ensuite été étudiée à différentes vitesses de filtration (0,9 à 18 cm/s). On retrouve l'évolution classique décrite dans la littérature : augmentation quasi-linéaire de la perte de charge avant une croissance exponentielle et une stabilisation. Les médias multicouches présentent, cependant, une phase de stabilisation de la perte de charge plus progressive comparativement aux monocouches. Un scénario de colmatage a été proposé et un modèle simpliste d'évolution de la perte charge en fonction de la masse de liquide accumulé au sein du filtre est présenté pour les médias monocouches. Afin de figer le liquide accumulé au sein du média et permettre une visualisation par micro-tomographie X des médias partiellement ou totalement colmatés, des résines thermodurcissables ont été testées. Les premiers résultats ont mis en évidence une perte de volume des résines trop importante après séchage ce qui rend difficile l'interprétation des clichés obtenus
Industrial installations often contain hazardous materials in aerosol form. High efficiency filters (HEPA) are usually the last barrier that ensure the containment of these airborne particles. In the nuclear industry, a large amount of radioactivity is handled in liquid form, that may release, in few scenarios, liquid aerosols. These particles may affect the performance of HEPA filters with a huge increase of the pressure drop, which lead in return to a significant reduction of the ventilation flowrate. In such scenarios the pressure drop increase may exceed the filter mechanical strength and induce degradations of the media and leading to a deterioration of its capacity to retain aerosol pollutants. To overcome this problem, and to protect HEPA filter, one of the solutions is to use pre-filter (more mechanically resistant but less efficient) made up with metallic fibers. To validate this approach, it is necessary to study the behavior of these prefilters, composed of a stack of different monolayers of media. In my work, I first focused on the clogging of industrial prefilters with liquid aerosol particles. Then, for a more analytical study, I study the clogging each layer separately, in order, to model, on the future, the behavior of the assembly. The microphysical of each media (thickness, packing density, and fiber size distribution) are determined. The evolution of both filter collection efficiency and pressure drop are studied along the clogging by a submicron liquid aerosol DEHS, for different filtration velocity (0,9 à 18 cm/s). For monolayer filters, I measure pressure drops in line with the previous results found in the literature. These experiments first highlight a quasi-linear increase of the pressure drop, associate with a collection of the droplets by the fibers. Then an exponential growth is measures, that corresponds to the clogging of the pores. And finally, an abrupt stabilization is observed corresponding a liquid film formation and its continuous drainage by the airflow. However, I show a more gradual stabilization for multilayer filters. A clogging scenario is proposed, and a simplistic model is established to forecast the pressure drop as a function of the mass of liquid accumulated. To this aim, I develop a new method to freeze the liquid accumulation using resin, that where further analyze using X-ray tomography

Deng, Xiaodong. "Nondestructive evaluation of thermal sprayed coating by acoustic microscopy and Eddy current testing". Thesis, Lyon, INSA, 2014. http://www.theses.fr/2014ISAL0030/document.

