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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
231

Proton acceleration experiment by high intensity laser pulse interaction with solid density target at the Texas Petawatt Laser Facility

Kuk, Donghoon 20 February 2012 (has links)
In recent, high intensity laser pulse interaction with solid density matter has been studied in several laboratory and facilities. Multi-MeV proton and ion beams from plasma produced by this interaction is one important application research area of HEDP. In this thesis, the basic theory of hot electron generation associated with proton acceleration will be introduced. A basic proton acceleration mechanism called TNSA will be introduced with supplemental free plasma expansion model. To investigate proton acceleration at the Texas Petawatt Facility, the experimental set up and target alignmen will be introduced in the chapter 5. While the analysis of data acquired from this experiment is still unfinished, a brief result with RCF image will be introduced in chapter 6. / text
232

Regents football : this is war

Neill, Cooper Hampton 15 April 2013 (has links)
After winning the TAPPS Division III State Championship in 2010, the Regents School of Austin Knights set out to defend their title as the top high school football team in their division. After losing their star players from the year before, dealing with injuries and personal struggles throughout the season the Knights responded and made it to the state title game only to lose to Bullard Brook Hill. / text
233

Effects of limestone fines on performance of concrete

Mckinley, Max., 麥兒. January 2013 (has links)
The production of high-performance concrete having all-rounded high performance has been promoted for the last few decades. Meanwhile, environmental concerns have quested for minimizing cement consumption to reduce carbon footprint. However, contradictory requirements are often imposed on the mix parameters in order to satisfy all the required performance attributes and environmental limitations. The addition of inert fillers such as limestone fines (LF) is a promising way to overcome these difficulties. In this thesis, the packing density and overall performance of mortar and concrete containing different amounts of LF are investigated. The test results revealed that blending of fine aggregate with LF or with both LF and cement could significantly increase the packing density because the LF and cement particles are much smaller than the aggregate particles and are thus able to fill into the voids between the aggregate particles. However, LF with similar fineness as cement has no filling effect for increasing the packing density when added to cement to a mortar mix in which the powder content is already enough to fill the voids between aggregate particles. Its filling effect is contributed mainly by filling into the paste to increase the paste volume. In fact, the addition of LF to mortar would slightly decrease the packing density, significantly decrease the water film thickness (WFT) and significantly increase the paste film thickness (PFT). The actual effects of LF volume on the packing density, WFT and PFT are dependent on the cement paste volume. In-depth analysis of the test results showed that the apparently complicated effects of the LF volume are caused by the corresponding changes in the WFT and PFT of the mortar. The overall effects of LF are dependent on the net outcome of the decrease in WFT and the increase in PFT due to the addition of LF. The addition of LF would increase the flow spread when the WFT is relatively large as the decrease in WFT has smaller effect than the increase in PFT, increase the cohesiveness when the LF volume is relatively small as the decrease in WFT has greater effect and increase the early strength provided the WFT would not become too small. However, the addition of LF would always decrease the flow rate because the decrease in WFT always has greater effect than the increase in PFT. Finally, the possible use of LF as cement paste replacement to reduce cement paste volume is studied. From the correlation of the ultimate shrinkage strain to the cement paste volume and W/C ratio, and to the concrete strength and cement paste volume, it may be concluded that cement paste replacement by the addition of LF would reduce the shrinkage of concrete by both decreasing the cement paste volume and increasing the concrete strength. Moreover, since the reduction in cement paste volume would allow less cement to be used, this would also lead to the production of concrete more ecological. More research on this possible usage of various inert fillers with different fineness is recommended. / published_or_final_version / Civil Engineering / Master / Master of Philosophy
234

Development of a sonar system to assist firefighter navigation in low-visibility high temperature environments.

Abbasi, Mustafa Zafar 24 February 2015 (has links)
Firefighters routinely have to go through buildings with reduced visibility due to smoke. Moving through even the simplest apartment building can become a perilous task when you remove visual sensing, and introduce fires, toxic gasses and extremely high temperatures. While a number of tools, both low and high tech, exist to aid firefighters, none of them are perfectly able to solve this problem. This thesis proposes using sonar to supplement those tools, and documents the development of a flame-penetrating sonar. To the authors knowledge, no previous effort has been made to develop sonar for firefighting applications. Traditional ultrasonic range finders were found unable to penetrate flames, and thus a pulse-compression based sonar is presented here. A prototype sonar is developed to allow experimental testing of this technique. A number of experiments were conducted to understand the limitations of this device. This sonar was able to overcome the scattering of the flame, and even detect the extents of the flame. A number of applications of this technology can be imagined other than assisting firefighters. Military personnel, or anyone else needing to navigate obscured environments could use this technology. Other applications could be two-dimensional and three-dimensional temperature field reconstruction for industrial applications. The author believes combination sensors using sonar, thermal-imaging, global positioning system, dead reckoning, etc, are the only way to solve the problem of firefighter navigation. / text
235

The effects of marginal pyridoxine deficiency and high protein intakes on vitamin b6 status and enzymes in intermediary metabolism in rats

