The effect of contact degradation on electromagnetic radiation in electronic devices

Loose electrical connectors tend to increase electromagnetic radiation. In this current study, the effect of loose contacts on electromagnetic radiation is theoretically modeled and experimentally analyzed. An equivalent model was developed and a wire antenna model was built according to the physical dimensions of the connector to evaluate the radiated field in the time domain. Combining the expressions of the radiated fields and the transfer function of the test probe, the relationship between the input signal and the leakage voltage was obtained. The near field test method was used to measure the leakage signal caused by the loose contact. The tested results for a specific loose contact condition were consistent with the theoretical analysis.     

Determination of dynamic contact angles within microfluidic devices

Here, we report a single-point detection method for the determination of dynamic surface conditions inside microfluidic channels. The proposed method is based on monitoring fluorescence amplitude as a function of the convolution of a laser beam with segmented flow consisting of two immiscible liquids, one containing fluorescent dye. The fluorescence amplitude is determined by the flow rate and the droplet shape, which is affected by the channel surface properties. We modeled the interaction of a droplet and a laser beam via computer-aided design software, using the laser beam location in relation to the droplet shape as a parameter. The method was applied to fused silica capillaries with both unmodified and modified surfaces, with segmented flow exhibiting water contact angles of ≈?30° and ≈?100°, respectively. The method allows discrimination between hydrophillic and hydrophobic surfaces, as well as the quality of the treatment. The results were verified using fluorescence imaging of the droplets via a stroboscopic technique. We also applied this method to the analysis of microfabricated channels with non-circular cross sections. We demonstrated that the technique enables the determination of the hydrophobicity of channel surfaces, a crucial property required for the generation of segmented flow or emulsions for applications such as digital PCR.     

Electrical contact resistance as a diagnostic tool for MEMS contact interfaces

The electrical contact resistance (ECR) was evaluated as an in situ diagnostic tool for the contact interface behavior of microelectromechanical systems (MEMS). Special polycrystalline silicon (polysilicon) MEMS devices fabricated by surface micromachining were used to study polysilicon/native oxide/polysilicon contact interfaces. ECR measurements obtained during monotonic contact loading and unloading and cyclic contact loading are interpreted in the context of a previous ECR theory. For monotonic contact loading and unloading, the ECR was measured as a function of apparent contact pressure and was found to be on the order of 10/sup 5/ /spl Omega/. The fairly moderate decrease of the ECR with the increase of the contact load is attributed to the intrinsic nonohmic behavior of the native oxide film. Experimental ECR results are correlated with analytical solutions to determine the oxide film thickness. The results indicate that the oxide film remains nearly intact under monotonic contact loading and unloading. Differences in the ECR behavior during unloading are discussed in light of the statistical distribution of asperity nanocontacts and the prevailing deformation mode. During cyclic contact loading, rupture of the oxide film leads to the formation of polysilicon/polysilicon nanocontacts, which produces ECR values in the range of 10/sup 2/-10/sup 3/ /spl Omega/. The erratic behavior of the ECR during cyclic contact loading is related to the pronounced effects of the insulating oxide film and oxide debris trapped at the contact interface.     

DTN中考虑连接时间的概率路由算法

鉴于连接时间对报文能否成功传输有重要影响,提出考虑连接时间的概率路由算法。该算法基于连接时间和历史相遇频率两个因素来估计递交概率,从而大大提高了报文成功递交的概率,减少了报文传输中断的发生。仿真结果表明,与传统的概率路由相比该路由算法具有较高的报文递交概率和较低的网络开销率。     

基于Pt/石墨烯纳米复合材料的甲醛电化学传感器

采用电沉积的方法制备了Pt/石墨烯纳米复合材料,考察了该复合材料的电化学性能,用于甲醛的检测,表现出良好的检测性能.实验结果表明:在0. 1 mol/L的H2 SO4 溶液中,Pt/石墨烯纳米复合材料修饰电极可以实现在2 ×10 -6 ~2 ×10-3 mol/L浓度范围内甲醛浓度的检测,最低检测限为1 ×10-6 mol/L,并且具有高的灵敏度和良好的重现性.     

