酞菁钯-聚苯胺修饰声表面波传感器及含磷毒气的检测

针对含磷毒气快速检测问题,以自制的杂化酞菁钯.聚苯胺为敏感膜材料,设计了一种双信道声表面波(SAW)传感器.阐述了传感器的基本原理,推导出以有机膜作为信道中间介质时,差频输出△f由物理化学吸附两种机制叠加的数学模型.依据声波振荡条件,设计了146±5MHz振荡频率的信号采集电路;以钽酸锂晶体为压电基片,通过MEMS微加工技术形成叉指电极对和加热膜;以真空镀膜工艺将敏感膜材料成膜,修饰在SAW信道中间区域构成SAW传感器.测试结果表明:最优气敏性时的材料配比为PdPc0.35PANI0.65;芯片加热60～80℃可提高性能,响应时间≤30s;输出与测试气体浓度与数学模型一致,为线性变化率-110kHz(mg/m3)的N型线性关系;抗汽油、CO2等气体干扰;80天稳定性考核,△f≤±0.1kHz,满足实际使用要求.     

InAs/GaSb超晶格红外探测器台面湿法腐蚀研究

研究了不同腐蚀体系对InAs/GaSb超晶格材料台面的刻蚀,并从中选择了由氢氟酸、酒石酸和双氧水构成的酒石酸腐蚀体系。该体系较适合InAs/GaSb超晶格材料的刻蚀,刻蚀速率稳定,下切效应小。进一步研究发现当HF达到一定浓度后不再影响刻蚀速度;在较低的酒石酸和双氧水浓度下,刻蚀速度是由氧化过程控制,且反应速度和双氧水的浓度成正比。腐蚀液配比为酒石酸(3.5g)∶H2O2(4mL)∶HF(1mL)∶H2O(400mL),刻蚀速度约为0.5μm/min。     

一种基于CPLD的动调陀螺测斜仪数据采集系统设计与实现

动调陀螺测斜仪是一种可在油气勘探中用于测量钻头走向方位的仪器,且不受地磁干扰,日益受到业界的青睐.针对动调陀螺测斜仪模拟信号数字化的实际需要,本文研究开发了一种基于CPLD的动调陀螺测斜仪数据采集系统.系统由CPLD控制芯片、模拟开关、A/D采样芯片以及相应的接口电路等组成.测试结果表明,所设计的数据采集系统采集精度高、稳定性好,能够在油气井高温、高压恶劣环境条件下正常工作,不仅具有工程实用价值,而且为动调陀螺测斜仪灵活、快捷的升级换代提供了保证.     

加载叉型电磁带隙结构的微带天线设计

分析了电磁带隙结构的原理及其特有的抑制表面波的特性,通过在原有贴片天线上加载结构紧凑的叉型电磁带隙结构来设计天线,并对中心频率为7.5GHz的叉型电磁带隙结构微带天线进行了仿真研究.结果表明,加载叉型电磁带隙结构以后,微带天线的增益提高2dB以上,天线方向图改善.研究结果对实现高效紧凑天线具有参考价值.     

双余度无刷直流电机系统的仿真及分析

为深入研究冗余无刷电动舵机系统,在建立双余度无刷直流电动机（DR-BLDCM）数学模型的基础上,利用Matlab／Simulink搭建了其伺服系统的仿真模型。模型采用模块化的设计方法,电机反电动势由分段线性法产生,提高了系统的准确性和有效性。仿真结果证明了该模型的有效性,为电动舵机系统设计提供了思路。     

Fake modern Chinese painting identification based on spectral–spatial feature fusion on hyperspectral image

Chinese painting is famous and valuable for special painting materials, skills and final art effects used, yet this has resulted in many fake paintings being produced. Those fake paintings were normally made by using modern high resolution scanning and printing technology, thus it is very hard to identify the fake ones by human vision. To address this challenging problem, in this paper, a hyperspectral image based features fusion method is proposed. Firstly, we scan Chinese paintings using a visual band hyperspectral camera with the spectral frequency ranging from 400 to 900 nm. Then, the spectral and spatial features are extracted respectively by using the principal component analysis and a convolution neural network. Finally, we fuse these two kinds of features and input the feature set into a support vector machines for classification. All samples of real and fake paintings are obtained from local Chinese painting organization. The experimental result shows the effectiveness of the proposed method with an accuracy achieved of 84.6 %, which is significantly higher than other approaches where only spectral or spatial feature is used.     

沙漠背景下红外偏振图像目标检测方法

红外偏振成像探测同时探测目标的强度辐射与反射偏振态,可以获取传统光学无法获取的目标。偏振探测获取的偏振度、偏振角等信息反映不同的物理特性,与强度图像有较强的互补性。针对该特性,提出一种沙漠背景目标红外偏振图像检测方法。使用一种改进的核模糊聚类算法对红外图像和偏振图像进行聚类处理;利用稀疏融合方法将聚类后的红外图像和偏振度图像中的物体信息充分结合,以区分目标与背景,以达到目标检测的目的。实验表明,提出的检测方法相对小波融合和拉普拉斯金字塔融合结果噪声更低、细节更清晰。     

LTE系统物理广播信道解码算法分析与优化

本文首先介绍了下行广播信道编码过程和PBCH的信道结构,以及PBCH解码的必要性,然后结合PBCH的结构特点,提出一种离线buffer数据的方式;该方案以平衡PBCH解码的可靠性和有效性为目标,将一帧的数据多次利用,在有限的一帧时间内进行多种可能情况的盲检测尝试。最后对该算法的虚警误检概率进行仿真分析,并根据分析结果提出优化方案,该优化方案虽然降低了解码的有效性,但是明显的提高了解码的可靠性,而且在降低PBCH解码虚警误检概率的同时提高系统的鲁棒性。     

Local morphology fitting active contour for automatic vascular segmentation

In this paper, we propose an active contour model using local morphology fitting for automatic vascular segmentation on 2-D angiogram. The vessel and background are fitted to fuzzy morphology maximum and minimum opening, separately, using linear structuring element with adaptive scale and orientation. The minimization of the energy associated with the active contour model is implemented within a level set framework. As in the current local model, fitting the image to local region information makes the model robust against the inhomogeneous background. Moreover, selective local estimations for fitting that are precomputed instead of updated in each contour evolution makes the evolution of level set robust again initial location compared to the current local model. The results on synthetic image and real angiogram compared with other methods are presented. It is shown that the proposed method can achieve automatic and accurate segmentation of vascular angiogram.