Nanoscale confinement can be defined as a space confined by interfaces with at least one nanometer-scale dimension. Objects under nanoscale confinement have a large ratio of interfacial area to volume that makes interfacial properties have significant impact. This dissertation examines three cases in which liquids are confined between solids. The main focus (two papers) describes how electrostatic interactions between two interfaces affect ions confined within the liquid. Commonly, the charge distribution near an interface is described by electrical double layer model, where the characteristic decay length of the potential is the Debye length κ^(-1), which is typically 1–100 nm. In a nanoscale confinement, the electrostatic potential from both confining surfaces overlaps, and there is no bulk solution in the confined liquid. If the two surfaces have the same potential in isolation, the potential will increase throughout the liquid phase. I examine two hypotheses for ions under confinement in aqueous solution: (1) diffusion of ions will be hindered by the electrostatic potential; (2) surfactants will form surface aggregates (a form of micelles) that would not occur without the modified potential. To test the first hypothesis, I studied diffusion of fluorescein sodium salt in the nanoscale water confined between glass surfaces. The confining glass surfaces were fabricated by thermally bonding Borofloat glass wafers. Fluorescence microscopy was used to monitor the amount of fluorescein throughout the confined water, and thereby to understand the diffusion Measurements with done for a variety of different Debye lengths and water film thicknesses. I found that the time for fluorescein to reach equilibrium distribution in the nano-scale confinement could be 10× longer when there was no salt initially present compared to when salt was present. However, even a small amount of salt initially in the confined liquid led to a very weak effect of Debye length on diffusion. Thus, provided that the surface potential inside a thin film is initially screened by even a low concentration of electrolyte inside the confinement, diffusion is unhindered. A practical application of this result is delivery of dissolved species should not be preceded by infusion of pure water into pores if speedy delivery is desired. For the second hypothesis, I studied adsorption and aggregation of dodecyltrimethylammonium bromide (DTAB), a cationic surfactant, within the same type of nanoscale confinement by Borofloat glass. A fluorescent dye, Nile red, whose fluorescence depends on its solvent environment was used to indicate formation of surface aggregates by the surfactant. We found that surface aggregation of DTAB occurred at a very low surfactant concentration (<1 % of the critical micelle concentration) when the confinement was less than 30 nm, which was about one Debye length of the solution. This finding overturns a major assumption of many surface forces measurements and ideas of colloidal stability. It has been customary to assume that the state of surfactant aggregation is constant when two particles approach, whereas we find that aggregation changes with the solution is confined. The change in aggregation can lead to a change in electrical potential, which affects the surface forces and colloidal stability. Past work that used this assumption will need to be re-interpreted. The third topic was the study of the displacement of oil trapped in dead-end nanopores by water. This is a model of the process of tertiary oil recovery. Surfactants are used to assist with oil recovery, but the mechanism is not well studied. Three hypotheses were considered for the effect of surfactant on oil displacement: (1) Lowering of the oil–water interfacial tension; (2) Adsorption to the water–solid interface; and (3) Effects on transport rather than thermodynamics. Measurements of three different types of surfactants: sodium dodecyl sulfate (SDS), an anionic surfactant; Aerosol OT (AOT), an anionic surfactant; dodecyltrimethylammonium bromide (DTAB), a cationic surfactant; and no surfactant. Results show that AOT was the only surfactant that led to substantial spontaneous displacement of oil within 12 hours. The effect was attributed to AOT's ability for form reverse micelles in the oil phase that could deliver water to the hydrophilic solid walls, thereby displacing oil. No prior literature describing this mechanism has been found. / Doctor of Philosophy / Nanoscale confinement are domains contained by interfaces with at least one dimension on the nanometer scale level. This dissertation describes very thin (1–100 nm) layers of water between solids. Such thin layers of water are important in oil recovery, cellular processes, delivery of sham-poo to hair, drug delivery, etc. I studied the transport and adsorption of ions in these thin layers, particularly when the solid walls were charged. Results show that (1) Diffusion of ions could be se-verely hindered by unscreened electrostatic potential within the thin film of water. Diffusion times were increased by up to 10 times; (2) Surfactant aggregation occurred in the thin film, even when it did not occur in bulk solution at the same concentration; (3) Water could not displace oil in a thin film, even when assisted by a variety of surfactants. One particular surfactant, Aerosol OT could displace the oil, which I attribute to its ability to transport water through the oil and onto the solid.

