Journal articles: 'Dispersion de charges'

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Yaakob, Muhamad Kamil, Mohamad Faris M. Taib, and Muhd Zu Azhan Yahya. "First Principle Study of Dynamical Properties of a New Perovskite Material Based on GeTiO₃." Advanced Materials Research 501 (April 2012): 352–56. http://dx.doi.org/10.4028/www.scientific.net/amr.501.352.

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The dynamical properties of a new perovskite GeTiO3 materials have been investigated by using first principle calculation based on Density Functional Theory (DFT) within the gradient generalized approximation (GGA). All calculations were performed using the Cambridge Serial Total Energy Package (CASTEP) computer code. The calculations include the structural parameter, Born effective charges, and phonon dispersion. The calculated Born effective charges and phonon dispersion have been analyzed and the possibility of ferroelectric feature in GeTiO3 compounds has been discussed. From the analysis, the calculated Born effective charge ZGe and ZTi showed large anomaly compared to the nominal charge which contributed to the large atomic displacement. The calculated phonon dispersion showed the most unstable mode was at G point and the unstable modes were dominated by Ge branch. The dynamical properties and ferroelectric properties in GeTiO3 are discussed and compared with the ferroelectric feature in PbTiO3.

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Koné, M., P. Courtin, and J. Lemerle. "Colloidal molybdoantimonic acids as ion exchangers." Canadian Journal of Chemistry 69, no. 2 (February 1, 1991): 293–99. http://dx.doi.org/10.1139/v91-045.

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Colloidal particles with a c.c.p. structure were obtained from mixtures of antimonic and molybdic acids through a polymerization process. These particles were octahedral and their sizes fits the log-normal distributions. The mean size decreases and the polydispersity increases with increasing Mo content in the particles. The stability of the aqueous dispersions was due to the surface charge density of the particles which was enhanced when increasing the Mo content. Ion exchange reactions can occur with the dispersions. Two different routes lead to Ag+ fixation: substitution of core H+ without flocculation of the dispersion or cancellation of external charges with flocculation. Key words: inorganic exchangers, colloids, antimonic acid, molybdic acid.

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Mukherjee, Siddhartha, Jayabrata Dhar, Sunando DasGupta, and Suman Chakraborty. "Patterned surface charges coupled with thermal gradients may create giant augmentations of solute dispersion in electro-osmosis of viscoelastic fluids." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 475, no. 2221 (January 2019): 20180522. http://dx.doi.org/10.1098/rspa.2018.0522.

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Augmenting the dispersion of a solute species and fluidic mixing remains a challenging proposition in electrically actuated microfluidic devices, primarily due to an inherent plug-like nature of the velocity profile under uniform surface charge conditions. While a judicious patterning of surface charges may obviate some of the concerning challenges, the consequent improvement in solute dispersion may turn out to be marginal. Here, we show that by exploiting a unique coupling of patterned surface charges with intrinsically induced thermal gradients, it may be possible to realize giant augmentations in solute dispersion in electro-osmotic flows. This is effectively mediated by the phenomena of Joule heating and surface heat dissipation, so as to induce local variations in electrical properties. Combined with the rheological premises of a viscoelastic fluid that are typically reminiscent of common biofluids handled in lab-on-a-chip-based micro-devices, our results demonstrate that the consequent electro-hydrodynamic forcing may open up favourable windows for augmented hydrodynamic dispersion, which has not yet been unveiled.

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Bauer, Rachel, Paul Pitzel, Emily Johnson, and Catherine Johnson. "Water-Cased Kicker Charges for Use in Explosive Demolition." Buildings 13, no. 2 (January 29, 2023): 378. http://dx.doi.org/10.3390/buildings13020378.

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Demolition projects involving explosives often incorporate cutting charges to sever columns in conjunction with kicker charges that “move” the columns out of alignment. Traditional kicker charges use dynamite secured to the column above a linear-shaped cutting charge. This study investigates the use of water-cased kicker charges for use in explosive demolition. The goal is to reduce the fragmentation of steel members and the quantity of explosive needed due to the increased density, incompressibility, and impedance mismatch water provides. Simulations and experimental tests were utilized to determine what type of charges provide the optimal column movement and water placement. Water charges and traditional charges were placed on hanging steel columns that swung freely from a top pivot and analyzed for the fragmentation and velocity of the column. Tests were recorded with high-speed video to calculate velocity and impulse. Simulations showed the same results as experimental tests, with water-cased charges moving the column faster and with more impulse than traditional charges. Experimental testing showed that water-cased charges moved the column 53% faster than traditional in contact charges while simulations showed that water-cased charges moved the column 43% faster than traditional in contact charges. Simulations showed the water tamped behind the charge increased beam velocity 32% while water in front of the charge reduced pressure 38% through dispersion.

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Chen, Lucy Huajing, Jayanthi Krishnan, and Heibatollah Sami. "Goodwill Impairment Charges and Analyst Forecast Properties." Accounting Horizons 29, no. 1 (October 1, 2014): 141–69. http://dx.doi.org/10.2308/acch-50941.

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SYNOPSIS We examine the association between goodwill impairment charges and analysts' forecast accuracy and dispersion. We compare a test sample of firm-quarters with reported goodwill impairment charges during 2003–2007, and two control samples (matched on propensity scores and performance) of firm-quarters that do not report impairment charges. We find that analysts' forecasts are less accurate and more dispersed for the impairment sample than for the control samples. The magnitude of impairment charges is also negatively associated with forecast accuracy and positively associated with forecast dispersion. However, two forms of monitoring, auditor industry specialization and institutional ownership, reduce the adverse effect of goodwill impairments on analyst forecast dispersion. JEL Classifications: G14; M41; M44

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Verheest, F. "On the nonexistence of large amplitude stationary solitary waves in symmetric unmagnetized pair plasmas." Nonlinear Processes in Geophysics 12, no. 5 (June 9, 2005): 569–74. http://dx.doi.org/10.5194/npg-12-569-2005.

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Abstract. Waves in pair plasmas have a fundamentally different dispersion due to the equal charge-to-mass ratios between negative and positive charges. In view of possible applications e.g. to electron-positron and fullerene pair plasmas, it is shown that there are no stationary large amplitude nonlinear structures in symmetric unmagnetized pair plasmas.

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Chun, Byoungjin, and Myung-Suk Chun. "Electrostatic Potential Analysis in Polyelectrolyte Brush-Grafted Microchannels Filled with Polyelectrolyte Dispersion." Micromachines 12, no. 12 (November 29, 2021): 1475. http://dx.doi.org/10.3390/mi12121475.