基于石墨烯晶体管的多巴胺检测微流控芯片

设计并制备了一种集成液体栅极的石墨烯场效应晶体管的微流控芯片,利用其对多巴胺进行检测,研究了多巴胺分子对石墨烯场效应管转移特性的影响。将石墨烯转移到载玻片上作为导电通道和传感材料集成在微流通道内部,利用剥离(lift-off)工艺制作晶体管的源极和漏极,采用液体栅极的方法对晶体管的转移特性进行测试。同时,结合微电子学的能带理论,从电子迁移的角度出发,讨论了石墨烯和多巴胺之间的氧化还原反应。并采用金属Pt电极作为石墨烯晶体管的栅极,检测到了1 nmol/L浓度的多巴胺溶液。     

基于电化学还原氧化石墨烯的电化学DNA生物传感器

使用还原氧化石墨烯(rGO)制备一种简单、快速和可重复方法构建DNA生物传感器。将带负电的氧化石墨烯(GO)与半胱氨酸上带正电的氨基基团通过静电作用相互吸附,用线性扫描伏安法(LSV)电化学还原电极表面吸附的GO。将二茂铁标记的DNA(Fc-DNA)探针固定到r GO表面,成功构建DNA传感器。传感器的制备过程使用循环伏安法和拉曼光谱表征。通过杂化前后DNA传感器所展现出方波信号峰电流的差异,实现对目标DNA的定量检测。实验结果表明:目标DNA浓度在1. 0×10~(-13)～1. 0×10~(-6)mol/L范围内,峰电流变化与目标DNA浓度呈线性关系,线性相关系数为0. 981,检测限是2. 0×10~(-13)mol/L (S/N=3)。     

Analysing interactive devices based on information resource constraints

Analysis of the usability of an interactive system requires both an understanding of how the system is to be used and a means of assessing the system against that understanding. Such analytic assessments are particularly important in safety-critical systems as latent vulnerabilities may exist which have negative consequences only in certain circumstances. Many existing approaches to assessment use tasks or scenarios to provide explicit representation of their understanding of use. These normative user behaviours have the advantage that they clarify assumptions about how the system will be used but have the disadvantage that they may exclude many plausible deviations from these norms. Assessments of how a design fails to support these user behaviours can be a matter of judgement based on individual experience rather than evidence. We present a systematic formal method for analysing interactive systems that is based on constraints rather than prescribed behaviour. These constraints capture precise assumptions about what information resources are used to perform action. These resources may either reside in the system itself or be external to the system. The approach is applied to two different medical device designs, comparing two infusion pumps currently in common use in hospitals. Comparison of the two devices is based on these resource assumptions to assess consistency of interaction within the design of each device.     

石墨烯气体传感解吸附特性研究

分析探讨了石墨烯气体解吸附特性与解吸附方法。通过实验分析石墨烯对NO2气体分子的响应时间、气体分子解吸附时间,分析探讨石墨烯的气敏特性。实验表明,石墨烯对NO2气体传感灵敏度高,响应快,但恢复过程缓慢,气体解吸附时间长。分析表明,通过加热的方法、光照的方法可有效减少石墨烯气体解吸附时间,改善解吸附特性。     

Vibrational analysis of graphene based nanostructures

This paper deals with the molecular mechanics simulations of graphene nanostructures and their vibration behavior for potential applications on nano-electronics and nanocomposites. The fundamental frequencies for CNTs range from 10 to 250 GHz and 100 to 1000 GHz for the cantilevered and bridged conditions, respectively. As the ratio L/d increases the fundamental frequency decreases, as expected. A decrease on fundamental frequencies with the bending waviness was noticed for all conditions. The mode shape for bent carbon nanotubes seems to be a superposition of the vibration mode and the bending mode for the zigzag configuration. Multi-layered graphene nanosheets were also investigated. The fundamental frequencies ranged from 50 to 150 GHz, with an odd/even shape mode switch.     

基于深度神经网络的移动端人像分割

针对现有的人像分割算法大多忽略移动设备的硬件限制,盲目追求效果,以致无法满足移动端对于分割速度要求的问题,提出了一种可在移动设备上高效运行的人像分割网络。首先,基于编码器-解码器的轻量级U型架构来构建网络;其次,为了克服全卷积网络（FCN）受制于较小的感受域,无法充分捕获长距离信息的缺陷,引入期望最大化注意力块（EMAU）置于编码器之后、解码器之前;然后,在训练阶段添加多层边界辅助损失,有助于提高人物边界轮廓的准确度;最后,对模型进行量化和压缩。在Veer数据集上将所提网络与PortraitFCN+、ENet和BiSeNet等网络进行对比实验。实验结果表明,所提网络可以提高图像推理速度和分割效果,并能够以95.57%的准确率处理分辨率为224×224的RGB图像。     

基于OMAP的手持设备嵌入式系统研究

嵌入式系统是将先进的计算机技术,半导体技术以及电子技术和各行业的具体应用相结合的产物,便携式仪器具有高集成度、低功耗以及使用灵活的特点.因此适合于战场设备检测和机动性强的场合,对OMAP平台构架进行研究,同时结合便携式仪器设计构建了OMPA平台,在OMAP基础硬件平台上移植Linux操作系统.该系统是融合计算、通讯、存储等多种功能,搭建一套适用性较强的开放式多媒体应用平台,并设计了人机交互的图形界面,实现了实时图形操作界面,解决了关键的采集、处理、显示、键盘管理等技术问题.     

