824 research outputs found
Lunar orbital photogaphic planning charts for candidate Apollo J-missions
A technique is presented for minimizing Mapping Camera film usage by reducing redundant coverage while meeting the desired sidelap of greater than or equal to 55%. The technique uses the normal groundtrack separation determined as a function of the number of revolutions between the respective tracks, of the initial and final nodal azimuths (or orbital inclination), and of the lunar latitude. The technique is also applicable for planning Panoramic Camera photography such that photographic contiguity is attained but redundant coverage is minimized. Graphs are included for planning mapping camera (MC) and panoramic camera (PC) photographic passes for a specific mission (i.e., specific groundtracks) to Descartes (Apollo 16), for specific missions to potential Apollo 17 sites such as Alphonsus, Proclus, Gassendi, Davy, and Tycho, and for a potential Apollo orbit-only mission with a nodal azimuth of 85 deg. Graphs are also included for determining the maximum number of revolutions which can elapse between successive MC and PC passes, for greater than or equal 55% sidelap and rectified contiguity respectively, for nodal azimuths between 5 deg and 85 deg
Strontium optical lattice clocks for practical realization of the metre and secondary representation of the second
We present a system of two independent strontium optical lattice standards
probed with a single shared ultra-narrow laser. The absolute frequency of the
clocks can be verified by the use of Er:fiber optical frequency comb with the
GPS-disciplined Rb frequency standard. We report hertz-level spectroscopy of
the clock line and measurements of frequency stability of the two strontium
optical lattice clocks.Comment: This is an author-created, un-copyedited version of an article
accepted for publication in Meas. Sci. Technol. The publisher is not
responsible for any errors or omissions in this version of the manuscript or
any version derived from it. The Version of Record is available online at
doi:10.1088/0957-0233/26/7/07520
Quantum Matching Pennies Game
A quantum version of the Matching Pennies (MP) game is proposed that is
played using an Einstein-Podolsky-Rosen-Bohm (EPR-Bohm) setting. We construct
the quantum game without using the state vectors, while considering only the
quantum mechanical joint probabilities relevant to the EPR-Bohm setting. We
embed the classical game within the quantum game such that the classical MP
game results when the quantum mechanical joint probabilities become
factorizable. We report new Nash equilibria in the quantum MP game that emerge
when the quantum mechanical joint probabilities maximally violate the
Clauser-Horne-Shimony-Holt form of Bell's inequality.Comment: Revised in light of referees' comments, submitted to Journal of the
Physical Society of Japan, 14 pages, 1 figur
FVM 1.0: a nonhydrostatic finite-volume dynamical core for the IFS
We present a nonhydrostatic finite-volume global atmospheric model
formulation for numerical weather prediction with the Integrated Forecasting
System (IFS) at ECMWF and compare it to the established operational
spectral-transform formulation. The novel Finite-Volume Module of the IFS
(henceforth IFS-FVM) integrates the fully compressible equations using
semi-implicit time stepping and non-oscillatory forward-in-time (NFT)
Eulerian advection, whereas the spectral-transform IFS solves the hydrostatic
primitive equations (optionally the fully compressible equations) using a
semi-implicit semi-Lagrangian scheme. The IFS-FVM complements the
spectral-transform counterpart by means of the finite-volume discretization
with a local low-volume communication footprint, fully conservative and
monotone advective transport, all-scale deep-atmosphere fully compressible
equations in a generalized height-based vertical coordinate, and flexible
horizontal meshes. Nevertheless, both the finite-volume and
spectral-transform formulations can share the same quasi-uniform horizontal
grid with co-located arrangement of variables, geospherical
longitude–latitude coordinates, and physics parameterizations, thereby
facilitating their comparison, coexistence, and combination in the IFS.
We highlight the advanced semi-implicit NFT finite-volume integration of the
fully compressible equations of IFS-FVM considering comprehensive
moist-precipitating dynamics with coupling to the IFS cloud parameterization
by means of a generic interface. These developments – including a new
horizontal–vertical split NFT MPDATA advective transport scheme, variable
time stepping, effective preconditioning of the elliptic Helmholtz solver in
the semi-implicit scheme, and a computationally efficient implementation of
the median-dual finite-volume approach – provide a basis for the efficacy of
IFS-FVM and its application in global numerical weather prediction. Here,
numerical experiments focus on relevant dry and moist-precipitating
baroclinic instability at various resolutions. We show that the presented
semi-implicit NFT finite-volume integration scheme on co-located meshes of
IFS-FVM can provide highly competitive solution quality and computational
performance to the proven semi-implicit semi-Lagrangian integration scheme of
the spectral-transform IFS.</p
Critical Dimensions in Architectural Photography: Contributions to Architectural Knowledge
This paper illustrates and explores three critical dimensions of photography in architecture, each of which informs the production of images, texts, and other artifacts which establish what might be called a building’s media footprint. The paper’s broad goal is to question the extent to which these critical dimensions are relevant to architectural decision-making processes. Acknowledging that such dimensions as the ones examined here rarely predict an architect’s specific design decisions in a transparent manner, the paper discusses not only the decisions made by architects during the process of designing buildings, but the decisions made by critics, visitors, and members of the general public as they engage in activities such as visiting buildings, writing about them and, particularly, photographing them.
