This report describes the speed characteristic and various methods of speed control of DC shunt (separately excited) motors, especially for application in electrical vehicles. The basic behavior of the DC motor is discussed, along with traditional and modern techniques of speed control. As an example, a speed controller for a shunt motor (built and tested by the author) is discussed. Two types of speed controllers for electric cars are discussed, and the performance results for an experimental electric car are presented. Finally, a design for a 24 HP car motor controller using both armature and field control was simulated on a smaller scale in the laboratory.

No description available.

Yes / In this paper, we draw on the Bakhtinian concept of chronotope to make the theoretical argument that the turn to embodiment can be supplemented through a consideration of connotation in discursive psychology. We use Billig’s conception of linguistic repression as a test-case as to how connotation can supplement discursive analysis, but using our own interview material to do so. From establishing the case that connotation, understood through the lens of chronotope, is potentially of vital interest to discursive psychology, we move to drawing out three implications for this for doing qualitative research differently. First of all, we suggest that researchers need to feel the chronotope of the interview to manage its connotations in vivo. Secondly, we draw attention to the role of the absent other in everyday speech and how this absent other can be analysed differently to a typical discourse analysis - as layering connotations into speech. Finally, we draw attention to the hermeneutic attitude of earnest irony when doing research as a further means of generating as well as managing connotations.

