DNA纳米结构在药物转运载体和智能载药中的应用进展

纳米材料具有荷载效率高、靶向性能好、半衰期较长等优点, 非常适于作为药物转运载体, 可有效提高药物的水溶性、稳定性和疾病治疗效果.目前, 开发具有良好生物相容性、可控靶向释放能力和精确载药位点的理想药物转运载体, 仍是该领域存在的挑战性问题和当前研究的重点.自组装DNA纳米结构是一类具有精确结构、功能多样的纳米生物材料, 具有良好的生物相容性和稳定性、较高的膜渗透性和可控靶向释放能力等优点, 是理想的药物转运载体和智能载药材料.本文总结了DNA纳米结构的发展历程、DNA纳米结构作为药物转运载体的研究现状、动态DNA纳米结构在智能载药中的应用进展, 并对其发展前景进行了展望.     

智能手机的主要叶类蔬菜品质和新鲜度指标的光谱检测

蔬菜品质和新鲜度的高低不仅影响食用时的口感,而且营养程度也不一样。作为蔬菜品质和新鲜度重要参考指标之一的叶绿素和含水量的检测,已经越来越受到国内外学者的重视。相比于传统的肉眼目视判断的检验方法,可见-近红外光谱分析具有快速高效、无损、非接触等独特的优势,更加适合蔬菜的实时检测。目前相关研究主要集中在生长中植被叶绿素和含水量的反演,对市场上成品蔬菜的研究较少,或者研究对象单一,缺乏市场普适性。此外,光谱数据的获取需要专业的光谱仪采集,费时费力,各种生理生化指标的研究离实用化还有很长的距离。为了与实际相结合,基于智能手机光谱系统（SCSS)建立了快速、准确、普适性强的反演蔬菜叶绿素和含水量的模型,并通过地面光谱仪SVC数据验证了该系统的可靠性。选取市场典型的五种蔬菜（菠菜、小油菜、油麦菜、生菜和娃娃菜）作为实验样本,分别进行常温保存和冷藏保存来模拟现实中菜市场和超市的蔬菜储存环境。每隔24 h进行一次数据采集。对获取的原始光谱数据进行波段选择和小波变换去噪的预处理。构建蔬菜叶绿素反演指数(VCRI_{（m, n）})和蔬菜含水量反演指数(VWRI_{(i, j)}),分别提取该两个指数与叶绿素和含水量实测值的相关系数R作为权重系数,最终建立了叶绿素和含水量的加权平均反演模型。实验结果表明,SVC仪器和SCSS两者数据针对蔬菜叶绿素和含水量的敏感波段基本一致,叶绿素反演的敏感波段在730~980 nm之间,反演精度R2分别为0.863和0.808 1,标准差为8.679 5和8.892 5;含水量反演的敏感波段在水汽吸收波段950~1 000 nm之间,反演精度R2分别为0.742 9和0.712 9,标准差为8.789 9%和8.861 4%。SVC实验数据跟SCSS实验数据结果十分接近,验证了新型智能手机光谱系统实时监测蔬菜叶绿素和含水量的有效性。智能手机光谱系统具有体积小、价格便宜的优势,结合网络云端服务和实时数据反馈的特点,能够实现蔬菜品质和新鲜度指标的智能检测,让光谱分析真正应用于人们日常生活中。     

Acoustic absorbers at low frequency based on split-tube metamaterials

The remarkable properties of acoustic metamaterials have attracted massive researches and applications, especially on low-frequency sound absorptions. Currently, most of the acoustic metamaterial absorbers employ resonances in plastic cavities, and their structural strengths are important in many circumstances, especially in harsh environment. However, studies of metamaterials including this point are very scarce. Here, we propose an acoustic metamaterial for low-frequency (<500 Hz) absorptions, composed of three nested square split tubes with inverted opening directions. The efficiency of the absorber is investigated both numerically and experimentally, and absorptions at the peeks are found to exceed 90% and the frequency can be effectively adjusted by tuning its geometric parameters. We further test its yield strength under compression and confirm its buckling behavior happens from the outmost layer. This tunable acoustic metamaterial with a fairly good mechanical strength may lead to broad applications in noise reduction.     

