Dielectric Properties in the Microwave Range of K<Subscript>0.5</Subscript>Na<Subscript>0.5</Subscript>NbO<Subscript>3</Subscript> Ceramics

Dielectric properties of a potassium sodium niobate (KNN) system in the microwave range up to GHz have rarely been studied. Since K_0.5Na_0.5NbO₃ is the most common and typical type of KNN materials, non-doped K_0.5Na_0.5 NbO₃ ceramics were synthesized at different temperatures (1080°C, 1090°C, 1100°C, and 1110°C) by a traditional solid reaction method for further characterization and analysis. The ceramics were in perovskite phase with orthorhombic symmetry. A small quantity of second phase was found in the 1110°C sintered specimen, which resulted from the volatilization of alkali oxides as the temperature increased. The complex permittivity was measured for the first time in the microwave range (8.2–12.4 GHz) and in the temperature range from 100°C to 220°C, and the effects of annealing on the dielectric properties were studied. The results indicate that the complex permittivity of KNN ceramics over the microwave range increases mainly due to high bulk density and the additional dielectric contributions of oxygen vacancies at high temperature.     

Novel high PSRR high-order temperature-compensated subthreshold MOS bandgap reference

Novel high power supply rejection ratio (PSRR) high-order temperature-compensated subthreshold metal-oxide-semiconductor (MOS) bandgap reference (BGR) is proposed in Semiconductor Manufacturing International Corporation (SMIC) 0.13 μm complementary MOS (CMOS) process. By adopting subthreshold MOS field-effect transistors (MOSFETs) and the piecewise-curvature temperature-compensated technique, the output reference voltage's temperature performance of the subthreshold MOS BGR is effectively improved. The subthreshold MOS BGR achieves high PSRR performance by adopting the technique of pre-regulator. Simulation results show that the temperature coefficient (TC) of the subthreshold MOS BGR is 1.38×10^?6/°C when temperature is changed from ?40 °C to 125 °C with a power supply voltage of 1.2 V. The subthreshold MOS BGR achieves the PSRR of ?104.54 dB, ?104.54 dB, ?104.5 dB, ?101.82 dB and ?79.92 dB at 10 Hz, 100 Hz, 1 kHz, 10 kHz and 100 kHz respectively.     

10Gb/s突发模式时钟数据恢复电路设计

突发模式的时钟数据恢复是10G EPON系统的关键技术之一。本文介绍了一种基于XNOR/XOR门的振荡器,分析了其工作原理与性能,以此为基础设计了半速率突发时钟恢复电路。设计采用SMIC 0.13?m CMOS工艺进行了流片验证,芯片面积为675?m ? 625?m。测试结果表明,该电路可以即时的实现10Gbit/s的突发数据恢复,恢复出的时钟数据符合IEEE 802.3av标准,锁定时间小于5bit。     

采用尺度不变特征和区域选择的图像配准方法

提出了一种改进的尺度不变特征点的图像配准方法。该方法在SURF算法的基础上使用图像的熵来对匹配图像作特征检测区域选择,建立特征点筛选机制来从初步的特征检测中得到最显著的特征点,以控制特征点的数目来减少后继的计算量和算法性能。同时改进了SURF的特征描述方法的计算过程,提出了一种改进的特征描述方法。实验表明,该方法在提高算法性能的同时,明显改进了特征点的匹配率。     

采用改进词袋模型的空中目标自动分类

为了解决飞机、直升机、导弹等3类空中目标图像的自动分类问题,提出了一种基于改进词袋模型的空中目标识别方法。首先采集3类多个型号的空中目标灰度图像并分割提取出目标,接着利用稠密采样方法进行SIFT特征提取,然后用模糊C均值聚类方法,对空中目标图像的SIFT特征进行聚类,得到大量空中目标图像的视觉单词。最后用视觉单词直方图训练支持向量机分类器,完成空中目标的自动分类。仿真实验表明,文中提出的算法能准确区分空中目标类别,性能优于传统的采用K均值聚类的词袋模型,且优于仿射矩。     

Efficient distributed traffic offloading algorithm based on SDN architecture

For addressing the problem of mobile data traffic offloading,network service cost minimization problem model was proposed,which considered the cost of base stations and the consumption of access points under the SDN architecture.Due to the defects of convergence speed and privacy security in the traffic offloading algorithm based on dual decomposition,the traffic offloading algorithm based on proximal Jacobian ADMM was proposed and an implementation scheme to ensure the privacy and security was designed.Meanwhile,the simulation results show that the algorithm based on the proximal Jacobian ADMM is superior to the dual decomposition algorithm in terms of convergence speed.     

