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The floating platform motion of an offshore wind turbine system can exacerbate output power fluctuations and increase fatigue loads. This paper proposes a new scheme based on a fast second-order sliding mode (SOSM) control and an adaptive super-twisting extended state observer to suppress the platform motion and power fluctuation. Firstly, an affine nonlinear model of the floating wind turbine pitch system is constructed. Then, a fast SOSM pitch control law is adopted to adjust the blade pitch angle, and a new adaptive super-twisting extended state observer is constructed to achieve total disturbance observation. Finally, simulations are conducted under two cases of wind and wave conditions based on FAST (fatigue, aerodynamics, structures, and turbulence) and MATLAB/Simulink. Compared with the traditional proportional integral (PI) control scheme and standard super-twisting control scheme, the platform roll under the proposed scheme is reduced by 13% and 4%, and pitch is reduced by 16% and 3% in Case 1. Correspondingly, the roll is reduced by 9% and 15%, and pitch is reduced by 7% and 1% in Case 2. For the tower top pitch and yaw moment, load reductions of 7% and 3% or more are achievable compared with those under the PI control scheme. It is indicated that the proposed scheme is more effective in suppressing floating platform motion, stabilizing output power of the wind turbine system, and reducing tower loads.

One of the performance enhancement strategies in thermoelectric technology is application of two-stage leg instead of normal single stage leg structure. However, for a thin-film solar thermoelectric generator applying this strategy requires many in-depth considerations including economic -cost and reliability aspects. In this research, attempts are made to identify the economic and performance characteristics of a two-stage thin-film solar thermoelectric generator under various geometrical conditions and then compare with normal single stage configuration. Generally, in addition to being cost-effective compared to the single-stage design, the double-stage design can produce more power if the appropriate material is selected. The results of numerical simulations show that the use of bismuth tellurides in single stage thermoelectric generator (SATEG) legs improves the performance of the system in terms of power generation. But the use of skutterudites in the lower layer and bismuth tellurides in the upper layer of the two-stage case, in addition to increasing the output power, significantly reduces the dollar/watt value. Furthermore, the highest output power and exergy efficiency are obtained in the lower layer angle ratio of 0.8–1 and in the upper layer angle ratio of 2. Among the geometrical parameters, the radius of heated area (Rh) has the greatest effect on the performance of double-stage solar annular thermoelectric generator (DSATEG). The highest power output is obtained at Rh = 1.5, which is equal to 1.323W.

Abstract Hydrovoltaic energy technology that generates electricity directly from the interaction of materials with water has been regarded as a promising renewable energy harvesting method. With the advantages of high specific surface area, good conductivity, and easily tunable porous nanochannels, two‐dimensional (2D) nanomaterials have promising potential in high‐performance hydrovoltaic electricity generation applications. Herein, this review summarizes the most recent advances of 2D materials for hydrovoltaic electricity generation, including carbon nanosheets, layered double hydroxide (LDH), and layered transition metal oxides and sulfides. Some strategies were introduced to improve the energy conversion efficiency and the output power of hydrovoltaic electricity generation devices based on 2D materials. The applications of these devices in self‐powered electronics, sensors, and low‐consumption devices are also discussed. Finally, the challenges and perspectives on this emerging technology are outlined.

In this paper, an effective strategy for harmonic‐suppressing power amplifier (HS‐PA) design is proposed. To ease the design of HS‐PAs with harmonic‐suppressing output matching networks (HS‐OMN), the capacitance‐splitting method is proposed to tactically incorporate harmonic‐reflecting λ/4 stubs into the HS‐OMN. Benefits from the proposed method, normally complex iterative tunings on HS‐OMN parameters are avoided in implementing HS‐PAs. Two prototype designs are presented to verify the effectiveness and generality of the proposed methodology. One prototype operates in Class AB, which achieves saturated output powers of 47.8 ± 0.2 dBm, peak efficiencies of 70 ± 3%, and harmonic suppressing ratios of better than 70 dB on both the second and third harmonics over 2.3–2.7 GHz. Another prototype is a Doherty HS‐PA, which achieves a saturated output power of 43.2 dBm, saturated/6 dB back‐off efficiencies of 77%/63%, and suppression ratio of better than 60 dB on both the 2nd and 3rd harmonics at 1.95 GHz. [ABSTRACT FROM AUTHOR]

Through the self-researched and manufactured dynamic rotating platform and model wind turbine, experiments were carried out at the open end of the wind tunnel, and the wind direction angle change and the yaw versus wind process were simulated. The influence of two variables (yaw speed and yaw delay time) on wind turbine power and blade stress is studied. The results are: During the dynamic yaw process, blade stress decreases from the root to the tip. Among the 4 yaw speeds (0.5°/s, 1.0°/s, 1.5°/s, 2.0°/s), the stress and power increase the fastest at 0.5°/s yaw speed, and the slowest increase at 2.0°/s. The rate of increase is inversely proportional to the yaw speed. It is found that in the dynamic yaw process, the yaw angle range of 20° to 0° is the main area of stress increase and power increase. In addition, the yaw delay time is investigated. It is found that if there is a delay time of 30S, when the yaw angle is 30°, the stress value decreases by 0.73711MPa, when the yaw angle is 60°, it decreases by 0.02965MPa, and when the yaw angle is 90°, it decreases by 0.0065MPa. It can be known that as the yaw angle increases, the effect of the delay time gradually decreases, so the delay time can be controlled in stages, that is, when the yaw angle is larger, a smaller delay time is used. We also introduce a dimensionless coefficient, which represents the ratio of power to blade stress. It is pointed out that a yaw speed of 0.5°/s is used at a yaw angle of 30°, a yaw speed of 1.0°/s at 60°, and a yaw speed of 2.0°/s at 90°. The results show that the staged control of the yaw speed can avoid power loss and improve the reliability of the wind turbine during operation. [ABSTRACT FROM AUTHOR]

It can be considered that electric generating power from solar energy is an essential topic in the energy field. Several environmental factors affect the energy production of solar cells. Dust accumulation is one of the main factors which significantly negatively influences output energy. However, this topic is not investigated extensively, despite its significant impact, especially in arid areas such as Iraq. In this research paper, both theoretical and experimental techniques were applied to investigate the effect of accumulated dust particles on the efficiency of photovoltaic PV systems. An on-grid photovoltaic system was selected to achieve the experimental work. The results proved the negative effect of dust particles on the performance of the solar cell. Based on the obtained results, a new relationship was introduced between efficiency degradation and the amount of dust that accumulated on the surfaces of cells. This correlation is considered a necessity to find the characteristics of PV solar systems to improve their performance and efficiency. The new correlation introduced in this paper can be considered a promising prediction tool to estimate the characteristics of photovoltaic solar cells under different actual environment working conditions. The output power of the cleaned array system increased by 5-26% compared with the untreated system over the test period. Furthermore, the performance ratio (PR) was enhanced within the cleaned array system by 3 to 6 compared with the uncleaned array. A significant formula introduced the connection between the actual output power of the PV systems and the environmental condition (dust accumulation), where it can be considered as feedback to keep the performance in a steady status, which means obtaining the highest output power. [ABSTRACT FROM AUTHOR]

Methods for harnessing clean energy have received considerable attention recently. In this study, a thermoelectric power generation device is developed for use in road engineering. The thermoelectric generator unit (TEGU) is systematically studied under the influence of various factors including varied temperature differences, load resistance, burial depth, and pavement defects. The experimental results indicate that the output voltage of the TEGU is consistent with the Seebeck effect. When the temperature difference is 60°C, the output power is 24.85 times the power generated when the temperature difference is 10°C. In addition, the deeper the burial depth of the TEGU, the lower the output voltage, and the higher the temperature difference at the same burial depth, the higher the output voltage. In the field test, the TEGU was buried 2 cm below the ground surface. When the maximum temperature difference reached 25.5°C, the open-circuit voltage was 21.41 V and the short-circuit current was 97.2 mA. When the optimal impedance matching resistance was 50 Ω, the output power reached a peak of 0.623 W, and the output voltage was 5.582 V. Furthermore, no significant changes in the power generation ability of the TEGU were observed with different degrees of asphalt pavement defects. The output voltage under typical road conditions when the temperature difference in the laboratory was 30°C only reached 55.49% of that when the temperature difference in the field test was 25.5°C. The developed system enables the conversion of the road surface heat energy and reduction of the internal temperature of the road surface, which can facilitate the development and application of thermoelectric technology. [ABSTRACT FROM AUTHOR]

Park et al. showed that the Shannon entropy of the probability distribution of a single random variable for far-field profiles (FFPs) in deformed microcavity lasers can efficiently measure the directionality of deformed microcavity lasers. In this study, we instead consider two random variables of FFPs with joint probability distributions and introduce the decomposed (Shannon) entropy for the peak intensities of directional emissions. This provides a new foundation such that the decomposed entropy can estimate the degree of the output power at given FFPs without any further information. [ABSTRACT FROM AUTHOR]

High output power, good efficiency, sufficient power gain, compact size, and low cost are essential parameters of high-frequency integrated microwave power amplifiers. Due to its unique characteristics, gallium nitride is considered a good choice for realizing high-frequency power amplifiers. This article presents an integrated microwave power amplifier with high efficiency and wide bandwidth in 0.25 μm GaN technology. Input and output matching networks are realized using spiral inductors, on-chip resistors, on-chip capacitors, and appropriate transmission line structures. The optimal values of the elements have been determined using the random and hybrid optimizer in the ADS simulator. Large on-chip inductors in the drain and gate bias circuits were used for biasing. They were designed in such a way that no ac signal leaks into the bias circuit. The proposed circuit works at 6.8 GHz to 11 GHz frequency, while its maximum PAE is 60%. The small signal gain at the frequency of 9.8 GHz is 12.45 dB, whereas the saturated output power is 32.68 dBm. [ABSTRACT FROM AUTHOR]

Thermoelectric generator can directly convert thermal energy into electrical energy, and applying it to recover waste heat from automobile exhaust is conducive to energy saving. In this paper, a thermoelectric generation experimental system is built, the power output performance and channel power consumption of the flat-plate thermoelectric power generation system under different exhaust gas flow rates are experimentally studied. The results show that when the exhaust flow rate is 40 Nm3/h and the exhaust inlet temperature is 400 °C, the maximum output power of the system is 26.8 W, and the maximum net output power is about 23.3 W. In addition, the exhaust flow rate is changed from 10 Nm3/h to 40 Nm3/h, and the proportion of power consumption in the hot air channel is changed from 1.91% to 12.85%, which has increased by more than six times.

Structural optimization is one of the effective means to improve thermoelectric generator (TEG) performance. Considering the inconsistent material parameters between P-type and N-type thermoelectrics, this paper proposes an L-type TEG configuration, where P-type and N-type semiconductors are designed with different heights and connected by L-shaped conductive strips. In addition, a thermal-electric-mechanical numerical model is established to evaluate and optimize the thermoelectric and mechanical performance of the L-type TEG. Results show that when the temperature difference is 400 K and the height ratio of the P-type to N-type semiconductor is 0.385, the L-type TEG achieves a maximum output power of 1.96 W and a maximum efficiency of 7.8 %. This is 2.39 % and 1.44 % higher, respectively, than the traditional π-type TEG. Although the temperature difference is not related to the optimal configuration of the L-type TEG, it will affect the extent of performance improvement, and the smaller the temperature difference, the greater the percentage gains of the L-type TEG compared to traditional design. In addition, the greater the difference in parameters (including Seebeck coefficient, thermal and electrical conductivity) between P-type and N-type is, the more significant the improvement of the L-type design will be. Specifically, the difference in electrical conductivity contributes to the increase of the output power, while the increase in the efficiency is affected by both the electrical conductivity and the thermal conductivity. This study provides a new perspective on the structural optimization of TEGs. • An innovative L-type configuration for thermoelectric generators is proposed. • A thermal-electric-mechanical numerical model is established to predict the TEG performance. • Power and efficiency are increased by 2.39 % and 1.44 % compared with traditional π-type design. • Greater disparities between P- and N-type lead to more gains when changing the π-to L-type design. [ABSTRACT FROM AUTHOR]

In this paper, the impact of dust deposition on solar photovoltaic (PV) panels was examined, using experimental and machine learning (ML) approaches for different sizes of dust pollutants. The experimental investigation was performed using five different sizes of dust pollutants with a deposition density of 33.48 g/m2 on the panel surface. It has been noted that the zero-resistance current of the PV panel is reduced by up to 49.01% due to the presence of small-size particles and 15.68% for large-size (ranging from 600 µ to 850 µ). In addition, a significant reduction of nearly 40% in sunlight penetration into the PV panel surface was observed due to the deposition of a smaller size of dust pollutants compared to the larger size. Subsequently, different ML regression models, namely support vector machine (SVMR), multiple linear (MLR) and Gaussian (GR), were considered and compared to predict the output power of solar PV panels under the varied size of dust deposition. The outcomes of the ML approach showed that the SVMR algorithms provide optimal performance with MAE, MSE and R2 values of 0.1589, 0.0328 and 0.9919, respectively; while GR had the worst performance. The predicted output power values are in good agreement with the experimental values, showing that the proposed ML approaches are suitable for predicting the output power in any harsh and dusty environment. [ABSTRACT FROM AUTHOR]

In recent years, piezoelectric shoes have been shown in numerous studies to have the potential to power built-in LED lights and foot sensors. In previous studies, the output power of piezoelectric shoes often remained around 1 mW due to the limitation of displacement. For this, this paper proposes piezoelectric shoes based on the structure of shrapnel transducer (length × width × height: 90 × 50 × 15 mm3), which consists of two piezoelectric bimorph. The energy harvesting efficiency of the shrapnel piezoelectric transducer under different excitation frequencies and displacements was tested in the laboratory. When the excitation frequency was 4 Hz and the displacement was 5 mm, the maximum output voltage was 11.03 V, the maximum output current was 0.18 mA, and the maximum output power was 2.03 mW under the matching resistance of 60 kΩ. Then, three people of different weights tested the output characteristics of piezoelectric shoes under different exercise modes. The experimental results showed that the output power increases with the wearer's weight and exercise intensity. When the body weight was 80 kg, the output powers of walking, running, and jumping were 8.24, 12.71, and 23.16 mW, respectively, and the corresponding matching resistances were 40, 14, and 12 kΩ, respectively. The shoe successfully lit up a 0.6-meter-long LED flexible light strip (35 LED lights), which could be used in future research to provide power for rechargeable luminous shoes for night workers or positioning shoes for people who are prone to getting lost. [ABSTRACT FROM AUTHOR]

Copyright of Piezoelectrics & Acoustooptics is the property of Piezoelectric & Acoustooptic and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A new n-channel recessed Metal semiconductor field effect transistor (MESFET) with different materials is designed for high power applications in Multi Input Multi Output (MIMO) systems in this paper. Based on material properties and electrical characteristics of MESFET, a SPICE model of the proposed device is developed. For high performance power switches, the power MESFETs are used in most of the applications. The employability of the technology is validated by the electrical measurements of the device. The operational mechanism has been shown by the characterizations done on the proposed device. To optimize the electrical performance, the contact resistance technique has to be enhanced. In this work, the output power and Gain compression of proposed n-channel MESFET at 100 MHz and 1 GHz for high input power is obtained. The output power at fundamental frequency of operation for high input power is also obtained. [ABSTRACT FROM AUTHOR]

To fully use high-pressure air, the two-stage piston expander (TSPE) has been widely studied. The following factors obstruct the use of the TSPE: A high expansion ratio will inevitably result in a lower air temperature in the cylinder, causing adverse effects such as ice blockage and lubricating oil freezing; the residual air from the I-stage cylinder will all flow into the II-stage cylinder, causing a large reverse force to the I-stage piston during the working process. To address the above problems, a modified two-stage piston expander (M-TSPE) based on spray heat transfer is proposed. Firstly, the working principle of the M-TSPE is introduced, followed by the construction of a mathematical model of the M-TSPE. Secondly, the valve-timing of the M-TSPE is determined and compared with the output power and efficiency of the TSPE. The output power and efficiency of the M-TSPE are increased by 57.58% and 13.28%, respectively. Then, the performance parameters of the M-TSPE with and without spray are compared and analyzed. Finally, parameter analysis is carried out on the air/water mass ratio and water mist particle size. Results show that when the intake pressure and load torque are set to 3 MPa and 150 N·m, respectively, the output power of the M-TSPE without spray is 14.22 kW and the output power of the M-TSPE with spray is 16.08 kW, which is a 13.08% increase in output power. The average air temperatures in the I-stage cylinder of the M-TSPE with and without spray are 321 K and 263 K, respectively, and the average air temperature in the I-stage cylinder is enhanced by 58 K. The output performance of the M-TSPE can be improved by increasing the mass ratio of the water mist in the cylinder and decreasing the particle size of the water mist. [ABSTRACT FROM AUTHOR]

In order to investigate the effect of different influencing factors on the application of temperature differential power generation in the ship exhaust gas and to explore the potential of waste heat recovery and the utilization of exhaust gas during ship travel, an experimental system based on the temperature differential power generation of ship exhaust gas in the marine environment was established. The maximum output power and the maximum efficiency of each temperature-difference power generation module were theoretically calculated. The results showed that the insulation material and the salt water (seawater) had little effect on the efficiency of the temperature differential power generation modules. Conversely, the installation pressure, the heat transfer oil, the cooling water temperature (seawater temperature), and the heat source temperature (exhaust gas pipe temperature) had a great influence on the open-circuit voltage and the maximum output power. The thermally conductive silicone grease and the cooling water temperature of 10 °C increased the open-circuit voltage by 31.54% and 18.95%, respectively, and increased the maximum output power by 82.05% and 51.79%, respectively. The maximum output of a single temperature differential power generator reached 63.5% when using an installation pressure of 3 bar, a cooling water temperature of 20 °C, double-layer aluminum insulation, and thermally conductive silicone grease. Finally, this study provides relevant data support for using temperature differential power generation devices for ship exhaust gas. [ABSTRACT FROM AUTHOR]

The use of photovoltaic cells has increased dramatically in recent years. However, the photovoltaic cells convert most of the solar radiation into heat, and this heat negatively affects the PV productivity. Therefore, a cooling system can get rid most of this heat. An experimental and theoretical examination is conducted for the augmentation of PV power and efficiency by using two different water cooling systems. The PV cooling has been equipped with two types of watercooling systems, i.e. immersion, and spraying. For the immersion cooling, the temperature decrease is achieved but the power output has been low. On the other hand, the water spraying cooling has been studied at three different chilled water flow rates. The solar simulator having an average radiation of 1300 W/m2 is generated through 50 W halogen lights for testing. It has been found out that a 60% temperature reduction has been achieved, with a remarkable increase in power output by 59% and efficiency by 8%. However, no remarkable difference has been achieved by varying water flow rates. Therefore, cooling by spraying system has given better results than immersion. Finally, the experimental results have been found to be consistent with the numerical results. [ABSTRACT FROM AUTHOR]

In order to ensure the continuous output of electric energy, it is necessary to study the fault-tolerant operation of permanent magnet wind generator with double three-phase winding under partial winding fault. For a permanent magnet wind generator with double three-phase winding, after one of the windings is isolated due to fault, the winding distribution will have a certain effect on the generator’s output power and electromagnetic torque during derating operation. In order to find the maximum power output and electromagnetic torque output under this condition, the permanent magnet wind generator with double three-phase winding is studied in this research. A 60 kW double three-phase winding generator with 12 parallel branches is designed. By combining the parallel branches of the generator in different parallel ways, four different double three-phase winding schemes are obtained and the corresponding physical models under single winding conditions are established, simulated and analyzed, and the optimal simulation results of the four schemes are obtained. Finally, through the construction and testing of the prototype platform, the accuracy of the theoretical analysis and simulation results is verified. The results show that the permanent magnet wind generator with double three-phase winding can obtain the maximum power output and electromagnetic torque through the optimal winding combination under single winding operation, which will increase the economic benefit of the generator and sustainable utilization of wind energy.

The Waste Power Plant is one of the power plants with a new renewable energy concept that utilizes waste as fuel. The processing of waste into electrical energy is carried out in two ways: the thermal conversion process and the biological conversion process to find the potential for waste that can be used as fuel to generate electricity. The analysis is needed, especially for Pangkalpinang, which currently has a lot of unprocessed waste. This research was conducted through calculations using several formulas that have been used in previous studies. From these results, the potential waste in 2015 is 97.25 tons/day and produces energy of 18548.10 MWh/year, and in 2020, it was about 186.57 tons/day and produced energy of 35547.18 MWh/year. The projection calculations are carried out to determine the potential for 2021 to 2030. Waste as much as 182523 tons/day in2021 can produce energy of as much as 34776.11 MWh/year. And in 2030, the amount of waste as much as 218132 tons/day can generate an energy potential of 41560.69 MWh/year.

In order to solve the problem of power transmission efficiency reduction resulting from misalignment in the Wireless Power Transfer (WPT) system for Autonomous Underwater Vehicle (AUVs), a novel coupling structure with strong tolerance to misalignment is proposed. A solenoid coil is selected as the transmitting coil, and the receiving coil is composed of dual combined planar coils. The WPT system can still maintain stable output under uncertain axial misalignments for AUVs. The magnetic field distribution of the proposed magnetic coupling structure is analyzed theoretically, and the distance between the coils in the dual combined planar receiving coil is optimized. The theoretical analysis shows that the proposed solenoid-dual combined planar coils coupling structure can effectively maintain a stable mutual inductance between the transmitting coil and receiving coil under different axial misalignments compared with solenoid-unipolar planar coil coupling structure. An S-S resonant compensated WPT experimental prototype is built to verify the output characteristics of the proposed magnetic coupling structure. Compared to the magnetic coupler with the unipolar planar coil, it is validated by experiment that the proposed magnetic coupler substantially enhances the stability of power transmission efficiency and output power when axial misalignment occurs. The power transmission efficiency decreases by 6.74% when axial misalignment increases from 0 to 40 mm in saltwater. Meanwhile, the variation of output power is less than 4.15%.

The energy of rotating machinery exists widely in the environment. It is of great significance to collect and utilize the energy of rotating machinery for sustainable development. In this paper, a novel piezoelectric and electromagnetic energy harvester, which is capable of generating electrical energy under rotary excitation, is proposed based on array magnetic coupling. The working principle of this kind of energy harvester is analyzed. And the energy output modeling of the harvester is developed and output results are simulated. Based on the experimental test platform built in the laboratory, the output characteristics of the piezoelectric and electromagnetic energy harvester are tested. Results show that the maximum output power of the proposed energy harvester reaches 182 mW when the excitation speed is 120 rpm. Furthermore, both the piezoelectric module and the electromagnetic module can reach the maximum output power at the excitation speed of 120 rpm.

This article presents the possibility of increasing the efficiency of a vertical-axis wind generator through the introduction of an automatic control system for the angle of attack of the blades. The calculation of the optimal position of the wind turbine blades for the maximum generation of electrical energy is given, and a developed scheme for controlling the blades using the sensors of the angular speed of rotation of the wind wheel by the anemometer and the current position of the blades is presented. The automatic control system implies the use of a PD controller. A comparison is made of two laboratory experimental models of vertical-axis wind turbines with and without the developed control system. This article focuses on optimizing the angle of attack and developing an automatic control system for vertical-axis wind turbines to increase their efficiency in generating electrical energy.

