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The solar cell is key photovoltaic (PV) device that converts light energy into electricity, and its surface defects are the main reason for the decrease in the efficiency of PV systems. Conventional solar cell defect detection methods are often interfered with by cell substrates and are difficult to detect under high reflection, especially the overlap of substrates and defects. A solar cell defect detection method based on Fourier single-pixel imaging (FSI) is proposed to distinguish periodic substrates and defects in reconstruction by projecting illumination patterns with Fourier fringes, in which the removal of substrates reaches 100%. Meanwhile, for the high reflection present on the solar cell surface, the solar cell is directly treated as a single-pixel detector, which is free from interference from ambient light. The experiment adopts the solar cell itself as an imaging device under highly reflective conditions and removes the interference of the cell substrate by a 4-step phase-shifted FSI reconstruction algorithm to achieve the extraction of four types of defects, each of which is located in a different position of the solar cell substrate, at 10%, 50%, and 100% sampling rates. The method described here complements existing solar cell defect detection approaches and may be applied to enhance photovoltaic testers that rely on real-time correlation measurements, with promising applications in chip inspection and medical cell imaging. • Fourier single-pixel imaging(FSI) method for solar cells defect detection. • By using the solar cell as a photodetector(PD) to avoid the interference of high reflections. • Periodic substrate removal by 4-step phase-shift-based FSI reaches 100% in four different types of defects. [ABSTRACT FROM AUTHOR]

Nickel ferrite owns a lot of advantages as electrode materials for supercapacitor, such as high energy density and excellent theoretical capacity. Whereas, the electrochemical performances of NiFe 2 O 4 in terms of rate performance and cycle stability are not satisfactory due to the low conductivity. While carbon fiber is a kind of material with high conductivity. Hence, NiFe 2 O 4 @ slit modified hollow carbon fiber is obtained through the coaxial electrospinning method. The slits on hollow carbon fibers are beneficial to the contact of inner NiFe 2 O 4 nanoparticles with electrolyte. Results of electrochemical tests show that at a current density of 1 A/g, the specific capacitance of NiFe 2 O 4 @ slit modified hollow carbon fiber is calculated to be 225.4 F/g, higher than that of NiFe 2 O 4 nanoparticles of 134.8 F/g. Moreover, a better cycle and rate performances (100 % vs 80 %; 71.9 % vs 47.5 %) are achieved. This work displays that slit modified hollow carbon fiber can improve the electrochemical performance of NiFe 2 O 4 efficiently. [Display omitted] • Carbon fibers are introduced to enhance the rate and cycle performances of NiFe 2 O 4. • Slits are obtained utilizing Al 2 O 3 sacrificial hard templates. • Slits are beneficial to the contact of NiFe 2 O 4 and electrolyte. [ABSTRACT FROM AUTHOR]

• The partial S-doping NiFe 2 O 4 was obtained through a facile hydrothermal method. • The d-spacing of NiFe 2 O 4 was expended caused by partial S-doping. • The impact of partial S-doping to NiFe 2 O 4 is exposed by VASP analysis. • The optimal electrode exhibited the highest specific capacitance of 284 F/g. Nickel ferrite exhibits many advantages as electrode materials in the application of supercapacitor, such as high energy capacity and excellent cycle stability. Whereas, compared with identical-metal sulfides, the specific capacitance of NiFe 2 O 4 is still insufficient. Hence, to combine the superiorities of oxides and sulfides, partial sulfur doping NiFe 2 O 4 is obtained through hydrothermal synthesis method. Analyzed by Vienna Ab-initio Simulation Package (VASP) software and high-resolution transmission electron microscopy, the lattice parameters of NiFe 2 O 4 are confirmed to be expanded by introducing sulfur atoms, which is beneficial to electrochemical performances. At a current density of 1 A/g, the specific capacitance of partial sulfur doping NiFe 2 O 4 is calculated to be 284 F/g, higher than that of the original NiFe 2 O 4 of 182.2 F/g. Moreover, a maximum energy density of 21.14 Wh/kg is achieved at a power density of 375 W/kg. This work shows that partial sulfur doping could improve the electrochemical performance of NiFe 2 O 4. To sum up, this work provides an effective way to enhance the poor electrochemical performance of oxides, greatly encouraging the application of oxides in energy storage field. [Display omitted] [ABSTRACT FROM AUTHOR]

