Stable Output Research Articles

Self-cleaning transparent Cu2Y2O5/Tb:Bi2Sn2O7 quantum dots/Bi2O3 pn junction for photovoltaic enhancement via synergism of up-conversion fluorescence and surface hydrophobicity

The competitiveness between photovoltaic conversion efficiency (PCE) and transparency would be the bottleneck of transparent device for actual applications, as well as the high maintenance cost. In this work, the self-cleaning transparent device in interfacial Tb:Bi2Sn2O7 QDs modified Cu2Y2O5/Bi2O3 pn junction is prepared via a simple approach of sol-gel-hydrothermal method. The obtained Cu2Y2O5/Tb:Bi2Sn2O7 QDs/Bi2O3 exhibits high transmittance of ∼85 %, obvious photovoltaic enhancement of ∼2.0 × 103-folds (PCE of ∼1.17 %), stable output in 5 months cycles and a good self-cleaning via the hydrophobicity (contact angle of ∼123.4°). It's mainly attributed to the Tb:Bi2Sn2O7 QDs and lamellar Bi2O3 array. Besides appropriate potential and high quantum yield, the Tb:Bi2Sn2O7 QDs, with the synergism of up-conversion fluorescence and interface/surface optimization, can improve the carrier kinetic equilibrium for achieving PCE-transparency balance, as well as increasing p-type conductivity through the synergism of Cu+/Cu2+ and interstitial oxygen. Moreover, the regular lamellar array can enhance solar efficiency via optimized surface, meanwhile achieving self-cleaning via the surface hydrophobicity and enhancing structural stability via the regular interval, making it being advantageous in actual applications of energy and information field, including windows, smart devices, etc.

Experimental investigation for the influence mechanism of air intake method and humidity level on performance of proton exchange membrane fuel cells

As pivotal component of hydrogen fuel cell vehicles (HFCVs), proton exchange membrane fuel cells (PEMFCs) play a crucial role in determining performance and energy efficiency of HFCVs. In this study, comprehensive bench tests of fuel cell stack and electrochemical impedance spectroscopy (EIS) tests of single cells were conducted, and influence mechanisms of air intake methods and humidity levels on performance of stack and single cells at different locations were analyzed in depth. The results indicate that counter-flow inlet method exhibits superior voltage output performance and stability across various relative humidity (RH) and current densities (CDs). A moderate increase in RH can mitigate performance degradation, but excessive humidity can lead to flooding. When RH is increased to 60%, the voltage difference between co-flow and counter-flow of fuel cell stack does not exceed 0.05 V at 1.6 A/cm2. Meanwhile, the performance of cells near inlet end plate is consistently worse than those farther away under different inlet conditions. In addition, the performance trend of single cells in serpentine channels aligns with that of fuel cell stack, underscoring strong adaptability of mechanisms influencing performance under different conditions. These findings provide theoretical guidance and data support for optimizing performance and preventing failures in PEMFCs.

Enzyme-Enabled Droplet Biobattery for Powering Synthetic Tissues.

Enzyme-enabled biobatteries are promising green options to power the next-generation of bioelectronics and implantable medical devices. However, existing power sources based on enzymatic biofuel chemistry exhibit limited scale-down feasibility due to the solid and bulky battery structures. Therefore, miniature and soft alternatives are needed for integration with implants and tissues. Here, a biobattery built from nanolitre droplets, fuelled by the enzyme-enabled oxidation of reduced nicotinamide adenine dinucleotide, generates electrical outputs and powers ion fluxes in droplet networks. Optimization of the droplet biobattery components ensures a stable output current of ~13,000 pA for over 24 h, representing a more than 600-fold increase in output over previous approaches, including light-driven processes. The enzyme-enabled droplet biobattery opens new avenues in bioelectronics and bioiontronics, exemplified by tasks such as the ability to drive chemical signal transmission in integrated synthetic tissues.

