Intrinsically Flexible and Aging Resistant Fluorene-Based Rod-Coil Copolymer for Bendable Deep-Blue PLEDs

In the field of flexible light-emitting display, goal-oriented intelligent molecular design is used to control various behaviors of molecules, which provides potential for the development of flexible light-emitting conjugated polymers (LCPs). The introduction of non-conjugated units into polymer molecules is a key prerequisite for realizing the intrinsic flexibility, but its easy interchain slip will also lead to the formation of interchain excited states, which is detrimental to the efficiency of light-emitting diodes. Herein, two kinds of fluorene-based rod-coil copolymer with stable deep blue emission characteristics is presented and with Commission Internationale de L'Eclairage (CIE) coordinates of (0.18, 0.14) and (0.15, 0.09), respectively. Surprisingly, the copolymer films show efficient blue emission even at 100% tension. Meanwhile, the rod-coil copolymer possesses better aging resistance compared to rigid π-conjugated counterparts. Finally, both rigid and flexible light-emitting diodes based on rod-coil copolymer exhibit stable deep blue emission, and the G2-based PLED with CIE coordinates of (0.16, 0.08), which approach National Television System Committee standard blue specification. These results confirm the validity of rod-coil copolymer design strategy in constructing inherently flexible polymers with deep blue emission, which have great application potential in flexible PLEDs.     

基于精化的TrustZone多安全分区建模与形式化验证

TrustZone作为ARM处理器上的可信执行环境技术,为设备上安全敏感的程序和数据提供一个隔离的独立执行环境.然而,可信操作系统与所有可信应用运行在同一个可信环境中,任意组件上的漏洞被利用都会波及系统中的其他组件.虽然ARM提出了S-EL2虚拟化技术,支持在安全世界建立多个隔离分区来缓解这个问题,但实际分区管理器中仍可能存在分区间信息泄漏等安全威胁.当前的分区管理器设计及实现缺乏严格的数学证明来保证隔离分区的安全性.详细研究了ARM TrustZone多隔离分区架构,提出一种基于精化的TrustZone多安全分区建模与安全性分析方法,并基于定理证明器Isabelle/HOL完成了分区管理器的建模和形式化验证.首先,基于逐层精化的方法构建了多安全分区模型RMTEE,使用抽象状态机描述系统运行过程和安全策略要求,建立多安全分区的抽象模型并实例化实现分区管理器的具体模型,遵循FF-A规范在具体模型中实现了事件规约;其次,针对现有分区管理器设计无法满足信息流安全性验证的不足,设计了基于DAC的分区间通信访问控制,并将其应用到TrustZone安全分区管理器的建模与验证中;再次,证明了具体模型...     

航天器姿轨控制研究综述:微分几何控制方法

作为空间任务顺利执行的关键技术,航天器姿态和轨道控制具有典型的非线性特征,其本质是对在矩阵李群SO (3)和SE (3)上演化的动态系统进行控制.与传统的参数化模型相比,航天器的矩阵李群模型对姿轨表征具有全局性、非奇异性和唯一性等固有优势,为控制设计提供了数学简洁、精度高、适用性好的模型基础.因此,近年来基于微分几何控制方法直接对其进行系统分析和控制设计的研究逐渐兴起,取得了一系列突破性成果.鉴于此,首先,系统地论述微分几何控制理论在航天器姿轨控制应用中的研究现状和进展;然后,面向空间任务的实际需要,分别对基于矩阵李群模型的单体航天器姿态控制、姿轨耦合控制、网络化航天器集群姿轨协同控制3个技术方向加以讨论;最后,对上述研究领域中存在的难题和挑战进行总结,并对未来发展方向进行展望.     

低视点下遮挡自适应感知的多目标跟踪算法

目的 针对低视点多目标跟踪场景的遮挡问题,提出一种能够遮挡自适应感知的多目标跟踪算法。方法 首先根据每帧图像的全局遮挡状态,提出了“自适应抗遮挡特征”,增强目标特征对遮挡的感知和调整能力。同时,采用“级联筛查机制”,减少由遮挡带来的目标特征剧烈变化而认定为“虚新入目标”的错误跟踪现象。最后,考虑到历史模板库中存在遮挡的模板对跟踪性能的影响,根据每一帧中目标的局部遮挡状态,提出自适应干扰模板更新机制,进一步提高对遮挡的应变和适应能力。结果 实验结果表明,本文算法在MOTA(multiple object tracking accuracy)、M OTP (multiple object tracking precision)、FN(false negatives)、Rcll (recall)、ML (mostly lost tracklets)等指标上明显优于STAM(spatial-temporal attention mechanism)、ATAF(aggregate tracklet appearance features)、STRN (spatial-temporal relat...     

