A High Capacity All Solid-State Li-Sulfur Battery Enabled by Conversion-Intercalation Hybrid Cathode Architecture

As demands for electrochemical energy storage continue to rise, alternative electrochemistries to conventional Li-ion batteries become more appealing. Here, an intercalation-conversion hybrid cathode that combines intercalation-type VS₂ with conversion-type sulfur chemistry to construct high performance solid-state lithium-sulfur batteries is reported. The layered VS₂ nanomaterial features Li-ion transport channels, metallic conductivity, and active capacity contribution, all of which provide an ideal platform for the solid state S/Li₂S redox couple to unlock its high gravimetric capacity. The S/VS₂/Li₃PS₄ hybrid cathode composite is prepared by a facile, low-cost, and low-energy mechanical blending process. The S/VS₂/Li₃PS₄|Li₃PS₄|Li/In (or Li) all-solid-state cell exhibits sulfur utilization of ≈85%, with a Coulombic efficiency of close to 100%. High areal capacity up to 7.8 mA h cm⁻² with an active material loading (S/VS₂) as high as 15.5 mg cm⁻² is achieved.     

Wide Bandgap Polymer with Narrow Photon Harvesting in Visible Light Range Enables Efficient Semitransparent Organic Photovoltaics

Wide bandgap polymer D18 with narrow photon harvesting in visible light range and small molecule N3 with near-infrared photon harvesting are adopted for building semitransparent organic photovoltaics (OPVs). To find out the optimal D18:N3 weight ratio for semitransparent OPVs, series of opaque OPVs are built with a varied D18:N3 weight ratio. The power conversion efficiency (PCE) and fill factor can be maintained over 16% and 77% in the D18:N3 (0.7:1.6, wt/wt) based opaque OPVs, respectively. The average visible transmittance (AVT) of the corresponding blend films can be achieved over 50%, demonstrating the great potential in fabricating efficient semitransparent OPVs. The semitransparent OPVs based on D18:N3 (0.7:1.6, wt/wt) are fabricated by using 1 nm Au/(10, 15, 20 nm) Ag as cathode. The thickness of Ag layers is varied to balance the optical properties and electrical properties of semitransparent top electrode. The semitransparent OPVs with 10 nm Ag achieve the highest light utilization efficiency of 2.90% with a PCE of 12.91% and an AVT of 22.49%, which should be among the best performance of reported semitransparent OPVs. This work demonstrates that the wide bandgap polymer donor with narrow photon harvesting in visible light range has great potential in preparing efficient semitransparent OPVs.     

改进混合积累的单通道机载SAR高径向速度目标检测方法

高径向速度目标会产生严重的距离走动并伴随方位失配,方位压缩会使其散焦并弥散在SAR图像中,不易被检测。该文针对高径向速度目标的检测问题,提出一种基于单通道机载SAR的检测方法。该方法通过抽取等效双通道,利用相干对消抑制杂波,并去除动目标的频谱分裂,再运用Dechirp处理和Hough变换积累目标在距离单元内和距离单元间的能量,以获得更大的积累增益。与传统的混合积累方法相比,该方法在抑制杂波的基础上,更好地积累高径向速度目标的能量,从而有效提高该类目标的检测性能。仿真数据和实测数据均验证了该方法的有效性和优越性。     

A Fluorophore‐Doped Polymer Nanomaterial for Referenced Imaging of pH and Temperature with Sub‐Micrometer Resolution

A new kind of pH and temperature sensitive material is reported. It is composed of dye‐doped polymer nanoparticles incorporated into a thin film of a polyurethane hydrogel. The new pH/temperature‐sensitive nanoparticles are obtained by post‐staining oxygen‐impermeable amino‐functionalized polyacrylonitrile nanoparticles with a long‐lifetime reference dye. Staining is followed by covalently linking fluorescein isothiocyanate onto the surface of the nanoparticle. The new sensor material has several distinct features: a) it enables imaging of pH via time domain dual‐lifetime referencing; b) effects of temperature on pH sensing may be compensated for; and c) temperature can simultaneously be visualized via rapid lifetime imaging. The new material enables referenced and temperature‐compensated pH imaging with superior spatial resolution due to the use of nanosized sensor nanoparticles.     

