Robustness against disorder and defects is a pivotal advantage of topological systems1, manifested by the absence of electronic backscattering in the quantum-Hall2 and spin-Hall effects3, and by unidirectional waveguiding in their classical analogues4,5. Two-dimensional (2D) topological insulators4–13, in particular, provide unprecedented opportunities in a variety of fields owing to their compact planar geometries, which are compatible with the fabrication technologies used in modern electronics and photonics. Among all 2D topological phases, Chern insulators14–25 are currently the most reliable designs owing to the genuine backscattering immunity of their non-reciprocal edge modes, brought via time-reversal symmetry breaking. Yet such resistance to fabrication tolerances is limited to fluctuations of the same order of magnitude as their bandgap, limiting their resilience to small perturbations only. Here we investigate the robustness problem in a system where edge transmission can survive disorder levels with strengths arbitrarily larger than the bandgap—an anomalous non-reciprocal topological network. We explore the general conditions needed to obtain such an unusual effect in systems made of unitary three-port non-reciprocal scatterers connected by phase links, and establish the superior robustness of anomalous edge transmission modes over Chern ones to phase-link disorder of arbitrarily large values. We confirm experimentally the exceptional resilience of the anomalous phase, and demonstrate its operation in various arbitrarily shaped disordered multi-port prototypes. Our results pave the way to efficient, arbitrary planar energy transport on 2D substrates for wave devices with full protection against large fabrication flaws or imperfections.
Structure control techniques have been used to control vibrations in civil structures from natural and other types of hazards for many years. However, it is difficult to achieve effective reduction in the dynamic responses of the structures under seismic excitation for the reason that earthquake generates huge kinetic energy in short time interval, unless adopting very large conventional vibration reduction devices to absorb so much energy. A kind of mass damper, the accelerated oscillator damper is proposed in this article to improve the performance of vibration absorbers. The kinetic energy of the secondary mass is proportional to the square of its velocity, and speed of the secondary mass can be amplified through the transmission of the accelerated oscillator damper system, so that according to the principle of energy conservation, the more kinetic energy the secondary mass gets from the whole system, the more kinetic energy the building will lose. The proposed accelerated oscillator damper system is superior to the tuned mass damper system for short input durations and the maximum seismic response. Moreover, the investigation also shows that the transmission ratio plays a more significant role for vibration absorption than the mass ratio.
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