Browsing by Subject "Fusion"

The discovery of the Higgs boson in 2012 provided confirmation of the

proposed mechanism for preserving the electroweak $SU(2) \times U(1)$

gauge symmetry of the Standard Model of particle physics. It also

heralded in a new era of precision Higgs physics. This thesis presents a

measurement of the rate at which the Higgs boson is produced by vector

boson fusion in the $WW^{(\ast)}\rightarrow\,\ell\nu\ell\nu$ decay channel. With gauge boson couplings

in both the production and decay vertices, a VBF measurement in this

channel is a powerful probe of the $VVH$ vertex strength. Using

$4.5$~fb$^{-1}$ and $20.3$~fb$^{-1}$ of $pp$ collision data collected

at respective center-of-mass energies of 7 and $8 \tev$ in the ATLAS

detector, measurements of the statistical significance and the signal

strength are carried out in the Higgs mass range $100 \leq m_H \leq

200 \gev$. These measurements are enhanced with a boosted decision

tree that exploits the correlations between eight kinematic inputs in

order to separate signal and background processes. At the benchmark

Higgs mass of $125.36 \gev$, the significance of the data assuming the

background-only hypothesis to be true has been observed to be

$3.2\sigma$ ($2.7\sigma$ expected), constituting evidence of VBF Higgs boson

production. The measured signal strength (ratio of observed cross section times

branching ratio to that predicted by the SM) is

$1.27^{+0.53}_{-0.45}$. The inclusive cross section times

branching ratio is found to be $0.51^{+0.22}_{-0.17}$~pb at $\sqrts =

8 \tev$, consistent with the SM prediction of $0.34$~pb. No

significant deviations from the SM predictions for VBF Higgs boson

production are observed.

Miles Davis, never one for self-effacing humility, took his boasting to new heights when he proclaimed in a Rolling Stone interview from December 1969, "I could put together the greatest rock and roll band you ever heard." Most critics agree that A Tribute to Jack Johnson, recorded between February and April of 1970, was his attempt to do just that. The album featured an ensemble that was closer to a rock power trio than a jazz quintet, musicians who were as schooled in rock and R&B as in jazz, and a prominent use of emerging instrument and studio technologies previously unheard in Davis's music. In highlighting these stylistic markers, A Tribute to Jack Johnson made definitive the musical transition that Davis's immediately preceding works had set in motion.

Though few fans of the era would have been surprised by Davis's invocation of the value-laden vocabulary of "greatness" in describing his music, many were taken aback by his desire to associate with rock and roll. For a musician trained in the jazz tradition and revered as a master of the genre, the intentional incorporation of influences from popular music was viewed by many jazz listeners as nothing short of heretical. What did it mean, then, for Davis to make such a claim - and such an album - at the particular time that he did?

To address these two questions, I investigate in my dissertation the production, circulation, and reception of both the stand-alone album A Tribute to Jack Johnson and the documentary film for which parts of the album were initially the soundtrack. Combining my training in music with scholarly perspectives on identity politics, technology studies, film studies, and African American social and political history, I demonstrate how this recording comprises both a signal incursion into accepted jazz practice, and a unique window onto vital debates around jazz, popular culture, and identity constructions in the U.S. in the early 1970s. This dissertation thereby offers one approach for continuing the critical re-evaluation of fusion jazz that has prominently been in progress since the late 1990s.

Spinal fusion is quickly becoming a common surgical operation in today's medical field. A major component of spinal fusion surgery is the use of metal rods. These rods, which are made of titanium or stainless steel, must be bent in such a way to hold the spine in the correct configuration. This part of the surgery is very time consuming and tiring for the surgeon, which increases the risk to the patient. A device is being designed that would automatically bend the rods to match a flexible pattern formed by the surgeon. A major consideration in the design of this device is predicting the amount of springback exhibited by the rod when bent. This thesis discusses a method of determining that springback. First, an experimental setup is designed and used to bend surrogate rods to certain angles. This experimental data is compared to a numerical simulation of the bending. The material model in the simulation uses a stress-strain curve derived from tensile test data. It was found that at bend angles less than 60 degrees, the simulation results are accurate enough to predict springback. Therefore, a curve was fit to the data, and the resulting polynomial equation was used to solve for the bend angle to which the rod would need to be bent in order to obtain a desired angle. However, the simulation became inaccurate at higher bend angles. It was found that a mesh finer than that which was used for the simulation resulted in better agreement with the experimental values. In conclusion, it was shown that a numerical simulation could be used to produce accurate springback values in order to develop a prediction algorithm for a rod bending device.

Fusion reactors have often been hailed as the holy grail of clean energy generation, though a power-generating reactor has never been built due to a multitude of limiting factors. One such factor is the immense 12-15 MW/m2 heat fluxes experienced by the inner wall of the reactor. Multiple groups have proposed the use of tungsten swirl tubes to withstand the heat generated within the reactor core. The primary focus of this investigation is to parameterize this ‘first wall’ interior structure to determine the highest achievable heat transfer coefficient given the many tungsten configurations enabled via additive manufacturing. Two general tube structures were considered: an orthogonal three-dimensional mesh of various diameters and spacings, as well as a swirl tube geometry with varying ‘tape’ thicknesses. The coolant liquid proposed is FLiBe (2LiF-BeF2) due to its high specific heat capacity as well as its ability to breed tritium, the fuel for the reactor.

This was accomplished using theoretical calculations; computational fluid dynamics and conjugate heat transfer simulations in ANSYS Workbench; as well as an experimental setup to confirm tube pressure drop along the pipe. It was determined that heat transfer coefficients between upwards of 60,000 W/m2K were readily achievable, keeping the first wall temperature around 1300 K. A multitude of designs proved to be feasible given the pumping power restrictions, though the suggested design going forward is a swirl tube with 2 mm ‘tape’ thickness and 3 m/s inlet velocity. Simulated pressure drop with water was accurate to within 30% of experimentally measured values, giving confidence in the credibility of the results.