1,804 research outputs found
Rubidium frequency standard test program for NAVSTAR GPS
Test data of the RFS Program in the Production phase and computer automation are presented, as an essential element in the evaluation of the RFS performance in a simulated spacecraft environment. Typical production test data will be discussed for stabilities from 1 to 100,000 seconds averaging time and simulated time error accumulation test. Also, design considerations in developing the RFS test systems for the acceptance test in production are discussed
Tribimaximal Neutrino Mixing and a Relation Between Neutrino- and Charged Lepton-Mass Spectra
Brannen has recently pointed out that the observed charged lepton masses
satisfy the relation m_e +m_\mu +m_\tau = {2/3}
(\sqrt{m_e}+\sqrt{m_\mu}+\sqrt{m_\tau})^2, while the observed neutrino masses
satisfy the relation m_{\nu 1} +m_{\nu 2} +m_{\nu 3} = {2/3} (-\sqrt{m_{\nu
1}}+\sqrt{m_{\nu 2}}+\sqrt{m_{\nu 3}})^2. It is discussed what neutrino Yukawa
interaction form is favorable if we take the fact pointed out by Brannen
seriously.Comment: 13 pages, presentation modifie
Contractor point of view for system development and test program
Industry's practice of testing space qualified hardware is examined. An overview of the Global Positioning System (GPS) Test Program is discussed from the component level to the sub-system compatibility tests with the space vehicle and finally to the launch site tests, all related to the Rubidium clock
A New Look at an Old Mass Relation
New data from neutrino oscillation experiments motivate us to extend a
successful mass relation for the charged leptons to the other fundamental
fermions. This new universal relation requires a Dirac mass around 3 10^-2 eV
for the lightest neutrino and rules out a maximal atmospheric mixing. It also
suggests a specific decomposition of the CKM mixing matrix.Comment: 8 pages, 2 figure
Projection Operator Approach to Langevin Equations in Theory
We apply the projection operator method (POM) to theory and derive
both quantum and semiclassical equations of motion for the soft modes. These
equations have no time-convolution integral term, in sharp contrast with other
well-known results obtained using the influence functional method (IFM) and the
closed time path method (CTP). However, except for the fluctuation force field
terms, these equations are similar to the corresponding equations obtained
using IFM with the linear harmonic approximation, which was introduced to
remove the time-convolution integral. The quantum equation of motion in POM can
be regarded as a kind of quantum Langevin equation in which the fluctuation
force field is given in terms of the operators of the hard modes. These
operators are then replaced with c-numbers using a certain procedure to obtain
a semiclassical Langevin equation. It is pointed out that there are significant
differences between the fluctuation force fields introduced in this paper and
those introduced in IFM. The arbitrariness of the definition of the fluctuation
force field in IFM is also discussed.Comment: 35pages,2figures, Prog. Theor. Phys. Vol. 107 No. 5 in pres
The structure of black hole magnetospheres. I. Schwarzschild black holes
We introduce a multipolar scheme for describing the structure of stationary,
axisymmetric, force-free black-hole magnetospheres in the ``3+1'' formalism. We
focus here on Schwarzschild spacetime, giving a complete classification of the
separable solutions of the stream equation. We show a transparent term-by-term
analogy of our solutions with the familiar multipoles of flat-space
electrodynamics. We discuss electrodynamic processes around disk-fed black
holes in which our solutions find natural applications: (a) ``interior''
solutions in studies of the Blandford-Znajek process of extracting the hole's
rotational energy, and of the formation of relativistic jets in active galactic
nuclei and ``microquasars'', and, (b) ``exterior'' solutions in studies of
accretion disk dynamos, disk-driven winds and jets. On the strength of existing
numerical studies, we argue that the poloidal field structures found here are
also expected to hold with good accuracy for rotating black holes, except for
maximum possible rotation rates. We show that the closed-loop exterior
solutions found here are not in contradiction with the Macdonald-Thorne
theorem, since these solutions, which diverge logarithmically on the hole's
horizon , apply only to those regions which exclude .Comment: 6 figures. Accepted for publication by MNRA
New Formulation of Causal Dissipative Hydrodynamics: Shock wave propagation
The first 3D calculation of shock wave propagation in a homogeneous QGP has
been performed within the new formulation of relativistic dissipative
hydrodynamics which preserves the causality. We found that the relaxation time
plays an important role and also affects the angle of Mach cone.Comment: 4 pages, 1 figure, Proceedings of Quark Matter 200
Hydrological modelling in representative catchments in Brazil using the SWAT model: the experience of the REHIDRO network.
Experimental and numerical studies in Experimental and Representative Basins are essential for water resources planning and for hydrological processes analysis due to land use changes and climate change scenarios. This work presents comparative analysis among diferente catchments in the Brazilian semiarid, and the Cerrado Biome. The Hydrological Network REHIDRO funded by the Brazilian Government (FINEP) has been focused on developing joint hydrological studies, involving the Federal Rural University of Pernambuco State (UFRPE), the Federal University of Pernambuco State (UFPE), the University of Brasília (UnB), and the Brazilian Corporation for Agricultural Research (EMBRAPA Cerrados). Numerical simulation analysis will be discussed, applying the SWAT model for three representative catchments: The Tapacurá Representative Catchment has been studied by UFPE. It is one of the main sub- catchments that supply the Recife Metropolitan Region, northeastern Brazil. The Tapacurá catchment covers an area of about 470 km2. Monitoring and modeling studies have been carried out on stream flow data from January 1997, using the data from a gauging station. The results show that the most sensitive hydrological parameters are the base flow, time of concentration and soil evaporation, which affect the catchment hydrology. The Ipanema catchment is part of the São Francisco River basin, and it is located in the Brazilian drought polygon. The São Francisco Basin has an area representing 8% of Brazilian territory. Na representative (Mimoso) catchment has been monitored as part of the network by the UFRPE, in the Pernambuco State. The study area of UnB research Group is part of the contribution área of the Descoberto reservoir. The Descoberto reservoir is responsible for 63% of the urban water supply of the Brazilian Federal District. The Descoberto reservoir basin has an area of about 420 km2 and the main tributary river has an area of about 114 km2. Flow, rainfall, sediments and nutrient loads has been collected at the main tributary rivers. Six sub-basins have been investigated and monitored, with areas ranging from 16 km2 to 114 km2. The Upper Jardim Experimental River Basin covers an area of about 105 km2, and is located in a rural zone of the Federal District, Brazil, in the core region of the Cerrado biome (Brazilian savanna). Since 2001, in order to generate a database to support hydrological studies in a typical rural catchment of the Brazilian savanna, EMBRAPA Cerrados (Savannas Agricultural Research Center), in partnership with the University of Brasilia (UNB), and other institutions, has intensively characterized and monitored this area. Comparative hydrology is discussed, mainly addressing SWAT parameters sensitivity analysis
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