Ultraviolet-Assisted Direct Ink Write (UV-DIW) is a material extrusion additive manufacturing (AM) technology in which a viscous ink, often at room temperature, is selectively extruded through a translating nozzle to selectively deposit material. The extruded ink is solidified via UV irradiation (photocuring) and three-dimensional parts are created by repeating the process in a layer-by-layer fashion. UV-DIW is an attractive AM technology due to its ability to (1) extrude highly viscous inks (i.e. >10,000 Pa·s if ink exhibits shearthinning behavior) (2) the promise of leveraging the broad photopolymer material library and chemistries established for other AM technologies capable of processing photopolymers and (3) the promise of processing a wide range of inks, which enables the fabrication of metal, ceramic, polymer, bio-based, and multi-material parts. Currently, the technology faces a few shortcomings including (1) limited material selection for UV-DIW due to requirement for inks to be photocurable and limited mechanical properties of photocurable materials (2) lack of feature resolution and topological complexity of printed parts and (3) lack of material screening models providing robust definition of the material requirements (e.g., viscosity, cure time, strength) for successful UV-DIW printing. To address these shortcomings, the goal of this work is to gain a fundamental understanding of the rheological and reactive properties required for successful Ultraviolet-Assisted Direct Ink Write (UV-DIW). The first approach to answering the fundamental research question is establishing the existing rheology experiments used to characterize DIW inks and the relationships between rheology and printability. An in-depth literature review of the techniques and relationships was compiled to better understand ink requirements for successful printing (Chapter 2). This broad survey is not limited to only UV-DIW, but includes all variations of DIW. The first part of the review provides a summary of the rheological experiments that have been used to characterize a wide variety of DIW inks. The second part of this review focuses on the connections between rheology and printability. This survey helps identify the required rheological properties for successful printing that is then used throughout the rest of this work. Additionally, this review identifies shortcomings in current work and proposes areas for future work. From this exhaustive literature review, a systematic roadmap was developed that investigators can follow to quickly characterize the printability of new inks, independent of that ink's specific attributes (Chapter 3). The roadmap simplifies the trends identified in literature into a brief and intuitive guide to the rheology experiments relevant to DIW printing and the relationship between those experiment and printing results. The roadmap was demonstrated by evaluating the printability of two inks: (1) a silicone ink with both yield-stress and reactive curing behavior and (2) urethane acrylate inks with photocuring behavior. Experimental printing studies were used to support the conclusions on printability made in the roadmap. The second main approach focuses on the development of three novel UV-DIW inks to address the current limited material selection for UV-DIW and help better understand the rheological and reactive properties required for successful printing. For the three novel UVDIW inks, the iterative process of ink synthesis, analysis of ink rheology, and printability evaluation was detailed. Data from the development process contributed to gaining a fundamental understanding of how rheology and reactivity affect printability. The three inks each had novel rheological properties that impacted their printing behavior: (1) photocuring (2) yield-stress behavior + photocuring and (3) photocuring + thermal curing. Additionally, each ink had unique properties that expands material selection for UV-DIW including (1) an all-aromatic polyimide possessing a storage modulus above 1 GP a up to 400 °C (Chapter 4), (2) a styrene butadiene rubber (SBR) nanocomposite with elongation at break exceeding 300 % (Chapter 5), and (3) a dual-cure ink enabling the printing of inks containing over 60 vol% highly opaque solids (Chapter 6). The third approach details the development of two UV-DIW process models to better understand the process physics of the UV-DIW process and give insight to the properties of a successful ink. The first process model uses data from photorheology experiments to model how a photocurable ink spreads upon deposition from the nozzle, accounting for transient UV curing behavior (Chapter 7). This model allows for the rapid evaluation of an ink's behavior during the solidification sub-function of UV-DIW solely based on its rheology, without the time-consuming process of trial-and-error printing or complex computer simulations. The second process model combines modeling with a novel experimental method that uses a UV photorheometer to accurately characterize the relationship between cure depth and UV exposure for a wide range of photopolymers (Chapter 8). This model helps understand an inks photocuring behavior and ensure a sufficient cure depth is produced to adhere to the previous layer in UV-DIW printing. Lastly, two UV-DIW process modifications are introduced to address research gaps of printing high resolution features and limited material selection. A hybrid DIW + Vat Photopolymerization system is presented to improve the feature size and topographical complexities of parts, while still retaining UV-DIW's ability to print with very high viscosity photoresins (Chapter 9). A high temperature Heated-DIW system is presented to heat inks to over 300 °C and ultimately enable printing of poly(phenylene sulfide) aerogels (Chapter 10). In enabling the DIW of poly(phenylene sulfide) aerogels, the production of ultra-lightweight thermally insulating components for applications in harsh environments is enabled. With the use of additive manufacturing, hierarchical porosity on the macroscale is enabled in addition to the meso-scale porosity inherent to the aerogels. / Doctor of Philosophy / Direct Ink Write (DIW) is a type of three-dimensional (3D) printing that is used to automatically produce a range of 3D geometries. Specifically, the DIW process selectively extrudes a viscous ink, similar in consistency to peanut butter or toothpaste, through a small moving nozzle to create the features of each layer. This process is like using a frosting bag to decorate a cake with icing. Three-dimensional parts are created by repeating this process and depositing layer on top of layer. While seemingly a straightforward process, it remains relatively unclear what properties an ink needs to produce quality parts. To produce quality parts, the ink first needs to be extruded from the nozzle to form homogenous beads with a constant width and free from breaks. Second, the extruded ink needs to retain the shape that it was deposited in. If the ink spreads excessively, the as-deposited features will be lost and a part resembling a blob will be produced. Lastly, the ink deposited on the first layers needs to have enough strength to support the weight of the part. Otherwise, the part will collapse akin to the Leaning Tower of Pisa. To achieve all three steps and produce a quality part, a successful ink needs to be able to flow through the nozzle and then solidify upon deposition. This work focuses on a specific process called Ultraviolet-Assisted Direct Ink Write (UV-DIW) where materials that solidify when exposed to UV light, called photopolymers, are printed. Currently, the properties of the inks, especially how they cure when exposed to UV light, that produce successful printing remains unclear. This work focuses on understanding how the properties of the photopolymer inks affect the printing behavior of the ink. The ultimate goal of this work is to develop guidelines for the properties of successful inks which will help others develop the next generation of materials printed via UV-DIW. Specifically, experiments are used study how inks behave when they flow through the nozzle (rheology) and then solidify when exposed to UV light (reactivity). This behavior is then connected to the inks printing behavior (printability). In working to better understand the connection between rheology, reactivity, and printability multiple approaches were used. These approaches include the development of new materials for printing via UV-DIW, development of a modified UV-DIW printing process that reduces the size of the printed features, and development of models to predict how inks will behave during printing. The new plastic materials that were developed and successfully printed via UV-DIW have outstanding properties including remaining strong up to 400 °C, being extremely flexible, and a plastic containing a large fraction of a solid filler. With each new material, the formulation was varied to change the inks rheological and reactive properties until successful UV-DIW was enabled. Each new formulation introduced material capabilities not previously available to DIW 3D printing. Then, A modified UV-DIW process was developed that takes advantage of the reactivity of the photopolymers to enable the printing of high-resolution features and shapes not previously possible via DIW 3D printing. In this novel process, a projector is used to project patterned UV light at the material and selectively cure small portions of the deposited material, instead of curing all the deposited material. After printing, the uncured ink is washed away resulting in features much smaller than what can be produced when directly extruding them. Finally, the developed process models use the relatively simple rheology and reactivity experiments, to predict how an ink behaves during the UV-DIW process. Using the results of these experiments and the developed models, the inks behavior during the printing process is predicted. These models allow for the properties of new inks to be quickly measured and their printing behavior predicted. New ink formulations can be quickly screened, and optimal process parameters predicted. Overall, this work produces guidelines for the rheological and reactive properties required of a photopolymer ink to produce successful UV-DIW printing. Future researchers can use these guidelines to develop the next generation of materials printed via UV-DIW more easily.