Inflation targeting and output stabilization in an estimated monetary model

This paper studies determinacy conditions in a monetary model with an interest rate rule. In addition to the inflation rate as an argument of the policy rule, we introduce a second argument: output, a case empirically relevant but overlooked in the existing literature on monetary models with flexible prices. Firstly, we estimate a model with money in utility and the production function. We find that an aggressive response to inflation does not necessarily guarantee determinacy anymore. Secondly, we compare monetary policy in the pre-Volcker era and the post-Volcker era. We find that, after the appointment of Paul Volcker, the Federal Reserve started to respond more aggressively to inflation and less aggressively to output. Indeterminacy is pervasive: the equilibrium is indeterminate in both sub-samples. Thirdly, we estimate the impulse response functions. We find that monetary shocks, sunspot inflation shocks, and productivity shocks have long-lasting effects on inflation, output, and interest rates.

Black phosphorus film as Q-switcher in neodymium-doped fiber laser

We present the successful development of a 1089.4 nm Q-switched laser employing a neodymium-doped fiber (NDF) as the active fiber and black phosphorus (BP) as the saturable absorber (SA). The BP SA was fabricated by inserting BP compound into a polyvinyl alcohol (PVA) host polymer, exhibiting a saturable absorption of 2.8 %. Integrated into an NDFL ring cavity, the SA modified the cavity loss, enabling the production of Q-switched pulses. With an increase in the 808 nm pumping power from 108.6 to 155.9 mW, the laser output pulse duration decreased from 3.74 to 3.54 μs, while the repetition rate improved from 40.6 to 51.0 kHz. The laser demonstrated a stable pulse train output, with a fundamental frequency signal to background noise ratio of 45.78 dB. The highest pulse energy of 1.3 nJ was recorded at 155.9 mW pump power. To the best of our knowledge, this represents the first utilization of BP as a SA or Q-switcher within an NDFL cavity.

Design and analysis of a novel rotary inertance hydraulic converter with the continuous controlling turntable

The inertance hydraulic converter is an energy-efficient hydraulic component, its output efficiency and dynamic performance are seriously affected by the switched valve. This paper proposed an innovative a rotary inertance hydraulic converter (RIHC), which uses a continuous controlling turntable to determine the ratio of the high pressure oil and the low pressure oil to change the output energy, instead of the discrete controlling of the switched valve. The working principle and mechanical design of the RIHC are described, and mathematical models are established. The effects of the key variables on energy efficiency are evaluated using numerical analysis. The operating performance is analyzed based on simulation, and a control strategy to achieve stable system output is proposed. The results provide a foundation for theoretical research and practical application of the novel RIHC.

A DEEP LEARNING ENSEMBLE APPROACH FOR X-RAY IMAGE CLASSIFICATION

The application of deep learning-based intelligent systems for X-ray imaging in various settings, including transportation, customs inspections, and public security, to identify hidden or prohibited objects are discussed in this study. In busy environments, x-ray inspections face challenges due to time limitations and a lack of qualified personnel. Deep learning algorithms can automate the imaging process, enhancing object detection and improving safety. This study uses a dataset of 5094 x-ray images of laptops with hidden foreign circuits and normal ones, training 11 deep learning algorithms with the 10-fold cross-validation method. The predictions of deep learning models selected based on the 70% threshold value have been combined using a meta-learner. ShuffleNet has the highest individual performance with 83.56%, followed by InceptionV3 at 81.30%, Darknet19 at 78.92%, DenseNet201 at 77.70% and Xception at 71.26%. Combining these models into an ensemble achieved a remarkable classification success rate of 85.97%, exceeding the performance of any individual model. The ensemble learning approach provides a more stable prediction output, reducing standard deviation among folds as well. This research highlights the potential for safer and more effective X-ray inspections through advanced machine learning techniques.

