10,590 research outputs found
Portable linear-focused solar thermal energy collecting system
A solar heat collection system is provided by utilizing a line-focusing device that is effectively a cylindrically curved concentrator within a protected environment formed by a transparent inflatable casing. A target, such as a fluid or gas carrying conduit is positioned within or near the casing containing the concentrator, at the line focus of the concentrator. The casing can be inflated at the site of use by a low pressure air supply to form a unitary light weight structure. The collector, including casing, concentrator and target, is readily transportable and can be used either at ground level or on rooftops. The inflatable concentrator can be replaced with a rigid metal or other concentrator while maintaining the novel advantages of the whole solar heat collection system
Three-dimensional tracking solar energy concentrator and method for making same
A three dimensional tracking solar energy concentrator, consisting of a stretched aluminized polymeric membrane supported by a hoop, was presented. The system is sturdy enough to withstand expected windage forces and precipitation. It can provide the high temperature output needed by central station power plants for power production in the multi-megawatt range
Strongly Coupled Plasmas via Rydberg-Blockade of Cold Atoms
We propose and analyze a new scheme to produce ultracold neutral plasmas deep
in the strongly coupled regime. The method exploits the interaction blockade
between cold atoms excited to high-lying Rydberg states and therefore does not
require substantial extensions of current ultracold plasma experiments.
Extensive simulations reveal a universal behavior of the resulting Coulomb
coupling parameter, providing a direct connection between the physics of
strongly correlated Rydberg gases and ultracold plasmas. The approach is shown
to reduce currently accessible temperatures by more than an order of magnitude,
which opens up a new regime for ultracold plasma research and cold ion-beam
applications with readily available experimental techniques.Comment: 5 pages, 5 figure
Charged Current Neutrino Nucleus Interactions at Intermediate Energies
We have developed a model to describe the interactions of neutrinos with
nucleons and nuclei, focusing on the region of the quasielastic and Delta(1232)
peaks. We describe neutrino nucleon collisions with a fully relativistic
formalism which incorporates state-of-the-art parametrizations of the form
factors for both the nucleon and the N-Delta transition. The model has then
been extended to finite nuclei, taking into account nuclear effects such as
Fermi motion, Pauli blocking (both within the local density approximation),
nuclear binding and final state interactions. The in-medium modification of the
Delta resonance due to Pauli blocking and collisional broadening have also been
included. Final state interactions are implemented by means of the
Boltzmann-Uehling-Uhlenbeck (BUU) coupled-channel transport model. Results for
charged current inclusive cross sections and exclusive channels as pion
production and nucleon knockout are presented and discussed.Comment: 26 pages, 24 figures; v2: 2 figures and discussion added, version
accepted for publication in Phys. Rev.
Reconciliation of object interaction models
This paper presents Reconciliation+, a
tool-supported method which identifies overlaps
between models of different object interactions
expressed as UML sequence and/or collaboration
diagrams, checks whether the overlapping elements
of these models satisfy specific consistency rules,
and guides developers in handling these
inconsistencies. The method also keeps track of the
decisions made and the actions taken in the process
of managing inconsistencies
Creating Non-Maxwellian Velocity Distributions in Ultracold Plasmas
We present techniques to perturb, measure and model the ion velocity
distribution in an ultracold neutral plasma produced by photoionization of
strontium atoms. By optical pumping with circularly polarized light we promote
ions with certain velocities to a different spin ground state, and probe the
resulting perturbed velocity distribution through laser-induced fluorescence
spectroscopy. We discuss various approaches to extract the velocity
distribution from our measured spectra, and assess their quality through
comparisons with molecular dynamic simulationsComment: 13 pages, 8 figure
Velocity Relaxation in a Strongly Coupled Plasma
Collisional relaxation of Coulomb systems is studied in the strongly coupled
regime. We use an optical pump-probe approach to manipulate and monitor the
dynamics of ions in an ultracold neutral plasma, which allows direct
measurement of relaxation rates in a regime where common Landau-Spitzer theory
breaks down. Numerical simulations confirm the experimental results and display
non-Markovian dynamics at early times.Comment: 5 pages, 5 figure
Interoperability and the Need for Intelligent Software: A Historical Perspective
With the objective of defining the interoperability theme of this year’s conference it is the purpose of this paper1 to trace the evolution of intelligent software from data-centric applications that essentially encapsulate their data environment to ontology-based applications with automated reasoning capabilities. The author draws a distinction between human intelligence and component capabilities within a more general definition of intelligence; - a kind of intelligence that can be embedded in computer software. The primary vehicle in the quest for intelligent software has been the gradual recognition of the central role played by data and information, rather than the logic and functionality of the application. The three milestones in this evolution have been: the separation of data management from the internal domain of the application; the development of standard data exchange protocols such as XML that allow machine interpretable structure and meaning to be added to data exchange packages; and, the ability to build information models that are rich in relationships and are thereby capable of supporting the automated reasoning capabilities of software agents.
The author suggests that the vision of a Semantic Web environment in which ontology-based Web services with intelligent capabilities are able to discover each other and individually or in self-configured groups perform useful tasks, is not only feasible but imminently realizable. The capabilities of an experimental proof-of-concept system featuring semantic Web services that was demonstrated during the 2002 meeting of this annual conference series is described in summary form
Transition From Data to Information
It is often lamented that we human beings are suffering from an information overload. This is a myth; as shown in Fig.1, there is no information overload. Instead, we are suffering from a data overload. The confusion between data and information is not readily apparent and requires further explanation. Unorganized data are voluminous but of very little value. Over the past 15 years, industry and commerce have made significant efforts to rearrange this unorganized data into purposeful data, utilizing various kinds of database management systems. However, even in this organized form, we are still dealing with data and not information
Reverse-Engineering the brain: The parts are as complex as the whole.
The purpose of this paper is to review the current state of neuroscience research with a focus on what has been achieved to date in unraveling the mysteries of brain operations, major research initiatives, fundamental challenges, and potentially realizable objectives. General research approaches aimed at constructing a wiring diagram of the brain (i.e., connectome), determining how the brain encodes and computes information, and whole brain simulation attempts are reviewed in terms of strategies employed and difficulties encountered. While promising advances have been made during the past 50 years due to electron microscopy, the development of new experimental methods, and the availability of computer-enabled high throughput imaging systems, brain research is still greatly encumbered by inadequate monitoring and recording capabilities. Four hypotheses relating to comprehension through the assembly of parts, formation of memories, influence of genes, and synapse formation are described as plausible explanations even though they cannot be validated at this time. By assessing the feasibility of overcoming the principal problems that beleaguer brain research in comparison with the potential benefits that can be derived from even partial achievement of the goals the author concludes that the significant investment of government funding is justified
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