Browsing by Subject "Windows"
Now showing 1 - 13 of 13
Results Per Page
Sort Options
Item A parametric study of dynamic response of rectangular window glass plates(Texas Tech University, 1989-05) Kamineni, SridharNot availableItem A Partitioning Approach for Parallel Simulation of AC-Radial Shipboard Power Systems(2011-08-08) Uriarte, Fabian MarcelAn approach to parallelize the simulation of AC-Radial Shipboard Power Systems (SPSs) using multicore computers is presented. Time domain simulations of SPSs are notoriously slow, due principally to the number of components, and the time-variance of the component models. A common approach to reduce the simulation run-time of power systems is to formulate the electrical network equations using modified nodal analysis, use Bergeron's travelling-wave transmission line model to create subsystems, and to parallelize the simulation using a distributed computer. In this work, an SPS was formulated using loop analysis, defining the subsystems using a diakoptics-based approach, and the simulation parallelized using a multicore computer. A program was developed in C# to conduct multithreaded parallel-sequential simulations of an SPS. The program first represents an SPS as a graph, and then partitions the graph. Each graph partition represents a SPS subsystem and is computationally balanced using iterative refinement heuristics. Once balanced subsystems are obtained, each SPS subsystem's electrical network equations are formulated using loop analysis. Each SPS subsystem is solved using a unique thread, and each thread is manually assigned to a core of a multicore computer. To validate the partitioning approach, performance metrics were created to assess the speed gain and accuracy of the partitioned SPS simulations. The simulation parameters swept for the performance metrics were the number of partitions, the number of cores used, and the time step increment. The results of the performance metrics showed adequate speed gains with negligible error. An increasing simulation speed gain was observed when the number of partitions and cores were augmented, obtaining maximum speed gains of <30x when using a quadcore computer. Results show that the speed gain is more sensitive to the number partitions than is to the number of cores. While multicore computers are suitable for parallel-sequential SPS simulations, increasing the number of cores does not contribute to the gain in speed as much as does partitioning. The simulation error increased with the simulation time step but did not influence the partitioned simulation results. The number of operations caused by protective devices was used to determine whether the simulation error introduced by partitioning SPS simulations produced a inconsistent system behavior. It is shown, for the time step sizes uses, that protective devices did not operate inadvertently, which indicates that the errors did not alter RMS measurement and, hence, were non-influential.Item Analysis of the window damaging mechanism in windstorms(Texas Tech University, 1974-05) Minor, Joseph EStudies of the behavior of window glass in windstorms have revealed that significant numbers of window glass failures may be attributed to windborne missiles. In addition to detailed discussions of the role of windborne missiles in window failure incidents, the presentation includes (1) an analysis of the character and dynamic properties of the damaging missile, (2) an analysis of window glass response to wind pressure acting in conjunction with missile impact, and (3) a discussion of the innovative process through which results of the investigation must pass in order to reach professional practice. Surveys of 54 rooftops in two urban areas suggested that large quantities of loose gravel present a potential hazard to adjacent glass curtain walls in multistory buildings. Dynamic analyses of the average rock size (0.61 gm) reveal that windspeeds in the 80-120 mph range can easily lift and propel roof gravel at speeds up to 90 fps -- missile speeds that are well within the range of impact speeds that will break glass. Extensive treatments of window glass response under conditions of uniformly distributed wind pressure acting in conjunction with small missile impact constitute the second major part of the presentation. Theoretical and experimental methods are employed to evaluate the response of two representative sizes of square glass windows (1 sq ft and 6 sq ft) to impacts from two representative sizes of missiles (0.61 gm and 5.55 gm) under several conditions of superposed wind pressure. Theoretical methods are advanced which characterize the response phenomena, and which permit predictions of failure modes. Experimental evaluations are presented to verify the theoretical characterizations of response, and to provide specific information regarding glass breakage phenomena under the loading conditions considered. It is concluded from these analyses that: (1) statistically average roof gravel missiles will break window glass at mean minimum impact velocities in the 40-60 fps range, (2) the presence of wind pressure coincident with missile impact will reduce the mean minimum impact velocity necessary for failure under certain missile size and glass geometry conditions, and (3) The presence of wind pressure coincident with missile induced glass fracture will assure total shattering of window glass panels in a high precentage of such impact incidents. The final part of the presentation contains discussions of important technological factors identified by the research and an outline of the innovative process involved with integrating the research into professional practice. It is concluded that roof gravel is available, it menaces glass windows in multistory buildings, and it can be lifted and propelled by winds with sufficient momentum to break windows. Conclusions related to glass failure mechanisms in windstorms have long range implications for the development of new glass design procedures. Development of these procedures and their acceptance by the architectural and engineering professions will involve a long "innovative process." It is concluded that additional research, extensive professional involvement, and active involvement with the building code and standard activity will be required to move new glass design technology into professional practice.Item Breakage characteristics of window glass subjected to small missle impacts.