Point Of Maximum Energy Research Articles

Laser-Based Dynamic Optical Wireless Power Transfer for Electrified Vehicles Covered with Solar Cells

This research proposes and theoretically analyzes a dynamic optical wireless power transfer (OWPT) system for wireless charging of aerial and ground electric vehicles (EVs). In the proposed system, an overhead facility is utilized to host laser transmitters, while solar arrays are attached on EVs to be energy receivers. Moreover, laser transmitters are able to rotate, point upward and downward to wirelessly charge aerial and ground EVs. Owing to the movement of EVs, the wirelessly transmitted power and energy to EVs are varying with time and distance, hence are not as simple as in the case of static wireless charging, i.e. when EVs are stopped or hovering. This paper therefore proposes an analytical analysis for the dependence of wirelessly transmitted laser power and energy to moving EVs on the transmitting distance, utilizing the exponential integral function. The derived results reveal that there exist a unique maximum power point and a unique maximum energy point, due to the monotonic increase and decrease of the transmitted power and energy. These give rise to determining the optimal distances at which the wirelessly transmitted laser power and energy are maximum. Numerical simulations are then carried out to validate and illustrate theoretical results.

Modeling & implementation of DRLA based partially shaded solar system integration with 3-ϕ conventional grid using constant current controller

Renewable Energy Resources (RERs) are widely used on the concern of global environment protection. Solar energy systems play an important role in the generation of electrical energy, remarkably minimize the utilization of nonrenewable fuel sources. Solar energy can be extracted and transformed into electrical energy via solar photovoltaic process. Several traditional, soft computing, heuristic, and meta-heuristic maximum power point tracking (MPPT) techniques have been developed to extract Maximum Energy Point (MEP) from the solar photovoltaic modules under different atmospheric conditions. In this manuscript, the combination of reinforcement learning algorithm (RLA) and deep learning algorithm (DLA) called deep Reinforcement Learning Algorithm based MPPT (DRLAMPPT) is proposed under partial shading conditions (PSC) of the solar system. DRLAMPPT can deal with continuous state spaces, in contrast to RL it can be operated only with discrete action state spaces. In this proposed DRLAMPPT, deep deterministic policy gradient (DDPG) solves the problem of continuous state spaces are involved to reach the GMEP in photovoltaic systems especially under PSC. In DRLAMPPT, the representative's strategy is parameterized by an artificial neural network (ANN), which uses sensory information as input and directly sends out control signals. This work develops a 2 kW solar photovoltaic power plant comprises of a photovoltaic array, DC/DC step-up converter, 3-Φ Pulse Width Modulated Voltage Source Inverter (PWM-VSI) integrated with conventional power grid using Constant Current Controller (CCC Effectiveness of the proposed DRLAMPPT with CCC can be validated through an experimental setup and with MATLAB. Simulation and tested at different input conditions of solar irradiance. Experimental results prove that, in comparison to existing MPPTs, suggested DRLAMPPT not only attains the best efficiency and also adopts the change in environmental conditions of the photovoltaic system at a much faster rate and able to reach the GMEP within 0.8 s under PSC. Experimental and simulation results also prove that suggested CCC with LC filter makes the inverter output voltage and the grid voltage are in phase at the lower value of THD i.e. 1.1% and 0.98% respectively.

New method for transient line selection in distribution system based on grounding fault transferred

When single-phase arc grounding fault occurs in the neutral ungrounded distribution system, the fault can be transferred by artificially grounding the faulty phase of the busbar, which can effectively improve the fault handling capability of distribution system. The theoretical analysis shows that the characteristic of transient zero-mode current is obviously different between grounding fault and fault transferred. That is to say, in the two grounding processes, the directions of the transient zero-mode current of the fault line are opposite and the direction of the transient zero-mode current of the non-fault line is identical. So, the fault line can be determined based on this theory. The zero-mode current of each line is analysed by wavelet packet decomposition, and the feature band is selected according to the point of maximum energy. The correlation coefficient polarity between two reconstructed data, each is extracted from the first quarter of power cycle of grounding process in respective feature band, is used to determine the criterion for fault line selection. This method only uses its own line information to choose fault line without any other line information. Simultaneously, number of simulation results shows that the method is accurate and reliable.

Energy harvesting study on single and multilayer ferroelectret foams under compressive force

Cellular polypropylene (PP) ferroelectret is a thin and flexible cellular polymer foam that generates electrical power under mechanical force. This work investigates single and multilayer ferroelectret PP foams and their potential to supply energy for human-body-worn sensors. Human foot-fall is emulated using an electrodynamic instrument, allowing applied compressive force and momentum to be correlated with energy output. Peak power, output pulse duration, and energy per strike is derived experimentally as a function of force and momentum, and shown to be a strong function of external load resistance, thus providing a clear maximum energy point. The possibility of increasing pulse time and reducing voltage to CMOS compatible levels at some expense of peak power is shown. To further increase the output power, multilayer ferroelectret is presented. The synchronized power generation of each layer is studied and illustrated using simulation, and results are supported by experiments. Finally, the energy output of single-layer and multi-layer ferroelectrets are compared by charging a capacitor via a rectifier. A ten-layer ferroelectret is shown to have charging ability 29.1 times better than that of the single-layer ferroelectret. It demonstrates energy output that is capable of powering the start-up and transmission of a typical low-power wireless sensor chipset.

A computational study of nonparabolic conduction band effect on quantum wire transport (e.g. GaN)

We studied the physics insight the GaN (example) quantum wire FET transistors. The model is based on the four \(\mathbf{k}{\cdot } \mathbf{p}\) Kane band model. We have introduced closed compact model for the Einstein relation of the diffusivity to mobility ratio (DMR) in quantum wires. The model can be applied for both wide and narrow band gaps of nonparabolic conduction band dispersion. The model is related to the optical matrix elements between conduction and valence bands. We have used 1D electrostatic to model the electron density over the maximum energy point. We have studied the effects of gate-to-source and drain-to-source voltages on the DMR by calculating the electron density using flux theory. We observed that above the threshold the non-parabolic dispersion increases the DMR. Additionally, we have studied the nonparabolic effects on the Fermi level and found that for low doping concentrations, the nonparabolic effect must be considered and an accurate calculation for the optical matrix elements is needed.

Nature and Properties of a Repulsive Fermi Gas in the Upper Branch of the Energy Spectrum

We generalize the Noziéres-Schmitt-Rink method to study the repulsive Fermi gas in the absence of molecule formation, i.e., in the so-called "upper branch." We find that the system remains stable except close to resonance at sufficiently low temperatures. With increasing scattering length, the energy density of the system attains a maximum at a positive scattering length before resonance. This is shown to arise from Pauli blocking which causes the bound states of fermion pairs of different momenta to disappear at different scattering lengths. At the point of maximum energy, the compressibility of the system is substantially reduced, leading to a sizable uniform density core in a trapped gas. The change in spin susceptibility with increasing scattering length is moderate and does not indicate any magnetic instability. These features should also manifest in Fermi gases with unequal masses and/or spin populations.

Nonlinear Control of Variable-Speed Wind Turbines for Generator Torque Limiting and Power Optimization

To maximize wind power extraction, a variable-speed wind turbine (VSWT) should operate as close as possible to its optimal power coefficient. The generator torque is used as a control input to improve wind energy capture by forcing the wind turbine (WT) to stay close to the maximum energy point. In general, current control techniques do not take into account the dynamical and stochastic aspect of both turbine and wind, leading to significant power losses. In addition, they are not robust with respect to disturbances. In order to address these weaknesses, a nonlinear approach, without wind speed measurement for VSWT control, is proposed. Nonlinear static and dynamic state feedback controllers with wind speed estimator are then derived. The controllers were tested with a WT simple mathematical model and are validated with an aeroelastic wind turbine simulator in the presence of disturbances and measurement noise. The results have shown better performance in comparison with existing controllers.

Motion analysis of a tumbling ball mill based on non-linear optimization

Non-linear optimization, a technique of numerical analysis, is applied to motion analysis of ball media in a tumbling ball mill. The basic principles of optimization are explained. The motion equations of ball media are established. The point of maximum energy is computed, and this maximum energy is 2.34% greater than the energy at the point of maximum falling height. The distribution graph of media collision energy shows that this is a multi-limit problem. We propose to define the total potential energy of charge as the accumulation of energy of all dropping points. Optimization of the parameters related to the total potential energy demonstrates that the point of maximum total potential energy does not depend on the mill size. The operation parameters are optimized with the total collision energy of the ball media per unit time as the objective function. The total collision energy of the ball media per unit time under the optimal operation parameters is increased significantly.

Bifurcation in gravity waves

A new method is proposed for the calculation of gravity waves on deep water. This is based on some recently discovered quadratic identities between the Fourier coefficients an in Stokes's expansion. The identities are shown to be derivable from a cubic potential function, which in turn is related to the Lagrangian of the motion. A criterion for the bifurcation of uniform waves into a series of steady waves of non-uniform amplitude is expressed by the vanishing of a particular determinant with elements which are linear combinations of the coefficients an. The critical value of the wave steepness for the symmetric bifurcations discovered by Chen & Saffman (1980) are verified. It is shown that a truncated scheme consisting of only the coefficients a0, a1 and a2 already exhibits Class 2 bifurcation, and similarly for Class 3. Asymmetric bifurcations are also discussed. A recent suggestion by Tanaka (1983) that gravity waves exhibit a Class 1 bifurcation at the point of maximum energy is shown to be incorrect.

Photochemical processes involving the 1n,π* excited state of aliphatic ketones bearing γ hydrogens

The triplet quantum yield was measured as a function of temperature for several alkyl ketones that photodecompose by intramolecular hydrogen abstraction. From these data Arrhenius parameters for the singlet reactions were derived. These reactions were treated as a transfer of a hydrogen atom across a potential energy barrier involving the formation of a six-membered ring in the transition state with concerted internal conversion and surface crossing located after the point of maximum energy. The A factors obtained per hydrogen atom lay between 1 × 10 10 and 2 × 10 10 s −1 for all the ketones investigated. The activation energies are determined by the substitution at the γ carbon and change from 1.1 (tertiary γ hydrogen) to 4.2 kcal/mol (primary γ hydrogen). The similarity between the kinetic behaviour of the excited singlet and triplet states of aliphatic ketones is discussed.