Wind energy has become one of the most important and thriving renewable energy resources in the world. Transforming the kinetic energy of wind into electric power is more environmentally friendly than traditional processes such as the combustion of fossil fuels. It provides independence from the limited fossil fuels reserves by using an unlimited resource. In order to develop a wind power facility, it is important to develop an initial wind resource assessment to guarantee the selected site will be profitable in terms of electric energy output. Several countries lack developed wind atlases that indicate a rough estimate of wind resource in their territories, which is an obstacle for inexpensive wind resource evaluations. In order to perform site evaluations generally an anemometer must be put in place to take wind measurements. This process is costly and time consuming since at least a year of data must be observed. The quality of wind resource depends on several geographic and atmospheric characteristics such as: air density, site location, site topography, wind speed and direction. This study was conducted to provide an initial wind resource assessment on three locations in Venezuela which do not have previous evaluations: Cerro Copey, Punta de Piedras and Los Roques. The assessment was done remotely based on the national meteorological service meteorological observations; wind resource and turbine power output uncertainties were taken into account. The wind assessment was done through Monte Carlo simulations mathematically considering several uncertainties with emphasis on surface roughness for vertical extrapolation. The results exhibit wind energy potential of the three sites and a throughout wind resource characterization of the site with the most potential: Cerro Copey. / A Thesis submitted to the Department of Civil and Environmental Engineering in partial fulfillment of the Master of Science. / Spring Semester 2016. / April 8, 2016. / Assessment, Energy, Venezuela, Wind / Includes bibliographical references. / Sungmoon Jung, Professor Directing Thesis; Eren Erman Ozguven, Committee Member; Kamal Tawfiq, Committee Member; Raphael Kampmann, Committee Member.

Renewable energy sources are fundamental alternatives to supply the rising energy demand in the world and to reduce or replace fossil fuel technologies. In order to make renewable-based technologies suitable for commercial and industrial applications, two main challenges need to be solved: the design and manufacture of highly efficient devices and reliable systems to operate under intermittent energy supply conditions. In particular, power generation technologies based on solar energy are one of the most promising alternatives to supply the world energy demand and reduce the dependence on fossil fuel technologies. In this dissertation, the dynamic behavior of a Concentrated Solar Power (CSP) supercritical CO2 cycle is studied under different seasonal conditions. The system analyzed is composed of a central receiver, hot and cold thermal energy storage units, a heat exchanger, a recuperator, and multi-stage compression-expansion subsystems with intercoolers and reheaters between compressors and turbines respectively. The effects of operating and design parameters on the system performance are analyzed. Some of these parameters are the mass flow rate, intermediate pressures, number of compression-expansion stages, heat exchangers' effectiveness, multi-tank thermal energy storage, overall heat transfer coefficient between the solar receiver and the environment and the effective area of the recuperator. Energy and exergy models for each component of the system are developed to optimize operating parameters in order to lead to maximum efficiency. From the exergy analysis, the components with high contribution to exergy destruction were identified. These components, which represent an important potential of improvement, are the recuperator, the hot thermal energy storage tank and the solar receiver. Two complementary alternatives to improve the efficiency of concentrated solar thermal systems are proposed in this dissertation: the optimization of the system's operating parameters and optimization of less efficient components. The parametric optimization is developed for a 1MW reference CSP system with CO2 as the working fluid. The component optimization, focused on the less efficient components, comprises some design modifications to the traditional component configuration for the recuperator, the hot thermal energy storage tank and the solar receiver. The proposed optimization alternatives include the heat exchanger's effectiveness enhancement by optimizing fins shapes, multi-tank thermal energy storage configurations for the hot thermal energy storage tank and the incorporation of a transparent insulation material into the solar receiver. Some of the optimizations are conducted in a generalized way, using dimensionless models to be applicable no only to the CSP but also to other thermal systems. This project is therefore an effort to improve the efficiency of power generation systems based on solar energy in order to make them competitive with conventional fossil fuel power generation devices. The results show that the parametric optimization leads the system to an efficiency of about 21% and a maximum power output close to 1.5 MW. The process efficiencies obtained in this work, of more than 21%, are relatively good for a solar-thermal conversion system and are also comparable with efficiencies of conversion of high performance PV panels. The thermal energy storage allows the system to operate for several hours after sunset. This operating time is approximately increased from 220 to 480 minutes after optimization. The hot and cold thermal energy storage also lessens the temperature fluctuations by providing smooth changes of temperatures at the turbines' and compressors' inlets. Additional improvements in the overall system efficiency are possible by optimizing the less efficient components. In particular, the fin's effectiveness can be improved in more than 5% after its shape is optimized, increments in the efficiency of the thermal energy storage of about 5.7% are possible when the mass is divided into four tanks, and solar receiver efficiencies up to 70% can be maintained for high operating temperatures (~ 1200°C) when a transparent insulation material is incorporated to the receiver. The results obtained in this dissertation indicate that concentrated solar systems using supercritical CO2 could be a viable alternative to satisfying energy needs in desert areas with scarce water and fossil fuel resources. / A Dissertation submitted to the Department of Mechanical Engineering in partial fulfillment of the requirements for the degree of Doctor of Philosophy. / Spring Semester 2016. / February 26, 2016. / Concentrated Solar Power (CSP), Efficiency, Optimization, Supercritical CO2 (sCO2), Thermodynamic Analysis / Includes bibliographical references. / Juan C. Ordonez, Professor Co-Directing Dissertation; Alejandro Rivera-Alvarez, Professor Co-Directing Dissertation; Hui Li, University Representative; Kunihiko Taira, Committee Member; Carl Moore, Committee Member; Rob Hovsapian, Committee Member.

