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1
Escudero, Ramiro Garcia. « Characterization of rigid spargers and their selection for flotation columns ». Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0001/NQ44423.pdf.
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Escudero, Garcia Ramiro. « Characterization of rigid spargers and their selection for flotation columns ». Thesis, McGill University, 1998. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=34953.
Texte intégralRésumé :
Rigid spargers are enjoying renewed interest in some flotation column applications such as de-inking of recycled paper and de-oiling of water. Sparger selection depends on the physical characteristics of the porous material, the liquid/slurry properties, and the dimensions of the column. There is no generally accepted method to select spargers for a given flotation column duty. A methodology for selecting stainless steel rigid spargers is proposed. The methodology is based on a target bubble size (db), gas holdup (epsilong), or bubble surface flux ( Sb). It combines two models: one for bubble formation at the sparger proposed by Kumar and Kuloor which relates bubble size to sparger characteristics, and drift flux analysis which relates mean bubble size, gas holdup, and gas rate.Prediction of bubble size by the Kumar and Kuloor model requires a knowledge of an equivalent pore diameter (De) of the sparger. A procedure to estimate De by fitting the predicted and measured epsilong - Jg relationships is developed.
Comparison of bubble size measured photographically with that estimated from drift flux analysis, and predicted by the Kumar and Kuloor model shows acceptable agreement between the measured, estimated and predicted values.
By combining db predicted with drift flux analysis, and allowing for column dimensions, both the gas holdup and the bubble surface flux were predicted. A maximum in sparger surface area was found above which the gas holdup and the bubble surface flux do not increase.
Spargers were characterized according to their permeability (k ), by applying the Darcy law. Sparger homogeneity was established from this permeability measurement. A relationship between De and k was derived. For spargers with permeability up to 0.75 darcy (0.75 x 10-5 m2), the equivalent pore diameter was constant (De = 2 mum). For larger permeabilities De increased with permeability.
Application of the sparger selection criteria in a pilot unit (0.5 m diameter column) showed epsilong and Sb can be predicted with acceptable accuracy.
3
Fang, Yan. « Pore Size Characterization of Monolithic Capillary Columns Using Capillary Flow Porometry ». BYU ScholarsArchive, 2009. https://scholarsarchive.byu.edu/etd/2234.
Texte intégralRésumé :
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.
4
Bergman, Niclas. « Characterization of strenght vaiability for reliability-based design of lime-cement columns ». Licentiate thesis, KTH, Jord- och bergmekanik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-98816.
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Adem, Seid Muhie. « DEVELOPMENT AND CHARACTERIZATION OF STABILIZED PHOSPHOLIPID COATINGS FOR OPEN TUBULAR AND PACKED CAPILLARY SEPARATIONS ». Diss., The University of Arizona, 2010. http://hdl.handle.net/10150/204067.
Texte intégralRésumé :
Phosphorylcholine (PC) based phospholipid bilayers have been explored as coating materials for various substrates due to their inherent resistance to non-specific protein adsorption. Phospholipids have been used for coatings in capillary electrophoresis (CE) to suppress electroosmotic flow (EOF) and to obtain better separation of proteins. Here, a series of investigations geared towards developing highly stable phospholipid based biomimetic stationary phases for chromatographic separations was performed.Fluid phospholipid bilayers lack the desired chemical and physical stability to serve as long-term coatings. In this work, highly stable phospholipid coatings generated via crosslinking polymerization of bis-SorbPC monomers were investigated. Reproducible EOF and migration times for model proteins were obtained for coated capillaries that were kept at room temperature for up to two months. Furthermore, the effects of surfactants, pH and capillary inner diameter (i.d.) on the stability of the lipid coating were investigated.In an alternate approach, stabilized phospholipid coatings for capillary electrophoresis were investigated via formation of hybrid monolayers. The capillary surface was chemically modified with a cyano group followed by deposition of phospholipid monomers. In this approach, marked enhancements in coating stability were attained with commercially available reagents. The hybrid coating was utilized for protein separations and gave efficiencies comparable to non-stabilized lipid coated capillaries.Fused silica capillaries were modified with phospholipid bilayers that were chemically tuned to introduce specific affinity binding agents, while minimizing nonspecific protein adsorption to the capillary wall. The wall of fused silica was functionalized with DOGS-NTA-Ni2+ lipid to present binding sites inside the capillary for 6xHis-tagged proteins. Fluorescence microscopy and changes in electrophoretic mobility were used to follow the interaction of the model proteins with the functionalized silica surface.The structural similarity of lipid vesicles to cell membranes made them attractive in developing stationary phases for both liquid chromatography and capillary electrophoresis to study interactions between analytes and phospholipid membranes. Stabilized PLB coated silica microspheres were prepared via polymerization of lipid monomers and displayed enhanced stability to extended storage and organic solvent. These highly stable microspheres, while minimizing nonspecific protein adsorption, were also functionalized with DOGS-NTA-Ni2+ and effectively bind 6xHis-EGFP proteins.
6
Denchitcharoen, Somyod. « Nanofabrication and characterization of high density nanostructures and QDs using ni annealing and anodic porous alumina methods ». Thesis, University of Bath, 2009. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.516956.
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Hara, Takeshi [Verfasser]. « Study on preparation and characterization of monolithic silica capillary columns for high separation efficiency in high performance liquid chromatography / Takeshi Hara ». Gießen : Universitätsbibliothek, 2013. http://d-nb.info/1064991351/34.
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Beach, Robert A. McGill T. C. « Column III nitride growth, characterization and devices / ». Diss., Pasadena, Calif. : California Institute of Technology, 2001. http://resolver.caltech.edu/CaltechETD:etd-11212003-141821.
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Liu, Guangdong. « Urban Watershed Characterization : Dry Run Columbus, Ohio ». The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1345129567.
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Davis, Van Leslie. « Characterization and scale-up of microbubble generation in column flotation ». Thesis, This resource online, 1990. http://scholar.lib.vt.edu/theses/available/etd-03242009-040658/.
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Zope, Anjali U. (Anjali Umesh). « Synthesis and Characterization of Methylated PCU Dimers ». Thesis, University of North Texas, 1993. https://digital.library.unt.edu/ark:/67531/metadc500801/.
