160 research outputs found
Comparative seismic performance of a moment frame equipped with Lateral Impact Resilient Double Concave Frictional devices
This study presents a comparative assessment of the seismic performance of a reinforced concrete moment frame equipped with a new isolator. The Lateral Impact Resilient Double Concave Friction Pendulum (LIR-DCFP) bearing has an enhanced inner slider capable of limiting the magnitude of the lateral impact force generated between the inner slider and the restraining rims of the sliding surfaces. Due to the presence of a plane high-friction interface with an internal gap, the novel isolator has an increased energy dissipation capacity that is activated during the lateral impact. Three isolation systems were considered to evaluate the benefits of using LIR-DCFP devices. One conformed by the suggested isolator, and two composed of classic non-articulated Double Concave Friction Pendulum (DCFP) bearings. The isolation devices were modelled employing a numerical formulation based on rigid body dynamics, capable of accounting for the lateral impact behaviour. The superstructure, a reinforced concrete moment resisting frame designed according to the American ASCE/SEI 7-16 standard, was modelled using beam-column elements considering geometric and material nonlinearities. Furthermore, the degrading behaviour of the building was incorporated using a proper degradation model for both the stiffness and the force. Incremental Dynamic Analyses (IDAs) were performed considering the friction coefficient as a random variable to characterize the statistics of the maximum inter-story responses. With the data generated in the IDAs, fragility curves related to the superstructure performance were constructed. Finally, employing the hazard curve, reliability curves were derived. The superstructure equipped with LIR-DCFP bearings presents better seismic performance than the same building equipped with the same size DCFP isolators. The benefits of using the new isolator are not achieved by increasing the lateral capacity of the classic isolation system
STATIC AND DYNAMIC EXPERIMENTAL VALIDATIONS OF THE LATERAL IMPACT RESILIENT DOUBLE CONCAVE FRICTION PENDULUM (LIR-DCFP) BEARING
During high-magnitude earthquakes, large base displacements that exceed the lateral capacity of the isolation level can cause internal impacts jeopardizing the benefits of using seismic isolation. The Lateral Impact Resilient Double Concave Friction Pendulum (LIR-DCFP) bearing has been proposed to mitigate the adverse effects of internal lateral impacts between inner sliders and restraining rims of sliding surfaces. This device has an enhanced inner slider formed by two bodies. These bodies are in contact, generating a plane high-friction interface capable of dissipating additional energy and limiting the magnitude of the impact. A numerical model based on rigid body dynamics has been proposed to represent the dynamic response of structures equipped with LIR-DCFP bearings. The numerical formulation includes important modeling aspects such as lateral impact behavior and large displacements (P-? effects), among other essential phenomena. A prototype of this novel device was constructed to validate its lateral behavior through static experimental tests. As predicted, if the inner slider does not contact the restraining rims of the sliding surfaces, the response of the isolator will be identical to the response of the classical frictional isolators. On the contrary, for larger lateral displacements, the contact between the inner slider and the restraining rims triggers high friction sliding. Finally, experimental tests were conducted to validate the dynamic response of a stiff structure equipped with four LIR-DCFP devices. An accurate prediction of the dynamic response can be obtained by employing the suggested numerical model under the presence or absence of internal lateral impacts
O risco real nas atividades de aventura em regiões montanhosas