In the recent years, MXenes (2D transition metal carbides, carbon nitrides and nitrides) and its precursor MAX phases have been widely investigated in electrochemical research. In this research, we successfully prepared a core-shell structured compound——Ti 3 C 2 @Ti 2 SnC/CNFs (MXene@TSC/C) as an anode material for lithium ion battery via electrospinning method. Results showed that this type of compound has a specific capacity of 288.9 mAh·g−1 at the current density of 0.4 A g−1 after 300 cycles, accompany with a retention rate of capacity of 105.4% in the rate performance test. These performances were benefit from the core-shell structured CNFs and Ti 3 C 2 MXenes. This work supported a novel way to improve the electrochemical property of MXene and MAX phases, which was expected to further explored. [ABSTRACT FROM AUTHOR]

A sol-gel method was employed for the synthesis of new High-entropy boride (HEB) powders, (Hf 0.2 Nb 0.2 Cr 0.2 Ta 0.2 Mo 0.2)B 2 , with nanoscale. The as-synthesized powders were obtained at a relatively low temperature of 1650 °C, and had small average particle size of 62.09 nm. X-ray diffraction confirmed that the (Hf 0.2 Nb 0.2 Cr 0.2 Ta 0.2 Mo 0.2)B 2 powders were hexagonal single-phase without any oxide impurities. In particular, electrochemical performance of the (Hf 0.2 Nb 0.2 Cr 0.2 Ta 0.2 Mo 0.2)B 2 powders with multiphase and high-entropy single phase were investigated using a three-electrode system. The improved electrochemical performance of the HEB powders is realized, with 27% higher in specific capacitance compared to the powders with multiphase. The HEB powders electrode exhibits a high capacitance retention of 97.03% after 5000 cycles. [ABSTRACT FROM AUTHOR]

Single-pixel imaging technology is popular with invisible wavelengths and low light environments. However, the time-consuming steps hindered the development of single-pixel imaging technology. To improve imaging efficiency, a high-efficiency one-step single-pixel imaging method based on the discrete Hartley transform is proposed. The proposed method does not require a large number of fringe patterns and only requires a real-number calculation. The number of fringe patterns required for the proposed method is only half of that required for the four-step phase-shift Fourier method at the same sampling rate. Although a one-step method, it also uses the idea of differential measurements and adds upsampling processing strategies, which simultaneously improve the signal-to-noise ratio of the recovered image. The simulation shows that the peak signal-to-noise ratio and structural similarity index of the recovered target scene exceed 20 dB and 80%, respectively, when the sampling rate is 30%. Only 20 164 patterns are needed to reconstruct a (256 × 256)-pixel image. After defocusing the gray stripe pattern into a binary pattern, it only takes milliseconds to project these patterns into the target. It can be seen that the experimental results of the proposed method are significantly better than those of the two-step phase-shift method under dramatical noise interference. With the rapid development of advanced equipment, this method will represent significant progress in the real-time reconstruction of single-pixel imaging. [ABSTRACT FROM AUTHOR]

Degradation of imaging quality due to noise sources is one of the most essential problems for single-pixel imaging (SPI). This paper presents a method that separates, identifies, and reduces noise from the 1-D signal of the SPI before reconstructing the image. The proposed method raises the quality of the picture significantly, for example, PSNR from 9.14 dB to 30.29 dB and SSIM from 5.55% to 91.99% when SNR is -15 dB in simulation. This method has a strong robustness to a variety of noise types compared to the traditional filtering methods. The experimental results verified the proposed method's feasibility and improved the image's quality from a chaotic state to an acceptable stage. The method proposed in this paper can separate, identify and remove the noise component from the sources in SPI, which may open a branch by removing noise from sources rather than post-processing. • A method to separate, identify, and reduce noise in single-pixel imaging. • Robust to a variety of noise types compared to the traditional filtering methods. • Enhance the imaging quality and expand application of SPI in noisy conditions. [ABSTRACT FROM AUTHOR]

• A deep-hole imaging method by using MMF is proposed. • Wavelet polarization fusion is applied to deep-hole image reconstruction. • The method achieves reconstruction with a maximum spatial resolution of 3.18 lp/mm. Conventional deep hole imaging uses a camera array as the imaging device, with the lens entering the deep hole to obtain spatial light information for reconstruction. The lens often determines the size of the imaging aperture and it is hard to adapt to different sizes of deep holes, especially elongated ones. This paper proposes a method of the multimode fiber(MMF) deep hole imaging based on wavelet polarization fusion, completed with fiber single-pixel imaging(FSPI) and fiber polarization single-pixel imaging(FPSPI). The system completes three different sizes of deep holes imaging, respectively 8mm × 8mm, 5mm × 5mm, 3mm × 3mm. In addition, the information entropy of each 32 pixels image increases 12.26 % and 11.78 % relative to the original image, which is higher than that of 64 pixels images of the same class, with the spatial resolution of 3.18 lp/mm. The proposed deep hole imaging method based MMF is expected to be applied in pipeline sidewall imaging and deep hole 3D imaging. [ABSTRACT FROM AUTHOR]

