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Articles 511 - 527 of 527
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A System Dynamics Approach To Modelling The Degradation Of Biochemical Oxygen Demand In A Constructed Wetland Receiving Stormwater Runoff, Leslie A. Mudgett
A System Dynamics Approach To Modelling The Degradation Of Biochemical Oxygen Demand In A Constructed Wetland Receiving Stormwater Runoff, Leslie A. Mudgett
Theses and Dissertations
The objective of this research was to develop a tool to aid the Air Force Environmental Manager in the identification of the design parameters of a constructed wetland system that may be optimized to provide a desired biochemical oxygen demand (BOD) removal efficiency during the treatment of Air Force stormwater runoff. The objective is achieved through the development and use of a system dynamics model which simulates the hydrological functions of a constructed wetland as well as the processes within the wetland responsible for degradation of BOD. Based on literature review, the primary mechanism responsible for the degradation of BOD …
A Comparison Of Response Surface Methodology And A One-Factor-At-A-Time Approach As Calibration Techniques For The Bioplume-Ii Simulation Model Of Contaminant Biodegradation, Benjamin Shuman
Theses and Dissertations
This thesis compared Response Surface Methodology (RSM) to the one-factor-at-a-time approach for calibrating the Bioplume-II simulation model of contaminant biodegradation. The MADE-2 data set from Columbus Air Force Base, Mississippi was used. The one-factor-at-a-time approach reduced the root-mean-squared (RMS) error for the flow to 0.921225 feet in a total of 36 runs of Bioplume-II. The RSM approach reduced the error criterion to 0.918875 in a total of 47 runs. The one-factor-at-a-time approach was unable to reduce the error below 67.1831 parts per billion (ppb) after 21 runs. The RSM approach reduced the RMS error to 67.0327 ppb after 47 runs. …
A Point Model Of Aquifer Cleanup With A Distribution Of First-Order Rate Parameters, Jon E. Hodge
A Point Model Of Aquifer Cleanup With A Distribution Of First-Order Rate Parameters, Jon E. Hodge
Theses and Dissertations
Many try modeling groundwater contaminant transport to predict it. Is this possible with rate-limited processes, and under what conditions? On occasion, cleanups go slower than predicted (tailing) and hazardous concentrations reappear after cleanup is thought complete (rebound). Rate-limited transport is blamed by many. When immobile water is present, diffusion from varied sizes and shapes of immobile regions can cause varied rate limitations (due to varied diffusion path lengths). Although known, most modelers represent these varied rate-limiting processes with a single 'representative' rate-parameter. This can yield poor predictions for long-term experiments, and the parameter is generally time and pump-rate dependent. This …
The Effects Of Vegetative Canopies On Atmospheric Dispersion, John R. Lindell
The Effects Of Vegetative Canopies On Atmospheric Dispersion, John R. Lindell
Theses and Dissertations
This research was conducted to improve our understanding of the effects of vegetative canopy-induced turbulence on the dispersion of air pollution. The computer model most often used to calculate atmospheric dispersion is the Gaussian plume model, which requires some method to compute the downwind dispersions coefficients. These coefficients are a parameterization of the atmospheric stability or the level of turbulence in the atmosphere. The Environmental Protection Agency's recommended parameterization scheme is the Pasquill-Gifford method. By comparing the Pasquill-Gifford method to the Modified Mitchell method using sigma theta, the standard deviation of the horizontal wind fluctuations, the relative precision of each …
A Decision Model For Environmental Assessment Of Process Waste Products, Kyle F. Byard
A Decision Model For Environmental Assessment Of Process Waste Products, Kyle F. Byard
Theses and Dissertations
Environmental managers must compare the potential impacts of waste products when deciding upon courses of action. The estimation and comparison of these impacts is a subjective process, and few methods of comprehensive, quantitative comparison of waste products currently exist. The intent of this study is to develop a decision methodology to evaluate the environmental impacts of waste products and to score them for comparison. The method will follow established system design principles and incorporate significant characteristics of the waste material. Scores derived to represent the environmental impacts of materials will then he analyzed employing statistical and probabilistic methods to assess …
Spatial Time-Series: Pollution Pattern Recognition Under Irregular Interventions, Samuel A. Wright
Spatial Time-Series: Pollution Pattern Recognition Under Irregular Interventions, Samuel A. Wright
Theses and Dissertations
