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作者： Neves, Alex Toledo Filho, Romildo Dias Dweck, Jo Fairbairn, Eduardo De Moraes Rego Federal University of Mato Grosso UFMT Cuiabá Brazil Civil Engineering Program COPPE Federal University of Rio de Janeiro Brazil School Chemistry Federal University of Rio de Janeiro Brazil

After submitted to early age carbonation curing, mechanical and physical properties of high initial strength sulfate resistant Portland cement (HS SR PC) pastes were investigated, which were compared to those of non-carbonated reference pastes. Carbonation was performed for 1 and 24 hours, at the best conditions of CO2 capturing, previously determined by the authors. Despite the compressive strength and elastic modulus of the 1h carbonated pastes were slightly higher than those of the reference pastes, their absorbed water content and porosity was slightly higher than that of the reference. In the case of 24h carbonation, its compressive strength decreases significantly because of its much higher porosity, although the new solid carbonated calcium silicate phase presents a much higher specific mass than those of the solid phases of the 1 hour and non-carbonated pastes. © (2015) Trans Tech Publications, Switzerland.

关键词： Carbonation

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Durability of lightweight slurries for oilwell cementing 8th

Durability of lightweight slurries for oilwell cementing

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8th International Conference on Concrete under Severe Conditions - Environment and Loading, CONSEC 2016

作者： Balthar, Vivian Karla Castelo Branco Louback Machado Filho, Romildo Dias Toledo De Moraes Rego Fairbairn, Eduardo De Miranda, Cristiane Richard Department of Structures FAU/ Universidade Federal Do Rio de Janeiro Avenida Pedro Calmon 550 Cidade Universitária Rio de Janeiro-RJ Brazil Program of Civil Engineering COPPE Universidade Federal Do Rio de Janeiro P.O. Box 68506 CEP Rio de Janeiro-RJ21941-972 Brazil Centro de Pesquisas e Desenvolvimento P and D em Geoengenharia Engenharia de Poço Perfuração e Completação de Poços CENPES/Petrobras Avenida Horacio de Macedo 3324 Cidade Universitaria Rio de Janeiro-RJ Brazil

ISBN: (纸本)9783035710441

In a deepwater environment, unconsolidated formations at seabed and naturally fractured carbonates at reservoir zones with high permeability are commonly found. In this context, the use of lightweight slurries is necessary to effectively cementing these formations, in order to mitigate slurry losses to the formations and to prevent their fracture. This work investigates the mechanical properties and durability of high performance lightweight slurries to be used in this environment. The mixtures were formulated within the framework of the Compressible Packing Model and were extended using hollow ceramic or glass microspheres. Tests were carried out to determine the slurries apparent density, rheology, free fluid, sedimentation, fluid loss, resistance to acid attack, sorptivity and total water absorption. A mechanical characterization was performed by uniaxial and triaxial compression and splitting tensile strength tests and were correlated with the durability tests. The reference slurry, extended with bentonite, presented a 1.46 g/cm3 density and compressive strength of 3 MPa (cure at 27°C/ 2.7 days). The slurries containing glass and ceramic microspheres were slightly lighter and presented a higher mechanical performance as compared to ordinary slurry. Besides, these mixtures presented a higher resistance to acid attacks and lower sorptivity, especially the lightweight slurry containing ceramic microspheres. © 2016 Trans Tech Publications, Switzerland.

关键词： Slurries

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A KNN Undersampling Approach for Data Balancing

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Journal of Intelligent Learning Systems and Applications 2015年第4期7卷 104-116页

作者： Marcelo Beckmann Nelson F. F. Ebecken Beatriz S. L. Pires de Lima Civil Engineering Program/COPPE Federal University of Rio de Janeiro Rio de Janeiro Brazil

In supervised learning, the imbalanced number of instances among the classes in a dataset can make the algorithms to classify one instance from the minority class as one from the majority class. With the aim to solve this problem, the KNN algorithm provides a basis to other balancing methods. These balancing methods are revisited in this work, and a new and simple approach of KNN undersampling is proposed. The experiments demonstrated that the KNN undersampling method outperformed other sampling methods. The proposed method also outperformed the results of other studies, and indicates that the simplicity of KNN can be used as a base for efficient algorithms in machine learning and knowledge discovery.