The security of liveness detection in face recognition is a crucial issue, but many attacks can spoof current face feature techniques. To enhance the security of liveness detection, a method is proposed to extract human physiological components from the object and classify the properties. The proposed method, different from traditional camera-based methods that require specific movement of the human face, separates the heart rate (HR) components from the computational ghost imaging (CGI) signal and achieves liveness detection by capturing only one image rather than image sequences. The correct rate reaches 96.0% against picture attacks and mask attacks. The average error is only 3.57% compared to commercial contact HR measuring devices. Meanwhile, this method is found resolution-independent and can work in low-resolution conditions, which is experimentally verified at a resolution of 32 × 32 pixels. This method can enhance the security of liveness detection and provide a fresh framework for physiological measurements. [ABSTRACT FROM AUTHOR]

The new inorganic material known as "high-entropy oxides" (HEOs) has a single-phase structure and is made up of several different main metal elements. It has many useful properties, including a high specific capacity, excellent cycling performance, high structural stability, and super-electronic conductivity. For lithium-ion batteries, it is viewed as a promising electrode material (LIBs). It is significant to develop high entropy oxides with different components and study their properties. Herein, Mg, Ni and Li are added to the quaternary medium entropy (CrFeMnCo)3O4. Four new spinel high entropy oxides were synthesized by glycine-nitrate SCS method at 750 °C and their material characterization and electrochemical properties were investigated respectively. The experimental results show that the four obtained samples have uniform particle size distribution. As for the electrochemical test, the capacities of the (CrFeMnCoMg)3O4 and (CrFeMnCoNi)3O4 do not decrease significantly after 800 cycles at 2000 mA·g−1. They have better cycle stability than the (CrFeMnCoMgLi)3O4 and (CrFeMnCoNiLi)3O4. As the anode of LIBs, all HEOs show excellent cycle stability and rate capability. This work provides a new strategy for designing high-entropy energy storage materials. [ABSTRACT FROM AUTHOR]

In this study, Zn 8 B 3 H 3 O 14 nanosheets were synthesized through a one-step coprecipitation process and employed as both a boron source and substrate templates for the fabrication of boron nitride nanosheets (BNNSs), which were synthesized efficiently at low temperatures by the borate nitration method using ammonia as the nitrogen source. The thickness of the synthesized BNNSs ranged from 3 to 10 nm with a flake dimension of about 2.56 μm. The prepared BNNSs using this method realized 98.8% boron source utilization and single batch yields up to gram level. In addition, BNNSs/SiO 2 microwave-transparent composites were prepared to investigate the potential for large-scale applications of the BNNSs produced by using this method. The composites demonstrated a remarkable increase in bending strength and fracture toughness, reaching 122.02 MPa and 2.31 MPa·m1/2, respectively, with the addition of only 0.5 wt% BNNSs. Compared with SiO 2 without BNNSs, the fracture toughness of the composites is increased by 106%. A novel crack plugging strong toughening mechanism of BNNSs is proposed. Simultaneously, the composites exhibit exceptional microwave-transparent properties, with dielectric constants below 4 in the real part and below 0.03 in the imaginary part. Therefore, this study has successfully achieved the low-temperature and efficient synthesis of micron-scale BNNSs, laying the groundwork for their large-scale application. [Display omitted] • Zn 8 B 3 H 3 O 14 nanosheets were used as substrate templates for the synthesis of BNNSs. • BNNSs were synthesized with high efficiency at low temperatures (900 °C). • The single batch yield of BNNSs reached up to the gram level. • The BNNSs/SiO 2 wave-transparent composites with ultrahigh toughness were obtained. • A novel mechanism for strengthening and toughening (BNNSs plugging) is proposed. [ABSTRACT FROM AUTHOR]

