Turing patterns formation on surfaces under deformation: A total lagrangian method approach

En este artículo se desarrollan varios ejemplos numéricos sobre ecuaciones de reacción-difusión con dominio creciente. Para este fin se utiliza el modelo de reacción de Schnakenberg, con parámetros en el espacio de Turing. Por tanto se realizan ensayos numéricos sobre la aparición de los patrones de Turing en superficies que tienen alta tasa de deformación. Para la solución de las ecuaciones de reacción difusión se presenta un método de solución en superficies en 3 dimensiones mediante el método de los elementos finitos bajo el uso de la formulación lagrangiana total. Los resultados muestran que la formación de los patrones de Turing depende de las funciones de deformación de la superficie y la tasa a la cual se presenta el cambio de posición de cada punto del dominio donde se lleva a cabo la solución numérica. Estos resultados pueden esclarecer algunos fenómenos de cambio de patrón en la superficie de la piel de aquellos animales que exhiben manchas características.In this work we have developed several numerical examples of reaction-diffusion equations with growing domain. For this purpose we have used the Schnakenberg reaction model with parameters in space Turing. Therefore numerical tests are performed on the appearance of Turing patterns on surfaces that have high deformation rate. For the solution of reaction diffusion equations is presented a solution method on surfaces in three dimensions using the finite element method under the use of the total Lagrangian formulation. The results show that the formation of Turing patterns depends on the features of surface deformation and the rate at which change in position of each point of the domain. These results can explain some phenomena of change of pattern on the surface of the skin of animals that exhibit characteristic spots.Peer Reviewe

Solution on square domains of reaction-convection-diffusion equations using spectral stochastic finite element and streamline upwind Galerkin Petrov

Se desarrolla la solución numérica de 2 problemas de difusión-convección (DC), mediante el empleo del método de elementos finitos de Petrov-Galerkin en contracorriente (SUPG). Los parámetros que definen el comportamiento de las ecuaciones se modelan como campos estocásticos, y son los siguientes: la velocidad convectiva, la difusión y la capacidad calorífica como valores de tipo aleatorio. Por tanto, se combina el método SUPG para ecuaciones de DC, con convección dominante, con el método de los elementos finitos estocásticos espectrales. Los parámetros de cada ecuación se han descrito mediante la expansión de Karhunen-Loève, mientras que la incógnita se representa mediante la expansión de los polinomios de caos. Los objetivos del artículo son: en primer lugar, estudiar la influencia de los campos estocásticos en la solución de problemas de DC con SUPG, y en segundo lugar obtener los patrones de cada coeficiente de la expansión en polinomios de caos. Los resultados muestran la versatilidad del método para solucionar diferentes problemas físicos gracias a la generalidad en la descripción estadística de la solución, y la riqueza en la representación de las zonas donde se halla la mayor variabilidad en la respuesta. Los patrones muestran la incertidumbre en la incógnita que depende de la dinámica de la difusión, la velocidad convectiva y el tipo de solución utilizado.In this paper we have developed the numerical solution of two problems of diffusion-convection (DC), using the finite element method of Streamline Upwind Petrov-Galerkin (SUPG). The parameters that define the behavior of the equations are modeled as stochastic fields, specifically, are used: the convective velocity, diffusion and heat capacity as values of random type. Therefore, we have included SUPG method to DC, with dominant convection, with the stochastic spectral finite element method. Each parameter was described by Karhunen-Loève expansion, while the unknown is represented by the polynomial expansion of the chaos. The objectives of the paper are: 1. To study the influence of stochastic fields in solving problems with SUPG DC and 2. Get the solution of each expansion unknown variable. The results show the versatility of the method for solving different physical problems due to the generality of the statistical description of the solution and the richness in the representation of the areas where there is the greater variability in response. The patterns shown in the unknown uncertainty depends on the dynamics of diffusion, convective velocity and the type of solution used.Peer Reviewe

Review of the techniques used in motor‐cognitive human‐robot skill transfer

Abstract A conventional robot programming method extensively limits the reusability of skills in the developmental aspect. Engineers programme a robot in a targeted manner for the realisation of predefined skills. The low reusability of general‐purpose robot skills is mainly reflected in inability in novel and complex scenarios. Skill transfer aims to transfer human skills to general‐purpose manipulators or mobile robots to replicate human‐like behaviours. Skill transfer methods that are commonly used at present, such as learning from demonstrated (LfD) or imitation learning, endow the robot with the expert's low‐level motor and high‐level decision‐making ability, so that skills can be reproduced and generalised according to perceived context. The improvement of robot cognition usually relates to an improvement in the autonomous high‐level decision‐making ability. Based on the idea of establishing a generic or specialised robot skill library, robots are expected to autonomously reason about the needs for using skills and plan compound movements according to sensory input. In recent years, in this area, many successful studies have demonstrated their effectiveness. Herein, a detailed review is provided on the transferring techniques of skills, applications, advancements, and limitations, especially in the LfD. Future research directions are also suggested