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La thèse a mis en œuvre deux méthodes inverses pour l’évaluation non destructive d’un milieu multicouche anisotrope : la microscopie acoustique et les courants de Foucault. Pour la microscopie acoustique, nous avons adapté un modèle de propagation de l'onde acoustique dans un milieu multicouche, en calculant les coefficients de réflexion et de transmission d’un revêtement multicouche sur un substrat et en modélisant la réponse acoustique V(z) propre à la microscopie acoustique. Une méthode inverse utilisant l’algorithme de Levenberg-Marquardt donne accès à l’épaisseur, au module de Young et à la densité du revêtement. Pour les courants de Foucault, une méthode inverse similaire basée sur le formalisme de Tree a été mise au point, qui donne accès à l’épaisseur, à la conductivité électrique et à la perméabilité magnétique du revêtement. Après des vérifications de l’algorithme sur des matériaux massifs de référence, nous avons appliqué ces méthodes à un métal revêtu pour tuyauteries de centrale thermique : de l’acier inoxydable austénitique type 304 revêtu par pulvérisation thermique de superalliage Hastelloy C22 à base de nickel. La corrosion sèche sous l’effet des gaz chauds (air contenant du gaz SO2) amincit graduellement la paroi des tubes, ce qui peut les rendre dangereux. Il a fallu tenir compte de l’effet du grenaillage préalable à la pulvérisation, qui crée une mince couche de martensite à laquelle les courants de Foucault sont très sensibles : un modèle à trois couches substrat / martensite / revêtement a été utilisé. Nous avons caractérisé des échantillons de métal avant et après exposition à l’air avec ou sans SO2 à 650°C. Les deux méthodes d’évaluation non destructive permettent une détermination très satisfaisante de l’épaisseur de revêtement et se complètent bien. L’évaluation des caractéristiques physiques (acoustiques et électromagnétiques) met en évidence des hétérogénités du revêtement liées à son mode d’élaboration et des évolutions au cours du temps. Des pistes d’amélioration des méthodes sont proposées
In the current work, we investigate the nondestructive evaluation of a thermal sprayed coating (Hastelloy C22 Ni-based alloy) on substrate (type 304 austenitic stainless steel) using acoustic microscopy and ECT method. Two models were built for the evaluation of this kind of material: one is for acoustic V(z) measurement and the other is for swept eddy current measurement. The implementation of these two models is used for the evaluation and properties measurement of the thermal sprayed coatings, such as elastic properties, electromagnetic properties. In particular, the main achievements and results are as follows: 1. Acoustic wave propagation in an anisotropic multilayered medium was investigated. The formula for calculating the reflection and transmission coefficients of the multilayered medium on or without a substrate were derived, which is necessary for the modeling of acoustic V(z) measurement of the thermal sprayed coating on substrate. 2. A model was built for the acoustic V(z) measurement of the thermal sprayed coatings on substrate, which can deal with anisotropic multilayered media. Specifically, we used a model of multilayered coatings with graded properties on substrate to calculate the acoustic reflection coefficient of our sample. Treating the thermal sprayed coating, deposited on a 304 steel substrate, as FGMs, we evaluated the coating thickness and the Young’s modulus evolution along the depth of the coating. 3. A model was built for the swept eddy current measurement of the thermal sprayed coatings. Since before the spraying process, the surface of the substrate is usually shot-peened (SP), the coated material is considered as a three-layer medium. The coating thickness and electromagnetic properties of each of the 3 layers were determined by an effective reverse process. 4. The thermal sprayed coated material after exposure in different conditions, i.e., as-received, heat-treated in air and heat-treated in SO2 environment, and after different exposure time was evaluated by the integrity of acoustic microscopy and ECT method. The coating thickness and the electromagnetic properties of the coated material under different conditions were measured

Al, Husseny Adel Ahmed Niameh Mehdy. "Heat transfer enhancement using rotating metallic porous media". Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/heat-transfer-enhancement-using-rotating-metallic-porous-media(1a50759b-fd87-4836-b7ab-5fa0ab6d6c5d).html.

