1,590 research outputs found
Integration of CAD Tools and Structured Design Principles in an Undergraduate Computer Engineering Curriculum
incorporating computer aided engineering and design (CAE/CAD) packages into undergraduate courses. The intent of augmenting the curriculum with these packages is to enhance the students theoretical understanding of the material with hands on design and analysis experience. The University of Arkansas i
Imaging Carrier Inhomogeneities in Ambipolar Tellurene Field Effect Transistors
Developing van der Waals (vdW) homojunction devices requires materials with
narrow bandgaps and simultaneously high hole and electron mobilities for
bipolar transport, as well as methods to image and study spatial variations in
carrier type and associated conductivity with nanometer spatial resolution.
Here we demonstrate the general capability of near-field scanning microwave
microscopy (SMM) to image and study the local carrier type and associated
conductivity in operando by studying ambiploar field effect transistors (FETs)
of the 1D vdW material tellurium in 2D form. To quantitatively understand
electronic variations across the device, we produce nanometer resolved maps of
the local carrier equivalence backgate voltage. We show that the global device
conductivity minimum determined from transport measurements does not arise from
uniform carrier neutrality, but rather from the continued coexistence of p-type
regions at the device edge and n-type regions in the interior of our
micron-scale devices. This work both underscores and addresses the need to
image and understand spatial variations in the electronic properties of
nanoscale devices.Comment: 15 pages, 4 figure
Gravity-Assist Mechanical Simulator for Outreach
There is no convenient way to demonstrate mechanically, as an outreach (or inreach) topic, the angular momentum trade-offs and the conservation of angular momentum associated with gravityassist interplanetary trajectories. The mechanical concepts that underlie gravity assist are often misunderstood or confused, possibly because there is no mechanical analog to it in everyday experience. The Gravity Assist Mech - anical Simulator is a hands-on solution to this longstanding technical communications challenge. Users intuitively grasp the concepts, meeting specific educational objectives. A manually spun wheel with high angular mass and low-friction bearings supplies momentum to an attached spherical neodymium magnet that represents a planet orbiting the Sun. A steel bearing ball following a trajectory across a glass plate above the wheel and magnet undergoes an elastic collision with the revolving magnet, illustrating the gravitational elastic collision between spacecraft and planet on a gravity-assist interplanetary trajectory. Manually supplying the angular momentum for the elastic collision, rather than observing an animation, intuitively conveys the concepts, meeting nine specific educational objectives. Many NASA and JPL interplanetary missions are enabled by the gravity-assist technique
In-Situ Infrared Transmission Study of Rb- and K-Doped Fullerenes
We have measured the four IR active molecular vibrations in
as a function of doping . We observe
discontinuous changes in the vibrational spectra showing four distinct phases
(presumably , and 6). The and modes
show the largest changes shifting downward in frequency in four steps as the
doping increases. Several new very weak modes are visible in the phase
and are possibly Raman modes becoming weakly optically active. We present
quantitative fits of the data and calculate the electron-phonon coupling of the
IR mode.Comment: 3 pages, Figure 1 included, 3 more figures available by request.
REVTEX v3.0 IRC60DO
Second SNPP Cal/Val Campaign: Environmental Data Retrieval Analysis
Satellite ultraspectral infrared sensors provide key data records essential for weather forecasting and climate change science. The Suomi National Polar-orbiting Partnership (Soumi NPP) satellite Environmental Data Records (EDRs) are retrieved from calibrated ultraspectral radiance or Sensor Data Records (SDRs). Understanding the accuracy of retrieved EDRs is critical. The second Suomi NPP Calibration/Validation field campaign was conducted during March 2015 with flights over Greenland. The NASA high-altitude ER-2 aircraft carrying ultraspectral interferometer sounders such as the National Airborne Sounder Testbed-Interferometer (NAST-I) flew under the Suomi NPP satellite that carries the Crosstrack Infrared Sounder (CrIS) and the Advanced Technology Microwave Sounder (ATMS). Herein we inter-compare the EDRs produced from different retrieval algorithms employed on these satellite and aircraft campaign data. The available radiosonde measurements together with the European Centre for Medium-Range Weather Forecasts (ECMWF) analyses are used to assess atmospheric temperature and moisture retrievals from the aircraft and satellite platforms. Preliminary results of this experiment under a winter, Arctic environment are presented
2003 Manifesto on the California Electricity Crisis
The authors, an ad-hocgroup of professionals with experience in regulatory and energy economics, share a common concern with the continuing turmoil facing the electricity industry ("the industry") in California. Most ofthe authorsendorsed the first California Electricity Manifesto issued on January 25, 2001. Almost two years have passed since that first Manifesto. While wholesale electric prices have moderated and California no longer faces the risk of blackouts, in many ways the industry is in worse shape now than it was at the start of 2001. As a result, the group of signatories continues to have a deep concern with the conflicting policy directions being pursued for the industry at both the State and Federal levels of government and the impact the uncertainties associated with these conflicting policies will have, long term, on the economy of California. Theauthorshave once again convened under the auspices of the Institute of Management, Innovation and Organization at the University of California, Berkeley, to put forward ourtheir ideas on a basic set of necessary policies to move the industry forward for the benefit of all Californians and the nation. The authors point out that theydo not pretend to be "representative." They do bring, however, a very diverse range of backgrounds and expertise.Technology and Industry, Regulatory Reform
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Characterization of the chemical signatures of air masses observed during the PEM experiments over the western Pacific