Solar photovoltaic (PV) energy integration in distribution networks is one of the fastest growing sectors of distributed energy integration. The growth in solar PV integration is incentivized by various clean power policies, global interest in solar energy, and reduction in manufacturing and installation costs of solar energy systems. The increase in solar PV integration has raised a number of concerns regarding the potential impacts that might arise as a result of high PV penetration. Some impacts have already been recorded in networks with high PV penetration such as in China, Germany, and USA (Hawaii and California). Therefore, network planning is becoming more intricate as new technologies are integrated into the existing electric grid. The integrated new technologies pose certain compatibility concerns regarding the existing electric grid infrastructure. Therefore, PV integration impact studies are becoming more essential in order to have a better understanding of how to advance the solar PV integration efforts without introducing adverse impacts into the network. PV impact studies are important for understanding the nature of the new introduced phenomena. Understanding the nature of the potential impacts is a key factor for mitigating and accommodating for said impacts. Traditionally, electric power utilities relied on phasor-based power flow simulations for planning their electric networks. However, the conventional, commercially available, phasor-based simulation tools do not provide proper visibility across a wide spectrum of electric phenomena. Moreover, different types of simulation approaches are suitable for specific types of studies. For instance, power flow software cannot be used for studying time varying phenomena. At the same time, it is not practical to use electromagnetic transient (EMT) tools to perform power flow solutions. Therefore, some electric phenomena caused by the variability of PV generation are not visible using the conventional utility simulation software. On the other hand, EMT simulation tools provide high accuracy and visibility over a wide bandwidth of frequencies at the expense of larger processing and memory requirements, limited network size, and long simulation time. Therefore, there is a gap in simulation tools and techniques that can efficiently and effectively identify potential PV impact. New planning simulation tools are needed in order to accommodate for the simulation requirements of new integrated technologies in the electric grid. The dissertation at hand starts by identifying some of the potential impacts that are caused by high PV penetration. A phasor-based quasi-static time series (QSTS) analysis tool is developed in order to study the slow dynamics that are caused by the variations in the PV generation that lead to voltage fluctuations. Moreover, some EMT simulations are performed in order to study the impacts of PV systems on the electric network harmonic levels. These studies provide insights into the type and duration of certain impacts, as well as the conditions that may lead to adverse phenomena. In addition these studies present an idea about the type of simulation tools that are sufficient for each type of study. After identifying some of the potential impacts, certain planning tools and techniques are proposed. The potential PV impacts may cause certain utilities to refrain from integrating PV systems into their networks. However, each electric network has a certain limit beyond which the impacts become substantial and may adversely interfere with the system operation and the equipment along the feeder; this limit is referred to as the hosting limit (or hosting capacity). Therefore, it is important for utilities to identify the PV hosting limit on a specific electric network in order to safely and confidently integrate the maximum possible PV systems. In the following dissertation, two approaches have been proposed for identifying the hosing limit: 1. Analytical approach: this is a theoretical mathematical approach that demonstrated the understanding of the fundamentals of electric power system operation. It provides an easy way to estimate the maximum amount of PV power that can be injected at each node in the network. This approach has been tested and validated. 