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The present research is dedicated to numerically optimise the heat transfer enhancement achieved by means of utilising rotating metallic porous media. Three systems that play a crucial role in power generation systems are examined. The first is the cooling passages used to dissipate the heat generated within the rotor conductors in electrical generators, the second is the double pipe-heat exchanger, and the last is the rotary thermal regenerator. In all of the systems under consideration, the main objective is to improve the overall performance achieved and to determine the optimum values of the parameters affecting it. Concerning the first system examined, an enhancement way is proposed through filling such rotating cooling passages either fully or partially with open-cell metal foams. A compound heat transfer enhancement is utilised in the second system through applying an axial rotation to a double-pipe heat exchanger occupied with open-cell metal foams structures. The enhancement process carried out using the third system is examined through proposing an effective and less-costly way to simulate and design rotary regenerators based on a porous medium approach. The developing three-dimensional convective fluid flow across the porous media utilised in all the systems investigated is considered laminar and incompressible. Both thermal dispersion and rotational effects, including centrifugal buoyancy and Coriolis force, are taken into account in the first and second systems, while they are neglected in the latter. The momentum equations are mathematically formulated using the generalised model with considering that fluid and solid phases are in a local thermal non-equilibrium. The governing equations are discretised based on the finite volumes method and then solved iteratively using the SIMPLE algorithm, where an in-house FORTRAN code has been developed to investigate the first system, while the other two systems have been simulated using the STAR-CCM+ CFD commercial code. Inspecting the worth of using metal foams to enhance the heat dissipated by the rotating channels reveals the potential of this proposal to outperform the turbulent flow in rotating clear channels, which confirms that this enhancement way is practically justified and efficient. Moreover, the overall system performance achieved using the compound enhancement employed in the second system is incomparable, i.e. OSP=O(102). The porous medium approach, on the other hand, has been found to be sufficient to accurately simulate the convective flow across the third system. Hence, it can be utilised as an effective and more economical alternative to design such sort of heat exchangers rather than the traditional experimental or numerical ways. The resulted data reveal that heat transfer can be improved considerably by manipulating the design factors including the operating conditions as well as the geometrical and thermal characteristics of the porous medium used. However, care must be taken to avoid unnecessary expenses resulting from potential augmentation in pressure drop.

Mansour, Yehia. "Études théorique et expérimentale de la formation des nanoparticules métalliques par ablation laser en milieu liquide. Modélisations des propriétés optiques et thermiques de l'interaction Laser-Nanoparticules". Electronic Thesis or Diss., Université de Lorraine, 2020. http://www.theses.fr/2020LORR0283.

