Preliminary study on the performance of biomorphic silicon carbide as substrate for diesel particulate filters

This paper presents the results of a preliminary experimental study to assess the performance of biomorphic silicon carbide when used for the abatement of soot particles in the exhaust of Diesel engines. Given its optimal thermal and mechanical properties, silicon carbide is one of the most popular substrates in commercial diesel particulate filters. Biomorphic silicon carbide is known for having, besides, a hierarchical porous microstructure and the possibility of tailoring that microstructure through the selection of a suitable wood precursor. An experimental rig was designed and built to be integrated within an engine test bench that allowed to characterizing small lab-scale biomorphic silicon carbide filter samples. A particle counter was used to measure the particles distribution before and after the samples, while a differential pressure sensor was used to measure their pressure drop during the soot loading process. The experimental campaign yielded promising results: for the flow rate conditions that the measuring devices imposed (1 litre per minute; space velocity = 42,000 L/h), the samples showed initial efficiencies above 80%, pressure drops below 20 mbar, and a low increase in the pressure drop with the soot load which allows to reach almost 100% efficiency with an increase in pressure drop lower than 15%, when the soot load is still less than 0.01 g/L. It shows the potential of this material and the interest for advancing in more complex diesel particle filter designs based on the results of this workMinisterio de Economía y Competitividad (España) MAT2013-41233-R DPI2013-46485-C3-3-RFondos FEDER MAT2013-41233-R DPI2013-46485-C3-3-RUniversidad de Sevilla VI Plan Propio I.3B - C.I. 24/05/2017 MAT2016-76526-

Space-Time Fractional Diffusion-Advection Equation with Caputo Derivative

An alternative construction for the space-time fractional diffusion-advection equation for the sedimentation phenomena is presented. The order of the derivative is considered as 0<β, γ≤1 for the space and time domain, respectively. The fractional derivative of Caputo type is considered. In the spatial case we obtain the fractional solution for the underdamped, undamped, and overdamped case. In the temporal case we show that the concentration has amplitude which exhibits an algebraic decay at asymptotically large times and also shows numerical simulations where both derivatives are taken in simultaneous form. In order that the equation preserves the physical units of the system two auxiliary parameters σx and σt are introduced characterizing the existence of fractional space and time components, respectively. A physical relation between these parameters is reported and the solutions in space-time are given in terms of the Mittag-Leffler function depending on the parameters β and γ. The generalization of the fractional diffusion-advection equation in space-time exhibits anomalous behavior

A transform based local RBF method for 2D linear PDE with Caputo–Fabrizio derivative

The present work aims to approximate the solution of linear time fractional PDE with Caputo Fabrizio derivative. For the said purpose Laplace transform with local radial basis functions is used. The Laplace transform is applied to obtain the corresponding time independent equation in Laplace space and then the local RBFs are employed for spatial discretization. The solution is then represented as a contour integral in the complex space, which is approximated by trapezoidal rule with high accuracy. The application of Laplace transform avoids the time stepping procedure which commonly encounters the time instability issues. The convergence of the method is discussed also we have derived the bounds for the stability constant of the differentiation matrix of our proposed numerical scheme. The efficiency of the method is demonstrated with the help of numerical examples. For our numerical experiments we have selected three different domains, in the first test case the square domain is selected, for the second test the circular domain is considered, while for third case the L-shape domain is selected

A transform based local RBF method for 2D linear PDE with Caputo–Fabrizio derivative

The present work aims to approximate the solution of linear time fractional PDE with Caputo Fabrizio derivative. For the said purpose Laplace transform with local radial basis functions is used. The Laplace transform is applied to obtain the corresponding time independent equation in Laplace space and then the local RBFs are employed for spatial discretization. The solution is then represented as a contour integral in the complex space, which is approximated by trapezoidal rule with high accuracy. The application of Laplace transform avoids the time stepping procedure which commonly encounters the time instability issues. The convergence of the method is discussed also we have derived the bounds for the stability constant of the differentiation matrix of our proposed numerical scheme. The efficiency of the method is demonstrated with the help of numerical examples. For our numerical experiments we have selected three different domains, in the first test case the square domain is selected, for the second test the circular domain is considered, while for third case the L-shape domain is selected

Fractional RC and LC Electrical Circuits

AbstractIn this paper we propose a fractional differential equation for the electrical RC and LC circuit in terms of the fractional time derivatives of the Caputo type. The order of the derivative being considered is 0<γ<1. To keep the dimensionality of the physical parameters R, L, C the new parameter a is introduced. This parameter characterizes the existence of fractional structures in the system. A relation between the fractional order time derivative γ and the new parameter σ is found. The numeric Laplace transform method was used for the simulation of the equations results. The results show that the fractional differential equations generalize the behavior of the charge, voltage and current depending of the values of γ. The classical cases are recovered by taking the limit when γ=1. An analysis in the frequency domain of an RC circuit shows the application and use of fractional order differential equations

Visual analytics in e-learning

Current technologies used in e-learning  processes require the logging of all activities performed. These data can be used in the assessment of students, instructors and the processes themselves. However, although this wealth of data exists, it is still difficult for those who teach (and interested stakeholders) to verify a hypothesis, extract conclusions, or make decisions based on the facts or situations that are discovered. This paper introduces an educational data analysis model based on visual analytics, learning analytics and academic analytics and using a software tool that allows performing confirmatory and exploratory data analysis through interaction with the information gathered from a typical Learning Management System. The main goal is to enable the discovery of knowledge on the specific learning process that, in turn, will permit its improvement

