17,338 research outputs found
Eigenmode-based capacitance calculations with applications in passivation layer design
The design of high-speed metallic interconnects such as microstrips requires the correct characterization of both the conductors and the surrounding dielectric environment, in order to accurately predict their propagation characteristics. A fast boundary integral equation approach is obtained by modeling all materials as equivalent surface charge densities in free space. The capacitive behavior of a finite dielectric environment can then be determined by means of a transformation matrix, relating these charge densities to the boundary value of the electric potential. In this paper, a new calculation method is presented for the important case that the dielectric environment is composed of homogeneous rectangles. The method, based on a surface charge expansion in terms of the Robin eigenfunctions of the considered rectangles, is not only more efficient than traditional methods, but is also more accurate, as shown in some numerical experiments. As an application, the design and behavior of a microstrip passivation layer is treated in some detail
Mean-field solution of the parity-conserving kinetic phase transition in one dimension
A two-offspring branching annihilating random walk model, with finite
reaction rates, is studied in one-dimension. The model exhibits a transition
from an active to an absorbing phase, expected to belong to the
universality class embracing systems that possess two symmetric absorbing
states, which in one-dimensional systems, is in many cases equivalent to parity
conservation. The phase transition is studied analytically through a mean-field
like modification of the so-called {\it parity interval method}. The original
method of parity intervals allows for an exact analysis of the
diffusion-controlled limit of infinite reaction rate, where there is no active
phase and hence no phase transition. For finite rates, we obtain a surprisingly
good description of the transition which compares favorably with the outcome of
Monte Carlo simulations. This provides one of the first analytical attempts to
deal with the broadly studied DP2 universality class.Comment: 4 Figures. 9 Pages. revtex4. Some comments have been improve
Morphisms from P2 to Gr(2,C4)
In this note we study morphisms from P2 to Gr(2,C4) from the point of view of
the cohomology class they represent in the Grassmannian. This leads to some new
result about projection of d-uple imbedding of P2 to P5
The fundamental group of reduced suspensions
We classify pointed spaces according to the first fundamental group of their
reduced suspension. A pointed space is either of so-called totally path
disconnected type or of horseshoe type. These two camps are defined
topologically but a characterization is given in terms of fundamental groups.
Among totally path disconnected spaces the fundamental group is shown to be a
complete invariant for a notion of topological equivalence weaker than that of
homeomorphism
Small-Scale Markets for Bilateral Resource Trading in the Sharing Economy
We consider a general small-scale market for agent-to-agent resource sharing,
in which each agent could either be a server (seller) or a client (buyer) in
each time period. In every time period, a server has a certain amount of
resources that any client could consume, and randomly gets matched with a
client. Our target is to maximize the resource utilization in such an
agent-to-agent market, where the agents are strategic. During each transaction,
the server gets money and the client gets resources. Hence, trade ratio
maximization implies efficiency maximization of our system. We model the
proposed market system through a Mean Field Game approach and prove the
existence of the Mean Field Equilibrium, which can achieve an almost 100% trade
ratio. Finally, we carry out a simulation study motivated by an agent-to-agent
computing market, and a case study on a proposed photovoltaic market, and show
the designed market benefits both individuals and the system as a whole
Weak solutions to the Navier-Stokes inequality with arbitrary energy profiles
In a recent paper, Buckmaster & Vicol (arXiv:1709.10033) used the method of
convex integration to construct weak solutions to the 3D incompressible
Navier-Stokes equations such that for a given
non-negative and smooth energy profile . However, it is
not known whether it is possible to extend this method to construct nonunique
suitable weak solutions (that is weak solutions satisfying the strong energy
inequality (SEI) and the local energy inequality (LEI)), Leray-Hopf weak
solutions (that is weak solutions satisfying the SEI), or at least to exclude
energy profiles that are not nonincreasing. In this paper we are concerned with
weak solutions to the Navier-Stokes inequality on , that is
vector fields that satisfy both the SEI and the LEI (but not necessarily solve
the Navier-Stokes equations). Given and a nonincreasing energy profile
we construct weak solution to the Navier-Stokes
inequality that are localised in space and whose energy profile stays arbitrarily close to for all . Our
method applies only to nonincreasing energy profiles. The relevance of such
solutions is that, despite not satisfying the Navier-Stokes equations, they
satisfy the partial regularity theory of Caffarelli, Kohn & Nirenberg (Comm.
Pure Appl. Math., 1982). In fact, Scheffer's constructions of weak solutions to
the Navier-Stokes inequality with blow-ups (Comm. Math. Phys., 1985 & 1987)
show that the Caffarelli, Kohn & Nirenberg's theory is sharp for such
solutions. Our approach gives an indication of a number of ideas used by
Scheffer. Moreover, it can be used to obtain a stronger result than Scheffer's.
Namely, we obtain weak solutions to the Navier-Stokes inequality with both
blow-up and a prescribed energy profile.Comment: 26 pages, 4 figures. arXiv admin note: text overlap with
arXiv:1709.0060
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