Mufflers and silencers are commonly used to attenuate noise sources such as internal combustion engines and HVAC systems. Typically, these environments contain mean flow that can affect the acoustic properties of the muffler components and may produce flow generated noise. To characterize the muffler performance, common metrics such as insertion and transmission loss and noise reduction are used in industry. Though transmission loss without flow is often measured and is a relatively simple bench top experiment and useful for model validation purposes, mean flow can significantly affect the muffler performance. There are a few existing and commercial transmission loss rigs that incorporate flow into the measurement procedure. These rigs are useful for model verification including flow but do not predict how the muffler will perform in the system since the source, termination, and pipe lengths significantly impact performance. In this research, the development of an insertion loss test rig is detailed. This testing strategy has the advantage of being simpler, quantifying the self-generated noise due to flow, and taking into account the effect of tailpipe length and a realistic termination. However, the test does not include the actual source and is not as useful for model validation. An electric blower produces the flow and a silencer quiets the flow. Loudspeakers are positioned just downstream of the flow silencer and they are used as the sound source. The low frequency source is a subwoofer installed in a cylindrical enclosure that includes a conical transition from speaker to pipe. Special care is taken to reduce any flow generated noise. Qualification of the system is detailed by comparing the measured transmission loss, noise reduction, and insertion loss to one-dimensional plane wave models. The results demonstrate that the developed rig should be useful as a muffler evaluation tool after a prototype has been constructed. The rig can also be used for transmission loss and noise reduction determination which will prove beneficial for laboratory testing.

The US Department of Energy in 2010 has identified several rare earth elements as critical materials to enable clean technologies. As part of ongoing research in REEs (rare earth elements) recovery from coal sources, the University of Kentucky has designed, developed and is demonstrating a ¼ ton/hour pilot-scale processing plant to produce high-grade REEs from coal sources. Due to the need to control critical variables (e.g. pH, tank level, etc.), process control is required. To ensure adequate process control, a study was conducted on leaching and solvent extraction control to evaluate the potential of achieving low-cost REE recovery in addition to developing a process control PLC system. The overall operational design and utilization of Six Sigma methodologies is discussed. Further, the application of the controls design, both procedural and electronic for the control of process variables such as pH is discussed. Variations in output parameters were quantified as a function of time. Data trends show that the mean process variable was maintained within prescribed limits. Future work for the utilization of data analysis and integration for data-based decision-making will be discussed.

The goal of this thesis is to use the Cal Poly Spacecraft Attitude Dynamics Simulator to provide proof of concept of two adaptive control theories developed by former Cal Poly students: Nonlinear Direct Model Reference Adaptive Control and Adaptive Output Feedback Control. The Spacecraft Attitude Dynamics Simulator is a student-built air bearing spacecraft simulator controlled by four reaction wheels in a pyramidal arrangement. Tests were performed to determine the effectiveness of the two adaptive control theories under nominal operating conditions, a “plug-and-play” spacecraft scenario, and under simulated actuator damage. Proof of concept of the adaptive control theories applied to attitude control of a spacecraft is provided. The adaptive control theories are shown to attain similar or improved performance over a Full State Feedback controller. However, the measurement capabilities of the simulator need to be improved before strong comparisons between the adaptive controllers and Full State Feedback can be achieved.

Increased government funding and incentives in recent years has led to an increase in the number of grid-tied renewable energy sources as their economic benefits become more renowned. Unfortunately, the outputs of these renewable resources are often highly variable, resulting in undesirable voltage disruptions that are harmful to sensitive loads. In addition to the energy variability of renewable energy sources, random voltage sags, swells and disruptions are already a major issue in power systems. Recent advances in power electronic devices have provided a platform for new solutions to the voltage support problem in power systems. One promising solution is the Dynamic Voltage Regulator (DVR), a series compensating device used to protect a sensitive load that is connected downstream from voltage sag or swell. For this thesis, the design, modeling, and analysis of a DVR system were performed using PSCAD software. Results from simulation demonstrate the DVR’s effectiveness in protecting a sensitive load from load and source side voltage disturbances as well as regulate the load bus voltage to its rated value.

Single stage cycloconverters generally incorporate hard switching at turn on and soft switching at turn off. This hard switching at turn on combined with the slow switching speeds of thyristors (the switch of choice for standard cycloconverters) limits their use to lower frequency applications. This thesis explores the analysis and design of a pulse density modulated (PDM), soft switching cycloconverter. Unlike standard cycloconverters, the controller in this converter does not adjust thyristor firing angles. It lets only complete half cycles of the input waveform through to the output. This allows and requires a much greater frequency step down from the input to the output. The advantages, shortcomings and tradeoffs of this topology are explored as this converter is designed, built and tested. The resulting cycloconverter has many deficiencies, but proves the concept of the PDM soft switching technique. Cases for further improvement and study are outlined. In the end, this converter shows much promise for applications requiring a high step down in frequency, as well as where the lower electromagnetic interference (EMI) of soft switching may be beneficial.

