Recommended Citation Mohapatra, Sucheta. "Development and quantitative assessment of a beam hardening correction model for preclinical micro-CT." MS his contributions of time, ideas, and funding to make my graduate study experience so productive and stimulating. accomplishments shall continue to inspire me towards my future goals. I owe a lot to all my friends and colleagues in Iowa City, who h...

The envelope oscillations of a cold-fluid corkscrewing elliptic beam in a uniformfocusing magnetic field are studied. In particular, by linearizing the generalized beam envelope equations, the eigenmodes of small-amplitude envelope oscillations are calculated for a cold-fluid corkscrewing elliptic beam oscillating about its equilibrium. All of the eigenmodes are shown to be stable. PACS: 29.27....

Crack propagation modeling in quasi-brittle materials such as concrete is essential for improving the reliability and load-bearing capacity assessment. Crack propagation explains many failure characteristics of concrete structures using the fracture mechanics approach. This approach could better explain the softening behavior of concrete structures. A great effort has been made in developing nu...

We show that the timing properties of a pulsed low-energy positron lifetime beam can be conveniently tested by an electron beam. We apply this method to study time resolution of the beam and electron scattering in a flat and a ’sawtooth’ shaped choppers. The results show that (i) time resolution of 160 ps is obtained, (ii) the scattering of the electrons and the secondary electron yield of the ...

We report an electronically switchable dielectric leaky wave antenna. The main beam angle can be electronically steered using p-i-n diodes. The diodes are used as switches to control the radiation from two sets of gratings with different periods, thereby switching the main beam angle. Beam steering is achieved at a single fixed frequency; no frequency sweeping is necessary. A microwave prototyp...

An analysis was carried out to determine whether concrete is a sustainable housing material. Sustainability generally means having no net negative impact on the environment, and this analysis compared the environmental impact of producing concrete and steel. To make this comparison, we first designed a simple reinforced concrete beam and a steel I-beam with the same moment capacity, and we then...

By employing a mixed SnO 2 + Sn source, we demonstrate suboxide molecular beam epitaxy (S-MBE) growth of phase-pure single-crystalline metastable (001) thin films on Y-stabilized ZrO substrates at rate ?1.0 nm/min without the need for additional oxygen. These grow epitaxially across wide substrate temperature range from 150 to 450 °C. Hence, present an alternative pathway overcome limitations h...

1 SUMMARY A mixed-mode delamination test procedure was developed combining double cantilever beam (DCB) mode I loading and end notch flexure (ENF) mode II loading on a split unidirectional laminate. By loading the specimen with a lever, a single applied load simultaneously produces mode I and mode II bending loads on the specimen. This mixed-mode bending (MMB) test was analyzed using both finit...

Initial operating experience witll the SLAC electronpositron storage ring SPEAR is described. A luminosity of 1.2 x 1031 cm-2 set-I has been achieved and two-beam interaction effects are described. A single-beam coherent instability, which can be suppressed either by control of the ring chromaticity or by feedback, has been observed. Current-dependent bunch lengthening and widening have been ob...

Two essential elements of a seeded FEL based on the echo-enabled harmonic generation (EEHG) are the undulator-modulators, in which a laser beam modulates the beam energy. We study how the interaction of electrons in these undulators changes the noise properties of the beam. This paper is based on the method of noise analysis developed in Ref. [1] and extends it for the case of EEHG. INTRODUCTIO...