Scheduling Network and Computing Resources for Sliding Demands in Optical Grids

In this paper, we consider the problem of scheduling lightpaths and computing resources for sliding grid demands in WDM networks. Each sliding grid demand is represented by a tuple (v,R,c,p,q,l) , where v is the client node, R is the resource-group which includes a group of predefined resource nodes, c is the required amount of computing resources, [p,q] is the time window and l is the demand duration. With each demand, the scheduling algorithm is required to decide the start time t (p les t les q - l), reserve an amount of c computing resources at a resource node v ^' isin R and provision a primary lightpath as well as a backup lightpath from v ^' to v . The reserved computing resources and lightpaths are used during [t,t + l]. Unlike the sequential approach wherein the start time, the network resources (lightpaths) and the computing resources are considered one after another, in our work we use the joint scheduling approach wherein the resources and the start time are examined jointly. We consider sliding demands with static and dynamic arrival patterns. We develop an integer linear programming (ILP) formulation to obtain optimal results. For the reason of scalability, we propose heuristic algorithms based on joint resource scheduling and study their effectiveness through simulation experiments.     

Optimization of alkaline protease production from Shewanella oneidensis MR‐1 by response surface methodology

BACKGROUND: The proteases are among the most important groups of enzymes. Therefore, it is important to produce inexpensive and optimized media for large‐scale commercial production. In the present work, three different Shewanella species were screened on skim milk agar medium for their ability to produce alkaline protease. The effects of different culture conditions were optimized for alkaline protease production by S. oneidensis MR‐1 using a Box–Behnken design combined with response surface methodology (RSM). RESULTS: Highest yield (112.90 U mL^?1) of protease production was obtained at pH 9.0, a temperature of 30 °C, glucose (12.5 g L^?1), tryptone (12.5 g L^?1) and an incubation period of 36 h. A second‐order polynomial regression model was used for analysis of the experiment. The experimental values were in good agreement with predicted values, with correlation coefficient 0.9996. CONCLUSION: Carbon and nitrogen, pH, temperature and incubation period were chosen as the main factors to be used in an experimental design for optimization to produce low‐cost enzymes, potentially for use on an industrial scale. A 60% increase in enzyme activity was achieved in the optimized medium compared with the original medium. Copyright © 2008 Society of Chemical Industry     

Holographic characterization of azo-dye doped poly (methyl methacrylate) films

Many holographic techniques have been developed for non-destructive studies and characterization of materials. In this paper, discussion will be made about the employed holographic technique to characterize the poly(methyl methacrylate) (PMMA) matrices doped with azo-dyes. In this manner we were able to study the effect of the thickness of the samples, the effect of concentration of the azo-dyes and of PMMA and the effect of aging (storage time) on the holographic efficiency (diffraction efficiency) of these materials. Auto-erasable holographic gratings have been successfully recorded on azo-dye doped PMMA films and the dynamic diffraction efficiency was monitored with light different from that used for the recording.     

Interfacial Thermal Resistance and the Solidification Behavior of the Al/SiCp Composites

The objective of this investigation is to study the effects of applied pressure on the solidification time and interfacial thermal resistance of A356/10% SiC_p during squeeze casting. Samples were prepared for various but constant squeeze pressures up to 130 MPa while maintaining the melt and mold temperatures at 800°C and 400°C, respectively. It was observed that the solidification time was 60 s when no squeeze pressure was applied but it decreased to 42 s when the squeeze pressure was maintained at 130 MPa. The results also showed that the cooling rate increased with squeeze pressure. The solidification time calculated from one-dimensional heat flow theory was found to be close to that obtained from the experimental cooling curves. The interfacial thermal resistance between the mold and the casting was calculated and it decreases when the squeeze pressure increases.     

