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The supply of energy with the correct parameters to electrical appliances is possible with the use of energy converters. When a direct current is required, rectifier bridges are needed. These can be made using rectifier diodes. The problem of excessive junction temperatures in power diodes, which are used to build rectifier bridges and power converters, was recognized. For this reason, research work was carried out to create a model of a rectifier diode placed on a heat sink and to analyze the heat dissipation from the junction of this diode under forced convection conditions. The results obtained from the simulation work were compared with the results of thermographic temperature measurements. The boundary conditions chosen for the simulation work are presented. A method is also presented that determined the convection coefficient under forced convection conditions. The difference between the simulation results and the results of the thermographic measurements was found to be 0.1 °C, depending on the power dissipated at the junction and the air velocity around the diode.

Oscillating wave surge converter (OWSC) is widely utilized to exploit energy from waves. Due to the wake effects, the layout of OWSCs will significantly affect the energy output of an OWSC farm. However, up to now the layout of OWSC farm was only determined empirically, and there was no quantitative layout optimization method for OWSC farm. The quantitative layout optimization needs analytical wake model for OWSC to conduct fast optimization iterations. However, there was still no analytical wake model for OWSC. Therefore, in this study, we proposed an analytical wake model regarding regular waves, based on which a quantitative method for optimizing the layout of OWSC farm was also proposed. It was found that the total energy outputs of the optimized layouts using the proposed method are significantly larger than those of the empirical ones, and increasing the spacing between the OWSCs in the bi-direction of wave propagation can greatly increase the total energy output. The proposed OWSC analytical wake model can predict the wave height changes with an accuracy of 94.73%. Innovatively, GPU-acceleration technology was utilized, and the GPU-based codes can run at least 1479 times faster than the CPU-based ones. Those implemented codes are opened for other researchers.

This paper is devoted to the determination of the value of the maximum specific power of capacitive electrostatic micromotors based on nanometer working gaps. The motors under consideration were developed earlier. They have the following structure: a metal—thin crystalline ferroelectric layer with a high dielectric constant—a nanometer working gap—a movable electrode. The mechanism limiting the magnitude of the maximum field in the gap have also been determined in previous works. The mechanism is the stripping of atoms from the surface of the movable electrode under the action of electrostatic forces. It was shown that the maximum energy density in the working gap can be as high as 1.6 × 109 J/m3. In the presented paper, a maximum frequency of electromechanical energy conversion as high as 10 MHz is estimated for these motors, with a maximum specific power of 5 × 108 W/kg. The application of the proposed motors for micromachines is discussed.

The parametric study and optimization of a two‐body wave energy converter (WEC) for the wave and current conditions in the region of Zhaitang Island (China) is presented. Nine parameters are considered, and their influence on the power captured by the two‐body WEC is investigated following both single‐parameter and multi‐parameter approaches. A backpropagation neural network model is developed and applied to predict the captured power for any given values of the nine parameters and the wave frequency. Then the robust design method, also known as the Taguchi method, is implemented to study the comprehensive effects of the parameters on the power output of the device. Moreover, scale model experiments are conducted to verify and confirm the influence of the principal parameters on the power output. Combining numerical simulations, a neural network model and experimental work, this study provides an optimization programme for the main parameters of the device in the target sea region and, at a more general level, references for two‐body WEC designs based on specific sea states.

Bipolar plates are an essential component of electrochemical cells and are used in fuel cells for media supply and electrical contacting, for example. The media supply is realized by flow fields, which are introduced into the plates by shaping processes. Metallic bipolar plates are coated to increase their electrical conductivity and service life. There is a considerable need for research into materials, processes and manufacturing strategies in order to develop cost-effective solutions that are suitable for mass production. Manufacturing strategies based on roll-to-roll processes offer considerable potential and are being further developed for this purpose. The latest developments in this area were addressed within a Fraunhofer project. Both the coating of steel strip with carbon-based coatings and the subsequent forming of the steel strip were investigated. It was shown that PVD coatings from strip processes and batch processes are electrically and electrochemically comparable. Furthermore, it was shown that the coated steel strips are formable and that the production of bipolar half-shells is possible.

