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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
61

The chemical limnology of Lake Bonney, Antarctica, with emphasis on trace metals and nutrients

Weand, Barron L. January 1975 (has links)
Chemical parameters of Lake Bonney, southern Victoria Land, Antarctica, were closely monitored during the 1973-74 and 1974-75 austral summers using marine analytical techniques and the method of standard additions. Results were at variance with reports of several previous investigators. Inorganic nitrogen was found to be present in high concentrations, particularly in the monimolimnion, and the dominant inorganic species was generally ammonia. Orthophosphate-phosphorus concentrations in the mixolimnion were ordinarily less than 10 µg/l throughout the study. Water samples were analyzed for the presence of copper, cobalt, iron, manganese, molybdenum, and nickel using flameless atomic absorption. More than 90 percent of the mass of each trace metal was found to be in the monimolimnion. Manganese was by far the most abundant trace metal in the lake, and some evidence suggests it may present a toxicity problem to algae in the surface waters. Concentrations of copper potentially toxic to at least algal species in the lake were present in the monimolimnion and, at times, in the mixolimnion. Continuous monitoring of one meltstream showed flows to be highly variable. Most of the orthophosphate-phosphorus carried to the lake by this meltstream was transported during the first two weeks of flow, probably due to the leaching of phosphates from the products of weathering generated over the long Antarctic winter. Whereas the meltstreams were previously considered as potential sources of significant quantities of nitrogen and phosphorus, it was determined that they probably contribute relatively minor amounts of these nutrients. The loading of trace metals to the lake also appears to be of minor importance, with the possible exception of cobalt. A decided peak in sulfate concentration and concomitant drop in pH was observed during each field season. Because no precursor to the sulfate could be identified, the mechanism for this phenomenon is not apparent, but may be related to subterranean inflow. The hypothesis that there is intermittent subterranean inflow at depth in Lake Bonney was supported by fluctuations in various chemical parameters. / Ph. D.
62

Fatigue damage mechanisms in fiber reinforced composite materials including the effect of cyclic loading frequency

Williams, Richard Scott January 1975 (has links)
A broad-based investigation seeking to characterize fatigue damage mechanisms in fiber reinforced composite materials, accounting for the effect of cyclic loading frequency, is presented. A many faceted approach to the investigation was utilized; which included well documented strain-controlled fatigue tests, a scanning electron microscopy study, implementation of energy emission techniques (such as acoustic and thermal emissions), and the development of an energy-based failure theory. A detailed discussion of each aspect of the investigation is presented and, in each case, pertinent conclusions are drawn. The effect of cyclic loading frequency on fatigue damage development is documented and found to be substantial. A micro-mechanical damage model, which accounts for the effects of frequency and fiber/matrix interface strength, is developed. Using a first law analysis, a good correlation between acoustic and thermal emission with damage propagation and extent is developed. Finally, a new conceptual theory, called the Strain Energy Release-Potential Theory, is postulated. Predictions based on this theory are made and compared with experimental findings, resulting in substantial agreement. / Ph. D.
63

The institutionalization of citizen participation in the Clean Air Act

Brady, Gordon L. January 1975 (has links)
In recent years Citizen Interest Groups (CIGs) have become an important factor in the implementation of environmental regulations and hence in the allocation of scarce resources via the political process. This study examines the impact of environmental CIGs on the implementation of the Clean Air Act. It does so by focusing on how changes in various institutions have affected the efficacy of the principal CIG tools of litigation, lobbying, and media usage. The impact on CIG behavior of tax subvention, the judicial interpretation of standing and fee-shifting, and EPA implementation of provisions for citizen participation in the Clean Air Act is assessed. Los Angeles is employed as a case study in order to focus on the impact of the above-mentioned institutions on the implementation process. Positive criteria for the subvention of private externality producing activities are developed in the final chapter. / Ph. D.
64

An analysis of the role of the school psychologist in the Commonwealth of Virginia

