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Machine Learning for Perovskites' Reap-Rest-Recovery Cycle
摘要： Perovskite photovoltaics are efficient and inexpensive, yet their performance is dynamic. In this Perspective, we examine the effects of H2O, O2, bias, temperature, and illumination on device performance and recovery. First, we discuss pivotal experiments that evaluate perovskites’ ability to go through a reap-rest-recovery (3R) cycle, and how machine learning (ML) can help identify the optimum values for each operating parameter. Second, we analyze perovskite dynamics and degradation, emphasizing the research challenges surrounding this 3R cycle. We then outline experiments that could identify the impact of environmental factors on recovery for different perovskite compositions. Finally, we propose an ML paradigm for maximizing long-term performance and predicting device performance recovery, including a shared-knowledge repository. By reframing perovskites’ optoelectronic transiency within the context of recovery rather than degradation, we highlight a set of research opportunities and the artificial intelligence solutions needed for the commercial adoption of these promising solar cell materials.
关键词： machine learning,perovskite photovoltaics,environmental factors,reap-rest-recovery cycle,device performance
更新于2025-09-09 09:28:46
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Effect of CsI(Tl) micro-conical-frustums on the performance of the pixelated CsI(Tl) scintillation screen in X-ray imaging
摘要： The pixelated CsI(Tl) scintillation screen based on oxidized silicon micro-pore array template with CsI(Tl) micro-conical-frustums (CMCF) was proposed. The effect of the CMCF on the performance of the pixelated CsI(Tl) scintillation screen in X-ray imaging was studied by using Geant4 Monte Carlo simulation code. The variations of the light output (LO), modulation transfer function (MTF) and detective quantum efficiency (DQE) for the screen with the cone angle β of the CMCF in X-ray imaging were revealed. The results show that the LO of the pixelated scintillation screen with CMCF is superior to that of the screens with CsI(Tl) micro-cylinders (CMC) or with reversed CsI(Tl) micro-conical-frustums (RCMCF), but the spatial resolution of the X-ray imaging system by using the pixelated scintillation screen with RCMCF is better than that by using the screens with CMCF or with CMC. At low frequency, the cone angle β corresponding to DQEs from good to bad are 2.40°, 0.00° and -2.40°. But at high frequency, the cone angle β corresponding to DQEs from good to bad change to 2.40°, -2.40° and 0.00°. The reason is that, for a pixelated scintillation screen, the DQE for the screen not only depends on the efficiency of X-ray absorption, but also depends on the number of scintillation photons exiting the bottom the screen per interacting X-ray photon and its Poisson excess, and MTF. The simulated results of DQEs show that the comprehensive performance of the pixelated CsI(Tl) screen with CMCF in X-ray imaging is better than that of the screens with CMC or with CRMCF.
关键词： Shape of CsI(Tl) micro-conical-frustum,Performance in X-ray imaging,Oxidized silicon micro-pore array template,Pixelated CsI(Tl) scintillation screen
更新于2025-09-09 09:28:46
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A novel approach to prepare one-pot Fe/PPy nanocomposite and evaluation of its microwave, magnetic, and optical performance
摘要： The aim of this study was preparation of Fe/Fe2O3/Fe3O4 (Fe)/polypyrrole (PPy) nanocomposite using reductive method and investigation of its microwave absorbing properties using polymethylmethacrylate (PMMA) medium. Firstly, PPy was prepared by an oxidative polymerization method with Fe3+ as a doping agent. Next, the Fe/PPy nanocomposite was formed by insitu reduction of Fe2+ and remained Fe3+ with sodium borohydride solution under an inert nitrogen atmosphere. Finally, PPy and Fe/PPy nanostructures were separately suspended within the PMMA matrix to examine their microwave absorbing characteristics. The prepared PPy and Fe/PPy nanostructures were studied using the Fourier transform infrared (FT-IR), X-ray powder diffraction (XRD), and field emission scanning electron microscopy (FE-SEM). The diffuse reflection spectroscopy (DRS) analysis presented a 1.79 eV band gap for the Fe/PPy nanocomposite based on the Kubelka–Munk theory. The vibrating sample magnetometer (VSM) revealed that magnetic properties were reinforced in the Fe/PPy nanocomposite. According to the results obtained by vector network analyzer (VNA), the maximum reflection loss of Fe/PPy/PMMA nanocomposite was -76.02 dB at 8.96 GHz with a thickness of 3.2 mm, absorbing all of the x-band frequency more than 12.72 dB with a thickness of 2.8 mm. Interestingly, the Fe/PPy/PMMA nanocomposite demonstrated a bandwidth > 3.4 GHz more than 10 dB from 2.2 to 3.2 mm at the x-band frequency.
