9,537 research outputs found
Feasibility of modifying the high resolution infrared radiation sounder (HIRS/2) for measuring spectral components of Earth radiation budget
The concept of adding four spectral channels to the 20 channel HIRS/2 instrument for the purpose of determining the origin and profile of radiant existence from the Earth's atmosphere is considered. Methods of addition of three channels at 0.5, 1.0 and 1.6 micron m to the present 0.7 micron m visible channel and an 18-25 micron m channel to the present 19 channels spaced from 3.7 micron m to 15 micron m are addressed. Optical components and physical positions were found that permit inclusion of these added channels with negligible effect on the performance of the present 20 channels. Data format changes permit inclusion of the ERB data in the 288 bits allocated to HIRS for each scan element. A lamp and collimating optic assembly may replace one of the on board radiometric black bodies to provide a reference source for the albedo channels. Some increase in instrument dimensions, weight and power will be required to accommodate the modifications
Performance of high-altitude, long-endurance, turboprop airplanes using conventional or cryogenic fuels
An analytical study has been conducted to evaluate the potential endurance of remotely piloted, low speed, high altitude, long endurance airplanes designed with 1990 technology. The baseline configuration was a propeller driven, sailplane like airplane powered by turbine engines that used JP-7, liquid methane, or liquid hydrogen as fuel. Endurance was measured as the time spent between 60,000 feet and an engine limited maximum altitude of 70,000 feet. Performance was calculated for a baseline vehicle and for configurations derived by varying aerodynamic, structural or propulsion parameters. Endurance is maximized by reducing wing loading and engine size. The level of maximum endurance for a given wing loading is virtually the same for all three fuels. Constraints due to winds aloft and propulsion system scaling produce maximum endurance values of 71 hours for JP-7 fuel, 70 hours for liquid methane, and 65 hours for liquid hydrogen. Endurance is shown to be strongly effected by structural weight fraction, specific fuel consumption, and fuel load. Listings of the computer program used in this study and sample cases are included in the report
The Effects of Deep Oscillation Therapy for Individuals with Lower-Leg Pain
Purpose: Lower extremity (LE) pain accounts for 13-20% of injuries in the active population. LE pain has been contributed to inflexibility and fascial restrictions. Deep oscillation therapy (DOT) has been proposed to improve range of motion and reduce pain following musculoskeletal injuries. Therefore, our objective was to determine the effectiveness of DOT on ankle dorsiflexion range of motion (ROM) and pain in individuals with and without lower-leg pain. Methods: We used a single blind, pre-post experimental study in a research laboratory. Thirty-two active participants completed this study. Sixteen individuals reporting lower-leg pain and sixteen non-painful individuals completed the study. Participants received a single session of DOT performed by one researcher to their affected limb or matched limb. The intervention parameters included a 1:1 mode and 70-80% dosage. The intervention began by stimulating the lymphatic channels at the cisterna chyli, the inguinal lymph node, and the popliteal lymph node at a frequency of 150 Hz all for a minute each. Next, the researcher treated the triceps surae complex for 11 minutes at three different frequencies. Finally, the participant was treated distal to the popliteal lymph node at 25 Hz for 5 minutes. The main outcome measures included pain using the VAS and ankle dorsiflexion ROM with the weight-bearing lunge test (WBLT). Statistical analyses included descriptive statistics and F-test comparisons between and within groups. Results: The average WBLT measures for all participants increased 0.6 cm, which not to the minimal detectable change for passive ankle dorsiflexion ROM. Significant differences from pre-post measures were identified for pain on the VAS. Conclusion: While increases in ROM were identified, the difference was not clinically important. DOT was successful in decreasing lower-leg pain
The Effects of Deep Oscillation Therapy for Individuals with Lower-Leg Pain
Purpose: Lower extremity (LE) pain accounts for 13-20% of injuries in the active population. LE pain has been contributed to inflexibility and fascial restrictions. Deep oscillation therapy (DOT) has been proposed to improve range of motion and reduce pain following musculoskeletal injuries. Therefore, our objective was to determine the effectiveness of DOT on ankle dorsiflexion range of motion (ROM) and pain in individuals with and without lower-leg pain. Methods: We used a single blind, pre-post experimental study in a research laboratory. Thirty-two active participants completed this study. Sixteen individuals reporting lower-leg pain and sixteen non-painful individuals completed the study. Participants received a single session of DOT performed by one researcher to their affected limb or matched limb. The intervention parameters included a 1:1 mode and 70-80% dosage. The intervention began by stimulating the lymphatic channels at the cisterna chyli, the inguinal lymph node, and the popliteal lymph node at a frequency of 150 Hz all for a minute each. Next, the researcher treated the triceps surae complex for 11 minutes at three different frequencies. Finally, the participant was treated distal to the popliteal lymph node at 25 Hz for 5 minutes. The main outcome measures included pain using the VAS and ankle dorsiflexion ROM with the weight-bearing lunge test (WBLT). Statistical analyses included descriptive statistics and F-test comparisons between and within groups. Results: The average WBLT measures for all participants increased 0.6 cm, which not to the minimal detectable change for passive ankle dorsiflexion ROM. Significant differences from pre-post measures were identified for pain on the VAS. Conclusion: While increases in ROM were identified, the difference was not clinically important. DOT was successful in decreasing lower-leg pain
