SUMMARYThis paper deals with the problem of exponential H ∞ filtering for a class of continuous-time switched linear system with interval time-varying delay. The time delay under consideration includes two cases: one is that the time delay is differentiable and bounded with a constant delay-derivative bound, whereas the other is that the time delay is continuous and bounded. Switched linear filters are designed to ensure that the filtering error systems under switching signal with average dwell time are exponentially stable with a prescribed H ∞ noise attenuation level. Based on the free-weighting matrix approach and the average dwell technology, delay-dependent sufficient conditions for the existence of such a filter are derived and formulated in terms of linear matrix inequalities (LMIs). By solving that corresponding LMIs, the desired filter parameterized matrices and the minimal average dwell time are obtained. Finally, two numerical examples are presented to demonstrate the effectiveness of the developed results.
a b s t r a c tGeotechnical applications often involve large displacements of structural elements, such as penetrometers or footings, in soil. Three numerical analysis approaches capable of accounting for large deformations are investigated here: the implicit remeshing and interpolation technique by small strain (RITSS), an efficient Arbitrary Lagrangian-Eulerian (EALE) implicit method and the Coupled Eulerian-Lagrangian (CEL) approach available as part of commercial software. The theoretical basis and implementation of the methods are discussed before their relative performance is evaluated through four benchmark cases covering static, dynamic and coupled problems in geotechnical engineering. Available established analytical and numerical results are also provided for comparison purpose. The advantages and limitation of the different approaches are highlighted. The RITSS and EALE predict comparable results in all cases, demonstrating the robustness of both in-house codes. Employing implicit integration scheme, RITSS and EALE have stable convergence although their computational efficiency may be low for high-speed problems. The CEL is commercially available, but user expertise on element size, critical step time and critical velocity for quasi-static analysis is required. Additionally, mesh-independency is not satisfactorily achieved in the CEL analysis for the dynamic case.
The emission of gaseous pollutants
from the combustion of fossil
fuels is believed to be one of the most serious environmental challenges
in the 21st century. Given the increasing demands of multipollutant
control (MPC) via adsorption or catalysis technologies, such as NO
x
, volatile organic compounds (VOCs), heavy
metals (Hg etc.), and ammonia, and considering investment costs and
site space, the use of existing equipment, especially the selective
catalytic reduction (SCR) system to convert pollutants into harmless
or readily adsorbed substances, is one of the most practical approaches.
Consequently, many efforts have been directed at achieving the simultaneous
elimination of multipollutants in a SCR convertor, and this method
has been widely used to mitigate the stationary emission of NO
x
. However, the development of active, selective,
stable, and multifunctional catalysts/adsorbents suitable for large-scale
commercialization remains challenging. Herein, we summarize recent
works on the applications of SCR in MPC, describing the approaches
of (i) SCR + VOCs oxidation, (ii) SCR + heavy metal control, and (iii)
SCR + NH3 reduction to reveal that the efficiency of simultaneous
elimination depends on catalyst composition and flue gas parameters.
Furthermore, the synergistic promotional/inhibitory effects between
SCR and VOCs/ammonia/heavy metal oxidations are shown to be the key
to the feasibility of the reactions.
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