基于XMPP的智能小区远程控制系统研究与设计

为解决智能家居系统中的通信控制实时性不强,系统可扩展性较差的问题,从即时通信领域引入XMPP协议,对传输的XML消息格式进行了扩展,使其适合于家居设备信息的描述和传输。通过asmack类库开发家居远程控制端和家居网关客户端,并对OpenFire服务器进行二次开发,构建了远程控制系统,该系统兼具智能家居控制与即时通信功能,实验表明,该系统控制信息传输时延在150ms以内,服务器端能支持200000用户,能满足小区用户的日常需求。     

基于ARM和nRF905组网的智能家居系统设计

针对家居中电器种类和数目繁多且分散于各室造成控制不便,提出了一种利用nRF905射频模块实现无线通信的智能家居控制系统。系统对射频数据传输协议进行了设计,给出了室内多个微控制器的组网方案。用户通过手机短信或万能遥控器把对家电的控制信号发送至基于ARM平台搭建的主控中心,再由主控中心发送至若干个通信节点或智能插座,万能遥控器通过射频信号实现对家电的近距离遥控,手机通过GSM通信实现对家电的远程遥控。通信节点基于STC89C52RC单片机设计,能够实现对多种红外家电的控制并具备安防报警功能,智能插座则用于控制非遥控家电。实验表明,该系统可使网络中各节点、插座得到有效的控制,数据传输稳定、功能丰富、可扩展性强,具备较高的应用价值。     

一种金融双界面卡可测试性设计研究

由于安全性好,存储容量大等方面的优点,金融IC卡代替传统的磁条卡已经成为一种必然趋势。由于电路的复杂性,在金融卡的设计过程中必需注意可测试性设计。论文对一种金融双界面卡进行可测试性设计,主要关注嵌入式存储器、振荡器电路和非接触模拟前端电路的可测试性设计,在进行理论分析的基础上提出测试结构,并对电路进行设计。最终基于V777系统对流片以后的金融双界面卡进行测试,测试结果表明本设计具有很好的功能。     

Injection attack detection using machine learning for smart IoT applications

Smart cities are a rapidly growing IoT application. These smart cities mainly rely on wireless sensors to connect their different components (smart devices) together. Smart cities rely on the integration of IoT and 5G technologies, and this has created a demand for a massive IoT network of connected devices. The data traffic coming from indoor wireless networks (e.g., smart homes, smart hospitals, smart factories , or smart school buildings) contributes to over 80% of the total data traffic of the current IoT network. As smart cities and their applications grow, security and privacy challenges have become a major concern for billions of IoT smart devices. One reason for this could be the oversight of handling security issues of IoT devices by their manufacturers, which enables attackers to exploit the vulnerabilities in these devices by performing different types of attacks, e.g., DDoS and injection attacks. Intrusion detection is one way to detect and mitigate the risk of such attacks. In this paper, an intrusion detection method was proposed to detect injection attacks in IoT applications (e.g. smart cities). In this method, two types of feature selection techniques (constant removal and recursive feature elimination) were used and tested by a number of machine learning classifiers (i.e., SVM, Random Forest, and Decision Tree). The T-Test was conducted to evaluate the quality of this proposed feature selection method. Using the public dataset, AWID, the evaluation results showed that the decision tree classifier can be used to detect injection attacks with an accuracy of 99% using only 8 features, which were selected using the proposed feature selection method. Also, the comparison with the most related work showed the advantages of the proposed intrusion detection method.     

棉网均匀度检测中的图象识别方法

传统的生条不匀率通常用萨氏条干不匀率和重量不匀率表示,但它们不能直接反映棉条的内在结构状态。本文根据图象分析原理,采用简单区域划分法和共生矩阵分析法,对棉网均匀度及其结构进行了定量分析,并比较了二种方法的分析结果。简单区域划分法能定量地给出棉网均匀度的检测数据,但对棉网的结构特性描述不够直观。共生矩阵法采用方向因子D(θ)和均匀度因子E(θ)给出棉网纤维的聚集状态。这些都已在CPPS-85图象信息处理系统,即由两级微机组成的计算机花型准备系统上获得了良好的检测结果。     

计算机教学机房的建设、管理与维护

针对计算机教学机房的建设、管理与维护,介绍了一些有效可行的保证机房正常、稳定运行的“软”保护方法,不需任何投资、不存在兼容性问题,且快速、方便。