High energy density experiments rely heavily on predictive physics simulations in the design process. Specifically in inertial confinement fusion (ICF), predictive physics simulations, such as in the radiation-hydrodynamics code xRAGE, are computationally expensive, limiting the design process and ability to find an optimal design. Machine learning provides a mechanism to leverage expensive simulation data and alleviate limitations on computational time and resources in the search for an optimal design. Machine learning efficiently identifies regions of design space with high predicted performance as well as regions with high uncertainty to focus simulations, which may lead to unexpected designs with great potential. This dissertation focuses on the application of Bayesian optimization to design optimization for ICF experiments conducted by the double shell campaign at Los Alamos National Lab (LANL). The double shell campaign is interested in implementing graded inner shell layers to their capsule geometry. Graded inner shell layers are expected to improve stability in the implosions with fewer sharp density jumps, but at the cost of lower yields, in comparison to the nominal bilayer inner shell targets. This work explores minimizing hydrodynamic instability and maximizing yield for the graded inner shell targets by building and coupling a multi-fidelity Bayesian optimization framework with multi-dimensional xRAGE simulations for an improved design process. / Doctor of Philosophy / Inertial confinement fusion (ICF) is an active field of research in which a fuel is compressed to extreme temperatures and densities to achieve thermonuclear ignition. Ignition is achieved when the fuel can continuously heat itself and sustain its reactions. These fusion reactions would produce large amounts of energy. Power plants using fusion could solve many of the world's energy concerns with far less pollution than current energy sources. Although ignition has not been achieved in the lab, ICF researchers are actively working towards this goal. At Los Alamos National Lab (LANL), ICF researchers are focused on studying ignition-relevant conditions for "double shell" targets through experiments at laser facilities, such at the National Ignition Facility (NIF). These experiments are extremely expensive to field, design, and analyze. To obtain the maximum information from each experiment, researchers rely on predictive physics simulations, which are computationally intensive, making it difficult to find optimal target designs. In this dissertation, better use of simulations is made by focusing on using machine learning along with simulation data to find optimal target designs. Machine learning allows for efficient use of limited computational time and resources on simulations, such that an optimal target design can be found in a reasonable amount of time before an ICF experiment. This dissertation specifically looks at using Bayesian optimization for design optimization of LANL's double shell capsules with graded material inner shells. Several Bayesian optimization frameworks are presented, along with a discussion of optimal designs and physics mechanisms that lead to high performing capsule designs. The work from this dissertation will create an improved design process for the LANL double shell (and other) campaigns, providing high fidelity optimization of ICF targets.

No description available.

The goal of this research project is to analyze the behavior of columns made with plain concrete and synthetic polypropylene/polyethylene fiber addition. In order to supplement the current data base, an experimental study was carried out on six columns of real size and ordinary concrete resistance confined by circular stirrups and subjected to constant axial loads and cyclic flexure. Three columns were built with concrete of normal resistance with 0% of synthetic fibers and three columns were built of concrete with 1% by volume of synthetic fibers.The used concrete strength varied from 25 to 42 MPa, the resistance of longitudinal steel was 510 MPa, that of the stirrups of 468 and 510 MPa and the axial factor load around 25% Ag f'c . Today, it is possible to explore the behavior in the plastic range of the structural elements under seismic loading. Predictions of behaviour of moment vs curvature as well as predictions of force vs displacement relationship were accomplished. Indeed, the comparison between the experimental results and the prediction made for the specimens with and without fibers shows a very good agreement. In the case of the prediction of the moment vs curvature relationship, the MNPHi software developed by [PAULTRE, 1996] was used and in the case of the prediction of force vs displacement relationship, software DISP96 developed by [LÉGERON, 1998] was used. Finally, the influence of tie spacement as well as addition of fibers were clearly observed.The results show that the presence of polypropylene/polyethylene fibers in the concrete matrix improves ductility, tenacity, and the capacity to dissipate energy. Also, they help to retain the cover concrete.

This study presents an assessment of the seismic performance of rectangular concrete columns internally reinforced with G (Glass) FRP. Eight full-scale columns prototypes, with a shear span of 1650-mm and 350-mm square cross-section, were constructed and tested under simulated seismic waves and constant axial loading. These columns simulate the lower portion of first storey columns between the footing and the contra-flexure point. Therefore, heavy steel-RC footing was post-tensioned to the laboratory strong floor in order to provide rational fixity to the column. The test parameters included reinforcement type, longitudinal reinforcement ratio, level of axial load, and stirrup spacing. Test results showed that deformability of GFRP-RC columns prototypes successfully replaced ductility in steel-RC columns in dissipating the seismic energy in the presence of constant axial load. Furthermore, the failure of sections was prominent by flexure concrete crushing at high drifts. Accordingly, GFRP-RC columns are a doable application in earthquake-resistant structures. / October 2015

No description available.

