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Compressive strength prediction of CFRP confined concrete using data mining techniques
Aires Camões,Francisco F. Martins 사단법인 한국계산역학회 2017 Computers and Concrete, An International Journal Vol.19 No.3
During the last two decades, CFRP have been extensively used for repair and rehabilitation of existing structures as well as in new construction applications. For rehabilitation purposes CFRP are currently used to increase the load and the energy absorption capacities and also the shear strength of concrete columns. Thus, the effect of CFRP confinement on the strength and deformation capacity of concrete columns has been extensively studied. However, the majority of such studies consider empirical relationships based on correlation analysis due to the fact that until today there is no general law describing such a hugely complex phenomenon. Moreover, these studies have been focused on the performance of circular cross section columns and the data available for square or rectangular cross sections are still scarce. Therefore, the existing relationships may not be sufficiently accurate to provide satisfactory results. That is why intelligent models with the ability to learn from examples can and must be tested, trying to evaluate their accuracy for composite compressive strength prediction. In this study the forecasting of wrapped CFRP confined concrete strength was carried out using different Data Mining techniques to predict CFRP confined concrete compressive strength taking into account the specimens’ cross section: circular or rectangular. Based on the results obtained, CFRP confined concrete compressive strength can be accurately predicted for circular cross sections using SVM with five and six input parameters without spending too much time. The results for rectangular sections were not as good as those obtained for circular sections. It seems that the prediction can only be obtained with reasonable accuracy for certain values of the lateral confinement coefficient due to less efficiency of lateral confinement for rectangular cross sections.
Performance of Concrete in Aggressive Environment
Aguiar, Jose B.,Camoes, Aires,Moreira, Pedro M. Korea Concrete Institute 2008 International Journal of Concrete Structures and M Vol.2 No.1
Surface treatments act as a barrier between the environment and the concrete, preventing or retarding the entry of harmful substances and cutting off the transportation path into concrete. The effectiveness of a surface protection preventing the permeation depends on how close and strongly connected are the resin molecules. This work intends to contribute to a better understanding of the performance of protected concrete in chemically aggressive environments, by presenting results of ion diffusion and resistance to aggressive solutions of several hydrophobic agents and coatings used to protect concrete. Three different types of surface protections were tested: silicone hydrophobic agent, acrylic and epoxy coatings. The obtained results indicate that the overall performance of epoxy resin was better than the other selected types of protections.
Lima, Adriano Fonseca,Formaggio, Stephanie Ellen Ferreira,Zambelli, Ligia Franca Aires,Palialol, Alan Rodrigo Muniz,Marchi, Giselle Maria,Saraceni, Cintia Helena Coury,de Oliveira, Marcelo Tavares The Korean Academy of Conservative Dentistry 2016 Restorative Dentistry & Endodontics Vol.41 No.4
Objectives: In this study, we evaluated the influence of different radiant exposures provided by single-peak and polywave light-curing units (LCUs) on the degree of conversion (DC) and the mechanical properties of resin cements. Materials and Methods: Six experimental groups were established for each cement (RelyX ARC, 3M ESPE; LuxaCore Dual, Ivoclar Vivadent; Variolink, DMG), according to the different radiant exposures (5, 10, and $20J/cm^2$) and two LCUs (single-peak and polywave). The specimens were made (7 mm in length ${\times}$ 2 mm in width ${\times}$ 1 mm in height) using silicone molds. After 24 hours of preparation, DC measurement was performed using Fourier transform infrared spectrometry. The same specimens were used for the evaluation of mechanical properties (flexural strength, FS; elastic modulus, E) by a three-point bending test. Data were assessed for normality, after which two-way analysis of variance (ANOVA) and post hoc Tukey's test were performed. Results: No properties of the Variolink cement were influenced by any of the considered experimental conditions. In the case of the RelyX ARC cement, DC was higher when polywave LCU was used; FS and E were not influenced by the conditions evaluated. The LuxaCore cement showed greater sensitivity to the different protocols. Conclusions: On the basis of these results, both the spectrum of light emitted and the radiant exposure used could affect the properties of resin cements. However, the influence was material-dependent.
A Heart Rate Variability-based Smart Approach to Analyze Frailty in Older Adults
Joao Paulo do Vale Madeiro,Paulo Cesar Cortez,Arnaldo Aires Peixoto Junior,Joao Alexandre Lobo Marques,Antonio Alisson Pessoa Guimara,John Hebert da Silva Felix 한국산학기술학회 2015 SmartCR Vol.5 No.4
This paper presents an algorithm that applies metrics derived from automatic QRS detection and segmentation in electrocardiogram signals for analyzing Heart Rate Variability to study the evolution of metrics in the frequency domain of a clinical procedure. The analysis was performed on three sets of elderly people, who are categorized according to frailty phenotype. The first set was comprised of frail elderly, the second pre-frail elderly, and the third robust elderly. Investigators from many disciplines have been encouraged to contribute to the understanding of molecular and physiological changes in multiple systems that may increase the vulnerability of frail elderly. In this work, the frailty phenotype can be characterized by unintentional weight loss, as self-reported, fatigue assessed by self-report, grip strength (measured directly), physical activity level assessed by self-report and gait speed (measured). The results obtained demonstrate the existence of significant differences between Heart Rate Variability metrics for the three groups, especially considering a higher preponderance for sympathetic nervous system for the group of robust patients in response to postural maneuver.
