Master of Science / Department of Architectural Engineering and Construction Science / Fred L. Hasler / On-site energy production is becoming increasingly prevalent in building systems design with a renewed public awareness of sustainability, decreased energy resources, and an increase in the requirements of local and federal energy codes. Systems such as photovoltaics and solar thermal collectors have been implemented in designs to meet these challenges. The emerging technology of hybrid photovoltaic thermal (PVT) offers the potential to combine these systems into one contained module. A hybrid PVT system can simultaneously produce thermal and electrical energy, maximizing the use of available surface area available for energy production. Hybrid PVT can be implemented using PVT air collectors, PVT liquid collectors, and ventilated PV facades. Hybrid PVT is gaining interest at the academic level and is being applied at the residential level. Several commercial hybrid PVT products are currently manufactured, but options are limited. This report will evaluate PV, solar thermal collector, and hybrid PVT technologies, discuss the various components required for these systems, and present advantages and disadvantages of these systems. For an example elementary school design, the report will compare monthly energy production of the various systems, evaluating their ability to supply the peak loads of an example building design. Estimated first costs and operating and maintenance costs will be evaluated. The report will also quantify the ideal balance of PV and solar thermal collectors for the example based on loads and simple payback. Conclusions will be made about the current state of hybrid PVT and what steps need to be taken for it to be effectively implemented in the commercial building market.

Doctor of Philosophy / Department of Secondary Education / Jacqueline D. Spears / Retention of women in the architectural engineering workforce is important to the diversity and future success of the profession. However, little research has been done on why women leave the engineering workforce, making it difficult for engineering employers to accommodate the needs of women employees as a means of increasing retention. This research study identifies the retention rate of women in architectural engineering and determines why women leave the profession. The study consisted of a written survey coupled with follow-up telephone interviews only with those who completed the survey and were no longer employed. A mailed survey was sent to all female graduates between the years 1990 and 2005 from a Midwest state university architectural engineering program. Individual telephone interviews were then conducted with these women who had identified themselves as no longer employed in a field related to architectural engineering. The study revealed a retention rate of 66%. It did not identify one single factor as the reason women leave the architectural engineering workforce but rather many factors that seem to contribute to or influence this decision. The primary factors that surfaced included work environment, family/work balance, and mentoring. These factors influencing retention are consistent with prior research on this topic in engineering and architecture. Four recommendations specifically promote retention in response to these findings: 1) offer alternate working arrangements to better accommodate family responsibilities, 2) develop mentoring programs to support female employees in their career progression, 3) develop programs to discuss issues that are specific to women in a male dominated workforce to help women be better equipped for obstacles they may encounter during their career progression, and 4) promote and assist women to re-enter the workforce, recognizing that some women will make the choice to take a break from their career.

Doctor of Philosophy / Department of Industrial & Manufacturing Systems Engineering / Zhijian Pei / Silicon is the primary semiconductor material used to fabricate integrated circuits (ICs). The quality of integrated circuits depends directly on the quality of silicon wafers. A series of processes are required to manufacture the high-quality silicon wafers. Chemical mechanical polishing is currently used to manufacture the silicon wafers as the final material removal process to meet the ever-increasing demand for flatter wafers and lower prices. A finite element analysis has been conducted to study the effects of influencing factors (including Young's modulus and Poisson's ratio of the polishing pad, thickness of the pad, and polishing pressure) on the wafer flatness. In addition, an experimental study was carried out on the effects of process variables (including wafer rotation speed, pad rotation speed, the temperature of the cooling wafer in polishing table, polishing pressure, and the slurry flow rate) on material removal rate (MRR) in polishing of silicon wafers. The results from this study show that the polishing pressure and the pad speed are the most significant factors affecting the MRR. The polishing pad is one of the most critical factors in planarizing the wafer surface. It transports the slurry and interacts with the wafer surface. When the number of polished wafers increases, the pad is glazed and degraded and hence the polishing quality is decreased. The pad properties are changed during the process. The measuring methods for the pad properties including pad thickness monitoring, elastic properties and hardness are reviewed. Elasticity of two types of pads are measured and compared. The poor flatness problems such as tapering, edge effect, concave or convex wafer shape were investigated. Finite element models were developed to illustrate the effects of polishing pad and carrier film properties on the stress and contact pressure distribution on the wafer surface. Moreover, the material removal unevenness is studied. A grinding-based manufacturing method has been investigated experimentally to demonstrate its potential to manufacture flat silicon wafers at a lower cost. It has been demonstrated that the site flatness on the ground wafers (except for a few sites at the wafer center) could meet the stringent specifications for future silicon wafers. One of the problems is the poor flatness at the wafer center: central dimples on ground wafers. A finite element model is developed to illustrate the generation mechanisms of central dimples. Then, effects of influencing factors (including Young's modulus and Poisson's ratio of the grinding wheel segment, dimensions of the wheel segment, grinding force, and chuck shape) on the central dimple sizes are studied. Pilot experimental results are presented to substantiate the predicted results from the finite element model. This provides practical guidance to eliminate or reduce central dimples on ground wafers. The study in this thesis is to understand the mechanism of CMP and grinding of silicon wafers. Improving the processes and the quality of silicon wafers are the final goals.

