No description available.

N/A

CESAR, Ricardo Lenz. Geração de malhas por refinamento adptativo usando GPU. 2009. 100 f. Dissertação (Mestrado em ciência da computação)- Universidade Federal do Ceará, Fortaleza-CE, 2009. / Submitted by Elineudson Ribeiro (elineudsonr@gmail.com) on 2016-07-12T16:29:15Z No. of bitstreams: 1 2009_dis_rlcesar.pdf: 14357749 bytes, checksum: 7bad74a149a075f4d9479d6efb083e77 (MD5) / Approved for entry into archive by Rocilda Sales (rocilda@ufc.br) on 2016-07-21T16:11:41Z (GMT) No. of bitstreams: 1 2009_dis_rlcesar.pdf: 14357749 bytes, checksum: 7bad74a149a075f4d9479d6efb083e77 (MD5) / Made available in DSpace on 2016-07-21T16:11:41Z (GMT). No. of bitstreams: 1 2009_dis_rlcesar.pdf: 14357749 bytes, checksum: 7bad74a149a075f4d9479d6efb083e77 (MD5) Previous issue date: 2009 / The high performance of the GPU and the increasing use of its programming mechanisms have stimulated several graphic applications of virtual reality to explore the potential of this device to achieve higher levels of realism. Studies have emerged with a focus on refining the silhouette of geometric meshes, seeking to express better the surface of three-dimensional objects being represented. The type of refining can be applied, for example, a fabric softening raw an avatar by means of an interpolation curve on their surface faces. Basic idea is to make an adaptive mesh discretization of the object and then generate a new silhouette using this discretization. Previous methods are analyzed and improvements are presented which together form the proposed method. The performance obtained is superior due to a better exploitation of parallelism of the GPU, and the proposed technique works well enough with existing mesh without the need to design new models for this. / O alto desempenho da GPU e o crescente uso dos seus mecanismos de programação têm estimulado diversas aplicações gráficas de realidade virtual a explorar melhor o potencial desse dispositivo para alcançar níveis mais altos de realismo. Trabalhos têm surgido com um enfoque no refinamento da silhueta de malhas geométricas, buscando expressar melhor a superfície dos objetos tridimensionais sendo representados. O tipo de refinamento aplicado pode ser, por exemplo, uma suavização da malha bruta de um avatar, por meio da interpolação de uma superfície curva sobre suas faces. A ideia básica é fazer uma discretização adaptativa da malha do objeto e então gerar uma nova silhueta usando essa discretização. Métodos anteriores são analisados e são apresentadas melhorias que juntas formarão o método proposto. O desempenho obtido é superior devido a uma exploração melhor do paralelismo da GPU, e a técnica proposta funciona suficientemente bem com malhas existentes sem necessidade de se projetar novos modelos para isso.

Submitted by Pedro Henrique Rodrigues (pedro.henriquer@ufpe.br) on 2015-03-04T18:21:26Z No. of bitstreams: 2 Dissertacao.pdf: 3554160 bytes, checksum: c0e2e7174583a750223705de5cd01844 (MD5) license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) / Made available in DSpace on 2015-03-04T18:21:26Z (GMT). No. of bitstreams: 2 Dissertacao.pdf: 3554160 bytes, checksum: c0e2e7174583a750223705de5cd01844 (MD5) license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Previous issue date: 2012-03-02 / FACEPE / In the development of critical systems it is common practise to make use of redundancy in order to achieve higher levels of reliability. There are well established design patterns that introduce redundancy and that are widely documented in the literature and adopted by the industry. However there have been few attempts to formally verify them with respect to behavioural preservation. In this work, we purpose an approach to specify such design patterns, called here fault tolerant patterns, using HOL. We use the theorem prover HOL4 to prove the compositionality and correctness of the fault tolerant patterns. We illustrate our approach by modelling three classical fault tolerant patterns: homogeneous redundancy, heterogeneous redundancy and triple modular redundancy. Our model takes into account that the original system (without redundancy) computes a certain function with some delay and is amenable to random failures. In order to prove that a fault tolerant pattern preserves the behaviour of its subsystems, we defined new notions of refinement. Systems engineers commonly accept the fact that fault tolerant patterns do not change the functionality of a system. However, this practise is not compatible with the classical refinement notions. Thus we defined axiomatic notions of refinement to prove that the formalised fault tolerant patterns preserve the behaviour of its subsystems. We also proved that our fault tolerant patterns are compositional in the sense that we can apply fault tolerant patterns consecutively and for an arbitrary number of times. The result of that is still a system whose delay, failure model and functionality can be systematically discovered (by proof) with almost no effort. In order to illustrate the usage of the patterns we applied the triple modular redundancy pattern to a simplified avionic Elevator Control System. We showed that once a fault tolerant pattern is verified, the application of it to a specific system and the proof of the behavioural preservation of the resulting system becomes trivial. This work has been done in collaboration with the Brazilian aircraft manufacturer Embraer.

