“Regioselective Deposition” Method to Pattern Silver Electrodes Facilely and Efficiently with High Resolution: Towards All‐Solution‐Processed,High‐Performance,Bottom‐Contacted,Flexible, Polymer‐Based Electronics

“Regioselectivity deposition” method is developed to pattern silver electrodes facilely and efficiently by solution‐process with high resolution (down to 2 μm) on different substrates in A4 paper size. With the help of this method, large‐area, flexible, high‐performance polymer field‐effect transistors based on the silver electrodes and polyimide insulator are fabricated with bottom‐contact configuration by all‐solution processes. The polymer devices exhibit high performance with average field‐effect mobility over 1.0 cm² V^?1 s^?1 (the highest mobility up to 1.5 cm² V^?1 s^?1) and excellent environmental stability and flexibility, indicating the cost effectiveness of this method for practical applications in organic electronics.     

Hierarchical Graphene–Carbon Fiber Composite Paper as a Flexible Lateral Heat Spreader

As a low dimensional crystal, graphene attracts great attention as heat dissipation material due to its unique thermal transfer property exceeding the limit of bulk graphite. In this contribution, flexible graphene–carbon fiber composite paper is fabricated by depositing graphene oxide into the carbon fiber precursor followed by carbonization. In this full‐carbon architecture, scaffold of one‐dimensional carbon fiber is employed as the structural component to reinforce the mechanical strength, while the hierarchically arranged two‐dimensional graphene in the framework provides a convenient pathway for in‐plane acoustic phonon transmission. The as‐obtained hierarchical carbon/carbon composite paper possesses ultra‐high in‐plane thermal conductivity of 977 W m^?1 K^?1 and favorable tensile strength of 15.3 MPa. The combined mechanical and thermal performances make the material highly desirable as lateral heat spreader for next‐generation commercial portable electronics.     

Hierarchically Structured Magnetic Nanoconstructs with Enhanced Relaxivity and Cooperative Tumor Accumulation

Iron oxide nanoparticles are formidable multifunctional systems capable of contrast enhancement in magnetic resonance imaging, guidance under remote fields, heat generation, and biodegradation. Yet, this potential is underutilized in that each function manifests at different nanoparticle sizes. Here, sub‐micrometer discoidal magnetic nanoconstructs are realized by confining 5 nm ultra‐small super‐paramagnetic iron oxide nanoparticles (USPIOs) within two different mesoporous structures, made out of silicon and polymers. These nanoconstructs exhibit transversal relaxivities up to ≈10 times (r ₂ ≈ 835 mm ^?1 s^?1) higher than conventional USPIOs and, under external magnetic fields, collectively cooperate to amplify tumor accumulation. The boost in r ₂ relaxivity arises from the formation of mesoscopic USPIO clusters within the porous matrix, inducing a local reduction in water molecule mobility as demonstrated via molecular dynamics simulations. The cooperative accumulation under static magnetic field derives from the large amount of iron that can be loaded per nanoconstuct (up to ≈65 fg) and the consequential generation of significant inter‐particle magnetic dipole interactions. In tumor bearing mice, the silicon‐based nanoconstructs provide MRI contrast enhancement at much smaller doses of iron (≈0.5 mg of Fe kg^?1 animal) as compared to current practice.     

基于差分隐私的轨迹隐私保护方法

针对现有的轨迹隐私保护模型大多难以抵御复杂背景知识攻击的问题,本文提出了一种基于差分隐私的轨迹隐私保护方法.首先结合地理不可区分机制对原始轨迹数据添加半径受限的拉普拉斯噪音;其次构造数据映射模型将原始数据和噪音数据映射到新的发布位置,使攻击者无法获取真实轨迹数据;接着应用最优数据映射函数发布最优的轨迹位置以提高发布数据...     

基于集成学习的全双工中继系统安全中继选择方案研究

当处于无线信道状态信息(Channel State Information,CSI)快速变化或者多跳中继等应用场景时,利用集成学习算法解决安全中继选择问题能减少实时处理时延及计算复杂度.将合法信道和窃听信道的CSI作为训练模型输入,使系统安全容量到达最大的中继节点索引作为输出,把全双工中继系统安全中继选择问题转化为一个多类分类问题,并利用随机森林(Random Forest,RF)算法求解.安全中继选择方案的实现分为数据准备、模型建立和结果预测三个阶段.在数据准备阶段,由于RF算法要求训练模型输入为离散值,给出了均匀量化和非均匀量化两种特征提取法将CSI转化为离散值.最后,通过仿真实验验证方案性能.     

