Journal articles: 'Phase change dispersion'

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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Tan, Felicia, Vincent Tam, and Chris Savvides. "Elevated LNG Vapour Dispersion—Effects of Topography, Obstruction and Phase Change." Eng 2, no. 2 (June 15, 2021): 249–66. http://dx.doi.org/10.3390/eng2020016.

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The dispersion of vapour of liquefied natural gas (LNG) is generally assumed to be from a liquid spill on the ground in hazard and risk analysis. However, this cold vapour could be discharged at height through cold venting. While there is similarity to the situation where a heavier-than-air gas, e.g., CO2, is discharged through tall vent stacks, LNG vapour is cold and induces phase change of ambient moisture leading to changes in the thermodynamics as the vapour disperses. A recent unplanned cold venting of LNG vapour event due to failure of a pilot, provided valuable data for further analysis. This event was studied using CFD under steady-state conditions and incorporating the effect of thermodynamics due to phase change of atmospheric moisture. As the vast majority of processing plants do not reside on flat planes, the effect of surrounding topography was also investigated. This case study highlighted that integral dispersion model was not applicable as key assumptions used to derive the models were violated and suggested guidance and methodologies appropriate for modelling cold vent and flame out situations for elevated vents.

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Ikutomo, R., Masato Tsujikawa, Makoto Hino, Hisamichi Kimura, Kunio Yubuta, and Akihisa Inoue. "Fine Crystalline Phase Dispersion in Zr-Based Bulk Metallic Glass by Laser Irradiation." Advanced Materials Research 26-28 (October 2007): 747–50. http://dx.doi.org/10.4028/www.scientific.net/amr.26-28.747.

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Bulk metallic glass (BMG) exhibits remarkable properties such as high strength, good stiffness and good corrosion resistance. However, the wear resistance of amorphous metals is not excellent as expected their high strength. It is thought that large local shear bands easily change into cracks for debris formation. The effective obstruction of shear band formation might be applied to improve the wear resistance of BMG. In this study, we tried to suppress shear band deformation by fine crystalline phase dispersion formed by semi-conductor laser irradiation. The microstructures of irradiated Zr-based BMG specimens were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). The fine dispersions of crystalline phases are observed in the amorphous matrix. The optimum condition for laser irradiation was discussed.

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Fischer, L. J., S. von Arx, U. Wechsler, S. Züst, and J. Worlitschek. "Phase change dispersion, potentially a new class of heat transfer fluids." Journal of Physics: Conference Series 745 (September 2016): 032133. http://dx.doi.org/10.1088/1742-6596/745/3/032133.

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14

Chavez, C. T., A. Egly, I. Sepulveda, and F. J. Wessel. "Measurement of 2D density profiles using a second-harmonic, dispersion interferometer." Review of Scientific Instruments 94, no. 2 (February 1, 2023): 023503. http://dx.doi.org/10.1063/5.0119896.

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A second-harmonic, dispersion interferometer is used to image large-area (≃5 cm2) plasma-jet and gas-jet density profiles. Achromatic telescopes magnify the diameters of the primary-laser beam (1064 nm) and its second-harmonic (532 nm) before probing the sample and de-magnify the beam diameters after the sample, where the primary beam transfers its phase change to a second, second-harmonic beam, allowing the sample’s dispersive-phase change to be measured between two, orthogonally polarized second harmonic beams. The telescopes produce an azimuthally symmetric, dispersive-phase shift in the sample + background phase-change image and in the background phase-change image, which is removed by digital subtraction. The interferometer’s performance was verified using standard-optical components as dispersive elements (BK7 lenses and wedge plates), resolving a minimum, phase-change sensitivity of Δ ϕmin ≳ 15 mrad and spatial resolution of Δ xres ≃ 100 μm. The phase change produced by unknown-density objects (a pulsed-plasma-jet and a pulsed-gas-jet) was measured, and their data were used to recover the original, 2D density profiles using an inverse Abel transform: peak-number density, Ngas ≃ 6 × 1020 cm−3 and Ne ≃ 5 × 1016 cm−3; line-integrated density, ∫Ngas dl ∼ 2 × 1019cm−2 and ∫Ne dl ∼ 1 × 1016cm−2. The techniques and methods developed here are scalable to even larger probe-beam diameters and frame-capture rates, leading to a diagnostic capability that is well-suited for applications involving the real-time measurement of density.

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Ptáček, Jan, Vladimír Rod, and Vladislav Hančil. "Mass transfer accompanied by chemical reaction in a liquid dispersion." Collection of Czechoslovak Chemical Communications 50, no. 8 (1985): 1685–98. http://dx.doi.org/10.1135/cccc19851685.

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An experimental procedure has been worked out to measure mass transfer rates in the presence of a chemical reaction in a liquid dispersion in a batch mixed vessel by a dynamic method. Transfer rates have been observed of iodine between decalin and water phase containing potassium iodide. The transfer was described by the pseudohomogeneous model. Transport parameters of this model have been evaluated from the response of the system to a step concentration change in the continuous phase. The model of the experiment described distortion of the information in the sampling device for the continuous phase. Dependences have been measured of the iodine transfer coefficients in both phases on the intensity of mixing and volume hold-up of the dispersed liquid. By a suitable choice of the concentration in the continuous phase the ratio could be adjusted of the resistance against the transfer in both phases and the sensitivity could be affected of the objective function to the evaluated model parameters.

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Begand, Sabine, Thomas Oberbach, Mathias Herrmann, and Kerstin Sempf. "Surface Properties after Ageing of Dispersion Ceramic and its Influence on Strength." Key Engineering Materials 396-398 (October 2008): 157–60. http://dx.doi.org/10.4028/www.scientific.net/kem.396-398.157.

