Computational methods for performance evaluation of a statisticalmultiplexer supporting bursty traffic

A statistical multiplexer supporting a number of bursty sources is modeled as a discrete time, single server queueing system with an infinite buffer. The probability generating function (PGF) method is used to analyze the queueing behavior. The PGF method requires the determination of a large number of boundary values and, hence, the roots of the characteristic equation. An iterative algorithm to evaluate the characteristic roots is proposed. When the arrival process is a superposition of independent processes, a decomposition approach is used to reduce the state space involved in the computational algorithm. Additionally, the computational algorithm is made efficient through the establishment of conditions under which all the roots are either real or nonnegative real numbers. A set of equations to recursively compute the moments of the queue length are established. Sample applications of the computational methods to evaluate the performance of a multiplexer supporting voice and video sources, modeled by two-state Markov and L-state MMPP processes, respectively, demonstrate the viability of the proposed methods     

三站时差定位模糊问题解决方法

三站时差定位系统对辐射源进行定位过程中会出现定位模糊及无解的情况,通过对模糊无解特征的研究,发现了长期对时差定位模糊无解认识存在的误区.基于模糊无解的特征,提出了模糊问题的解决方法.仿真结果表明,不需增加系统复杂性,即可有效的解决定位模糊问题.     

海杂波FRFT域分形特征判别及动目标检测方法

该文研究了海杂波在分数阶Fourier变换(FRFT)域的分形特征,提出了一种基于分形特征差异的联合动目标检测方法。首先,分析了海杂波数据在FRFT域的统计特性,通过对不同极化方式下分形曲线的仿真分析,得到海杂波在FRFT域满足自相似性。其次,给出了分形参数的提取方法和无标度区间,并分析了变换阶数对分形参数估计的影响。最后,利用临近距离单元或临近时刻的雷达回波信号在FRFT域的分形维数和斜距的差值作为检测统计量,经不同极化方式下的海杂波数据验证,表明算法不仅具有良好的微弱动目标检测能力,而且能够准确估计目标的运动状态。     

Delay analysis of interval-searching contention resolution algorithms

The intelligent design of a random multiple-access communication system involves analyzing the tradeoffs among throughput rate, transmission delay, and stability subject to additional restrictions imposed by distributed processing requirements. Interval-searching contention resolution algorithms have been found to achieve high throughput, and simulations have shown that they also possess short average delay. A general approach to the delay analysis of interval-searching contention resolution is proposed based on solving an integral equation for the distribution of a quantity called the transmission lag. For a certain multibit feedback algorithm, this analytical technique leads to exact determination of the throughput-delay characteristic. For the celebrated "0.487" algorithm, the method yields upper and lower bounds to the curve of expected delay versus throughput that are in close agreement with simulation results.     

PV module characterization using Q-Rdecomposition based on the least square method

The determination of solar cell parameters (I-V characteristic) from experimental data was achieved by using the Q -R decomposition technique based on the least squares method, where all data points were considered. The algorithm used a three-parameter equation transformed from the original cell equation of five parameters. This method could be used to analyze the I-V characteristics of photovoltaic (PV) modules of various technologies under the natural conditions of implementation, and to help to establish the best sizing of a PV system and the best adaptation of a PV system to its environment     

Calculation of the Parameters of Ridge Waveguides

In this paper an algebraic expression which constitutes an approximation to Cohn's transcendental equation is given for the determination of the dominant-mode cutoff wavelength of ridge waveguides. A modified derivation of Mihran's equation for calculating the characteristic impedance of ridge waveguides is discussed. Based upon these formulas, nomography are constructed to permit the determination of these parameters with sufficient accuracy when the waveguide and the ridge dimensions vary. Experimental verification of the calculated cutoff wavelength is included.     

适合处理乘性噪声估计卫星姿态的非线性迭代滤波算法

针对带乘性噪声的星敏感器/陀螺非线性卫星姿态确定系统,提出了一种迭代MEKF(Iterative Multiplicative Extended Kalman Filter)姿态估计滤波算法.通过对带乘性噪声的非线性卫星姿态确定系统的状态方程和测量方程进行二次线性化迭代,并基于线性最小方差准则和投影公式,导出了姿态状态...     