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In this study, the model framework that includes almost all relevant parameters of interest has been developed to quantify the electrostatic potential and charge density occurring in microchannels grafted with polyelectrolyte brushes and simultaneously filled with polyelectrolyte dispersion. The brush layer is described by the Alexander-de Gennes model incorporated with the monomer distribution function accompanying the quadratic decay. Each ion concentration due to mobile charges in the bulk and fixed charges in the brush layer can be determined by multi-species ion balance. We solved 2-dimensional Poisson–Nernst–Planck equations adopted for simulating electric field with ion transport in the soft channel, by considering anionic polyelectrolyte of polyacrylic acid (PAA). Remarkable results were obtained regarding the brush height, ionization, electrostatic potential, and charge density profiles with conditions of brush, dispersion, and solution pH. The Donnan potential in the brush channel shows several times higher than the surface potential in the bare channel, whereas it becomes lower with increasing PAA concentration. Our framework is fruitful to provide comparative information regarding electrostatic interaction properties, serving as an important bridge between modeling and experiments, and is possible to couple with governing equations for flow field.

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ALÌ, GIUSEPPE, GIOVANNI MASCALI, VITTORIO ROMANO, and ROSA CLAUDIA TORCASIO. "A hydrodynamical model for covalent semiconductors with a generalized energy dispersion relation." European Journal of Applied Mathematics 25, no. 2 (January 31, 2014): 255–76. http://dx.doi.org/10.1017/s0956792514000011.

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We present the first macroscopical model for charge transport in compound semiconductors to make use of analytic ellipsoidal approximations for the energy dispersion relationships in the neighbours of the lowest minima of the conduction bands. The model considers the main scattering mechanisms charges undergo in polar semiconductors, that is the acoustic, polar optical, intervalley non-polar optical phonon interactions and the ionized impurity scattering. Simulations are shown for the cases of bulk 4H and 6H-SiC.

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AGOSTINI, ALESSANDRA. "COVARIANT FORMULATION OF NOETHER'S THEOREM FOR κ-MINKOWSKI TRANSLATIONS." International Journal of Modern Physics A 24, no. 07 (March 20, 2009): 1333–58. http://dx.doi.org/10.1142/s0217751x09042943.

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The problem of finding a formulation of Noether's theorem in noncommutative geometry is very important in order to obtain conserved currents and charges for particles in noncommutative space–times. In this paper, we formulate Noether's theorem for translations of κ-Minkowski noncommutative space–time on the basis of the five-dimensional κ-Poincaré covariant differential calculus. We focus our analysis on the simple case of free scalar theory. We obtain five conserved Noether currents, which give rise to five energy–momentum charges. By applying our result to plane waves it follows that the energy–momentum charges satisfy a special-relativity dispersion relation with a generalized mass given by the fifth charge. In this paper, we provide also a rigorous derivation of the equation of motion from Hamilton's principle in noncommutative space–time, which is necessary for the Noether analysis.

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BURKIN, Viktor V., Aleksey S. D’YACHKOVSKIY, Aleksandr N. ISHCHENKO, Vladimir Z. KASIMOV, Konstantin S. ROGAEV, and Nina M. SAMOROKOVA. "STUDY OF THE PASTE-LIKE PROPELLANT COMBUSTION AT VARIOUS LOADING SCHEMES." Vestnik Tomskogo gosudarstvennogo universiteta. Matematika i mekhanika, no. 67 (2020): 89–101. http://dx.doi.org/10.17223/19988621/67/9.

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The experimental and theoretical studies of the paste-like propellant combustion in a model ballistic installation are implemented. The research is carried out using three masses of projectile assemblies and three types of the propellant charge. The paper presents two versions of the law of dispersion for paste-like propellants which allow accounting for the pressure on the front and acceleration of the projectile assembly with a traveling charge. The coefficients in the laws of dispersion are obtained. Using the mathematical model presented in this work, the gas-dynamic pictures of the shots when the propellants are applied as traveling charges are obtained for each dispersion law. Based on the results, a detailed study of the processes occurring with the traveling charge consisting of a model paste-like propellant is implemented for various shot arrangements. The discrepancy between theoretical results and the results obtained in the set of experiments is no more than 2% for the maximum pressure and no more than 1% for the muzzle velocity. The dispersion law accounting for the projectile assembly acceleration and traveling charge makes it possible to describe accurately the processes in the space behind the projectile for projectile assemblies of various masses and different types of granulated powder charge in terms of the model ballistic installation in the considered pressure range.

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Rogaev, K. S., A. N. Ishchenko, V. V. Burkin, A. S. D’yachkovskiy, A. D. Sidorov, and E. Yu Stepanov. "A STUDY OF THE COMBUSTION OF HIGH-DENSITY PROPELLANTS IN A MODEL BALLISTIC INSTALLATION." Vestnik Tomskogo gosudarstvennogo universiteta. Matematika i mekhanika, no. 69 (2021): 127–38. http://dx.doi.org/10.17223/19988621/69/10.

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In internal ballistics of barrel systems, a promising trend is related to the increasing of projectile muzzle velocity by means of high-energy propellants utilized as a traveling charge. The use of a loading scheme with a traveling charge allows one to increase the loading density and to redistribute the energy of powder gases in the space behind the projectile, which leads to a significant increase in the muzzle velocity of the projectile. To attain the listed advantages, it is necessary to know the laws of dispersion and combustion of the propellants used as traveling charges, providing non-digressive gas entry into the charge space. In this work, a comprehensive experimental and theoretical study of the laws of dispersion and combustion of high-density propellants under dynamic pressures, provided in a model ballistic installation, is carried out. The main ballistic characteristics of shots are obtained, which use a classic scheme of loading with a propellant charge made of pyroxylin powder and a scheme with a traveling charge, where, in addition to the propellant charge, a high-density propellant is included. All the experiments are simulated in a software package, taking into account the presence of the high-density propellants in the propellant charge, dispersing into individual particles that burn out while moving along the barrel. As a result of comparing the calculated and experimental data, plausible patterns of the distribution of gas-dynamic parameters are obtained using the classic loading scheme and the loading scheme with a travelling high-density propellant charge.

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Zhao, Li Hong, Jian Rong Hu, and Bei Hai He. "Effect of Electrical Characteristics Modification on Viscosity of Kaolin Suspension." Advanced Materials Research 335-336 (September 2011): 1262–66. http://dx.doi.org/10.4028/www.scientific.net/amr.335-336.1262.

