# Browsing by Subject "Connections"

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Item A population gain control model of spatiotemporal responses in the visual cortex(2009-08) Sit, Yiu Fai; Miikkulainen, Risto; Seidemann, EyalShow more The mammalian brain is a complex computing system that contains billions of neurons and trillions of connections. Is there a general principle that governs the processing in such large neural populations? This dissertation attempts to address this question using computational modeling and quantitative analysis of direct physiological measurements of large neural populations in the monkey primary visual cortex (V1). First, the complete spatiotemporal dynamics of V1 responses over the entire region that is activated by small stationary stimuli are characterized quantitatively. The dynamics of the responses are found to be systematic but complex. Importantly, they are inconsistent with many popular computational models of neural processing. Second, a simple population gain control (PGC) model that can account for these complex response properties is proposed for the small stationary stimuli. The PGC model is then used to predict the responses to stimuli composed of two elements and stimuli that move at a constant speed. The predictions of the model are consistent with the measured responses in V1 for both stimuli. PGC is the first model that can account for the complete spatiotemporal dynamics of V1 population responses for different types of stimuli, suggesting that gain control is a general mechanism of neural processing.Show more Item Preliminary analysis and design of a test setup for evaluating lateral resistance of steel gravity framing systems(2020-06-25) Hernandez Carranza, Jorge Tercero; Clayton, Patricia M.Show more The majority of steel structures in the U.S. follow a typical design practice. This practice consists of having relatively few frames of the building that resists lateral loads, and the remainder of the structure is designed to resist only gravity loads. The elements of this gravity system are connected using “simple shear” connections that are designed and assumed to behave as “perfect pins” that have no flexural strength or stiffness, thus generating no moment resistance at the connection. Nevertheless, past research has shown that the gravity system contributes to the lateral resistance of a building in non-negligible quantities. The main objective of this research is to perform preliminary analyses to support the design of a test specimen that will be used to evaluate the cyclic response of a multi-bay steel gravity framing test specimen subjected to lateral loads. This thesis explained and delineated the test program and concept that will be used in the large-scale system-level testing. Tests will be administered on variable-scale assemblies of two-by-three bays with dimensions of 16’x8’ and two half-stories of 6’. Three servo-controlled hydraulic actuators will be used to impose a displacement on the upper floor of the specimen. The first test specimen will evaluate the response with strong-axis decking metal deck (metal deck ribs oriented parallel to the load direction), and the presence and absence of seams at the column lines. Design and sizing of the specimen elements were done trying to have a continuation of previous research (Donahue, 2019) and based on the current practices in construction (Professional Advisory Committee). Several pushover analyses were done on SAP2000 (Computers and Structures, 2020), to a structural model of the test specimen, using several constructed moment-rotation spring models of hinges at the joints (to represent the simple shear connections). These moment-rotation spring models were developed and validated with the results of previous research (Donahue, 2019) and they accurately characterized the various detailing variations present in the previous studies. The results of these analyses showed the loads and displacements needed to “fail” the specimen, how each variation of the specimen could affect these loads and displacements, and the demands for designing critical elements like base beams, column support clevises, and the top truss diaphragm.Show more Item Roots of polynomials and their connections(2010-08) Wardlaw, Cathy Jo; Armendáriz, Efraim P.; Daniels, Mark L.Show more In the study of mathematics, one of the most useful, relevant topics explored in secondary mathematics remains the zeros of polynomials. This paper will present various ways to explore this topic while preserving the fundamental concept as a whole. In addition, this paper will reveal some distinct relationships between roots and their behavior within the different branches of mathematics. The purpose of this paper is to show how this topic can be inserted at key points in the developmental curriculum to preserve the autonomy of this vital mathematical concept, allowing students to experience the behavior and value of this topic in a variety of contexts.Show more Item Simplified modeling for assessing collapse resistance of steel gravity frames with composite floor systems(2014-05) Oksuz, Umit Can; Williamson, Eric B., 1968-; Engelhardt, Michael D.Show more Progressive collapse is a structural failure that is initiated by the failure of a primary structural member due to manmade or natural reasons and causes a disproportionately large portion of the structure to damage and/or collapse. This thesis is focused on the computational assessment of the performance of steel gravity frames with composite floor systems under column loss scenarios. The ultimate goal is to provide step-by-step guidance to practicing civil/structural engineers on modeling and analyzing full-size structures by using simple structural analysis software with the purpose of determining progressive collapse resistance. In this research project, a steel frame structure with simple framing connections and a composite floor system was tested, modeled, and analyzed under an interior column loss scenario. For the computational analysis part of the research, a simplified modeling approach was developed and verified by comparing the analysis results with detailed finite element model results and available experimental data. Next, the test specimen was modeled with the proposed approach using the SAP2000 software, and an analysis was performed. Results of the analysis were compared with the test data to verify that the model accurately simulates the measured behavior of the structure. In the end, it was concluded that steel gravity frame structures with composite floor systems can be accurately simulated by using the proposed simplified modeling approach up to the point of first element failure. Moreover, it was shown that practicing civil/structural engineers can do quick and simple checks for their structure’s ability to resist progressive collapse by using the methods and approaches that are described in this thesis.Show more