The caper bush has developed different mechanisms to survive in Mediterranean conditions, such as drought tolerance and seed dormancy. Many studies have been carried out to improve the germination of caper seeds, but ultrasound is one of the least studied methodologies in this species. This study aimed to analyze the effects of treatments with an ultrasonic probe processor on the imbibition and germination of caper seeds. After applying the ultrasound treatment using three output powers and three holding times, the seed coat’s disruption level was determined, and the imbibition, viability and germination tests were carried out. Ultrasonication fastens the initial imbibition, but after 48 h of soaking, seed moisture does not present differences compared to non-sonicated seeds. It produces the scarification of the testa but does not affect the tegmen, so moistening occurs through the hilar region, as in control seeds. There is a significant linear and negative correlation between the germination of the seeds and the temperature reached during the sonication treatment, so that temperatures above 40 °C practically annulled the germination. The combination of 20 W and 60 s provided the greatest germination percentage, being the only treatment that statistically improves germination in relation to the control seeds. When the output power and/or holding time were higher, the temperature increased, and the germination percentage statistically decreased.

The control strategy is crucial for the effective and safe operation of the ORC system. A transient model of the ORC system was developed in the present work and validated by the experimental data of a 4 kW ORC prototype. Then, the effect of heat source temperature on the dynamic response and operation characteristics of the ORC system were analyzed. Five control strategies were compared: the constant working fluid mass flow rate mode, constant vapor superheat mode, constant vapor temperature mode, constant evaporation pressure mode and constant output power load mode. Under the constraint that the working fluid at the expander inlet should be superheated, we found that the constant vapor superheat mode enabled the safe operation with the largest range of heat source temperature, while the other four modes were only available for a certain temperature range. Apart from the constant output power mode, the constant evaporation pressure mode can also provide a relatively stable performance for the ORC unit. The variation of the thermal efficiency was limited when the heat source temperature was higher than 125 °C, except for the constant vapor temperature mode. Considering the high performance and stable operation of the ORC system, it is necessary to have different operation modes combined in the control strategy according to the specific working scenarios. [ABSTRACT FROM AUTHOR]

Nowadays, the original and secondary side high-order topology is more and more used in the wireless transmission of electric energy. To analyze the influence of compensation network parameters on transmission characteristics in the radio energy transmission system with S-LCC topology, firstly, the loop circuit equation was established by using the double coil equivalent circuit model, and the expression of system output power was derived. Secondly, the constant current and constant voltage characteristics of the system were discussed under different parameter conditions, Determined the relationship between the parameters of the compensation network aiming at the optimal output power, analyzed the influence of load resistance, resonant inductance and parasitic resistance on the system output power, and built a double coil wireless power transfer （WPT） physical system. The results show that the relationship between the primary and secondary side resonant capacitance with the optimal output power as the target can be accurately determined. With the increase of load resistance, the output power of the system increases first and then decreases, or increases first and then decreases, then increases and then decreases. The optimal load resistance decreases first and then increases with the decrease of resonant capacitance, decreases first and then increases with the decrease of resonant inductance, and increases with the increase of parasitic resistance. [ABSTRACT FROM AUTHOR]

Planar electromagnetic vibration energy harvester (EVEH) is a promising technology for compact, low form factor self-powered wireless devices. However, planar EVEH has the limitation of non-fully utilized magnetic flux gradient and low output power due to its structure constraint and weak magnetic flux gradient capturing capability. Planar coil is the key component in harvesting magnetic flux gradient and determining the output electromotive force (EMF) voltage and output power. A novel non-uniform distributed planar (NUDP) coil is proposed to break the current limitation of output power for the planar coil. The boost in output power is realized with tight inner windings and loose outer windings. The breakpoint is determined based on power increasing rate for each winding. The optimal winding radius for both inner and outer coils is investigated using discrete non-linear constraint heuristic optimization method. The designed NUDP coil-based EVEH achieves peak-to-peak output voltage of 305 mV and output power of 1.163 mW at 64.3 Hz resonant frequency and 0.05 g acceleration. It realizes 16.3% higher output power and 19.4% higher output voltage than uniform distributed planar (UDP) coil under the same spring and magnet. The power density of the proposed prototype reaches 9.616 mW/cm3g2, which is 15.025 times higher than the state-of-the-art EVEHs with the planar coil. [ABSTRACT FROM AUTHOR]