关键词： Machine Learning Class Overlaping Imbalanced Datases

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Fuzzy inference about wind resources in urban environment 3

Fuzzy inference about wind resources in urban environment

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3rd International Workshop on Simulation for Energy, Sustainable Development and Environment, SESDE 2015

作者： Moreira, Marcos Antonio Cruz Rosenhaim, Roberto Santos, Robson Da Cunha Cunha, Gerson Gomes De Araújo Holanda, Thaiane Fagundes Fluminense Federal Institute Automation and Control Engineering Environmental Engineering Program Macaé Brazil Fluminense Federal Institute Automation and Control Engineering Macaécio Brazil Control Engineering Department Federal Institute and Estacio de Sá University Cabo Frio Brazil Alberto Luiz Coimbra Institute Graduate Engineering and Research Civil Engineering Program/COPPE/UFRJ Federal University of Rio de Janeiro Brazil Fluminense Federal University Macaécio Brazil

ISBN: (纸本)9788897999522

The advancement of renewable energy technology gave rise to the implementation of small wind towers in urban areas. A major problem in predicting the use of such facilities is the difficulty of measuring in micro-regions that suffer different influences of the surrounding environment. Thus a wind tower may be installed where it does not work properly. Fuzzy inference systems try to approach the thinking process of human language allowing for a more assertive decision process. For the development of a fuzzy inference system dealing with this issue it was necessary to determine the variables that most impact on the variation of the wind distribution in micro urban environment as well as using data from automatic weather stations which allow to estimate the wind regime for a macro region. These data are fed in a fuzzy inference system that outputs an adequacy rank for sitting a small wind tower.

关键词： Wind power

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Multivariate Analysis of Extreme Physical, Biological and Chemical Patterns in the Dynamics of Aquatic Ecosystem

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Journal of Environmental Protection 2015年第8期6卷 885-901页

作者： Marilia Mitidieri Fernandes de Oliveira Gilberto Carvalho Pereira Nelson Francisco Favilla Ebecken Jorge Luiz Fernandes de Oliveira Center of Technology Federal University of Rio de Janeiro-Civil Engineering Postgraduate Program-COPPE/UFRJ Rio de Janeiro Brazil Geography Postgraduate Program Geoscience Institute of Fluminense Federal University-UFF Niterói Brazil

This study is a part of the research in monitoring systems of environmental impacts in coastal re-gions in order to develop trophic dynamic models to be used in the aquatic systems management. Meteorological influences in the variability of the nutrients, larvae concentration, dissolved oxygen (DO) and chlorophyll a were investigated in a region where upwelling occurs. Extreme seasonal variations of reanalysis, QuikSCAT, and surface stations from the southeast coast of Brazil, as well as, surface seawater data collected in Anjos Bay, Arraial do Cabo city northeast of Rio de Janeiro state, are analyzed. Seasonality and correlations are applied to verify the relationship between them, considering minimum values of sea surface temperature (SST) and sea level variation and maximum values of the other variables. Principal Component Analysis (PCA) and Hierarquical Cluster Analysis (HCA) are applied to verify spatial and temporal variances and to describe more clearly the structure of the local ecosystem. The seasonality of northeasterly extreme wind stress follows the seasonal pattern expected for the study area with peaks during spring. The SST has a well-defined seasonal pattern with maximum peaks from February to July and minimum peaks from September to January. Chlorophyll a presents higher seasonal peak in February, being in accordance with DO;both are related to the maximum primary productivity. Correlations of the physical variables (local and remote) with nutrients and larvae present a relatively similar pattern around 0.5, showing these variables have a reasonable interaction with the meteorological forcing. PCA shows a strong variability in pressure data around 0.9, which may be related to the seasonal variations in South Atlantic subtropical anticyclone (SASA) and consequently to the occurrence of upwelling in the region. HCA shows the twenty-five parameters into two big clusters with predominance of biotic variables in one side and abiotic ones at the other. T

关键词： Larvae Nutrient Concentrations Coastal Waters Brazil Upwelling

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Influence of sodium and potassium chlorides on the hydration kinetics and its impact on the strength of oil well cement pastes

Influence of sodium and potassium chlorides on the hydration...

