Projecto de execução de fundações e estruturas de uma ponte em betão armado pré-esforçado

Este Trabalho refere-se ao Projecto de Execução de Fundações e Estruturas de uma Ponte Rodoviária em betão armado pré-esforçado, realizado no âmbito do Trabalho Final de Mestrado em Engenharia Civil – Especialização em Estruturas, do Instituto Superior de Engenharia de Lisboa. O Projecto de Execução é composto de Peças Escritas e Peças Desenhadas. Nas Peças Escritas estão incluídos: Memória Justificativa e Descritiva; Cálculos Justificativos e Anexos. A ponte é composta por dois tabuleiros paralelos com 10,28m de largura cada um e afastados entre si de 0,10m. A obra é constituída de 8 tramos; os tramos correntes com 31m de comprimento e os tramos extremos com 25 e 20m de comprimento, perfazendo um comprimento total de 231m. A obra foi parcialmente isolada dos sismos pela introdução, em todos os pilares, de aparelhos de apoio de elevado amortecimento sísmico do tipo HDRB (High Damping Rubber Bearings). Encontram-se particularmente discriminadas e detalhadas neste projecto as seguintes situações: - Cálculo do Pré-esforço e respectivas perdas; - Acção das sobrecargas rodoviárias; - Diferença de comportamento da obra na entrada em serviço e no longo prazo; - Análise sísmica e do isolamento sísmico; - Estudo dos efeitos diferidos: retracção e fluência. Tendo as abordagens de cálculo e as verificações de segurança seguido a regulamentação nacional em vigor, nomeadamente RSA e REBAP, foi no entanto feita uma aproximação às regras do “Capacity Design” previstas no EC8, em que se privilegia a actuação do projectista sobre o comportamento da estrutura, procurando uma resposta não linear da mesma, visando garantir que: - A rotura não ocorrerá nos elementos de fundação; - Nos pilares a dissipação de energia se faz através de rótulas plásticas, evitando-se roturas associadas a esforços transversos. A aplicação destas regras neste Projecto demonstrou haver um agravamento substancial na definição dos esforços a que devem resistir alguns dos componentes da estrutura, designadamente os pilares e as fundações, originando soluções de secções de betão e armaduras bem mais exigentes do que aqueles que resultariam da simples verificação de segurança, pela comparação entre esforços actuante e esforços resistentes “secção a secção”, imposta pela actual regulamentação nacional.

Modelação numérica de uma solução de reforço de solos para fundações de aerogeradores

Dissertação de mestrado integrado em Engenharia Civil

Method for estimating railroad track settlements due to dynamic traffic loads

This paper is the result of real-scale physical modeling study designed to simulate the load-deformation characteristics of railroad foundation systems that include the railroad ties, the ballast, and the sub-base layers of a railroad embankment. The study presents comparisons of the application of dynamic loads of 100kN on the rails, and the resulting deformations during a 500,000 cycle testing period for three rail support systems; wood, concrete and steel. The results show that the deformation curve has an exponential shape, with the larger portion of the deformation occurring during the first 50,000 load cycles followed by a tendency to stabilize between 100,000 to 500,000 cycles. These results indicate that the critical phase of deformations of a new railroad is within the first 50,000 cycles of loading, and after that, it slowly attenuates as it approaches a stable value. The paper also presents empirically derived formulations for the estimation of the deformations of the rail supports as a result of rail traffic.

Al Redescubrimiento de los Usuarios en las Unidades de Información

Se presenta una serie de ideas en relación con la nueva concepción que deben seguir las empresas y por lo tanto las Unidades de Información, respecto al cliente, tomando como marco de referencia o fundamento la Teoría de Sistemas.Se concluye entre otras cosas, que el usuario es la razón de ser de nuestras organizaciones y será él quien última instancia decidirá la existencia o extinción de éstas.

Research study of criteria and procedures for evaluating scientific information retrieval systems; final report. Prepared for Office of Science Information Service, National Science Foundation, Washington, D.C., contract NSF-C218.

"AD 273 115."

Subterranean Urban Systems Study, Graham Foundation Grant, 1971-1974

[Conceptual Sketch], untitled. Ink sketch on spiral notebook paper, 8 1/4 x 10 3/4 inches [from photographic copy by Lance Burgharrdt]

Subterranean Urban Systems Study, Graham Foundation Grant, 1971-1974

[Conceptual Sketches], untitled. Ink sketches on spiral notebook paper, 8 1/4 x 10 3/4 inches [from photographic copy by Lance Burgharrdt]

Subterranean Urban Systems Study, Graham Foundation Grant, 1971-1974

[Conceptual Sketches], untitled. Ink sketches on spiral notebook paper, 8 1/4 x 10 3/4 inches [from photographic copy by Lance Burgharrdt]

Subterranean Urban Systems Study, Graham Foundation Grant 1971-1974

[Conceptual Sketches], untitled. Digital image only of blue ink sketches on spiral notebook paper, initialed, 8 1/4 x 10 3/4 inches

Comparative study of chemical and mechanical retentive systems for bonding of indirect composite resin to commercially pure titanium