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Les nanoparticules (NPs) de métaux nobles sont le siège d’un phénomène de résonance plasmon de surface résultant de l’oscillation collective de leurs électrons de conduction sous l’effet d’une onde électromagnétique. Dans le cas de NPs d’or et l’argent, la fréquence de résonance est située dans visible ce qui confère à ces NPs plasmoniques des propriétés optiques uniques. En particulier, la position et l’intensité de la bande de résonance plasmon peuvent varier en fonction de leur taille, leur forme (rapport d'aspect) et de l'indice du milieu hôte. Les possibilités d’applications nécessitent des échantillons purs et de distribution mono disperse. La synthèse des NPs par voie chimique permet de contrôler dans une certaine mesure la forme et la taille des NPs. Elle nécessite cependant l’utilisation d’agents stabilisants qui mènent à une contamination de surface par les résidus de synthèse. Pour limiter cet inconvénient, la technique physique d’ablation laser en milieu liquide est une alternative prometteuse qui souffre cependant d’un manque de contrôle de la forme et de la taille des NPs produites. La forme et la taille des NPs élaborées par ablation laser en milieu liquide (ALML) sont étroitement liées aux trois étapes essentielles du processus : Interaction cible/laser ; Transport de masse ; Interaction laser/NPs en suspension dans le liquide. Afin d’appréhender les mécanismes régissant chacune de ces étapes, il est nécessaire de les étudier séparément. Dans ce travail, nous nous sommes focalisés sur les mécanismes d’interaction entre le faisceau laser et les NPs en suspension dans le liquide. Suivant la densité d’énergie absorbée par les NPs en suspension, celles-ci subissent la fragmentation ou le remodelage. Par la suite nous avons étudié les mécanismes à l’origine du phénomène de la fragmentation. L’évolution de la distribution de forme des NPs lors de la fragmentation des NPs a été étudiée en développant une technique originale et quantitative de spectroscopie optique in-situ. De même, l’évolution de la fraction volumique des NPs au cours de leur élaboration par ALML par spectroscopie optique in-situ est obtenue et analysée. En parallèle aux travaux expérimentaux, nous avons développé des modèles théoriques pour la compréhension des mécanismes de formation des nanoparticules métalliques par ablation laser en un milieu liquide. Une autre étude approfondie sur la modélisation des propriétés optiques et thermiques de l'interaction Laser-Nanoparticules est discutée dans cette thèse. Un modèle thermique de Takami modifié nommé MTM (Modified Takami Model) a été également introduit. Son utilité importante a été démontrée pour l’interprétation des mécanismes de l’interaction laser-NPs
Noble metal nanoparticles (NPs) are the site of a surface plasmon resonance phenomenon resulting from the collective oscillation of their conduction electrons under the effect of an electromagnetic wave. In the case of gold and silver NPs, the resonant frequency is in the visible range, which gives these plasmonic NPs unique optical properties. In particular, the position and intensity of the plasmon resonance depend on their size, shape (aspect ratio) and the index of the host medium. The possible applications require pure samples and mono-dispersed distribution. The chemical synthesis of NPs allows the shape and size of NPs to be controlled. However, it requires the use of stabilizing agents, which lead to surface contamination by synthetic residues. To limit this disadvantage, the physical technique of laser ablation in a liquid medium is a promising alternative, which, however, suffers from a lack of control over the shape and size of the NPs produced. The shape and size of NPs produced by liquid laser ablation (ALML) are closely related to the three essential steps of the process: Target / laser interaction; Mass transport; Laser / NPs interaction suspended in the liquid. In order to understand the mechanisms governing each of these stages, it is necessary to study them separately. In this work, we focused on the mechanisms of interaction between the laser beam and the NPs suspended in the liquid. Depending on the energy density absorbed by the suspended NPs, they undergo fragmentation or remodeling. We then studied the mechanisms behind the phenomenon of fragmentation. The evolution of the shape distribution of NPs during NP fragmentation was studied by developing an original and quantitative technique of in-situ optical spectroscopy. And, the evolution of the volume fraction of NPs during their preparation by ALML by in-situ optical spectroscopy is obtained and analyzed. In parallel with the experimental work, we have developed theoretical models for understanding the mechanisms of formation of metallic nanoparticles by laser ablation in a liquid medium. A modest study on the modeling of optical and thermal properties of the Laser-Nanoparticle interaction is discussed in this thesis. A modified Takami thermal model named MTM was also presented. Its important utility has been demonstrated for mechanisms for the interpretation of the mechanisms of laser-NPs interaction

Più fonti

Libri sul tema "Metallic medium":

Murphy, Robin. Fundamentals of materia medica: Aconite napellus to Zincum metallicum. [Santa Fe, N.M: R. Murphy], 1988.

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caroline, justin. Cornell Notes Notebook: Pretty Metallic Rose Gold Cornell Note Paper Notebook. Nifty Large College Ruled Medium Lined Journal Note Taking System for School and University. Independently Published, 2020.

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Notebooks, Monogram Initi Christmas Gift. E: Cute Initial Monogram Letter e College Ruled Notebook. Nifty Girly Personalized Name Medium Lined Journal & Diary for Writing & Notes for Girls and Women - Gold Metallic Floral for Christmas. Independently Published, 2019.

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Notebooks, Monogram Initi Christmas Gift. G: Cute Initial Monogram Letter G College Ruled Notebook. Nifty Girly Personalized Name Medium Lined Journal & Diary for Writing & Notes for Girls and Women - Gold Metallic Floral for Christmas. Independently Published, 2019.

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Notebooks, Monogram Initi Christmas Gift. V: Cute Initial Monogram Letter V College Ruled Notebook. Nifty Girly Personalized Name Medium Lined Journal & Diary for Writing & Notes for Girls and Women - Gold Metallic Floral for Christmas. Independently Published, 2019.

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Capitoli di libri sul tema "Metallic medium":

Durand, J. "Magnetic Properties and Medium-Range Order in Metallic Glasses". In Glass … Current Issues, 202. Dordrecht: Springer Netherlands, 1985. http://dx.doi.org/10.1007/978-94-009-5107-5_16.

