3,404 research outputs found
Efficient Analysis of Complex Diagrams using Constraint-Based Parsing
This paper describes substantial advances in the analysis (parsing) of
diagrams using constraint grammars. The addition of set types to the grammar
and spatial indexing of the data make it possible to efficiently parse real
diagrams of substantial complexity. The system is probably the first to
demonstrate efficient diagram parsing using grammars that easily be retargeted
to other domains. The work assumes that the diagrams are available as a flat
collection of graphics primitives: lines, polygons, circles, Bezier curves and
text. This is appropriate for future electronic documents or for vectorized
diagrams converted from scanned images. The classes of diagrams that we have
analyzed include x,y data graphs and genetic diagrams drawn from the biological
literature, as well as finite state automata diagrams (states and arcs). As an
example, parsing a four-part data graph composed of 133 primitives required 35
sec using Macintosh Common Lisp on a Macintosh Quadra 700.Comment: 9 pages, Postscript, no fonts, compressed, uuencoded. Composed in
MSWord 5.1a for the Mac. To appear in ICDAR '95. Other versions at
ftp://ftp.ccs.neu.edu/pub/people/futrell
Dissipative breathers in rf SQUID metamaterials
The existence and stability of dissipative breathers in rf SQUID
(Superconducting Quantum Interference Device) arrays is investigated
numerically. In such arrays, the nonlinearity which is intrinsic to each SQUID,
along with the weak magnetic coupling of each SQUID to its nearest neighbors,
result in the formation of discrete breathers. We analyze several discrete
breather excitations in rf SQUID arrays driven by alternating flux sources in
the presence of losses. The delicate balance between internal power losses and
input power, results in the formation of dissipative discrete breather (DDB)
structures up to relatively large coupling parameters. It is shown that DDBs
may locally alter the magnetic response of an rf SQUID array from paramagnetic
to diamagnetic or vice versa.Comment: 5 pages, 4 figure
Surface breathers in discrete magnetic metamaterials
We analyze the properties of discrete breathers excited near the edge of a one-dimensional metamaterial created by a truncated array of nonlinear split-ring resonators. We study a crossover between nonlinear surface states and discrete breathers by analyzing the modes centered at finite distances from the array edge and demonstrate the existence of a class of nonlinear localized surface states, the so-called nonlinear Tamm states or surface breathers, which exhibit features that have no counterparts either in the continuous systems or in linear arrays
The Basic Psychological Needs in Exercise Scale: Translation and Evidence for Cross-Cultural Validity
The present study reports on the psychometric evaluation and cross-cultural validity of the Basic Psychological Needs in Exercise Scale (BPNES; Vlachopoulos & Michailidou, 2006) translated from Greek into English. The data obtained from 346 British exercise participants supported the hypothesized 3-factor structure,showed satisfactory internal reliability coefficients, and offered evidence for the factor concurrent, discriminant, and nomological validity of the translated scale.Cross-cultural validity analyses across British and Greek participants supported configural invariance and partial metric, partial strong, and partial strict factorial invariance of the BPNES responses. The findings provide promising evidence for the validity and reliability of the translated BPNES and support the use of the scale in single-culture and cross-culture exercise-related motivational research within the self-determination theory framework
Multistability and localization in coupled nonlinear split-ring resonators
We study the dynamics of a pair of nonlinear split-ring resonators (a
`metadimer') excited by an alternating magnetic field and coupled magnetically.
Linear metadimers of this kind have been recently used as the elementary
components for three-dimensional metamaterials or 'stereometamaterials' [N. Liu
{\em et al}, Nature Photon. {\bf 3}, 157 (2009)]. We demonstrate that
nonlinearity offers more possibilities with respect to real-time tunability and
a multiplicity of states which can be reached by varying the external field.
Moreover, we demonstrate almost total localization of the energy in one of the
resonators in a broad range of parameters.Comment: 3 pages, 5 figure
Organization politics and the role of accounting
This paper views the organization as an open political system. The way that organizations are structured makes inevitable the creation of sectional interests and differentiates the understanding of organizational goals. Decision-making is viewed as a power game between competing interest groups over the control of organizational resources. Power relations are generated and power is accumulated to the divisions that have control of scarce organizational resources or to those who cope most successfully with uncertainty. Accounting information is used as an argument that justifies demands from organizational actors or for the rationalization of decisions made.peer-reviewe
Validity of the Gor'kov expansion near the upper critical field in type II superconductors
We have examined the validity of the Gor'kov expansion in the strength of the
order parameter of type II superconductors near the upper critical field.
Although the degeneracy of the electron levels in a magnetic field gives non-
perturbative terms in the solution to the Bogoliubov-de Gennes equations we
find, contrary to recent claims, that these non-perturbative terms cancel in
the expression for the thermodynamic potential, and that the traditional
Gor'kov theory is correct sufficiently close to Hc2 at finite temperature. We
have derived conditions for the validity of the Gor'kov theory which
essentially state, that the change in the quasiparticle energies as compared to
the normal state energies cannot be too large compared to the temperature.Comment: 5 pages, 3 figures. One reference adde
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