A new method called the Direct Method is developed to solve for the propagating modes in waveguides via the finite-element method. The variational form of the Direct method is derived to ensure that an extremum is reached. The Direct method uses Maxwell's equations directly, both zero and first-order, scalar and vector bases that are used in the finite-element formulation. The direct solution method solves for both the magnetic and electric fields simultaneously. Comparisons are made with the traditionally used vector-Helmholtz equation set. The advantages and disadvantages of the newly developed method is described as well as several results displayed using the WR-90 waveguide and a circular waveguide as test waveguides. Results include a partially filled dielectric loaded rectangular waveguide. The effects of including the divergence of the fields in the functional as penalty terms on the quality of results obtained by the Direct method and the vector-Helmholtz method is explored. The quality of results is gauged on the accuracy of the computed modes as well as the elimination or a significant reduction in the number of 'spurious modes' that are often encountered in solutions to waveguide problems. It is shown that computational time for the solution and computer storage requirements exceed the typically used Helmholtz equation method but the results obtained can be more accurate. Future work may include developing a sparse eigenvalue solution method that could reduce the solution time and storage requirements significantly. The Direct method of solution in dynamics resulted after an initial search in magnetostatics for methods to solve for the magnetic field without using the magnetic-vector potential using finite-element methods. A variational derivation that includes the boundary conditions is developed for the magnetic-vector potential method. Several techniques that were used to attempt accurate solutions for the magnetostatic fields with multiple materials and without the use of the magnetic-vector potential are described. It was found that some of the newly developed general techniques for magnetostatics are only accurate when homogeneous media are present. A method using two curl equations is developed which is a Direct method in magnetostatics and reveals the interaction between the bases used. The transition from magnetostatics to dynamics is made and similar Direct methods are applied to the waveguide problem using different bases. / Ph. D.

In a grounded direct current system, motor faults may occur which will not be indicated by ordinary protective devices, but which will affect motor operation or create unsafe conditions. All such faults are manifested by the fact that the current in one lead supplying the motor will be greater than that in the other. This current differential can be made to operate a direct current differential relay. About the two supplying leads, when such a fault occurs, will exist a magnetomotive force. This mmf will set up a flux in the core and armature of a relay which forms a magnetic circuit about the supplying conductors. Since the armature of the relay is balanced on a knife edge, the force of attraction between core and armature which is caused by the flux passing from one to the other will move the armature, and in so doing close a pair of contacts. A model relay was built which operates on this principle. Testing demonstrated that it would operate on a differential of approximately one and one-half amperes and that the relay would release when the differential was reduced to approximately four-tenths amperes. The test also showed that these differentials did not vary when the total currents involved changed. These results indicate that a relay built with a slightly different design, (so as to overcome the shortcomings of test model, notably the insecure armature mounting, and so as to provide certain other features, such as control of the current differential for which the relay will operate), would be responsive to current differentials of less than one-half ampere. Such a relay would be a practical device and would be capable of performing, in conjunction with a second, conventional, relay and a circuit breaker, an important control function. / M.S.

