388 research outputs found
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An Optimization Based Design Framework for Multi-Functional 3D Printing
This work investigates design analysis and optimization methods for the integration of
active internal systems into a component for manufacture using multi-material 3D printing
processes. This enables efficient design of optimal multifunctional components that exploit the
design freedoms of additive manufacturing (AM). The main contributions of this paper are in two
areas: 1) the automated placement and routing of electrical systems within the component volume
and, 2) the accommodation of the effect of this system integration on the structural response of
the part through structural topology optimization (TO). A novel voxel modeling approach was
used to facilitate design flexibility and to allow direct mapping to the 3D printer jetting nozzles.Mechanical Engineerin
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Design Optimization Strategy for Multifunctional 3D Printing
An optimization based design methodology for the additive manufacture of multifunctional parts (for example, a structure with embedded electronic/electrical systems and
associated conductive paths) is presented. This work introduces a coupled optimization strategy
where Topology Optimization (TO) is combined with an automated placement and routing
approach that enables determination of an efficient internal system configuration. This permits
the effect of the incorporation of the internal system on the structural response of the part to be
taken into account and therefore enables the overall optimization of the structure-system unit. An
example test case is included in the paper to evaluate the optimization strategy and demonstrate
the methods effectiveness. The capability of this method allows the exploitation of the
manufacturing capability under development within the Additive Manufacturing (AM)
community to produce 3D internal systems within complex structures.Mechanical Engineerin
Evidence of Twisting and Mixed-polarity Solar Photospheric Magnetic Field in Large Penumbral Jets: IRIS and Hinode Observations
A recent study using {\it Hinode} (SOT/FG) data of a sunspot revealed some
unusually large penumbral jets that often repeatedly occurred at the same
locations in the penumbra, namely at the tail of a penumbral filament or where
the tails of multiple penumbral filaments converged. These locations had
obvious photospheric mixed-polarity magnetic flux in \NaI\ 5896 Stokes-V images
obtained with SOT/FG. Several other recent investigations have found that
extreme ultraviolet (EUV)/X-ray coronal jets in quiet Sun regions (QRs),
coronal holes (CHs) and near active regions (ARs) have obvious mixed-polarity
fluxes at their base, and that magnetic flux cancellation prepares and triggers
a minifilament flux-rope eruption that drives the jet. Typical QR, CH, and AR
coronal jets are up to a hundred times bigger than large penumbral jets, and in
EUV/X-ray images show clear twisting motion in their spires. Here, using IRIS
\MgII\ k 2796 \AA\ SJ images and spectra in the penumbrae of two sunspots we
characterize large penumbral jets. We find redshift and blueshift next to each
other across several large penumbral jets, and interpret these as untwisting of
the magnetic field in the jet spire. Using Hinode/SOT (FG and SP) data, we also
find mixed-polarity magnetic flux at the base of these jets. Because large
penumbral jets have mixed-polarity field at their base and have twisting motion
in their spires, they might be driven the same way as QR, CH and AR coronal
jets.Comment: 18 pages, 11 figures; to appear in Ap
MAT-759: PARTICLE SIZE ANALYSIS AS A MEANS TO BETTER UNDERSTAND THE INFLUENCE OF FLY ASH VARIABILITY IN CONCRETE
Fly ash is generated from thermal power stations as an industrial by-product of coal combustion materials. Its particles are generally glassy, spherical in shape, and typically range in size from 0.5-300 µm. Coal fly ash is widely used as a partial cementitious material in concrete, which not only offers economic and environmental benefits but also improves concrete performance. However, variability of the physical description and chemical composition of fly ash has been considered to be a major barrier to its increased use in cement and concrete. In this study the variability and properties of fly ash are characterized with an emphasis on particle size analysis as a means for fly ash producers to better understand material properties in relation to the process of production, classification, and potential modes of utilization. Fly ash samples were collected from different coal-fired power plants from certain Indian and Canadian sources. The particle size analysis results using Laser Diffraction Technique showed a wide variation between the particle size distributions of the studied sources. However, no correlation between the varied size distributions and chemical compositions of fly ash samples was found. Laboratory experiments on the selected fly ash samples are being undertaken to correlate fly ash characteristics and their effects on the performance of concrete mixtures with cementitious replacement level up to 50%
The Cause of Faint Coronal Jets from Emerging-Flux Regions in Solar Coronal Holes
