1,590 research outputs found

    Integration of CAD Tools and Structured Design Principles in an Undergraduate Computer Engineering Curriculum

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    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

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    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

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    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

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    We have measured the four IR active C60C_{60} molecular vibrations in MxC60M_{x}C_{60} (M=K,Rb)(M = K, Rb) as a function of doping xx. We observe discontinuous changes in the vibrational spectra showing four distinct phases (presumably x=0,3,4x = 0, 3, 4, and 6). The 1427cm11427cm^{-1} and 576cm1576cm^{-1} 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 x=6x=6 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 1427cm11427cm^{-1} 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

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    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

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    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

    "What was once rebellion is now clearly just a social sect": Identity, ideological conflict and the field of punk rock artistic production

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    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

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    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}

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    A numerical renormalization group technique recently developed by one of us is used to analyse the Coulomb pseudopotential (μ{\mu^*}) in C60{{\rm C}_{60}} for a variety of bare potentials. We find a large reduction in μ{\mu^*} due to intraball screening alone, leading to an interesting non-monotonic dependence of μ{\mu^*} on the bare interaction strength. We find that μ{\mu^*} 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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