Master of Science / Department of Architectural Engineering and Construction Science / Charles L. Burton / Building Information Modeling (BIM) is a new way of approaching the design, construction, and management of a building. It is an innovative method that bridges the communication gap between the architects, engineers, and contractors. By definition Building Information Modeling is a model-based technology linked with a database of project information. BIM builds a virtual model of the building so that architects, engineers, and contractors can all access at anytime. With BIM, architects and engineers are able to efficiently generate and exchange information, create digital representations of all stages of the building process, and simulate real-world performance. By doing this, many errors are eliminated in the field which increases productivity and improves quality. This report defines what BIM actually is and discusses the benefits and challenges that are associated with this new method of design and construction. Specifically, this report will take an in depth look at how BIM affects MEP design.

Master of Science / Department of Architectural Engineering and Construction Science / Charles L. Burton / Ground source heat pump systems have been around for nearly 50 years. The efficiencies that can be achieved today are difficult to match with any other type of heating and air conditioning system. With the familiarity of the system, installed costs have become very reasonable, and in some cases have been the same or less expensive than other comparable systems. Given all this, the question remains – why aren't more of these systems being proposed and installed? This report will investigate some of the reasons why and what can be done to remedy them. Major issues include professional education, availability of research and design material, industry or governmental incentives, and education in our K-12 schools and universities. Certainly all participants in the design process, from the designer to the owner, play a part in this dilemma. Recommendations will be made that address key hurdles this industry faces regarding making ground source heat pumps the system of choice.

Master of Science / Department of Mechanical and Nuclear Engineering / Donald L. Fenton / Emergency cooling systems are applied to any application where the loss of cooling results in damage to the product, loss of data, or equipment failure. Facilities using chilled water for cooling that experience an electrical power outage, even a small one, would cause the chiller to shut down for 20 minutes or more. If emergency cooling is not available, temperatures would continue to increase to dangerous levels, potentially damaging the facility. Examples of facilities that could be protected by having emergency cooling systems are data centers, hospitals, banks, control rooms, laboratories, clean rooms, and emergency shelters among others. This project addresses the current lack of information and methods needed to correctly design emergency cooling systems. Three application uses were investigated for the possible benefits of having emergency cooling systems. The software TRNSYS was used to simulate five typical emergency cooling systems for each of the three applications. The characteristics and differences of the systems developed from the simulations were then analyzed and documented. The five systems simulated include a pressurized chilled water tank (parallel), atmospheric chilled water tank (parallel and series), low temperature chilled water tank (parallel), and ice storage tank (series). Simulations showed that low temperature chilled water tanks were less stratified than regular chilled water tanks by approximately 10%. Simulations also showed that the differences between atmospheric and pressurized tanks were negligible. Each tank discharged energy in the same manner and managed to replenish itself in the same amount of time. Examination of the different system configurations showed that tanks in series with the thermal load have issues with recharging due to its inability to isolate itself from the thermal load. It was also observed that while low temperature chilled water and ice storage tanks had the potential of reducing the storage tank volume, the amount of time ragged cooling will last is decreased by at least a factor of two. The examination of the five systems produced the desired design methodologies needed to address the lack of information on emergency cooling systems. With the reported information designers can effectively engineer systems to meet their needs.

Master of Science / Department of Architectural Engineering and Construction Science / Fred L. Hasler / The purpose of this report is to provide an introduction to the new ASHRAE Standard 189.1-2009, Standard for the Design of High-Performance Green Buildings. The report will include an overview of the standard to detail what the purpose, scope and requirements for high-performance buildings will be. The entire standard will be overviewed, but the focus of this paper is in the areas of energy efficiency and building performance. Next, the report will examine further impacts that the standard will have on the building design and construction industry. Chapter 3 includes the impact on other standards, specification writing and coordination of the design and construction teams. A case study of an office building is performed to compare a baseline building meeting ASHRAE Standard 90.1 to a building meeting the minimum standards of ASHRAE Standard 189.1. The case study compares the total annual energy use of the two projects to determine an expected energy savings. Based on this information, recommendations about the new standard will be discussed. Universities and government entities should require ASHRAE Standard 189.1 for new construction projects, to show willingness to provide sustainability in buildings. Finally, conclusions about how the standard will change and impact industry will be addressed. These conclusions will include issues with adopting ASHRAE Standard 189.1 as code as well as discussion on the LEED rating system.

