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101.
Monica Sorescu Tianhong Xu Lucian Diamandescu Devin Hileman 《Hyperfine Interactions》2011,199(1-3):365-386
Indium oxide-doped hematite xIn2O3*(1-x)??-Fe2O3 (molar concentration x = 0.1?C0.7) solid solutions were synthesized using mechanochemical activation by ball milling. XRD patterns yield the dependence of lattice parameters and grain size as function of milling time. After 12 h of milling, the completion of In3?+? substitution of Fe3?+? in hematite lattice occurs for x = 0.1. For x = 0.3, 0.5 and 0.7, the substitutions between In3?+? and Fe3?+? into hematite and respectively, In2O3 lattices occur simultaneously. The lattice parameters of ??-Fe2O3 (a and c) and In2O3 (a) vary with milling time. For x = 0.1, Mössbauer spectra were fitted with one, two, or three sextets versus milling time, corresponding to gradual substitution of In3?+? for Fe3?+? in hematite lattice. For x = 0.3, Mössbauer spectra after milling were fitted with three sextets and two quadrupole-split doublets, representing In3?+? substitution of Fe3?+? in hematite lattice and Fe3?+? substitution of In3?+? in two different sites of In2O3 lattice. For x = 0.5 and 0.7, Mössbauer spectra fitting required two sextets and one quadrupole-split doublet, representing coexistence of In3?+? substitution of Fe3?+? in hematite lattice and Fe3?+? substitution of In3?+? in indium oxide lattice. The recoilless fraction studied versus milling time for each molar concentration exhibited low values, consistent with the occurrence of nanoparticles in the system. SEM/EDS measurements revealed that the mechanochemical activation by ball milling produced xIn2O3*(1-x)??-Fe2O3 solid solution system with a wide range of particle size distribution, from nanometer to micrometer, but with a uniform distribution of Fe, In, and O elements. 相似文献
102.
Mohamed Miloudi Karim Medles Amar Tilmatine Mostefa Brahami Lucian Dascalescu 《Journal of Electrostatics》2011,69(6):631-637
Electrostatic separation has already proved to be an effective means for the recycling of granular plastics from industrial wastes. The aim of the present work was to optimize the operation of a novel device that could ensure effective triboelectric charging of such materials prior to their selective sorting in a high-intensity electric field. The experiments were performed on two sorts of mm-size granular materials Acrylonitrile Butadiene Styrene and High Impact Polystyrene, originating from the processing of waste electric and electronic equipment. The samples were introduced in a Polyvinyl Chloride cylinder, where a co-axial propeller entrained the plastic granules into a helical motion that favored their triboelectric charging by combining the mechanical and aerodynamical effects. The experimental design methodology was employed for the modeling and optimization of the tribocharging process. 相似文献
103.
Lucian Olteanu 《International Journal of Mathematical Education in Science & Technology》2013,44(7):1021-1033
This paper contains a discussion of how the concept of critical aspects and the principle of compositionality can provide a powerful tool to analyse and understand the communications that occur in the classroom. It is grounded in data collected in a longitudinal study. The content chosen is algebra. It is argued that the critical aspects and the principle of compositionality should be considered as a methodological principle that describes how communication in the classroom should be designed. Here, I present the power of using variation theory whose main purpose is to generate an understanding of critical aspects and compositionality in practice. 相似文献
104.
Maxime Crochemore Lucian Ilie Costas S. Iliopoulos Marcin Kubica Wojciech Rytter Tomasz Waleń 《European Journal of Combinatorics》2013
The Longest Previous Factor array gives, for each position i in a string y, the length of the longest factor (substring) of y that occurs both at i and to the left of i in y. The Longest Previous Factor array is central in many text compression techniques as well as in the most efficient algorithms for detecting motifs and repetitions occurring in a text. Computing the Longest Previous Factor array requires usually the Suffix Array and the Longest Common Prefix array. We give the first time–space optimal algorithm that computes the Longest Previous Factor array, given the Suffix Array and the Longest Common Prefix array. We also give the first linear-time algorithm that computes the permutation that applied to the Longest Common Prefix array produces the Longest Previous Factor array. 相似文献
105.
