SUMMARYThis paper investigates the problem of state observer design for a class of nonlinear uncertain dynamical systems with interval time-varying delay and the one-sided Lipschitz condition. By constructing the novel Lyapunov-Krasovskii functional while utilizing the free-weighting matrices approach, the one-sided Lipschitz condition and the quadratic inner-bounded condition, novel sufficient conditions, which guarantee the observer error converge asymptotically to zero, are established for a class of nonlinear dynamical systems with interval time-varying delay in terms of the linear matrix inequalities. The computing method for observer gain matrix is given. Finally, two examples illustrate the effectiveness of the proposed method.

Coronavirus disease 2019 (COVID-19) is a challenging global problem. COVID-19 has caused shocks to various urban systems, and the tourism industry is no exception. We analyzed the impact on vacation rentals by conducting diachronic data mining on nearly 10 GB of rental data (calendar, listings, and reviews) in twelve highly internationalized megacities distributed across Asia, Europe, America, and Oceania based on the data set from the Inside Airbnb website. All twelve cities were adversely affected. The specific time of the impact is related to the pandemic's outbreak and enforced lockdowns policies. Affected by the epidemic, reservation rates decreased, tourists preferred renting in suburbs instead of city centers, the proportion of foreign tourists in all destinations dropped sharply, tourist sentiment scores fluctuated dramatically especially among foreigners, and people focused less on tourism related activities. This study reveals the changing illustrations of vacation rentals in highly internationalized megacities under the pandemic's influence. It offers a methodological assessment framework to monitor the hospitality sector over time and aims to serve as a reference for preparedness in similar cities worldwide.

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The use of detailed chemical reaction mechanisms of kerosene is still very limited in analyzing the combustion process in the combustion chamber of the aircraft engine. In this work, a new reduced chemical kinetic mechanism for fuel n-decane, which selected as a surrogate fuel for kerosene, containing 210 elemental reactions (including 92 reversible reactions and 26 irreversible reactions) and 50 species was developed, and the ignition and combustion characteristics of this fuel in both shock tube and flat-flame burner were kinetic simulated using this reduced reaction mechanism. Moreover, the computed results were validated by experimental data. The calculated values of ignition delay times at pressures of 12, 50 bar and equivalence ratio is 1.0, 2.0, respectively, and the main reactants and main products mole fractions using this reduced reaction mechanism agree well with experimental data. The combustion processes in the individual flame tube of a heavy duty gas turbine combustor were simulated by coupling this reduced reaction mechanism of surrogate fuel n-decane and one step reaction mechanism of surrogate fuel C12H23 into the computational fluid dynamics software. It was found that this reduced reaction mechanism is shown clear advantages in simulating the ignition and combustion processes in the individual flame tube over the one step reaction mechanism.

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