Recent Advances on High-Speed and Holographic Two-Photon Direct Laser Writing

Two-Photon Lithography, thanks to its very high sub-diffraction resolution, has become the lithographic technique par excellence in applications requiring small feature sizes and complex 3D pattering. Despite this, the fabrication times required for extended structures remain much longer than those of other competing techniques (UV mask lithography, nanoimprinting, etc.). Its low throughput prevents its wide adoption in industrial applications. To increase it, over the years different solutions have been proposed, although their usage is difficult to generalize and may be limited depending on the specific application. A promising strategy to further increase the throughput of Two-Photon Lithography, opening a concrete window for its adoption in industry, lies in its combination with holography approaches: in this way it is possible to generate dozens of foci from a single laser beam, thus parallelizing the fabrication of periodic structures, or to engineer the intensity distribution on the writing plane in a complex way, obtaining 3D microstructures with a single exposure. Here, the fundamental concepts behind high-speed Two-Photon Lithography and its combination with holography are discussed, and the literary production of recent years that exploits such techniques is reviewed, and contextualized according to the topic covered.     

In Situ Electrical Network Activation and Deactivation in Short Carbon Fiber Composites via 3D Printing

Prior studies on carbon-filler based, conductive polymer composites have mainly investigated how conductive filler morphology and concentration can tailor a material's electrical conductivity and overlooks the effects of filler alignment due to the difficulty to control and quickly quantify the filler alignment. Here, direct ink write 3D printing's unique ability is utilized to control carbon fiber alignment with a single process parameter, velocity ratio, to instantaneously activate or deactivate the electrical network in composites. Maximum electrical conductivity is achieved by randomly aligning carbon fibers that enhances the chance of direct fiber-to-fiber contact and, thus, activating the electrical network. However, aligning the fibers by increasing the velocity ratio disrupts the electrical network by minimizing fiber-to-fiber contact that resulted in a drastic decrease in electrical conductivity by as much as five orders of magnitude in both short and long carbon fiber composites. With this study, this study demonstrates that electrically conductive or insulative composites can be fabricated sequentially with a single ink. This novel ability to instantaneously control the electrical conductivity of carbon fiber reinforced composites allow to directly embed conductive pathways into designs to 3D print multifunctional composites that are capable of localized heating and self-sensing.     

基于ISSA-Fuzzy-PID算法的无刷直流电机调速控制系统

为了使无刷直流电机(BLDCM)从复杂多变的非线性关系中找出最佳PID参数,提出了一种基于改进麻雀算法(ISSA)优化模糊(fuzzy)控制的调速系统。根据BLDCM工作原理及控制方法在MATLAB平台上搭建仿真模型并加入反向学习策略初始化麻雀种群,形成非线性时变控制系统,并将该优化系统与传统PID以及模糊PID(fuzzy-PID)控制系统进行对比分析。仿真结果表明,基于ISSA-Fuzzy-PID的调速控制系统有较快的动态响应,有效增强了BLDCM转速控制的精度和鲁棒性。     

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.     

基于定子磁场定向的永磁辅助同步磁阻电机无差拍直接转矩控制

针对永磁辅助同步磁阻电机(PMASynRM)直接转矩控制(DTC)转矩脉动较大的问题,研究了基于PMASynRM的无差拍直接转矩控制（DB-DTC）方案。该方案将有效磁链的概念引入PMASynRM,〖JP2〗提取转子位置信息应用于DB-DTC,提高了电机的运行性能;采用了基于定子磁场定向的无差拍转矩控制方法以简化计算和有效抑制转矩脉动。搭建基于定子磁场定向的无差拍直接转矩磁链控制（DB-DTFC）模型并在MATLAB/Simulink软件上进行仿真试验,验证了该算法可以有效减小磁链和转矩脉动,具有较好的动态和稳态性能。     

基于改进代价敏感直推式支持向量机的发电企业 滥用市场力识别

随着现货市场的加速推进,准确地实时识别滥用市场力行为是电力市场违规行为管理的一项关键性任务。将改进的支持向量机与变分不等式求解算法结合,实现了在只有少量发电企业有标签数据情形下仍可以准确实时地识别发电企业滥用市场力行为。首先,结合电力市场实际情况,构造了滥用市场力识别指标体系,并基于电力市场高维数据的特点对数据进行降维。其次,针对发电企业有标签数据占总体数据小部分及数据不平衡的特点,提出了基于改进代价敏感直推式支持向量机的发电企业滥用市场力识别方法。然后,考虑到半监督算法求解时间较长,将求解问题转化为高效的变分不等式求解问题,并使用定制近邻法进行求解。最后,利用UCI数据集、电力市场仿真数据及实际电力市场数据进行试验。结果表明,该识别方法可以将滥用市场力的发电企业快速有效地识别出来。     

墨水直写、喷墨打印和激光直写技术及其在微电子器件中的应用

直写技术是一种新型微加工技术,其加工过程不需模板并可在亚微米至厘米范围实现材料加工成型.墨水直写、喷墨打印和激光直写作为最常用的直写技术,具有强大的二维、三维成型能力和优异的成型精度,可实现金属、陶瓷、聚合物、水凝胶等复杂构型的程序化构筑,被广泛应用于微电子、组织工程、微流控等领域.阐述了这3种直写技术的构型原理和材料选择,重点介绍了其在微电子器件制造中的应用,讨论了当前研究的难点和热点问题,并对其未来发展趋势进行了展望.     

3‐D Printing and Development of Fluoropolymer Based Reactive Inks

Engineering reactive materials is an ever present goal in the energetics community. The desire is to have energetics configured in such a manner that performance is tailored and energy delivery can be targeted. Additive manufacturing (3‐D printing) is one area that could significantly improve our capabilities in this area, if adequate formulations are developed. In this paper, fluoropolymer based reactive inks are developed with micron (mAl) and nanoscale aluminum (nAl) serving, as the fuel at high solids loading (up to 67 wt%) and their viscosity required for 3‐D printing is detailed. For the pen‐type technique and valves used in this work, it is required to have viscosities on the order of 10⁴–10⁵ cP. For printed traces with apparent diameters under <500 μm, the combustion velocities for both micron and nano scale aluminum formulations, are approximately identical: 30 ± 3 versus 32 ± 2 mm s^?1, respectively. Further increasing the apparent diameter is shown to increase the combustion velocity in the case of the nanoscale aluminum formulation by four‐fold over that of the micron scale aluminum formulation, but it plateaus as it approaches an apparent diameter of 2 mm. The results suggest with proper architecture that tailorable combustion rates and energy delivery are feasible.