Academic literature on the topic 'Phase change dispersion'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the lists of relevant articles, books, theses, conference reports, and other scholarly sources on the topic 'Phase change dispersion.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Journal articles on the topic "Phase change dispersion"
1
Fischer, Ludger, Ernesto Mura, Geng Qiao, Poppy O’Neill, Silvan von Arx, Qi Li, and Yulong Ding. "HVDC Converter Cooling System with a Phase Change Dispersion." Fluids 6, no. 3 (March 12, 2021): 117. http://dx.doi.org/10.3390/fluids6030117.
Full textAbstract:
High voltage direct current converters require efficient cooling of thyristors via heat sinks. Currently, infrastructures use deionised water as a means of cooling the high voltage direct current converters; however, recent research has shown that other fluids have potential to offer more efficient cooling. Phase change dispersions are a new class of heat transfer fluids that employ the latent heat of phase change, thus offering isothermal cooling during melting. For cooling applications, the temperature increase during operation is thus lowered when using phase change dispersions (compared to water) and consequently, the heat sink and thyristors surface temperatures are reduced. In this investigation, a phase change dispersion with non-conductive components, high stability, high capacity and low viscosity has been developed and tested. An experimental setup of a real size heat sink has been installed and the heat transfer behaviour of both the formulated phase change dispersion and water have been investigated and a comparison has been presented. Using water as the heat transfer fluid, the temperature increase from inlet to outlet of the heat sink was 4 K and with the formulated phase change dispersion (at the same mass flow rate and heat input) the temperature increase was 2 K. The phase change dispersion caused a 50% reduction in the heat sink surface temperature. Furthermore, the global heat transfer coefficients obtained for the phase change dispersion were found to be independent of the heating input applied, unlike the trend found for water, additionally, the global heat transfer coefficients were found to be similar to those obtained for water at the same mass flow rates and reached a maximum value of 6100 W m2 K−1. Despite this, the pressure drops and viscosities obtained for the phase change dispersion were higher than for water. Overall, the current investigation demonstrates the ability of using a phase change dispersion as a cooling fluid for the cooling of electronic components, which thus far is limited to using air and water cooling and cannot reach the cooling capacity achieved by phase change dispersions.
2
Fischer, Ludger, Ernesto Mura, Poppy O’Neill, Silvan von Arx, Jörg Worlitschek, Geng Qiao, Qi Li, and Yulong Ding. "Heat Transfer Performance Potential with a High-Temperature Phase Change Dispersion." Energies 14, no. 16 (August 11, 2021): 4899. http://dx.doi.org/10.3390/en14164899.
Full textAbstract:
Phase change dispersions are useful for isothermal cooling applications. As a result of the phase changes that occur in PCDs, they are expected to have greater storage capacities than those of single-phase heat transfer fluids. However, for appropriate heat exchanger dimensions and geometries for use in phase change dispersions, knowledge about the convective heat transfer coefficients of phase change dispersions is necessary. A test unit for measuring the local heat transfer coefficients and Nusselt numbers of PCDs was created. The boundary condition of constant heat flux was chosen for testing, and the experimental heat transfer coefficients and Nusselt numbers for the investigated phase change dispersion were established. Different experimental parameters, such as the electrical wall heat input, Reynolds number, and mass flow rate, were varied during testing, and the results were compared to those of water tests. It was found that, due to the tendency of low-temperature increases in phase change dispersions, the driving temperature difference is greater than that of water. In addition, larger heat storage capacities were obtained for phase change dispersions than for water. Through this experimentation, it was acknowledged that future investigation into the optimised operating conditions must be performed.
3
Fischer, Ludger J., Somayajulu Dhulipala, and Kripa K. Varanasi. "Phase Change Dispersion Made by Condensation–Emulsification." ACS Omega 6, no. 50 (December 6, 2021): 34580–95. http://dx.doi.org/10.1021/acsomega.1c04940.
Full text
4
Andreev, A. A., N. A. Belov, V. V. Makarova, G. A. Shandryuk, D. V. Bryankin, D. S. Pashkevich, and A. Yu Alentiev. "Dispersion of Polyethylene Glycol in Perfluorodecalin for Liquid Phase Fluorination." Eurasian Chemico-Technological Journal 24, no. 3 (October 10, 2022): 259–65. http://dx.doi.org/10.18321/ectj1439.
Full textAbstract:
This work aims to obtain the dispersions based on polyethylene glycols (PEGs) of various molecular masses (MM) and perfluorodecalin (PFD) for subsequent direct fluorination. The solubility of the components was estimated using laser interferometry and differential scanning calorimetry, and it was shown that PEGs with different MM are not highly compatible with PFD. The dispersions were prepared during sonication. Gel permeation chromatography (GPC) analysis indicated that MMs almost did not change in this process. While the sonication of PEG-PFD, there is a formation of dispersion with the particle sizes distribution in a range of 0.4‒2 μm depending on the MM of PEG. The dispersion is metastable for several hours, even though its stability was significantly affected by additional bubbling with the gas flow. Moreover, the dispersions with a solid PEG phase (MM > 600 Da) were subjected to a smaller change compared to a liquid one (MM < 600 Da). The results of this research shed light on the applicability of the ultrasonic preparation of PEGs in PFD for liquid-phase fluorination with obtaining perfluorinated polyether of target MM.
5
Fischer, L. J., S. von Arx, U. Wechsler, S. Züst, and J. Worlitschek. "Phase change dispersion properties, modeling apparent heat capacity." International Journal of Refrigeration 74 (February 2017): 240–53. http://dx.doi.org/10.1016/j.ijrefrig.2016.10.008.
Full text
6
Fasano, Antonio, and Roberto Gianni. "Phase change of a two-component liquid–liquid dispersion." Nonlinear Analysis: Real World Applications 1, no. 4 (December 2000): 435–48. http://dx.doi.org/10.1016/s0362-546x(99)00103-0.