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Modifications of the interfacial electrical characteristics of kaolin were investigated through reversing particles surface charges induced by organic cationic polyelectrolyte and natural anionic organic substance. Zeta potential and rheology tests indicated that polymeric OH-Al reversed the edge charges and reached a saturation adsorption on kaolin surface at dosage of 45μmol/g, corresponding to a lower viscosity of kaolin suspension, as a result of the combined action of OH-Al modified positive particle surface and negative charges from sodium hexametaphosphate dispersant. A significant reduction in viscosity of kaolin modified by gallic acid was also observed in either dilute or concentrated suspension. The strong interaction of OH-Al ions with clay greatly increased the gallic acid adsorption, and resulted in the lowest viscosity for modified kaolin, indicating the bound of gallic acid to the reactive surface sites induced by OH-Al. It can be concluded in this experiments that the highly charged organic coating play a role in the dispersion of kaolin particles.

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RIAHI, SIAVASH, MOHAMMAD REZA GANJALI, and PARVIZ NOROUZI. "QUANTUM MECHANICAL DESCRIPTION OF THE INTERACTIONS BETWEEN DNA AND 9,10-ANTHRAQUINONE." Journal of Theoretical and Computational Chemistry 07, no. 03 (June 2008): 317–29. http://dx.doi.org/10.1142/s0219633608003770.

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Molecular geometries of the 9,10-anthraquinone (AQ) and DNA bases (Adenine, Guanine, Cytosine, and Thymine) were optimized using B3LYP/6-31G** method. Properties of isolated intercalator (9,10-anthraquinone) and their stacking interactions with adenine ⋯ thymine (AT) and guanine ⋯ cytosine (GC) nucleic acid base pairs were investigated by means of DFTB method. DFTB method, an approximate version of the DFT method, was extended to cover London dispersion energy. AQ exhibits a large charge delocalization and it has no site with dominant charge. This intercalator has a large polarizability and is a good electron acceptor, while base pairs are good electron donors. B3LYP/6-31G** stabilization energies of intercalator ⋯ base pair complexes are large (-18.83 kcal/mol for AT ⋯ AQ and -15.69 kcal/mol for GC ⋯ AQ). It is concluded that, the dispersion energy predominantly contributes to the stability of intercalator ⋯ DNA base pair complexes. Any procedure which does not cover dispersion energy is thus not suitable for studying the process of intercalation. The results showed that AQ changes the structure of DNA on bond length, bond angle, torsion angle, and charges.

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Khudaiberganov, T., D. Bukharov, and S. Arakelian. "Deformation mechanism coherent migration of charges in thin film." Journal of Physics: Conference Series 2131, no. 5 (December 1, 2021): 052088. http://dx.doi.org/10.1088/1742-6596/2131/5/052088.

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Abstract We present new mechanism of the charge transport in thin films based on coherent migration of the deformation of the nanoclusters potential, which carries with it an electron. We represent correlation between deformation and charges as the distorton-inverson quasiparticle. This effect is based on the inversion of the potential energy of nanoclusters due to the Jahn-Teller effect in a nanocluster, when charges flow in a network of nanoclusters. The distorton-inverson is quasiparticle are consisted the distorton and electron or hole, this quasiparticle similar an inverson in the Watkins effect. A distorton is quasiparticle which appears itself in the effects of deformation of the potential of the nanocluster with not closed shell. This quasiparticle is similar a defecton in the Watkins effect. We are calculated transmission spectrum and dispersion properties this quasiparticle.

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Marchuk, Alla, Pichu Rengasamy, and Ann McNeill. "Influence of organic matter, clay mineralogy, and pH on the effects of CROSS on soil structure is related to the zeta potential of the dispersed clay." Soil Research 51, no. 1 (2013): 34. http://dx.doi.org/10.1071/sr13012.

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The high proportion of adsorbed monovalent cations in soils in relation to divalent cations affects soil structural stability in salt-affected soils. Cationic effects on soil structure depend on the ionic strength of the soil solution. The relationships between CROSS (cation ratio of soil structural stability) and the threshold electrolyte concentration (TEC) required for the prevention of soil structural problems vary widely for individual soils even within a soil class, usually attributed to variations in clay mineralogy, organic matter, and pH. The objective of the present study was to test the hypothesis that clay dispersion influenced by CROSS values depends on the unique association of soil components, including clay and organic matter, in each soil affecting the net charge available for clay–water interactions. Experiments using four soils differing in clay mineralogy and organic carbon showed that clay dispersion at comparable CROSS values depended on the net charge (measured as negative zeta potential) of dispersed clays rather than the charge attributed to the clay mineralogy and/or organic matter. The effect of pH on clay dispersion was also dependent on its influence on the net charge. Treating the soils with NaOH dissolved the organic carbon and increased the pH, thereby increasing the negative zeta potential and, hence, clay dispersion. Treatment with calgon (sodium hexametaphosphate) did not dissolve organic carbon significantly or increase the pH. However, the attachment of hexametaphosphate with six charges on each molecule greatly increased the negative zeta potential and clay dispersion. A high correlation (R2 = 0.72) was obtained between the relative clay content and relative zeta potential of all soils with different treatments, confirming the hypothesis that clay dispersion due to adsorbed cations depends on the net charge available for clay–water interactions. The distinctive way in which clay minerals and organic matter are associated and the changes in soil chemistry affecting the net charge cause the CROSS–TEC relationship to be unique for each soil.

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Biais, Pauline, Patricia Beaunier, François Stoffelbach, and Jutta Rieger. "Loop-stabilized BAB triblock copolymer morphologies by PISA in water." Polymer Chemistry 9, no. 35 (2018): 4483–91. http://dx.doi.org/10.1039/c8py00914g.

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Klimovich, B. V., and V. V. Nelaev. "Variable charges at govalent bonds and phonon dispersion in silicon." Soviet Physics Journal 31, no. 7 (July 1988): 599–602. http://dx.doi.org/10.1007/bf00917558.

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VERHEEST, FRANK, P. K. SHUKLA, N. N. RAO, and PETER MEURIS. "Dust-acoustic waves in self-gravitating dusty plasmas with fluctuating dust charges." Journal of Plasma Physics 58, no. 1 (July 1997): 163–70. http://dx.doi.org/10.1017/s0022377897005722.

