Computational Fluid Dynamic Studies of Vortex Amplifier Design for the Nuclear Industry—I. Steady-State Conditions

In this study the effects of changes to the geometry of a vortex amplifier are investigated using computational fluid dynamics (CFD) techniques, in the context of glovebox operations for the nuclear industry. These investigations were required because of anomalous behavior identified when, for operational reasons, a long-established vortex amplifier design was reduced in scale. The aims were (i) to simulate both the anomalous back-flow into the glovebox through the vortex amplifier supply ports, and the precessing vortex core in the amplifier outlet, then (ii) to determine which of the various simulated geometries would best alleviate the supply port back-flow anomaly. Various changes to the geometry of the vortex amplifier were proposed; smoke and air tests were then used to identify a subset of these geometries for subsequent simulation using CFD techniques. Having verified the mesh resolution was sufficient to reproduce the required effects, the code was then validated by comparing the results of the steady-state simulations with the experimental data. The problem is challenging in terms of the range of geometrical and dynamic scales encountered, with consequent impact on mesh quality and turbulence modeling. The anomalous nonaxisymmetric reverse flow in the supply ports of the vortex amplifier has been captured and the mixing in both the chamber and the precessing vortex core has also been successfully reproduced. Finally, by simulating changes to the supply ports that could not be reproduced experimentally at an equivalent cost, the geometry most likely to alleviate the back-flow anomaly has been identified

Healthy Eating Habits of School-Aged Children in Rural Areas

This study provides further understanding of interventions to impact healthy eating habits in children. Children received a short lesson on healthy eating habits, and took a pre and post test to see how much their knowledge improved. Test means increased from pre-test to post-test (51.76 to 60.48). A paired samples t-test showed the results to be statistically significant (p\u3c0.002). The findings of this study supports providing elementary school aged children with nutritional education may impact their ability to make wiser, and healthier choices regarding food intake

The Negro in southern fiction: 1920-1940

Dissertation (Ph.D.)--Boston University, 1947. This item was digitized by the Internet Archive

Addressing Issues in the Detection of Gene-Environment Interaction Through the Study of Conduct Disorder

This work addresses issues in the study of gene-environment interaction (GxE) through research of conduct disorder (CD) among adolescents and extends the recent report of significant GxE and subsequent replication studies. A sub-sample of 1,299 individual participants/649 twin pairs and their parents from the Virginia Twin Study of Adolescent and Behavioral Development was used for whom Monoamine Oxidase A (MAOA) genotype, diagnosis of CD, maternal antisocial personality symptoms, and household neglect were obtained. This dissertation (1) tested for GxE by gender using MAOA and childhood adversity using multiple approaches to CD measurement and model assessment, (2) determined whether other mechanisms would explain differences in GxE by gender and (3) identified and assessed other genes and environments related to the interaction MAOA and childhood adversity. Using a multiple regression approach, a main effect of the low/low MAOA genotype remained after controlling other risk factors in females. However, the effects of GxE were modest and were removed by transforming the environmental measures. In contrast, there was no significant effect of the low activity MAOA allele in males although significant GxE was detected and remained after transformation. The sign of the interaction for males was opposite from females, indicating genetic sensitivity to childhood adversity may differ by gender. Upon further investigation, gender differences in GxE were due to genotype-sex interaction and may involve MAOA. A Markov Chain Monte Carlo approach including a genetic Item Response Theory modeled CD as a trait with continuous liability, since false detection of GxE may result from measurement. In males and females, the inclusion of GxE while controlling for the other covariates was appropriate, but was little improvement in model fit and effect sizes of GxE were small. Other candidate genes functioning in the serotonin and dopamine neurotransmitter systems were tested for interaction with MAOA to affect risk for CD. Main genetic effects of dopamine transporter genotype and MAOA in the presence of comorbidity were detected. No epistatic effects were detected. The use of random forests systematically assessed the environment and produced several interesting environments that will require more thoughtful consideration before incorporation into a model testing GxE

