16,789 research outputs found
Chow's theorem and universal holonomic quantum computation
A theorem from control theory relating the Lie algebra generated by vector
fields on a manifold to the controllability of the dynamical system is shown to
apply to Holonomic Quantum Computation. Conditions for deriving the holonomy
algebra are presented by taking covariant derivatives of the curvature
associated to a non-Abelian gauge connection. When applied to the Optical
Holonomic Computer, these conditions determine that the holonomy group of the
two-qubit interaction model contains . In particular, a
universal two-qubit logic gate is attainable for this model.Comment: 13 page
Symmetry Reduction of Optimal Control Systems and Principal Connections
This paper explores the role of symmetries and reduction in nonlinear control
and optimal control systems. The focus of the paper is to give a geometric
framework of symmetry reduction of optimal control systems as well as to show
how to obtain explicit expressions of the reduced system by exploiting the
geometry. In particular, we show how to obtain a principal connection to be
used in the reduction for various choices of symmetry groups, as opposed to
assuming such a principal connection is given or choosing a particular symmetry
group to simplify the setting. Our result synthesizes some previous works on
symmetry reduction of nonlinear control and optimal control systems. Affine and
kinematic optimal control systems are of particular interest: We explicitly
work out the details for such systems and also show a few examples of symmetry
reduction of kinematic optimal control problems.Comment: 23 pages, 2 figure
Independent Orbiter Assessment (IOA): Assessment of the remote manipulator system FMEA/CIL
The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) are presented. The IOA effort first completed an analysis of the Remote Manipulator System (RMS) hardware, generating draft failure modes and potential critical items. To preserve independence, this analysis was accomplished without reliance upon the results contained within the NASA FMEA/CIL documentation. The IOA results were than compared to the NASA FMEA/CIL baseline with proposed Post 51-L updates included. A resolution of each discrepancy from the comparison is provided through additional analysis as required. The results of that comparison for the Orbiter RMS hardware are documented. The IOA product for the RMS analysis consisted of 604 failure mode worksheets that resulted in 458 potential critical items being identified. Comparison was made to the NASA baseline which consisted of 45 FMEAs and 321 CIL items. This comparison produced agreement on all but 154 FMEAs which caused differences in 137 CIL items
Sharp measure contraction property for generalized H-type Carnot groups
We prove that H-type Carnot groups of rank and dimension satisfy the
if and only if and . The latter
integer coincides with the geodesic dimension of the Carnot group. The same
result holds true for the larger class of generalized H-type Carnot groups
introduced in this paper, and for which we compute explicitly the optimal
synthesis. This constitutes the largest class of Carnot groups for which the
curvature exponent coincides with the geodesic dimension. We stress that
generalized H-type Carnot groups have step 2, include all corank 1 groups and,
in general, admit abnormal minimizing curves.
As a corollary, we prove the absolute continuity of the Wasserstein geodesics
for the quadratic cost on all generalized H-type Carnot groups.Comment: 18 pages. This article extends the results of arXiv:1510.05960. v2:
revised and improved version. v3: final version, to appear in Commun.
Contemp. Mat
Rigidity around Poisson Submanifolds
We prove a rigidity theorem in Poisson geometry around compact Poisson
submanifolds, using the Nash-Moser fast convergence method. In the case of
one-point submanifolds (fixed points), this immediately implies a stronger
version of Conn's linearization theorem, also proving that Conn's theorem is,
indeed, just a manifestation of a rigidity phenomenon; similarly, in the case
of arbitrary symplectic leaves, it gives a stronger version of the local normal
form theorem; another interesting case corresponds to spheres inside duals of
compact semisimple Lie algebras, our result can be used to fully compute the
resulting Poisson moduli space.Comment: 43 pages, v3: published versio
Independent Orbiter Assessment (IOA): Analysis of the remote manipulator system
The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) are presented. The IOA approach features a top-down analysis of the hardware to determine failure modes, criticality, and potential critical items (PCIs). To preserve independence, this analysis was accomplished without reliance upon the results contained within the NASA FMEA/CIL documentation. The independent analysis results for the Orbiter Remote Manipulator System (RMS) are documented. The RMS hardware and software are primarily required for deploying and/or retrieving up to five payloads during a single mission, capture and retrieve free-flying payloads, and for performing Manipulator Foot Restraint operations. Specifically, the RMS hardware consists of the following components: end effector; displays and controls; manipulator controller interface unit; arm based electronics; and the arm. The IOA analysis process utilized available RMS hardware drawings, schematics and documents for defining hardware assemblies, components and hardware items. Each level of hardware was evaluated and analyzed for possible failure modes and effects. Criticality was assigned based upon the severity of the effect for each failure mode. Of the 574 failure modes analyzed, 413 were determined to be PCIs
Power dissipation in nanoscale conductors: classical, semi-classical and quantum dynamics
Modelling Joule heating is a difficult problem because of the need to introduce correct correlations between the motions of the ions and the electrons. In this paper we analyse three different models of current induced heating (a purely classical model, a fully quantum model and a hybrid model in which the electrons are treated quantum mechanically and the atoms are treated classically). We find that all three models allow for both heating and cooling processes in the presence of a current, and furthermore the purely classical and purely quantum models show remarkable agreement in the limit of high biases. However, the hybrid model in the Ehrenfest approximation tends to suppress heating. Analysis of the equations of motion reveals that this is a consequence of two things: the electrons are being treated as a continuous fluid and the atoms cannot undergo quantum fluctuations. A means for correcting this is suggested
CONSUMER USE OF NUTRITION LABELS ON PACKAGED MEATS
Consumer perceptions of the importance of nutritional labeling of fresh meats and knowledge of nutritional terms have been presented in the Journal of Food Distribution Research (Piedra, et al 1995). This article presents follow up information on consumer reported uses of nutritional labels on packaged meats and the specific nutrients that the consumers check for on packaged meats. The results indicate that consumers use nutrition labels to check for desirable dietary components and to compare nutrient content among meats as well as to check for the presence of undesirable dietary components in packaged meats.Consumer/Household Economics,
HOUSEHOLD PERCEPTIONS OF THE NUTRITIONAL LABELING OF MEATS
Previous research on the relationship between diet and health has increased consumer interest in the nutritional content of specific foods. Federal programs, such as the Dietary Guidelines for Americans and The Food Pyramid, have had similar impacts. A 1994 mail survey of 3,080 Louisiana households in eight rural and urban parishes examined consumer awareness of the nutritional labeling of fresh meats and its importance. Rural respondents placed more emphasis on nutritional labeling than did urban respondents. The respondents also ranked three descriptive terms (lean, extra lean and low fat) for fat content as defined by the USDA. Eighteen percent of households ranked them correctly with white households displaying better ranking capability. These results tend to justify an earlier decision by Congress to implement legislation covering the nutritional labeling of fresh meats.Consumer/Household Economics,
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