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The present work proposes a non-contact vibration attenuator made up of a permanent magnet mounted on a piezoelectric stack. Two such actuators are made to work simultaneously in a 'twin-actuator' configuration. It is conceived that a controlled change in the gap between the actuator and the structure is capable of attenuation of vibration of the structure. This appropriate change in gap is achieved by controlled motion of the piezoelectric stacks. It is shown that the actuator works as an active damper when the extension and contraction of the actuators are made proportional to the velocity of the beam. The resolution of extension of a piezoelectric stack is in the order of nanometers. Thus in the proposed actuator the force of actuation can be applied with great precision. This actuator is also attractive for its simple constructional feature. [ABSTRACT FROM AUTHOR]

This article uses particle swarm optimization, one of the derivative-free optimization techniques, to optimize the proportional-integral controller parameters of the DC-link voltage controller of a 48-pulse static synchronous series compensator. This particle-swarm-optimization-based proportional-integral controller is used to keep the voltage across the DC-link capacitor of a 48-pulse voltage-source-inverter-based static synchronous series compensator constant. The particle swarm optimization approach avoids the repeated trials that are needed in a trial-and-error approach to obtain near-optimum proportional-integral controller parameters. An objective function is proposed, which helps to improve the damping of modes near to the imaginary axis. The study system considered is the IEEE first benchmark model for sub-synchronous resonance. The stability of the system is determined from eigenvalue analysis. The article also shows that an optimized proportional-integral controller can improve the performance of the system with lower value of DC-link capacitor. Non-linear simulations are performed to verify the results of eigenvalue analysis. [ABSTRACT FROM AUTHOR]

• Experimental tests showed that the knurled fiber presented an improved thermomechanical behavior up to 1000 °C. • The FE model can extrapolate investigations to structures in practice and save enormous laboratory time. • The constitutive model implemented in commercial software showed the accuracy of 7% with the experimental round panel test. Stainless steel fibers are widely used as reinforcement in the refractories due to advantages such as high thermal compatibility, cost-effective on account of long life and effective resistance to corrosion at high temperatures. The purpose of this research is to investigate the thermomechanical behavior of alumina based refractory concrete reinforced with different shapes of stainless steel fibers. Straight, wavy and knurled shaped stainless-steel fibers were selected for the study. These refractory composites are extensively procured for the industrial applications. A research program of experimental test and numerical simulations was carried out. Three-point bending, fiber pull-out, direct tensile and compression tests were performed at temperatures ranging from 25 to 1200 °C to obtain the mechanical residual values. The experimental test results allowed the development of the material's constitutive model that was implemented in the finite element program ABAQUS. The constitutive model was validated through thermomechanical simulations of the round panel test. The flexural results showed the behavior of the reinforcement with knurled fibers was superior for all temperatures due to its higher bond with the matrix. The experimental tests and the numerical simulations showed that the reinforcement benefits the pre-peak and post-peak behavior of the refractory concretes. The influence of the fibers on the shape of the softening curve allows the prediction of the fracture behavior of the composites. [ABSTRACT FROM AUTHOR]

• Adhesively bonded glass-metal façade elements show a high structural capacity. • Failure of the glass-metal elements is generally initiated within the adhesive. • Glass-metal elements with acrylic adhesive bonding show a higher initial stiffness. • Activation of the glass pane under in-plane loads is improved by grouting blocks. • Non-linear simulations allow a good prediction of the mechanical response. The structural efficiency of transparent façades can be increased by achieving a composite structural behaviour between the framing elements and the glass panes. The use of suitable intermediary materials is substantial for obtaining a composite structural behaviour for both out-of-plane and in-plane loading. This article presents two novel configurations for such glass-metal elements. For the first configuration, a perimetrical bonding with a silicone adhesive between the glass pane and the filigree metal framing is responsible for transferring stresses in out-of-plane direction, and grouting blocks are used near the glass pane corners for transferring stresses in in-plane direction. In the case of the second configuration, a perimetrical bonding with an acrylic adhesive between the glass pane and the filigree metal framing is responsible for transferring stresses in both out-of-plane and in-plane direction. Full-scale tests and finite element simulations with loads acting in three different directions, both separately and combined, are performed for the two configurations. The results of the tests performed under in-plane shear loading reveal a high load-bearing capacity of both configurations and show that failure is initiated within the adhesive joints. The numerical models, which include previously derived non-linear material models for the adhesives, allow a good prediction of the mechanical response of the investigated glass-metal elements. The presented load vs. displacement diagrams illustrate that the elements with acrylic adhesive behave stiffer both under out-of-plane and under in-plane loading before the adhesive starts to yield. Overall, the configuration with silicone adhesive and grouting represents a solution which can be applied in real projects based on existing technical approvals for the involved materials in similar applications. On the other hand, the configuration with acrylic adhesive indicates the potential of glass-metal elements with stiffer adhesives, assuming that the knowledge on such adhesives will continue to grow and that, eventually, new enhanced products will be developed by the adhesive industry. [ABSTRACT FROM AUTHOR]