A plate‐wave energy converter (pWEC) moored in front of a floating stationary breakwater is considered. The pWEC is composed of a submerged flexible plate with piezoelectric layers bonded to both faces of it. Hence the elastic motion of the plate excited by water waves can be transformed into useful electricity due to the piezoelectric effect. To evaluate the performance of the breakwater‐attached pWEC in terms of wave power absorption and wave attenuation, a hydroelastic model based on linear potential flow theory and the eigenfunction matching method is developed with the electromechanical and the hydrodynamic problems of the pWEC coupled together. The pWEC can be either simply supported or clamped at the edge. A multi‐parameter analysis is carried out with the employment of the present model. Effects of the width, submergence and edge types of the plate, together with the scales of the breakwater, including its width and draft, on wave power absorption and wave attenuation, are examined. As the pWEC moves towards a deeper position, the main peaks of the frequency response of the wave power absorption efficiency become lower and narrower. In contrast, its effect on wave attenuation is limited.

The power performances of a point absorber wave energy converter (WEC) operating in a nonlinear multidirectional random sea are rigorously investigated. The absorbed power of the WEC Power-Take-Off system has been predicted by incorporating a second order random wave model into a nonlinear dynamic filter. This is a new approach, and, as the second order random wave model can be utilized to accurately simulate the nonlinear waves in an irregular sea, avoids the inaccuracies resulting from using a first order linear wave model in the simulation process. The predicted results have been systematically analyzed and compared, and the advantages of using this new approach have been convincingly substantiated.

This article substantiates the relevance of adopting hybrid transport systems. The circuit designs are chosen, and an algorithm of controlling the multifunctional energy converter for a hybrid transport system is developed. The performance of the system is analyzed using a multiconvector hybrid circuit with two energy storage units (a capacitor-design capacitive storage and an electrochemical storage battery). The multifunctional energy converter is modeled in the MATLAB/Simulink suite. The model is appropriate for the rational management of energy in transport systems in their various operational modes, which confirms the expediency of configuring and choosing circuit designs when creating a converter for a hybrid transport system.

In 2019 a Scientific Research & Demonstration Platform was deployed near islands and reefs in South China Sea by a joint research group of 7 institutes and universities in China. It is a simplified small model of a two-module semi-submersible-type VLFS. The test on site has continued for more than one and half years since then for long-term observations to validate the developed key technologies for design and behavior predictions of floating structures deployed near islands and reefs. An integrated information system was set up to continuously collect and inspect the data of the encountered waves, structure responses, connector forces, mooring line forces, anti-corrosion status of the platform, the performance efficiencies of a floating breakwater nearby and a wave energy converter attached on the breakwater. In this paper, the status of the on-site measurements and validations of the key technologies are briefly described.

This paper examines the response of a heaving plate wave energy converter integrated with a chambered breakwater system through experimental and numerical simulations. A porous seaside wall with 20% porosity and an impermeable back wall constitutes a chambered breakwater under investigation. The time-domain response of the wave energy converter before and after integration with the chambered breakwater is evaluated using an open-source code WEC-Sim implemented in MATLAB and Simulink. The performance of WEC subjected to regular wave conditions and the wave elevations measured from the experiments are examined in the present investigation. The reflection characteristics of the chambered breakwater system after integrating with the wave energy converter have been found to decrease. The heave RAO of the wave energy converter installed at a location toward the porous wall is observed to have improved by 22% after integrating with the chambered breakwater than the stand-alone wave energy converter. A similar increase in the power generation performance of the wave energy converter is also observed. The proposed system can improve the economic competitiveness of the wave energy converter by serving dual purposes.

