No description available.

The goal of my thesis is the design of a multipurpose sport hall in Litoměřice locality made in two separate variants. Objects ground plan dimensions are 38x38 meters and the height of the object is 16 meters. Used material is S235 steel and C20/25 concrete. The periphery and roof casing of the object is realized from sandwich panels. The carrying construction of the object is made from cross truss, oblong truss and from pillars. Thesis consists of assessing the carrying elements of the construction, selected details and drawing documentation.

A simple capillary flow porometer (CFP) was assembled for pore structure characterization of monolithic capillary liquid chromatography columns based on ASTM standard F316-86. Determination of differential pressures and flow rates through dry and wet samples provided the necessary information to determine the through-pore throat diameter, bubble point pore diameter, mean flow pore diameter, and pore distribution. Unlike measurements in bulk using traditional techniques to provide indirect information about the pore properties of monolithic columns, monoliths can be characterized in their original chromatographic forms with this system. The performance of the new CFP was first evaluated by characterizing the pore size distributions of capillary columns packed with 3, 5, and 7 µm spherical silica particles. The mean through-pore diameters of the three packed columns were measured to be 0.5, 1.0 and 1.4 µm, which are all smaller than the pore diameters calculated from a close-packed arrangement (i.e., 0.7, 1.1 and 1.6 µm), with distributions ranging from 0.1 - 0.7, 0.3 - 1.1 and 0.4 - 2.6 µm, respectively. This is reasonable, since visual inspection of SEM images of the particles showed relatively large fractions of smaller than specified particles in the samples. Typical silica monoliths were fabricated via phase separation by polymerization of tetramethoxysilane (TMOS) in the presence of poly(ethylene glycol) (PEG). The mean pore diameter and pore size distribution measured using the CFP system verified that a greater number of pores with small throat diameters were prepared in columns with higher PEG content in the prepolymer mixture. SEM images also showed that the pore diameters of monoliths fabricated in bulk were found to be smaller than those in monoliths synthesized by the same procedure, but confined in capillary tubes. The CFP system was also used to study the effects of column inner diameter and length on pore properties of polymeric monoliths. Typical monoliths based on butyl methacrylate (BMA) and poly(ethylene glycol) diacrylate (PEGDA) in capillary columns with different inner diameters (i.e., 50 to 250 µm) and lengths (i.e., 1.5 to 3.0 cm) were characterized. The mean pore diameters and the pore size distributions indicated that varying the inner diameter and/or the length of the column affected little the pore properties. The latter finding is especially important to substantiate the use of CFP for determination of monolithic pore structures in capillaries. The results indicate that the through-pores are highly interconnected and, therefore, pore structure determinations by CFP are independent of capillary length. A negatively charged polymer monolith based on BMA, ethylene glycol dimethacrylate (EDMA) and 2-acryloylamido-2-methylpropanesulfonic acid monomer (AMPS), was successfully prepared in silica sacrificial layer, planar (SLP) microchannels. Extraction of FITC (fluorescein 5-isothiocyanate) labeled phenylalanine and capillary electrochromatography (CEC) of FITC labeled glycine using this monolithic stationary phase were demonstrated.

We present a hybrid optimization algorithm for mixed-integer linear programming, embedding both heuristic and exact components. In order to validate it we use the periodic vehicle routing problem (PVRP) as a case study. This problem consists of determining a set of minimum cost routes for each day of a given planning horizon, with the constraints that each customer must be visited a required number of times (chosen among a set of valid day combinations), must receive every time the required quantity of product, and that the number of routes per day (each respecting the capacity of the vehicle) does not exceed the total number of available vehicles. This is a generalization of the well-known vehicle routing problem (VRP). Our algorithm is based on the linear programming (LP) relaxation of a set-covering-like integer linear programming formulation of the problem, with additional constraints. The LP-relaxation is solved by column generation, where columns are generated heuristically by an iterated local search algorithm. The whole solution method takes advantage of the LP-solution and applies techniques of fixing and releasing of the columns as a local search, making use of a tabu list to avoid cycling. We show the results of the proposed algorithm on benchmark instances from the literature and compare them to the state-of-the-art algorithms, showing the effectiveness of our approach in producing good quality solutions. In addition, we report the results on realistic instances of the PVRP introduced in Pacheco et al. (2011) [24] and on benchmark instances of the periodic traveling salesman problem (PTSP), showing the efficacy of the proposed algorithm on these as well. Finally, we report the new best known solutions found for all the tested problems. (authors' abstract)

