Instrumentation to Monitor Bridge Foundation on the Crosstown Project

The Crosstown Bridge Monitoring Project is located at the intersection of Highway 62 and Interstate I35W a few miles south and west of downtown Minneapolis. The bridge being evaluated is at a railroad overpass located midway along the Crosstown expansion. This research project involved placing instrumentation on the bridge foundation in order to measure the change in the foundation loading during the course of the construction project. For several years there have been questions pertaining to the forces in the pile foundations that support highway embankments. This project placed strain gages on the pile foundations in order to monitor these forces over time. The gages were places in select locations on the piles prior to being driven into the ground to support the bridge abutments. To protect the gages during driving, steel angles were welded to the piles to cover the gages and cables. The cables were connected to a data collection system in order to monitor the foundation over time. This portion of the overall project involved testing the stain gages prior to pile driving and after pile driving in order to determine if any damage to the gages occurred during pile driving. Readings taken using a datalogger and a simple multimeter will be provided to show the results of this check, with conclusions relating to the mortality of the gages. Although this project is still in its preliminary stages, the object of the overall project will be to monitor and record the stains for several years

Gas Turbine Fuel and Fuel Quality Requirements for use in Industrial Gas Turbine Combustion

TutorialFor economic and environmental reasons, it is important that gas turbines used in Oil & Gas applications can burn a wide variety of fuels with the minimum impact on the environment. This workshop will examine the types of gaseous and liquid fuels that can be used in Industrial Gas Turbines, and discuss the two basic types of combustion system employed – ‘conventional’ and ‘Dry Low Emissions’ – and the flexibility of these systems to accept different types of fuel. It will also look at common contaminants found in fuels and the impact these contaminants can have on the operability and maintenance of an industrial gas turbine

Modular construction of a Byzantine agreement protocol with optimal message bit complexity

This paper presents a new Byzantine agreement protocol that tolerates t processor faults using 3t + 1 processors, t + o(t) rounds, O(t2) total message bits, and O(tɛ) maximum message size, for any ɛ > 0. The protocol is optimal or near optimal in all cost measures: the number of processors is optimal, the message bit complexity is optimal, the number of rounds exceeds the lower bound by o(t), and the maximum message size exceeds the lower bound by O(tɛ). The round complexity is uniformly better than 2·(t + 1) and thus is reasonable even for small t. This is the first Byzantine agreement protocol to have optimal message bit complexity. The new protocol is constructed by recursively applying a simple, yet general, transformation that changes the number of rounds, total message bits, and maximum message size required by a Byzantine agreement protocol, but preserves correctness, number of processor faults tolerated, and total number of processors. Each application of this new transformation reduces the number of message bits sent—at the expense of adding rounds of communication. Surprisingly, the base case of the recursive construction is the agreement protocol of Lamport, Shostak, and Pease, which has a number of message bits exponential in t

Neuromuscular control of wingbeat kinematics in Anna's hummingbirds (Calypte anna)

Hummingbirds can maintain the highest wingbeat frequencies of any flying vertebrate – a feat accomplished by the large pectoral muscles that power the wing strokes. An unusual feature of these muscles is that they are activated by one or a few spikes per cycle as revealed by electromyogram recordings (EMGs). The relatively simple nature of this activation pattern provides an opportunity to understand how motor units are recruited to modulate limb kinematics. Hummingbirds made to fly in low-density air responded by moderately increasing wingbeat frequency and substantially increasing the wing stroke amplitude as compared with flight in normal air. There was little change in the number of spikes per EMG burst in the pectoralis major muscle between flight in normal and low-density heliox (mean=1.4 spikes cycle^(–1)). However the spike amplitude, which we take to be an indication of the number of active motor units, increased in concert with the wing stroke amplitude, 1.7 times the value in air. We also challenged the hummingbirds using transient load lifting to elicit maximum burst performance. During maximum load lifting, both wing stroke amplitude and wingbeat frequency increased substantially above those values during hovering flight. The number of spikes per EMG burst increased to a mean of 3.3 per cycle, and the maximum spike amplitude increased to approximately 1.6 times those values during flight in heliox. These results suggest that hummingbirds recruit additional motor units (spatial recruitment) to regulate wing stroke amplitude but that temporal recruitment is also required to maintain maximum stroke amplitude at the highest wingbeat frequencies

