12,069 research outputs found
An investigation of the compressive strength of PRD-49-3/Epoxy composites
The development of unidirectional fiber composite materials is discussed. The mechanical and physical properties of the materials are described. Emphasis is placed in analyzing the compressive behavior of composite materials and developing methods for increasing compressive strength. The test program for evaluating the various procedures for improving compressive strength are reported
Weed and Feed
Fertilizer and herbicide combinations are often applied prior to planting, at planting, or after crop emergence, a procedure sometimes called weed and feed . The opportunities for utilizing this system are numerous with the major advantage being saving an extra trip across the field. In order for the system to work, it must ensure that both fertilizer and herbicide are present when needed. When both the crop plant and weedy plant are at growth stages which allow for compatible applications with a single treatment, this can be highly successful. Conversely, when these two plant systems are not at compatible growth stages, severe crop injury and/or a lack of weed control can result.
There are several methods of applying herbicides and fertilizers together, but regardless, always follow directions on the pesticide label for specific instructions and/or restrictions
The luminosity function of the brightest galaxies in the IRAS survey
Results from a study of the far infrared properties of the brightest galaxies in the IRAS survey are described. There is a correlation between the infrared luminosity and the infrared to optical luminosity ratio and between the infrared luminosity and the far infrared color temperature in these galaxies. The infrared bright galaxies represent a significant component of extragalactic objects in the local universe, being comparable in space density to the Seyferts, optically identified starburst galaxies, and more numerous than quasars at the same bolometric luminosity. The far infrared luminosity in the local universe is approximately 25% of the starlight output in the same volume
AN ECONOMIC AND RISK ANALYSIS OF THE EFFECTS OF TILLAGE AND NITROGEN SOURCE ON SOIL CARBON SEQUESTRATION IN CORN PRODUCTION
The economic potential of no-tillage versus conventional tillage to sequester soil carbon using either commercial nitrogen or manure for continuous corn production is evaluated. Results indicate which system provides the highest net returns, which system is preferred by risk averse decision makers, and the price of carbon credits under alternative risk aversion preferences.Risk and Uncertainty,
Laser-zone Growth in a Ribbon-to-ribbon (RTR) Process Silicon Sheet Growth Development for the Large Area Silicon Sheet Task of the Low Cost Solar Array Project
A technique for growing limited-length ribbons continually was demonstrated. This Rigid Edge technique can be used to recrystallize about 95% of the polyribbon feedstock. A major advantage of this method is that only a single, constant length silicon ribbon is handled throughout the entire process sequence; this may be accomplished using cassettes similar to those presently in use for processing Czochralski waters. Thus a transition from Cz to ribbon technology can be smoothly affected. The maximum size being considered, 3 inches x 24 inches, is half a square foot, and will generate 6 watts for 12% efficiency at 1 sun. Silicon dioxide has been demonstrated as an effective, practical diffusion barrier for use during the polyribbon formation
Magnon Dispersion in the Field-Induced Magnetically Ordered Phase of TlCuCl3
The magnetic properties of the interacting dimer system TlCuCl3 are
investigated within a bond-operator formulation. The observed field-induced
staggered magnetic order perpendicular to the field is described as a Bose
condensation of magnons which are linear combinations of dimer singlet and
triplet modes. This technique accounts for the magnetization curve and for the
field dependence of the magnon dispersion curves observed by high-field neutron
scattering measurements.Comment: 4 pages, 4 figures, REVTeX
Hydrodynamic interaction in quasi-two-dimensional suspensions
Confinement between two parallel surfaces is found, theoretically and
experimentally, to drastically affect the hydrodynamic interaction between
colloid particles, changing the sign of the coupling, its decay with distance
and its concentration dependence. In particular, we show that three-body
effects do not modify the coupling at large distances as would be expected from
hydrodynamic screening.Comment: 8 pages, 2 figure
Molecular heat pump for rotational states
In this work we investigate the theory for three different uni-directional
population transfer schemes in trapped multilevel systems which can be utilized
to cool molecular ions. The approach we use exploits the laser-induced coupling
between the internal and motional degrees of freedom so that the internal state
of a molecule can be mapped onto the motion of that molecule in an external
trapping potential. By sympathetically cooling the translational motion back
into its ground state the mapping process can be employed as part of a cooling
scheme for molecular rotational levels. This step is achieved through a common
mode involving a laser-cooled atom trapped alongside the molecule. For the
coherent mapping we will focus on adiabatic passage techniques which may be
expected to provide robust and efficient population transfers. By applying
far-detuned chirped adiabatic rapid passage pulses we are able to achieve an
efficiency of better than 98% for realistic parameters and including
spontaneous emission. Even though our main focus is on cooling molecular
states, the analysis of the different adiabatic methods has general features
which can be applied to atomic systems
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