动态分段思想在MapInfo中的实现

动态分段是一种新的线性特征的动态分析、显示和绘图技术.目前该技术已经成功地应用在以Arc/Info为代表的采用"弧段-结点"数据模型的GIS软件中,但是在采用"面向实体"数据模型的GIS软件中实现动态分段的研究却很少.本文在分析Arc/Info中动态分段数据结构的基础上,探讨如何在MapInfo中实现动态分段思想.     

面向对象的三维动态实物模型建模技术

总结了面向对象三维建模思想,对模型的组成、结构和框架进行了详细的分析,提出了面向对象的三维动态模型的概念,并建立了模型的数据构成方式,还在此基础上对此结构进行了简化,对由此数据结构产生的文件进行了深入系统的剖析,并给出了实验系统的演示效果.     

RADARSAT影像在土地利用动态监测中的应用

为了改变以往土地管理部门对土地管理的传统方式,节省在常规管理中耗费的大量人力和物力,遥感技术作为新兴发展的科学技术,已应用于动态监测土地利用的变化。本文将具体论述如何利用微波遥感技术监测土地利用的动态变化。     

广义非线性动态处理模型及其解算方法

本文针对当今各国高层领导和科学家十分关注并大力倡导的“数字地球”、“数字国家”、“数字城市”、“数字矿山”等科学工程构建中遇到的大量的多源、多维、多类型、多时态、多精度并具有非线性特征的联合数据处理问题的特点,建立了一个广义非线性动态联合数据处理模型及其相应的广义非线性最小二乘模型。针对该模型规模大、维数高的特点,借鉴多变量函数寻优的“变量轮换法”或“因素交替法”的思想、结合无记忆牛顿法,建立了一个解算算法,该算法将大规模的优化问题分解为两个较低规模的优化问题进行解算,降低了问题的规模,借助无记忆牛顿法,减少了存储量,特别适合大规模问题的解算。     

土地利用动态遥感监测数据库标准探讨

为了将土地利用动态遥感监测技术和成果进一步普及和应用,规范土地利用动态遥感监测数据库建设,依据国土资源信息化标准建设的总体部署和要求,参考相关标准和规程,结合土地利用动态遥感监测业务特点,制定了土地利用动态遥感监测数据库标准草案。     

远洋渔船动态监控系统研究

针对远洋渔业生产中的渔船监控问题,以卫星通讯、GIS、GPS、数据库等技术手段为支撑,进行了远洋渔船GPS动态监控系统的研究和开发工作。本文在介绍了系统总体框架的基础上,系统阐述了通讯文件的解包和数据质量的控制过程,并对渔船的动态监视和轨迹分析功能进行了论述。     

乳头状肾细胞癌的CT表现与手术病理对照

目的：分析乳头状肾细胞癌的cT影像,探讨其相对特异的CT表现。方法：回顾性分析10例经病理证实的乳头状肾细胞癌的临床、手术及CT资料。结果：全部病例均为单发肿块,位于右。肾7例,位于左肾3例,CT平扫肿瘤呈圆形或椭圆形,边缘清楚或欠清楚。病变长径1．0～4．5cm,平均2．5cm。瘤体小时（冬3cm）密度较均匀,无囊变和坏死：瘤体较大时（≥3cm）常出现坏死、囊变。肿瘤强化程度较低,三期呈渐进性轻度增强,特别是排泄期密度略降低。结论：与其他亚型。肾癌相比,乳头状肾细胞癌的cT表现有一定特征,多呈渐进性轻度强化,其确诊可为手术方式的选择提供依据。     

Dynamic interaction numerical models in the time domain based on the high performance scaled boundary finite element method

Consideration of structure-foundation-soil dynamic interaction is a basic requirement in the evaluation of the seismic safety of nuclear power facilities. An efficient and accurate dynamic interaction numerical model in the time domain has become an important topic of current research. In this study, the scaled boundary finite element method （SBFEM） is improved for use as an effective numerical approach with good application prospects. This method has several advantages, including dimensionality reduction, accuracy of the radial analytical solution, and unlike other boundary element methods, it does not require a fundamental solution. This study focuses on establishing a high performance scaled boundary finite element interaction analysis model in the time domain based on the acceleration unit-impulse response matrix, in which several new solution techniques, such as a dimensionless method to solve the interaction force, are applied to improve the numerical stability of the actual soil parameters and reduce the amount of calculation. Finally, the feasibility of the time domain methods are illustrated by the response of the nuclear power structure and the accuracy of the algorithms are dynamically verified by comparison with the refinement of a large-scale viscoelastic soil model.     

Effective force testing using a robust loop shaping controller

Effective force testing (EFT) is one of the force‐based experimental methods used for performance evaluation of structures that incorporate dynamic force control using hydraulic actuators. Although previous studies have shown successful implementations of force control, controllable frequency ranges are limited to low frequencies (10 Hz). This study presents the EFT method using a robust loop shaping force feedback controller that can extend the frequency range up to 25 Hz or even higher. Unlike the conventional PID controllers, loop shaping controllers can provide robustness for a high level of force measurement noise. This study investigates the dynamic properties of hydraulic actuators and the design of a loop shaping controller that compensates for control–structure interaction and suppresses the effect of oil‐column resonance. The designed loop shaping controller was successfully implemented into an EFT setup at the Johns Hopkins University. An experimental investigation of the loop shaping controller was performed under step, random, and earthquake force loadings. Experimental results showed that the loop shaping controller provided excellent force tracking performance and robustness for dynamic force loadings. It was also shown that the loop shaping controller had the gain margin of 9.54 dB at the frequency of 28 Hz. Copyright © 2012 John Wiley & Sons, Ltd.     

A web‐based methodology for the prediction of approximate IDA curves

A web‐based methodology for the prediction of approximate IDA curves, which consists of two independent processes, is proposed. The result of the first process is a response database of the SDOF model, whereas the second process involves the prediction of approximate IDA curves from the response database by using n‐dimensional linear interpolation. Such an approach enables user‐friendly prediction of the seismic response parameters with high accuracy. In order to demonstrate the capabilities of the proposed methodology, a web application for the prediction of the approximate 16th, 50th and 84th fractile responses of an RC structure was developed. For the presented case study, the response database was computed for a set of 30 ground motion records and the discrete values of six structural parameters. Very good agreement between the computed and the approximated IDA curves of the four‐storey RC building was observed. Copyright © 2012 John Wiley & Sons, Ltd.