基于静止、准静止双星TDOA／FDOA无源定位算法

针对由静止卫星、准静止卫星构成的无源定位系统，该文研究了利用到达时间差／到达频率差（TDOA／FDOA）联合对地球表面固定辐射源的无源定位算法。与迭代搜索法相比，该算法不需要初值，不用迭代运算，仅仅需要解4次多项式方程，因此该算法更有效。文中推导了定位方程的求解算法，分析了多项式方程的多根情况，并提出了相应的解决办法；最后进行了蒙特卡罗仿真，仿真结果表明该算法具有适应能力强、定位精度高的优点。     

A Big-data Inspired Precision Improvement Algorithm for Autonomous Navigation Based on Period Variable Stars

Periodic variable navigation can realize the integration of positioning, attitude determination, timing and other functions. As a novel autonomous navigation method, autonomous management and autonomous operation of spacecraft are the main direction of great significance to reduce the burden of ground measurement and control, to improve the viability of spacecraft, While, the precision of the navigation is very critical for the use of periodic variable navigation for the long range spacecraft. So, we propose a big-data inspired precision improvement algorithm in this paper. Period variable star phase time measurement is used as observation information, and accomplished by the orbital dynamics equation of spacecraft motion. According to the gathering of the sampling data and the sensor data, a self-learning system is trained with the parameters from the nonlinear filtering methods. Based on the Unscented Kalman Filtering, an autonomous navigation algorithm of period variable star is established to realize the navigation and positioning of spacecraft. Under the measurement conditions of a single sampling interval of 0.01s and the measurement precision of period variable star phase observation time of 10^??5s, It can be find that the navigation position determination precision can reach 400m, the speed determination precision can reach 0.3m/s, and the measurement precision can reach 10^??5s with our proposed algorithm.

     

一种高精度的BDS/INS紧耦合测姿算法

针对"北斗"卫星姿态测量系统在测姿过程中测姿精度和稳定性不高的问题,提出了"北斗"卫星导航系统(BDS)/惯性导航系统(INS)紧耦合姿态测量算法.该算法首先利用BDS观测量设计了BDS系统测姿误差模型;然后以INS状态误差方程为滤波系统状态方程,以载波相位为主要观测量设计了扩展卡尔曼滤波器,利用滤波器的输出实现对惯性导航测姿系统的辅助校正;最后采用静态测试、动态测试和遮挡测试验证该算法.该系统可以有效提高BDS测姿精度与输出频率,并且在静态条件下航向角测量精度可以达到0.15°.     

基于免疫算法的非等间隔梳状谱信号峰均功率比抑制研究

提出了一种采用免疫算法抑制非等间隔梳状谱信号峰均功率比的新方法。免疫算法是一种具有优异全局搜索特性的多目标优化算法,该特性可用于搜索非等间隔梳状谱信号的最优初始相位组合,极大限度抑制峰均功率比。相比解析代数式法,免疫算法具有不受梳状谱信号的谱线间隔和谱线数限制等优点,更具有通用性。     

基于特征描述子的匹配方法

利用一种效率和匹配率均较高且存储空间小的基于特征描述子的指纹识别算法,实现了指纹匹配且可应用到嵌入式系统。由于自动指纹识别系统一般在嵌入式系统上实现,对算法的复杂度、运算速度、存储空间需要等均有较高要求,因此选用普遍使用的基于细节特征的匹配算法。该算法运算速度快,一幅300×300像素的指纹图像,仅需几十个特征向量。实验证明,算法克服了点匹配计算量大、速度慢和参考点确定难等缺点,且对图像的旋转和平移具有较好的鲁棒性。可以使基于特征描述子的随机局部区域描述子特征的匹配性能进一步提高。     

Detection of chemical oxygen demand in water based on UV absorption spectroscopy and PSO-LSSVM algorithm

A method of detecting chemical oxygen demand (COD) of water based on ultraviolet (UV) absorption spectra is proposed. The modeling and analysis of the standard samples and the actual water samples are carried out respectively. For the standard solution samples, the univariate linear models based on single wavelengths and the partial least square (PLS) model based on synergy interval partial least square (SiPLS) and moving window partial least square (MWPLS) are established. For the actual water samples, different pre-processing methods are used. SiPLS and MWPLS are used to select the characteristic bands. The least squares support vector machine algorithm optimized by particle swarm optimization (PSO-LSSVM) algorithm is used to establish the prediction model, and the prediction results of various models are compared. The results show that the optimal model is PSO-LSSVM which uses SiPLS to select the characteristic bands of the first derivative spectra (preprocessing method). The determination coefficient of the prediction set is 0.963 1, and the root mean square error of prediction (RMSEP) is 2.225 4 mg/L. PSO-LSSVM algorithm has good prediction performance for the analysis of COD in actual water samples by UV spectra. This paper provides a new design idea for the research and development of water quality detection optical sensor.     

