主动源勘探中震源编码与解码方法

依据人工主动震源的可控性,引入通讯中的编码原理,采用震源编码技术能够有效提高小当量人工震源的探测深度和信号接收距离。笔者分析研究了主动源勘探中的震源编码与解码方法,主要做了以下工作:①分析研究了震源信号自相关函数的基本性质,探讨了利用自相关函数峰值间的零值区进行信号检测的可能性,研究表明编码方法能够通过相关增加有效信息的检测范围,提高监测能力;②研究了震源编码的三种基本方式,分析了它们的旁瓣压制效果,通过不同激发能量的源在不同时刻重复激发建立编码震源,信号能够在相关峰值和相关旁瓣间有效检测出;③探讨了迭代相关法解码的基本原理,编码方法能够大幅度提高地震探测能力,利用小能量震源获得大的探测距离和高分辨率,具有很强的抗干扰能力。     

Remote-sensing data-based Archaeological Predictive Model (APM) for archaeological site mapping in desert area,South Morocco

Morocco hosts numerous archaeological sites, some of which are part of the UNESCO world heritage. Many of these sites, especially funerary mounds also called tumuli, or rock engravings and ceramics, are located in remote areas with limited access, particularly in the Saharan Morocco desert. We developed a remote sensing and GIS model to identify areas with high potential for hosting archaeological sites in the Awserd region of southern Morocco. A field campaign in a “reference site” zone of 21 km² has revealed 233 archaeological sites. Here we use satellite images and Digital Elevation Models to examine with various techniques (spatial analysis, statistical techniques, and fuzzy logic functions) the relations between the distribution of the archaeological sites and geo-environmental variables such as ground geology, topographic elevation and slope, orientation (aspect), and distance to water sources. We derive empirical relations that reveal that the distribution of archaeological sites depends on the above geo-environmental variables. We then use the empirical relations to anticipate the potential locations of archaeological sites in a region of 980 km² enclosing the reference site area. The model proves capable of predicting 582 sites in the larger region. Subsequent field observations there confirmed that about 80% of the model anticipations were correct. Our Archaeological Predictive Model (APM) can be scaled to larger areas and varied geographic settings, and hence can be a useful guide for archeological studies in desert regions.     

一种条形二进制编码标尺的数字水准仪系统设计与实验

目前,世界上极少数的公司垄断了数字水准仪的生产,他们的专利保护主要集中在电子读数原理和标尺编码结构上。本文在此背景下,提出了一种新的基于二进制编码的标尺编码方案。该方案将使用的刻度标尺横线进行二进制编码,水准仪部分采用面阵CCD采集标尺图像,利用快速数字图像处理算法进行水平中心定位读数。理论分析和实验表明,该设计具有可行性,在标尺不同位置和椒盐噪声点数小于60 K的时候有着100%的识别率。     

GIS和DVS的集成与应用

随着社会的进步和发展,地理信息系统也需要根据用户的需求开发更多的功能。数字视频服务器是一种对音视频数据进行编码处理并完成网络传输的专用设备,可以实现远程监控、语音对讲等功能。将它与GIS结合,可以为GIS提供更加实时的音视频专题信息,GIS也可以对这些信息做出更加科学系统的分析处理,辅助用户做出相应的决策。基于DVS技术的GIS的设计与实现,很好地解决了银行保安、道路监控等实际问题,加快数字城市的建设脚步。     

数字视频加密技术发展现状及展望

对视频加密所涉及到的基本原理和技术、存在的问题和一些重要的方法、当前研究热点及发展趋势等进行了全面介绍和综述;通过分析视频加密方法的特点,指出针对压缩视频数据信源特征而采用的选择性加密技术是未来的主要研究方向。     

磁共振成像的空间编码理论和方法

本文系统地研究了核磁共振成像的基本方法,提出了局部Fourier变换法、射频编码法。在此基础上,作者评述了各种方法的特点和优缺点及其实现方法和技术途径。     

Operational flood control of a low-lying delta system using large time step Model Predictive Control