Arsenic is a highly toxic, easily transportable and widespread contaminant in groundwater throughout the world. Arsenic causes acute toxicity by disrupting biological functions. In groundwater arsenic concentrations can reach up to a few milligrams per liter. Current regulations on arsenic content in drinking water are becoming more stringent and require the standard to be reduced to a few parts per billion. Arsenic exists as oxyanions in aqueous solution in either trivalent or pentavalent oxidation states depending on the oxidation-reduction potential and pH of the medium. Several treatment methods are available for removing arsenic from water. However, cost, operational complexity of the technology, skill required to operate the technology and disposal of arsenic bearing residual are factors that should be considered before the selection of any treatment method. Most of these techniques are also effective only in removing As(V) and not As(III). N,N’-bis(2-mercaptoethyl)isophthalamide), abbreviated BDTH2, is known to effectively precipitate soft heavy metals from water. A solid-supported reagent with the metal capture ability of BDTH2 would be ideal to use as a filtration column packing material for removal of aqueous As(III). In order to attain this objective, a new dithiol compound, 2,2'-(isophthaloylbis(azanediyl))bis(3-mercaptopropanoic acid) (abbreviated ABDTH2) has been synthesized and immobilized on silica beads. Silica-supported reagent ABDTH2 (SiABDTH2) thus prepared, completely removed As(III) from water by forming As-S bonds. In batch study, SiABDTH2 reduced the concentration of As(III) in aqueous solutions from 200 ppb to below 5 ppb at pH 5, 7 and 9. XAFS study of ABDT-As(III) and SiABDT-As(III) indicated that arsenic was present in +3 oxidation state as well as As(III) was only bonded to sulfur atom of ABDT unit. When SiABDTH2 was used as filtration column material, only 3% of ABDTH2 was leached out from the column. However, 100% As(III) was removed from 20 L of 200 ppb As(III) aqueous solution at a flow rate of 20 mL/min.

This study was motivated by the fact that many times intact specimens with a number of oversized particles are dynamically tested in the laboratory and the impact of the particles on the dynamic properties is unknown. The effects of oversized particles represented by gravel particles on the shear modulus (G) and material damping ratio (D) of a uniform sand were evaluated in the linear (γ ≤ 0.001%) and nonlinear (γ > 0.001%) ranges of shear strain with combined resonant column and torsional shear (RCTS) equipment. The sand used in this investigation is a uniform sand as a reference, well-characterized material on the dynamic properties. Sand-gravel specimens were constructed using the undercompaction method. A variety of rounded gravel particles was used in building the specimens. Dynamic tests on the sand-gravel specimens were performed, and the tests results are presented. Among the findings of this investigation are that, compared to uniform sand: (1) oversized gravel particles symmetrically located along the longitudinal axis in uniform sand generally decreased slightly the small-strain shear modulus (Gmax), (2) oversized gravel particles asymmetrically located away from the longitudinal axis of rotation resulted in slight increases in Gmax and the small-strain material damping ratio (Dmin), (3) the G – log γ relationships of sand-gravel specimens with asymmetrically located gravel particles are generally above those with gravel particles symmetrically located along the longitudinal axis, and (4) the G/Gmax – log γ relationships of all specimens were reasonably close for the nonlinear ranges covered in these tests (γ < 0.05 % and G/Gmax > 0.6). As long as the oversized particles were near the axis of rotation, the particles had little effect on the dynamic properties (Gmax, Dmin and G – log γ relationships) regardless of sizes and numbers of particles. However, once the oversized particles were located away from the axis of rotation and closer to the perimeter of the specimen, the oversized particles influenced the dynamic properties. Finally, the additions of oversized particles located both symmetrically and asymmetrically in the uniform sand specimens have little impact on the nonlinear dynamic properties (G/Gmax – log γ and D – log γ relationships) which compared well with uniform sand. / text

No description available.

