An analytical model of radial dust trapping in protoplanetary disks

We study dust concentration in axisymmetric gas rings in protoplanetary disks. Given the gas surface density, we derived an analytical total dust surface density by taking into account the differential concentration of all the grain sizes. This model allows us to predict the local dust-to-gas mass ratio and the slope of the particle size distribution, as a function of radius. We test this analytical model comparing it with a 3D magneto-hydrodynamical simulation of dust evolution in an accretion disk. The model is also applied to the disk around HD 169142. By fitting the disk continuum observations simultaneously at $\lambda = 0.87$, 1.3, 3.0 mm, we obtain a global dust-to-gas mass ratio $\epsilon_{\rm global} = 1.05 \times 10^{-2}$ and a viscosity coefficient $\alpha = 1.35 \times 10^{-2}$. This model can be easily implemented in numerical simulations of accretion disks

Combining reinforcement learning and conventional control to improve automatic guided vehicles tracking of complex trajectories

With the rapid growth of logistics transportation in the framework of Industry 4.0, automated guided vehicle (AGV) technologies have developed speedily. These systems present two coupled control problems: the control of the longitudinal velocity, essential to ensure the application requirements such as throughput and tag time, and the trajectory tracking control, necessary to ensure the proper accuracy in loading and unloading manoeuvres. When the paths are very short or have abrupt changes, the kinematic constraints play a restrictive role, and the tracking control becomes more challenging. In this case, advanced control strategies such as those based on intelligent techniques, including machine learning (ML) can be useful. Hence, in this work, we present an intelligent hybrid control scheme that combines reinforcement learning-based control (RLC) with conventional PI regulators to face both control problems simultaneously. On the one hand, PIs are used to control the speed of each wheel. On the other hand, the input reference of these regulators is calculated by the RLC in order to reduce the guiding error of the path tracking and to maintain the longitudinal speed. The latter is compared with a PID path following controller. The PID regulators have been tuned by genetic algorithms. The RLC allows the vehicle to learn how to improve the trajectory tracking in an adaptive way and thus, the AGV can face disturbances or unknown physical system parameters that may change due to friction and degradation of AGV mechanical components. Extensive simulation experiments of the proposed intelligent control strategy on a hybrid tricycle and differential AGV model, that considers the kinematics and the dynamics of the vehicle, prove the efficiency of the approach when following different demanding trajectories. The performance of the RL tracking controller in comparison with the optimized PID gives errors around 70% smaller, and the average maximum error is also 48% lower.Open access funding enabled and organized by Projekt DEAL

A Coordinated Plan for Teaching Software Engineering in the University Rey Juan Carlos.

Un plan para organizar las enseñanzas de la ingeniería del software en las titulaciones de informática de la URJC. Nowadays both industry and academic environments are showing a lot of interest in the Software Engineering discipline. Therefore, it is a challenge for universities to provide students with appropriate training in this area, preparing them for their future professional practice. There are many difficulties to provide that training. The outstanding ones are: the Software Engineering area is too broad and class hours are scarce; the discipline requires a high level of abstraction; it is difficult to reproduce real world situations in the classroom to provide a practical learning environment; the number of students per professor is very high (at least in Spain); companies develop software with a maturity level rarely over level 2 of the CMM for Software (again, at least in Spain) as opposed to what is taught at the University. Besides, there are different levels and study plans, making more difficult to structure the contents to teach in each term and degree. In this paper we present a plan for teaching Software Engineering trying to overcome some of the difficulties above

Application of knowledge engineering acquisition techniques to requirements capture: a case study

In this paper we want to point out, by means of a case study, the importance of incorporating some knowledge engineering techniques to the processes of software engineering. Precisely, we are referring to the knowledge eduction techniques. We know the difficulty of requirements acquisition and its importance to minimise the risks of a software project, both in the development phase and in the maintenance phase. To capture the functional requirements use cases are generally used. However, as we will show in this paper, this technique is insufficient when the problem domain knowledge is only in the "experts? mind". In this situation, the combination of the use case with eduction techniques, in every development phase, will let us to discover the correct requirements

A taxonomy of the quality attributes for distributed applications

The software engineering community has paid little attention to non-functional requirements, or quality attributes, compared with studies performed on capture, analysis and validation of functional requirements. This circumstance becomes more intense in the case of distributed applications. In these applications we have to take into account, besides the quality attributes such as correctness, robustness, extendibility, reusability, compatibility, efficiency, portability and ease of use, others like reliability, scalability, transparency, security, interoperability, concurrency, etc. In this work we will show how these last attributes are related to different abstractions that coexist in the problem domain. To achieve this goal, we have established a taxonomy of quality attributes of distributed applications and have determined the set of necessary services to support such attributes

How to distinguish between interacting and noninteracting molecules in tunnel junctions

Recent experiments demonstrate a temperature control of the electric conduction through a ferrocene-based molecular junction. Here we examine the results in view of determining means to distinguish between transport through single-particle molecular levels or via transport channels split by Coulomb repulsion. Both transport mechanisms are similar in molecular junctions given the similarities between molecular intralevel energies and the charging energy. We propose an experimentally testable way to identify the main transport process. By applying a magnetic field to the molecule, we observe that an interacting theory predicts a shift of the conductance resonances of the molecule whereas in the noninteracting case each resonance is split into two peaks. The interaction model works well in explaining our experimental results obtained in a ferrocene-based single-molecule junction, where the charge degeneracy peaks shift (but do not split) under the action of an applied 7-Tesla magnetic field. This method is useful for a proper characterization of the transport properties of molecular tunnel junctions.Comment: Main text: 7 pages, 5 figures; SI: 2 pages, 2 figures. Accepted to RSC Nanoscal

