Simulation Optimization Studies of Routing and Process Flow Problems

Computer aided simulation is emerging as a powerful tool for numerical analysis and in conducting performance evaluations of complex systems that depend on a multitude of variables. The primary objective in such simulation studies is to gauge the performance of the system under a various constraints and operating conditions. The effects of changing the operating parameter space can thus be analyzed without having to implement costly changes. Simulations are also carried out for the baseline scenarios to verity and validate the basic underlying system model. In this thesis research, two practical problems were studied through numerical modeling, and optimized solutions obtained for both. Optimizing the pick-up and delivery routes using a commercial software tool was the first task. Optimization of a production assembly line using a discrete event simulation tool was the second project that was carried out. The primary objective for the first task was to explore various routing scenarios and determine delivery routes that would minimize the total network mileage, while maintaining the pick-up time slots requested by the clients. A related task was to evaluate the possible advantages of centralizing all routing activity from a single site, instead of the two-hub scenario currently in effect. A total of eight different scenarios were studied as part of this effort. The second task involved optimization of the throughput of a fuel injector plant by placing buffers within the assembly lines for increased productivity

On the possible use of satellite fixed positions for Argo profiles in case of GPS failures

INCOIS had deployed iridium based PROVOR Bio-Argo floats obtained from NKE, France. These floats are fitted with GPS for obtaining accurate position of the Argo profiles. However there are cases where in the GPS fitted with the Argo floats tend to give wrong positions owing to unknown reasons. In this present work we discuss the possibilities of using the Iridium satellite fixed position in case of GPS failures. For this, analysis was done by comparing the GPS and satellite fixed profiles positions of good floats. These statistics can be used for using the satellite fixed position in case of GPS failures. For each comparison the satellite fixed position with least circular error probability (CEP) radius was chosen. The study suggested that on a average the satellite fixed positions tend to differ from the GPS fixed positions by 0.03 degrees. CEP radii are found to be consistent with the difference between satellite fixed position and GPS position. Based on this we suggest a quality flag of 2 for positions with CEP radius <=4 and flag 4 for any other positions

The effect of natural organic matter on the adsorption of mercury to bacterial cells

We investigated the ability of non-metabolizing Bacillus subtilis, Shewanella oneidensis MR-1, and Geobacter sulfurreducens bacterial species to adsorb mercury in the absence and presence of Suwanee River fulvic acid (FA). Bulk adsorption and X-ray absorption spectroscopy (XAS) experiments were conducted at three pH conditions, and the results indicate that the presence of FA decreases the extent of Hg adsorption to biomass under all of the pH conditions studied. Hg XAS results show that the presence of FA does not alter the binding environment of Hg adsorbed onto the biomass regardless of pH or FA concentration, indicating that ternary bacteria–Hg–FA complexes do not form to an appreciable extent under the experimental conditions, and that Hg binding on the bacteria is dominated by sulfhydryl binding. We used the experimental results to calculate apparent partition coefficients, Kd, for Hg under each experimental condition. The calculations yield similar coefficients for Hg onto each of the bacterial species studies, suggesting there is no significant difference in Hg partitioning between the three bacterial species. The calculations also indicate similar coefficients for Hg–bacteria and Hg–FA complexes. S XAS measurements confirm the presence of sulfhydryl sites on both the FA and bacterial cells, and demonstrate the presence of a wide range of S moieties on the FA in contrast to the bacterial biomass, whose S sites are dominated by thiols. Our results suggest that although FA can compete with bacterial binding sites for aqueous Hg, because of the relatively similar partition coefficients for the types of sorbents, the competition is not dominated by either bacteria or FA unless the concentration of one type of site greatly exceeds that of the other

Stoichiometry of mercury-thiol complexes on bacterial cell envelopes

We have examined the speciation of Hg(II) complexed with intact cell suspensions (1013 cells L− 1) of Bacillus subtilis, a common gram-positive soil bacterium, Shewanella oneidensis MR-1, a facultative gram-negative aquatic organism, and Geobacter sulfurreducens, a gram-negative anaerobic bacterium capable of Hg-methylation at Hg(II) loadings spanning four orders of magnitude (120 nM to 350 μM) at pH 5.5 (± 0.2). The coordination environments of Hg on bacterial cells were analyzed using synchrotron based X-ray Absorption Near Edge Structure (XANES) and Extended X-ray Absorption Fine Structure (EXAFS) spectroscopy at the Hg LIII edge. The abundance of thiols on intact cells was determined by a fluorescence-spectroscopy based method using a soluble bromobimane, monobromo(trimethylammonio)bimane (qBBr) to block thiol sites, and potentiometric titrations of biomass with and without qBBr treatment. The chemical forms of S on intact bacterial cells were determined using S k-edge XANES spectroscopy. Hg(II) was found to complex entirely with cell bound thiols at low Hg:biomass ratios. For Bacillus subtilis and Shewanella oneidensis MR-1 cells, the Hg—S stoichiometry changed from Hg—S₃ to Hg—S₂ and Hg—S (where ‘S’ represents a thiol site such as is present on cysteine) progressively as the Hg(II) loading increased on the cells. However, Geobacter sulfurreducens did not form Hg—S₃ complexes. Because the abundance of thiol was highest for Geobacter sulfurreducens (75 μM/g wet weight) followed by Shewanella oneidensis MR-1 (50 μM/g wet weight) and Bacillus subtilis (25 μM/g wet weight), the inability of Hg(II) to form Hg—S₃ complexes on Geobacter sulfurreducens suggests that the density and reactivity of S-amino acid containing cell membrane proteins on Geobacter sulfurreducens are different from those of Bacillus subtilis and Shewanella oneidensis MR-1. Upon saturation of the high affinity thiol sites at higher Hg:biomass ratios, Hg(II) was found to form a chelate with α-hydroxy carboxylate anion. The stoichiometry of cell envelope bound Hg-thiol complexes and the associated abundance of thiols on the cell envelopes provide important insights for understanding the differences in the rate and extent of uptake and redox transformations of Hg in the environment