2. Stochastic simulation software approach: this approach provides a comprehensive simulation software that can be used in order to identify the PV hosting limit. The software performs a large number of stochastic simulation while varying the PV system size and location. The collected data is then analyzed for violations in the voltage levels, voltage fluctuations and reverse power flow. It is important to note that there are multiple factors that affect the hosting limits in a distribution network. Moreover, the limit can be assessed based on different parameters; however, it will be shown in this dissertation that in most cases the voltage level is the first parameter to be violated under high PV penetration conditions. Therefore, in both approaches, the voltage is considered the main factor to be monitored for violations for PV hosting limit identification. The work presented hereinafter focuses on providing novel, innovative and practical solutions for fulfilling certain gaps in power system simulation. A novel hybrid simulation tool is presented in this dissertation as a solution for some of the issues facing the simulation of distribution networks with high PV penetration. Hybrid simulation is a relatively new concept in power system simulation and has not yet been applied for studying PV impacts in distribution networks. The presented hybrid tool offers accurate results and fast simulations. It can be used for various applications regarding the study of PV impacts as will be shown in this dissertation. It interfaces an EMT model of a grid-tied PV system with a phasor-domain model of a distribution network. The presented hybrid simulation tool incorporates a phasor-domain QSTS simulation with a time-domain EMT simulation which allows for a wide range of frequency visibility. The tool offers full EMT-level visibility at the point of common coupling (PCC), as well as slow dynamic visibility through the QSTS simulation. The tool is validated and tested by comparing the results with a full EMT simulation. It is used for studying the impacts of PV systems on the distribution network during fault conditions, islanding situation, solar irrandiance variation, among many other applications. The developed tool is made completely open-source in order to promote the hybrid simulation concept in power systems simulations as a viable solution for many of the conventional simulation tool limitations. Moreover, the work presented hereinafter proposes a novel co-simulation architecture with power hardware-in-the-loop (PHIL) simulation. The proposed architecture is the first of its kind developed at the National Renewable Energy Laboratory (NREL). The co-simulation testbed is developed in order to allow for wider range of hardware testing before deploying new technologies into the field. The testbed is composed of: 1. A full phasor model of the distribution network developed using a commercial distribution management software (DMS) environment. 2. A reduced form of the full network model developed in a real-time EMT environment using Opal-RT real-time simulator. 3. A hardware setup tested in a PHIL simulation environment. The hardware setup represents a grid-tied PV system at the PCC composed of a grid simulator, PV simulator, and a PV inverter. The co-simulation allows a slow QSTS simulation to be performed using the DMS model where slow variations are simulated, such as voltage regulator operations and slow variations in loads and solar irradiance. The QSTS simulation updates the EMT model components (loads, generators, voltage sources, and voltage regulators). The reduced EMT model is solved in real-time which allows for detailed and accurate visibility of the transient phenomena occurring in the network. Finally, the EMT model communicates with the physical hardware device at the PCC in order to close the PHIL loop. This architecture expands the capabilities of conventional PHIL testing and allows for more tests and scenarios to be implemented. The co-simulation testbed is tested by solving a real feeder network model in the DMS using historic load and solar irradiance data. The phasor model updates the EMT model's loads, voltage sources, and voltage regulator status at every QSTS time-step. The EMT model communicates through the hardware interface of the real-time simulator with the hardware setup by sending command control signals to the grid simulator and the PV simulator in order to replicate the simulated conditions in the real physical hardware. The inverter is tested under different operation modes, and its capabilities to use advanced algorithms for voltage regulation are put to test. The co-simulation architecture also addresses the stability and accuracy concerns of the PHIL experiments. A detailed stability and accuracy analysis is discussed in Chapter 6. / A Dissertation submitted to the Department of Electrical and Computer Engineering in partial fulfillment of the requirements for the degree of Doctor of Philosophy. / Spring Semester 2017. / April 7, 2017. / Distribution Network Planning, Hardware-in-the-Loop, Photovoltaic Systems, Power System Simulation, PV Impact Studies, Simulation Tool / Includes bibliographical references. / Juan Ordonez, University Representative; Simon Y. Foo, Committee Member; Chris S. Edrington, Committee Member.