Texte intégralRésumé :
Conversion of 1-Methylpentacyclo[5.4.0.0²⋅⁶.0³⋅¹⁰.0⁵⋅⁹]undecane- 8,11-dione into the corresponding mono(ethylene ketal) followed by Wolff-Kishner reduction resulted in a mixture of two isomers (i.e., 1- and 7-methyl-8-[2',-(1',3',dioxolano)]pentacyclo[5.4.0.0²⋅⁶.0³⋅¹⁰.0⁵⋅⁹] undecane. Hydrolysis of each isomer in turn resulted in 1- and 7- methyl pentacyclo[5.4.0.0²⋅⁶.0³⋅¹⁰.0⁵⋅⁹ ]undecan-8-ones (i.e.,"methylated PCU-8-ones"), respectively. "Titanium-promoted reductive dimerization of each of the methylated pentacycloundecane (PCU)-8-ones afforded mixtures of "methylated PCU alkene dimers". Individual isomers have been isolated from these mixtures via column chromatography by using silver nitrate impregnated silica gel as adsorbent followed by fractional recrystallizations of individual chromatography fractions. Structures of three isomerically pure methylated PCU alkene dimers (C₂₄H₂₈) have been established unequivocally by application of single crystal X-ray crystallographic methods.
12
Onesti, Riccardo. « Characterization of a ceramic monolithic support for affinity protein chromatogrophy ». Master's thesis, Alma Mater Studiorum - Università di Bologna, 2017.
Trouver le texte intégralRésumé :
Affinity chromatography is a process for the separation of biomolecules from complex mixtures. Its versatility, high selectivity and efficiency make it the most currently used method in the final stages of purification of pharmaceutical and food industries, where a high degree of purity is required.
Conventional affinity chromatography uses packed beads as solid support and suffers of several limitations, such as high material costs, high operating costs, intraparticle diffusion as primary transport phenomenon and difficulties in column packing.
Therefore, it is necessary to develop and characterize cheaper and more efficient materials as stationary phase for chromatographic separations. From this perspective, monolithic media have shown a significant potential.
In this research project a new ceramic composite monolithic support, a cellular Al2TiO5 and Al2TiO5-Al2O3 composite monolith, has been experimentally characterized.
First, several monolithic columns have been prepared, by polishing the material to obtain cylindrical samples of the desired height and dimensions. Then the columns have been characterized by calculating the main fluid dynamic parameters that govern the motion of a fluid in a porous material: permeability, porosity and axial dispersion coefficient. To this aim permeability tests and pulse tests have been performed.
One column has been functionalized with epoxy groups, by linking 3-glycidoxypropyltrimethoxysilane (GPTMS). This step, called activation, creates active sites for the immobilization on the support of protein A, that on turn is used for the affinity adsorption of immunoglobulin-G.
The number of active epoxy groups has been estimated by measuring the ability of the column to irreversibly bind the bovine serum albumin, BSA, in chromatographic experiments.
13
Menon, Surabo, Jean-Louis Brenguier, Olivier Boucher, Paul Davison, Genio Anthony D. Del, Johann Feichter, Steven Ghan et al. « Evaluating aerosol/cloud/radiation process parameterizations with single-column models and Second Aerosol Characterization Experiment (ACE-2) cloudy column observations : Evaluating aerosol/cloud/radiation process parameterizations withsingle-column models and Second Aerosol Characterization Experiment (ACE-2) cloudy column observations ». Wiley, 2003. https://ul.qucosa.de/id/qucosa%3A13455.
Texte intégralRésumé :
The Second Aerosol Characterization Experiment (ACE-2) data set along with ECMWF reanalysis meteorological fields provided the basis for the single column model (SCM) simulations, performed as part of the PACE (Parameterization of the Aerosol Indirect Climatic Effect) project. Six different SCMs were used to simulate ACE-2 case
studies of clean and polluted cloudy boundary layers, with the objective being to identify limitations of the aerosol/cloud/radiation interaction schemes within the range of uncertainty in in situ, reanalysis and satellite retrieved data. The exercise proceeds in three
steps. First, SCMs are configured with the same fine vertical resolution as the ACE-2 in situ data base to evaluate the numerical schemes for prediction of aerosol activation, radiative transfer and precipitation formation. Second, the same test is performed at the coarser vertical resolution of GCMs to evaluate its impact on the performance of the
parameterizations. Finally, SCMs are run for a 24–48 hr period to examine predictions of boundary layer clouds when initialized with large-scale meteorological fields. Several schemes were tested for the prediction of cloud droplet number concentration (N). Physically based activation schemes using vertical velocity show noticeable discrepancies compared to empirical schemes due to biases in the diagnosed cloud base vertical velocity. Prognostic schemes exhibit a larger variability than the diagnostic ones, due to a coupling between aerosol activation and drizzle scavenging in the calculation of N. When
SCMs are initialized at a fine vertical resolution with locally observed vertical profiles of liquid water, predicted optical properties are comparable to observations. Predictions however degrade at coarser vertical resolution and are more sensitive to the mean liquid
water path than to its spatial heterogeneity. Predicted precipitation fluxes are severely underestimated and improve when accounting for sub-grid liquid water variability. Results from the 24–48 hr runs suggest that most models have problems in simulating boundary
layer cloud morphology, since the large-scale initialization fields do not accurately reproduce observed meteorological conditions. As a result, models significantly overestimate optical properties. Improved cloud morphologies were obtained for models with subgrid inversions and subgrid cloud thickness schemes. This may be a result of
representing subgrid scale effects though we do not rule out the possibility that better large-forcing data may also improve cloud morphology predictions.
14
Zeng, Erman. « Design, synthesis and characterization of columnar discotic and bowlic liquid crystals ». Diss., Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/12268.
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Polit, Colleen. « Characterization and redesign of the University of Florida Training Reactor (UFTR) thermal column ». [Gainesville, Fla.] : University of Florida, 2009. http://purl.fcla.edu/fcla/etd/UFE0024633.
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Kenny, Sean. « Mechanical Characterization of Patterned Silver Columnar Nanorods with the Atomic Force Microscope ». VCU Scholars Compass, 2012. http://scholarscompass.vcu.edu/etd/2705.
Texte intégralRésumé :
Patterned silver (Ag) columnar nanorods were prepared by the glancing angle physical vapor deposition method. The Ag columnar nanorods were grown on a Si (100) substrate patterned with posts in a square “lattice” of length 1 μm. An electron beam source was used as the evaporation method, creating the deposition flux which was oriented 85˚ from the substrate normal. A Dimension Icon with NanoScope V controller atomic force microscope was used to measure the spring constant in 10 nm increments along the long axis of five 670 nm long Ag nanorod specimens. The simple beam bending model was used to analyze the data. Unexpected behavior of the spring constant data was observed which prevented a conclusive physically realistic value of the Young’s modulus to be calculated.
17
Menon, Surabo, Jean-Louis Brenguier, Olivier Boucher, Paul Davison, Genio Anthony D. Del, Johann Feichter, Steven Ghan et al. « Evaluating aerosol/cloud/radiation process parameterizations with single-column models and Second Aerosol Characterization Experiment (ACE-2) cloudy column observations ». Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-177303.
