Anaerobic digestion is a process where biogas is generated from organic substance in the absence of oxygen. The most common application of the anaerobic digestion technology in developing countries is small-scale household digesters producing biogas for cooking purposes. These systems are usually fed with cattle dung or organic household waste. The typical small-scale digester models are fixed-dome digester, floating-drum digester and rubber-balloon digester. Biogas systems contribute to self-sustainability of energy production, improve waste management and mitigate deforestation and health problems caused by poor waste management and usage of traditional cooking fuels such as firewood and charcoal. Anaerobic digestion technology is still quite unknown in Mozambique. An initiative to implement this technology in the municipality of Quelimane located in Zambézia province in the central part of the country, was taken in 2015 and background studies were performed during spring 2015 and 2016. As a part of the study resulting in this report, performed in spring 2017, a small-scale biogas digester was installed in Quelimane city. The digester was fed with the initial input of cow manure in order to create population of anaerobic bacteria and in the future it’s planned to be fed with food waste. The purpose of the first installed digester is to serve for educational purposes and to produce cooking fuel for the few people working in the municipal location where the digester is installed. It’s estimated that the digester has a potential to produce daily 0.3 m3 of biogas from 2 kg of food waste which can be used for preparing lunch for the employees or for heating water. In the future, possible applications of anaerobic digestion technology in Quelimane are a municipal biogas plant, cooling systems for the fish industry and biogas based latrines in the less developed areas located outside of the city center.

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The biopharmaceutical industry has experienced remarkable progress in the upstream production capacity of life-saving proteins. This is while the downstream processing has failed to keep pace, including unit operations which are working close to their physical limit with no economy of scale. Column chromatography which is an integral unit in different stages of downstream purification is considered as the major bottleneck in this section. The packed-bed resin media is costly and the processes are labor-intensive and extremely time consuming. Membrane chromatography which uses a stack of adsorptive membranes as the chromatographic media is one of the most promising alternatives for conventional chromatography techniques. The performance of membrane adsorbers is consistent over a wide range of flow rates which is owing to the dominance of convective solute transport as opposed to the diffusion-based nature of mass transfer within the pores of the resin beads. This translates to much higher productivity and considerably lower buffer consumption (even as high as 95%), leading to much lower overall processing costs. The other advantages are significantly lower footprints and decreased pressure drops, both contributing to diminished capital costs. Membrane adsorbers are greatly scalable and used in a single-use manner. The latter eliminates the cleaning and validation steps and brings about much shorter processing times and higher flexibility in process development. Due to the performance advantages of membrane chromatography, this technique is now widely used in purification of high volumes of samples in late-stage polishing. Currently available membrane adsorbers have radial-flow spiral-wound configuration with high frontal surface area to bed height ratio according to which dilute impurities are removed in a flow-through format at very high flow rates and low pressure drops. Nevertheless, they fail to give high-resolution for bind-and-elute separations which makes them unsuitable for many unit operations, highly restricting their application. Severe design deficiencies such as large dead volumes and varying membrane area over the bed height result in broad and poorly resolved peaks. Herein, a novel device design was successfully developed which addresses the abovementioned shortcomings. The laterally-fed membrane chromatography (LFMC) devices house a stack of rectangular membrane sheets with two rectangular lateral channels on both sides of the stack as the feed and permeate channels. The design offers balanced pressure over the sides of the stack as well as even solute flow path lengths due to which the solute residence time is very uniform. Also, the small dead volumes minimize the dispersion effects. These features make the LFMC technology highly suitable for bind-and-elute applications, the improvement which is brought about by a simple design. The devices are easy to fabricate and highly scalable. The LFMC devices containing cation-exchange (CEX) membranes with 7 mL bed volume were examined for bind-and-elute separation where they outperformed the equivalent commercially available radial-flow devices. The design was further modified to give even lower dead volumes and more cost-effective fabrication. The