Conductivity in Half-filled Ionic Hubbard Model

We calculate the temperature dependent conductivity in the half-filled ionic Hubbard model with an on-site Coulomb repulsion $U$ and an ionic energy $\Delta$ by mean of the coherent potential approximation. It is shown that for intermediate and large $\Delta$ the largest conductivity occurs near the special value $U = 2 \Delta$ at all temperatures $T$, for a fixed $\Delta$ the region of finite conductivity $[U_{c1}, U_{c2}]$ expands and its maximum decreases with increasing $T$. Our results are in good agreement with those derived from the determinant quantum Monte Carlo simulation

Properties of DMF-fossil gasoline RON95 blends in the consideration as the alternative fuel

The use of endless biomass sources form agricultural by-products for the renewable fuel synthesis has been being considered as the extremely useful works meeting the strict strategies of environment protection. In this work, 2,5-dimethylfuran (DMF) synthesized from available rice straw in Vietnam was mixing with fossil gasoline RON95 to determine and measure the key properties of DMF-gasoline RON95 blends based on corresponding ASTM standards in the consideration as a new alternative fuel for modern gasoline engines. Each 5% volume fraction of DMF was used for mixing purposes to create 21 samples with the change of DMF volume fractions from 0% to 100%. As a result, the linearization of density, octane number, and laten heat of vaporization was conducted; meanwhile, the stoichiometric air/fuel ratio, heating value, and self-ignition temperature of DMF-gasoline RON95 blends were also reported. This work provided the full properties of blends of DMF-gasoline RON95 blends based on experimental results, and of course, achieved results could be used for the next steps to investigate the applicability of DMF-gasoline RON95 blends to practical experiments or simulation studies

WTC2005-64192 INVESTIGATION ON THE WEAR OF WELL-TUBING IN THE OIL EXPLOITATION

ABSTRACT In this paper, the results of investigation of wear of well-tubing with the sea depth from 3000 to 5000 meters are presented. The theory of erosion for tubing is established basing on the flow of exploited products and the principles of erosion and corrosion, for calculating the wear of thickness of tubing and the influence of environment and exploited oil products flow (pressure, velocity, temperature etc.). The long-life of tubing is determined for the maintenance service. Various proposals for increasing effectiveness of tubing exploitation are presented as materials changing, manufacturing, improving etc

Pulsed Electric Discharge in Active Metallic Grains for Water Purification Processes

Chemical reactions in electric metal pulse dispersion in the aqueous solutions of inorganic substance (НSiO[3]{–}, Ni{2+}, Н[2]AsO[4]{–}, Mn{2+}, Cr[2]O[7]{2–}) were determined through IR spectroscopy, X-ray phase, chemical, kinetic, and thermodynamic analyses. Under such conditions, both reduction and oxidation reactions occur, as well as, locally initiated by heating, hydrolysis and exchange reactions without changing the oxidation rate of the dissolved substance itself. Reduction and oxidation of dissolved substances is determined by the generation and activation of high dispersed Fe in an electric discharge. Physical and chemical processes which take place under the action of pulse electric discharges upon the layer of metallic grains in salt solution, containing НSiO[3]{–}, Ni{2+}, Н[2]AsO[4]{–}, Mn{2+}, Cr[2]O[7]{2–} ions were determined on the basis of product composition, obtained experimentally and the thermodynamic data. It was shown, that PED discharge in heterogeneous mediums can be used for waste and natural water purification