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The 14th International Congress on the Chemistry of Cement（ICCC 2015）

作者： C.A.A.Rocha G.C.Cordeiro R.D.Toledo Filho Civil Engeenering Program-PEC Universidade Federal do Rio de Janeiro-COPPE/UFRJ Civil Engineering Laboratory-LECIV Universidade Estadual do Norte Fluminense Darcy Ribeiro-UENF

In mis paper,the hydration process of Portland cement with NaCl and KCl addition was studied by isothermal calorimeter,ultrasonic method and compressive *** were designed containing 5%,10%,15%,20%and 36%NaCl by the weight of water（BWOW）,and 5%,10%,15%,20%and 34%KCl（BWOW） and water to cement ratio of *** results of these tests were correlated with the amount of the formed hydration products obtained by thermogravimetric analysis and the compressive *** addition of NaCl up to 15%accelerated the hydration reactions at the first *** the other hand,20 and 36%of NaCl addition delayed the hydration *** older ages,all pastes with NaCl addition had their reactions delayed;it directly influenced the amount of formed products and the compressive *** KCl addition accelerated the hydration reactions at the first ages,with exception of paste containing 34%*** addition of KCl have not significantly influenced the amount of the formed products and mechanical properties at long *** Cement paste is placed in an annular space between the case and borehole wall during the oilfield drilling operations to isolate different permeable *** cementing of salt rock domes,the produced cement pastes,sometimes,have addition of some salt to avoid the migration of rock salt to the cement *** salt can alter many properties of cement paste,including hydration behavior,and it has been long understood by *** properties required of the fresh saline paste,such as thickening time,rheology,fluid loss,and free fluid differ greatly depending of the salt concentration from that ordinary *** also changes the mechanical strength of the hardened paste in different ways depending on the salt ***,the effect of the NaCl and KCl addition on the hydration process is still not entirely known and little research about this theme can be found in the ***,in this paper,we propose to stud

关键词： Hydration kinetics Strength NaCl KCl Oil well cement pastes

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Optimization of open cold-formed steel sections based on shape grammar

Optimization of open cold-formed steel sections based on sha...

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Structural Stability Research Council Annual Stability Conference 2014, SSRC 2014

作者： Franco, J.M.S. Batista, E.M. Landesmann, A. Civil Engineering Program COPPE Federal University of Rio de Janeiro Brazil

ISBN: (纸本)9781632667106

The main goal of the present research is to find innovative and appropriate CFS shapes, improving its structural behavior at the same time that are manufacturable and, if possible, cost saving. Open cold-formed steel sections (CFS) optimization is obtained by integration of four investigation fields: (i) modeling the search domain, (ii) designing the fitness functions, (iii) applying Artificial Intelligence and (iv) computational implementation and visualization integrates the three other investigation fields. The paper focuses innovative application of Shape Grammar formalism, addressed to easy modeling of feasible CFS sections. The original developed algorithm is identified as CFS-Language - composed by a set of sentences translating each step of manufacturing by cold-forming - which was combined with Genetic Algorithm in order to select adequate shape, in accordance with previously selected objectives (Pareto's Front). The results of the analysis for three fitness functions are presented: (i) axial compression and (ii) flexural strength with the help of the Direct Strength Method and (iii) manufacturing costs. CFS-language was firstly developed in a CAD platform, further translated to MATLAB code and finally integrated with GA procedure inside the open-source code CUFSM (v.4.0.5) for buckling analysis based on constrained finite strip method. Based on the above described methodology, CFS shapes were generated by combining fitness functions and geometric modeling algorithms through Genetic Algorithm. The paper presents in detail the developed CFS-language, shows how the computational algorithms were integrated and finally presents the results of illustrative examples.

关键词： Genetic algorithms

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A comparative study between the early stages hydration of a high strength and sulphate resistant portland cement and the type II F Portland cement through non conventional differential thermal analysis and thermogravimetry

A comparative study between the early stages hydration of a ...

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作者： Junior, Alex Neves Viana, Marcelo Mendes Dweck, Jo Filho, Romildo Dias Toledo College of Architecture Engineering and Technology-FAET Universidade Federal Do Mato Grosso-UFMT Av. Fernando Corrêa da Costa 2367 Bairro Boa Esperança CEP Cuiabá MT78060-900 Brazil School of Chemistry Universidade Federal Do Rio de Janeiro-UFRJ Bloco E do CT sala E206 CEP Rio de Janeiro RJ21949-900 Brazil Civil Engineering Program COPPE Universidade Federal Do Rio de Janeiro-UFRJ NUMATS CEP Rio de Janeiro RJ21949-900 Brazil

