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Evolutionary Computation Framework for Handling Resource and Optimization of Solar Energy Harvesting System for WSN
Published in R.S. Chauhan, Kavita Taneja, Rajiv Khanduja, Vishal Kamra, Rahul Rattan, Evolutionary Computation with Intelligent Systems, 2022
The P&O method operates on the theory of balancing impedance between charge and solar panel. The impedance matching is important for optimum power transfer. Utilizing a DC-DC converter, this impedance matching is accomplished. Through utilizing a DC-DC converter, impedance is changed by adjusting the MOSFET switch’s service cycle (DD). The relationship between input voltage, output voltage, and the duty cycle is given as follows: Vo=Vin⋅DRin=RL/D2
Capacitors and Inductors
Published in Kevin Robinson, Practical Audio Electronics, 2020
As can be seen from Eq. 13.1 the value of a capacitor’s reactance depends on the capacitance of the device and the frequency of the signal. So for a given device which has a fixed value (measured in farads) the impedance can be plotted against the frequency of the signal applied. This relationship is graphed in Figure 13.5 for three capacitance values: 22nF, 47nF, and 100nF. As the frequency increases the impedance decreases. This illustrates the capacitor’s core behaviour which clearly explains why capacitors block low frequencies and pass high frequencies. At low frequencies the impedance becomes very high and so little signal can get past while at high frequencies the impedance becomes very low and so signals have little difficulty in passing through.
Fundamentals of Audio and Acoustics
Published in Douglas Self, Audio Engineering Explained, 2012
Direct current (DC) flows in one direction only. In AC (alternating current) the direction of current flow is alternating at the frequency of the waveform. Voltage and current are not always in sync so the phase relationship between them must be considered. Power flow is reduced when they are not in relative phase (synchronization). Voltage and current are in phase in resistive circuits. Phase shifts between voltage and current are produced by reactive elements in a circuit. Reactance reduces the power transferred to the load by storing energy and reflecting it back to the source. Loudspeakers and transformers are examples of sound system components that can have significant reactive characteristics. The combined opposition to current flow caused by resistance and reactance is termed the impedance (Z) of the circuit. The unit for impedance is also the ohm (Ω). An impedance can be purely resistive, purely reactive, or most often some combination of the two. This is referred to as a complex impedance. Impedance is a function of frequency, and impedance measurements must state the frequency at which the measurement was made. Sound system technicians should be able to measure impedance to verify proper component loading, such as at the amplifier/loudspeaker interface.
Application of Behavioral Psychology in Clothing Design from The Perspective of Big Data
Published in Applied Artificial Intelligence, 2023
It can be seen that to improve the common mode rejection capability, We can increase differential voltage gain or decrease common mode voltage gain to increase or decrease the CMRR, which is the ratio of differential voltage gain to common mode voltage gain. Emitter resistance RE should be raised to increase CMRR. The CMRR’s value is frequently influenced by signal frequency. Where, the closed-loop gain, resistance matching accuracy, and of the amplifier circuit must be considered, that is, the multi-op-amp differential amplifier circuit of the following parts should be used. Designing source and load impedances for resistance matching reduces signal reflection or increases power transfer. A circuit’s mismatched resistance will cause a reflection of the signal back to its source. The power transmitted downstream to a load is lessened when a signal reflects. Impedance matching serves the twin purpose of minimizing reflections while facilitating power transmission into a load.
Modified Cascaded H-bridge Multilevel Inverter for Hybrid Renewable Energy Applications
Published in IETE Journal of Research, 2022
LC filter is designed for the second-order passive filter, which contains two reactive components that are inductor and capacitor. When a capacitor and an inductor are placed in the same filter, there are two reactive devices responding in opposite ways to the changes of frequency. The inductor blocks high frequencies and passes low frequencies, while the capacitor passes high frequencies and blocks low frequencies. The filtering action of resistor/capacitor filters is also dependent on the impedance that will vary the frequency. The impedance of a capacitor is inversely proportional to frequency, or increasing frequency leads to reducing impedance. For an inductor, its impedance is directly proportional to the frequency. Increasing frequency leads to increasing impedance. The frequency for the LC filter can be calculated as: where fr= frequency resonance,L = inductance and C = capacitance. So, with these WO reactive components, most of the frequencies can be blocked and the number of harmonic frequencies that goes through the system can be reduced. To minimize distortion, for linear or non-linear loads, the inverter output impedance must be minimized. Therefore, the capacitance must be maximized, and the inductance must be minimized when specifying the cut-off frequency. This decreases the overall cost, weight and volume. In contrary, when the capacitance is increased, the inverter power rating will be increased due to the increase of the reactive power due to the presence of filter.
Self-sensing concrete: from resistance-based sensing to capacitance-based sensing
Published in International Journal of Smart and Nano Materials, 2021
The measured resistance can be DC or AC. The DC method is advantageous for its greater degree of current penetration, while the AC method is advantageous for the lower degree of electric polarization. Polarization refers to the movement of charges (e.g., ions) so that an electric dipole is formed. Polarization occurs during resistance measurement, which involves the application of a small current provided by the measurement meter for the duration of the measurement. The longer is the time of the measurement, the more is the polarization. Depolarization occurs upon reversal of the polarity of the current. The dipole impedes conduction, thus causing the measured resistance to be higher than the true resistance. In order to measure the true resistance, the resistance should be measured within the first few seconds of resistance measurement, before polarization becomes appreciable. Alternatively, the current polarity can be reversed and the average of the measured resistance immediately before the reversal and that immediately after the reversal gives the true resistance [64,65] (Figure 3). In both DC and AC methods, the removal of the contact resistance from the measured resistance is important. The AC resistance is to be distinguished from the AC impedance, which is a complex quantity that reflects both the real part (resistance) and imaginary part (reactance).