6,860 research outputs found
Peak polarity selector Patent
Peak polarity selector for monitoring waveform
New Calculations of Recombination Rates for Cold He Atoms and Determination of Universal Scaling Functions
Three-body recombination rates for cold He are calculated with a new
method which exploits the simple relationship between the imaginary part of the
atom-dimer elastic scattering phase shift and the -matrix for recombination.
The elastic phase shifts are computed above breakup threshold by solving a
three-body Faddeev equation in momentum space with inputs based on a variety of
modern atom-atom potentials. Recombination coefficients for the HFD-B3-FCII
potential agree very well with the only previously published results. Since the
elastic scattering and recombination processes for He are governed by
"Efimov physics", they depend on universal functions of a scaling variable. The
newly computed recombination coefficients for potentials other than HFD-B3-FCII
make it possible to determine these universal functions for the first time.Comment: 15 pages, 5 figure
MR405: Response of Young Black Spruce (Picea mariana (Mill.) B.S.P.) to a Mixture of Wood Ash and Secondary Papermill Sludge
A study to examine the effects of a combination of wood ash and secondary papermill sludge applied to a clearcut planted to black spruce was initiated in 1987 with the cooperation of Great Northern Paper. Objectives of the study were to assess the effects of the residuals on (1) seedling growth, (2) seedling foliar element concentrations, and (3) chemical properties of the forest floor and mineral soil. This report emphasizes growth results for 1991 through 1995 and foliar element results through 1994.https://digitalcommons.library.umaine.edu/aes_miscreports/1023/thumbnail.jp
Detection of Water and/or Hydroxyl on Asteroid (16) Psyche
In order to search for evidence of hydration on M-type asteroid (16) Psyche,
we observed this object in the 3 micron spectral region using the
long-wavelength cross-dispersed (LXD: 1.9-4.2 micron) mode of the SpeX
spectrograph/imager at the NASA Infrared Telescope Facility (IRTF). Our
observations show that Psyche exhibits a 3 micron absorption feature,
attributed to water or hydroxyl. The 3 micron absorption feature is consistent
with the hydration features found on the surfaces of water-rich asteroids,
attributed to OH- and/or H2O-bearing phases (phyllosilicates). The detection of
a 3 micron hydration absorption band on Psyche suggests that this asteroid may
not be metallic core, or it could be a metallic core that has been impacted by
carbonaceous material over the past 4.5 Gyr. Our results also indicate
rotational spectral variations, which we suggest reflect heterogeneity in the
metal/silicate ratio on the surface of Psyche.Comment: 13 pages, 9 figures in Astronomical Journal, 201
Application of Hapke photometric model to three geologic surfaces using PARABOLA bidirectional reflection data
The Geologic Remote Sensing Field Experiment (GRSFE) was conducted in July and September of 1989 to collect data with both ground and airborne instrumentation. A major objective of GRSFE was to collect data which could be used to test radiative transfer models for the extraction of composition and textural surface properties from remotely acquired data. Reported here are the initial results from an application of the Hapke photometric model, using data from the Portable Apparatus for Remote Acquisition of Bidirectional Observations of Land and Atmosphere (PARABOLA), a ground based radiometer with three spectral channels. PARABOLA data was collected in the Lunar Crater Volcanic Field in Nevada, specifically from the region of Lunar Lake, a playa. The Hapke model was found to be inadequate for three relatively common geologic surfaces (a clay-rich, hard packed surface with decimeter sized mudcracks; a cobble site, similar to a playa site, but strewn with basaltic cobbles and pebbles; and a surface mantled basalt lava flow). The model is not at fault; rather, the complexity of most geologic surfaces is not accounted for in the initial assumptions
Assessment of fish populations and habitat on Oculina Bank, a deep-sea coral marine protected area off eastern Florida
A portion of the Oculina Bank located off eastern Florida is
a marine protected area (MPA) preserved for its dense populations of the ivory tree coral (Oculina varicosa),
which provides important habitat for fish. Surveys of fish assemblages and benthic habitat were conducted inside and outside the MPA in 2003 and 2005 by using remotely operated
vehicle video transects and digital still imagery. Fish species composition, biodiversity, and grouper densities
were used to determine whether O. varicosa forms an essential habitat compared to other structure-forming
habitats and to examine the effectiveness of the MPA. Multivariate analyses indicated no differences in fish
assemblages or biodiversity among hardbottom habitat types and grouper densities were highest among the most complex habitats; however the higher densities were not exclusive to
coral habitat. Therefore, we conclude that O. varicosa was functionally equivalent to other hardbottom habitats. Even though fish assemblages were not different among management
areas, biodiversity and grouper densities were higher inside the MPA compared to outside. The percentage of intact coral was also higher inside the MPA. These results provide initial evidence demonstrating effectiveness of the MPA for restoring reef fish and their habitat. This is the first study to compare reef fish populations on O. varicosa with other structure-forming reef habitats and also the first to examine the effectiveness of the MPA for restoring fish populations and live reef cover
Heavy-Ion Beam Acceleration of Two-Charge States from an Ecr Ion Source
This paper describes a design for the front end of a superconducting (SC) ion
linac which can accept and simultaneously accelerate two charge states of
uranium from an ECR ion source. This mode of operation increases the beam
current available for the heaviest ions by a factor of two. We discuss the 12
MeV/u prestripper section of the Rare Isotope Accelerator (RIA) driver linac
including the LEBT, RFQ, MEBT and SC sections, with a total voltage of 112 MV.
The LEBT consists of two bunchers and electrostatic quadrupoles. The
fundamental frequency of both bunchers is half of the RFQ frequency. The first
buncher is a multiharmonic buncher, designed to accept more than 80% of each
charge state and to form bunches of extremely low longitudinal emittance (rms
emittance is lower than 0.2 keV/u nsec) at the output of the RFQ. The second
buncher is located directly in front of the RFQ and matches the velocity of
each charge-state bunch to the design input velocity of the RFQ. We present
full 3D simulations of a two-charge-state uranium beam including space charge
forces in the LEBT and RFQ, realistic distributions of all electric and
magnetic fields along the whole prestripper linac, and the effects of errors,
evaluated for several design options for the prestripper linac. The results
indicate that it is possible to accelerate two charge states while keeping
emittance growth within tolerable limits.Comment: LINAC2000, MOD0
Feasibility study of a 110 watt per kilogram lightweight solar array system
An investigation of the feasibility of a solar array panel subsystem which will produce 10,000 watts of electrical output at 1 A.U. with an overall beginning-of-life power-to-weight ratio of at least 110 watt/kg is reported. A description of the current baseline configuration which meets these requirements is presented. A parametric analysis of the single boom, two blanket planar solar array system was performed to arrive at the optimum system aspect ratio. A novel concept for the stiffening of a lightweight solar array by canting the solar cell blankets at a small angle to take advantage of the inherent in-plane stiffness to increase the symmetric out-of-plane frequency is introduced along with a preliminary analysis of the stiffening effect. A comparison of welded and soldered solar cell interconnections leads to the conclusion that welding is required on this ultralightweight solar array. The use of a boron/aluminum composite material in a BI-STEM type deployable boom is investigated as a possible advancement in the state-of-the-art
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