2,271 research outputs found
Induced Growth of Asymmetric Nanocantilever Arrays on Polar Surfaces
©2003 The American Physical Society. The electronic version of this article is the complete one and can be found online at: http://link.aps.org/doi/10.1103/PhysRevLett.91.185502DOI: 10.1103/PhysRevLett.91.185502We report that the Zn-terminated ZnO (0001) polar surface is chemically active and the oxygenterminated (0001) polar surface is inert in the growth of nanocantilever arrays. Longer and wider "comblike" nanocantilever arrays are grown from the (0001)-Zn surface, which is suggested to be a self-catalyzed process due to the enrichment of Zn at the growth front. The chemically inactive
(0001)-O surface typically does not initiate any growth, but controlling experimental conditions could lead to the growth of shorter and narrower nanocantilevers from the intersections between (0001)-O with (0110) surfaces
Extremely-Fast, Energy-Efficient Massive MIMO Precoding with Analog RRAM Matrix Computing
Signal processing in wireless communications, such as precoding, detection,
and channel estimation, are basically about solving inverse matrix problems,
which, however, are slow and inefficient in conventional digital computers,
thus requiring a radical paradigm shift to achieve fast, real-time solutions.
Here, for the first time, we apply the emerging analog matrix computing (AMC)
to the linear precoding of massive MIMO. The real-valued AMC concept is
extended to process complex-valued signals. In order to adapt the MIMO channel
models to RRAM conductance mapping, a new matrix inversion circuit is
developed. In addition, fully analog dataflow and optimized operational
amplifiers are designed to support AMC precoding implementation. Simulation
results show that the zero-forcing precoding is solved within 20 ns for a
16x128 MIMO system, which is two orders of magnitude faster than the
conventional digital approach. Meanwhile, the energy efficiency is improved by
50x.Comment: Submitted to an IEEE journal for possible publicatio
Normalized ground state solutions for the fractional Sobolev critical NLSE with an extra mass supercritical nonlinearity
This paper is concerned with existence of normalized ground state solutions
for the mass supercritical fractional nonlinear Schr\"{o}dinger equation
involving a critical growth in the fractional Sobolev sense. The compactness of
Palais-Smale sequences is obtained by a special technique, which borrows from
the ideas of Soave (J. Funct. Anal. 279 (6) (2020) 1086102020). This paper
represents an extension of previously known results - in the local and the
nonlocal cases
Microstructures and constituents of super-high strength aluminum alloy ingots made through LFEC process
Ingots of a new super-high strength Al-Zn-Mg-Cu-Zr alloy were produced respectively by low frequency electromagnetic casting (LFEC) and by conventional direct chill (DC) casting process. Microstructure and constituents of the ingots were studied. The results indicated that the LFEC process significantly refines microstructure and constituents of the alloy, and to some extent, decreases the area (or volume) fraction of constituents and eutectic structure precipitated at grain boundaries. But, no difference in the type of constituents was observed between LFEC and DC ingots. The results also showed LFEC process can improve the as-cast mechanical properties
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