Thesis advisor: Sara Cordes / Throughout early childhood, children learn various symbolic systems to represent abstract concepts such as quantity. Yet it is unclear how the acquisition of symbols for quantity (e.g., number words; measurement concepts of “seconds”, “minutes”… for time, etc.) may shape nonsymbolic representations of these quantities. While previous work hints at the possibility that acquiring numerical symbols refines numerical acuity (i.e., “refinement hypothesis”), these data are correlational in nature, making it impossible to assess causality. As such, experimental manipulations training the symbolic system are necessary in order to determine whether a causal relation exists. Moreover, these investigations have been limited to the domain of number, making it unclear if similar relations exist in continuous quantities, such as time and space. My dissertation tests whether the relation between symbolic and nonsymbolic abilities holds for the inherently continuous quantity of time, while also providing one of the first investigations of the refinement hypothesis outside of the domain of number. Results reveal that nonsymbolic and symbolic timing are related in childhood, both before and during formal instruction on temporal units of measurement (Experiment 1 & 2), but not in adulthood (Experiment 3). Further, I find no support for the refinement hypothesis: learning temporal symbols did not result in improved temporal acuity (Experiment 2), nor did shifting adults’ symbolic mapping of time shape temporal acuity (Experiment 3). Similarly, learning labels for surface area did not enhance adults’ spatial acuity (Experiment 4). Broader educational implications and areas of future investigation are also discussed. / Thesis (PhD) — Boston College, 2019. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Psychology.

This project investigates the use of a truss network, a structural mechanics model, as a metaphor for adapting a computational fluid dynamics (CFD) mesh. The objective of such adaptation is to increase computational effi- ciency by reducing the numerical error. To drive the adaptation, or to give the scheme an understanding of accuracy, computational errors are translated into forces at mesh vertices via a so-called monitor function. The ball-vertex truss network method is employed as it offers robustness and is applicable to problems in both two and three dimensions. In support of establishing a state-of-the-art adaptive meshing tool, boundary vertices are allowed to slide along geometric boundaries in an automated manner. This is achieved via feature identification followed by the construction of 3rd order bezier surface patches over boundary faces. To investigate the ability of the scheme, three numerical test cases were investigated. The first comprised an analytical case, with the aim of qualitatively assessing the ability to cluster vertices according to gradient. The developed scheme proved successful in doing this. Next, compressible transonic flow cases were considered in 2D and 3D. In both cases, the computed coefficient of lift and moment were investigated on the unrefined and refined meshes and then compared for error reduction. Improvements in accuracy of at least 60% were guaranteed, even on coarse meshes. This is viewed as a marked achievement in the sphere of robust and industrially viable r-refinement schemes.

Adaptive all-hexahedral meshing algorithms have many desirable features. These algorithms provide a mesh that is efficient for analysis by providing a high element density in specific locations, such as areas of high stress gradient or high curvature and reduced mesh density in other areas of less importance. In addition, inside-out hexahedral grid based schemes, using Cartesian structured grids for the base mesh, have shown great promise in accommodating automatic all-hexahedral algorithms. In these algorithms mesh refinement is generally used to capture geometric features. Unfortunately, most adaptive mesh generation algorithms employ a 3-refinement method. This method, although easy to employ, provides a mesh that is coarse in most areas and highly refined in other areas. Because a single refined hex is subdivided into 27 new hexes, regardless of the desired refinement, there is little control on mesh density. This paper will present an adaptive all-hexahedral grid-based meshing algorithm that employs a 2-refinement insertion method. 2-refinement is based on dividing a hex to be refined into eight new hexes. This allows greater control on mesh density which in turn increases computational efficiency.

