Rational Analysis Method Research Articles

The unsteady propagation of premixed flames through nonhomogeneous mixtures and thermal gradients

Recent advances in the mathematical study of unsteady laminar premixed flames have required the imposition of nearly constant flame temperature. This condition disallows investigations into such fundamentally important problems as flame propagation into thermal gradients and regions of varying equivalence ratio. Here a rational method of analysis is presented to derive asymptotic solutions for one-dimensional unsteady propagation of deflagration waves with O(1) flame temperature variations. The propagations of premixed flames down thermal and concentration gradients are studied as example problems.

化学分析によるマンガン鉱石および還元マンガン鉱石中の各種成分の分別定量および組成分析

In this report, the rational method of analysis by fractional determination of various elements, such as manganese, iron, silicon etc., in manganese and reduced manganese ores is discussed as based on the data described in the previous reports (Parts 1 to 8) is made. A method for fractional determination of manganese silicates in manganese and reduced manganese ores is also sought. After some experiments, a the following procedure for this purpose was decided upon as recommendable: Heat a 0.5 g sample of manganese or reduced manganese ore in a 50 mL solution of 18 N sulfuric acid with a small amount of hydrogen peroxide for an hour, in order to bring out all the manganese silicates (i.e. tephroite, braunite, penwithite etc.) in the sample except rhodonite in solution. The solution is then filtered after diluting with 200 mL of hot water, and adding a small amount of paper pulp; the residue containing rhodonite is washed thoroughly first with hot 0.5 N sulfuric acid solution, then, with water. The residue placed in a platimum crucible is ignited, fused with sodium carbonate, and extracted with sulfuric acid solution. The whole manganese in the extraction is determined by means of ferrous-permanganate titration, and the resultant manganese is calculated for rhodonite. The results of such analysis show that some trivalent manganese is contained only in some specific manganese ores such as braunite ore.

Rational Analysis of Heat-Exchanger Tube-Sheet Stresses

Abstract The paper presents a rational method of analysis of heat-exchanger tube-sheet stresses. While the tube sheet is taken to be a perforated plate on an elastic foundation in the manner of Gardner and Miller, it is also considered as part of an integrated indeterminate structure, and the interaction between the tube sheet and the connecting cylindrical shells and flange of the exchanger is determined so that a condition may be formulated which the edge rotation and edge moment of the tube sheet must satisfy. In general, neither the edge rotation nor the edge moment is zero; the edge of a tube sheet is therefore neither clamped nor simply supported. Application of the present method to four different types of heat exchangers is described in detail. To illustrate the method, Gardner’s example of a fixed-tube-sheet exchanger is recalculated. While Gardner’s method yields only the two limiting values of the maximum stress in the tube sheet, which differ by more than 100 per cent, the present method makes it possible to determine the exact value of this maximum stress. By means of the present method, the stresses in the other parts of the heat exchanger, namely, the tubes, shell, head, and flange, also can be calculated. As a consequence of the present analysis, it is found that, in the external-floating-head type of exchanger, the tube-sheet stress is not independent of the shell-side pressure, which is contrary to Gardner’s and Miller’s conclusions.

Labor-Turnover Records and the Labor Problem

Abstract The application of rational methods of analysis to the conduct of the operative details of industrial establishments has long been accepted as an effective means of approaching the maximum efficiency of output, and in recent years production problems of all kinds have been studied and solved by such methods. In this paper the author advocates the application of a similar mode of analysis to an increasingly important phase of the labor problem, namely, the labor turnover, or the shifting of workers from one place of employment to another. He considers various causes that have given rise to the problem and suggests other aspects of the subject that still remain to be explored, leaving a discussion of the remedies which have proved successful for future treatment.