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Recently, state-of-the-art crowd counting methods have focused more on predicting a density map and then obtaining the final aggregated count. In 2018, a typical density map-based network for congested scene recognition called CSRNet was proposed, and it achieved better crowd counting performance than previous methods with a simple architecture. It utilizes the first 10 layers from VGG-16 as the front end and deploys dilated convolutional layers as the back-end to generate high-quality density maps. CSRNet has been demonstrated on four datasets (ShanghaiTech dataset, the UCF_CC_50 dataset, the World Expo'10 dataset, and the UCSD dataset) and delivered great performance. To obtain better performance, in this paper, we propose a small network as a new component that generates a counting residual estimation, and we combine our component with CSRNet. We demonstrate this combined network on three datasets (ShanghaiTech dataset, the UCF_CC_50 dataset, and the World Expo'10 dataset) and compare the results with those of CSRNet. The results show that our method has significantly improved the results of CSRNet. Through a series of experiments, such as ablation experiments and control experiments, we demonstrate the effectiveness of our method. In the future, we will apply our method to other networks to achieve better results. [ABSTRACT FROM AUTHOR]

Recently, visual attention mechanisms have been employed in CNN-based crowd counting methods to overcome the interference of background noise and have achieved good performance. However, the existing methods usually focus on designing complex attention structures and extracting pixel-level contextual information, while ignoring global contextual information extraction at different scales. In this paper, to overcome scale variation and complex background noise, we propose a novel scale-aware and global contextual network (SGCNet) that employs multi-scale attention mechanisms to selectively strengthen features with different network scales. The key component of SGCNet is a multi-scale global contextual block that consists of multi-scale feature selection and global contextual information extraction, where global contextual information is adopted as guidance to weight features at different scales. Compared with the previous methods that ignore scale information injected into the attention mechanism, SGCNet achieves better counting performance via multi-scale contextual information extraction. Extensive experiments on four crowd counting datasets (ShanghaiTech, UCF_CC_50, UCF-QNRF, UCSD) demonstrate the effectiveness and superiority of the proposed method in highly congested noisy crowd scenes. [ABSTRACT FROM AUTHOR]

The present work reports our efforts to enhance the performance and uniformity for the long tapes of metal–organic deposition YBa2Cu3O7−x (MOD-YBCO) layer on ion-beam-assisted deposition MgO (IBAD-MgO) template. Reflection High-energy electron diffraction (RHEED) is employed to realize the in-situ growth monitor of IBAD-MgO, as well as the correlation between the quantitative RHEED peaks and in-plane texture of Epi-MgO identified by XRD, which is an effective guide to improve the uniformity and performance of long YBCO tapes. In addition, the surface of the LMO layer during the magnetron sputtering process is improved via controlling the O2 flux, and then the critical-current density (Jc) of YBCO films has been improved. By optimizing the texture of the MgO layer and precisely controlling the LMO layer growth conditions, the performance and uniformity of YBCO-coated conductors grown by metal–organic deposition (MOD) have been greatly enhanced. The superconducting current-carrying capacities of 12-mm-wide tapes have upgraded steadily from 400–500 A to 500–550 A in past 3 years. The laminated CC tapes with current-carrying capacities of 150–170 A per 4-mm width show good uniformity and high quality along 500-m length, implying being promising for various commercial power applications. [ABSTRACT FROM AUTHOR]

The joint-free superconducting annular disks and their stacks, obtained by cutting REBCO (REBa2Cu3O7–δ, RE: rare earth) wide tapes, are proposed as promising passive magnetic shields in this paper. The shielding properties of the disks have been numerically studied using the finite element method. The shielding factor (SF), defined as the ratio between the applied field and the central field, had a frequency-independent value when the magnetic field is much lower than the full penetration field. It appears to have a linear relationship with the ratio of the outer and inner diameter of the disk. Furthermore, various architectures with stacked disks were studied. High shielding factors (SF > 104) under enhanced full penetration fields of above 100 mT can be obtained in the configuration of more disks and proper disk distance (the distance between the disks on each layer). Two stacked disks were designed. In a 1-mT, 1-Hz applied field, the SF of the 4-mm inner diameter discrete stack is 1.21 × 107 (140 dB), and the SF of the 20-mm inner diameter split stack reaches 3.44 × 104 (90 dB). It implies that the stacked REBCO disks have great potential for the application of high-efficiency magnetic shielding. [ABSTRACT FROM AUTHOR]