Murray, Philip Allen January 1975 (has links)
The expectations of three groups--school superintendents, school psychologists, and school psychologist trainers--for the Virginia school psychologist's job performances, professional participations, and personal attributes were surveyed by means of a mailed opinionnaire. The degree of intrapositional and interpositional consensus was determined, as was the perceived importance of the school psychologist's generalized functions and the relative frequency of performance of each function. Certain demographic data were collected, and the effect of demographic variables on the expectations of role definers was investigated. The majority of the respondents held positive expectations for about two-thirds of the job performances of the school psychologist suggested by items of the opinionnaire. Most role definers held neutral to moderately positive expectations for the professional activities of the school psychologist, but held no strong preference regarding such personal attributes of the psychologist as age, sex, marital and parental status. The majority of respondents preferred that the school psychologist have training at least to the master's level, have training in education and psychology, and have completed a nine month internship. Higher levels of consensus within and between groups were found on expectations for the professional participations and personal attributes, than for the job performances of the school psychologist. The greatest agreement between role definers existed on items concerning the more traditional functions of the school psychologist, where positive expectations were almost universally expressed. The highest level of intrapositional consensus was found among school psychologist trainers; the lowest level among school psychologists themselves. The highest level of interpositional consensus existed between superintendents and trainers; the lowest level between superintendents and psychologists. Discordance between role definers resulted not so much from differences in opinion, as from differences in the intensity with which opinions were held. Although there was moderate disagreement between role definers regarding the relative importance of the school psychologist's functions generalized into ten major service areas, respondents appeared to agree as to whether the service area was most important, important, or least important. Most participants ranked diagnostic studies as the single most important functional area of the school psychologist. (School psychologist trainers, however, believed consultation with teachers a more important service area.) Findings support the assumption that school psychologists in Virginia are actually performing most frequently those functions the three role definer groups considered most important, and least frequently those functions that were considered least important. The effect of demographic variables on importance and frequency rankings was not found to be great. It was concluded that greater consensus regarding the role of the Virginia school psychologist exists today than in the past. Potential implications of the results of this study were discussed, and recommendations for further research offered. / Ed. D.
65

Stress distribution around holes in laminated composite plates

Huang, Chi-Hung January 1975 (has links)
A solution is presented for the stress distribution around holes in laminated composite plates under pure bending. The shear deformation, lamination theory is derived and employed for the analysis of circular, elliptical, square, and diamond-shaped holes piercing the laminated composite plate. Each layer of the laminate is assumed to be homogeneous and to have isotropic properties. Functional analysis employing complex variable methods is used to solve the governing equations. Using conformal mapping and boundary form perturbation techniques, the circular hole solution has been extended to the solution of the curvilinear hole case. These analytical solutions are compared with the solution obtained from a 72 DOF finite element method. The stress resultants and stress couples around the hole, the interlaminar stresses, as well as the tangential stress through the plate thickness are studied. In addition, the boundary layer phenomenon in the vicinity of the hole is presented. / Ph. D.
66

Application of the principle of minimization of entropy in the achievement of steady-state solutions for dynamic systems

Wells, Robert Ferrell January 1975 (has links)
The “Limits to Growth” controversy has identified attainment of a steady-state world system as an essential goal for human culture. This study investigates implications of steady-state systems using principles of thermodynamics in conjunction with Systems Dynamics simulation techniques. Evaluation of Forrester’s World Dynamics model shows it to degenerate in accordance with the dictates of the Second Law of Thormodync.mics. Two fundamental policy criteria are established for world society: 1. Maximization of the future horizon for mankind. 2. Satisfaction of basic quality-of-life requirements for all of mankind. Optimization principles for satisfaction of these criteria are derived from interrelationships found to exist between three physical laws (Einstein’s relativistic mass-energy and the First and Second Laws of Thermodynamics), non-equilibrium thermodynamics (Prlgogine’s Theorem of Minimum Entropy Production as the defining condition for a steady-state system) and a cultural law (the Golden Rule). Policy based on the Principles of Minimization of Entropy and Cooperative Behavior are presented as the optimal means for defining, achieving and maintaining long-term steady-state systems both locally and globally. It is shown that the “Golden Rule” shares with the thermodynamic concept of equilibrium the defining mechanism of “reversibility” (synonyms: reciprocity, self-returning, “frictionless”, ideal efficiency, etc.). This common criterion allows both concepts to be used as unambiguous, perfect standards for determining the relative effectiveness of actual performance (one in terms of cultural behavior and the other in terms of physical behavior). Recognition of this relationship (which reflects the fundamental tendency of natural systems to seek optimal stability conditions in the most efficient manner) is advanced as a means for achieving optimal steady-state solutions for complex cultural- physical systems; specifically: 1. Use the Principle of Minimization of Entropy (with respect to the equilibrium standard) when making decisions that essentially involve physical behavior. 2. Use the Principle of Cooperative Behavior (with respect to the Golden Rule standard) when making decisions that essentially involve cultural behavior. The effects of these policies are identical: the minimization of system “friction”; or, conversely, the maximation of system “welfare”. These principles are embedded as policy tables in Forrester’s World Dynamics model and used to demonstrate the conceptual feasibility of achieving truly long-term steady-state solutions satisfying desirable quality-of-life goals. In order to demonstrate the practical potential of such policies, the Principle of Minimization of Entropy is related to the engineering concept of Thermodynamic Analysis and advanced a method for evaluating Total Energy Systems. Two application schemes are presented as examples which represent the range of both Total Energy System technology and analytical procedure: 1. A manually calculated Decision Tree Analysis for a Wind Source Total Energy System emphasizing simple technology that can be immediately utilized world-wide (using indigenous “self-help” labor and materials) to satisfy small scale “biotechnic" community needs. 2. A DYNAMO simulation model for a Laser-Fusion Total Energy System offering the ultimate range in resource management technology needed to support complex, large-scale communities. The study is closed with a suggested subject for further research: development of an “Evolutionary Dynamics” model based on Prigogine’s thermodynamic concepts for “open” systems. / Ph. D.
67