First, the text discusses the potential of buildings to operate as mechanisms for producing images, in the sense originated by Beatriz Colomina. The question is developed through the analysis of the space of photography – mapping of points of view, directions of view, and fields of view of defined photographic collections. Secondly, it considers photography’s complicity in the canonization of buildings, and specifically, the extent to which photography is responsible for distinguishing between major and minor architectural works. Finally, the essay examines the erosion over time of photography’s historical power to frame when confronted with contemporary technologies of virtual reality and photo realistically rendered digital models. Each of these critical dimensions, or concepts, develops a specific aspect of how photographic information about buildings is organized, structured, and disseminated, and is thus only part of the larger project of architectural epistemology, which inquires into this wider field. This will be done through an examination of the Mies van der Rohe-designed Commons Building at ITT in Chicago and the evolution of its relationship with architectural photography and photographic representation – both on its own terms and through the prism of the Rem Koolhaas-designed McCormick Tribune Student Center, which adds to and incorporates the Commons Building. Until the end of the twentieth century, the Commons Building on the campus of the Illinois Institute of Technology was generally considered one of Mies van der Rohe’s lesser works. Reportedly neglected by its own architect during the design process, and frequently marginalized in academic discussions of the campus, when mentioned at all the building was often cited as an unrefined prototype of Crown Hall. This discourse took a new direction when in 1998, Rem Koolhaas/OMA won a design competition for a student center on the IIT campus: uniquely among the competition
entries, Koolhaas’s design incorporated the Commons Building within a new context – what ultimately became the McCormick Tribune Campus Center (MTCC). When critics concluded that the incorporation of the Commons Building into the larger whole could compromise its integrity as
an exemplar of Mies’s work, the building became the object of renewed interest and controversy. The two projects considered here show a clear evolution in architecture’s relationship with the photographic image. Specifically, the history of the Commons Building can be traced through photographs: during and shortly following its construction, the building was photographed as part
of Mies’s own attention to publicity; it was documented as part of historical analyses; and over time it was visited and photographed by casual and amateur photographers. Following the competition results, photographs of the Commons Building were strategically deployed by both proponents and critics of Koolhaas’s design. Contemporary photographs of the building appear in architectural and campus guidebooks and on websites such as Flickr.com. Examining the ways in which
photographs of the Commons Building appear in these various contexts allows discussion of the critical dimensions identified above and permits us to trace the evolution of the mutually reinforcing relationship between architecture and photography
GRB 080319B: A Naked-Eye Stellar Blast from the Distant Universe
Long duration gamma-ray bursts (GRBs) release copious amounts of energy
across the entire electromagnetic spectrum, and so provide a window into the
process of black hole formation from the collapse of a massive star. Over the
last forty years, our understanding of the GRB phenomenon has progressed
dramatically; nevertheless, fortuitous circumstances occasionally arise that
provide access to a regime not yet probed. GRB 080319B presented such an
opportunity, with extraordinarily bright prompt optical emission that peaked at
a visual magnitude of 5.3, making it briefly visible with the naked eye. It was
captured in exquisite detail by wide-field telescopes, imaging the burst
location from before the time of the explosion. The combination of these unique
optical data with simultaneous gamma-ray observations provides powerful
diagnostics of the detailed physics of this explosion within seconds of its
formation. Here we show that the prompt optical and gamma-ray emissions from
this event likely arise from different spectral components within the same
physical region located at a large distance from the source, implying an
extremely relativistic outflow. The chromatic behaviour of the broadband
afterglow is consistent with viewing the GRB down the very narrow inner core of
a two-component jet that is expanding into a wind-like environment consistent
with the massive star origin of long GRBs. These circumstances can explain the
extreme properties of this GRB.Comment: 43 pages, 18 figures, 3 tables, submitted to Nature May 11, 200
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