A vibration piezoelectric energy harvester (PEH) is usually designed with a resonance frequency at the external excitation frequency for higher energy conversion efficiency. Here, we proposed a bridge-shaped PEH capable of tuning its resonance frequency by applying a direct current (DC) electric field on piezoelectric elements. A theoretical model of the relationship between the resonance frequency and DC electric field was first established. Then, a verification experiment was carried out and the results revealed that the resonance frequency of the PEH can be tuned by applying a DC electric field to it. In the absence of an axial preload, the resonance frequency of the PEH can be changed by about 18.7 Hz under the DC electric field range from −0.25 kV/mm to 0.25 kV/mm. With an axial preload of 5 N and 10 N, the resonance frequency bandwidth of the PEH can be tuned to about 13.4 Hz and 11.2 Hz, respectively. Further experimental results indicate that the output power and charging response of the PEH can also be significantly enhanced under a DC electric field when the excitation frequency deviates from the resonance frequency. [ABSTRACT FROM AUTHOR]

Assessment of the wind turbine output power (WTG OP) during the operation and maintenance is one of the key indicators of operation quality evaluation. It is often carried out in the form of the wind speed-power curve. This form only considers the wind speed, and it is usually measured according to relevant IEC standards, e.g., IEC 61400-12, which has problems such as long measurement duration and harsh conditions. This study proposes a WTG OP assessment method based on SCADA data by using the regression-kriging algorithm. The influences of wind shear, turbulence intensity, and air density on the WTG OP were analyzed. Two regression-kriging output power models were built based on SCADA data (i.e., SCADA2power model) and wind resource parameters from met mast (i.e., wind2power model). According to the evaluation of the simulation result, it was found that the results of the two models are basically consistent. Based on the evaluation of historical data under normal operating conditions, the goodness of fitting output power of the two models is 99.9%. This shows that the regression-kriging-based wind turbine power performance assessment method based on SCADA data has an accurate prediction and the potential of general application in WTG OP evaluation. [ABSTRACT FROM AUTHOR]

In this paper, a different model based on Landau phase transition theory is proposed to characterize the martensite reorientation in magnetic shape memory alloy (MSMA) during energy harvesting. An energy harvesting system is designed to obtain the open-circuit voltage of the pick-up coil at low frequencies (below 40 Hz). It is found that the open-circuit voltage increases with the increase of frequency. Then connect the pick-up coil in series with a variable resistor and record the voltage and power of the resistor. The voltage of the resistor is found to approach that in the open circuit with the increase of the resistance. And the resistance-power relation of the variable resistor is a single-peak curve, and the resistance corresponding to the peak power is equal to the coil resistance. In the experiment, RMS voltage and output power up to 242.8 mV and 76.14 μW respectively, are obtained when the frequency is 40 Hz. The model parameters are identified according to the obtained experimental data. Finally, the proposed model is combined with Faraday's law and electrical formulas to predict the induced voltage and output power of the resistor. The predictions have achieved satisfactory accuracy, and the validity of the proposed method has been verified. [ABSTRACT FROM AUTHOR]

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The paper aims to develop a model using adaptive neuro-fuzzy inference system (ANFIS) architecture for enhancing output power of semitransparent photovoltaic thermal (PV/T) air collector by predicting the failure of PV panels for different weather conditions and different climate zones. Increased temperature of the photovoltaic module is a big problem which reduces its working life. The working and hotspot temperatures of photovoltaic (PV) modules have been reduced using ANFIS-based thermal design with optimal placement of PV cells which increase their life and reduce the failure rate which in turn increase the output power. The overall analysis reveals that output power is enhanced using ANFIS-based model by minimizing absolute error to 1.4% in 100 epochs by predicting accurate parameters. [ABSTRACT FROM AUTHOR]

In addition to the use of waste heat from the vessel's exhaust gas to save energy onboard, reduce the carbon emissions of the ship, and combine the characteristics of ship waste heat, mathematical modeling and testing of ship waste heat temperature difference power generation were carried out in this study. Finally, an experimental platform for temperature differential power generation was established to assess the impact of influencing agents on the efficiency of temperature differential power generation. The results show that the effect of different thermally conductive greases on the efficiency of temperature differential power generation tablets is basically the same. In addition, the rate of flow of cooling water, the cooling plate area, and the heat source temperature have more significant effects on the open-circuit voltage and maximum output power. The results show that the maximum power output growth rate increases with increasing cooling water flow, reaching 8.26% at 4 L/min. Likewise, increasing the heat source temperature enhances the maximum output power growth rate by 15.25% at 220 °C. Conversely, the maximum output power of the temperature difference power generation device decreases as the cooling plate area increases, and the maximum output power reduction rate is 15.25% when the cooling plate area is 80 × 200 mm2 compared to the case of using a cooling plate area of 80 × 80 mm2. Moreover, the maximum output power of the temperature differential power generation device reaches 13.6 W under optimal conditions. Assuming that the temperature difference power generation plate is evenly distributed on the tailpipe of the 6260ZCD marine booster diesel engine, it could save approximately 5.44 kW·h electric power per hour and achieve a reduction in CO2 emissions of 0.3435 kg per hour. [ABSTRACT FROM AUTHOR]