Extensive observations of tropospheric trace species during the second NASA Global Tropospheric Experiment Western Pacific Exploratory Mission (PEM-West B) in February-March 1994 showed significant seasonal variability in comparison with the first mission (PEM-West A), conducted in September-October 1991. In this study we adopt a previously established analytical method, i.e., the ratio C2H2/CO as a measure of the relative degree of atmospheric processing, to elucidate the key similarities and variations between the two missions. In addition, the C2H2/CO ratio scheme is combined with the back-trajectory-based and the LIDAR-based air mass classification schemes, respectively, to make in-depth analysis of the seasonal variation between PEM-West A and PEM-West B (hereinafter referred to as PEM-WA and PEM-WB). A large number of compounds, including long-lived NMHCs, CH4, and CO2, are, as expected, well correlated with the ratio C2H2/CO. In comparison with PEM-WA, a significantly larger range of observed C2H2/CO values at the high end for the PEM-WB period indicates that the western Pacific was more impacted by "fresher" source emissions, i.e., faster or more efficient continental outflow. As in the case of PEM-WA, the C2H2/CO scheme complements the back-trajectory air mass classification scheme very well. By combining the two schemes, we found that the atmospheric processing in the region is dominated by atmospheric mixing for the trace species analyzed. This PEM-WB wintertime result is similar to that found in PEM-WA for the autumn. In both cases, photochemical reactions are found to play a significant role in determining the background mixing ratios of trace gases, and in this way the two processes are directly related and dependent upon each other. This analysis also indicates that many of the upper tropospheric air masses encountered over the western Pacific during PEM-WB may have had little impact from eastern Asia's continental surface sources. NOx mixing ratios were significantly enhanced during PEM-WB when compared with PEM-WA, in the upper troposphere's more atmospherically processed air masses. These high levels of NOx resulted in a substantial amount of photochemical production of O3. A lack of corresponding enhancements in surface emission tracers strongly implies that in situ atmospheric sources such as lightning are responsible for the enhanced upper tropospheric NOx. The similarity in NOx values between the northern (higher air traffic) and southern continental air masses together with the indications of a large seasonal shift suggests that aircraft emissions are not the dominant source. However, photochemical recycling cannot be ruled out as this in situ source of NOx. Copyright 1999 by the American Geophysical Union
"What was once rebellion is now clearly just a social sect": Identity, ideological conflict and the field of punk rock artistic production
I advance a sociological reappraisal of the Western punk rock youth cultural artistic form. Contrasting prevalent perspectives correlating punk rock culture with adolescent rites of superficial social rebellion, I argue that the art form often exudes an underappreciated level of sophistication. I argue for the presence of two dominant strains of punk artistic logic, and demonstrate how each correspond with popular trends in neo-Marxist social theory. However, I also note that these competing logics promote contradictory forms of punk artistic conduct. Incorporating the perspectives of Pierre Bourdieu, I link this imperative for ideological division with the punk artists’ placement within fields of cultural production. Drawing from the artistry and testimonies of historically significant punk artists (and artistic consecrators), I argue that notable instances of punk ideological debate simultaneously function to allow punk artists to compete amongst one another for claims to artistic distinction and authority. I consider significant case studies wherein ideological debates double as tactics through which artists bolster their own claims to distinction in striving to delegitimize the authority of their ideological competitors. I question whether the primary function of ideological punk artistic debate stem from sincere ideological imperatives, or concerns surrounding the processes of accrediting individual claims to artistic legitimacy within the punk artistic field. Critically considering the interaction between collectivist punk artistic ideologies and the individualistic imperative of asserting personal claims to authoritative punk identity, I conclude that movements toward internal differentiation ultimately undermine punk rocks’ capacity to serve as a substantive counter-hegemonic artistic movement
"It's not a fashion statement, it's a death wish" : subcultural power dynamics, niche-media knowledge construction, and the 'emo kid' folk-devil
This thesis examines the genesis of the derogative ‘emo kid’ representation and considers the latent functions it initially served in being applied to visible categories of adolescent subculturalists on the behalf of participants within the wider punk subculture. Pulling from the work of Stanley Cohen in arguing that the ‘emo kid’ representation be conceptualized as a subcultural ‘folk-devil’, this thesis argues for the applicability of a Bourdieuian theoretical framework in understanding the means in which subcultural ‘authenticity’ is not only distributed throughout ‘fields’ of subcultural participation, but within those spheres of communicative entertainment media in which subcultural knowledge is created, legitimized and disseminated. In offering a Foucaultian genealogy of the niche-mediated ‘emo’ pseudo-genre, and highlighting its correlation with concurrent movements perceived as facilitating the mainstream colonization of the punk subculture, this thesis argues that the ‘emo kid’ folk-devil was constructed and reified by virtue of an array of discursive measures – based largely in online, ‘micro-mediated’ forums - through which punk subculturalists vied to marginalize those ‘emo kids’ so perceived as threatening the exclusivity of the punk subculture and the long-established ‘symbolic economies’ contained therein. Finally, this thesis demonstrates the process through which this subcultural folk-devil was annexed into a wider socio-discourse concerning dangerous youth populations and, thus, came to be utilized in collusion with mass-mediated campaigns meant to perpetuate the political disempowerment of adolescent populations through the endorsement of ‘representational politics’
Renormalization Group Approach to the Coulomb Pseudopotential for C_{60}
A numerical renormalization group technique recently developed by one of us
is used to analyse the Coulomb pseudopotential () in
for a variety of bare potentials. We find a large reduction in due to
intraball screening alone, leading to an interesting non-monotonic dependence
of on the bare interaction strength.
We find that is positive for physically reasonable bare parameters,
but small enough to make the electron-phonon coupling a viable mechanism for
superconductivity in alkali-doped fullerides. We end with some open problems.Comment: 12 pages, latex, 7 figures available from [email protected]
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