581 research outputs found
Preparation and field-induced electrical properties of perovskite relaxor ferroelectrics
(111)-oriented and random oriented Pb0.8Ba0.2ZrO3 (PBZ) perovskite relaxor ferroelectric thin films were fabricated on Pt(111)/TiOx/SiO2/Si substrate by sol-gel method. Nano-scaled antiferroelectric and ferroelectric two-phase coexisted in both (111)-oriented and random oriented PBZ thin film. High dielectric tunability (i = 75%, E = 560 kV/ cm ) and figure-of-merit (FOM ~ 236) at room temperature was obtained in (111)-oriented thin film. Meanwhile, giant electrocaloric effect (ECE) (AT = 45.3 K and AS = 46.9 JK-1kg-1 at 598 kVcm-1) at room temperature (290 K), rather than at its Curie temperature (408 K), was observed in random oriented Pb0.8Ba0.2ZrO3 (PBZ) thin film, which makes it a promising material for the application to cooling systems near room temperature. The giant ECE as well as high dielectric tunability are attributed to the coexistence of AFE and FE phases and field-induced nano-scaled AFE to FE phase transition
Stochastic Averaging Principle for Dynamical Systems with Fractional Brownian Motion
Stochastic averaging for a class of stochastic differential equations (SDEs)
with fractional Brownian motion, of the Hurst parameter H in the interval (1/2,
1), is investigated. An averaged SDE for the original SDE is proposed, and
their solutions are quantitatively compared. It is shown that the solution of
the averaged SDE converges to that of the original SDE in the sense of mean
square and also in probability. It is further demonstrated that a similar
averaging principle holds for SDEs under stochastic integral of pathwise
backward and forward types. Two examples are presented and numerical
simulations are carried out to illustrate the averaging principle
DFR: Depth from Rotation by Uncalibrated Image Rectification with Latitudinal Motion Assumption
Despite the increasing prevalence of rotating-style capture (e.g.,
surveillance cameras), conventional stereo rectification techniques frequently
fail due to the rotation-dominant motion and small baseline between views. In
this paper, we tackle the challenge of performing stereo rectification for
uncalibrated rotating cameras. To that end, we propose Depth-from-Rotation
(DfR), a novel image rectification solution that analytically rectifies two
images with two-point correspondences and serves for further depth estimation.
Specifically, we model the motion of a rotating camera as the camera rotates on
a sphere with fixed latitude. The camera's optical axis lies perpendicular to
the sphere's surface. We call this latitudinal motion assumption. Then we
derive a 2-point analytical solver from directly computing the rectified
transformations on the two images. We also present a self-adaptive strategy to
reduce the geometric distortion after rectification. Extensive synthetic and
real data experiments demonstrate that the proposed method outperforms existing
works in effectiveness and efficiency by a significant margin
Revisiting Rolling Shutter Bundle Adjustment: Toward Accurate and Fast Solution
We propose a robust and fast bundle adjustment solution that estimates the
6-DoF pose of the camera and the geometry of the environment based on
measurements from a rolling shutter (RS) camera. This tackles the challenges in
the existing works, namely relying on additional sensors, high frame rate video
as input, restrictive assumptions on camera motion, readout direction, and poor
efficiency. To this end, we first investigate the influence of normalization to
the image point on RSBA performance and show its better approximation in
modelling the real 6-DoF camera motion. Then we present a novel analytical
model for the visual residual covariance, which can be used to standardize the
reprojection error during the optimization, consequently improving the overall
accuracy. More importantly, the combination of normalization and covariance
standardization weighting in RSBA (NW-RSBA) can avoid common planar degeneracy
without needing to constrain the filming manner. Besides, we propose an
acceleration strategy for NW-RSBA based on the sparsity of its Jacobian matrix
and Schur complement. The extensive synthetic and real data experiments verify
the effectiveness and efficiency of the proposed solution over the
state-of-the-art works. We also demonstrate the proposed method can be easily
implemented and plug-in famous GSSfM and GSSLAM systems as completed RSSfM and
RSSLAM solutions
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