Inverse Control and Stabilization of Free-flying Flexible Robots

The question of control and stabilization of flexible space robots is considered. Although, this approach is applicable to space robots of other configurations, for simplicity, a flexible planar two-link robot, mounted on a rigid floating platform, is considered. The robotic arm has two revolute joints and its links undergo elastic deformation in the plane of rotation. Based on nonlinear inversion technique, a control law is derived for controlling output variables describing the position and orientation of the platform and the joint angles of the robot. Although, the inverse controller accomplishes reference trajectory tracking, it excites the elastic modes of the arm. For the vibration suppression, three different stabilizer are designed. Using linear quadratic optimal control theory, a composite stabilizer for stabilization of the rigid and flexible modes and a decoupled flexible mode stabilizer are designed for regulating the end point of the robot to the target point and vibration suppression. Stabilization using only elastic mode velocity feedback is also considered. For large maneuvers, first the inverse controller is active, and the stabilizer is switched for regulation when the motion of the robot lies in the neighborhood of the terminal equilibrium state. Simulation results are presented to show that in the closed-loop system including the inverse controller and each of the stabilizers, trajectory tracking and stabilization of elastic modes are accomplished

On the criticality of inferred models

Advanced inference techniques allow one to reconstruct the pattern of interaction from high dimensional data sets. We focus here on the statistical properties of inferred models and argue that inference procedures are likely to yield models which are close to a phase transition. On one side, we show that the reparameterization invariant metrics in the space of probability distributions of these models (the Fisher Information) is directly related to the model's susceptibility. As a result, distinguishable models tend to accumulate close to critical points, where the susceptibility diverges in infinite systems. On the other, this region is the one where the estimate of inferred parameters is most stable. In order to illustrate these points, we discuss inference of interacting point processes with application to financial data and show that sensible choices of observation time-scales naturally yield models which are close to criticality.Comment: 6 pages, 2 figures, version to appear in JSTA

Prediction of genotypic values of maize for the agricultural frontier region in northeastern Maranhão, Brazil.

Agricultural research, mainly focused on the evaluation of maize cultivars along agricultural frontiers, are scarce. This study assessed 128 maize genotypes in the agricultural frontier region of the State of Maranhão, between 2008 and 2009. The experiment was arranged in a lattice design with two replications. The genotypes were evaluated for grain yield in a mixed model, with fixed intercept and experimental effects. The random effects were genotype, genetic class (single-, double or triple-cross hybrid and variety), and incomplete block/replication/ environment. The genotype effect was significant by the likelihood ratio test in all models, highlighting the genotypic values of the single-cross hybrids DKB177, AG8088 and DKB390, the triple-cross PL6882, the double-cross BM502 and of the open-pollinated variety SHS3031Nota técnica

Just Another Day: A Comic About Brexit

The uncertainty generated by Brexit has motivated us to prepare a comic that explains in an educative and informative way the different options that Europeans and their families have available to minimise the impact of Brexit. Concept and story by Francisco de la Mora and Ernesto Priego. Art by Ricardo Peláez. Second page text and information by Manuel Padilla Behar. The text in the comic was translated from the original Spanish into English by Ernesto Priego. Graphic design by Daniela Rocha. With special thanks to Helen Calderon for proofreading and feedback

Tumor dissociation of highly viable cell suspensions for single-cell omic analyses in mouse models of breast cancer.

Cell preparation with a high rate of viable cells is required to obtain reliable single-cell transcriptomic and epigenomic data. This protocol describes a technique for digestion and single-cell isolation from mouse mammary tumors to achieve ∼90% of viable cells, which can be subsequently processed in a diverse array of high-throughput single-cell "omic platforms," both in an unbiased manner or after selection of a specific cell population. For complete details on the use and execution of this protocol, please refer to Valdes-Mora et al. (2021)

