394 research outputs found
A Passive Probe for Subsurface Oceans and Liquid Water in Jupiter's Icy Moons
We describe an interferometric reflectometer method for passive detection of
subsurface oceans and liquid water in Jovian icy moons using Jupiter's
decametric radio emission (DAM). The DAM flux density exceeds 3,000 times the
galactic background in the neighborhood of the Jovian icy moons, providing a
signal that could be used for passive radio sounding. An instrument located
between the icy moon and Jupiter could sample the DAM emission along with its
echoes reflected in the ice layer of the target moon. Cross-correlating the
direct emission with the echoes would provide a measurement of the ice shell
thickness along with its dielectric properties. The interferometric
reflectometer provides a simple solution to sub-Jovian radio sounding of ice
shells that is complementary to ice penetrating radar measurements better
suited to measurements in the anti-Jovian hemisphere that shadows Jupiter's
strong decametric emission. The passive nature of this technique also serves as
risk reduction in case of radar transmitter failure. The interferometric
reflectometer could operate with electrically short antennas, thus extending
ice depth measurements to lower frequencies, and potentially providing a deeper
view into the ice shells of Jovian moons.Comment: Submitted to Icaru
Extensive CGMD Simulations of Atactic PS Providing Pseudo Experimental Data to Calibrate Nonlinear Inelastic Continuum Mechanical Constitutive Laws
In this contribution, we present a characterization methodology to obtain pseudo experimental deformation data from CG MD simulations of polymers as an inevitable prerequisite to choose and calibrate continuum mechanical constitutive laws. Without restriction of generality, we employ a well established CG model of atactic polystyrene as exemplary model system and simulate its mechanical behavior under various uniaxial tension and compression load cases. To demonstrate the applicability of the obtained data, we exemplarily calibrate a viscoelastic continuum mechanical constitutive law. We conclude our contribution by a thorough discussion of the findings obtained in the numerical pseudo experiments and give an outline of subsequent research activities. Thus, this work contributes to the field of multiscale simulation methods and adds a specific application to the body of knowledge of CG MD simulations
The mythos of dwelling : a settlement at Kalaupapa, Molokai
Thesis (M. Arch.)--Massachusetts Institute of Technology, Dept. of Architecture, 1989.Includes bibliographical references (p. 99-103).This thesis is the exploration of the physical and metaphorical potential of one of the most beautiful and poignant places in the world. It is Kalaupapa, a peninsula on the North Shore of Molokai, Hawaii, and the site of the infamous Leper colony run by Father Damien at the end of the last century. Here is explored the social issues of compassion to our fellow man and the importance of that compassion in reinforcing an emerging attitude towards life today. The issue of relevancy to this age i s further reinforced with the· analogy of people with leprosy to people with AIDS and the similar societal treatment they have each received. The physical manifestation of this social charge is a place - a settlement run by the National Park Service- where we learn about illness, about dealing with the metaphors attached to illness, about life and death. It is a place that must relate to the strength of the landscape and the technological constraints prescribed by the location. Here, the physical manifestation has the explicit charge of helping, rather than hindering, our ability to dwell. J?welling has been defined as the physical and existential participation in our life-world. We dwell by gathering a world to us, a world that reflects our underlying beliefs. These beliefs are myths and they are the basis for our lives and for the act of dwelling. I suspect that the myths of today do not allow us to fully participate in our world, but there is hope that a planetary myth is emerging that will make this participation possible. This project tries, with every ounce of strength, to help this myth emerge in the minds of the readers.by Paul R. Ries.M.Arch
Multi-messenger astronomy in the new physics modality with GPS constellation
We explore a novel, exotic physics, modality in multi-messenger astronomy. We
are interested in exotic fields emitted by the mergers and their direct
detection with a network of atomic clocks. We specifically focus on the
rubidium clocks onboard satellites of the Global Positioning System. Bursts of
exotic fields may be produced during the coalescence of black hole
singularities, releasing quantum gravity messengers. To be detectable such
fields must be ultralight and ultra-relativistic and we refer to them as exotic
low-mass fields (ELFs). Since such fields possess non-zero mass, the ELF bursts
lag behind the gravitational waves emitted by the very same merger. Then the
gravitational wave observatories provide a detection trigger for the atomic
clock networks searching for the feeble ELF signals. ELFs would imprint an
anti-chirp transient across the sensor network. ELFs can be detectable by
atomic clocks if they cause variations in fundamental constants. We report our
