28,154 research outputs found
Model fusion using fuzzy aggregation: Special applications to metal properties
To improve the modelling performance, one should either propose a new modelling methodology or make the best of existing models. In this paper, the study is concentrated on the latter solution, where a structure-free modelling paradigm is proposed. It does not rely on a fixed structure and can combine various modelling techniques in ‘symbiosis’ using a ‘master fuzzy system’. This approach is shown to be able to include the advantages of different modelling techniques altogether by requiring less training and by minimising the efforts relating optimisation of the final structure. The proposed approach is then successfully applied to the industrial problems of predicting machining induced residual stresses for aerospace alloy components as well as modelling the mechanical properties of heat-treated alloy steels, both representing complex, non-linear and multi-dimensional environments
Position and Orientation Estimation of a Rigid Body: Rigid Body Localization
Rigid body localization refers to a problem of estimating the position of a
rigid body along with its orientation using anchors. We consider a setup in
which a few sensors are mounted on a rigid body. The absolute position of the
rigid body is not known, but, the relative position of the sensors or the
topology of the sensors on the rigid body is known. We express the absolute
position of the sensors as an affine function of the Stiefel manifold and
propose a simple least-squares (LS) estimator as well as a constrained total
least-squares (CTLS) estimator to jointly estimate the orientation and the
position of the rigid body. To account for the perturbations of the sensors, we
also propose a constrained total least-squares (CTLS) estimator. Analytical
closed-form solutions for the proposed estimators are provided. Simulations are
used to corroborate and analyze the performance of the proposed estimators.Comment: 4 pages and 1 reference page; 3 Figures; In Proc. of ICASSP 201
High-fidelity state detection and tomography of a single ion Zeeman qubit
We demonstrate high-fidelity Zeeman qubit state detection in a single trapped
88 Sr+ ion. Qubit readout is performed by shelving one of the qubit states to a
metastable level using a narrow linewidth diode laser at 674 nm followed by
state-selective fluorescence detection. The average fidelity reached for the
readout of the qubit state is 0.9989(1). We then measure the fidelity of state
tomography, averaged over all possible single-qubit states, which is 0.9979(2).
We also fully characterize the detection process using quantum process
tomography. This readout fidelity is compatible with recent estimates of the
detection error-threshold required for fault-tolerant computation, whereas
high-fidelity state tomography opens the way for high-precision quantum process
tomography
Correlation Energy Estimators based on M{\o}ller-Plesset Perturbation Theory
Some methods for the convergence acceleration of the M{\o}ller-Plesset
perturbation series for the correlation energy are discussed. The
order-by-order summation is less effective than the Feenberg series. The latter
is obtained by renormalizing the unperturbed Hamilton operator by a constant
factor that is optimized for the third order energy. In the fifth order case,
the Feenberg series can be improved by order-dependent optimization of the
parameter. Alternatively, one may use Pad{\'e} approximants or a further method
based on effective characteristic polynomials to accelerate the convergence of
the perturbation series. Numerical evidence is presented that, besides the
Feenberg-type approaches, suitable Pad{\'e} approximants, and also the
effective second order characteristic polynomial, are excellent tools for
correlation energy estimation.Comment: 21 pages, 87 references, LaTeX2e, elsart.cls, uuencoded compressed
tar file created by csh script uufiles. J. Mol. Struct. (THEOCHEM), in press.
Postscript and dvi also available via
http://www.chemie.uni-regensburg.de/preprint.html and
ftp://rchs1.uni-regensburg.de/pub/preprint/TC-QM-96-
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