Single-Image Super-Resolution Reconstruction via Learned Geometric Dictionaries and Clustered Sparse Coding

Recently, single image super-resolution reconstruction (SISR) via sparse coding has attracted increasing interest. In this paper, we proposed a multiple-geometric-dictionaries-based clustered sparse coding scheme for SISR. Firstly, a large number of high-resolution (HR) image patches are randomly extracted from a set of example training images and clustered into several groups of "geometric patches," from which the corresponding "geometric dictionaries" are learned to further sparsely code each local patch in a low-resolution image. A clustering aggregation is performed on the HR patches recovered by different dictionaries, followed by a subsequent patch aggregation to estimate the HR image. Considering that there are often many repetitive image structures in an image, we add a self-similarity constraint on the recovered image in patch aggregation to reveal new features and details. Finally, the HR residual image is estimated by the proposed recovery method and compensated to better preserve the subtle details of the images. Some experiments test the proposed method on natural images, and the results show that the proposed method outperforms its counterparts in both visual fidelity and numerical measures.     

Object Tracking via Partial Least Squares Analysis

We propose an object tracking algorithm that learns a set of appearance models for adaptive discriminative object representation. In this paper, object tracking is posed as a binary classification problem in which the correlation of object appearance and class labels from foreground and background is modeled by partial least squares (PLS) analysis, for generating a low-dimensional discriminative feature subspace. As object appearance is temporally correlated and likely to repeat over time, we learn and adapt multiple appearance models with PLS analysis for robust tracking. The proposed algorithm exploits both the ground truth appearance information of the target labeled in the first frame and the image observations obtained online, thereby alleviating the tracking drift problem caused by model update. Experiments on numerous challenging sequences and comparisons to state-of-the-art methods demonstrate favorable performance of the proposed tracking algorithm.     

3G核心网话音质量监测系统中媒体流数据预处理模块的研究与开发

为解决3G核心网话音业务和扩展业务过快增长带来的核心网接口监测难题,本系统通过监测A接口、Nb接口的原始信令数据并对其进行解码分析,得到网络中与话音质量相关的核心指标,在信令处理层引入预处理模块,通过对RTP数据流和对应信令过程的关联重组数据,降低了数据流量,完成了端到端的话音质量分析。本方案已应用于3G核心网话音质量监测系统中,效果良好。     

基于软件无线电的电台综合测试系统研究

随着信息化的建设,电台已广泛应用于军事和民用领域。目前电台多波段、多制式并存,不同波段、不同制式的电台测试方法不尽相同,对电台的测试造成问题。对某一波段、某一制式电台的测试,需要选用不同性能、不同功能的测试仪器组成测试系统,如音频信号发生器、音频信号分析仪、射频信号发生器、射频信号分析仪、频谱分析仪、跳频信号发生器等。这种测试系统存在仪表种类多、体积大、成本高、效率低、操作复杂等问题。本文研究基于软件无线电的电台综合测试系统,可在一个通用硬件平台下调用不同的程序,实现多体制调制解调、跳频信号发生、射频分析、频谱分析、调制域分析、音频发生、音频分析、误码测试等多种功能,能解决多波段、多制式电台的测试问题。通过软件升级,也能适应未来电台测试需要。     

工作空间测量定位系统定向参数修正方法

为保证工作空间测量定位系统的现场测量精度,需要在发射站姿态受到温度、震动等环境因素影响时对其定向参数进行修正。提出了一种以固定接收器为基准的定向参数修正方法,通过在工作空间内稳定参考点处安装的冗余接收器监控发射站工作状态并对定向参数进行实时在线修正,采用光平面参数描述的发射站几何模型推导了接收器坐标测量方程。在此基础上,以参考点坐标为已知条件,建立了基于共面约束的定向参数修正量优化方程,给出了平差解算方法。实验结果表明,当采用6个接收器进行修正时,系统坐标测量偏差在0.15 mm以内,满足现场大尺寸坐标测量的精度要求,有效提高了系统的可靠性、实用性。     