(Texas Tech University, 1974-12) Beason, William L.Not availableItem Evaluation of a building with respect to wind in an integrated windows environment(Texas Tech University, 1995-12) Teal, Mark H.Evaluating a building's performance in a windstorm has previously been a long, coitputationally intensive, manual process. It has also required the time of an expert to perform all of the calculations to insure the latest knowledge of wind/building interaction is properly used to guide the process and interpret the results. This paper presents the integration of a knowledge based expert system with more traditional algorithmic programs in an effort to automate the evaluation. The expert system uses knowledge gleaned from actual experts in wind engineering to guide the repetitive calculations and comparisons, which the algorithmic programs can accorrplish many times faster than a human. The Microsoft Windows operating system offers a number of different methods of intertask communication, user interaction, and data management. Ultimately, the user must have convenient access to the database auid knowledge base, as well as an accurate analysis of the building. Different combinations of intertask communication have been explored, noting their appropriateness in terms of memory limitations and time consumption.Item Failure prediction for heat treated window glass(Texas Tech University, 1995-12) Bove, Paul MarkA failure prediction model for heat treated window glass has been advanced. The failure prediction model for heat treated window glass is an extension of the failure prediction methodology developed for annealed window glass. The failure prediction model for heat treated window glass relates the probability of window glass failure to the characteristics of the surface flaws on the glass and the magnitude of the induced residual compressive surface stress in the glass. The characteristics of the surface flaws can only be estimated from the results of carefully controlled window glass failure tests. Four samples of heat treated monolithic window glass are tested to failure under uniform lateral loading which increases linearly with time from the inception of loading to failure. Surface strength parameters are estimated for three samples of new heat treated window glass using the failure prediction model in conjunction with their 60-second equivalent failure strength data and the residual compressive surface stress in the glass. The magnitudes of the residual compressive surface stresses in the new heat treated window glass samples are estimated using stress measuring devices. The surface strength parameters and the magnitude of the induced residual compressive surface stress for a sample of weathered heat strengthened window glass are estimated using a statistical procedure in conjunction with the failure prediction model.Item Investigation of the mechanics of windborne missile impact on window glass(Texas Tech University, 1999-12) Bole, Scott A.Engineers have recognized that failure of the building envelope is one mechanism that can lead to severe damage of structures during windstorms. The building envelope consists of the roof, doorways, windows, and cladding components that form the exterior wall system of a building. Failure of the building envelope results in internal pressurization of the structure which may lead to structural failure. For this reason, engineers have begun to focus on ways to make the building envelope resistant to the effects of severe windstorms. Window glass is one type of cladding material. Of the threats posed by a windstorm, the major threat to window glass consists of windborne debris. ASTM El886, ASTM El996, and SSTD 12-99 address the Issue of resistance to windborne missile impacts. This thesis concludes that a simple statement of an object's kinetic energy upon impact by itself cannot serve to predict the outcome of the impact. Conservation of angular momentum occurs during a missile impact on window glass. Finally, energy is lost during a missile impact on window glass.Item Load resistance of trapezoidal window glass(Texas Tech University, 2001-12) Jackson, Ryan CrawfordVirtually all glass used in aircraft control tower cabs have a trapezoidal geometry. Currently, the Federal Aviation Administration (FAA) has no formal design methodology for trapezoidal window glass. The objective of the research presented herein consists of gaining insight into the behavior and load resistance of trapezoidal window glass. The research consisted of loading trapezoidal window glass specimens to fracture using a load that increased linearly with time, measuring the magnitude of loading at fracture and locating the fracture origin, and measuring the deflection of the window glass. Glass Research and Testing Laboratory (GRTL) staff at Texas Tech University tested one sample comprised of 13 monolithic glass specimens removed from Insulating Glass (IG) units and a second sample comprised of 8 Laminated Glass (LG)lites. Analyses of failure load data indicate that load resistance of the monolithic sample falls below values that current design methodology predicts. Even so, the experimental load resistance data are not significantly lower than other experimental load resistance data. Experimental load resistance data from the laminated