This research describes the spectrophotometric determination of methylene blue (MB) after shaker-assisted liquid-liquid microextraction combined with back-extraction (SALLME-BE). A hydrophobic deep ...eutectic solvent (DES) was used for extraction of MB from alkaline solutions (0.5 M NaOH). Then, the extracted dye was back-extracted into a hydrochloric acid solution (2 M). Decanoic acid and methyltrioctylammonium bromide were used, respectively as hydrogen bond donor and hydrogen bond acceptor constituents of the hydrophobic DES. The calibration graph was linear in the range of 2–170 ng mL−1. The recovery analysis of wastewater and river water samples verified that this method is practical for environmental monitoring.
•Shaker-assisted liquid-liquid microextraction of methylene blue•Application of deep eutectic solvent as environmentally friendly extraction solvent•Spectrophotometric quantification after back-extraction
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
In this paper, the problem of optimal robust fault detection (FD) for uncertain Lipschitz nonlinear systems is considered. A robust active fault detection approach for a class of the Lipschitz ...nonlinear systems in the presence of disturbances and parametric uncertainties is proposed, wherein the Lipschitz constant is assumed as one of the optimization parameters in the observer design. In addition to disturbance attenuation level, the fault sensitivity criterion based on
H
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index is also defined in the FD system design. Different criteria are defined as a weighted multi-objective linear matrix inequality optimization problem, and the optimal variables of the FD system are derived based on a newly defined cost function. A numerical example is provided to demonstrate the effectiveness of the proposed FD system. The results show the robustness of the proposed method against parametric uncertainty and nonlinear uncertainty as well.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
In this paper, a new fault detection approach for nonlinear Lipschitz systems based on observer method is proposed wherein the gain of the observer is obtained by optimal maximized Lipschitz constant ...and minimized disturbance attenuation level. The FD system is defined as a weighted LMI optimization problem in which the Lipschitz constant and disturbance attenuation level are assumed as decision variables. The projection lemma is used to reduce the conservatism of the proposed FD system. Maximization of the Lipschitz constant will result in robustness of the FD system against parametric and nonlinear uncertainties, while maintaining the fault sensitivity of the FD system and may further eliminate the problem of getting the exact value of the Lipschitz constant in practical applications. A single-link manipulator is provided to demonstrate the effectiveness of the proposed method.
Pitch angle control strategy has been applied to mitigate the influence of mechanical load and also output power control at above-rated wind speeds. In this paper, a wind turbine is modeled based on ...simplified two-mass model and an adaptive fractional-order non-singular fast terminal sliding mode controller (AFO-NFTSMC) is proposed based on individual pitch control strategy to control pitch angle of wind turbine against uncertainties and external disturbances. To do this, the single-blade approach is used and the wind turbine is divided into aerodynamics and mechanical subsystems and governing equations of each subsystem are derived. By designing and applying the AFO-NFTSMC to the two-mass model, system behavior is observed and simulated in terms of step and turbulent wind speed inputs. In addition, to verify the validity of the AFO-NFTSMC, the proposed controller is implemented in the FAST environment in which the wind speed profiles are generated using TurbSim. In order to analyze the environmental effects on the dynamic behavior of the system, the controller performance is explored in presence of parametric uncertainties. Simulation results reveal the priority and high-precision performance of the controller compared to conventional adaptive and adaptive sliding mode controller. Moreover, rotor speed tracking error is evaluated and demonstrated through different criteria.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
In this paper, a new robust fault diagnosis approach based on the combination of Bond Graph (BG) method and a robust observer is proposed. Different criteria including disturbance attenuation level, ...enhanced fault sensitivity and robustness against parametric uncertainties are considered in the proposed fault diagnosis system. A new form of analytical redundancy relations (ARRs), which is called error-based analytical redundancy relations (EARRs), is introduced and is used as the residuals for fault diagnosis purposes in considered uncertain linear systems. This form of the residuals is obtained using the output estimation error of the observer and satisfies considered criteria of the fault diagnosis system. The ARRs and state space representation of the system can be derived based on the BG model. The robust observer design is defined as an LMI problem in which the region of robustness against parametric uncertainty is achieved by the feasibility constraint of the obtained LMI. Finally, in order to show the performance of the proposed method, a quarter-car model is considered and different criteria are compared with the conventional ARRs method.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
•A fluorescence-based method for analysis of sulfide is presented.•The method shows high selectivity and sensitivity toward sulfide.•The applicability of the method was demonstrated via analysis of ...real samples.
