A method is surveyed for telephone communication using a predictive adaptive delta modulator. This method is based on an estimation of the input waveform and an encoding of the signal into a digital sequence. The Kalman Filter does this estimation to filter out some of the noise, thus increasing the fidelity of the output to the original signal. The adaptive delta modulator does the encoding and allows the digital output to be reconstructed by a decoder which is identical to the feedback portion of the encoder. In implementing the adaptive delta modulator, a bi-state quantizer and tri-state quantizer are presented for comparison. Since the grannular region difficulties can be eliminated by the tri-state quantizer, the tri-state quantizer ADM provides a better stability. The present design also consists of a predictor which is based on the theory of a Taylor series expansion in order to match the overload rate whenever the signal slope becomes too sharp. The results indicate that the present design is suitable for implementation when the incoming messages are highly correlated-implying rapid signal sampling. / Master of Science

The behavior of fishes in and around power plant discharges has not been adequately explored despite the recent proliferation of electric generating stations. This study investigated the response of fish to heated and/or chlorinated waters in a field laboratory. Carp (Cyprinus carpio), channel catfish (Ictalurus punctatus) and golden shiners (Notemigonus crysoleucas) were tested at 6, 12, 18, 24 and 30-C acclimation temperatures in a steep concentration gradient. Residence time in the treated water was determined to be the most simple and sensitive index of avoidance behavior. TRC, CRC, and FRC avoidance thresholds varied between species and acclimation temperatures. HOCl avoidance thresholds were consistent between acclimation temperatures, suggesting that HOCl is the primary constituent of the TRC controlling avoidance behavior. Trials were conducted at 12 and 24 C in which the treated water was heated to a preferred temperature, derived in a shallow horizontal temperature gradient. At low chlorine doses fish significantly preferred the warmer water, whereas at high chlorine doses, the fish were repelled by the treated water. The TRC, CRC, and FRC avoidance thresholds varied between fish species, but the HOCl avoidance thresholds were similar for all species at 24 C. The avoidance thresholds for the carp and golden shiners were well below 96hrLC₅₀ values, signifying that they can avoid dangerous solutions before they are adversely affected. The channel catfish avoidance thresholds are slightly greater than reported 96hrLC₅₀ values, indicating a potential for mortalities in power plant discharges. This mortality has not been observed in the field and alternate explanations are discussed. Present interim criteria for chlorinated discharges may not adequately protect all warmwater fish. This study indicates that HOCl may greatly influence fish behavior and suggests that HOCl criteria be adopted for use in conjunction with current total residual chlorine criteria. / Master of Science

The applicability to composite materials of a particular NDI technique, vibrothermography, is studied. With this technique, specimens are excited with a high power, low frequency ultrasonic shaker while the specimen is monitored with an infrared camera. Once temperature patterns are developed, thermograms are photographed from the color display of the infrared camera. A three dimensional, orthotropic, finite difference heat conduction analysis is performed and written into a computer coding. After an estimate of the heat sources responsible for an experimental thermogram is made, these heat sources along with the material information is fed into the computer coding to produce an analytical temperature pattern. A comparison between the experimental and analytical thermograms may lead to further information concerning the nature of the heat sources. The computer coding is written to handle an eight ply symmetric laminate using one hundred elements per ply in the analysis. A listing of the computer coding along with a guide to its use, a sample data set, and a sample output are included in the thesis. / Master of Science

The thesis project has two general objectives. The primary objective is to design a facility whose plan incorporates and reflects an understanding of architecture — a facility that is right for its purpose, its people and its surroundings. A secondary objective is to document the process methodology leading to the proposed design solution. The project building type is a community college facility to serve approximately 850 students within a planned building area of 85,000 square feet. The Virginia Department of Community College's activity and space requirements document, dated November 1968, set forth for construction of phase II of the existing Radford-Pulaski Community College has been incorporated as a program requirement for this thesis project. The project site is the site of the existing Radford-Pulaski Community College which is a one hundred acre tract of land located near the Southwestern Virginia town of Dublin, in Pulaski County a part of the New River Valley Planning District. The thesis paper traces the development of the proposed design solution through the various phases of the design process to the final presentation of the proposed facility. The paper externalizes criteria selected to generate and guide the design effort; documents objectives, motivations, convictions, intentions and design decisions; discusses process methodology employed and presents various diagrammatic drawings and physical study models generated along the design path. The paper ends without a lengthy narrative justification of the proposed design solution, but instead with a presentation of architectural drawings illustrating the proposed facility. / Master of Architecture

