28 research outputs found
Design of two-dimensional sharp-edged-throat supersonic nozzle with boundary-layer correction
Computer program accounts for effective nozzle geometry changes due to boundary layer displacement thickness. Program input and output are discussed
Asteroid models from the Lowell Photometric Database
We use the lightcurve inversion method to derive new shape models and spin
states of asteroids from the sparse-in-time photometry compiled in the Lowell
Photometric Database. To speed up the time-consuming process of scanning the
period parameter space through the use of convex shape models, we use the
distributed computing project Asteroids@home, running on the Berkeley Open
Infrastructure for Network Computing (BOINC) platform. This way, the
period-search interval is divided into hundreds of smaller intervals. These
intervals are scanned separately by different volunteers and then joined
together. We also use an alternative, faster, approach when searching the
best-fit period by using a model of triaxial ellipsoid. By this, we can
independently confirm periods found with convex models and also find rotation
periods for some of those asteroids for which the convex-model approach gives
too many solutions. From the analysis of Lowell photometric data of the first
100,000 numbered asteroids, we derived 328 new models. This almost doubles the
number of available models. We tested the reliability of our results by
comparing models that were derived from purely Lowell data with those based on
dense lightcurves, and we found that the rate of false-positive solutions is
very low. We also present updated plots of the distribution of spin obliquities
and pole ecliptic longitudes that confirm previous findings about a non-uniform
distribution of spin axes. However, the models reconstructed from noisy sparse
data are heavily biased towards more elongated bodies with high lightcurve
amplitudes
Asteroid models reconstructed from ATLAS photometry
The Asteroid Terrestrial-impact Last Alert System (ATLAS) is an all-sky
survey primarily aimed at detecting potentially hazardous near-Earth asteroids.
Apart from the astrometry of asteroids, it also produces their photometric
measurements that contain information about asteroid rotation and their shape.
To increase the current number of asteroids with a known shape and spin state,
we reconstructed asteroid models from ATLAS photometry that was available for
approximately 180,000 asteroids observed between 2015 and 2018. We made use of
the light-curve inversion method implemented in the Asteroid@home project to
process ATLAS photometry for roughly 100,000 asteroids with more than a hundred
individual brightness measurements. By scanning the period and pole parameter
space, we selected those best-fit models that were, according to our setup, a
unique solution for the inverse problem. We derived ~2750 unique models, 950 of
them were already reconstructed from other data and published. The remaining
1800 models are new. About half of them are only partial models, with an
unconstrained pole ecliptic longitude. Together with the shape and spin, we
also determined for each modeled asteroid its color index from the cyan and