Full text
7
Wang, Hushan, Huabao Cao, Yishan Wang, Wei Zhao, and Yuxi Fu. "Suppression of Pulse Intensity Dependent Dispersion during Nonlinear Spectral Broadening with Intermediate Compression for Passive CEP Stable Pulse Generation." Photonics 9, no. 10 (October 12, 2022): 761. http://dx.doi.org/10.3390/photonics9100761.
Full textAbstract:
The intensity fluctuation induced spectral phase-change of the laser pulse during nonlinear spectral broadening is theoretically investigated. The oscillation of the phase-change curves at the central part of the spectra is explained by the two-wave interference model, while the bending of the phase-change curves at the wings is considered to originate from the intensity dependent dispersion caused by the self-steepening (SST) effect. Both of them can degrade carrier envelop phase (CEP) stability after an intra-pulse difference frequency generation (IP-DFG) setup. We propose an effective approach to suppress the intensity dependent dispersion with intermediate compression. Verified by numerically simulations, well-phased spectral components at the wings can be obtained, which is highly beneficial for CEP stable pulse generation with noisy input.
8
Tanaka, Chigusa, Jianqiang Mai, Masamichi Nakagawa, Shuzo Oshima, Ryuichiro Yamane, and Myeng-Kwan Park. "New Actuator Utilizing Phase Change of Functional Fluids." International Journal of Modern Physics B 13, no. 14n16 (June 30, 1999): 2183–88. http://dx.doi.org/10.1142/s0217979299002290.
Full textAbstract:
This paper proposes a new actuator utilizing the phase change of the ER fluid. The dielectric coolant was used for the solvent and silica gel particles for the dispersion particle. The dynamic characteristics of the actuator was determined for the several patterns of the working conditions.
9
Deng, Y. F., Z. Li, J. H. Peng, C. Liu, and X. S. Miao. "Thermal dispersion and secondary crystallization of phase change memory cells." Applied Physics Letters 103, no. 23 (December 2, 2013): 233501. http://dx.doi.org/10.1063/1.4831966.
Full text
10
Fischer, Ludger, Simon Maranda, Anastasia Stamatiou, Silvan von Arx, and Jörg Worlitschek. "Experimental investigation on heat transfer with a Phase Change Dispersion." Applied Thermal Engineering 147 (January 2019): 61–73. http://dx.doi.org/10.1016/j.applthermaleng.2018.10.056.
Full textDissertations / Theses on the topic "Phase change dispersion"
1
O'Neill, Poppy. "Phase change dispersions as high performance heat transfer fluids." Electronic Thesis or Diss., Lyon, INSA, 2022. http://www.theses.fr/2022ISAL0073.
Full textAbstract:
Cette thèse porte sur le transfert de chaleur, le transport et le comportement rhéologique de nouveaux fluides à deux phases, appelés dispersions à changement de phase. Les dispersions à changement de phase consistent en un matériau à changement de phase dispersé dans une phase continue à l'aide de surfactants. La procédure de formulation optimale pour les dispersions à changement de phase avec des stabilités élevées, de faibles degrés de surfusion et des capacités de chaleur spécifiques apparentes élevées est discutée et une approche innovante dans le réglage fin des propriétés thermophysiques des dispersions à changement de phase avec l'utilisation de cosurfactants est définie. Deux des formulations développées ont ensuite été choisies pour une comparaison du transfert de chaleur et du comportement rhéologique afin d'observer l'effet des tensioactifs sur les propriétés de transport et de transfert de chaleur pendant le chauffage. Cette comparaison a été réalisée à l'aide d'un banc d'essai pour mesurer les températures du fluide en vrac et de la paroi interne des dispersions à changement de phase s'écoulant dans un tube cylindrique dans des conditions de flux thermique constant. Le transfert de chaleur de cristallisation et le comportement rhéologique d'une dispersion à changement de phase ont également été examinés par le calcul des bilans thermiques dans un conduit rectangulaire. Pendant la fusion et la cristallisation, un phénomène intéressant a été découvert, à savoir que la transition du laminaire au turbulent avec les dispersions à changement de phase était beaucoup plus faible que celle prédite pour les fluides newtoniens. Par régression des résultats expérimentaux, des corrélations pour les nombres de Nusselt moyens pour l'écoulement laminaire et turbulent sont présentées, en utilisant un nombre de Reynolds modifié et un facteur de correction du nombre de Prandtl. Un modèle numérique pour l'étude du comportement thermique d'une dispersion à changement de phase pendant son refroidissement dans un écoulement laminaire à travers un conduit rectangulaire a été développé et est basé sur l'approche monofluide quasi-homogène. L'évolution des valeurs expérimentales et théoriques montre un bon accord et le modèle prédit de manière satisfaisante le comportement, avec des variations inférieures à 5%This thesis focuses on the heat transfer, transport, and rheological behaviour of novel two-phase fluids, named phase change dispersions. Phase change dispersions consist of phase change material dispersed into a continuous phase with the aid of surfactants. The optimal formulation procedure for phase change dispersions with high stabilities, low supercooling degrees and high apparent specific heat capacities is discussed and an innovative approach in fine-tuning the thermophysical properties of phase change dispersions with the use of cosurfactants is defined. Two of the developed formulations were then chosen for a heat transfer and rheological behaviour comparison to observe the effect that surfactants have on the transport and heat transfer properties during heating. This was performed using a test-rig to measure the bulk fluid and inner wall temperatures of the phase change dispersions flowing through a cylindrical tube under the constant heat flux boundary condition. The crystallisation heat transfer and rheological behaviour of a phase change dispersion was also examined through calculation of heat balances in a rectangular duct. During melting and crystallisation, an interesting phenomenon was discovered, that the transition from laminar to turbulent with phase change dispersions was much lower than those predicted for Newtonian fluids. By regression of the experimental results, correlations for the average Nusselt numbers for laminar and turbulent flow are presented, using a modified Reynolds number and a Prandtl number correction factor. A numerical model for the thermal behaviour studies of a phase change dispersion during its cooling in laminar flow through a rectangular duct was developed and is based on the quasi-homogeneous single fluid approach. The evolution of the experimental and theoretical values shows good agreement and the model satisfactorily predicts the behaviour, with variations of less than 5%
2
Taetz, Christoph [Verfasser]. "Laminar Heat Transfer of Phase Change Dispersions / Christoph Taetz." Aachen : Shaker, 2014. http://d-nb.info/1053903332/34.