Heave-pitch-roll analysis and testing of air cushion landing systems

The analytical tools (analysis and computer simulation) needed to explain and predict the dynamic operation of air cushion landing systems (ACLS) is described. The following tasks were performed: the development of improved analytical models for the fan and the trunk; formulation of a heave pitch roll analysis for the complete ACLS; development of a general purpose computer simulation to evaluate landing and taxi performance of an ACLS equipped aircraft; and the verification and refinement of the analysis by comparison with test data obtained through lab testing of a prototype cushion. Demonstration of simulation capabilities through typical landing and taxi simulation of an ACLS aircraft are given. Initial results show that fan dynamics have a major effect on system performance. Comparison with lab test data (zero forward speed) indicates that the analysis can predict most of the key static and dynamic parameters (pressure, deflection, acceleration, etc.) within a margin of a 10 to 25 percent

Healthy Eating Habits of School Aged Children in Rural-Areas

Childhood obesity is a growing epidemic in the United States. Despite the programs that have been implemented and the information that has been disseminated to prevent and stop this epidemic, childhood obesity is still very prevalent among society. The aim of this study is to determine why obesity is still such an epidemic, specifically in rural areas of the United States. This study also provides further understanding of interventions to impact healthy eating habits in children. During the intervention implemented, children received a short lesson on healthy eating habits and the “Healthy Food Plate Model.” After, they took a pre test and a post test to see how much their knowledge improved from the lesson. Both tests included ten multiple-choice questions, arranged in differing orders. Test means increased from pre-test to post-test (51.76 to 60.48). A paired samples t-test showed the results to be statistically significant (p\u3c0.002). The findings of this study supports providing elementary school aged children with nutritional education may impact their ability to make wiser, and healthier choices regarding food intake. The findings also show that further research is needed in this topic area, and children would greatly benefit from continuous, routine nutritional lessons during elementary school

Dynamic heave-pitch analysis of air cushion landing systems

A program to develop analytical tools for evaluating the dynamic performance of Air Cushion Landing Systems (ACLS) is described. The heave (vertical) motion of the ACLS was analyzed, and the analysis was extended to cover coupled heave-pitch motions. The mathematical models developed are based on a fundamental analysis of the body dynamics and fluid mechanics of the aircraft-cushion-runway interaction. The air source characteristics, flow losses in the feeding ducts, trunk and cushion, the effects of fluid compressibility, and dynamic trunk deflections, including ground contact are considered. A computer program, based on the heave-pitch analysis, was developed to simulate the dynamic behavior of an ACLS during landing impact and taxi over an irregular runway. The program outputs include ACLS motions, loadings, pressures, and flows as a function of time. To illustrate program use, three basic types of simulations were carried out. The results provide an initial indication of ACLS performance during (1) a static drop, (2) landing impact, and (3) taxi over a runway irregularity

Application of Differential Global Positioning System (DGPS) Indexing to Remote Sensing Photogrammetry

In photogrammetry, radial displacement occurs when the point being imaged is not at the elevation of the mean datum. It is standard practice in photogrammetric mapping to provide 60% forward overlap and 30% sidelap between adjacent photographs. Such overlap is often required as the aircraft is subject to altitude variations, tip, and tilt as the flight proceeds. Differential GPS is used to minimize 3-D positional variations and provide precise indexing of the photographic exposures. This paper reports on the application of differential GPS to scientifically map the “uplight” emanating from the Ames, IA area, which serves to provide preliminary photogrammetry for Iowa State University engineering students working on Aerial Integrated Platform (AIP) senior projects. The data and it’s acquisition technique also serves as a model for low cost mapping of non-downward municipal and business lighting practices contributing to light pollution

An approach to CMG steering using feedback linearization

This paper presents an approach for controlling spacecraft equipped with control moment gyroscopes. A technique from feedback linearization theory is used to transform the original nonlinear problem to an equivalent linear form without approximating assumptions. In this form, the spacecraft dynamics appear linearly, and are decoupled from redundancy in the system of gyroscopes. A general approach to distributing control effort among the available actuators is described which includes provisions for redistribution of rotors, explicit bounds in gimbal rates, and guaranteed operation at or near singular configurations. A particular algorithm is developed for systems of double-gimbal devices, and demonstrated in two examples for which existing approaches fail to give adequate performance