Plasma reforming of aliphatic hydrocarbons with CO/sub 2/

CO/sub 2/ reforming of methane, propane, and neopentane was investigated with a ferroelectric packed-bed reactor (FPR) in N/sub 2/ at temperatures ranging from 298 K to 433 K. The reaction behavior of the hydrocarbons was greatly affected by their chemical structures and reaction temperature. At ambient temperature, hydrocarbon conversion decreased in the following order: neopentane/spl Gt/propane>methane. With an increase in reaction temperature, hydrocarbon reactivity was enhanced with only a slight difference in the conversions of the above hydrocarbons. CO/sub 2/ deoxygenation was a clean reaction irrespective of reaction temperature, but CO was formed not only from CO/sub 2/ but also from hydrocarbons. No chemical interaction between CO/sub 2/ and the hydrocarbons in nonthermal plasma was observed. Temperature effect on the H/sub 2/ yield depended on the hydrocarbon structure. Higher H/sub 2/ yields were obtained for neopentane and propane than for methane. Product composition and carbon balance were also affected by the hydrocarbon structure, relative concentrations of hydrocarbons to CO/sub 2/, and temperature.     

Electrical conductivity of modified poly(vinyl chloride)

Chemical modification of poly(vinyl chloride) (PVC) by dehydrochlorination with ethanolic KOH is found to yield modified PVC with conjugated polyene sequence. The semiconducting nature of ethoxide-modified PVC is illustrated with temperature dependence of conductivity (σ). The relative ratios (r) of conductivity,σ _modifiedpvc /σ _{unmodifiedpvc} , are greater than unity in the temperature range 50° to 180°C,r being maximum in the vicinity of glass-transition temperature (T _g).T _g inferred from conductivity-temperature profiles is found to be greater for modified PVC relative to unmodified PVC, which is explicable in terms of restricted free rotation limiting segmental motion. For comparison with the conductivity andT _g of ethoxide-modified PVC, LiCl-modified PVC and (aniline + S₂O ₈ ²⁻ )-modified PVC have also been studied.     

Novel solid hypergolic fuels for hybrid propellants

A new class of compounds, viz., monothiocarbohydrazones, have been found to be hypergolic with anhydrous and red fuming nitric acids. A study of the ignition delays of the various thiocarbohydrazonenitric acid systems as a function of particle size and fuel/oxidizer ratio reveals no significant effect by these parameters. The observed ignition delays have been explained in terms of the chemical reactivity and structure of these compounds.     

Effects of Temperature, Voltage Properties, and Initial Gas Composition on the Plasma Reforming of Aliphatic Hydrocarbons With $hbox{CO}_{{bf 2}}$

CO₂ reforming of methane, propane, and neopentane was investigated with a ferroelectric packed-bed and silent discharge plasma reactors in N₂ at temperature from 303 to 433 K. The conversions of the substrate hydrocarbons and CO₂, and the yields of H₂ and CO were expressed as functions of reactor energy density irrespective of voltage waveform. The positive temperature effect on the hydrocarbon conversions and the product yields can be ascribed to the promotion of secondary decomposition of the hydrocarbons induced by radicals formed in situ because reactor power consumption was not affected by reaction temperature at the same frequencies and peak-to-peak voltages. At 303 K, the reactivity of the hydrocarbon decreased in the following order: neopentane > propane > methane. At 433 K, propane and neopentane showed the same reactivities. The molar ratio of H₂ to CO was affected by hydrocarbon structure and the initial concentration ratio of CO₂ to the carbon atom in hydrocarbon, but not by reaction temperature. Better carbon balances were obtained for all the hydrocarbons at 433 K than at 303 K, suggesting higher reaction efficiencies at 433 K. Carbon balance was also affected by initial gas composition, and the carbon atoms in reacted neopentane were quantitatively recovered as CO, CO₂ and lighter hydrocarbons at 10 of [CO₂]/[neopentane].     

A review on thermal energy storage systems in solar air heaters

The drying needs of agricultural, industrial process heat requirements and for space heating, solar energy is one of the prime sources which is renewable and pollution free. As the solar energy is inconsistent and nature dependent, more often there is a mismatch between the solar thermal energy availability and requirement. This drawback could be addressed to an extent with the help of thermal energy storage systems combined with solar air heaters. This review article focuses on solar air heaters with integrated and separate thermal energy storage systems as well as greenhouses with thermal storage units. A comprehensive study was carried out in solar thermal storage units consisting of sensible heat storage materials and latent heat storage materials. As the phase change heat storage materials offer many advantages over the sensible heat storage materials, the researchers are more interested in this system. The charging and discharging characteristics of thermal storage materials with various operational parameters have been reported. All the possible solar air heater applications with storage units have also been discussed.