The scanning laser Doppler vibrometer (SLDV) provides the capability necessary for collecting a broad-band spatially dense data set. A laser-based broad-band spatially dense automated data acquisition system is presented and verified. The motivation for such a system is to provide vibration data at many frequencies and spatial locations to allow a more complete dynamic characterization of a structure. The acquisition system interfaces an SLDV to a frequency analyzer and a Silicon Graphics Crimson workstation. The system allows the user to specify the frequency range, scanning area, and spatial density. The system moves the laser beam, collects and downloads data for the specified area and spatial density. The system post-processes the data compensating the measurements for calibrations and then computes the complex-valued Frequency Response Function (FRF), and coherence plots. The data acquisition system is used to collect FRF data for a beam hanging with simulated free-free boundary conditions. Examples of the FRFs are presented and the data verified by extracting the natural frequencies, damping, and mode shapes of the system. The experimental natural frequencies were compared with those predicted by Euler-Bernoulli beam theory. The comparison yielded less than an 8% difference for the first seven transverse bending modes extracted. The mode shapes were compared by the Modal Assurance Criterion to show the orthogonality of the modes and a comparison with theory. In each of the cases above, the comparisons yielded results that indicated the modes were both orthogonal and close to theory. The overall conclusion based on the above verification was that the system can be used to collect spatially dense broad-band vibration data that can be used to characterize structures. / Master of Science

M.S.

An experimental apparatus was built and operated for the measurement of moisture permeability of building materials. The data are for use in resolution of problems associated with moisture buildup in porous building materials. The apparatus is capable of maintaining simultaneous humidity and temperature differences across a test specimen. In contrast with existing experimental methods, the relative humidity on either side of the specimen is controlled without the use of quiescent saturated salt solutions. Forced-air convection at the surface of the specimen is used, resulting in uniform spatial conditions and faster results. Data are obtained for fiberboard sheathing at various temperature and humidity setpoints. The apparatus consists of two environmental chambers between which a wood-based test specimen is sealed. An external forced-air conditioning system using distilled water and molecular sieve desiccant humidifies or dries the chamber air as needed. The moisture transfer rate across the specimen is determined gravimetrically: the desiccant column is weighed to measure its change in mass as a result of moisture diffusion across the specimen. The apparatus is capable of maintaining relative humidities over a range of 5 to 65 percent RH, with a temperature difference across the specimen of up to 20°C. Furthermore, the apparatus is capable of automated relative humidity and temperature control to within ±0.5 percent RH and ±0.5°C of the setpoints, respectively. Test results for fiberboard sheathing subjected to a range of humidity and temperature conditions are presented. Results are compared with the limited data from the literature. Recommendations for improvement of the data measurement methods are included. / Master of Science

Overwinter survival of wild turkeys on industrial forests managed for short-rotation pines (treatment) and typical Piedmont forests and farmland (control), was investigated in Virginia's central Piedmont during 1986-1988. Ninety-six percent of the turkeys (N =106) were captured in early fall with alpha-chloralose laced bait. Sixty-three percent of the captured turkeys recovered and were released with transmitters; 15% were released without transmitters; and 21% died from capture related causes. Overwinter survival for all turkeys was <2% regardless of area or year. Daily survival was lower on the control areas (P < 0.01), however, due to the small (13) and scattered sample of turkeys captured over the 3 years on control areas, these data were omitted from further analyses. Daily survival on treatment areas over the 3 years was 97.6%. Thirty-seven percent of radio-equipped turkeys on treatment areas died within 2 weeks of release suggesting that factors related to the trapping process influenced survival. Possibilities considered were residual effects from alpha-chloralose, capture myopathy, and/or a negative effect from the transmitter and/or harness. Four weeks after release daily survival rates improved significantly (P < 0.01) indicating the influence from trapping had subsided. While hardwoods composed 38% of the primary treatment area, 65% of turkeys died in hardwood stands; predation accounted for 81% of the turkey mortality (N =42). Field evidence and necropsy results plus scent station data indicated that gray foxes (Urocyon cinereoargenteus) were the main turkey predators. Fox scats contained no detectable turkey remains but indicated that eastern cottontails (Silvilagus floridanus) were a primary prey species. / Master of Science

Master of Science

The conventional design methods for sheet-pile cellular cofferdams were developed in the 1940's and 1950's based on field and limited experimental observations. The analytical techniques of the day were unable to account for the complexities involved. The procedures used only rudimentary concepts of soil-structure interaction which do not exhibit the true response of the cofferdam for most circumstances. During the past decade it has been demonstrated that with proper consideration of the soil-structure interaction effects, the two-dimensional finite element models can be powerful tools in the investigation of cellular cofferdam behavior. However, universal implementation of the findings of these analyses was difficult to justify, since uncertainties remain about the assumptions made in arriving at the two-dimensional models. The only way to address these uncertainties was to perform a three-dimensional analysis. This investigation has focused on the study of the three-dimensional behavior of Lock and Dam No. 26 (R) sheet—pile cellular cofferdam. The work involved the development of a new three-dimensional soil-structure interaction finite element code for cellular cofferdam modeling, and the application of the new code to the study of the behavior of the first- and second-stage cofferdam at Lock and Dam No. 26 (R). The new code was used to study the cell filling process where the main cell is filled first with the subsequent filling of the arc cell. The finite element results show that interlock forces in the common wall were 29 to 35 percent higher than those in the main cell which are less than those calculated by conventional methods and compare well with the observed values. After cell filling, the new code was used to model the cofferdam under differential loading due to initial dewatering of the interior of the cofferdam and changes in river levels. The finite element analysis results show that increasing differential water loads cause the confining stresses in the cell fill to increase which results in a decrease in the level of mobilized shear strength in the cell fill. This explains why the cellular cofferdam can withstand extremely high lateral loads and lateral deformations without collapsing. / Ph. D.