On average, a small business could lose $150,000 a year due to employee fraud schemes. For most of the small businesses affected by employee fraud schemes, the average $150,000 loss could be detrimental to the small business, causing the business to close. The purpose of this multiple case study was to explore the internal controls small business owners apply to detect and prevent fraud from occurring in the business. The population for the study consisted of 3 small business owners located in Hartsville, South Carolina who implemented effective internal fraud controls in their business. The conceptual framework guiding the study was the fraud triangle theory. Data were collected and triangulated through semistructured interviews, company internal control policy and procedure documents, the Committee of Sponsoring Organizations of the Treadway Commission internal control framework, and the Small Business Administration internal control good practices. Data were analyzed through coding. There were 3 themes which emerged in relation to addressing the central research question: cash collection, separation of duties, and attentiveness and awareness. The findings could contribute to positive social change by providing best practices for small business owners to mitigate the components of the fraud triangle and subsequently decrease, if not eliminate, fraud from occurring in small businesses.

<p>When searching for better and more practical interfaces between users and their computers, additional or alternative modes of communication between the two parties would be of great use. This thesis handles the possibilities of using eye and head movements as well as voice input as these alternative modes of communication. </p><p>One part of this project is devoted to find possible interaction techniques when navigating in a computer interface with movements of the eye or the head. The result of this part is four different controls of an interface, adapted to suit this kind of navigation, combined together in a demo application. </p><p>Another part of the project is devoted to the development of an application, with voice control as primary input method. The application developed is a simplified version of the application ActiViewer., developed by AerotechTelub Information&Media AB.</p>

<p>The aim with this master thesis is to analyze a scientific material concerning the context between learning and child/student development, and factors which controls process of learning, to create an image with quality account and teaching in mathematics, which then can raise the mathematical knowledge among students.</p><p>The phenomena which stand in focus for the investigation is: <em>why there is a negative tendency for development of knowledge in mathematics, among the Swedish students that TIMSSs investigations showed </em>in intercultural comparison within the years 1993, 1999, 2003 and 2007.</p><p>The method is the ethnographical method, which is based on: analyzing scientific theories about learning child/student development, factors which controls process of learning, and factors which controls process of learning the most and qualitative empiric investigation with qualitatively analyzes the questionnaires, which is about factors which are controlling the process of learning and factors which are controlling the process of learning the most.</p><p>Result of the theoretical and empiric analyzes shows that factors as school environment, attitude for subjects and teaching, controls and influence the learning. To end a unenthusiastic tendency as a negative development of mathematical knowledge among students that is shown in TIMSS investigation and to elevate the students' performance in mathematics, an elevated qualitative account and teaching in mathematics, by the factors named. Safe school environments as the intercultural meeting place, the teachers influence part to the students' subjects' attitude in mathematics and goal related grading criteria in teaching, is all required for e qualitative teaching in mathematics.</p>

The aim with this master thesis is to analyze a scientific material concerning the context between learning and child/student development, and factors which controls process of learning, to create an image with quality account and teaching in mathematics, which then can raise the mathematical knowledge among students. The phenomena which stand in focus for the investigation is: why there is a negative tendency for development of knowledge in mathematics, among the Swedish students that TIMSSs investigations showed in intercultural comparison within the years 1993, 1999, 2003 and 2007. The method is the ethnographical method, which is based on: analyzing scientific theories about learning child/student development, factors which controls process of learning, and factors which controls process of learning the most and qualitative empiric investigation with qualitatively analyzes the questionnaires, which is about factors which are controlling the process of learning and factors which are controlling the process of learning the most. Result of the theoretical and empiric analyzes shows that factors as school environment, attitude for subjects and teaching, controls and influence the learning. To end a unenthusiastic tendency as a negative development of mathematical knowledge among students that is shown in TIMSS investigation and to elevate the students' performance in mathematics, an elevated qualitative account and teaching in mathematics, by the factors named. Safe school environments as the intercultural meeting place, the teachers influence part to the students' subjects' attitude in mathematics and goal related grading criteria in teaching, is all required for e qualitative teaching in mathematics.

There is a need for smaller and more economic transportation systems. Two-wheeled inverted-pendulum machines, such as the Segway, have been proposed to address this need. However, the Segway places the operator on top of a naturally unstable platform that is stabilized by means of a control system. The control stability of the Segway can be severely affected when minor disturbances or unanticipated conditions arise. In this thesis, a dynamic model of a Segway is developed and used in simulations of various conditions that can arise during normal use. The dynamic model of a general two-wheeled inverted pendulum and human rider is presented. Initial estimates of the parameters were calculated or obtained from other references. The results from numerous experiments are presented and used to develop a better understanding of the dynamics of the vehicle. The experimental data was then used to adjust the model parameters to match the dynamics of a real Segway Human Transporter. Finally, the model was used to simulate various failure conditions. The simulations provide a better understanding of how these conditions arise, and help identify which parameters play an important role in their outcome.