glass sample falls in line with values predicted by current design methodologies.Item Missile impact resistance of window glass constructions(Texas Tech University, 1995-05) Abraham, Vinu JosephNot availableItem Repair versus replace, a second look : the windows of the tower at the University of Texas at Austin(2010-05) Freeman, Emily Paige, 1984-; Gale, Frances; Holleran, MichaelThe Secretary of the Interior’s Standards for the Treatment of Historic Buildings promote repair rather than replacement of deteriorated features when possible. Though replacement and retrofitted elements may provide improved energy efficiency with a minor impact on appearance, there is currently no guide for objectively considering the potential benefits of such treatments for historic buildings. In an effort to provide decision-making tools to those seeking to balance both preservation and economic/ sustainability concerns, this thesis will present an approach to weighing treatment options specifically for windows, including modifications for energy efficiency that are not specifically endorsed by the Secretary of the Interior’s Standards. This thesis explores the critical decision processes involved in selecting to repair or replace deteriorated historic windows, and examines those of the Main Building Tower of the University of Texas as a case study. The steel windows of the Tower, which was completed in 1937, suffer from corrosion and are not performing optimally in terms of energy efficiency. An understanding of the history and significance of the building, the current condition and performance of the windows, balanced against project-specific goals and an evaluation of current treatment options for historic windows helped narrow the potential options for the Tower. Including a “decision tree” that assists users in selecting an appropriate treatment, this thesis maps the considerations necessary to arrive at an informed solution, which may be applied to other projects with varying existing conditions and project objectives.Item Semi-empirical model of convection heat transfer at windows and blinds near floor diffusers for use in building energy modeling(2010-08) Clark, Jordan Douglas; Novoselac, Atila; Siegel, JeffreyAccurate modeling of energy flows in buildings is necessary for optimization of mechanical systems, and architectural designs and components. One specific process which has been studied little is that of forced convection on the interior surfaces of window assemblies, which is present in the majority of newly constructed commercial buildings. To this end, energy flows associated with a specific Heating Ventilation and Air-Conditioning (HVAC) configuration- a floor register near a glass curtain wall with or without Venetian blinds- are analyzed experimentally and partially described with accepted theory. Natural convection at the same surface is analyzed as well, both to establish a baseline and to experimentally validate the experimental setup. A 60 cubic meter environmental chamber with precisely controlled interior conditions and electrical resistance heating panels is employed to study heat transfer at the interior surfaces of a building’s envelope. Convection heat transfer processes for various blind angles, HVAC regimes, surface temperatures, and window sizes are examined. Results show that convection at window and blind surfaces is highly dependent on blind angle, supply temperature and flow rate, moderately dependent on room-supply air temperature difference and HVAC regime, and weakly dependent on surface-supply air temperature difference. A simplified model of convection heat transfer in this particular situation is proposed for easy implementation in energy modeling software.Item The effects of thickness and temper on the resistance of glass to small missile impact(Texas Tech University, 1978-05) Harris, Philip LloydWith regard to window glass breakage, there are two predominate modes of failure: uniform wind pressure and missile impact. This paper is concerned with the latter and deals with the effects of sample thickness, temper, and missile weight on the impact resistance of glass. Included in this research are (1) a discussion of past research as it relates to the present study, (2) presentation of data with relevant statistical analyses, and (3) discussion of appropriate theories of failure. Surveys of previous research revealed that a relatively small number of investigators have studied the effects of missile impact on window glass. The survey also showed that missiles are a potential hazard to glass during windstorms and revealed that the size of the missile is major controlling factor in causing glass failure. Impact tests were run on six different thicknesses of glass ranging from 3/16 in. to 3/4 in. at four temper levels and with two missile weights, 5.55 gmf and 28.14 gmf. Linear regressions were performed on the experimental data to relate thickness, missile weight, and amount of heat treating to the velocity required to break a sample of glass. Confidence bands were determined from the regressions. From observations of both the data and the statistical analyses, four conclusions were drawn: (1) Within the range of thicknesses tested, the lowest velocity required to break a sample of glass did not occur in the smallest thickness. (2) This minimum missile velocity is not the same for annealed and heat treated glass. (3) The missile weight has a more pronounced effect on annealed glass than on heat treated glass. (4) The degree of heat treatment appears to affect the missile resistance of glass. Relevant impact theories were employed to explain trends in the experimental data. The stress wave theory appears to explain the trends in the data best.Item The strength of new window glass using surface characteristics(Texas Tech University, 1984-08) Kanabolo, Diboro CelestineNot available