The objectives of this study were: (1) to estimate the effects of certain non-genetic sources of variation in weight, gnde, and condition of beef cows; (2) to estimate the heritability of weight, grade. and condition of beef cows; and (3) to estimate the genetic, phenot;rpic, and environmental correlations between weight, grade, and condition of beef cows. Weights, grades., and condition scores taken on 1371 Angus cows were used to evaluate the genetic and environmental nature of these traits. This sample of cows represented 365 sire groups. Four models were used in this study: 1. Model A - Cow weight and grade were considered dependent variables; herds and sires within herds were considered random independent variables; and season, age, condition, nursing status, and their interactions were considered fixed independent variables. Least-squares procedures involving Henderson's (1953) Method II were used to adjust tor fixed effects and to obtain variance and covax-iance components. Heritability estimate and correlation coefficients were obtained by paternal half-sib analysis. 2. Model B differed from Model A in that condition 3 score was considered a dependent variable instead of an independent variable. 3. Model C was the same as Model A except that the coefficients (kₒ and k₂) for the within sire (σw²) component of variance included in the among sire and herd adjusted expected mean squares (EMS) were considered unity whereas as in Model A they were calculated according to Method II of Henderson. 4. Model D - Heritability estimates were computed by doubling the estimate of intra-sire regression of offspring on dam from 198 dam-daughter pairs representing 63 sire groups. The dam-daughter pairs were part of the group or 1371 cows. The results of this study indicated that season, age, condition score, nursing status, and age by nursing status remain significant when condition score was not considered as a fixed environmental effect (Model B). However, a comparison of the magnitude of the mean squares for these effects in Models A and B indicated that season, age, and nursing status are highly confounded with condition score. Season and flesh condition were found to have a significant effect on grade of beef cows when they were included in the same model (Model A). When condition score was not included (Model B) age had a significant effect on grade. Age, season, and nursing status were found to have a significant effect on flesh condition (Model B). Paternal half-sib heritability estimates for cow weight using Models A, B, and C were 0.38 ± 0.11, 0.29 ± 0.11, and 0.56.± 0.11, respectively. Estimates for grade from the same models were 0.49 ± 0.11, 0.43 ± 0.11, and 0.67 ±0.12, in that order. Estimates from Model A should be the most reliable. The differences in the estimates from Models A, B, and C, illustrate that variation in heritability estimates is not entirely due to genetic differences. Considerable variation can occur depending on how much adjustment has been made to fixed effects, and the methods used in estimating the variance and covariance components. The heritability estimates of cow weight and grade obtained by intra-sire regression of offspring on dam were 0.22 ± 0.14 and 0.10 ± 0.06, respectively. The paternal half-sib heritability estimate for condition score was 0.31 ± 0.11, which implies that adjusting cow weights and grades for condition may actually involve adjusting for genetic differences as well as differences due to environmental influences. The correlation between weight and grade or beef oowe was found to be largely genetic whereas the correlation between condition and cow weight or grade was primarily environmental. / Ph. D.

This study was conducted to investigate the factors that affect the duration of breastfeeding in low and middle income women, and to determine if low income women have a greater incidence of decreased duration of breastfeeding. Specifically, the effects of early introduction of formula and solid food and mother’s perceived inadequate milk supply, on the duration of breastfeeding, was researched. A questionnaire was developed and one on one interviews conducted on 147 women who breastfed a baby within the past five years. Data analysis included crosstabulation of selected variables, descriptive analyses, and chi square analyses. Results indicated that the majority of the women surveyed introduced formula early, were long term breastfeeders, between the ages of 30-39, and college graduates. There was no difference in duration of breastfeeding between women of low and middle incomes, however, women of middle income terminated breastfeeding early to return to work or school and tended to introduce formula earlier than low income women. Furthermore, mothers who introduced formula or solid foods early, were generally short term breastfeeders. Mothers who introduced formula and solid foods early cited insufficient milk supply as their main reason for terminating breastfeeding. Therefore, mothers perceived to have an insufficient milk supply, tend to introduce formula and solid foods early, thus, contributing to a possible decrease in duration of breastfeeding. / Master of Science

LORD, shall we not bring these gifts to your service? Shall we not bring to your service all our powers For life, for dignity, grace and order, And intellectual pleasures of the senses? The LORD who created must wish us to create And employ our creation again in His service Which is already His service in creating. For man is joined spirit and body, And therefore must serve as spirit and body. Visible and invisible, two worlds meet in Man; Visible and invisible must meet in his temple; You must not deny the body. Choruses from "The Rock" T.S. Eliot We read in this stanza, from a T.S. Eliot poem, a description of man. Here we find man as a created being experiencing the two separate worlds that merge within him. We witness the coexistence of these two worlds in life and death, in our ideals and our temporality, in what we desire to be and what we are. This thesis is a study (in architectural terms) of humanity touching the ideal, of the ephemeral brushing the eternal. And beauty, I must not deny beauty. / Master of Architecture

The effects of time and stress level were investigated in cross-ply laminates to gain more understanding on the damage events in composites. Analytical predictions of the effect of stress level were performed for the case of linear elastic materials. The predictions were based on energy methods and linear elastic fracture mechanics. Damage was simulated with a Monte Carlo numerical scheme. The predicted results corresponded well with experimental data in the literature. Experimental testing was performed on cross-ply laminates to gain a better understanding of the effect of time and rate on matrix cracking. The tests were performed on Kevlar/epoxy and graphite/epoxy [0/90₃]₈ laminates. The results indicate that the stress levels required for matrix cracking are a function of how fast the specimens were loaded. Also, significant time dependent damage was observed in cross-ply laminates which were subjected to sustained loads. / Master of Science