Improvement In Output Power Research Articles

Oxygen electrodes for protonic ceramic cells

Protonic ceramic cells (PCCs), including protonic ceramic fuel cells (PCFCs) and electrolysis cells (PCECs), are attracting increasing attention owing to several advantages such as their low activation energy for proton diffusion, fuel flexibility, absence of fuel dilution, and potentially lower housing/stacking costs at intermediate operating temperatures (400–600 °C). However, one of the major challenges for PCCs is the design and realization of oxygen electrodes for efficient oxygen reduction and water splitting reactions. Many research groups have devoted efforts to this research topic and have obtained encouraging results showing improved power output and current density in PCCs owing to the improvement of the oxygen electrode. This trend needs to be continued to enable the commercialization of the PCC technology. This review article describes the research progress in oxygen electrodes for PCCs, comprehensively summarizing literature work and offering prospective pathways for further development of high-performance oxygen electrodes.

Improvement in output power of vibration generators based on piezoelectric elements by using internal capacitor cancel control rectifier

AbstractRecently, energy harvesting has attracted increasing attention. The present study focuses on vibration generators based on piezoelectric elements by proposing an internal capacitor cancel control (ICCC) rectifier to improve the output power. The proposed rectifier cancels the internal capacitor to improve the output power while retaining the maximum output power. Accordingly, this paper experimentally demonstrates the improvement in output power by using the ICCC rectifier compared to conventional circuits and the previous proposed circuit.

AlGaN-based laser diodes with reduced Al composition in quantum barriers in the deep ultraviolet region

Subject of study. In AlGaN-based deep ultraviolet laser diodes, the quantum well affects the performance in the active region. Moreover, the composition of aluminum in quantum barriers in the quantum well matters to the performance of AlGaN-based deep ultraviolet laser diodes. It might be observed effectively by looking at performance indicators like the emitted power and optical confinement factor (band diagram, carrier concentration, and stimulated recombination). Method. Two deep ultraviolet laser diode devices with a nominated wavelength of 267.5 nm are simulated and compared in this paper using the Crosslight program LASTIP. The proposed deep ultraviolet laser diode device B with a reduced Al composition in the quantum barrier is used in the active region as opposed to the reference deep ultraviolet laser diode device A. Main results. This led to an improvement in emitted output power of 0.109 W with a reduced injection current of 0.02 A and an improvement in the optical confinement factor of 19%. Practical significance. The structure of the reference device is inspired by the experimental structure. The results of the proposed device are calculated and are evaluated based on parameters such as the improved conduction band barrier height, reduced valence band barrier height, and improved stimulated recombination rate. It outperforms the deep ultraviolet laser diode for the reference device.

Experimental and Theoretical Study to Increase the Solar-Organic Rankine Cycle Efficiency

Under conditions of high climate temperature and environmental pollution, scientists are turning to the use of new and renewable energy. The solar Organic Rankin Cycle (ORC) is greatest technology for converting low or medium-temperature energy sources into electricity. For the purpose of generating steam from solar energy to power the organic Rankin cycle a system consists of solar pond, flat plate collector and parabolic dish was designed, implemented, and tested to use in organic Rankin cycle (ORC). The novelty in the present work is the use of the solar pond as storage of heat that does not lose because the salinity gradient middle layer in the pond does not allow heat to pass through it, as well as the use of reheating to enhance the thermodynamic efficiency. Also, an analytical model has been made to enhance the output power and efficiency of the solar thermal ORC according to some organic control criteria. A Cycle of solar thermal power plants (ORC) is simulated with four refrigerants, R144a, R123, R124 and R245fa of working fluid’s performance. The cycle net-specific work can be verified at the highest efficiency as a function of turbine extraction numbers, over-temperature, and evaporation temperature. Superheated steam was obtained at a temperature of 327 °C to be used in the Rankin cycle of the solar energy system which is generated in this work. The maximum output power improvement is 9% when using the working fluid R123 for R124, 5.5% for R245fa, and approximately 2.8 for R144a. And the thermal efficiency of ORC is higher with R123 compared to 144a by about 2.2%. Furthermore, it also concluded that both inlet and outlet temperatures of a turbine are very important factors that affect the operational performance of organic Rankin cycle power generation systems.

