This paper is devoted to solve the problems on simultaneous actuator and sensor fault estimations as well as the nonfragile fault-tolerant control (FTC) for a kind of Markovian jump systems with faults and disturbances. First, the considered system is converted to an augmented system by putting the sensor fault into the new state. Then, an adaptive observer is designed for the descriptor system with the actuator fault adjusted by the designed adaptive law. Based on the estimated actuator faults, an output-feedback-based FTC strategy is proposed to stabilize the closed-loop system against actuator and sensor faults, and disturbances, while showing robustness for the control gain perturbations. Sufficient conditions for the existences of the observer and controller are provided in forms of linear matrix inequalities. Finally, a practical application is given to express the validation and effectiveness of the proposed method.

Refractive index (RI) and temperature (T) are both critical environmental parameters for environmental monitoring, food production, and medical testing. The paper develops a D-shaped photonic crystal fiber (PCF) sensor to measure RI and T simultaneously. Its cross-sectional structure encompasses a hexagonal-hole lattice, with one hole selectively filled with toluene for temperature sensing. By coating the D-shaped surface of the PCF with a metal film and a MoS₂ film, the refractive index-detection channel is formed. Numerical results demonstrate that RI and T can be reflected in the same spectrum, without any interference caused by the two parameters with each other. At an environmental RI of 1.26–1.38, its maximum RI sensitivity is up to 5400 nm/RIU. At a temperature of 20–80 °C, its temperature sensitivity reaches −1.2 nm/°C. This design allows for a broad operational spectrum and an extensive measurement range, which makes it particularly suitable for applications requiring low-RI detection. Moreover, the resonance strength of the sensor is significantly enhanced by introducing a two-dimensional material MoS₂ on the D-surface. Specifically, it reaches 195,149 dB/m when RI = 1.34 at 30 °C. This is much higher than that of most previous studies, and the requirements for inspection equipment can be lowered in this case. These results are essential for progress in simultaneously detecting RI and T.

In this article, an asynchronous output-feedback controller is proposed for a class of Markovian jump systems (MJSs) with generally bounded transition rates (TRs). Specifically, two cases have been considered, one of which assumes the TR being completely unknown, while the other specifies the TR range. In particular, the designed asynchronous output-feedback controller is independent of the system modes, implying a sustainable controlling behavior against unavailable system modes. It is worth noting that the mode-dependent controller can be treated as a special case of the independent one. Furthermore, the existing conditions of such a controller are acquired in terms of linear matrix inequalities. Finally a practical example, concerning a single-machine infinite-bus power system, is given to confirm the feasibility of the proposed controller.

We propose a novel design of photonic crystal fiber to achieve the single-polarization single-mode transmission. The topology of this design only employs, with a view to simplicity and stability, uniformly sized circular air holes, and they are all regularly latticed in a pure-silica background. Guiding properties are studied by use of the full-vector finite element method, combined with perfectly matched layers as absorbing boundary conditions. It has been found that, increasing the hole-to-pitch ratio can be performed to broaden the SPSM band, however subject to a qualification that the radio should be inadequate to open a bandgap. In addition, influences of the ring number and the inner cladding coverage on transmission characteristics have been thoroughly investigated. An optimized sample is deliberately designed to offer an SPSM band with width of 120nm, centered at =1.55μm. Moreover, the proposed design demonstrates low confinement loss, high nonlinear coefficient, as well as excellent bending resistance.

Ultrasensitive refractive index (RI) sensing based on novel Vernier-effect demodulation through a single fiber Fabry–Perot interferometer (FFPI) is proposed and demonstrated. A core-offset fiber pair is used as an FFPI for RI sensing. An artificial reference spectrum (ARS) obtained by modulating and extracting a sensing spectrum twice is demonstrated. The Vernier effect is realized by superimposing the sensing spectrum with the ARS. By optimizing the cavity length of the FFPI and the free spectrum range (FSR) of the ARS, an ultrahigh sensitivity of 133948.33 nm/refractive index unit (RIU) with a magnification factor of 118.38 in the RI range of 1.3340~1.3354 is obtained. The magnification factor based on the ARS can be conveniently adjusted. Furthermore, the proposed scheme is suitable for various interferometric sensing applications.