A tribo-aero-electrostatic separator has been recently patented for the selective sorting of granular plastics mixtures generated during the recycling of waste electrical and electronic equipments (WEEE). The plastics are tribo-charged in a parallelepiped fluidized bed device, two opposite walls of which being the electrodes that generate the electric field that performs the separation. In two previous papers, different sets of operating parameters of this separator have been studied by hundreds of experiments, in order to improve the efficiency of the process and the purity of the products. The aim of the present paper is to complement these studies by establishing a model for computing the trajectory of plastics granules in such separator. The distribution of electric field and the profile of the airflow between electrodes were expressed using simple analytical formulas, which were introduced in the system of differential equations that served for the calculation of granule trajectories under the action of the various electric and mechanical forces. The computations were performed for various operating parameters: applied-voltage, granule size, charge density. The model can guide the design of industrial tribo-aero-electrostatic separators and the choice of the optimum values of the operating variables of such equipment. 相似文献
106.
Horia-Nicolai Teodorescu Lucian Dascalescu Mircea Hulea Marius Cristian Plopeanu 《Journal of Electrostatics》2013,71(4):635-647
The aim of this paper is to determine the degree of correlation between the electrostatic potential distribution on the surface of non-woven fabrics and the material structure as obtained by optical means. The potential distribution on the material surface was monitored for several samples of two types of fabrics that were electrically charged using corona discharge. The results show that the charge distribution on the samples surface significantly correlates with the spreading and the third centered moment of the gray-scale pictures of the samples. 相似文献
107.
108.
Lucian Dragos Filip Lucian Pintilie 《The European Physical Journal B - Condensed Matter and Complex Systems》2016,89(2):44
A model for current voltage characteristics of a thin film metal-ferroelectric-metalstructure is constructed by combining the electrostatics of a polarized ferroelectric filmwith the balanced flow of charge through its interfaces. Using a set of fittingparameters, good agreement with several sets of experimental data is obtained fordifferent system temperatures. The influence of model parameters on the current-voltagecharacteristic is discussed. Best fit values of some of these parameters correlate wellwith ab initio calculations in the literature, supporting the idea of low dielectricpermittivity of the interface transition layers in the ferroelectric. 相似文献
109.
We present a Thomas-Fermi-inspired density scaling under which electron densities of atomic, molecular, or condensed matter become both large and slowly varying, so that semiclassical approximations and second-order density gradient expansions are asymptotically exact for the kinetic and exchange energies. Thus, even for atoms and molecules, density-functional approximations should recover the universal second-order gradient expansions in this limit. We also explain why common generalized gradient approximations for exchange do not. 相似文献
110.
Lavinia Claudia Buruleanu Andreea Antonia Georgescu Ioana Daniela Dulama Cristina Mihaela Nicolescu Radu Lucian Olteanu 《Analytical letters》2019,52(8):1195-1214
The elemental composition and antioxidant activity have been obtained for regional mushrooms species, wild and cultivated, from Dambovita County, Romania. A multivariate approach and data mining techniques (principal component analysis and cluster analysis, respectively) were applied in order to evaluate the correlation matrix for these parameters for both caps and stipes of mushrooms. The associations between metallic elements (i.e., Fe, Cu, Cd, Pb, Co, Ni, Zn, Mn, Cr, Na, K, Ca and Mg) correlated with antioxidant activity, total phenolics, and total flavonoids were carried out by using a full factorial linear design. The multivariate functional analysis revealed on associated accumulation of several elements in mushrooms. In the cluster analysis, the dataset was treated to appreciate the correlation between metals group (e.g., heavy metals, such as Fe, Cu, Cd, Pb, Co, Ni, Zn, Mn, Cr, and important nutritional elements, such as Na, K, Ca, and Mg). Fungal species with similar characteristics in terms of metal accumulation formed two distinctive clusters. From a point of view of the consumer, the content of Cd and especially Pb in the fruiting bodies of the analyzed mushrooms species may be considered elevated, so that mapping the risk is compulsory. Applying the chemometric tools in the sense mentioned above, as well as in helping the scientific research by optimizing the number of data points, was shown to be extremely useful. 相似文献