Non-recursive augmented Lagrangian algorithms for the forward and inverse dynamics of constrained flexible multibodies

A technique is presented for solving the inverse dynamics of flexible planar multibody systems. This technique yields the non-causal joint efforts (inverse dynamics) as well as the internal states (inverse kinematics) that produce a prescribed nominal trajectory of the end effector. A non-recursive global Lagrangian approach is used in formulating the equations for motion as well as in solving the inverse dynamics equations. Contrary to the recursive method previously presented, the proposed method solves the inverse problem in a systematic and direct manner for both open-chain as well as closed-chain configurations. Numerical simulation shows that the proposed procedure provides an excellent tracking of the desired end effector trajectory

An overview of current Spanish theatre

El artículo reflexiona sobre la escena española actual y, desde sus antecedentes inmediatos, sugiere sus líneas principales. Una mirada sobre algunos acontecimientos significativos recientes permite examinar hasta qué punto esta tradición de la que proviene tiene vigencia, pero también advertir cuáles son las perspectivas para un futuro próximo.This article deals with today’s Spanish theatre and, taking stock of the latest records, singles out its main trends. A look at some recent performances permits to assess both the importance of tradition and the impact of new perspectives

Experimental Research and Finite Element Modeling of 3-D Semi-Rigid Composite Joints under Proportional Loads

The behaviour of 2-D composite semi-rigid joints has been researched since the seventies, including experimental work, numerical models, analytical models and practical methods of analysis. However, one of the areas where research is still needed is in the three-dimensional behaviour of semi-rigid composite joints, that is, columns with beams attached to both axes (major and minor axis). This paper describes the details and the results of an experimental program consisting in a test of a 3D composite semi-rigid joint. The design of major axis connection is made with a bolted flush end plate connection while that of the minor axis is done by means of an additional plate welded to the column flanges, rather than attach it to the column web. The specimen is subjected to proportional loads, and further research will be done with non-proportional loads. A finite element (FE) model is developed and validated using the experimental results. The FE model will be used to perform a parametric study for three-dimensional semi-rigid composite joints subjected to proportional and non-proportional loads in a future research

Metamodelling of stiffness matrices for 2D welded asymmetric steel joints

Manuscrito aceptado[Abstract]: Beam-column steel joints usually have a semi-rigid behaviour, and this must be taken into account when carrying out a global analysis of the structure. Rotational springs at each side of the joint are commonly used to simulate this behaviour by means of the component method, but asymmetric welded beam-column steel joints are not included in the formulations of Eurocode 3. This research work proposes a new methodology to obtain the stiffness of welded asymmetrical beam-column steel joints, by means of a cruciform element of 4 nodes and 12 DOF, whose stiffness matrix is directly obtained by means of the meta-modelling of its elements using Kriging's method. The authors have carried out a wide study of 754 different asymmetric welded beam-column steel joints, whose finite element models have been analysed, and then the static condensation method has been used to obtain the equivalent condensed stiffness matrix (Kcond) of the cruciform element for the joints belonging to the training set. These matrices have been used to build the Kriging's model, and the rest of joints have been used for testing the method, which yields very good results. The use of meta-modelling methods to obtain the stiffness matrix of the joint is not only easier in its application than the component method, but it also leads to a formulation that is more accurate, and also takes into account the interactions between the different parts of the joint.The financial support provided by the Spanish Ministerio de Economía y Competitividad and Fondo Europeo de Desarrollo Regional under contract BIA2016-80358-C2-2-P and BIA2016-80358-C2-1-P MINECO/FEDER UE is gratefully acknowledged

First evidence of microplastics isolated in European citizens’ lower airway

Microplastics (MPs) have been detected in all environmental locations, including the atmosphere. However, few studies have investigated the presence of airborne MPs in the human respiratory system. Our research purpose was to investigate these pollutants in the lower human airways of 44 adult European citizens, using bronchoalveolar lavage fluid (BALF) collection as a minimally invasive method, that enables the detection of these pollutants in living patients. We studied the relationship between the patients’ life habits and physiological parameters, based on background information and medical and occupational history, and the concentration of MPs isolated from their respiratory systems. Our results indicate that most MPs were in the form of microfibers (MFs) (97.06%), with an average concentration of 9.18 ± 2.45 items/100 mL BALF, and only 5.88% (0.57 ± 0.27 items/100 mL BALF) were particulate MPs, without a significant relationship with environmental, physiological, or clinical factors. The average size was 1.73 ± 0.15 mm, with the longest dimension (9.96 mm) corresponding to a polyacrylic fiber. Taken together, the results demonstrated the occurrence of MPs in the lower human airway, although more studies are necessary to elucidate the negative effects these pollutants could induce in the human respiratory system and its associated diseases.We wish to express our sincere appreciation to José V. Navarro for safe BALF samples transportation form HGUE to UPCT and back, as well as to the HGUE Pneumology Service, particularly to Sandra Ruiz, Lucía Zamora, Maria José Soler, Asunción Guillén, and Carmen María Vidal for their help in BALF samples collection and investigation support. This work was finacially supported by grant 20268/FPI/17 from Fundación Séneca assigned to Dra. Sonia Olmos, as well as by Project Number 6627/21IQA signed between FISABIO and Technical University of Cartagena, with financial help from Sociedad Valenciana de Neumología

Virtualización de prácticas de laboratorio para la mejora del aprendizaje de estudiantes de primeros cursos en Ciencias e Ingenierías en las Facultades de Ciencias, Ciencias Químicas y Ciencias Agrarias y Ambientales

Memoria ID-2020/006.Ayudas de la Universidad de Salamanca para la innovación docente, curso 2020-2021

Devising an Electric Power System: A CDIO Approach Applied to Electrical Engineering

The study of electric power systems within the field of Electrical Engineering is usually approached by computer simulations because any actual test is quite complex to be implemented. Having the aim to improve student learning about this topic, a new subject called “Devising an Electric Power System” was organized following a CDIO (Conceive-Design- Implement-Operate) approach. The subject is programmed for one academic year and based entirely on laboratory work. The students are divided into three groups. Every group would have to work on a device that includes a solar PV generator and a pumping controlled drive, both connected to a three–phase grid. The process followed by the students along the academic year begins with a short theoretical introduction and simulation studies where they conceive and design control strategies. These control strategies are for the solar PV generator (i.e., programing the “Maximum Power Point Tracking” MPPT) as well as for the pumping electric drive (i.e., following a V/f strategy or a vector control). The process is continued by practical implementation of the simulated algorithms previously obtained. In this step, the students implement and operate the systems until they become robust and well adjusted, and ready for the intermediate partial competition among the three groups. During this practical implementation stage, the innovative competence is better enhanced. At the moment that each group has implemented an electric generator and an electric consumption (load), they follow the third and last part of the subject that is focused on “electric utility” business strategy. The students will have to comply with the rules of the electricity market by offering energy packages to be generated and consumed at a certain price. The price and volume of energy to be generated/consumed are determined by the convergence point of supply and demand, as determined by the marginal pricing model. Once the market is cleared, the students have to realize their generation/consumption commitments by operating the real power system they have conceived and implemented. After the first academic year of this subject, the students’ evaluation was highly acceptable. The specific technological contents of the subject were learnt by the method called “learning by doing” that allows students to improve their skills in team building, innovation and communications. In addition, a good work atmosphere among students and teachers has arisen