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The primary purpose of this work was the examination of the surface and the strength of ATZ ceramic after hydrothermal treatment. Hydrothermal treatment of ATZ ceramic leads to changes of roughness and phase composition on the surface. The phase composition and the microstructure on the surface and within the peripheral zone were determined after applying a stepwise broad ion beam polishing technique and quantitative phase analysis. With this technique a penetration depth of the phase transformation of less than 14 µm was observed. Investigations of the cross sectional area by means of FESEM have shown a transformation zone of about 9 µm. Both methods lead to comparable results with a very small, morphologically changed peripheral layer. The study of the strength after ageing with different thickness of the samples showed that for a thickness of 2.0 mm there is no negative influence on mechanical behaviour. In consideration of this fact no significant change of tribological properties is expected.

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Song, Yimin, Deshun Yuan, Junhui Zhang, Hailiang Xu, Dong An, and He Ren. "Study on the Stage Characteristics of Noise Dispersion in the Deformation Evolution of Red Sandstone." Mathematical Problems in Engineering 2022 (December 26, 2022): 1–20. http://dx.doi.org/10.1155/2022/2149273.

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The uniaxial compression experiment of red sandstone is observed simultaneously by using acoustic emission and digital speckle correlation methods. The deformation evolution of red sandstone is divided into microfracture random expansion stage, deformation localization stage, subinstability stage, and instability failure stage. Green’s function and dispersion curve of each stage are obtained from the noise data picked up by acoustic emission equipment, and the dispersion characteristics of each evolution stage are analyzed. The results show the following: (1) In the stage of random propagation of microcracks, the noise in the low frequency range passes through at a higher phase velocity, the phase velocity changes periodically, the correlation coefficient is high at the initial time, and the variation trend of frequency dispersion curve is relatively consistent. (2) In the deformation localization stage, the frequency range without zero phase velocity moves to the high frequency range, and the phase velocity changes periodically. (3) In the subinstability stage, dense phase velocity zeros appear on the dispersion curve image, the dispersion curve tends to be disordered, various indicators change obviously, and the correlation coefficient decreases rapidly. (4) In the unstable failure stage, the fracture evolution is completed, and the variation trend of each index of the frequency dispersion curve is consistent. (5) The size and difference of the sensitive kernel function of the two layers are related to the evolution region of the fracture. The sensitivity kernel value of the medium layer where the fracture evolves is high, and the longer the evolution time, the greater the difference.

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Yang, Luxi, Linchuan Dai, Lu Ye, Rui Yang, and Yangcheng Lu. "Microfluidic Fabrication and Thermal Properties of Microencapsulated N-Hexadecane with a Hybrid Polymer Shell for Thermal Energy Storage." Materials 15, no. 10 (May 22, 2022): 3708. http://dx.doi.org/10.3390/ma15103708.

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In this study, a strategy based on microfluidic method is developed toward a facile fabrication of phase change material microcapsules with uniform and controllable particle size as well as high encapsulation ratio and thermal stability. N-hexadecane, as a phase change material, was successfully encapsulated by a hybrid shell of poly (methyl methacrylate) and polyurea. The fabrication process includes the following three steps: (1) Formation of oil-in-water droplets with uniform micron size in the microfluidic chip; (2) formation of the first polyurea shell to encapsulate droplets by fast interfacial polymerization when the droplets pass through the coiled transport microchannel; and (3) completion of free radical polymerization of methyl methacrylate inside the microspheres by heating to form the hybrid microcapsule shell. The average size, encapsulation ratio, and phase change enthalpy of microcapsules changed by varying the flow rate of the dispersion phase and raw material composition. The highest melting enthalpy of 222.6 J g−1 and encapsulation ratio of 94.5% of the microcapsule were obtained when the flow rates of the continuous and dispersion fluids were 600 μL min−1 and 24 μL min−1, respectively. It is shown that the phase change material microcapsules were stable after 50 heating/cooling cycles.

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Zhang, Jingjing, Qiuli Huang, Chungui Du, Rui Peng, Yating Hua, Qi Li, Ailian Hu, and Junhui Zhou. "Preparation and Anti-Mold Properties of Nano-ZnO/Poly(N-isopropylacrylamide) Composite Hydrogels." Molecules 25, no. 18 (September 10, 2020): 4135. http://dx.doi.org/10.3390/molecules25184135.

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The aim of this study was to overcome drawbacks of the inhomogeneous dispersion and facile agglomeration of nano-ZnO/poly(N-isopropylacrylamide) composite hydrogels (nano-ZnO/PNIPAm composite hydrogels) during synthesis and improve the anti-mold property of the nano-ZnO/PNIPAm composite hydrogels. Here, nano-ZnO/PNIPAm composite hydrogels were prepared by the radical polymerization method. Fourier transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM), differential scanning calorimeter (DSC), and dynamic light scattering (DLS) were used to characterize the effects of different dispersants on the particle sizes, dispersions, and phase transition characteristics of the nano-ZnO/PNIPAm composite hydrogels. The anti-mold properties of nano-ZnO/PNIPAm composite hydrogels were studied. Results revealed that the nano-ZnO/PNIPAm composite hydrogel prepared by the addition of nano-ZnO dispersion liquid exhibited the smallest particle size, the most homogeneous dispersion, and the highest stability. The addition of the dispersant did not change the phase transition characteristics of nano-ZnO/PNIPAm, and the nano-ZnO/PNIPAm composite hydrogels (Pf) exhibited good anti-mold properties to the bamboo mold.

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Fischer, Ludger, Ernesto Mura, Poppy O'Neill, Silvan von Arx, Jörg Worlitschek, Geng Qiao, Qi Li, and Yulong Ding. "Thermophysical properties of a phase change dispersion for cooling around 50 °c." International Journal of Refrigeration 119 (November 2020): 410–19. http://dx.doi.org/10.1016/j.ijrefrig.2020.05.013.

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Paul, John, Mahendran Samykano, Adarsh Kumar Pandey, Kumaran Kadirgama, and Vineeth Veer Tyagi. "Nano Engineered Paraffin-Based Phase Change Material for Building Thermal Management." Buildings 13, no. 4 (March 29, 2023): 900. http://dx.doi.org/10.3390/buildings13040900.