低密度脑电自适应去噪方法

便携式和可穿戴设备的低密度脑电图更便于实际使用,但会受到多种不可预知的噪声影响,给去噪带来极大的困难。脑活动成分较为相似,在特征空间分布较为紧密,而噪声成分与脑电成分不同,差异性大,在特征空间分布较为分散。本文提出了一种低密度脑电自适应去噪方法,采用小波分解和盲源分离方法提取潜在成分,并基于脑电和噪声成分在特征空间的分布特性,采用单类支持向量机识别并去除远离成分分布中心的异常成分。仿真数据的定量分析结果表明,提出的方法在肌电、眼电和工频等噪声抑制方面均优于现有方法;通过对真实脑电数据的成分簇可视化分析,直观展示了低密度脑电噪声有效去除的原因。结合盲源分离和异常检测的思路进行低密度脑电去噪,不需要设定特定噪声相关的特征参数,能够自适应地去除多种类型噪声同时有效保留脑活动成分,具有优良的性能和实用性。     

融合隐向量对齐和Swin Transformer的OCTA血管分割

目的 光学相干断层扫描血管造影（optical coherence tomography angiography,OCTA）是一种非侵入式的新兴技术,越来越多地应用于视网膜血管成像。与传统眼底彩照相比,OCTA技术能够显示黄斑周围的微血管信息,在视网膜血管成像邻域具有显著优势。临床实践中,医生可以通过OCTA图像观察不同层的血管结构,并通过分析血管结构的变化来判断是否存在相关疾病。大量研究表明,血管结构的任何异常变化通常都意味着存在某种眼科疾病。因此,对OCTA图像中的视网膜血管结构进行自动分割提取,对众多眼部相关疾病量化分析和临床决策具有重大意义。然而,OCTA图像存在视网膜血管结构复杂、图像整体对比度低等问题,给自动分割带来极大挑战。为此,提出了一种新颖的融合隐向量对齐和Swin Transformer的视网膜血管结构的分割方法,能够实现血管结构的精准分割。方法 以ResU-Net为主干网络,通过Swin Transformer编码器获取丰富的血管特征信息。此外,设计了一种基于隐向量的特征对齐损失函数,能够在隐空间层次对网络进行优化,提升分割性能。结果 在3个OCTA图像数据集上的...     

Dual-terminal event-triggered dynamic output feedback H∞ control for aero engine networked control systems with quantization

This study deals with the problem of dual-terminal event-triggered dynamic output feedback (DOF) control for aero engine networked control systems (NCSs) subject to network-induced delay, external disturbance, and quantization effects. First, we established a generalized mathematical model of the aero engine. Second, a dual-terminal dynamic event-triggered mechanism (DETM) was designed to reduce the utilization of the network bandwidth. In addition, a DOF controller with a compensation function was proposed to stabilize the system. By utilizing the Lyapunov-Krasovskii (LK) method, the stability criteria were determined. Accordingly, the design conditions of the DOF controller and DETMs were presented. Furthermore, based on a genetic algorithm (GA), a parameter tuning method was proposed to obtain the allowable delay upper bound with less conservatism. Finally, some examples were presented to show the effectiveness and superiority of the presented scheme.     

PDE-based event-triggered containment control of multi-agent systems with input delay under spatial boundary communication

This article studies the containment control problem for multi-agent systems with input delay under spatial boundary communication by employing an event-based approach. Firstly, the collective dynamics of multi-agent systems are described as parabolic partial differential equations (PDEs). Applying the integral transformation method developed in PDEs, the delayed parabolic PDEs are transformed into a series of new coupled PDE-PDE systems. Then, by taking the spatial boundary communication scheme into account and using the local boundary information, two boundary containment control protocols together with a dynamic event-triggered scheme (DETS) are designed, such that the states of all followers converge to a convex hull formed by multiple leader agents with and without input delay. The optimal protocols are given by minimizing the 2-norm of the designed control gain matrix, and the exclusion of the Zeno behavior is analyzed. Finally, a numerical simulation example is provided to support the main results.     

Semi-supervised transformable architecture search for feature distillation

Pattern Analysis and Applications - The designed method aims to perform image classification tasks efficiently and accurately. Different from the traditional CNN-based image classification methods,...     

Graph-based fine-grained model selection for multi-source domain

Pattern Analysis and Applications - The prosperity of datasets and model architectures has led to the development of pretrained source models, which simplified the learning process in multi-domain...