With the rapid growth of agricultural and industrial sectors, a significant quantity of sulfide is released into water resources systems at an increasing rate. This has caused serious environmental problems, which calls for the development of sensitive and selective methods for determining sulfide in environmental samples. In this report, we employed carbon dots (C-dots) as fluorescence emitters and measured the decrease in their fluorescence intensity caused by Ag2S formation. Instead of having free Ag+ cation (which can interact with many other species besides sulfide) in the C-dot solution, we used iodide (I−) to convert Ag+ to one of the least soluble silver salts (i.e., AgI). While AgI interacts with sulfide to form Ag2S (because of the lower solubility of Ag2S), it remains stable against many other anions, thereby offering the method high selectivity. Under optimized experimental conditions, the developed method enabled quantifying sulfide in the range of 1–10 μM with the low detection limit of 0.48 μM. The applicability of the method was demonstrated by successful analysis of sulfide in a mineral water, a hot spring water, and an industrial wastewater sample.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
In this paper, the problem of robust Fault Detection (FD) for continuous time switched system is tackled using a hybrid approach by combination of a switching observer and Bond Graph (BG) method. The ...main criteria of an FD system including the fault sensitivity and disturbance attenuation level in the presence of parametric uncertainties are considered in the proposed FD system. In the first stage, an optimal switching observer based on state space representation of the BG model is designed in which simultaneous fault sensitivity and disturbance attenuation level are satisfied using H =H1 index. In the second stage, the Global Analytical Redundancy Relations (GARRs) of the switching system are derived based on the output estimation error of the observer, which is called Error-based Global Analytical Redundancy Relations (EGARRs). The parametric uncertainties are included in the EGARRs, which define the adaptive thresholds on the residuals. A constant term due to the effect of disturbance is also considered in the thresholds. In fact, a two-stage FD system is proposed wherein some criteria may be considered in each stage. The efficiency of the proposed method is shown for a two-tank system.
This paper deals with a new robust fault detection (FD) scheme for nonlinear Lipschitz systems wherein a robust nonlinear observer is used in combination with the Bond Graph (BG) method. In order to ...improve the efficiency of the classical Analytical Redundancy Relations (ARRs) FD scheme based on the BG method, a new form of the ARRs for the nonlinear Lipschitz systems is presented. This new form of the residuals is based on the output estimation error of the observer and is called Error-based Analytical Redundancy Relations (EARRs). The robustness against disturbances and parametric uncertainties in the FD system is achieved by the proposed method. Next, the integral form of the EARRs for the nonlinear Lipschitz system is presented that is robust in the sense of measurement noises as well. The BG model of a single link manipulator with revolute joints actuated by a DC motor is derived and the efficiency of the proposed method in comparison to the classical ARR method is shown in the simulation results.
In this paper, the position of a pulse width modulation (PWM)-driven pneumatic actuator has been controlled using a dynamic neural network (DNN) and Proportional Integral Derivative (PID) controller. ...The harmony search algorithm (HSA) has been used to unravel the optimization problem. The DNN controller is optimally designed to control the position of the actuator. As to the performance of the PID controller, it can assist the DNN controller to give better results. Therefore, an optimal hybrid scheme with both DNN and PID controllers based on HSA is suggested. A pneumatic circuit containing a fast-switching valve is used to reduce the complexity of the PWM-driven servo pneumatic system along with its cost price.
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NUK, OILJ, SAZU, UKNU, UL, UM, UPUK
This paper deals with robust fault detection (FD) of continuous time Lipschitz nonlinear switched systems based on observer method. A switched observer with average dwell time (ADT) approach is ...designed using projection lemma wherein the Lipschitz constant is maximized and simultaneously the effect of disturbances is attenuated effectively. Lipschitz constant maximization makes the fault detection system robust against parametric and nonlinear uncertainties. One more degree of freedom is provided by applying projection lemma, which could be used to obtain smaller ADT value and disturbance attenuation level of the observer. Some simulation results are given to demonstrate the efficiency and performance of the proposed FD scheme for nonlinear switched systems.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
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