Determining optimal policies for management of an aquatic ecosystem

Powers, Joseph E. January 1975 (has links)
A methodology was developed by which a state fish and game agency can determine Optimal Ecosystem Policies (OEP). This methodology consisted of: (1) an ecosystem simulation model which depicted a variety of interactions among and between species; (2) an objective function consisting of several criteria; and (3) a computer implemented optimization procedure designed to find the time sequence of decision activities which maximized the objective function. OEP was applied to a specific case study area, a stream fishery in Rich Creek, Monroe County, West Virginia. The simulation model consisted of a system of difference equations calculated for discrete time stages (one year time horizon). Interaction was modeled using a special queueing framework, where an animal's actions were governed by a preemptive priority sequence. Using the queueing framework, all interactions become density-dependent, and probability parameters may be estimated subjectively. Ration size, mortality, and reproduction were calculated and were inputs to population abundance, growth, and metabolism calculating routines. The criteria considered in the objective function in the Rich Creek study were: (1) catch per unit effort by the commercial operators summed over all time stages (a measure of benefits to the commercial fishermen); (2) the environmental stability measured by a diversity index; (3) the number of fishermen visiting the stream during the year (angler-days); and (4) the sum over the year of a measure of angler satisfaction (utility). The utility function was a function of the attributes: size of fish caught, species of fish caught, number of fish caught, and crowding by other anglers. The utility model was empirically determined and it was found to be multiplicative over the attributes. Terminal (year end) constraints in OEP were a budgetary constraint, a diversity constraint, and a commercial catch constraint. Thus, the objective was maximization of a linear combination of the four criteria subject to the three terminal constraints. The approximate optimal solution was found by search by Regression and Application of the Maximum Principle (RAMP search). Quadratic transition functions were fit to simulated data and the optimal policy was found for these transitions using the discrete maximum principle. This policy was returned to the simulation to generate new data and the procedure was iterated until a convergence criterion was met. Optimization and sensitivity analysis of the Rich Creek model showed that an adequate budget was needed to maintain levels of stocked trout (the preferred species) to produce relatively high levels of angler utility. At low budgets other species became more important and diversity became an active constraint. Diversity and commercial catch criteria conflicted, therefore optimal catch occurred early in the year so that diversity could recover later. Solutions were most sensitive to three system components: (1) human aspects such as population size, preferences, and angler abundance; (2) the temperature prediction function (it served as a driver for many other variables); and (3) trout biomass variables.Future research on Rich Creek should be directed toward these three components. / Doctor of Philosophy
68

Dr. Woodrow W. Wilkerson: his life and work as state superintendent of public instruction in Virginia, 1960-1974