Modelo de sobrealimentación para motores de combustión interna alternativos

En este trabajo se muestra un modelo mediante el cual se pretende la caracterización del comportamiento e interacción de un grupo de turbosobrealimentación acoplado a un motor de combustión interna alternativo de cuatro tiempos. El modelo empleado para el grupo de sobrealimentación ha sido desarrollado buscando la compatibilidad del mismo con herramientas numéricas basadas en modelos de acción de ondas para la simulación de flujos en los conductos de admisión y escape, previamente desarrolladas por los autores. El modelo del grupo de sobrealimentación ha mostrado una buena adaptación tanto en las zonas de funcionamiento normal de las turbomáquinas como ante situaciones de bloqueo, inversión de flujo o bombeo, presentes dada la naturaleza oscilante del flujo en las secciones de entrada y salida de las mismas. Tras un proceso de validación del mismo se ha aplicado el código modificado incluyendo el modelo de grupo de sobrealimentación a una serie de configuraciones de MCIA determinadas.In this work a turbocharging system is modeled and integrated within a previously developed numerical tool in order to simulate reciprocating internal combustion engines. The turbocharging model has been tested and applied to a four strokes, four cylinders internal combustion engine model showing the effects of turbocharging in different parameters

An Ex Vivo Model in Human Femoral Heads for Histopathological Study and Resonance Frequency Analysis of Dental Implant Primary Stability

Objective. This study was designed to explore relationships of resonance frequency analysis (RFA)—assessed implant stability (ISQ values) with bone morphometric parameters and bone quality in an ex vivo model of dental implants placed in human femoral heads and to evaluate the usefulness of this model for dental implant studies. Material and Methods. This ex vivo study included femoral heads from 17 patients undergoing surgery for femoral neck fracture due to osteoporosis (OP) ( ) or for total prosthesis joint replacement due to severe hip osteoarthrosis (OA) ( ). Sixty  mm Dentsply Astra implants were placed, followed by RFA. CD44 immunohistochemical analysis for osteocytes was also carried out. Results. As expected, the analysis yielded significant effects of femoral head type (OA versus OA) ( ), but not of the implants ( ) or of the interaction of the two factors ( ). Bonferroni post hoc comparisons showed a lower mean ISQ for implants in decalcified ( ) heads than in fresh ( ) or fixated ( ) heads (both ). The ISQ score (fresh) was significantly higher for those in OA ( ) versus OP ( ) heads. However, mixed linear analysis showed no significant association between ISQ scores and morphologic or histomorphometric results ( in all cases), and no significant differences in ISQ values were found as a function of the length or area of the cortical layer (both ). Conclusion. Although RFA-determined ISQ values are not correlated with morphometric parameters, they can discriminate bone quality (OP versus OA). This ex vivo model is useful for dental implant studies.This investigation was partially supported by Research Group no. CTS-138 (Junta de Andalucía, Spain)

Probabilistic Agent Based Model for Tumoral Cells, and 3D Model For Angiogenesis

The study of tumoral cells behaviour through computational models is arising. The movement of these cells is governed by physical laws; therefore, the different forces exerted between them need to be implemented. Nevertheless, biological criteria should be also considered since other factors, as oxygen level or cellular density, are decisive in the real movement. These phenomena are captured by probabilistic models such as the Agent Based Model (ABM). Following this research line, the present paper outlines a numerical model that tries to join both criteria with the aim of reproducing the behaviour of the cells that are part of a brain tumor: Glioblastoma Multiforme (GBM). The study has been carried out by the implementation of the different force equations in a Smoothed-Particle Hydrodynamic (SPH) framework. The SPH method is a meshfree lagrangian method based on the discretization of the study domain into finite particles which carry their own information, as tumoral cells do. Cohesive, viscous and pressure forces have been taking into account. Also, the possible attraction or repulsiveness between cells is considered through the implementation of a mechanical force formulation that combines the Maxwell and KelvinVoigt viscoelastic models. In addition to this forces approach, an energetic model is proposed to consider the results provided by an ABM. It evaluates the energy consumption and the associated extra-force that the cell needs to reach the ABM position, which is considered the biologically optimal one. The model has been tested under different sets of parameters, getting the logical outcome. Successful results have also been found in the evaluation of the energy consumption and, therefore, of the extra-force, finding a formulation that joins both criteria

Experimental Techniques to Measure Hypnotic Levels During Surgery

[Abstract] The administration of anesthetics during a surgical procedure has been done historically in a manual way with the anesthesiologist deciding what amounts and at what rates to use. Over the last few decades there has been a rapid increase in the automation of many medical areas including anesthesiology, with that increased level of automation have also appeared new ways to measure the level of sedation in patients. Historically, one of the most frequently index used has been the BIS, which has proven rather reliable as an indicator. More recently, another index called PSI has attracted interest of practitioners. In this article a comparison of these two indexes was performed. Data recording BIS and PSI values from surgical operations for several patients were collected and analyzed. The results seem to indicate that it is to be expected that in 95% of the cases the correlation between the BIS and PSI index will be at least 0.6866.This work has been supported by the grant DPI2010-18278 of the Spanish Governmenthttps://doi.org/10.17979/spudc.978849749808