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Redfield, Andrew C., e Andrew Zangwill. "The Effective Medium Approach to the Energetics of Metallic Compounds". In Atomistic Simulation of Materials, 153–57. Boston, MA: Springer US, 1989. http://dx.doi.org/10.1007/978-1-4684-5703-2_16.

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Pethick, Fred K. "High Temperature Dust Collection Using a Unique Metallic Fiber Filter Medium in Baghouses". In Gas Cleaning at High Temperatures, 378–84. Dordrecht: Springer Netherlands, 1993. http://dx.doi.org/10.1007/978-94-011-2172-9_24.

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Yan, Xiangqiao. "Notch S-N Equation for a Low/Medium/High Cycle Fatigue of Metallic Materials". In Multiaxial Notch Fracture and Fatigue, 81–150. Boca Raton: CRC Press, 2023. http://dx.doi.org/10.1201/9781003356721-3.

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Yan, Xiangqiao. "Applicability of the Wöhler Curve Method for a Low/Medium/High Cycle Fatigue of Metallic Materials". In Multiaxial Notch Fracture and Fatigue, 19–79. Boca Raton: CRC Press, 2023. http://dx.doi.org/10.1201/9781003356721-2.

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Lagrange, P., e A. Hérold. "An Example of Crystalline Growth in a Constrained Medium : The Intercalation of Metals and Metallic Alloys into Graphite". In Chemical Reactions in Organic and Inorganic Constrained Systems, 421–28. Dordrecht: Springer Netherlands, 1986. http://dx.doi.org/10.1007/978-94-009-4582-1_31.

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Simovski, Constantin R. "Dispersion Properties of Stop-Band Structures from Thin Metallic Spirals". In Advances in Electromagnetics of Complex Media and Metamaterials, 229–44. Dordrecht: Springer Netherlands, 2002. http://dx.doi.org/10.1007/978-94-007-1067-2_13.

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Mozhayko, Anna A., e Sergey A. Manninen. "Features of Signal Processing in the Study of Defects in Metallic Mediums Using an Electromagnetic Acoustic Wave". In Springer Proceedings in Physics, 557–63. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-58868-7_61.

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Gadot, F., E. Akmansoy, T. Brillat, A. de Lustrac e J. M. Lourtioz. "Band Gap Engineering in Metallic PBG Materials at Microwave Frequencies using Composite Material and Defect Lattice". In IUTAM Symposium on Mechanical and Electromagnetic Waves in Structured Media, 257–68. Dordrecht: Springer Netherlands, 2001. http://dx.doi.org/10.1007/0-306-46955-3_20.

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Nerukh, Alexander, e Trevor Benson. "An Electromagnetic Field in a Metallic Waveguide with a Moving Medium". In Non-Stationary Electromagnetics, 317–87. Jenny Stanford Publishing, 2018. http://dx.doi.org/10.1201/9780429027734-6.

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Atti di convegni sul tema "Metallic medium":

Slawska-Waniewska, A., M. Kuzminski, M. Gutowski e H. K. Lachowicz. "Nanocrystalline Metallic Glass - An Unusual Particulate Medium". In 1993 Digests of International Magnetics Conference. IEEE, 1993. http://dx.doi.org/10.1109/intmag.1993.642183.

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Rabosh, R. V., Ya I. Kunets e Yu I. Maksymiv. "Effective Models for Metallic Inclusions in Piezoelectric Medium". In 2020 IEEE XXVth International Seminar/Workshop Direct and Inverse Problems of Electromagnetic and Acoustic Wave Theory (DIPED). IEEE, 2020. http://dx.doi.org/10.1109/diped49797.2020.9273353.

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Shu, Juping, Jian P. Zhou e Shi Z. Xu. "Organo-metallic thin film for erasable optical recording medium". In Shanghai - DL tentative, a cura di Shixun Zhou e Yongling Wang. SPIE, 1991. http://dx.doi.org/10.1117/12.47332.

