1,640 research outputs found
Fluid flow restrictor Patent
Tubular flow restrictor for gas flow control in pipelin
Gas-flow restrictor
Gas flow restrictor is described, consisting of predetermined length and size of capillary tubing to control flow rate of carrier gas into gas chromatograph of flow rate of sample gas into mass spectrometer inlet system. Length and inner diameter of capillary tubing was estimated with mathematical expressions for viscous flow
Relationships between charge density response functions, exchange holes and localized orbitals
The charge density response function and the exchange hole are closely
related to each other via the fundamental fluctuation-dissipation theorem of
physics. A simple approximate model of the static response function is visually
compared on several examples in order to demonstrate this relationship. This
study is completed by illustrating the well-known isomorphism between the
exchange hole and the square of the dominant localized orbital lying in the
space region of the reference point of the exchange hole function. The
implications of these relationships for the interpretation of common chemical
concepts, such as delocalization, are discussed.Comment: 10 two-columns pages, including 3 figure
Characterization and Inference of Graph Diffusion Processes from Observations of Stationary Signals
Many tools from the field of graph signal processing exploit knowledge of the
underlying graph's structure (e.g., as encoded in the Laplacian matrix) to
process signals on the graph. Therefore, in the case when no graph is
available, graph signal processing tools cannot be used anymore. Researchers
have proposed approaches to infer a graph topology from observations of signals
on its nodes. Since the problem is ill-posed, these approaches make
assumptions, such as smoothness of the signals on the graph, or sparsity
priors. In this paper, we propose a characterization of the space of valid
graphs, in the sense that they can explain stationary signals. To simplify the
exposition in this paper, we focus here on the case where signals were i.i.d.
at some point back in time and were observed after diffusion on a graph. We
show that the set of graphs verifying this assumption has a strong connection
with the eigenvectors of the covariance matrix, and forms a convex set. Along
with a theoretical study in which these eigenvectors are assumed to be known,
we consider the practical case when the observations are noisy, and
experimentally observe how fast the set of valid graphs converges to the set
obtained when the exact eigenvectors are known, as the number of observations
grows. To illustrate how this characterization can be used for graph recovery,
we present two methods for selecting a particular point in this set under
chosen criteria, namely graph simplicity and sparsity. Additionally, we
introduce a measure to evaluate how much a graph is adapted to signals under a
stationarity assumption. Finally, we evaluate how state-of-the-art methods
relate to this framework through experiments on a dataset of temperatures.Comment: Submitted to IEEE Transactions on Signal and Information Processing
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Photoheliograph film camera design
Photoheliograph film camera design for use with Apollo telescope moun
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