Simplified qualitative discrete numerical model to determine cracking pattern in brittle materials by means of finite element method

This paper presents the formulation, implementation, and validation of a simplified qualitative model to determine the crack path of solids considering static loads, infinitesimal strain, and plane stress condition. This model is based on finite element method with a special meshing technique, where nonlinear link elements are included between the faces of the linear triangular elements. The stiffness loss of some link elements represents the crack opening. Three experimental tests of bending beams are simulated, where the cracking pattern calculated with the proposed numerical model is similar to experimental result. The advantages of the proposed model compared to discrete crack approaches with interface elements can be the implementation simplicity, the numerical stability, and the very low computational cost. The simulation with greater values of the initial stiffness of the link elements does not affect the discontinuity path and the stability of the numerical solution. The exploded mesh procedure presented in this model avoids a complex nonlinear analysis and regenerative or adaptive meshes.Peer ReviewedPostprint (published version

Improving traffic-related air pollution estimates by modelling minor road traffic volumes

Accurately estimating annual average daily traffic (AADT) on minor roads is essential for assessing traffic-related air pollution (TRAP) exposure, particularly in areas where most people live. Our study assessed the direct and indirect external validity of three methods used to estimate AADT on minor roads in Melbourne, Australia. We estimated the minor road AADT using a fixed-value approach (assuming 600 vehicles/day) and linear and negative binomial (NB) models. The models were generated using road type, road importance index, AADT and distance of the nearest major road, population density, workplace density, and weighted road density. External measurements of traffic counts, as well as black carbon (BC) and ultrafine particles (UFP), were conducted at 201 sites for direct and indirect validation, respectively. Statistical tests included Akaike information criterion (AIC) to compare models’ performance, the concordance correlation coefficient (CCC) for direct validation, and Spearman’s correlation coefficient for indirect validation. Results show that 88.5% of the roads in Melbourne are minor, yet only 18.9% have AADT. The performance assessment of minor road models indicated comparable performance for both models (AIC of 1,023,686 vs. 1,058,502). In the direct validation with external traffic measurements, there was no difference between the three methods for overall minor roads. However, for minor roads within residential areas, CCC (95% confidence interval [CI]) values were − 0.001 (− 0.17; 0.18), 0.47 (0.32; 0.60), and 0.29 (0.18; 0.39) for the fixed-value approach, the linear model, and the NB model, respectively. In the indirect validation, we found differences only on UFP where the Spearman’s correlation (95% CI) for both models and fixed-value approach were 0.50 (0.37; 0.62) and 0.34 (0.19; 0.48), respectively. In conclusion, our linear model outperformed the fixed-value approach when compared against traffic and TRAP measurements. The methodology followed in this study is relevant to locations with incomplete minor road AADT data

Improving traffic-related air pollution estimates by modelling minor road traffic volumes

Accurately estimating annual average daily traffic (AADT) on minor roads is essential for assessing traffic-related air pollution (TRAP) exposure, particularly in areas where most people live. Our study assessed the direct and indirect external validity of three methods used to estimate AADT on minor roads in Melbourne, Australia. We estimated the minor road AADT using a fixed-value approach (assuming 600 vehicles/day) and linear and negative binomial (NB) models. The models were generated using road type, road importance index, AADT and distance of the nearest major road, population density, workplace density, and weighted road density. External measurements of traffic counts, as well as black carbon (BC) and ultrafine particles (UFP), were conducted at 201 sites for direct and indirect validation, respectively. Statistical tests included Akaike information criterion (AIC) to compare models' performance, the concordance correlation coefficient (CCC) for direct validation, and Spearman's correlation coefficient for indirect validation. Results show that 88.5% of the roads in Melbourne are minor, yet only 18.9% have AADT. The performance assessment of minor road models indicated comparable performance for both models (AIC of 1,023,686 vs. 1,058,502). In the direct validation with external traffic measurements, there was no difference between the three methods for overall minor roads. However, for minor roads within residential areas, CCC (95% confidence interval [CI]) values were -0.001 (-0.17; 0.18), 0.47 (0.32; 0.60), and 0.29 (0.18; 0.39) for the fixed-value approach, the linear model, and the NB model, respectively. In the indirect validation, we found differences only on UFP where the Spearman's correlation (95% CI) for both models and fixed-value approach were 0.50 (0.37; 0.62) and 0.34 (0.19; 0.48), respectively. In conclusion, our linear model outperformed the fixed-value approach when compared against traffic and TRAP measurements. The methodology followed in this study is relevant to locations with incomplete minor road AADT data

Improving construction processes of concrete building structures using load limiters on shores

