测量散射参数的交互换位双信号方法及其应用

叙述了外内向功率波复数比的测量方法,给出了散射参数测量的交互换位双信号测量线方法。用此方法测量了双栅ＧａＡｓＭＥＳＦＥＴ适用散射参数,并用它设计Ｓ波段混合集成双栅ＧａＡｓＭＥＳＦＥＴ可控增益放大器。测试结果与设计吻合。     

Microstructure near 2 1 1 phase in high Jc MTG YBCO

The microstructures of MTG YBCO near 2 1 1 phase clusters inside the sample are studied by means of transmission electron microscopy. The results indicate that crystal defects around 2 1 1 phase are closely related to the distance between 2 1 1 particles (d _{2 1 1}). With the decrease ofd _{2 1 1}, the twin spacing increases. Simultaneously, the thickness of the twin boundary decreases. Whend _{2 1 1} is less than 0.51 m, there are almost no defects between 2 1 1 particles. According to the established crack model, the mechanism of the appearance of a defect-free-zone is explained. The relationship betweend _{2 1 1} and Jc is discussed in this paper.     

335 GHz非平衡式肖特基二极管三倍频器

基于混合集成的方式,采用对称锥形渐变线匹配结构设计了335 GHz非平衡式三倍频器。在保证单模传输的条件下,该匹配结构不仅能够固定二极管位置,而且可以增大匹配效果,解决了高频段倍频器3 dB带宽较窄的问题。实测结果表明,该倍频器在330~356 GHz频率范围内输出功率均大于5 mW。驱动功率为220 mW时,有最高输出功率11.2 mW,由它作为核心器件组成的固态太赫兹本振源,能够驱动超外差接收机中670 GHz二次谐波混频器。     

基于sMLD特征的远红外航空图像配准算法

航空场景下的远红外图像迫切需要准确、鲁棒、快速的特征描述与自动配准方法。由于已有的多重线型描述符MLD特征存在“特征孤岛”和“尺度变换受限”的问题,因此针对远红外航空图像的配准问题,文章提出了一种聚合特征点以及线型描述符分段统计的特征描述方式,即sMLD特征。结合sMLD特征相互连接构成网状拓扑结构的特性,还提出了一种由粗到细的分支加速匹配算法RF-BA。其中,RF-BA粗匹配充分利用拓扑图的结构,通过局部寻优算法提高匹配的效率。RF-BA精匹配利用最小外接凸四边形原则和GMS校验原则,提升配准精度。实验结果表明,与已有的几种代表性配准方法相比,所提方法在配准精度和时间开销方面均具有更好的性能。     

基于TRNSYS的气候变化下“冷-热-电”联供系统运行优化

气候变化导致的极端天气给建筑负荷和冷、热、电联供(combined cooling heating and power, CCHP)系统供能策略带来很大的影响,以上海市某医院为主要研究对象,采用PRECIS软件预测该地区2025至2100年的温度变化,利用TRNSYS软件搭建医院能耗模型计算气候变化影响下的全年逐时负荷,构建了考虑负荷变化影响的“冷-热-电”联供系统运行优化模型,最终生成适应气候变化的供能系统运行方案。负荷预测结果表明,极端高温现象导致建筑的冷、热负荷呈现波动变化趋势,可能造成供需失衡,即夏季高温制冷不足和冬天暖冬供暖过剩的问题。与传统优化模型相比,该模型生成的系统协同运行方案可以增强用户体验,实现降本增效。     

面向方向图保形的共口径基站天线去耦技术

为了节省基站天线所占空间资源,降低其运营成本,现代移动通信需要将多个天线阵列紧密地排列在一起,构成多频共口径基站天线。多天线的紧密排列势必造成天线间强烈的耦合,不仅使得天线阻抗失配、隔离度变差,同时也造成辐射方向图的严重变形。因此,近年来多频共口径基站天线的去耦成为工业界和学术界研究的热点,早期的去耦技术主要是面向改善天线的阻抗匹配和隔离度,而对面向方向图保形的去耦技术研究相对较少。文章在简要介绍面向方向图保形的基站天线去耦技术的研究现状的基础上,重点阐述了褚庆昕教授天线射频团队基于感应电流抵消、耦合场抵消和辐射阻断等原理,提出的几种新型的去耦技术。这些技术不仅可以有效地改善基站天线的阻抗匹配和隔离,更重要的是很好地实现了天线方向图保形。仿真和测试结果验证了原理的正确性和设计的可行性。一些技术已被用于5G基站天线产品。     

Electrochemically Induced Crystalline-to-Amorphous Transition of Dinuclear Polyoxovanadate for High-Rate Lithium-Ion Batteries