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Thermal energy storage (TES) and harvesting is an effective technique for optimum building thermal management. Phase-change materials (PCMs) are commonly used for TES applications but are troubled by their degraded thermal conductivity. Recent research progress in latent heat energy storage using PCMs and nano additives provides a viable solution for solar TES. A series of hybrid nano-enhanced phase change materials (HNePCMs) were prepared via two-step synthesis. Hybrid graphene–silver nanofillers were dispersed in commercial paraffin (melting point 25 °C) under different dispersion rates (0.1%, 0.3%, 0.5%). Different characterization techniques, e.g., FESEM, FT-IR, UV-VIS, TGA, XRD, DSC, and Tempos, were used in material characterization. A maximum enhancement of 6.7% in latent heat and 5% in heat storage efficiency was noted for nanocomposites with 0.3 wt% of additives. The nanocomposite with 0.3 Wt% showed great potential in shielding UV rays and showed a reduction of 6.5% in bandgap energy. Furthermore, the thermal conductivity of samples was boosted by a maximum of 90% (from 0.2 W/mK-0.39 W/mK) with 0.3 wt% dispersion of graphene–silver nanofillers. The thermophysical characterization results establish that the synthesized paraffin/graphene–silver hybrid nanocomposites are well suited for building thermal management.

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Njeh, A., D. Schneider, H. Fuess, and M. H. Ben Ghozlen. "Surface Wave Propagation in Thin Silver Films under Residual Stress." Zeitschrift für Naturforschung A 57, no. 1-2 (February 1, 2002): 58–64. http://dx.doi.org/10.1515/zna-2002-1-208.

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Investigations using surface acoustic waves provide information on the elastic properties of thin films. Residual stresses change the phase velocity of the surface waves. We have calculated the phase velocity and dispersion of surface waves in thin silver films with a strong [111]-fibre texture. A non-linear description of surface waves propagating along the [110]-direction of the substrate has been developed on the basis of an acoustoelastic theory, taking into account residual stresses. The relative change Δc/c of the velocity v was found to be linear for large excitation frequencies. The dispersion curves were measured using a photoacoustic method. For sputtered polycrystalline thin silver films we found good agreement between the experimental and calculated dispersion curves for frequencies up to 225 MHz

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Njeh, A., T. Wieder, D. Schneider, H. Fuess, and M. H. Ben Ghozlen. "Surface Wave Propagation in Thin Silver Films under Residual Stress." Zeitschrift für Naturforschung A 57, no. 9-10 (October 1, 2002): 58–64. http://dx.doi.org/10.1515/zna-2002-9-1008.

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Investigations using surface acoustic waves provide information on the elastic properties of thin films. Residual stresses change the phase velocity of the surface waves. We have calculated the phase velocity and dispersion of surface waves in thin silver films with a strong [111]-fibre texture. A non-linear description of surface waves propagating along the [110]-direction of the substrate has been developed on the basis of an acoustoelastic theory, taking into account residual stresses. The relative change Δv/v of the velocity v was found to be linear for large excitation frequencies. The dispersion curves were measured using a photoacoustic method. For sputtered polycrystalline thin silver films we found good agreement between the experimental and calculated dispersion curves for frequencies up to 225 MHz.

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Aksenov, D. A., S. N. Faizova, and I. A. Faizov. "Hardening mechanisms contribution at nonmonotonic change of properties in the Cu–0.6Cr–0.1Zr alloy at high pressure torsion." Frontier materials & technologies, no. 3 (2022): 23–32. http://dx.doi.org/10.18323/2782-4039-2022-3-1-23-32.

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Phase transformations play an important role in the formation of properties in the dispersion-hardened alloys, for example, such as the Cu–Cr–Zr system alloys. It is known that under severe plastic deformation, the diffusion conditions change significantly, which leads to a change in the phase transformation kinetics. In this work, the authors studied the Cu–0.6Cr–0.1Zr alloy in the low concentration solid solution state subjected to high pressure torsion (up to 10 cycles). In this case, due to the solid solution low concentration and the formed ensemble of large particles, the process of solid solution decomposition was excluded at the first stages. The preliminary work on the analysis of such structurally sensitive characteristics as electrical conductivity and lattice parameter made it possible to identify the nonmonotonic nature of a change in the alloying elements concentration in the solid solution during HPT. Nonmonotonicity is related to the significant changes in the characteristics of the second phase particles ensemble under the influence of high voltages. Such significant structural changes are reflected in the nature of the mechanical characteristics change. The authors identified that when increasing the number of HPT revolutions, changes in strength also have a nonmonotonic nature, which corresponds to the nonmonotonic nature of changes in the concentration of alloying elements and electrical conductivity. Various contributions to the Cu–0.6Cr–0.1Zr alloy hardening were analyzed. The analysis identified that the dispersion strengthening contribution plays the main role in the nonmonotonic change in the mechanical characteristics. The calculated data correlate with the obtained experimental results.

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Andiarto, Rizky, Muhammad Khalish Nuryadin, and Rosari Saleh. "Structural and Thermal Properties Investigation of Stearic Acid Dispersed Fe₃O₄/TiO₂ Nanocomposites for Thermal Energy Storage." Materials Science Forum 864 (August 2016): 180–85. http://dx.doi.org/10.4028/www.scientific.net/msf.864.180.

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In this paper, a series of magnetic Stearic acid (Sa)/Fe3O4/TiO2 nanocomposites were synthesized as a functional phase change materials through a two step methods; sol gel method followed by dispersion technique. Fe3O4/TiO2 nanocomposites were first synthesized by varying the molar ratio of Fe3O4:TiO2 from 1:1 to 1:5 followed by dispersing the synthesized Fe3O4/TiO2 nanocomposites in stearic acid (Sa). The structural properties were confirmed by X-ray diffractometer (XRD), while their chemical compositions were determined from energy dispersive X-ray (EDX). The molecular interaction were detected by Fourier transform infrared spectroscopy (FT-IR). Thermal storage capability such as latent heat and specific heat were detected by differential scanning calorimetry (DSC) while high thermal reliability of their phase change performance were detected by thermogravimetric analysis (TGA) experiment. The result shows that the incorporation of nanocomposites Fe3O4/TiO2 enhance the latent heat as well as heat capacity of phase change materials.