This work presents a study, which compares the early stages of hydration of a High Initial Strength and Sulphate Resistant Portland Cement (HIS SR PC) with those of Type II F Portland Cement (PC II), by Non-Conventional Differential Thermal Analysis (NCDTA) within the first 24 hours of hydration. Water/cement (w/c) ratios equal to 0.5, 0.6 and 0.66 were used to prepare the pastes. The hydration of these two types of cement was monitored on real time by NCDTA curves, through the thermal effects of the hydration reactions, from which cumulative evolved energy curves were obtained. These techniques allow one to analyse the influence of each type of cement on the main stages that occur during the hydration process. Thermogravimetric analysis were also performed at 4 and 24h of hydration for both cements, to analyse the influence of each kind of cement on the amount of the main formed hydrated products. The results showed that with 4h of hydration, the total combined water amount released from the hydrated products was higher for the PC II pastes than for the HIS SR PC pastes. Otherwise, with 24h of hydration, the amount of the total combined water released from the hydrated products was higher for the HIS SR PC pastes than for the PC II pastes.

关键词： Thermogravimetric analysis

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Cold-formed steel lipped channel beams under fire conditions: Distortional response, failure and DSM design

Cold-formed steel lipped channel beams under fire conditions...

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Structural Stability Research Council Annual Stability Conference 2014, SSRC 2014

作者： Landesmann, A. Camotim, D. Civil Engineering Program COPPE Federal University of Rio de Janeiro Brazil Civil Engineering Department ICIST University of Lisbon Portugal

ISBN: (纸本)9781632667106

The aim of this paper is to report an ongoing shell finite element investigation on the distortional post-buckling behavior, ultimate strength and design of cold-formed steel single-span lipped channel beams subjected to elevated temperatures caused by fire conditions. The beam ultimate strengths are computed by means of a steady-state loading strategy that consists of applying an increasing major-axis uniform bending moment to a beam under a uniform (elevated) temperature distribution, in order to obtain the corresponding failure moments). The steel constitutive law at elevated temperatures is simulated by means of the stress-strain-temperature models prescribed in EC3-1.2 for cold-formed steel. The materially and geometrically non-linear response of the cold-formed lipped channel beams is determined by means of ANSYS non-linear shell finite element analyses that incorporate critical-mode initial geometrical imperfections. Finally, since there are no specific rules to predict the bending strength of cold-formed steel beams failing distortionally when subjected to elevated temperatures, the above failure moments and temperature values will be used to establish guidelines for the design of cold-formed steel lipped channel beams under fire conditions. The approach followed is based on the increasingly popular Direct Strength Method, already employed by other researchers (e.g., Ranawaka and Mahendran 2009b) - the currently available design/strength equations/curves, developed for ambient temperature, are modified to account for the appropriate Young's modulus and yield stress reductions due to the temperature increase.

关键词： Yield stress

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Influence of sodium and potassium chlorides on the hydration kinetics and its impact on the strength of oil well cement pastes

Influence of sodium and potassium chlorides on the hydration...

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The 14th International Congress on the Chemistry of Cement (ICCC 2015)第14届国际水泥化学大会

作者： C.A.A.Rocha G.C.Cordeiro R.D.Toledo Filho Civil Engeenering Program-PEC Universidade Federal do Rio de Janeiro-COPPE/UFRJ Rio de JaneiroRJ Brazil Civil Engineering Laboratory-LECIV Universidade Estadual do Norte Fluminense Darcy Ribeiro-UENF Campos dos Goytacazes RJ Brazil

In this paper, the hydration process of Portland cement with NaCl and KCl addition was studied by isothermal calorimeter, ultrasonic method and compressive *** were designed containing 5%, 10%, 15%, 20% and 36% NaCl by the weight of water (BWOW), and 5%, 10%, 15%, 20% and 34% KCl (BWOW) and water to cement ratio of *** results of these tests were correlated with the amount of the formed hydration products obtained by thermogravimetfic analysis and the compressive *** addition of NaCl up to 15% accelerated the hydration reactions at the first *** the other hand, 20 and 36% of NaCl addition delayed the hydration *** older ages, all pastes with NaCl addition had their reactions delayed;it directly influenced the amount of formed products and the compressive *** KCl addition accelerated the hydration reactions at the first ages, with exception of paste containing 34% *** addition of KCl have not significantly influenced the amount of the formed products and mechanical properties at long periods.

关键词： Hydration kinetics Strength NaCl KCl Oil well cement pastes

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