Herein, we demonstrate the effectiveness of surface-enhanced Raman scattering (SERS) to detect trace concentration of potentially harmful imidacloprid pesticide. To achieve this ultimate objective, a ...rapid and highly effective methodology for the fabrication of active and stable porous silicon (PSi) plated palladium nanoparticles (PdNPs) SERS substrates by an electrochemical anodization and immersion plating routes was applied. The PSi layers were fabricated by the electrochemical anodization of a silicon wafer in ethanoic fluoride solution, followed by uniformly deposition of PdNPs via a simple immersion plating technique. The structural features and morphology of fabricated frameworks of PSi-Pd NPs have been investigated by field emission scanning electron microscopy (FE-SEM) with energy dispersive X-ray (EDX), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FT-IR) spectra. The PSi substrate demonstrates a meso-porous morphology with good distribution, good pore density and average pore sizes around 20 nm. The SERS performance of Si-Pd NPs and PSi-Pd NPs substrates has been examined taking imidacloprid (an insecticide) as a target analyte. The SERS signal of imidacloprid using PSi-Pd NPs substrate exhibited immense enhancement compared to the Si-Pd NPs substrate. The active substrate revealed excellent detectable performance with a concentration as low as 10
M imidacloprid and an enhancement factor (EF) of 1.2 × 10
. This large EF is fundamentally ascribed to the combined effect of the electromagnetic improvement and charge transfer mechanisms. Additionally, no aging effect was observed for the present substrates kept in air for two weeks. Striking enhancement in Raman spectral signals obtained with the current PSi-Pd NPs substrates can provide a simple and smooth platform towards the sensitive detection of various target analytes.
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•Importance of various device designs for different functional layers used in tandem cells.•Crucial role of cell design for efficient light-management.•R&D undertaken in real world ...conditions and its chances for scaleup.•Trends in 3-Terminal tandem devices and its prospects.
Successful integration of perovskite cell with silicon cell to form a tandem solar device has shown tremendous potential for outperforming the state-of-the-art single junction silicon devices. This tandem approach has enabled high efficiencies up to 29% within a short period of time and one can find sufficient work and various strategies being applied to enhance the efficiency in these devices. At this point in time, a compilation of all these studies, with a critical review and perspectives is extremely relevant and essential. With this motivation the present review has been brought out, with all achievements attained so far by optimizing various components namely the electron/hole transport layer and absorber layer, functional layers in bottom cell, transparent contacts, deposition techniques and the innovative light management tactics used. The review also outlines the solutions proposed by various researchers to overcome the challenges that restrict the efficiency of tandem strategy in three distinct configurations, namely, monolithic (2T), four terminal (4T) and three terminal (3T) configurations. Finally, the perspectives provide real insights into choosing suitable materials, techniques and methods and achieve efficiencies near and beyond Shockley Queisser limit, thus spiking high hopes that this device would be the dominant energy conversion device in future.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Quantum dot enhancement film (QDEF) working in tandem with a blue light-emitting-diode (LED) back-light-unit (BLU) has been recently used in liquid crystal display (LCD) to minimize the cross talks ...between the polarized emitting B-, G-, and R-light. However, they still exhibit a fundamental and considerable emitting-light-power loss from QDEF because of the light absorption loss in resin and transparent films of QDEF. In this work, we propose and demonstrate the superiority of the LCD using blue-(B-), green-(G-), and red-(R-) perovskite-quantum-dot (PrQD) functional CFs coupled with a blue LED BLU. This LCD using PrQD functional CFs and a blue LED BLU features cross-talk free spectra of polarized emitting B-, G-, and R-light, maximizing the LCD color gamut and exhibiting a world record performance of over 102.7% (137%) of Rec.2020 standard (NTSC standard). Theoretically, such an improvement in color gamut would facilitate unlimited scaling-down of the pixel leading to super ultra-high resolution LCD.