The sorts of converters are characterized into six ages as per the qualities and improvement process. This characterization reviews all DC/DC converters and classifies new models. Since 2001, the DC/DC converter has been fabricated and this order has perceived in everywhere throughout the world. Presently it is anything but difficult to sort and apportion DC/DC converters and evaluate their specialized highlights. DC/DC converters are basic in assortment of uses including power supplies, for example, individual/smart phones, telephones, office equipment's, rocket control frameworks, and media transmission equipment's, and also heavenly bodies where input/yield voltage ranges cover. PWM age is viewed as the more essential in the Converter plan and a few multicarrier strategies have been produced to diminish the mutilation in level converters in light of the established with triangular transporters [1] . A DC/DC converter is an electronic circuit which changes over a wellspring of direct present (DC) starting with one voltage level then onto the next. It is a class of energy converter.

A mixed time‐domain/frequency‐domain method is proposed for modelling dense wave energy converter (WEC) arrays with non‐linear power take‐off (PTO). The model is based on a harmonic balance method which describes the system response in the frequency domain, while evaluating the non‐linear PTO force and solving the system equations of motion in the time domain. The non‐linear PTO force is computed with Lagrange multipliers. In order to apply the proposed method for WEC array responses in real sea states, the time series is split into time windows and the simulation is carried out individually per window. The method is demonstrated by investigating the dynamics of the Ocean Grazer WEC array (OG‐WEC) with an adaptable piston pumping system. The key parameters thought to possibly influence model accuracy, including the number of harmonic components, the length of the time window and overlay, are discussed. It is shown that the proposed model can significantly reduce the computational cost with an acceptable accuracy penalty.

With the continuous development of society and economy, people’s demand for electric energy is increasing. The low-carbon and energy-saving technologies of renewable energy especially wave energy have become the focus of current researches. Considering the increasingly serious energy problems, a wave energy converter (WEC) is proposed based on Halbach permanent magnetic array, which increases the output performance. The equivalent magnetic circuit model of the WEC is established. The static magnetic field modeling and structural parameters optimal permanent of the WEC are performed on this theoretical. Theoretical studies have found that the optimal permanent magnet thickness ratios for Halbach permanent magnet array structures is 0.6, and the ratio of permanent magnet to coil radial ratio is 0.7. The coil winding form and rectifying circuit of the WEC were designed. The WEC equivalent magnetic circuit model was verified by COMSOL Multiphysics finite element software, and the open circuit voltages of WEC was obtained. If the WEC moves at a speed of 0.1 m/s, the coil voltage can reach about 113 V after simulation. According to the testing requirements of the WEC, a test platform was built. The Halbach permanent magnet array structures greatly enhances the wave energy collection of WEC.

The hydraulic power take-off (HPTO) is considered as the most promising method to convert wave power to electrical power. This paper presents an experimental assessment of the power conversion of a wave energy converter using HPTO. Based on the experimental results, a modification of accumulator pre-charged pressure and a control strategy were proposed to improve the system performance. System design, the working principle and mathematical model of all components were described. The proposed method was verified based on both simulation and experimental tests. The results showed that the system always works at an optimal condition under different input wave conditions.

System level optimization is used to design an innovative ocean–wind energy converter to meet the “as good as it can be done” design objective. This general design procedure is then applied to the design of a 20 kW energy system and it is demonstrated that a combined energetic and economical design procedure is required for an optimal solution.

The operation of a solar cell resonant converter at operating modes in the power supply system of a small spacecraft is investigated. The resonant converter with pulse-code regulation simulation model has been developed, and the operation point by stabilizing charge current mode and stabilizing output voltage mode is considered. The converter regulating characteristics in various operating modes are obtained.

Wave Energy Converters (WEC) are devices that harvest the different energies that are associated with moving waves, such as kinetic energy and potential energy, and converting them into useful mechanical and electrical energies. Considering that the ocean and sea are covering around 71 percent of the earth, it is unavoidable to consider it as the main source of renewable energy. This report starts with reviewing a few of the most recent WECs. In the analysis section, it shows a device that functions using pistons to run a hydraulic motor, which then runs a generator in a system. The device is further modified by attaching a rotating mass, which is directly connected to a generator. It is a hybrid device using technologies of both the Pelamis and the Penguin. The power output calculated for the system is 177 kW, which is quiet reasonable considering the wave conditions at Fujairah’s sea shore in United Arab Emirates.

The direct-drive Permanent Magnet Linear Generator (PMLG)-based Ocean Wave Energy Converter (OWEC) generates variable AC voltage, which cannot be directly utilized by the load. This paper presents ...

Since the input power of the real waves varies continuously and periodically, how to stabilise the operation and generation during wave energy utilisation has become an inevitable and significant topic. This study focuses on the wave energy converter of a hydraulic power take-off (HPTO) connected to a pendulum and studies the influences of the key components, i.e. the high-pressure accumulator, oil tank and flow control valve, on the operational stability of HPTO by simulations and experiments. Parameters of the high-pressure accumulator are analysed and optimised. The dynamic performance of the HPTO with or without the oil tank is also investigated. Besides, the functions of the flow control valve in the cases of excessive input power and load shedding are given. Results show that the key components play very important roles in the operational stability of HPTO. Reasonable configurations of the high-pressure accumulator and oil tank are significant to improve the quality of output power and stability. Appropriate actions of the flow control valve are beneficial to protection and stability. Therefore, these key components should be considered preferentially during the design of HPTO.

Numerical models are essential in all the development stages of a Wave Energy Converter. The results accuracy, the capacity to model the (main) WEC non-linearities and the computational burden associated to a numerical simulation make up the focus of many academic researchers. This paper pursues the development of a spectral-domain model of a gyroscopic wave energy converter, called ISWEC, equipped with a hydraulic PTO system. Due to its ability to model the ISWEC non-linearities and the low computational time required for a single wave simulation, the spectral-domain model represents a valid solution to perform the design of the ISWEC system, at least to accomplish its first draft in which million of single wave simulation are required. The major outcomes of this work are the detailed derivation of the spectral-domain model together with a first evaluation of the model accuracy and computational effort required.

In a Wave Energy Converter (WEC), the Power Take-off (PTO) mechanism does the energy conversion through a series of mechanical and electrical systems. The PTO system plays a major role in defining the WEC system's structural dynamics. Since the PTO system directly affects the efficiency of power conversion, it has a significant role to play in the annual energy production of the WEC system. This emphasizes the importance of selecting an appropriate PTO system for any WEC based on the working conditions and other related parameters. In this chapter, different types of PTO systems developed over the past few decades are discussed along with their corresponding advantages and shortcomings. On reading this chapter, the reader will get acquainted with different types of PTO mechanisms in existence and also gain an insight on when to use what type of PTO.

Wave energy is favored by more and more people because of its wide distribution, pollution-free, renewable and many other advantages. Among numerous wave energy converting devices, the converters using floating breakwaters are recognized to be quite promising as the construction and maintenance cost can be shared. In this study, a shoreline wave energy converter (WEC) is proposed which consists of a floating breakwater arranged along the wave direction and restricted to only have vertical degree of motion. Making use of the motion of breakwaters, a dynamo is able to convert the wave power to electricity. At the same time, the incoming waves can be attenuated due to the complex interaction between waves and the floating structure. A scale model was built in the laboratory at Hohai University, and then employed to investigate the performance of developed wave energy device. In the physical model, dynamos and resistance were employed as the power take-off (PTO) system, and the instantaneous output power could be calculated using the measured data. Experimental results show that the resonance state of float plays an important role for the wave energy extraction, and the hydrodynamic efficiency of the device under the resonance state can be up to 41.8% for single breakwater, counting in the internal energy converted by the dissipative force. When subjected to shorter waves, the PTO damping encourages the wave reflection; whereas, more wave energy is dissipated or transformed to power for longer waves. Meanwhile, the PTO damping is also a negative factor for the wave overtopping reduction as the motion of float may be restrained considerably. Last but not the least, the PTO load is proved to be a significant parameter for the optimization the output power, and a strategy must be found to achieve the best power conversion under the dominant wave conditions.

This article presents a methodology to find out a suitable ocean wave energy converter (OWEC) device for Indian coastal region. A comprehensive literature survey of all the existing OWEC devices is...

CECO is a wave energy converter (WEC) of the oscillating body type equipped with an inclined PTO system and being developed at the Faculty of Engineering of the University of Porto. In the last years, several research studies have been performed to assess and to improve the performance of this WEC, using both physical model tests and numerical simulations. The main objective of this paper is reviewing the most significant findings of past research works, so as to provide a detailed overview about the present status of knowledge, but also presenting recent outcomes on the development of CECO and the next research steps. It discusses the influence of the PTO slope angle and damping on the efficiency of CECO harvesting wave energy and describes its energy conversion stages. Furthermore, the intra-annual variability of the wave resource (i.e., on a monthly basis) is considered in the analysis of the influence of the PTO inclination and local water depth at the deployment site on CECO captured energy and captured energy efficiency, along the North Atlantic coast of the Iberian Peninsula. The results have shown significant differences between the summer and winter months and also highlighted the fact that the initial geometry of this WEC is more suitable for the less energetic wave climates, characteristic of the southern locations of the case study area and of shallow waters. The conclusions obtained supported the design of an enhanced version of CECO, prepared for the more energetic stretches of the study area, which presents a hydrodynamic efficiency of more than twice the original one, for the target wave conditions.

Since the hydraulic power take-off (PTO) is a widely-utilized transmission device for oscillating-body wave energy converters, its parameter configurations need to be optimized with an accurate dynamic model. To accurately describe the cylinder friction force, the motor loss and the accumulator working patterns, this paper establishes a novel nonlinear state space model for a hydraulic PTO. The model contains a stiction-involved Stribeck curve for the hydraulic cylinder, an improved Jeong's theory for the hydraulic motor and a pressure-bound-related formula for the high-pressure accumulator. The proposed model is simulated in irregular waves and verified via the comparison with the WEC models based on Yang's theory [1]. Furthermore, the research focuses on obtaining optimal PTO parameter configurations with the suitable piston area and resistance, according to the generating ability, energy conversion efficiency and pressure stability. The results show that the piston area has a more significant impact on the generating ability and pressure stability than the resistance but the same influence on the energy conversion efficiency. In general, a small piston area and a minor resistance are the superior configurations at the fixed capacity.

Energy resource classification systems are useful assessment tools that support energy planning and project development, e.g., siting and feasibility studies. They typically establish standard classes of power, a measure of the opportunity for energy resource capture. In this study, we develop wave energy resource classification systems for the US based on wave power (J, kW/m) and its distribution with peak period ( T p , s ). These metrics are calculated for 70,386 sites from partitioned bulk wave parameters generated from a validated 30-year WaveWatch III model hindcast. As the operating resonant period bandwidth of a wave energy converter (WEC) technology is an important design characteristic, the dominant period band containing the largest energy content is identified among three peak period band classes. These classification systems, comprised of four power classes and three peak period band classes, are based on the total wave power or the partitioned wave power in the dominant peak period band. They discriminate distinct trends in wave energy resource among five regions within the US, and provide useful information for energy planners, project developers, and technology designers. They also establish a framework for investigating the feasibility of a compatible wave climate (design load) conditions and WEC technology classification system to reduce design and manufacturing costs.

We consider the hydrodynamics of wave energy converter (WEC) arrays consisting of periodically repeated single bodies or sub-arrays. Of special interest is the array gain due to wave interactions as a function of the spatial configuration of the array. For simplicity, we assume identical WECs oscillating in heave only, although the results should extend to general motions. We find that array gains can be as high as $O(10)$ compared to the same WECs operating in isolation. We show that prominent decreases in array gain are associated with Laue resonances, involving the incident and scattered wave modes, for which we obtain an explicit condition. We also show theoretically that Bragg resonances can result in large decreases in gain with as few as two rows of strong absorbers. For general WEC geometries, we develop a multiple-scattering method of wave–body interactions applicable to generally spaced periodic arrays. For arrays of truncated vertical cylinders, we perform numerical investigations confirming our theoretical predictions for Laue and Bragg resonances. For a special class of multiple-row rectangular WEC arrays, our numerical results show that motion-trapped Rayleigh–Bloch waves can exist and be excited by an incident wave, resulting in sharp, narrow-banded spikes in the array gain.

espanolLa mayoria de las comunidades en la zona del pacifico no estan conectadas al sistema nacional de energia electrica, ademas estas zonas tienen gran riqueza hidrica y maritima, con un enorme potencial no solo pesquero sino tambien energetico. La generacion de electricidad a partir de energia undimotriz busca aprovechar la periodicidad y la amplitud de la energia cinetica y potencial del oleaje, para generar electricidad a partir de un Convertidor de Energia de las Olas y menos perjudicial para el medio ambiente. Este articulo analiza la posibilidad de generar energia electrica a partir de las olas en la costa norte del Pacifico colombiano, lo que reducira el impacto ambiental de la generacion de energia actual a partir del Diesel o la gasolina, reduciendo los costos de generacion de energia debido al costo y transporte de este combustible, lo que permitira que estas comunidades tengan electricidad durante todo el dia [1]. EnglishMost of the Pacific communities are not connected to the national system of electricity, many of these areas have great hydroelectric and maritime wealth, with an enormous potential not only for fishing but also for energy. The generation of electricity from wave energy seeks to take advantage of the frequency and amplitude of the kinetic and potential energy of the waves, to generate electricity from a wave energy converter and that is less harmful to the environment ambient. This article analyzes the possibility of generating electric power from the waves on thenorth coast of the Colombian Pacific, which will reduce the environmental impact of current energy generation from diesel or gasoline, reducing the costs of power generation due to the cost and transportation of this fuel, which will allow these communities have electricity throughout the day.

Photon enhanced thermionic emission (PETE) is a new concept in solar energy conversion, combining thermal and photovoltaic carrier excitations with thermionic emission. A solar-power-driven thermionic energy converter operates by illuminating the solar light condensed by a large-scale Fresnel lens to convert heat energy into electrical energy. By enhancing the efficiency of converting solar radiation into the emitter internal energy, the output power and efficiency of the thermionic energy converter can be greatly improved. In this study, using numerical simulations, the effects of emitter temperature and output characteristics on a thermionic energy converter were investigated. The results showed that the higher rate of the heating power represented the higher temperature of an emitter, as well as output current density, and efficiency. In addition, by reducing the diameter of a collector and thermal conductivity of insulation materials, or increasing the diameter of emitter, the temperature of emitter, output current density, and efficiency could be notably improved. It is also worth mentioning that the main factor that affected the emitter temperature in the process of heat transfer was heat conduction between solids. In conclusion, adequate illumination, reasonable size of collector and emitter, as well as appropriate insulation measurements could efficiently improve the output characteristics of thermionic energy converter.

Distinct from conventional energy‐harvesting (EH) technologies, such as the use of photovoltaic, piezoelectric, and thermoelectric effects, betavoltaic energy conversion can consistently generate uniform electric power, independent of environmental variations, and provide a constant output of high DC voltage, even under conditions of ultra‐low‐power EH. It can also dramatically reduce the energy loss incurred in the processes of voltage boosting and regulation. This study realized betavoltaic cells comprised of p‐i‐n junctions based on silicon carbide, fabricated through a customized semiconductor recipe, and a Ni foil plated with a Ni‐63 radioisotope. The betavoltaic energy converter (BEC) includes an array of 16 parallel‐connected betavoltaic cells. Experimental results demonstrate that the series and parallel connections of two BECs result in an open‐circuit voltage Voc of 3.06 V with a short‐circuit current Isc of 48.5 nA, and a Voc of 1.50 V with an Isc of 92.6 nA, respectively. The capacitor charging efficiency in terms of the current generated from the two series‐connected BECs was measured to be approximately 90.7%.

The wave energy resource along the Northern Spanish coast is determined, for a period of 33 years (1979–2012) based on hindcast results of WAVEWATCH III for the Atlantic ocean area, coupled with the SWAN model for the coastal areas, and using surface winds from ECMWF's ERA- Interim data base. Results are validated with buoy data, in order to evaluate the model's accuracy. Statistical analysis of the wave parameters and wave power results are presented. The analysis was carried out for a coarse grid, on the North of Spain, and for three local areas with a finer mesh: Northwest Galicia, the area between Cape San Adrian and Cape Ortegal and Santander. The case studies include a more realistic perspective of the amount of energy that can be extracted with a wave energy converter, by adopting examples of a large and a small device. A seasonal variability evaluation is done for the nested areas through the analyzes of the seasonal average wave power resource for the different locations, throughout the 33 year hindcast, and the joint distributions of significant wave height and peak period for the number of occurrences and wave power.

To maximize energy conversion, real-time control of a wave energy converter (WEC) requires knowledge of the present and future excitation force ( $F_{\rm{ex}}$ ) acting on the device, which is a nonmeasurable quantity. The problem of estimation and forecasting of $F_{\rm{ex}}$ becomes more challenging when arrays of WECs are considered, due to the hydrodynamic interactions in the array. In this paper, a global $F_{\rm{ex}}$ estimator for a complete WEC array is developed and compared to a set of independent estimators, which utilize information local only to each device. A significant question is whether the array of measurements is sufficient to compensate for the greater complexity of the wave field, compared to the isolated body case. The paper shows that the global estimator is always more accurate than the independent estimator, improving up to $\text{45}\%$ the estimation accuracy of the independent estimator. Regarding prediction, two different $F_{\rm{ex}}$ forecasters for a WEC array are compared: a global forecaster, utilizing $F_{\rm{ex}}$ estimates from the full set of array devices, and an independent forecaster, utilizing only a local $F_{\rm{ex}}$ estimate. We demonstrate that the global forecaster achieves more accurate results, not only compared to the independent forecaster, but also compared to the isolated body case.

Today, the importance of using vernier machines in wave energy converters has increased because of its simple structure and ability to generate a lot of thrust force at low speeds due to the magnetic gear effect. The linear vernier permanent magnet machine has been designed in various structures. Proper design and selection of the main parameters of the machine will improve performance and increase the efficiency of the linear vernier machine. One of these parameters is the shape of the permanent magnets and how they are magnetically oriented. The novelty of this paper is the reduction of leakage flux, achieved by changing the shape and orientation of the permanent magnet. Three types of linear permanent magnet vernier machines with different permanent magnet structures and orientation, including V-shape, Halbach array and consequent-pole are presented. The considered machines have been compared to each other and to the existing machine in terms of airgap flux density, back EMF, PM flux, Inductance, thrust force, detent force, loss, efficiency, power factor, flux density and flux line, using the finite element method in the same conditions and with the same volume of permanent magnets. The results show that the magnetic orientation and shape of the permanent magnet have a considerable effect on the leakage flux, and all the proposed models have a lower leakage flux and better performance compared to the existing model.

This paper presents identification of parameters for noise pollution based electrical energy converter. Parameters involved in traffic noise model and their effects on the performance of noise pollution based electrical energy converter are also discussed.

In this study, power capture performance of a heaving wave energy converter has been optimized by investigating the effect of variation of power take-off damping. The wave energy converter model used in this study utilizes the sliding discrete Fourier transform technique to estimate the local wave frequency. The power take-off parameters are adjusted according to the estimated wave frequency. As a part of the study, two different cases are evaluated. In the first case, the conventional approach based on using power take-off damping equal to radiation damping which is a function of the estimated wave frequency is considered. In the second part of the study, as a proposed approach, the power take-off damping is calculated with a gain factor. This gain factor varies the hydrodynamic analysis-based frequency-dependent radiation damping by multiplying with it. The results show that the captured power results can be increased from 1.64 to 10.38%, while, in average, the power capture increase covering all datasets is 5.95%.

Wave energy can be used to power oceanographic buoys. A new switching control strategy is developed in this paper for a two-body heaving wave energy converter that is composed of a floating cylinder and two rigidly connected submerged hemispheres. This control strategy is designed to prevent excessive displacement of the floating buoy that may occur due to the actuator force. This control strategy switches the control between a multi-resonant controller and a nonlinear damping controller, depending on the state of the system, to account for displacement constraints. This control strategy is developed using a one-degree-of-freedom dynamic model for the relative motion of the two bodies. Estimation of the relative motion, needed for feedback control, is carried out using a Kalman filter. Numerical simulations are conducted to select the proper mooring stiffness. The controller is tested with stochastic models of irregular waves in this paper. The performance of the controller with different sea states is discussed. Annual power production using this control strategy is presented based on real data in 2015 published by Martha's Vineyard Coastal Observatory.

Flow Induced Oscillations (FIO) of tandem cylinders can be enhanced to harness hydrokinetic energy by varying the system parameters. In general, the Converter consists of two mass–spring–damper oscillators subjected to transverse FIOs and specifically Vortex Induced Vibrations and galloping. These FIOs are strongly influenced by variations of the inflow velocity, damping, stiffness, mass and in-flow center-to-center spacing L between two tandem cylinders. In turn, those influence the harnessed power and efficiency of the Converter. In previous experiments, the interactions between the cylinders were proven to be beneficial for the synergy of the cylinders. In this paper, modeling of tandem-cylinder converters is studied considering the Converter parameters, aiming at enhancing the cylinder synergy resulting in increased harnessed power by using a backpropagation (BP) neural network. The main conclusions are: (1) The surrogate model is constructed by a BP network using the experimental data to reduce excessive experimentation or computational inaccuracy. The harnessed power at different flow velocities is computed by the present model and is found to be consistent with experimental results not included in the modeling. (2) Increasing the damping ratio (0.20–0.30) of two tandem cylinders is conducive to improve the power efficiency, but has little effect on power harvesting. (3) In galloping, the harnessed power and its corresponding efficiency for the case of L/D = 1.57 perform at a higher level than that of bigger spacing ratios.

Unique umbilical designs for wave energy converters (WECs), including the ability to handle significantly larger motions and loads over long deployments, are often required when conventional marine umbilical designs for offshore oil and gas and offshore wind may not meet the design and cost needs of wave energy technologies. This study details a fatigue analysis of a dynamic power umbilical attached to a two-body floating point absorber WEC system, using the sea states provided for the PacWave testing facilities. The 6 degrees of freedom motion time history for the WEC was simulated, and the motions of the attachment point for the umbilical on the WEC and respective sea states were used to analyze the dynamic motions and fatigue of the connected power umbilical to predict the fatigue life. The results show that the fatigue damage observed is more significant in shallow water, and extensive fatigue damage may occur because of the larger curvature response of the umbilical. The umbilical configurations departing at 90 deg off incoming waves were found to have the highest fatigue life attributed to less extension or compression of the umbilical. However, additional bend stiffener/limiter features may need to be incorporated into the buoyancy section and touchdown regions to minimize curvature-induced fatigue.