latest embodiment of the device gave resolutions which were comparable with the ones obtained with the commercially packed resin columns in 1 mL and 5 mL scale with consistency over wide range of flow rates. The results were all acquired using a three component model protein system. Upon the approval of suitability of the device for bind-and-elute separation, the CEX-LFMC was used for purification of monoclonal antibodies (mAbs), the largest class of biopharmaceuticals. The device showed great performance in separation of mAb charge variants when extensively shallow gradients (60 membrane bed volumes) were required. The devices offered very stable conductivity gradients at high flow rates. LFMC devices in three different preparative scales gave great performance in separation of mAb aggregates which was approved for different mAb samples. The other application studied with the CEX-LFMC devices was the single-step preparative purification of mono-PEGylated proteins which is as well very challenging due to the physicochemical similarities between the target molecules and the impurities. Collectively, the LFMC devices combine the high-resolution with high-productivity which is highly desirable in downstream purification of biological molecules with great potential to expand the application of membrane chromatography. Finally, the LFMC devices were modified to adapt the analytical scale where they were integrated with a stack of hydrophilized PVDF membranes. The device successfully delivered ultra-fast separation of mAb aggregates in less than 1.5 minutes based on hydrophobic interaction membrane chromatography (HIMC). The assay times achieved with the HI-LFMC technique outclassed the currently available ultra-high performance chromatography (UPLC) methods at the same time with being extremely cost-effective. The application of the LFMC technology in analytical scale has great potential to offer cheap and rapid analysis in process development and quality control section of biopharmaceutical manufacturing. / Thesis / Doctor of Philosophy (PhD)

Indiana University-Purdue University Indianapolis (IUPUI) / In this research, a Split-Shaft Wind Energy Conversion System (SS-WECS) is investigated to improve the performance and cost of the system and reduce the wind power uncertainty influences on the power grid. This system utilizes a lightweight Hydraulic Transmission System (HTS) instead of the traditional gearbox and uses a Doubly-Fed Induction Generator (DFIG) instead of a synchronous generator. This type of wind turbine provides several benefits, including decoupling the shaft speed controls at the turbine and the generator. Hence, maintaining the generator’s frequency and seeking maximum power point can be accomplished independently. The frequency control relies on the mechanical torque adjustment on the hydraulic motor that is coupled with the generator. This research provides modeling of an SS-WECS to show its dependence on mechanical torque and a control technique to realize the mechanical torque adjustments utilizing a Doubly-Fed Induction Generator (DFIG). To this end, a vector control technique is employed, and the generator electrical torque is controlled to adjust the frequency while the wind turbine dynamics influence the system operation. The results demonstrate that the generator’s frequency is maintained under any wind speed experienced at the turbine. Next, to reduce the size of power converters required for controlling DFIG, this research introduces a control technique that allows achieving MPPT in a narrow window of generator speed in an SS-WECS. Consequently, the size of the power converters is reduced significantly. The proposed configuration is investigated by analytical calculations and simulations to demonstrate the reduced size of the converter and dynamic performance of the power generation. Furthermore, a new configuration is proposed to eliminate the Grid- Side Converter (GSC). This configuration employs only a reduced-size Rotor-Side Converter (RSC) in tandem with a supercapacitor. This is accomplished by employing the hydraulic transmission system (HTS) as a continuously variable and shaft decoupling transmission unit. In this configuration, the speed of the DFIG is controlled by the RSC to regulate the supercapacitor voltage without GSC. The proposed system is investigated and simulated in MATLAB Simulink at various wind speeds to validate the results. Next, to reduce the wind power uncertainty, this research introduces an SS-WECS where the system’s inertia is adjusted to store the energy. Accordingly, a flywheel is mechanically coupled with the rotor of the DFIG. Employing the HTS in such a configuration allows the turbine controller to track the point of maximum power (MPPT) while the generator controller can adjust the generator speed. As a result, the flywheel, which is directly connected to the shaft of the generator, can be charged and discharged by controlling the generator speed. In this process, the flywheel energy can be used to modify the electric power generation of the generator on-demand. This improves the quality of injected power to the grid. Furthermore, the structure of the flywheel energy storage is simplified by