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Investigation of the approach used in the unresolved resonance region
The typical practice used in Monte Carlo neutron transport codes in the unresolved resonance region (URR) is to take advantage of the probability table (PT) approach. Cross sections are sampled from PTs and used as needed, along with generated average cross sections. The PTs are generated based on cross-section calculations performed using the single-level Breit–Wigner approximation. Although the approach used in the URR seems plausible, a detailed examination was needed to understand the benchmark results obtained using specific tests.
ORNL FY2024 Nuclear Data Evaluation Contributions: Cu, La, N, and Ta [Slides]
63,65 Cu angular distributions resolved for ENDF/B-VIII.1, consistent with both differential data and integral benchmark performance. 139 La RRR and URR evaluations will be merged with the LANL high energy evaluation, and to be submitted to the future ENDF-B release (post-VIII.1). 14 N RRR evaluation is planned to produce n+ 14 N, p+ 14 C, and a+ 11 B contributions to be submitted to the future ENDF-B release (post-VIII.1). 181 Ta covariances repaired and reported as intended in an errata to ENDF/B-VIII.1.
Fellowship of the Resolved [Slides]
There are new evaluation methods being explored for combined RRR + URR. Simple example demonstrated in SAMMY code using. Potential to be applied to future LoFi, Medium-Fi covariance efforts. Much more work needs to be done to fully correlate regions.
A Downscaling Analysis of the Urban Influence on Rainfall: TRMM Satellite Component AMS Conference on Satellite Meteorology and Oceanography
A recent publication by Shepherd et al. (2002) demonstrated the feasibility of using TRMM precipitation radar (PR) estimates to identify precipitation anomalies caused by urbanization. The approach is particularly useful for investigating this global process because TRMM data span large portions of the globe and comprise an extended temporal dataset. Recent literature suggests that urbanized regions of Houston, Texas may be influencing lightning and precipitation formation over and downwind of the city. Possible mechanisms include: (1) enhanced convergence through interactions between the sea breeze, Galveston bay breeze, and urban heat island circulations, (2) enhanced convergence due to increased surface roughness over the city and/or destabilization of the boundary layer by the UHI, or (3) enhanced cloud condensation nuclei due to urban and industrial aerosol sources. In this study, a downscaling analysis of spatial and temporal trends in rainfall around the Houston Area is being conducted. The downscaling analysis concept involves identifying and quantifying urban rainfall anomalies at progressively smaller spatial and temporal scales using the TRMM satellite, ground-based radar, and a dense network of rain gauges. The goal is to test the hypothesis that the Houston urban district and regions in the climatological downwind region of the city exhibit enhanced rainfall amounts relative to the climatological upwind regions. TRMM was launched in 1997 and currently operates in a low-inclination (35 deg), non-sun-synchronous orbit at an altitude of 402 km (350 km prior to August 2001). The satellite analysis follows the methodologies described in Shepherd et al. (2002). Nearly five years of TRMM PR-derived mean monthly rainfall estimates are utilized to produce annual and warm season isohyetal analyses around Houston. Early results indicate that rainfall rates (mm/h) for the entire period are largest within 100 km northeast and east of Houston (e.g. the "hypothesized downwind region"). The mean rainfall rate over the Houston urban center is 30.5% larger than the upwind control region. The mean rainfall rate in the downwind region is 34.4% larger than the upwind region. An analysis of a parameter called the urban rainfall ratio (URR) illustrates that 65% (88%) of the satellite-derived rainfall rates in the downwind (upwind control) region are greater (less) than the mean background rainfall rate of the entire study region. When the data is stratified by summer months from 1998 to 2001 (June-August), even greater influence over and downwind of the urban area is observed in the statistics. This result is consistent with published reports of urban-generated rainfall being more prevalent in the warm season. The research demonstrates that the evolving TRMM satellite climatology is a credible way to detect mesoscale precipitation signatures that may be linked to urbanization. Early results also corroborate recent findings on Houston-induced convection/drainfall anomalies. Burian and Shepherd will report on other aspects of the downscaling analysis in future forums, but early rain gauge results are consistent with the satellite-based observations.
NASA Processes and Requirements for Conducting Human-in-the-Loop Closed Chamber Tests
NASA has specific processes and requirements that must be followed for tests involving human subjects to be conducted in a safe and effective manner. There are five distinct phases of test operations. Phase one, the test request phase, consists of those activities related to initiating, processing, reviewing, and evaluating the test request. Phase two, the test preparation phase consists of those activities related to planning, coordinating, documenting, and building up the test. Phase three, the test readiness phase consists of those activities related to verifying and reviewing the planned test operations. Phase four, the test activity phase, consists of all pretest operations, functional checkouts, emergency drills, and test operations. Phase five, the post test activity phase, consists of those activities performed once the test is completed, including briefings, documentation of anomalies, data reduction and archiving, and reporting. Project management processes must be followed for facility modifications and major test buildup, which include six phases: initiation and assessment, requirements evaluation, preliminary design, detailed design, use readiness review (URR) and acceptance. Compliance with requirements for safety and quality assurance are documented throughout the test buildup and test operation processes. Tests involving human subjects must be reviewed by the applicable Institutional Review Board (IRB).
Tests of the probability table method for unresolved resonances [Slides]
Abstract not provided.