Master of Science / Department of Industrial & Manufacturing Systems Engineering / Todd W. Easton / Integer programs (IP) are a commonly researched class of problems used by governments and businesses to improve decision making through optimal resource allocation and scheduling. However, integer programs require an exponential amount of effort to solve and in some instances a feasible solution is unknown even with the most powerful computers. There are several methods commonly used to reduce the solution time for IPs. One such approach is to generate new valid inequalities through lifting. Lifting strengthens a valid inequality by changing the coefficients of the variables in the inequality. Lifting can result in facet defining inequalities, which are the theoretically strongest inequalities. This thesis introduces the Cutting-plane Algorithm in Three Sets (CATS) that can help reduce the solution time of integer programs. CATS uses synchronized simultaneous lifting to generate a new class of previously undiscovered valid inequalities. These inequalities are based upon three sets of indices from a binary knapsack integer program, which is a commonly studied integer program. CATS requires quartic effort times the number of inequalities generated. Some theoretical results describe easily verifiable conditions under which CATS inequalities are facet defining. A small computational study shows CATS obtains about an 8.9% percent runtime improvement over a commercial IP software. CATS preprocessing time is fast and requires an average time of approximately .032 seconds to perform. With the exciting new class of inequalities produced relatively quickly compared to the solution time, CATS is advantageous and should be implemented to reduce solution time of many integer programs.

Master of Science / Department of Mechanical and Nuclear Engineering / Bruce R. Babin / A significant body of literature exists for experiments in spray cooling applications that utilize one-dimensional heat transfer through a metal ingot to determine the average surface heat flux. Due to inherent non-uniformities in spray distributions, measurements that account for the two-dimensional effects are required. In this study, an infrared (IR) camera was used to capture the two-dimensional temperature distribution formed when spraying an electrically heated NiChrome surface with three different fluids. IR thermography captured the thermal response of the un-sprayed side of a 0.005-inch (0.125mm) think strip of NiChrome exposed to spray from a 90° full-cone nozzle at low mass fluxes (0.025 – 0.045 lb/ft[superscript]2-s / 0.122 – 0.220 kg/m[superscript]2-s) from a distance of approximately 5 to 11 inches (13 to 28cm). Results were measured for surface average temperatures ranging from 150 to 600°F (65 – 315°C).

Master of Science / Department of Architectural Engineering and Construction Science / Fred Hasler / Data center space and power densities are increasing as today’s society becomes more dependent on computer systems for processing and storing data. Most existing data centers were designed with a power density between 40 and 70 watts per square foot (W/SF), while new facilities require up to 200W/SF. Because increased power loads, and consequently cooling loads, are unable to be met in existing facilities, new data centers need to be built. Building new data centers gives owners the opportunity to explore more energy efficient options in order to reduce costs. Fuel cells are such an option, opposed to the typical electric grid connection with UPS and generator for backup power. Fuel cells are able to supply primary power with backup power provided by generators and/or the electric grid. Secondary power could also be supplied to servers from rack mounted fuel cells. Another application that can benefit from fuel cells is the HVAC system. Steam or high-temperature water generated from the fuel cell can serve absorption chillers for a combined heat and power (CHP) system. Using the waste heat for a CHP system, the efficiency of a fuel cell system can reach up to 90%. Supplying power alone, a fuel cell is between 35 and 60% efficient. Data centers are an ideal candidate for a CHP application since they have constant power and cooling loads. Fuel cells are a relatively new technology to be applied to commercial buildings. They offer a number of advantages, such as low emissions, quiet operation, and high reliability. The drawbacks of a fuel cell system include high initial cost, limited lifetime of the fuel cell stacks, and a relatively unknown failure mode. Advances in engineering and materials used, as well as higher production levels, need to occur for prices to decrease. However, there are several incentive programs that can decrease the initial investment. With a prediction that nearly 75% of all 10 year old data centers will need to be replaced, it is recommended that electrical and HVAC designer engineers become knowledgeable about fuel cells and how they can be applied to these high demand facilities.