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Krishnamoorthy, Venkateskumar, Suchandrasen, and Verma Priya Ranjan Prasad. "Physicochemical characterization and in vitro dissolution behavior of olanzapine-mannitol solid dispersions." Brazilian Journal of Pharmaceutical Sciences 48, no. 2 (June 2012): 243–55. http://dx.doi.org/10.1590/s1984-82502012000200008.

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The objective of the present work is to study the dissolution behavior of olanzapine from its solid dispersions with mannitol. Solid dispersions were prepared by melt dispersion method and characterized by phase solubility studies, drug content and in vitro dissolution studies. The best releasing dispersions were selected from release data, dissolution parameters and their release profiles. Solid state characterization techniques like Fourier transform infrared (FT-IR) spectroscopy, X-ray diffractometry, differential scanning calorimetry, near-infrared and Raman spectroscopy were used to characterize the drug in selected dispersions. The dispersions were also evaluated by wettability studies and permeation studies. The results of phase solubility studies and the thermodynamic parameters indicated the spontaneity and solubilization effect of the carrier. The release study results showed greater improvement of drug release from solid dispersions compared to pure drug, and the release was found to increase with an increase in carrier content. The possible mechanism for increased release rate from dispersions may be attributed to solubilization effect of the carrier, change in crystal quality, phase transition from crystalline to amorphous state, prevention of agglomeration or aggregation of drug particles, change in surface hydrophobicity of the drug, and increased wettability and dispersability of the drug in dissolution medium. The suggested reasons for increased release rate from dispersions were found to be well supported by results of solid state characterization, wettability and permeation studies. The absence of any interaction between the drug and the carrier was also proved by FT-IR analysis.

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Velupula, Teja, Gayathri Devi Amboru, Sneha Chowdary Gundapaneni, Bhavya Kadiyala, Phani Sreenidhi Kanakagiri, Supraja Kari, Vyshnavi Kota, Venkata Ramana Maddula, and Rama Rao Nadendla. "Bioavailability Enhancement of Ritonavir by Solid Dispersion Technique." Journal of Drug Delivery and Therapeutics 11, no. 5 (September 15, 2021): 52–56. http://dx.doi.org/10.22270/jddt.v11i5.4983.

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Ritonavir is an antiretroviral agent used in the treatment of HIV-infection. It is a BCS class IV drug having poor aqueous solubility leading to poor bioavailability. Bioavailability is the amount of drug that enters the systemic circulation. The bioavailability is affected by various factors like solubility, dissolution and stability. In order to improve bioavailability, many techniques like solid dispersions, nanoparticles, liposomes, encapsulation methods were present. The main aim of this study is to improve the bioavailability of ritonavir with the help of Polyvinyl Pyrrolidone (PVP) K-30 by using solid dispersion technique. Different formulations were made with varied concentrations of polymer. Characterization of solid dispersion was done by phase solubility, drug content, Fourier transformed infrared spectroscopy (FT-IR), Differential Scanning Calorimetry (DSC) and in-vitro dissolution studies. From phase solubility studies that apparent solubility constant was found to be 42.227M-1. The drug content of the binary system of ritonavir and PVP was found to be ranging from 99.17% to 103.06%. %. FT-IR studies revealed that there was no drastic change in the wave number indicating polymer compatibility with drug. In-vitro dissolution studies proved that there was an increase in drug release of ritonavir with incremental ratios of polymer and F5 formulation has shown almost 95% of drug release. Keywords: Bioavailability, Solid dispersion, Polyvinyl pyrrolidine, Solvent evaporation, Dissolution.

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Tao, Wen, Xiangfa Kong, Anyang Bao, Chuangang Fan, and Yi Zhang. "Preparation and Phase Change Performance of Graphene Oxide and Silica Composite Na2SO4·10H2O Phase Change Materials (PCMs) as Thermal Energy Storage Materials." Materials 13, no. 22 (November 17, 2020): 5186. http://dx.doi.org/10.3390/ma13225186.

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In this study, a novel nucleating agent composed of graphene oxide (GO) and silicon dioxide (SiO2) (GO–SiO2) is developed. GO is used as a skeleton material through which SiO2 nanomaterials are absorbed and subsequently incorporated into Na2SO4·10H2O phase change materials (PCMs). Furthermore, this study examines the phase change performance of the composite Na2SO4·10H2O materials. Fourier-transform infrared (FTIR) spectra confirmed the physical combination of GO with a SiO2 nanoparticles. Scanning electron microscope (SEM) results showed that the GO–SiO2 composite exhibited a layered structure and excellent dispersibility. The GO–SiO2 composite Na2SO4·10H2O PCMs displayed a low level of supercooling, i.e., about 1.2 °C with the addition of GO–SiO2 at 2.45 wt%. This was because the synergistic relation of the GO and the high dispersion SiO2, imparted more nucleation sites for Na2SO4·10H2O. Additionally, the prepared PCMs achieved high phase change latent heat and thermal conductivity, even under these conditions. The results show that the GO–SiO2 in the Na2SO4·10H2O exhibited advantageous application prospects for the improvement of the thermal performance of hydrate salts.

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Sebti, Seyed, Mohammad Mastiani, Sina Kashani, Hooshyar Mirzaei, and Ahmad Sohrabi. "Numerical study of melting in an annulur enclosure filled with nano-enhanced phase change material." Thermal Science 19, no. 3 (2015): 1067–76. http://dx.doi.org/10.2298/tsci120720022s.

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Heat transfer enhancement during melting in a two-dimensional cylindrical annulus through dispersion of nanoparticle is investigated numerically. Paraffin-based nanofluid containing various volume fractions of Cu is applied. The governing equations are solved on a non-uniform O type mesh using a pressure-based finite volume method with an enthalpy porosity technique to trace the solid and liquid interface. The effects of nanoparticle dispersion into pure fluid as well as the influences of some significant parameters, namely, nanoparticle volume fraction and natural convection on the fluid flow and heat transfer features are studied. The results are presented in terms of streamlines, isotherms, temperatures and velocity profiles and dimensionless heat flux. It is found that the suspended nanoparticles give rise to the higher thermal conductivity as compared to the pure fluid and consequently the heat transfer is enhanced. In addition, the heat transfer rate and the melting time increases and decreases, respectively, as the volume fraction of nanoparticle increases.