Full text
3
Delhorme, Maxime. "Thermodynamics and Structure of Plate-Like Particle Dispersions." Phd thesis, Université de Bourgogne, 2012. http://tel.archives-ouvertes.fr/tel-00818964.
Full textAbstract:
A considerable amount of mineral particles are found to have a plate-like shape. The work in this thesis concerns theoretical investigations, using a Monte Carlo method, of the properties of such particles in aqueous solutions. The objectives were first to create a model that could capture the essential physics of clay suspensions and also to understand the role of thermodynamics in certain chemical processes. For all investigations, the results are related to experimental studies. The acid-base behavior of clays have been studied, using the primitive model, and an excellent agreement between simulated and experimental results was found. The formation of gel phases as a function of the charge anisotropy have also been investigated. Liquid-gel and sol-gel transitions are found to occur for high and moderate charge anisotropy, respectively. These transitions were also found to be size and salt dependent. In absence of charge anisotropy, a liquid-glass transition is reported. The formation of smectic and columnar liquid crystals phases with plate-like particles has been found to be favored by a strong charge anisotropy, in opposition to what was observed for nematic phases. New liquid-crystal phases were also reported. The stability and growth of nanoplatelets is discussed. It was found that the internal Coulombic repulsion could be the cause of the limited growth of C-S-H platelets. The influence of thermodynamics on the agregation mode of such platelets was also investigated
4
Kappels, Tobias [Verfasser], Marcus [Gutachter] Petermann, and Roland [Gutachter] Span. "Rheologische Eigenschaften von Paraffin/Wasser-Dispersionen als Phase Change Slurry / Tobias Kappels ; Gutachter: Marcus Petermann, Roland Span." Bochum : Ruhr-Universität Bochum, 2017. http://d-nb.info/1123283451/34.
Full text
5
Bourova, Ekaterina. "Etude de la structure lithosphérique par l'analyse d'ondes de surface dans deux zones de convergence : la mer Egée et l'Iran." Phd thesis, Université Joseph Fourier (Grenoble), 2004. http://tel.archives-ouvertes.fr/tel-00721460.
Full textAbstract:
La structure lithosphérique profonde a été étudiée dans deux zones de convergence : la zone de subduction de la mer Egée et la zone de collision en Iran. Pour obtenir des contraintes sur la structure lithosphérique, nous avons analysé des ondes de surface enregistrées sur des réseaux temporaires large-bande installés dans ces zones. Dans la mer Egée, les quatre coupes de vitesse des ondes S obtenues montrent une anomalie de vitesse rapide associée au slab subductant. Une anomalie de vitesse lente de 4% est observée dans la partie nord de la région, à 100-150 km de profondeur. La position de cette anomalie correspond à une zone de déformation rapide en surface, qui semble être liée à des processus profonds dans le manteau. Dans la deuxième zone d'étude, nous avons constaté des vitesses lentes et une lithosphère amincie sous l'Iran central. Ces résultats peuvent être expliqués par une remontée de l'asthénosphère et l'érosion thermique de la lithosphère dans cette région
6
Essebbar, Abderrahman. "Séparation paramétrique des ondes en sismique." Phd thesis, Grenoble INPG, 1992. http://tel.archives-ouvertes.fr/tel-00785644.
Full textAbstract:
Dans cette étude, nous nous intéressons à la séparation des ondes sismiques, traitement principal conditionnant toute interprétation physique des données. En première partie, les méthodes de séparation non paramétriques (Matrice spectrale, Transformée de Karhunen-Loève et Filtrage FK) sont étudiées. La limitation de ces méthodes nous a conduit à utiliser l'approche paramétrique. Cette approche fait apparaître une modélisation qui permet de tenir compte des divers types d'ondes sismiques. La séparation paramétrique des ondes utilise l'estimateur du maximum de vraisemblance. Elle est réalisée en estimant les différents paramètres (lenteur apparente, amplitude, forme de l'onde, phase et angle d'incidence) caractérisant chaque onde. Les différentes méthodes d'estimation ainsi que les limites et les performances de la séparation paramétrique sont étudiées en deuxième partie. Les résultats de cette étude sont appliqués, en dernière partie, au traitement des signaux sismiques de puits issus d'une expérimentation ainsi qu'à des ondes dispersives de sismique de, surface.
7
Salem, Diana. "Synthèse de nanotubes de carbone monofeuillets individuels et composites modèles polymères - nanotubes de carbone : application à l’effet photovoltaïque." Thesis, Strasbourg, 2012. http://www.theses.fr/2012STRAE001/document.
