60,622 research outputs found
An extensive English language bibliography on graph theory and its applications
Bibliography on graph theory and its application
Methods for Determining Blood Flow Through Intact Vessels of Experimental Animals Under Conditions of Gravitational Stress and in Extra-terrestrial Space Capsules Final Report, 1 Nov. 1960 - 31 Dec. 1964
Electromagnetic blood flow meter to determine blood flow through intact vessels of test animals in gravitational stress and in extraterrestrial space capsule
Gradient and Passive Circuit Structure in a Class of Non-linear Dynamics on a Graph
We consider a class of non-linear dynamics on a graph that contains and
generalizes various models from network systems and control and study
convergence to uniform agreement states using gradient methods. In particular,
under the assumption of detailed balance, we provide a method to formulate the
governing ODE system in gradient descent form of sum-separable energy
functions, which thus represent a class of Lyapunov functions; this class
coincides with Csisz\'{a}r's information divergences. Our approach bases on a
transformation of the original problem to a mass-preserving transport problem
and it reflects a little-noticed general structure result for passive network
synthesis obtained by B.D.O. Anderson and P.J. Moylan in 1975. The proposed
gradient formulation extends known gradient results in dynamical systems
obtained recently by M. Erbar and J. Maas in the context of porous medium
equations. Furthermore, we exhibit a novel relationship between inhomogeneous
Markov chains and passive non-linear circuits through gradient systems, and
show that passivity of resistor elements is equivalent to strict convexity of
sum-separable stored energy. Eventually, we discuss our results at the
intersection of Markov chains and network systems under sinusoidal coupling
A survey of methods for deciding whether a reaction network is multistationary
Which reaction networks, when taken with mass-action kinetics, have the
capacity for multiple steady states? There is no complete answer to this
question, but over the last 40 years various criteria have been developed that
can answer this question in certain cases. This work surveys these
developments, with an emphasis on recent results that connect the capacity for
multistationarity of one network to that of another. In this latter setting, we
consider a network that is embedded in a larger network , which means
that is obtained from by removing some subsets of chemical species and
reactions. This embedding relation is a significant generalization of the
subnetwork relation. For arbitrary networks, it is not true that if is
embedded in , then the steady states of lift to . Nonetheless, this
does hold for certain classes of networks; one such class is that of fully open
networks. This motivates the search for embedding-minimal multistationary
networks: those networks which admit multiple steady states but no proper,
embedded networks admit multiple steady states. We present results about such
minimal networks, including several new constructions of infinite families of
these networks
Hall Effect Gyrators and Circulators
The electronic circulator, and its close relative the gyrator, are invaluable
tools for noise management and signal routing in the current generation of
low-temperature microwave systems for the implementation of new quantum
technologies. The current implementation of these devices using the Faraday
effect is satisfactory, but requires a bulky structure whose physical dimension
is close to the microwave wavelength employed. The Hall effect is an
alternative non-reciprocal effect that can also be used to produce desired
device functionality. We review earlier efforts to use an ohmically-contacted
four-terminal Hall bar, explaining why this approach leads to unacceptably high
device loss. We find that capacitive coupling to such a Hall conductor has much
greater promise for achieving good circulator and gyrator functionality. We
formulate a classical Ohm-Hall analysis for calculating the properties of such
a device, and show how this classical theory simplifies remarkably in the
limiting case of the Hall angle approaching 90 degrees. In this limit we find
that either a four-terminal or a three-terminal capacitive device can give
excellent circulator behavior, with device dimensions far smaller than the a.c.
wavelength. An experiment is proposed to achieve GHz-band gyration in
millimetre (and smaller) scale structures employing either semiconductor
heterostructure or graphene Hall conductors. An inductively coupled scheme for
realising a Hall gyrator is also analysed.Comment: 18 pages, 15 figures, ~5 MB. V3: sections V-VIII revisited plus other
minor changes, Fig 2 added. Submitted to PR
- …