Synchrophasor Measurement Units (PMUs) are devices that can not only measure but also time stamp voltage, current, frequency, among others. PMUs take these synchronized measurements as fast as 60 times per second; compared with the traditional 2-4 second SCADA measurements, PMUs bring a much clear and real-time picture of what is happening in the power system. PMUs have been increasingly deployed across transmission power grids worldwide. In the USA this is primarily done by utilities through projects sponsored mainly by SIGS and Smart Grid grants. There are different applications that synchrophasors can provide, including off-line and real-time applications. However, due to budget constraints, technology development and characteristics specific to each system, not all applications are equally suitable and essential for all electric power systems. This thesis provides a method for PMU applications prioritization based on the analysis and results of wide area disturbance events. / Master of Science

The Egyptian Fractions of One problem (EFO), asks the following question: Given a positive integer n, how many ways can 1 be expressed as the sum of n non-increasing unit fractions? In this paper, we verify a result concerning the EFO problem for n=8, and show the computational complexity of the problem can be severely lessened by new theorems concerning the structure of solutions to the EFO problem. / Master of Science / Expressing numbers as fractions has been the subject of one’s education since antiquity. This paper shows how we can write the number 1 as the sum of uniquely behaved fractions called “unit fractions”, that is, fractions with 1 in the numerator and some natural counting number in the denominator. Counting the number of ways this can be done reveals certain properties about the prime numbers, and how they interact with each other, as well as pushes the boundaries of computing power.

VPT, Inc and the U.S. Dept. of Energy have sponsored the development of a high-speed 12 kW AC induction motor to drive automotive fuel cell air compressors. As one part of the development, thermal considerations and the cooling system are detailed in this paper. The motor and inverter are packaged in one unit with the heat sink in the middle. The heat sink is a cold chamber designed to absorb the maximum heat losses from the unit. Empirical data was used to validate the model of the cold chamber and finalize the design. A lumped capacitance finite-difference model was developed to simulate the entire motor inverter assembly. The individual components of the thermal model were tested and the data was used to calibrate and validate the thermal model. Using the model, the thermal overload conditions were investigated. The limiting factors are the stator copper winding temperatures, which can damage the plastic slot liners. The double current test was simulated and operating temperatures of the system remained within thermal limits for 4 minutes. As a conclusion from the model, the thermal resistances from the stator to the case or the heat sink need to be reduced. Integrating the motor casing and end plate to the heat sink, rather than building it in sections, would reduce the thermal contact resistances. Also the copper winding ends in the stator could be coated in material that would bond to the case, thus increasing heat transfer from the windings to the case. / Master of Science

Heterogeneity is increasing across all levels of computing, with the rise of accelerators such as GPUs, FPGAs, and other coprocessors into everything from cell phones to supercomputers. More quietly it is increasing with the rise of NUMA systems, hierarchical caching, OS noise, and a myriad of other factors. As heterogeneity becomes a fact of life, efficiently managing heterogeneous compute resources is becoming a critical, and ever more complex, task. The focus of this dissertation is to lay the foundation for an autonomic system for heterogeneous computing, employing runtime adaptation to improve performance portability and performance consistency while maintaining or increasing programmability. We investigate heterogeneity arising from a myriad of factors, grouped into the dimensions of locality and capability. This work has resulted in runtime schedulers capable of automatically detecting and mitigating heterogeneity in physically homogeneous systems through MPI and adaptive coscheduling for physically heterogeneous accelerator based systems as well as a synthesis of the two to address multiple levels of heterogeneity as a coherent whole. We also discuss our current work towards the next generation of fine-grained scheduling and synchronization across heterogeneous platforms in the design of a highly-scalable and portable concurrent queue for many-core systems. Each component addresses aspects of the urgent need for automated management of the extreme and ever expanding complexity introduced by heterogeneity. / Ph. D.

Hardy space scalar theory on the disk is now classical. Some extensions have been done, one of them is the approach done by Donald Sarason using Laurent series. We present the more complicated function theory, without the use of either power series or Laurent series, for finitely-connected planar domains. / Master of Science

Information, products and services can be requested and purchased via the Interactive Video Data Service (IVDS) system developed by The Center for Wireless Telecommunications, Virginia Tech. This system consists of three components - User control, Repeater unit and a Host program. The user requests a service using his/her television remote (User control). A transceiver (User control) located near the television set responds to user requests by extracting information hidden in the commercial's audio, and transmitting information to the repeater unit. The receiver unit decodes received messages and forwards them in capsules to the Host component. Thus the user requests are received by the host system. The repeater unit is a real-time operating system with its in-built hardware and software functions. Application specific software can be written using the existing software drivers and libraries (kernel) to decode and process messages. The Host program monitors and responds to received user messages. This thesis focuses on the repeater unit hardware setup and discusses the application software implementation developed to receive messages from the transceiver box and to retransmit the messages in a different format over the Internet. The software specifications included no incoming message loss, ability to statically hold 10000 user messages, time-stamp and location-stamp (using a GPS receiver) forwarded messages, scheduling messages for retransmission based on message priority, and retransmission using the point-to-point protocol (PPP) using a dial-up modem connection. In order to achieve better performance the existing software kernel was re-written in some sections. This thesis also discusses some of the system limitations from the repeater unit's perspective. / Master of Science