Introducing an n-type electron deceleration layer to enhance the luminous efficiency of AlGaN-based DUV-LEDs

The internal quantum efficiency (IQE) of conventional AlGaN-based deep-ultraviolet (DUV) light-emitting diodes (LEDs) is seriously limited by the poor and inhomogeneous carrier injection. The typical solution is to optimize the structure parameters of p-type region and active region. In this work, however, we try to address this issue by introducing an n-type electron deceleration layer (EDL) underneath multiple quantum wells (MQWs). On one hand, the electron deceleration layer helps to decrease the electron velocity and thus increase the electron capture rate. On the other hand, it can also reduce barrier heights in the band valence and thus enhance the hole transport in the multiple quantum wells. As a consequence, the concentrations of electrons and holes in the multiple quantum wells were significantly increased, resulting in the enhancement of radiative recombination. Compared to the conventional structure, the DUV-LED structure with an electron deceleration layer achieves a higher internal quantum efficiency, leading to a 39% improvement in the light output power. It is believed that performing energy-band engineering in n-type region has great application prospects for high-performance DUV-LEDs.

On analysing vibration energy harvester with auxetic core and magneto-electro-elastic facings

Powering systems without heavy maintenance-intensive batteries is a challenge for various engineering applications. Often, energy in the form of heat, vibration, sound etc., is squandered while operating many machines/structures. A judicious utilisation of these potent energies using energy harvesters (EH) will reduce the degree of dependency on depletable energy sources. Sometimes, EH acts as a parasitic mass and consumes additional space. To address this issue, the current work proposes a lightweight vibration-based bimorph beam (VBBB) EH constituted of multifunctional magneto-electro-elastic (MEE) facesheets and auxetic metamaterial core (AMC). The frequency response functions, which consider series and parallel configurations of the active ME layers, are derived using distributed parameter single-mode formulation to quantify the system’s output response. The overall effect of the negative Poison’s Ratio of the auxetic materials, combined with the material, geometric and parameters such as the number of turns and resistances, is investigated. The advantage of using an auxetic core to enhance the energy harvester’s performance is realised through an improved power output as the thickness of the auxetic core layer rises. The maximum values of the output parameters are witnessed for larger auxetic angles and lower rib–length ratios. Meanwhile, greater values of the geometrical parameters like length-to-thickness ratio and length-to-width ratio result in enhanced power harvested. A comparative study justifies that under similar working conditions, the power output of the auxetic-based energy harvester is almost 1.5 times more than the conventional metal-based energy harvesters. Further, auxetic-based EH reported a 22% weight reduction for the same power output obtained from the conventional metal-based EH. This enables the lightweight construction of low-powered smart systems with enhanced efficiency. It is believed that the results of this article will lead to further studies on utilising multifunctional composites and metamaterials for complex engineering applications.

All-day working photovoltaic cooling system for simultaneous generation of water and electricity by latent heat recycling

The photovoltaic (PV) cooling system based on solar-driven interfacial water evaporation (SIWE) system can effectively reduce the temperature of PV panels and obtain fresh water, but it cannot work at night during which there is no heat source input. In this work, we proposed a novel SIWE-based PV cooling systems with optimized performance that can achieve all-day working. In this hybrid system, the heat generated by the PV panel is extracted as the form of vaporization latent heat through membrane distillation (MD). Then it transferred along with the condensation of water vapor and stored in Phase Change Material (PCM), which is used to achieve electric power generation by thermoelectric effect at night. The hybrid system can achieve an 19.5 % improvement of output power compared with that without cooling method. Additionally, a 1.55 kg m-2 h−1 fresh water output with a salt rejection rate more than 99.9 % are realized under 3-sun irradiation. At the same time, it can also achieve a peak power output of 6 W m−2 at night by the release of latent heat stored in PCM. This hybrid system may provide a new idea to broaden application scenarios of traditional SIWE-based PV cooling systems.