Numerical models (GMS MODFLOW, SEAM3D, and SEAM3D Interface) were applied to simulate groundwater flow, petroleum hydrocarbon compound (PHC) transport and biodegradation, and the transport and biotransformation of chlorinated ethenes at Site FT-002 Plattsburgh Air Force Base (PAFB), NY. Site FT-002 was contaminated with waste jet fuel and chlorinated ethenes used as a fire source during fire fighting training. The results of groundwater analysis indicated that the aquifer exhibited aerobic, nitrate reducing, ferrogenic, sulfate reducing and methanogenic conditions due to the biodegradation of the PHCs. Additional groundwater analysis showed the biotransformation of TCE to DCE, VC, and ethene. A numerical model was developed to simulate and assess the extent to which reductive dechlorination and direct anaerobic oxidation were responsible for the biotransformation of the chlorinated ethenes. Reductive dechlorination accounted for the 100%, 98.3%, and 97.5% of the biotransformation of TCE, DCE, and VC respectively. Direct anaerobic oxidation accounted for 1.7% and 2.5% of the biotransformation of DCE and VC respectively. Though direct anaerobic oxidation only accounted for a small percentage of total biotransformation it was necessary to fully develop the biotransformation of the DCE and VC in the ferrogenic zone. This study focused on the mechanisms responsible for the biotransformation of chlorinated ethenes, specifically reductive dechlorination and direct anaerobic oxidation. By further defining the NAPL source and initial conditions it could be used as a tool to accurately predict the monitored natural attenuation (MNA) of the FT-002 contaminant plume. / Master of Science

A trade study is carried out for the design of electric propulsion based lunar robotic precursor missions. The focus is to understand the relationships between payload mass delivered, electric propulsion power, and trip time. The results are compared against a baseline system using chemical propulsion with LOX/H2. The major differences between the chemical propulsion based and electric propulsion based systems are presented in terms of the payload mass and trip time. It is shown that solar electric propulsion offers significant advantage over chemical propulsion in delivering non-time critical payloads to lunar orbit. / Master of Science

Two experiments were conducted to determine the effects of various alternatives to antibiotics in broilers grown on used litter on performance, intestinal lesion scores, body composition, and cecal volatile fatty acid (VFA) concentrations. The first experiment used a corn-soybean meal based basal diet to generate a negative control (NC) diet (without treatment), a Bacillus licheniformis probiotic containing diet (NC + 0.10% DFM1), and four diets that contained various concentrations of a Bacillus subtilis probiotic (NC + 0.05% DFM2, NC + 0.10% DFM2, NC + 0.20% DFM2, and NC + 0.40% DFM2). Experimental diets were fed to broilers over a 42-day period. Body weight gain (BWG) was depressed from d 0-28 and d 0-42 with supplementation of 0.10% DFM1 and 0.05% DFM2 compared to NC fed birds (P ≤ 0.05), with no differences among the remaining treatments and the NC fed birds (P > 0.05). Feed intake (FI) and mortality corrected feed efficiency (FEm) were not different over the 0-42 day period. No differences in oocyst shedding, lesion scores, body composition or cecal VFA production were observed (P > 0.05). Consistently low lesion scores were indicative of a mild coccidial challenge. The second experiment utilized a corn-soybean meal basal diet to generate experimental treatment diets. The basal diet without additional supplements was fed to two groups of control birds, one on clean pine shaving litter (PC) and a second on used litter (NC). Treatment groups were fed the same diet, supplemented with butyrate for the first 14 days (NC + But 0-14), botanicals from d 15-43 (NC + Bot 15-43), butyrate from d 0-14 and botanicals from d 15-43 (NC + But 1-14/Bot 15-43), and butyrate from d 0-43 (NC + But 1-43). Butyrate supplementation reduced BWG from d 0-14 (P ≤ 0.05), but there were no differences in BWG from 0-43 d (P > 0.05). Feed intake was reduced for the NC + But 0-14 group from d 0-43 in comparison to both PC and NC. Lesion scores in the jejunum were reduced with supplementation of butyrate alone, fed for either d 0-14 or d 0-43 (P ≤ 0.05) and is an indication of a mild coccidial infection due to the used litter. Although there were no significant differences among treatments, overall performance was above industry expectations, likely due to the mild fall weather. These two experiments indicate that there are numerous factors involved in the efficacy of antibiotic alternatives, at least partially explaining the inconsistent results observed in the published literature. / Master of Science / Recently, increased regulations and customer demand have restricted and reduced the use of antibiotics in the poultry industry. Historically, antibiotics were used in poultry feed at sub-therapeutic levels to improve performance and prevent the incidence of clinical and subclinical disease. Since the reduction of antibiotic use, many producers have experienced reduced performance resulting in reduced profits. The limited use of antibiotics can also present an animal welfare issue associated with increased sub-clinical and clinical disease. Many researchers are investigating alternative feed additives that will both improve performance and prevent disease, including probiotics, organic acids, and botanical products. Previous research has demonstrated the ability of these alternative to positively, if inconsistently, influence the performance and health of broiler chickens. Therefore, the objective of this thesis is to investigate the effects of two probiotic bacteria fed at various concentrations and the effects of butyric acid and botanicals, fed alone, or in combination, on the performance, intestinal lesion scores, body composition, and cecal volatile fatty acid concentrations of broiler chickens raised on used litter. In these experiments, the used litter is representative of a mild disease challenge that would likely be present in a commercial poultry setting. Overall, there were few differences with the treatment of broilers with probiotic bacteria, but the lowest inclusions slightly reduced body weight gain compared to the control fed broilers. Butyric acid supplementation reduced body weight gain over the first 14 days, but these differences were no longer observed over the 0 to 42 day period. Although performance was not improved, butyrate did result in reduced intestinal lesion scores from the middle section of the small intestine, indicating potential health benefits with butyrate treatment. Overall, the data presented in this thesis suggest that there are a variety of factors that can alter the effectiveness of these alternatives in broiler production and care should be used in selection of antibiotic replacement tools.