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Bagci, S., e D. Celebioglu. "Light Oil Combustion With Metallic Additives in Limestone Medium". In Canadian International Petroleum Conference. Petroleum Society of Canada, 2004. http://dx.doi.org/10.2118/2004-086.

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Kosulnikov, Sergei, Dmytro Vovchuk, Igor Nefedov, Sergei Tretyakov e Constantin Simovski. "Broadband power transfer through a metallic wire medium slab". In 2016 URSI International Symposium on Electromagnetic Theory (EMTS). IEEE, 2016. http://dx.doi.org/10.1109/ursi-emts.2016.7571463.

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Freitas, Taiane A. M. G., e Ricardo M. Ribeiro. "Modalmetric Detector in an Acoustic Transmission Along Metallic Medium". In 2021 SBMO/IEEE MTT-S International Microwave and Optoelectronics Conference (IMOC). IEEE, 2021. http://dx.doi.org/10.1109/imoc53012.2021.9624930.

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Legier, J. F., M. Hochedez e M. Vindevoghel. "An Educational Tool "Plane Wave in a Metallic Bounded Medium"". In 21st European Microwave Conference, 1991. IEEE, 1991. http://dx.doi.org/10.1109/euma.1991.336339.

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Maurice, Anthony, Naima Khebacche, Isabelle Russier-Antoine, Christian Jonin, Sergey E. Skipetrov e Pierre-Francois Brevet. "Second harmonic generation from metallic nanoparticles in a random medium". In 2017 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC). IEEE, 2017. http://dx.doi.org/10.1109/cleoe-eqec.2017.8087665.

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Hao Xin e Rongguo Zhou. "Low-effective index of refraction medium using metallic wire array". In 2007 IEEE Antennas and Propagation Society International Symposium. IEEE, 2007. http://dx.doi.org/10.1109/aps.2007.4396049.

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Aymard, N., P. Fache e Bernard Paya. "NEW METALLIC TORCH DESIGN FOR INDUCTIVE COUPLED PLASMA AT MEDIUM FREQUENCY". In Progress in Plasma Processing of Materials, 1999. Connecticut: Begellhouse, 2023. http://dx.doi.org/10.1615/itppc-1998.10.

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Rapporti di organizzazioni sul tema "Metallic medium":

Clausen, Jay, Samuel Beal, Thomas Georgian, Kevin Gardner, Thomas Douglas e Ashley Mossell. Effects of milling on the metals analysis of soil samples containing metallic residues. Engineer Research and Development Center (U.S.), luglio 2021. http://dx.doi.org/10.21079/11681/41241.

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Metallic residues are distributed heterogeneously onto small-arms range soils from projectile fragmentation upon impact with a target or berm backstop. Incremental Sampling Methodology (ISM) can address the spatially heterogeneous contamination of surface soils on small-arms ranges, but representative kilogram-sized ISM subsamples are affected by the range of metallic residue particle sizes in the sample. This study compares the precision and concentrations of metals in a small-arms range soil sample processed by a puck mill, ring and puck mill, ball mill, and mortar and pestle prior to analysis. The ball mill, puck mill, and puck and ring mill produced acceptable relative standard deviations of less than 15% for the anthropogenic metals of interest (Lead (Pb), Antimony (Sb), Copper (Cu), and Zinc (Zn)), with the ball mill exhibiting the greatest precision for Pb, Cu, and Zn. Precision by mortar and pestle, without milling, was considerably higher (40% to >100%) for anthropogenic metals. Media anthropogenic metal concentrations varied by more than 40% between milling methods, with the greatest concentrations produced by the puck mill, followed by the puck and ring mill and then the ball mill. Metal concentrations were also dependent on milling time, with concentrations stabilizing for the puck mill by 300 s but still increasing for the ball mill over 20 h. Differences in metal concentrations were not directly related to the surface area of the milled sample. Overall, the tested milling methods were successful in producing reproducible data for soils containing metallic residues. However, the effects of milling type and time on concentrations require consideration in environmental investigations.