The Fernald Environmental Restoration Management Corporation (FERMCO) has noted the introduction of arsenic contamination to groundwater around the area of the groundwater recovery system, which captures uranium contaminated groundwater. The introduction of arsenic occurs during high levels of pumping and is particularly sensitive to the western two of the five pumps. Auto-Regressive Moving Average (ARMA) and Spatial-Temporal ARMA (STARMA) empirical analyses are used to model the level of arsenic contamination found through time. The intervention of varied levels of pumping is modeled with a transfer function using analytic techniques to create a causal intervention transfer function input series to give …
Experiment Using Infrared Spectroscopy To Study The Effect Of Soil Characteristics Upon The Rate Of Trichloroethylene Desorption, Benjamin T. Kindt
Experiment Using Infrared Spectroscopy To Study The Effect Of Soil Characteristics Upon The Rate Of Trichloroethylene Desorption, Benjamin T. Kindt
Theses and Dissertations
This research investigated the influence of soil characteristics on the desorption of trichloroethylene (TCE). TCE is one of the most common contaminants at Superfund sites. Unfortunately, extraction of TCE from contaminated soils has been hindered by its slow and poorly understood desorption from soil particles. The rate and progress of desorption of TCE from seven types of soil with varying particle diameters and elemental compositions was measured using optical absorption techniques. Fitting the data to the Langmuir Isotherm functional form predicted in the literature yielded parameters for the desorption rate and total amount desorption each soil type. These parameters were …
Simulation Of Hydrologic Influences On Wetland Ecosystem Succession, Robert A. Pompilio
Simulation Of Hydrologic Influences On Wetland Ecosystem Succession, Robert A. Pompilio
Theses and Dissertations
This research focuses on the development of a simulation model to determine the effects of hydrological influences on a wetland ecosystem. The model allows perturbations to the inputs of various wetland data which in turn, influences the successional development of the ecosystem. This research consisted of converting a grassland ecosystem model to one which simulates wetland conditions. The critical factor in determining the success of wetland creation is the hydrology of the system. There are four of the areas of the original model which are affected by the hydrology. The model measures the health or success of the ecosystem through …
How Effective Has The Air Force Been In Eliminating Its Dependence On Ozone Depleting Chemicals?, L. Susan Willard
How Effective Has The Air Force Been In Eliminating Its Dependence On Ozone Depleting Chemicals?, L. Susan Willard
Theses and Dissertations
This research was undertaken to determine how effectively the Air Force had eliminated its dependence on Ozone Depleting Chemicals. The research was limited to analyzing the impact of ODCs on major acquisition programs. Results indicated existing variables which may be impeding full implementation. Also identified were lessons learned which could be applied to future environmental legislation with potential impact on acquisition programs. In- depth telephonic interviews were conducted with Program Directors responsible for the development and fielding of major Air Force acquisition programs. Analysis revealed that ODCs substantially impacted the acquisition programs to the extent that many programs had classified …
Development Of An Analysis Method To Identify The Root Causes Of Finding From The Air Force Environmental Compliance Assessment And Management Program (Ecamp), Frederick B. Cade
Development Of An Analysis Method To Identify The Root Causes Of Finding From The Air Force Environmental Compliance Assessment And Management Program (Ecamp), Frederick B. Cade
Theses and Dissertations
The Air Force is committed to being a national leader in achieving environmental compliance. This commitment is exemplified by the Air Force Chief of Staffs goal of no 'notices of violation.' This goal, however, has proven to be elusive. In the early 1990s, the number of Air Force notices of violation (NOVs) increased by 73%, from 103 to 178. One of the reasons may be findings from the Environmental Compliance Assessment and Management Program (ECAMP) are not being utilized effectively. This research developed an analysis method to identify root causes of ECAMP findings. The model emphasized the use of performance …
Coherence And Usability Of An Environmental Impact Statement, Jill A. Easterly
Coherence And Usability Of An Environmental Impact Statement, Jill A. Easterly
Theses and Dissertations
The purpose of this research effort was to investigate the application of certain principles of effective communication to improve the comprehension, and ultimately the usability, of an Environmental Impact Statement (EIS). Principles from cohesion theory (an area of research describing effective design) were used to manipulate the design of select sections of two sample EISs. Each sample EIS was altered to manipulate the presence and/or absence of visual and linguistic cohesion. Subjects were required to read select versions from each section of the two sample EISs and answer four short answer questions. The dependent variables were accuracy in answering the …