Raposo_Blouw, Sara 26 August 2015 (has links)
Pyridoxal-5-phosphate (PLP), the active form of vitamin B6 (B6), is a co-factor for enzymes in macronutrient metabolism. Increasing protein intake may affect B6 by increasing PLP-dependent enzymes in amino acid metabolism, which may be more pronounced during moderate B6 deficiency. Decreased B6 status decreases PLP-dependent enzyme activity possibly altering macronutrient metabolism. We examined changing dietary carbohydrate: protein ratios in rats consuming recommended vs. moderately deficient intakes of pyridoxine (PN)-HCl, on plasma markers of B6 status and enzymes in intermediary metabolism. Marginal B6 deficiency decreased all plasma B6 vitamers except for pyridoxic acid. Protein intake (40% energy) significantly reduced plasma PN and tended to decrease plasma pyridoxal with no significant alterations in plasma homocysteine or cysteine. Hepatic cystathionine-γ-lyase, glycogen phosphorylase, plasma aspartate and alanine aminotransferase significantly decreased with marginal B6 deficiency and cystathionine-γ-lyase decreased with increasing protein intake. Marginal B6 deficiency significantly increased hepatic glycogen with no changes in plasma haptoglobin. / October 2015
236

Comparing the effects of three exercise intensities on the prevention of hypoglycemia in people with type 1 diabetes

Rempel, Meaghan 01 September 2015 (has links)
The appropriate intensity of exercise needed to reduce the risk of hypoglycemia (≤3.9 mmol/L) in persons with type 1 diabetes (T1D) is not known. Ten participants with T1D performed four exercise sessions on a treadmill lasting 45 minutes: a control condition at 45-55% of heart rate reserve and three high intensity sessions at 70, 80, and 90% of heart rate reserve. A blinded continuous glucose monitor was used to measure time spent ≤3.9 mmol/L and glucose variability in the 12 hours following exercise. There were no significant changes in the percentage of time spent ≤3.9 mmol/L (p=0.58) and glucose variability as measured by mean absolute glucose change (p=0.53) and continuous overall net glycemic action (CONGA1: p=0.95; CONGA2: p=0.90; CONGA4: p=0.72) between the sessions. High intensity exercise at 70, 80, and 90% of HRR does not significantly reduce the amount of time spent ≤3.9 mmol/L or glucose variability compared to the 45-55% session alone. / October 2015
237

Extending the pump energy range for a pump-probe system using High Harmonics Generation

FLE, Guillaume January 2015 (has links)
No description available.
238

A Search for Z' Gauge Bosons Decaying to Tau-Antitau Pairs in Proton-Proton Collisions with the ATLAS Detector

Leister, Andrew Gerard 08 August 2015 (has links)
<p>Many Beyond-the-Standard-Model theories predict the existence of one or more additional neutral gauge bosons, or <i>Z'</i> bosons, with masses at the TeV scale or higher. A search for resonances of <i>Z'</i> bosons decaying to &tau;<sup>+</sup> &tau;<sup>-</sup> pairs in [special characters omitted]<i>s</i> = 8 TeV <i>pp</i> collisions from the LHC is presented. The data was collected by the ATLAS detector and corresponds to an integrated luminosity of 19.5-20.3 fb<sup>-1</sup>. The search is performed in ditau decay channels in which at least one tau decays hadronically. In each channel, the numbers of ditau events in high-mass regions of data are counted and compared to the expected numbers from Standard Model backgrounds and <i>Z'</i> signals. No statistically significant excess above the Standard Model expectation is observed in any channel. Bayesian 95% credibility upper limits are placed on the <i>Z'</i> production cross section times <i>Z'</i> &rarr; &tau;&tau; branching ratio as functions of the <i>Z'</i> resonance mass for each channel and for a combination of the channels. Sequential Standard Model <i>Z'</i> bosons with masses below 2.02 TeV are excluded at 95% credibility. The impacts on the cross section limits from varying the <i>Z<sub>ssM</sub></i> decay width and couplings to fermions are evaluated. Limits are also placed on the cross section times branching ratio of Non-Universal <i>G</i>(221) <i> Z'</i> bosons with enhanced couplings to third-generation fermions. These are evaluated as functions of the <i>Z'<sub>NU</sub></i> mass and another free parameter. <i>Z'<sub>Nu</sub></i> bosons with masses below 1.3-2.1 TeV are excluded at 95% credibility.</p>
239

Fabrictions and microstructure analyses of melt-textured YBCO superconductors using a simple tube furnace

周春臨, Chow, Chun-lam, James. January 1995 (has links)
published_or_final_version / Electrical and Electronic Engineering / Doctoral / Doctor of Philosophy
240

xy Position Reconstruction in DarkSide-50

Brodsky, Jason Philip 24 October 2015 (has links)
<p> The DarkSide-50 experiment seeks to directly detect dark matter in a liquid argon time projection chamber. In this dissertation, I present an algorithm of my design that determines the position of particle interactions with the liquid argon. This position reconstruction algorithm will be used by DarkSide-50 to reject backgrounds, particularly backgrounds from radioactive elements on the detector surface.</p><p> The position reconstruction algorithm functions by constructing light response functions (LRFs) that map locations in the detector to the expected distribution of signal in DarkSide-50's 38 photomultiplier tubes. Accurate LRFs cannot be produced by simulations of DarkSide-50's optics because such simulations are known to be flawed. Instead, this algorithm constructs LRFs using an iterative process driven by data. Initial, flawed LRFs are produced using simulated events but then used to produce new LRFs from data events. Multiple generations of LRFs are created from data with each generation driven to better satisfy a known feature of the detector: the dominant argon-39 background is uniformly distributed.</p><p> I also discuss a method of discriminating against surface background as an alternative to the common approach of fiducialization. This method considers the difference in goodness-of-fit between the best-fit reconstructed position and the best-fit position at the detector's surface.</p><p> I conclude by presenting results on the performance and validity of this algorithm, including some discussion of reconstruction errors. </p>

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