ABSTRACT LEAD(II) AND AMMONIUM EXCHANGE on Na-FORM of G&Ouml / RDES CLINOPTILOLITE ASiroglu, Sedat M.S., Department of Chemical Engineering Supervisor Prof. Dr. Hayrettin Y&uuml / cel September 2006, 89 pages Natural zeolites, especially clinoptilolite, have the ability of removing certain cations from wastewater by utilizing ion exchange and adsorption. In this study, ion exchange behaviour of G&ouml / rdes clinoptilolite at particle size range (0.5-0.25 mm) for lead and ammonium removal was investigated to establish the conditions under which clinoptilolite may be used in an economical and effective manner. Experiments were divided into two parts. Batch and continuous (column) experiments were carried out. In the batch experiments, experimental isotherms of NH4+-Na+, Pb2+-Na+ binary systems and NH4+-Pb2+-Na+ ternary system were obtained as the graphs of equivalent fractions of exchanging cation in solution versus equivalent fractions of cation in zeolite. It was determined that clinoptilolite has affinity for Pb2+ and NH4+ ions. Finally, the selectivity sequence of G&ouml / rdes clinoptilolite in the presence of Pb2+ and NH4+ together was determined as Pb2+ &gt / NH4+ &gt / Na+. In the column studies, removal of lead, ammonium and simultaneous removal of lead-ammonium solutions were investigated. The loading flow rates were selected as 8, 15, and 30 mL/min. The ion exchange capacity of clinoptilolite for lead and ammonium removal showed good performance. Flow rates at 8, 15, 30 mL/min, breakthrough capacities were found as 0.398 meq/g (Pb2+) and 0.337 meq/g (NH4+), 0.299 meq/g (Pb2+) and 0.297 meq/g (NH4+), 0.197 meq/g (Pb2+) and 0.198 meq/g (NH4+) for lead-ammonium-sodium system and corresponding column efficiencies were 63.36%, 51.38%, 34.05%, respectively.

Considering measurable evidence and fuzzy measures that involve linguistic terms, this thesis proposes a fuzzy-number based Choquet integral to aggregate linguistic information when information fusion between criteria is considered. The proposed fuzzy-number based Choquet integral is a generalization of a standard Choquet integral that can cope with interval-number or fuzzy-number types of measurable evidence and fuzzy measures. Furthermore, by investigating the related characteristics of the Choquet integral and the fuzzy-number based Choquet integral, the operation process of the fuzzy-number based Choquet integral is clarified in this thesis. Combining linguistic terms and the compatibility of psychology, fuzzy numbers and the fuzzy-number based Choquet integral, when information fusion between criteria is considered, are introduced into evaluating service quality and aggregating information in three-column format of SERVQUAL. Finally, a numerical example, regarding the comparison of overall service performance between e-stores, is demonstrated to illustrate how the fuzzy-number based Choquet integral and its two-stage aggregation process operate in three-column format of SERVQUAL for evaluating service quality.

The goal of this thesis is to introduce new methods to create intricate perforated shapes in a computing environment. Modeling shapes with a large number of holes and handles, while requiring minimal human interaction, is an unsolved research problem in computer graphics. In this thesis, we have developed two methods for interactively modeling such shapes. Both methods developed create perforated shapes by building a framework of tube like elements, such that each edge of a given mesh is replaced by a pipe. The first method called Wire modeling replaces each edge with a pipe that has a square cross-section. The result looks like a shape that is created by a framework of matchsticks. The second method, called Column modeling allows more rounded cross-sections for the pipes. The cross-sections can be any uniform polygon, and the users are able to control the number of the segments in the cross-section. These methods are implemented as an extension to an existing modeling system guaranteeing that the pipes are connected and the resulting shape can be physically constructed. Our methods require an initial input mesh that can either be imported from a commercially available software package, or created directly in this modeling system. The system also allows the users to export the models in obj file format, so that the models can be animated and rendered in other software packages.

Dual head placement machines are commonly used in industry for placing components on circuit cards with great speed and accuracy. This thesis evaluates a novel approach for prescribing process plans for circuit card assembly on dual head placement machines. Process planning involves assigning component types to heads and to feeder slots associated with each head and prescribing appropriate sequences of picking, placing and nozzle-changing steps. The approach decomposes these decisions into four inter-related problems: P1, P2, P3 and P4. This thesis reviews this approach; presents a new heuristic to address P1; a method to facilitate P2 and P3 solutions; a method to control nozzle changes in P4; tests approaches to P1, P2, P3 and P4; and presents a thorough analysis of computational results to evaluate the efficacy of the approach which aims to balance workloads on machine heads to maximize assembly line throughput.