Full textAbstract:
L’objectif de ce travail est d’élaborer des matériaux composites modèles nanotubes de carbone/polymères permettant de tirer profit des propriétés des nanotubes de carbone à l’échelle macroscopique. L’obtention de tels matériaux nécessitant une fonctionnalisation homogène entre les nanotubes de carbone et les polymères, les nanotubes de carbone utilisés doivent être individuels et de même réactivité chimique, donc de même diamètre. Ainsi, ils doivent être synthétisés par CVD par des nanoparticules catalytiques monodisperses et supportées. Dans la première partie, nous avons élaboré une nouvelle méthode générique de synthèse de nanoparticules d’oxydes métalliques supportées. Nous avons principalement détaillé la synthèse de nanoparticules de Fe2O3 dont la distribution en taille est de 1.1 ± 0.3 nm. Dans la deuxième partie, après avoir étudié la stabilité thermique de ces nanoparticules, nous les avons utilisées pour catalyser la croissance des nanotubes de carbone monofeuillets individuels par CVD. La caractérisation des nanotubes obtenus par Raman indique une distribution en diamètre exceptionnellement étroite de 1.27 ± 0.15 nm. Dans la troisième partie, nous avons tout d’abord étudié la mise en solution des nanotubes de carbone par fonctionnalisation non covalente avec un polymère hydrosoluble le POE portant un motif pyrène en bout de chaîne et mis en évidence un phénomène de déplétion qui limite la solubilisation des nanotubes. Nous avons ensuite élaboré des matériaux composites nanotubes de carbone/rrP3HT par fonctionnalisation covalente et non covalente et nous avons étudié l’efficacité de séparation de charge dans les deux cas de fonctionnalisationsThe aim of this work is to develop composite materials carbon nanotubes/polymers to take advantage of properties of carbon nanotubes at macroscopic scale. To get such materials, homogeneous functionalization between carbon nanotubes and polymers is required, carbon nanotubes must be individual with the same chemical reactivity, therefore the same diameter. Thus, they must be synthesized by CVD from monodispersed and supported catalyst nanoparticles. In the first part, we developed a new universal method for the synthesis of metal oxide supported nanoparticles. We mainly detailed the synthesis of Fe2O3 nanoparticles with size distribution of 1.1 ± 0.3 nm. In the second part, after studying the thermal stability of these nanoparticles, we used them to catalyze the growth of individual single wall carbon nanotubes by CVD. The caracterisation of the obtained nanotubes by Raman show exceptionally narrow diameter distribution of 1.27 ± 0.15 nm. In the third section, we first studied the dispersion of carbon nanotubes by noncovalent functionalization withhydro-soluble polymer POE with pyrene as end group and revealed depletion phenomena that limit the solubilization of nanotubes. Then we developed composite materials carbon nanotubes/rrP3HT by covalent and noncovalent functionalisation and we studied the efficiency of charge separation in both cases of functionalization
8
Chiu, Yu-Hsiu, and 邱鈺琇. "Thermal Properties and Structural Characterizations of New Types of Phase Change Material: Anhydrous and Hydrated Palmitic Acid/Camphene Solid Dispersions." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/9k3f6k.
Full textAbstract:
碩士國立中央大學
化學工程與材料工程學系
101
Our aim is to find phase change material (PCM) mixtures which also have an increase in the heat capacity in solid or liquid state. Increasing heat capacity in liquid or solid state would enhance the part of heat storage which can be used in a wider temperature range, rather than just to absorb or release heat energy near the melting point or freezing point. We use low-temperature differential scanning calorimetry (LT-DSC) to determine the melting point and the equilibrium state, powder X-ray diffraction (PXRD) and small-angle X-ray scattering (SAXS) to determine the nano structures, temperature-history method to find the thermal properties in large-scale. 1: 1 molar ratios of palmitic acid/camphene mixture (PA1CA1) By using temperature-history method, thermal properties of anhydrous PA1CA1 are: Tm = 322.7+0.0 K, cpl = 2.04+0.04 kJ kg-1 K-1, cps = 2.17+0.06 kJ kg-1 K-1, ΔHls = 114.0+1.2 kJ kg-1, and ks = 0.21+0.00 W m-1 K-1 and the thermal properties of hydrated PA1CA1 are: Tm = 324.8+0.2 K, cpl = 2.29+0.04 kJ kg-1 K-1, cps = 2.61+0.01 kJ kg-1 K-1, ΔHls = 119.6+1.8 kJ kg-1, and ks = 0.21+0.01 W m-1 K-1. Overall, hydrated PA1CA1 is better than anhydrous PA1CA1 with increasing in both heat capacity in solid and liquid state. Partial amorphous phase formation (more disordered state) helps increase the heat capacity in solid state of anhydrous or hydrated PA1CA1. The mixture of palmitic acid and camphene in this research is not a eutectic mixture but rather palmitic acid particles nanometer-sized 222 nm ~431 nm are dispersed in partial amorphous camphene matrix to form a solid dispersion. Our systems can be used in passive storage in bio-climatic building/architecture and application in off-peak electricity for cooling and heating.
Books on the topic "Phase change dispersion"
1
Aveyard, Bob. Surfactants. Oxford University Press, 2019. http://dx.doi.org/10.1093/oso/9780198828600.001.0001.
Full textAbstract:
Characteristically, surfactants in aqueous solution adsorb at interfaces and form aggregates (micelles of various shapes and sizes, microemulsion droplets, and lyotropic liquid crystalline phases). This book is about the behaviour of surfactants in solution, at interfaces, and in colloidal dispersions. Adsorption at liquid/fluid and solid/liquid interfaces, and ways of characterizing the adsorbed surfactant films, are explained. Surfactant aggregation in systems containing only an aqueous phase and in systems with comparable volumes of water and nonpolar oil are each considered. In the latter case, the surfactant distribution between oil and water and the behaviour of the resulting Winsor systems are central to surfactant science and to an understanding of the formation of emulsions and microemulsions. Surfactant layers on particle or droplet surfaces can confer stability on dispersions including emulsions, foams, and particulate dispersions. The stability is dependent on the surface forces between droplet or particle surfaces and the way in which they change with particle separation. Surface forces are also implicated in wetting processes and thin liquid film formation and stability. The rheology of adsorbed films on liquids and of bulk colloidal dispersions is covered in two chapters. Like surfactant molecules, small solid particles can adsorb at liquid/fluid interfaces and the final two chapters focus on particle adsorption, the behaviour of adsorbed particle films and the stabilization of Pickering emulsions.
Book chapters on the topic "Phase change dispersion"
1
Khelladi, Mounir. "Femtosecond Laser Pulses: Generation, Measurement and Propagation." In Recent Advances in Numerical Simulations. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.95978.