Improvement of Output Power and Bandwidth for Terahertz Extended Interaction Klystron With Multiple Resonance Cavities

In this article, an extended interaction klystron (EIK) in a terahertz band with high power, high efficiency, and wide bandwidth based on a mode overlap scheme and multiple resonance cavities is proposed. The high-frequency characteristics and electric field distribution of modes in 17-gap cavity are analyzed. And <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\pi $ </tex-math></inline-formula> mode and 15/ <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$16\pi $ </tex-math></inline-formula> mode are selected as the two adjacent working modes to realize mode overlap to expand the bandwidth. The number of cavity gaps and the length ratio of long and short slots are carefully optimized to achieve the appropriate frequency interval between modes. Then the sensitivity analysis of key parameters requires that the processing tolerance of the circuit should not exceed <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$5~\mu \text{m}$ </tex-math></inline-formula> . The stability of the circuit is analyzed by using the normalized electronic conductance to ensure that the circuit will not produce oscillation. Finally, with the conditions of 0.3-A current, 18.5-kV voltage, and 0.02-W input power for the designed G-band six-cavity EIK, the PIC simulation results shows that the mode overlap can be achieved in different cavities, and the circuit can obtain a power of 740 W, a gain of 45.68 dB, a 3-dB bandwidth of 1.92 GHz, and an efficiency of 13.3%. The power, bandwidth, and efficiency have obvious improvement compared with other reported EIKs in the same frequency band. In addition, the consistency of the simulation results trend between AJDISK and CST also proves that the circuit we designed is reliable and feasible for the terahertz band EIKs with high performance in the future.

Data-Driven Approach for Condition Monitoring and Improving Power Output of Photovoltaic Systems

Increasing renewable energy targets globally has raised the requirement for the efficient and profitable operation of solar photovoltaic (PV) systems. In light of this requirement, this paper provides a path for evaluating the operating condition and improving the power output of the PV system in a grid integrated environment. To achieve this, different types of faults in grid-connected PV systems (GCPVs) and their impact on the energy loss associated with the electrical network are analyzed. A data-driven approach using neural networks (NNs) is proposed to achieve root cause analysis and localize the fault to the component level in the system. The localized fault condition is combined with a parallel operation of adaptive neurofuzzy inference units (ANFIUs) to develop a power mismatch-based control unit (PMCU) for improving the power output of the GCPV. To develop the proposed framework, a 10-kW single-phase GCPV is simulated for training the NN-based anomaly detection approach with 14 deviation signals. Further, the developed algorithm is combined with the PMCU implemented with the experimental setup of GCPV. The results identified 98.2% training accuracy and 43000 observations/sec prediction speed for the trained classifier, and improved power output with reduced voltage and current harmonics for the grid-connected PV operation.

Design and Analysis of Hybrid-Excitation Variable Flux Memory Motor for Traction Applications: Improving Output Power in High-Speed Area During Six-Step Operation Mode

Design and Analysis of Hybrid-Excitation Variable Flux Memory Motor for Traction Applications: Improving Output Power in High-Speed Area During Six-Step Operation Mode

Endogenous electric field accelerates phenol degradation in bioelectrochemical systems with reduced electrode spacing.