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It is shown that the recently published work of Pandey and Dwivedi [J. Plasma Phys. 55, 395 (1996)] dealing with dust-acoustic waves in a self-gravitating unmagnetized dusty plasma is erroneous. This is demonstrated on the basis of a dispersion relation in which gravitational and electrostatic forces are kept on an equal footing. Furthermore, a general linear dispersion relation for the dust-acoustic and dust-ion acoustic waves in self-gravitating dusty plasmas is obtained, taking into account the dust-charge perturbations. Specific results for limiting cases are discussed.

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Zou, Z. B., R. Q. Wu, and Y. F. Zhao. "Na2HeO: A possible helium compound from first-principles study." International Journal of Computational Materials Science and Engineering 09, no. 01 (March 2020): 2050001. http://dx.doi.org/10.1142/s2047684120500013.

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By first-principle study, we propose a possible stable helium-based compound with chemical formula of Na2HeO. It has a structure of space group [Formula: see text]. Energy calculation indicates that it has a local minimum with a lattice constant [Formula: see text] Å. Electronic band structure suggests that it is a wide gap insulator. Analysis on Hirshfeld charges and charge density distribution shows a chemical bond formed between O and He atoms in this structure. Results from both elastic constants and phonon dispersion indicate that this compound in the proposed structure is both mechanically and dynamically stable.

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Durgut, Emrah, Mustafa Cinar, Mert Terzi, Ilgin Kursun Unver, Yildiz Yildirim, and Orhan Ozdemir. "Evaluation of Different Dispersants on the Dispersion/Sedimentation Behavior of Halloysite, Kaolinite, and Quartz Suspensions in the Enrichment of Halloysite Ore by Mechanical Dispersion." Minerals 12, no. 11 (November 10, 2022): 1426. http://dx.doi.org/10.3390/min12111426.

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In this study, the dispersion properties of pure halloysite, kaolinite, and quartz minerals in halloysite ore were determined in the absence and presence of dispersants (sodium silicate, STPP, SHMP). First of all, the samples were characterized by chemical, mineralogical, BET, FTIR, and TEM analyses. Afterward, the physico-chemical properties of these minerals were investigated by zeta potential measurements and dispersion/sedimentation experiments in the absence and presence of the dispersants. The zeta potential measurements showed that the surface charges of all minerals changed from negative to positive as the PH changed from basic to acidic. The presence of dispersants at natural pHs indicated that the mineral surface charges tended to become more negative as the concentration increased in the zeta potential measurements. SHMP showed the most effect on the zeta potential. In the dispersion/sedimentation experiments, settling was slowed down with the use of dispersants. Finally, the dispersion properties of halloysite ore in the presence of dispersants were explored using mechanical dispersion and pulp viscosity experiments based on the amount of material passing to <38 μm size and the chemical changes in the materials. As a result of the mechanical dispersion tests carried out in the presence of dispersants (sodium silicate, STPP, SHMP), 71.3% of the material with 30.8% Al2O3 and 50.5% SiO2 content passed to <38 μm size without using dispersant, and 73.2% of <38 μm sized material with 35.5% Al2O3 and 46.1% SiO2 content was gained in the use of 7.5 kg/ton SHMP, which was determined as the optimum within the scope of the study. In conclusion, dispersant use enhanced the mechanical dispersion effect for plastic clay mineral separation from hard minerals in an aqueous medium.

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Nikolaev, Sergey, Dmitry Pshenay-Severin, Yuri Ivanov, and Alexander Burkov. "Effect of Deformation on Topological Properties of Cobalt Monosilicide." Crystals 11, no. 2 (January 29, 2021): 143. http://dx.doi.org/10.3390/cryst11020143.

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Recently, it was shown that materials with certain crystal structures can exhibit multifold band crossings with large topological charges. CoSi is one such material that belongs to non-centrosymmetric space group P213 (#198) and posseses multifold band crossing points with a topological charge of 4. The change of crystal symmetry, e.g., by means of external stress, can lift the degeneracy and change its topological properties. In the present work, the influence of uniaxial deformation on the band structure and topological properties of CoSi is investigated on the base of ab initio calculations. The k·p Hamiltonian taking into account deformation is constructed on the base of symmetry consideration near the Γ and R points both with and without spin-orbit coupling. The transformation of multifold band crossings into nodes of other types with different topological charges, their shift both in energy and in reciprocal space and the tilt of dispersion around nodes are studied in detail depending on the direction of uniaxial deformation.

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Samchenko, Svetlana, Irina Kozlova, Оlga Zemskova, and Ekaterina Baskakova. "Influence of optimal conditions of ultrasonic dispersion on the stability of suspensions of finely ground slags." MATEC Web of Conferences 265 (2019): 01017. http://dx.doi.org/10.1051/matecconf/201926501017.

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The preparation in the jet mill of finely ground slag (FGS) from the waste of metallurgical production granulated blast-furnace slag, the obtaining of slag suspensions, and the behavior of FGS particles in an aqueous dispersion medium are considered in the paper. It was found that FGS particles in the suspension form micelles of two types with negative (micelle 1) and positive (micelle 2) charges of FGS surface. To increase the aggregative and sedimentation stability of FGS particles in suspensions, studies were carried out using ultrasonic dispersion. The results of investigations on the detection of optimal dispersion parameters for slag suspensions are presented. It was found that in the absence of temperature control, the process of coagulation of slag particles is accelerated and aggregative and sedimentation stability of suspensions of FGS is reduced. The slag particles in the suspension form aggregates that lead to a deterioration of the strength characteristics of the cement stone using suspensions of FGS. Optimal parameters of ultrasonic dispersion of slag suspensions are established: the frequency of ultrasonic vibrations is equal to 44 kHz; the dispersion temperature is 25 ± 2 °C; the dispersion time is 15 min. It was found that the application of ultrasonic dispersion to slag suspensions with the observance of dispersion conditions can increase the aggregative and sedimentation stability of FGS suspension by 2-3 times in comparison with the mechanical mixing of suspensions. The strength of samples with suspensions of FGS prepared using UST under the recommended dispersing conditions increased by 19 to 39% in the first day; for 28 days of hardening - by 19 - 36%, which allows using slag suspensions in the production of cement composite materials and concretes based on them.

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Chen, Taoyi, and Thomas A. Manz. "A collection of forcefield precursors for metal–organic frameworks." RSC Advances 9, no. 63 (2019): 36492–507. http://dx.doi.org/10.1039/c9ra07327b.

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Atom-in-material (AIM) partial charges, dipoles and quadrupoles, dispersion coefficients (C₆, C₈, C₁₀), polarizabilities, electron cloud parameters, radial moments, and atom types were extracted from quantum chemistry calculations for >3000 MOFs.