This dissertation discusses two independent topics: a resource-constrained shortest-path problem (RCSP) and a literature review on scheduling problems involving sequence-dependent setup (SDS) times (costs). RCSP is often used as a subproblem in column generation because it can be used to solve many practical problems. This dissertation studies RCSP with multiple resource constraints on an acyclic graph, because many applications involve this configuration, especially in column genetation formulations. In particular, this research focuses on a dynamic RCSP since, as a subproblem in column generation, objective function coefficients are updated using new values of dual variables at each iteration. This dissertation proposes a pseudo-polynomial solution method for solving the dynamic RCSP by exploiting the special structure of an acyclic graph with the goal of effectively reoptimizing RCSP in the context of column generation. This method uses a one-time “preliminary” phase to transform RCSP into an unconstrained shortest path problem (SPP) and then solves the resulting SPP after new values of dual variables are used to update objective function coefficients (i.e., reduced costs) at each iteration. Network reduction techniques are considered to remove some nodes and/or arcs permanently in the preliminary phase. Specified techniques are explored to reoptimize when only several coefficients change and for dealing with forbidden and prescribed arcs in the context of a column generation/branch-and-bound approach. As a benchmark method, a label-setting algorithm is also proposed. Computational tests are designed to show the effectiveness of the proposed algorithms and procedures. This dissertation also gives a literature review related to the class of scheduling problems that involve SDS times (costs), an important consideration in many practical applications. It focuses on papers published within the last decade, addressing a variety of machine configurations - single machine, parallel machine, flow shop, and job shop - reviewing both optimizing and heuristic solution methods in each category. Since lot-sizing is so intimately related to scheduling, this dissertation reviews work that integrates these issues in relationship to each configuration. This dissertation provides a perspective of this line of research, gives conclusions, and discusses fertile research opportunities posed by this class of scheduling problems. since, as a subproblem in column generation, objective function coefficients are updated using new values of dual variables at each iteration. This dissertation proposes a pseudo-polynomial solution method for solving the dynamic RCSP by exploiting the special structure of an acyclic graph with the goal of effectively reoptimizing RCSP in the context of column generation. This method uses a one-time

Carbon sequestration is a method of capturing and storing excess anthropogenic CO₂ in the subsurface. When CO₂ is injected, the temperature and pressure at depth turn it into a supercritical (SC) fluid, where density is that of a liquid, but viscosity and compressibility resemble a gas. Ultimately the SC CO₂ is trapped at depth either by low permeability sealing layers, by reactions with minerals, or by dissolving into fluids. The injected CO₂ is buoyant and initially exists as a non-aqueous hydrophobic layer floating on top of the subsurface brine, up against the upper sealing formation, but over time it will dissolve into the brine and potentially react with minerals. The details of that initial dissolution reaction, however, are only poorly understood, and I address three basic questions for this research: What is the fundamental kinetics of SC CO₂ dissolution into water? How fast does dissolved CO₂ diffuse away from the source point? And what geochemical conditions influence the dissolution rate? To answer these questions I employed a high pressure flow-through approach using a column packed with coarse quartz sand. The system was both pressure and temperature controlled to have either liquid or SC CO₂ present, and was typically run at 100 Bar, 0.5 to 2.5 mls/min, and 28-60°C. After establishing the hydraulic parameters for the column using two conservative tracers (Br, As), injections (5 and 20 [mu]l) were made either as aqueous solutions equilibrated to high pressure CO₂, or as pure liquid or SC CO₂ into 0.1 mmol NaOH. For all experiments the pH of the system was monitored, and [CO₂] over time was calculated from those data. For injections of brine with dissolved CO₂, transport was conservative and was nearly identical to the conservative tracers. The CO₂ quickly mixes in the column and does not react with the quartz. The liquid and SC CO₂ injections, however, do not act conservatively, and have a very long tailing breakthrough curve that extends to tens of pore volumes. I hypothesize that the SC CO₂ is becoming trapped as a droplet or many droplets in the pore spaces, and the long breakthrough tail is related either to the rate of dissolution into the aqueous phase, the diffusion of dissolved CO₂ away from the phase boundary, or the reaction with the NaOH, limited to the narrow contact zones in the pore throats. Because of the speed at which acid-base reactions occur (nanosecond kinetics), I infer that the rate limiting step is either surface dissolution or diffusion. From plots of ln[CO₂] v. time I obtained values for k, the specific rate of the dissolution reaction R=-k[CO₂]. No trend for k was seen with respect to changes in temperature, but k did show a trend with respect to changing flow rate. k increased from an average value of 3.05x10⁻³ at 0.5 ml/min to an average value of 3.38x10⁻³ at 1.6 ml/min, and then held constant at the higher flow rates, up to 2.5 ml/min. I interpret these data to show that at low flow rates, the reaction is diffusion limited; the fluid nearest the contact zone becomes saturated with dissolved CO₂. At higher flow rates, the fluid is moving fast enough that saturation cannot occur, and the kinetics of the dissolution reaction dominate. Simple geometric models indicate that the CO₂/water interface is shaped like a spherical cap, indicating that the snapped-off CO₂ is forming a meniscus in the pore throat, limiting the surface area across which dissolution can occur. / text