Sistemas expertos que recomiendan estrategias de instrucción. Un modelo para su desarrollo

Las aplicaciones inteligentes del software computacional intentan emular los procesos del pensamiento humano. El problema que se presenta a los diseñadores de ambientes educativos es la cantidad de variables que interactúan entre sí y que deben ser tenidas en cuenta para un diseño efectivo de la instrucción. Los autores describen un sistema experto que asiste a los diseñadores de la instrucción en la identificación de la mejor estrategia instruccional dado un escenario definido por las características del que aprende, del currículum y del contexto del aprendizaje. En los aspectos metodológicos se considera la definición del problema estableciendo: objetivos, alcance, participantes y ámbito donde se utiliza el sistema. Una vez conocidos todos estos datos, el sistema experto es capaz de identificar el patrón o combinación de patrones que mejor se adapta a la situación instruccional presentada por el usuario, recomendando de este modo estrategias de instrucción a utilizar por parte del diseñador.As aplicações inteligentes do software computacional tentam copiar os processos do pensamento humano. O problema que se apresenta para os projetistas de ambiente educativos e da quantidade de variáveis que interatuam entre si e que deveriam ter em conta para um projeto efetivo de Instrução. Os autores descrevem um sistema especial que auxilia os projetistas de instrução na identificação da melhor estratégia instrucional dado um cenário definitivo para as características do que aprende, do currículo e do contexto de aprendizagem. Nos aspectos metodológicos se considera a definição dos problemas estabelecendo: objetivos, alcance, particpants e ámbito onde se utiliza o sistema. Uma vez conhecidos todos os dados, o sistema especial e capaz de identificar de pronto a combinação de padrões que melhor se adapta a situação instrucional apresentada pelo usuário, recomendando deste modo estratégias de instrução a utilizar por parte do projetista

Utilización de fibras desechas de procesos industriales como estabilizador de mezclas asfálticas sma

Las mezclas tipo SMA (Stone Mastic Asphalt) son mezclas asfálticas calientes de gradación discontinua desarrolladas para maximizar la resistencia al ahuellamiento y la durabilidad. Esta mezcla está compuesta de dos partes: un esqueleto de agregados gruesos y un mastic rico en asfalto, sin embargo, estas dos partes hacen que la mezcla asfáltica presente segregación entre los agregados y el asfalto, y como consecuencia de ello escurrimiento del mismo asfalto. Es por esto que la mezcla requiere del uso de fibras que inhiban el escurrimiento, y para ello los manuales de diseño específicos para este tipo de mezcla exigen el uso de fibras de celulosa peletizadas y premezcladas con asfalto. Este tipo de fibras actualmente no se producen en el país, por lo que su importación eleva el costo de la mezcla respecto al costo de una mezcla convencional.SMA mixtures (Stone Mastic Asphalt) are hot asphalt mixtures discontinuous gradation developed to maximize rutting resistance and durability. This mixture is composed of two parts: a coarse aggregate skeleton and asphalt rich mortar, however, these two parts make present asphalt mixture segregation of the aggregates and asphalt and as a consequence asphalt draindown. That is why the mixture requires the use of fibers that inhibit runoff, and for these specific design manuals for this type of mixture require the use of cellulose fibers and premixed pelletized asphalt. This type of fiber is not currently produced in the country, so import raises the cost of the mixture in relation to the cost of a conventional mixture.Ingeniero (a) CivilPregrad

Hybrid Optimized Fuzzy Pitch Controller of a Floating Wind Turbine with Fatigue Analysis

Floating offshore wind turbines (FOWTs) are systems with complex and highly nonlinear dynamics; they are subjected to heavy loads, making control with classical strategies a challenge. In addition, they experience vibrations due to wind and waves. Furthermore, the control of the blade angle itself may generate vibrations. To address this issue, in this work we propose the design of an intelligent control system based on fuzzy logic to maintain the rated power of an FOWT while reducing the vibrations. A gain scheduling incremental proportional–derivative fuzzy controller is tuned by genetic algorithms (GAs) and combined with a fuzzy-lookup table to generate the pitch reference. The control gains optimized by the GA are stored in a database to ensure a proper operation for different wind and wave conditions. The software Matlab/Simulink and the simulation tool FAST are used. The latter simulates the nonlinear dynamics of a real 5 MW barge-type FOWT with irregular waves. The hybrid control strategy has been evaluated against the reference baseline controller embedded in FAST in different environmental scenarios. The comparison is assessed in terms of output power and structure stability, with up to 23% and 33% vibration suppression rate for tower top displacement and platform pitch, respectively, with the new control scheme. Fatigue damage equivalent load (DEL) of the blades has been also estimated with satisfactory results.This work has been partially supported by the Spanish Ministry of Science and Innovation under the project MCI/AEI/FEDER number RTI2018-094902-B-C21 and PDI2021-123543OB-C21