This article presents a high-performance radio frequency (RF) power amplifier (PA) module for which an optimum chip-level packaging structure is proposed to reduce the operating temperature of the RF PA monolithic microwave integrated circuit (MMIC). Because the output power (Pout) and the efficiency of an RF PA module are strongly affected by the thermal characteristics of the PA MMIC, various types of heat spreader materials and thermal interface materials have been examined to implement the PA chip-level packaging structure, and the optimum combination is proposed for a performance enhancement of the PA module in this article. In addition, the optimum form-factor of the heat spreader was suggested based on a thermal simulation. To verify the proposed PA chip-level packaging structure, a 10 W 6–18 GHz RF PA MMIC using a commercial 0.25-μm gallium nitride high electron mobility transistor process was designed and implemented for radar applications. The operating temperature of the PA MMIC on the proposed chip-level packaging structure shows a dramatic reduction of 24.8 °C, and accordingly, the average Pout and average power-added efficiency are enhanced by up to 9.2% and 2.8%, respectively, when compared with a PA module using the conventional chip-level packaging structure. [ABSTRACT FROM AUTHOR]

The impact of RAMAN-EDFA hybrid optical amplifier is analyzed for wireless super dense optical communication system. Evaluation has done in terms of OSNR, recived power and output power with data rate of 10 Gbps and channel spacing of 100 GHz respectively. Pump power of 500 mW at 1430 nm and 480 mW at 1480 nm for HOA have shown to cover maximum distance range of 350 km with input power of 45 mW with least fluctuation in the signals. [ABSTRACT FROM AUTHOR]

The major goal of this study is to achieve the cooling effect of a photovoltaic panel by employing titanium dioxide nanofluid as a cooling fluid in two passes circulation to lower the panel surface temperature, improve the performance of the photovoltaic/thermal system, and increase efficiency. Photovoltaic technology is constantly losing efficiency due to the high temperature of the PV panel's upper surface, which results in lower output power and lower overall efficiency. Five photovoltaics panels were utilized in this investigation to compare the three concentrations of Titanium Oxide nanofluid (1 wt%,2 wt%,3 wt%), as well as cooling by water and an uncooled penal. The output powers were (44.5, 44, 43.2, 42.6, and 39.5 W) when the three concentrations of Titanium Oxide nanofluid (3 wt%, 2 wt%, and 1 wt%) were used, then water cooled and uncooled, respectively. Cooling by nanofluid at concentration (3 wt%) had the highest efficiency (19.23%). Depending on the concentrations, there is a variation in temperature between the cooling fluids' output and inlet. For the three concentrations of Titanium Oxide nanofluid (3 wt%, 2 wt%, and 1 wt%), and water, the results were (7.3, 7.8, 8.3, 8.6 °C). When the surface temperatures of the solar panels were compared to the uncooled photovoltaic panels, it was discovered that the cooling system reduced the surface temperatures by 19.0%. All of the results were obtained at 30° tilt angles with fluid rotating in two passes. The high concentration of nanofluids produced the best results, resulting in a benefit of greater heat extraction.

The enthalpy–entropy approach, which is a rigorous and accurate method, was used to model the actual cycle of a gas turbine (GT). The constructed GT C# programming language code was used to study the effects of ambient temperature (Tam), relative humidity (RH), and ambient pressure (Pam) on GT output parameters. The results of the GT modeling program showed that the maximum (minimum) difference in GT output power (PGT) was 1.12% (0.01%) at a Tam of 39.7 °C (23.3 °C) compared with the actual output power of El Atf power station. As Tam increased from 14 °C to 40 °C, the PGT decreased by 19.01% (18.38%) of nominal GT power (250 MW) at 15% (95%) RH while GT thermal efficiency (ηth) decreased by 2.3058% (2.4431%) and the specific fuel consumption (SFC) increased by 7.12% (7.59%). The PGT decreased by 0.1497% and 0.7674% with an RH increase from 15% to 95%, respectively. The PGT decreased by 0.03675 and 0.16835 MW while ηth decreased by 0.0047% and 0.0243% at Tam values of 15 and 40 °C, respectively, when Pam was decreased from 1.013 to 0.990 bar. Using the compressor assumptions of each stage increases the humid air pressure by the same value and the efficiency of each stage is the same and equal to the compressor overall efficiency is more logical and leads to accurate results. The compressor isentropic efficiency was not affected by the bleeding air percent according to the assumptions used.