removing its dedicated motor/generator and the power electronics driver. Two separate supervisory controllers are developed using fuzzy logic regulators to generate a real-time output power reference. Furthermore, small-signal models are developed to analyze and improve the MPPT controller. Extensive simulation results demonstrate the feasibility of such a system and its improved quality of power generation. Next, an integrated Hybrid Energy Storage System (HESS) is developed to support the new DFIG excitation system in the SS-WECS. The goal is to improve the power quality while significantly reducing the generator excitation power rating and component counts. Therefore, the rotor excitation circuit is modified to add the storage to its DC link directly. In this configuration, the output power fluctuation is attenuated solely by utilizing the RSC, making it self-sufficient from the grid connection. The storage characteristics are identified based on several system design parameters, including the system inertia, inverter capacity, and energy storage capacity. The obtained power generation characteristics suggest an energy storage system as a mix of fast-acting types and a high energy capacity with moderate acting time. Then, a feedback controller is designed to maintain the charge in the storage within the required limits. Additionally, an adaptive model-predictive controller is developed to reduce power generation fluctuations. The proposed system is investigated and simulated in MATLAB Simulink at various wind speeds to validate the results and demonstrate the system’s dynamic performance. It is shown that the system’s inertia is critical to damping the high-frequency oscillations of the wind power fluctuations. Then, an optimization approach using the Response Surface Method (RSM) is conducted to minimize the annualized cost of the Hybrid Energy Storage System (HESS); consisting of a flywheel, supercapacitor, and battery. The goal is to smooth out the output power fluctuations by the optimal size of the HESS. Thus, a 1.5 MW hydraulic wind turbine is simulated, and the HESS is configured and optimized. The direct connection of the flywheel allows reaching a suitable level of smoothness at a reasonable cost. The proposed configuration is compared with the conventional storage, and the results demonstrate that the proposed integrated HESS can decrease the annualized storage cost by 71 %. Finally, this research investigates the effects of the reduced-size RSC on the Low Voltage Ride Through (LVRT) capabilities required from all wind turbines. One of the significant achievements of an SS-WECS is the reduced size excitation circuit. The grid side converter is eliminated, and the size of the rotor side converter (RSC) can be safely reduced to a fraction of a full-size excitation. Therefore, this low-power-rated converter operates at low voltage and handles the regular operation well. However, the fault conditions may expose conditions on the converter and push it to its limits. Therefore, four different protection circuits are employed, and their effects are investigated and compared to evaluate their performance. These four protection circuits include the active crowbar, active crowbar along a resistorinductor circuit (C-RL), series dynamic resistor (SDR), and new-bridge fault current limiter (NBFCL). The wind turbine controllers are also adapted to reduce the impact of the fault on the power electronic converters. One of the effective methods is to store the excess energy in the generator’s rotor. Finally, the proposed LVRT strategies are simulated in MATLAB Simulink to validate the results and demonstrate their effectiveness and functionality.

The primary objective of this dissertation is to determine Hispanic consumers’ preferences and willingness-to-pay (WTP) for grass-fed beef. Two hundred and thirty-one Hispanic consumers in four experiment sites in Virginia (Galax, Roanoke, Richmond, and Blacksburg) participated in an experimental economics laboratory procedure. Taste tests and visual evaluations were conducted to understand Hispanic consumers’ sensory preferences for grass-fed beef in comparison to conventional grain-fed beef. A contingent valuation method, Multiple Price Lists (MPL) was used to measure Hispanic consumers’ WTP for grass-fed beef. In the study, MPL was put into a non-hypothetical environment due to real products, real money, and actual transactions involved. A bivariate Probit model was estimated to determine Hispanic consumers’ visual and taste preferences for grass-fed beef and to explore the relationship between their expected and experienced quality of grass-fed beef. A two-step decision process examined Hispanic consumers’ WTP and investigated the factors influencing their valuations on grass-fed beef. Approximately 50% of Hispanic consumers sampled preferred grass-fed to conventional grain-fed beef steak and the vast majority of grass-fed preferring consumers were willing to pay a price premium for it. Hispanic consumers were able to distinguish the appearance and taste between grass-fed and conventional grain-fed beef steaks. A positive correlation between visual and taste preferences for grass-fed beef was captured. / Ph. D.