Coronal jets are transient thin bursts of magnetically channeled solar material from the surface into the corona. They are brightest at their base, with a bright point (jet bright point, JBP) at an edge of the base. Early studies (Shibata et al. 1992) suggested that jets result from magnetic flux emergence: a small bipole emerges into unipolar ambient field, driving the jet and forming the JBP via interchange reconnection. More recent studies, using higher-cadence, higher-resolution, and broader wavelength coverage than before, show that prominent coronal jets are usually driven by a minifialment eruption (Sterling et al. 2015), and that, rather than flux emergence, flux cancelation usually prepares and triggers the eruption (Panesar et al. 2016). Here, we analyzed eight emerging flux regions to determine whether the emerging flux directly drove any coronal jets. We used EUV images from the Solar Dynamics Observatory (SDO)/Atmospheric Imaging Assembly (AIA) (in 304, 171, 211, 193, and 94 channels), and magnetograms from SDO/Helioseismic & Magnetic Imager (HMI). All eight regions produced jet-like features that were weak in intensity (faint jets), by which we mean they were so faint that we likely would not have identified them as jets had we initially searched for jets in AIA movies alone (as in, e.g., Panesar et al. 2016, Moore et al. 2013) without knowing whether the base was an emerging bipole. In seven of the eight regions, all jets (faint or prominent) erupted from locations where one leg of the emerging bipole was evidently canceling with an ambient opposite-polarity flux clump. The eighth case, the one that had the fastest flux emergence, possibly made faint jets by the flux-emergence mechanism, but these too might instead have resulted from flux cancelation
A CME-Producing Solar Eruption from the Interior of an Emerging Bipolar Active Region
In a negative-polarity coronal hole, magnetic flux emergence, seen by the Solar Dynamics Observatory's {SDO) Helioseismic Magnetic lmager (HMI), begins at approximately 19:00 UT on March 3, 2016. The emerged magnetic field produced sunspots, which NOAA numbered 12514 two days later. The emerging magnetic field is largely bipolar with the opposite-polarity fluxes spreading apart overall, but there is simultaneously some convergence and cancellation of opposite-polarity flux at the polarity inversion line (PIL) inside the emerging bipole. In the first fifteen hours after emergence onset, three obvious eruptions occur, observed in the coronal EUV images from SDO's Atmospheric Imaging Assembly (AIA). The first two erupt from separate segments of the external PIL between the emerging positve-polarity flux and the extant surrounding negative-polarity flux, with the exploding magnetic field being prepared and triggered by flux cancellation at the external PIL. The emerging bipole shows obvious overall left-handed shear and/or twist in its magnetic field. The focus of th is poster is the third and largest eruption, which comes from inside the emerging bipole and blows it open to produce a CME observed by SOHO/LASCO. That eruption is preceded by flux cancellation at the emerging bipole's interior PIL, cancellation that plausibly builds a sheared and twisted flux rope above the interior PIL and finally triggers the blow-out eruption of the flux rope via photospheric-convectiondriven slow tether-cutting reconnection of the legs of the sheared core field, low above the interior PIL, as proposed by van Ballegooijen & Martens (1989) and Moore & Roumeliotis (1992). The production of this eruption is a (perhaps rare) counterexample to solar eruptions that result from external collisional shearing between opposite polarities from two distinct emerging and/or emerged bipoles (Chintzoglou et al. 2019)
Utilization of agro-industrial residues for the production of β-Galactosidase using fungal isolate under solid state fermentation conditions
β-Galactosidase is an enzyme of commercial importance owing to its multiple benefits. Among all microbial sources, fungal species are of great interest for the production of this enzyme. Thus, the aim of this present work was to optimize the media as well as process parameters to achieve maximum β-Galactosidase production by solid state fermentation using the fungal isolate Rhizomucor pusillus. Various agro-industrial residues were tested for carbon as well as for nitrogen sources. The different process parameters were also studied to observe their effects on β-galactosidase production. Among all screened agro-industrial residues, wheat bran and corn steep liquor had the potential to be used as carbon and nitrogen sources, respectively; whereas MgSO4 was found to be a suitable salt supplement. The optimal process parameters included particle size of 1000 microns, 50% moisture content, pH 5.5, 50 ºC temperature, and 7 days of fermentation
Invisibility of Solar Active Region Umbra-to-Umbra Coronal Loops: New Evidence that Magnetoconvection Drives Solar-Stellar Coronal Heating
Coronal heating generally increases with increasing magnetic field strength: the EUV/X-ray corona in active regions is 10--100 times more luminous and 2--4 times hotter than that in quiet regions and coronal holes, which are heated to only about 1.5 MK, and have fields that are 10--100 times weaker than that in active regions. From a comparison of a nonlinear force-free model of the three-dimensional active region coronal field to observed extreme-ultraviolet loops, we find that (1) umbra-to-umbra coronal loops, despite being rooted in the strongest magnetic flux, are invisible, and (2) the brightest loops have one foot in an umbra or penumbra and the other foot in another sunspot's penumbra or in unipolar or mixed-polarity plage. The invisibility of umbra-to-umbra loops is new evidence that magnetoconvection drives solar-stellar coronal heating: evidently, the strong umbral field at both ends quenches the magnetoconvection and hence the heating. Our results from EUV observations and nonlinear force-free modeling of coronal magnetic field imply that, for any coronal loop on the Sun or on any other convective star, as long as the field can be braided by convection in at least one loop foot, the stronger the field in the loop, the stronger the coronal heating
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