Papers by Keyword: Charge Density

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Authors: Jun Zhang, Michael W. Reeks
Abstract: A theoretical model to predict the joint distribution of droplet size and charge density for an electrostatic spray is described based on the maximum entropy method. From known values of the electrostatic spray parameters, the model is used to evaluate the joint distribution of droplet size and charge density for a cone-jet mode electrostatic spray. The predicted results of present model show that it has generally a relatively narrow distribution for both droplet and charge density in a cone-jet mode. Comparatively, the droplet size distribution is narrower than that of the charge density. In addition the two distributions are significantly different in shape. The droplet size distribution is nearly symmetric about its peak position, whilst the left side of the charge density distribution curve is noticeably steeper than the right side. The results are also compared with existing experimental data with agreement considering the uncertainties in the data.
Authors: R.A.J.R. Sheeba, R. Saravanan, L. John Berchmans
Abstract: An effort has been made to understand the charge density distribution of the Si and Ge based diluted magnetic semiconductors. A theoretical analysis has been done on the variation of charge densities when the semiconductors Si and Ge are doped with the transition metal atoms of V, Mn and Co with different concentrations of x (0.02, 0.04, 0.06, 0.08, and 0.10), in Si1-xMx and Ge1-xMx. Two dimensional electron density contour maps have been plotted for all the compositions studied in this work. The theoretical mid bond densities were found out for the compounds which can be taken as the reference values for comparison of the experimental values of the same compositions.
Authors: D.L. Smith, C. Smith, P.C. Rice-Evans, J.H. Evans-Freeman, Hugh E. Evans
Authors: Jonathan Stranger, Mark P. Staiger, Nick Tucker, Kerry Kirwan
Abstract: A detailed understanding of charge density and its origins during the electrospinning process is desirable for developing new electrospinnable polymer-solvent systems and ensuring mathematical models of the process are accurate. In this work, two different approaches were taken to alter the charge density in order to measure its effect on the Taylor cone, mass deposition rate and initial jet diameter. It was found that an increase in charge density results in a decrease in the mass deposition rate and initial jet diameter. A theory is proposed for this behaviour in that an increase in charge density leads to the tip of the Taylor cone forming a smaller radius of curvature resulting in the concentration of electric stresses at the tip. This leads to the electrostatic forces drawing the initial jet from a smaller effective area or “virtual orifice”.
Authors: Xu Huang, Zhen Zhen Weng, Gui Gui Xu, Zhi Gao Chen, Zhi Gao Huang
Abstract: Effects of oxygen atom adsorption on work functions of Mo(110) surface and substrate are investigated using first-principles methods based on density functional theory. The calculated results reveal that there exist a most probable site (named f1 site) in the surface oxygen adsorption on Mo(110) surface. Moreover, it is found that work functions of oxygen-adsorbed Mo(110) increase with increasing oxygen coverage, while the adsorption energies of oxygen decrease with increasing oxygen coverage. For a given oxygen coverage such as 0.333ML with surface f1 site, the work functions are insensitive to the distribution of oxygen atoms. In the meantime, the relationship among charge density, surface dipole density and the work function are discussed.
Authors: Wei Hua Wang, Cui Lan Zhao, Xin Jun Ma
Abstract: The centre Au-doped armchair graphene nanoribbons (AGNRs) are investigated using the local density approximation based on density function theory. The charge density, electronic energy band and project density of states of centre Au-doped AGNRs are calculated. Our results indicate the charge density is transferred between C and Au atoms and mainly located on the Au atoms. The centre Au-doped AGNRs are an indirect band gap semiconductor with an energy gap of 1.046 eV. The Fermi level is located on valence band so that the AGNRs of doping Au become into degenerate semiconductor. The project density of states is calculated to reveal localization and hybridization between C-2p and Au-6s, 5d electronic states. The localization and hybridization are much stronger in the valence band. The hybridization between C-2p and Au-6p electronic states are strongly in the conduction band.
Authors: Xiaoping Han, Yao Zhang, Sheng Kai Gong, Hui Bin Xu
Authors: Hai Ming Li, Xiao Hong Chen, Jing Hui Zhou, Ying Han, Guang Wei Sun
Abstract: The reaction of the xylan-type hemicellulose with 2,3-epoxypropyltrimethylammonium chloride and acrylamide in ethanol-water-alkali slurry yielded water-soluble, cationic etherified xylan-type hemicellulose derivatives. The degree of substitution (DS) value reaches up to 0.40 by adjusting the mass ratios (NaOH/hemicellulose, total etherifying agents/hemicellulose and 2,3-epoxypropyltrimethylammonium chloride/acrylamide), the reaction temperature and the reaction time in a one-step synthesis. The etherified hemicellulose was characterized by infrared spectroscopic analysis (FT-IR), Zeta potential analysis, charge density analysis and thermogravimetric analysis (TGA). It is found that Zeta potential is promoted from-30.50mv to +35.81mv and charge density is promoted from-0.50mmol/g to +0.88mmol/g during etherification under the conditions used. The thermal stability of the etherified hemicellulose is lower than that of the unmodified xylan-type hemicellulose polymers.
Authors: Mani Shugani, Mahendra Aynyas, Harsha Pawar, Sankar P. Sanyal
Abstract: The electronic structures, densities of states and Fermi surfaces of ErX (X = Cu, Ag and Au) intermetallic compounds are studied using full potential linear augmented plane wave (FP-LAPW) method within generalized gradient approximation (GGA) for the exchange-correlation functional. The total energies are computed as a function of volume and fitted to the Birch equation of state. The ground state properties such as equilibrium lattice constants (a0), bulk modulus (B) and pressure derivative of bulk modulus (B') and density of states at the Fermi level N (EF) are calculated. The states at the Fermi level (EF) are dominated by Er ‘d states with significant contribution of ‘p and ‘d states of X. We have also plotted charge density and Fermi surface to study the bonding properties of ErX compounds.
Authors: Chun Chen, Wei Bing Li, Jun Liu
Abstract: For passive RDX, fluent software was applied to simulate the cook-off for explosive of different charge density at heating rates of 1, 5, 10k/min to improve thermal safety in the ammunition storage, transport and battle. The results show that the heating rate has great effect on ignition time and position for passive RDX. Charge density also has great influence on ignition time but no influence on ignition position. The ignition time decreases and ignition position moves from the center to the two ends of the cylinder edge with the increase of the heating rate. The ignition time increases with the increase of charge density under the same condition. Therefore, increasing the charge density can effectively improve the thermal safety of ammunition.
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