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Padiyan, D. Pathinettam, S. K. Mohanlal, and K. S. Chandrasekaran. "Anomalous dispersion effects, thermal vibrations and bonding charges in gallium arsenide." Zeitschrift f�r Physik B Condensed Matter 65, no. 3 (September 1987): 299–304. http://dx.doi.org/10.1007/bf01303715.

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Li, Zhonglei, Jingang Su, Boxue Du, Zhaohao Hou, and Chenlei Han. "Inhibition Effect of Graphene on Space Charge Injection and Accumulation in Low-Density Polyethylene." Nanomaterials 8, no. 11 (November 20, 2018): 956. http://dx.doi.org/10.3390/nano8110956.

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Space charge injection and accumulation is attracting much attention in the field of dielectric insulation especially for electronic devices, power equipment and so on. This paper proposes using the inhibition effect of graphene for the injection and accumulation of space charge in low-density polyethylene (LDPE). Scanning electron microscope (SEM) and transmission electron microscopy (TEM) images were employed to observe the dispersion of graphene with a two-dimensional structure in LDPE. The time-dependent space charge dynamic behaviors of graphene/LDPE nanocomposites with the filler content of 0, 0.003, 0.005, 0.007 and 0.01 wt % were characterized by the pulsed electro-acoustic (PEA) test at 40, 60 and 80 °C, and the charge mobility was evaluated by its depolarization processes. The experimental results show that for the undoped LDPE film, large amounts of space charges were injected from the electrodes into samples, especially at 60 and 80 °C. The graphene/LDPE nanocomposites with a filler content of 0.005 wt % could markedly suppress the space charge injection and accumulation even at 80 °C, which is attributed to the large quantities of graphene-polymer in interface regions. These interface regions introduced numbers of deep trap sites within the forbidden band of nanocomposites, which can reduce the de-trapping rate of charges and suppress the space charge accumulation in the polymer bulks. The graphene/LDPE nanocomposites are suggested for dielectric applications, intending the inhibition of space charge injection and accumulation.

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Sirisathitkul, Chitnarong, Pongsakorn Jantaratana, and Nantakan Muensit. "Dielectric and magnetic properties of polyvinylidene fluoride polymer composites highly loaded with nickel." Science and Engineering of Composite Materials 19, no. 3 (September 1, 2012): 255–58. http://dx.doi.org/10.1515/secm-2012-0018.

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AbstractIn this work, electroactive polyvinylidene fluoride (PVDF) was a matrix for dispersing 10 wt% ferromagnetic nickel (Ni) particles. The composites were formed into its shape by using a spin coater with varying spinning speeds from 750 to 3750 rpm to obtain the thicknesses between 68 μm and 40 μm on printed circuit board substrates. Magnetic hysteresis loops of the composites were dependent on the spinning speed because the spin regulated the dispersion and size distribution of Ni particles in the PVDF matrix. Owing to the Ni agglomeration, the composites prepared by 750, 1500 and 2250 rpm spinning clearly displayed soft ferromagnetic properties but the capacitance was decreased with the decrease in spinning speed. In every sample, the capacitance was reduced with the increase in frequency from 1 kHz to 100 kHz and remained minimal up to 1 MHz. These changes in capacitance can be explained by the polarization of surface charges of Ni clusters of varying sizes from different spinning speeds. The dissipation factor was, by contrast, sensitive to the frequency and the dispersion of Ni only at frequencies higher than 60 kHz.

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Golubovic, Ljubisa. "Equipotential surface identification of punctual electrically system charges using measurement results." Facta universitatis - series: Electronics and Energetics 23, no. 2 (2010): 147–58. http://dx.doi.org/10.2298/fuee1002147g.

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Identification of equipotential surfaces, based on the measurement results and by application of Least Dispersion Volume Method (LDVM) is described in this paper. In a concrete example of two punctual electric charges a suitable methodology for determining corresponded parameters, which characterize the observed equipotential surfaces is presented. Error analyses that take into account the tested parameters are given.

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28

Saravanan, R., S. K. Mohanlal, and K. S. Chandrasekaran. "Anharmonic temperature factors, anomalous-dispersion effects and bonding charges in gallium arsenide." Acta Crystallographica Section A Foundations of Crystallography 48, no. 1 (January 1, 1992): 4–9. http://dx.doi.org/10.1107/s0108767391005512.

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Saravanan, R., S. K. Mohanlal, and K. S. Chandrasekaran. "Anomalous dispersion effects, anharmonic thermal vibrations and bonding charges in indium antimonide." Journal of Physics and Chemistry of Solids 52, no. 7 (January 1991): 879–86. http://dx.doi.org/10.1016/0022-3697(91)90009-o.

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Kanygina, O. N., O. P. Kushnareva, E. V. Salnikova, and A. A. Yudin. "SURFACE CHARGES AND ZERO CHARGE POINTS OF NATURAL CLAYS OF ORENBURG REGION." Steklo i Keramika, no. 12 (December 2022): 41–49. http://dx.doi.org/10.14489/glc.2022.12.pp.041-049.

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The values of surface charges and zero charge points in water-clay suspensions with pH equal to 5, 7 and 9 have been studied. Their changes under the influence of a microwave field and variations in particle dispersion have been determined. Powders of two fractions of montmorillonite, polymineral and kaolin clays of the Orenburg region were selected as objects of research. The determination of the TNZ of natural clays was carried out by the method of weight titration, based on the measurement of the pH limit value with an increase in the weight fractions of clay. Processing of clay powders in a microwave field was carried out according to the following mode: output power of 750 watts, operating frequency of 2.45 GHz, exposure time 600 s. The magnitude and sign of the charges formed at the interface of the surface of the electrolyte solution particles depend on the mineralogical compositions of the particles. The fine fractions of two clays – montmorillonite containing and polymineral – were sensitive to treatment in the microwave field; the pH values of TNZ shifted to the acidic region by 0.26 and 0.31 units, respectively (by 4 %). The pH values of the TNZ suspensions with kaolin clay after treatment in microwave radiation practically did not change. If the pH value of the solution surrounding the particle exceeds the pH of the TNZ, then the sorbent will be able to absorb cations if the pH value of the solution is lower than the pH of the TNZ – anions. The results obtained will allow the use of microwave exposure as a tool that expands the pH range, contributing to the effective sorption of anions and cations.

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Pan, Qifeng, Qiao Liu, Yuanjiang Yang, and Dongbin Tian. "Abnormal Capacitance Increasing at Elevated Temperature in Tantalum Capacitors with PEDOT:PSS Electrodes." Active and Passive Electronic Components 2018 (October 1, 2018): 1–6. http://dx.doi.org/10.1155/2018/9864387.