Design and multi‐objective optimisation of double‐layer non‐uniform Halbach external‐rotor permanent magnet synchronous motor

AbstractIn order to further improve the output torque and stability of the external rotor permanent magnet synchronous motor, a double‐layer non‐uniform Halbach external rotor permanent magnet synchronous motor (DNH) structure is proposed and optimised. Finite element models of DNH and other structures are established to compare the electromagnetic characteristics of these motors and verify the superiority of the proposed structure. Secondly, the multi‐objective whale optimisation algorithm is improved, and the algorithm is tested by test function to verify the improvement effect. Further, the Spearman correlation of the parameters is calculated, and the parameters are layered. The first layer parameters are optimised by the improved multi‐objective whale optimisation algorithm, and the second layer parameters are optimised by parameter scanning. Finally, the motor performance of the initial scheme, single layer optimisation scheme, and hierarchical optimisation scheme is compared by simulation. The simulation results show that the hierarchical optimisation method is superior to the single layer optimisation method. By comparing with other schemes, the performance advantages of hierarchical optimisation DNH in terms of average output torque, cogging torque, torque ripple, permanent magnet cost and other parameters are proved, as well as the effectiveness of the optimisation method.

SERS and electrochemical dual-mode detection of miRNA-141 by using single Au@Ag nanowire as a new platform.

As biomarkers of cancer, the accurate and sensitive detection of microRNAs is of great significance. Therefore, we proposed a surface-enhanced Raman scattering (SERS)/electrochemical (EC) dual-mode nanosensor for sensitively detecting miRNA-141. The nanosensor uses Au@Ag nanowires as a novel SERS/EC sensing platform, which has the advantages of good biocompatibility, fast response, and high sensitivity. The dual-mode nanosensor can not only effectively overcome the problem of insufficient reliability of single signal, but also realize the amplification and stable output of the detection signal, to ensure the reliability and repeatability of miRNA detection. With this sensing strategy, the target miRNA-141 can be detected over a wide linear range (100 fM to 50 nM) (LOD of 18.4 fM for SERS and 16.0 fM for electrochemical methods). In addition, the process shows good selectivity and can distinguish miRNA-141 from other interfering miRNAs. The actual analysis of human serum samples also proves that our strategy has good reliability, repeatability, and has broad application prospects in the field of analysis and detection.

Design and Analysis of a Vertical Axis Ocean Current Turbine Tunnel Using SolidWorks Computational Fluid Dynamics

The development of renewable energy in the marine power generation sector presents a promising approach to producing electrical energy in a sustainable and environmentally friendly manner. Indonesia, with its vast oceanic territory, holds significant potential for harnessing marine energy. However, the relatively slow speed of ocean currents in the region, typically ranging from 0.1 m/s to 1.5 m/s, poses a challenge to the efficiency of marine power generation. To overcome this limitation, this research focuses on the design and analysis of a vertical-axis ocean current turbine tunnel aimed at increasing the speed of ocean currents, thereby enhancing the overall efficiency of energy production. The study combines a thorough literature review with experimental research methods, utilizing SolidWorks Computational Fluid Dynamics (CFD) software to simulate the tunnel's impact on ocean current velocity. The simulations reveal that the tunnel construction significantly boosts current speeds, increasing them from 1.0 m/s to 1.7 m/s, and from 1.5 m/s to 2.6 m/s. This increase in velocity directly translates to higher kinetic energy available for conversion into electrical power by the turbine. Moreover, the study shows that the tunnel construction contributes to a more uniform flow of ocean currents, as evidenced by the Reynolds numbers obtained—100.250 at a current speed of 1.0 m/s and 150.375 at 1.5 m/s. These values, being below 2000, indicate laminar flow conditions within the tunnel, which are beneficial for optimizing turbine performance by reducing turbulence and ensuring a stable energy output. The findings underscore the effectiveness of the tunnel design in improving the efficiency of vertical-axis ocean current turbines, making it a viable solution for enhancing renewable energy production in regions with low ocean current speeds.

