33,085 research outputs found
Science instrumentation package, LST
The projected design of an optical instrument package for the large space telescope includes: a diffraction limited camera; low- and high-dispersion spectrographs; astrometric machines; photometers; polarimeters; F/12 camera; Fourier interferometer; infrared instrumentation; and a very high dispersion spectrographs
The flight demonstration program and selection process
The Orbital Refueling System (ORS); force torque sensor; Plasma Motor/Generator (PMG) proof of function; voice controlled system; infrared intercommunications; superfluid helium on orbit transfer; laser docking sensor; and the Small Expendable Deployment System (SEDS) are summarized
Recommended from our members
Navigating the Turbulent Waters of School Reform Guided by Complexity Theory
The goal of this research study has been to develop, implement, and evaluate a school reform design experiment at a continuation high school with low-income, low-performing underrepresented minority students. The complexity sciences served as a theoretical framework for this design experiment. Treating an innovative college preparatory program as a nested complex adaptive system within a larger complex adaptive system, the school, we used features of complex adaptive systems (equilibrium, emergence, self-organization, and feedback loops) as a framework to design a strategy for school reform. The goal was to create an environment for change by pulling the school far from equilibrium using a strategy we call “purposeful perturbations” to disrupt the stable state of the school in a purposeful way. Over the four years of the study, several tipping points were reached, and we developed agent-based simulation models that capture important dynamic properties of the reform at these points. The study draws upon complexity theory in multiple ways that have supported improved education for low-achieving students
Simplified half-life methods for the analysis of kinetic data
The analysis of reaction rate data has as its goal the determination of the order rate constant which characterize the data. Chemical reactions with one reactant and present simplified methods for accomplishing this goal are considered. The approaches presented involve the use of half lives or other fractional lives. These methods are particularly useful for the more elementary discussions of kinetics found in general and physical chemistry courses
Lunar landing flight research vehicle Patent
Lunar landing flight research vehicl
Nonlinear r-modes in a spherical shell: issues of principle
We use a simple physical model to study the nonlinear behaviour of the r-mode
instability. We assume that r-modes (Rossby waves) are excited in a thin
spherical shell of rotating incompressible fluid. For this case, exact Rossby
wave solutions of arbitrary amplitude are known. We find that:
(a) These nonlinear Rossby waves carry ZERO physical angular momentum and
positive physical energy, which is contrary to the folklore belief that the
r-mode angular momentum and energy are negative.
(b) Within our model, we confirm the differential drift reported by Rezzolla,
Lamb and Shapiro (1999).
Radiation reaction is introduced into the model by assuming that the fluid is
electrically charged; r-modes are coupled to electromagnetic radiation through
current (magnetic) multipole moments. We find that:
(c) To linear order in the mode amplitude, r-modes are subject to the CFS
instability, as expected.
(d) Radiation reaction decreases the angular velocity of the shell and causes
differential rotation (which is distinct from but similar in magnitude to the
differential drift reported by Rezzolla et al.) prior to saturation of the
r-mode growth. This is contrary to the phenomenological treatments to date,
which assume that the loss of stellar angular momentum is accounted for by the
r-mode growth. We demonstrate, for the first time, that r-mode radiation
reaction leads to differential rotation.
(e) We show that for l=2 r-mode electromagnetic radiation reaction is
equivalent to gravitational radiation reaction in the lowest post-Newtonian
order.Comment: 8 pages, no figures, uses MNRAS style, abstract abridged to fit into
24 line
Symmetry and Topological Order
We prove sufficient conditions for Topological Quantum Order at both zero and
finite temperatures. The crux of the proof hinges on the existence of
low-dimensional Gauge-Like Symmetries (that notably extend and differ from
standard local gauge symmetries) and their associated defects, thus providing a
unifying framework based on a symmetry principle. These symmetries may be
actual invariances of the system, or may emerge in the low-energy sector.
Prominent examples of Topological Quantum Order display Gauge-Like Symmetries.
New systems exhibiting such symmetries include Hamiltonians depicting
orbital-dependent spin exchange and Jahn-Teller effects in transition metal
orbital compounds, short-range frustrated Klein spin models, and p+ip
superconducting arrays. We analyze the physical consequences of Gauge-Like
Symmetries (including topological terms and charges), discuss associated
braiding, and show the insufficiency of the energy spectrum, topological
entanglement entropy, maximal string correlators, and fractionalization in
establishing Topological Quantum Order. General symmetry considerations
illustrate that not withstanding spectral gaps, thermal fluctuations may impose
restrictions on certain suggested quantum computing schemes and lead to
"thermal fragility". Our results allow us to go beyond standard topological
field theories and engineer systems with Topological Quantum Order.Comment: 10 pages, 2 figures. Minimal changes relative to published version-
most notably the above shortened title (which was too late to change upon
request in the galley proofs). An elaborate description of all of the results
in this article appeared in subsequent works, principally in
arXiv:cond-mat/0702377 which was published in the Annals of Physics 324, 977-
1057 (2009
- …