Effect of Lattice Setting Density on Fluid Flow and Convective Heat Transfer Characteristics of Bricks in Tunnel Kilns

This paper reports the effect of setting density on flow uniformity, pressure drop, pumping power, and convective heat transfer coefficients (CHTCs). High-density setting (HDS) comprises 768 bricks, and low-density setting (LDS) contains 512 bricks are tested for different inlet air velocities using both local and average approaches. The investigation is carried out using a 3D-computational fluid dynamics (CFD) model with k–ω turbulence model. Both settings are validated against experimental data reported in the literature with errors less than 1.9% for pressure drop and −1.0% for brick surface temperature. The reported results indicated that the LDS has distinct benefits over the HDS as it enhances the flow uniformity, particularly in the stack channels. Also, LDS attains lower pressure drop, pumping power, and firing time than HDS by 45.93%, 50%, and 35%, respectively. In addition, LDS produces larger CHTCs, rates of heat transfer for individual bricks, and the ratio of heat transfer to pumping power than HDS by 24.53%, 35%, and 34%, respectively. Moreover, LDS produces more homogenous heating of the setting bricks than HDS as the maximum difference of CHTCs between bricks is about 4.39% for LDS and 19.62% for HDS. The best performance of the firing process is accomplished at low inlet air velocity (3 m/s), whereas the highest productivity is achieved at high inlet air velocity (9 m/s).

The crystal structure of barikaite

Electron microprobe analysis of barikaite (Topa et al., 2013) indicates the chemical formula Ag2.90Tl0.04Pb9.31As11.26Sb8.12S40.37. Barikaite is monoclinic, with a 8.533(1) Å, b 8.075(1) Å, c 24.828(2) Å, and β 99.077(1)°; unit-cell volume 1689.2 Å3 and the space-group setting is P21/n. This compares well with the unit-cell parameters of rathite Pb10Tl0.9As17.9Sb1.3Ag2S40 from the Lengenbach deposit with the same lattice setting. Barikaite is a member of sartorite homologous series (N = 4). The unit cell of barikaite contains eight cation sites and ten anion sites. Four of the cation sites have mixed occupancies – the split sites As2–Sb2, As3–Sb3, Ag5–As5 and the site Me6 with three cations involved. Two of the lead sites, Pb1 and Pb2, display tricapped trigonal prismatic coordinations and alternate along the 8.53 Å a direction. They form zig-zag walls parallel to (001). There are three distinct [100] columns of alternating cations, As1–(As, Sb)2, Sb4–(As, Sb)3 and (As, Ag)5–(Pb, Sb)6 which together form trapezoidally configured single (013) layers. These layers aggregate into tightly-bonded double layers, separated by lone electron pair micelles. In barikaite, the predominantly As-occupied and Sb-occupied sites are distributed in a chess-board-like scheme.

GEOMETRICAL DESCRIPTION OF THE LOCAL INTEGRALS OF MOTION OF MAXWELL-BLOCH EQUATION

We represent a classical Maxwell-Bloch equation and relate it to positive part of the AKNS hierarchy in geometrical terms. The Maxwell-Bloch evolution is given by an infinitesimal action of a nilpotent subalgebra n+ of affine Lie algebra [Formula: see text] on a Maxwell–Bloch phase space treated as a homogeneous space of n+. A space of local integrals of motion is described using cohomology methods. We show that Hamiltonian flows associated with the Maxwell–Bloch local integrals of motion (i.e. positive AKNS flows) are identified with an infinitesimal action of an Abelian subalgebra of the nilpotent subalgebra n− on a Maxwell–Bloch phase space. Possibilities of quantization and lattice setting of Maxwell–Bloch equation are discussed.

The SP-hull of a Lattice-Ordered Group

There have been several recent papers on the subject of the P-hull and the SP-hull of an l-group (lattice-ordered group). The most natural formulation of the concepts was given by P. Conrad in [6]. T. Speed studied P-groups extensively in [11]; his work was motivated by earlier work by H. Nakano and I. Amemiya in a vector lattice setting. A. Vecksler [12] produced the SP-hull for f-rings. The ortho-completion of S. Bernau [2] is a related concept.