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Due to the importance of capacitance temperature stability in precise analog circuit applications, capacitance instability at elevated temperature of 125°C was investigated in tantalum capacitors with PEDOT:PSS counter electrodes. Capacitance-voltage measurement supposed that residual ions in the PEDOT:PSS dispersion caused an accumulation of charges at the dielectric-cathode interface which contributed to an increase in the dielectric constant and resulted in the capacitance increasing at high temperature. Based on the hypothesis, water wash process was applied and capacitance dropped significantly at high temperature. This study shows that an additional water wash process is necessary to improve the capacitance temperature stability after each dispersion dip step.

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Yang, Hua Ping, and Ming Li. "Analysis of Adsorbed Methane Gas Structure and Mullikan Charges." Advanced Materials Research 962-965 (June 2014): 1118–22. http://dx.doi.org/10.4028/www.scientific.net/amr.962-965.1118.

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The methane molecule model, the coal molecule model and the absorption model of coal and methane have been thoroughly investigated using the DFT method,Van der Walls force radius as boundary conditions as well. The investigations focuses on optimizing the three types of model structure. Meanwhile, adsorption equilibrium geometries with 6-311G++ basic sets have been established. Through the model analysis of the changes in the structure and Millikan charge from free state to the adsorption states, the results indicate that the adsorption process of methane gas on the coal in the Van der Walls force mainly dispersion forces and induction force, methane molecules are polarized in the adsorption process, the electric dipole moment.

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Hemati, A., S. Shrestha, M. Agarwal, and K. Varahramyan. "Layer-by-Layer Nanoassembly of Copper Indium Gallium Selenium Nanoparticle Films for Solar Cell Applications." Journal of Nanomaterials 2012 (2012): 1–6. http://dx.doi.org/10.1155/2012/512409.

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Thin films of CIGS nanoparticles interdigited with polymers have been fabricated through a cost-effective nonvacuum film deposition process called layer-by-layer (LbL) nanoassembly. CIGS nanoparticles synthesized by heating copper chloride, indium chloride, gallium chloride, and selenium in oleylamine were dispersed in water, and desired surface charges were obtained through pH regulation and by coating the particles with polystyrene sulfonate (PSS). Raising the pH of the nanoparticle dispersion reduced the zeta-potential from+61 mV at pH 7 to−51 mV at pH 10.5. Coating the CIGS nanoparticles with PSS (CIGS-PSS) produced a stable dispersion in water with−56.9 mV zeta-potential. Thin films of oppositely charged CIGS nanoparticles (CIGS/CIGS), CIGS nanoparticles and PSS (CIGS/PSS), and PSS-coated CIGS nanoparticles and polyethylenimine (CIGS-PSS/PEI) were constructed through the LbL nanoassembly. Film thickness and resistivity of each bilayer of the films were measured, and photoelectric properties of the films were studied for solar cell applications. Solar cell devices fabricated with a 219 nm CIGS film, when illuminated by 50 W light-source, produced 0.7 V open circuit voltage and 0.3 mA/cm2short circuit current density.

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Romeo, Maurizio. "Electromagnetic field-current coupling in rigid polarized conductors." Mathematics and Mechanics of Solids 23, no. 1 (September 13, 2016): 85–98. http://dx.doi.org/10.1177/1081286516666404.

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A continuum model, based on a theory of electromagnetic media with microstructure, is exploited to deal with rigid conductors endowed with polarization and magnetization. Charge carriers are considered as a continuum superimposed to the microstructured conductor where the density of bound charges depends on the internal degrees of freedom of the continuum particle. The non-linear dynamical model is formulated, deriving the mechanical balance laws that are coupled with the electromagnetic field equations. A reduction to the micropolar linear case is performed in order to analyze admissible solutions in the form of one-dimensional plane waves. Dispersion equations are derived for modes pertaining to longitudinal and transverse fields and the effects of conductivity and polarization are evidentiated. Polariton modes, arising from the dynamics of microdeformation, are also discussed.

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Kanellis, G., W. Kress, and H. Bilz. "Dynamical properties of copper halides. I. Interionic forces, charges, and phonon dispersion curves." Physical Review B 33, no. 12 (June 15, 1986): 8724–32. http://dx.doi.org/10.1103/physrevb.33.8724.

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Lefebure, S., E. Dubois, V. Cabuil, S. Neveu, and R. Massart. "Monodisperse magnetic nanoparticles: Preparation and dispersion in water and oils." Journal of Materials Research 13, no. 10 (October 1998): 2975–81. http://dx.doi.org/10.1557/jmr.1998.0407.

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Nanometric maghemite and cobalt ferrite particles are chemically synthesized. The process produces particles polydisperse in size. The positive charges of their surface allow one to disperse them in aqueous acidic solutions and to obtain dispersions stabilized through electrostatic repulsions. Increasing acid concentration (in the range 0.1 to 0.5 mol.L−1), interparticles repulsions are screened and phase transitions are induced. Using this phenomenon, we describe a two-step size sorting process, in order to get significant amounts of nanometric monosized particles (with diameters monitored between typically 6 and 13 nm). As the surface of the latter is not modified by the size sorting process, usual procedures are used to disperse them in several aqueous or oily media.

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Hansen, Steen H. "Accelerated expansion induced by dark matter with two charges." Monthly Notices of the Royal Astronomical Society: Letters 508, no. 1 (September 2, 2021): 22–25. http://dx.doi.org/10.1093/mnrasl/slab103.

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ABSTRACT The accelerated expansion of the Universe has been established through observations of supernovae, the growth of structure, and the cosmic microwave background. The most popular explanation is Einstein's cosmological constant, or dynamic variations hereof. A recent paper demonstrated that if dark matter particles are endowed with a repulsive force proportional to the internal velocity dispersion of galaxies, then the corresponding acceleration of the Universe may follow that of a cosmological constant fairly closely. However, no such long-range force is known to exist. A concrete example of such a force is derived here, by equipping the dark matter particles with two new dark charges. This result lends support to the possibility that the current acceleration of the Universe may be explained without the need for a cosmological constant.

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38

Chen, Wen Chao, and Louis-André Hamel. "Calcul analytique du transport des charges dans le a-Si :H." Canadian Journal of Physics 73, no. 9-10 (September 1, 1995): 585–94. http://dx.doi.org/10.1139/p95-085.

