2,115 research outputs found
Transient analysis of bodies with moving boundaries using NASTRAN
A scheme is presented which allows the modeling of a moving boundary with NASTRAN NOLIN cards. Various aspects and limitations of the approach are explained. Recommendations are given as to the procedure to be used in implementing the method
LOX/GOX mechanical impact tester assessment
The performances of three existing high pressure oxygen mechanical impact test systems were tested at two different test sites. The systems from one test site were fabricated from the same design drawing, whereas the system tested at the other site was of different design. Energy delivered to the test sample for each test system was evaluated and compared. Results were compared to the reaction rates obtained
Fitting the Means to the Ends: One School’s Experience with Quantitative and Qualitative Methods in Curriculum Evaluation During Curriculum Change
Curriculum evaluation plays an important role in substantive curriculum change. The experience of the University of Texas Medical Branch (UTMB) with evaluation processes developed for the new Integrated Medical Curriculum (IMC) illustrates how evaluation methods may be chosen to match the goals of the curriculum evaluation process. Quantitative data such as ratings of courses or scores on external exams are useful for comparing courses or assessing whether standards have been met. Qualitative data such as students’ comments about aspects of courses are useful for eliciting explanations of observed phenomena and describing relationships between curriculum features and outcomes. The curriculum evaluation process designed for the IMC used both types of evaluation methods in a complementary fashion. Quantitative and qualitative methods have been used for formative evaluation of the new IMC courses. They are now being incorporated into processes to judge the IMC against its goals and objectives
BIMA and Keck Imaging of the Radio Ring PKS 1830-211
We discuss BIMA (Berkeley Illinois Maryland Association) data and present new
high quality optical and near-IR Keck images of the bright radio ring PKS
1830-211. Applying a powerful new deconvolution algorithm we have been able to
identify both images of the radio source. In addition we recover an extended
source in the optical, consistent with the expected location of the lensing
galaxy. The source counterparts are very red, I-K=7, suggesting strong Galactic
absorption with additional absorption by the lensing galaxy at z=0.885, and
consistent with the detection of high redshift molecules in the lens.Comment: To be published in the ASP Conference Proceedings, 'Highly Redshifted
Radio Lines', Greenbank, W
Size dependence of the photoinduced magnetism and long-range ordering in Prussian blue analog nanoparticles of rubidium cobalt hexacyanoferrate
Nanoparticles of rubidium cobalt hexacyanoferrate
(RbCo[Fe(CN)]HO) were synthesized using different
concentrations of the polyvinylpyrrolidone (PVP) to produce four different
batches of particles with characteristic diameters ranging from 3 to 13 nm.
Upon illumination with white light at 5 K, the magnetization of these particles
increases. The long-range ferrimagnetic ordering temperatures and the coercive
fields evolve with nanoparticle size. At 2 K, particles with diameters less
than approximately 10 nm provide a Curie-like magnetic signal.Comment: 10 pages, 6 figures in text, expanded text and dat
The redshift of the gravitationally lensed radio source PKS1830-211
We report on the spectroscopic identification and the long awaited redshift
measurement of the heavily obscured, gravitationally lensed radio source PKS
1830-211, which was first observed as a radio Einstein ring. The NE component
of the doubly imaged core is identified, in our infrared spectrum covering the
wavelength range 1.5-2.5 microns, as an impressively reddened quasar at
z=2.507. Our redshift measurement, together with the recently measured time
delay (Lovell et al.), means that we are a step closer to determining the
Hubble constant from this lens. Converting the time delay into the Hubble
constant by using existing models leads to high values for the Hubble constant.
Since the lensing galaxy lies very close to the center of the lensed ring,
improving the error bars on the Hubble constant will require not only a more
precise time delay measurement, but also very precise astrometry of the whole
system.Comment: 11 pages, 2 figures, Accepted ApJ
Agricultural Lime Recommendations Based on Lime Quality
Soil acidity is one of the most important soil factors affecting crop growth and ultimately, yield and profitability. It is determined by measuring the soil pH, which is a measure of the amount of hydrogen ions in the soil solution. As soil acidity increases, the soil pH decreases. Soils tend to be naturally acidic in areas where rainfall is sufficient to cause substantial leaching of basic ions (such as calcium and magnesium), which are replaced by hydrogen ions. Most soils in Kentucky are naturally acidic because of our abundant rainfall. Some nitrogen fertilizers are also a source of soil acidity, so fields with a history of N applications likely will be more acidic
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