3,501 research outputs found
The reflex-free hull
No full textWe propose a hull operator, the reflex-free hull, that allows us to define a 3D analogue to bays in polygons. The reflex-free hull allows a rich set of topological types, yet for polyhedral input with n edges, it remains a polyhedral set with O(n) edges. This is in contrast to other possible hull definitions that give non-planar surfaces and higher combinatorial complexity. The reflex-free hull is related to identifying cavities in computer aided design and manufacturing, but we sketch examples to indicate that computing a reflex-free hull will be a challenging problem.Brain Korea 21 program of MOE (Ahn), RGC CERG HKUST 6074/97E (Cheng) and NSF grants 9988742 and 0076984 (Snoeyink)
Post-fabrication tuning of a polymeric grating-assisted codirectional coupler filter by photobleaching
No full textWe present a convenient post-fabrication tuning method that uses photobleaching to adjust the center wavelength of the polymeric grating-assisted codirectional coupler filter. The passive polymer waveguide is used as a low-loss optical path and the electro-optic (EO) polymer waveguide is used for dropping the optical signal at a given wavelength. Photobleaching reduces the effective index of the EO polymer waveguide, which makes it possible to adjust the center wavelength. We call easily realize the filters with a desired center wavelength by exposing ultraviolet light on them with a proper energy even after finishing the device fabrication. The center wavelength is decreased by 25 nm with a photobleaching energy of 180 J/cm(2) without extra loss. (C) 2001 Elsevier Science B.V. All rights reserved
Grating-assisted codirectional coupler filter using electro-optic and passive polymer waveguides
No full textMSSQ: Manhattan Spatial Skyline Queries
No full textSkyline queries have gained attention lately for supporting effective retrieval over massive spatial data. While efficient algorithms have been studied for spatial skyline queries using the Euclidean distance, these algorithms are (1) still quite computationally intensive and (2) unaware of the road constraints. Our goal is to develop a more efficient algorithm for L-1 distance, also known as Manhattan distance, which closely reflects road network distance for metro areas. We present a simple and efficient algorithm which, given a set P of data points and a set Q of query points in the plane, returns the set of spatial skyline points in just O(vertical bar P vertical bar log vertical bar P vertical bar) time, assuming that vertical bar Q vertical bar <= vertical bar P vertical bar. This is significantly lower in complexity than the best known method. In addition to efficiency and applicability, our algorithm has another desirable property of independent computation and extensibility to L-infinity norm distance, which naturally invites parallelism and widens applicability. Our extensive empirical results suggest that our algorithm outperforms the state-of-the-art approaches by orders of magnitude. We also present efficient algorithms that report the changes of the skyline points when single or multiple query points move along the x- or y-axis. (C) 2013 Elsevier Ltd. All rights reserved.X1199Nsciescopu
EFFECT OF STRESS FREQUENCY ON THE CYCLIC CREEP-BEHAVIOR OF ZIRCALOY-4 IN THE DYNAMIC STRAIN AGING TEMPERATURE-RANGE
No full textPolymeric digital optical modulator based on asymmetric branch
No full textA digital optical modulator based on an asymmetric Y-branch waveguide is proposed and fabricated by using an electro-optic polymer. The operating point is initially shifted to the off-state utilising the asymmetry in the branch to provide an initial zero-tate with no electrical bias. It has been confirmed that the high extinction ratio can be obtained with a low drive voltage. An extinction ratio of 25 dB is demonstrated for a drive voltage of 20V using a polymer, PMMA-DR1 with r(33) of 5pm/V at 1.3 mum
A study on ray tracing method for CFD simulations of laser keyhole welding: Progressive Search Method
No full textHigh extinction ratio digital optical modulator based on the asymmetric Y-branch waveguide in electro-optic polymer
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