基于深度神经网络的移动端人像分割

针对现有的人像分割算法大多忽略移动设备的硬件限制，盲目追求效果，以致无法满足移动端对于分割速度要求的问题，提出了一种可在移动设备上高效运行的人像分割网络。首先，基于编码器-解码器的轻量级U型架构来构建网络；其次，为了克服全卷积网络（FCN）受制于较小的感受域，无法充分捕获长距离信息的缺陷，引入期望最大化注意力块（EMAU）置于编码器之后、解码器之前；然后，在训练阶段添加多层边界辅助损失，有助于提高人物边界轮廓的准确度；最后，对模型进行量化和压缩。在Veer数据集上将所提网络与PortraitFCN+、ENet和BiSeNet等网络进行对比实验。实验结果表明，所提网络可以提高图像推理速度和分割效果，并能够以95.57%的准确率处理分辨率为224×224的RGB图像。     

基于自适应分块的移动设备上特征点提取方法

当前,移动设备的计算能力越来越强,但类似增强现实对实时性要求较高的应用,其性能还无法完全满足需求。在增强现实应用中,提取特征点和特征点的匹配是关键。主要关注特征点的提取,以SURF算法为例,针对移动设备较小的高速缓存容量不适应原算法图像数据访问方式的问题,提出了依据图像内容的自适应分块方法。实验结果表明,改进后的算法在没有牺牲精确度的情况下,速度提高了1.5¹.7倍。     

基于DSP技术的煤矿瓦斯检测装置设计

由于目前用于瓦斯检测的设备普遍存在探测范围小、反应时间慢、成本高和稳定性差等问题,因此根据气体的近红外吸收光谱的特点,采用D S P作为微控制器,结合红外差分吸收原理设计一种响应时间短、稳定性强的矿井瓦斯检测装置,对于预防在煤矿和其他企业安全生产中的瓦斯事故具有一定意义。     

基于六轴MEMS器件姿态测量系统

为了解决噪声和漂移等原因造成的误差不断累积的问题,针对陀螺仪的静态性能以及加速度计的动态性能,提出了一种利用六轴MEMS器件对照相机三脚架的稳定测量系统,介绍了MEMS器件的工作原理,介绍硬件系统和软件系统,完成了基于ADXR450陀螺仪和ADXL355加速度计的检测硬件系统设计,通过传感器获取角速度加速度信息,采用不同的滤波方式对输出结果进行了分析,比较卡尔曼滤波和一阶RC数字滤波;经比较,卡尔曼滤波实时性更好,一阶RC滤波动态响应更好;实验证明,系统静态下更适用于一阶滤波,计算出姿态测量角度误差在0.104°以内,得到理想的姿态信息,能有效地提高检测目标姿态的精度。     

基于FPGA的可加密USB存储设备设计

基于FPGA的可加密USB存储设备的设计过程,介绍了FPCA芯片EP1C3T100、USB接口芯片AU6983等各个模块的功能及硬件电路设计。对AES加密算法作了详细说明,并对硬件FPGA实现进行了设计和优化。该设备由FPGA芯片通过硬件来完成数据加密过程,由高速传输总线进行数据传输。具有实时性好、安全性高等优点。     

Solution-processed ZnO energy harvester devices based on flexible substrates

Microsystem Technologies - The smart healthcare devices connected to the internet of things (IoT) for medical services can acquire and process physiological data of risk patients, real-time...     

基于同步转换器的飞机仪表综合测试系统

针对国外自动测试设备昂贵、国内设备专用性强这一现状,采用单片机做控制器,设计了基于同步转换器的飞机仪表综合测试系统,用于航空仪表的地面离位测试.介绍了航空仪表的测试原理,设计了同步发送电路和同步接收电路,实现了数字/同步信号的相互转换.采用数字I/O口和继电器板实现了离散量的自动测试.采用双通道耦合的方法,提高了系统测...