EXPERIMENTS ON THE GROUP GENERALIZATIONG OF CONTOUR LINES FOR TOPOGRAPHIC MAPS

This paper analyzes the advantages and disadvantages of two techni-cal lines for automatic group generalization of contour lines.The author suggeststhat it is possible to get faster and better generalization results if we simulate theintelligence of human experts in program designing,retrieve geomorphologicalstructural information using the input data of 2-D contour lines and derive andoutput the generalied 2-D results directly.     

自动和人工测定煤镜质组反射率的对比研究

对比分析了煤镜质组反射率人工测定与自动测定的各自特点,给出了与人工测定结果高度相关的自动测定方法和条件。测定结果表明,自动测定结果的重现性好于人工测定结果。;区分能力与人工测定相当。     

Monitoring of seismic events from a specific source region using a single regional array: A case study

In the monitoring of earthquakes and nuclear explosions using a sparse worldwide network of seismic stations, it is frequently necessary to make reliable location estimates using a single seismic array. It is also desirable to screen out routine industrial explosions automatically in order that analyst resources are not wasted upon detections which can, with a high level of confidence, be associated with such a source. The Kovdor mine on the Kola Peninsula of NW Russia is the site of frequent industrial blasts which are well recorded by the ARCES regional seismic array at a distance of approximately 300 km. We describe here an automatic procedure for identifying signals which are likely to result from blasts at the Kovdor mine and, wherever possible, for obtaining single array locations for such events. Carefully calibrated processing parameters were chosen using measurements from confirmed events at the mine over a one-year period for which the operators supplied Ground Truth information. Phase arrival times are estimated using an autoregressive method and slowness and azimuth are estimated using broadband f{-}k analysis in fixed frequency bands and time-windows fixed relative to the initial P-onset time. We demonstrate the improvement to slowness estimates resulting from the use of fixed frequency bands. Events can be located using a single array if, in addition to the P-phase, at least one secondary phase is found with both an acceptable slowness estimate and valid onset-time estimate. We evaluate the on-line system over a twelve month period; every event known to have occured at the mine is detected by the process and 32 out of 53 confirmed events were located automatically. The remaining events were classified as “very likely” Kovdor events and were subsequently located by an analyst. The false alarm rate is low; only 84 very likely Kovdor events were identified during the whole of 2003 and none of these were subsequently located at a large distance from the mine. The location accuracy achieved automatically by the single-array process is remarkably good, and is comparable to that obtained interactively by an experienced analyst using two-array observations. The greatest problem encountered in the single array location procedure is the difficulty in determining arrival times for secondary phases, given the weak Sn phase and the complexity of the P-coda. The method described here could be applied to a wide range of locations and sources for which the monitoring of seismic activity is desirable. The effectiveness will depend upon the distance between source and receiver, the nature of the seismic sources and the level of regional seismicity.     

Local Sensitivity Analysis of a Numerical Model of Volcanic Plinian Columns through Automatic Differentiation

Numerical simulation of geological phenomena are nowadays widely used to understand them. A good example are the numerous codes developed to model mass motion in different processes. Such models are approximations to the real phenomena because the physical conditions are simplified or because the values of the parameters intervening in the modeling are known only approximately. For this reason, an obligatory step in the application of these models is the assessment of their sensitivity to changes in the parameters. Sensitivity analysis is also required to evaluate the influence of the different input variables in the outcome of the model. In general this analysis is carried out by repeated computation of the model to different sets of input variables and settings of the model. A more fruitful procedure to carry out such analysis can be achieved by automatic differentiation. In this paper we illustrate such approach through its application to the model of an eruptive plinian column. The results of the analysis allow to assess, in a systematic and efficient manner, the relevance of the different boundary values and parameters of the model. The analysis reveals the effects on velocity, temperature, gas fraction, radius and ultimately column height, by changes in their boundary value (i.e. at the vent). The effect of changes in the value of the gas constants, density of pyroclasts and specific heat of the erupted material is also evidenced. Alternatively, the results can be regarded as a mean to estimate the values of the variables for different set of boundary values without recurring to new runs of the model. Automatic differentiation is shown to be a convenient scheme to obtain derivatives of model variables. This type of analysis forms in addition the basis for further work in inversion schemes.     

气象服务文本产品的自动生成

目前气象信息文本的自动生成技术主要有2种基于文字替换的CWF(Computer-Worded Forecasting)技术和基于知识库的KBTG(Knowledge-Based Text Generation)技术.使用CWF技术进行文本的自动生成,技术较成熟、容易实现.文中阐述了使用CWF技术进行文本的自动生成过程中涉及的3个关键技术①自动、定时生成预报文本;②定义预报文本的输出格式;③使预报文本的表达更接近自然语言.     

Study of Wave and Tide Influence on Slope Stability of the Navigation Channel of Tianjin Port

The Tianjin Port is the largest man-made port in China.Since the navigation channel of the Tianjin Port is constructed by dredging,a very important problem,as many people concerned,is the submarine slope stability.As the environment on land is different from that in submarine,it is necessary to evaluate the influence of the environmental loading,such as wave and tide,on the stability of navigation channel slope.In the present study,based on the observed results,the characteristics of the navigation channel slope are summarized,and the causes of creating the special slope shape are analyzed.The roles of waves and tides are evaluated,and failure mechanics are discussed to helq us predict what will happen in the future.     

水下机器人运动的S面控制方法

由于水下机器人的强非线性以及系统存在不确定性，同时考虑到港湾环境下水声的噪声大，因此，水下机器人进行精确作业时的运动控制一直是其实用化过程中困扰人们的问题，通常水下机器人的控制方式有PID控制器，神经网络控制器和模糊逻辑控制器三种，但是，由于这三种方法在实际应用中都存在一些参数难以确定的缺陷，为了解决这一问题，本文从模糊逻辑控制方式出发，借鉴PID控制的结构形式，推导出一种全新而简单有效的控制方法，定义为S面控制法，从水下机器人的水池试验和海上实验来看，不论是定点的控制精度还是运动过程中的控制效果都较令人满意，尤其是在风浪，潮流都比较大的海上实验中得到验证，鲁帮性很好。     

汕头港外航道适航水深的研究和运用

通过对现场测量资料和淤泥流变特性试验结果的分析,研究了可航容重的特性并探讨了粘性颗粒粒度含量对可航容重的影响,提出了汕头港外航道适航水深的应用技术指标。应用情况表明适航水深的研究取得所期望的功效。     

GPS导航的技术改进

在完善ＧＰＳ导航方式的过程中，引入重要目标点的概念，并以此为思想指导，修改原导航程序，使之多个目标点明确、直观地显示于驾驶台及船上各实验室的计算机显示屏幕上。从而提高船舶停靠站位的精度，并使船舶停靠原站位具可重复性。这样，满足了海上地质勘测和石油化探中多点间歇采样的需要，同时，亦提高了工作效率并有利于船舶航行安全。     

BD卫星星间链路定轨结果及分析

我国新一代北斗导航系统试验卫星搭载了高精度星间链路载荷并已经得到了实测数据。本文给出了星间链路数据预处理方法,并介绍了星间链路数据独立定轨和星间Ka测量与L波段数据联合定轨的方法和初步结果。利用3颗试验卫星和1个地面Ka站在轨试验,结果表明:独立采用星间链路定轨,其结果 R方向误差小于0.5m;星间链路数据与L波段数据联合定轨,其对L波段定轨结果有显著改善,轨道R方向误差小于0.3m;星间测量设备时延标校精度优于0.1m。