物联网环境下的差异网络数据库异常数据检测

当前的物联网环境下,各个智能网络的数据库的使用没有统一标准,不同生产商的数据库中的异常数据标准也不同,这就使得传统的以模式识别为基础的网络数据库异常检测方法在进行异常阀值设置时,无法形成统一标准,数据库数据量庞大且存在无序性,无法保证检测的准确性和检测效率。提出基于混沌特征分析算法的物联网环境下的差异网络数据库异常数据检测方法。依据混沌特征分析相关理论构建物联网环境下的差异网络数据库模型,构建一种异常数据的偏差函数,对不同数据库下的异常数据进行偏差统计,通过对偏差函数的统计结果进行最小值求解,根据求解描述最小化的阀值请求,实现物联网环境下的差异网络数据库异常数据的检测。实验结果表明,利用改进算法进行异常数据检测,能够提高检测的有效性与准确性。     

基于人工蜂群的无线传感器网络能耗均衡算法

由于无线传感器网络中的节点链路状况、数据传输能耗及节点剩余能量的限制,造成网络中部分感知节点寿命缩短,影响网络生存周期,提出了一种基于人工蜂群算法的WSNs能耗均衡算法,优化网络能耗均衡,从而提高网络寿命;文章给出了网络能耗相应的数学模型及优化求解算法,介绍人工蜂群算法的寻找食物过程,阐述了人工蜂群算法在网络能耗均衡方面的实现步骤;通过实验仿真证明,文章提到的算法与LEACH分簇算法、蚁群优化算法相比,具有更好的能耗和负载均衡能量、丢包率和时延性,有效地提高了网络生存周期。     

基于地面特征的移动机器人单目视觉里程计算法

提出了一种基于单目视觉的移动机器人定位算法。该方法根据地平面假设,采用基于KLT的角点检测与跟踪方法,运用基于平面的单应性关系,建立移动机器人位姿估计模型。在随机抽样一致性算法框架下,求解上述模型,实现移动机器人的初定位。在此基础上,引入角点特征的三角形结构估算平面参数差异,结合M-estimation算法,有效地去除了非地面特征信息,提高了移动机器人的定位精度。室内环境下实验结果验证了所提算法的有效性与可行性。     

认知无线电网络中提高传输层端到端吞吐率的跨层参数配置

在认知无线电网络中, 传输层端到端(TCP)吞吐率是衡量网络性能的重要指标. 前期相关研究大都具有以下两方面缺点: 第一, 大部分研究只考虑了协议底层参数来优化物理链路性能, 对传输层性能有所忽略; 第二, 目前的研究大都基于马尔可夫决策过程建模, 这需要网络具有完全知识, 使得这类模型的应用受到很大限制. 针对以上问题, 本文提出一种新的算法: 网络中每个节点通过联合配置物理层调制方式、发射功率、 链路层信道接入和TCP拥塞控制因子来找到传输层端到端近似最优吞吐率. 由于无线设备对环境感知存在误差, 本文将网络模型建模为部分可观测马尔可夫决策过程, 并将其转换成信念状态马尔可夫决策过程, 采用Q值迭代找到近似最优策略. 仿真分析表明, 提出的算法能在动态无线环境下以一定的误差限收敛于最优策略, 能在功率受限条件下, 有效提高传输层端到端吞吐率.     

智能光网络中一种新型的分布式恢复方法

提出了一种基于固定备用路由和目的端触发的智能光网络中的分布式恢复方法,所选择的任一对源端节点和目的的端节点之间的固定备用路由包括该节点对之间的k条最短路径路由和基于部分链路无关的路由.目的端节点一旦探测到业务通道的失效将立即启动恢复进程,根据网络当前的资源使用情况,在这些备用路由中按照一定的次序选择一条恢复路由并为此分配一条可用的波长(对于没有波长变换器的光网络),然后将恢复通道的建立请求消息发送给该恢复通道的相关节点,这些相关节点可以锁定相关的网络资源,以避免来自其他恢复通道的竞争.所提出的算法增加了固定备用路由的数量,从仿真结果可以看出,该方法明显改善了失效连接的阻塞性能.     

物联网环境下Web数据库异常数据检测方法研究

物联网环境下web数据库网络承载着不同的网络载体和网络信道,web数据库通过云储存的形式来实现资源共享,云储存产生的异常数据会给网络信息web数据库空间带来一种危机感和存储数据容量空间的不足,所以对物联网环境下web数据库异常数据的检测要求更精准。传统的异常数据检测方法采用简化梯度方法进行web数据库异常数据检测,对含有干扰频率成份的web异常数据不能准确的去除,检测性能低。为此,提出一种基于时空关联的分布式的web数据库异常数据检测方法,通过与集中式算法的精度和消耗量进行对比,仿真实验表明,所提方法进行异常数据检测,减少了web数据的能量消耗,信号幅值大于干扰噪声数据幅值,具有较好的抗干扰性能。     

