Tuned Liquid Dampers (TLDs) are dissipative devices whose distinguished features like low cost in installation and maintenance or their multidirectional and multifrequency application to new and already existing structures make them an attractive damping option. Their working principle is similar to that of a Tuned Mass Damper but in this case the relative movement comes from a fluid that provides with mass, damping and stiffness. Moreover, TLDs can mitigate both horizontal and vertical vibrations. All these make TLDs worth deeply studying. TLD utilization in civil vibration control arose in the 1980s. From early years, different improvements have been implemented to achieve a better performance. Some of these modifications include passive variations in the geometry or the fluid. The use of smart materials applied on TLDs has also been of great interest since the 1990s and comprehends different configurations in which magnetic fields are used to passively or semi-actively improve the TLD performance. A lack of review is detected in this field. For this reason, a state-of-the-art review is presented in this paper. Its aim is to help researchers find a thorough, up-to-date classification of the different possibilities, configurations, numerical evaluation, materials used and also found limitations and future development in the application of magnetic fields on TLDs.

Tuned Liquid Dampers (TLDs) are dissipative devices that mitigate vibrations through the out-of-phase movement of a fluid, typically water, inside a container relative to a main structure. Water’s low density and viscosity have led to modifications to enhance their effectiveness. Fluid properties, such as density or viscosity, significantly impact their performance by altering mass and damping, respectively. When magnetorheological fluids are employed, magnetic fields can modify the fluid viscosity, affecting the damping. This study experimentally examines the effect of a magnetic field and ambient parameters on the viscosity of different low-cost, custom-prepared magnetic fluids. A tube filled with magnetic liquids into which diverse non-magnetic spheres are dropped was employed, considering on- and off-states of the magnetic field generated by a pair of Helmholtz coils. The impact on the fluid viscosity variation of different measured variables was statistically analyzed. It was found that in all cases, the variations in ambient temperature and relative humidity had no effect on the results. While the magnetic field had a large effect on the viscosity of the magnetic fluid, for the sunflower oil-based fluids, the spheres used or the concentration of iron filings had a greater effect on the viscosity than the presence of the magnetic field.

Los pernos conectores aportan múltiples ventajas de uso, entre las que se encuentra el elevado margen de seguridad que ofrecen sus soldaduras ejecutadas mediante arco eléctrico. Estas soldaduras, aunque ampliamente fiables, son difícilmente comprobadas mediante ensayos no destructivos. El presente estudio plantea la inspección de soldaduras de pernos conectores mediante su espectro acústico. Analíticamente, la investigación se ha centrado en el cálculo de los primeros modos propios de vibración. Experimentalmente se han medido las frecuencias propias de resonancia de 28 pernos, en los que posteriormente se han llevado a cabo ensayos tanto no destructivos como destructivos. Se ha obtenido, tanto teórica como experimentalmente, una relación entre la frecuencia de vibración de los pernos conectores y la calidad de la soldadura. Por ello se verifica la posibilidad de inspección de estas soldaduras mediante un ensayo acústico con el que es posible detectar los defectos internos donde los métodos convencionales resultan inviables.

This article presents a new automatic evaluation for on-line graphics, its application and the numerous advantages achieved applying this developed correcting method. The software application developed by the Innovation in Education Group “E4”, from the Technical University of Madrid, is oriented for the online self-assessment of the graphic drawings that students carry out as continuous training. The adaptation to the European Higher Educational Area is an important opportunity to research about the possibilities of on-line education assessment. In this way, a new software tool has been developed for continuous self-testing by undergraduates. Using this software it is possible to evaluate the graphical answer of the students. Thus, the drawings made on-line by students are automatically corrected according to the geometry (straight lines, sloping lines or second order curves) and by sizes (depending on the specific values which define the graphics)

Information about the paper titled "HOW TO LEARN HAVING FUN: DRAG AND DROP QUESTIONS FOR BUILDING STRUCTURES" at IATED Digital Library