Texte intégralRésumé :
The Second Aerosol Characterization Experiment (ACE-2) data set along with ECMWF reanalysis meteorological fields provided the basis for the single column model (SCM) simulations, performed as part of the PACE (Parameterization of the Aerosol Indirect Climatic Effect) project. Six different SCMs were used to simulate ACE-2 case
studies of clean and polluted cloudy boundary layers, with the objective being to identify limitations of the aerosol/cloud/radiation interaction schemes within the range of uncertainty in in situ, reanalysis and satellite retrieved data. The exercise proceeds in three
steps. First, SCMs are configured with the same fine vertical resolution as the ACE-2 in situ data base to evaluate the numerical schemes for prediction of aerosol activation, radiative transfer and precipitation formation. Second, the same test is performed at the coarser vertical resolution of GCMs to evaluate its impact on the performance of the
parameterizations. Finally, SCMs are run for a 24–48 hr period to examine predictions of boundary layer clouds when initialized with large-scale meteorological fields. Several schemes were tested for the prediction of cloud droplet number concentration (N). Physically based activation schemes using vertical velocity show noticeable discrepancies compared to empirical schemes due to biases in the diagnosed cloud base vertical velocity. Prognostic schemes exhibit a larger variability than the diagnostic ones, due to a coupling between aerosol activation and drizzle scavenging in the calculation of N. When
SCMs are initialized at a fine vertical resolution with locally observed vertical profiles of liquid water, predicted optical properties are comparable to observations. Predictions however degrade at coarser vertical resolution and are more sensitive to the mean liquid
water path than to its spatial heterogeneity. Predicted precipitation fluxes are severely underestimated and improve when accounting for sub-grid liquid water variability. Results from the 24–48 hr runs suggest that most models have problems in simulating boundary
layer cloud morphology, since the large-scale initialization fields do not accurately reproduce observed meteorological conditions. As a result, models significantly overestimate optical properties. Improved cloud morphologies were obtained for models with subgrid inversions and subgrid cloud thickness schemes. This may be a result of
representing subgrid scale effects though we do not rule out the possibility that better large-forcing data may also improve cloud morphology predictions.
18
Anderson, JoAnna Todd. « Characterization of a sacral dorsal column pathway activating autonomic and hindlimb motor pattern generation ». Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/42849.
Texte intégralRésumé :
Spinal cord injuries (SCI) sever communication between supraspinal centers and the central pattern generator (CPG) responsible for locomotion. Because the CPG is intact and retains the ability to initiate locomotor activity, it can be accessed electrically and pharmacologically. The goal of this thesis was to identify and characterize a novel spinal cord surface site along the sacral dorsal column (sDC) for electrically evoking locomotor-like activity in the neonatal rat spinal cord. Stimulation of the sDC robustly activated rhythmic left-right alternation in flexor-related ventral roots that was dependent on the activation of high-threshold C fiber afferents. The C fibers synapsed onto spinal neurons, which project to the lumbar segments as part of a pathway dependent on purinergic, adrenergic, and cholinergic receptor activation. In ventral roots containing only somatic efferents, rhythmic activity was rarely recruited. However, in ventral roots containing both autonomic and somatic efferents, sacral dorsal column stimulation recruited autonomic efferent rhythms, which subsequently recruited somatic efferent motor rhythms. The efferent rhythms revealed a half-center organization with very low stimulation frequencies, and the evoked alternating bursts entrained to the stimuli. Similar entrainment was seen when sDC stimuli were applied during ongoing neurochemically-induced locomotor rhythms. The rhythmic patterns evoked by sDC stimulation operated over a limited frequency range, with a discrete burst structure of fast-onset, frequency-independent peaks. In comparison, neurochemically-induced locomotor bursts operated over a wide frequency range and had slower time to peaks that varied with burst frequency. The overall findings support the discovery of an autonomic efferent pattern generator that is recruited by sacral visceral C fiber afferents. It is hoped that this research will advance the understanding of afferent activation of the lumbar central pattern generator and potentially provide insight useful for future development and design of neuroprosthetic devices.
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Mirzaei, Sedigheh. « Characterization of columnar liquid crystals and plasmonic effects for organic solar cells application ». Toulouse 3, 2012. http://thesesups.ups-tlse.fr/1670/.
Texte intégralRésumé :
Le thème général de cette thèse est le photovoltaïque organique. Elle se compose de deux parties. La mobilité électrique est d'abord mesurée dans un nouveau composé qui montre une phase cristal liquide (CL) colonnaire à température ambiante. Ce CL, dont le nom abrégé est Pe4C8EH, est constitué de molécules discotiques avec des chaînes flexibles connectées aux cœurs aromatiques. On a montré que Pe4C8EH avait une propriété de semiconducteur directionnelle. Les valeurs de mobilité mesurées sont 2,8 10-4 cm2/V. S et 8,5 10-5 cm2/V. S dans les directions parallèle et perpendiculaire aux colonnes, respectivement. Cette propriété est intéressante pour des applications aux cellules solaires et aux transistors. L'accroissement de la mobilité est attribué au recouvrement des orbitales p le long des colonnes. Dans la deuxième partie, l'effet de nanoparticules sphériques d'or (AuNPs) sur le rendement de cellules solaires P3HT: PCBM a été étudié par l'adsorption de AuNPs de diamètre 30nm sur la surface de l'électrode en oxyde d'indium et d'étain (ITO). Les nanoparticules métalliques peuvent améliorer le rendement d'absorption d'une cellule à la fois par la diffusion et l'absorption de la lumière incidente à une fréquence particulière appelée résonance plasmonique de surface (SPR). La SPR dépend du métal, de la taille et de la forme des nanoparticules. Notre recherche a montré que l'effet positif des AuNPs sur le rendement de la cellule solaire dépendait de leur concentration en surface. Une haute concentration d'AuNPs (215/µm2) annihile pratiquement le photocourant généré par la cellule, tandis qu'une faible concentration (8/µm2) a un effet positif sur le rendement de la celluleThe general theme of this thesis is organic photovoltaics. In more details it consists of two parts: Measuring the electrical mobility in a new compound showing liquid crystalline (LC) phase at room temperature. This LC whose abbreviated name is Pe4C8EH, is made up of disc-like molecules with flexible chains connected to the disc core. When disc-like cores pile-up upon each other, they form columns. We showed that along these columns the mobility of charge is enhanced, meaning that Pe4C8EH shows directional semiconducting properties. Measured values of mobility are 2. 8 10-4 cm2/V. S and 8. 5 10-5 cm2/V. S in the direction parallel and perpendicular to the columns, respectively. This property is interesting for solar cell and transistor applications. Mobility enhancement is attributed to the p-orbital overlapping along the columns. In the second part, the effect of 30nm spherical gold nanoparticles (AuNPs) on the efficiency of P3HT:PCBM solar cells was studied by adsorbing them on the surface of Indium Tin Oxide (ITO) electrode. Metallic nanoparticles can enhance the absorption efficiency of a cell by both scattering and absorption of the incident light at a special frequency, which is called Surface Plasmon Resonance (SPR). SPR depends on the metal, size and shape of nanoparticles. Our investigation showed that the positive effect of AuNPs on the efficiency of solar cells depends on their surface concentration. High concentration (215/µm2) of AuNPs almost suppresses the photocurrent generated by the solar cell while low concentration (8/µm2) has a positive effect on the efficiency of the cell
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Cripe, M. Kathleen Leslie. « Syntheses and characterization of a t-OCTYLCALIX[5]ARENE derivatized capillary column for gas chromatography ». Connect to online version at OhioLINK ETD Connect to online version at Digital.Maag, 1998. http://hdl.handle.net/1989/3749.
