News on China's scientific and technological development.

SanWenYu

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Scientists from CAS, PKU and Songshan Lake Lab found a way to mass produce millimeter thick single-crystal copper plates. The same method can be used for other metals, too.

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Production of single-crystal Cu plates by electrodeposition on high-index Cu foils​


科学家利用电镀方法实现毫米级厚度单晶铜片制备

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近日,中国科学院院士王恩哥、松山湖材料实验室/北京大学教授刘开辉与合作者突破电镀单晶铜片技术,首次利用电镀的方法实现毫米级厚度单晶铜片的制备,并提出“衬底表面原子台阶诱导单晶生长”的外延电镀新机制。相关研究在线发表于《科学通报》。

单晶铜材料内部不存在晶界且缺陷密度极低,在电力传输、高频通讯、金属靶材等领域具有非常广阔的应用和市场前景。然而,当前商业化的单晶铜材料是通过切割块体单晶铸锭获得,成本昂贵且尺寸小,无法满足其规模化应用要求。

电镀技术由于其简单、易操作、低成本、可规模化等优势已经成为现代金属行业的标准加工技术。但是在传统外延电镀过程中,随镀层厚度增加,缺陷数量的积累会导致孪晶出现,并进一步导致镀层结构向多晶转变,最终只能获得几微米厚的单晶薄膜。

基于表面调控材料生长动力学的学术思想,研究人员提出一种“原子台阶引导原子精准排列”的调控策略,利用简单、易操作且低成本的电镀技术,实现了厚度可达毫米量级的单晶铜片的制备。

该研究利用高指数单晶铜衬底表面原子台阶引导铜原子的精准排列,成功解决了传统外延电镀过程中镀层缺陷积累导致结构向多晶转变而无法获得厚单晶镀层的问题,实现了毫米级厚单晶铜片的外延电镀制备。该方法的提出,为金属单晶体材料的工业化应用提供了一种简单、有效、易控制的规模化制备新方法。

该成果首次利用电镀的方法实现毫米级厚度单晶铜片的制备,为单晶铜材料的规模化生产提供了新的方法,有望推动单晶铜在高速电子、大功率电气领域的高端应用。其提出的“衬底表面原子台阶诱导金属单晶生长”电镀机理与技术,有望推广到其他金属、合金材料的单晶制造,推动工业、国防、经济等各领域金属材料性能升级。
 

SanWenYu

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Optically and radiofrequency-transparent metadevices based on quasi-one-dimensional surface plasmon polariton structures​

Abstract​

Transparent metadevices could equip electronic systems with unique functionalities such as anti-interference and stealth capabilities. However, optically transparent devices currently rely on transparent conductive materials, which have low optical transmittance, low operating efficiency and an inability to achieve radiofrequency transparency. Here, we show that metadevices based on quasi-one-dimensional surface plasmon polariton structures can offer optical and radiofrequency transparency. The structures are composed of subwavelength unit cells created from fine metallic lines printed on a flexible and transparent substrate. The approach can be used to create arbitrarily shaped waveguides with topological robustness for transmission applications, and converters for changing surface plasmon polariton waves into space waves for radiation applications. To illustrate the potential of the technology, we use the microwave metadevices to construct a wireless communication scheme for image transfer.

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近日,西电电子工程学院天线与微波技术重点实验室吴边教授团队在准一维表面等离激元光学与射频双透明电磁器件方面取得突破性进展,研究成果以《Optically and radiofrequency-transparent metadevices based on quasi-one-dimensional surface plasmon polariton structures》”为题发表在《自然•电子》(Nature Electronics)。西电祖浩然博士为论文第一作者,吴边教授和东南大学崔铁军院士为论文通讯作者,西电苏涛教授、刘英教授也参与了该工作,西安电子科技大学为论文第一单位。

研究团队创新性地提出了准一维表面等离激元(quasi-1D SPPs)的概念,利用周期性排列的准一维微金属线构建表面等离激元结构,可实现对表面波的高局域与强束缚,对电磁波具有任意拓扑传输与高效辐射转换等灵活调控能力。相比传统结构,金属占比降低两个数量级以上,同时具有极佳的光学透明与射频透明特性,在可见光与典型射频频段透过率均达到90%以上。准一维表面等离激元能够实现任意拓扑结构的传输并保持电磁能量的低逸散,还能对场束缚性进行有效操控,实现高束缚导行波向低束缚空间波的高效转换。因此,准一维表面等离激元结构有望构建一系列传输型和辐射型透明电磁器件,其极佳的透光特性使其在自然环境下几乎不可见。

研究团队搭建了准一维表面等离激元无线图像传输系统,并与传统ITO无线图像传输系统进行了数据传输对比实验。以典型的载波频率直接传输像素为534 pt × 490 pt的图像(西安电子科技大学校徽),对图像进行数字化处理,然后由信号处理模块将数据转换为射频信号,再将射频信号送入准一维SPPs或ITO收发射频终端,对比了无障碍与自身作为障碍物的图像传输质量。由于准一维SPPs优异的光学透明、射频透明、高辐射效率等优势,在无线图像传输中获得了更好的图像传输质量,而在相同极端条件下,传统ITO收发终端在图像传输中发生了大量的数据丢失与图像畸变。

该工作首次提出了准一维表面等离激元的概念,揭示了准一维表面等离激元更显著的场束缚与场增强效应,验证了任意拓扑结构传输与空间辐射转换功能,以及极端条件下高质量无线图像传输能力。该技术突破了透明电磁器件的光学与射频透过率限制,为高透光与射频隐身无线传输系统提供了新思路,有望应用于5G/6G移动通讯、智能家居、物联网与车联网等高集成隐蔽化通信领域。
 

luminary

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Researchers from Inha University in China have created a new grid-forming inverter concept based on the artificial bee colony (ABC) algorithm, which is an optimization algorithm based on the intelligent behavior of a honey bee swarm.

This algorithm mimics the food-foraging behavior of honey bee colonies when searching for nectar. It optimizes numerical problems by converting them to the problem of finding the best parameter to minimize an objective function. The algorithm moves towards better solutions, while abandoning poor solutions.

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create adjustable voltage and frequency and can operate microgrids without conventional synchronous power generators. They can also act as primary mechanisms to improve grid synchronization, especially during low-inertia operating conditions.

The group said the proposed inverter design can work optimally on both grid-connected and islanding conditions. It combines these two different control strategies by using a Fractional Order based Proportional–Integral (FOPI) controller – a way of adding additional parameters to the algorithm.

The new inverter design is presented in the paper “
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,” published in Energy Reports.
 

GodRektsNoobs

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Researchers from Inha University in China have created a new grid-forming inverter concept based on the artificial bee colony (ABC) algorithm, which is an optimization algorithm based on the intelligent behavior of a honey bee swarm.

This algorithm mimics the food-foraging behavior of honey bee colonies when searching for nectar. It optimizes numerical problems by converting them to the problem of finding the best parameter to minimize an objective function. The algorithm moves towards better solutions, while abandoning poor solutions.

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create adjustable voltage and frequency and can operate microgrids without conventional synchronous power generators. They can also act as primary mechanisms to improve grid synchronization, especially during low-inertia operating conditions.

The group said the proposed inverter design can work optimally on both grid-connected and islanding conditions. It combines these two different control strategies by using a Fractional Order based Proportional–Integral (FOPI) controller – a way of adding additional parameters to the algorithm.

The new inverter design is presented in the paper “
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,” published in Energy Reports.
Isn't Inha University in Seoul? What does this have to do with Chinese scientific advances?
 

siegecrossbow

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The world's largest and most powerful windmill was installed. The manufacturer is Xinjiang Goldwind. Rated at 16 MW. The expected annual production is 66 GWh. Its diameter is 260 meters. It has already survived a typhoon during the installation.
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View attachment 116346

Size and power means nothing if it is made from slave labor.
 

sunnymaxi

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Testing pesticides with smartphones? Chinese scientists have developed and integrated a fluorescent paper-based sensor into a smartphone-based color recognition app that can achieve real-time monitoring of pesticide residues in water and on fruits and vegetables..

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