基于量子粒子群和SARSA算法的蜂窝网络信道分配

为了对蜂窝网络的信道进行在线、实时和动态的分配,设计了一种基于量子粒子群算法和SARSA算法的蜂窝网络信道分配方法。首先,采用分配方案表示量子粒子的位置,通过粒子群在粒子空间中不断寻优,将寻求的最优粒子位置作为信道分配方案的初始解。然后,根据得到的初始解的目标值来计算各状态动作对处的初始Q值,在此基础上,通过加入资格迹的SARSA(λ)算法和ε-greedy策略得到改进的SARSA(λ)算法,执行算法直到各状态动作对的Q值不发生变化为止,此时最终解为信道分配方案。为了验证文中方法的优越性,采用具有30个小区的移动蜂窝网络进行实验,仿真实验结果表明文中方法能实现蜂窝通信网络中信道的在线分配,且与其它方法比较,具有信道分配合理和收敛速度快的优点,是一种有效的信道分配方法。     

基于粒子群的无线紫外光网络快速信道分配方法

针对无线紫外光散射通信中非视距(NLOS)传输特点和信道干扰模型,采用基于粒子群的无线紫外光网络快速信道分配方法,充分考虑了空间角度对信道冲突矩阵的影响,实现了一种定向、快速的信道分配新方法。仿真分析了该算法的平均迭代次数、平均干扰度以及收敛时间与粒子群数目和信道数目的关系。实验结果表明此紫外光网络信道分配方法具有收敛速度快、冲突度小的优势,保障了无线紫外光网络信道分配的快速性和准确性。     

基于自适应状态聚集Q学习的移动机器人动态规划方法

针对现有移动机器人路径规划方法存在的收敛速度慢和难以进行在线规划的问题,研究了一种基于状态聚集SOM网和带资格迹Q学习的移动机器人路径动态规划方法——SQ(λ);首先,设计了系统的总体闭环规划模型,将整个系统分为前端(状态聚集)和后端(路径规划);然后,在传统的SOM基础上增加输出层构建出三层的SOM网实现对移动机器人状态的聚集,并给出了三层SOM网的训练算法;最后,基于聚集的状态提出了一种基于带资格迹和探索因子自适应变化的改进Q学习算法实现最优策略的获取,并能根据改进Q学习算法的收敛速度自适应地控制前端SOM输出层神经元的增减,从而改进整体算法的收敛性能;仿真实验表明:文中设计的SQ(λ)能有效地实现移动机器人的路径规划,较其它算法相比,具有收敛速度快和寻优能力强的优点,具有较大的优越性。     

基于改进交叉熵算法的随机需求车辆路径设计方法

传统的车辆路径规划方法无法有效地应对实时在线客户需求量随机变化的情形且收敛速度过慢,为了克服其缺点,设计了一种基于蒙特卡罗和重要性采样的交叉熵车辆路径规划方法;首先对随机动态车辆路径规划问题进行了数学建模,然后,描述了蒙特卡罗和交叉熵算法实现稀有事件概率估计的原理,并引入Tsallis熵实现对传统交叉熵的改进,采用蒙特卡罗多次采样获得的费用期望作为路径真实费用的估计值,通过交叉熵算法对重要性概率密度函数和分位数进行不断更新,以增加重要样本获取的概率,从而实现最优路径的获取;最后定义了具体的基于Tsallis熵的随机动态车辆路径规划方法;在MATLAB仿真工具下进行试验,结果表明文中方法能有效地解决随机动态车辆路径问题,与其它方法相比,具有收敛速度快和收敛精度高的优点,是一种有效的随机动态车辆路径规划方法。     

基于概率感知和改进量子遗传算法的节点部署策略

为了最大化监测区域的网络覆盖率和实现网络的负载均衡,设计了一种基于改进概率感知模型和量子遗传算法的移动节点部署方法。首先,在传统概率感知模型中加入环境干扰噪声因素和节点剩余能量因素进而获得改进的概率感知模型,然后,对传统的量子遗传算法进行改进,设计了新的量子旋转门和量子比特变异方式,以加快全局收敛速度和防止陷入局部最优。最后,定义了基于改进量子遗传算法获取移动节点最优部署位置的算法。仿真实验表明：文中方法能有效地对网络区域进行部署,实现最大化网络的覆盖率和最小化能量消耗,与其它方法相比,具有较大的优越性,是一种可行的方法。     

基于LMS/SOLMS算法的时变多径水声信道估计方法

缓变信道下基于LMS算法的信道估计算法具有较好的跟踪性能,但对快变信道,LMS算法跟踪性能下降。SOLMS算法具有比LMS算法更好的跟踪性能,尤其是在快变的信道下。但由于SOLMS算法在收敛阶段的振荡性,这时收敛速度较LMS算法慢。本文提出一种收敛模式下用LMS算法获得信道的参数,收敛后则切换成SOLMS算法跟踪信道的变化的信道估计方法。新方法结合了LMS算法收敛快和SOLMS算法跟踪性能好的优点。对时变多径水声信道估计的计算机仿真实验证明了该方法的有效性。     

