1,970 research outputs found
Binary superlattice design by controlling DNA-mediated interactions
Most binary superlattices created using DNA functionalization or other
approaches rely on particle size differences to achieve compositional order and
structural diversity. Here we study two-dimensional (2D) assembly of
DNA-functionalized micron-sized particles (DFPs), and employ a strategy that
leverages the tunable disparity in interparticle interactions, and thus
enthalpic driving forces, to open new avenues for design of binary
superlattices that do not rely on the ability to tune particle size (i.e.,
entropic driving forces). Our strategy employs tailored blends of complementary
strands of ssDNA to control interparticle interactions between micron-sized
silica particles in a binary mixture to create compositionally diverse 2D
lattices. We show that the particle arrangement can be further controlled by
changing the stoichiometry of the binary mixture in certain cases. With this
approach, we demonstrate the abil- ity to program the particle assembly into
square, pentagonal, and hexagonal lattices. In addition, different particle
types can be compositionally ordered in square checkerboard and hexagonal -
alternating string, honeycomb, and Kagome arrangements.Comment: 4 figures in the main text. 5 figures in the supplementary
informatio
Multifunction tests of a frequency domain based flutter suppression system
The process is described of analysis, design, digital implementation, and subsonic testing of an active control flutter suppression system for a full span, free-to-roll wind tunnel model of an advanced fighter concept. The design technique uses a frequency domain representation of the plant and used optimization techniques to generate a robust multi input/multi output controller. During testing in a fixed-in-roll configuration, simultaneous suppression of both symmetric and antisymmetric flutter was successfully shown. For a free-to-roll configuration, symmetric flutter was suppressed to the limit of the tunnel test envelope. During aggressive rolling maneuvers above the open-loop flutter boundary, simultaneous flutter suppression and maneuver load control were demonstrated. Finally, the flutter damping controller was reoptimized overnight during the test using combined experimental and analytical frequency domain data, resulting in improved stability robustness
A Low-Dimensional Representation for Robust Partial Isometric Correspondences Computation
Intrinsic isometric shape matching has become the standard approach for pose
invariant correspondence estimation among deformable shapes. Most existing
approaches assume global consistency, i.e., the metric structure of the whole
manifold must not change significantly. While global isometric matching is well
understood, only a few heuristic solutions are known for partial matching.
Partial matching is particularly important for robustness to topological noise
(incomplete data and contacts), which is a common problem in real-world 3D
scanner data. In this paper, we introduce a new approach to partial, intrinsic
isometric matching. Our method is based on the observation that isometries are
fully determined by purely local information: a map of a single point and its
tangent space fixes an isometry for both global and the partial maps. From this
idea, we develop a new representation for partial isometric maps based on
equivalence classes of correspondences between pairs of points and their
tangent spaces. From this, we derive a local propagation algorithm that find
such mappings efficiently. In contrast to previous heuristics based on RANSAC
or expectation maximization, our method is based on a simple and sound
theoretical model and fully deterministic. We apply our approach to register
partial point clouds and compare it to the state-of-the-art methods, where we
obtain significant improvements over global methods for real-world data and
stronger guarantees than previous heuristic partial matching algorithms.Comment: 17 pages, 12 figure
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