Reducing the electrode spacing in bioelectrochemical systems (BESs) are widely reported to improve power output, which was mainly attributed to the decrease of ohmic resistance (Rohm) for a long time. Here we found the change of endogenous electric field (EF) intensity was the key to improve electroactivity in response to a reduced electrode spacing, which also accelerated phenol biodegradation. Correlation and principal components analysis revealed that the microbial community of electroactive biofilm (EAB) was independent of Rohm, while the EF intensity was found closely related to most of predominant genera. A strong EF selectively enriched phenol-degrading bacteria Comamonas in suspension and Geobacter in EAB, contributed to the improvement of degradation efficiency. EF also induced the secretion of extracellular polymeric substances, protected EAB from being inactivated by phenol. Our findings highlighted the importance of EF intensity on BESs performance, providing new insights into the design and application of BESs in wastewater treatment.

Expert knowledge-based peak current mode control of electrosurgical generators for improved output power regulation.

Electrosurgical generators (ESG) are widely used in medical procedures to cut and coagulate tissue. Accurate control of the output power is crucial for surgical success, but can be challenging to achieve. In this paper, a novel expert knowledge-based peak current mode controller (EK-PCMC) is proposed to regulate the output power of an ESG. The EK-PCMC leverages expert knowledge to adapt to changes in tissue impedance during surgical procedures. We compared the performance of the EK-PCMC with the classical peak current mode controller (PCMC) and fuzzy PID controller. The results demonstrate that the EK-PCMC significantly outperformed the PCMC, reducing the integral square error (ISE) and integral absolute error (IAE) by a factor of 3.88 and 4.86, respectively. In addition, the EK-PCMC outperformed the fuzzy PID controller in terms of transient response and steady-state performance. Our study highlights the effectiveness of the proposed EK-PCMC in improving the regulation of the output power of an ESG and improving surgical outcomes.

A Tall Gate Stem GaN HEMT With Improved Power Density and Efficiency at Ka-Band

In this letter, AlGaN/GaN HEMTs with tall-gate-stem structures were realized to improve the power performance of Ka-band devices, and a film thinning process is adopted in the fabrication process to reduce the parasitic capacitance caused by the thick silicon nitride film. According to the S-parameter measurement results, devices owning a tall-gate-stem structure and undergoing the film thinning process have higher cut-off frequency (fT) and maximum oscillation frequency (fmax) values with lower extracted parasitic capacitance. For the load-pull measurement result, the AlGaN/GaN HEMT with a tall gate stem has improved output power density (Pout) and power added efficiency (PAE) at Ka-band. The device with the elevated stem shows a steady-state current density of 883 mA/mm and a maximum transconductance of 323 mS/mm at 20 V bias, and it achieves fT of 39.5 GHz, fmax of 112.9 GHz with the maximum PAE of 24.6 % and the maximum Pout of 6.6 W/mm at 38 GHz.

Humidity-thermoelectric bimodal energy harvester for sustainable power generation

Thermoelectricity is a promising solution to utilize waste heat for electrical energy, whereas thermal saturation or the temporal absence of thermal gradient incurs discontinuities in energy harvesting. Meanwhile, utilizing humidity has recently emerged as an energy harvesting stimulus owing to its sustainable availability, but its low power output limits feasibility. Herein, we report a humidity-thermoelectric bimodal energy harvester (HT-BET) for sustainable and complementary power generation. Aqueous and air electrothermal wave (ETW) uniformly deposits palladium nitrate precursors and directly fabricates tunable palladium/palladium oxide/carbon-based composites (Pd/PdxOy @C) in terms of morphology, composition, and interfacial characteristics, thereby screening optimal electrochemical electrodes for humidity-driven energy-harvesting cells. An asymmetric cell incorporating a solidified poly(4-styrenesulfonic acid) (PSSH) between screened Pd/PdxOy @C and carbon fibers is integrated with a thermoelectric p–n junction employing Bi2Te3 cells to complete the HT-BEH fabrication. The single HT-BEH exhibits highly improved output power by 67 times (0.3 µW), compared with a thermoelectric cell (4.5 nW) at 308.15 K (∆T = 10.35 K) and 30% relative humidity (RH). Furthermore, the flexible multi-array of HT-BEHs achieves 0.41 µW output power for 16 h through the human skin temperature, sweat, and surrounding RH, thereby confirming the capability of sustainable energy sources for wearable platforms in ambient environments.

