2,936 research outputs found
Mechanical Properties of Small Clear Specimens and Visually Graded Lumber from Living and Spruce Budworm-Killed Balsam Fir
Small clear specimens from living balsam fir and from spruce budworm-killed balsam fir dead 3 months, 12 months, and 22 months were tested in bending and compression perpendicular to the grain. Results indicated that modulus of rupture (MOR) of specimens from budworm-killed trees dead 3 months or more was significantly lower than MOR of specimens from living trees. Modulus of elasticity (MOE) appeared to be less sensitive to changes in budworm-killed material than MOR. Stress at the proportional limit for compression perpendicular to the grain was significantly lower for specimens from trees dead 22 months than for specimens from living trees. Both MOE and MOR in bending were determined for visually graded nominal 2- by 4-inch lumber from living and spruce budworm-killed balsam fir dead 12 months and 22 months. Average MOE values for living balsam fir were 1.274 x 106 psi, 1.217 x 106 psi, and 1.175 x 106 psi for Construction, Standard and Utility grades, respectively. Average MOR values for the same grades of living material were 4,699 psi, 4,684 psi, and 4,352 psi, respectively. Average MOE and MOR for Utility grade lumber from both spruce budworm-killed categories were not significantly different from the average MOE and MOR for living balsam fir. Statistical analyses of the MOE and MOR data for Construction and Standard grades of budworm-killed lumber were not performed due to the small sample sizes
Comparison of Two Methodologies for Calibrating Satellite Instruments in the Visible and Near Infrared
Traditionally, satellite instruments that measure Earth-reflected solar radiation in the visible and near infrared wavelength regions have been calibrated for radiance response in a two-step method. In the first step, the spectral response of the instrument is determined using a nearly monochromatic light source, such a lamp-illuminated monochromator. Such sources only provide a relative spectral response (RSR) for the instrument, since they do not act as calibrated sources of light nor do they typically fill the field-of-view of the instrument. In the second step, the instrument views a calibrated source of broadband light, such as lamp-illuminated integrating sphere. In the traditional method, the RSR and the sphere spectral radiance are combined and, with the instrument's response, determine the absolute spectral radiance responsivity of the instrument. More recently, an absolute calibration system using widely tunable monochromatic laser systems has been developed, Using these sources, the absolute spectral responsivity (ASR) of an instrument can be determined on a wavelength-hy-wavelength basis. From these monochromatic ASRs. the responses of the instrument bands to broadband radiance sources can be calculated directly, eliminating the need for calibrated broadband light sources such as integrating spheres. Here we describe the laser-based calibration and the traditional broad-band source-based calibration of the NPP VIIRS sensor, and compare the derived calibration coefficients for the instrument. Finally, we evaluate the impact of the new calibration approach on the on-orbit performance of the sensor
Lattice calculation of hybrid mesons with improved Kogut-Susskind fermions
We report on a lattice determination of the mass of the exotic
hybrid meson using an improved Kogut-Susskind action. Results from both
quenched and dynamical quark simulations are presented. We also compare with
earlier results using Wilson quarks at heavier quark masses. The results on
lattices with three flavors of dynamical quarks show effects of sea quarks on
the hybrid propagators which probably result from coupling to two meson states.
We extrapolate the quenched results to the physical light quark mass to allow
comparison with experimental candidates for the hybrid meson. The
lattice result remains somewhat heavier than the experimental result, although
it may be consistent with the .Comment: 24 pages, 12 figures. Replaced to match published versio
Pavement surface specification for road load measurement
This report proposes a framework for specifying coast-down test surfaces that will produce relevant, reproducible road load measurements. The proposed specification includes grade, roughness, megatexture, and macrotexture. Specification using standard scales in use by the pavement monitoring community is recommended for roughness (International Roughness Index), megatexture (“megatexture level” from ISO 13473-5), and macrotexture (Mean Profile Depth). These scales are well understood, and have demonstrated relevance to various type of vehicle response to the pavement. However, they may be replaced over the long term when other scales are developed with a specific emphasis on fuel consumption. The report also reviews commercially available equipment of measuring grade, roughness, megatexture, and macrotexture.
