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In recent years, deep learning‐based fault diagnosis technology for high‐voltage circuit breakers (HVCB) has advanced significantly, but the working environment of HVCBs is complex, resulting in unsatisfactory fault diagnosis results of HVCBs in noisy environment and existing deep learning methods are difficult to solve this problem. This paper proposes a multi‐channel convolutional neural network combines dense residual structure and attention mechanism to achieve high‐precision and high‐robust diagnosis of HVCBs in noisy backgrounds. A dense residual network is introduced into the convolutional neural network to prevent feature loss during network propagation to preserve the difference information between the network layers as much as possible, Simultaneously, a channel attention mechanism is introduced to adaptively adjust the weights of different convolution channels. The model can extract multi‐scale features from the original signal and fully exploit the intrinsic relationship between the vibration signal and the HVCB's operating state. The experimental results show that the diagnostic method can still meet the requirements of fault diagnosis in the presence of noise, with an average diagnostic accuracy rate of 85.92% when the signal‐to‐noise ratio is −4. The model outperforms the traditional single‐channel model in terms of diagnostic accuracy and stability. [ABSTRACT FROM AUTHOR]

The Laurentian Great Lakes are one of the most prominent hotspots for the study of climate change induced lake warming. Warming trends in large, deep lakes, which are often inferred by the observations of lake surface temperature (LST) in most studies, are strongly linked to the total lake heat content. In this study, we use a 3D hydrodynamic model to examine the nonlinear processes of water mixing and ice formation that cause changes in lake heat content and further variation of LST. With a focus on mechanism study, a series of process‐oriented experiments is carried out to understand the interactions among these processes and their relative importance to the lake heat budget. Using this hydrodynamic model, we estimate the lake heat content by integrating over the entire 3D volume. Our analysis reveals that (1) Heat content trends do not necessarily follow (can even be opposed to) trends in LST. Hence, using LST as a warming indicator can be problematic; (2) vertical mixing in water column may play a more important role in regulating lake warming than traditionally expected. Changes in the water mixing pattern can have a prolonged effect on the thermal structure; (3) Ice albedo feedback, even in cold winters, has little impact on lake thermal structure, and its influence on lake warming may have been overestimated. Our results indicate that climate change will not only affect the air‐lake energy exchange but can also alter lake internal dynamics, therefore, the lake's response to a changing climate may vary with time. [ABSTRACT FROM AUTHOR]

A series of novel SrLu2O4: x Ho3+, y Yb3+ phosphors ( x=0.005-0.05, y=0.1-0.6) were synthesized by a simple solid-state reaction method. The phase purity, morphology, and upconversion luminescence were measured by X-ray diffraction ( XRD), scanning electron microscopy ( SEM), and photoluminescence ( PL) spectroscopy. The doping concentrations and sintering temperature were optimized to be x=0.01, y=0.5 and T=1400°C to obtain the strongest emission intensity. Under 980 nm laser diode excitation, the SrLu2O4:Ho3+, Yb3+ phosphors exhibit intense green upconversion ( UC) emission band centered at 541 nm (5F4,5S2→5I8) and weak red emission peaked at 673 nm (5F5→5I8). Under different pump-power excitation, the UC luminescence can be finely tuned from yellow-green to green light region to some extent. Based on energy level diagram, the energy-transfer mechanisms are investigated in detail according to the analysis of pump-power dependence and luminescence decay curves. The energy-transfer mechanisms for green and red UC emissions can be determined to be two-photon absorption processes. Compared with commercial NaYF4:Er3+, Yb3+ and common Y2O3:Ho3+, Yb3+ phosphors, the SrLu1.49Ho0.01Yb0.5O4 sample shows good color monochromaticity and relatively high UC luminescence intensity. The results imply that SrLu2O4:Ho3+, Yb3+ can be a good candidate for green UC material in display fields. [ABSTRACT FROM AUTHOR]

In this study, Cr3+‐doped and Mn4+‐Cr3+ co‐doped double perovskite fluoride phosphors K2LiGaF6 are prepared using a simple hydrothermal method. High‐efficiency near‐infrared (NIR) emission near 762 nm is obtained under blue‐light excitation, and the co‐doping effect of Mn4+ on the NIR luminescence properties of Cr3+ is studied. Compared with the Cr3+ single‐doped phosphor, Mn4+, and Cr3+ co‐doped K2LiGaF6 exhibit a sharp increase of 129% in NIR emission, an enhancement in the internal quantum efficiency from 82.5% to 90.0%, and an enhancement in the thermal stability at 425 K from 85.0% to 90.7%. The encapsulated NIR phosphor‐converted light‐emitting diode device at 300 mA exhibits a photoelectric conversion efficiency of 15.3%. These values exceed most previously reported results. This study provides a new approach for enhancing the luminescence properties of Cr3+‐doped fluoride NIR phosphors. [ABSTRACT FROM AUTHOR]