Transitional metal nitrides (TMNs) are regarded as comparatively promising electrode materials for supercapacitor due to the high electronic conductivity, good corrosion resistance and special electron structure. Herein, in this work a heterostructure Co 2 N-Ni 3 N nanosheets-nanowires arrays grown on Ni foam (NF) are designed and synthesized by a simple hydrothermal reaction and nitriding treatment. The prepared Co 2 N-Ni 3 N/NF nanoarrays has a high electrical conductivity, abundant surface active sites, charge transfer channels and the synergy effect between each component, which makes it exhibit outstanding electrochemical performance. Electrochemical test results revealed that the areal capacitance of Co 2 N-Ni 3 N/NF was 2.17 F cm−2 at 1 mA cm−2 using a three-electrode system in 1 M KOH. Meanwhile, when the current density increases to 20 mA cm−2, it can still retain 62.21% of the original capacitance, suggesting a good rate capability. In addition, in two-electrode test with Co 2 N-Ni 3 N/NF as the positive electrode and activated carbon as the negative electrode, a maximum energy density of 145.65 μWh cm−2 is shown when the power density is 0.75 mW cm−2. And it has 85.90% capacitance retention after 5000 cycles. [Display omitted] • Unique Co 2 N-Ni 3 N nanoarray heterostructure was successfully synthesized. • Co 2 N-Ni 3 N/NF achieves an areal capacitance 2.17 F cm-2 at current density of 1 mA cm-2. • The Co 2 N-Ni 3 N/NF // AC exhibits good electrochemical performance in two-electrode tests. [ABSTRACT FROM AUTHOR]

As the precursor of MXenes (2D transition metal carbides, carbon nitrides and nitrides), MAX phase materials have attracted ever-increasing attention in electrochemical applications. In this work, we have successfully hybridized a MAX phase, Ti 2 SnC, with various ratios of carbon nanofibers (CNFs) via electrospinning. The results show that the Ti 2 SnC/CNFs compounds possess a stable lithium ion storage ability as an anode material, reaching a stable specific capacity of up to 367.5 mAh·g−1 after 500 charge/discharge cycles at the current density of 1.0 A g−1, which are drastically better than some other MAX phase materials such as Ti 3 SiC 2 and Nb 2 SnC. This strategy provides a new pathway for the improvement of the electrochemical stability of MAX phase, which has a wide application prospect. • Ti 2 SnC/CNFs was successfully prepared by an electrospinning method. • CNFs retard the volume expansion of Ti 2 SnC during the charge/discharge process. • Ti 2 SnC/CNFs performed stable lithium ion capacitance (367.5 mAh·g−1 at 1.0 A g−1). [ABSTRACT FROM AUTHOR]

MAX phase materials, the precursors of MXenes (2D transition metal carbides, carbon nitrides, and nitrides), have become increasingly popular in electrochemical applications. In this study, we have successfully prepared Ti 2 SnC with high lithium capacity via the in-situ formation of SnO 2. Results show that there are TiC nanowhiskers and SnO 2 inside the Ti 2 SnC MAX calcined at 800 ℃, and the initial specific capacity could reach 377 and 371 mAh·g−1 at high current densities of 400 mA·g−1 and 1.0 A·g−1, respectively. These values are higher than those of most MAX phase materials reported in previous studies, such as Ti 3 SiC 2 and Nb 2 SnC, but the stability and rate performance are inferior, which is a direction for the future. This paper provides a new pathway for the application of MAX phases in electrochemistry, which has more in-depth application prospects. ● Ti 2 SnC with in-situ formation of SnO 2 was successfully prepared by a calcination method. ● The Ti 2 SnC layered structure slows down the volume expansion of in-situ prepared SnO 2. ● This anode material performed a better specific capacitance, arriving at 377 mAh/g at the current density of 1.0 A/g. [ABSTRACT FROM AUTHOR]

• We propose a single-pixel superposition compound eye (SPSCE) that deploys a photodetector which has no spatial resolution and imitates the rhabdom in natural organisms to deliver super-resolution imaging signal, which creates a new branch for the compound eyes. • SPSCE has the capacity to improve the imaging resolution two orders of magnitude than the number of ommatidia without subsequent image processing. • SPSCE has the unique super-robust character to capture whole acceptable images even if almost one-third of ommatidia are not working, and obtain images beyond the actual visual field of the target without observing directly. Deep understanding of biological superposition compound eye provides great opportunities in developing imaging systems with features beyond current planar detector array based imaging devices. However, artificial superposition compound eyes are designed on the basis of a planar detector array and that subsequently leads to the complex optical design and degradation of imaging quality inevitably. We propose a single-pixel superposition compound eye (SPSCE), whose imaging resolution has been improved two orders of magnitude than the number of ommatidia without subsequent image processing. SPSCE has the ability to capture the whole acceptable image of objects even if almost one-third of ommatidia at random positions are not working, which makes it possible to operate reliably even in the damaged state. SPSCE has the capacity to image beyond the actual visual field of the target without observing directly. With only one lateral sub-eye working and deviating from the visual field of the target by 20. 41 ∘ , SPSCE obtains the complete and recognizable image of the target independently through the diffuse reflection optical information of the surrounding environment. The unique super-robust character of SPSCE with its super-resolution property contributes to developing anti-interference artificial compound eyes, unlocking the limit toward development of much higher imaging resolution artificial superposition compound eyes. [ABSTRACT FROM AUTHOR]