Shufflebarger, Emmett Garnett January 1975 (has links)
The study concerned Dr. Woodrow W. Wilkerson who served as State Superintendent of Public Instruction for the Commonwealth of Virginia from August 16, 1960, to April 1, 1975. His length of service exceeded that of any of the thirteen previous superintendents in the 103-year history of public education in Virginia. The thesis of the study was that the Commonwealth of Virginia made strides toward improvement in the quality of education during the leadership of Dr. Wilkerson. A detailed biographical study of Dr. Wilkerson pointed out his unique personality influenced by all with whom he came in contact; his family, his church, his college professors, his educational associates, and others. The position of State Superintendent of Public Instruction was discussed with Dr. Wilkerson and six of his associates. The relationship of his position with the State Board of Education, the members of the General Assembly, the various governors, and the local division superintendents was presented. This composite description of the past fifteen years in public education in Virginia indicates how the position actually operated. The legal basis of the position of State Superintendent of Public Instruction was described. A procedure was established to identify and analyze changes which occurred in public education during Dr. Wilkerson's tenure. General measures of educational quality for the nation were identified. Specific educational goals in Virginia from various sources were established. These goals were classified and given priorities by a panel of experienced educators. A questionnaire was sent to eighteen carefully selected representatives of the Virginia educational community who ranked the goals according to their significance. Ten highest ranked goals were associated with measures of educational quality. A panel selected ten goals for which comparative educational data might be available. A collection of data for the years 1960 through 1974 in Virginia and the nation was made. In many cases comparable data were not available. A determination of the degree of success on the ten measures of quality was made. The questionnaire also indicated that the major educational goal in Virginia during Dr. Wilkerson's tenure was the standards of quality program. Dr. Wilkerson and close associates were interviewed concerning the development and implementation of the important program. Aspects of the program with which Dr. Wilkerson was involved were discussed in detail. An evaluation of the program and its effectiveness was presented. Dr. Wilkerson's accomplishments were influenced by the many issues of his time, by the personalities that he encountered, and by the limitations placed upon him by various political and economic conditions. Dr. Wilkerson and his unique personality had a marked effect upon public education in Virginia. The Commonwealth of Virginia made progress in the improvement in the quality of education during the leadership of Dr. Woodrow W. Wilkerson as State Superintendent of Public Instruction. / Doctor of Education
69

Money, income, and prices: the velocity of money in nine major O.E.C.D. economies

Rule, William Thomas January 1975 (has links)
The widespread growth of nominal income and the price level in many countries in the late 1960's and early 1970 1 s added to interest in the quantity theory of money. Most earlier work centered on the United States. This study investigates the applicability of some simple quantity theory hypotheses to a group of nine major non-U.S. O.E.C.D. economies. After a brief discussion of the quantity theory with attention to its applicability under regimes of fixed and floating exchange rates, there is a discussion of the estimation of quarterly GNP for countries not reporting full series, using related quarterly and annual data by generalized least squares methods. Analysis of the relationship between money and income is conducted using annual and quarterly data. Regressions of two measures of the money stock on nominal income, and of money per unit of output on the price level are estimated for annual data. Using quarterly data, distributed lags of money on nominal income are estimated. While there was found to be considerable variation in the closeness of the money-income relationship, the evidence suggests the broad applicability of the quantity theory within a wide range of monetary arrangements and exchange rate regimes. / Doctor of Philosophy
70

Nutrient characterization of swine fecal waste and utilization of these nutrients by swine

Holland, Morris Randolph January 1975 (has links)
Swine feces collected from finishing hogs was fed to 48 crossbred gilts averaging 125 kg in two total collection metabolism trials. Unprocessed feces (fresh) was used in one trial and dried feces was used in the other trial. Feces from the gilts fed the feces substituted rations were significantly higher in crude fiber, ether extract, crude protein, magnesium, copper, and zinc content in both the unprocessed and dry trials. The fecal concentration of ash, NFE, calcium, phosphorus, and potassium tended to remain constant, Phosphorus was the only urinary mineral which significantly increased as the level of feces substituted in the basal ration increased. Output of feces increased as the amount of feces substituted for the basal ration was increased with no differences in urinary output. Swine feces were found to be of less nutritive value than a basal corn-soybean meal ration, but nutrients were available. Digestion of dry matter, ash, crude fiber, ether extract, crude protein, and nitrogen-free extract was significantly reduced as either fresh or dried swine feces was substituted for the basal ration with digestion coefficients of (%): 52.3, 32.4, 50.5, 53.5, 62.7, and 48.5, respectively for the wet feces and 43.7, 30.7, 31.2, 54.7, 57.5, and 43.3, respectively for the dried feces, calculated by difference and regression, and averaged. The apparent absorption of most minerals analyzed was reduced as the level of feces substituted increased while the absorption and retention in grams per day was similar across treatments in most cases. / M.S.

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