10,518 research outputs found
Deep gamma ray penetration in thick shields
Appropriate importance function and sampling scheme facilitates the application of the Monte Carlo method to problems involving the deep penetration of radiation
Electromagnetic Imaging with Atomic Magnetometers: A Novel Approach to Security and Surveillance
We describe our research programme on the use of atomic magnetometers to
detect conductive objects via electromagnetic induction. The extreme
sensitivity of atomic magnetometers at low frequencies, up to seven orders of
magnitude higher than a coil-based system, permits deep penetration through
different media and barriers, and in various operative environments. This
eliminates the limitations usually associated with electromagnetic detection.Comment: 5 pages, 5 figure
Verification of the electromagnetic deep-penetration effect in the real world
The deep penetration of electromagnetic waves into lossy media can be obtained by properly generating inhomogeneous waves. In this work, for the very first time, we demonstrate the physical implementation and the practical relevance of this phenomenon. A thorough numerical investigation of the deep-penetration effects has been performed by designing and comparing three distinct practical radiators, emitting either homogeneous or inhomogeneous waves. As concerns the latter kind, a typical Menzel microstrip antenna is first used to radiate improper leaky waves. Then, a completely new approach based on an optimized 3-D horn TEM antenna applied to a lossy prism is described, which may find applications even at optical frequencies. The effectiveness of the proposed radiators is measured using different algorithms to consider distinct aspects of the propagation in lossy media. We finally demonstrate that the deep penetration is possible, by extending the ideal and theoretical evidence to practical relevance, and discuss both achievements and limits obtained through numerical simulations on the designed antennas
Quark Gluon Plasma - Recent Advances
While heavy ion collisions at the SPS have produced excited strongly
interacting matter near the conditions for quark deconfinement, the RHIC may be
the first machine capable of creating quark-antiquark plasmas sufficiently
long-lived to allow deep penetration into the new phase. A comprehensive
experimental program addressing this exciting physics has been put into place.
Presented here are preliminary results from Au+Au at = 130 GeV
obtained during the first RHIC run and some CERN SPS results from Pb+Pb at
= 17 GeV (particularly relevant to QGP search).Comment: 15 pages, 19 figure
Distinct expressions of the BSR using various frequencies offshore Uruguay and its correspondence with the gas hydrate stability zone
At the Uruguayan continental margin, seismic evidence for the occurrence of gas hydrate has been identified based on the presence of BSRs in densely spaced 2D reflection seismic sections from different surveys. Mapping of BSRs based on 2D seismic data acquired in 2007 and 2008 suggested the presence of gas hydrates in areas that were not previously identified; hence hydrate occurrence offshore Uruguay is more widespread than previously thought. Recently ANCAP has digitized offshore seismic data acquired between 1970 and 1982. Being able to work on this data using interpretation software, and integrating results with the latest interpretations performed on the seismic collected in 2007 and 2008, the BSR extends over an area of approximately 25.000 km2. It is present in water depths greater than 500 m and has high continuity in Pelotas Basin but is more discontinuous at Punta del Este Basin and southern part of Oriental del Plata Basin.
In offshore basins around the world the base of GHSZ can have different seismic expressions such as continuous, segmented, and high-relief BSRs depending on the stratigraphic, fluid and geothermal setting. Here, we present examples of the influence of the acquisition parameters on the acoustic expression of the BSR, comparing commercial seismic sections acquired for hydrocarbon exploration and high resolution seismic sections acquired during the R/V Meteor Cruise M49/2 in 2001 and R/V Meteor Cruise M78/3a (May - June 2009) using different sources and streamer system. For the different data sets the BSR presents differences regarding its continuity and amplitude strength. In high resolution seismic, enhanced amplitudes and phase reversals are observed for several reflectors while deep penetration seismic shows only one single continuous reflector.
This comparison may help to visualize the complexity of the free gas, gas hydrate and stratigraphic system behind the BSR, which is usually masked on low-frequency deep penetration seismic data
Anomalous Capacitive Sheath with Deep Radio Frequency Electric Field Penetration
A novel nonlinear effect of anomalously deep penetration of an external radio
frequency electric field into a plasma is discribed. A self-consistent kinetic
treatment reveals a transition region between the sheath and the plasma.
Because of the electron velocity modulation in the sheath, bunches in the
energetic electron density are formed in the transition region adjusted to the
sheath. The width of the region is of order , where V_{T} is the
electron thermal velocity, and is frequency of the electric field. The
presence of the electric field in the transition region results in a cooling of
the energetic electrons and an additional heating of the cold electrons in
comparison with the case when the transition region is neglected.Comment: 14,4 figure
Dedication: In Honor of Elvin R. Latty
The smart grid concept is the grid design philosophy that diversifies the powergrids and the electricity markets. However a deep penetration of \prosumers" and distributedgeneration in urban environments could lead to significant problems from an electromagneticcompatibility (EMC) viewpoint. Traditional classification methods, used for small isolated systems, are inadequate tools to investigate, improve and evaluate mitigation measures for largedistributed infrastructures such as a smart grid. Therefore, an alternative classification method,originally developed to investigate the vulnerability of large distributed systems from intentionalelectromagnetic interference (IEMI), is used here. The method is used to analyse the smart gridconcept to investigate if the smart grid is, from an EMC and IEMI viewpoint for a large distributed system, an improvement or deterioration compared to traditional power grids (and theaspects that is attached to them)QC 20131010</p
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