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Multitrapping transport of carriers through exponential band tails is studied for carriers generated at an arbitrary position in the device in presence of a linearly varying electric field, thus generalizing the usual treatment of time of flight experiments. An analytical expression is found for the free carrier density distribution n(x,t) for values of the dispersion parameter 0 < α < 1. In the case α = 1/2, analytical solutions are given for the transient current I(t) and the induced charge Q(t). Comparison with previous calculations is made for the special case of uniform electric field and carriers initially generated at one interface.

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Hou, P., J. Sun, S. B. Zhou, and Jie Weng. "Synthesis and Dispersion of Magnetic Nano-Particles by a Surfactant-Mediated Approach." Key Engineering Materials 330-332 (February 2007): 231–34. http://dx.doi.org/10.4028/www.scientific.net/kem.330-332.231.

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Magnetic nano-particles of around 20nm synthesized by poly-ethylene glycol (PEG) and sodium oleate mediated approach show well stability without sediment during 6 months. Upon treated through the modification procedure, magnetic nano-particles have a weakly physical bond with PEG, meanwhile a strong bond with sodium oleate. Naked magnetic nano-particles present positive charges on the surface, while turn to be negative when modified with sodium oleate, which suggest that the hydrophilic carboxyl on the surface of the nano-particles is outward. Magnetic property of the nano-particles changes according to the concentrations of reactants and surfactant.

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Town, Raewyn M., and Herman P. van Leeuwen. "Labilities of aqueous nanoparticulate metal complexes in environmental speciation analysis." Environmental Chemistry 11, no. 2 (2014): 196. http://dx.doi.org/10.1071/en13138.

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Environmental context Sorbing nanoparticles can have a significant effect on the speciation of small ions and molecules in the environment. The reactivity of nanoparticulate-bound species can differ significantly from that of their molecular or colloidal counterparts. We present a conceptual framework that describes the chemodynamics and lability of nanoparticulate metal complexes over a wide range of experimental timescales and environmental conditions. Abstract An inherent property of a dispersion of charged nanoparticles is that their charges and reactive sites are spatially confined to the particle body which is at a different potential from that in the bulk medium. This feature has important consequences for the reactivity of nanoparticulate complexants: the diffusive rate of reactant supply is lower as compared to molecular complexants, whereas the local concentration of reactant ions may be enhanced if the particle’s electric field has the opposite charge sign. These effects are most dramatic for soft nanoparticles for which the electrostatic accumulation mechanisms operate on a 3-D level. We show how the interplay of these effects governs the reactivity of charged nanoparticulate metal complexes (M-NPs) at the surface of an analytical speciation sensor. A theoretical framework is presented that describes the lability of M-NP species over a range of effective timescales for different electrochemical and other dynamic speciation analysis techniques. The concepts are illustrated by electrochemical stripping data on metal complexes with natural soft nanoparticles of humic acid.

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41

Gunawan, Vincensius. "calculated attenuated total reflection (ATR) for analyzing surface plasmon polaritons." International Journal of Scientific Research and Management 10, no. 11 (November 4, 2022): 20–24. http://dx.doi.org/10.18535/ijsrm/v10i11.p01.

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The electromagnetic waves propagate in the interface between metal and dielectric can be simply called surface plasmon polariton. The surface plasmon polaritons were produced by the coupling of incoming electromagnetic waves and collective vibrations of free charges on metal surface. The generation of surface polaritons may be done using attenuated total reflection (ATR) method which was based on total internal reflection. The method can be performed numerically by analyzing reflections on each involved interfaces. The generated surface plasmon polaritons were represented by the appearance of the dip in the ATR spectroscopy. In this paper, we presented the ATR spectroscopy for surface plasmon polaritons generated on gold-castor oil interface. The results showed the predicted dispersion relation from calculated ATR of the surface plasmons polaritons were in good agreement with the dispersion relation from the theory.

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42

Hong, Xiao‐wen, Wei‐bing Li, Xiao‐ming Wang, Wen‐bin Li, and Rui Li. "Explosion Temperature and Dispersion Characteristics of Composite Charges Based on Different Non‐detonative Materials." Propellants, Explosives, Pyrotechnics 43, no. 12 (October 10, 2018): 1251–62. http://dx.doi.org/10.1002/prep.201800132.

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43

M. Aguilar, Nery, José Manuel Pérez-Aguilar, Valeria J. González-Coronel, Hugo Martínez-Gutiérrez, Teresa Zayas Pérez, Guillermo Soriano-Moro, and Brenda L. Sánchez-Gaytán. "Hydrolyzed Polyacrylamide as an In Situ Assistant in the Nucleation and Growth of Gold Nanoparticles." Materials 15, no. 23 (December 1, 2022): 8557. http://dx.doi.org/10.3390/ma15238557.

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The modulation of nanoparticles’ size, shape, and dispersion by polymers has attracted particular attention in different fields. Nevertheless, there is a lack of information regarding the use of charged macromolecules as assistants in the nanostructures’ nucleation and growth processes. Prompted by this, the in situ synthesis of gold nanoparticles (AuNPs) aided by hydrolyzed polyacrylamides (HPAM), with different chemical structures, was developed. In contrast to the conventional synthesis of nanostructures assisted by polyacrylamide, here, the polymerization, hydrolysis, and nanostructure formation processes were carried out simultaneously in the same milieu. Likewise, the growing chains acted as a template for the nanoparticles’ growth, so their conformations and chemical structure, especially the amount of charges along the chain, played an important role in the AuNPs’ morphology, size, and some of the final composite features. The nanocomposite was thoroughly characterized with appropriate techniques, including ATR–FTIR, GPC, UV–Vis, and SEM.

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44

Suphasorn, Pawanrat, Intuorn Appamato, Viyada Harnchana, Prasit Thongbai, Chalathorn Chanthad, Chomsri Siriwong, and Vittaya Amornkitbamrung. "Ag Nanoparticle-Incorporated Natural Rubber for Mechanical Energy Harvesting Application." Molecules 26, no. 9 (May 6, 2021): 2720. http://dx.doi.org/10.3390/molecules26092720.

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The energy conversion performance of the triboelectric nanogenerator (TENG) is a function of triboelectric charges which depend on the intrinsic properties of materials to hold charges or the dielectric properties of triboelectric materials. In this work, Ag nanoparticles were synthesized and used to incorporate into natural rubber (NR) in order to enhance the dielectric constant for enhancing the electrical output of TENG. It was found that the size of Ag nanoparticles was reduced with the increasing CTAB concentration. Furthermore, the CTAB surfactant helped the dispersion of metallic Ag nanoparticles in the NR-insulating matrix, which promoted interfacial polarization that affected the dielectric properties of the NR composite. Ag nanoparticle-incorporated NR films exhibited an improved dielectric constant of up to almost 40% and an enhanced TENG performance that generated the highest power density of 262.4 mW/m2.

