12,319 research outputs found

    Assembly for recovering a capsule Patent

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    Assembly for opening flight capsule stabilizing and decelerating flaps with reference to capsule recover

    Space capsule ejection assembly Patent

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    Describing assembly for opening stabilizing and decelerating flaps of flight capsules used in space researc

    Minimal kernels of Dirac operators along maps

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    Let MM be a closed spin manifold and let NN be a closed manifold. For maps f ⁣:MNf\colon M\to N and Riemannian metrics gg on MM and hh on NN, we consider the Dirac operator Dg,hfD^f_{g,h} of the twisted Dirac bundle ΣMRfTN\Sigma M\otimes_{\mathbb{R}} f^*TN. To this Dirac operator one can associate an index in KOdim(M)(pt)KO^{-dim(M)}(pt). If MM is 22-dimensional, one gets a lower bound for the dimension of the kernel of Dg,hfD^f_{g,h} out of this index. We investigate the question whether this lower bound is obtained for generic tupels (f,g,h)(f,g,h)

    The weld-brazing metal joining process

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    Superior mechanical properties were obtained in metal joints weld-brazed between faying surfaces. Weld-braze applications and advantages are listed

    Geometric variations of the Boltzmann entropy

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    We perform a calculation of the first and second order infinitesimal variations, with respect to energy, of the Boltzmann entropy of constant energy hypersurfaces of a system with a finite number of degrees of freedom. We comment on the stability interpretation of the second variation in this framework.Comment: 9 pages, no figure

    A deep photometric survey of the eta Chamaeleontis cluster down to the brown dwarf - planet boundary

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    We report the outcome of the deep optical/infrared photometric survey of the central region (33 X 33 arcmin or 0.9 pc^2) of the eta Chamaeleontis pre-main sequence star cluster. The completeness limits of the photometry are I = 19.1, J = 18.2 and H = 17.6; faint enough to reveal low mass members down to the brown dwarf and planet boundary of ~ 13 M_Jup. We found no such low mass members in this region. Our result combined with a previous shallower (I = 17) but larger area survey indicates that low mass objects (0.013 < M/M(solar mass) < 0.075) either were not created in the eta Cha cluster or were lost due to the early dynamical history of the cluster and ejected to outside the surveyed areas.Comment: 5 pages with 4 figures, accepted by MNRA

    Manifestation of three-body forces in f7/2-shell nuclei

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    The traditional nuclear shell model approach is extended to include many-body forces. The empirical Hamiltonian with a three-body force is constructed for the identical nucleons on the 0f7/2 shell. Manifestations of the three-body force in spectra, binding energies, seniority mixing, particle-hole symmetry, electromagnetic and particle transition rates are investigated. It is shown that in addition to the usual expansion of the valence space within the tranditional two-body shell model, the three-body component in the Hamiltonian can be an important part improving the quality of the theoretical approach.Comment: 5 pages, 1 figur

    Bi-HKT and bi-Kaehler supersymmetric sigma models

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    We study CKT (or bi-HKT) N = 4 supersymmetric quantum mechanical sigma models. They are characterized by the usual and the mirror sectors displaying each HKT geometry. When the metric involves isometries, a Hamiltonian reduction is possible. The most natural such reduction with respect to a half of bosonic target space coordinates produces an N = 4 model, related to the twisted Kaehler model due to Gates, Hull and Rocek, but including certain extra F-terms in the superfield action.Comment: 31 pages, minor corrections in the published versio

    Prospective Surveillance of Multivariate Spatial Disease Data

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    Surveillance systems are often focused on more than one disease within a predefined area. On those occasions when outbreaks of disease are likely to be correlated, the use of multivariate surveillance techniques integrating information from multiple diseases allows us to improve the sensitivity and timeliness of outbreak detection. In this paper, we present an extension of the surveillance conditional predictive ordinate to monitor multivariate spatial disease data. The proposed surveillance technique, which is defined for each small area and time period as the conditional predictive distribution of those counts of disease higher than expected given the data observed up to the previous time period, alerts us to both small areas of increased disease incidence and the diseases causing the alarm within each area. We investigate its performance within the framework of Bayesian hierarchical Poisson models using a simulation study. An application to diseases of the respiratory system in South Carolina is finally presented. Keywords: disease surveillance; multiple diseases; Shared component model; conditional predictive ordinate

    One step multiderivative methods for first order ordinary differential equations

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    A family of one-step multiderivative methods based on Padé approximants to the exponential function is developed. The methods are extrapolated and analysed for use in PECE mode. Error constants and stability intervals are calculated and the combinations compared with well known linear multi-step combinations and combinations using high accuracy Newton-Cotes quadrature formulas as correctors. w926020
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