orange filter used by the ATLAS survey. We also show the correlations between
the color index, albedo, and slope of the phase-angle function. The current
analysis is the first inversion of ATLAS asteroid photometry, and it is the
first step in exploiting the huge scientific potential that ATLAS photometry
has. ATLAS continues to observe, and in the future, this data, together with
other independent photometric measurements, can be inverted to produce more
refined asteroid models
Exploring Advanced Technology Gas Turbine Engine Design and Performance for the Large Civil Tiltrotor (LCTR)
A Large Civil Tiltrotor (LCTR) conceptual design was developed as part of the NASA Heavy Lift Rotorcraft Systems Investigation in order to establish a consistent basis for evaluating the benefits of advanced technology for large tiltrotors. The concept has since evolved into the second-generation LCTR2, designed to carry 90 passengers for 1,000 nautical miles at 300 knots, with vertical takeoff and landing capability. This paper explores gas turbine component performance and cycle parameters to quantify performance gains possible for additional improvements in component and material performance beyond those identified in previous LCTR2 propulsion studies and to identify additional research areas. The vehicle-level characteristics from this advanced technology generation 2 propulsion architecture will help set performance levels as additional propulsion and power systems are conceived to meet ever-increasing requirements for mobility and comfort, while reducing energy use, cost, noise and emissions. The Large Civil Tiltrotor vehicle and mission will be discussed as a starting point for this effort. A few, relevant engine and component technology studies, including previous LCTR2 engine study results will be summarized to help orient the reader on gas turbine engine architecture, performance and limitations. Study assumptions and methodology used to explore engine design and performance, as well as assess vehicle sizing and mission performance will then be discussed. Individual performance for present and advanced engines, as well as engine performance effects on overall vehicle size and mission fuel usage, will be given. All results will be summarized to facilitate understanding the importance and interaction of various component and system performance on overall vehicle characteristics
Preparation and antioxidant activity of albumin binding Salen Schiff-base metal complexes
A Study of the Effects of Magnetic Saturation and Spatial Harmonics on Isolated Salient-Pole Synchronous Generators
Motion of Chips When Leaving the Cutting Zone during Chipboard Plane Milling
ΠΡΠ»ΠΈ ΡΡΡΠ°Π½ΠΎΠ²Π»Π΅Π½Ρ ΠΌΠ°ΡΠ΅ΠΌΠ°ΡΠΈΡΠ΅ΡΠΊΠΈΠ΅ ΡΡΠ°Π²Π½Π΅Π½ΠΈΡ ΠΈ ΠΏΡΠΎΠ°Π½Π°Π»ΠΈΠ·ΠΈΡΠΎΠ²Π°Π½Ρ ΡΠ»Π΅Π΄ΡΡΡΠΈΠ΅ Π·Π°ΠΊΠΎΠ½ΠΎΠΌΠ΅ΡΠ½ΠΎΡΡΠΈ ΠΏΡΠΎΡΠ΅ΡΡΠ° ΠΏΠ»ΠΎΡΠΊΠΎΠ³ΠΎ ΡΡΠ΅Π·Π΅ΡΠΎΠ²Π°Π½ΠΈΡ Π΄ΡΠ΅Π²Π΅ΡΠ½ΡΡ
ΠΌΠ°ΡΠ΅ΡΠΈΠ°Π»ΠΎΠ²: Π²Π»ΠΈΡΠ½ΠΈΠ΅ ΡΠ³Π»Π° Π½Π°ΠΊΠ»ΠΎΠ½Π° ΡΠ΅ΠΆΡΡΠ΅ΠΉ ΠΊΡΠΎΠΌΠΊΠΈ Π½Π° ΡΠ³ΠΎΠ» Π²ΡΡ
ΠΎΠ΄Π° ΡΡΡΡΠΆΠΊΠΈ, Π²Π»ΠΈΡΠ½ΠΈΠ΅ ΡΠ³Π»Π° Π½Π°ΠΊΠ»ΠΎΠ½Π° ΡΠ΅ΠΆΡΡΠ΅ΠΉ ΠΊΡΠΎΠΌΠΊΠΈ Π½Π° ΡΠΊΠΎΡΠΎΡΡΡ Π΄Π²ΠΈΠΆΠ΅Π½ΠΈΡ ΡΡΡΡΠΆΠΊΠΈ Π²Π΄ΠΎΠ»Ρ Π»Π΅Π·Π²ΠΈΡ ΠΈ ΡΠΊΠΎΡΠΎΡΡΡ Π½Π° Π²ΡΡ
ΠΎΠ΄Π΅ ΡΡΡΡΠΆΠΊΠΈ ΠΈΠ· Π·ΠΎΠ½Ρ ΡΠ΅Π·Π°Π½ΠΈΡ, Π·Π°Π²ΠΈΡΠΈΠΌΠΎΡΡΡ ΡΠ³Π»Π° Π²ΡΡ