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Internal Combustion (IC) engines are prevalent in the process sector, and maintaining sufficient Air-Fuel Ratio (AFR) regulation in their fuel system is crucial for enhanced engine performance, fuel ...economy, and environmental safety. Faults in the AFR system's sensors cause the engine to shut down, hence, fault tolerance is essential. In order to avoid engine shutdown, this paper offers a novel Active Fault-Tolerant Control System (AFTCS) for air-fuel ratio control of an Internal Combustion (IC) engine in a process plant. In the Fault Detection and Isolation (FDI) unit, the proposed AFTCS uses a nonlinear regression-based observer model for analytical redundancy. The suggested system was simulated in the MATLAB / Simulink environment. The proposed system was tested at two different speeds (300 r/min and 600 r/min) and the results show that the system's response is within the acceptable bound without compromising the stability. The findings also demonstrate the higher fault tolerance capability for sensor defects of the AFR control system, particularly for the MAP sensor (at 300 r/min) in terms of reduced oscillatory response in comparison to the current literature. Compared to the linear regression-based and Genetic Algorithm (GA) based model, the nonlinear regression-based model results in a more accurate estimation of the faulty sensors. The proposed model is also efficient in terms of computation power and response time.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Polyvinyl alcohol (PVA) incorporated with various amounts of ammonium iodide salt (NH
4
I) composite polymer electrolyte films were prepared via the casting process. The XRD analysis, as a tool for ...structural investigation, confirms the polymer electrolytes formation. The transmittances of the studied samples are decreased with increasing NH
4
I fillers. The UV–Vis absorption spectra are shifted to the higher wavelengths, which indicate their importance for light shielding devices. The bandgaps decrease with the increase in NH
4
I content, attributed to the increase in the crystallite size. The calculated Urbach energy was found to increase with increasing NH
4
I salt fillers. The samples' optical limiting is carefully investigated using a He–Ne laser beam of wavelength = 632.8 nm. This result enhances light absorption behavior and makes the material suitable for optical UV-protection devices. The correlation between dielectric properties and conductivity is also understood and discussed. The dielectric permittivity
ε
' of the samples is associated with the dipole, and polarization increased with the addition of NH
4
I salt content as the particle size increased according to XRD analysis. AC impedance spectroscopy was carried out to disclose the PVA doped with NH
4
I polymer electrolyte films as a function of various NH
4
I salt fillers. The analysis via complex electric modulus gives abnormal behavior by adding NH
4
I salt content, where the minimization of the electrode polarization can be achieved. Our results indicate that the newly designed composite polymeric electrolyte films are commonly appropriate for electronic and optoelectronic devices.
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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
Fault-tolerant control systems (FTCS) are used in safety and critical applications to improve reliability and availability for sustained operation in fault situations. These systems may be used in ...process facilities to reduce significant production losses caused by irregular and unplanned equipment tripping. Internal combustion (IC) engines are widely used in the process sector, and efficient air–fuel ratio (AFR) regulation in the fuel system of these engines is critical for increasing engine efficiency, conserving fuel energy, and protecting the environment. In this paper, a hybrid fault-tolerant control system has been proposed, being a combination of two parts which are known as an active fault-tolerant control system and a passive fault-tolerant control system. The active part has been designed by using the genetic algorithm-based fault detection and isolation unit. This genetic algorithm provides estimated values to an engine control unit in case of a fault in any sensor. The passive system is designed by using the higher-order sliding mode control with an extra fuel actuator in the fuel supply line. The performance of the system was tested experimentally in MATLAB/Simulink environment. Based on the simulation results, the designed system can sustain the AFR despite sensor failures. A new method of managing the AFR of an IC engine has been demonstrated in this study, and it is highly capable, robust, reliable, and highly effective. A comparison with the existing works found in the literature also proves its superior performance. By inserting the fault in each sensor, it was clearly observed that proposed HFTCS was much better than the existing model as it was more fault-tolerant due to its ability to work in both online and offline modes. It also provided an exact value of 14.6 of AFR without any degradation.
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Safety and critical applications employ fault-tolerant control systems (FTCS) to increase reliability and availability in the event of a failure of critical components. Process facilities may employ ...these technologies to cut down on production losses caused by equipment failures that occur on an irregular or unscheduled basis. Air–fuel ratio (AFR) adjustment in the fuel system of internal combustion engines (ICE) is crucial for enhancing engine efficiency, saving fuel energy, and safeguarding the environment. This paper proposes a novel hybrid fault-tolerant control system (HFTCS) for controlling the AFR in ICEs that combines the features of both an active fault-tolerant control system (AFTCS) and a passive fault-tolerant control system (PFTCS). The fault detection and isolation (FDI) unit is designed using fuzzy logic (FL) as part of an AFTCS to give estimated sensor values to the engine controller when the sensor becomes faulty. Super-twisting sliding mode control (ST-SMC) is implemented as part of a PFTCS to maintain AFR by adjusting the throttle actuator in the fuel supply line under faulty conditions. Lyapunov stability analysis is also performed to make sure that the system remains stable in both normal and faulty conditions. According to the results in the Matlab/Simulink environment, the suggested system stays robust and stable during sensor faults. In faulty situations, it also maintains the AFR at 14.6 without any degradation, and a comparison with previous studies is carried out. The study shows that the suggested approach is an innovative and highly dependable solution for AFR control in ICEs, preventing engine shutdown and output loss for higher profitability.
