Radiation from Fine Particle Clouds in High-Temperature Combustion Gas

Radiation from fine particle cloud floating in high-temperature combustion gas was studied theoretically and the effects of temperature, its distribution, absorption thickness and the distribution of volumetric concentration were made clear. Radiations from particle clouds of carbon, ferric oxide, converter ash, diatomaceous earth and boiler ash were measured and the emissivity of particle cloud which has equal absorption thickness decreases in the following order of carbon, ferric oxide, converter ash, diatomaceous earth and boiler ash. The order of these emissivities agreed with that of the emissivities of particle-piled surfaces. Empirical formulae were obtained for the relation between the emissivity and absorption thickness

Calculation Method of the Optimum Configurations of the Extended Surfaces with Simultaneous Conductive, Convective and Radiative Heat Transfer in Heat Exchanger

A simultaneous conductive, convective and radiative heat transfer in the extended surface systems of longitudinally finned cylinders and circumferentially finned cylinders is treated analytically, by taking the radiative interaction into consideration. A procedure to determine the optimum configurations of extended surfaces is examined for the various kinds of combinations of six heat transfer parameters from the viewpoint of saving fin material. It is found that if the radiative interaction is not taken into consideration, wrong results are included. Instead of using the complex optimization algorithm, a graphical expression is adopted to show the numerical coefficients and indices in the formulas which give the optimum dimensionless fin height and the minimum fin volume

Experimental Study on Luminous Flame

In the experimental furnace of comparatively large scale, the radiant heat transfer from the flame and the soot formation in the flames of the liquid fuel and gaseous fuel are studied. In the luminous flame of the liquid fuel, the soot concentrations and the size distributions of soot particles differ considerably by the burning methods, and particles larger than 10μ are often found. Even in the luminous flame of the gaseous fuel, the large particles are also found and the size distributions are different from the previously accepted knowledge obtained in very small gas flames. The chemical compositions of soot particles of each flame also vary at the various positions. The radiation from the cloud of soot particles is affected remarkably by the size distribution of the soot particles and a little by the chemical composition. The relation by which the emissivity of the luminous flame can be estimated is obtained

Conduction-Radiation Property of Ceramic and Graphite Fiber Thermal Insulation Mat

The thermal conductivities for four typical kinds of heat resisting fibrous thermal insulation mats were obtained by the steady state parallel plates method in a vacuum condition. These experimental results were correlated by a combined conduction and radiation heat transfer model to determine the conduction thermal conductivity and the extinction coefficient which govern the heat transfer in the layer of fibrous insulating material. On the basis of these values, a new simple method was proposed to estimate the thermal conductivities of the four materials as a function of the bulk density and the mean temperature in the insulation layer

Construction of N = 2 Chiral Supergravity Compatible with the Reality Condition

We construct N = 2 chiral supergravity (SUGRA) which leads to Ashtekar's canonical formulation. The supersymmetry (SUSY) transformation parameters are not constrained at all and auxiliary fields are not required in contrast with the method of the two-form gravity. We also show that our formulation is compatible with the reality condition, and that its real section is reduced to the usual N = 2 SUGRA up to an imaginary boundary term.Comment: 16 pages, late

Supersymmetry algebra in N = 1 chiral supergravity

We consider the supersymmetry (SUSY) transformations in the chiral Lagrangian for $N = 1$ supergravity (SUGRA) with the complex tetrad following the method used in the usual $N = 1$ SUGRA, and present the explicit form of the SUSY trasformations in the first-order form. The SUSY transformations are generated by two independent Majorana spinor parameters, which are apparently different from the constrained parameters employed in the method of the 2-form gravity. We also calculate the commutator algebra of the SUSY transformations on-shell.Comment: 10 pages, late

Minimal Off-Shell Version of N = 1 Chiral Supergravity

We construct the minimal off-shell formulation of N = 1 chiral supergravity (SUGRA) introducing a complex antisymmetric tensor field $B_{\mu \nu}$ and a complex axial-vector field $A_{\mu}$ as auxiliary fields. The resulting algebra of the right- and left-handed supersymmetry (SUSY) transformations closes off shell and generates chiral gauge transforamtions and vector gauge transformations in addition to the transformations which appear in the case without auxiliary fields.Comment: 9 pages, late

Canonical formulation of N = 2 supergravity in terms of the Ashtekar variable

We reconstruct the Ashtekar's canonical formulation of N = 2 supergravity (SUGRA) starting from the N = 2 chiral Lagrangian derived by closely following the method employed in the usual SUGRA. In order to get the full graded algebra of the Gauss, U(1) gauge and right-handed supersymmetry (SUSY) constraints, we extend the internal, global O(2) invariance to local one by introducing a cosmological constant to the chiral Lagrangian. The resultant Lagrangian does not contain any auxiliary fields in contrast with the 2-form SUGRA and the SUSY transformation parameters are not constrained at all. We derive the canonical formulation of the N = 2 theory in such a manner as the relation with the usual SUGRA be explicit at least in classical level, and show that the algebra of the Gauss, U(1) gauge and right-handed SUSY constraints form the graded algebra, G^2SU(2)(Osp(2,2)). Furthermore, we introduce the graded variables associated with the G^2SU(2)(Osp(2,2)) algebra and we rewrite the canonical constraints in a simple form in terms of these variables. We quantize the theory in the graded-connection representation and discuss the solutions of quantum constraints.Comment: 19 pages, Latex, corrected some typos and added a referenc

The selective elimination of messenger RNA underlies the mitosis–meiosis switch in fission yeast

The cellular programs for meiosis and mitosis must be strictly distinguished but the mechanisms controlling the entry to meiosis remain largely elusive in higher organisms. In contrast, recent analyses in yeast have shed new light on the mechanisms underlying the mitosis–meiosis switch. In this review, the current understanding of these mechanisms in the fission yeast Schizosaccharomyces pombe is discussed. Meiosis-inducing signals in this microbe emanating from environmental conditions including the nutrient status converge on the activity of an RRM-type RNA-binding protein, Mei2. This protein plays pivotal roles in both the induction and progression of meiosis and has now been found to govern the meiotic program in a quite unexpected manner. Fission yeast contains an RNA degradation system that selectively eliminates meiosis-specific mRNAs during the mitotic cell cycle. Mmi1, a novel RNA-binding protein of the YTH-family, is essential for this process. Mei2 tethers Mmi1 and thereby stabilizes the transcripts necessary for the progression of meiosis