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A Process Planning Method and Data Format for Achieving Tolerances in Stereolithography
When building parts in a stereolithography apparatus (SLA), the user is faced with many decis!ons
regarding the setting of process variables. To 'achieve a set of tolera~ces as closely as pOSSIble,
relationships between part geometry, tolerances, and process v~nables ~ust be understood
quantitatively. This paper presents a method for SLA process plannIng that IS based on response
surface methodology and multi-objective optimization, where the response surfaces capture these
relationships. These response surfaces were generated by extensive design-of-experiment studies
for a variety of geometries. An annotated STL data format is also presented that enables the
inclusion of tolerance and surface information in fatetted representations. Application of the data
format and process planning method is illustrated on one part.Mechanical Engineerin
Sustained Veggie: Considerations for Consistent On-Orbit Leafy Green Production
No abstract availabl
Finding local community structure in networks
Although the inference of global community structure in networks has recently
become a topic of great interest in the physics community, all such algorithms
require that the graph be completely known. Here, we define both a measure of
local community structure and an algorithm that infers the hierarchy of
communities that enclose a given vertex by exploring the graph one vertex at a
time. This algorithm runs in time O(d*k^2) for general graphs when is the
mean degree and k is the number of vertices to be explored. For graphs where
exploring a new vertex is time-consuming, the running time is linear, O(k). We
show that on computer-generated graphs this technique compares favorably to
algorithms that require global knowledge. We also use this algorithm to extract
meaningful local clustering information in the large recommender network of an
online retailer and show the existence of mesoscopic structure.Comment: 7 pages, 6 figure
Moving Difference (MDIFF) Non-adiabatic Rapid Sweep (NARS) EPR of Copper(II)
Non-adiabatic rapid sweep (NARS) EPR spectroscopy has been introduced for application to nitroxide-labeled biological samples (Kittell et al., 2011). Displays are pure absorption, and are built up by acquiring data in spectral segments that are concatenated. In this paper we extend the method to frozen solutions of copper-imidazole, a square planar copper complex with four in-plane nitrogen ligands. Pure absorption spectra are created from concatenation of 170 5-gauss segments spanning 850 G at 1.9 GHz. These spectra, however, are not directly useful since nitrogen superhyperfine couplings are barely visible. Application of the moving difference (MDIFF) algorithm to the digitized NARS pure absorption spectrum is used to produce spectra that are analogous to the first harmonic EPR. The signal intensity is about four times higher than when using conventional 100 kHz field modulation, depending on line shape. MDIFF not only filters the spectrum, but also the noise, resulting in further improvement of the SNR for the same signal acquisition time. The MDIFF amplitude can be optimized retrospectively, different spectral regions can be examined at different amplitudes, and an amplitude can be used that is substantially greater than the upper limit of the field modulation amplitude of a conventional EPR spectrometer, which improves the signal-to-noise ratio of broad lines
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