Analysis of a two unit standby system with partial failure and two types of repairs

A two dissimiliar unit standby system is analysed. The priority unit can either be in normal or partial operative mode. When the unit fails from the partial mode, it undergoes minor repair and the unit becomes operative with different failure rate. If this unit fails again, it goes to major repair after which it works as good as new. The standby unit while in use is either operative or failed. This non priority unit fails without passing through the partial failure mode and undergoes only one type of repair with different repair time distribution. Failure and repair time distributions are negative exponential and general respectively. Regenerative technique in MRP is applied to obtain several reliability characteristics of interest to system designers.     

CRYSTAL SIZE GROWTH IN THE LIQUID PHASE METHANOL SYNTHESIS CATALYST

The phenomenon of crystal growth in the methanol synthesis catalyst has been studied. Crystallite size distributions in the cuo/ZnO/Al₂O₃ methanol synthesis catalyst have been determined. The effects of temperature, reaction environment and time under reaction conditions have been studied. It is observed that water in the reaction mixture promotes crystal growth.     

LMFBR system analysis: Impact of heat transport system on core thermal-hydraulics

In discussing LMFBR thermal-hydraulic analysis, this paper focuses on the heat transport system and its impact on the predicted core behavior, particularly during off-normal or protected accident transients. Following a brief background of related work in the area of system simulation for both loop and pool-type LMFBR designs, modeling considerations for individual components such as reactor core, piping, pumps, heat exchangers and check valves, together with the overall integrated approach to system simulation, are discussed. The need for, and current approaches to, modeling pool stratification are also examined. The role of buoyancy forces in the system is clarified, with particular emphasis on its increasing influence during flow decay. Sample results are presented to illustrate the influence of system modeling details, and selection of component parameters and operational mode, on predicted core thermal-hydraulic response during protected loss-of-flow transients. From a systematic study of the effect of pump inertia for a flow coastdown to natural circulation event in a loop-type design, it is found that certain combinations of primary and secondary pump inertias can lead to core flow reversal for a sustained period, and eventual boiling in the hot fuel channel. This effect, based on its impact on core flow, is even more pronounced in pool-type designs.     

Delay-on-Demand: A Signaling Protocol to Reduce Blocking Probability in Optical Burst-Switching Networks

Optical burst switching (OBS) is emerging as one promising switching paradigm for the next generation optical networks. To support multiple services in burst-switching networks, the OBS paradigm should support some quality-of-service (QoS) provisioning. A major design issue in such networks is to reduce the blocking probability of the bursts arising due to resource contention at the intermediate core router. In this paper, we propose a signaling protocol which we call ‘Delay-on-Demand’ (OBS-DoD), to reduce blocking probability and support QoS in optical burst-switching networks. The proposed scheme guarantees that at least one of the bursts succeeds depending on its priority, propagation delay from the ingress router, and the burst-size when contention occurs at the core router. For this, we use a control packet to delay, in case of a contention, the transmission of bursts at the ingress router. We compare the performance of our proposal, by simulation, with an earlier proposed scheme, and show that the proposed OBS-DoD outperforms the earlier scheme in reducing the blocking probability. For simulation, we generated bursty traffic using an M/Pareto distribution.     

Nanorods of copper and nickel oxalates synthesized by the reverse micellar route

Nanorods of nickel and copper oxalate have been synthesized by the reverse micellar route. Powder X-ray diffraction studies and thermo gravimetric analysis confirms the formation of monophasic NiC2O4 x 2H2O and CuC2O4 x H2O. Transmission electron microscopy shows that the as prepared nanorods of nickel and copper have diameter of 250 nm and 130 nm while the length is of the order of 2.5 microm and 480 nm respectively. The aspect ratio of the nanorods could be modified by changing the solvent. The nickel oxalate nanorods appear very smooth with uniform length while the copper oxalate nanorods appear to be corrugated. Nickel oxalate dihydrate nanorods show an antiferromagnetic transition at T(N) = 34 K while the copper based nanorods show temperature independent paramagnetism.     

Drop formation in non-newtonian liquids under pulsed conditions

Drop formation from single nozzles under pulsed flow conditions in non-Newtonian fluids following the power law model has been studied. An existing model has been modified to explain the experimental data. The flow conditions employed correspond to the mixer—settler type of operation in pulsed sieve-plate extraction columns. The modified model predicts the drop sizes satisfactorily. It has been found that consideration of non-Newtonian behaviour is important at low pulse intensities and its significance decreases with increasing intensity of pulsation. Further, the proposed model for single orifices has been tested to predict the sizes of drops formed from a sieve-plate distributor having four holes, and has been found to predict the sizes fairly well in the absence of coalescence.     

Fires of insulations on tank exteriors

This paper presents a method for calculating radiative heat transfer to an adjacent tank from fire involving insulation on tank exteriors. An approximate method for calculating the radiative flux from an ignition source is also provided. The results are generalized to allow convenient estimates of safe separations for a range of tank sizes, fire intensities, and critical ignition fluxes. Wind effects are not considered in the present study. Factory Mutual Research Corporation