Investigation of reliability attributes and accelerated stress factors on terrestrial solar cells

Major effort during this reporting period was devoted to two tasks: improvement of the electrical measurement instrumentation through the design and construction of a microcomputer controlled short interval tester, and better understanding of second quadrant behavior by developing a mathematical model relating cell temperature to electrical characteristics. In addition, some preliminary work is reported on an investigation into color changes observed after stressing

Rocket Fin Test Fixture Development & Exploration of Rotation Inducing Fin Design

The purpose of this senior project was to develop a method of applying rotation inducing rocket fin concepts to rockets for the benefit of the University of Akron Akronauts; the student led rocket design team. The project was performed independently of the team’s current efforts as a research and development endeavor for future team projects. Main project goals were divided into three parts: design a fin test fixture for verification testing in the University’s wind tunnel, develop a parameter-driven software model that could be used to generate design options with theoretical performance data as an output, and run fluid dynamics analyses to offer additional support to findings. At a higher level, this project was chosen as an opportunity to exercise a few of the many different facets of the engineering process. Over the course of the project, our team received valuable experience with: idea generation and brainstorming, concept vetting, technical software programming, process troubleshooting, rapid prototyping, and aerodynamic-related testing

Emotional expression during attention-deficit/hyperactivity disorders treatment: initial assessment of treatment effects.

OBJECTIVE: The purpose of this research was to provide an initial examination of the effects of atomoxetine and stimulants on emotional expression using a newly developed scale for assessing emotional expression in children with attention-deficit/hyperactivity disorder (ADHD). METHOD: The parent-rated Expression and Emotion Scale for Children (EESC) was collected during two studies. During a cross-sectional validation study, the EESC was completed to assess the child\u27s current treatment and retrospectively for previous medication. In a randomized, placebo-controlled trial of atomoxetine, the EESC was collected at baseline and endpoint. RESULTS: In the validation study, no statistically significant differences in EESC scores were found between groups taking atomoxetine (n = 74) and stimulants (n = 105). Patients who switched from a stimulant to atomoxetine (n = 40) had greater improvement in emotional expression than those switched to another stimulant (n = 21) (p = 0.008). In the clinical trial, no difference in rates of worsening of emotional expression were observed (atomoxetine 8.8%, placebo 12.3%; p = 0.440). CONCLUSION: No treatment differences in emotional expression were observed based on current medications. However, stimulant patients needing to switch medications may have greater improvements in emotional expression by switching to atomoxetine

Bond-disordered spin systems: Theory and application to doped high-Tc compounds

We examine the stability of magnetic order in a classical Heisenberg model with quenched random exchange couplings. This system represents the spin degrees of freedom in high-$T_\textrm{c}$ compounds with immobile dopants. Starting from a replica representation of the nonlinear $\sigma$-model, we perform a renormalization-group analysis. The importance of cumulants of the disorder distribution to arbitrarily high orders necessitates a functional renormalization scheme. From the renormalization flow equations we determine the magnetic correlation length numerically as a function of the impurity concentration and of temperature. From our analysis follows that two-dimensional layers can be magnetically ordered for arbitrarily strong but sufficiently diluted defects. We further consider the dimensional crossover in a stack of weakly coupled layers. The resulting phase diagram is compared with experimental data for La$_{2-x}$Sr$_x$CuO$_4$.Comment: 12 pages, 5 figure

Measurement of Unpolarized and Polarized Cross Sections for Deeply Virtual Compton Scattering on the Proton at Jefferson Laboratory with CLAS

This paper reports the measurement of polarized and unpolarized cross sections for the ep → e \u27p\u27 γ reaction, which is composed of deeply virtual Compton scattering (DVCS) and Bethe-Heitler (BH) processes, at an electron beam energy of 5.88 GeV at the Thomas Jefferson National Accelerator Facility using the Large Acceptance Spectrometer CLAS. The unpolarized cross sections and polarized cross section differences have been measured over broad kinematics, 0.10 2 \u3c 4.8 GeV2,and 0.09 \u3c −t\u3c 2.00 GeV2. The results are found to be consistent with previous CLAS data, and these new data are discussed in the framework of the generalized parton distribution approach. Calculations with two widely used phenomenological models are approximately compatible with the experimental results over a large portion of the kinematic range of the data

Boosted three-dimensional black-hole evolutions with singularity excision

Binary black hole interactions provide potentially the strongest source of gravitational radiation for detectors currently under development. We present some results from the Binary Black Hole Grand Challenge Alliance three- dimensional Cauchy evolution module. These constitute essential steps towards modeling such interactions and predicting gravitational radiation waveforms. We report on single black hole evolutions and the first successful demonstration of a black hole moving freely through a three-dimensional computational grid via a Cauchy evolution: a hole moving ~6M at 0.1c during a total evolution of duration ~60M