关于山区农村公路最大纵坡与坡长限制的探讨

文章根据我国目前公路工程技术标准,通过对重庆地区山区农村公路的纵坡进行调查,分析了山区农村公路的特点和功能,探讨适合山区农村公路最大纵坡与坡长的设计方法。     

数字移动无线电无线传输技术分析

针对DMR-TD和DPMR-FD的底层无线传输系统体制进行详细介绍和对比;通过误比特率分析了2种制式无线传输系统的性能;最后建立点对点传输链路仿真平台,分析和比较了2种制式无线传输的误比特率性能。     

Speckle reduction based on contourlet transform using scale adaptive threshold for medical ultrasound image

A new speckle suppression method in contourlet domain was presented. By modeling the subband contourlet coefficients of the ultrasound images after logarithmic transform as generalized Gaussian distribution (GGD), we gave a scale-adaptive threshold in Bayesian framework. Experimental results of both synthetic and clinical ultrasound images show that our method has a better performance on speckle suppressing than the wavelet-based method while well preserving the feature details.     

Survey and empirical evaluation of nonhomogeneous arrival process models with taxi data

Arrival processes are important inputs to many transportation system functions, such as vehicle prepositioning, taxi dispatch, bus holding strategies, and dynamic pricing. We conduct a comprehensive survey of the literature which shows that many transport systems employ basic homogeneous arrival process models or static nonhomogeneous processes. We conduct an empirical experiment to compare five state of the art arrival process short term prediction models using a common transportation system data set: New York taxi passenger pickups in 2013. Pickup data is split between 672 observations for model estimation and 96 observations for validation. From our experiment, we obtain evidence to support a recent model called FM‐IntGARCH, which is able to combine the benefits of both time series models and discrete count processes. Using a set of seven performance metrics from the literature, FM‐IntGARCH is shown to outperform the offline models—seasonal factor method, piecewise linear model—as well as the online models—ARIMA, Gaussian Cox process. Implications for operating data‐driven “smart” transit systems and urban informatics are discussed. Copyright © 2016 John Wiley & Sons, Ltd.     

基于一种改进粒子滤波算法的目标跟踪研究

为了解决非线性、非高斯系统目标跟踪问题,研究了一种新的滤波方法——高斯粒子滤波算法。通过基于重要性采样和蒙特卡罗模拟方法得到一高斯分布来近似未知状态变量的后验分布。并讨论了此算法在机动目标非线性转弯运动中的跟踪应用,与粒子滤波算法相比,其优点是不需要重采样步骤。在闪烁噪声下比较了高斯粒子滤波器、粒子滤波器和扩展卡尔曼滤波器在滤波精度、运算时间等方面的差异,仿真结果表明该算法性能优于其他算法。