基于可见-近红外光谱特征波长选择的土壤有机质快速检测研究

选择光谱特征波长进行建模可以减少冗余波长的干扰,提高模型的预测精度。采用小波阈值消噪法对采集的104个土壤样本光谱数据进行了预处理,并通过间隔偏最小二乘法、无信息变量消除、连续投影算法和群智能算法等9种方法筛选了建模波长。结果表明,小波阈值消噪法能有效降低光谱中的噪声。利用波长选择方法筛选建模波长不仅能减少建模变量的个数,而且还能提高模型的预测精度,特别是离散粒子群优化算法利用26个波长进行建模,预测决定系数达到了0.81,预测的相对标准误差为2.31。实验结果证明,通过对光谱波长进行选择不但可以降低模型的复杂度,还能有效预测土壤有机质达的含量。     

Constrained Chebyshev design of FIR filters

In many filter-design problems, additional constraints are often imposed on the optimal filter in the sense of, say, minimal Chebyshev error norm. Based on the characteristic properties of the optimal filter for the Chebyshev design with frequency equation constraints, a modified Remez (MRemez) algorithm is proposed in this paper. The central problem of this paper is the constrained Chebyshev design of finite-impulse response filters with equation and inequality constraints in the frequency domain. By converting the problem into a series of Chebyshev design problems with equation constraints, an iterative MRemez algorithm which uses the MRemez algorithm as the computational core of the iteration is proposed, and the convergence of the algorithm is obtained. Design examples demonstrate the effectiveness and the fast convergence of the MRemez algorithm and the iterative MRemez algorithm.     

On the propagation of light waves in a multilayer planar dielectric waveguide

Dispersion equations for the eigenvalues of effective refractive index β of a planar dielectric waveguide supporting an optic TE wave are investigated. A relation between the traditional dispersion equation obtained on the basis of the characteristic-matrix method and the so-called multilayer equation is revealed. It is shown that all of the roots of the traditional dispersion equation are roots of the multilayer equation for the same problem. It is found that the roots of the multilayer equation may include the values of the refractive indices of inner layers of the waveguide and that these values are not the eigenvalues of quantity β.     

等离子体圆柱波导的频率相关性

通过给出的等离子体圆柱波导的精确特征方程,讨论了特征方程的特征值对频率的依赖。并且对特征值与厚度因子(α)的关系进行讨论,给出了在α1时的特征方程,该方程计算简便。进一步运用α1时的特征方程的解,提出了一种求解严格特征方程之特征值的近似方法。     

An Efficient Method for an Ill-Posed Problem — Band-Limited Extrapolation by Regularization

In this paper, a regularized spectral estimation formula and a regularized iterative algorithm for band-limited extrapolation are presented. The ill-posedness is taken into account. First the Fredholm equation is regularized. Then it is transformed to a differential equation in the case where the time interval is R. A fast algorithm to solve the differential equation is given by the finite difference and a regularized spectral estimation formula is obtained. Then a regularized iterative extrapolation algorithm is introduced and compared with the Papoulis and Gerchberg algorithm     

一维非线性光子晶体中电磁波传播的理论分析

考虑具有金属包层结构的一维非线性光子晶体,应用Maxwell经典电磁理论,建立了电磁波传播特性的理论分析模型,得到了其电磁场的全波解。根据电磁场在包层边界应满足的基本关系,建立了描述其带隙结构的特征方程,给出了特征方程迭代求解的算法描述,为电磁波传播特性数值仿真分析提供了理论基础。     

Algorithm for speech model root location

A novel algorithm for locating the roots of the speech model filter polynomial derived from LPC analysis is proposed. The technique is guaranteed to converge and can be implemented in a fixed time interval. When several iterations are performed, very accurate root estimation can be achieved