Cr3+‐activated near‐infrared (NIR) phosphors have gained extensive attention for use in NIR phosphor‐converted light‐emitting diodes (pc‐LEDs), which are required for smart NIR spectroscopy techniques. Nevertheless, obtaining broadband NIR‐emitting phosphors with outstanding thermal stabilities and photoluminescence (PL) efficiencies remains a significant challenge. Herein, considering NaSr2XGe5O14 (X = Al, Ga, Sc, and In) as hosts, which possess a large band gap and multiple sites for the substitution of Cr3+ ions. NaSr2XGe5O14:Cr3+ phosphors are successfully prepared using a solid‐state reaction technology. Upon blue light excitation, the phosphors cover a broad NIR emission band in 650–1100 nm region. Notably, an abnormal blueshift and PL enhancement are observed following the substitution of Al/Ga with Sc/In. In particular, the PL internal quantum efficiency is improved from 34.5% (NaSr2GaGe5O14: Cr3+) to 87.5% (NaSr2ScGe5O14: Cr3+). Moreover, the manufactured NIR pc‐LED exhibited an exceptional photoelectric efficiency of 17.7% with an NIR output power of 10.2 mW at 20 mA, and its potential application in nondestructive detection is demonstrated. [ABSTRACT FROM AUTHOR]

Deep learning (DL) has attracted significant attention in partial discharge (PD) pattern recognition of gas‐insulated switchgear (GIS). However, the existing DL method extracts numerical information and ignores spatial correlation information. In addition, once the sample size is reduced, model performance is severely degraded. To address these issues, a novel capsule deep graph convolutional network (CDGCN) is employed for GIS PD pattern recognition. First, the GIS PD data is transformed to graph data. Then, the CDGCN is established for GIS PD pattern recognition. The introduction of a ChannelSortPooling layer enriches the graph representation information and filters out the feature values with higher information content. In addition, the multi‐view graph representation is converted to a capsule form, and a capsule network with stronger feature extraction capability is introduced to improve the accuracy of the final graph representation. The results reveal that the proposed CDGCN can effectively diagnose the GIS PD and is more accurate than the traditional DL method. The proposed CDGCN can handle small samples pattern recognition problems and provides a reliable reference for GIS PD pattern recognition. [ABSTRACT FROM AUTHOR]

Current white light emitting diodes (WLEDs) have poor thermal stability and lack red‐light, which restrict their applications in high‐power and high‐color‐rendering‐index solid‐state lighting. YAG glass‐ceramics provide an efficient way to resolve these problems. Herein, novel YAG‐embedded calcium bismuth borate glass‐ceramics (YAG‐GCs) with Eu3+ doping were prepared using a rapid melt quenching technique. The precursor glass exhibits superior YAG refractive index matching and high transmittance. Differential scanning calorimeter simulations verify YAG particles react with the precursor glass. The degree of YAG erosion is slight but monotonously increases with the co‐sintering temperature from 640 to 700°C. The erosion products probably contain YAB (Al3Y(BO3)4), Al3Eu(BO3)4, Bi24B2O39, and Ca12Al14O33 phases, and the Bi ion valence state is maintained during the reaction process. The energy transfer from Ce3+ to Eu3+ is suppressed. The YAG‐GC PL intensities monotonously increase as the co‐sintering temperature decrease from 640 to 700°C and the YAG content increase from 2.5 to 7 wt.%. The optical parameters of a WLEDs packed by YAG‐GCs and blue chips are a luminous efficiency of 105.3 lm/W, correlated color temperature of 3940 K and color rendering index of 70.1. The as‐prepared YAG‐GCs are promising candidates for high‐power, warm WLEDs due to their superior thermal stability, high quantum efficiency, and low cost. [ABSTRACT FROM AUTHOR]

The low permeability of discharged muck must last for at least tens of minutes to avoid water spewing during earth pressure balance (EPB) shield tunneling; however, foam, which is usually added to soil to reduce its permeability, has its own unique time‐varying characteristics. Thus, it is important to predict the stable time of permeability of foam‐conditioned soil for EPB shield tunneling. Based on theories of the effective permeation channel of pure foam and fluid mechanics, a constant is proposed to predict the duration of the initial period during which the coefficient of permeability of the conditioned soil remains stable. A series of large‐scale permeation tests were carried out to determine the duration of the initial stable period for various foam‐conditioned soils, and it was verified that the predicted results were in good agreement with the measured results. Furthermore, based on the constant, practical concepts, including duration reference curves, optimum fineness, optimum porosity and critical particle size, are proposed for the spewing control of EPB shield tunneling. [ABSTRACT FROM AUTHOR]

It has been one of the hot issues to prepare the red‐emitting Mn4+‐doped fluoride phosphors with highly efficient and waterproofness for warm white‐light‐emitting diodes (WLEDs) by the green and environmentally friendly method. Herein, we design a novel green molten salt route to synthesize K2SiF6:Mn4+ red powder using molten NH4HF2 salt instead of HF liquor as the reaction medium. The results show that KMnO4 and MnF2 could produce Mn4+ in NH4HF2 molten salt through a reduction reaction, and the resulting Mn4+‐doped K2SiF6 exhibited a bright red emission peaked at 632 nm under blue light excitation. The luminescence intensity of the as‐obtained product after immersing into water for 24 hours maintain nearly 100% of that before soaking and emission peak shape remains unchanged. The thermal stability of the sample was evaluated by temperature‐dependent luminescence spectral intensity during heating and cooling. Furthermore, a warm white‐light‐emitting diodes (WLEDs) with an excellent color rendering index (Ra = 87.1), lower correlated color temperature (CCT = 3536K), and high luminous efficacy (116.99 lm·W−1) was fabricated based on blue chip and K2SiF6:Mn4+ and commercial yellow phosphor (Y3Al5O12:Ce3+). [ABSTRACT FROM AUTHOR]

Fluoride phosphors as red components for warm white LEDs have attracted a tremendous amount of research attention. But these phosphors are extremely sensitive to moisture, which seriously limits their practical industrial applications. To tackle this problem, unlike all the straightforward preventive strategies, a reverse strategy "Good comes from bad" was successfully developed to treat the degraded K2SiF6 : Mn4+ (D‐KSFM) phosphor in the present study, which not only completely restores the luminescence properties, but also significantly enhances the moisture resistance at the same time. After treatment with an oxalic acid solution as restoration modifier, the emission intensity of the D‐KSFM phosphor can be restored to 103.7% of the original K2SiF6 : Mn4+ red phosphor (O‐KSFM), and the moisture resistance is remarkably improved. The restored K2SiF6 : Mn4+ (R‐KSFM) maintains approximately 62.3% of its initial relative emission intensity after immersing in deionized water for 300 min, while the reference commercial K2SiF6 : Mn4+ with a protective coating (C‐KSFM) is only 33.2%. As a proof of general applicability, this strategy was also conducted to K2TiF6 : Mn4+ phosphor, which is less moisture‐stable than K2SiF6 : Mn4+. The luminescence intensity of the degraded K2TiF6 : Mn4+ (D‐KTFM) phosphor can be restored to 162.6% of original level of the K2TiF6 : Mn4+ synthesized through a cation exchange approach without any treatment (O‐KTFM). The emission intensity of the restored K2TiF6 : Mn4+ (R‐KTFM) phosphor retains 62.8% of its initial emission intensity after soaking in deionized water for 300 min. Finally, the R‐KSFM phosphors were packaged into white light‐emitting diodes with blue InGaN chips and Y3Al5O12 : Ce3+ yellow phosphors. The WLEDs display excellent color rendition with higher color rendering index, lower color temperature (WLED‐II: Ra=83.6, R9=57.3, 3743 K, ηl=199.68 lm/W; WLED‐III: Ra=90.4, R9=94.2, 2892 K, ηl=183.3 1 m/W). The above results show that the reverse strategy can be applied in those phosphor materials with poor moisture resistance to restore luminescence properties and improve moisture resistance without excessively care about the deterioration during the production, storage and transportation. [ABSTRACT FROM AUTHOR]

Y1.94MAl4SiO12:0.06Ce3+ (M = Ba, Sr, Ca, Mg) phosphors were successfully prepared through a classic solid‐state reaction method. The crystal structures, photoluminescence spectra, quantum yields, and thermal stabilities of the phosphors were investigated in detail. The results indicate that all Y1.94MAl4SiO12:0.06Ce3+ phosphors maintain the crystal structure of garnets. The emission peaks of Y1.94MAl4SiO12:0.06Ce3+ (M = Ba, Sr, Ca, Mg) phosphors are located at 537, 538, 554, and 565 nm, respectively. A red‐shift trend of emission peak is observed with decreasing M radius, which can be ascribed to the increase in the crystal‐field splitting in the Ce3+ 5d level owing to the co‐doping of M2+−Si4+. Under 460 nm excitation, the luminescence quantum yields and thermal stabilities of the Y1.94MAl4SiO12:0.06Ce3+ phosphors decreased with the decrease of M radius. The IQE of the Y1.94BaAl4SiO12:0.06Ce3+ phosphor is 92.89%, and the resistance to thermal quenching is improved to be 93.32% at 150°C. In addition, the color shifts of Y1.94MAl4SiO12: 0.06Ce3+ phosphors with increasing temperature are all tiny, which also demonstrates good resistance to thermal quenching of luminescence. The linear shrinkage of Y1.94MAl4SiO12:0.06Ce3+ phosphors is significantly improved compared with that of YAG: Ce3+, which is expected to generate Y1.94MAl4SiO12:0.06Ce3+ transparent/translucent ceramics and fabricate high‐powder w‐LEDs for high‐quality solid‐state lighting in the future. [ABSTRACT FROM AUTHOR]