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Shah, Piyush J. « Nanostructured Columnar Thin Films Using Oblique Angle Deposition : Growth, SERS Characterization and Lithographic Processing ». Wright State University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=wright1341852929.
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Bajwa, Tariq Mahmood. « Experimental Characterization of the Thermal, Hydraulic and Mechanical (THM) Properties of Compost Based Landfill Covers ». Thèse, Université d'Ottawa / University of Ottawa, 2012. http://hdl.handle.net/10393/20518.
Texte intégralRésumé :
Landfills are considered to be one of the major sources of anthropogenic methane (CH4) emissions in the environment. A landfill biocover system optimizes environmental conditions for biotic CH4 consumption that controls the fugitive and residual emissions from landfills. A compost material has more oxidation potential in comparison to any other material due to its high porosity, organic content, free flux for gases and water holding capacity. Thermal, hydraulic, bio – chemical and mechanical (THMCB) properties are important factors that can significantly affect the performance of biocover material with regards to CH4 oxidation potential as well as structural stability. Technical data on the thermal, hydraulic and mechanical (THM) properties of compost based biocover materials are quite limited. Hence, a detailed experimental program has been carried out at the University of Ottawa to study the THM properties and behaviour of compost biocover material by conducting experimental tests on small compost samples as well as by performing column experiments.
The test results indicate that lower water content (dry of optimum for compaction curve) shows more free air space (FAS) in comparison to higher water content. The compost has almost the same shear strength for various initial water contents and dry unit weights; however, it settles and swells more at higher water content than lower water content per mechanical test results. The thermal and hydraulic properties of compost are a function of the compaction degree in addition to various other parameters. It is also found that the THM properties of compost are strongly coupled and the degree of saturation greatly affects the FAS.
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Samuelsson, Jörgen. « Development of Methods for Phase System Characterization in Liquid Chromatography ». Doctoral thesis, Uppsala universitet, Ytbioteknik, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-8597.
Texte intégralRésumé :
The aim of this thesis is first and foremost to improve the fundamental knowledge of nonlinear and preparative separation theory by focusing on some of the remaining “white spots” on the theoretical chromatographic map. Secondly, the acquired knowledge is used to develop, validate and execute new methods for phase characterization in liquid chromatography. The methodology used in this thesis is a combination of experiments, fundamental nonlinear theory and systematic computer simulations. A fundamental knowledge of the molecular interactions between the compounds to be separated and the separation media requires the determination of adsorption isotherms over a broad concentration range to give a complete picture of all interactions in the separation system - weak as well as strong. In addition, such adsorption data is essential for optimization in preparative chromatography. For the first time, it has been experimentally shown that the injected molecules are not present in the detected peak when a small excess of molecules are injected into a chromatographic system equilibrated with a constant stream of identical molecules. Several experimental procedures for this method were developed such as (i) the optimal injection strategy and (ii) different labeling methods for visualizing the injected molecules. Remarkable phenomena in the single-component case, such as invisible peak deformation and deformed (invisible) frontal chromatograms, are reported, investigated, and explained. This phenomenon has asides from its future practical implementation, also a large didactic value. The accuracy of the ECP method is experimentally improved, and used to characterize the separation of protolytic compounds at different pH on modern commercially available silica and hybrid silica column packing materials. That investigation enables us to answer why basic compounds give a much more compact preparative peak profile at pH 11 than they yields at lower pH.
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Tarkin, Eylem. « Characterization And Study Of Solution Properties Of Poly(propylene Oxide) Synthesized By Metal Xanthate Catalysts ». Master's thesis, METU, 2003. http://etd.lib.metu.edu.tr/upload/1086099/index.pdf.
Texte intégralRésumé :
Zinc xanthates polymerize propylene oxide into high polymer (PPO) with coordination mechanism. In order to identify structure and stereoisomerisms of this polymer, PPO was subjected to thermal and column fractionation. Obtained fractions were characterized by end-group analysis, cryoscopy, viscometry, IR and 13C-NMR spectroscopy, melting temperature. PPO is composed of a high molecular weight, stereoregular, crystallizable polymer (K-polymer) with low molecular weight (=500 g/mol) D-polymer. Presence of double bonds and hydroxyl terminals was interpreted as the product of an anionic mechanism.
K-Polymers can be thermally fractionated on the basis of their melting temperature (Tm) rather than molecular weight (Mwt). It’
s found that higher Tm fractions have lower Mwt, but they precipitate at higher temperatures than higher Mwt but lower Tm fractions. In column fractionation, K-polymers were deposited on glass beads from isooctane solution in a narrow temperature interval. Then the precipitated samples were split into a number of fractions by using again isooctane but at a higher temperature than the precipitation temperature by increasing residence time from 5 minutes to several hours. It&
#8217
s found that rate of solubility is not controlled by molecular weight, but controlled by percentage crystallinity and Tm. Highest Tm polymers, with relatively higher Mwt showed faster rate of solution than that of lower Tm, lower Mwt but higher percent crystalline fractions. This discrepancy was accounted by suggesting a stereo-block structure where tactic blocks are bound each other with non-crystallizable atactic blocks. The mechanism of polymerization was also discussed in some detail.
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Booso, Benjamin David. « The Growth of Columnar Thin Films and Their Characterization Within the Visible and Near Infrared Spectral Bands ». University of Dayton / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1272587327.
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Wishrojwar, Anitha Suhas. « SYNTHESIS, CHARACTERIZATION AND DEVELOPMENT OF CATALYSTS FOR CO2 CAPTURE ». UKnowledge, 2010. http://uknowledge.uky.edu/gradschool_theses/42.
Texte intégralRésumé :
Fossil fuel and advanced industrialization techniques contribute to global warming through emissions of greenhouse gases such as CO2. In order to mitigate climate change, there is a desperate need to reduce CO2 emissions from different sources. CO2 capture and sequestration (CCS) play an important role in these reductions.
Naturally occurring enzymes, e.g., carbonic anhydrase (CA), can catalyze these reactions in living systems. Much effort has been focused on complexes of zinc with ligands such as teta, cyclen and tripodal ligands including BIMA and Trispyrazolylborates. These complexes have many interesting CO2 capture properties, but maintain toxic perchlorate ions.