A Visible‐ and NIR‐Light Responsive Photothermal Therapy Agent by Chirality‐Dependent MoO3−x Nanoparticles

Chirality‐based semiconducting nanocrystals, as an emerging area, are envisioned to have great potential in chiral sensing, biomedicine, and chiroptical devices. Herein, chiral substoichiometric molybdenum oxide (l /d ‐Cys‐MoO_3?x) nanoparticles are synthesized via step‐by‐step reduction treatment with chiral cysteine molecules. The obtained nanoparticles are used as visible‐ and near‐infrared‐light dual responsive photothermal therapy agent for tumor cell ablation. Notably, the chiral nanoparticles show chiral selectivity for incident light, i.e., when irradiated by left‐circularly polarized light, l ‐Cys‐MoO_3?x is the most sensitive agent giving the highest mortality for HeLa cell ablation in vitro, and vice versa for right‐circularly polarized light with d ‐Cys‐MoO_3?x. In comparison to traditional photothermal therapy with near‐field light source, the investigations with chiral visible light at 532 nm indicate the possibility of chiral Cys‐MoO_3?x nanoparticles for visible light‐based phototherapy via metal–ligand charge transfer chirality, which provides insights for new methods in nanotechnology supported photothermal treatments.     

Mie‐Resonant Membrane Huygens' Metasurfaces

All‐dielectric metasurfaces have become a new paradigm for flat optics as they allow flexible engineering of the electromagnetic space of propagating waves. Such metasurfaces are usually composed of individual subwavelength elements embedded into a host medium or placed on a substrate, which often diminishes the quality of the resonances. The substrate imposes limitations on the metasurface functionalities, especially for infrared and terahertz frequencies. Here a novel concept of membrane Huygens' metasurfaces is introduced. The metasurfaces feature an inverted design, and they consist of arrays of holes made in a thin membrane of high‐index dielectric material, with the response governed by the electric and magnetic Mie resonances excited within dielectric domains of the membrane. Highly efficient transmission combined with the 2π phase coverage in the freestanding membranes is demonstrated. Several functional metadevices for wavefront control are designed, including beam deflector, a lens, and an axicon. Such membrane metasurfaces provide novel opportunities for efficient large‐area metadevices, whose advanced functionality is defined by structuring rather than by chemical composition.     

全工况仿真平台在电气工程教学中的应用

各类非对称接地故障在中压配电网中是非常普遍的,因此在电气工程教学过程中对于lOkV配电网故障的产生、过程、危害以及防治等进行研究和授课具有十分重要的现实意义。本文使用电力系统仿真工具PSCAD／EMTDC构建了10kV配电网的全工况仿真平台,并建立了并行仿真环境,在此基础上可开展对中性点不同的接地方式、四类不同消弧线圈...     

短波正交频分复用(OFDM)传输性能研究

短波通信作为一种重要的通信方式一直受到信道带宽的限制,加之传输信道的不稳定性致使其传输效果不佳,如何有效的提高频带利用率、改善传输性能是短波通信的重要研究内容。正交频分复用(OFDM)是一种多载波数字调制技术,在提高频谱利用率、克服多径方面发挥了重要作用。文章以Simulink为平台构建短波OFDM通信系统仿真模型,并在频偏和多径条件下进行仿真,分析仿真结果可以看到,频偏和多径对系统的传输效果都有影响,其中频偏对通信系统的影响较为严重。     

Sulfur Composite Cathode Materials for Rechargeable Lithium Batteries

Conductive polymer/sulfur composite materials were prepared by heating the mixture of polyacrylonitrile (PAN) and sublimed sulfur. During the heating process, PAN was dehydrogenated by sulfur, forming a conductive main chain similar to polyacetylene. At the same time, the high‐polarity functional group –CN cyclized at the melt state, forming a thermally stable heterocyclic compound in which sulfur was embedded. The nanodispersed composites showed excellent electrochemical properties. Tested as cathode material in a non‐aqueous lithium cell based on poly(vinylidene fluoride) (PVDF) gel electrolyte at room temperature, the composite exhibited a specific capacity up to 850 mA h g^–1 in the initial cycle. Its specific capacity remained above 600 mA h g^–1 after 50 cycles, about five times that of LiCoO₂, and recovered partly after replacement of the anode with a fresh lithium sheet. The utilization of the electrochemically active sulfur was about 90 % assuming a complete reaction to the product, Li₂S.