关键词： Optical performance,Magnetic properties,Fe/PPy/PMMA,Microwave absorption
更新于2025-09-09 09:28:46
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A Non-Contact Method to Assess Contractility on the Langendorff’s Model Based on CCD Imaging
摘要： Cardiac performance measurements of the isolated beating heart are essential for the evaluation of new pharmaceutical heart treatments. In the small animal, the means for these measurements usually are direct pressure changes in the left ventricle. Although volume equations are also used, they usually are indirect correlates of the pressure changes as opposed to true anatomical or dimensional measurements. In order to acquire detailed cardiac physiological data echocardiographic studies have been used in alive small animals. However, these are experimental techniques that demand a high level of expertise and expensive equipment. A new easy to use and fast charge-coupled device (CCD) analysis tool has been developed by our team for the isolated beating heart, based on morphometric changes of the projected heart‘s surface. It uses a commercially available fast CCD camera technology, home-made software and an image acquisition-analysis method to extract true dimensional changes. Its significance relies on acquisition and assessment of the cardiac anatomical parameters, using non-contact methods. A high definition CCD camera is used to acquire images from the isolated beating heart. Subsequently, image analysis software is used to eliminate noise and provide morphometric data (heart chamber dimensional changes) which are transformed to myocardial contractility indices and heart rate measurements. In conclusion, the new method presented in this paper is contactless, unbiased, cost effective, simple and can be used to evaluate the cardiac function in an ex vivo working model.
关键词： Ischemic heart,Cardiac performance,Evaluation,Dimensional changes,Langendorff
更新于2025-09-09 09:28:46
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A NOVEL DUAL-BAND METAMATERIAL ABSORBER AND ITS APPLICATION FOR MICROSTRIP ANTENNA
摘要： In this letter, a novel dual-band metamaterial absorber is presented and analyzed. The absorber is composed of four patches on the top of a thin grounded dielectric substrate which can absorb incident wave at two di?erent frequency bands e?ectively. Then the absorber is loaded on the dual-band microstrip antenna, whose working frequency bands are overlapped with that of the absorber, to reduce the in-band RCS (Radar Cross Section) of antenna. The prototype is simulated, manufactured and measured. Simulated results show that the absorption of the absorber is as high as 98.6% at 4.29 GHz and 99.8% at 6.49 GHz. As to the dual-band antenna loaded with the proposed absorber, its radiation performance is unchanged while the RCS has declined by 8.59 dB at 4.29 GHz and 9.9 dB at 6.49 GHz respectively. There is a good agreement between simulated and measured results, which veri?es that this absorber can be used for in-band RCS reduction of dual-band antenna so as to improve its in-band stealth performance.
关键词： RCS reduction,dual-band metamaterial absorber,microstrip antenna,stealth performance
更新于2025-09-09 09:28:46
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Performance enhancement of novel antipodal Vivaldi antenna with irregular spacing distance slots and modified-w-shaped metamaterial loading
摘要： This paper proposes a novel enhanced far-field performance antipodal Vivaldi antenna (AVA) by including slots into the flare with irregular spacing distance between each other and modified-w-shaped metamaterial (MWSM) unit cells etched on both sides of the substrate. The MWSM unit cell is simulated in finite element method commercially available software HFSS version16 and the effective parameters of the meta-atom are extracted by homogenization retrieval method based on transmission and reflection coefficients. Electric field and surface current distribution are displayed to qualitatively explain the occurrence of near-zero index permittivity, permeability and refraction index in 10 GHz. The unloaded and loaded modeled AVA simulation is provided, respectively, in detail and manufacturing procedure is conducted to verify the effectiveness of the suggested ideas. The return loss measurement indicated a good impedance match between the bare AVA and the loading composite MWSM unit cells despite little discrepancy compared to the simulation results. Numerical simulation reveals that the gain of the composite AVA increases from 7.5 to 11.52 dB after loading with the irregular spacing distance slots in the flare and MWSM unit cells etched substrate. The half-power beamwidth decreased from 72.4° to 41.4° for the E-plane and reduced to 33.38° from 63.4° for the H-plane, respectively. The measured results of the fabricated prototype are consistent with the simulated ones with slight discrepancy. This presented strategy will combine the advantages of the lens effect of metamaterial on the AVA and modified radiating flare, thus keeping the low profile of the whole structure all the time.
