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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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Thesis Introduction, Single Chapter, and Conclusion including work supported by Sandia LDRD project. This is not the entire Thesis document, which is much longer.
Purpose: To determine the daily and cumulative dosimetric effects of intrafraction prostate motion on step-and-shoot (SNS) intensity-modulated radiation therapy (IMRT) plans, to evaluate the correlation of dosimetric effect with motion-based metrics, and to compare on a fraction-by-fraction basis the dosimetric effect induced in SNS and helical tomotherapy plans. Methods and Materials: Intrafraction prostate motion data from 486 fractions and 15 patients were available. A motion-encoded dose calculation technique was used to determine the variation of the clinical target volume (CTV) D{sub 95%} values with respect to the static plan for SNS plans. The motion data were analyzed separately, and the correlation coefficients between various motion-based metrics and the dosimetric effect were determined. The dosimetric impact was compared with that incurred during another IMRT technique to assess correlation across different delivery techniques. Results: The mean ({+-}1 standard deviation [SD]) change in D{sub 95%} in the CTV over all 486 fractions was 0.2 {+-} 0.5%. After the delivery of five and 12 fractions, the mean ({+-}1 SD) changes over the 15 patients in CTV D{sub 95%} were 0.0 {+-} 0.2% and 0.1 {+-} 0.2%, respectively. The correlation coefficients between the CTV D{sub 95%} changes and the evaluated motion metrics were, in general, poor and ranged from r = -0.2 to r = -0.39. Dosimetric effects introduced by identical motion in SNS and helical tomotherapy IMRT techniques were poorly correlated with a correlation coefficient of r = 0.32 for the CTV. Conclusions: The dosimetric impact of intrafraction prostate motion on the CTV is, in general, small. In only 4% of all fractions did the dosimetric consequence exceed 1% in the CTV. As expected, the cumulative effect was further reduced with fractionation. The poor correlations between the calculated motion parameters and the subsequent dosimetric effect implies that motion-based thresholds are of limited value in predicting the dosimetric impact of intrafraction motion. The dosimetric effects between the two evaluated delivery techniques were poorly correlated.
Buildings are responsible for 40% of US energy consumption, and sensing and control technologies are an important element in creating a truly sustainable built environment. Motion-based occupancy sensors are often part of these control systems, but are usually altered or disabled in response to occupants' complaints, at the expense of energy savings. Can we leverage commodity hardware developed for other sectors and embedded software to produce more capable sensors for robust building controls? The National Renewable Energy Laboratory's (NREL) 'Image Processing Occupancy Sensor (IPOS)' is one example of leveraging embedded systems to create smarter, more reliable, multi-function sensors that open the door to new control strategies for building heating, cooling, ventilation, and lighting control. In this keynote, we will discuss how cost-effective embedded systems are changing the state-of-the-art of building sensing and control.
Purpose: A new motion-based gated proton therapy for the treatment of orbital tumors using real-time eye-tracking system was designed and evaluated. Methods: We developed our system by image-pattern matching, using a normalized cross-correlation technique with LabVIEW 8.6 and Vision Assistant 8.6 (National Instruments, Austin, TX). To measure the pixel spacing of an image consistently, four different calibration modes such as the point-detection, the edge-detection, the line-measurement, and the manual measurement mode were suggested and used. After these methods were applied to proton therapy, gating was performed, and radiation dose distributions were evaluated. Results: Moving phantom verification measurements resulted in errors of less than 0.1 mm for given ranges of translation. Dosimetric evaluation of the beam-gating system versus nongated treatment delivery with a moving phantom shows that while there was only 0.83 mm growth in lateral penumbra for gated radiotherapy, there was 4.95 mm growth in lateral penumbra in case of nongated exposure. The analysis from clinical results suggests that the average of eye movements depends distinctively on each patient by showing 0.44 mm, 0.45 mm, and 0.86 mm for three patients, respectively. Conclusions: The developed automatic eye-tracking based beam-gating system enabled us to perform high-precision proton radiotherapy of orbital tumors.
Accurate human identification using radar has a variety of potential applications, such as surveillance, access control and security checkpoints. Nevertheless, radar-based human identification has been limited to a few motion-based biometrics that are solely reliant on micro-Doppler signatures. This paper proposes for the first time the use of combined radar-based heart sound and gait signals as biometrics for human identification. The proposed methodology starts by converting the extracted biometric signatures collected from 18 subjects to images, and then an image augmentation technique is applied and the deep transfer learning is used to classify each subject. A validation accuracy of 58.7% and 96% is reported for the heart sound and gait biometrics, respectively. Next, the identification results of the two biometrics are combined using the joint probability mass function (PMF) method to report a 98% identification accuracy. To the best of our knowledge, this is the highest reported in the literature to date. Lastly, the trained networks are tested in an actual scenario while being used in an office access control platform to identify different human subjects. We report an accuracy of 76.25%.
We have used the first ~3 years of 3.4 μm (W1) and 4.6 μm (W2) observations from the WISE and NEOWISE missions to create a full-sky set of time-resolved coadds. As a result of the WISE survey strategy, a typical sky location is visited every six months and is observed during ≳ 12 exposures per visit, with these exposures spanning a ~1 day time interval. We have stacked the exposures within such ~1 day intervals to produce one coadd per band per visit - that is, one coadd every six months at a given position on the sky in each of W1 and W2. For most parts of the sky, we have generated six epochal coadds per band, with one visit during the fully cryogenic WISE mission, one visit during NEOWISE, and then, after a 33-month gap, four more visits during the NEOWISE-Reactivation mission phase. These coadds are suitable for studying long-timescale mid-infrared variability and measuring motions to ~1.3 mag fainter than the single-exposure detection limit. In most sky regions, our coadds span a 5.5-year time period and therefore provide a >10× enhancement in time baseline relative to that available for the AllWISE catalog's apparent motion measurements. As such, the signature application of these new coadds is expected to be motion-based identification of relatively faint brown dwarfs, especially those cold enough to remain undetected by Gaia.
The Wide-field Infrared Survey Explorer (WISE) is a powerful tool for finding nearby brown dwarfs and searching for new planets in the outer solar system, especially with the incorporation of NEOWISE and NEOWISE-Reactivation data. However, so far, searches for brown dwarfs in WISE data have yet to take advantage of the full depth of the WISE images. To efficiently search this unexplored space via visual inspection, we have launched a new citizen science project, called “Backyard Worlds: Planet 9,” which asks volunteers to examine short animations composed of difference images constructed from time-resolved WISE coadds. We report the first new substellar object discovered by this project, WISEA J110125.95+540052.8, a T5.5 brown dwarf located approximately 34 pc from the Sun with a total proper motion of ∼0.″7 yr{sup −1}. WISEA J110125.95+540052.8 has a WISE W2 magnitude of W2=15.37±0.09; our sensitivity to this source demonstrates the ability of citizen scientists to identify moving objects via visual inspection that are 0.9 mag fainter than the W2 single-exposure sensitivity, a threshold that has limited prior motion-based brown dwarf searches with WISE.