Search arXiv⌕ Search

arXiv · 0708.4412

Increasing the Efficiency of Energy Scavengers

Abstract

In this paper, a methodology for designing efficient energy scavengers is proposed. The scavenger consists of a cantilever beam on which piezoelectric films and a mass are mounted. The mass at the tip of the beam is known as the proof mass and the device is called either an energy scavenger or a beam-mass system. The proof mass is a permanent magnet, where in its vicinity attracting permanent magnets are placed. It is shown that when the magnets have appropriate strengths and are placed appropriately, the vibration of the beam-mass system can be amplified, thereby the scavenged energy is increased. Examples are given throughout the paper.

Explore related subjects

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Shahram M. Shahruz. 2007-09-26. Increasing the Efficiency of Energy Scavengers. https://arxiv.org/abs/0708.4412

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

Geometry-induced chaos and scaling near two singular limits of an eye-shaped billiard

We investigate how boundary geometry controls the coexistence of regular and chaotic motion in a static, eye-shaped billiard. A single control parameter continuously deforms the smooth, strictly convex boundary between two singular geometric limits. Across the sampled parameter range, chaotic layers coexist with regular islands and invariant curves that restrict phase-space transport. We derive analytical conditions for the existence of diagonal period-two orbits and determine the stability transitions of the axial period-two trajectories. We also establish the existence of invariant caustics near the boundary for every finite positive value of the control parameter. Numerical simulations reveal a nonmonotonic dependence of the average maximal Lyapunov exponent on the control parameter, withthe strongest sampled instability occurring at an intermediate geometry. The mean squared-angle envelope width associated with the sampled chaotic component decreases toward both singular limits, following power laws with fitted exponents of opposite signs and magnitudes close to two thirds. We further characterize a geometric response function and discuss the resulting analogy with continuous critical behavior. Our findings show how geometric deformation governs orbital stability, barriers to chaotic transport, and scaling properties in conservative billiard dynamics.

nlin.CD↗

Reduction of Decaying Navier--Stokes Turbulence to the Quantum Pendulum

The statistics of a classical flow is a problem of quantum mechanics in loop space, and not by analogy: the loop functional of any flow is the loop-ordered exponential of the covariant derivative $\partial+\mathrm{i}v/ν$. We follow this representation from the Navier--Stokes equation to the Euler ensemble, the fixed point of the loop equation regularized by polygons with $N$ sides. Near the turning angle $β=π$ an exact operator identity, followed by an asymptotic continuum step and without a saddle-point approximation, reduces the ensemble to two quantum pendulums, the Mathieu equation; this supersedes our earlier WKB evaluation. A Monte Carlo simulation up to $N=10^5$ confirms the reduction. Extreme turbulence has singularities at small scales, and, as in quantum field theory, we define it by this regularization and a renormalization: the leading power of $N$ is removed, and the turbulent viscosity $\tildeν$ remains as the single physical scale. This is a proposed definition of turbulence at infinite Reynolds number; its continuum spectrum is computed under a stated convergence condition, and its identification with physical turbulence is a hypothesis. The energy spectrum is a function of $κ=k\sqrt{\tildeν(t+t_0)}$ that falls as $1/k$ and then as $k^{-2}$. At $κ=\sqrt2$ it has a weak nonanalyticity: its second derivative diverges logarithmically. At a fixed wave number the decay is therefore singular at the finite time $t_*=2/(\tildeνk^2)-t_0$, when $t_*>0$, and the vorticity correlations oscillate in space with the period $\sqrt2\,π\sqrt{\tildeν(t+t_0)}$. Of the limits of the ensemble with structure, only the pendulum limit is taken at a critical point and has a bulk dissipation that vanishes with the viscosity. A companion paper compares it with simulations and experiments.

nlin.CD↗

Geometric Transition of Latent Dynamics in Intermittent Chaos: SVD-based Effective Dimension for Detection and Proactive Control

This paper investigates the geometric detection of latent dynamic transitions (where the latent space is defined as a finite-dimensional state space reconstructed via a delay-embedding Hankel matrix) in mutually coupled phase-locked loops (PLLs) exhibiting on-off intermittent chaos. We propose a data-driven approach to identify the transition of the effective dimension in latent dynamics as a precursor to physical bursting events. By applying Singular Value Decomposition (SVD) to a Hankel matrix constructed from high-resolution oversampled data, we extract the effective dimension that reflects the dynamical shift of intrinsic variables - from a synchronized two-dimensional manifold to a higher-dimensional chaotic state - prior to the actual burst. This geometric indicator enables a proactive, event-driven intervention using Pyragas-type delayed feedback control, which is activated only when the detected dimension exceeds a critical threshold. Simulation results demonstrate that this geometric precursor effectively compensates for control latencies and substantially reduces accumulated control energy compared to conventional continuous feedback. The findings establish a methodological strategy for stabilizing infinite-dimensional delayed systems by exploiting early warning signals embedded in dimensional transitions of latent dynamics.

nlin.CD↗