13,753 research outputs found

    Thermal stress cycling of GaAs solar cells

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    Thermal stress cycling was performed on gallium arsenide solar cells to investigate their electrical, mechanical, and structural integrity. Cells were cycled under low Earth orbit (LEO) simulated temperature conditions in vacuum. Cell evaluations consisted of power output values, spectral response, optical microscopy and ion microprobe mass analysis, and depth profiles on both front surface inter-grid areas and metallization contact grid lines. Cells were examined for degradation after 500, 5,000, 10,000 and 15,245 thermal cycles. No indication of performance degradation was found for any vendor's cell lot

    Stress history of the Tharsis Region, Mars

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    The Tharsis topographic rise of Mars is roughly 5000 km wide and 10 km high and is believed to have originated more than 3.5 BY ago. Within its boundaries lie the four largest volcanoes on the planet. It is also the locus of a series of fracture traces which extend over approximately a hemisphere. The events leading to the formation of the Tharsis region continue to generate debate. Three geophysical models of the formation of Tharsis are now in general contention and each of these models has been used to predict a characteristic stress-field. These models are: the volcanic construct model, the isostatic compensation model, and the lithospheric uplift model. Each has been used by its proponents to predict some of the features observed in the Tharsis region but none accurately accounts for all of the fracture features observed. This is due, in part, to the use of fractures too young to be directly related to the origin of Tharsis. To constrain the origin of Tharsis, as opposed to its later history, one should look for the oldest fractures related to Tharsis and compare these to the predictions made by the models. Mapping of old terrains in and around the Tharsis rise has revealed 175 hitherto unknown old fracture features

    Multi-Stream Inflation in a Landscape

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    There are hidden observables for inflation, such as features localized in position space, which do not manifest themselves when only one inflation trajectory is considered. To address this issue, we investigate inflation dynamics in a landscape mimicked by a random potential. We calculate the probability for bifurcation of the inflation trajectory in multi-stream inflation. Depending on the shape of the random bumps and the distance between bumps in the potential, there is a phase transition: on one side of the critical curve in parameter space isocurvature fluctuation are exponentially amplified and bifurcation becomes very probable. On the other side bifurcation is dominated by a random walk where bifurcations are less likely to happen.Comment: Reference added to match published version in JCA

    Peer Mentors and Writing Center Tutors: What our collaborations taught us about serving the SJSU Freshmen Students

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    The Library Outpost, a satellite office of the campus’s Dr. Martin Luther King Jr. Library, seeks ways to reach out to First Year students who are new to writing research papers. One of our goals is to meet the First Year students on their own turf. Since the Peer Mentors and Writing Center tutors have peer relationships with the First year students, we want to learn how we can collaborate with them to provide services to the First year students. We surveyed the Peer Mentors and Writing Center Tutors to assess their perceptions of their own research skills, and their students’ research needs to guide the services and workshops offered by the Library Outpost
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