Adriano Fonseca Lima,Stephanie Ellen Ferreira Formaggio,Ligia Franca Aires Zambelli,Alan Rodrigo Muniz Palialol,Giselle Maria Marchi,Cintia Helena Coury Saraceni,Marcelo Tavares de Oliveira 대한치과보존학회 2016 Restorative Dentistry & Endodontics Vol.41 No.4
Objectives: In this study, we evaluated the influence of different radiant exposures provided by single-peak and polywave light-curing units (LCUs) on the degree of conversion (DC) and the mechanical properties of resin cements. Materials and Methods: Six experimental groups were established for each cement (RelyX ARC, 3M ESPE; LuxaCore Dual, Ivoclar Vivadent; Variolink, DMG), according to the different radiant exposures (5, 10, and 20 J/cm2) and two LCUs (single-peak and polywave). The specimens were made (7 mm in length × 2 mm in width × 1 mm in height) using silicone molds. After 24 hours of preparation, DC measurement was performed using Fourier transform infrared spectrometry. The same specimens were used for the evaluation of mechanical properties (flexural strength, FS; elastic modulus, E) by a three-point bending test. Data were assessed for normality, after which twoway analysis of variance (ANOVA) and post hoc Tukey’s test were performed. Results: No properties of the Variolink cement were influenced by any of the considered experimental conditions. In the case of the RelyX ARC cement, DC was higher when polywave LCU was used; FS and E were not influenced by the conditions evaluated. The LuxaCore cement showed greater sensitivity to the different protocols. Conclusions: On the basis of these results, both the spectrum of light emitted and the radiant exposure used could affect the properties of resin cements. However, the influence was materialdependent.
Piyasan Praserthdam,Narongrat Poovarawan,Thidaya Thitiapichart,Kongkiat Suriye,Joongjai Panpranot,Wimonrat Limsangkass,Francisco José Cadete Santos Aires 한국화학공학회 2016 Korean Journal of Chemical Engineering Vol.33 No.1
Lanthanum (0.5, 0.6, 0.75, 0.9 and 1 wt%) was added as a second metal on the 9 wt% WO3/SiO2 catalysts by the incipient wetness impregnation method. The catalysts were tested in the metathesis reaction of ethylene and 2- butene using either pure 2% trans-2-butene and the mixture of 1% cis- and 1% trans-2-butene as the reaction feed and were characterized by X-ray diffraction (XRD), nitrogen physisorption (BET), inductively coupled plasma optical emission spectrometry (ICP-OES), scanning electron microscopy, ion-exchange titration, FT-Raman, ammonia temperature programmed desorption (NH3-TPD) and reactant temperature programmed desorption (reactant-TPD). An optimum lanthanum loading at 0.5 wt% could improve dispersion of tungsten active phase and adsorption properties of the reactants on the catalysts. The adsorption of the mixed cis/trans-2-butene isomer was much improved on the La- WO3/SiO2 catalysts with 0.5 wt% La.
do Nascimento Rafaela Andrade,Vieira Mariana Carmem Apolinário,Fernandes Juliana,Azevedo Ingrid Guerra,Moreira Mayle Andrade,Costa José Vilton,Câmara Saionara Maria Aires da,Maciel Álvaro Campos Caval 한국역학회 2022 Epidemiology and Health Vol.44 No.-
OBJECTIVES: This study analyzed the influence of anthropometric indices of adiposity on the physical performance of middle-aged and older women. METHODS: A cross-sectional study was conducted among 368 women from 50 years to 80 years old. Anthropometric and biochemical characteristics were analyzed, and physical performance was evaluated. The statistical analysis used measures of central tendency and dispersion for descriptive data, Pearson correlations to demonstrate the initial associations between the variables, and canonical correlation (CC) to evaluate the relationship between the set of anthropometric adiposity indices and performance-related variables. RESULTS: The participants had a mean age of 58.57± 8.21 years, a visceral adiposity index of 7.09± 4.23, a body mass index of 29.20 ± 4.94 kg/m2 , and a conicity index of 1.33 ± 0.07. The average handgrip strength was 25.06 ± 4.89 kgf, gait speed was 1.07± 0.23 m/s, and the mean Short Physical Performance Battery (SPPB) score was 10.83± 1.36. The first canonical function presented the highest shared variance, CC, and redundancy index (cumulative percentage of variance, 82.52; Wilks’ lambda, 0.66; CC, 0.532; p< 0.001). From the analysis of this canonical function, the conicity index (-0.59) displayed inverse correlations with handgrip strength (0.84) and the SPPB (0.68), as well as a direct correlation with gait speed (-0.43). CONCLUSIONS: In middle-aged and older women, there was an inverse relationship between the conicity index and muscle strength and power, while a direct relationship was found between the same index and gait speed.
In-situ surface analysis of AuPd(110) under elevated pressure of CO
Languille, M.A.,Ehret, E.,Lee, H.C.,Jeong, C.K.,Toyoshima, R.,Kondoh, H.,Mase, K.,Jugnet, Y.,Bertolini, J.C.,Aires, F.J.C.S.,Mun, B.S. Elsevier Science Publishers 2016 CATALYSIS TODAY - Vol.260 No.-
<P>With the combination of various in-situ surface science tools, surface chemical and structural properties of bimetallic AuPd(1 1 0) alloys are characterized under elevated CO pressure. Under 1 Torr of CO gas pressure, STM images show the formation of nano-sized surface rice-grains along the index direction of [1-10] while PM-IRRAS shows new CO vibrational band. This new vibrational band of PM-IRRAS is confirmed as the CO molecules attached to atop site of Pd with the results of ambient pressure XPS. In the case of adsorption of CO on AuPd(1 1 0) alloys, the so-called 'pressure gap' exists and the surface morphology and its chemical states change at elevated pressure conditions. (C) 2015 Elsevier B.V. All rights reserved.</P>