基于生命期模型的无线传感器网络信道分配博弈算法

针对无线传感器网络中节点因干扰过大导致重传能耗增加, 进而节点过早失效、网络生命期缩短的问题, 根据网络拓扑信息和路由信息设计节点的负载模型, 从而构建了节点的生命期模型. 然后利用博弈论将路径增益、交叉干扰和节点生命期等性能参数融入到效益函数中, 构建信道分配博弈模型. 理论分析证明该博弈模型存在纳什均衡. 进而运用最佳回应策略, 在所构建的信道分配博弈模型的基础上, 设计了一种优化网络生命期的抗干扰信道分配算法. 该算法使节点在选择信道时避免与网络中交叉干扰较大的节点和生命期较小的节点使用相同信道, 实现干扰小、能耗低且均衡的信道选择. 理论分析与仿真结果证明该算法最终能够快速地收敛到纳什均衡, 且具有较小的信息复杂度, 从而减小算法本身的通信能耗. 同时, 该算法具有良好的抗干扰性和信道均衡性, 能够有效地延长网络生命期.     

基于安全性约束和协同禁忌优化算法的云计算工作流调度

针对现有的云计算工作流调度方法侧重于节能和可靠性等方面进行研究,忽略了安全性约束的要求,设计了一种基于协同禁忌算法的具有安全型约束的能实现云计算工作流高效调度的方法。首先,定义了云计算工作流调度的DAG图,对安全性约束进行了形式化描述,并建立了云计算工作流调度的数学模型。然后,在经典的协同禁忌算法的基础上,通过设计解的编码方式、适应度函数、变邻域结构和双禁忌表,实现对经典的协同禁忌算法进行改进。最后,定义了基于改协同禁忌算法实现对云计算工作流调度的具体算法。在云计算的仿真环境Cloud-Sim下进行实验,实验结果证明了文中方法不仅具有较快的收敛速度,而且能寻求到比其它方法更优的调度方案,能满足安全性约束要求,是一种可行实用的调度方法。     

一种快速收敛的符号回归常数模盲均衡算法

为了加快符号回归常数模算法(SRCMA)的收敛速度,本文提出了一种适合于BPSK信号 的快速算法。该算法用新的误差函数替代SRCMA中的误差函数,新误差函数针对BPSK信号而 设计。新算法采用分数间隔均衡模型,有效地加快了SRCMA算法的收敛速度。水声信道仿真实验 表明,该算法性能稳定,收敛速度快,适用于快速变化信道的盲均衡和水声通信数据的实时恢复。     

基于压缩感知和粒子滤波的OFDM超宽信道估计

针对通信系统中的正交频分复用(Orthogonal frequency division multiplexing, OFDM)超宽信道具有的稀疏多径和含噪声特征,将信道估计问题转换为稀疏信号的重构和优化问题,设计了一种基于压缩感知理论和粒子滤波的OFDM信道估计方法。首先定义和描述了OFDM数学模型;然后在对压缩感知理论模型研究的基础上,采用改进的正交匹配算法对OFDM超宽信道进行重构,为了进一步减少信道重构的误差,将由于正交匹配算法得到的重构信道作为初始的粒子,并将OFDM数学模型转换为动态参数模型,并通过粒子滤波来更新模型中的参数和频率响应,通过不断迭代获得信道的估计值。为了验证文中方法的优越性,将文中方法与经典的正交匹配算法与粒子滤波算法进行比较,结果表明：文中方法能有效地对含噪声的稀疏信号进行估计,具有较小的重构误差,且与其它方法相比,具有较小的归一化均方误差。     

Theoretical analysis and simulation of conjugate heights for dual-conjugate AO system in lidar

A multi-conjugate adaptive optics （MCAO） can offer a possibility of widening field of view （FOV） characterized by the isoplanatic angle, and the choose of conjugate height becomes a basic problem for MCAO, which influences the size of iosplanatic angle. Considering the application of lidar, the isoplanatic angle＇s expressions of two deformable mirrors （DMs） MCAO for uplink and downlink are deduced. The effects of conjugate heights for dual-conjugate AO are thoughtfully discussed, and the isoplanatic angles are further analyzed. The results show that the isopanatic angle varies with the conjugate height and reaches the maximum as the conjugate height is at the optimal altitude. Moreover, the optimal conjugate height changes with the propagation distance.     

Quick single-photon detector with many avalanche photo diodes working on the time division

Due to the limit of response speed of the present single-photon detector, the code rate is still too low to come into practical use for the present quantum key distribution (QKD) system.A new idea is put up to design a quick single-photon detector.This quick single-photon detector is composed of a multi-port optic-fiber splitter and many avalanche photo diodes (APDs).Au of the ports with APDs work on the time division and cooperate with a logic discriminating and deciding unit driven by the clock signal.The operation frequency lies on the number N of ports, and can reach N times of the conventional single-photon detector.The single-photon prompt detection can come true for high repetition-rate pulses.The applying of this detector will largely raise the code rate of the QKD, and boost the commercial use.     