Ingeniero Civil / Este trabajo de título estudia de forma numérica el comportamiento de viga y columna de una conexión para marcos a momento en acero. El tipo de conexión utilizada para materializar dicha unión es la llamada \textit{Conexión Árbol} o en inglés \textit{Column-Tree}, que a pesar de no estar precalificada en la normativa vigente es de amplia utilización en el país, como por ejemplo en Metro de Santiago o el Aeropuerto Arturo Merino Benitez. La conexión \textit{Column-tree} consiste en un segmento de viga ( Stub Beam ) soldado en maestranza a la cara de la columna, a la cual se conecta el resto de la viga mediante placas de empalme en las alas y alma, las cuales pueden estar soldadas o apernadas, lo que genera ventajas constructivas respecto a otros tipos de conexión. El estudio numérico consiste en la aplicación de desplazamientos controlados, mediante un protocolo de carga a un sub-ensamblaje del marco a momento. Para ello se definió una estructura tipo, modelada en el software de diseño sísmico ETABS, obteniendo dimensiones de los perfiles viga y columna luego de la completa verificación según la norma de diseño sísmico NCh 433. Simultáneamente, se elaboró una guía de diseño para la conexión, cumpliendo con todas las especificaciones de las normas vigentes (AISC 2016) verificando los modos de falla pertinentes y utilizando una filosofía de diseño por capacidad mediante la cual se establece la formación de rótula plástica en la viga Stub Beam , con el objetivo de evitar fallas frágiles. Posteriormente se modela el sub-ensamblaje del marco a momento en el software de elementos finitos ANSYS, donde finalmente se realiza el estudio numérico. Finalizado el análisis se obtiene una curva histerética momento-rotación que tiene un cambio de pendiente al inicio del protocolo de carga, lo que refleja una disminución en la rigidez de la conexión pero no así de su resistencia, lo cual es producto de deformaciones plásticas tempranas en la zona de la viga que está en contacto con el borde de los extremos de empalmes de ala. Este efecto se debe a la restricción geométrica que imponen los empalmes al ser de un espesor y largo considerables. La conexión es analizada hasta 0.04 [rad] de rotación, donde se alcanzan las principales deformaciones plásticas en las alas de la viga \textit{Stub-Beam}. Los resultados permiten concluir que para la estructura diseñada se obtienen perfiles y empalmes de grandes dimensiones los que restringen en exceso a la viga, fenómeno que no se pudo prever en el cálculo, lo cual lleva a dejar propuesto el análisis del comportamiento de la conexión en diversas estructuras.

The first chapter of this thesis presents an introduction to sol-gel methodology whose usefulness as a synthetic route will be demonstrated with two applications in chromatography. The first application involves the fabrication of a capillary micro-extraction (CME) device by coating a phenyl functionalized extracting phase on the inner surface of a fused silica capillary for analyte pre-concentration. The device was coupled on-line to a RP-HPLC system and practicality was demonstrated using allergens as target analytes. The allergens chosen as model analytes are typically found in fragrance products and food. Most of the 26 fragrance allergens that are monitored by various government authorities have a phenyl organic moiety (a strong chromophore), thus making them appropriate probes for exploring the extraction efficiency of the coating using a UV detector. The CME device showed ppt level limit of detection which makes it suitable for trace analyses of allergens and similar compounds in a variety of matrices. The second application explores the feasibility of using sol-gel derived chromia-based stationary phase in gas chromatographic columns. The organic moiety of the stationary phase was derived from Ucon 75-H-90,000 while the inorganic backbone was prepared using chromium(III) dichloride hydroxide - methacrylic acid - aqua complex, 40% in isopropanol/acetone . Usefulness of prepared chromia-based GC stationary phase was examined for petrochemical application. Promising results were obtained using aliphatic-aromatics, polyaromatic hydrocarbons, BTEX test mixture, cycloalkanes, branched alkanes and akylbenzenes. The column was able to perform without degradation despite being rinsed multiples times sequentially with the following solvents: dichloromethane, methanol, water and finally methanol again. Maximum theoretical plate number calculated is around 2,400 plates/m. The plate number clearly needs improvement but is a promising result for the newly explored chromia-based stationary phase. The maximum programmable temperature is 250oC which is comparable with similar commercially available polar stationary phases.

Contamination of soils by munitions constituents is pervasive on Department of Defense operational ranges. Low-order detonations result in the heterogeneous distribution of explosives residues (ER) at shallow depths. At a limited number of ranges ER contamination of groundwater has been observed. Previous studies have shown that the downward migration of colloid-sized contaminants can significantly impact groundwater quality. The goal of this study was to investigate if colloid transport plays a role in the migration of ER contaminants. Our primary objective was to determine the transport potential of fine (<5>um) ER particles under ideal conditions for colloid transport. A secondary objective was to develop a direct detection method for the identification and quantitative analysis of particulate ER. A series of saturated transport experiments were conducted in columns (2x20 cm) packed with clean sand. 2,6- Dinitrotoluene was used as a surrogate for explosives chemicals. Experiments were conducted with both particulate and dissolved-phase DNT. Bromide and microspheres tracers were also used to characterize nonreactive transport. Particulate tracers were applied to the columns, either suspended in the influent solution, or directly to the top layer of sand, in order to more realistically replicate field conditions. Experimental results indicate that DNT movement through the columns occurred as a combination of solid and dissolved phase transport. Concentration differences between unfiltered and filtered samples indicate that particulate DNT accounted up to 30% of the total mass recovered in the effluent.