Dusty Cometary Globules in W5
We report the discovery of four dusty cometary tails around low mass stars in
two young clusters belonging to the W5 star forming region. Fits to the
observed emission profiles from 24 micron observations with the Spitzer Space
Telescope give tail lifetimes < 30 Myr, but more likely < 5 Myr. This result
suggests that the cometary phase is a short lived phenomenon, occurring after
photoevaporation by a nearby O star has removed gas from the outer disk of a
young low mass star (see also Balog et al. 2006; Balog et al. 2008).Comment: 11 pages, 3 figures. Accepted for publication to ApJ Letter
On the correllation effect in Peierls-Hubbard chains
We reexamine the dimerization, the charge and the spin gaps of a half-filled
Peierls-Hubbard chain by means of the incremental expansion technique. Our
numerical findings are in significant quantitative conflict with recently
obtained results by M. Sugiura and Y. Suzumura [J. Phys. Soc. Jpn. v. 71 (2002)
697] based on a bosonization and a renormalization group method, especially
with respect to the charge gap. Their approach seems to be valid only in the
weakly correlated case.Comment: 7pages,4figures(6eps-files
Workshop on Thrust Augmenting Ejectors
The state of the art of ejector technology is assessed and the desired direction of future studies in all aspects of ejector thrust augmenting systems is deliniated
Validation of a Climate-Data Record of the "Clear-Sky" Surface Temperature of the Greenland Ice Sheet
Surface temperatures on the Greenland Ice Sheet have been studied on the ground, using automatic weather station (AWS) data from the Greenland-Climate Network (GC-Net), and from analysis of satellite sensor data. Using Advanced Very High Frequency Radiometer (AVHRR) weekly surface temperature maps, warming of the surface of the Greenland Ice Sheet has been documented since 1981. We extended and refined this record using higher-resolution Moderate-Resolution Imaging Spectroradiometer (MODIS) data from March 2000 to the present. We developed a daily and monthly climate-data record (CDR) of the "clear-sky" surface temperature of the Greenland Ice Sheet using an ice-surface temperature (1ST) algorithm developed for use with MODIS data. Validation of this CDR is ongoing. MODIS Terra swath data are projected onto a polar stereographic grid at 6.25-km resolution to develop binary, gridded daily and mean-monthly 1ST maps. Each monthly map also has a color-coded image map that is available to download. Also included with the monthly maps is an accompanying map showing number of days in the month that were used to calculate the mean-monthly 1ST. This is important because no 1ST decision is made by the algorithm for cells that are considered cloudy by the internal cloud mask, so a sufficient number of days must be available to produce a mean 1ST for each grid cell. Validation of the CDR consists of several facets: 1) comparisons between ISTs and in-situ measurements; 2) comparisons between ISTs and AWS data; and 3) comparisons of ISTs with surface temperatures derived from other satellite instruments such as the Thermal Emission and Reflection Radiometer (ASTER) and Enhanced Thematic Mapper Plus (ETM+). Previous work shows that Terra MODIS ISTs are about 3 C lower than in-situ temperatures measured at Summit Camp, during the winter of 2008-09 under clear skies. In this work we begin to compare surface temperatures derived from AWS data with ISTs from the MODIS CDR
Application of B-splines to determining eigen-spectrum of Feshbach molecules
The B-spline basis set method is applied to determining the rovibrational
eigen-spectrum of diatomic molecules. A particular attention is paid to a
challenging numerical task of an accurate and efficient description of the
vibrational levels near the dissociation limit (halo-state and Feshbach
molecules). Advantages of using B-splines are highlighted by comparing the
performance of the method with that of the commonly-used discrete variable
representation (DVR) approach. Several model cases, including the Morse
potential and realistic potentials with 1/R^3 and 1/R^6 long-range dependence
of the internuclear separation are studied. We find that the B-spline method is
superior to the DVR approach and it is robust enough to properly describe the
Feshbach molecules. The developed numerical method is applied to studying the
universal relation of the energy of the last bound state to the scattering
length. We numerically illustrate the validity of the quantum-defect-theoretic
formulation of such a relation for a 1/R^6 potential.Comment: submitted to can j phys: Walter Johnson symposu
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