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Pakhomov, M. A. "Numerical modeling of the influence of bubbles on flow and heat transfer in the descending gas-liquid flow in a pipe." Proceedings of the Mavlyutov Institute of Mechanics 9, no. 1 (2012): 131–35. http://dx.doi.org/10.21662/uim2012.1.025.

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The paper presents the results of modeling the dynamics of flow, friction and heat transfer in a descending gas-liquid flow in the pipe. The mathematical model is based on the use of the Eulerian description for both phases. The effect of a change in the degree of dispersion of the gas phase at the input, flow rate, initial liquid temperature and its friction and heat transfer rate in a two-phase flow. Addition of the gas phase causes an increase in heat transfer and friction on the wall, and these effects become more noticeable with increasing gas content and bubble diameter.

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Wang, H. Y., V. G. McDonell, and S. Samuelsen. "Influence of Hardware Design on the Flow Field Structures and the Patterns of Droplet Dispersion: Part I—Mean Quantities." Journal of Engineering for Gas Turbines and Power 117, no. 2 (April 1, 1995): 282–89. http://dx.doi.org/10.1115/1.2814092.

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In a gas turbine engine combustor, performance is likely tied to the spatial distribution of the fuel injected into the dome. The GE/SNECMA CFM56 combustor swirl cup is one example of a design established to provide a uniform presentation of droplets to the dome. The present study is part of a series to detail the dispersion of droplets in practical hardware, and to assess the effect of isolated parameters on the continuous- and dispersed-phase distributions. In this study, the influence of the swirling air outlet geometry is evaluated relative to the effect on the flow field structures and the patterns of droplet dispersion. This is accomplished by comparing the continuous-phase (air in the presence of a spray) and dispersed-phase (droplets) behavior downstream of the swirl cup assembly outfitted with two different conical expansions (“flares”). One features a narrow expansion angle, the other possesses a wide expansion angle. Two-component phase-Doppler interferometry was employed to provide the information of droplet size and velocity components as well as continuous-phase velocity components. Photographs of light scattered by droplets from a laser sheet were used for the study of flow field structures. This study reveals that (1) the air stream issued from the narrow flare remains close to the centerline and expands gradually downstream while the air stream issued from the wide flare expands immediately downstream of the swirl cup, and (2) the narrow flare provides weaker droplet dispersion, slower decay of droplet velocities, and finer droplet sizes compared to the wide flare. The results demonstrate that a relatively modest change in flare geometry can create a significant change in the structure of both the continuous and dispersed phases.

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Tian, Ximin, Junwei Xu, Ting-Hui Xiao, Pei Ding, Kun Xu, Yinxiao Du, and Zhi-Yuan Li. "Broadband Generation of Polarization-Immune Cloaking via a Hybrid Phase-Change Metasurface." Photonics 9, no. 3 (March 4, 2022): 156. http://dx.doi.org/10.3390/photonics9030156.

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Metasurface-enabled cloaking offers an alternative platform to render scatterers of arbitrary shapes indiscernible. However, specific propagation phases generated by the constituent elements for cloaking are usually valid for a single or few states of polarization (SOP), imposing serious restrictions on their applications in broadband and spin-states manipulation. Moreover, the functionality of a conventional metasurface cloak is locked once fabricated due to the absence of active elements. Here, we propose a hybrid phase-change metasurface carpet cloak consisting of coupled phase-shift elements setting on novel phase-change material of Ge2Sb2Se4Te1 (GSST). By elaborately arranging meta-atoms at either 0 or 90 degrees on the external surface of the hidden targets, the wavefront of its scattered lights can be thoroughly rebuilt for arbitrary SOP exactly as if the incidence is reflected by a flat ground, ensuring the targets’ escape from polarization-scanning detections. Furthermore, the robustness of phase dispersion of meta-atoms endows the metasurface cloak wideband indiscernibility ranging from 7.55 to 8.35 µm and tolerated incident angles at least within ±25°. By reversibly switching of the phase states of Ge2Sb2Se4Te1, the stealth function of our design can be turned on and off. The generality of our approach will provide a straightforward platform for polarization-immune cloaking, and may find potential applications in various fields such as electromagnetic camouflage and illusion and so forth.

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Zhang, Xiaobin, Jingfeng Li, Jiakai Zhu, and Limin Qiu. "Computational fluid dynamics study on liquefied natural gas dispersion with phase change of water." International Journal of Heat and Mass Transfer 91 (December 2015): 347–54. http://dx.doi.org/10.1016/j.ijheatmasstransfer.2015.07.117.

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Ye, Xue, Hongshuai Cao, Fugang Qi, Xiaoping Ouyang, Zhisong Ye, Caihong Hou, Lianhui Li, Dingfei Zhang, and Nie Zhao. "Effect of Y Addition on the Microstructure and Mechanical Properties of ZM31 Alloy." Materials 13, no. 3 (January 26, 2020): 583. http://dx.doi.org/10.3390/ma13030583.

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Effects of different Y contents (0, 0.3, 0.7, 1.5, 3, 5 and 10 wt.%) on the microstructure, thermal stability and mechanical properties of Mg-3Zn-1Mn (ZM31) alloys were systematically studied. The existence form and action mechanism of Y in the experimental alloys were investigated. The results revealed that with the change of Y content, the main phases of the ZM31-xY alloys changed from Mg7Zn3 phase, I-phase, I + W-phase, W-phase, W + LPSO phase to LPSO phase. When Y content was low (≤1.5%), hot extrusion could break up the residual phases after homogenization to form dispersed fine rare-earth phase particles, and fine second phases would also precipitate in the grain, which could inhibit the grain growth. When Y content was high (≥3%), the experimental alloys were only suitable for high-temperature extrusion due to the formation of the high heat stable rare-earth LPSO phase. In addition, Y could evidently enhance the mechanical properties of the as-extruded ZM31 alloy, of which the ZM31-10Y alloy had the best mechanical properties, that is, the tensile and yield strengths are 403 MPa and 342 MPa. The high strengths of the alloys were mainly determined by fine grain strengthening, rare-earth phase strengthening and dispersion strengthening of fine α-Mn particles.

