64,645 research outputs found
Current economic and sensitivity analysis for ID slicing of 4 inch and 6 inch diameter silicon ingots for photovoltaic applications
The economics and sensitivities of slicing large diameter silicon ingots for photovoltaic applications were examined. Current economics and slicing add on cost sensitivities are calculated using variable parameters for blade life, slicing yield, and slice cutting speed. It is indicated that cutting speed has the biggest impact on slicing add on cost, followed by slicing yield, and by blade life as the blade life increases
The Transversal Relative Equilibria of a Hamiltonian System with Symmetry
We show that, given a certain transversality condition, the set of relative
equilibria \mcl E near p_e\in\mcl E of a Hamiltonian system with symmetry
is locally Whitney-stratified by the conjugacy classes of the isotropy
subgroups (under the product of the coadjoint and adjoint actions) of the
momentum-generator pairs of the relative equilibria. The dimension
of the stratum of the conjugacy class (K) is , where
Z(K) is the center of K, and transverse to this stratum \mcl E is locally
diffeomorphic to the commuting pairs of the Lie algebra of . The
stratum \mcl E_{(K)} is a symplectic submanifold of P near p_e\in\mcl E if
and only if is nondegenerate and K is a maximal torus of G. We also show
that there is a dense subset of G-invariant Hamiltonians on P for which all the
relative equilibria are transversal. Thus, generically, the types of
singularities that can be found in the set of relative equilibria of a
Hamiltonian system with symmetry are those types found amongst the
singularities at zero of the sets of commuting pairs of certain Lie subalgebras
of the symmetry group.Comment: 18 page
Impact of dynamical chiral symmetry breaking on meson structure and interactions
We provide a glimpse of recent progress in meson physics made via QCD's
Dyson-Schwinger equations with: a perspective on confinement and dynamical
chiral symmetry breaking (DCSB); a pre'cis on the physics of in-hadron
condensates; results for the masses of the \pi, \sigma, \rho, a_1 mesons and
their first-radial excitations; and an illustration of the impact of DCSB on
the pion form factor.Comment: 6 pages, 3 figures, 1 table. Contribution to Proceedings of the 11th
International Workshop on Meson Production, Properties and Interaction,
Uniwersytet Jagiellonski, Instytut Fizyki, Krakow, Poland, 10-15 June 201
Search for transient ultralight dark matter signatures with networks of precision measurement devices using a Bayesian statistics method
We analyze the prospects of employing a distributed global network of
precision measurement devices as a dark matter and exotic physics observatory.
In particular, we consider the atomic clocks of the Global Positioning System
(GPS), consisting of a constellation of 32 medium-Earth orbit satellites
equipped with either Cs or Rb microwave clocks and a number of Earth-based
receiver stations, some of which employ highly-stable H-maser atomic clocks.
High-accuracy timing data is available for almost two decades. By analyzing the
satellite and terrestrial atomic clock data, it is possible to search for
transient signatures of exotic physics, such as "clumpy" dark matter and dark
energy, effectively transforming the GPS constellation into a 50,000km aperture
sensor array. Here we characterize the noise of the GPS satellite atomic
clocks, describe the search method based on Bayesian statistics, and test the
method using simulated clock data. We present the projected discovery reach
using our method, and demonstrate that it can surpass the existing constrains
by several order of magnitude for certain models. Our method is not limited in
scope to GPS or atomic clock networks, and can also be applied to other
networks of precision measurement devices.Comment: See also Supplementary Information located in ancillary file
Robustness of the Thirty Meter Telescope Primary Mirror Control System
The primary mirror control system for the Thirty Meter Telescope (TMT) maintains the alignment of the 492 segments in the presence of both quasi-static (gravity and thermal) and dynamic disturbances due to unsteady wind loads. The latter results in a desired control bandwidth of 1Hz at high spatial frequencies. The achievable bandwidth is limited by robustness to (i) uncertain telescope structural dynamics (control-structure interaction) and (ii) small perturbations in the ill-conditioned influence matrix that relates segment edge sensor response to actuator commands. Both of these effects are considered herein using models of TMT. The former is explored through multivariable sensitivity analysis on a reduced-order Zernike-basis representation of the structural dynamics. The interaction matrix ("A-matrix") uncertainty has been analyzed theoretically elsewhere, and is examined here for realistic amplitude perturbations due to segment and sensor installation errors, and gravity and thermal induced segment motion. The primary influence of A-matrix uncertainty is on the control of "focusmode"; this is the least observable mode, measurable only through the edge-sensor (gap-dependent) sensitivity to the dihedral angle between segments. Accurately estimating focus-mode will require updating the A-matrix as a function of the measured gap. A-matrix uncertainty also results in a higher gain-margin requirement for focus-mode, and hence the A-matrix and CSI robustness need to be understood simultaneously. Based on the robustness analysis, the desired 1 Hz bandwidth is achievable in the presence of uncertainty for all except the lowest spatial-frequency response patterns of the primary mirror
MCMC methods for functions modifying old algorithms to make\ud them faster
Many problems arising in applications result in the need\ud
to probe a probability distribution for functions. Examples include Bayesian nonparametric statistics and conditioned diffusion processes. Standard MCMC algorithms typically become arbitrarily slow under the mesh refinement dictated by nonparametric description of the unknown function. We describe an approach to modifying a whole range of MCMC methods which ensures that their speed of convergence is robust under mesh refinement. In the applications of interest the data is often sparse and the prior specification is an essential part of the overall modeling strategy. The algorithmic approach that we describe is applicable whenever the desired probability measure has density with respect to a Gaussian process or Gaussian random field prior, and to some useful non-Gaussian priors constructed through random truncation. Applications are shown in density estimation, data assimilation in fluid mechanics, subsurface geophysics and image registration. The key design principle is to formulate the MCMC method for functions. This leads to algorithms which can be implemented via minor modification of existing algorithms, yet which show enormous speed-up on a wide range of applied problems
A Fluid Generalization of Membranes
In a certain sense a perfect fluid is a generalization of a point particle.
This leads to the question as to what is the corresponding generalization for
extended objects. The lagrangian formulation of a perfect fluid is much
generalized and this has as a particular example a fluid which is a classical
generalization of a membrane, however there is as yet no indication of any
relationship between their quantum theories.Comment: To appear in CEJP, updated to coincide with published versio
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