The width of REBCO (REBa2Cu3O7-x, RE: rare earths)-coated conductor is an important factor associated with AC (alternating current) loss of the tape. In the same electromagnetic environment, coils winding with narrow REBCO tapes generate less AC loss than the wide one. For a single coil, the critical current density of outer turns is higher than that of inner turns, due to the inhomogeneous distribution of magnetic field. This paper presents a multi-width technique which is applicable for single REBCO coil by partly slitting single tape in place, which can effectively reduce AC loss, while maintaining current-carrying capacity in high field. The AC loss of coils with slitting in different turns is calculated by the software of finite element modeling (FEM). The results indicate that the appropriate slitting in radially outer turns of coil appears effective to reduce AC loss, especially in the case of the coils running with high current. [ABSTRACT FROM AUTHOR]

Blended cathode materials generally suffer from capacity loss impacting on their power performance in lithium-ion batteries. This work reports a systematic study of LiNi1/3Co1/3Mn1/3O2–LiMn2O4 blended materials incorporated with characterizations of particles, calculations of charging-discharging characters, and analysis of cyclic voltammetry. A synergetic effect, a capacity increasing at high discharging rate referring to the linear superposition of blending components, is observed in a wide blending ratio for blended materials. The model analysis of charging-discharging characters shows that LiMn2O4 releases more reversible capacity in the blended materials than when it is alone at the same electrochemical condition. An equivalent circuit model is proposed to interpret the electrochemical behaviors showed in electrochemical impedance spectroscopy. The mechanism of particle synergetic effect is attributed to the compensating property of blending components, which improves the inter-particles diffusibility of Li+, therefore reduces the particle impedance of blended materials promoting rate performance. Over the blending range, the scheme LiNi1/3Co1/3Mn1/3O2/LiMn2O4–Blend (50:50 in mass ratio) shows the best performance and highest capacity increasing. [ABSTRACT FROM AUTHOR]

Polyethyleneimine (PEI) with an amount of -NH2 groups used in precursor solution could effectively reduce Cu2+ volatilization during the pyrolysis process. Thermogravimetric analysis shows that the temperature window of low-temperature pyrolysis for precursor solution with PEI (PEI-YBCO) is widened significantly. The slower pyrolysis process can enrich Cu2+ and improve critical current density (Jc) of PEI-YBCO films. The highest Jc is 3.03 MA/cm2 at 77 K when the amount of PEI is 0.5 g/10 mL and the film thickness is 400 nm. Then the thickness increases from 0.4 to 2.0 μm by changing the coating times. The Jc values of PEI-YBCO films decrease gradually with the thickness increase. However, the critical current (Ic) can be up to 197 A/cm (at 77 K, self-field) and Jc can still keep 1.68 MA/cm2 at 1.2 μm. [ABSTRACT FROM AUTHOR]

Bilayered YDy0.5Ba2Cu3.6O7−δ superconducting films with a thickness of about 1 μ were deposited by metallorganic deposition method, an interlayer of secondary phase of SrZrO3 (SZO) and BaZrO3 (BZO) were inserted. Detailed growth mechanism studies of these structures as well as superconducting properties in different temperatures and magnetic field range (0-5 T) were investigated. Structural analysis showed that bilayer structure changed clearly the growth mechanism of YBCO. The SZO interlayer smoothens the film surface. Magnetic measurements of superconducting properties demonstrated that the critical temperature decreases slightly when both of SZO and BZO interlayer were inserted. This indicates a growing strain effect at the layer interfaces. The critical current densities as well as pining forces of bilayered YDy0.5Ba2Cu3.6O7−δ in the entire applied temperature and magnetic field range were enhanced by the insertion of SZO layer and decreased when BZO layer is introduced. The enhancement of the pinning properties is explained by the dense flux pinning in layered YDyBCO superconductors; this result may give further improvements in the current-carrying capability. [ABSTRACT FROM AUTHOR]

BaHfO (BHO) has been proposed as a new cap layer material for YBaCuO (YBCO) coated conductors. Highly c-axis oriented BHO cap layer has been deposited on ion-beam assisted deposition-MgO buffered Hastelloy tapes by direct-current-magnetron sputtering method. The epi-growth of BHO films combined with its properties is investigated in details. The degenerated cubic crystal structure of BHO film is confirmed by Raman spectrum analysis. XRD θ-2θ scan, φ-scan and ω-scan reveal an excellent c-axis alignment with good in-plane and out-of-plane textures for BHO cap layers. SEM and AFM investigations show BHO cap layer a dense and crack-free morphology. Subsequently pure c-axis orientation YBCO film was epitaxial grown on such BHO cap layer successfully, shown BaHfO a potential cap layer material for coated conductors. [ABSTRACT FROM AUTHOR]

