Current Issue : October - December Volume : 2017 Issue Number : 4 Articles : 5 Articles
The low energy transition efficiency of electromagnetic ultrasonic transducer (EMAT)\nis a common problem in practical application. For the purpose of enhancing the amplitude of the\nreceived signal, an improved double-coil bulk wave EMAT is proposed for the thickness measurement\nof metallic block. This new configuration of magnets consists of a solid cylindrical magnet and\na ring-shaped magnet encircling the outer side of the solid cylindrical one. A double-coil was applied\ninstead of a single spiral-coil. Numerical simulations were performed to analyze and optimize\nthe proposed configuration of the EMAT by the 2-D axisymmetric finite element model (FEM).\nThe experiment effectively verifies the rationality of the new configuration and the feasibility of\nimproving the signal strength....
Metallurgy industries often use steel billets, at a proper temperature, to achieve the desired metallurgical, mechanical, and\ndimensional properties of manufactured products. Optimal operation of steel billet reheating furnaces requires the minimization\nof fuel consumption while maintaining a homogeneous material thermal soak. In this study, the operation of a reheating furnace is\nmodeled as a nonlinear optimization problem with the goal of minimizing fuel costwhile satisfying a desired discharge temperature.\nFor this purpose, a genetic algorithms approach is developed. Computational simulation results show that it is possible to minimize\ncosts for different charge temperatures and production rates using the implemented method. Additionally, practical results are\nvalidated with actual data, in a specific scenario, showing a reduction of 3.36% of fuel consumption....
This paper develops a distribution circuit multi-time-scale simulation tool for applications\nin wind turbine and photovoltaic (PV) integration analysis. The proposed simulation tool developed\nin MATLABTM includes several distribution circuit components, such as voltage sources, distribution\nlines, transformers, loads, capacitor banks, wind turbines and PVs. Each equipment consists of three\nmodels for simulations in three different time scales, i.e., steady-state, electromechanical transient\nand electromagnetic transient models. Therefore, the proposed tool is able to perform a long-term\nsimulation involving power system phenomena spreading across time scales. The test circuits\nemployed to perform multi-time-scale simulation in this paper are modified from the IEEE four-node\ntest feeder. The simulation scenarios include wind speed and solar irradiance ramp up and down;\na capacitor bank is energized and de-energized; and a single-line-to-ground fault occurs and clears\nitself. The simulation results show that the proposed tool is capable of evaluating power system\nphenomena spread across time scales....
This paper addresses the problem of vibrations produced by switched reluctance actuators, focusing on the linear configuration of\nthis type of machines, aiming at its characterization regarding the structural vibrations. The complexity of the mechanical system\nand the number of parts used put serious restrictions on the effectiveness of analytical approaches. We build the 3D model of the\nactuator and use finite element method (FEM) to find its natural frequencies. The focus is on frequencies within the range up to\nnearly 1.2 kHz which is considered relevant, based on preliminary simulations and experiments. Spectral analysis results of audio\nsignals from experimental modal excitation are also shown and discussed. The obtained data support the characterization of the\nlinear actuator regarding the excitedmodes, its vibration frequencies, andmode shapes, with high potential of excitation due to the\nregular operation regimes of the machine. The results reveal abundant modes and harmonics and the symmetry characteristics of\nthe actuator, showing that the vibration modes can be excited for different configurations of the actuator. The identification of the\nmost critical modes is of great significance for the actuator�s control strategies. This analysis also provides significant information\nto adopt solutions to reduce the vibrations at the design....
High efficiency ultrathin CdTe film is an excellent candidate for reliable,\nefficient, stable and low cost solar cells. In this paper, a high efficiency CdS/CdTe\nsolar cell has been studied by using ADEPT 1D simulation tool. The proposed device\nhas been simulated with a reduced CdTe absorber layer thickness and a ZnTe\nlayer as back surface field (BSF) which substantiates sensible energy conversion\nefficiency. The investigation into the simulation results showed that the conversion\nefficiency with BSF layer and 1 �¼m thick CdTe absorber is 8.24% more as compared\nto the conventional CdTe cells (without BSF layer). Reduction of minority carrier\nrecombination loss due to the insertion of BSF layer at the back contact in ultrathin\nCdS/CdTe cells has also been investigated. The results depict that CdTe cell\nwith BSF layer is responsible for increasing the quantum efficiency. However, the\nproposed structure of ZnO/CdS/CdTe/ZnTe demonstrates the highest efficiency of\n24.66% (Voc = 946.51 mV, Jsc = 34.40 mA/cm2 and FF = 75.72%) under global AM1.5G\nillumination spectra....
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