Identifying industry clusters in Colombia based on graph theory

This paper presents a new way to identify and understand the industry clusters in the Colombian economy. The analysis relies on a recent methodology proposed by Duque and Rey (2008) where intricate input-output linkages between industries are simplified using network analysis. In addition to other techniques for cluster identification available in the literature, this novel methodology allows us not only to classify each industry in a given cluster, but also to understand how industries are related to each other within their clusters. This methodology offers a conciliatory approach to two radically different views about the economic unit from which policy makers should design their strategies for resource allocation: Porter's cluster strategy versus Hausmann's industrial targeting

Identificação de clusters industriais na Colômbia baseados na teoria de grafos

This paper presents a new way to identify and understand the industry clusters in the Colombian economy. The analysis relies on a recent methodology proposed by Duque and Rey (2008) where intricate input-output linkages between industries are simplified using network analysis. In addition to other techniques for cluster identification available in the literature, this novel methodology allows us not only to classify each industry in a given cluster, but also to understand how industries are related to each other within their clusters. This methodology offers a conciliatory approach to two radically different views about the economic unit from which policy makers should design their strategies for resource allocation: Porter's cluster strategy versus Hausmann's industrial targeting

Effects of hydrostatic pressure and electric field on the electron-related optical properties in GaAs multiple quantum well

The properties of the electronic structure of a finite-barrier semiconductor multiple quantum well are investigated taking into account the effects of the application of a static electric field and hydrostatic pressure. With the information of the allowed quasi-stationary energy states, the coefficients of linear and nonlinear optical absorption and of the relative refractive index change associated to transitions between allowed subbands are calculated with the use of a two-level scheme for the density matrix equation of motion and the rotating wave approximation. It is noticed that the hydrostatic pressure enhances the amplitude of the nonlinear contribution to the optical response of the multiple quantum well, whilst the linear one becomes reduced. Besides, the calculated coefficients are blueshifted due to the increasing of the applied electric field, and shows systematically dependence upon the hydrostatic pressure. The comparison of these results with those related with the consideration of a stationary spectrum of states in the heterostructure-obtained by placing infinite confining barriers at a conveniently far distance-shows essential differences in the pressure-induced effects in the sense of resonant frequency shifting as well as in the variation of the amplitudes of the optical responses. Copyright © 2017 American Scientific Publishers All rights reserved

Electronic structure and STM images simulation of defects on hBN/ black-phosphorene heterostructures: A theoretical study

By first principles calculations which include van der Waals interactions, we studied the electronic structure of hexagonal boron-nitride/black-phosphorene heterostructures (hBN/BP). In particular the role of several kind of defects on the electronic properties of black-phosphorene monolayer and hBN/BP heterostructure was analyzed. The defects under consideration were single and double vacancies, as well Stone-Wale type defects, all of them present in the phosphorene layer. In this way, we found that the electronic structure of the hBN/BP is modified according the type of defect that is introduced. As a remarkable feature, our results show occupied states at the Fermi Level introduced by a single vacancy in the energy gap of the hBN/BP heterostructure. Additionally, we performed simulations of scanning tunneling microscopy images. These simulations show that is possible to discriminate the kind of defect even when the black-phosphorene monolayer is part of the heterostructure hBN/BP. Our results may help to discriminate among several kind of defects during experimental characterization of these novel materials. © 2017 Elsevier B.V

Organizing farmers for effective training and capacitation for tree-based enterprises

Since the adoption of a nationwide community-based forest management strategy 25 years ago, people’s organizations (POs) have been the Philippine Government’s key partners in programs and projects in upland communities, including the Natural Resources Management Program (NRMP), the Environment and Natural Resources Sectoral Adjustment Loan Program (ENR-SECAL), and the Community-Based Resource Management Program (CBRMP). These programs have provided important lessons that have served as the foundation for recent Government initiatives. In 2018, a PO accreditation system was pioneered through the Integrated Natural Resources and Environmental Management Project (INREMP). This innovative mechanism to improve disbursement and increase POs’ capacity to facilitate high-quality sub-projects has, however, been confronted with implementation challenges. This brief suggests concrete actions to increase the capacity of the Department of Environment and Natural Resources (DENR) and POs and to simplify the complex process for POs to support their transformation into small, community-based enterprises