Uso de microalgas inmovilizadas en biofilm para tratamiento de aguas residuales

Los sistemas desarrollados para el cultivo de las microalgas pueden clasificarse en dos grandes grupos, en función de la forma de desarrollo de las poblaciones algales: cultivos en suspensión y cultivos inmovilizados. A su vez, ambos sistemas de cultivo pueden ser abiertos o cerrados, según que las microalgas y el medio de cultivo estén en contacto directo con el aire atmosférico o no. Los cultivos de microalgas inmovilizadas en una superficie que actúa de soporte, forman un 'biofilm' contínuo sobre dicha superficie formando un ecosistema específico de agregación denominado 'biofilm', normalmente constituido por varias especies, incluyendo bacterias, aunque puede haber alguna predominante. Las principales ventajas que tienen los fotobior reactores de biofilm sobre los de células suspendidas son: a) Facilidad para la cosecha, b) Mayor concentración por unidad de volumen de medio, c) reducción o ausencia de células en el efluente, d) reducción en la necesidad de energía y e) mayor eficiencia en el empleo de la radiación recibida por unidad de superficie de suelo. El uso de fotobiorreactores abiertos de microalgas inmovilizadas es relativamente reciente, dirigiéndose los desarrollos en dos direcciones: una que considera el soporte del biofilm fijo, siendo el medio acuoso el que se mueve sobre él y otra que considera el soporte del biofilm móvil en un medio acuático estático o de lento movimiento. Al primero de los tipos pertenece el fotobiorreactor laminar desarrollado por el Grupo de Agroenergética de la UPM (GA-UPM) (patente ES 2 347 515 B2 ), especialmente concebido para la captación del CO2 procedente de emisiones y para la producción de biomasa algal. Otro desarrollo del GA-UPM perteneciente al segundo tipo ha sido un fotobiorreactor de biodisco de eje flotante, que elimina los inconvenientes de los contactores de biodisco tradicionales, ya que no necesita cojinetes de apoyo ni eje rígido y al estar dotado de un propulsor hidrobárico consume muy poca energía, sin limitación técnica en cuanto a la longitud total del eje. (Modelo de Utilidad ES 1 099 707 U). Este fotobiorreactor está especialmente diseñado para la eliminación de nutrientes (N y P) de los efluentes del secundario de las EDAR y también puede utilizarse como un contactor tradicional de biodiscos para eliminación de la materia orgánica de las aguas residuales con indudables ventajas de reducción de costes de instalación y funcionamiento

A transient network of telechelic polymers and microspheres : structure and rheology

We study the structure and dynamics of a transient network composed of droplets of microemulsion connected by telechelic polymers. The polymer induces a bridging attraction between droplets without changing their shape. A viscoelastic behaviour is induced in the initially liquid solution, characterised in the linear regime by a stretched exponential stress relaxation. We analyse this relaxation in the light of classical theories of transient networks. The role of the elastic reorganisations in the deformed network is emphasized. In the non linear regime, a fast relaxation dynamics is followed by a second one having the same rate as in the linear regime. This behaviour, under step strain experiments, should induce a non monotonic behaviour in the elastic component of the stress under constant shear rate. However, we obtain in this case a singularity in the flow curve very different from the one observed in other systems, that we interpret in terms of fracture behaviour.Comment: 9 pages, 4 figure

Dairy buffalo behaviour and welfare from calving to milking

This review integrates recent scientific findings on the behaviour and welfare of buffalo dams during calving and the subsequent milking phase. These issues are discussed in relation to the level of welfare that buffalo dams and calves experience under different production systems. Key aspects are addressed including welfare issues related to dystocic parturitions and uterine prolapses, the formation of a selective dam-calf bonding, the habituation of inexperienced animals to the milking routine and the appropriate relationship to be developed with stock-people. All these aspects are also discussed in relation to farm profitability, in terms of calf vitality and milk production, and safety of the personnel involved in farm operations

Resiliencia en profesionales de la intervención social

La resiliencia es un concepto con un enorme potencial para todas aquellas profesiones que reconocen en su objeto de intervención la prevención basada en las fortalezas y recursos propios de las personas y del entorno con el que se relacionan. En base a ello, existen numerosas investigaciones que analizan el papel de la intervención social y de sus profesionales en la construcción de la resiliencia de los individuos, grupos y comunidades hacia los que dirigen su actuación. Sin embargo, son menos frecuentes los trabajos de teorización e investigación centrados en el desarrollo y construcción de esta misma capacidad resiliente en los propios profesionales y en las implicaciones que de ello se deriva para su práctica profesional y para las organizaciones en las que se encuentran. Con el objetivo principal de analizar la presencia de la resiliencia en los profesionales de la intervención social frente a la de otros profesionales no relacionados con la ayuda social, se lleva a cabo una investigación de corte transversal en la que participan 366 sujetos, trabajadores sociales y otros profesionales – informáticos, ingenieros, trabajadores manuales y de servicios- todos ellos de la provincia de Málaga. Se analizan los diferentes los componentes de la resiliencia, siguiendo el modelo de Grotberg (1995). Los resultados apuntan hacia el colectivo de trabajadores sociales como más resilientes que el resto de profesionales.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech