The development and improvements in wind energy conversion systems (WECSs) are intensively focused these days because of its environment friendly nature. One of the attractive development is the maximum power extraction (MPE) subject to variations in wind speed. This paper has addressed the MPE in the presence of wind speed and parametric variation. This objective is met by designing a generalized global sliding mode control (GGSMC) for the tracking of wind turbine speed. The nonlinear drift terms and input channels, which generally evolves under uncertainties, are estimated using feed forward neural networks (FFNNs). The designed GGSMC algorithm enforced sliding mode from initial time with suppressed chattering. Therefore, the overall maximum power point tracking (MPPT) control is very robust from the start of the process which is always demanded in every practical scenario. The closed loop stability analysis, of the proposed design is rigorously presented and the simulations are carried out to authenticate the robust MPE. INDEX TERMS Feed forward neural networks (FFNNs), generalized global sliding mode controller (GGSMC), maximum power point tracking (MPPT), permanent magnet synchronous generator (PMSG), wind energy conversion systems (WECSs). The associate editor coordinating the review of this manuscript and approving it for publication was Ding Zhai.
Edge detection has beneficial applications in the fields such as machine vision, pattern recognition and biomedical imaging etc. Edge detection highlights high frequency components in the image. Edge detection is a challenging task. It becomes more arduous when it comes to noisy images. This study focuses on fuzzy logic based edge detection in smooth and noisy clinical images. The proposed method (in noisy images) employs a 3×3 mask guided by fuzzy rule set. Moreover, in case of smooth clinical images, an extra mask of contrast adjustment is integrated with edge detection mask to intensify the smooth images. The developed method was tested on noise-free, smooth and noisy images. The results were compared with other established edge detection techniques like Sobel, Prewitt, Laplacian of Gaussian (LOG), Roberts and Canny. When the developed edge detection technique was applied to a smooth clinical image of size 270×290 pixels having 24 dB ‘salt and pepper’ noise, it detected very few (22) false edge pixels, compared to Sobel (1931), Prewitt (2741), LOG (3102), Roberts (1451) and Canny (1045) false edge pixels. Therefore it is evident that the developed method offers improved solution to the edge detection problem in smooth and noisy clinical images.
Laser direct metal deposition (LDMD) has developed from a prototyping to a single metal manufacturing tool. Its potential for creating multimaterial and functionally graded structures is now beginning to be explored. This work is a first part of a study in which a single layer of Inconel 718 is deposited on Ti-6Al-4V substrate. Single layer tracks were built at a range of powder mass flow rates using a coaxial nozzle and 1.5 kW diode laser operating in both continuous and pulsed beam modes. This part of the study focused on the experimental findings during the deposition of Inconel 718 powder on Ti-6Al-4V substrate. Scanning electron microscopy (SEM) and X-ray diffraction analysis were performed for characterization and phase identification. Residual stress measurement had been carried out to ascertain the effects of laser pulse parameters on the crack development during the deposition process.
The effects of soil amendments [i.e., control, gypsum, farmyard manure (FYM), and gypsum þ FYM] and seed priming (i.e., unprimed, seed soaked in water for 10 hr prior to sowing, and seed soaked in 0.4% gypsum solution for 10 hr prior to sowing) were assessed on growth and yield of wheat (Triticum aestivum L.) crop in alkali soil in northwestern Pakistan. A split plot design was used, keeping priming methods in main plots and soil amendments in sub-plots. The results showed that the effects of soil amendments and seed priming on grain yield, straw yield, harvest index and number of spikes were significant but their interactive effect was non-significant. The highest crop yields and yield index were obtained with gypsum þ FYM amendments, and seed priming with gypsum solution. The effect on seed emergence, plant height and number of grains per spike was, however, not significant. Grain yield increased by 104% in gypsum þ FYM treatment over control and by 16.8% with seed primed in water, followed by 8.5% with priming in gypsum solution, as compared to non-priming. The weight of 1000 grains was significantly increased by 35% in gypsum þ FYM treatment and by 15.8% in gypsum priming. The phosphorus (P) and potassium (K) content increased with soil amendments. Soil pH and gypsum requirement reduced significantly with soil amendments. The blend of gypsum and FYM has improved the properties of salt-affected soil and enhanced fertility for optimum production of wheat in addition to the beneficial effect of seed priming in gypsum solution on crop yield. Using these amendments could be ameliorative in removing the adverse effect of the salt-affected soils, rendering the soil a good medium for plant growth.
The increasing energy demand and the target to reduce environmental pollution make it essential to use efficient and environment-friendly renewable energy systems. One of these systems is the Photovoltaic (PV) system which generates energy subject to variation in environmental conditions such as temperature and solar radiations. In the presence of these variations, it is necessary to extract the maximum power via the maximum power point tracking (MPPT) controller. This paper presents a nonlinear generalized global sliding mode controller (GGSMC) to harvest maximum power from a PV array using a DC-DC buck-boost converter. A feed-forward neural network (FFNN) is used to provide a reference voltage. A GGSMC is designed to track the FFNN generated reference subject to varying temperature and sunlight. The proposed control strategy, along with a modified sliding mode control, eliminates the reaching phase so that the sliding mode exists throughout the time. The system response observes no chattering and harmonic distortions. Finally, the simulation results using MATLAB/Simulink environment demonstrate the effectiveness, accuracy, and rapid tracking of the proposed control strategy. The results are compared with standard results of the nonlinear backstepping controller under abrupt changes in environmental conditions for further validation.
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