3,679 research outputs found
Stabilization of Cascaded Two-Port Networked Systems Against Nonlinear Perturbations
A networked control system (NCS) consisting of cascaded two-port
communication channels between the plant and controller is modeled and
analyzed. Towards this end, the robust stability of a standard closed-loop
system in the presence of conelike perturbations on the system graphs is
investigated. The underlying geometric insights are then exploited to analyze
the two-port NCS. It is shown that the robust stability of the two-port NCS can
be guaranteed when the nonlinear uncertainties in the transmission matrices are
sufficiently small in norm. The stability condition, given in the form of
"arcsin" of the uncertainty bounds, is both necessary and sufficient.Comment: 8 pages, in preparation for journal submissio
Feature-preserving image restoration and its application in biological fluorescence microscopy
This thesis presents a new investigation of image restoration and its application to
fluorescence cell microscopy. The first part of the work is to develop advanced image
denoising algorithms to restore images from noisy observations by using a novel featurepreserving
diffusion approach. I have applied these algorithms to different types of
images, including biometric, biological and natural images, and demonstrated their
superior performance for noise removal and feature preservation, compared to several
state of the art methods. In the second part of my work, I explore a novel, simple and
inexpensive super-resolution restoration method for quantitative microscopy in cell
biology. In this method, a super-resolution image is restored, through an inverse process,
by using multiple diffraction-limited (low) resolution observations, which are acquired
from conventional microscopes whilst translating the sample parallel to the image plane,
so referred to as translation microscopy (TRAM). A key to this new development is the
integration of a robust feature detector, developed in the first part, to the inverse process
to restore high resolution images well above the diffraction limit in the presence of strong
noise. TRAM is a post-image acquisition computational method and can be implemented
with any microscope. Experiments show a nearly 7-fold increase in lateral spatial
resolution in noisy biological environments, delivering multi-colour image resolution of
~30 nm
Experimental analysis for the effect of dynamic capillarity on stress transformation in porous silicon
The evolution of real-time stress in porous silicon(PS) during drying is investigated using micro-Raman spectroscopy. The results show that the PS sample underwent non-negligible stress when immersed in liquid and suffered a stress impulsion during drying. Such nonlinear transformation and nonhomogeneneous distribution of stress are regarded as the coupling effects of several physical phenomena attributable to the intricate topological structure of PS. The effect of dynamic capillarity can induce microcracks and even collapse in PSstructures during manufacture and storage.This work is funded by the National Natural Science
Foundation of China Contract Nos. 10732080 and
10502014
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