progress in the development of techniques to search for ELF bursts with clocks
onboard GPS satellites. We focus on the binary neutron star merger GW170817 of
August 17, 2017. We find an intriguing excess in the clock noise post LIGO
gravitational wave trigger. Potentially the excess noise could be explained
away by the increased solar electron flux post LIGO trigger.Comment: 9th Symposium on Frequency Standards and Metrolog
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City Park Visitation and Attitudes about Urban Forests: Exploring the Relationship
GRACE Measurements of Mass Variability in the Earth System
Monthly gravity field estimates made by the twin Gravity Recovery and Climate Experiment (GRACE) satellites have a geoid height accuracy of 2 to 3 millimeters at a spatial resolution as small as 400 kilometers. The annual cycle in the geoid variations, up to 10 millimeters in some regions, peaked predominantly in the spring and fall seasons. Geoid variations observed over South America that can be largely attributed to surface water and groundwater changes show a clear separation between the large Amazon watershed and the smaller watersheds to the north. Such observations will help hydrologists to connect processes at traditional length scales (tens of kilometers or less) to those at regional and global scales
The Hybrid Capriccio Method: A 1D Study for Further Advancement
Polymers and, in particular, polymer composites are known for the enormous adjustability of their mechanical, chemical, and thermal behavior. Multiscale methods are increasingly employed to unravel the polymer microstructure's impact on the material properties. These methods combine the accuracy of particle-based techniques with the efficiency of continuum mechanical approaches. Amorphous polymers pose a special challenge since their microstructure does not continue periodically, and therefore special attention needs to be paid to the particle domain boundary. In this study, we introduce a coupling via an interface between the continuum and the particle domain. Padding atoms as particle representations of the continuum, which serve as interaction partners for the atoms in the particle region, allow for the transfer of displacements and forces between the domains. We present a straightforward 1D example with simple interactions, evaluate the scheme's performance, discuss the resulting energy contributions, and identify an optimal set of coupling parameters. Eventually, this forms the basis for future 3D implementations
Dialogue Act Modeling for Automatic Tagging and Recognition of Conversational Speech
We describe a statistical approach for modeling dialogue acts in
conversational speech, i.e., speech-act-like units such as Statement, Question,
Backchannel, Agreement, Disagreement, and Apology. Our model detects and
predicts dialogue acts based on lexical, collocational, and prosodic cues, as
well as on the discourse coherence of the dialogue act sequence. The dialogue
model is based on treating the discourse structure of a conversation as a
hidden Markov model and the individual dialogue acts as observations emanating
from the model states. Constraints on the likely sequence of dialogue acts are
modeled via a dialogue act n-gram. The statistical dialogue grammar is combined
with word n-grams, decision trees, and neural networks modeling the
idiosyncratic lexical and prosodic manifestations of each dialogue act. We
develop a probabilistic integration of speech recognition with dialogue
modeling, to improve both speech recognition and dialogue act classification
accuracy. Models are trained and evaluated using a large hand-labeled database
of 1,155 conversations from the Switchboard corpus of spontaneous
human-to-human telephone speech. We achieved good dialogue act labeling
accuracy (65% based on errorful, automatically recognized words and prosody,
and 71% based on word transcripts, compared to a chance baseline accuracy of
35% and human accuracy of 84%) and a small reduction in word recognition error.Comment: 35 pages, 5 figures. Changes in copy editing (note title spelling
changed
A Collaborative Effort to Train Green Industry Professionals
A collaborative project between the Oregon State University Extension Service, and the green industry and allied professional organizations resulted in an educational seminar series for landscape professionals. In 2003 and 2004, the seminar series consisted of seven 3.5-hour sessions covering a range of horticultural topics and capitalized on expertise of extension personnel and green industry professionals. After the 2004 series, a survey was sent to all participants to determine attendance, overall evaluation, usefulness and applicability of information, participant learning, and behavior change as a result of the seminars. The response rate was 31%. Overall, participants gave the seminars a positive rating. A majority (83%) of respondents reported they had applied information learned at the seminar(s), and showed a significant increase in understanding of a subject as a result of participating in the seminar(s). Further, 98% of those who applied this information reported making multiple changes to their practices or recommendations to clients in the 6 months following the seminars
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