With the development of the power grid into an automated system, phasor measurement units and phasor data concentrators are essential for real time control of the system. PMUs are time synchronized throughout the power system and take sample measurements in very small windows of time. Phasor Data Concentrators accept PMU data and time align the data so that a snapshot of the power system can be viewed in real time. It is unfeasible to possess enough real PMUs to thoroughly test PDCs, thus a Real Time PMU Simulator is desired. It is possible to implement a UNIX based PMU simulator that can emulate the behavior of real PMUs, while also allowing the user to alter the Synchrophasor data to test the response of a PDC. GPS is used to synchronize a UNIX machine to UTC time to match that of a real PMU. In this way, the PMU simulator will accurately behave as a PMU. This PMU data can be sent to PDCs to test the response of the device. To test extremes of the PDC, alterations were made to the PMU software to send irregular data to a PDC. The results conclude that the open source iPDC software is capable of being used for latency testing, sending late data frames, as well as sending corrupted data. The PMU simulator proved to be successful in the area of PDC testing. The purpose of this thesis is to demonstrate how the iPDC software can be implemented to test PDC's. / Master of Science

A system with hysteresis is one that exhibits path dependent but rate independent memory. Hysteresis can be observed physically through the magnetization of a ferromagnetic material. In order to mathematically describe systems with hysteresis, we use the Preisach model. A discussion of the Preisach model is given as well as a method for computing the hysteretic transformation of an input variable. The focus of this paper is hysteresis in economics, namely, unemployment. We consider essential time series techniques for analyzing time series data, i.e. unit root testing for stationarity. However, we point out problems in modeling hysteresis with these techniques and argue that unit root tests cannot capture the selective memory of a system with hysteresis. For that, hysteresis in economic time series data is modeled using the Preisach model. We test the explanatory power of the previous unemployment rate on the current unemployment rate using both a hysteretic and non-hysteretic model. We find that the non-hysteretic model is better at explaining current unemployment rates, which suggests hysteresis is not present in the United States unemployment rate. / Master of Science

Background: Getting admitted to CCU is viewed as a stressful event by patients. However, numerous studies have indicated that nurses do not always accurately perceive the stressors of their clients. Therefore, it is important for nurses to know what seems most stressful from the patients‘ perspective so that appropriate nursing measures can be directed towards minimizing such stressors. Objectives: The purpose of this study was to explore the perception of CCU stressors experienced by patients from both patients and nurses perspective and to compare between them, identify the effect of socio-demographic characteristics of participant's on the level of stress perception and to what extent clinical guidelines fulfil CCU needs. Methodology: A mixed method approach (qualitative and quantitative) was applied. Purposive random sampling was used to recruit data. Ethical approval was obtained prior to data collection. Data was collected from three CCUs within the West and Northwest NHS Trusts. Participants who met the inclusion criteria were interviewed and asked to rank the Environmental Stressor Questionnaire (ESQ). Qualitative data was analyzed using Gorgi's method of analysis. A quantitative data was analyzed using the SPSS software version 15. Results: There was some consistency in the data where patients and nurses provided same ranking for CCU stressors. Consistently nurses ranked physiological stressors higher than psychological stressors. Patients showed consistency in the findings between what they ranked in the ESQ and their narratives more than their counterparts. Perception of stress was affected by participant's socio-demographic characteristics. A key finding is that the current guidelines do not serve patients and nurses needs. Conclusions: Nurses should be well equipped with knowledge and experience to overcome stressful situations. Educational programs should be made available for nurses to improve stress management. Nurses should assess patient's needs by applying effectively communication skills.

Output power of hydro power plant was modelled and an optimization algorithm was implemented in a tool for optimizing hydro power plants. The tool maximizes power output of a hydro power plant by distributing water over a set of active units in the power plant which will be used in planning of electricity production. This tool was built in a MATLAB environment, using the optimization toolbox, and a GUI was developed for Vattenfall. The optimization tool was based on the same architecture as the current tool used for this kind of optimization which is to be replaced by the work presented in this thesis. Therefore, the goal was to achieve the same optimal results as the current optimization tool. Power output of three of Vattenfall’s hydro power plants were computed and two of these plants were optimized. These power output results were compared to results from the optimization tool currently used. This showed differences within the inaccuracy of measurements of ≤ 0.3%. These three power plants proved that the new tool is sufficient to replace the current tool but further testing is recommended to be conducted on more of Vattenfall’s hydro power plants to prove its consistency.