This paper analyses the redistribution of maximum loads using a system of load limiters on shores in which the limiters yield at a given load and thus reduce the maximum load absorbed by the shores. For this analysis a finite element modelling (FEM) of an experimental building was developed in which load limiters had been fitted to the shores to restrict their maximum load to a given value. This was designed to: (a) optimise slab construction costs by using shores of lower load-bearing capacities, (b) improve safety during the construction of consecutive concrete slab floors by reducing maximum loads and redistributing loads amongst the shores; and (c) increase structural efficiency by more efficient use of the materials employed due to load redistribution. It has been estimated that using load limiters in this way can reduce total shoring costs in a building project by between 30% and 40%.The authors would like to express their gratitude to the Universitat Politecnica de Valencia for funding this research project (PAID-06-11) and also to the Encofrados J. Alsina Company for their invaluable cooperation.Buitrago Moreno, M.; Alvarado Vargas, YA.; Adam Martínez, JM.; Calderón García, PA.; Gasch, I.; Moragues, JJ. (2015). Improving construction processes of concrete building structures using load limiters on shores. Engineering Structures. 100:104-115. doi:10.1016/j.engstruct.2015.06.007S10411510

HyRA: A Hybrid Recommendation Algorithm Focused on Smart POI. Ceutí as a Study Scenario

Nowadays, Physical Web together with the increase in the use of mobile devices, Global Positioning System (GPS), and Social Networking Sites (SNS) have caused users to share enriched information on theWeb such as their tourist experiences. Therefore, an area that has been significantly improved by using the contextual information provided by these technologies is tourism. In this way, the main goals of this work are to propose and develop an algorithm focused on the recommendation of Smart Point of Interaction (Smart POI) for a specific user according to his/her preferences and the Smart POIs’ context. Hence, a novel Hybrid Recommendation Algorithm (HyRA) is presented by incorporating an aggregation operator into the user-based Collaborative Filtering (CF) algorithm as well as including the Smart POIs’ categories and geographical information. For the experimental phase, two real-world datasets have been collected and preprocessed. In addition, one Smart POIs’ categories dataset was built. As a result, a dataset composed of 16 Smart POIs, another constituted by the explicit preferences of 200 respondents, and the last dataset integrated by 13 Smart POIs’ categories are provided. The experimental results show that the recommendations suggested by HyRA are promising.Project (the SmartSDK project is co-funded by the EU’s Horizon2020 programme under agreement number 723174 - c 2016 EC and the CONACYT’s agreement number 737373) Doctorado IndustrialAdministración y Dirección de EmpresasIngeniería, Industria y ConstrucciónTurism

Quantifying Inactive Lithium in Lithium Metal Batteries

Inactive lithium (Li) formation is the immediate cause of capacity loss and catastrophic failure of Li metal batteries. However, the chemical component and the atomic level structure of inactive Li have rarely been studied due to the lack of effective diagnosis tools to accurately differentiate and quantify Li+ in solid electrolyte interphase (SEI) components and the electrically isolated unreacted metallic Li0, which together comprise the inactive Li. Here, by introducing a new analytical method, Titration Gas Chromatography (TGC), we can accurately quantify the contribution from metallic Li0 to the total amount of inactive Li. We uncover that the Li0, rather than the electrochemically formed SEI, dominates the inactive Li and capacity loss. Using cryogenic electron microscopies to further study the microstructure and nanostructure of inactive Li, we find that the Li0 is surrounded by insulating SEI, losing the electronic conductive pathway to the bulk electrode. Coupling the measurements of the Li0 global content to observations of its local atomic structure, we reveal the formation mechanism of inactive Li in different types of electrolytes, and identify the true underlying cause of low Coulombic efficiency in Li metal deposition and stripping. We ultimately propose strategies to enable the highly efficient Li deposition and stripping to enable Li metal anode for next generation high energy batteries

Immunology and Oxidative Stress in Multiple Sclerosis: Clinical and Basic Approach

Multiple sclerosis (MS) exhibits many of the hallmarks of an inflammatory autoimmune disorder including breakdown of the blood-brain barrier (BBB), the recruitment of lymphocytes, microglia, and macrophages to lesion sites, the presence of multiple lesions, generally being more pronounced in the brain stem and spinal cord, the predominantly perivascular location of lesions, the temporal maturation of lesions from inflammation through demyelination, to gliosis and partial remyelination, and the presence of immunoglobulin in the central nervous system and cerebrospinal fluid. Lymphocytes activated in the periphery infiltrate the central nervous system to trigger a local immune response that ultimately damages myelin and axons. Pro-inflammatory cytokines amplify the inflammatory cascade by compromising the BBB, recruiting immune cells from the periphery, and activating resident microglia. inflammation-associated oxidative burst in activated microglia and macrophages plays an important role in the demyelination and free radical-mediated tissue injury in the pathogenesis of MS. The inflammatory environment in demyelinating lesions leads to the generation of oxygen- and nitrogen-free radicals as well as proinflammatory cytokines which contribute to the development and progression of the disease. Inflammation can lead to oxidative stress and vice versa. Thus, oxidative stress and inflammation are involved in a self-perpetuating cycle

