Investigations of simulated aircraft flight through thunderstorm outflows

The effects of wind shear on aircraft flying through thunderstorm gust fronts were investigated. A computer program was developed to solve the two dimensional, nonlinear equations of aircraft motion, including wind shear. The procedure described and documented accounts for spatial and temporal variations of the aircraft within the flow regime. Analysis of flight paths and control inputs necessary to maintain specified trajectories for aircraft having characteristics of DC-8, B-747, augmentor wing STOL, and DHC-6 aircraft was recorded. From the analysis an attempt was made to find criteria for reduction of the hazards associated with landing through thunderstorm gust fronts

Frequency distributions: from the sun to the earth

The space environment is forever changing on all spatial and temporal scales. Energy releases are observed in numerous dynamic phenomena (e.g. solar flares, coronal mass ejections, solar energetic particle events) where measurements provide signatures of the dynamics. Parameters (e.g. peak count rate, total energy released, etc.) describing these phenomena are found to have frequency size distributions that follow power-law behavior. Natural phenomena on Earth, such as earthquakes and landslides, display similar power-law behavior. This suggests an underlying universality in nature and poses the question of whether the distribution of energy is the same for all these phenomena. Frequency distributions provide constraints for models that aim to simulate the physics and statistics observed in the individual phenomenon. The concept of self-organized criticality (SOC), also known as the "avalanche concept", was introduced by Bak et al. (1987, 1988), to characterize the behavior of dissipative systems that contain a large number of elements interacting over a short range. The systems evolve to a critical state in which a minor event starts a chain reaction that can affect any number of elements in the system. It is found that frequency distributions of the output parameters from the chain reaction taken over a period of time can be represented by power-laws. During the last decades SOC has been debated from all angles. New SOC models, as well as non-SOC models have been proposed to explain the power-law behavior that is observed. Furthermore, since Bak's pioneering work in 1987, people have searched for signatures of SOC everywhere. This paper will review how SOC behavior has become one way of interpreting the power-law behavior observed in natural occurring phenomenon in the Sun down to the Earth

Southwest Research Institute assistance to NASA in biomedical areas of the technology utilization program Final report, 1 Nov. 1967 - 30 Nov. 1968

Southwest Research Institute activities in technology utilization program in biomedical areas, Nov. 1967 - Nov. 196

Health Risk of Obesity in Native American Adolescents

Recent reports demonstrate the need to improve methods for identifying obesity among adolescent minority populations, especially among Native American adolescents. Our study examined several anthropometric measures to see which one was the best indicator of obesity for Native American adolescents. We compared our data with that provided by the Centers for Disease Control and Prevention (CDC), and the National Health and Nutrition Examination Surveys (NHANESIII). We examined which measures diï¬ered signiï¬cantly from the NHANESIII, and which were most eï¬ective for measuring obesity in Native American adolescents. Our study population represented a cross-sectional, epidemiological population (N=183) of Native American students (ages 14-18) from diverse tribal backgrounds at an urban residential high school. We obtained baseline anthropometric measurements of height, weight, waist, triceps skin-fold, and calf skin-fold measures from the Native American students and compared this information with reference data to assess weight classiï¬cation by body mass indices for our population. Under the conditions of our study, we found the calf skin-fold measure to be the best indicator of normal weight in male Native American adolescents, and the triceps skin-fold measure to be the best indicator of obesity in male Native American adolescents. The assessment of health risk by anthropometric measures we obtained appears appropriate for predicting obesity and developing eï¬ective interventions for Native American adolescents in general. Correlations between anthropometric measures and obesity in our study population may prove of signiï¬cant interest for monitoring obesity prevention initiatives for Native American adolescents

Validation of Observed Bedload Transport Pathways Using Morphodynamic Modeling

Phenomena related to braiding, including local scour and fill, channel bar development, migration and avulsion, make numerical morphodynamic modeling of braided rivers challenging. This paper investigates the performance of a Delft3D model, in a 2D depth-averaged formulation, to simulate the morphodynamics of an anabranch of the Rees River (New Zealand). Model performance is evaluated using data from field surveys collected on the falling limb of a major high flow, and using several sediment transport formulas. Initial model results suggest that there is generally good agreement between observed and modeled bed levels. However, some discrepancies in the bed level estimations were noticed, leading to bed level, water depth and water velocity estimation errors