7,365 research outputs found
Multispectral imaging and analysis system
Arrays of charge coupled devices or linear detector arrays simultaneously obtain spectral reflectance data of different wavelengths for a target area. Several accommodating a particular bandwidth, are individually associated with each array. Data from the arrays are read out in parallel and applied to a computer or microprocessor for processing. The microprocessor serves to analyze the data in real time and if possible, in accordance with hard-wired algorithms. The data are then displayed as an image on an appropriate display unit and also recorded for further use. The display system may be operationally connected to receive a terrain image such that the target area and the analyzed spectral reflectance data are superimposed and simultaneously displayed
Structural features in the Colorado Plateau margin near Flagstaff, Arizona
The author has identified the following significant results. On ERTS-1 frame 1014-17375, a set of northwest-trending lineaments has been discovered which converge on the north-trending lineament of the Oak Creek Fault near Flagstaff, Arizona. The lineaments are most easily seen in band 7. The region of convergence may mark an area structurally favorable for the location of water in Paleozoic sediments that underlie the basalt cap
The influence of defects of the fatigue resistance of butt and girth welds in A106B steel
This three-phase study was directed at developing a fitness for service defect acceptance criteria for welds with defect indications. The study focussed on A106 Gr. B steel pipe. The first phase involved a literature search and critical review to develop the preliminary acceptance criteria to the extent permitted by the data. The second phase developed data for flat plate, wall segment, and vessel specimens containing artificial or natural planar or volumetric defects. The final phase developed acceptance criteria from the test data
Quantum optimal control of photoelectron spectra and angular distributions
Photoelectron spectra and photoelectron angular distributions obtained in
photoionization reveal important information on e.g. charge transfer or hole
coherence in the parent ion. Here we show that optimal control of the
underlying quantum dynamics can be used to enhance desired features in the
photoelectron spectra and angular distributions. To this end, we combine
Krotov's method for optimal control theory with the time-dependent
configuration interaction singles formalism and a splitting approach to
calculate photoelectron spectra and angular distributions. The optimization
target can account for specific desired properties in the photoelectron angular
distribution alone, in the photoelectron spectrum, or in both. We demonstrate
the method for hydrogen and then apply it to argon under strong XUV radiation,
maximizing the difference of emission into the upper and lower hemispheres, in
order to realize directed electron emission in the XUV regime
Preliminary results in the comparison of Skylab, ERTS and RB-57 images for the detection of lineaments and fractures in Precambrian, Paleozoic, and late Tertiary rocks on and near the Colorado Plateau, North-Central Arizona
There are no author-identified significant results in this report
Study of the horizontal-to-vertical spectral ratio (HVSR) method for characterization of deep soils in the Mississippi Embayment
The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file.Title from PDF of title page (University of Missouri--Columbia, viewed on December 22, 2009).Thesis advisor: Dr. Brent L. Rosenblad.Includes bibliographical references.M.S. University of Missouri--Columbia 2009.Dissertations, Academic -- University of Missouri--Columbia -- Civil engineering.Soil deposits can significantly influence the amplitude and frequency content of surface ground motions during earthquakes. Estimating the fundamental frequency (f0) of a site is often needed for improved planning and design for future earthquakes. A cost-effective method of obtaining an estimate of f0 is the Horizontal-to-Vertical Spectral Ratio (HVSR) method (also termed Nakamura's method), which utilizes ambient energy recorded in the horizontal and vertical directions from a single, three-component sensor. In addition to estimating the fundamental frequency, average shear wave velocity (VS,AVG) values have been estimated using the HVSR method and a simple approximate relationship relating VS,AVG to f0 and the depth to bedrock. This procedure was performed by Bodin et al. (2001) to develop a relationship between VS,AVG and soil depths in the Mississippi embayment. However, this relationship predicts average velocity values that are about 25% higher than values predicted by another relationship developed using a different method (Chen et al. 1996). Although this inconsistency is known, the relationship of Bodin et al. (2001) is often cited as the best information on the velocity structure in the embayment. In addition, Bodin et al. (2001) identified a second frequency peak of unknown origin in their HVSR plots. The objectives of this study are to answer these unresolved questions, specifically: (1) why the shear wave velocity relationships developed for the Mississippi embayment using the HVSR method are inconsistent with other findings, and (2) the origin of the second frequency peak observed in HVSR plots from the Mississippi embayment. To meet these objectives, the following three studies were performed: (1) a parametric study of site factors influencing the fundamental frequency and average velocity estimates from the HVSR method, (2) an investigation into the influence of the HVSR processing parameters using experimental data collected at eleven deep soil sites in the Mississippi embayment, and (3) comparison of experimental and simulated HVSR results for Mississippi embayment sites. With regard to the first objective, it was found that the HVSR method yielded reliable values of the fundamental site frequency for conditions of high velocity contrast between soil and rock and saturated soil conditions (conditions that are met in the Mississippi embayment). Also, it was shown that varying the HVSR processing parameters had a negligible impact on the HVSR frequency estimates. However, it was demonstrated that use of the approximate method to estimate VS,AVG systematically over-predicted the true VS,AVG values. With regard to the second objective, it was shown that the second frequency peak observed in the experimental HVSR plots can be attributed to either a higher-mode resonance of horizontally-polarized shear waves reflecting from the soil/bedrock boundary or local site resonance due to a shallow contrast in VS within the soil deposit. Based on the findings of this study it is recommended that the VS relationship for the sediments of the Mississippi embayment developed by Chen et al. (1996) should be preferred to the Bodin et al. (2001) relationship
Calibration of the LIGO displacement actuators via laser frequency modulation
We present a frequency modulation technique for calibration of the
displacement actuators of the LIGO 4-km-long interferometric gravitational-wave
detectors. With the interferometer locked in a single-arm configuration, we
modulate the frequency of the laser light, creating an effective length
variation that we calibrate by measuring the amplitude of the frequency
modulation. By simultaneously driving the voice coil actuators that control the
length of the arm cavity, we calibrate the voice coil actuation coefficient
with an estimated 1-sigma uncertainty of less than one percent. This technique
enables a force-free, single-step actuator calibration using a displacement
fiducial that is fundamentally different from those employed in other
calibration methods.Comment: 10 pages, 5 figures, submitted to Classical and Quantum Gravit
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