像素重要性测量特征下的侧扫声呐目标检测

研究了在较低信噪比下,在保证检测概率的前提下尽量降低虚警概率的目标检测,提出了一种针对特定目标的两阶段筛选算法.第一阶段中,首先使用阈值分割出有效点,并定义了一种新的像素重要性测量特征用于初步筛选目标。即通过有效像素点之间的距离来赋以高斯分布的权值,当前像素重要性的值定义为剩余有效点的距离加权和,具有较高的像素重要性值的聚集性强的区域内像素点会被定位出来。第二阶段,使用卷积神经网络分类器排除虚假目标.在实验中,使用近期无人潜器获得的海底数据,召回率与虚警概率分别达到90.39%与2.39%,证明了其相比声呐目标检测主流算法有更好的检测能力。      

一种改进的快速N-FINDR端元提取算法

为了解决传统N-FINDR算法计算量大,提取结果对噪声和初始端元选取敏感,且容易将异常点作为端元而造成误提取的问题,提出一种改进的快速N-FINDR端元提取算法.该方法通过光谱距离提取并去除高光谱图像中的冗余信息,减少N-FINDR提取端元的搜索范围,平滑噪声影响,并自适应剔除异常点,通过最大化光谱距离选取N-FINDR的初始端元,避免了随机选择的盲目性.采用合成数据和真实高光谱数据进行仿真分析并与现有算法进行对比,结果表明,本文算法能在噪声与奇异点干扰下正确提取端元,其提取效率和鲁棒性均优于现有算法.     

飞控系统的光传网络的可靠性及实时性

调研了传统光传(FBL)网络的几种拓扑结构, 就可靠性和实时性两方面对它们进行了分析和比较。选择采用一个包含256个节点的mesh光交换网络, 它具有冗余拓扑结构能承受3处链路故障, 保证了网络的可靠性。以网络中发生链路故障的数目, 及多个故障同时发生时故障的邻近程度来衡量网络故障的严重性。对所有链路故障情形进行仿真, 测试端到端的通信延迟。仿真结果表明, 采用这种网络拓扑结构的光传网络, 即使在发生较为严重的故障的情况下, 端到端通信路由的跳数增加不大, 仍能满足实时通信的要求。     

基于改进二阶段检测网络的长时跟踪重检测方法

为构建适用于长时跟踪的重检测模块,受改进二阶段检测网络的GlobalTrack方法的启发,提出了一种高效的对特定模板目标进行端到端重检测的深度网络：首先,为了在大尺度图像上更高效地融合模板特征,通过构造交叉信息增强模块改进深度互相关方法,利用交叉通道注意力信息编码搜索特征和模板特征;此外,采用动态实例交互模块替代传统二阶段网络的RPN(region proposal network)和RCNN(region-based convolutional neural networks)结构,根据模板信息指导检测网络的分类和回归阶段,构建了端到端的稀疏重检测结构。在LaSOT和OxUva长时跟踪数据集上进行对比实验,本文方法相较于原始方法性能提升3%,实时帧率提升173%。实验结果表明,改进后的方法可以在全图范围内更准确、快速地重新检测模板目标。     

Guided-Wave Two-Dimensional Acousto-Optic Scanner Using Proton-Exchanged Lithium Niobate Waveguide

Two-dimensional scanning of a 0.6328 mum guided-light beam has been realized using noncolinear acousto-optic (AO) coplanar Bragg diffraction together with colinear AO guided-mode to substrate radiation-mode conversion in a Z-cut Xpropagation LiNbO3 proton-exchanged (PE) waveguide. The two surface acoustic (SAW) waves utilized are at the center frequencies of 500 and 200 MHz, propagating in the Y and X axes, respectively. Two-dimensional scanning of approximately 720 resolvable light beam spots, namely, 18 40 (horizontal vertical) scanning, has been demonstrated using a light beam of 1.0 mm aperture. The total number of resolvable beam spots can be greatly increased from 720 by simply utilizing SAW transducers of larger bandwidth and a light beam of greater aperture. It should also be possible to significantly increase the diffraction efficiency from 3 % by optimizing the parameters of the PE waveguide and the SAWs.     

Effect ofγ-radiation on the spectral luminescence characteristics of impure cadmium tungstate crystals

Results of a study of the effect of γ-radiation on the spectral luminescence properties of cadmium tungstate crystals doped with silver, bismuth, and molybdenum cations are presented. Spectral characteristics of the nondnnnoped crystals are briefly described. Absorption and photo and X-ray luminescence spectra of the crystals taken before and after exposure to γ-radiation (5.5·10⁴ Gy) are compared. It is found that the spectral characteristics of the crystals doped with silver, bismuth, and molybdenum cations do not change markedly after the exposure. The relation between the type of impurity-induced defects, individual characteristics of the impurity cations, and the character of the effect of γ-radiation on the spectral luminescence properties of impure crystals is analyzed (preliminarily). Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 1, pp. 55–60, January–February, 1997.     

