21,938 research outputs found

    Autonomous prealignment of a docking mechanism

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    Proposed future space exploration, such as lunar and Martian expeditions, will require autonomous docking of space vehicles. One proposed candidate method of autonomous docking utilizes a actively controlled parallel manipulator. Operation of the proposed docking manipulator can be segmented into four successive events: prealignment, capture/latching, attenuation, and structural rigidization. This paper discusses the development and testing of a digitally controlled, six-degree-of-freedom (6-DOF), parallel manipulator for the prealignment segment of a docking spacecraft

    The Magnetic Topology of the Weak-Lined T Tauri Star V410 - A Simultaneous Temperature and Magnetic Field Inversion

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    We present a detailed temperature and magnetic investigation of the T Tauri star V410 Tau by means of a simultaneous Doppler- and Zeeman-Doppler Imaging. Moreover we introduce a new line profile reconstruction method based on a singular value decomposition (SVD) to extract the weak polarized line profiles. One of the key features of the line profile reconstruction is that the SVD line profiles are amenable to radiative transfer modeling within our Zeeman-Doppler Imaging code iMap. The code also utilizes a new iterative regularization scheme which is independent of any additional surface constraints. To provide more stability a vital part of our inversion strategy is the inversion of both Stokes I and Stokes V profiles to simultaneously reconstruct the temperature and magnetic field surface distribution of V410 Tau. A new image-shear analysis is also implemented to allow the search for image and line profile distortions induced by a differential rotation of the star. The magnetic field structure we obtain for V410 Tau shows a good spatial correlation with the surface temperature and is dominated by a strong field within the cool polar spot. The Zeeman-Doppler maps exhibit a large-scale organization of both polarities around the polar cap in the form of a twisted bipolar structure. The magnetic field reaches a value of almost 2 kG within the polar region but smaller fields are also present down to lower latitudes. The pronounced non-axisymmetric field structure and the non-detection of a differential rotation for V410 Tau supports the idea of an underlying α2\alpha^2-type dynamo, which is predicted for weak-lined T Tauri stars.Comment: Accepted for A&A, 18 pages, 10 figure

    On the Miura map between the dispersionless KP and dispersionless modified KP hierarchies

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    We investigate the Miura map between the dispersionless KP and dispersionless modified KP hierarchies. We show that the Miura map is canonical with respect to their bi-Hamiltonian structures. Moreover, inspired by the works of Takasaki and Takebe, the twistor construction of solution structure for the dispersionless modified KP hierarchy is given.Comment: 19 pages, Latex, no figure

    Spin-other-orbit matrix elements for f sup 4 configurations

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    Data for spin orbit matrix elements for f to 4th power configuratio

    Configuration interaction matrix elements for d sup n configurations

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    Configuration interaction matrix elements for weak interaction

    Matrix elements of the spin-spin interactions for f sup 4 configurations

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    Matrix elements of spin-spin interactions for F4 electron configuration

    Blood, body and belonging: the geographies of halal food consumption in the UK

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    This article presents a framework for understanding how ‘halal’ food consumption is understood, practiced and experienced by British Muslims through an empirical study in Birmingham (UK). There are emerging bodies of literature in geography that analyse food/animal ethics and work recognising the increasing importance of the halal food industry. However, there is also a need to understand how ethical and theological concerns translate when scaled down to individual food choices and experiences of Muslims, as they negotiate food consumption as a minority group. Accordingly, this paper utilises qualitative data from an in-depth study to develop a framework for understanding halal food consumption from the perspective of British Muslims. Utilising conceptual literature on food/animal ethics, abjection and belonging it draws evidence into three corresponding sections: (i) Blood–the ethics of religious slaughter processes; (ii) Body–the embodied responses to ‘clean’ and ‘impure’ food, and (iii) Belonging–integral connections between halal food and notions of belonging. The paper concludes by suggesting that this framework is a helpful starting point from which to understand the ways in which halal food consumption scales down from abstraction to practice, from ethics to embodied experience

    Electromagnetic Fields of Slowly Rotating Magnetized Gravastars

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    We study the dipolar magnetic field configuration and present solutions of Maxwell equations in the internal background spacetime of a a slowly rotating gravastar. The shell of gravastar where magnetic field penetrated is modeled as sphere consisting of perfect highly magnetized fluid with infinite conductivity. Dipolar magnetic field of the gravastar is produced by a circular current loop symmetrically placed at radius aa at the equatorial plane.Comment: 5 pages, 2 figures, accepted for publication to Mod. Phys. Lett.

    Phase transition from quark-meson coupling hyperonic matter to deconfined quark matter

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    We investigate the possibility and consequences of phase transitions from an equation of state (EOS) describing nucleons and hyperons interacting via mean fields of sigma, omega, and rho mesons in the recently improved quark-meson coupling (QMC) model to an EOS describing a Fermi gas of quarks in an MIT bag. The transition to a mixed phase of baryons and deconfined quarks, and subsequently to a pure deconfined quark phase, is described using the method of Glendenning. The overall EOS for the three phases is calculated for various scenarios and used to calculate stellar solutions using the Tolman-Oppenheimer-Volkoff equations. The results are compared with recent experimental data, and the validity of each case is discussed with consequences for determining the species content of the interior of neutron stars.Comment: 12 pages, 14 figures; minor typos correcte

    Matrix elements of atomic interaction operators for d sup n configurations

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    Tabulation of matrix elements of atomic interaction operators for various configuration
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