All‐Fiber Structured Electronic Skin with High Elasticity and Breathability

With the rapid advancement in artificial intelligence, wearable electronic skins have attracted substantial attention. However, the fabrication of such devices with high elasticity and breathability is still a challenge and highly desired. Here, a route to develop an all‐fiber structured electronic skin with a scalable electrospinning fabrication technique is reported. The fabricated electronic skin is demonstrated to exhibit high pressure sensing with a sensitivity of 0.18 V kPa^?1 in the detection range of 0–175 kPa. This wearable device could maintain prominent sensing performance and mechanical stability in the presence of large deformation, even when the elastic deformation is up to 50%. The electronic skin is easily conformable on different desired objects for real‐time spatial mapping and long‐term tactile sensing. Besides, it possesses high gas permeability with a water vapor transmittance rate of 10.26 kg m^?2 d^?1. More importantly, the electronic skin is capable of working in a self‐powered manner and even serves as a reliable power source to effectively drive small electronics. Possessing several compelling features, such as high sensitivity, high elasticity, high breathability as well as being self‐powered and scalable in fabrication, the presented device paves a pathway for smart electronic skins.     

Synergistic Coassembly of Highly Wettable and Uniform Hole‐Extraction Monolayers for Scaling‐up Perovskite Solar Cells

All organic charge‐transporting layer (CTL)‐featured perovskite solar cells (PSCs) exhibit distinct advantages, but their scaling‐up remains a great challenge because the organic CTLs underneath the perovskite are too thin to achieve large‐area homogeneous layers by spin‐coating, and their hydrophobic nature further hinders the solution‐based fabrication of perovskite layer. Here, an unprecedented anchoring‐based coassembly (ACA) strategy is reported that involves a synergistic coadsorption of a hydrophilic ammonium salt CA‐Br with hole‐transporting triphenylamine derivatives to acquire scalable and wettable organic hole‐extraction monolayers for p–i–n structured PSCs. The ACA route not only enables ultrathin organic CTLs with high uniformity but also eliminates the nonwetting problem to facilitate large‐area perovskite films with 100% coverage. Moreover, incorporation of CA‐Br in the ACA strategy can distinctly guarantee a high quality of electronic connection via the cations' vacancy passivation. Consequently, a high power‐conversion‐efficiency (PCE) of 17.49% is achieved for p–i–n structured PSCs (1.02 cm²), and a module with an aperture area of 36 cm² shows PCE of 12.67%, one of the best scaling‐up results among all‐organic CTL‐based PSCs. This work demonstrates that the ACA strategy can be a promising route to large‐area uniform interfacial layers as well as scaling‐up of perovskite solar cells.     

2D/2D 1T‐MoS2/Ti3C2 MXene Heterostructure with Excellent Supercapacitor Performance

2D/2D heterostructures can combine the collective advantages of each 2D material and even show improved properties from synergistic effects. 2D Transition metal carbide Ti₃C₂ MXene and 2D 1T‐MoS₂ have emerged as attractive prototypes in electrochemistry due to their rich properties. Construction of these two 2D materials, as well as investigation about synergistic effects, is absent due to the instability of 1T‐MoS₂. Here, 3D interconnected networks of 1T‐MoS₂/Ti₃C₂ MXene heterostructure are constructed by magneto‐hydrothermal synthesis, and the electrochemical storage mechanisms are investigated. Improved extra capacitance is observed due to enlarged ion storage space from a synergistically interplayed effect in 3D interconnected networks. Outstanding rate performance is realized because of ultrafast electron transport originating from Ti₃C₂ MXene. This work provides an archetype to realize excellent electrochemical properties in 2D/2D heterostructures.     

Unprecedented Improvement of Single Li‐Ion Conductive Solid Polymer Electrolyte Through Salt Additive

Solid‐state lithium metal (Li°) batteries (SSLMBs) are believed to be the most promising technologies to tackle the safety concerns and the insufficient energy density encountered in conventional Li‐ion batteries. Solid polymer electrolytes (SPEs) inherently own good processability and flexibility, enabling large‐scale preparation of SSLMBs. To minimize the growth of Li° dendrites and cell polarization in SPE‐based SSLMBs, an additive‐containing single Li‐ion conductive SPE is reported. The characterization results show that a small dose of electrolyte additive (2 wt%) substantially increases the ionic conductivity of single Li‐ion conductive SPEs as well as the interfacial compatibility between electrode and SPE, allowing the cycling of SPE‐based cells with good electrochemical performance. This work may provide a paradigm shift on the design of highly cationic conductive electrolytes, which are essential for developing safe and high‐performance rechargeable batteries.