开关电容式闭环微加速度计的稳定性研究

该文对开关电容式闭环微加速度计的系统稳定性进行了深入研究。提出了可通用于该类微传感系统的动态特性分析方法,并具体研究了传感器品质因子、力反馈延迟、电路补偿单元的参数多种因素对系统稳定性的影响。基于 CMOS工艺实现了一款接口电路芯片实例,实验结果表明,充分的电路补偿设计对于保证系统稳定性十分关键,实际的系统稳定边界与理论分析结果也较为吻合,从而证明了理论分析方法的正确性。     

卫星移动通信抗衰落技术研究

卫星移动通信信道是典型的衰落信道,信道的衰落会降低信号的接收质量,严重时可能导致通信中断。该文针对卫星移动通信在复杂信道条件下的衰落特性,简要介绍了分集接收抗衰落技术、自适应均衡抗衰落技术、编码抗衰落技术等方法,通过分析衰落产生的原理并结合抗衰落技术研究的现状,总结了相应的抗衰落性能。     

煅烧温度和恒温时间对ZnO/AAO/Si组装体系的影响

以AAO/Si为模板,采用化学气相沉积(CVD)的方法在不同温度下,通过煅烧Zn粉和C粉的混合物制备ZnO/AAO/Si组装体系,并对其结构和性质进行了研究。扫描电镜(SEM)结果表明:随着煅烧温度的升高,AAO表面的孔洞逐渐被封堵,当温度达到900℃时,在AAO的表面出现了一层ZnO薄膜。X射线衍射(XRD)结果显示,700℃时在XRD图谱上观看到六角纤锌矿的ZnO的衍射峰,并且随着温度的升高,ZnO的衍射峰逐渐增强,当温度升至800和900℃时出现了ZnAl2O4的衍射峰。因此,化学气相沉积制备组装体系时的最适温为700℃。在700℃时煅烧不同恒温时间制备的ZnO/AAO/Si组装体系SEM图显示,随着恒温时间的延长,孔的封闭效应逐渐明显。     

掺杂位置对基于马赫-曾德尔干涉的硅光调制器的消光比的影响

在基于马赫-曾德尔干涉的硅光调制器中,载流子吸收会极大的影响器件的消光比。并且,不同的掺杂位置会引起注入的载流子的分布不一样,从而导致不同的消光比。从实验上研究了这一现象,实验中的器件采用0.18 μm CMOS工艺制作在SOI材料上。实验表明,掺杂位置离脊波导的边沿0.5 μm左右时,器件会获得最佳的消光比。     

Manipulating the Light-Matter Interaction of PtS/MoS2 p–n Junctions for High Performance Broadband Photodetection

Due to the limited carrier concentration, 2D transition metal dichalcogenides have lower intrinsic dark current, and thus, are widely studied for high performance room photodetection. However, the light-matter interaction is still unclear, thus tuning the photoexcitation and further manipulating the photodetection is a challenge. Herein, large-area PtS films are synthesized, and the growth mechanism is investigated. It is demonstrated that PtS has an orthorhombic structure and exhibits the p-type semiconducting behavior. Then, MoS₂/PtS p–n heterojunction is fabricated, and its energy diagram is discussed based on the Kelvin probe force microscopy. The contact potential difference is about 160 mV, which is much larger than previous 2D junctions facilitating the charge separation. Furthermore, the phototransistor based on MoS₂/PtS p–n heterojunction is prepared, showing broadband photoresponse from visible to near-infrared. The manipulation of an external field on photoresponse, detectivity, and rise/fall time are explored and discussed. The responsivity can reach up to 25.43 A W⁻¹, and the detectivity is 8.54 × 10¹² Jones. These results indicate that PtS film is a prospective candidate for high-performance optoelectronic devices and broaden the scope of infrared detection materials.