This paper proposes a generalized fractional controller for integer order systems with time delay. The fractional controller structure is so adopted to have a combined effect of fractional filter and Smith predictor. Interestingly, the resulting novel controller can be decomposed into fractional filter cascaded with an integer order PID controller. The method is applied to two practical examples i.e. liquid level system and Shell control fractionator system. The closed- loop responses resulting from the proposed method are compared with that of the available methods in the literature. For quantitative evaluations of the proposed method, Integral Absolute Error (IAE) and Integral Square Control Input (ISCI) performance criteria are employed. The proposed method effectively enhances the closed-loop response by improving the IAE values, reducing the control effort inputs to achieve the desired output. The disturbance rejection and robustness tests are also carried out. The robustness test reveals a significant improvement in the maximum absolute sensitivity measure. That is displayed in numerical simulations of the paper.
The evolution of microstructured optical fibers with hexagonal array (H-MOFs) of air-holes rooted in the background of undoped silica has led to the realization of an ideal host for encouraging and technologically entitled optical properties. We focus to explore the divergence of radiation into free space from the end-facet of solid-core H-MOFs by using the improved theoretical model. Also, we investigated the wavelength dependence of beam divergence angle for principal core mode of H-MOFs under step-index fiber approximation (SIFA). Experimental results have been included for comparison.
In this paper, a low power highly sensitive Triple Metal Surrounding Gate (TM-SG) Nanowire MOSFET photosensor is proposed which uses triple metal gates for controlling short channel effects and III–V compound as the channel material for effective photonic absorption. Most of the conventional FET based photosensors that are available use threshold voltage as the parameter for sensitivity comparison but in this proposed sensor on being exposed to light there is a substantial increase in conductance of the GaAs channel underneath and, thereby change in the subthreshold current under exposure is used as a sensitivity parameter (i.e., Iillumination/IDark). In order to further enhance the device performance it is coated with a shell of AlxGa1-xAs which effectively passivates the GaAs surface and provides a better carrier confinement at the interface results in an increased photoabsorption. At last performance parameters of TM-SG Bare GaAs Nanowire MOSFET are compared with TM-SG core-shell GaAs/AlGaAs Nanowire MOSFET and the results show that Core-Shell structures can be a better choice for photodetection in visible region.
Background: a humidity sensor is used to sense and measure the relative humidity of air. A new composite system has been fabricated using environmental pollutants such as carbon black and low-cost zinc oxide, and it acts as a humidity sensor. Residual life of the sensor is calculated and an expert system is modelled. For properties and nature confirmation, characterization is performed, and a sensing material is fabricated. Methodology: characterization is performed on the fabricated material. Complex impedance spectroscopy (CIS), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscopy (SEM) are all used to confirm the surface roughness, its composite nature as well as the morphology of the composite. The residual lifetime of the fabricated humidity sensor is calculated by means of accelerated life testing. An intelligent model is designed using artificial intelligence techniques, including the artificial neural network (ANN), fuzzy inference system (FIS) and adaptive neuro-fuzzy inference system (ANFIS). Results: maximum conductivity obtained is 6.4×10⁻³ S/cm when zinc oxide is doped with 80% of carbon black. Conclusion: the solid composite obtained possesses good humidity-sensing capability in the range of 30–95%. ANFIS exhibits the maximum prediction accuracy, with an error rate of just 1.1%.
The present work aims at studying the effects of orientation, size, position, and the combination of multiple internal diathermal obstructions in a fluid-saturated square porous enclosure, generally encountered in thermal insulations. The overall objective is to suppress the natural convection fluid flow and heat transfer across a differentially heated porous enclosure. To serve this purpose, multiple diathermal obstructions are employed to mechanically protrude into a porous medium. It is sought to estimate the effect of various types of orientation, clustering and alternate positioning of obstructions by considering number of obstructions (Np), length of obstructions (λ), modified Rayleigh number (Ra*) on local and average Nusselt number (Nu). The Darcy model for porous media is solved using Finite difference method along with Successive Accelerated Replacement scheme. One of the findings is that the value of the Nusselt number decreases by increasing both, the number of obstructions as well as the length of obstructions irrespective of its orientation and positioning. The reduction in Nusselt number is significant with obstructions attached on lower half of the hot wall and/or on upper half of cold wall. In addition, the overall reduction in Nusselt number is slightly greater with obstructions attached explicitly to the cold wall.
In this paper, a novel double-layer multiband circularly polarized microstrip patch antenna is proposed. The design employs the concept of slotted patch fed with proximity coupled feed having defected ground plane (DGS). The proposed antenna achieves multiple operating frequency bands including FB1 (11.15 GHz), FB2 (4.17 GHz), FB3 (4.87 GHz) and FB4 (1.98 GHz). The proposed antenna has obtained bandwidth of 12.98%, 4.7%, 4.69% and 5.39% at FB1, FB2, FB3 and FB4 bands, respectively. The proposed antenna also exhibits circular polarization in the frequency band FB4. The 3dB ARBW of the antenna is 9.23% at 11.2 GHz. Finally, a metallic cavity is used with the antenna to achieve a unidirectional radiation pattern. The designed antenna radiation characteristics are verified with the experimental results.
Heat exchangers are widely employed in numerous industrial applications to serve the heat recovery and cooling purpose. This work reports a performance analysis of a tube in tube heat exchanger for different flow configuration under variable operating conditions. The experimental investigation was performed on a U-shaped double pipe heat exchanger set up whereas Commercial Computational Fluid Dynamics code FLUENT along with k-ε turbulence modeling scheme was implemented for the simulation study. The flow solution was achieved by implementing k-ε turbulence modeling scheme and the simulation findings were compared with the experimental results. The experimental findings were in good agreement with the simulation results. The counter-flow configuration was found to be 29.4% more effective than the co-current one at low fluid flow rate. Direct relationship between heat transfer rate and flow rate is observed while effectiveness and LMTD showed inverse relationship with it. The significance of inlet temperature of hot and cold stream has been evaluated, they play crucial role in heat exchange process.