Investigation on the characteristics of Q‐switched pulses in an EDFL based on the saturable absorption effect of germanene

AbstractIn this paper, an all‐fiber passively Q‐switched (QS) Er‐doped fiber laser (EDFL) was designed and successfully demonstrated by innovatively employing germanene as saturable absorber (SA). Due to its low‐warp honeycomb structure and remarkable zero bandgap property, germanene exhibits excellent potential for highly stable broadband pulse modulation. Based on the saturable absorption effect of germanene, a stable passive QS laser output was successfully achieved at 1530 nm under a threshold pump power of 63.7 mW. With the pump power increasing from 63.7 to 403.5 mW, the pulse repetition rate increases from 48.5 to 121.2 kHz accordingly. Meanwhile, we observe that the pulse width was shortened from 3.54 μs to 890 ns. The experimental results prove that germanene nanosheets have a promising future as a Q‐switcher in fiber lasers.

Research on flexible and fast tunable laser in coherent optical communications

A flexible and fast tunable laser based on hybrid integration is proposed, which can realize single and multi-wavelength reconfigurable output by controlling the on or off of semiconductor optical amplifiers (SOAs) array in combination with a tunable arrayed waveguide grating (AWG). The wavelength switching time achieves <0.8 ns. The stable output power of the tunable laser is >16 dBm with >70 dB side mode suppression ratio (SMSR) and 6.4 nm tunability. The designed laser exhibits narrow linewidths down to 1 kHz and longitudinal mode spacing of 0.8 nm, which is suitable for ITU-T standards and the output power meets the requirements of coherent optical communications. A broadened spot-size converter (SSC) for bi-directional transmission is designed and implemented with a power coupling efficiency about 0.93 and an optical bandwidth of more than 200 nm. Demonstration of the 100 Gb/s quadrature phase shift keying (QPSK) self-homodyne coherent optical transmission based on designed laser is achieved.

Resilience Improvement of Microgrid Cluster Systems Based on Two-Stage Robust Optimization

For microgrids in deep and remote sea areas, ocean currents are widely used as an emerging power generation resource. Implementing ES systems is crucial for smooth power output and grid stability. The stability of power output from sea current energy generation faces challenges due to speed fluctuations. Enhancing resilience requires addressing transmission line failures caused by extreme seabed conditions, and ensuring operational security. An ES configuration method considering line faults based on two-stage robust optimization is presented in this paper. First, in order to simultaneously consider planning and operation, a defender–attacker–defender (DAD) model was established. Additionally, the capacity, rated power, and charging/discharging power of ES during operation were jointly optimized through the column-and-constraint generation (C&amp;CG) algorithm. In addition, the rationality and effectiveness of the proposed method were demonstrated through experiments on modified IEEE six-bus and fifty-seven-bus systems. The results show that a distributed ES configuration increased system resilience by 54.60% and reduced abandoned power rate by 57.06% compared with the situation without ES configuration.

Circuit firing homeostasis following synaptic perturbation ensures robust behavior.

Homeostatic regulation of excitability and synaptic transmission ensures stable neural circuit output under changing conditions. We find that pre- or postsynaptic weakening of motor neuron (MN) to muscle glutamatergic transmission in Drosophila larva has little impact on locomotion, suggesting non-synaptic compensatory mechanisms. In vivo imaging of MN to muscle synaptic transmission and MN activity both show that synaptic weakening increases activity in tonic type Ib MNs, but not in the phasic type Is MN that innervate the same muscles. Additionally, an inhibitory class of pre-MNs that innervates type Ib-but not Is-MNs decreases activity. Our experiments suggest that weakening of MN evoked synaptic release onto the muscle is compensated for by an increase in MN firing due to a combined cell-autonomous increase in excitability and decreased inhibitory central drive. Selectivity for type Ib MNs may serve to restore tonic drive while absence of firing adjustment in the convergent Is MN can maintain the contraction wave dynamics needed for locomotion.