LiNiCoMnO, LiMnO and LiCoO are paired to make the blended materials for the cathode of lithium-ion batteries. The factors impacting on the characteristics of blended materials are studied using constant current charge/discharge measurement and electrochemical impedance spectroscopy. The results show that the three pairs of blended materials exhibit very different synergetic effects in high C-rate discharging. The mechanism of particle synergetic effect has a physical root on the compensating material property of blending components, which fundamentally correlates with their similarity and difference in crystalline and electronic structures. The AC impedance show the obvious changes that alternate the high C-rate performance, due to reduced particle impedance in blended materials. The pairs of LiNiCoMnO-LiMnO and LiCoO-LiMnO present obvious increases in high C-rate reversible capacities than does the pair LiCoO-LiNiCoMnO. [ABSTRACT FROM AUTHOR]

Thick YBaCuO (YBCO) films grown by metallorganic deposition (MOD) are very significant for high-performance superconducting wires. In the present work, the modified MOD method with reduced fluorine content in precursor solution (namely LF-MOD in the following) is applied to prepare the YBCO films with the purpose of reducing the processing time as well as increasing thickness. Five-layer YBCO films with a thickness of more than 2.5 μm are achieved after the effect of high-temperature annealing time ( t) on the morphology and texture of YBCO films is systematically investigated. It is suggested that an annealing time as long as 6 h appears necessary to achieve a good performance for such a thick YBCO film. To understand the evolution of texture with thickness, plasma etching is employed to characterize the profile morphology at different depths inside the films, revealing the a-axis grains together with the impurity phases arising from the incomplete reaction mostly present at the top surface only. [ABSTRACT FROM AUTHOR]

This work presents a study of the evolution of the phases in the intermediate heat treatment process (IHP) which was after the pyrolysis process and before the crystallization of YBCO superconducting thin films. It was shown that the evolution of the solid solution could always take place whether with or without water vapor and oxygen. When water vapor is present in the atmosphere, the evolution temperature of the intermediate phase was lower than the one without vapor. The intermediate phase of YCuO with the vapor was observed at 680 °C. By calculating the changes of Gibbs free energy of reactions possibly involved in the IHP, the priority reaction with water vapor was CuF>YF>BaF when CuF, YF, and BaF coexisted while CuF and YF prefer to react with BaO to form BaF while they coexisted. The appearance of intermediate phase features could be illustrated through the calculation. [ABSTRACT FROM AUTHOR]

The possible exhaustion of fossil fuels in the near future and soaring global energy demand have driven the search for new types of sustainable and renewable alternatives. Perovskite (CHNHPbX, X = I, Br, Cl) solar cells are a type of solar cell based on a perovskite absorber, most commonly a tin halide-based or hybrid organic-inorganic lead material, as the visible-light sensitizer layer, which produces electricity from sunlight. Recently, perovskite solar cells have received substantial worldwide attention. Compared with traditional solar cells, the perovskite solar cells can obtain high efficiency with a simple architecture and via a cost-effective process. In the latest 5 years, the efficiency of perovskite solar cells to convert power has skyrocketed from 3.8 % to more than 19.3 %. It is the fastest advancing solar technology to date. The highest efficiency demonstrated by perovskite solar cells is higher than that of dye-sensitized solar cells (DSSCs). A lager number of research groups have demonstrated that perovskite solar cells may ultimately boost efficiency as high as 25 %. The high efficiency and cheap production costs make it evident that perovskite solar cells have great potential to be commercialized soon. In this review, the history, materials, processing and architecture of solar cells are discussed to obtain a better understanding of high-performance perovskite solar cells. [ABSTRACT FROM AUTHOR]

We report a mild template-free hydrothermal route for selective synthesis of SnO2 hollow microspheres and nano-sheets using SnCl2 and NaOH as initial materials. By switching the solvent from water to ethanol, the formed SnO2 nanostructures changed from nano-sheets to hollow microspheres. The obtained nano-sheets were single crystalline in structure. On the basis of the characterization of intermediate products, the formation of SnO2 hollow microspheres was ascribed to a crystal growth process, while the formation of SnO2 nano-sheets was ascribed to the oxidation of SnO2 sheets during the hydrothermal process. Further characterization of the SnO2 hollow microspheres and nano-sheets by X-ray photoelectron spectroscopy and UV-Vis absorption spectroscopy reveals different optical absorption properties and valence band electronic structures. In addition, the SnO2 nano-sheets and hollow microspheres exhibit different sensing properties. The present work provides a facile and simple template-free method for the synthesis of nano-structured SnO2. [ABSTRACT FROM AUTHOR]