基于UKF的只测方位TMA中数据率因素影响的仿真研究

应用无味卡尔曼滤波(UKF)来解决只测方位目标运动分析(BO-TMA)问题,研究了其中数据率因素的实际影响.提出了一种对估计标准差及均方根误差(RMSE)进行归一化的新方法,并据此经过仿真分析揭示了估计的标准差及RMSE与数据率之间存在着简单的1/2次幂的反比关系;而同样的结论在EKF中则无法得到.     

Finite-precision analysis of a covariance algorithm for leastsquares FIR filtering and AR modeling

A numerically stable, fast, order-recursive algorithm for solving the covariance problem in signal modeling is described. The propagation of finite arithmetic errors as well as data acquisition errors is studied in detail. First, linearization of the main algorithmic recursions is carried out. Then, a suitable transformation converts the resulting state equations of the accumulated errors into their residual form. Subsequently, bounds for the residuals are computed. The derivation of these bounds depends heavily on the Levinson type structure of the algorithm and the low displacement rank of the problem. The main result is that the algorithm is weakly numerically stable. The proposed order-recursive algorithm is subsequently utilized as a block adaptive method. Its performance is also demonstrated by long run simulations     

Finite difference methods for the analysis of integrated optical waveguides

A finite difference method based on a Crank-Nicolson discretisation procedure has been implemented and applied to the analysis of propagation of optical beams in dielectric waveguides. It is based on a new formula which takes into account the correct boundary conditions. Comparisons with the well known BPM technique show a definite improvement in computer time saving, accuracy and ease of use.<>     

Recursive least squares identification methods for multivariate pseudo-linear systems using the data filtering

This paper concerns the parameter identification methods of multivariate pseudo-linear autoregressive systems. A multivariate recursive generalized least squares algorithm is presented as a comparison. By using the data filtering technique, a multivariate pseudo-linear autoregressive system is transformed into a filtered system model and a filtered noise model, and a filtering based multivariate recursive generalized least squares algorithm is developed for estimating the parameters of these two models. The proposed algorithm achieves a higher computational efficiency than the multivariate recursive generalized least squares algorithm, and the simulation results prove that the proposed method is effective.     

面向车道线图像识别的多种滤波方式对比分析

针对图像预处理的结果会影响车道线识别精度和速度的问题,文中选取二维小波包分解滤波、中值滤波和锐化滤波对某一汽车常用工况下的车道线图像分别进行滤波降噪,采用Sobel算子对未经滤波处理和经过3种滤波处理的车道线图像进行了边缘检测。结果显示二维小波包分解滤波处理后的图像能识别的车道线特征点数目最多,中值滤波处理后的图像能识别的车道线特征点占比最高,锐化滤波处理后的图像识别速度最快。     

基于像素与子块的背景建模级联算法

针对子块级背景建模方法无法保证所提取前景形状的精确性及像素级背景建模方法无法有效处理非平稳场景的问题,提出了一种背景建模分层模型,首先采用文中子块级建模算法得到较为粗糙的背景区域和前景区域,然后利用混合高斯模型对特定图像区域执行像素级的前景提纯或背景模型更新操作,2种不同层次的算法通过非对称前向反馈机制进行级联。实验结果表明,所提分层模型在能够有效处理非平稳场景的同时保证了所提取前景形状的精确性,且对光照突变不敏感,建模效果优于级联算法中任一独立算法,而处理时间小于2种独立算法处理时间之和,满足了实时处理要求。     

Symbolic analysis methods for averaged modeling of switching powerconverters

Symbolic analysis methods for the averaged modeling of switching power converters are presented in this paper. A general averaging method suitable for computer-aided modeling is discussed first. Then, a symbolic analysis package that uses this averaging method to automatically generate an analytical averaged model for a switching power converter is described. The package is implemented using the computer algebra system Mathematica and can be used for modeling DC/DC power converters employing different switching techniques, including hard-switching pulse-width modulation (PWM), quasi-resonant soft switching, and soft transition. Several examples are provided to demonstrate the applications of the package. Further applications of symbolic analysis methods in power electronics are also discussed     

Comprehensive performance modeling and analysis of multicasting in optical networks

Multicasting is becoming increasingly important in today's networks. In optical networks, optical splitters facilitate the multicasting of optical signals. By eliminating the transmission of redundant traffic over certain links, multicasting can improve network performance. However, in a wavelength-division multiplexed (WDM) optical network, the lack of wavelength conversion necessitates the establishment of a single multicast circuit (light-tree) on a single wavelength. On the other hand, establishing several unicast connections (lightpaths) to satisfy a multicast request, while requiring more capacity, is less constrained in terms of wavelength assignment. The objective of the paper is to evaluate the tradeoff between capacity and wavelength continuity in the context of optical multicasting. To this end, we develop accurate analytical models with moderate complexity for computing the blocking probability of multicast requests realized using light-trees, lightpaths, and combinations of light-trees and lightpaths. Numerical results indicate that a suitable combination of light-trees and lightpaths performs best when no wavelength conversion is present.     

