In the ellipsoidal collapse model, the critical density for the collapse of a gravitationally bound object is a function of its mass. In the excursion set formalism, this translates into a moving barrier problem such that the mass function of dark matter haloes is given by the first crossing probability of a random walker across the barrier. In this paper, we study this first crossing probabili...

We present two reduced-dimensional, noncanonical Hamiltonian models for a neutrally buoyant underwater vehicle coupled to an internal moving mass. It is expected that these models will be useful in designing nonlinear control laws for underwater gliders as well as for spacecraft, atmospheric re-entry vehicles, and other vehicles which use internal moving mass actuators. To illustrate, we invest...

In this study, the active vibration control of a rectangular plate submerged in water was investigated. Mass dampers were attached to plate, and system modeled via assumed mode. Water is as an inviscid fluid with moving boundaries at fluid–solid interaction surfaces applied forces on being calculated by Bernoulli equation. The natural frequencies vacuum (for partial fully cases) found from nume...

A novel damage detection approach based on Auto-encoder neural network is proposed to identify in beam-like bridges subjected a moving mass. In this approach, several sensors are used measure structural vibration responses during mass across the bridge. An auto-encoder (AE) designed extract features from measured responses. fixed window cut out time-domain generate inputs of AE network. Moreove...

In previous work by the authors, Spectral Difference Method has been formulated in a framework with time-dependent moving deformable meshes. The framework has also been shown to preserve the design accuracy of the underlying high order temporal (explicit Runge-Kutta) and spatial discretization (Spectral Difference) methods. In this study, Spectral Difference method is further extended to deal w...

Laser footprint size and beam divergence angle tuning was found to affect LiDAR data accuracy and measurement precision because of beam axis shifting. The laser beam divergence angle is generally tunable in modern LiDAR systems in order to adapt to different application scenarios. Beam divergence angle can either be switched from one position to the other (i.e. 0.3mRad / 0.8 mRad), or be tuned ...