7,423 research outputs found
New Geometric Algorithms for Fully Connected Staged Self-Assembly
We consider staged self-assembly systems, in which square-shaped tiles can be
added to bins in several stages. Within these bins, the tiles may connect to
each other, depending on the glue types of their edges. Previous work by
Demaine et al. showed that a relatively small number of tile types suffices to
produce arbitrary shapes in this model. However, these constructions were only
based on a spanning tree of the geometric shape, so they did not produce full
connectivity of the underlying grid graph in the case of shapes with holes;
designing fully connected assemblies with a polylogarithmic number of stages
was left as a major open problem. We resolve this challenge by presenting new
systems for staged assembly that produce fully connected polyominoes in O(log^2
n) stages, for various scale factors and temperature {\tau} = 2 as well as
{\tau} = 1. Our constructions work even for shapes with holes and uses only a
constant number of glues and tiles. Moreover, the underlying approach is more
geometric in nature, implying that it promised to be more feasible for shapes
with compact geometric description.Comment: 21 pages, 14 figures; full version of conference paper in DNA2
Identification of nonlinear kinematic hardening constitutive model parameters using the virtual fields method for advanced high strength steels
In this work, the nonlinear kinematic hardening combined with Voce isotropic hardening was selected to characterize the material behavior of advanced high strength steel sheet samples subjected to a few reverse loading cycles. Multi-components of backstress were considered for the combined nonlinear kinematical hardening model, namely, one, two, and three backstress components. To calibrate the model, an inverse problem solution tool, so-called virtual fields method, which takes full advantage of full-field deformation measurement, was applied to identify the material constitutive parameters. First, finite element simulations of forward-reverse simple shear were performed to validate the proposed identification method. The influence of strain noise on the identification accuracy was also evaluated. Then, the proposed method was applied to three kinds of sheet metals (DP600, TRIP780 and TWIP980) tested under two cycles of forward-reverse simple shear for parameter identification. The identification results obtained with different number of backstress components were critically discussed. (C) 2016 Elsevier Ltd. All rights reserved.1132Ysciescopu
Controlling mode orientations and frequencies in levitated cavity optomechanics
Cavity optomechanics offers quantum cooling, quantum control and measurement
of small mechanical oscillators. However the optical backactions that underpin
quantum control can significantly disturb the oscillator modes: mechanical
frequencies are shifted by the optical spring effect and light-matter
hybridisation in strong coupling regimes; mechanical modes hybridise with each
other via the cavity mode. This is even more pertinent in the field of
levitated optomechanics, where optical trapping fully determines the mechanical
modes and their frequencies. Here, using the coherent-scattering (CS) set-up
that allowed quantum ground state cooling of a levitated nanoparticle, we show
that -- when trapping away from a node of the cavity standing wave -- the CS
field opposes optical spring shifts and mechanical mode hybridisation. At an
optimal cancellation point, independent of most experimental parameters, we
demonstrate experimentally that it is possible to strongly cavity cool and
control the {\em unperturbed} modes. Suppression of the cavity-induced mode
hybridisation in the plane is quantified by measuring the
correlation spectra which are seen to always be
anti-correlated except at the cancellation point where they become
uncorrelated. The findings have implications for directional force sensing
using CS set-ups
Wavelength-multiplexed duplex transceiver based on III-V/Si hybrid integration for off-chip and on-chip optical interconnects
A six-channel wavelength-division-multiplexed optical transceiver with a compact footprint of 1.5 x 0.65 mm(2) for off-chip and on-chip interconnects is demonstrated on a single silicon-on-insulator chip. An arrayed waveguide grating is used as the (de)multiplexer, and III-V electroabsorption sections fabricated by hybrid integration technology are used as both modulators and detectors, which also enable duplex links. The 30-Gb/s capacity for each of the six wavelength channels for the off-chip transceiver is demonstrated. For the on-chip interconnect, an electrical-to-electrical 3-dB bandwidth of 13 GHz and a data rate of 30 Gb/s per wavelength are achieved
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Simplified Rolled Technique at Implantâ Uncovering Surgery for Correcting Horizontal Ridge Defect
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/142141/1/cap0140.pd
The Directed Dominating Set Problem: Generalized Leaf Removal and Belief Propagation
A minimum dominating set for a digraph (directed graph) is a smallest set of
vertices such that each vertex either belongs to this set or has at least one
parent vertex in this set. We solve this hard combinatorial optimization
problem approximately by a local algorithm of generalized leaf removal and by a
message-passing algorithm of belief propagation. These algorithms can construct
near-optimal dominating sets or even exact minimum dominating sets for random
digraphs and also for real-world digraph instances. We further develop a core
percolation theory and a replica-symmetric spin glass theory for this problem.
Our algorithmic and theoretical results may facilitate applications of
dominating sets to various network problems involving directed interactions.Comment: 11 pages, 3 figures in EPS forma
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