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Ruiz-Salcines Pablo Appendini Christian M. Salles Paulo Rey Wilmer Vigh Jonathan L. 《Natural Hazards》2021,105(1):431-459
Natural Hazards - This study presents a new approach to assess storm surge risk from tropical cyclones under climate change by direct calculation of the local flood levels using a limited number of... 相似文献
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A numerical model has been developed for the simulation of turbidity currents driven by nonuniform, non cohesive sediment and flowing over a complex three dimensional submarine topography. The model is based on an alternative approach known as Cellular Automata paradigm. The model is validated by comparing a simulation with a reported field-scale event. The chosen case is a turbidity current which occurred in Capbreton Canyon and was initiated by a storm in December 1999. Using data from recent oceanographic cruises, the deposit of the event has been precisely described, which constrain values of model parameters. The model simulates the 1999 turbidity current over the actual canyon topography and related turbidite using three different types of particle. The model successfully simulates areas of erosion and deposition in the canyon. It predicts the vertical and longitudinal grain size evolution, and shows that the fining-up sequence can be deposited by several phases of deposition and erosion related to the current energetic variation during its evolution. This result could explain the presence of intrabed contacts or the frequent lack of facies in Bouma sequences. 相似文献
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The relevant theory is presented and numerical results are compared with the analytical solution for the interaction of non-breaking waves with an array of vertical porous circular cylinders on a horizontal bed. The extension to the cases of unidirectional and multidirectional waves is obtained by means of a transfer function. The influence of the mechanical properties of porous structures and wave irregularity on wave transformation is analysed. Results for unidirectional and multidirectional wave spectra are compared to those obtained for regular waves. The model presented reproduces well the analytical results and provides a tool for analysing several engineering problems. 相似文献
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Salles Lucas A. Vani Bruno C. Moraes Alison Costa Emanoel de Paula Eurico R. 《Surveys in Geophysics》2021,42(4):999-1025
Surveys in Geophysics - Over the last 15 years, the satellite constellation of the global positioning system (GPS) has been modernized for more precise applications, with the introduction... 相似文献
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Contributions of individual countries?? emissions to climate change and their uncertainty 总被引：1，自引：0，他引：1
Niklas H?hne Helcio Blum Jan Fuglestvedt Ragnhild Bieltvedt Skeie Atsushi Kurosawa Guoquan Hu Jason Lowe Laila Gohar Ben Matthews Ana Claudia Nioac de Salles Christian Ellermann 《Climatic change》2011,106(3):359-391
We have compiled historical greenhouse gas emissions and their uncertainties on country and sector level and assessed their contribution to cumulative emissions and to global average temperature increase in the past and for a the future emission scenario. We find that uncertainty in historical contribution estimates differs between countries due to different shares of greenhouse gases and time development of emissions. Although historical emissions in the distant past are very uncertain, their influence on countries?? or sectors?? contributions to temperature increase is relatively small in most cases, because these results are dominated by recent (high) emissions. For relative contributions to cumulative emissions and temperature rise, the uncertainty introduced by unknown historical emissions is larger than the uncertainty introduced by the use of different climate models. The choice of different parameters in the calculation of relative contributions is most relevant for countries that are different from the world average in greenhouse gas mix and timing of emissions. The choice of the indicator (cumulative GWP weighted emissions or temperature increase) is very important for a few countries (altering contributions up to a factor of 2) and could be considered small for most countries (in the order of 10%). The choice of the year, from which to start accounting for emissions (e.g. 1750 or 1990), is important for many countries, up to a factor of 2.2 and on average of around 1.3. Including or excluding land-use change and forestry or non-CO2 gases changes relative contributions dramatically for a third of the countries (by a factor of 5 to a factor of 90). Industrialised countries started to increase CO2 emissions from energy use much earlier. Developing countries?? emissions from land-use change and forestry as well as of CH4 and N2O were substantial before their emissions from energy use. 相似文献
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Sousasantos J. Abdu M. A. de Paula E. R. Moraes A. O. Salles L. A. Affonso B. J. 《GPS Solutions》2022,26(3):1-9
Traditional intersatellite communications for shared timing information rely on microwave transceivers such as those in Milstar, AEHF, and Iridium constellations. With extensive space heritage and well-established engineering and performance specifications, these methods have typified the field of high-performance satellite synchronization for decades, recently introduced into active GNSS satellite constellations such as BeiDou. Optical crosslinks, currently investigated as an augmentation or alternative to traditional microwave-based methods, can provide enhanced precision to intersatellite ranging and time transfer, performing beyond one-way or uplink/downlink microwave-based communications. The challenges of time transfer through optical links and crosslinks can significantly impact the systems architecture, optical terminal complexity, and agreements on international standards. Orders-of-magnitude precision enhancement can enable novel timing and ranging technologies allowing for advanced navigation capabilities. Additionally, basic scientific studies with a fleet of synchronized satellites could inform fundamental physics studies on a truly global scale. We evaluate the benefits, drawbacks, and potential applications of satellite synchronization through microwave and optical crosslinks for shared timing and ephemeris data in support of enhanced constellation state estimation and reduced range error. The risks and value associated with these technologies are also discussed with an emphasis on challenges for aerospace.
相似文献9.
Lucas de Queiroz Salles Paulo Galvão Luiz Rogério Bastos Leal Ricardo Galeno Fraga de Araujo Pereira Carlos Gleidson Campos da Purificação Fernando Verassani Laureano 《Environmental Earth Sciences》2018,77(16):593
The morphological evolution of the karstic systems is associated with a set of physical and chemical processes, triggered by the dissolution of the rocks, related to percolation of groundwater and surface water, which consequently open underground voids and carve out peculiar forms of relief. Due to environmental and geotechnical aspects, this system is naturally more fragile and vulnerable than other natural systems and, therefore, has increasingly received the attention of the scientific community over the past decades. The objective of the study was to delimit zones with varying degrees of susceptibility for collapses and subsidence of sinkholes in the municipality of Iraquara, Chapada Diamantina (BA), Brazil, and to understand their geological and morphological determinant factors. Geological data, karst phenomenon map, and visual analysis in the field were used to categorize zones with different types of susceptibilities to the nucleation of new sinkholes based on a Hazard Index. This index was defined from the sum of geological hazard factors, lineament density, and sinkhole density. The areas that presented the highest susceptibility for terrain collapse and subsidence corresponded to regions where carbonate rocks outcrop, with high density of photolineaments and 2.62 sinkholes/km2. Processes associated with terrain collapse and subsidence in karst areas consisted of a combination of various factors, hindering precise predictions. However, zones of different types of susceptibilities to terrain collapse and subsidence can be delimited when the relationships between these processes and their factors are understood. The Hazard Index proposed does not provide quantitative values for the probability of hazard susceptibility, but rather indicates areas that are more susceptible to terrain subsidence and collapse. 相似文献
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