Optimal delays in decision and control

Computations involved in controlling a system or a decision process are time-consuming in practice. The problem of optimally choosing the estimation and control delays is formulated in the dynamic programming framework and illustrated by examples. Selection of optimal estimation and control algorithms is outlined conceptually.     

Low-temperature complete combustion of a dilute mixture of methane and propane over transition-metal-doped ZrO2 catalysts: effect of the presence of propane on methane combustion

Complete combustion of dilute methane alone or a dilute mixture of methane and propane over transition-metal (viz. Mn, Co, Cr, Fe, and Ni)-doped ZrO2 (cubic) catalysts at different temperatures (523-873 K) and a space velocity of 51,000 cm3 x g(-1) x h(-1) has been investigated for controlling methane and propane emissions from exhaust gases. The catalysts are compared for their catalytic ignition temperature and activity in the combustion of propane and methane in the presence of each other. The methane combustion activity of all the catalysts is strongly influenced by the presence of propane; it is decreased markedly. In the combustion of mixed methane and propane the Mn-doped ZrO2 and Cr-doped ZrO2 catalysts show the highest activity in the combustion of methane and propane, respectively; the Ni-doped ZrO2 shows the lowest activity in both cases. In the combustion of mixed methane and propanethe propane combustion is enhanced butthe methane combustion retarded when the Cr-doped ZrO2 and Mn-doped ZrO2 catalysts in a 1:1 ratio are used together in different ways (mixed or in layers).     

Reliability analysis of combined wind-electric and conventional generation systems

Probabilistic models for wind-electric conversion systems and their use in the reliability studies of combined wind-electric and conventional generation systems are discussed. Representative numerical results for a typical site in Hawaii for the month with an excellent wind regime are presented. The results and discussions documented in this paper should be helpful in the planning and incorporation of wind-electric systems as a component in the generation mixes of the utility systems of the future.     

Surface dendrite in lithium niobate crystals

The growth of a surface dendrite of a complex nature has been observed in lithium niobate grown perpendicular to the c-axis. The dendrite limbs in different directions are described and a growth mechanism is suggested. It was found that a small volume of the melt in the crucible and a rapid rate of cooling do not favour the dendritic growth.     

Microstructures,thermal diffusion and decomposition studies in the two phase solution grown mixed crystals of NaCl and KCl

Mixed NaCl-KCl crystals are grown from water solution. Thermal diffusion, decomposition and microstructures studies by employing the etching technique are reported. It is shown that microstructures consisting of alternate lamellae of NaCl and KCl arranged in 〈100〉 and 〈110〉 directions in the two-phase mixed NaCl-KCl crystals observed at room temperature get converted to the one consisting of random mixture of both the phases on finer scale on heating at 300°C for 30 hr. The dissociated matrix on heating at 600°C for 15 hr regains almost all the characteristics of a single crystal transforming the material into single-phase mixed (NaK) Cl crystals. The temperature dependence of the thermal diffusion is discussed.     

Distribution of phosphoinositides among subfractions of rat brain myelin

Rat brain myelin was separated into three subfractions, heavy, medium, and light, and the concentrations of phosphatidic acids (PA), phosphatidylinositol (PI), di- (DPI), and triphosphoinositide (TPI) in these fractions were determined. PI was evenly distributed among the fractions, and PA, DPI, and TPI occurred in highest concentrations in the “light” myelin. This result indicates that these fast metabolizing lipids play an important role in the tightly packed central lamellae of the myelin sheath.     

Toxic organic wastewater treatment through solid phase transformation with re-use potential

A novel treatment of wastewater generated in the production of dinitrobenzene was examined. The method involves solid phase transformation of the wastewater by slaking with lime, followed by removal of the organics contained in the lime in a muffle furnace. The regenerated lime may be re-used, e.g., for the neutralization of acidic wastewaters resulting from the manufacture of m-aminophenol. A flowsheet for the integrated treatment of dinitrobenzene and m-aminophenol plant wastewaters is proposed.     

Influence of variation in calcium content on casein micelle stability and techno-functional properties of buffalo milk

Changes in techno-functional properties of buffalo milk were evaluated due to variation in calcium content. Decalcification resulted in significant variation in ζ-potential, casein size, colour and η_app. However, calcium addition only influenced ζ-potential of milk. In case of acid gelation, the time and temperature required for coagulation decreased significantly for both calcium-depleted and -added milks. However, during chymosin gelation, only 20%–30% of calcium-depleted milk coagulated with an increased clotting time. Furthermore, calcium addition increased firmness, consistency and cohesiveness of both chymosin and acid-induced gelation.     

Eosin-G and ethyl eosin dye sensitized CdS nanowires towards dye sensitized solar cells applications

One dimensional (1-D) CdS nanowires have been grown through a low temperature chemical route and have been sensitized with eosin-G and ethyl eosin dyes to broaden the absorption spectrum of CdS and to enhance the photoelectrochemical (PEC) performance under illumination. The used method is advantageous due to its simplicity, low cost, scalability, and controllability. Interestingly, eosin-G and ethyl eosin dyes yield nearly four- and six-fold increase in device efficiency compared to bare CdS when tested in dye-sensitized solar cell assembly. Structural, surface morphological, optical, and surface wettability studies have been formulated for CdS, whereas identification of materials along with PEC investigations were conducted through current density–voltage (J-V), external quantum efficiency (EQE), characteristics under the illumination of 94.6 mW/cm² (AM 1.5G), and electrochemical impedance spectroscopy (EIS).     

A genetic algorithmic approach for optimization of surface roughness prediction model

Due to the widespread use of highly automated machine tools in the industry, manufacturing requires reliable models and methods for the prediction of output performance of machining processes. The prediction of optimal machining conditions for good surface finish and dimensional accuracy plays a very important role in process planning. The present work deals with the study and development of a surface roughness prediction model for machining mild steel, using Response Surface Methodology (RSM). The experimentation was carried out with TiN-coated tungsten carbide (CNMG) cutting tools, for machining mild steel work-pieces covering a wide range of machining conditions. A second order mathematical model, in terms of machining parameters, was developed for surface roughness prediction using RSM. This model gives the factor effects of the individual process parameters. An attempt has also been made to optimize the surface roughness prediction model using Genetic Algorithms (GA) to optimize the objective function. The GA program gives minimum and maximum values of surface roughness and their respective optimal machining conditions.