A Change-Point Approach for Phase-I Analysis in Multivariate Profile Monitoring and Diagnosis

Process monitoring and fault diagnosis using profile data remains an important and challenging problem in statistical process control (SPC). Although the analysis of profile data has been extensively studied in the SPC literature, the challenges associated with monitoring and diagnosis of multichannel (multiple) nonlinear profiles are yet to be addressed. Motivated by an application in multioperation forging processes, we propose a new modeling, monitoring, and diagnosis framework for phase-I analysis of multichannel profiles. The proposed framework is developed under the assumption that different profile channels have similar structure so that we can gain strength by borrowing information from all channels. The multidimensional functional principal component analysis is incorporated into change-point models to construct monitoring statistics. Simulation results show that the proposed approach has good performance in identifying change-points in various situations compared with some existing methods. The codes for implementing the proposed procedure are available in the supplementary material.     

基于Ⅳ-Ⅵ族化合物的胶体量子点太阳电池研究进展

基于Ⅳ-Ⅵ族化合物的胶体量子点具有易于合成、带隙可调等优点,被认为是一种非常有前途的窄带隙光伏材料。近年来,利用Ⅳ-Ⅵ族化合物制作的胶体量子点太阳电池最高转换效率已经突破10%。介绍了胶体量子点的合成方法、基本结构及其光电特性;着重分析了国内外关于肖特基和异质结胶体量子点太阳电池的研究现状,指出了目前该领域研究中存在的问题和发展趋势,并分析了未来需要重点解决的关键问题。     

Nanostructured Li3V2(PO4)3 Cathodes

To further increase the energy and power densities of lithium‐ion batteries (LIBs), monoclinic Li₃V₂(PO₄)₃ attracts much attention. However, the intrinsic low electrical conductivity (2.4 × 10^?7 S cm^?1) and sluggish kinetics become major drawbacks that keep Li₃V₂(PO₄)₃ away from meeting its full potential in high rate performance. Recently, significant breakthroughs in electrochemical performance (e.g., rate capability and cycling stability) have been achieved by utilizing advanced nanotechnologies. The nanostructured Li₃V₂(PO₄)₃ hybrid cathodes not only improve the electrical conductivity, but also provide high electrode/electrolyte contact interfaces, favorable electron and Li⁺ transport properties, and good accommodation of strain upon Li⁺ insertion/extraction. In this Review, light is shed on recent developments in the application of 0D (nanoparticles), 1D (nanowires and nanobelts), 2D (nanoplates and nanosheets), and 3D (nanospheres) Li₃V₂(PO₄)₃ for high‐performance LIBs, especially highlighting their synthetic strategies and promising electrochemical properties. Finally, the future prospects of nanostructured Li₃V₂(PO₄)₃ cathodes are discussed.     

In Situ Chelating Synthesis of Hierarchical LiNi1/3Co1/3Mn1/3O2 Polyhedron Assemblies with Ultralong Cycle Life for Li‐Ion Batteries

Layered lithium transition‐metal oxides, with large capacity and high discharge platform, are promising cathode materials for Li‐ion batteries. However, their high‐rate cycling stability still remains a large challenge. Herein, hierarchical LiNi_1/3Co_1/3Mn_1/3O₂ polyhedron assemblies are obtained through in situ chelation of transition metal ions (Ni²⁺, Co²⁺, and Mn²⁺) with amide groups uniformly distributed along the backbone of modified polyacrylonitrile chains to achieve intimate mixing at the atomic level. The assemblies exhibit outstanding electrochemical performances: superior rate capability, high volumetric energy density, and especially ultralong high‐rate cyclability, due to the superiority of unique hierarchical structures. The polyhedrons with exposed active crystal facets provide more channels for Li⁺ diffusion, and meso/macropores serve as access shortcuts for fast migration of electrolytes, Li⁺ and electrons. The strategy proposed in this work can be extended to fabricate other mixed transition metal‐based materials for advanced batteries.     

Fabricating Ir/C Nanofiber Networks as Free‐Standing Air Cathodes for Rechargeable Li‐CO2 Batteries

Li‐CO₂ batteries are promising energy storage systems by utilizing CO₂ at the same time, though there are still some critical barriers before its practical applications such as high charging overpotential and poor cycling stability. In this work, iridium/carbon nanofibers (Ir/CNFs) are prepared via electrospinning and subsequent heat treatment, and are used as cathode catalysts for rechargeable Li‐CO₂ batteries. Benefitting from the unique porous network structure and the high activity of ultrasmall Ir nanoparticles, Ir/CNFs exhibit excellent CO₂ reduction and evolution activities. The Li‐CO₂ batteries present extremely large discharge capacity, high coulombic efficiency, and long cycling life. Moreover, free‐standing Ir/CNF films are used directly as air cathodes to assemble Li‐CO₂ batteries, which show high energy density and ultralong operation time, demonstrating great potential for practical applications.     

Facile synthesis of porous germanium-iron bimetal oxide nanowires as anode materials for lithium-ion batteries

Germanium-based oxide has been found to be a promising high-capacity anode material for lithium-ion batteries (LIBs). However, it exhibits poor electrochemical performance because of the drastic volume change during cycling. Herein, we designed porous Ge-Fe bimetal oxide nanowires (Ge-Fe-O_x-700 NWs) by a large-scale and facile solvothermal reaction. When used as the anode material for LIBs, these Ge-Fe-O_x-700 NWs exhibited superior electrochemical performance (～ 1,120 mAh·g^?1 at a current density of 100 mA·g^?1) and good cycling performance (～ 750 mAh·g^?1 after 50 cycles at a current density of 100 mA·g^?1). The improved performance is due to the small NW diameter, which allows for better accommodation of the drastic volume changes and zero-dimensional nanoparticles, which shorten the diffusion length of ions and electrons.

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A novel PMA/PEG-based composite polymer electrolyte for all-solid-state sodium ion batteries

In recent years, development of all-solid-state batteries has become a promising approach to improve the safety of batteries. Herein, we report the preparation of a new composite polymer electrolyte (CPE) for use in all-solid-state sodium ion batteries. The CPE comprising of poly(methacrylate) (PMA), poly(ethylene glycol) (PEG), α-Al₂O₃ with acidic surface sites, and NaClO₄ exhibited high ionic conductivity (1.46 × 10^-4 S·cm^-1 at 70 °C), wide electrochemical stability window (4.5 V vs. Na⁺/Na), and good mechanical strength. With the introduction of the prepared CPE and Na₃V₂(PO₄)₃, the final all-solid-state sodium ion batteries showed good rate and cycle performance, with a high reversible capacity of 85 mAh·g^-1 when operated at 0.5 C (1 C = 118 mA·g^–1) and 94.1% capacity retention rate after 350 cycles at 70 °C. Our work provides a novel solid electrolyte for the development of all-solid-state sodium ion batteries.

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Aggregation-induced emission luminogen-assisted stimulated emission depletion nanoscopy for super-resolution mitochondrial visualization in live cells

Nano Research - Aggregation-induced emission luminogens (AIEgens) are fluorescent agents that are ideal for bioimaging and have been widely used for organelle targeting, cellular mapping, and...