基于距离模型的波数域算法

合成孔径雷达(SAR)存在四种距离模型,本文利用这四种模型推导出四种波数域算法,给出了四种算法详细的推导过程,并得到了四种算法和四种模型之间的一一对应关系。文章提出了单色等效斜视波数域算法,该算法不需要插值,因而提高了计算效率,适合于小斜视角且测绘带宽度不大的情况下的快速成像。最后利用该算法对星载SAR的实际数据进行成像,结果表明在成像精度牺牲不大的情况下可以大大提高成像速度。     

郯庐断裂在胶东金矿聚集区的成矿效应

郯庐断裂带是中生代华北与扬子板块的碰撞造山带的陆内转换断层,大规模左行韧性剪切位移牵引胶北太古宙穹隆(栖霞复背斜)逆时针旋扭隆升,并且形成三山岛一仓上、焦家一黄县和招远一平度(破头青)等弧形右行剪切带和混合花岗岩.早白垩世末期郯庐断裂从韧性向脆性构造域的快速转换,引发招掖变质地体的金矿成矿大爆发,形成胶东独特的金矿床汇聚链.     

路域DEM数据变化区域标定方法的探讨

针对道路建设引起的路域DEM数据变化范围的标定问题,该文探讨了基于多源数据的标定方法。该方法首先提取设计成果的外边界作为核心变化区,再根据该区域100m范围内道路建设前后的遥感影像提取出植被发生明显变化的区域作为野外调查和建模处理的区域,并对该区域内融合构建的DEM数据和原有带状地形图构建的DEM数据进行差异分析,求出最终的DEM数据变化区。以杭瑞高速毕都(毕节至都格)段为例开展的实验研究表明,该文提出的方法可以精确地标定因道路建设引起路域DEM数据的变化区域,可直接用于DEM数据增量的采编与更新操作。     

An Oscillating Wave Energy Converter with Nonlinear Snap-Through Power-Take-Off Systems in Regular Waves

Floating oscillating bodies constitute a large class of wave energy converters, especially for offshore deployment. Usually the Power-Take-Off (PTO) system is a directly linear electric generator or a hydraulic motor that drives an electric generator. The PTO system is simplified as a linear spring and a linear damper. However the conversion is less powerful with wave periods off resonance. Thus, a nonlinear snap-through mechanism with two symmetrically oblique springs and a linear damper is applied in the PTO system. The nonlinear snap-through mechanism is characteristics of negative stiffness and double-well potential. An important nonlinear parameter is defined as the ratio of half of the horizontal distance between the two springs to the original length of both springs. Time domain method is applied to the dynamics of wave energy converter in regular waves. And the state space model is used to replace the convolution terms in the time domain equation. The results show that the energy harvested by the nonlinear PTO system is larger than that by linear system for low frequency input. While the power captured by nonlinear converters is slightly smaller than that by linear converters for high frequency input. The wave amplitude, damping coefficient of PTO systems and the nonlinear parameter affect power capture performance of nonlinear converters. The oscillation of nonlinear wave energy converters may be local or periodically inter well for certain values of the incident wave frequency and the nonlinear parameter , which is different from linear converters characteristics of sinusoidal response in regular waves.     

灾害链领域本体构建方法——以暴雨洪涝灾害链为例

自然灾害发生具有突发性、随机性和链式效应,而且自然灾害拥有庞大的概念体系和灾害事件之间异常复杂的时空关系,由于缺乏对灾害知识的统一描述表达机制,导致灾害领域知识难以实现共享和重用,因此,构建灾害链的统一描述模型并实现灾害知识的共享与重用是当前亟须解决的一个问题。本文提出了一种灾害链领域本体的构建方法,在对比现有方法基础之上,定义了灾害链相关概念、属性,以及概念之间的关系,采用网络本体语言OWL对灾害链领域本体进行建模,并实现了灾害链领域本体的可视化,为灾害知识的共享与重用提供了有效支撑。最后,以暴雨-洪涝灾害链为例验证了该方法的有效性和可靠性。     

