Development of MTV Compositions as Igniter for HTPB/AP Based Composite Propellants

MTV compositions were prepared by keeping the magnesium/Teflon ratio constant and increasing the Viton content of the mixture up to 14% by an increment of 2% to investigate the effect of binder content on the heat of explosion, which is found to increase with the increasing Viton percentage as the magnesium content concomitantly goes down toward the stoichiometric value. In the second part of the study, fuel-rich MTV compositions were prepared by changing the magnesium content and keeping the Viton fraction constant at a specific value to investigate the effect of magnesium content on the heat of explosion and combustion characteristics. The observed general trend is that the heat of explosion of MTV compositions decreases as the magnesium content increases. All the MTV compositions were tested in a closed vessel to measure the maximum pressure achieved and the rate of reaching this pressure. The ignition performance of three selected MTV compositions was examined in 2.75 inch rocket motor by using the same charge of igniter and the same HTPB/AP composite propellant of the equal amount in each test. Two of them have excellent ignition performance and, therefore, can be used as igniter for the HTPB/AP based composite rocket propellants.     

Batch kinetics and isotherms for biosorption of copper(II) ions onto pre-treated powdered waste sludge (PWS)

Waste sludge samples from different plants were tested for Cu(II) ion biosorption capacities with and without pre-treatment. Waste sludge from a paint industry wastewater treatment plant was found to perform better than the others after pre-treatment with 1% H(2)O(2). Powdered waste sludge (PWS) from the paint industry wastewater treatment plant was used for recovery of Cu(II) ions from aqueous solution by biosorption after pre-treatment with 1% H(2)O(2). Batch kinetics and isotherms of biosorption of Cu(II) ions were investigated at variable initial Cu(II) concentrations between 50 and 400 mg l(-1) with a PWS particle size of 64 microm. The pseudo-first and -second order kinetic models were used to correlate the experimental data. The kinetic constants were determined for both models and the second order kinetic model was found to be more suitable. The Langmuir, Freundlich and the generalized isotherm models were used to correlate the equilibrium biosorption data and the isotherm constants were determined. The Langmuir isotherm was found to fit the experimental data better than the other isotherms tested. The maximum biosorption capacity (116 mg g(-1)) of the pre-treated powdered waste sludge for Cu(II) ions was found to be superior as compared to the other biosorbents reported in literature.     

Effects of Reagent Concentrations on Advanced Oxidation of Amoxicillin by Photo-Fenton Treatment

The degradation and mineralization of amoxicillin in an aqueous solution was accomplished by using a photo-Fenton treatment. An ultraviolet light source with a 254-nm wavelength was used with hydrogen peroxide (H2O2) and iron(II). The effects of reagent concentrations on amoxicillin degradation and mineralization were investigated systematically by using the Box-Behnken statistical experiment design. Amoxicillin (10–200??mgL-1), H2O2 (10–500??mgL-1), and iron(II) (0–50??mgL-1) concentrations were considered independent variables; the percent amoxicillin degradation and the total organic carbon (TOC) removal (mineralization) were the objective functions to be maximized. Both H2O2 and iron(II) concentrations affected the extent of the amoxicillin degradation and mineralization. The amoxicillin degradation was completed within 2.5?min, and 53% mineralization took place within 60?min. The optimum H2O2∶Fe∶amoxicillin ratio that resulted in complete amoxicillin degradation and 53% mineralization was 100∶40∶105??mgL-1.     

Bio-hydrogen production from acid hydrolyzed wheat starch by photo-fermentation using different Rhodobacter sp

Hydrogen gas production from sugar solution derived from acid hydrolysis of ground wheat starch by photo-fermentation was investigated. Three different pure strains of Rhodobacter sphaeroides (RV, NRLL and DSZM) were used in batch experiments to select the most suitable strain. The ground wheat was hydrolyzed in acid solution at pH = 3 and 90 °C in an autoclave for 15 min. The resulting sugar solution was used for hydrogen production by photo-fermentation after neutralization and nutrient addition. R. sphaeroides RV resulted in the highest cumulative hydrogen gas formation (178 ml), hydrogen yield (1.23 mol H₂ mol⁻¹ glucose) and specific hydrogen production rate (46 ml H₂ g⁻¹ biomass h⁻¹) at 5 g l⁻¹ initial total sugar concentration among the other pure cultures. Effects of initial sugar concentration on photo-fermentation performance were investigated by varying sugar concentration between 2.2 and 13 g l⁻¹ using the pure culture of R. sphaeroides RV. Cumulative hydrogen volume increased from 30 to 232 ml when total sugar concentration was increased from 2.2 to 8.5 g l⁻¹. Further increases in initial sugar concentration resulted in decreases in cumulative hydrogen formation. The highest hydrogen formation rate (3.69 ml h⁻¹) and yield (1.23 mol H₂ mol⁻¹ glucose) were obtained at a sugar concentration of 5 g l⁻¹.     

Hydrogen production by combined dark and light fermentation of ground wheat solution

Ground waste wheat was subjected to combined dark and light batch fermentation for hydrogen production. The dark to light biomass ratio (D/L) was changed between 1/2 and 1/10 in order to determine the optimum D/L ratio yielding the highest hydrogen formation rate and the yield. Hydrogen production by only dark and light fermentation bacteria was also realized along with the combined fermentations. The highest cumulative hydrogen formation (CHF = 76 ml), hydrogen yield (176 ml H₂ g⁻¹ starch) and formation rate (12.2 ml H₂ g⁻¹ biomass h⁻¹) were obtained with the D/L ratio of 1/7 while the lowest CHF was obtained with the D/L ratio of 1/2. Dark–light combined fermentation with D/L ratio of 1/7 was faster as compared to the dark and light fermentations alone yielding high hydrogen productivity and reduced fermentation time. Dark and light fermentations alone also yielded considerable cumulative hydrogen, but slower than the combined fermentation.     

Comparison of kernel estimators,perceptrons and radial-basis functions for OCR and speech classification

We compare kernel estimators, single and multi-layered perceptrons and radial-basis functions for the problems of classification of handwritten digits and speech phonemes. By taking two different applications and employing many techniques, we report here a two-dimensional study whereby a domain-independent assessment of these learning methods can be possible. We consider a feed-forward network with one hidden layer. As examples of the local methods, we use kernel estimators like k-nearest neighbour (k-nn), Parzen windows, generalised k-nn, and Grow and Learn (Condensed Nearest Neighbour). We have also considered fuzzy k-nn due to its similarity. As distributed networks, we use linear perceptron, pairwise separating linear perceptron and multi-layer perceptrons with sigmoidal hidden units. We also tested the radial-basis function network, which is a combination of local and distributed networks. Four criteria are taken for comparison: correct classification of the test set; network size; learning time; and the operational complexity. We found that perceptrons, when the architecture is suitable, generalise better than local, memory-based kernel estimators, but require a longer training and more precise computation. Local networks are simple, leant very quickly and acceptably, but use more memory.