815 research outputs found
Tunable transmission and harmonic generation in nonlinear metamaterials
We study the properties of a tunable nonlinear metamaterial operating at
microwave frequencies. We fabricate the nonlinear metamaterial composed of
double split-ring resonators and wires where a varactor diode is introduced
into each resonator so that the magnetic resonance can be tuned dynamically by
varying the input power. We show that at higher powers the transmission of the
metamaterial becomes power dependent, and we demonstrate experimentally
power-dependent transmission properties and selective generation of higher
harmonics.This work has been supported
by the Australian Research Council through the Discovery
projects, by the Australian Academy of Science through a
travel grant, and by the Air Force Office of Scientific Research
AFOSR through the MURI program Grant No.
F49620-03-1-0420
Effect of Thermal Gradients on the Electromigration Lifetime in Power Electronics
The combined effects of electromigration and thermomigration are studied. Significantly shorter electromigration lifetimes are observed in the presence of a temperature gradient. This cannot be explained by thermomigration only, but is attributed to the effect of temperature gradient on electromigration-induced failures
Tunable transmission and harmonic generation in nonlinear metamaterials
We study the properties of a tunable nonlinear metamaterial operating at
microwave frequencies. We fabricate the nonlinear metamaterial composed of
double split-ring resonators and wires where a varactor diode is introduced
into each resonator so that the magnetic resonance can be tuned dynamically by
varying the input power. We show that at higher powers the transmission of the
metamaterial becomes power dependent, and we demonstrate experimentally
power-dependent transmission properties and selective generation of higher
harmonics.Comment: 3 page
Wave scattering and splitting by magnetic metamaterials
We study experimentally propagation of electromagnetic waves
through a slab of uniaxial magnetic metamaterial. We observe a range of
novel phenomena including partial focusing and splitting into multiple
transmitted beams.We demonstrate that while some of these experimentally
observed effects can be described within the approximation of an effective
medium, a deeper understanding of the experimental results requires a
rigorous study of internal eigenmodes of the lattice of resonators
A low-bias simulation scheme for the SABR stochastic volatility model
The Stochastic Alpha Beta Rho Stochastic Volatility (SABR-SV) model is widely used in the
financial industry for the pricing of fixed income instruments. In this paper we develop an lowbias
simulation scheme for the SABR-SV model, which deals efficiently with (undesired) possible
negative values, the martingale property of the discrete scheme and the discretization bias of commonly
used Euler discretization schemes. The proposed algorithm is based the analytic properties
of the governing distribution. Experiments with realistic model parameters show that this scheme
is robust for interest rate valuation
Nonlinear magnetic metamaterials
We study experimentally nonlinear tunable magnetic metamaterials
operating at microwave frequencies. We fabricate the nonlinear
metamaterial composed of double split-ring resonators where a varactor
diode is introduced into each resonator so that the magnetic resonance
can be tuned dynamically by varying the input power. We demonstrate
that at higher powers the transmission of the metamaterial becomes
power-dependent and, as a result, such metamaterial can demonstrate
various nonlinear properties. In particular, we study experimentally
the power-dependent shift of the transmission band and demonstrate
nonlinearity-induced enhancement (or suppression) of wave transmission
Extensible Component Based Architecture for FLASH, A Massively Parallel, Multiphysics Simulation Code
FLASH is a publicly available high performance application code which has
evolved into a modular, extensible software system from a collection of
unconnected legacy codes. FLASH has been successful because its capabilities
have been driven by the needs of scientific applications, without compromising
maintainability, performance, and usability. In its newest incarnation, FLASH3
consists of inter-operable modules that can be combined to generate different
applications. The FLASH architecture allows arbitrarily many alternative
implementations of its components to co-exist and interchange with each other,
resulting in greater flexibility. Further, a simple and elegant mechanism
exists for customization of code functionality without the need to modify the
core implementation of the source. A built-in unit test framework providing
verifiability, combined with a rigorous software maintenance process, allow the
code to operate simultaneously in the dual mode of production and development.
In this paper we describe the FLASH3 architecture, with emphasis on solutions
to the more challenging conflicts arising from solver complexity, portable
performance requirements, and legacy codes. We also include results from user
surveys conducted in 2005 and 2007, which highlight the success of the code.Comment: 33 pages, 7 figures; revised paper submitted to Parallel Computin
Salmonella choleraesuis live vaccine strain suisaloral: molecular characterization and differentiation from homologous field isolates
The Salmonella enterica subsp. enterica (S.) live vaccine Suisaloral represents an auxotrophic mutant of a S. Choleraesuis strain which is deficient in adenine synthesis. Based on this auxotrophic marker, an adenine-deficient medium is used to identifY this vaccine strain by its inability to grow in this diagnostic medium. However, the widespread application of a Salmonella live vaccine strain requires additional methods that enable a reliable identification of the vaccine strain, its differentiation from field isolates of the same serovar as well as the proof of its genetic stability during animal and environmental passages. Since molecular methods have proven to be very useful tools for the characterization of Salmonella field isolates (Olsen et al. 1993) but also of other Salmonella enterica subsp. enterica (S.) live vaccine strains such as the S. Typhimurium vaccine strain Zoosaloral H (Schwarz & Liebisch 1994a,b) and the S. Dublin vaccine strain Bovisaloral (Liebisch & Schwarz 1996), four independent molecular methods were used to characterize the S. Choleraesuis live vaccine strain Suisaloral and to differentiate this live vaccine strain from homologous field isolates
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