Self-Adhesive Polydimethylsiloxane Foam Materials Decorated with MXene/Cellulose Nanofiber Interconnected Network for Versatile Functionalities

Polydimethylsiloxanes (PDMS) foam as one of next-generation polymer foam materials shows poor surface adhesion and limited functionality, which greatly restricts its potential applications. Fabrication of advanced PDMS foam materials with multiple functionalities remains a critical challenge. In this study, unprecedented self-adhesive PDMS foam materials are reported with worm-like rough structure and reactive groups for fabricating multifunctional PDMS foam nanocomposites decorated with MXene/cellulose nanofiber (MXene/CNF) interconnected network by a facile silicone foaming and dip-coating strategy followed by silane surface modification. Interestingly, such self-adhesive PDMS foam produces strong interfacial adhesion with the hybrid MXene/CNF nano-coatings. Consequently, the optimized PDMS foam nanocomposites have excellent surface super-hydrophobicity (water contact angle of ≈159^o), tunable electrical conductivity (from 10⁻⁸ to 10 S m⁻¹), stable compressive cyclic reliability in both wide-temperature range (from −20 to 200 ^oC) and complex environments (acid, sodium, and alkali conditions), outstanding flame resistance (LOI value of >27% and low smoke production rate), good thermal insulating performance and reliable strain sensing in various stress modes and complex environmental conditions. It provides a new route for the rational design and development of advanced PDMS foam nanocomposites with versatile multifunctionalities for various promising applications such as intelligent healthcare monitoring and fire-safe thermal insulation.     

一种宽带宽角圆极化天线的设计研究

本文提出了一种宽带圆极化微带层叠天线形式,天线采用多层结构,使用正交耦合缝隙附加90°相移对贴片 馈电,以达到宽带宽角圆极化工作的目的。采用矩量法对天线进行了计算,确定其最终的各项参数。通过对样机 的测试表明,天线性能与计算结果相符很好,驻波比小于2 的相对带宽大于35％;天线方向图在140°的范围内增 益大于0dB,轴比在30％的带宽内小于3dB,是一种性能优良的宽带双极化天线。     

高兼容性低成本无铅材料开发与应用

现今市面上主流的无铅材料多是中Tg和高Tg的产品,高的Tg的预示着高成本;目前全球经济持续低迷,给PCB行业也带来了不小的冲击,迫使各PCB厂家积极寻求低成本高性能的替代材料。CCL供应商推出的PN固化、添加无机填料的普通Tg无铅兼容材料无疑成为一大亮点,成为有效提升客户产品性价比和竞争力的首选。此类型材料除满足一般传统多层板的要求,在HDI板、高多层及厚铜板方面表现同样优秀,文章将逐一说明,以供大家参考和借鉴。     

可快速精确重建的毫米波MIMO近距离成像机制研究

毫米波成像在人体安检领域发挥了重要作用,引起了人们的广泛关注。现有的毫米波近场人体安检成像机制主要分为SISO和MIMO两种。SISO机制可实现快速精确成像,然而随着工作频率的升高,其所需天线数目迅速增长、天线间隔下降,不仅造成了系统成本提升,还使得天线耦合难以被抑制。MIMO机制虽然降低了成像所需的天线数目、增大了天线间隔,但目前无法实现类似SISO机制的快速精确重建。提出了一种可快速精确重建的MIMO近距离成像机制,定量给出了该机制的适用条件。与传统MIMO近距离成像机制不同,该MIMO近距离成像机制通过巧妙地设计MIMO子阵列,使其在近场成像中满足等效相位中心原理。因此它能够直接使用诸如距离迁徙算法（range migration algorithm,RMA）等各种基于SISO机制开发的精确且快速的成像算法去重建图像,兼顾了SISO机制和MIMO机制的优势。E波段的示例表明,在近场毫米波成像中,该MIMO机制与SISO机制具有同等水平的成像质量和成像速度,但相较于SISO机制,该MIMO机制的天线利用率、天线间隔可提升4倍以上。与传统MIMO成像机制相比,该MIMO成像机制不但有更好的成像质量,而且其重建速度大幅提升,在一个成像区域为1 m×1 m×0.2 m,体素尺寸为1.85 mm3的典型成像场景中,比传统MIMO成像机制快近200,000倍。仿真和实验结果验证了该成像机制的有效性。     

