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Your search keyword '"Petersen, Alex"' showing total 8 results
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8 results on '"Petersen, Alex"'

2. In protecting wild spaces, choose the right 30 percent

Author

Petersen, Alex

Subjects
General interest, News, opinion and commentary
Abstract

Byline: Alex Petersen Over the past four centuries, America has seen so much farming, logging, grazing and paving that we've reduced our wild spaces to a tiny fraction of their [...]

Published
2021

6. Critical analysis of lattice thermal conductivity of half-Heusler alloys using variations of Callaway model.

Author

Petersen, Alex, Bhattacharya, S., Tritt, T. M., and Poon, S. J.

Subjects
*HEUSLER alloys, *THERMAL conductivity, *ELECTRIC properties of solids, *PHONON scattering, *THERMOELECTRIC materials, *CRITICAL analysis
Abstract

Half-Heusler alloys have been the focus of recent experimental research as emerging thermoelectric materials. Particular attention has been focused on the MNiSn (M=Ti, Zr, and Hf) alloys with substitutions made to reduce the lattice thermal conductivity and enhance the electrical transport properties. The effect of these substitutions on the relaxation time of phonon scattering in the material, and the impact on the lattice thermal conductivity, was investigated with a focus on modeling the experimental data. A modified Callaway model was used to describe experimental data, which were then compared to theoretical results predicted using phonon scattering by mass fluctuation and strain field models. The correlation between the coefficients obtained with experimental fits and theoretical models shows a predictable and systematic relationship between alloy composition and the thermal conductivity. In addition, the role of the normal (N) phonon-phonon scattering process is investigated following a recent theoretical study that indicated that the effect of N-process was underestimated in original Callaway's model. A comparison of the lattice thermal conductivity behavior using the phonon relaxation times in the original Callaway's model and the newly suggested theoretical model by Allen for the normal process is presented and discussed. [ABSTRACT FROM AUTHOR]

Published
2015
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8. Work-in-Progress: Moving from volunteering to mentoring K12 students: What does it take?

Author

Whitman, Lawrence E., Petersen, Alex, and Wyant, Christopher D.

Subjects
*STEM education, *ENGINEERING students, *INFORMATION technology, *ENGINEERING education, *EDUCATIONAL technology, *TECHNOLOGY education, *ENGINEERING technology education
Abstract

Engaging minority and underrepresented students in STEM fields in high school is not difficult, but providing the student with long-term outlooks in STEM fields in which the students can see themselves is very difficult. Most students do not know anyone who is currently in a STEM career. STEM professionals volunteer at a good rate, but do not serve as mentors as frequently as those in other professions. A definite key to closing the STEM graduate gap is enabling youth to view themselves in a STEM career. Mentoring helps the student bridge the gap between where they are in high school and the where they see themselves in the future. The guidance provided by a mentor through a student's secondary academic career and transition into a post-secondary setting is critical to minority and underrepresented students due to the lack of this guidance in their social circle. High impact STEM mentoring is needed for mentors to have a lasting impact on our nation. This paper will focus on converting STEM professional volunteers into roles as mentors. This paper will describe efforts to increase the number of mentors in a mid-sized urban community. The paper will discuss the levels of commitment and the level of intensity of desired by the mentors. [ABSTRACT FROM AUTHOR]

Published
2015

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