Full textAbstract:
In this contribution some basic properties of femtosecond laser pulse are summarized. In sections 2.1–2.5 the generation of femtosecond laser pulses via mode locking is described in simple physical terms. In section 2.6 we deal with measurement of ultrashort laser pulses. The characterization of ultrashort pulses with respect to amplitude and phase is therefore based on optical correlation techniques that make of the short pulse itself. In section 3 we start with the linear properties of ultrashort light pulses. However, due to the large bandwidth, the linear dispersion is responsible for dramatic effects. To describe and manage such dispersion effects a mathematical description of an ultrashort laser pulse is given first before we continue with methods how to change the temporal shape via the frequency domain. The chapter ends with a paragraph of the wavelet representation of an ultrashort laser pulse.
2
Glazer, A. M. "5. Seeing atoms." In Crystallography: A Very Short Introduction, 94–106. Oxford University Press, 2016. http://dx.doi.org/10.1093/actrade/9780198717591.003.0005.
Full textAbstract:
It is clear that knowledge of the relative phases is essential if we wish to find the atoms in a crystal. So what do we do if we do not have phase information? ‘Seeing atoms’ describes the phase problem and the different methods of phase determination used by crystallographers: a difference Fourier map; the Patterson method; electron density maps; multiple isomorphous replacement; multiple-wavelength anomalous dispersion using synchrotron radiation, which is often used in macromolecular crystallography; molecular replacement, commonly used in protein crystallography; the Sayre equation, a mathematical relationship that enables probable values for the phases of some diffracted beams to be found; and a new technique called charge flipping.
3
Guenther, B. D. "Guided Waves." In Modern Optics Simplified, 249–84. Oxford University Press, 2019. http://dx.doi.org/10.1093/oso/9780198842859.003.0008.
Full textAbstract:
Use a one-dimension theory based on the normal to a plane wave to evaluate the propagation of light in a dielectric layer. If the ray strikes the walls of the guide it must meet the condition for total reflection. The theory, called the zigzag model, is not a “pure” geometric theory because we use the properties of interference and of phase change upon total reflection that we derived using wave theory. The theory predicts that the rays propagating down the guide can only strike the walls at discrete angles. These angles are the modes of the guide. The theory allows us to calculate the number of bounces/unit length the ray can make. We show limitaitons on coupling energy into the guided modes and the numerical aperture of a mode. We discuss losses and dispersion in the guide and introduce photonic crystals that allow hollow guides to be constructed.
4
Joseph D., Robson. "Dispersoid Precipitation in Aluminum Alloys." In Encyclopedia of Aluminum and Its Alloys. Boca Raton: CRC Press, 2019. http://dx.doi.org/10.1201/9781351045636-140000252.
Full textAbstract:
Dispersoid particles are critical to the control of recrystallization and grain growth behavior during thermomechanical processing of wrought aluminum alloys. The precipitation of dispersoids has some unique characteristics that must be considered to understand the microstructure and properties obtained in the final product. Dispersoids precipitate from a segregated cast structure and therefore are inhomogeneously distributed within a grain. They often precipitate from other phases that form during heating and then redissolve. Finally, their precipitation is often in competition with other microstructural processes, for example, a change in composition of the constituent phases. Understanding these factors is critical to control dispersoid precipitation. Furthermore, the increasing demand to replace primary aluminum with recycled material requires careful control of the dispersoid-forming elements, which tend to accumulate during recycling. Small changes in the amounts of these additions can have a large effect on recrystallization behavior and hence texture and properties.
5
Chimenti, Dale, Stanislav Rokhlin, and Peter Nagy. "Waves in Periodically Layered Composites." In Physical Ultrasonics of Composites. Oxford University Press, 2011. http://dx.doi.org/10.1093/oso/9780195079609.003.0011.
Full textAbstract:
Composite materials, unless they are quite thin, often include periodic layering, where laminated plates composed of alternating uniaxial plies in two or more directions result in more evenly distributed in-plane stiffness. The oriented plies can generally be reduced to a unit cell geometry which repeats throughout the laminate and is composed of sublayers each having highly directional in-plane stiffness, but identical out-of-plane properties. As the transverse isotropy of a uniaxial fibrous ply derives from the geometry of the two-phase material, composite laminates of these plies will have microscopic elastic stiffness tensors which change only in the plane of the laminate, as we saw in Chapter 1. The elastic properties normal to the laminate surface remain unchanged from ply to ply. In this chapter we take up the subject of waves in periodically layered plates. Unusual guided wave dispersion effects have been observed experimentally in periodically layered plates. Shull et al. found, for guided waves polarized in the vertical plane in plates of alternating aluminum and aramid–epoxy composites, that dispersion never scales with the frequency–thickness product, as it would in homogeneous isotropic, or layered transversely isotropic, plates. Instead, grouping of the mode curves has been observed. In an attempt to understand this behavior in terms of periodic layering, Auld et al. have analyzed the simpler case of SH wave propagation in periodically layered plates and have demonstrated that these observed phenomena can be attributed to the pass band and stop band structure caused by the periodic layering. In this section, we will show that Floquet modes play a critical role in the behavior of guided waves in plates that are periodically layered. To analyze the problem, we apply an extension of the stiffness matrix method of the previous chapter. Floquet modes, which are the characteristic modes for the infinite periodically layered medium, can be thought of as the analogy—in a periodically layered medium—to the quasilongitudinal and quasishear modes for the infinite homogeneous medium. On the topic of infinite periodic media, many calculations, both approximate and exact, have been performed to model elastic wave propagation in this important class of structures.
6
Mrówka-Nowotnik, Grażyna. "6XXX Alloys: Chemical Composition and Heat Treatment." In Encyclopedia of Aluminum and Its Alloys. Boca Raton: CRC Press, 2019. http://dx.doi.org/10.1201/9781351045636-140000212.
