32,855 research outputs found
FlexibleSUSY -- A spectrum generator generator for supersymmetric models
We introduce FlexibleSUSY, a Mathematica and C++ package, which generates a
fast, precise C++ spectrum generator for any SUSY model specified by the user.
The generated code is designed with both speed and modularity in mind, making
it easy to adapt and extend with new features. The model is specified by
supplying the superpotential, gauge structure and particle content in a SARAH
model file; specific boundary conditions e.g. at the GUT, weak or intermediate
scales are defined in a separate FlexibleSUSY model file. From these model
files, FlexibleSUSY generates C++ code for self-energies, tadpole corrections,
renormalization group equations (RGEs) and electroweak symmetry breaking (EWSB)
conditions and combines them with numerical routines for solving the RGEs and
EWSB conditions simultaneously. The resulting spectrum generator is then able
to solve for the spectrum of the model, including loop-corrected pole masses,
consistent with user specified boundary conditions. The modular structure of
the generated code allows for individual components to be replaced with an
alternative if available. FlexibleSUSY has been carefully designed to grow as
alternative solvers and calculators are added. Predefined models include the
MSSM, NMSSM, ESSM, USSM, R-symmetric models and models with right-handed
neutrinos.Comment: 56 pages, 3 figures, 3 tables; v3: correcting typos, matches version
accepted for publication by CP
A theory of MHD instability of an inhomogeneous plasma jet
A problem of the instability of an inhomogeneous axisymmetric plasma jet in a
parallel magnetic field is solved. The jet boundary becomes, under certain
conditions, unstable relative to magnetosonic oscillations (Kelvin-Helmholtz
instability) in the presence of a shear flow at the jet boundary. Because of
its internal inhomogeneity the plasma jet has resonance surfaces, where
conversion takes place between various modes of plasma MHD oscillations.
Propagating in inhomogeneous plasma, fast magnetosonic waves drive the Alfven
and slow magnetosonic oscillations, tightly localized across the magnetic
shells, on the resonance surfaces. MHD oscillation energy is absorbed in the
neighbourhood of these resonance surfaces. The resonance surfaces disappear for
the eigen-modes of slow magnetosonic waves propagating in the jet waveguide.
The stability of the plasma MHD flow is determined by competition between the
mechanisms of shear flow instability on the boundary and wave energy
dissipation because of resonant MHD-mode coupling. The problem is solved
analytically, in the WKB approximation, for the plasma jet with a boundary in
the form of a tangential discontinuity over the radial coordinate. The
Kelvin-Helmholtz instability develops if plasma flow velocity in the jet
exceeds the maximum Alfven speed at the boundary. The stability of the plasma
jet with a smooth boundary layer is investigated numerically for the basic
modes of MHD oscillations, to which the WKB approximation is inapplicable. A
new "global" unstable mode of MHD oscillations has been discovered which,
unlike the Kelvin-Helmholtz instability, exists for any, however weak, plasma
flow velocities
Simple Model of Propagating Flame Pulsations
A simple model which exhibits dynamical flame properties in 1D is presented.
It is investigated analytically and numerically. The results are applicable to
problems of flame propagation in supernovae Ia.Comment: 10 pages, 8 figures, revised version accepted by MNRA
Unsupervised Monocular Depth Estimation with Left-Right Consistency
Learning based methods have shown very promising results for the task of
depth estimation in single images. However, most existing approaches treat
depth prediction as a supervised regression problem and as a result, require
vast quantities of corresponding ground truth depth data for training. Just
recording quality depth data in a range of environments is a challenging
problem. In this paper, we innovate beyond existing approaches, replacing the
use of explicit depth data during training with easier-to-obtain binocular
stereo footage.
We propose a novel training objective that enables our convolutional neural
network to learn to perform single image depth estimation, despite the absence
of ground truth depth data. Exploiting epipolar geometry constraints, we
generate disparity images by training our network with an image reconstruction
loss. We show that solving for image reconstruction alone results in poor
quality depth images. To overcome this problem, we propose a novel training
loss that enforces consistency between the disparities produced relative to
both the left and right images, leading to improved performance and robustness
compared to existing approaches. Our method produces state of the art results
for monocular depth estimation on the KITTI driving dataset, even outperforming
supervised methods that have been trained with ground truth depth.Comment: CVPR 2017 ora
GemTools: A fast and efficient approach to estimating genetic ancestry
To uncover the genetic basis of complex disease, individuals are often
measured at a large number of genetic variants (usually SNPs) across the
genome. GemTools provides computationally efficient tools for modeling genetic
ancestry based on SNP genotypes. The main algorithm creates an eigenmap based
on genetic similarities, and then clusters subjects based on their map
position. This process is continued iteratively until each cluster is
relatively homogeneous. For genetic association studies, GemTools matches cases
and controls based on genetic similarity.Comment: 5 pages, 1 figur
Active Vibration Control of Structures using an Impedance Matching Control Technique
Active vibration control of structures has gained a lot of interest in recent years. This paper presents an active vibration control methodology of a structure using piezoelectric actuators. The proposed methodology is useful in practical applications where the system to be controlled is difficult to model due to the presence of complex boundary conditions. The impedance matching control technique uses a power flow approach wherein the controller is designed such that the power flow into the structure is minimized. The system transfer function is obtained from the experimental collocated actuator/sensor pair data using Eigen Realisation Algorithm (ERA). The controller is designed for the system transfer function according to impedance matching theory. The above approach is targeted towards the vibration control of wind tunnel stings, which suffer from flow-induced vibration. A wind tunnel sting model is designed and fabricated for this study. The real time implementation of the impedance matching controller has been carried out using dSPACE® Digital Signal Processor (DSP) card. The results are encouraging and demonstrate the feasibility of applying this technique in the wind tunne
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