The safety of low-lying deltas is threatened not only by riverine flooding but by storm-induced coastal flooding as well. For the purpose of flood control, these deltas are mostly protected in a man-made environment, where dikes, dams and other adjustable infrastructures, such as gates, barriers and pumps are widely constructed. Instead of always reinforcing and heightening these structures, it is worth considering making the most of the existing infrastructure to reduce the damage and manage the delta in an operational and overall way. In this study, an advanced real-time control approach, Model Predictive Control, is proposed to operate these structures in the Dutch delta system (the Rhine–Meuse delta). The application covers non-linearity in the dynamic behavior of the water system and the structures. To deal with the non-linearity, a linearization scheme is applied which directly uses the gate height instead of the structure flow as the control variable. Given the fact that MPC needs to compute control actions in real-time, we address issues regarding computational time. A new large time step scheme is proposed in order to save computation time, in which different control variables can have different control time steps. Simulation experiments demonstrate that Model Predictive Control with the large time step setting is able to control a delta system better and much more efficiently than the conventional operational schemes.     

河北省碾子沟金矿形成条件及隐伏矿体预测准则

矿区位于华北地台北缘，具有典型的受地层－岩体－构造控制的“三位一体”成矿特征。对矿区内 隐伏金矿体的预测，应注意在岩体外接触带６ｋｍ范围内的北西向及东西向断裂构造的有利部位，要密切结合围岩蚀变、矿体的变化趋势，矿物及地球化学元素的垂直带规律、地 球物理电异常等信息，最终提出了太矿体的预测准则。     

台湾海峡冬季海面风场数值预报的验证与分析

通过布放在台湾海峡5个浮标冬季(2010年12月至2011年2月)的实测数据对MM5风场的预报结果进行了检验.从空间上看,平潭以北预测风速比实测风速偏高,南部则偏低;随着计算时长的增加,MM5模式预报的平均风速有增加的趋势.通过综合评价检验方法,该模式的短期预报较长期预报效果好.将MM5模式的结果用于台湾海峡冬季平均风场的研究,预测风场和实测风场基本吻合,但台湾海峡靠近台湾一侧模式的平均风速比之前的研究偏小.整体上看MM5较好的体现了台湾海峡冬季风场特点,可以为该区的业务化预报提供参考.     

Grade-tonnage and other models for diamond kimberlite pipes

Grade-tonnage and other quantitative models help give reasonable answers to questions about diamond kimberlite pipes. Diamond kimberlite pipes are those diamondiferous kimberlite pipes that either have been worked or are expected to be worked for diamonds. These models are not applicable to kimberlite dikes and sills or to lamproite pipes. Diamond kimberlite pipes contain a median 26 million metric tons (mt); the median diamond grade is 0.25 carat/metric ton (ct/mt). Deposit-specific models suggest that the median of the average diamond size is 0.07 ct and the median percentage of diamonds that are industrial quality is 67 percent. The percentage of diamonds that are industrial quality can be predicted from deposit grade using a regression model (log[industrial diamonds (percent)]=1.9+0.2 log[grade (ct/mt)]). The largest diamond in a diamond kimberlite pipe can be predicted from deposit tonnage using a regression model (log[largest diamond (ct)]=–1.5+0.54 log[size (mt]). The median outcrop area of diamond pipes is 12 hectares (ha). Because the pipes have similar forms, the tonnage of the deposits can be predicted by the outcrop area (log[size (mt)]=6.5+1.0 log[outcrop area (ha)]). Once a kimberlite pipe is identified, the probability is approximately .005 that it can be worked for diamonds. If a newly discovered pipe is a member of a cluster that contains a known diamond kimberlite pipe, the probability that the new discovery can be mined for diamonds is 56 times that for a newly discovered kimberlite pipe in a cluster without a diamond kimberlite pipe. About 30 percent of pipes with worked residual caps at the surface will be worked at depth. Based on the number of discovered deposits and the area of stable craton rocks thought to be well explored in South Africa, about 10^–5 diamond kimberlite pipes are present per square kilometer. If this density is applicable to the South American Precambrian Shield, more than 70 undiscovered kimberlite pipes are predicted to be present.