Full textAbstract:
Analysis of the influence of chemical composition, crystallization process and heat treatment on the phase constituents’ morphology, and mechanical properties and crack resistance of 6xxx Al alloys were conducted. The alloys with low Mg and Si content (6063) in the as-cast state are characterized by presence of Si particles and primary intermetallic phases: α-Al8Fe2Si, β-Al5FeSi, β-Mg2Si, and α-Al(FeMn)Si. Higher Mg, Si, and Mn content (6005 and 6082) leads to separation of additional phase particles: Al6Fe, Al6Mn, and Al12(FeMn)Mg3Si6, whereas high Cu content (6061—0.35% and 6066—0.95%, respectively) is responsible for precipitation of additional phase particles: Q-Al5Cu2Mg8Si6 and θ-Al2Cu. It has been established that homogenization results in total dissolution of the θ-Al2Cu and Q-Al5Cu2Mg8Si6 primary phases and partial dissolution of β-Mg2Si. Needle-like and Chinese-script α-Al8Fe2Si and β-Al5FeSi were transformed into spheroidal α-Al(FeMn)Si particles. The maximal consolidation of the 6xxx alloys is a result of precipitation of metastable particles, the transient βʺ, βʹ, and Qʹ/θʹ phases (6061 alloy) with high dispersion. The highest mechanical properties were achieved after holding in the temperature of 565°C/6 h, supersaturated in water, and aging at 175°C/10–20 h (T6). The decohesion process in the presence of tensile stresses in the room temperature proceeds through nucleation, the growth and joining of the voids, as well as the cracking of the primary and secondary large-sized intermetallic phase particles. The increase of deformation temperature up to 300°C causes the changes of the nucleation source and joining of voids—it occurs mainly along the matrix–particle interface.
7
A. Novakova, Alla, and Dmitrii S. Novikov. "Study of Deep-Ocean Ferromanganese Crusts Ore Components." In Iron Ores [Working Title]. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.98200.
Full textAbstract:
A complex layer-by-layer morphology and phase analysis of a ferromanganese crust aged about 70 million years, extracted from the rise of the Magellan Mountains of the Pacific Ocean, was carried out using several physics methods: digital optical microscopy, scanning electron microscopy with high resolution, X-ray fluorescence and diffraction analysis and Mossbauer spectroscopy. This analysis showed that the crust is an association of several minerals with various dispersion and crystallization degree, between which fossilized bacterial mats with Fe- and Mn- oxides are located. These phenomena indicate the biogenic nature of the crust. Changes in the crusts phase composition from the lower layer to the upper layer indicate changes in the external environmental conditions during their formation.
8
Yakhno, Tatiana, and Vladimir Yakhno. "Structure and Dynamics of Aqueous Dispersions." In Colloids - Types, Preparation and Applications [Working Title]. IntechOpen, 2020. http://dx.doi.org/10.5772/intechopen.94083.
Full textAbstract:
The content of the chapter summarizes the long-term studies of the authors of the structure and dynamics of aqueous dispersions, including model protein-salt solutions, blood serum of healthy and sick people, food microdisperse systems. The data are considered in the context of the existing scientific literature on the stated problem. One of the important issues is the phase transitions of the protein when the ionic strength of the solution changes. To observe these processes, a drying droplet model, optical and atomic force microscopy are used. Based on the observations, a model of a cascade of phase transitions of a protein, from micelles to gel, was created. Parallels are drawn with the violation of these processes based on the results of the study of blood serum in seriously ill people. It is also shown that in the free volume of microdisperse systems there are near-hour oscillatory processes associated with the aggregation - disaggregation of the microdispersed phase. The surface tension of solutions, the mechanical properties of liquids, and the morphological characteristics of dried drops also fluctuate simultaneously. A model of self-oscillatory processes in such systems is presented, consistently describing the observed phenomena.
9
V. Sazanova, Katerina, Nadezhda V. Psurtseva, and Alexey L. Shavarda. "Metabolomic Changes in Wood Inhabiting Filamentous Fungi during Ontogenesis." In Metabolomics - Methodology and Applications in Medical Sciences and Life Sciences. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.96621.
Full textAbstract:
GC–MS-based metabolomic profiling of different strains of basidiomycetes Lignomyces vetlinianus, Daedaleopsis tricolor and Sparassis crispa were studied. On different stages of growth in the methanol extracts of mycelium the different compounds including amino acids, organic acid of TCA cycle, sugars, fatty acids, sugar alcohols, and sugar acids were detected. Changes in the metabolite network occurring with age of the mycelium of L. vetlinianus and D. tricolor are discussed. The exponential phase of mycelium growth is characterized by pronounced differences during of growth, which manifests itself both in the analysis of specific compounds and in the modeling of the statistical model of the metabolic network. The metabolomic network in the stationary growth phase is less susceptible to changes over time, and is also characterized by a lower dispersion of samples from one aging group. For some compounds, including biotechnologically significant ones, targeted analysis by GC–MS was performed. 4, 6-dimethoxy-phthalide (4, 6-dimetoxy-1 (3H) -isobenzofuranone) was isolated from the mycelium of Lignomyces vetlinianus, accumulating in the mycelium in the form of large aggregates. The accumulation of sparassol and other orsellinic acid derivatives in Sparassis crispa culture under various conditions is described.
10
Mishra, Bal Mukund, Supriyo Roy, and Goutam Kumar Bose. "Tribological and Micro-Structural Characterization of Ni-Cu-P-W Coatings." In Advanced Surface Coating Techniques for Modern Industrial Applications, 209–25. IGI Global, 2021. http://dx.doi.org/10.4018/978-1-7998-4870-7.ch009.
Full textAbstract:
Ni-Cu-P-W coating was deposited by electroless method on mild steel substrate to study the crystallization and tribological behavior at different annealing temperatures. Energy dispersive x-ray (EDX) analysis, scanning electron microscopy (SEM), x-ray diffraction (XRD), and differential scanning calorimeter (DSC) were used to study the composition, surface morphology, phase behavior, and thermal behavior of the coating, respectively. Tribological study was conducted using Pin-on-Disc tribotester. EDX analysis confirms the presence of Ni, Cu, P, and W in the deposit. SEM image shows the surface is dense, smooth, and without any observable nodule. Some of the samples were heat treated to 300°C, 500°C, and 700°C for 1 hour to observe the crystallographic change by XRD. One sharp crystalline peak of Ni (111) is present in all condition, but the intensity increases rapidly with the heat treatment temperature. The phase transition temperature of this quaternary coating analyzed by DSC was 431.8°C.