Polyoxometalates are intriguing high-capacity anode materials for alkali-metal-ion storage due to their multi-electron redox capabilities and flexible structure. However, their poor electrical conductivity and high working voltage severely restrict their practical application. Herein, the dinuclear polyoxovanadate Sr₂V₂O₇·H₂O with unusually high electrical conductivity is reported as a promising anode material for lithium-ion batteries. During the initial lithiation process, the Sr₂V₂O₇·H₂O anode experiences an electrochemically induced crystalline-to-amorphous transition. The resulting amorphous structure provides high redox activity and fast reaction kinetics via reversible V^4.9+/V^2.8+ redox couple through the intercalation mechanism. Furthermore, when coupled with the LiFePO₄ cathode, the strong V O bonds of the amorphous anode provide excellent structural stability, with the full-cell capable of performing >12 000 cycles with a capacity retention of 72%. Another advantage of Sr_2xV₂O_7-δ·yH₂O (0.5 ≤ x ≤ 1.0) is its composition adjustability, which enables delicately regulating the Sr vacancy content without destroying the structure. The defect Sr_2xV₂O_7-δ·yH₂O (x = 0.5) electrodes show significantly improved specific capacity and rate capability without sacrificing other key properties, delivering a high specific capacity of 479 mAh g^-1 at 0.1 mA cm^-2 and 41.9% of its capacity in 2 min. Overall, the preliminary study points the way forward for the facile preparation of high-quality polyoxometalates for advanced energy storage applications and beyond.     

Solution-Mediated Hybrid FAPbI3 Perovskite Quantum Dots for Over 15% Efficient Solar Cell

Organic–inorganic formamidinium lead triiodide (FAPbI₃) hybrid perovskite quantum dot (QD) is of great interest to photovoltaic (PV) community due to its narrow band gap, higher ambient stability, and long carrier lifetime. However, the surface ligand management of FAPbI₃ QD is still a key hurdle that impedes the design of high-efficiency solar cells. Herein, this study first develops a solution-mediated ligand exchange (SMLE) for preparing FAPbI₃ QD film with enhanced electronic coupling. By dissolving optimal methylammonium iodide (MAI) into antisolvent to treat the FAPbI₃ QD solution, the SMLE can not only effectively replace the long-chain ligands, but also passivate the A- and X-site vacancies. By combining experimental and theoretical results, this study demonstrates that the SMLE engineered FAPbI₃ QD exhibits lower defect density, which is beneficial for fabricating high-quality QD arrays with desired morphology and carrier transport. Consequently, the SMLE FAPbI₃ QD based solar cell outputs a champion efficiency of 15.10% together with improved long-term ambient storage stability, which is currently the highest reported value for hybrid perovskite QD solar cells. These results would provide new design principle of hybrid perovskite QDs toward high-performance optoelectronic application.     

Sufficient Utilization of Mn2+/Mn3+/Mn4+ Redox in NASICON Phosphate Cathodes towards High-Energy Na-Ions Batteries

Na superionic conductor of Na₃MnTi(PO₄)₃ only containing high earth-abundance elements is regarded as one of the most promising cathodes for the applicable Na-ion batteries due to its desirable cycling stability and high safety. However, the voltage hysteresis caused by Mn²⁺ ions resided in Na⁺ vacancies has led to significant capacity loss associated with Mn reaction centers between 2.5–4.2 V. Herein, the sodium excess strategy based on charge compensation is applied to suppress the undesirable voltage hysteresis, thereby achieving sufficient utilization of the Mn²⁺/Mn³⁺ and Mn³⁺/Mn⁴⁺ redox couples. These findings indicate that the sodium excess Na_3.5MnTi_0.5Ti_0.5(PO₄)₃ cathode with Ti⁴⁺ reduction has a lowest Mn²⁺ occupation on the Na⁺ vacancies in its initial composition, which can improve the kinetics properties, finally contributing to a suppressed voltage hysteresis. Based on these findings, it is further applied the sodium excess route on a Mn-richer phosphate cathode, which enables the suppressed voltage hysteresis and more reversible capacity. Consequently, this developed Na_3.6Mn_1.15Ti_0.85(PO₄)₃ cathode achieved a high energy density over 380 Wh kg⁻¹ (based on active substance mass of cathode) in full-cell configurations, which is not only superior to most of the phosphate cathodes, but also delivers more application potential than the typical oxides cathodes for Na-ion batteries.     

An Artificial Motion and Tactile Receptor Constructed by Hyperelastic Double Physically Cross-Linked Silk Fibroin Ionoelastomer

Ionotronic artificial motion and tactile receptor (i-AMTR) is essential to realize an interactive human-machine interface. However, an i-AMTR that effectively mimics the composition, structure, mechanics, and multi-functionality of human skin, called humanoid i-AMTR, is yet to be developed. To bridge this technological gap, this study proposes a strategy that combines molecular structure design and function integration to construct a humanoid i-AMTR. Herein, a silk fibroin ionoelastomer (SFIE) with double cross-linked molecular structure is designed to mimic the composition and structure of human skin, thereby resolving the conflict of stretchability, softness, and resilience, suffered by many previously reported ionotronics. Functionally, electromechanical sensing and triboelectricity-based tactile perception are integrated into SFIE, to enable simultaneous perception of both motion and tactile inputs. By further leveraging the machine learning and Internet of Things (IoT) techniques, the proposed SFIE-based humanoid i-AMTR precisely senses the movement of human body and accurately sortball objects made of different materials. Notably, the success rate for 610 sorting tests reaches as high as 92.3%. These promising results essentially demonstrate a massive potential of humanoid i-AMTR in the fields of sorting robots, rehabilitation medicine, and augmented reality.