We desired to replace them with less hazardous counteranions like BF4- or PF6-. Our research focused mainly on the synthesis and characterization of Zn, Co and Cu cyclen and teta complexes that could mimic CA. We also examined some of these species for catalytic CO2 hydration behavior on wetted-wall column (WWC) at Center for Applied Energy Research (CAER).
We successfully synthesized and characterized eight new complexes. These catalysts as CO2 capture systems are more stable have low molecular weights (compared to CA) and more cost effective than enzymes. In terms of catalytic activity significant results were obtained only for few of the catalysts
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Aggarwal, Pankaj. « High-Performance Polymer Monoliths for Capillary Liquid Chromatography ». BYU ScholarsArchive, 2014. https://scholarsarchive.byu.edu/etd/4236.
Texte intégralRésumé :
This dissertation focuses on improving the chromatographic efficiency of polymeric organic monoliths by characterizing and optimizing the bed morphology. In-situ characterization techniques such as capillary flow porometry (CFP), 3-dimensional scanning electron microscopy (3D SEM) and conductivity measurements were developed and implemented to quantitatively characterize the morphology of poly(ethylene glycol) diacrylate (PEGDA) monoliths. The CFP measurements for monoliths prepared by the same procedure in capillaries with different diameters (i.e., 75, 150, and 250 μm) clearly showed a change in average through-pore size with capillary diameter, thus, certifying the need for in-situ measurement techniques. Serial sectioning and imaging of PEGDA monoliths using 3D SEM gave quantitative information about the average pore size, porosity, radial heterogeneity and tortuosity of the monolith. Chromatographic efficiency was better for a monolith with smaller average pore size (i.e., 5.23 μm), porosity (i.e., 0.49), radial heterogeneity (i.e., 0.20) and tortuosity (i.e., 1.50) compared to another monolith with values of 5.90 μm, 0.59, 0.50 and 2.34, respectively. Other than providing information about monolith morphology, these techniques also aided in identifying factors governing morphological changes, such as capillary diameter, polymerization method, physical/chemical properties of the pre-polymer constituents and weight proportion of the same. A statistical model was developed for optimizing the weight proportion of pre-polymer constituents from their physical/chemical properties for improved chromatographic efficiency. Fabricated PEGDA columns were used for liquid chromatography of small molecules such as phenols, hydroxyl benzoic acids, and alkyl parabens. The chromatographic retention mechanism was determined to be principally reversed-phase (RP) with additional hydrogen bonding between the polar groups of the analytes and the ethylene oxide groups embedded in the monolith structure. The chromatographic efficiency measured for a non-retained compound (uracil) was 186,000 plates/m when corrected for injector dead volume. High resolution gradient separations of selected pharmaceutical compounds and phenylurea herbicides were achieved in less than 18 min. Column preparation was highly reproducible, with relative standard deviation (RSD) values less than 2.1%, based on retention times of the phenol standards (3 different columns). A further improvement in chromatographic performance was achieved for monoliths fabricated using a different polymerization method, i.e., living free-radical polymerization (LFRP). The columns gave an unprecedented column performance of 238, 000 plates/m for a non-retained compound under RP conditions.
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Jemah, Adel Karem. « Buckling of stayed columns and elastically supported columns ». Thesis, Cardiff University, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.278598.
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Chakravorty, Utshab. « STUDY OF CHARACTERIZATION OF SUBMICRON COAL PARTICLES DISPERSED IN AIR AND CAPTURE OF COAL PARTICLES BY WATER DROPS IN A SCRUBBING COLUMN ». UKnowledge, 2012. http://uknowledge.uky.edu/cme_etds/16.
Texte intégralRésumé :
Present day water spray based dust removal technologies do not effectively remove respirable submicron coal and silica dust particles in the underground coal mines causing Coal worker’s pneumoconiosis (CWP). The objective of this research was to study the electrostatic charges present in the airborne coal dust in order to develop efficient water spraying based dust removal technology where water drops charged using ionic compounds and surfactants would be used to capture the oppositely charged coal particles. In an experimental scrubbing column, coal particles dispersed in an air stream by a Fluidized Bed Aerosol Generator were captured by water drops sprayed by an atomizer. Characterization studies performed using an Aerodynamic Particle Sizer and Aerosol Electrometer showed that airborne coal particles have a significant amount of positive charge with an average of 140 elementary units of charge. The capture efficiencies of the water drops evaluated were found to be higher than those predicted by previously determined mathematical models. It was predicted that apart from the effects of Brownian diffusion, interception and impaction, the effect of Coulombic attraction was present and the charge of the water drops was predicted to be between - 2 x 10-6 C and -2 x 10-4 C.
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Hazel, William Andrew. « Fourteen Columns ». Thesis, Virginia Tech, 2012. http://hdl.handle.net/10919/44950.
Texte intégralRésumé :
The thesis inquiry is a study of the interrelations between character, emotion and rationality in architecture. The primary modes of representation are digital still photography and hand drawing. To best illuminate these issues the work of the eye and hand of the architect play a vital role. Pastel, pencil and charcoal are the preferred media for the works on paper. Programmatically the building is a boathouse for eight-men crew shells.
The boathouse is embedded into an ideal hillside, with one curved side angled slightly to the water and the landscape beyond. Together with a generous curved roof running the length of the boathouse they provide a covered architectural prow and dry sanctuary below for the storage of the crew shells. From the prow above one has an expansive overlook on the water and the varied activities upon it.
In the thesis project water is not seen as a substance, but rather as a material with a capacity to influence the character of the interior space. For example in the lower level of the boathouse there are small windows adjacent to an artificial water basin. Filtered sunlight passes through the water collected in the basin and then through the small windows. This condition allows a subtle colored light to pervade the lower space.
Another important aspect of this building is a consideration of the twenty-four hour rhythm of day and night. For much of the rowing community, mornings and afternoons are when races or practice activities occur. However the building must be able to show itself when the sun is arriving and departing. In the morning the boathouse and its interior act as an invitation to the rising sun. At night the building provides light to gently
illuminate the darkening surroundings at dusk â similar to a lighthouse resting on its side for shells to navigate towards.Master of Architecture
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Leng, Siwei. « From Crystal to Columnar Discotic Liquid Crystal Phases : Phase Structural Characterization of Series of Novel Phenazines Potentially Useful in Organic Electronics ». Akron, OH : University of Akron, 2009. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=akron1247614330.
Texte intégralRésumé :
Dissertation (Ph. D.)--University of Akron, Dept. of Polymer Science, 2009."August, 2009." Title from electronic dissertation title page (viewed 9/23/2009) Advisor, Stephen Z. D. Cheng; Committee members, Alexei P. Sokolov, Gustavo A. Carri, Darrell H. Reneker, Weiping Zheng; Department Chair, Ali Dhinojwala; Dean of the College, Stephen Z. D. Cheng; Dean of the Graduate School, George R. Newkome. Includes bibliographical references.