近红外光谱分析中建模样品优选方法的研究

结合牛奶成分近红外光谱测量系统的实例,在已定的浓度范围内针对牛奶中脂肪、蛋白质、乳糖三成分采用正交设计法优选参与建模的样品.研究中首次利用正交表的\     

光学软件热分析方法和消热差镜头设计

光学系统的性能易受工作温度的变化影响,因此设计光学系统时需要进行热分析并采用无热化设计方法进行优化。本文研究了工作温度对光学系统性能的影响,介绍了光学元件的热分析参数,并讨论了光学系统的结构参数与温度变化之间的关系,然后指出了Code V软件在热分析功能上存在的不足,在研究热分析的原理后,通过编写宏文件的方式,分别从光学元件间隔计算和光学材料折射率计算两个方面进行改进,最后利用Code V软件进行了一款消热差镜头的优化设计工作。该镜头的焦距为28mm,F数为22,视场角为160°,工作温度范围在-20～85℃。设计结果表明,在整个工作温度范围内,系统成像质量良好,满足使用需求。     

Temporal reshaping of optical pulses using quadratic spatialsoliton generation and spatial filtering

We perform a temporal reshaping of laser pulses by means of quadratic spatial soliton excitation combined with a spatial filtering of the output beam. We demonstrate that the device presents a behavior similar to the one of a saturable absorber, and numerically investigate the parameters giving optimum temporal filtering     

光学准直测量方法与精度分析

光学准直测量技术具有非接触、高准确度和高灵敏度的特点,广泛应用于航空航天、精密制造安装等工业领域.为了在精密工业测量中通过准直建立和维持高精度的坐标系,对基于高精度电子经纬仪和全站仪的光学准直测量方法作了总结,提出了激光法、ATR法等新的准直方法.在实验室中对各种方法进行了平面镜的准直实验,利用Leica TM5100...     

Theoretical and experimental study of the analysis and modeling ofintegrated optical components

Using a mode-matching technique, a modular microwave equivalent circuit incorporating both guided and continuum spectra has been developed to model open guided-wave integrated optical components accurately with limited computational effort. The accuracy of the analysis is verified by comparison with other methods of analysis, and by experiments performed on GaAs homojunction rib waveguides, directional couplers, and three-guide couplers. The limitations of approximate theories for the analysis of coupled structures are also identified     

Multivariate statistical methods for modeling and analysis of wafer probe test data

Probe testing following wafer fabrication can produce extremely large amounts of data, which is often used to inspect a final product to determine if the product meets specifications. This data can be further utilized in studying the effects of the wafer fabrication process on the quality or yield of the wafers. Relationships among the parameters may provide valuable process information that can improve future production. This paper compares many methods of using the probe test data to determine the cause of low yield wafers. The methods discussed include two classes of traditional multivariate statistical methods, clustering and principal component methods and regression-based methods. These traditional methods are compared to a classification and regression tree (CART) method. The results for each method are presented. CART adequately fits the data and provides a "recipe" for avoiding low yield wafers and because CART is distribution-free there are no assumptions about the distributional properties of the data. CART is strongly recommended for analyzing wafer probe data.     

Interrogation of wavelength multiplexed fiber Bragg gratings using spectral filtering and amplitude-to-phase optical conversion

A technique for interrogating multiplexed FBG sensors using all-fiber low-cost devices is demonstrated. It is based on spectral filtering employing a fused biconical wavelength-division multiplexer and on amplitude-to-phase optical conversion to perform power referencing. Four FBG sensors are wavelength multiplexed in the network, and a 3-nm-wide tunable optical filter is employed at the detection block for sensor demultiplexing. With this technique an operation range of more than 2 nm is demonstrated for the sensors with achievable wavelength static resolution ranging from 1.9 to 13.4 pm/Hz/sup 1/2/ with no observable hysteresis. As for power referencing, the system is proven to be unaffected by power variations as high as 75% of the total power launched by the source. Finally, output-phase variations due to crosstalk are shown to be under 1% of the total output phase range, with more than 29-dB optical isolation between channels.     

