Backlash Compensation for Plants With Saturating Actuators

A compensation scheme is proposed for plants subject to both saturation and backlash in series at the actuator. It is shown that the series connection of a backlash inverse, saturation and the backlash itself is equivalent to a saturation function at a different level to the original saturation, and we call this the ‘saturation equivalence’. Therefore, it is proposed to include such a backlash inverse in the compensator. This is shown to be optimal in a sense defined in the article. It is then straightforward to devise a compensator scheme based on traditional anti-windup. This is illustrated in both simulation and on a laboratory scale rig with severe backlash. A correction for the chattering observed in the control signal due to the discontinuous nature of the nonlinearity inverse is also presented. </jats:p

Análisis sobre la influencia de la densidad en la termografía de infrarrojos y el alcance de esta técnica en la detección de defectos internos en la madera

This paper shows the results of a laboratory phase for the determination of the 1limits of infrared thermography in detecting internal defects in wood and, furthermore, it analyses how the density of this material can influence the surface temperature displayed in a thermogram. To this end, experimental work is carried out whereby a series of work and environmental parameters are monitored (such as environmental temperature, relative humidity, distance to target), and the process is systematized by using pieces of different wood species (different densities) and by devising a set of samples for which various possible cases are analysed in terms of size and internal position of the damage. Similarly, using these samples, a study has been conducted on the effect on the thermal image produced by an increase of humidity inside the defect phenomena normally associated with wood decay.En el presente artículo se muestran los resultados obtenidos en una fase de laboratorio al tratar de determinar el alcance de la termografía de infrarrojos en la detección de defectos internos en la madera y, por otro lado, cómo interviene la densidad de este material sobre la temperatura superficial mostrada en un termograma. Para ello se ha desarrollado un trabajo experimental donde se han controlado una serie de parámetros ambientales y de trabajo (temperatura ambiente, humedad relativa, distancia al objetivo…), y se ha sistematizado el proceso utilizando piezas de distintas especies de madera (distintas densidades) y diseñando una serie de probetas donde se han analizado varias casuísticas posibles en cuanto a tamaño y posición interna de los daños. Análogamente, sobre estas probetas se ha estudiado el efecto que produce sobre la imagen termográfica un incremento de humedad interna en el defecto asociada normalmente a los fenómenos de pudrición de la madera

Evaluación del estado de la madera en obras de rehabilitación mediante técnicas de ultrasonidos y obtención de parámetros resistentes

A nondestructive technique for inspection and evaluation in place timber structures and components based on ultrasonic pulse velocity, and moisture content is presented herein. By applying this methodology we could obtain the bending strength and elasticity modulus of timber beams, as well as the damage in them. The quantitative determination of the existing strength of timber beams will provide information necessary to take the most suitable decisions in rehabilitation works involving timber structural elements.Este artículo presenta el desarrollo de un método de ensayo, no destructivo, para la inspección y evaluación in situ de elementos estructurales de madera, basado en las medidas de la velocidad de ondas ultrasónicas y determinación de humedad. Mediante la aplicación de este método se podrá obtener una estimación de la resistencia a flexión y del módulo de deformación de la madera estudiada, así como la detección de estados de deterioro de la misma. Esto aportará información suficiente a la hora de tomar decisiones en una obra de rehabilitación con elementos estructurales de este material

Use of Polycarbonate Waste as Aggregate in Recycled Gypsum Plasters

The use of gypsum as an indoor coating material for buildings is very extensive. This means that huge amounts of gypsum waste are generated daily worldwide. Therefore, many researchers in the last years have been working on the generation of new gypsum-related materials and products that incorporate recycled gypsum waste as a replacement for the commercial one. On the other hand, trying to reduce the large amounts of plastic generated globally each year, several studies have used different types of plastic waste as aggregates for the development of new construction and building materials. However, up to now, no previous studies have been found in which any type of plastic waste has been used as an aggregate in a recycled gypsum matrix. This paper presents a study in which two different types of waste were mixed for the development of new gypsum plasters: unheated gypsum waste from industrial plasterboard production (GPW) and polycarbonate (PC) waste from rejected compact discs (CDs) and digital versatile discs (DVDs). In this sense, the mechanical and thermal performance of plasters was evaluated. Finally, in order to evaluate the changes in the microstructure of the composites, a scanning electron microscopy (SEM) analysis was conducted. The results showed a good performance of the new composites when both types of waste were combined in the mixes. New lightweight eco-efficient plasters, completely recycled, with enhanced flexural strength (by 14.8%), compressive strength (by 26.8%), and thermal conductivity (42.8% less), compared to the reference material, were achieved