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Guo, Cha Xiu, and Ya Hui Wang. "Numerical Investigation of Nanoparticle-Enhanced High Temperature Phase Change Material for Solar Energy Storage." Advanced Materials Research 512-515 (May 2012): 961–64. http://dx.doi.org/10.4028/www.scientific.net/amr.512-515.961.

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In order to store the solar energy efficiently, high temperature phase change material (HTPCM) through dispersion of nanoparticles is reported. Based on the enthalpy-porosity approach, the numerical model is first validated by comparing the results of the reference. Then the melting processes of HTPCM with different mass fraction nanoparticles in an enclosure are conducted. Results show that nanoparticles can greatly increase melting rate, compared with that of HTPCM, so nanoparticle-enhanced phase high temperature change material (NEHTPCM) has a promising application for solar energy storage.

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Piątkowski, Jarosław, and Robert Wieszała. "Crystallization and Structure of AlSi10Mg0.5Mn0.5 Alloy with Dispersion Strengthening with Al–FexAly–SiC Phases." Metals 9, no. 8 (August 8, 2019): 865. http://dx.doi.org/10.3390/met9080865.

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The paper characterizes a composite with dispersion phases cast via the use of stir casting method on an aluminum matrix. A mixture of aluminum with FexAly and SiC powders was achieved in the process of mechanical alloying and self-propagating high temperature synthesis (ASHS). Chemical composition of agglomerates was chosen in such a way that the strengthening components made up 25% of the mass of the AlSi10Mg0.5Mn0.6 (EN AC-43400) alloy matrix. The characteristic temperatures of crystallization of the tested alloy were measured by thermal analysis ATD (analysis thermal derivative). A change of chemical and phase composition was confirmed in the elements of the intermetallic phase FeAl in the aluminum matrix. A silumin casting structure was achieved, with the matrix including micro-areas of ceramic phases and intermetallic phases, which are characteristic for hybrid strengthening. A refinement of dendrites in solid solution α was found, together with a transition from a binary plate eutectic composition α(Al) + β(Si) into modified eutectic composition.

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Murayama, M., L. Reich, and K. Hono. "Clustering and Segregation of Ag and Mg Atoms in the Nucleation and Growth Stage of Ω And T1 Precipitates In Al-Cu(-Li) Alloys." Microscopy and Microanalysis 4, S2 (July 1998): 116–17. http://dx.doi.org/10.1017/s1431927600020705.

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Trace additions of Ag and Mg in Al-Cu and Al-Li-Cu alloys change the precipitation processes drastically. In Al-Cu-Mg-Ag alloy, plate-like Ω phase precipitates on the {111} matrix planes. Similarly, additions of Ag and Mg to Al-Li-Cu alloy cause uniform dispersion of the T1 precipitate on the {111} matrix planes. Ω and T1 phases are structurally and morphologically similar, and a similar mechanism is expected to work in both alloy systems to enhance uniform dispersion of the plate-like precipitates on the {111} planes. A previous atom probe work [1] reported that Ag and Mg are segregated at the αΩ. interfaces in an Al-Cu-Mg-Ag alloy. In an Al-Li-Cu-Mg-Ag alloy, Ag and Mg atoms were found to be incorporated with the T, phase [2]; however, because of the thinness of the T1, plate, the exact location of these atoms with respect to the T1, phase could not be determined sucessfully by a conventional atom probe.

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Zimmermann, Charlotte, Taija L. Fischer, and Martin A. Suhm. "Pinacolone-Alcohol Gas-Phase Solvation Balances as Experimental Dispersion Benchmarks." Molecules 25, no. 21 (November 3, 2020): 5095. http://dx.doi.org/10.3390/molecules25215095.

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The influence of distant London dispersion forces on the docking preference of alcohols of different size between the two lone electron pairs of the carbonyl group in pinacolone was explored by infrared spectroscopy of the OH stretching fundamental in supersonic jet expansions of 1:1 solvate complexes. Experimentally, no pronounced tendency of the alcohol to switch from the methyl to the bulkier tert-butyl side with increasing size was found. In all cases, methyl docking dominates by at least a factor of two, whereas DFT-optimized structures suggest a very close balance for the larger alcohols, once corrected by CCSD(T) relative electronic energies. Together with inconsistencies when switching from a C4 to a C5 alcohol, this points at deficiencies of the investigated B3LYP and in particular TPSS functionals even after dispersion correction, which cannot be blamed on zero point energy effects. The search for density functionals which describe the harmonic frequency shift, the structural change and the energy difference between the docking isomers of larger alcohols to unsymmetric ketones in a satisfactory way is open.

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Lei, Xun, Zenghui Gu, Jianbin Ma, Guanshi Qin, Zhanguo Chen, and Shaowu Chen. "Investigation of the local dispersion change in anomalous dispersion microcavity and quantitative analysis of the phase-matching in Kerr comb generation." Applied Optics 56, no. 16 (May 31, 2017): 4828. http://dx.doi.org/10.1364/ao.56.004828.

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Aftandiliants, Ye G. "Modelling of structure forming in structural steels." Naukovij žurnal «Tehnìka ta energetika» 11, no. 4 (September 10, 2020): 13–22. http://dx.doi.org/10.31548/machenergy2020.04.013.