Femtosecond Transform-Limited Pulse Generation by Compensating for the Linear Chirp of SPM Spectra in Dispersion Shifted Fibers

A simple technique of pulse compression, based on the linear chirp compensation of self-phase modulation (SPM) spectra in dispersion shifted fibers, is demonstrated. The optimization procedure is carried out, for a short span of a single-mode fiber, using a parabolic law, which describes the behavior of the squared output pulse width versus the pump peak power in the case of Gaussian pulses. The experimental results give a minimum pulse duration of 233 fs, which is in good agreement with the model. Shorter and coherent pulses, down to 90 fs, have been obtained by inserting an interference filter at the optical output.     

Sorting of bending magnets for the SSRF booster

The Shanghai Synchrotron Radiation Facility(SSRF)booster ring,a full energy injector for the storage ring,is deigned to accelerate the electron beam energy from 150MeV to 3.5GeV that demands high extraction efficiency at the extraction energy with low beam loss rate when electrons are ramping.Closed orbit distortion(COD)caused by bending magnet field uniformity errors which affects the machine performance harmfully could be effectively reduced by bending magnet location sorting.Considering the affections of random errors in measurement,both ideal sorting and realistic sorting are studied based on measured bending magnet field uniformity errors and one reasonable combination of bending magnets which can reduce the horizontal COD by a factor of 5is given as the final installation sequence of the booster bending magnets in this paper.     

Measurement of nonlinear coefficient of optical fiber based on small chirped soliton transmission

We measure the waveform and phase curves of short optical pulses before and after transmission over different lengths of fibers by use of the pulse analyzer with the frequency-resolved optical gating (FROG),and numerically simulate pulse evolution under the experimental conditions.The nonlinear coefficient of the fiber is given by comparing the experimental results with the numerical ones.Difference between the experiment and numerical simulation is analyzed.     

Resonance scattering of canonical elastic shells in absorbing fluid medium

Resonance scattering of elastic spherical shell and cylindrical shell while the surrounding fluid medium has absorption is studied. The normal mode solution derived using exact elastic theory and the separation of variables is still applicable. However, the scattering form function has to be modified for the absorbing medium, otherwise the unreasonable result would be obtained. The backscattering form function in the absorbing medium is redefined, and the form function of elastic spherical and cylindrical shell with vacuum or solid matter filled is calculated in various absorption conditions. The results show that the absorption of surrounding fluid leads to notable attenuation of the coincidence resonances in the mid-frequency, but it has a little influence on the low-frequency resonance scattering induced by the filler inside the shell.     

Single-beam self-referenced phase-sensitive surface plasmon resonance sensor with high detection resolution

A versatile and low-cost single-beam self-referenced phase-sensitive surface plasmon resonance(SPR)sensing system with ultra-high resolution performance is presented.The system exhibits a root-mean-square phase fluctuation of ±0.0028.over a period of 45 min.i.e.a resolution of±5.2×10-9 refractive index units.The enhanced performance has been achieved through the incorporation of three design elements:a true single-beam configuration enabling complete self-referencing so that only the phase change associated with SPR gets detected,a differential measurement scheme to eliminate spurious signals not related to the sensor response,and the elimination of retardation drifts by incorporating temperature stabilization in the liquid crystal phase modulato .Our design should bring the detection sensitivity of non-labeling SPR biosensing closer to that achievable by conventional fluorescence-based techniques.     

Influences of SiO2 protective layers and annealing on the laser-induced damage threshold of Ta2O5 films

Ta2O5 films are prepared on BK7 substrates with conventional electron beam evaporation deposition.The effects of SiO2 protective layers and annealing on the laser-induced damage threshold (LIDT) of the films are investigated.The results show that SiO2 protective layers exert little influence on the electric field intensity(EFI)distribution,microstructure and microdefect density but increase the absorption slightly.Annealing iS effective on decreasing the microdefect density and the absorption of the films.Both SiO2 protective layers and annealing are beneficial to the damage resistance of the films and the latter is more effective to improve the LIDT.Moreover,the maximal LIDT of Ta2O5 films is achieved by the combination of SiO2 protective layers and annealing.     

A stereo matching algorithm using multi-peak candidate matches and geometric constraints

Gray cross correlation matching technique is adopted to extract candidate matches with gray cross correla- tion coefficients less than some certain range of maximal correlation coefficient called multi-peak candidate matches. Multi-peak candidates are extracted corresponding to three closest feature points at first. The corresponding multi-peak candidate matches are used to construct the model polygon. Correspondence is determined based on the local geometric relations between the three feature points and the multi-peak candidates. The disparity test and the global consistency checkout are applied to eliminate the remaining ambiguous matches that are not removed by the local geometric relational test. Experimental results show that the proposed algorithm is feasible and accurate.