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Vais, Anca Mihaela. « Side reboiled distillation columns ». Thesis, University of Nottingham, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.270237.
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Khalil, Nariman Jaber. « Slender reinforced concrete columns ». Thesis, University of Leeds, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.305374.
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BUFFONI, SALETE SOUZA DE OLIVEIRA. « PARAMETRIC INSTABILITY OF COLUMNS ». PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 1998. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=2132@1.
Texte intégralRésumé :
COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIORUNIVERSIDADE FEDERAL DO PARÁ
O presente trabalho tem por objetivo desenvolver uma formulação e certas estratégias que permitam a análise da perda de estabilidade de colunas esbeltas submetidas a carregamento axial periódico, fenômeno este conhecido como ressonância paramétrica. Uma excitação é dita paramétrica quando aparece nas equações de movimento do sistema na forma de coeficientes variáveis com o tempo - geralmente periódicos - e não como uma não homogeneidade. A coluna é descrita pela formulação clássica de Navier. O presente trabalho trata a coluna considerando-se um e três graus de liberdade com ou sem não-linearidades. As equações de movimento são obtidas utilizando-se o princípio de Hamilton através do método de Ritz. A equação linear (equação de Mathieu) e a equação de Duffing com pequeno amortecimento, são resolvidas de forma aproximada pelo método das múltiplas escalas, revelando a possibilidade de instabilização da posição de equilíbrio em diversas regiões do espaço definido pelos parâmetros de controle. A mesma conclusão é mostrada utilizando-se procedimentos computacionais para a resolução dos sistemas de equações lineares e nãolineares, com ou sem imperfeição geométrica inicial, podendo-se obter assim, a resposta do sistema, planos fase, seções de Poincaré e diagramas de bifurcação. Mostra-se a partir dos resultados numéricos, que a coluna submetida a cargas axiais harmônicas, pode tanto apresentar soluções com o mesmo período da força excitadora, quanto oscilações subarmônicas e superarmônicas de diversas ordens, além de movimentos caóticos.
The main aim of the present work is to develop a formulation and some strategies for the instability analysis of slender columns under an axial harmonic force this phenomenon is known as parametric ressonance. An excitation is said to be parametric if it appears as timedependent - often periodic - coefficients in the equations governing the motion of the system,and not as an inhomogeneous term.The column is described by Navier classical formulation. The present work consider the column with one or three degrees of freedom with or without nonlinearities. The equations governing the motion are obtained by the Ritz method.The linear equation (Mathieu equation) and the Duffing equation with small damping are solved in an approximate way using multiple scales techniques, revealing the possibility of destabilizing the static equilibrium position in certain regions of the control space. A similar conclusion is obtained by employing numerical methods for the solution of linear and nonlinear equation systems with or without initial geometrical imperfections.This enables one to obtain time response, phase space, projections Poincaré sections and bifurcation diagrams. These numerical results show that the column with nonlinearities and loaded by a periodic longitudinal force can present various solutions with the same period as the forcing and subharmonic e superharmonic oscillations, as well as chaotic motions.
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Lui, Wing Man. « Design of cold-formed high strength stainless steel tubular columns and beam-columns / ». View abstract or full-text, 2004. http://library.ust.hk/cgi/db/thesis.pl?CIVL%202004%20LUI.
Texte intégralRésumé :
Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2004.Includes bibliographical references (leaves 149-154). Also available in electronic version. Access restricted to campus users.
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Ben, Amar Marwa. « Characterization of adsorption processes for the removal of metal ions from waste effluents using biosorbents and graphene-based sorbents. Studies in Batch and in fixed-bed column ». Doctoral thesis, Universitat de Girona, 2021. http://hdl.handle.net/10803/673800.
Texte intégralRésumé :
Wastewater discharged from industrial and agricultural activities contains relatively large
amounts of toxic metal ions, especially including Cd(II), Cu(II), Pb (II), and Cr(VI). The removal
of these pollutants is of great interest from both health and environmental perspectives. Arsenic
contamination, generally associated with the geochemical environment, is a global threat due to
its acute toxicity and carcinogenicity. The oxidation of different mineral species due to the redox
conditions causes arsenic to become soluble and enter into the surrounding environment through
drainage water. Conventional technologies for wastewater treatment and water purification such
as precipitation, coagulation-flocculation, membrane processes, electrodialysis and ion-exchange
are of limited utility due to their high cost, inefficiency in removing low metal concentrations,
and sometimes also because they can generate large volumes of sludge. Adsorption is an
attractive alternative due to its simplicity, its ability to remove trace amounts of metal ions, low
cost, short operation time, and for the capacity for the material to be reused. Sorption processes
are based on physical adsorption, chemical adsorption and ion exchange mechanisms. Among the
different sorbent materials, activated carbon is the most widely used despite its high initial cost
together with its regeneration costs. In the search for highly efficient, eco-friendly and economic
adsorbents, agricultural waste and by-products from forest industries, including tea waste, coffee,
hulls and shells from different nuts, sawdust, barks, cellulosic and lignocellulosic waste,
corncobs, rice hulls, olive cake, fruit peels, sugar beet pulp, palm fruit bunch, maize leaves,
among others, have been evaluated as biosorbents. They all typically have a good capacity to
adsorb metal ions due to their porous structure and the fact that they have having carboxyl,
hydroxyl, and other functional groups on their surface. The type of functional groups and
chemical components of lignocellulosic materials makes them a good alternative adsorbent to
treat contaminated effluents. The costs of these treatments will be low if the most suitable locally
available biosorbents are used. Hence, in our case, we have evaluated lignocellulosic agroindustrial
waste that is available in the Mediterranean region, such as olive stones and pine cones,
as efficient biosorbents for the removal of toxic metal ions such as Pb(II), Cu(II), Cd(II) and
