342,099 research outputs found
Robust H2/H∞ filtering for linear systems with error variance constraints
Copyright [2000] IEEE. This material is posted here with permission of the IEEE. Such permission of the IEEE does not in any way imply IEEE endorsement of any of Brunel University's products or services. Internal or personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution must be obtained from the IEEE by writing to [email protected]. By choosing to view this document, you agree to all provisions of the copyright laws protecting it.In this correspondence, we consider the robust H2/H∞ filtering problem for linear perturbed systems with steady-state error variance constraints. The purpose of this multiobjective problem is to design a linear filter that does not depend on the parameter perturbations such that the following three performance requirements are simultaneously satisfied. (1) The filtering process is asymptotically stable. (2) The steady-state variance of the estimation error of each state is not more than the individual prespecified value. (3) The transfer function from exogenous noise inputs to error state outputs meets the prespecified H∞ norm upper bound constraint. We show that in both continuous and discrete-time cases, the addressed filtering problem can effectively be solved in terms of the solutions of a couple of algebraic Riccati-like equations/inequalities. We present both the existence conditions and the explicit expression of desired robust filters. An illustrative numerical example is provided to demonstrate the flexibility of the proposed design approac
A remark on the Hard Lefschetz Theorem for K\"ahler orbifolds
We give a proof of the hard Lefschetz theorem for orbifolds that does not
involve intersection homology. This answers a question of Fulton. We use a
foliated version of the hard Lefschetz theorem due to El Kacimi
Thermal Entanglement in Ferrimagnetic Chains
A formula to evaluate the entanglement in an one-dimensional ferrimagnetic
system is derived. Based on the formula, we find that the thermal entanglement
in a small size spin-1/2 and spin-s ferrimagnetic chain is rather robust
against temperature, and the threshold temperature may be arbitrarily high when
s is sufficiently large. This intriguing result answers unambiguously a
fundamental question: ``can entanglement and quantum behavior in physical
systems survive at arbitrary high temperatures?"Comment: 4 pages, 3 figure
Vision-based hand gesture interaction using particle filter, principle component analysis and transition network
Vision-based human-computer interaction is becoming important nowadays. It offers natural interaction with computers and frees users from mechanical interaction devices, which is favourable especially for wearable computers. This paper presents a human-computer interaction system based on a conventional webcam and hand gesture recognition. This interaction system works in real time and enables users to control a computer cursor with hand motions and gestures instead of a mouse. Five hand gestures are designed on behalf of five mouse operations: moving, left click, left-double click, right click and no-action. An algorithm based on Particle Filter is used for tracking the hand position. PCA-based feature selection is used for recognizing the hand gestures. A transition network is also employed for improving the accuracy and reliability of the interaction system. This interaction system shows good performance in the recognition and interaction test
Single-photon transport in a one dimentional waveguide coupling to a hybrid atom-optomechanical system
We explore theoretically the single-photon transport in a single-mode
waveguide that is coupled to a hybrid atom-optomechanical system in a strong
optomechanical coupling regime. Using a full quantum real-space approach,
transmission and reflection coefficients of the propagating single-photon in
the waveguide are ob- tained. The influences of atom-cavity detuning and the
dissipation of atom on the transport are also studied. Intriguingly, the
obtained spectral features can reveal the strong light-matter interaction in
this hybrid system.Comment: 7pages, 8figure
Pseudogap, competing order and coexistence of staggered flux and d-wave pairing in high-temperature superconductors
We study the t-J-V model of a doped Mott insulator in connection to high-T_c
superconductors. The nearest neighbor Coulomb interaction (V) is treated
quantum mechanically on equal footing as the antiferromagnetic exchange
interaction (J). Motivated by the SU(2) symmetry at half-filling, we construct
a large-N theory which allows a systematic study of the interplay between
staggered flux order and superconductivity upon doping. We solve the model in
the large-N limit and obtain the ground state properties and the phase diagram
as a function of doping. We discuss the competition and the coexistence of the
staggered flux and the d-wave superconductivity in the underdoped regime and
the disappearance of superconductivity in the overdoped regimeComment: 5 pages, 3 figures, published versio
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