30 resultados para Cartographic updating

em Chinese Academy of Sciences Institutional Repositories Grid Portal


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Knowledge about the world phylogeny of human mitochondrial DNA (mtDNA) is essential not only for evaluating the pathogenic role of specific mtDNA mutations but also for performing reliable association studies between mtDNA haplogroups and complex disorder

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This paper attempts to develop a reduction-based model updating technique for jacket offshore platform structure. A reduced model is used instead of the direct finite-element model of the real structure in order to circumvent such difficulties as huge degrees of freedom and incomplete experimental data that are usually civil engineers' trouble during the model updating. The whole process consists of three steps: reduction of FE model, the first model updating to minimize the reduction error, and the second model updating to minimize the modeling error of the reduced model and the real structure. According to the performance of jacket platforms, a local-rigidity assumption is employed to obtain the reduced model. The technique is applied in a downscale model of a four-legged offshore platform where its effectiveness is well proven. Furthermore, a comparison between the real structure and its numerical models in the following model validation shows that the updated models have good approximation to the real structure. Besides, some difficulties in the field of model updating are also discussed.

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We have successfully extended our implicit hybrid finite element/volume (FE/FV) solver to flows involving two immiscible fluids. The solver is based on the segregated pressure correction or projection method on staggered unstructured hybrid meshes. An intermediate velocity field is first obtained by solving the momentum equations with the matrix-free implicit cell-centered FV method. The pressure Poisson equation is solved by the node-based Galerkin FE method for an auxiliary variable. The auxiliary variable is used to update the velocity field and the pressure field. The pressure field is carefully updated by taking into account the velocity divergence field. This updating strategy can be rigorously proven to be able to eliminate the unphysical pressure boundary layer and is crucial for the correct temporal convergence rate. Our current staggered-mesh scheme is distinct from other conventional ones in that we store the velocity components at cell centers and the auxiliary variable at vertices. The fluid interface is captured by solving an advection equation for the volume fraction of one of the fluids. The same matrix-free FV method, as the one used for momentum equations, is used to solve the advection equation. We will focus on the interface sharpening strategy to minimize the smearing of the interface over time. We have developed and implemented a global mass conservation algorithm that enforces the conservation of the mass for each fluid.

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The Latest developed LECR2M (Lanzhou ECR No. 2 Modified) source is the updated one of LECR2 (Lanzhou ECR No. 2) source at IMP. It has been assembled on the low energy ion beam experimental platform to produce MCI beams for atomic physics and material physics experimental research. In our updating program, the structure of injection and extraction components has been modified to make the source structure more simple and effective. The hexapole magnet has also been replaced by a new hexapole magnet with higher radial field and larger inner diameter. With this updating, stronger magnetic field confinement of the ECR plasma is possible and better base vacuum condition is also achieved. LECR2M was designed to be operated at 14.5GHz. During the preliminary test, 1.3emA O6+ beam was extracted with the injected rf power of 1.1kW. The source has been used to deliver intense MCI beams for different experiments. After some discussion of the main features of this newly updated source, some of the typical commissioning test results of LECR2M will be presented.

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针对现有软件发布方式主要以开发者的角度进行软件开发后生命周期管理所存在的问题,提出了更为合理的以用户的角度进行软件开发后生命周期管理的思想,建立了一种新的软件发布机制体系结构。该发布机制试图解决如下问题:让用户透明地使用软件,即用户不需要显式地进行软件的安装、更新和卸载;支持软件的即点即用和使用态发布,使用态发布指安装了某软件的计算机可以作为该软件的发布源;使得系统重装后能够以较小的代价恢复到指定的状态点。最后,分析了软件动态更新和分布式软件系统发布所应解决的问题。

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文中研究的相关跟踪技术主要应用于飞航导弹的末制导。现阶段,激光制导技术、GPS制导技术、合成孔径雷达(SAR)制导技术在我国的实际应用还不成熟,传统的电视、红外制导技术仍然具有很强的生命力,因而,基于可见光的视频相关跟踪技术具有重要的研究价值。本文主要论述的两种相关算法是:多灰度点相关(MPC)、区域模板相关(RTC)。其中多点相关(MPC)算法的跟踪灵敏度高,定位精度好,硬件实现比较方便,实时性能好;区域模板相关算法(RTC),在图像的匹配过程中,不仅考虑了目标区域的灰度特征,而且兼顾了区域里多灰度层次的位置特征、面积特征,算法具有很好的鲁棒性。文中深入研究了两种相关跟踪算法,并针对它们在实际应用中的不足,提出了有效的改善措施。最后,本文对两种相关跟踪算法进行了初步融合,一是:通过粗匹配、精匹配过程来选取目标跟踪点;二是:提出了一种度量模板更新的能量准则函数。大量的仿真实验结果表明:改进后的两种相关跟踪技术可以较好地完成一些复杂背景下的目标跟踪任务,两种算法的有效结合又进一步提高了目标跟踪的稳定性能和可靠性能。本文研究的一些相关跟踪技术已经运用到实际工程项目中。

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在面向目标追踪等应用的无线传感器网络研究中,协同任务分配机制的研究是很重要的。基于动态联盟机制的协同任务分配方法是事件触发的,适用于任务出现频率相对较低的大规模无线传感器网络。本文在基于动态联盟机制研究的基础上,首先引入了联盟覆盖范围和休眠盟员的概念,进一步消除针对同一任务的检测传感器节点的冗余,降低系统的能量消耗;而后又给出了一种动态联盟的更新机制,以保证动态联盟执行任务时的连续性,在一定程度上保证网络的检测性能。最后通过仿真,从系统总能耗、目标捕获率和检测误差标准差等方面检验了算法的性能,并给出了缓冲带宽度等参数对能耗和网络检测性能的影响。

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本文首先介绍了视觉伺服的一般原理 .然后提出了一种模型无关的无定标视觉伺服控制方法 ,在这种方法中不需要机器人模型和摄像机模型 ,应用方差最小化的原理推导出了模型无关的无定标视觉伺服控制律 .此外还给出了图像雅可比矩阵的递推公式 .文章最后通过一个轨线跟踪的仿真实验验证了算法的正确性和有效性

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介绍了一套多水下机器人三维视景仿真系统。该系统采用虚拟现实技术,利用虚拟仿真软件VegaPrime 与Visual C++.NET 2003 混合编程实现三维视景仿真。它主要用于海洋环境的模拟和多水下机器人运行时的位姿更新、碰撞检测、环境效果及各种特效的实时显示。此外,它还具有响应各种输入/输出设备的功能和通过人性化图形界面接口与用户进行交互的功能。

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本文以空值的完全语义为基础,以空值环境下基于5值(5VL)的选择运算为工具,深入研究了基于关于模型的含空值关系数据库的数据更新策略和实现算法

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本文在[1]扩展关系模型中引入属性级的不完全信息空值。为适应此环境下更新操作的需要,本文对[1]中的扩展关系模型进行了进一步的扩展,并以此模型为基础讨论了空值环境下含不确定及可能信息关系数据库的更新操作的策略,给出了相应的处理算法。

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In this paper,the traditional relational model is extended in order to express indefinite and maybe information. On the basis of the extended relational model.,the foundamental operations in relational algebra are defined again,and the policy and algorithm for updating relational database are given.