A quantitative design methodology for high-speed interpolation/averaging ADCs

This paper proposes a new quantitative and systematic design methodology for high-speed interpolation/ averaging ADCs. The methodology consists of a new mathematical BW/gain model derived from the pre-amps arrays static model and new small-signal model, a new offset modeling mechanism that can accurately estimate and help to reduce the offset, and hence a new systematic design flow. The methodology enables a quantitative and systematic analysis, conducts iterative and accurate calculation realized in MATLAB, and finally leads to an optimized ADC design that reaches a guaranteed optimum full-chip performance with given specs (i.e., resolution, speed, input range, power, input CM, etc.). The methodology shows significant advantage over the traditional trial-and-error ADC design approach with respect to performance and design efficiency, and is much more reliable in nanometer technologies. The proposed methodology was fully validated in silicon: a 4-bit 5GSps interpolation/averaging ADC is fabricated in a 65 nm CMOS technology and the measurement results show that our ADC has indeed achieved an outstanding and comparable overall performance compared to reported state-of-the art ADCs.     

Evaluation of the pole expressions of nano-scale multistage amplifiers based on equivalent output impedance

Several frequency compensation schemes have been proposed to stabilize multistage amplifiers with negative feedback. The performance of these amplifiers can be analyzed by inspecting their input-output transfer function as representation of their frequency response. With many circuit elements affecting the output response, it is relatively difficult to obtain the real transfer function of multistage amplifiers based on only the original small-signal expressions. Instead, certain techniques such as Miller’s theorem are used to approximate important parameters such as DC gain and dominant pole. These methods are not generally helpful for approximating the nondominant poles which have a critical role on the loop stability of nano-scale amplifiers. With this issue in mind, this work proposes a systematic methodology to achieve the pole expressions of multistage amplifiers with frequency compensation. The key in the proposed technique is to model the equivalent impedance of the compensation loop at the output. The effectiveness of the proposed approach has been verified through comparison between the transfer functions obtained from theory and those transfer functions found in the literature.     

5G基站的配套改造方式浅析

随着5G商用牌照的发放,5G基站建设如火如荼地开展,5G基站的基础配套的改造需求变得越来越紧迫.现有基站的配套能力如何满足5G建设的需要,成为亟需面对和解决的问题.通过分析三大运营商5G网络的特点和架构,同时考虑多家运营商共享情况,并根据5G网络建设实施情况分析5G基站的塔桅抱杆、电源和外电的配套改造方案.     

一种基于实时几何测距的船桥主动防撞方法

本文提出一种基于实时几何测距的船桥主动防撞方法.该方法对船的改动量甚微,仅需维持多项距离矩阵,通过告警逻辑矩阵进行展示与告警,能起到很好的船桥防撞提示效果.     

4K技术在我国影视行业中的应用与发展

4K技术极大地提升了视频清晰度,给用户带来了极致的沉浸式观影体验和视觉享受,满足了受众对影视节目制作质量不断提升的要求,因此被广泛应用于影视行业。从诞生至今,4K超高清技术已经逐步完善,目前已经向8K技术进发。梳理4K技术在我国影视行业的应用和发展历程,可以更好地促进4K技术的进一步发展,同时为8K技术的普及和发展提供参考。     

高分辨率机载InSAR高程距离向空变误差定标方法

高分辨率机载干涉合成孔径雷达(Interferometric Synthetic Aperture Radar, InSAR)是获取高精度数字高程模型(Digital Elevation Model, DEM)的重要手段之一。由于主副天线距离向相位方向图存在差异等原因,导致干涉相位偏差沿距离向变化,而传统的干涉定标方法将干涉相位偏差视为常数进行定标,无法消除干涉相位沿距离向变化的误差,因此使得定标后反演得到的高程存在距离向空变误差。针对该问题,该文提出一种单独将干涉相位偏差沿视角进行多项式拟合的定标方法。最后,利用一组机载实测数据对该方法加以验证,实验结果表明,该方法能有效地解决高分辨率机载InSAR高程测量距离向误差的空变问题。