Nacre-Inspired,Liquid Metal-Based Ultrasensitive Electronic Skin by Spatially Regulated Cracking Strategy

The realization of liquid metal-based wearable systems will be a milestone toward high-performance, integrated electronic skin. However, despite the revolutionary progress achieved in many other components of electronic skin, liquid metal-based flexible sensors still suffer from poor sensitivity due to the insufficient resistance change of liquid metal to deformation. Herein, a nacre-inspired architecture composed of a biphasic pattern (liquid metal with Cr/Cu underlayer) as “bricks” and strain-sensitive Ag film as “mortar” is developed, which breaks the long-standing sensitivity bottleneck of liquid metal-based electronic skin. With 2 orders of magnitude of sensitivity amplification while maintaining wide (>85%) working range, for the first time, liquid metal-based strain sensors rival the state-of-art counterparts. This liquid metal composite features spatially regulated cracking behavior. On the one hand, hard Cr cells locally modulate the strain distribution, which avoids premature cut-through cracks and prolongs the defect propagation in the adjacent Ag film. On the other hand, the separated liquid metal cells prevent unfavorable continuous liquid-metal paths and create crack-free regions during strain. Demonstrated in diverse scenarios, the proposed design concept may spark more applications of ultrasensitive liquid metal-based electronic skins, and reveals a pathway for sensor development via crack engineering.     

基于FPGA的107 cm全色PDP驱动控制信号产生电路的设计

从等离子体平板显示器(PDP)的发光原理出发,分析和研究了等离子体显示器(PDP)的驱动显示原理,给出了驱动控制原理图,提出一种新颖的基于现场可编程门阵列(FPGA)的驱动控制信号产生方案。最后给出了该方案的具体电路框图和仿真波形。     

ZrO2掺杂及其工艺参数的对AC-PDP介质保护膜结晶取向的影响

在电子束蒸发镀膜工艺条件下,掺杂含量、基板温度和蒸镀速率都会对薄膜的结晶取向产生影响.掺杂含量会影响复合膜层的晶面取向和X射线衍射峰的强度,其中ZrO2掺杂比为0.2时,能获得相对最强的(111)晶面衍射峰.而对于复合介质保护膜的制备工艺,则是较低的基板温度和较高的蒸镀速率条件下,更容易形成(111)的晶面取向;较高的基板温度和较低的蒸镀速率条件下,则更容易形成(200)或(220)的晶面取向.     

阶梯电压驱动场致发光器件的电路设计

阐述了阶梯状电压驱动方式的具体原理及其硬件实现电路,同传统的方波电压驱动原理相比较,使用阶梯状电压驱动方式可以使场致发光显示器件的耗能降低到传统方式的75%,最后介绍了阶梯状电压驱动方式的硬件电路设计。     

Influence of the underneath cavity on buoyant‐forced cooling of the integrated photovoltaic panels in building roof: a thermography study

Airflow around building‐integrated photovoltaics (BIPV) has a significant impact on their hygrothermal behavior and degradation. The potential of reducing the temperature of BIPV using an underneath cavity is experimentally and numerically investigated in literature. Most of the models are oversimplified in terms of modeling the impact of 3D flow over/underneath of PV modules, which can result in a non‐uniform surface temperature and consequently a non‐homogenous thermal degradation. Moreover, the simultaneous presence of radiation and convection related to upstream wind, in addition to the combined impact of back‐ventilation and surface convection, is barely addressed in literature. However, these simplifications can result in the unrealistic loading climate conditions. This paper aims to present a unique experimental setup to provide more realistic climate conditions for investigating the ventilation potential of the underneath. The setup consists of a solar simulator and a building prototype with installed PV, placed inside an atmospheric wind tunnel to control upstream wind velocity. Thermography is performed using an infrared camera to monitor the surface temperature of the BIPV. The potential of an underneath cavity with various cavity heights and PV arrangement is further investigated in this paper. The outcome would be eventually useful in the development of practical guidelines for BIPV installation. Copyright © 2013 John Wiley & Sons, Ltd.     

激光超声透射波频域特征的仿真与实验研究

为了解决航空发动机原位裂纹的快速检测问题,通过数值模拟与实验分析相结合,分析激光超声透射波与不同深度缺陷的铝板相互作用后的频域波形峰值的变化。研究表明：（1）随着缺陷深度的增加,透射波频域波形的幅值整体上呈现降低的趋势;（2）由实验数据分析可得,缺陷深度从0.3mm增加到0.9mm时,Ⅰ、Ⅱ、Ⅲ区的峰值增加量分别为35.45%、24.90%、24.11%,即其增加量逐渐减小。该分析方法为超声信号表征表面微缺陷提供了一种思路,为今后从频域峰值方面分析裂纹深度奠定一定的基础。     

改善激光熔覆镍基合金和陶瓷硬质相复合涂层性能的研究

激光熔覆镍基合金和陶瓷硬质相（WC）复合涂层过程中存在的问题是容易形成缺陷和开裂。通过调整WC的比例和分布,合理的工艺参数,增设韧性良好的过渡层,并加入微量混合稀土氧化物,对发生马氏体相变硬化的热影响区进行激光回火处理等,以获得无裂纹缺陷,金相组织均匀,并具有硬度平滑过渡的优质熔覆层。     

5G大规模MIMO增强技术及发展趋势

大规模MIMO技术是5G的关键技术之一,其原理是当基站天线数量远远大于终端天线数量的时候,基站到各个用户之间的干扰趋于消失,为更好地应用大规模MIMO技术提升系统容量和用户频谱效率,3GPP对相关技术进行了标准化。首先介绍了3GPP在Rel15阶段对大规模波束赋形的传输方案和波束管理等关键技术的标准化情况,然后重点分析描述了Rel16阶段大规模MIMO的增强技术,包括多点(TRP)/多面板(panel)发送以及多波束发送等关键技术,未来大规模MIMO的发展趋势将根据实际应用部署对相关的技术做进一步增强。     

LED显示屏驱动电流的潜在电磁干扰分析

为了控制对发光二极管(LED)显示屏亮度调制时电 源电流产生的电磁干扰(EMI),对3种脉冲宽度调制(PWM)调光方法下显示 屏的电源电流频谱进行了研究。首先比较了线性、离散和选通3种PWM的调光原理和潜在 EMI,设计了基于电流频谱分析的EMI评估法,并通过对单亮度和亮度均匀渐变图像 的仿真,验证了评 估法的有效性;最后通过对LED显示屏真实图像显示时的电流频谱分析,比较了3种调光方 法的潜在EMI。实验结果表明:线性PWM方式下,同时点亮LED会产生较大的EMI;离 散PWM对消耗电流的 延展和码制对消作用,可以有效地减小EMI;选通PWM随着选通等级的提高,最小点 亮脉冲变窄不利 于减小EMI。本文的分析结果可用于在LED显示屏产品设计时,合理进行EMI分析 与分配,预估产品的电磁兼容性。     

基于Verilog的模拟前端时序的实现方法

针对如何高精度、高速实现模拟前端时序的问题,提出了一种用于平板探测器的模拟前端时序的Verilog实现方法。Verilog语言的编程整体上采用模块化设计,主要包含电荷采集模块、数据读出模块和计数器模块。利用锁相环技术设置各模块不同的时钟信号,通过编写有限状态机和改进型计数器实现各模块的时序。仿真结果表明,该编程方法满足了时序高精度实现的需求,具有运行速度快、灵活性高等特点,达到了预期效果。