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Effect of a commercial dispersion of multi walled carbon nanotubes on the hydration of an oil well cementing paste

Frontiers of Structural and Civil Engineering 2016年第2期10卷 174-179页

作者： Ocar Aurelio MENDOZA rEALES William C. PEArL Jr Maria D. M. PAIVA Cristiane r. MIrANDA r.mildo dias toledo filho Civil Engineering Department PEC/COPPE Universidade Federal do Rio de Janeiro Rio de Janeiro 21941-972 Brazil Halliburton Brazil Technology Center Halliburton Rio de Janeiro 21941-907 Brazil CPetrobras Petroleo Brasileiro S.A Rio de Janeiro 21941-901 Brazil

This work studies the influence of a commercial dispersion of multi wall carbon nanotubes （MWCNT） on the hydration of a class G cement paste, at room and elevated down-hole temperatures. The MWCNT dispersion was produced with a solids concentration of 3.0 % by mass and an anionic surfactant as dispersing agent. Cement pastes with water-to-cement ratio of 0.45 and additions of solid MWCNT by mass of cement up to 0.50 % were studied. Isothermal calorimetry results showed a clear retardation of the hydration of cement caused by the surfactant contained in the MWCNT dispersion. Nevertheless, thermogravimetric evaluations showed that once the hydration reaction resumed, the retardation effect of the surfactant did not have a negative impact on the amount of hydration products precipitated. It was concluded that the commercial MWCNT dispersion presents a good potential to be applied in oil well cement pastes.

关键词： carbon nanotubes surfactant retardation combined water C-S-H

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Suiting Dynamic Models of Fixed-Bed Catalytic reactors for Computer-Based Applications

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Engineering（科研） 2011年第7期3卷 778-785页

作者： Eduardo Coselli Vasco de toledo Edvaldo rodrigo Morais Delba Nisi Cosme Melo Adriano Pinto Mariano Joao F.C.A.Meyer rubens Maciel filho Petrobras Paulínia Refinery(Replan)PaulíniaBrazil Laboratory of Optimization Design and Advanced ControlSchool of Chemical EngineeringUniversity of CampinasCampinasBrazil Institute of Mathematics Statisticsand Scientific ComputationUniversity of CampinasCampinasBrazil

This work investigated the applicability of heterogeneous and pseudo-homogeneous models to predict the dynamic behavior of a fixed-bed catalytic reactor. Some issues concerning the dynamic behavior of the system were discussed, such as the prediction of the inverse response phenomenon. The proposed models (Het- erogeneous I and II and Pseudo-homogeneous) were able to predict with qualitative similarity the main characteristics of the dynamic behavior of a fixed-bed catalytic reactor, including the inverse response. The computational time demanded for the solution of the heterogeneous models was 10 to 50% longer than in the case of the pseudo-homogeneous model, making the use of the former suitable for applications where computational time is not the major restriction (off-line applications). On the other hand, when on-line applications are required, the simplified model (Pseudo-homogeneous model) showed to be a good alternative because this model was able to predict (qualitatively) the dynamics of the reactor using a faster and easier numerical solution.

关键词： Dynamic Models Inverse response Fixed-Bed Catalytic reactors Simulation

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SMEArED CrACKING FEM SIMULATION OF ALKALI SILICA EXPANSION USING A NEW MACrOSCOPIC COUPLED MODEL

SMEARED CRACKING FEM SIMULATION OF ALKALI SILICA EXPANSION U...

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第十二届国际混凝土碱集料反应会议

作者： Eduardo M.r.Fairbairn Fernando L.B.ribeiro r.mildo D.toledo-filho Luciana E.Lopes Marcos M.Silvoso Marcia F.F.guas Quintiliano M.Guedes COPPE/The post-Graduate Engineering Institute Universidade Federal do Rio de JaneiroC.P.68506CEP 21945-970-Rio de Janeiro-RJ-Brasil COPPE/The post-Graduate Engineering Institute Universidade Federal do Rio de JaneiroC.P.68506CEP 21945-970-Rio de Janeiro-RJ-Brasil COPPE/The post-Graduate Engineering Institute Universidade Federal do Rio de JaneiroC.P.68506CEP 21945-970-Rio de Janeiro-RJ-Brasil COPPE/The post-Graduate Engineering Institute Universidade Federal do Rio de JaneiroC.P.68506CEP 21945-970-Rio de Janeiro-RJ-Brasil COPPE/The post-Graduate Engineering Institute Universidade Federal do Rio de JaneiroC.P.68506CEP 21945-970-Rio de Janeiro-RJ-Brasil FUrNAS Centrais Elétricas SA-DEC)-rua real Grandeza 219 CEP 22281-031-Rio de Janeiro-RJ-Brasil FUrNAS Centrais Elétricas SA-DEC)-rua real Grandeza 219 CEP 22281-031-Rio de Janeiro-RJ-Brasil

＜正＞ We present an ASr thermo-chemo-mechanical expansion model recently developed, whose main feature is the representation of the stress-induced anisotropy, which is taken into account by means of a classical smeared cracking model that was implemented in a 3D Finite Element code. This model considers the influence of temperature and humidity in the development of ASr. Since cracking occurs generally at the beginning of the swelling process, it is suggested that the assessment of the reaction characteristics in free expansion tests could be attained considering a cracked specimen. Hence, an inverse analysis is used to determine ASr parameters. Besides the validation of the model by the simulation of laboratory tests, it was applied to the simulation of alkali-silica expansion in a real gravity dam. We computed the displacements at the crest of the block comparing it with measures taken in the field for the last 25 years. The good correlation between experimental and numerical data displayed the accuracy of the model indicating its potentialities to engineering applications.

关键词： Alkali-silica reaction numerical modeling coupled model cracking

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Topographical Analysis of Frontal Lobe Executive Functions in Patients Following a Stroke

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World Journal of Neuroscience 2016年第2期6卷 143-150页

作者： roberta Márcia Torres Kristiana Cerqueira Mousinho Liércio Pinheiro Nathália Costa toledo Pacheco Piatti Taise Almeida Cavalcante Aline da Silva Amorim Ana Karolina Barros de Jesus Maria Wylianna Oliveira dos Santos Euclides Maurício Trindade filho University Center CESMAC Maceió Brazil

Objective: This study aimed to carry out a topographical analysis of frontal lobe executive function components in post-stroke patients. Methods: A descriptive, cross-sectional study. The assessment using the WCST (Wisconsin Card Sorting Test) included sixteen patients with a clinical diagnosis of CVA and frontal lobe impairment. results from the two groups were compared (patients with right frontal lobe impairment and patients with left frontal lobe impairment). Statistical analysis was performed using the program “Statistical Package for Social Sciences” (SPSS) Version 20.0. For comparison between groups was used Mann-Whitney test and considered the alpha level of 0.05 on the statistically significant results. results: There was no statistically significant difference between the groups, thus showing that executive functions are symmetrically distributed across the frontal lobes. Conclusion: Executive functions are symmetrically organized across the two frontal lobes, since the comparison between the groups did not demonstrate a statistically significant difference for any of the variables of WSCT.

关键词： Executive Function Stroke Frontal Lobe Neuropsychology

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