This report presents a detailed survey of roughness values found on the public road system using data obtained from the Federal Highway Administration’s Highway Performance Monitoring System. The report also includes a tutorial presentation of
road surface textures and some pavement design specifications that affect surface texture.Hyundai-Kia America Technical Center, Inc.http://deepblue.lib.umich.edu/bitstream/2027.42/106399/1/102993.pd
PD/VFC #2 -- a detector for the Izana transmission monitor
The PD/VFC #2, a detector for the Izaña transmission monitor, is described
The transition between hole-pairs and four-hole clusters in four-leg tJ ladders
Holes weakly doped into a four-leg \tj ladder bind in pairs. At dopings
exceeding a critical doping of four hole clusters are
observed to form in DMRG calculations. The symmetry of the ground state
wavefunction does not change and we are able to reproduce this behavior
qualitatively with an effective bosonic model in which the four-leg ladder is
represented as two coupled two-leg ladders and hole-pairs are mapped on hard
core bosons moving along and between these ladders. At lower dopings,
, a one dimensional bosonic representation for hole-pairs
works and allows us to calculate accurately the Luttinger liquid parameter
\krho, which takes the universal value \krho=1 as half-filling is
approached
Quantitative and Rapid DNA Detection by Laser Transmission Spectroscopy
Laser transmission spectroscopy (LTS) is a quantitative and rapid in vitro technique for measuring the size, shape, and number of nanoparticles in suspension. Here we report on the application of LTS as a novel detection method for species-specific DNA where the presence of one invasive species was differentiated from a closely related invasive sister species. The method employs carboxylated polystyrene nanoparticles functionalized with short DNA fragments that are complimentary to a specific target DNA sequence. In solution, the DNA strands containing targets bind to the tags resulting in a sizable increase in the nanoparticle diameter, which is rapidly and quantitatively measured using LTS. DNA strands that do not contain the target sequence do not bind and produce no size change of the carboxylated beads. The results show that LTS has the potential to become a quantitative and rapid DNA detection method suitable for many real-world applications
Plasma Turbulence in the Local Bubble
Turbulence in the Local Bubble could play an important role in the
thermodynamics of the gas that is there. The best astronomical technique for
measuring turbulence in astrophysical plasmas is radio scintillation.
Measurements of the level of scattering to the nearby pulsar B0950+08 by
Philips and Clegg in 1992 showed a markedly lower value for the line-of-sight
averaged turbulent intensity parameter is smaller than normal for two of them, but is completely nominal for
the third. This inconclusive status of affairs could be improved by
measurements and analysis of ``arcs'' in ``secondary spectra'' of pulsars.Comment: Submitted to Space Science Reviews as contribution to Proceedings of
ISSI (International Space Science Institute) workshop "From the Heliosphere
to the Local Bubble". Refereed version accepted for publicatio
AD Leonis: Radial Velocity Signal of Stellar Rotation or Spin–Orbit Resonance?
AD Leonis is a nearby magnetically active M dwarf. We find Doppler variability with a period of 2.23 days, as well as photometric signals: (1) a short-period signal, which is similar to the radial velocity signal, albeit with considerable variability; and (2) a long-term activity cycle of 4070 ± 120 days. We examine the short-term photometric signal in the available All-Sky Automated Survey and Microvariability and Oscillations of STars (MOST) photometry and find that the signal is not consistently present and varies considerably as a function of time. This signal undergoes a phase change of roughly 0.8 rad when considering the first and second halves of the MOST data set, which are separated in median time by 3.38 days. In contrast, the Doppler signal is stable in the combined High-Accuracy Radial velocity Planet Searcher and High Resolution Echelle Spectrometer radial velocities for over 4700 days and does not appear to vary in time in amplitude, phase, period, or as a function of extracted wavelength. We consider a variety of starspot scenarios and find it challenging to simultaneously explain the rapidly varying photometric signal and the stable radial velocity signal as being caused by starspots corotating on the stellar surface. This suggests that the origin of the Doppler periodicity might be the gravitational tug of a planet orbiting the star in spin–orbit resonance. For such a scenario and no spin–orbit misalignment, the measured v sin i indicates an inclination angle of 15°̣5 ± 2°̣5 and a planetary companion mass of 0.237 ± 0.047 M Jup
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