22,220 research outputs found
A New Genus of Exodont lchneutinae (Hymenoptera: Braconidae)
Two new species of Muesebeckiini, Ichneutinae, are described as a new genus characterized by exodont mandibles and by alternate pairs of abdominal spiracles missing. Most specimens have been found in northern Florida and a few in eastern Texas
A New Genus of Exodont lchneutinae (Hymenoptera: Braconidae)
Two new species of Muesebeckiini, Ichneutinae, are described as a new genus characterized by exodont mandibles and by alternate pairs of abdominal spiracles missing. Most specimens have been found in northern Florida and a few in eastern Texas
Development of technology for fluid-structure interaction modelling of a 1/8-scale dynamic model of the shuttle External Tank (ET). Volume 2: Supporting data appendixes A through C
For abstract, see N75-21359
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Martian atmospheric O<sub>3</sub> retrieval development for the NOMAD-UVIS spectrometer
The composition of atmospheric trace gases and aerosols is a highly variable and poorly constrained component of the martian atmosphere, and by affecting martian climate and UV surface dose, represents a key parameter in the assessment of suitability for martian habitability. The ExoMars Trace Gas Orbiter (TGO) carries the Open University (OU) designed Ultraviolet and VIsible Spectrometer (UVIS) instrument as part of the Belgian-led Nadir and Occultation for MArs Discovery (NOMAD) spectrometer suite. NOMAD will begin transmitting science observations of martian surface and atmosphere back-scattered UltraViolet (UV) and visible radiation in Spring 2018, which will be processed to derive spatially and temporally averaged atmospheric trace gas and aerosol concentrations, intended to provide a better understanding of martian atmospheric photo-chemistry and dynamics, and will also improve models of martian atmospheric chemistry, climate and habitability. Work presented here illustrates initial development and testing of the OUās new retrieval algorithm for determining O3 and aerosol concentrations from the UVIS instrument
Measurement of Newtonian fluid slip using a torsional ultrasonic oscillator
The composite torsional ultrasonic oscillator, a versatile experimental
system, can be used to investigate slip of Newtonian fluid at a smooth surface.
A rigorous analysis of slip-dependent damping for the oscillator is presented.
Initially, the phenomenon of finite surface slip and the slip length are
considered for a half-space of Newtonian fluid in contact with a smooth,
oscillating solid surface. Definitions are revisited and clarified in light of
inconsistencies in the literature. We point out that, in general oscillating
flows, Navier's slip length b is a complex number. An intuitive velocity
discontinuity parameter of unrestricted phase is used to describe the effect of
slip on measurement of viscous shear damping. The analysis is applied to the
composite oscillator and preliminary experimental work for a 40 kHz oscillator
is presented. The Non-Slip Boundary Condition (NSBC) has been verified for a
hydrophobic surface in water to within ~60 nm of |b|=0 nm. Experiments were
carried out at shear rate amplitudes between 230 and 6800 /s, corresponding to
linear displacement amplitudes between 3.2 and 96 nm.Comment: Revised with minor edits for revie
HST followup observations of two bright z ~ 8 candidate galaxies from the BoRG pure-parallel survey
We present followup imaging of two bright (L > L*) galaxy candidates at z > 8
from the Brightest of Reionizing Galaxies (BoRG) survey with the F098M filter
on HST/WFC3. The F098M filter provides an additional constraint on the flux
blueward of the spectral break, and the observations are designed to
discriminate between low- and high-z photometric redshift solutions for these
galaxies. Our results confirm one galaxy, BoRG 0116+1425 747, as a highly
probable z ~ 8 source, but reveal that BoRG 0116+1425 630 - previously the
brightest known z > 8 candidate (mAB = 24.5) - is likely to be a z ~ 2
interloper. As this source was substantially brighter than any other z > 8
candidate, removing it from the sample has a significant impact on the derived
UV luminosity function in this epoch. We show that while previous BoRG results
favored a shallow power-law decline in the bright end of the luminosity
function prior to reionization, there is now no evidence for departure from a
Schechter function form and therefore no evidence for a difference in galaxy
formation processes before and after reionization.Comment: Accepted by ApJL, 7 pages, 4 figure
Generarized Cubic Model for BaTiO-like Ferroelectric Substance
We propose an order-disorder type microscopic model for BaTiO-like
Ferroelectric Substance. Our model has three phase transitions and four phases.
The symmetry and directions of the polarizations of the ordered phases agree
with the experimental results of BaTiO. The intermediate phases in our
model are known as an incompletely ordered phase, which appears in a
generalized clock model.Comment: 6 pages, 4figure
Entropy and weak solutions in the thermal model for the compressible Euler equations
Among the existing models for compressible fluids, the one by Kataoka and
Tsutahara (KT model, Phys. Rev. E 69, 056702, 2004) has a simple and rigorous
theoretical background. The drawback of this KT model is that it can cause
numerical instability if the local Mach number exceeds 1. The precise mechanism
of this instability has not yet been clarified. In this paper, we derive
entropy functions whose local equilibria are suitable to recover the Euler-like
equations in the framework of the lattice Boltzmann method for the KT model.
Numerical examples are also given, which are consistent with the above
theoretical arguments, and show that the entropy condition is not fully
guaranteed in KT model. The negative entropy may be the inherent cause for the
non-physical oscillations in the vicinity of the shock. In contrast to these
Karlin's microscopic entropy approach, the corresponding subsidiary entropy
condition in the LBM calculation could also be deduced explicitly from the
macroscopic version, which provides some insights on the numerical instability
of the lattice Boltzmann model for shock calculation.Comment: 27 pages,6 figure
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