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Liu, Mingsheng (August 1992)[more][less]
Abstract: The influence of heat recovery on the energy impact of air infiltration, and the systematic error due to the steady-state method were studied both experimentally and theoretically. Two methodologies suitable for measurement of the overall heat loss factors in full-size houses have been developed and validated. Dynamic measurements of Infiltration Heat Exchange effectiveness (IHEE), which expresses the air infiltration heat recovery as a fraction of the classical value of air infiltration energy consumption, showed that results from earlier steady-state measurements can be approximately applied to dynamic conditions when solar radiation is not present. However, this study has shown for the first time that IHEE is strongly dependent on air flow direction due to the impacts of air flow on the recovery or rejection of solar radiation energy. IHEE values greater than one and less than zero have been measured. These values are impossible in the absence of solar radiation. The results highlight the necessity of considering the air infiltration heat recovery and improving the current design methods for calculating the heating and cooling loads in buildings. The experimental and theoretical investigation show that steady-state methodology can: *be used without systematic error in the case of constant air flow *result in IHEE prediction error in a range of 1% to 8% when one-way dynamic air f1ow is present *cause significantly larger error when balanced dynamic air flow is present. The SSP (Single input and Single output data Pair) method can identify UAo of an enclosure using short term measurement data, typically a few hours long. It has overcome most of the typical problems in UA0 identification, such as errors due to thermal storage, ground heat transfer, inter-correlated multi-inputs, and solar radiation. The STAM (Short Term Average Method) has also been developed which makes it possible for the first time to determine both the UA and the solar aperture precisely under outdoor conditions from a two-day or a three-day test. These methods were developed and used to measure heat loss factors needed to determine IHEE values in this study. URI: http://handle.tamu.edu1969.1/6463 Files in this item: 0
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Noboa, Homero L. (December 1991)[more][less]
Abstract: A model of the radiant heat transfer in attics containing dusty radiant barriers was developed. The geometrical model was a triangular enclosure in which the temperatures of the enclosing surfaces were known. The dust particles were simulated as areas of diameter equal to the mean diameter of the real dust to be analyzed and an emissivity substantially larger than the emissivity of the radiant barrier. Several shape factors were calculated using shape factor algebra, including a procedure to find the shape factor between a small rectangle and a triangular surface perpendicular to the rectangular plane. The thermal model was developed using the "Net Radiation Method" in which the net heat exchange between the surfaces surrounding the enclosure was found by solving a system of equations that has as many equations as the number of surfaces involved in the calculations. This led to the necessity of solving a very large system of equations in order to account for the dust particles in a representative amount. The solution of the system of equations provided the heat flux for each element of the enclosure. Finally, replacing the radiant barrier and the dust particles for an equivalent surface corresponding to the dusty radiant barrier provided the means to calculate the emissivity of this dusty radiant barrier. The theoretical model was tested to assess its validity. The experimentation was carried out using a reflection emissometer to measure the increase of the emissivity of aluminum radiant barrier when known quantities of dust were artificially applied to it. The experimental results showed good agreement with the theoretical model. A linear relationship between the emissivity and the area of dust coverage was found. The simple relation developed can be used in future research which still has to deal with the determination of the area of dust coverage by using the geometrical model of dust superposition or other statistical model to simulate the random location of random size dust particles over the radiant barrier. URI: http://hdl.handle.net/1969.1/6461 Files in this item: 0
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Baltazar-Cervantes, Juan-Carlos (December 2006)[more][less]
Abstract: This dissertation provides one methodology to determine potential energy savings of buildings with limited information. This methodology is based upon the simplified energy analysis procedure of HVAC systems and the control of the comfort conditions. Numerically, the algorithm is a tailored exhaustive search over all the independent variables that are commonly controlled for a specific type of HVAC system. The potential energy savings methodology has been applied in several buildings that have been retrofitted and/or commissioned previously. Results from the determined savings for the Zachry building at Texas A&M after being commissioned show a close agreement to the calculated potential energy savings (about 85%). Differences are mainly attributed to the use of simplified models. Due to the restriction of limited information about the building characteristics and operational control, the potential energy savings method requires the determination of parameters that characterize its thermal performance. Thus, a calibrated building is needed. A general procedure has been developed to carry out automated calibration of building energy use simulations. The methodology has been tested successfully on building simulations based on the simplified energy analysis procedure. The automated calibration is the minimization of the RMSE of the energy use over daily conditions. The minimization procedure is fulfilled with a non-canonical optimization algorithm, the Simulated Annealing, which mimics the Statistical Thermodynamic performance of the annealing process. That is to say, starting at a specified temperature the algorithm searches variable-space states that are steadier, while heuristically, by the Boltzmann distribution, the local minima is avoided. The process is repeated at a new lower temperature that is determined by a specific schedule until the global minimum is found. This methodology was applied to the most common air-handler units producing excellent results for ideal cases or for samples modified with a 1% white noise. URI: http://hdl.handle.net/1969.1/6456 Files in this item: 0
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Patel, Bhavini Narendrakumar (March 20, 2008)[more][less]
Abstract: Salmonella typhimurium is a bacterium that causes many food-borne illnesses such as gastrointestinal infections, diarrhea, and abdominal cramps. It affects 700,000 to 3.8 million people each year. The SseB protein, a part of the Salmonella Pathogenicity Island II (SPI2), plays a critical role in the pathogenesis of gastrointestinal infections. It is part of the Type III Secretion System (TTSS) that is involved in translocating proteins from the bacteria to the host gastro intestinal-epithelial cells. The aim of the research project is to clone, purify the SseB protein from Salmonella typhimurium and obtain a diffracting-quality crystal that will give high resolution data so that the structure of the protein can be determined using x-ray diffraction patterns. The SseB gene was amplified and cloned into pET30b vector and transformed into E. coli novablue cells. The SseB protein is then expressed into E. coli BL21 cells and purified using various chromatographic methods. Purified protein was used for crystallization and diffracting quality crystals were obtained using grid screening method. SseB protein crystallized in P-orthorhombic space group (P 21 21 21) and diffracted to 3.8Å. Further optimization is underway to get a good diffracting quality crystal. It is important to determine the crystal structure of SseB since this will reveal its role in the interaction with other translocation complex such as (SseC and SseD). Based on the structural information, potential drug targets can be designed for translocon complex, which can further prevent diseases caused by the bacterium Salmonella and other closely related bacteria. URI: http://hdl.handle.net/1969.1/6431 Files in this item: 0
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Haberl, J. S.; Melek, Z.; Akleman, E. (The Journal of Visualization and Computer Animation, July 2001)[more][less]
Abstract: This paper summarizes a function-based approach to model and animate 2D and 3D flows. We use periodic functions to create cyclical animations that represent 2D and 3D flows. These periodic functions are constructed with an extremely simple algorithm from a set of oriented lines. The speed and orientation of the flow are described directly by the orientation and the lengths of these oriented lines. The resulting cyclical animations are then obtained by sampling the constructed periodic functions. Our approach is independent of dimension, i.e. for 2D and 3D flow the same types of periodic functions are used. Rendering images for 2D and 3D flows is slightly different. In 2D function values directly are mapped to color values. On the other hand, in 3D function values are first mapped to color and opacity and then the volume is rendered by our volume renderer. Modeled and animated flows are used to improve the visualization of operations of rolling piston and rotary vane compressors. URI: http://hdl.handle.net/1969.1/6430 Files in this item: 0
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