ΠΎΠ΄Π° ΡΡΡΡΠΆΠΊΠΈ ΠΎΡ ΠΊΠΎΡΡΡΠΈΡΠΈΠ΅Π½ΡΠΎΠ² ΡΡΠ΅Π½ΠΈΡ ΡΡΡΡΠΆΠΊΠΈ Π½Π° ΠΏΠΎΠ²Π΅ΡΡ
Π½ΠΎΡΡΠΈ ΠΎΠ±ΡΠ°Π±Π°ΡΡΠ²Π°Π΅ΠΌΠΎΠ³ΠΎ ΠΌΠ°ΡΠ΅ΡΠΈΠ°Π»Π° ΠΈ Π²Π΄ΠΎΠ»Ρ ΠΏΠΎΠ²Π΅ΡΡ
Π½ΠΎΡΡΠΈ Π»Π΅Π·Π²ΠΈΡ (ΠΊΠΎΡΡΡΠΈΡΠΈΠ΅Π½ΡΡ ΡΡΠ΅Π½ΠΈΡ ΠΎΠΏΡΠ΅Π΄Π΅Π»ΡΠ»ΠΈΡΡ ΠΏΠΎ ΡΠ΅Π·ΡΠ»ΡΡΠ°ΡΠ°ΠΌ ΡΠΊΡΠΏΠ΅ΡΠΈΠΌΠ΅Π½ΡΠ°Π»ΡΠ½ΡΡ
ΠΈΠ·ΠΌΠ΅ΡΠ΅Π½ΠΈΠΉ), Π° ΡΠ°ΠΊΠΆΠ΅ Π²Π»ΠΈΡΠ½ΠΈΠ΅ ΡΠ°ΡΡΠΎΡΡ Π²ΡΠ°ΡΠ΅Π½ΠΈΡ ΠΌΠ΅Π»ΡΠ½ΠΈΡΡ Π½Π° ΡΠ³ΠΎΠ» Π²ΡΡ
ΠΎΠ΄Π° ΡΡΡΡΠΆΠΊΠΈ
Evidence of relationship between strain and In-incorporation: Growth of N-polar In-rich InAlN buffer layer by OMCVD
Β© 2019 Author(s). Two I n x A l 1 - x N layers were grown simultaneously on different substrates [sapphire (0001) and the Ga-polar GaN template], but under the same reactor conditions, they were employed to investigate the mechanism of strain-driven compositional evolution. The resulting layers on different substrates exhibit different polarities and the layer grown on sapphire is N-polar. Moreover, for the two substrates, the difference in the degree of relaxation of the grown layers was almost 100%, leading to a large In-molar fraction difference of 0.32. Incorporation of In in I n x A l 1 - x N layers was found to be significantly influenced by the strain imposed by the under-layers. With the evolutionary process of In-incorporation during subsequent layer growth along [0001], the direction of growth was investigated in detail by Auger electron spectroscopy. It is discovered that the I n 0.60 A l 0.40 N layer grown directly on sapphire consists of two different regions with different molar fractions: the transition region and the uniform region. According to the detailed cross-sectional transmission electron microscopy, the transition region is formed near the hetero-interface due to the partial strain release caused by the generation of misfit-dislocations. The magnitude of residual strain in the uniform region decides the In-molar fraction. I n x A l 1 - x N layers were analyzed by structural and optical characterization techniques. Our present work also shows that a multi-characterization approach to study I n x A l 1 - x N is a prerequisite for their applications as a buffer layer.status: publishe
Evaluation of Cytotoxic Activity of Schisandra chinensis Lignans
Using exhaustive chromatographic separation we
have isolated ( 12)-tigloyl-deangeloyl-gomisin F as
a novel dibenzocyclooctadiene lignan from Schisandra
chinensis. With the help of HPLC, we further
isolated (+)-schisandrin, (+)-deoxyschisandrin,
(+)-\u3b3-schisandrin, ( 12)-gomisin J, (+)-gomisin
A, ( 12)-gomisin N, ( 12)-tigloyl-gomisin P, ( 12)-wuweizisu
C, ( 12)-gomisin D, rubrisandrin A, ( 12)-gomisin
G, (+)-gomisin K3 and ( 12)-schisantherin C.
A full NMR description of ( 12)-schisantherin C was
carried out with the aim to confirm previous reports
of its structure. Compounds isolated were
identified on the basis of UV, IR, 1H- and 13C\u2011NMR
and MS. The cytotoxicity of lignans was tested for
the BY-2 cell line alone and as a synergistic effect
with the cytotoxic agent camptothecin. Lignans
showed various toxicity and synergistic and antagonistic
effects on camptothecin-induced cytotoxicity.
Cytotoxicity against colon cancer cell line
LoVo was also tested