Accurate analysis and modeling of laminated multilayered 3-D optical waveguides

The theoretical investigation of waveguides having nonuniform cross-sections is an attractive and challenging problem which deserves serious interest. In this paper, we present a novel analysis of laminated multilayered three-dimensional waveguide, based on two modes: 1) a new coupled transmission line approach that considers the sloping of the layers along the longitudinal direction and 2) a transmission line matrix integral equation (TLMIE) modeling that complete and extends the investigation of the field propagation. In method 1), we neglect radiation modes and their EM coupling. All physical effects instead are accounted for by the full-wave TLMIE method. By using TLMIE, we validate the EM analysis and calculate TE/TM losses, arising from radiation modes.     

Energy analysis using semi-Markov modeling for the base station in 5G networks

With the increasing prevalence of wireless sensor networks, the uninterrupted operation of these networks becomes essential. To ensure continuous functionality, wireless networks rely on available base stations (BSs). However, the persistent operation of BSs comes at the cost of substantial energy consumption. Consequently, given the surge in wireless network traffic and the necessity for uninterrupted BS availability, energy efficiency within the BS becomes a concerning issue. To address this, the study employs a semi-Markov model to depict the availability of the BS, with states corresponding to the failures of its components (baseband unit, remote unit, and software module). The analysis yields a steady-state solution, with reward rates assigned to each state based on the energy consumption of individual BS components. This approach enables the determination of the expected energy consumption within this model. Additionally, the BS's throughput is assessed using an M/G/1 queueing model with server breakdown.     

Thin-film tunable optical filtering using anisotropic and noncollinear acoustooptic interaction in LiNbO3waveguides

Theoretical and experimental studies of optical filtering which utilize anisotropic and noncollinear acoustooptic interaction in aY-cut LiNbO3waveguide are reported. A guided-light beam from either an He-Ne laser at 6328 Å or an argon laser at around 5000 Å, propagating at an angle centering around 70° from theZ(c)axis of the LiNbO3crystal, was Bragg diffracted by the surface acoustic wave with 500 MHz center frequency and propagating at 16° from thexaxis of the crystal. High optical resolving power, large optical angular aperture, and good spatial separation between the filtered light and the unfiltered light have been simultaneously achieved. An optical passband of 16 Å and an angular aperture of 9° have been measured for the case in which the undiffracted and diffracted light propagate in TE0mode and TM0mode, respectively. Furthermore, by varying the acoustic frequency from 350 to 670 MHz, the filtered optical wavelength may be tuned from 8300 to 5000 Å.     

Enhancing the dynamic range and DGD monitoring windows in DOP-based DGD monitors using symmetric and asymmetric partial optical filtering

We propose and demonstrate a new type of degree-of-polarization (DOP)-based differential-group-delay (DGD) monitor using an optical filter such that the DGD monitoring range and DOP dynamic range are dramatically increased. We apply this technique to varying pulsewidth return-to-zero (RZ), carrier-suppressed RZ (CSRZ), and alternate-chirped RZ (ACRZ) signals and show that by optimally setting the position, bandwidth, and shape of a filter, we can double the DGD monitoring range compared to traditional DOP-based DGD monitors. Using our technique, the DGD monitoring ranges for 10, 20, and 40 Gb/s /spl sim/12.5-ps pulsewidth RZ signals are increased by 32, 33, and 12 ps, respectively. We also show that a narrow-band optical filter, offset from the center of the optical spectrum by the bit-rate frequency, can double the dynamic range of DOP-based DGD monitors for non-RZ (NRZ) signals.     

On the duality between fast QR methods and lattice methods in leastsquares adaptive filtering

The authors show that fast QR methods and lattice methods in least squares adaptive filtering are duals and follow from identical geometric principles. Whereas the lattice methods compute the residuals of a projection operation via the forward and backward prediction errors, the QR methods compute instead the weights used in the projections. Within this framework, the parameter identification problem is solved using fast QR methods by showing that the reflection coefficients and tap parameters of a least squares lattice filter operating in the joint process mode are immediately available as internal variables in the fast QR algorithms. This parameter set can be readily exploited in system identification, signal analysis, and linear predictive coding, for example. The relations derived also lead to a fast least squares algorithm of minimal complexity that is a hybrid between a QR and a lattice algorithm. The algorithm combines the order recursive properties of the lattice approach with the robust numerical behavior of the QR approach