In 1990, creosote contamination was discovered at a railroad tie yard in Oneida, Tennessee. A phytoremediation system that included over 1,200 hybrid poplar trees was installed between 1997 and 1998 for hydraulic control of the groundwater and enhancement of the natural biodegradation processes in the subsurface. Since then, Virginia Polytechnic Institute and State University has monitored eight polycyclic aromatic hydrocarbons (PAHs) in the soil and groundwater. They have found that concentrations of smaller and more volatile PAHs have decreased over the years as the DNAPL contamination has become more enriched with the larger PAHs. This thesis focuses on the movement of naphthalene through the subsurface because it comprises the majority of the creosote and evidence for its remediation exists. Of the many mechanisms within the phytoremediation system that serve to remediate contaminated groundwater and soil, the most important are rhizosphere bioremediation and plant uptake. However, another mechanism, direct volatilization through the soil, was thought to have significant remediation capabilities at this site. Because naphthalene is a highly volatile PAH, it was hypothesized that naphthalene is volatilizing directly through the soil to the atmosphere and that the rate of volatilization may be enhanced by the presence of the phytoremediation system. The goals of this research are to measure the amount of naphthalene that volatilizes from the subsurface and determine the factors that significantly influence this direct volatilization. A flux chamber was designed and constructed to measure naphthalene fluxes from the soil. Factors that influence direct volatilization include the groundwater level, soil moisture, precipitation, pressure changes, temperature and humidity, the most important of which we found to be the groundwater level through its influence on naphthalene concentrations in the groundwater. We found that the presence of the trees significantly affects groundwater levels. As trees transpire and lower the groundwater table, concentrations in the uppermost portion of the groundwater increase, and under dry conditions, naphthalene fluxes from the soil are maximized. To complement the field measurements of direct volatilization, we also investigated rates of volatilization and biodegradation in the laboratory. Column experiments were conducted to determine the importance of direct volatilization on biodegradation in the vadose zone. We hypothesize that the combined mechanisms of contaminant transfer to the vadose zone, followed by rapid biodegradation, speeds up remediation in contrast to biodegradation that occurs only in the saturated zone under high groundwater conditions. Several columns using contaminated and uncontaminated soil from the site were constructed with a naphthalene source. Vertical naphthalene vapor concentration profiles were measured, and first-order biodegradation rates were determined. We found that biodegradation rates in the bacterially active columns were small initially, but that the biodegradation rates of the contaminated soil dramatically increased at day 60, while the biodegradation rates of the uncontaminated soil did not begin to increase until day 150. By the end of the experiment, both soil types had approximately the same biodegradation rate, signifying that soil that had previously been exposed to naphthalene degrades naphthalene more efficiently in the early stages than soil that has not been exposed, but that over time the non-exposed soil degrades naphthalene as efficiently as the pre-exposed soil. We determined that the combined mechanisms of diffusion and biodegradation in the unsaturated zone have significant remediation capabilities. Because long-term exposure risks are associated with inhaling indoor contaminant vapors, the Johnson and Ettinger vapor intrusion model was applied to the creosote-contaminated site, as outlined in Appendix C. This model takes into account soil, chemical, and building foundation characteristics to determine a dimensionless attenuation ratio, which is the ratio of contaminant vapor concentration in an enclosed space (i.e. basement) to the vapor concentration directly above the source. For a conservative case, the Johnson and Ettinger model without biodegradation was used. We found that if the land were developed, naphthalene vapor intrusion would not pose any health risks based on regulatory standards and levels at which health effects have been recorded. / Master of Science