A Tour of the Tour of the Hilbert-Huang Transform: An Empirical Tool for Signal Analysis

The HHT provides an alternative tool for signal analysis. Case studies in applying the HHT technique for bearing degradation monitoring and machine tool breakage detection have demonstrated its effectiveness for revealing the non-stationary and non-linear features hidden in dynamic signals. In addition to the application illustrated in this article, the HHT technique has shown to be effective in other applications, such as biomedical engineering [8], [9], system identification [10], [11], environmental monitoring [12], or financial analysis [13]. Because of its empirical nature, rigorous mathematical proof of this technique has remained an active research topic. More interesting reports are to be expected on the application of this technique for solving various types of real-world problems.     

基于MODIS数据的安徽省土地覆盖分类研究

利用中分辨率成像光谱仪MODIS(MODerate Resolution Imaging Spectroradiometer)多时相、多光谱及纹理数据,结合安徽省GIS属性数据(2000年1∶25万土地利用图),采用多时相分类和分层分类相结合的方法对安徽省土地覆盖进行分类(水田、旱地、林地、水体、城市).最后,使用安徽土地利用格点数据对分类结果进行精度分析.结果表明:应用MODIS数据可以实时有效的获取安徽省土地覆盖信息,同时对大面积土地覆盖分类具有很好的精度.     

调频广播传播预测方法分析与本地应用研究

准确评估调频广播覆盖效果,更好地为用户服务,是广播从业者追求的目标.本文介绍ITU-R P.1546模型的预测方法,分析不同参数带来的差异,结合实际测量提出该模型本地化的应用建议,为ITU-R P.1546模型本地化改进以及广播业务规划提供了参考.     

Biomimetic Hygroscopic Fibrous Membrane with Hierarchically Porous Structure for Rapid Atmospheric Water Harvesting

Sorption-based atmospheric water generation (SAWG) is a promising strategy to alleviate the drinkable water scarcity of arid regions. However, the high-water production efficiency remains challenging due to the sluggish sorption/desorption kinetics. Herein, a composite sorbent@biomimetic fibrous membrane (PPy-COF@Trilayer-LiCl) is reported by mimicking nature's Murray networks, which exhibits outstanding water uptake performance of 0.77–2.56 g g⁻¹ at a wide range of relative humidity of 30%–80% within 50 min and fast water release capacity of over 95% adsorbed water that can be released within 10 min under one sun irradiation. The superior sorption–desorption kinetics of PPy-COF@Trilayer-LiCl are enabled by the novel hierarchically porous structure, which is also the critical factor to lead a directional rapid water transport and vapor diffusion. Moreover, as a proof-of-concept demonstration, a wearable SAWG device is established, which can operate 10 sorption–desorption cycles per day in the outdoor condition and produce a high yield of clean water reaching up to 3.91 kg m⁻² day⁻¹. This study demonstrates a novel strategy for developing advanced solar-driven SAWG materials with efficient water sorption–desorption properties.     

Rewritable Electrically Controllable Liquid Crystal Actuators

Conductive structures determine the functions and actuation modes of electrically responsive soft actuators. The rewritability of conductive structures is highly desirable but has not been realized in electro-driven actuators. Typically, once conductive pathways are established, they can hardly be modified; thus, the function of the actuator is permanently fixed. In this study, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) is developed as a rewritable conductive coating for actuators composed of liquid crystalline elastomers (LCEs). This enables reconfigurable, adaptive, and precisely controllable electro-driven motions and the repeated use of the same actuator for various purposes without disposal. Moreover, different PEDOT:PSS layers can be coated onto different regions, thus enabling the assembly of different actuation behaviors in a monolithic actuator under a single input voltage. Unlike all previously reported soft actuators that respond to electricity and light, opposite shape changes in an actuator with a series circuit can be performed under these two stimuli. Furthermore, when combining LCEs with dynamic covalent bonds, the PEDOT:PSS-coated LCE (PEDOT:PSS-LCE) actuator can be reprogrammed based on two different mechanisms: rewriting the conductive PEDOT:PSS patterns and re-aligning the LCEs. This versatile method can be adapted to other types of actuators.     

综合业务接入区业务承载方案

随着中国移动在全国范围内开展的综合业务接入区建设的基本完成,如何充分利用综合业务接入区资源,降低投入成本,有效地支撑业务发展,提高各接入区业务接入能力,是未来综合业务接入区发展的基本要求。本文通过对已建成的综合业务接入区承载业务诸多问题进行分析,提出了综合业务接入区内基站、WLAN、集团客户专线、家庭宽带等各类业务承载方案。     

基于传声器阵列的声定位成像系统研究与设计

为了实现对室内声源定位的目的,文中对其中的两个关键技术：时延估计、定位算法做了深入的研究.通过使用高保真监听拾音器、多功能信号采集器MPS010602,以及结合简单的数据采集图形化编程软件LabVIEW,搭建了软硬件设计系统,讨论了五元十字阵列在不同条件下的定位精度.实验应用表明：该系统可以创新性的对多个声源判决定位,并且提高了声阵列定位成像系统在细节上的分辨能力.     

Direct Freeform Laser Fabrication of 3D Conformable Electronics

3D conformable electronic devices on freeform surfaces show superior performance to the conventional, planar ones. They represent a trend of future electronics and have witnessed exponential growth in various applications. However, their potential is largely limited by a lack of sophisticated fabrication techniques. To tackle this challenge, a new direct freeform laser (DFL) fabrication method enabled by a 5-axis laser processing platform for directly fabricating 3D conformable electronics on targeted arbitrary surfaces is reported. Accordingly, representative laser-induced graphene (LIG), metals, and metal oxides are successfully fabricated as high-performance sensing and electrode materials from different material precursors on various types of substrates for applications in temperature/light/gas sensing, energy storage, and printed circuit board for circuit. Last but not the least, to demonstrate an application in smart homes, LIG-based conformable strain sensors are fabricated and distributed in designated locations of an artificial tree. The distributed sensors have the capability of monitoring the wind speed and direction with the assistance of well-trained machine-learning models. This novel process will pave a new and general route to fabricating 3D conformable electronic devices, thus creating new opportunities in robotics, biomedical sensing, structural health, environmental monitoring, and Internet of Things applications.     

一种应用于芯片高精度拾放的视觉定位方法

视觉定位技术是全自动芯片拾放设备的核心技术之一,其设计需结合设备功能、结构特点、运动方式来完成。介绍的视觉定位方法采用仰视与俯视双相机、俯视相机双镜头切换方式,适用于全自动粘片机、点胶机、晶圆芯片拾取机等设备中的拾放定位功能,及设备执行部件相对位置校验功能。     

无线传感器网络通信技术与标准化分析

通过分析现有无线传感器网络标准,并对Zig Bee、蓝牙以及Wi-Fi这3种最常用标准的优缺点进行详细比较,探讨了无线传感器网络通信技术面临的挑战,进一步研究策略和未来发展趋势。