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45

Janek, M., P. Komadel, and G. Lagaly. "Effect of autotransformation on the layer charge of smectites determined by the alkylammonium method." Clay Minerals 32, no. 4 (December 1997): 623–32. http://dx.doi.org/10.1180/claymin.1997.032.4.12.

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AbstractHydrogen-forms of <2 µm fractions of six bentonites of various Fe contents were prepared by H+→OH-→H+ ion exchange using resins. Potentiometric titration curves revealed that the number of strong acid sites varied and accounted for 60-95% of the total acidity in the freshly prepared H-forms. The number of strong acid sites decreased and that of the weak acid sites increased on ageing. The process of autotransformation in aqueous dispersion at 90~ was completed within four days. Layer-charge distributions of all samples were inhomogeneous with layer charges from 0.25-0.39 Eq/unit O10(OH)2. Oxalate pretreatment of the samples resulted in changes in the layer-charge distribution due to the removal of readily soluble phases which may have blocked exchange sites. After autotransformation, the alkylammonium exchange method revealed inhomogeneous charge density distributions; the fraction of layers of the highest charge decreased. Comparison of total CEC obtained from potentiometric curves and interlamellar CEC calculated from the mean layer charge confirmed attack of protons from particle edges. However, for several samples the structural attack may also occur from the interlayer space. Autotransformation of the Hsmectites decreased the mean layer charge. Protons probably attack the Mg(O,OH)6 octahedra preferentially during the autotransformation.

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Potty, Gopu R., James H. Miller, Lindsey J. Moss, Andrew R. McNeese, Preston S. Wilson, Ying-Tsong Lin, and David R. Dall'Osto. "Dispersion of broadband signals in the Seabed Characterization Experiment-2022." Journal of the Acoustical Society of America 152, no. 4 (October 2022): A239. http://dx.doi.org/10.1121/10.0016137.

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Broadband sources such as SUS charges and Rupture Induced, Underwater Sound Sources (RIUSS) were deployed in the New England Mud Patch in support of the 2022 Seabed Characterization Experiment. Data measured on the Ocean Bottom Recorders (OBX) and hydrophones will be discussed. Five OBXs were deployed on the seabed and four hydrophones were configured as a tetrahedral array on the bottom mounted Geosled. The OBXs measured three components of particle velocities and acoustic pressure. The spatial variability in the dispersion of broadband signals observed in the pressure and particle velocity data will be discussed. Presence of Scholte waves on the OBX data will be explored using the random decrement technique. Results will be compared with modeling using the seismo-acoustic propagation code (OASES). Outputs of preliminary inversions will be compared with core data collected as part of the experiment. [Work Supported by Office of Naval Research.]

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Grewal, Manjit Singh, Hiroya Abe, Yasutaka Matsuo, and Hiroshi Yabu. "Aqueous dispersion and tuning surface charges of polytetrafluoroethylene particles by bioinspired polydopamine–polyethyleneimine coating via one-step method." Royal Society Open Science 8, no. 8 (August 2021): 210582. http://dx.doi.org/10.1098/rsos.210582.

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We propose a surface modification of poorly dispersive polytetrafluoroethylene (PTFE) particles via bioinspired polydopamine–polyethyleneimine (PDA–PEI) which conferred PTFE particles a uniform dispersion in aqueous medium. With increasing dopamine concentration in the reaction solution, dispersity of PTFE particles improved and the surface charges of particles changed from negative to positive due to an increase of surface coverage of PDA–PEI layers. Simplicity of the method here outlines an attractive route for surface modification of inert surfaces useful for large-scale applications.

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Mahanty, J., and M. P. Das. "POSSIBLE MECHANISM OF PAIRING IN HIGH Tc SUPERCONDUCTORS: A MULTI-COMPONENT PLASMA MODEL." International Journal of Modern Physics B 02, no. 05 (October 1988): 873–81. http://dx.doi.org/10.1142/s021797928800069x.

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Screening of a pair of point charges in a medium of electrons and ions is studied using the hydrodynamical model, treating the system as a multi-component plasma. When some of the ion plasma branches possess negative dispersion, the interaction potential of the pair can become attractive and large in certain regions of momentum space under certain conditions. By using this potential in the BCS gap equation, high transition temperatures have been obtained. Applicability of this model to oxide superconductors is discussed.

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Mahanty, J., and MP Das. "A Dielectric Approach to High Temperature Superconductivity." Australian Journal of Physics 42, no. 5 (1989): 541. http://dx.doi.org/10.1071/ph890541.

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In this paper we investigate the dielectric response of an electron-ion system to the presence of a pair of charges. From the nature of the dielectric function, it Is shown that a strong attractive pair formation is possible depending on the dispersion of the ion branches. The latter brings a reduction to the sound velocity which is used as a criterion for the superconductivity. By solving the BCS equation with the above dielectric function, we obtain a reasonable value of Te.

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Cheng, Yujia, Guang Yu, and Zhuohua Duan. "Effect of Cooling Medium on LDPE Dielectric Properties." Polymers 14, no. 3 (January 21, 2022): 425. http://dx.doi.org/10.3390/polym14030425.

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Polyethylene, with its excellent mechanical and dielectric properties is used as an insulator for high-voltage direct current (HVDC) transmission. In ultra-high-voltage direct current (UHVDC) transmission, the ageing of insulation materials caused by space charge under high DC voltage becomes serious. Therefore, restraining the space charge and improving the dielectric properties of HVDC cables is important. In this study, low-density polyethylene (LDPE) was used as the raw material and combined with cooling media in a vulcanizing press. A polarizing microscope was used to observe the samples’ crystal morphologies. The space charge accumulation and dispersion were detected using pulsed electro-acoustic. Additionally, dielectric properties such as electrical conductivity and dielectric frequency spectrum were tested. The grain size in the air-cooled LDPE samples was found to be large and unevenly dispersed. However, the grain sizes in the water and oil cooling LDPE samples were small. The mean charge density of the oil cooling samples was the lowest. Under a short circuit measurement, more space charges were found in the natural and rapid air cooling samples. The mean charge densities of these two samples were high, with a fast decay rate. With an 8 and 50 kV/mm electric field strength, the oil cooling samples’ conductivity was the highest and lowest, respectively.

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Journal articles on the topic 'Dispersion de charges'

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