Improving High-Voltage Cycling Stability and High-Rate Capability of Sodium-Ion Layered Cathode Oxides through Trace Amounts of Low-Valence Metals.

With the increasing demand for clean energy sources, the need for large-scale energy storage systems to ensure the stable output of renewable energy sources, such as wind and solar, has also increased. Sodium-ion batteries have emerged as a potential solution for these storage systems owing to their high energy density, abundance in the Earth's crust, and low cost. However, the larger atomic radius of sodium ions results in higher energy barriers for ion migration in cathode materials, which can affect the cycle life and rate performance of the battery. Therefore, developing a suitable structure that facilitates rapid sodiation and desodiation and maintains good cycling stability remains a significant challenge. This study aimed to reduce the content of trivalent manganese ions and minimize the impact of the Jahn-Teller effect to enhance the capacity retention of manganese-based layered oxides. Additionally, a series of P2-type Na0.78Li0.1ZnxNi0.15-xMn0.75O2 compounds were successfully synthesized through doping with divalent zinc ions. Structural analyses of the doped material indicated that Zn doping did not alter the crystal structure but increased the interlayer distance of the transition metals. Electrochemical performance tests revealed that appropriate Zn2+ doping promoted sodium-ion diffusion and improved the reversible capacity of the battery. This study provides a promising approach for developing sodium-ion batteries with rapid charging and discharging capabilities.

Dual-wavelength single-frequency Tm:ZBLAN fiber amplifier operating at 1.94 and 2.33 μm

We report here, to the best of our knowledge, the first dual-wavelength single-frequency thulium-doped fiber amplifier operating at 1.94 and 2.33 μm. The single-stage, Tm3+-doped ZBLAN fiber amplifier, ground-state pumped by a 793-nm laser diode, yielded a stable output power of 1.45 W at 2332 nm and 7.4 W at 1939 nm. The injection of 1.94-μm seed effectively suppresses parasitic lasing in the 2.33-μm Tm fiber amplifier. The experiment investigated the competitive relationship between the 2-μm transition and the 2.3-μm transition, and the results suggest that the injection of 1.94-μm seeds is beneficial to the improvement of 2.33-μm efficiency, while the injection of 2.33-μm seed slightly reduces the 1.94-μm efficiency.

Self-cleaning transparent photovoltaic device in perovskite SrTiO3 quantum dot modified CuGaO2/Zn2SnO4 nanoarrays pn junction via surface plasma modification

A self-cleaning transparent pn junction in perovskite SrTiO3 QDs modified CuGaO2/Zn2SnO4 nanoarrays is prepared via the hydrothermal-solgel-surface plasma (SP) method. The CuGaO2/SrTiO3 QDs/Zn2SnO4 exhibits transmittance of ∼85%–90%, photovoltaic enhancement of ∼1.8 × 103-folds (photovoltaic conversion efficiency of ∼1.25%), stable output in 5 months, and good hydrophobicity (contact angle of ∼138.1°). The main reasons are mainly attributed to the SrTiO3 QDs and SP modification; besides the appropriate Fermi level and high quantum yield can improve the carrier kinetic equilibrium for balancing transparency-photovoltaic conversion efficiency, the SP modification can enhance the solar and carrier efficiency further, meanwhile achieving self-cleaning. Additionally, the CuGaO2 orderly nanoarrays can release stress, increase solar efficiency, and promote carrier transportation, in order to balance the structural stability, transparency, and photovoltaic efficiency.