Theoretical analysis on improving output power of continuous-wave single-wavelength two-photon pumped Rb-vapor laser with mid-infrared seed laser

We theoretically prove that introducing 5.23-μm mid-infrared (MIR) seed laser can greatly increase output power of two-photon pumped Rb-vapor laser (Rb-TPAL) for the first time. Firstly, MIR laser stimulated radiation is added to the three-dimensional calculation model we reported in Ref. [1]. Then we simulate the Rb-TPAL pumped by a high-power continuous-wave laser diode and analyze the effects of MIR seed power and direction, vapor cell temperature and length, waist radii of pump and MIR seed, and output mirror reflectance on the output characteristics. The results show that by optimizing the above parameters, the MIR seed laser can not only significantly improve the output power and conversion efficiency of blue and MIR laser, but also reduce the pump and temperature thresholds of blue laser. This study can be useful for designing a TPAL system with high-power dual-waveband laser output.

An electromagnetic energy harvester for applications in a high-speed rail pavement system

Energy harvesting from ambient environment is one of the effective solutions to supply power for low power electronic devices. There are still some challenges such as poor space utilization and low power density for pavement energy harvesters. In this paper, an electromagnetic energy harvester with the double rockers is proposed to harvest the human footstep energy from high-speed rail pavement environment. Combined with two one-way bearings, the proposed double-rocker structure converts up and down motion of plate into a unidirectional rotation motion of the shaft. As the effect of the inertia flywheel, the velocity attenuation of the shaft of generator is slowed down. The dynamic model of the energy harvester with the engagement and disengagement phase is explored. Moreover, the input force and the angular velocity are simulated under the input of the various sinusoidal displacements and frequencies. The simulation and experimental results show that it can obtain the maximum output power of 466.6 mW under the vibration frequency of 5 Hz and the displacement of 10 mm. Further, the inertia flywheel can enhance the system stability and achieve the improvement of average output power by 49.45 % compared with no flywheel system. A pavement block with four energy harvesters is assembled and the actual field test proves it can obtain the maximum voltage of 54.4 V and the output power of 1.034 W, which proves the proposed electromagnetic energy harvester has great potential to achieve self-powered monitoring system and power for the low power electronic devices in high-speed rail environment.

Numerical Investigation on Aerodynamic Characteristics of Dual-Rotor Wind Turbines

Improving power output and reducing costs are crucial to the sustainable development of offshore wind power. In the present study, a dual-rotor wind turbine (DRWT) is proposed to improve wind energy capture efficiency by adding an auxiliary rotor behind the main rotor. The two rotors can be the same size or different sizes. This will result in different aerodynamic characteristics for DRWTs. In this paper, the NREL Offshore Baseline-5 MW and the NREL 750 kW single-rotor wind turbines (SRWTs) are used to configure three different types of DRWTs. The power output and wake characteristics of three different DRWTs with co-rotating (CO-DRWT) and counter-rotating (CR-DRWT) configurations on an actual scale are compared. The Reynolds-averaged Navier–Stokes (RANS) model with k-ω SST (shear stress transport model) is used to simulate the unsteady flow generated by the DRWT’s rotation. The present numerical results show that the power coefficient of the 5 MW-5 MW CO-DRWT can reach 1.22 times that of the 5 MW SRWT. Moreover, a faster wake velocity deficit recovery is found in the 5 MW-5 MW DRWTs because the high-velocity flow caused by the merging and mixing of the trailing vortices of the 5 MW-5 MW DRWTs brings an energy supplement to the wake velocity deficit.