O Montanhismo é uma modalidade de aventura abrangente, por generalizar uma considerável quantidade de práticas distintas. O montanhismo moderno abrange um largo espectro de atividades/jogos/esportes, indo das caminhadas e escaladas em blocos de rochas às escaladas em paredes com grande nível de complexidade, de formas extremas em altas montanhas e expedições em grandes altitudes. Cada uma das diferentes modalidades tem objetivos, técnicas, equipamentos, estratégias e regras próprias, além de poderem ser praticadas em superfícies e localizações diversas, o que confere a estas modalidades uma parcela considerável de riscos e a presença constante do perigo. Assim sendo, o artigo tem como propósito apresentar o risco real nas atividades de aventura em regiões montanhosas e sistematizar os principais fatores de risco. Para tal, utilizou-se a revisão bibliográfica e documental, a partir da discussão de diversos autores que já abordaram o tema em questão. A contribuição desse artigo está na sistematização, na formatação gráfica e na apresentação dos fatores de risco no montanhismo, pois permite uma melhor visualização e compreensão destes, possibilitando a elaboração de um plano de ação para evitá-los
A dynamic management framework for socio-ecological system stewardship: A case study for the United States Bureau of Ocean Energy Management
An effective and efficient stewardship of natural resources requires consistency across all decision-informing approaches and components involved, i.e., managerial, governmental, political, and legal. To achieve this consistency, these elements must be aligned under an overarching management goal that is consistent with current and well-accepted knowledge. In this article, we investigate the adoption by the US Bureau of Ocean Energy Management of an environmental resilience-centered system that manages for resilience of marine ecological resources and its associated social elements. Although the framework is generally tailored for this Bureau, it could also be adapted to other federal or non-federal organizations. This paper presents a dynamic framework that regards change as an inherent element of the socio-ecological system in which management structures, e.g., federal agencies, are embedded. The overall functioning of the management framework being considered seeks to mimic and anticipate environmental change in line with well-accepted elements of resilience-thinking. We also investigate the goal of using management for resilience as a platform to enhance socio-ecological sustainability by setting specific performance metrics embedded in pre-defined and desired social and/or ecological scenarios. Dynamic management frameworks that couple social and ecological systems as described in this paper can facilitate the efficient and effective utilization of resources, reduce uncertainty for decision and policy makers, and lead to more defensible decisions on resources
Cure and discontinuation of treatment in a tuberculosis control state programme in Brazil: insights from dispensing data
Poster presented at the 45th ESCP Symposium on Clinical Pharmacy. 4-6 October 2016, Oslo, NorwayN/
Cenário futuro de temperatura para a distribuição geográfica do Chrysoperla externa, inseto benéfico para as pastagens do Brasil.
Distribuição geográfica de crisopideos (Chrysoperla externa) no Brasil a partir de cenários atual e futuros do IPCC.
Clinical profile and treatment discontinuation in a tuberculosis control state programme in Brazil: preliminary results from SINAN database
Poster presented at the 45th ESCP Symposium on Clinical Pharmacy. 4-6 October 2016, Oslo, NorwayN/
Proteínas de ação inseticida com potencial de uso no controle da cigarrinha-daspastagens: uma revisão.
As cigarrinhas-das-pastagens (Hemiptera: Cercopidae) impactam a produção de forragens no Brasil, causando perdas significativas na produção de leite e carne. Por não haver forrageira altamente resistente a todas as espécies de cigarrinhas, uma alternativa para o controle destes insetos é a obtenção de forrageiras geneticamente modificadas (GM) que expressam proteínas de ação inseticida. Portanto, a escolha dos genes mais eficazes para obtenção das forrageiras GM é uma etapa essencial. Assim, este trabalho objetivou listar as proteínas de ação inseticida que têm sido utilizadas para o controle de insetos hemípteros e identificar aquelas com maior potencial de uso para o controle das cigarrinhas-das-pastagens. Para tanto, foi feita uma revisão bibliográfica no repositório NCBI/PubMed com as palavras-chave ?insecticidal proteins? e ?hemiptera? limitada a artigos publicados nos últimos 20 anos (2001 a 2020). Foram listados 663 artigos científicos e, após análise, foram identificados 57 que descreviam o uso de proteínas de ação inseticidas contra hemípteros. Foram extraídos dados dos 57 artigos, sendo identificadas as proteínas utilizadas, seus modos de ação, os insetos hemípteros que foram estudados e a taxa de mortalidade obtida. Baseado nos dados levantados, foram definidas três proteínas de ação inseticida que potencialmente podem ser utilizadas para o controle das cigarrinhas-das-pastagens via obtenção de forrageiras geneticamente modificadas
- …