Use Of Infrared Spectrometry To Determine The Effect Of Temperature On The Description Rates Of Trichloroethylene From Plastic Clay 98b, Abdellatif Fares
Use Of Infrared Spectrometry To Determine The Effect Of Temperature On The Description Rates Of Trichloroethylene From Plastic Clay 98b, Abdellatif Fares
Theses and Dissertations
This thesis investigated the influence of temperature on the desorption rated of trichloroethylene (TCE) from plastic clay. It was expected that an increase in temperature will cause an increase in both the desorption rates of TCE and in the desorbed quantity. Previous studies on other chemicals indicated a faster decrease in the remaining sorbed concentration with an increase in temperature. This research made use of the infrared optical absorption technique. IR spectroscopy was used to measure the concentration of the vapor TCE that desorbed from the soil. The soil was exposed to liquid TCE for 2 days then placed inside …
Estimating Groundwater Flow Parameters Using Response Surface Methodology, Leo C. Adams
Estimating Groundwater Flow Parameters Using Response Surface Methodology, Leo C. Adams
Theses and Dissertations
This thesis examined the use of response surface methodology RSM as a parameter estimation technique in the field of groundwater flow modeling. Using RSM, an attempt was made to calibrate three hydraulic parameters porosity, transverse permeability, and rate of recharge of an existing two- dimensional, steady-state flow model. The model simulated groundwater flow for a portion of landfill 10 located on Wright-Patterson Air Force Base, Ohio. The model had previously been calibrated by graphical matching observed water-levels to predicted water-levels. Using the parameter values from the earlier calibration effort as a starting point, a central composite design was developed and …
Air Pollution Transport Modeling, David M. Paal
Air Pollution Transport Modeling, David M. Paal
Theses and Dissertations
This research effort addresses modeling of the transportation of air pollution in the atmosphere and the numerical analysis of the partial differential equations used in such modeling. Three Gaussian models are examined and compared using example problems. Several finite difference schemes are developed to solve the partial differential equations used in air pollution transport modeling. This study examines three Gaussian models SCREEN, AFTOX, and the program GAUSPLUM. The model GAUSPLUM is developed in this study and uses the Ada programming language and the analytic solution to the advection- diffusion equation. Numerical analysis of the partial differential equations PDE used in …
A Study Of Sensitive Lands In Provo, Doris R. Monson
A Study Of Sensitive Lands In Provo, Doris R. Monson
Theses and Dissertations
Sensitive lands are being developed in great quantity. Because of problems caused by the development of sensitive lands, Provo City has developed land use ordinances. This thesis examines the development of Provo's ordinances along with the development of its sensitive lands. It determines ways that the city can strengthen their land use ordinances and avoid some of the problems found in sensitive land development.
The Historical Development Of Wasatch Trails In Salt Lake County, Clyde Brian Hardy
The Historical Development Of Wasatch Trails In Salt Lake County, Clyde Brian Hardy
Theses and Dissertations
In this study investigation was made concerning the etiology of the foot trails that thread their way through Wasatch Forest lands in Salt Lake county. The time delimitation was 1847 to 1975.
The origin of the majority of these trails dates back to the nineteenth century and is closely tied to the efforts of pioneers who labored to wrest a living from semi-arid land. Early lumbering, livestock operations, mining activities, water collection systems, and pioneer recreation all provided impetus for trail development. In a sense these trails are a kind of anthology of human endeavor.
Passing into the twentieth century …
The Mormon Role In Irrigation Beginnings And Diffusions In The Western States: An Historical Geography, Kelly C. Harper
The Mormon Role In Irrigation Beginnings And Diffusions In The Western States: An Historical Geography, Kelly C. Harper
Theses and Dissertations
Irrigation has played an important part in the development of the Western States. Its beginnings have often been associated with the Mormon settlement in Utah. However, irrigation had its inception in the West long before the Mormons came to the Great Basin in 1847. The spatial extent of irrigation before this date included limited acreage in nearly every Western State.
Before their arrival in the Great Basin the Mormons had become acquainted with irrigation methods. Knowledge of irrigation had diffused to them primarily from the Spanish in the Southwest. Thus, they were well prepared to begin their irrigation enterprises in …