Thesis (M.A.)--University of North Carolina at Wilmington, 2007. / Includes bibliographical references (leaves: 92-105)

Thesis (M.P.H.)--University of Hong Kong, 2006.

Context. Performance and resource usage is often an important factor for database driven services. Depending on the purpose of the application, choosing the wrong type of database may require unnecessary hardware upgrades or replacements. Objectives. This study investigates the differences in performance and resource usage between different SQL- and NoSQL-databases. The study is a comparison that focuses on how the databases perform in different applications. The purpose is to give a hint of which database may be the most appropriate depending on the application. Methods. The different databases are compared using experiments, executed with the help of a testing tool developed to measure the performance and resource usage for the different databases. Results. Several tests have been executed on Cassandra, MongoDB and MySQL that are the databases used in this study. Where the performance is measured as operations per second and the resource usage is measured as the activity of CPU, RAM and harddrive. Conclusions. We conclude that the databases perform differently well dependning on the application. In some of the cases MongoDB performed the best, while MySQL performed best in others. The resource usage also differs a lot, like the performance, dependning on the application. As a conclusion it’s recommended to test what database may suit the specific situation depending on the application.

Circadian rhythms are endogenous molecular clocks that correspond to the 24-hour day and are regulated by light stimulus, allowing organisms to entrain to the dawn-dusk cycle. These clocks may allow organisms to anticipate daily events, influencing their behavior. In arthropods, including spiders, circadian rhythmicity is tested using activity monitors, which house individuals in tubes. However, this does not reflect the natural habitat of many spiders. We compared the locomotor activity of the cellar spider Pholcus phalangiodes in activity monitors with the locomotor activity in web boxes. After being entrained to a 12:12 light:dark cycle, the spiders were recorded in constant darkness. The resulting free-running periods demonstrated similar clock data for spiders in tubes as in boxes. This validates the activity-monitor research method.

In recent years, the number of electric vehicles (EVs) on the road has increased drastically. In parallel to the increase of EVs, there is a proportionate increase in collisions involving them which poses a serious risk of Lithium-Ion Battery (LIB) damage. As these EVs and technology continue to increase in occurrence and complexity, there must be a similar jump in advanced testing and modelling to accurately predict and protect against major failure. FEM has emerged as the leading preventative measure for crash analysis but, due to the complexity of modern vehicles, these simulations require homogenization of models for simplicity and reduced calculation time. This requires experimental equipment to be developed to mechanically deform the LIBs in order to obtain load and displacement curves necessary for simulation. These simulations are then calibrated in order to represent the experiment that has been completed. Thus far researchers have focused on the compression properties but have not provided insight into the rebound response of the battery cells. This thesis project is threefold: to develop experimental equipment necessary to perform the required deformation testing, use said equipment to perform deformation experiments on a series of LIB, and to develop a set of models corresponding to the indentation experiments. The simulations from these models should accurately represent the compression and rebound portions of the resultant load-displacement curves. It was determined that adjustment of the final stage of the stress curve used in LS DYNA, dictated the response of the rebound curve following compression. The comparison of the simulation vs the experimental results of the indentation experiments show that depending on the type of loading, different representative material models could be used to simulate the cell behavior. Effects of punch head size, element size, as well as punch head geometry and material selection were studied in this research. The smaller the punch head the smaller the elements must be to capture the LIB response and similarly the more complex the punch geometry the smaller the elements must be. These findings, and the models developed will be used to further the research on LIB homogenization and fully modelling rebound curves moving forward. / Mechanical Engineering

In this dissertation, experiments are described which elucidate how the ordering of symmetric diblock copolymers affects the dynamics within various geometries. In all studies presented herein, experimental techniques are used to probe the dynamics of symmetric diblock copolymer systems as they progress toward equilibrium and to study the role that nanoscale ordering plays in these processes. In the majority of work presented herein, experiments were performed on symmetric diblock copolymer thin films. This work focuses on the effect of various sample preparation techniques on the equilibration kinetics of lamellar forming films. Films are prepared with varying thicknesses in the homogeneous, disordered state and annealed to form islands and holes as the surface decomposes to form commensurate thicknesses. Both nucleated and spinodal growth patterns were observed for this surface decomposition dependent on the initial thickness and intermediate morphologies formed upon ordering. We also prepare equilibrium commensurate films and induce a step change in surface interactions, switching from asymmetric to symmetric wetting boundaries. Upon equilibration, a perforated lamella forms at the free surface to mediate the order-order transition, inducing hole growth with a ramified shape. In the final project, the effect that lamellar order has on dynamics is studied within unstable polymer melt bridges. Liquid bridges are what is formed when a droplet is stretched between two surfaces, like spit between two fingers. Disordered diblock bridges are shown to evolve similar to their homopolymer counterparts. However, ordered diblock copolymer exhibits an enhanced stability with an inhibition of flow proposed to be induced by the isotropic orientational order within the bridge. As well, shear thinning is observed that is believed to be caused by an alignment of ordered domains along the bridge axis due to shear strain rates, providing pathways for flow of diblock copolymer out of the unstable bridge. / Thesis / Doctor of Philosophy (PhD)

No description available.

A Hint of Meaning contains a scholarly preface, "Language, Experimentation, and Craft: Creating a Vivid, Continuous Fictional Dream," that discusses the ambiguities of language and how they relate to different aspects of the craft of writing. Six original short stories follow the preface. "Musical Chairs" explores a woman's conflicting emotions about her ex-husband. "Baby Steps" depicts the struggle of a woman against her father's alcoholism. "Go Home Happy" depicts a day in the life of a video store employee. "Bargain Basement Perfection" contrasts the reality of a relationship with an imagined, perfect relationship. "Did You Hear about Donald and Bitsy?" is an experimental piece that tells a story through gossip. "Glass Angels" explores a minister's relationship with his homosexual son and how that relates to the minister's faith.

Note:

No description available.