Cr(VI)Les aigües residuals generades per activitats agrícoles i industrials diverses contenen quantitats relativament grans d’ions metàl·lics tòxics, entre els què s’inclouen els ions Cd(II), Cu(II), Pb(II) i Cr(VI). L’eliminació d’aquests contaminants té un gran interès tant des de la perspectiva de la salut com del medi ambient. La contaminació per arsènic, generalment associada a l’entorn geoquímic, és un problema mundial a causa de la seva aguda toxicitat i carcinogenicitat. L'oxidació de diferents espècies minerals a causa de les condicions redox del medi aquàtic fa que l'arsènic sigui soluble i entri al medi ambient a través de l'aigua de drenatge. Les tecnologies convencionals per tractar les aigües residuals i depurar les aigües, com la precipitació, la coagulació-floculació, els processos de membrana, l’electrodiàlisi i l’intercanvi iònic, són d’utilitat limitada pel seu alt cost, la seva ineficiència en l’eliminació de baixes concentracions de metalls i, de vegades, també perquè poden generar grans volums de fangs. L’adsorció és un tractament alternatiu d’interès atesa la seva simplicitat, la seva capacitat d’eliminar ions metàl·lics a nivell de traces, el seu baix cost, curt temps d’operació i la potencial reutilització dels adsorbents. L’adsorció es pot basar en processos d’adsorció física, adsorció química i d’intercanvi iònic. Entre els diferents materials absorbents, el carbó actiu és el més utilitzat malgrat el seu preu elevat i els costos de regeneració. Com adsorbents alternatius, eficients i ecològics s’ha proposat l’ús de residus agrícoles i subproductes derivats de les indústries forestals, entre els que cal esmentar, entre d’altres, els residus de te i cafè, closques de diferents fruits secs, serradures, escorces, panotxes de blat de moro, pellofes d’arròs, pells de fruita, polpa de remolatxa sucrera, raïm de palma, fulles de blat de moro, i, en general, tot tipus de residus cel·lulòsics i lignocel·lulòsics. Molts d’aquests biosorbents han mostrat tenir una bona capacitat d’adsorció d’ions metàl·lics atesa la seva estructura porosa i la presència de grups funcionals carbonil, carboxil, hidroxil i d’altres tipus com amino o tiol en la superfície del biosorbent. . El tipus de grups funcionals i composició química dels materials lignocel·lulòsics fa que siguin una bona alternativa a altres adsorbents pel tractament d’efluents contaminats. Els costos d’aquests tractaments serien baixos si s’utilitzen els biosorbents adients disponibles localment. Per tant, en el nostre cas, s’han seleccionat residus agro-industrials lignocel·lulòsics disponibles a la regió mediterrània, com els pinyols d’oliva i les pinyes (estròbils), i s’ha avaluat la seva eficiència en l’eliminació d’ions metàl·lics tòxics com Pb(II), Cu(II), Cd(II) i Cr(VI)
Programa de Doctorat en Química
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Perea, Tiziano. « Analytical and experimental study on slender concrete-filled steel tube columns and beam-columns ». Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/37303.
Texte intégralRésumé :
The use of composite steel-concrete columns and beam-columns in many structural systems is increasing globally due to the intrinsic synergy when these materials are designed and detailed together properly. However, limited test data are available to justify the structural system response factors and comprehensive design equations in current design specifications. This research, through the testing of 18 full-scale, slender concrete-filled steel tube (CFT) beam-columns, attempts to address the latter need. The circular and rectangular CFT specimens tested for this research are by far the longest and the most slender full-scale CFT members tested worldwide. These CFT specimens were subjected to a complex load protocol that includes pure compression, uniaxial and biaxial bending combined with compression, pure torsion, and torsion combined with compression. In addition, data from the hydrostatic pressure on the steel tubes due to the fresh concrete at casting was evaluated. The single most important contribution of this research is the clarification of the interaction between strength and stability in slender composite concrete-filled columns and beam-columns. Parallel to the experimental study, advanced computational analyses were carried out to calibrate material and element models that characterize the salient features of the observed CFT response, such as steel local buckling and residual stresses, concrete confinement, stability effects, strength, and stiffness degradation, among others. Based on the observed behavior, simplified guidelines for the computation of the strength and stiffness parameters for CFT columns and beam-columns are proposed for design purposes.
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Trezona, James Richard. « Analysis and design of circular reinforced concrete columns and concrete filled steel tube columns / ». Title page, contents and abstract only, 1995. http://web4.library.adelaide.edu.au/theses/09ENS/09enst818.pdf.
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Al-Shihri, Marai Abdullah 1958. « BUCKLING STRENGTH OF HEAVY STEEL COLUMNS (WELDED SHAPES, INITIAL CURVED COLUMNS, HOT-ROLLED SHAPES) ». Thesis, The University of Arizona, 1986. http://hdl.handle.net/10150/291869.
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Schaller, Markus. « Numerically Optimized Diabatic Distillation Columns ». Doctoral thesis, Universitätsbibliothek Chemnitz, 2007. http://nbn-resolving.de/urn:nbn:de:swb:ch1-200701134.
Texte intégralRésumé :
Im Gegensatz zur konventionellen adiabatischen Destillation erfolgt bei der diabatischen Destillation Wärmeaustausch nicht nur am Kondensator und Verdampfer, sondern auch innerhalb der Kolonne an den einzelnen Siebböden, was die Entropieproduktion (=Exergieverlust) des Destillationsprozesses stark reduziert. In dieser Arbeit werden Modellsysteme zur diabatischen Destillation von idealen binären Gemischen mittels numerischer Optimierung untersucht. Das Ausgangsmodell beschränkt sich auf die Minimierung der Entropieproduktion verursacht durch Wärme- und Massentransport im Inneren der diabatischen Destillationskolonne. Im zweiten Modell wird das diabatische Modell um die Irreversibilität bedingt durch den Wärmeaustausch mit der Umgebung erweitert. Im dritten Modellsystem wird anstelle der bis dahin voneinander unabhängig geregelten Bodentemperaturen eine diabatische Implementierung mit seriellen Wärmetauschern untersucht, die nur mehr vier Kontrollvariablen besitzt und besonders zur praktischen Anwendung geeignet ist. Für alle diabatischen Modelle werden die minimale Entropieproduktion und optimalen Betriebsprofile numerisch ermittelt, und mit konventionellen Destillationskolonnen verglichen. Alle Ergebnisse zeigen eine deutlich Reduktion der Entropieproduktion für den diabatische Fall, besonders bei Kolonnen mit vielen BödenContrary to conventional adiabatic distillation, in diabatic distillation columns heat transfer not only happens at the condenser and reboiler but also at the intermediate trays which strongly reduces the entropy production (= exergy losses). In this work, model systems for the diabatic distillation of ideal binary mixtures are investigated numerically.The first model is restricted to the minimization of the entropy production due to heat and mass transfer inside the diabatic column. In the second approach the model is extended with the irreversibility due to heat transfer with the column's surroundings. Instead of independently controlled tray temperatures as in the latter models, we focus on a specific diabatic implementation with sequential heat exchangers, which has merely four controls and which is particularly suitable for practical application. For all diabatic models the minimum entropy production and resulting optimal operating profiles are determined numerically, and compared to the ones obtained for a conventional column. All results show an enormous reduction of the entropy production for the diabatic case, especially for columns with many trays
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Kim, Dong Keon. « A Database for Composite Columns ». Thesis, Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/7126.