Early Mortality Syndrome (EMS) is a widespread bacterial infection of shrimp, attributed to pathogenic Vibrio parahaemolyticus strains (VP-EMS). This disease threatens aquaculture production and global food security. A valuable and alternative approach to using antibiotics for pathogen control, is the practice of incorporating direct-fed microbes (DFM) or probiotics. In order to evaluate the hypothesis that probiotics (specific strains of Bacillus subtilis spores) are able to provide shrimp, Litopenaeus vannamei, protection to the EMS disease, a pathogen growth model, disease challenge model, and probiotic feed coating methodologies were developed and refined, allowing independent shrimp probiotic trials to be piloted. A single probiotic strain of Bacillus subtilis: O14VRQ and a blend of Bacillus subtilis strains: Plus10, were evaluated as feed additives or as water additions, for their efficacy. Accordingly, two independent trials were conducted in which shrimp were fed daily with a probiotic-coated feed for seven days, before a challenge with VP-EMS. Each trial consisted of a negative control (no VP-EMS exposure, no probiotic) and positive control (VP-EMS exposure, no probiotic), with five additional probiotic treatment groups, which were fed and exposed to VP-EMS in the same manner as the positive control. Shrimp were observed for clinical signs of disease after the initial exposure and were continuously exposed every 24 hours until 50% of the population remained in the positive control treatment. Both probiotics studied were shown to significantly (p < 0.05) improve shrimp survival. Overall the data presented in this work demonstrates that probiotic prophylaxis is reliant upon probiotic dose, regardless of application. / Master of Science in Life Sciences / Aquaculture is one of the fastest growing agricultural sectors in the world allowing it to greatly contribute to global food security. Seafood products are known for their excellent health benefits, providing good sources of protein, fatty acids, and vitamins. However, the animals raised in this industry, like in many facets of animal agriculture, are susceptible to disease. Diseases can be costly to treat and if no treatment exists, can be detrimental to farms, especially to highly valued species such as shrimp. Traditionally, many diseases have been treated with antibiotics, however this can promote the growth of antibiotic resistant bacteria, which is a public health concern especially when involving animals fit for human consumption. An alternative to this approach is administering probiotics or beneficial bacteria to these animals. When incorporated with feed or applied to water, these beneficial bacteria can prevent diseases and help promote the growth of healthy animals. Two novel probiotics were fed to shrimp, before exposing them to the bacteria, Vibrio parahaemolyticus, which causes Early Mortality Syndrome, and is responsible for annual shrimp losses of more than $1 billion USD. Signs of this disease and survival were observed to assess if this probiotic could provide protection against this bacterium. Results from these studies show that these probiotics were capable of offering protection to shrimp when they were fed or introduced into tank water in high concentrations. Such probiotic applications could have beneficial effects on intensive shrimp aquaculture and help prevent this disease.

The Range Limited Antenna (RLA) is a device, which accurately estimates the range of incoming signals and rejects those that arrive from outside a certain, pre-determined range. This task is accomplished by using two multi-element arrays and applying direction finding (DF) algorithms on each of them. Rectangular, single-layer, coax-fed patch antennas are used as array elements for the specific purpose of tracking cell phones operating in the PCS band inside a given building. It is vital to ensure that the patch antenna is designed in such a manner that it resonates at the desired frequency. This thesis introduces the Agilent High Frequency Structure Simulator (HFSS) as an effective tool for modeling electromagnetic structures. It presents a comprehensive and meticulous description of the process of modeling a rectangular coax-fed patch antenna in HFSS. Plots of S-parameter values are calculated and are compared with WIPL-D, which is another simulation software program, and with measurements performed at the George Washington University. Various important parameters of the HFSS simulation are varied and their effects are investigated to provide a deeper understanding of the program. / Master of Science