9,548 research outputs found
Attitude control and damping system for spacecraft Patent
Utilization of momentum devices for forming attitude control and damping system for spacecraf
TRICCS: A proposed teleoperator/robot integrated command and control system for space applications
Robotic systems will play an increasingly important role in space operations. An integrated command and control system based on the requirements of space-related applications and incorporating features necessary for the evolution of advanced goal-directed robotic systems is described. These features include: interaction with a world model or domain knowledge base, sensor feedback, multiple-arm capability and concurrent operations. The system makes maximum use of manual interaction at all levels for debug, monitoring, and operational reliability. It is shown that the robotic command and control system may most advantageously be implemented as packages and tasks in Ada
Complex hyperbolic free groups with many parabolic elements
We consider in this work representations of the of the fundamental group of
the 3-punctured sphere in such that the boundary loops are
mapped to . We provide a system of coordinates on the
corresponding representation variety, and analyse more specifically those
representations corresponding to subgroups of -groups. In
particular we prove that it is possible to construct representations of the
free group of rank two \la a,b\ra in for which , ,
, , , and all are mapped to parabolics.Comment: 21 pages, 11 figure
Exploring the bulk of tidal charged micro-black holes
We study the bulk corresponding to tidal charged brane-world black holes. We
employ a propagating algorithm which makes use of the three-dimensional
multipole expansion and analytically yields the metric elements as functions of
the five-dimensional coordinates and of the ADM mass, tidal charge and brane
tension. Since the projected brane equations cannot determine how the charge
depends on the mass, our main purpose is to select the combinations of these
parameters for which black holes of microscopic size possess a regular bulk.
Our results could in particular be relevant for a better understanding of
TeV-scale black holes.Comment: Latex, 15 pages, 1 table, 5 figures; Section 3.2 extended, typos
corrected, no change in conclusion
The Newtonian limit at intermediate energies
We study the metric solutions for the gravitational equations in Modified
Gravity Models (MGMs). In models with negative powers of the scalar curvature,
we show that the Newtonian Limit (NL) is well defined as a limit at
intermediate energies, in contrast with the usual low energy interpretation.
Indeed, we show that the gravitational interaction is modified at low densities
or low curvatures.Comment: 4 pages, REVTeX 4; minor typos corrected, one reference adde
Tessie, You Are The Only, Only, Only
https://digitalcommons.library.umaine.edu/mmb-vp/6733/thumbnail.jp
A flexible telerobotic system for space operations
The objective and design of a proposed goal-oriented knowledge-based telerobotic system for space operations is described. This design effort encompasses the elements of the system executive and user interface and the distribution and general structure of the knowledge base, the displays, and the task sequencing. The objective of the design effort is to provide an expandable structure for a telerobotic system that provides cooperative interaction between the human operator and computer control. The initial phase of the implementation provides a rule-based, goal-oriented script generator to interface to the existing control modes of a telerobotic research system, in the Intelligent Systems Research Lab at NASA Research Center
Electrostatics in the Stability and Misfolding of the Prion Protein: Salt Bridges, Self-Energy, and Solvation
Using a recently developed mesoscopic theory of protein dielectrics, we have
calculated the salt bridge energies, total residue electrostatic potential
energies, and transfer energies into a low dielectric amyloid-like phase for 12
species and mutants of the prion protein. Salt bridges and self energies play
key roles in stabilizing secondary and tertiary structural elements of the
prion protein. The total electrostatic potential energy of each residue was
found to be invariably stabilizing. Residues frequently found to be mutated in
familial prion disease were among those with the largest electrostatic
energies. The large barrier to charged group desolvation imposes regional
constraints on involvement of the prion protein in an amyloid aggregate,
resulting in an electrostatic amyloid recruitment profile that favours regions
of sequence between alpha helix 1 and beta strand 2, the middles of helices 2
and 3, and the region N-terminal to alpha helix 1. We found that the
stabilization due to salt bridges is minimal among the proteins studied for
disease-susceptible human mutants of prion protein
Economic Impacts of Planned Transportation Investments in New Jersey
This report demonstrates that New Jersey's plans to invest in transportation infrastructure over the next decade will result in nearly 27,000 full-time jobs per year. It also shows that the state's transportation investments will generate economic impacts in the form of employment, income, gross domestic product, and state and local tax revenues. The report is the result of a joint study conducted by the Heldrich Center and the Center for Urban Policy Research at Rutgers University's Edward J. Bloustein School of Planning and Public Policy
Constraints on a New Post-General Relativity Cosmological Parameter
A new cosmological variable is introduced which characterizes the degree of
departure from Einstein's General Relativity (GR) with a cosmological constant.
The new parameter, \varpi, is the cosmological analog of \gamma, the
parametrized post-Newtonian variable which measures the amount of spacetime
curvature per unit mass. In the cosmological context, \varpi measures the
difference between the Newtonian and longitudinal potentials in response to the
same matter sources, as occurs in certain scalar-tensor theories of gravity.
Equivalently, \varpi measures the scalar shear fluctuation in a dark energy
component. In the context of a "vanilla" LCDM background cosmology, a non-zero
\varpi signals a departure from GR or a fluctuating cosmological constant.
Using a phenomenological model for the time evolution \varpi=\varpi_0
\rho_{DE}/\rho_{M} which depends on the ratio of energy density in the
cosmological constant to the matter density at each epoch, it is shown that the
observed cosmic microwave background (CMB) temperature anisotropies limit the
overall normalization constant to be -0.4 < \varpi_0 < 0.1 at the 95%
confidence level. Existing measurements of the cross-correlations of the CMB
with large-scale structure further limit \varpi_0 > -0.2 at the 95% CL. In the
future, integrated Sachs-Wolfe and weak lensing measurements can more tightly
constrain \varpi_0, providing a valuable clue to the nature of dark energy and
the validity of GR.Comment: 9 pages, 7 figures; added reference
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