The high-noise environments in and around modern military jet aircraft can impair voice communications and cause permanent damage to the hearing of pilots and maintenance crews if adequate hearing protection is not worn. With external noise levels of some aircraft approaching 150 dBA, adequate hearing protection must provide better than 50 dB of attenuation. In order to reach such a high level ...

Over the years, metamaterials have shown their potential in a wide range of different disciplines, e.g. optics, electromagnetics, dynamics etc. Metamaterials are, often periodic, engineered structures made conventional materials but which exhibit properties not encountered nature. In field noise and vibration, received increasing interest since they can obtain frequency ranges high vibration at...

We report that vertical vibration with small amplitude and high frequency can tame convective heat transport in Rayleigh–Bénard convection a turbulent regime. When is applied, dynamically averaged ‘anti-gravity’ results stabilizes the thermal boundary layer inhibits eruption of plumes. This eventually leads to attenuation intensity large-scale mean flow significant suppression transport. Accoun...

This study proposes the use of a linear and geometrically nonlinear inerter-based resonator in locally resonant acoustic metamaterials (LRAMs) evaluates performance on low-frequency wave attenuation. The LRAM is modeled as 1D chain system composed mass-in-mass unit cells connected by springs, geometrical nonlinearity achieved two lateral inerters linking lumped mass symmetrically with respect t...

The irregular wave disturbance attenuation problem for jacket-type offshore platforms involving the nonlinear characteristics is studied. The main contribution is that a digital-control-based approximation of optimal wave disturbances attenuation controller (AOWDAC) is proposed based on iteration control theory, which consists of a feedback item of offshore state, a feedforward item of wave for...

By using the methodology of multiobjective optimal design engineering systems, we consider problem weight-vibration Pareto optimization a dual mass flywheel with an aim to study feasibility its application in heavy-duty truck powertrains. The results obtained show following: solution considered does exist; inertia, stiffness, and damping parameters absorber optimized operating engine speed rang...