Characterization of PolyA and PolyC mismatches by Raman spectroscopy

A.C mismatches are studied by Raman spectral characterization of PolyA, PolyC, and their equimolar complex in solution of 0.14 mol/L Na ,pH7.0.Experimental results show that A·C mismatches occur to be A/B (mainly A) conformers, and unlike Watson-Crick base pairing, this kind of mismatches is stabilized by only one hydrogen bond involving cytosine N4H2 and adenine N7.The formation of A·C complex makes the base stacking interactions much stronger, and conformation of the backbone more ordered, which leads to obvious Raman hypochromic effect with some shifts in corresponding bands.     

Improvement of four-wave mixing-based wavelength conversion efficiency in dispersion shifted fiber by 40-GHz clock pumping

40-GHz clock modulated signal as a pump to improve the efficiency of four-wave mixing (FWM)-based wavelength conversion in a 26.5-km dispersion shifted fiber (DSF) is investigated. The experimental results demonstrate that the conjugated FWM component has higher intensity with the clock pumping than that with the continuous-wave (CW) light pumping. The improvement of FWM-based wavelength conversion efficiency is negligible when the pump power is less than Brillouin threshold. But when the pump power is greater than Brillouin threshold, the improvement becomes significant and increases with the increment of pump power. The improvement can increase up to 9 dB if pump power reaches 17 dBm.     

Multi-pulse operation of a Kerr-lens mode-locked femtosecond laser

Our experimental results show that the presence of a proper amount of negative group velocity dispersion is essential to multi-pulse operation of a Kerr-lens mode-locked femtosecond laser. We demonstrate that the pulse separations and the number of pulses contained within a cavity round trip are strongly dependent on the initial perturbations. The results allow us to get a better understanding on the influences of the convoluted self-phase modulation and intra-cavity dispersions on the stable multi-pulse oscillation in a Kerr-lens mode-locked femtosecond laser.     

Propagation of Helmholtz-Gauss beams in weak turbulent atmosphere

Based on the Rytov approximation of light propagation in weak turbulent atmosphere,the closed-form expressions of field and average irradiance of each one of the four fundamental families of Helmholtz-Gauss (HzG)beams:cosine-Gauss beams,stationary Mathieu-Gauss beams,stationary parabolic-Gauss beams,and Bessel-Gauss beams,which are propagating in weak turbulent atmosphere,are obtained.The results show that the field and average irradiance can be written as the product of four factors:complex amplitude depending on the z-coordinate only,a Ganssian beam.a factor of complex phase perturbation induced by atmospheric turbulence,and a complex scaled version of the transverse shape of the non-diffracting beam.The effect of weak atmospheric turbulence on irradiance distribution of the HzG beam can be ignored.     

An effective method for reducing speckle noise in digital holography

An effective method for reducing the speckle noise in digital holography is proposed in this paper.Different from the methods based on classical filtering technique,it utilizes the multiple holograms which are generated by rotating the illuminating light continuously.The intensity images reconstructed by a series of holograms generated by rotating the illuminating light possess different speckle patterns.Hence by properly averaging the reconstructed intensity fields,the speckle noises can be reduced greatly.Experimental results show that the proposed method is simple and effective to reduce speckle noise in digital holography.     

Influence of purity of HfO2 on reflectance of ultraviolet multilayer

The impurities in two kinds of HfO2 materials and in their corresponding single layer thin films were determined through glow discharge mass spectrum technology and secondary ion mass spectrometry(SIMS) equipment respectively.It was found that ZrO2 was the main impurity in the two kinds of HfO2 either in the original HfO2 materials or in the electron beam deposited films.In addition,the difference of Zr content in the two kinds of HfO2 single laver films was much laxger than that of the other impurities such as Ti and Fe.which showed that it was just ZrO2 that made the difference between the optical performance of the film products including the two kinds of HfO2.With these two kinds of HfO2 and the same kind of SiO2.we deposited HfO2/SiO2 multilayer reflective coatings at the wavelength of 266 nm.Experimental results showed that the reflectances of these two mirrors were about 99.85% and 99.15% respectively,which agreed well with the designed results what were based on the optical constants obtained from the corresponding single layer thin films.     

Speech enhancement by array crosstalk resistant ANC and spectrum subtraction

Microphone array-based speech enhancement has great importance for speech communications and speech recognition. To reduce the aperture of the microphone array and to increase the effect of the speech enhancement will greatly broaden the application areas of the microphone array. An array crosstalk resistant adaptive noise cancellation method is therefore presented. And then an improved spectral subtraction algorithm is further cascaded to obtain better enhancement results. Theoretic analysis and experiments indicate that the proposed scheme needs only a very small microphone array while it simultaneously achieves a higher SNR improvement. Besides, the proposed scheme can be used in many noisy environments and is easy for real-time implementation.