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Faults frequently occur in the sensors and actuators of process machines to cause shutdown and process interruption, thereby creating costly production loss. centrifugal compressors (CCs) are the ...most used equipment in process industries such as oil and gas, petrochemicals, and fertilizers. A compressor control system called an anti-surge control (ASC) system based on many critical sensors and actuators is used for the safe operation of CCs. In this paper, an advanced active fault-tolerant control system (AFTCS) has been proposed for sensor and actuator faults of the anti-surge control system of a centrifugal compressor. The AFTCS has been built with a dedicated fault detection and isolation (FDI) unit to detect and isolate the faulty part as well as replace the faulty value with the virtual redundant value from the observer model running in parallel with the other healthy sensors. The analytical redundancy is developed from the mathematical modeling of the sensors to provide estimated values to the controller in case the actual sensor fails. Dual hardware redundancy has been proposed for the anti-surge valve (ASV). The simulation results of the proposed Fault-tolerant control (FTC) for the ASC system in the experimentally validated CC HYSYS model reveal that the system continued to operate in the event of faults in the sensors and actuators maintaining system stability. The proposed FTC for the ASC system is novel in the literature and significant for the process industries to design a highly reliable compressor control system that would continue operation despite faults in the sensors and actuators, hence preventing costly production loss.
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Cyber-threats are becoming a big concern due to the potential severe consequences of such threats is false data injection (FDI) attacks where the measures data is manipulated such that the detection ...is unfeasible using traditional approaches. This work focuses on detecting FDIs for phasor measurement units where compromising one unit is sufficient for launching such attacks. In the proposed approach, moving averages and correlation are used along with machine learning algorithms to detect such attacks. The proposed approach is tested and validated using the IEEE 14-bus and the IEEE 30-bus test systems. The proposed performance was sufficient for detecting the location and attack instances under different scenarios and circumstances.
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•A novel Au@PPy-C/SnO2 nanocomposite photocatalyst via a simple wet chemical methodology.•Ultrafast photodegradation of imidacloprid insecticide under visible light ...illumination.•Efficient charge carrier separation was detected due to enhanced light absorption.•The rate constant (k) of active photocatalyst is 4 times larger than the undoped photocatalyst.•The Au@PPy-C/SnO2 photocatalyst exhibits excellent stability and reusability.
Highly precise, determined and mind provoking steps are must for efficacious designing of smart visible-light photocatalysts. Herein, we successfully designed an ultrafast visible-light responsive photocatalyst comprising of SnO2, polypyrrole doped carbon black (PPy-C) and gold nanoparticles (Au NPs) by a simple and reliable approach. XRD, FTIR, XPS, FESEM, TEM and UV–vis spectroscopic tools were employed for comprehensive characterization of synthesized nanostructures. XPS and XRD investigations confirmed the establishment of ternary photocatalyst among SnO2, PPy-C and Au. TEM analysis showed that synthesized SnO2 material possessed irregular nanorods of 20–100 nm length and 20 nm diameter. The PPy-C polymer combination has beads or dumbbell shape morphology intertwined with SnO2 while dispersed Au NPs can be easily seen along with PPy-C and SnO2 nanostructures. The bandgap energy (Eg) for pristine SnO2, PPy-C/SnO2 and Au@PPy-C/SnO2 nanocomposite was found to be 3.55, 3.22 and 2.85 eV, respectively. The photocatalytic performance of each newly produced photocatalyst was evaluated under visible light using imidacloprid (an insecticide derivative) and methylene blue (MB) dye as target pollutants. Among different tested photocatalysts, the newly created Au@PPy-C/SnO2 trio combination was proven to be the most proficient with 93.18 % removal of imidacloprid in just 20 min and complete destruction of MB dye only in 10 min. The degradation rate constant (k) for SnO2 and Au@PPy-C/SnO2 was found to be 0.0327 and 0.1310 min−1 respectively, revealing 4 times higher proficiency of Au@PPy-C/SnO2 than bare SnO2. The effect of variation of different parameters on imidacloprid photodegradation has also been investigated like irradiation time, reaction pH, substrate concentration and catalyst concentration. Higher photocatalytic activity has been observed at low substrate concentration under acidic condition (pH: 4) with 20 minutes as an optimal time.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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