Conference papers on the topic "Phase change dispersion"
1
Zeng, Xie, Haifeng Hu, Yongkang Gao, Dengxin Ji, Nan Zhang, Haomin Song, Kai Liu, and Qiaoqiang Gan. "Phase change dispersion of plasmonic nano-objects." In CLEO: Applications and Technology. Washington, D.C.: OSA, 2015. http://dx.doi.org/10.1364/cleo_at.2015.jtu5a.76.
Full text
2
Xie Zeng, Haifeng Hu, Yongkang Gao, Dengxin Ji, Nan Zhang, Haomin Song, Kai Liu, and Qiaoqiang Gan. "Phase change dispersion during surface plasmon coupling via nano-objects." In 2015 IEEE Photonics Conference (IPC). IEEE, 2015. http://dx.doi.org/10.1109/ipcon.2015.7323697.
Full text
3
Trezza, J. A., B. Pezeshki, M. C. Larson, S. M. Lord, and J. S. Harris. "High Contrast Reflection Electro-Absorption Modulator With Zero Phase Change." In Quantum Optoelectronics. Washington, D.C.: Optica Publishing Group, 1993. http://dx.doi.org/10.1364/qo.1993.qthb.7.
Full textAbstract:
Vertical cavity quantum-well optical modulators utilizing the quantum-confined Stark effect (QCSE) are being increasingly investigated for use in optical communication and computing.1 Reflection modulators based upon large absorption changes in quantum wells have shown high contrast ratios2 while exhibiting lower parasitic phase modulation than conventional waveguide modulators.3 Since quantum wells are capable of large absorption changes (Δα), they also exhibit large refractive index changes (Δn).4-5 Understanding the role of quantum well excitons and phase is crucial for high speed optical switching since such switching will be critically limited by Δn induced pulse broadening. The ratio of phase shift to absorption is typically reported through the chirp parameter where a low chirp parameter is desirable for low-dispersion amplitude modulation. Here we describe how parasitic Δn can be eliminated in a novel, optimized structure thus yielding a pure reflection modulator with a zero chirp parameter. At the operating wavelength, such a device would exhibit a high reflectivity change and zero phase change when switched between two bias points. We have designed and developed such devices by analyzing excitonic lineshapes, numerically simulating our structures including quantum well absorption and dispersion effects, and creating a flexible modulator design which allows for optimization after growth. We note that our theory also applies to eliminating Δn in waveguide modulators which rely upon the QCSE.
4
Han, Zenghu, Bao Yang, and Yung Y. Liu. "Phase-Change Nanofluids With Enhanced Thermophysical Properties." In ASME 2009 Second International Conference on Micro/Nanoscale Heat and Mass Transfer. ASMEDC, 2009. http://dx.doi.org/10.1115/mnhmt2009-18148.
Full textAbstract:
The colloidal dispersion of solid nanoparticles (1–100nm) has been shown experimentally to be an effective way to enhance the thermal conductivity of heat transfer fluids. Moreover, large particles (micrometers to tens of micrometers) of phase-change materials have long been used to make slurries with improved thermal storage capacity. Here, a hybrid concept that uses nanoparticles made of phase-change materials is proposed to simultaneously enhance the effective thermal conductivity and the effective heat capacity of fluids. Water-in-perfluorohexane nanoemulsion fluids and indium-in-polyalphaolefin nanofluids are examples of fluids that have been successfully synthesized for experimental studies of their thermophysical properties (i.e., thermal conductivity, viscosity, and heat capacity) as functions of particle loading and temperature. The thermal conductivity of perfluorohexane was found to increase by up to 52% for nanoemulsion fluids containing 12 vol. % water nanodroplets with a hydrodynamic radius of ∼10 nm. Also observed in water-in-perfluorohexane nanoemulsion fluids was a remarkable improvement in effective heat capacity, about 126% for 12 vol. % water loading, due to the melting-freezing transitions of water nanodroplets to ice nanoparticles and vice versa. The increases in the thermal conductivity and dynamic viscosity of these nanoemulsion fluids were found to be highly nonlinear against water loading, indicating the important roles of the hydrodynamic interaction and the aggregation of nanodroplets. For indium-in-polyalphaolefin nanofluids, the thermal conductivity enhancement increases slightly with increasing temperature (i.e., about 10.7% at 30°C to 12.9% at 90°C) with a nanoparticle loading of 8 vol. %. The effective volumetric heat capacity can be increased by about 20% for the nanofluids containing 8 vol. % indium nanoparticles with an average diameter of 20 nm. Such types of phase-change nanoemulsions and nanofluids possess long-term stability and can be mass produced without using as-prepared nanoparticles. The observed melting-freezing phase transitions of nanoparticles of phase-change materials (i.e., water nanodroplets and indium nanoparticles) considerably augmented the effective heat capacity of the base fluids. The use of phase-change nanoparticles would thus provide a way to substantially enhance the thermal transport properties of conventional heat transfer fluids. Future development of these phase-change nanofluids is expected to open new opportunities for studies of thermal fluids.
5
Prokopeva, Ludmila J., Vladimir Liberman, Jeffrey Chou, Christopher Roberts, Mikhail Shalaginov, Yifei Zhang, Juejun Hu, Zhaxylyk A. Kudyshev, and Alexander V. Kildishev. "Time domain modeling of bi-anisotropic media and phase change materials with generalized dispersion (Conference Presentation)." In Metamaterials, Metadevices, and Metasystems 2019, edited by Nader Engheta, Mikhail A. Noginov, and Nikolay I. Zheludev. SPIE, 2019. http://dx.doi.org/10.1117/12.2529097.