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The study showed that the influence of alloying elements on the secondary structure formation of the steels containing from 0.19 to 0.37 wt. % carbon; 0.82-1.82 silicon; 0.63-3.03 manganese; 1.01-3.09 chromium; 0.005-0.031 nitrogen; up to 0.25 wt.% vanadium and austenite grain size is determined by their change in the content of vanadium nitride phase in austenite, its alloying and overheating above tac3, and the dispersion of ferrite-pearlite, martensitic and bainitic structures is determined by austenite grain size and thermal kinetic parameters of phase transformations. Analytical dependencies are defined that describe the experimental data with a probability of 95% and an error of 10% to 18%. An analysis results of studying the structure formation of structural steel during tempering after quenching show that the dispersion and uniformity of the distribution of carbide and nitride phases in ferrite is controlled at complete austenite homogenization by diffusion mobility and the solubility limit of carbon and nitrogen in ferrite, and secondary phase quantity in case of the secondary phase presence in austenite more than 0.04 wt. %. Equations was obtained which, with a probability of 95% and an error of 0.7 to 2.6%, describe the real process.

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Dalgetty, Laura, and Malcolm W. Kennedy. "Building a home from foam—túngara frog foam nest architecture and three-phase construction process." Biology Letters 6, no. 3 (January 27, 2010): 293–96. http://dx.doi.org/10.1098/rsbl.2009.0934.

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Frogs that build foam nests floating on water face the problems of over-dispersion of the secretions used and eggs being dangerously exposed at the foam : air interface. Nest construction behaviour of túngara frogs, Engystomops pustulosus , has features that may circumvent these problems. Pairs build nests in periodic bursts of foam production and egg deposition, three discrete phases being discernible. The first is characterized by a bubble raft without egg deposition and an approximately linear increase in duration of mixing events with time. This phase may reduce initial over-dispersion of foam precursor materials until a critical concentration is achieved. The main building phase is marked by mixing events and start-to-start intervals being nearly constant in duration. During the final phase, mixing events do not change in duration but intervals between them increase in an exponential-like fashion. Pairs joining a colonial nesting abbreviate their initial phase, presumably by exploiting a pioneer pair's bubble raft, thereby reducing energy and material expenditure, and time exposed to predators. Finally, eggs are deposited only in the centre of nests with a continuously produced, approximately 1 cm deep egg-free cortex that protectively encloses hatched larvae in stranded nests.

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42

Lv, Xifeng, Xuehua Shen, Luxiang Zhang, Yazhou Wang, and Fang Wang. "Preparation of Organic-Inorganic Coupling Phase Change Materials with Enhanced Thermal Storage Performance via Emulsion Polymerization." Materials 15, no. 9 (May 8, 2022): 3373. http://dx.doi.org/10.3390/ma15093373.

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The serious phase separation in inorganic phase change materials, and easy leakage of organic phase change materials are the main obstacles to the practical batch application of phase change heat storage materials. To solve these problems, in this work, emulsion polymerization is introduced as the method for preparing organic-inorganic coupling phase change material (oic-PCM) with high heat storage performance using polyacrylamide (PAM) as the wall material and organic phase change material of cetyl alcohol as the core material, and diatomite is used as a supporting substrate to absorb inorganic sodium sulfate decahydrate (SSD). A differential scanning calorimeter (DSC), X-ray diffractometer (XRD), dust morphology and dispersion analyzer, and thermal conductivity tester were used to characterize the prepared organic-inorganic coupled phase change materials and investigate their performance. The research results show that when the mass fraction of cetyl alcohol is 68.97%, the mass fraction of emulsifier is 3.38%, and the mass fraction of sodium sulfate decahydrate/diatomite is 3.40%. The phase change latent heat of the organic-inorganic coupled phase change material is as high as 164.13 J/g, and the thermal conductivity reaches up to 0.2061 W/(m·k), which proves that the prepared organic-inorganic coupled phase change material has good heat storage performance, showing its good application prospects.

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Zhang, Yu, and Shengnian Tie. "Preparation and Rheological Properties of Amide-based Multiwalled Carbon Nanotube Mirabilite Phase Change Materials." Scientific and Social Research 3, no. 2 (July 13, 2021): 86–91. http://dx.doi.org/10.36922/ssr.v3i2.1109.

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The multi-walled carbon nanotubes (MWCNTs) are modified by redox methods, and the surface groups of the MWCNTs are analyzed by infrared spectroscopy. And the modified MWCNTs were added to the mirabilite-based phase change materials (PCMs) at 40°C to prepare the mirabilite-based phase change composite material. The results show that when the volume fraction is 0.05% and 0.25%, when the temperature rises from 30°C to 50°C, the viscosity drop of the phase change composite material is 35.86% and 37.50%, respectively. That is, the larger the volume of the fraction of nanoparticles, the higher the viscosity, thus the greater the ability to perceive temperature fluctuations. In addition, the amide multiwalled carbon nanotube mirabilite PCMs was placed for 30 days, and the dispersion stability was good, and no phase delamination occurred.

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Shutyi A. M., Sementsov D. I., and Eliseeva S. V. "Mode bistability of plasmons and dispersive jump in a structure with two graphene layers." Physics of the Solid State 64, no. 6 (2022): 726. http://dx.doi.org/10.21883/pss.2022.06.53839.259.

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Plasmon modes in a symmetric structure consisting of two layers of inverted graphene separated by a dielectric barrier layer and their dispersion properties are studied for various parameters of the barrier layer. The occurrence of a bifurcation of the splitting of the branch of the dispersion dependence, which leads to the appearance of bistability and a dispersion jump with a change in the stability of the branches included in the bistability, is found. The plasmonic modes belonging to the two branches of the bistable state differ in the gain increment and phase velocity, and their group velocities are opposite in sign. Keywords: inverted graphene, three-layer structure, branching bifurcation, modal bistability, amplifying modes, dispersion dependence jump.

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Шутый, А. М., Д. И. Семенцов, and С. В. Елисеева. "Модовая бистабильность плазмонов и дисперсионный скачок в структуре с двумя графеновыми слоями." Физика твердого тела 64, no. 6 (2022): 724. http://dx.doi.org/10.21883/ftt.2022.06.52407.259.

