The article investigates robust dynamic output feedback (DOF) stabilization for uncertain time-varying delays singular Markovian jump systems (SMJSs). First, by using improved Lyapunov-Krasovskii functional, sufficient conditions of robust admissibility (namely regularity, non-impulsiveness, and asymptotic stability) for unforced nominal time-varying delays SMJSs are given. Second, by constructing a DOF controller such that the resulting closed-loop system satisfies robust admissibility, the robust DOF stabilization problem is solved in terms of linear matrix inequalities via orthogonal complement technique. Finally, the availability and practicality of the prime results are certified by two numerical examples and a practical example of the oil catalytic cracking process.

With the development of flexible surface-enhanced Raman spectroscopy (SERS) substrates that can realize rapid in situ detection, the SERS technique accompanied by miniaturized Raman spectrometers holds great promise for point-of-care testing (POCT). For an in situ detection strategy, constructing high-performance flexible and transparent SERS substrates through a facile and cost-effective fabrication method is critically important. Herein, we present a simple method for fabricating a large-area flexible and transparent SERS substrate consisting of a silver-nanoparticle-grafted wrinkled polydimethylsiloxane (Ag NPs@W-PDMS) film, using a surface-wrinkling technique and magnetron sputtering technology. By characterizing rhodamine 6G as a probe molecule with a portable Raman spectrometer, the flexible SERS substrate shows a low detection limit (10–7 M), a high enhancement factor (6.11 × 106), and excellent spot–spot and batch–batch reproducibilities (9.0% and 4.2%, respectively). Moreover, the Ag NPs@W-PDMS substrate maintains high SERS activity under bending and twisting mechanical deformations of over 100 cycles, as well as storage in air for 30 days. To evaluate its practical feasibility, in situ detection of malachite green on apple and tomato peels is performed with a detection limit of 10–6 M. In addition, for point-of-care analysis, we develop a wireless transmission system to transmit the collected SERS spectral data to a computer in real time for signal processing and analysis. Therefore, the proposed Ag NPs@W-PDMS SERS substrate fabricated through a simple and mass-producible method, combined with the utilization of a portable Raman spectrometer and wireless communication, offers a promising opportunity to extend the SERS technique from the laboratory to POCT applications.

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Flow field predictions of various turbulent lubrication models are compared with the existing experimental data of turbulent Couette flow and shear-induced countercurrent flow. [S0742-4787(00)00502-6]

A study of the interaction between an initially columnar intake vortex (hereinafter referred to as the primary vortex) and vortex structures in the wake of a single sphere (hereinafter referred to as secondary vortices) is performed using a series of flow visualization experiments, in which a sphere is towed toward a stationary vortex with ambient axial flow and gradually decelerated to rest at a specified distance from the vortex core axis. Both the primary vortex core and the boundary layer of the sphere are visualized using laser-induced fluorescent dyes of two different colors, which are illuminated either with a laser sheet or a laser volume. The strength of the primary vortex is measured using particle-image velocimetry, which is also used to measure the strength of the secondary vortices in select cases. The form of the sphere wake in the presence of the primary vortex and the effect of the induced velocity from the secondary vortices on the primary vortex are studied for different values of the vortex-sphere separation distance, the sphere diameter, and the primary vortex core radius. Weak secondary vortices are observed to induce formation of small-amplitude waves of varying core area on the primary vortex, eventually forming a turbulent sheath surrounding the primary vortex. Stronger secondary vortices have an increasingly strong effect on the primary vortex, including large-amplitude variation in core area, outward ejection of fluid from the primary vortex core, and breakdown of the primary vortex. [S0098-2202(00)01403-6]