Patrones de participación y logro en un MOOC de Saberes Digitales para Docentes en servicio de México

Participation patterns and completion rates of a MOOC on Digital Knowledge for Teachers with over 8000 students were investigated in this article using descriptive statistics and cluster analysis according to age, gender and previous educational attainment. Results indicate that older and more educated participants obtained higher completion rates and employed more often the discussion forum. No gender differences were obtained. Participation in the course followed a funnel model in which there is a steep decrease of involvement after the first activity which stabilizes in the fifth one. The course rested on a basis of trust assuming that each participant voluntarily enrolled with the purpose of learning and therefore considering his/her self-perception of course performance as one element of overall appraisal is consistent with these courses

"Bioadsorption of silver ions by calcareous chitin, chitin and chitosan"

"Context: Calcareous chitin, chitin, chitosan, and their modifications are used as bioadsorbents of metals and dyes that cause environmental pollution, endocrine disruption, and human diseases. Aims: To evaluate the selective bioadsorption of silver ions (Ag+ ) by calcareous chitin, chitin, and chitosan. Methods: Experimental and prospective study. The presence of functional groups of the bioadsorbents was identified by Fourier-transformed infrared spectroscopy (FT-IR), 1H-NMR spectroscopy and scanning electron microscopy (SEM). The Langmuir, Freundlich, and Elovich models were applied to describe the adsorption capacity of bioadsorbents according to granule size (20-40, 40-60, 60-80 meshes) and temperature (10, 20, and 30°C). Results: The FT-IR spectrum of calcareous chitin indicates the presence of carbonate (CO3 = 1420 cm-1 ), amide III (1313 cm-1 ), –OH groups (3441.90 cm-1 ), and pyranose structure (952.83 cm-1 ); chitin has –OH groups (3441.90 cm-1 ), NH (3268 cm-1 ), amide I (1654 cm-1 ) and II (1559 cm-1 ); chitosan has –OH groups (3419.90 cm-1 ), –NH (3200 cm-1 ), amide I (1712.18 cm-1 ), –NH2 (1654.46 cm-1 ), amide III (1317.11 cm-1 ) and pyranose structure (1070.12 cm-1 and 1031 cm-1 ). The Langmuir model indicates greater bioadsorption of Ag+ ions at smaller particle sizes (60-80 = 0.25-0.18 mm) and at a temperature of 20-30°C. Conclusions: The bioadsorption of silver ions (Ag+ ) by chitosan is greater with respect to calcareous chitin and chitin; the Langmuir model fits for the Ag+ isotherm and suggests that the process is controlled by physisorption.

Estadodel Arteen La Ciencia y Tecnología Para La Produccióny Procesamiento Dejatrophano Tóxica / State of Art on Science and Technology for Production and Processing of Non-Toxic Jatropha Compiladores

Ecología y etnobotánica de Jatropha curcas L. no tóxica Ecology and ethnobotany of non-toxic Jatropha curcas L. Odilón Manuel Sánchez-Sánchez, Ofelia Andrea Valdés-Rodríguez, Diana Estela Sánchez-Herrera 1 Buscando los orígenes de la Jatropha curcas L. no tóxica Searching for the oirigin or non-toxic Jatropha curcas L. Ofelia Andrea Valdés-Rodríguez, Odilón Sánchez-Sánchez, Modesto Castillo-Guerrero 12 Producción de semilla de Jatropha curcas L.: elementos clave Jatropha curcas sedd production: key elements Leobigildo Córdova-Téllez, José Trinidad Zavala-Hernández, Edgardo Bautista-Ramírez, Ma. del Rosario Martínez-Sánchez y Nancy Yazmín Hernández-Nicolás 19 Marcadores moleculares: herramienta para el mejoramiento genético de Jatropha curcas L. Molecular markers: a tool for the genetic improvement of Jatropha curcas L. Víctor Pecina Quintero, Jose Luis Anaya Lopez, Noé Montes García, Carlos Herrera Corredor 29 Comportamiento agronómico, energético y emisiones de gases de piñón mexicano (Jatropha curcas L.) Agonomic, energetic and gas emission behavior of mexican pine nut (Jatropha curcas L.) José Luis Solís Bonilla, Víctor Pecina Quintero, Ana Laura Reyes Reyes, Biaani Beeu Martínez Valencia, Alfredo Zamarripa Colmenero, Lexi Javivi López Ángel, Enrique Riegelhaupt, Guillermo López Guillen y Edwin Javier Barrios Gómez 39 Principales plagas y enfermedades del piñón (Jatropha curcas L.) Jatropha’s (Jatropha curcas L.) main pests and diseases Guillermo López-Guillén, Jaime Gómez-Ruiz, Juan Francisco Barrera Gaytán, Misael Martínez Bolaños, Elizabeth de los Ángeles Herrera Parra, Marianguadalupe Hernández Arenas, Ana Laura Reyes Reyes, José Luis Solís Bonill