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Plasmon modes in a symmetric structure consisting of two layers of inverted graphene separated by a dielectric barrier layer and their dispersion properties are studied for various parameters of the barrier layer. The occurrence of a bifurcation of the splitting of the branch of the dispersion dependence, which leads to the appearance of bistability and a dispersion jump with a change in the stability of the branches included in the bistability, is found. The plasmonic modes belonging to the two branches of the bistable state differ in the gain increment and phase velocity, and their group velocities are opposite in sign.

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Yang, Chunying, and Wenchuang Wang. "Azimuthal multiple signal classification of dispersive and aliased surface waves recorded in 3D seismic acquisition." GEOPHYSICS 87, no. 2 (January 10, 2022): V87—V100. http://dx.doi.org/10.1190/geo2020-0417.1.

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Irregular acquisition geometry causes discontinuities in the appearance of surface wave events, and a large offset causes seismic records to appear as aliased surface waves. The conventional method of sampling data affects the accuracy of the dispersion spectrum and reduces the resolution of surface waves. At the same time, “mode kissing” of the low-velocity layer and inhomogeneous scatterers requires a high-resolution method for calculating surface wave dispersion. This study tests the use of the multiple signal classification (MUSIC) algorithm in 3D multichannel and aliased wavefield separation. Azimuthal MUSIC is a useful method to estimate the phase velocity spectrum of aliased surface wave data, and it represents the dispersion spectra of low-velocity and inhomogeneous models. The results of this study demonstrate that the mode kissing affects dispersion imaging, and inhomogeneous scatterers change the direction of surface-wave propagation. Surface waves generated from the new propagation directions also are dispersive. The scattered surface wave has a new dispersion pattern different from that of the entire record. Diagonal loading is introduced to improve the robustness of azimuthal MUSIC, and numerical experiments demonstrate the resultant effectiveness of imaging aliasing surface waves. A phase-matched filter is applied to the results of azimuthal MUSIC, and phase iterations are unwrapped in a fast and stable manner. Aliased surface waves and body waves are separated during this process. Overall, field data demonstrate that the azimuthal MUSIC and the phase-matched filters can successfully separate aliased surface waves.

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Wilson, John, Abhishek Singh, Abhinay Singh, and Subramanian Ganapathy. "Waste heat recovery from diesel engine using custom designed heat exchanger and thermal storage system with nanoenhanced phase change material." Thermal Science 21, no. 1 Part B (2017): 715–27. http://dx.doi.org/10.2298/tsci160426264w.

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In this research study an attempt has been made to recover the heat energy of the exhaust gas from a Diesel engine, using a triangular finned shell and tube heat exchanger with segmental baffle at 20?, and efficiently store as sensible and latent heat energy using thermal storage tank having phase change material with CuO nanoparticles. The nanoparticles and the phase change material form the nanoparticle-enhanced phase change material and mainly the thermal conductivity of the phase change material can be enhanced through the dispersion of the nanoparticles. The temperature variations of the heat transfer fluid in the heat recovery heat exchanger with various load conditions of the Diesel engine are studied. The performance of the heat exchanger is evaluated using heat extraction rate and effectiveness. Evaluation of the performance of the thermal storage system can be analyzed by using the total heat energy stored and charging rate during the charging period for the selected nanoparticle-enhanced phase change material.

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Radha, Ramaswamy, and Vaduganathan Ramesh Kumar. "Interplay Between Dispersion and Nonlinearity in Femtosecond Soliton Management." Zeitschrift für Naturforschung A 65, no. 6-7 (July 1, 2010): 549–54. http://dx.doi.org/10.1515/zna-2010-6-710.

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In this paper, we investigate the inhomogeneous higher-order nonlinear Schr¨odinger (NLS) equation governing the femtosecond optical pulse propagation in inhomogeneous fibers using gauge transformation and generate bright soliton solutions from the associated linear eigenvalue problem. We observe that the amplitude of the bright solitons depends on the group velocity dispersion (GVD) and the self-phase modulation (SPM) while its velocity is dictated by the third-order dispersion (TOD) and GVD. We have shown how the interplay between GVD, SPM, and TOD can be profitably exploited to change soliton width, amplitude (intensity), shape, phase, velocity, and energy for an effective femtosecond soliton management. The highlight of our paper is the identification of ‘optical similaritons’ arising by virtue of higher-order effects in the femtosecond regime.

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Wang, Bo, Xijin Luo, Qinghong Sheng, and Zhijun Yan. "The Effect of Martian Ionospheric Dispersion on SAR Imaging." Space: Science & Technology 2022 (July 26, 2022): 1–13. http://dx.doi.org/10.34133/2022/9860932.

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When passing through the ionosphere, the high-frequency (HF) pulse signal of the Mars Exploration Radar is affected by the dispersion effect error, which results in signal attenuation and time delay and brings about a phase advance in such a way that the echo cannot be matched and filtered. In this paper, a high-order phase model is built to overcome the above problems and enable echo matching and filtering. Most studies on the dispersion effect approximate the additional phase after the effect, assuming that the ionosphere is a thin-layer structure. In this paper, an effective model for the HF waveband is constructed to analyze the change of signal propagation paths in the ionosphere. The additional phase is expanded in a Taylor series and retained these expansions as high-order terms to calculate the cumulative additional phase along the path. We show the range-offset variables of signal frequency, bandwidth, and electron density, simulate the effects of the ionosphere under different conditions, and conclude that the model can effectively estimate Mars without considering the effects of magnetic fields and anomalous solar activity and the effect of the ionosphere on synthetic aperture radar (SAR) echoes. The results obtained using ray tracing calculations are different from those obtained by simplifying assumptions, and we can simulate the Martian ionospheric effects by the former.

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Niu, Xiaofeng, Ruifeng Xia, Honglin Dong, Dandan Wang, Dichang Duan, Peng Gao, and Risto Kosonen. "Dispersion stability and thermophysical properties of microencapsulated phase change material slurry for liquid desiccant dehumidification." Energy and Buildings 240 (June 2021): 110870. http://dx.doi.org/10.1016/j.enbuild.2021.110870.

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Journal articles on the topic 'Phase change dispersion'

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