Indiana University-Purdue University Indianapolis (IUPUI) / The imposition and promotion of democracy through military force is an idea that has been discussed throughout U.S. history since the end of World War II. Military interventions—coupled with nation building—serve as a pivotal point of discussion as the United States continues it efforts to establish democratic states in regions all across the world. This thesis examines three unique case studies post-WWII, arguing that democracy cannot, in fact, be forced. This argument arises from historical research as well as democratic evaluation tools such as Freedom House. Democracy must be tied to the culture and people of a given society in order to achieve substantive and enduring change; conducting an election is not sufficient to establish a truly democratic nation.

Complexity-modulated tasks elicit differential hemodynamic activations in the primary motor cortex for upper limb motor representations. However, much is yet to be learned regarding lower limb complexity modulation, as most fNIRS complexity modulation studies focus on the upper limb. It is currently unknown whether hemodynamic activations from single-joint lower limb motor tasks are detectable by fNIRS, and further, if fNIRS can detect differences between activations from simple and complex lower limb motor tasks. An fNIRS study was conducted to investigate the effects of an unpredictable, complex force-tracking task vs. a predictable, simple force-tracking task on hemodynamic activations in the TA motor representation. No significant TA motor cortex activations were found for 4/5 participants, with one participant showing a significant activation in one channel. Lack of activation in the TA motor representation was attributed to the depth of the area within the central sulcus. Significant hemodynamic activations were also found in areas assumed to overly STG/SII, and pre-SMA/SMA. These activations were attributed to sensory integration and motor learning, respectively. An fNIRS processing review was also conducted to inform processing decisions in the first experiment and to further fNIRS usage in our lab. Common techniques were identified as low-pass, band-pass, and high-pass filters, smoothing filters, wavelet filters, and the GLM. More appropriate alternative techniques were provided, including short-separation regression, pre-whitening, and spline interpolation with a Savitsky-Golay filter. Future studies may elucidate the lack of activity in the TA motor representation, and will further basic neuroscience regarding fNIRS. / Thesis / Master of Science in Kinesiology

Pulling behavior in canines remains a common problem despite the potential for serious injury. Unfortunately, data regarding the potential force a canine could exhibit while being walked in either a collar or harness is limited. Therefore, we designed a single-day study to investigate the impact of equipment type on canine potential pulling force. This study was approved by the Southern Illinois University Institutional Animal Use and Care Committee (21-005) prior to initiation of the work. For this crossover study, community and student-owned dogs (n=28) were recruited through email and social media advertisement. Upon arrival, dogs were weighed and grouped by size; small, medium, or large. Canines followed a standardized circuit that included different environmental stimuli (unfamiliar dog, food, thrown toy) commonly encountered during a walk in the park. Dogs were walked once in a fitted 1.5" flat nylon Tactipup© collar and a fitted padded Good2Go harness. An apparatus, EasyForce® digital dynamometer, was attached between the leash and a trained technician walking the canines. Variables of interest included: mean pulling force, peak pulling force, and time spent pulling. Data were analyzed using PROC GLM Two-way ANOVA (SAS Version 9.4) with significance set at P < 0.05. Although time spent pulling was similar (P = 0.3458) for both harness and collar, dogs pulled with greater mean force (P < 0.0001) while wearing a harness as compared to a collar (13.6 ± 0.88lbf and 8.5 ± 0.79lbf, respectively). Furthermore, peak pulling force was also greater in the harness (44.7 ± 1.22lbf) as compared to the collar (36.6 ± 1.21lbf) (P = 0.03). It is also important to note that when peak pulling force was expressed as a % of body weight (%BW), the smallest group exerted the most prominent force (122 ± 9.45%BW) when compared to the larger groups (P < 0.0001). This data compares the pulling force potential in canines while wearing either a collar or a harness and helps provide much-needed data to develop guidelines and better educational materials for dog owners related to leash-pulling behaviors. Future work should implement different types of collars and harnesses and look to see if the use of training has any effect on pulling behavior in canines.

Steady and unsteady force and moment experiments were conducted in the Virginia Tech Stability wind tunnel using the Dynamic Plunge-Pitch-Roll (DyPPiR) model mount to perform rapid time-dependent,high-excursion maneuvers. The experiments were performed for a DARPA2 submarine model using three widely spaced 2-force-component loadcells and three tri-axial accelerometers to extract the aerodynamic loads. The DARPA2 model was tested with different body configurations in two different test sections. The body configurations for both the steady and unsteady experiments were the bare body hull, body with sail, body with stern appendages, and body with sail and stern appendages. Tests were done using trips on the bow and sail and with no trips. The bare hull configuration with no trips was the only body configuration tested in the six-foot-square test section with solid walls. All body configurations were tested in the six-foot-square test section with slotted walls that were used to reduce the blockage effects produced by the DyPPiR and model. The steady experiments were performed over a range of angles of attack and roll positions. Data were acquired through the series of angles the body encountered during the unsteady testing (-26° < ± <+26° ). The data for the tripped bare hull gave symmetric results while the data acquired for the bare hull with no trips did not. In the unsteady experiments the model was pitched in ramp maneuvers about the 1/4 chord location of the sail from 0° to -25° and from +25° to 0° in 0.3 seconds. Sine wave maneuvers at 3 Hz were also performed, plunging the model up and down with an amplitude of ±0.375 inches. The steady data agreed within uncertainties with previous data that were limited to the David Taylor Research Center (DTRC). There was a higher level of confidence in the steady data taken with trips due to the symmetry of the data. Effects of the sail and/or stern appendages were studied using the steady and unsteady data, but no quantitative value could be calculated due to the uncertainties. The unsteady data were modeled with a quasi-steady time-lag model, and all the unsteady data were found to lead the quasi-steady data. The unsteady data did have oscillations, but the overall aerodynamic trend was still present. The uncertainties were too large to discuss effects of any appendages, however. / Master of Science

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