4,841 research outputs found
Dependence of the Spin Transfer Torque Switching Current Density on the Exchange Stiffness Constant
We investigate the dependence of the switching current density on the
exchange stiffness constant in the spin transfer torque magnetic tunneling
junction structure with micromagnetic simulations. Since the widely accepted
analytic expression of the switching current density is based on the macro-spin
model, there is no dependence of the exchange stiffness constant. When the
switching is occurred, however, the spin configuration forms C-, S-type, or
complicated domain structures. Since the spin configuration is determined by
the shape anisotropy and the exchange stiffness constant, the switching current
density is very sensitive on their variations. It implies that there are more
rooms for the optimization of the switching current density with by controlling
the exchange stiffness constant, which is determined by composition and the
detail fabrication processes
Oracle Based Active Set Algorithm for Scalable Elastic Net Subspace Clustering
State-of-the-art subspace clustering methods are based on expressing each
data point as a linear combination of other data points while regularizing the
matrix of coefficients with , or nuclear norms.
regularization is guaranteed to give a subspace-preserving affinity (i.e.,
there are no connections between points from different subspaces) under broad
theoretical conditions, but the clusters may not be connected. and
nuclear norm regularization often improve connectivity, but give a
subspace-preserving affinity only for independent subspaces. Mixed ,
and nuclear norm regularizations offer a balance between the
subspace-preserving and connectedness properties, but this comes at the cost of
increased computational complexity. This paper studies the geometry of the
elastic net regularizer (a mixture of the and norms) and uses
it to derive a provably correct and scalable active set method for finding the
optimal coefficients. Our geometric analysis also provides a theoretical
justification and a geometric interpretation for the balance between the
connectedness (due to regularization) and subspace-preserving (due to
regularization) properties for elastic net subspace clustering. Our
experiments show that the proposed active set method not only achieves
state-of-the-art clustering performance, but also efficiently handles
large-scale datasets.Comment: 15 pages, 6 figures, accepted to CVPR 2016 for oral presentatio
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