Comparison and convergence studies are conducted with two non- linear finite element beam-column models. Both models admit physical and geometric nonlinearities. The models differ in their respective strain field representations. Model 2 permits a linear longitudinal and transverse strain variation. The strain field of model 3 can vary linearly in the transverse direction and quadratically in the longitudinal direction. The system model and solution process used with both element models are identical. The system model is defined by an energy function. The equilibrium path of the system is determined at discrete load levels. At each load level, application of the solution process yields the new equilibrium configuration of the system. Four test problems are selected to determine the relative merits of models 2 and 3. The models are tested over the entire range of response. The tests indicate that both models predict accurate responses throughout the range of response. Mesh refinement is seen to increase the accuracy of the models' response predictions. The models achieve identical response predictions in the linearly elastic range. The inelastic response predictions of model 2 are seen to be more accurate than those of model 3. Model 2 is computationally more efficient than model 3 over the entire range of response. The results of the studies reveal that throughout the range of response, the efficiency of response of model 2 is greater than that of model 3. / Master of Science

Groundwater on the eastern coast of the State of Virginia exceeds the Environmental Protection Agency Maximum Contaminate Level (MCL) for fluoride. This thesis explores the use of alum and alum and lime for the reduction of fluoride to the MCL or lower. In order to reduce an initial fluoride concentration of 2.1 mg/l to 1.8 mg/l 125 mg/l alum was required, for reduction from 5.5 mg/l to 1.8 mg/l, 415 mg/l alum was needed, and for reduction from 8.0 mg/l to 1.8 mg/l, 670 mg/l alum was utilized. If the system pH was lowered below 6.0 the fluoride reduction was insufficient and thus lime was required to maintain the pH above 6.0. However, hardness increased with the lime dose and other methods of pH adjustment such as employing soda ash should be considered. Aluminum was detected in the unfiltered treated water, perhaps in sufficient concentrations to cause problems in the distribution system, but further testing of filtered samples is needed. Sulfates were low in the raw water, but buildup with the addition of alum. No tests were made for sulfates in the treated water. Tests of the sludge produced by the addition of alum and lime indicated high volumes, low solids and very poor dewatering characteristics. Polymers should be considered as a possible means to achieve better sludge dewatering. / Master of Science

"Architecture As A Three-Dimensional Language" is defined as a communication between architect and man manifested in form. It is useful to make an analogy between architecture and language since the purpose of both is to communicate. Communication requires the use of signs and symbols. In architecture form communicates meanings through signs and symbols. Some meanings communicated in architecture through signs and symbols demonstrate a sense of shelter, function, and movement. Function manifested in form anticipates the need for movement in the environment. Movement involves defining a direction. Direction can be established through the use of view and path as they relate to form. These elements create the approach, entrance, and circulation pattern of each building. As each individual building communicates movement by establishing a direction, the city also establishes a direction for movement in a universal way. Describing architecture as a language whose basic mode of communication is form suggests a design criteria based on how man perceives and responds to what the architect's design is trying to communicate. / Master of Architecture

The break-in behaviors of two similar heterogeneously catalyzed systems were studied during propylene disproportionation. A cobalt oxide-molybdena-alumina (CoO-MoO₃—Al₂O₃) catalyst was found to undergo a rapid increase in the catalytic activity during the first 100 seconds of contacting with the reactants and this was the order of magnitude of the mass transport delays. A slower first order process was observed with a break-in period of about 30 minutes, and this process is reversed by inert purge. The effects of the products of propylene disproportionation on the activity of a tungsten oxide on silica (WO₃-SiO₂) catalyst were studied by using a split-bed reactor and using mixtures containing low concentrations of products in propylene as feed. In both experiments the products were found to have some suppressing effects on the activity of this catalyst. The activity of the WO₃-SiO₂ catalyst was reduced to one tenth of the original by adding 0.02N NaOH aqueous solution to the catalyst and drying at 120°C for twelve hours. Dosing hydrogen (a reductant) and oxygen (an oxidant) to the fully activated WO₃-SiO₂ catalyst individually or alternatively reduced the activity of this catalyst to a point where another break-in period was needed to restore full activity. The break-in period of cooling and reheating the steady-state WO₃-SiO₂ catalyst in stagnant propylene was much shorter than that observed in propylene flow. / Master of Science

One of the major problems in image processing is information reduction. The research reported in this thesis examines the semantics of cortext-independent edges in a real-world environment. Topics discussed include a classification scheme for edges, edge semantics, and a method for minimizing noise effects in edge computations. / Master of Science

The criteria for design and construction of a single family dwelling in a tropical oceanside environment will be investigated. Tropical vernacular architecture will be studied. Concepts established will be integrated in a modern architectural language, preserving the time tested truths of the local architecture. The position of tropical vernacular architecture and contraposition of modern architecture will then be synthesized into a single family tropical dwelling based on established criteria. / Master of Architecture