1,700 research outputs found
Air traffic control surveillance accuracy and update rate study
The results of an air traffic control surveillance accuracy and update rate study are presented. The objective of the study was to establish quantitative relationships between the surveillance accuracies, update rates, and the communication load associated with the tactical control of aircraft for conflict resolution. The relationships are established for typical types of aircraft, phases of flight, and types of airspace. Specific cases are analyzed to determine the surveillance accuracies and update rates required to prevent two aircraft from approaching each other too closely
The applications of satellites to communications, navigation and surveillance for aircraft operating over the contiguous United States. Volume 1 - Technical report
Satellite applications to aircraft communications, navigation, and surveillance over US including synthesized satellite network and aircraft equipment for air traffic contro
Coherent phenomena in mesoscopic systems
A mesoscopic system of cylindrical geometry made of a metal or a
semiconductor is shown to exhibit features of a quantum coherent state. It is
shown that magnetostatic interaction can play an important role in mesoscopic
systems leading to an ordered ground state. The temperature below the
system exhibits long-range order is determined. The self-consistent mean field
approximation of the magnetostatic interaction is performed giving the
effective Hamiltonian from which the self-sustaining currents can be obtained.
The relation of quantum coherent state in mesoscopic cylinders to other
coherent systems like superconductors is discussed.Comment: REVTeX, 4 figures, in print in Supercond. Sci. Techno
African Water: Supporting African involvement in the EU Framework Programme.
Water researchers in developing countries have yet to take full advantage of the funding and collaborative research opportunities presented by the EU Framework Programme. There are a variety of reasons for this, such as insufficient information and a lack of previous experience. The African Water initiative aims to increase the involvement of African water researchers through a range of activities including communication and dissemination, capacity building and development, and complementary initiatives. The project has demonstrated that there is a demand for such sector-specific support activities. However, African Water is a small component of a much larger process of partnership between the developed and the less-developed countries of the world, involving many different European and African organisations working across political, institutional and technical domains, and complementing the wide range of actions already being undertaken
Extraction of level density and gamma strength function from primary gamma spectra
We present a new iterative procedure to extract the level density and the
gamma strength function from primary gamma spectra for energies close up to the
neutron binding energy. The procedure is tested on simulated spectra and on
data from the Yb-173(He-3,alpha)Yb-172 reaction.Comment: 23 pages including 1 table and 7 figure
Flux qubit on mesoscopic nonsuperconducting ring
The possibility of making a flux qubit on nonsuperconducting mesoscopic
ballistic quasi 1D ring is discussed. We showed that such ring can be
effectively reduced to a two-state system with two external control parameters.
The two states carry opposite persistent currents and are coupled by tunneling
which leads to a quantum superposition of states. The qubit states can be
manipulated by resonant microwave pulses. The flux state of the sample can be
measured by a SQUID magnetometer. Two or more qubits can be coupled by the flux
the circulating currents generate. The problem of decoherence is also
discussed.Comment: Phys. Rev. B. (accepted
Possibility of long-range order in clean mesoscopic cylinders
A microscopic Hamiltonian of the magnetostatic interaction is discussed. This
long-range interaction can play an important role in mesoscopic systems leading
to an ordered ground state.
The self-consistent mean field approximation of the magnetostatic interaction
is performed to give an effective Hamiltonian from which the spontaneous,
self-sustaining currents can be obtained.
To go beyond the mean field approximation the mean square fluctuation of the
total momentum is calculated and its influence on self-sustaining currents in
mesoscopic cylinders with quasi-1D and quasi-2D conduction is considered. Then,
by the use of the microscopic Hamiltonian of the magnetostatic interaction for
a set of stacked rings, the problem of long-range order is discussed. The
temperature below which the system is in an ordered state is
determined.Comment: 14 pages, REVTeX, 5 figures, in print in Phys. Rev.
Entanglement of qubits via a nonlinear resonator
Coherent coupling of two qubits mediated by a nonlinear resonator is studied.
It is shown that the amount of entanglement accessible in the evolution depends
both on the strength of nonlinearity in the Hamiltonian of the resonator and on
the initial preparation of the system. The created entanglement survives in the
presence of decoherence.Comment: 6 pages, 10 figure
Medical Radioisotopes Produced with Cyclotron Beams in Warsaw
The various production routes of the prospective medical radioisotopes 43Sc, 44gSc, 44mSc, 47Sc,
44Ti/44gSc, 99mTc, 72Se/72As and 211At were investigated by a team from the Heavy Ion Laboratory,
University of Warsaw (HIL-UW), the University of Silesia (US) and the National Centre for
Nuclear Research (NCNR). Three cyclotrons were employed: the K=160 heavy-ion cyclotron with
an internal 32 MeV alpha particle beam and the p/d PETtrace medical cyclotron at HIL and the C30
proton cyclotron at NCNR in Świerk, near Warsaw. The Thick Target Yields, activity at the End of
Bombardment (EOB) and the impurities produced in addition to the main isotope are reported. The
possible medical applications of these radioisotopes are briefly discussed
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