9,420 research outputs found
Line of Dirac monopoles embedded in a Bose-Einstein condensate
The gauge field of a uniform line of magnetic monopoles is created using a
single Laguerre-Gauss laser mode and a gradient in the physical magnetic field.
We study the effect of these monopoles on a Bose condensed atomic gas, whose
vortex structure transforms when more than six monopoles are trapped within the
cloud. Finally, we study this transition with the collective modes
Not Just Cyberwarfare
© Springer Science+Business Media Dordrecht 2015Bringsjord and Licato provide a general meta-argument that cyberwarfare is so different from traditional kinetic warfare that no argument from analogy can allow the just war theory of Augustine and Aquinas (hereinafter called JWT) to be pulled over from traditional (modern) warfare to cyberwarfare. I believe that this meta- argument is sound and that it applies not just to cyberwarfare: in particular, on my reading of the meta-argument, argument from analogy has never been adequate to allow JWT to be applied to the kind of warfare that we are familiar with now.Peer reviewedSubmitted Versio
Payload system tradeoffs for mobile communications satellites
System level trade-offs carried out during Mobile Satellite (M-SAT) design activities are described. These trade-offs relate to the use of low level beam forming, flexible power and spectrum distribution, and selection of the number of beams to cover the service area. It is shown that antenna performance can be improved by sharing horns between beams using a low level beam forming network (BFN). Additionally, greatly increased power utilization is possible using a hybrid matrix concept to share power between beams
Considerations for spacecraft design for MSAT
The paper describes the system design considerations and design activities performed at Spar Aerospace in the last 18 months in support of the development of a Canadian Mobile Communication Satellite (MSAT). Recent evolving international agreements and events of importance to MSAT are the emergence of the U.S. Operator and the Mobile WARC 1987. Their impacts on the system requirements and system design are discussed. Solutions to these new requirements are implemented into the 9 Beam baseline design. The system design and the parallel technology development permit the support of a commercial flight program
Social Requirements for Virtual Organization Breeding Environments
The creation of Virtual Breeding Environments (VBE) is a topic which has
received too little attention: in most former works, the existence of the VBE
is either assumed, or is considered as the result of the voluntary,
participatory gathering of a set of candidate companies. In this paper, the
creation of a VBE by a third authority is considered: chambers of commerce, as
organizations whose goal is to promote and facilitate business interests and
activity in the community, could be good candidates for exogenous VBE creators.
During VBE planning, there is a need to specify social requirements for the
VBE. In this paper, SNA metrics are proposed as a way for a VBE planner to
express social requirements for a VBE to be created. Additionally, a set of
social requirements for VO planners, VO brokers, and VBE members are proposed.Comment: 10 pages, 2 figure
Depositing spacing layers on magnetic film with liquid phase epitaxy
Liquid phase epitaxy spacing layer is compatible with systems which are hard-bubble proofed by use of second magnetic garnet film as capping layer. Composite is superior in that: circuit fabrication time is reduced; adherence is superior; visibility is better; and, good match of thermal expansion coefficients is provided
Extending Continuum Models for Atom Probe Simulation
This work describes extensions to existing level-set algorithms developed for
application within the field of Atom Probe Tomography (APT). We present a new
simulation tool for the simulation of 3D tomographic volumes, using advanced
level set methods. By combining narrow-band, B-Tree and particle-tracing
approaches from level-set methods, we demonstrate a practical tool for
simulating shape changes to APT samples under applied electrostatic fields, in
three dimensions. This work builds upon our previous studies by allowing for
non-axially symmetric solutions, with minimal loss in computational speed,
whilst retaining numerical accuracy
Similar Sublattices and Coincidence Rotations of the Root Lattice A4 and its Dual
A natural way to describe the Penrose tiling employs the projection method on
the basis of the root lattice A4 or its dual. Properties of these lattices are
thus related to properties of the Penrose tiling. Moreover, the root lattice A4
appears in various other contexts such as sphere packings, efficient coding
schemes and lattice quantizers.
Here, the lattice A4 is considered within the icosian ring, whose rich
arithmetic structure leads to parametrisations of the similar sublattices and
the coincidence rotations of A4 and its dual lattice. These parametrisations,
both in terms of a single icosian, imply an index formula for the corresponding
sublattices. The results are encapsulated in Dirichlet series generating
functions. For every index, they provide the number of distinct similar
sublattices as well as the number of coincidence rotations of A4 and its dual.Comment: 8 pages, paper presented at ICQ10 (Zurich, Switzerland
The rings of n-dimensional polytopes
Points of an orbit of a finite Coxeter group G, generated by n reflections
starting from a single seed point, are considered as vertices of a polytope
(G-polytope) centered at the origin of a real n-dimensional Euclidean space. A
general efficient method is recalled for the geometric description of G-
polytopes, their faces of all dimensions and their adjacencies. Products and
symmetrized powers of G-polytopes are introduced and their decomposition into
the sums of G-polytopes is described. Several invariants of G-polytopes are
found, namely the analogs of Dynkin indices of degrees 2 and 4, anomaly numbers
and congruence classes of the polytopes. The definitions apply to
crystallographic and non-crystallographic Coxeter groups. Examples and
applications are shown.Comment: 24 page
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