Texte intégralRésumé :
A database of composite column tests was augmented and utilized to evaluate the proposed AISC 2005 provisions. The database consists of column and beam-column steel-concrete columns (or encased, SRC), circular concrete filled tubes (CCFT), and rectangular concrete filled tube (RCFT). Information on material and geometric properties on each specimen was summarized. The database includes 119 SRC columns, 136 SRC beam-columns, 312 circular CFT columns, 198 circular CFT beam-columns, 222 rectangular CFT columns and 194 rectangular CFT beam-columns. The database has a total of 1181 specimens, an addition of 451 specimens over those in the original database (Aho 1996).
The data on each specimen was analyzed and compared with current design provision for composite columns (AISC 1999 and Eurocode 4), and reassessed by the upcoming 2005 AISC specification. The data indicates that the Eurocode gives good predictions for columns and the AISC 2005 method performs very well for beam-columns. For rectangular CFT columns, all three methods predict the ultimate capacity very well. The main improvement for the AISC 2005 method is its ability to handle specimens which have high yield stress and/or high strength concrete.
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Flores, Tlacuahuac Antonio. « Robust control of distillation columns ». Thesis, Imperial College London, 2011. http://hdl.handle.net/10044/1/8016.
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Elmahdy, Ghada. « Buckling of built-up columns ». Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ30272.pdf.
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Xu, Manqiu. « Sparger study in flotation columns ». Thesis, McGill University, 1987. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=64062.
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Hunaiti, Y. M. « Behaviour of battened composite columns ». Thesis, University of Manchester, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.374803.
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Philip, J. « Viscous liquids in bubble columns ». Thesis, University of Cambridge, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.235274.
Texte intégralRésumé :
This dissertation is concerned with studies of highly viscous Newtonian and non-Newtonian liquids in bubble columns with, and without, draft tubes. The importance of the parameters influencing bubble column reactors is discussed with reference to previous work. The shapes and rise velocities of single bubbles in these liquids were studied in an 8.8cm diameter column, and the gas holdup, resulting from continuous bubbling of gas into this column, was also measured. Agreement between holdup predicted by the equation of Nicklin et al (1962), and experimental data in die present work and that of other workers is good. The limiting result of Dumitrescu (1943) was found to apply for fully developed slug flow in viscous non-Newtonian liquids in large columns. Gas holdup, in a 15cm diameter bubble column with a draft tube, consisted of large bubbles (slugs), which rapidly rose through the liquid, and very small bubbles, which accumulated in the liquid. These small bubbles were generated near the gas distributor and also at the liquid surface; less than 1% of the total gas flowrate into the system was converted into small bubbles for a highly viscous Newtonian liquid. The gas holdup due to small bubbles in non-Newtonian liquids was much less than that in Newtonian liquids. Large bubble velocities deduced from the bubble column measurements were consistent with the single bubble measurements. Liquid velocities in the 15cm column were measured by a neutrally buoyant flow follower; the liquid circulation rate was found to decrease with an increase in liquid viscosity. A model to predict the liquid circulation rate is outlined. The effect of scale-up on the gas holdup and liquid circulation rate was also studied experimentally in a 60cm square bubble column with a 30cm square draft tube. The bubble size distribution in this column was similar to the 15cm column but liquid velocities were higher, and gas holdup was smaller in the 60cm column.
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Al-Dunainawi, Yousif Khalaf Yousif. « Intelligent Control for distillation columns ». Thesis, Brunel University, 2017. http://bura.brunel.ac.uk/handle/2438/15597.
Texte intégralRésumé :
Nowadays, industrial processes are having to be rapidly developed to meet high standards regarding increases in the production rate and/or improving product quality. Fulfilling these requirements is having to work in tandem with the pressure to reduce energy consumption due to global environmental regulations. Consequently, most industrial processes critically rely on automatic control, which can provide efficient solutions to meet such challenges and prerequisites. For this thesis, an intelligent system design has been investigated for controlling the distillation process, which is characterised by highly nonlinear and dynamic behaviour. These features raise very challenging tasks for control systems designers. Fuzzy logic and artificial neural networks (ANNs) are the main methods used in this study to design different controllers, namely: PI- PD- and PID-like fuzzy controllers, ANN-based NARMAL2 in addition to a conventional PID controller for comparison purposes. Genetic algorithm (GA) and particle swarm optimisation (PSO) have also been utilised to tune fuzzy controllers by finding the best set of scaling factors. Finally, an intelligent controller is proposed, called ANFIS-based NARMA-L2, which uses ANFIS as an approximation approach for identifying the underlying systems in a NARMA-L2 configuration. The controllers are applied to control two compositions of a binary distillation column, which has been modelled and simulated in MATLAB® and on the Simulink® platform. Comparative analysis has been undertaken to investigate the controllers' performance, which shows that PID-like FLC outperforms the other tested fuzzy control configurations, i.e. PI- and PD-like. Moreover, PSO has been found to outperform GA in finding the best set of scaling factors and over a shorter time period. Subsequently, the performance of PID-like FLC has been compared with ANN-based NARMA-L2 and the proposed ANFIS-based NARMA-L2, by subjecting the controlled column to different test scenarios. Furthermore, the stability and robustness of the controllers have been assessed by subjecting the controlled column to inputs variance and disturbances situations. The proposed ANFIS-based NARMAL2 controller outperforms and demonstrates more tolerance of disturbances than the other controllers. Finally, the study has involved investigating the control of a multicomponent distillation column due to its significant enhancement in operational efficiency regarding energy saving and recent widespread implementation. That is, Kaibel's distillation column with 4×4 configuration has been simulated also in MATLAB® and on the Simulink® platform with the proposed controller being implemented to control the temperatures of the column and the outcomes subsequently compared with conventional PID controllers. Again, the novel controller has proven its superiority regarding the disturbances tolerance as well as dealing with the high dynamics and nonlinear behaviour.
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Prasad, Badri Krishnamurthy 1959. « Experimental investigation of sleeved columns ». Thesis, The University of Arizona, 1989. http://hdl.handle.net/10150/277134.
Texte intégralRésumé :
Results of experimental tests are presented for twelve 'Sleeved Column' specimens. All the specimens had an outer sleeve and an inner core, both of rectangular cross section. Outer sleeve was 23 in. long and the inner core was 23.5 in., with axial load applied only to the core. There was a gap between the sleeve and the core for all specimens except for one which had zero gap. The parameters considered for the study were core thickness and gap. It was concluded from the study that the sleeved column system carries substantially more load than the conventional Euler's column. The stiffness of the core and the gap between the sleeve and the core affects the load carrying capacity of sleeved column system significantly. For the same core size, specimens with least gap carried more load when compared to other specimens with larger gaps.
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Rahimi, Rahbar. « Heat transfer in bubble columns ». Thesis, University of Bath, 1988. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.380868.
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Yang, Guoqiang. « Bubble formation dynamics and transport phenomena in high pressure bubble columns and slurry bubble columns / ». The Ohio State University, 2001. http://rave.ohiolink.edu/etdc/view?acc_num=osu1486474078051133.
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