关键词： performance enhancement,modified-w-shaped metamaterial,Antipodal Vivaldi antenna,irregular spacing distance slots
更新于2025-09-09 09:28:46
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Optical performance analysis of an innovative linear focus secondary trough solar concentrating system
摘要： The parabolic trough solar concentrating system has been well developed and widely used in commercial solar thermal power plants. However, the conventional system has its drawbacks when connecting receiver tube parts and enhancing the concentration ratio. To overcome those inherent disadvantages, in this paper, an innovative concept of linear focus secondary trough concentrating system was proposed, which consists of a fixed parabolic trough concentrator, one or more heliostats, and a fixed tube receiver. The proposed system not only avoids the end loss and connection problem on the receiver during the tracking process but also opens up the possibility to increase the concentration ratio by enlarging aperture. The design scheme of the proposed system was elaborated in detail in this paper. Besides, the optical performance of the semi and the whole secondary solar trough concentrator was evaluated by using the ray tracing method. This innovative solar concentrating system shows a high application value as a solar energy experimental device.
关键词： secondary parabolic trough solar concentrator,optical performance,concentration ratio,linear focus,ray tracing method
更新于2025-09-09 09:28:46
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How does cobalt phosphate modify the structure of TiO2 nanotube array photoanodes for solar water splitting?
摘要： TiO2 nanotube arrays (TNA) have been modified by cobalt phosphate (CoPi) through potentiostatic electrodeposition method. Different samples have been prepared by changing the loaded CoPi through the deposition time from 10 to 960 minutes. Formed catalytic materials have been characterized by different methods. Although charge transfer resistance of the CoPi/TNA photoanodes have been decreased from 5.5 to 4.0 kΩ by increasing the deposition time from 5 to 60 minutes, the maximum photoresponse was obtained for 10 min CoPi deposition leading to 24% more photocurrent compare to bare TNA which proposed optimum value for cobalt phosphate decoration. Based on field emission scanning electron microscopy (FESEM) and X-ray photoelectron spectroscopy (XPS) results, by depositing the electrocatalyst, nanotube walls have been spread and holes have been covered by CoPi. Correlation between observed change in surface morphology and Raman spectra of the samples along with electrocatalytic tests revealed how decoration time can influence structural properties and photoelectrochemical performance of the final CoPi/TNA photoanodes in solar water splitting system.
关键词： CoPi,TiO2 photoanode,photoelectrochemical performance,solar water splitting
更新于2025-09-09 09:28:46
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Hourly PV production estimation by means of an exportable Multiple Linear Regression model
摘要： The current state of photovoltaic (PV) electricity integration is demanding several strategies that control the optimal performance of PV plants. Cleaning the PV plant, controlling PV production or the estimation of the electricity generation, are some relevant items related to the PV systems. In general, the soiling, the clouds and another climatological factors are involved in the final PV production. For knowing the performance of a PV system, it is necessity to model the PV plant behavior according to these relevant variables. In this work, a Multiple Linear Regression (MLR) model has been presented to determine the hourly PV production by using the Performance Ratio (PR) factor, according to different technologies: Cadmium Telluride (CdTe) and multicrystalline silicon (mc-Si). In this sense, data from several PV plants were studied in different Chile regions: San Pedro de Atacama and Antofagasta. With this study, it has been determined that the model can be extrapolated to different climatological emplacements, where generally, the root mean square error (RMSE) presents values lower than 16% in all cases, having the best result the CdTe technology.
关键词： Solar Energy,PV estimation,mc-Si,Multiple Linear Regression,CdTe,Performance Ratio
更新于2025-09-09 09:28:46
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Performance of 7-cells Dye Sensitized Solar Module in Z-type Series Interconnection
摘要： Dye sensitized solar cells (DSSC) is becoming attractive research topic as third generation solar cells technology since it provides clean energy and low cost fabrication. In this study, DSSC was fabricated into module scale, which is important for practical applications. The module was prepared in sandwich structure consisting of TiO2 working electrode and Pt counter electrode on conductive substrate with an area of 100 mm x 100 mm, which was distributed into seven active cells. TiO2 paste was deposited on FTO glass as working electrode with a size of 10 mm x 98 mm per unit cell by screen printing method. Each cell was connected in Z-type series that able to produce high voltage. ?? ? ?? measurement was applied in two methods consisting of laboratory testing using sun simulator under 500 W/m2 of illumination and outdoor testing using a digital multimeter under direct sunlight. The result shows that DSSC module has photoconversion efficiency of 1.08% and 1.17% for laboratory and outdoor testing, respectively. The module was also tested in three different times to monitor its stability performance.
关键词： Z-type series interconnection,Dye sensitized solar cells,stability performance,photoconversion efficiency,DSSC module
更新于2025-09-09 09:28:46