A high-performance electromagnetic vibration energy harvester based on ring magnets with Halbach configuration

• First contribution to the applicability of Halbach arrays within ring-shaped structures. • Halbach arrays do not ensure improved output power of an electromagnetic harvester. • Optimization of the proposed transducer improved its output power by almost 30%. • Parameters for power maximization are different from those for voltage maximization. • The highest NPD performance compared to other devices with Halbach arrays is reached. This paper proposes and studies a ring-shaped architecture with Halbach configuration for electromagnetic vibration energy harvesters. The proposed transducer consists of three ring magnets with a linear Halbach array that concentrates its magnetic field in the inner space of the mechanism where a single vertically-centered concentric coil has been located. This particular structure allows to increase the resonant mass within a fixed dimensions of the transducer and reduces the coil resistance for the same number of turns, enhancing its power generation capabilities. The ring-shaped architecture has been compared with several ring magnet arrangements, including single magnets, double-magnet arrays, and an alternative linear Halbach array, using numerical simulations to determine their influence on its performance. Consequently, this work is the first contribution to the applicability of Halbach configurations for electromagnetic vibration energy harvesters within ring-shaped architectures. Also, a geometrical optimization of the proposed transducer has been conducted, mainly as a function of the inner radius, the height, and the wire diameter of the coil, to increase its power generation. The maximum simulated output power for the optimized generator reaches 3.61 mW for an input harmonic vibration of 0.03 g at a frequency of 61.7 Hz, corresponding to a 29.08 mW/cm 3 g 2 normalized power density performance, significantly higher than devices described in the literature for similar applications. Besides, a harvester prototype based on the proposed configuration has been fabricated to validate the modeling strategy used and to certify the reliability of the proposed design regarding power generation capabilities. Several experimental tests have been conducted under harmonic excitation with frequencies ranging between 10 Hz to 100 Hz and a vibration amplitude of 0.03 g. The experimentally measured induced voltage and electrical output power have been found in good agreement with their corresponding simulated values, with a difference of about 2.1% and 5%, respectively.

Development of a novel high bandwidth piezo-hydraulic actuator for a miniature variable swept wing

Piezoelectric hydraulic actuators, instead of electromagnetic actuators, have a wide application prospect in the field of aerospace due to the merits of light weight, compact structure, non-magnetic interference, etc. Many researches have been devoted to boosting output powers of actuators with the help of large-scale piezoelectric stacks. However, the existing actuator operates at a relatively low frequency, limiting the output power improvement and the application. In this work, a high bandwidth piezo-hydraulic actuator (PHA) is proposed based on a resonant active valve piezoelectric pump with sandwich bending transducers (SBTs). The configuration and principle of the PHA are presented and analyzed. A tested setup of the PHA is established, and the maximum output velocity and thrust are measured to be 30.5 mm/s and 53.2 N under 1.6 kHz, and the output power reaches up to 294 mW under the load of 30 N. In addition, a variable swept wing (VSW) driven by the PHA is studied. The composition and deformation process of the PHA-Based VSW are discussed; the dynamic model of the PHA-Based VSW is derived; the tested results indicate that the maximum angular velocity and torque of the PHA-Based VSW are 1.135 rad/s and 1.701 N·m, and the swept angle range is 15.9° ∼ 64.1°

Steady-state performance analysis of permanent magnet synchronous generator with capacitive assistance

This paper presents the steady-state performance analysis of an electrical connection scheme that improves the power factor and output power of a three-phase interior-rotor permanent magnet generator (IPMSG). The inverse saliency ratio ranges from 1 to 6. A three-phase capacitor is connected across the stator winding, close to the generator load, for each ratio. Leading current from the capacitor was used to improve the lagging power factor of the machine, maintain the load voltage under varying load conditions, and enhance the output power conversion ability, which the inverse saliency ratio scheme could not do alone, and without the need for external power electronics control circuitry. The numerical solution of the study was implemented in MATLAB®. The proposed IPMSG performance curves were enhanced with the generator yielding an improved output power of about 11.1% when compared with the inverse saliency ratio scheme without capacitors.