During the last 9 years I have completed 2300 confinement cases in general practice in a working class district in Edinburgh. During this period I resolved to keep a correct record of every case in a book kept for the purpose and written in every instance immediately after the birth has taken place and while the facts were fresh in my memory. The object then of the thesis is to 1. Contrast it with analysis of other records 2. To give a faithful account as to the manner and success with which I did my work 3. To make suggestions which such an experience may indicate.

Ce travail de thèse porte sur l'étude des performances des lasers à base de bâtonnets quantiques en régime de verrouillage de modes passif dans différentes configurations: laser à deux sections (une section de gaine et une section à absorbant saturable) et laser autopulsant constitué d'une seule section de gain. Nous nous intéresserons tout particulièrement au bruit de phase et à la gigue temporelle des impulsions, caractéristiques limitantes pour les applications faible gigue telles que la récupération d'horloge tout-optique ou la génération de porteuses optiques micro-ondes et millimétriques. Une technique de stabilisation optique permettant de réduire cette gigue temporelle est mise en oeuvre dans ces travaux. Nous présentons également la génération d'impulsions sub-picosecondes à des fréquences de répétition supérieures à 300 GHz à l'aide de lasers autopulsants. / This PhD thesis deals with the study of passive quantum-dash-based mode locked laser in different configurations: 2-section device (one gain section and one saturable absorber section) and self pulsating laser using a single section device.We have assessed in particular phase noise and timing jitter in optical pulses. The latter is very important for low jitter applications as ail optical clock recovery and millimeter wave generation. Stabilization technique based on optical feedback has been applied to reduce the timing jitter. Moreover, we present passive mode locked operation of a self-pulsating quantum dash Fabry-Perot laser diode at arepetition rate over 300 GHz.

Thesis advisor: Michael Graf / Bismuth is an interesting element to study because the low effective mass of its charge carriers makes the material sensitive to quantum confinement effects. When bismuth is reduced to the nanoscale two interesting phenomena may occur: it may transition from a semimetal to a semiconductor, or charge carriers in special surface states may begin to dominate the behavior of the material. Arrays of bismuth nanowires of various diameters were studied to investigate these possibilities. The magnetoresistance of the arrays was measured and the period of Shubnikov-de Haas oscillations suggested an increase in the effective mass and density of the material’s charge carriers for small nanowire diameters. These increases suggested that electrons were present in surface states and strongly influenced the material’s behavior when its dimensions were sufficiently reduced. The magnetization of the nanowire arrays was also measured and the lack of de Haas-van Alphen oscillations for certain diameter nanowires suggested that electrons were not present in surface states and that instead the material was transitioning from a semimetal to a semiconductor. Heat capacity measurements were planned to reconcile the two experiments. My detailed calculations demonstrated that heat capacity measurements were feasible to determine the presence, or absence, of surface charge carriers. Because the electronic contribution to the material’s heat capacity is small a calorimeter platform was constructed with ultra-low heat capacity components. / Thesis (BS) — Boston College, 2009. / Submitted to: Boston College. College of Arts and Sciences. / Discipline: College Honors Program. / Discipline: Physics.

Victorian society witnessed a transformation in the understanding and treatment of psychological disorders. The expansion of nosologies or classifications of lunacy was one measure hailed by psychological physicians as indicative of their mastery over madness. Yet between the 1840s and the 1870s the introduction of moral insanity and monomania to established classificatory systems undercut the medical authority of physicians and challenged their desired cultural stature as benevolent and authoritative agents of cure. Far from consolidating medical authority, these `partial' forms of lunacy (which were detected in the emotions rather than the intellect) paradoxically heightened anxiety about the ease with which eccentric or sane individuals could be wrongfully incarcerated in lunatic asylums. This dissertation examines the themes, motifs and defining issues of wrongful incarceration as they were discussed in Parliament, national and regional newspapers, medical and literary journals, and novels and short stories. Discussing in detail several infamous `cases' of wrongful confinement, it traces the ways in which anxieties were formulated, expressed and negotiated. The public outcry over cultural representations of wrongful confinement generated heated reactions from physicians and lunacy law reformers. The most contentious discussions centred on the manner in which notions of humanity and benevolence, and tyranny and liberty, were marshalled to influence public opinion. These debates represented not solely a legal conflict centring the claim to treatment and authority over the alleged lunatic, but more dramatically a battle for the public's good opinion. As important as medico-legal trials and their consequent rulings was the contested appropriateness of sentiment; this was manifested in words and images utilised to exacerbate or contain anxiety. The wrongful confinement controversy constitutes an important (though largely overlooked) episode in the history of English nineteenth-century psychiatry; formatively altering perceptions of the profession of mental science in the Victorian period.