Πειραματική διεκπεραίωση 24 υποστυλωμάτων ορθογωνικής διατομής με μεγάλο λόγο πλευρών 3:1 και 4:1, κατασκευασμένα υπό κλίμακα, ενισχυμένα με ινοπλισμένα πολυμερή άνθρακα και εφαρμογή σχετικών προσομοιωμάτων υπάρχουσας βιβλιογραφίας. / Experimental procedure of 24 large-scale column specimens 3:1 and 4:1 reinforced with carbon fiber polymers CFRP and comparison of the test results with those calculated from the existing models of large-scale columns.

Η παρούσα διπλωματική εργασία έχει ως θέμα την μελέτη μιας κολόνας διύλισης και πιο συγκεκριμένα την εκτίμηση των συγκεντρώσεων του υγρού σε κάθε δίσκο της με χρήση του βέλτιστου γραμμικού φίλτρου Kalman, καθώς και τον έλεγχό της. / -

Gas phase chemiluminescence nitrogen specific detector (CLND)is used for the direct analysis of underivatized nitrogen-containing components such as alkylamines that can not be detected by the so called universal HPLC detector, the UV detector. However, alkali metal hydroxides can not be used as mobile phase constituents with the CLND because they form non volatile particulate combustion products that foul the detector. Therefore, trimethylsulfonium hydroxide (TMSOH) has been selected as a strong base for use with the CLND, because its combustion products, CO2, H2O and SxOy are volatile. An alkali-stable zirconia-based column was used and coupled to the CLND. Zirconia-based columns are mechanically and hydrolytically more stable than silica-based columns, which have a working pH range from 3 to 8 only. Zirconia-based columns can be used at a pH from 1 to 14 and can be used at temperatures up to 200˚C. The separation of amines was carried out at high pH values where the amino groups were deprotonated. Primary, secondary, tertiary and quaternary amines were separated using a pH=13.7 mobile phase that contained only TMSOH, methanol and water. Good peak shapes were observed for all, except n-alkylamines and samples that contained both amino groups and alcohol groups.

Using a specially constructed Gas Hydrate Resonant Column (GHRC), the University of Southampton explored different methods of hydrate synthesis and measured the properties of the resulting sediments, such as shear wave velocity (Vs), compressional wave velocity (Vp) and their respective attenuation measurements (Qs -1 and Qp -1). Two approaches were considered. The first utilises an excess gas technique, where known water volume in the pore space dictates the quantity of hydrate. The second approach uses a known quantity of methane gas within the water saturated pore space to constrain the volume of hydrate. Results from the two techniques show that hydrates formed in excess gas environments cause stiffening of the sediment structure at low concentrations (3%), whereas, even at high concentrations of hydrate (40%) in excess water environments, only moderate increase in stiffness was observed. Additionally, attenuation results show a peak in damping at approximately 5% hydrate in excess gas tests, whereas in excess water tests, damping continues to increase with increasing hydrate content in the pore space. By considering the results from the two approaches, it becomes apparent that formation method has an influence on the properties of the hydrate bearing sand, and must therefore influence the morphology of the hydrate in the pore space.