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A one-dimensional theoretical model has been used to analyze the steady state and stability performance of a single-phase, two-phase, and supercritical natural circulation in a uniform diameter rectangular loop. Parametric influences of diameter, inlet temperature, and system pressure on the steady state and stability performance have been studied. In the single-phase liquid filled region, the flow rate is found to increase monotonically with power. On the other hand, the flow rate in two-phase natural circulation systems is found to initially increase, reach a peak, and then decrease with power. For the supercritical region also, the steady state behavior is found to be similar to that of the two-phase region. However, if the heater inlet temperature is beyond the pseudo critical value, then the performance is similar to single-phase loops. Also, the supercritical natural circulation flow rate decreases drastically during this condition. With an increase in loop diameter, the flow rate is found to enhance for all the three regions of operation. Pressure has a significant influence on the flow rate in the two-phase region, marginal effect in the supercritical region, and practically no effect in the single-phase region. With the increase in loop diameter, operation in the single-phase and supercritical regions is found to destabilize, whereas the two-phase loops are found to stabilize. Again, pressure has a significant influence on stability in the two-phase region. [DOI: 10.1115/1.4000866]

Supercritical water (SCW) has excellent heat transfer characteristics as a coolant for nuclear reactors. Besides it results in high thermal efficiency of the plant. However, the flow can experience instabilities in supercritical water cooled reactors, as the density change is very large for the supercritical fluids. A computer code SUCLIN has been developed employing supercritical water properties to carry out the steady-state and linear stability analysis of a SCW natural circulation loop (SCWNCL). The conservation equations of mass, momentum, and energy have been linearized by imposing small perturbation inflow rate, enthalpy, pressure, and specific volume. The equations have been solved analytically to generate the characteristic equation. The roots of the equation determine the stability of the system. The code has been benchmarked against published results. Then the code has been extensively used for studying the effect of diameter, heater inlet temperature, and pressure on steady-state and stability behavior of a SCWNCL. A separate computer code, NOLSTA, has been developed, which investigates stability characteristics of supercritical natural circulation loop using nonlinear analysis. The conservation equations of mass, momentum, and energy in transient form were solved numerically using finite volume method. The stable, unstable, and neutrally stable points were identified by examining the amplitude of flow and temperature oscillations with time for a given set of operating conditions. The stability behavior of loop, predicted using nonlinear analysis has been compared with that obtained from linear analysis. The results show that the stability maps obtained by the two methods agree qualitatively. The present paper describes the linear and nonlinear stability analysis models and the results obtained in detail. [DOI: 10.1115/1.4000342] Keywords: supercritical, linear, nonlinear, stability, natural circulation

CONTEXT: Ideal family size and desire for an additional child are the two most commonly used fertility preference indicators. However, little is known about the consistency over time of responses [...]

CONTEXT: Although there is a growing body of research examining the issue of nonconsensual sex among adolescents, few studies have looked at coerced sex within marriage in settings where early [...]

The birefringence of the elliptical core photonic crystal fiber with circular pores in the cladding has been studied by using higher order Mathieu functions. It is observed that the birefringence decreases with decreasing wavelength. Calculated results also indicate the sensitivity to the radius of the pores in the cladding. High birefringence up to 0.0079 is obtained. The efficacy of this proposed method is proved by comparing the results. OCIS codes: 060.2310, 060.2400.

Abstract--In this paper, we have compared the performance of a Turbo and Trellis coded optical code division multiple access (OCDMA) system. The comparison of the two codes has been accomplished [...]

Micronutrient deficiency is a serious public health concern in most developing countries. In India, iron deficiency, vitamin A deficiency, and iodine deficiency disorder are of greatest public health significance. In addition, subclinical zinc deficiency, flourosis, and fluoride-deficient dental caries are important areas of concern. The National Pilot Program on Control of Micronutrient Malnutrition was launched in 1995 to address these problems and the Department of Biochemistry and Nutrition of the All India Institute of Hygiene and Public Health (Calcutta) was entrusted to coordinate its activities. The program presently covers one northeastern and four eastern states, namely Assam, Bihar (Jharkhand), Orissa, West Bengal, and Tripura. Baseline analyses were conducted on demographic situation, food and nutrient intake pattern, nutritional deficiency diseases (e.g., iron deficiency anemia), iodine deficiency disorder, and vitamin A deficiency. It was observed that except for cereals, the diet was deficient in all other food groups. Nutrient intake (i.e., energy, protein, vitamins, and minerals) was also deficient in almost the entire state. Anthropometric indices (e.g., weight-forage and height-for-age data) indicated that large percentages of

Considers production control problems in the application of cellular manufacture. Design of a production control system; Layout of the cell; Variation of optimum schedules.