Accurate and reasonable contract time is important to all aspects of a highway construction project. Unreasonably short contract times can raise the bid price, restrict qualified bidders from submitting bids, reduce the quality of the work, and increase the potential for legal disputes. Conversely, unreasonably long contract times encourage less qualified contractors to submit a bid and are a general inconvenience to the traveling public. The Federal Highway Administration (FHWA) recognizes this, and has recommended that all state highway agencies develop a standardized method for estimating contract performance time. To date, the Virginia Department of Transportation (VDOT) does not have an established method. One major portion of this work is the development of the framework for a multi-level time estimating system to aid in the establishment of contract performance times. This system parallels the VDOT cost estimating process, refining estimates as design details become available along the Project Development Concurrent Engineering Process (PDCEP). Three distinct stages exist along the PDCEP that will facilitate the use of a tool for estimating contract time. Sufficient information to begin the conceptual estimate is known as the project enters the six year plan. The parametric estimate may commence as the project enters the scoping phase. Finally, details for the pre-advertisement time estimate are available upon project field inspection. The second major component of this work, the pre-advertisement estimating database system (BIDDS – Bid Item Duration Data System) was constructed during this work. BIDDS uses project information and characteristics to filter through historical performance time data, returning production data from similar projects. Production data is returned at the bid item level to assist in the estimation of production rates, for calculating activity durations. / Master of Science

No description available.

During an early developmental period, some glycinergic synapses in the brainstem and spinal cord release predominately GABA, which activates GABAA receptors on the postsynaptic membrane. The function of this early GABAergic transmission is unknown but presumed to contribute to synapse maturation. Classically, the enzyme glutamic acid decarboxylase (GAD), which synthesizes GABA from glutamate, has been considered the sole source of GABA in neurons. GABAergic neurons typically express one or both of the two known isoforms of this enzyme, GAD65 and GAD67. However, co-transmitting synapses in the midbrain were recently reported to acquire GABA through other means – GABA transporters (GAT1 and GAT3) and/or aldehyde dehydrogenase (ALDH1A1). To determine the source of GABA in immature glycinergic neurons of the auditory brainstem, we immunostained for GADs, GATs, and ALDH1A1, co-staining with markers for glial cell and synaptic terminals to verify cellular and subcellular location. GAD65 was expressed in synaptic terminals whereas GAD67 was localized to neuronal cell bodies, proximal dendrites, and presumabed synaptic terminals. However, during the peak period of GABA transmission in the first postnatal week, expression levels of both GAD65 and GAD67 were surprisingly low. Although GAT1 and GAT3 expression levels coincided with the peak period of GABA transmission, neither GAT was localized to neuronal cell bodies. In contrast, ALDH1A1 was expressed during the first postnatal week and was localized to neuronal cell bodies. These results suggest that immature glycinergic neurons of the auditory brainstem may not acquire GABA through classical GABA synthesis or GABA reuptake, but perhaps are able to synthesis GABA through the putrescine degradation pathway mediated by ALDH1A1. / Thesis / Master of Science (MSc) / Evolutionarily older parts of the mammalian brain, such as the brainstem, typically play little role in higher-order functions, but contain regulatory centers that are critically important for keeping the organism alive. As conventional wisdom has been that brainstem centers require fast inhibitory communication (mediated by the neurotransmitter glycine) to carry out their critical functions, an ongoing mystery lies in why many immature inhibitory neurons in the developing brainstem use the relatively slow inhibitory neurotransmitter, GABA. We and others have speculated that inhibitory neural circuits of the brainstem require GABA for maturation and/or refinement. As a first step in addressing this question in the auditory brainstem, we looked for the cellular and molecular sources of GABA by performing antibody stains for various proteins known to be involved in GABA synthesis and transport. Our results suggest, somewhat surprisingly, that GABA in the immature brainstem likely arises from non-classical sources.