Full text
6
Zheng, Shu-ying, and Ping Guo. "An expression for the halfwidth of phase dispersion induced transmission filters." In Optical Interference Coatings. Washington, D.C.: Optica Publishing Group, 1997. http://dx.doi.org/10.1364/oic.1998.wf.5.
Full textAbstract:
The theory on induced transmission in absorbing thin films1,2 made it feasible to design dielectric-metal narrow band filters based on the relationship between the optical properties and the optical surroundings of a metal layer. It has been indicated that narrow band reflection and transmission of a metal layer may be induced by a drastic change in the reflection phase shift from the matching stack attached to the emergent boundary of the metal layer3 and that the halfwidth of spectral band was inversely proportional to the phase dispersion power4. It can be seen in this paper that a simple expression for the halfwidth of phase dispersion induced transmission (PDIT) filters was a derivative of the induced transmission theory.
7
Abelès, Florin, and Philip Baumeister. "Multilayer dielectric mirrors with minimal dispersion of differential phase shift upon reflection." In Optical Interference Coatings. Washington, D.C.: Optica Publishing Group, 1992. http://dx.doi.org/10.1364/oic.1992.omb4.
Full textAbstract:
Lasers and liquid crystal displays often require coatings that reflect the incident radiant flux with minimal change in its state of polarization. The differential phase shift upon reflection of such a coating should be zero. Since there is always a possibility of drift of the wavelength centering of the stack during fabrication, the dispersion of the differential phase shift upon reflection should also be minimal.
8
Akhmetov, Alfir T., Marat V. Mavletov, Sergey P. Sametov, Artur A. Rakhimov, Azat A. Valiev, and Iskander S. Akhatov. "Dispersion Flow in Microchannels." In ASME 2012 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/imece2012-86618.
Full textAbstract:
The work is devoted to experimental investigations of the features of flow of dispersions in microchannels. The paper consists of three parts. In the first part the flow of emulsions in smooth contracting cylindrical microchannels is investigated. It is received that a significant role at dynamic blocking of channels is played by the inclusions comparable by size to the diameter of a narrowing. This is in spite of the fact that their influence on the change of a flow rate of emulsion before blocking is insignificant. In the second part the generation of emulsion in a complex structure of microchannels (micromodels) when water is displaced by composition of hydrocarbon with surfactants is investigated. The experimental dependences of the rheological characteristics of emulsions based on the composition of SAS and water at different concentrations of the aqueous phase can explain blocking of a porous structure by generated emulsion. In the third part a comparison of flow of water-in-oil emulsions with the suspension which was obtained by freezing the microdroplets of the aqueous phase of emulsions was studied. It was found that the blocking of suspension is not as complete as in the case of emulsion. It is explained by deformation of the droplets and by formation of a dense structure, as opposed to suspension of beads, through which hydrocarbon phase is filtered. A small increase in effective viscosity due to solidification of freezing droplets of the dispersed phase was found.
9
Dhiman, Nikhil, Jeet Shah, Dereje Agonafer, Naveen Kannan, James Hoverson, and Mike Kaler. "Application of Phase Change Material in Sustainable Cooling of Data Centers." In ASME 2013 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/imece2013-66515.
Full textAbstract:
The ever increasing information technology heat load and data center cooling energy are the main reasons to investigate the performance of microencapsulated phase change slurry over other heat transfer fluids. Microencapsulated phase change slurry is dispersion where the phase change material, microencapsulated by a polymeric capsule, is dispersed in water. Compared to water, these new fluids have a higher heat capacity during phase change and a possible enhancement, as a result of this phase change, in the heat transfer phenomenon. The composition of phase change material used in slurry greatly affects its efficiency, If not selected properly it can cause serious damage, e.g. agglomeration and clogging of pipes. The main objective of this work is to develop standalone pumpable microencapsulated phase change slurry that is able to withstand shear stresses of the pump and other course surfaces of pipe and pipe joints. In this study, experiments were performed, to determine performance of microencapsulated phase change slurry over conventional heat transfer fluids. After certain pumping cycles, scanning electron microscopy (SEM) has been done to analyze the conditions of shell material of polymeric capsule. Results obtained from SEM show that centrifugal pump is compatible with mPCM particle size upto 3 μm. It is true that selected mPCS have shown better performance over water in hot water bath in case of thermal storage. Also, closed loop final testing has shown that heat flux is about 2–3 times higher with mPCS than water.
10
Pan, J. J., F. Q. Zhou, Y. Shi, and S. X. Li. "Effective Apodized Phase Mask For Optimum FBGs." In The European Conference on Lasers and Electro-Optics. Washington, D.C.: Optica Publishing Group, 1998. http://dx.doi.org/10.1364/cleo_europe.1998.cfb3.
Full textAbstract:
FBGs are promising devices for DWDM networks [1]. Phase mask (PM) technique is one of the most versatile techniques for massive production of FBGs. However, ever increasing requirements of DWDM put stringent requirements on FBG sidelobe suppression and spectral skirt sharpness. In this paper, we report a detailed comparison of different apodization profiles with emphasis on narrow linewidth, sharp spectral skirt and a large figure of merit which is the ratio of bandwidth at -0.5 dB to that at -25 dB. Effective apodized PM was fabricated by using e-beam writing and reactive ion-milling (RIM) with stitching error-free. For a gaussian apodized FBG. it has a gaussian refractive index modulation, an inverse gaussian index background and a constant average index change along the FBG with no unwanted dispersion. FBG apodization using PM dithering technique suffers some drawbacks for pulsed UV excimer lasers and for very high UV photosensitive fibers. Scanning writing apodized FBG technique needs double UV exposures for FBG writing and background index change resulting in a lower control accuracy and a lower fabrication efficiency. Using apodization aperture and amplitude masks have the similar problems of double exposure and lower control accuracy resulting unwanted dispersion. Apodized PM technique is an efficient method for qualified DWDM FBGs production with a simple setup and an excellent fabrication repeatability.