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41.
Fast heuristic principle for spare capacity placement inmesh-restorable SONET/SDH transport networks
The authors propose a useful new insight into the problem of spare capacity design for mesh-restorable networks. A straightforward heuristic of average case complexity O(S) based on the new principle is within 21% (13% on average) of the minimum capacity and runs 8.5-80 times faster than the optimal integer program (IF). Application to evaluate benefits from six new span addition candidates in a 53 node, 81 span network yielded the correct rank-order of merit 650 times faster than optimal methods. This contributes to a practical assault on the problem of finding the globally best single or multiple new span additions in the evolution of large transport networks 相似文献
42.
We study theoretically the destruction of spin nematic order due to quantum fluctuations in quasi-one-dimensional spin-1 magnets. If the nematic ordering is disordered by condensing disclinations, then quantum Berry phase effects induce dimerization in the resulting paramagnet. We develop a theory for a Landau-forbidden second order transition between the spin nematic and dimerized states found in recent numerical calculations. Numerical tests of the theory are suggested. 相似文献
43.
44.
MacGregor M. Grover W.D. Maydell U.M. 《Selected Areas in Communications, IEEE Journal on》1993,11(9):1461-1469
This paper presents a metric for managing dynamically reconfigurable transport networks. In such networks, one physical set of transport links can be configured into many different logical networks, in order to meet uncertain and volatile traffic demands. Connectability is a figure of merit for capturing the composite routing efficiency and capacity utilization of a transport network. Connectability is mathematically inspired by existing metrics for reliability. Reliability concepts are adapted to quantify notions of efficiency in reconfigurable networks. The authors define connectability mathematically, and set out a procedure for its' calculation in a distributed real-time setting. The centralized version of this calculation has O(n log n) time complexity. A series of simulation studies are presented to illustrate the use of connectability in characterizing strategies for transport network reconfiguration. One strategy based on the isolated calculation of connectability at each node is shown to yield lower blocking and more efficient use of transport network resources than the other strategies tested. Finally, a short study of applying connectability to restoration in a national network demonstrates that there is a continuum along which restoration can be temporarily traded off against transport network management 相似文献
45.
Analysis for the transient response of a simply supported three layer viscoelastically damped sandwich plate, subjected to a half sine shock pulse, has been carried out, with account taken of the transverse inertia effects only. The properties of the viscoelastic core material have been represented by those of a four element viscoelastic model. The influences of the variation of various geometrical and physical parameters of the damped sandwich plate on the shock response are investigated. The decay rate of the transverse vibrations of the plate is evaluated in terms of the logarithmic decrement. 相似文献
46.
A quantitative study of the contrast of Young's fringes obtained with a fully scattering element by double exposure technique as a function of the inclination of the incident beam and the effect of varying the scatterer- photographic plate distance upon the γ - θ curve have been presented. 相似文献
47.
The importance of direct current transfer between stages of switching circuits is illustrated with reference to conventional circuits using noncomplementary transistors. It is shown that an implicit configuration of flip?flop amplifier has particular advantages, which increase under worst-case design conditions. 相似文献
48.
Horace Grover 《Experimental Mechanics》1972,12(5):250-256
It is impossible to find, for a specific design concern, fatigue information that is entirely adequate for an exact quantitative evaluation. Some of the approaches available for approximate design estimates are described to illustrate the problems that may occur and the considerations important in using available fatigue information in design. 相似文献
49.
The Bi2Sr2CaCu2O8 system is viewed as an archetypal of superconductors modelled as Josephson coupled CuO2 bilayers. The isothermal and temperature dependent DC and AC magnetization measurements forH‖c in a single crystal of Bi2212 have been performed. Qualitative changes are observed to occur over a narrow range of temperature
values before reaching the superconducting-normal transition. The observed behaviour can be ascribed to the rapid variation
in the strength of the coupling between the superconducting CuO2 planes (i.e., bilayers in the case of Bi2212). Strongly coupled planes behave like a 3D superconductor, whereas weakly coupled
planes have a two component response attributable to 2D planes and interplanar couplings. We believe that this paper is a
plethora of new findings. Our observations imply that resistivity across the planes becomes zero earlier than that within
the planes. A new line (designated asH
2D(T)) above which the change in the electromagnetic response is dominated by quasi 2D-planes has been determined for the first
time. This paper also contains the first observation of Differential Diamagnetic Effect (DDE) in the In-phase AC susceptibility
data which signals the onset (atT
2D(H)) of dominance of response from 2D-planes. In addition to a host of interesting thermomagnetic history effects which are
a consequence of interplay between the diamagnetic responses from the two components, a comparison of irreversibility lines
(of the 3D state) determined by different methods on the same specimen of a HTSC is also being presented for the first time.
We have come across Paramagnetic Meissner Effect (PME), first recognized in ceramic samples of Bi2212, in the temperature
region of dimensional crossover in our single crystal sample, whichinter-alia confirms our labelling of the two component behaviour. A schematic phase diagram summarizing the various transformations
that can occur nearT
c in the electromagnetic response of an anisotropic layered system has been drawn. 相似文献
50.
The authors describe an alternative to the method of least squares (LS) for estimating the location of a subscriber in a mobile radio system through hyperbolic trilateration with multipath corrupted ranging estimates. In simulation trials, the new approach reduced the multipath limited error by 30-500% relative to the LS method. This contributes to location finding applications without needing GPS receivers in mobiles or phased arrays at the base stations to combat multipath 相似文献