This study evaluated the effect of chemical and mechanical surface treatments for cast metal alloys on the bond strength of an indirect composite resin (Artglass) to commercially pure titanium (cpTi). Thirty cylindrical metal rods (3 mm diameter x 60 mm long) were cast in grade-1 cpTi and randomly assigned to 6 groups (n=5) according to the received surface treatment: sandblasting; chemical treatment; mechanical treatment - 0.4 mm beads; mechanical treatment - 0.6 mm beads; chemical/mechanical treatment - 0.4 mm; and chemical/mechanical treatment - 0.6 mm beads. Artglass rings (6.0 mm diameter x 2.0 mm thick) were light cured around the cpTi rods, according manufacturer's specifications. The specimens were invested in hard gypsum and their bond strength (in MPa) to the rods was measured at fracture with a universal testing machine at a crosshead speed of 2.0 mm/min and 500 kgf load cell. Data were analyzed statistically by one-way ANOVA and Tukey test (a=5%). The surface treatments differed significantly from each other (p<0.05) regarding the recorded bond strengths. Chemical retention and sandblasting showed statistically similar results to each other (p=0.139) and both had significantly lower bond strengths (p<0.05) than the other treatments. In conclusion, mechanical retention, either associated or not to chemical treatment, provided higher bond strength of the indirect composite resin to cpTi.

Coronal and apical leakage analysis of two different root canal obturation systems

This study compared the coronal and apical leakage of AH Plus with gutta-percha to that of Epiphany with Resilon. Twenty-four single rooted teeth were instrumented and divided into 2 groups according to the solutions for smear layer removal and the obturation materials employed: Group A - 17% EDTA-T and AH Plus with gutta-percha; Group B - primer and Epiphany with Resilon. The Group B specimens were light-cured in the coronal area for 20 s. The external root surfaces were covered with a double layer of ethyl cyanoacrylate, except for the apical foramen and the cavity access. The teeth were immersed in 0.5% methylene blue for 48 h. The specimens were rinsed, dried and axially split for dye penetration measurement with the ImageLab 2.3 software. The t-test showed no significant differences for coronal leakage between the groups, but there were significant differences for apical leakage between the groups (P < 0.05). AH Plus with gutta-percha and Epiphany with Resilon provided the same coronal seal, whereas Epiphany with Resilon provided the best apical seal.

Synchronization of Discrete-Time Chaotic Systems in Bandlimited Channels

Over the last couple of decades, many methods for synchronizing chaotic systems have been proposed with communications applications in view. Yet their performance has proved disappointing in face of the nonideal character of usual channels linking transmitter and receiver, that is, due to both noise and signal propagation distortion. Here we consider a discrete-time master-slave system that synchronizes despite channel bandwidth limitations and an allied communication system. Synchronization is achieved introducing a digital filter that limits the spectral content of the feedback loop responsible for producing the transmitted signal. Copyright (C) 2009 Marcio Eisencraft et al.

Integration and visualization of systems biology data in context of the genome

Background: High-density tiling arrays and new sequencing technologies are generating rapidly increasing volumes of transcriptome and protein-DNA interaction data. Visualization and exploration of this data is critical to understanding the regulatory logic encoded in the genome by which the cell dynamically affects its physiology and interacts with its environment. Results: The Gaggle Genome Browser is a cross-platform desktop program for interactively visualizing high-throughput data in the context of the genome. Important features include dynamic panning and zooming, keyword search and open interoperability through the Gaggle framework. Users may bookmark locations on the genome with descriptive annotations and share these bookmarks with other users. The program handles large sets of user-generated data using an in-process database and leverages the facilities of SQL and the R environment for importing and manipulating data. A key aspect of the Gaggle Genome Browser is interoperability. By connecting to the Gaggle framework, the genome browser joins a suite of interconnected bioinformatics tools for analysis and visualization with connectivity to major public repositories of sequences, interactions and pathways. To this flexible environment for exploring and combining data, the Gaggle Genome Browser adds the ability to visualize diverse types of data in relation to its coordinates on the genome. Conclusions: Genomic coordinates function as a common key by which disparate biological data types can be related to one another. In the Gaggle Genome Browser, heterogeneous data are joined by their location on the genome to create information-rich visualizations yielding insight into genome organization, transcription and its regulation and, ultimately, a better understanding of the mechanisms that enable the cell to dynamically respond to its environment.

Modeling Two-Oscillator Circadian Systems Entrained by Two Environmental Cycles

Several experimental studies have altered the phase relationship between photic and non-photic environmental, 24 h cycles (zeitgebers) in order to assess their role in the synchronization of circadian rhythms. To assist in the interpretation of the complex activity patterns that emerge from these ""conflicting zeitgeber'' protocols, we present computer simulations of coupled circadian oscillators forced by two independent zeitgebers. This circadian system configuration was first employed by Pittendrigh and Bruce (1959), to model their studies of the light and temperature entrainment of the eclosion oscillator in Drosophila. Whereas most of the recent experiments have restricted conflicting zeitgeber experiments to two experimental conditions, by comparing circadian oscillator phases under two distinct phase relationships between zeitgebers (usually 0 and 12 h), Pittendrigh and Bruce compared eclosion phase under 12 distinct phase relationships, spanning the 24 h interval. Our simulations using non-linear differential equations replicated complex non-linear phenomena, such as ""phase jumps'' and sudden switches in zeitgeber preferences, which had previously been difficult to interpret. Our simulations reveal that these phenomena generally arise when inter-oscillator coupling is high in relation to the zeitgeber strength. Manipulations in the structural symmetry of the model indicated that these results can be expected to apply to a wide range of system configurations. Finally, our studies recommend the use of the complete protocol employed by Pittendrigh and Bruce, because different system configurations can generate similar results when a ""conflicting zeitgeber experiment'' incorporates only two phase relationships between zeitgebers.