4,171 research outputs found
System data communication structures for active-control transport aircraft, volume 2
The application of communication structures to advanced transport aircraft are addressed. First, a set of avionic functional requirements is established, and a baseline set of avionics equipment is defined that will meet the requirements. Three alternative configurations for this equipment are then identified that represent the evolution toward more dispersed systems. Candidate communication structures are proposed for each system configuration, and these are compared using trade off analyses; these analyses emphasize reliability but also address complexity. Multiplex buses are recognized as the likely near term choice with mesh networks being desirable for advanced, highly dispersed systems
System data communication structures for active-control transport aircraft, volume 1
Candidate data communication techniques are identified, including dedicated links, local buses, broadcast buses, multiplex buses, and mesh networks. The design methodology for mesh networks is then discussed, including network topology and node architecture. Several concepts of power distribution are reviewed, including current limiting and mesh networks for power. The technology issues of packaging, transmission media, and lightning are addressed, and, finally, the analysis tools developed to aid in the communication design process are described. There are special tools to analyze the reliability and connectivity of networks and more general reliability analysis tools for all types of systems
Solubilization method for isolation of photosynthetic mega- And super-complexes from conifer thylakoids
Photosynthesis is the main process by which sunlight is harvested and converted into chemical energy and has been a focal point of fundamental research in plant biology for decades. In higher plants, the process takes place in the thylakoid membranes where the two photosystems (PSI and PSII) are located. In the past few decades, the evolution of biophysical and biochemical techniques allowed detailed studies of the thylakoid organization and the interaction between protein complexes and cofactors. These studies have mainly focused on model plants, such as Arabidopsis, pea, spinach, and tobacco, which are grown in climate chambers even though significant differences between indoor and outdoor growth conditions are present. In this manuscript, we present a new mild-solubilization procedure for use with “fragile” samples such as thylakoids from conifers growing outdoors. Here, the solubilization protocol is optimized with two detergents in two species, namely Norway spruce (Picea abies) and Scots pine (Pinus sylvestris). We have optimized the isolation and characterization of PSI and PSII multimeric mega- and super-complexes in a close-to-native condition by Blue-Native gel electrophoresis. Eventually, our protocol will not only help in the characterization of photosynthetic complexes from conifers but also in understanding winter adaptation
Beam instrumentation for the Tevatron Collider
The Tevatron in Collider Run II (2001-present) is operating with six times
more bunches and many times higher beam intensities and luminosities than in
Run I (1992-1995). Beam diagnostics were crucial for the machine start-up and
the never-ending luminosity upgrade campaign. We present the overall picture of
the Tevatron diagnostics development for Run II, outline machine needs for new
instrumentation, present several notable examples that led to Tevatron
performance improvements, and discuss the lessons for future colliders
Ion counting efficiencies at the IGISOL facility
At the IGISOL-JYFLTRAP facility, fission mass yields can be studied at high
precision. Fission fragments from a U target are passing through a Ni foil and
entering a gas filled chamber. The collected fragments are guided through a
mass separator to a Penning trap where their masses are identified. This
simulation work focuses on how different fission fragment properties (mass,
charge and energy) affect the stopping efficiency in the gas cell. In addition,
different experimental parameters are varied (e. g. U and Ni thickness and He
gas pressure) to study their impact on the stopping efficiency. The simulations
were performed using the Geant4 package and the SRIM code. The main results
suggest a small variation in the stopping efficiency as a function of mass,
charge and kinetic energy. It is predicted that heavy fragments are stopped
about 9% less efficiently than the light fragments. However it was found that
the properties of the U, Ni and the He gas influences this behavior. Hence it
could be possible to optimize the efficiency.Comment: 52 pages, 44 figure
Parametrization of the Driven Betatron Oscillation
An AC dipole is a magnet which produces a sinusoidally oscillating dipole
field and excites coherent transverse beam motion in a synchrotron. By
observing this coherent motion, the optical parameters can be directly measured
at the beam position monitor locations. The driven oscillation induced by an AC
dipole will generate a phase space ellipse which differs from that of the free
oscillation. If not properly accounted for, this difference can lead to a
misinterpretation of the actual optical parameters, for instance, of 6% or more
in the cases of the Tevatron, RHIC, or LHC. The effect of an AC dipole on the
linear optics parameters is identical to that of a thin lens quadrupole. By
introducing a new amplitude function to describe this new phase space ellipse,
the motion produced by an AC dipole becomes easier to interpret. Beam position
data taken under the influence of an AC dipole, with this new interpretation in
mind, can lead to more precise measurements of the normal Courant-Snyder
parameters. This new parameterization of the driven motion is presented and is
used to interpret data taken in the FNAL Tevatron using an AC dipole.Comment: 8 pages, 8 figures, and 1 tabl
Compressed Data Structures for Dynamic Sequences
We consider the problem of storing a dynamic string over an alphabet
in compressed form. Our representation
supports insertions and deletions of symbols and answers three fundamental
queries: returns the -th symbol in ,
counts how many times a symbol occurs among the
first positions in , and finds the position
where a symbol occurs for the -th time. We present the first
fully-dynamic data structure for arbitrarily large alphabets that achieves
optimal query times for all three operations and supports updates with
worst-case time guarantees. Ours is also the first fully-dynamic data structure
that needs only bits, where is the -th order
entropy and is the string length. Moreover our representation supports
extraction of a substring in optimal time
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