适用于海洋动态观测设备嵌入式系统的低功耗管理预测模型

能耗是制约海洋设备在水下工作时长的关键因素。为进一步降低海洋动态观测设备嵌入式系统的动态功耗, 本文针对前人提出的用于预测空闲时间的指数平滑算法所存在的权重系数基于凑数法确定、算法难以适应大波动等问题, 设计了一种新的权重系数, 并构建了一种自适应的低功耗管理预测模型。当模型检测到预测的空闲时间超过工作和休眠状态切换的时间阈值后, 中央处理器关停系统的部分外设, 使系统进入低功耗休眠状态。仿真和单片机实验均表明,本文提出的低功耗管理预测模型能够有效地提高对处理器工作的空闲时间预测的准确性, 且面对突发状况具有良好的自适应性, 可显著降低嵌入式系统的功耗, 有效延长设备的工作时间。     

Estimation of the Mesozoic geological time scale

Geological time scales are constructed by combining the stratigraphic record with radiometric dates and their standard deviations. The stratigraphic record encompasses litho-, bio-, chrono-, and magnetostratigraphy. The statistical methods employed should embody concepts and data available for the systems considered. Recently, in order to estimate the ages of 31 Mesozoic stage boundaries, use was made of a database with chronostratigraphic classifications for 340 dates, biostratigraphic data including ammonite subzones, and information on seafloor spreading. This paper is primarily concerned with the propagation of errors through the successive steps of the data analysis. The following stepwise approach was taken for combining the different types of data: (1) maximum likelihood estimation with windows set around prior stage boundary estimates, (2) averaging of estimates with variable precision including magnetochronologic data, and (3) calibration by means of cubic smoothing splines assuming equal duration of ammonite subzones. The end product is a time-scale in which the stage boundary ages are accompanied by approximate 95 per cent confidence intervals.     

Smoothing unit vector fields

Data, each consisting of a unit vector and a position, are modeled as a smooth unit vector field plus random directional errors; the smooth unit vector field is estimated by fitting a spline to observations. The estimate is nonlinear; it is obtained with an iterative procedure in which, at each step, a least-squares smoothing spline is fitted to a set of pseudovalues. The resulting estimate is exemplified with a data set extracted from the literature in geology. The proposed estimate is compared, using the same data set with that obtained through suggestions of other authors, and is found to have attractive qualities. The use of plots of the resulting estimate to find the appropriate value of the smoothing parameter is emphasized throughout.     

Automatic soil-boundary location from transect data

Spatially distributed soil data possess a short-range erratic variation, an irregular longer range pattern, and maybe multivariate. In order to reveal a pattern or meaning in them, they are usually classified by drawing boundaries. A method is described for determining boundaries automatically on transects. A small portion of a sampled transect is taken and divided about its midpoint, and Mahalanobis' generalized distance, Dor D²,between the two halves calculated from the sample data. The procedure is repeated for portions of the same length at positions one-sampling interval apart along the transect. High peaks on the resultant series of D² identify the boundaries. The length of portions is set equal to, or somewhat less than, the expected average distance between boundaries, and is determined by constructing correlograms of principal components. The lag distance over which fairly steady decay occurs is related closely to the distance between boundaries. The procedure is illustrated with data from a 6-km transect in Oxfordshire and shows good agreement with boundaries drawn by combined air-photo interpretation and field judgment. A means of extending the procedure to two dimensions is suggested.     

利用数据挖掘的滑坡监测数据处理流程

为了快速而准确地分析降雨型滑坡的变形趋势,以指数平滑法为数学基础,从滑坡的实际演化阶段出发,建立外界主要诱发因素与模型参数的关联,引入月累积降雨量作为模型参数动态评估因子,对白家包滑坡90期累积位移数据进行了拟合及预测。最终拟合的累计位移平均绝对误差和相关系数分别为11.346和0.933。与传统的静态参数方法相比,这种方法更符合降雨型滑坡发展的一般规律,预测精度更高。     

GPS单频伪距相位平滑的离散性分析

基于Hatch滤波方法进行伪距相位平滑的研究,对GPS单频伪距相位平滑的离散性进行理论分析,给出移动窗口分段平滑方法的处理方案.采用自编软件,利用IGS跟踪站数据,对单频伪距相位平滑的离散性进行数据验证;对基于Hatch滤波的移动窗口分段平滑方法的可行性和效果进行分析,结果表明:移动窗口分段平滑方法可以较好地控制单频伪...     

用基于平滑技术的时频分析方法对地震资料去噪的研究

本文提出了一种新的时频分析方法—基于平滑技术的时频分析方法,并给出了该方法的基本原理以及用该方法对地震观测信号进行去噪的具体算法.它以信号的平滑处理为基础,与传统去噪手段相比,具有物理意义清晰且运算简单的优点.实验结果表明,利用该时频分析方法可以极大地提高远距离地震观测信号的信噪比,从而为远距离地震信号的检测提供了有力的工具.