Molecular Layer Deposition for Membrane Applications

Molecular layer deposition (MLD) is a layer-by-layer technique capable of creating polymer thin films with monomer level control over thickness, cross-linking and chemical composition. With these capabilities, MLD is ideal the fabrication of polymeric membranes. Two crosslinked semipermeable polyamide MLD films, presented in Chapter 2, were made from m-phenylenediamine (MPD) and trimesoyl chloride (TMC) as well as piperazine and TMC. The growth and properties of the polyamides were characterized with FTIR, XPS and ellipsometry.Thin film composites were fabricated using MLD in Chapter 3. In this method, the pores of ultrafiltration membranes were capped with Al2O3 using plasma-enhanced atomic layer deposition. MPD-TMC MLD films were then deposited on the non-porous capping layer. The Al2O3 pore caps were then removed by timed backside exposures to a dilute sodium hydroxide solution. Pore-capping and etching was confirmed with gas permeance measurements. The removal of the Al2O3 pore caps on polymer substrates led to the detachment of the MLD film. However, the film was anchored to the support at fractures located in the Al2O3 film prior to the MLD. Anchoring was controlled by tuning the fracture density which was varied with applied tensile stress via sample bending. In the final chapter, a new nonporous support was utilized to produce reverse osmosis membranes with MLD. MPD-TMC films as thin as 0.5 nm were applied to NF270 nanofiltration membranes. Within two molecular layers, desalination performance was affected. As film thickness increased to 15 nm (48 MLD cycles), performance progressed from nanofiltration to reverse osmosis metrics in terms of salt rejection and water permeance. With film thickness &gt;5 nm, rejection values exceeded a small sampling of commercial membranes. In all cases, a tradeoff between rejection and permeance was observed. Atomic force microscopy measurements indicate that MLD enhancement led to removal of small-scale roughness features and resulted in a root mean square roughness difference of &lt;0.1 nm from the substrate. These initial MLD studies represent a novel processing approach that offers a potential pathway for the fabrication of membranes with finely tailored properties.</p

Investigations of Star Formation and Ionizing Radiation Across Time and Spatial Scales

This thesis explores a broad range of spatial scales across a broad range of times throughout the history of the universe, with the goal of improving our understanding of star formation and the origin of ionizing radiation across these broad scales. In the nearby universe, we can examine star formation on galactic scales and at the level of individual stars. However, in the distant universe, we are often limited to only the larger galactic scales due to finite telescope resolution. However, with gravitational lensing, we can reveal similarly small scales in distant galaxies. In my work, I examined lensed galaxy substructure at redshifts z > 6 down to parsec scales, and in one case I determined that an individual star is observed at z = 6. These observations allow for detailed study of the structures of these distant galaxies, as well as the composition of a star within the first billion years of the universe. On the larger scales, galaxy clusters typically contain little active star formation. However, I examined diffuse ultraviolet radiation around massive clusters and found an excess, which could be explained by ongoing star formation in the intracluster medium. Together, these studies contribute to our understanding of star formation on multiple scales. Additionally, young, UV-bright stars are key contributors to the ionizing radiation that drove the transition from neutral to ionized hydrogen in the early universe, and contributes to continuing that ionized state today. The studies presented herein again offer a multi-scale perspective on the sources of ionizing UV light. The small scale star formation in distant galaxies can help determine how ionizing photons are created and escape from these galaxies into the intergalactic medium, where they contribute to reionization. Meanwhile, studying the UV emission from galaxy clusters provides an additional source to help make sense of the UV background light, which, at higher energies, contributes to maintaining the ionized state of the intergalactic medium