利用PO修正MM-UTD计算机载波导缝隙天线阵的方向图

针对物理光学方法(PO)中Ludwig算法数值发散的问题,提出了解决方案。以复矢量场为接口,利用PO修正了MOM-UTD算法,并应用于机载波导缝隙天线阵方向图的计算。采用MOM分析天线自身的特性,UTD分析飞机形状简单的大型部件对天线方向图畸变的影响,PO分析机头等形状复杂的部件的影响。计算结果表明,此3种方法的结合算法适用于计算靠近机头的机载天线的方向图。     

一种用于单片UHF RFID阅读器中的低相位噪声LC VCO设计

介绍了一种适用于UHF RFID(Radio Frequency Identification)阅读器的低相位噪声压控振荡器(VCO)电路.通过在传统的VCO电路中加入抑制电源噪声的regulator并在共模端加入平衡滤波电路对尾电流源的二次谐波分量进行抑制来降低1/f3区域的相位噪声,同时选取合适的电感值及其Q值使得VCO在1/f2区域也能获得较佳的相位噪声性能.同时,文中给出了本设计中使用的低噪声基准源电路.整个电路采用UMC0.18 μm MM/RF CMOS工艺实现,仿真与测试结果显示所提出的VCO结构和传统VCO相比几乎在所有区域内对相噪声均有5 dB的改善.本设计使用的电源电压为3.3 V,VCO中心频率为1.8 GHz,调谐范围约为11%,频偏1MHz处相位噪声约为-127 dBc/Hz,总电流约为7.2 mA.     

一种基于DSP的电子送经卷取控制系统

研制了一种电子送经和电子卷取系统.本系统以DSP(TMS320LF2407)为主控制器,采用交流伺服运动控制技术,实现了纬密的精确控制与经纱的恒张力控制,保证织物质量,满足工业生产要求.     

Dopant Diffusion Equilibrium Overcoming Impurity Loss of Doped QDs for Multimode Anti-Counterfeiting and Encryption

High ion diffusivity of Cu⁺ dopants accelerates outdiffusion in quantum dots (QDs) at high temperatures. This kind of self-purification gives rise to a sharp decrease in dopant photoluminescence (PL) intensity. Herein, a dopant diffusion equilibrium strategy is developed by introducing extra Cu⁺ in the epitaxial growth process. By preventing the loss of dopant Cu⁺, both the decrease of dopant PL and increase of band-edge PL intensity are successfully suppressed. The coexistence of visible and invisible near-infrared (NIR) PL bands for Cu-doped CdSe@CdS QDs demonstrates their novel multimode anti-counterfeiting/encryption potential. Via printing by combined using of intrinsic and doped QD “inks” with visible and invisible NIR emissions, respectively, the bulk-sized patterns, texts, and numerals can achieve visible–invisible PL synergetic confidential information multimode anti-counterfeiting and encryption.     

Moisture-Induced Reversible Phase Conversion of Cesium Copper Iodine Nanocrystals Enables Advanced Anti-Counterfeiting

Hydrochromic materials have attracted widespread attention in the fields of anti-counterfeiting because of their ability of the reversible light absorption and/or emission properties in response to water. Here, for the first it is demonstrated that the ternary copper halides Cs₃Cu₂I₅ nanocrystals (NCs) possess excellent hydrochromic properties. The prepared Cs₃Cu₂I₅ NCs films can dynamically extract and insert CsI by exposing/removing water to realize the reversible conversion between blue-emissive Cs₃Cu₂I₅ and yellow-emissive CsCu₂I₃. Interestingly, polymethyl methacrylate (PMMA) coated Cs₃Cu₂I₅ can effectively avoid the extraction of CsI and maintain long-term stability in the water. Further, the hydrochromic Cs₃Cu₂I₅ and water-resistant Cs₃Cu₂I₅@PMMA are used as the inks to synergistically act on anti-counterfeiting information to achieve multiple encryption effects, which can clearly identify and authenticate the effective information after moisture decryption. Importantly, the pattern can be re-encrypted to the invalid pattern after water evaporation. In addition, the anti-counterfeiting pattern has excellent stability during repeated encryption/decryption conversion cycles, which can not only balance the accessibility of anti-counterfeiting information but also effectively improve the security of information. This new discovery may not only deepen the understanding of Cs₃Cu₂I₅ but also provide new options for the design of hydrochromic materials for anti-counterfeiting information.