High sensitivity flexible piezoelectric nanogenerator based on multi‐layer piezoelectric composite fiber for human motion energy harvesting

AbstractIn this study, a piezoelectric nanogenerator (PENG) based on multilayer composite fiber had good and stable piezoelectric output performance, which could realize biomechanical energy collection and human movement monitoring. The polyvinylidene fluoride‐hexafluoryl propylene (P(VDF‐HFP)) composite fiber doped with MXene was used as a promising piezoelectric functional layer (MPFP). By electrospinning, P(VDF‐HFP) composite fiber was constructed by alternating electrospinning with polyurethane (TPU) nanofibers layer by layer. The adoption of MXene as a functional filler promoted the transformation of P(VDF‐HFP) from α to piezoelectric β‐crystal, the piezoelectric β‐crystal content of P(VDF‐HFP) increased, and the dielectric properties and polarization levels were enhanced. At the same time, the multi‐layer structure design improved the piezoelectric sensitivity and mechanical properties of the composite fiber, and the composite fiber was more flexible and had longer tensile strain. With excellent dielectric and mechanical properties, 3MPFP/TPU/3MPFP/TPU multilayer composite fibers showed piezoelectric sensitivity of 10.88 V/kPa. Under the action of palm pressing, the PENG generated an open circuit voltage of 25 V, and the voltage signal of the device under different motion forms had specific characteristics such as peak value, frequency, and shape, which could be used to realize the analysis of human motion forms. This study provided an efficient, simple, and creative new idea for the application of flexible energy storage electronic devices, PENGs, and piezoelectric sensors.

Design of a PID Controller for Microbial Fuel Cells Using Improved Particle Swarm Optimization

The microbial fuel cell (MFC) is a renewable energy technology that utilizes the oxidative decomposition processes of anaerobic microorganisms to convert the chemical energy in organic matter, such as wastewater, sediments, or other biomass, into electrical power. This technology is not only applicable to wastewater treatment but can also be used for resource recovery from various organic wastes. The MFC usually requires an external controller that allows it to operate under controlled conditions to obtain a stable output voltage. Therefore, the application of a PID controller to the MFC is proposed in this paper. The design phase for this controller involves the identification of three parameters. Although the particle swarm optimization (PSO) algorithm is an advanced optimization algorithm based on swarm intelligence, it suffers from issues such as unreasonable population initialization and slow convergence speed. Therefore, this paper proposes an improved particle swarm algorithm based on the Golden Sine Strategy (GSCPSO). Using Circle chaotic mapping to make the distribution of the initial population more uniform, and then using the Golden Sine Strategy to improve the position update formula, not only improves the convergence speed of the population but also enhances convergence precision. The GSCPSO algorithm is applied to execute the described design process. The results of the simulation show that the designed control method exhibits smaller steady-state error, overshoot, and chattering compared with sliding-mode control (SMC), backstepping control, fuzzy SMC (FSMC), PSO-PID, and CPSO-PID.

Misalignment‐tolerant coupling cell of 2‐D modular WPT system for charging area simplified extension

Abstract2‐D modular wireless power transfer (WPT) system needs to have stable output when coil misalignment occurs. In order to improve the misalignment tolerance of the system coupling unit, this article proposes a magnetic coupling structure based on the LCC‐S compensation topology by combining a rectangular coil with two sets of mutually orthogonal solenoidal compensation coils. The rectangular coil is used to receive the vertical magnetic flux, and the two sets of compensating coils are used to receive the magnetic flux in the directions of X‐axis and Y‐axis on the horizontal plane, separately. The receiving side of the 2‐D wireless power transmission array cells cascaded half‐bridge rectifiers to connect each group of coils. This arrangement effectively compensates for the voltage drop of the rectangular coil caused by positional offset in any direction, so that the output voltage of the receiving side remains stable. The article firstly establishes the equivalent circuit model of the proposed design and deduces in detail the relationship equations between the output characteristics of the system and each influence factor. Secondly, the magnetic coupling structure is designed by finite element electromagnetic simulation software, and the total equivalent mutual inductance fluctuation of the proposed design is verified to be within 3.9% over the range of 2‐D transmission array cells. Finally, a 150 W experimental platform is built to verify the misaligment‐tolerant of the proposed design in the range of 2‐D transmission array cells. The experimental results show that the output voltage fluctuation of the proposed design within 4.27% at all directional offsets. Moreover, the stable output performance can be obtained in the case of vertical and rotational misalignment.