A Global Approach to the Spatial Diversity and Dynamics of Internet Domains

The objective of this paper is to describe the place of individual countries in digital space through the lens of Internet domains and specific websites. We will discuss the global geography of domains in reference to states and other entities of spatial organization, and changes in the positions of individual websites. These issues will be approached with an awareness of the significant changes taking place in the functioning of the Web, particularly cyberbalkanization. This study mainly used data from Alexa rankings, the best free source of information available on the behavior of Internet users. One conclusion is the clear U.S. dominance over other countries in relation to number of most popular domains. Despite the clear U.S. dominance, the BRIC countries—Brazil, Russia, India, and China—play an increasingly significant role in the geography of domains. The trends discussed in this article are related to the so‐called balkanization of the Internet. Regulations of its functioning and the growing importance of national websites and search engines have contributed to deepening the differences between Internet users in different countries.     

网络RTK动态中长基线模糊度解算方法比较研究

论文对比分析了网络RTK中长基线模糊度固定方法中无电离层组合+宽巷模糊度解算与原始模糊度整体解算两种方法的优劣。实验结果表明:与现有的模糊度解算方法相比,观测值域内的模糊度固定不但可以快速可靠地固定宽巷整周模糊度,而且提高了L2模糊度正确固定的成功率和效率。     

商业网点管理领域工程与可复用构件开发

网点资产经营管理型企业是普遍存在于城市中的网点经营实体,由于房屋拆迁、产权变更、租户行为复杂多变、商铺信息变更频繁等原因,商业网点的管理难度加大,信息化管理成为必然要求。目前,管理平台的独立开发模式,尽管在一定程度上满足了企业的管理需求,但定制化的开发又造成了开发成本的增加。为此,本文采用面向特征的领域工程方法,对网点管理中的业务范围、主要场景、业务逻辑等进行了高度抽象,并基于ArcGIS Engine地图构件开发了商业网点管理可复用构件。实践证明,该构件能够快速用于特定企业网点管理平台的具象化开发。     

宽频地震处理技术在南海某工区的应用

在海洋地震勘探中产生的鬼波会抑制低频分量,造成频域的陷波点,降低地震记录的分辨率,使地震记录的同相轴发生混叠甚至产生假的同相轴。笔者采用FK域水平电缆压制鬼波法,将地震数据进行FK变换,对维纳滤波求取反褶积算子投影到FK域,并对二者进行褶积,将结果 FK反变换回时间域。鬼波压制后的模型数据频带得到了有效拓宽,低频、高频信息均得到了加强。鬼波压制后的实际数据目的层频带从12~60 Hz拓宽到8~75 Hz,三亚组能量与合成记录匹配较原始数据更好。     

An innovative block partition and equivalence method of the wave scatter diagram for offshore structural fatigue assessment

The fatigue assessment plays an increasing role for the offshore structural safety. Many fatigue assessment methods have been developed for this purpose. Among those methods, the time domain method is regarded as the most accurate method but less adopted in practice due to time consuming. In order to improve the efficiency of the time domain method, an innovative block partition and equivalence method of the wave scatter diagram is developed for offshore structural fatigue assessment. After the wave scatter diagram is partitioned into several blocks, the newly developed method, involves determination of the equivalent wave height, wave period and occurrence probability of the representative sea states based on modified energy equivalent principle. The equivalent wave period of the representative sea state is calculated via the spectral moment formula in which the equivalent spectral moments of zero and second order are obtained based on the weighted averaging principle. Combining with the determined wave period, the equivalent significant wave height can be determined by reversing the wave spectrum integral formula, where the equivalent wave energy of a divided block of the wave scatter diagram is modified by introducing a factor to compensate the effect of low- and high-amplitude cycles fatigue damage. The equivalent occurrence probability is equal to the summation of the original sea states’ occurrence probability within the divided block. The developed method has the advantage of preserving the stochastic characteristics of the short term sea states within the divided block during determining the representative sea state. At the same time the newly developed method has no limitation on block partition and can be applied on different offshore structure. Two structural models, a fixed mono-pile platform and a floating semi-submersible platform, are demonstrated in the numerical examples. Results indicate that the newly developed method is robust, computationally affordable, and accurate within engineering expectations.