On the possible use of satellite fixed positions for Argo float profiles in case of wrong fixes by GPS

Indian National Centre for Ocean Information Services (INCOIS) had deployed Iridium based Provor Bio-Argo floats obtained from NKE Instrumentation, France. These floats are fitted with GPS for obtaining accurate position of the Argo profiles. However there are cases where in the GPS fitted with the Argo floats tend to give wrong coordinates of profile position owing to unknown reasons. In the present work we discussed the possibilities of using the Iridium satellite fixed position as a substitute of GPSfixed locations in place of wrong GPS positions. For this, statistical analysis was done by comparing the GPS and Iridium satellite fixed profiles positions of 258 profiles from 5 floats which had no problem with the GPS. For each comparison, the GPS fixed position with least Circular Error Probability (CEP) radius was chosen. It was observed that CEP radii are relatively consistent with distances between GPS and Iridiumsatellite fixes with a correlation of 0.85. The study suggests that on an average the Iridium satellite based positions tend to differ from the GPS fixed positions by 0.09°. On the whole CEP radii are found to be consistent with the difference between Iridium satellites and GPS fixed positions. Based on this we suggest a quality flag of 2 (implying probably well) for positions with CEP radius less than or equal to 4 Km and flag 4 (implying bad) for all other positions

As(3)p: A Fast Algorithm to Search Structurally Similar Protiens

Protein structure comparison is essential for understanding various aspects of protein structure, function and evolution. It can be used to explore the structural diversity and evolutionary patterns of protein families. In view of the above, a new algorithm is proposed which performs faster protein structure comparison using the peptide backbone torsional angles. It is fast, robust, computationally less expensive and efficient in finding structural similarities between two different protein structures and is also capable of identifying structural repeats within the same protein molecule

Advancement of steam generation process in water tube boiler using Taguchi design of experiments

Steam generation and utilization are needed in many industries and home appliances with, specific requirements. Though there are numerous categories of boilers available for steam generation, this analysis concentrated on the water tube boiler since it produces more steam and offers better safety measures. Taguchi techniques are considered in this entire research work completed through the design of experiments (DOE). Orthogonal array L16 is selected to examine the steam generation with four process parameters and four levels. Selected process parameters are namely temperature of feed water (◦C), the pressure of feed water (bar), cold water supply (liters), and boiler drum pressure (bar). The response of this study is the as the steam generation to since increasing the steam is a target of this investigation. The experimental value of the steam generation is compared with the desired range; most of the response values are within the predicted value. Further, the superheated steam temperature and pressure analysis were also carried out. The maximum steam generation is achieved as 84.31 L; registered in the 15th run of the experiment

Role of Morphology and Förster Resonance Energy Transfer in Ternary Blend Organic Solar Cells

Organic solar cells (OSCs) fabricated from ternary blend thin film absorbers are designed to maximize the range of absorption in the solar spectrum and thus increase the short-circuit current density (J$_{SC}$) of the device. Herein, we report OSCs formed with two different compositions of ternary blend thin films comprising two electron donors and one acceptor, namely, PTB7-Th/PCDTBT/IT4F and PTB7-Th/PBDB-T/IT4F. We evaluate the role of Förster resonance energy transfer (FRET) and blend morphology to achieve composition-dependent device performance. We observed ≥10% increment in J$_{SC}$ for both the ternary blends as compared to that for the PTB7-Th:IT4F binary blend, resulting in an enhanced power conversion efficiency (PCE) up to 10.34% for the PTB7-Th:PBDB-T:IT4F blend. We provide evidence that the two foremost parameters that control the PCE are blend morphology and FRET between donor components. The improved exciton generation rate for PCDTBT-based ternary blends was achieved, suggesting effective contribution of FRET toward enhanced device photocurrent, whereas the PBDB-T-based ternary blend excelled mainly due to suppressed carrier recombination as a result of favorable orientation with PTB7-Th/IT4F