1,954 research outputs found
A NETWORK LINK PREDICTION MODEL BASED ON OBJECT-OBJECT MATCH METHOD
In this paper, we proposed and evaluated a new network link prediction method that can be used to predict missing links in a social network. In the proposed model, to improve the prediction accuracy, the network link prediction problem is transformed to a general object-object match prediction problem, in which the nodes of a network are regarded as objects and the neighbors of a node are regarded as the node\u27s associated features. Also a machine learning framework is devised for the systematic prediction. We compare the prediction accuracy of the proposed method with existing network link prediction methods using well-known network datasets such as a scientific co-authorship network, an e-mail communication network, and a product co-purchasing network. The results showed that the proposed approach made a significant improvement in all three networks. Also it reveals that considering the neighbor\u27s neighbors are critical to improve the prediction accuracy
Physical Origin and Generic Control of Magnonic Band Gaps of Dipole-Exchange Spin Waves in Width-Modulated-Nanostrip Waveguides
We report, for the first time, on a novel planar structure of
magnonic-crystal waveguides, made of a single magnetic material, in which the
allowed and forbidden bands of propagating dipole-exchange spin-waves can be
manipulated by the periodic modulation of different widths in thin-film
nanostrips. The origin of the presence of several magnonic wide band gaps and
the crucial parameters for controlling those band gaps of the order of ~10 GHz
are found by micromagnetic numerical and analytical calculations. This work can
offer a route to the potential application to broad-band spin-wave filters in
the GHz frequency range.Comment: 24 pages, 8 figure
Characteristics of R134a/R410A Cascade Heat Pump and Optimization
Single stage air source heat pump has been widely used around the world. However, it has some drawback, for example, deteriorated heating capacity and COP in cold ambient temperature. To overcome these disadvantages, cascade cycle has been suggested and shows better performance at low ambient temperature. Cascade cycle has smaller compression ratio at each cycle and shows higher compression efficiency compared to that of single stage cycle. Intermediate pressure is most critical parameter which decides the system performance. There have been many research studies about cascade heat pump system using NH3/CO2 and C3H8/CO2 as refrigerants at high and low stage, respectively. Most studies conducted on system optimization, finding the optimal intermediate pressure. However, little information has given about the experimental optimization results. In this study, AWHP (air to water heat pump), which is composed by two single stage cycle, was studied experimentally. AWHP high and low cycle adopts R134a and R410A as refrigerants, respectively, because critical temperature of R134a is higher than R410A. Since there are two single stage cycles, each cycle has a different compression ratio. In this research, by introducing numerical analysis, system optimization was studied. Characteristics of cascade cycle with respect to each compressor have been also studied. Experiment was conducted with various operating conditions; ambient temperature, water inlet temperature
Normal modes of coupled vortex gyration in two spatially separated magnetic nanodisks
We found from analytical derivations and micromagnetic numerical simulations
that there exist two distinct normal modes in apparently complex vortex
gyrotropic motions in two dipolar-coupled magnetic nanodisks. The normal modes
have characteristic higher and lower single angular eigenfrequencies with their
own elliptical orbits elongated along the x (bonding axis) and y axes,
respectively. The superposition of the two normal modes results in coupled
vortex gyrations, which depend on the relative vortex-state configuration in a
pair of dipolar-coupled disks. This normal-mode representation is a simple
means of understanding the observed complex vortex gyrations in two or more
dipolar-interacting disks of various vortex-state configurations.Comment: 18 pages, 3 figures, 1 tabl
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