共查询到18条相似文献，搜索用时 421 毫秒
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一种基于面向对象的企业建模技术 总被引：3，自引：0，他引：3
将一种面向对象的思想应用于企业建模中 ,利用面向对象的技术实现功能模型和信息模型的集成。对象的独立性和封装性增强了系统的鲁棒性 ,能适应企业功能和结构的动态重组。提出了对象状态图、对象状态矩阵和对象属性矩阵 ,容易贯彻“自顶向下”的系统分析策略 ,使系统的外部视图(用户视图 )与内部视图 (计算机视图 )统一 ,达到清晰的、完整的描述系统的目的。 相似文献
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专题实时环境数据分发系统(THREDDS)作为海洋大气数据管理和发布平台,通过NetCDF库可以提供多样化数据服务功能(包括OPeNDAP、WMS/WCS、HTTP和NetcdfSubSet等),便于数据用户灵活获取数据,也方便数据平台管理和数据发布。本研究通过NcML的配置使用,可以在不改动数据源文件条件下,对同组众多的数据文件虚拟为单一数据发布,最终让用户可以通过单一的网络数据服务接口,完成对众多数据文件跨文件连续、便利获取的数据。该功能也可为下一步数据可视化开发工作提供统一便捷的数据流基础。 相似文献
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《中国海洋大学学报(自然科学版)》2015,(6)
海洋环境数据种类繁多且数量巨大,多数以文档数据集形式存在,这使得海洋环境大规模数据的存储和访问变得困难。针对当前海洋环境大数据存储方法不足和编程访问的局限性,提出了一种面向应用编程的数据存储访问模型。该模型将文件数据模型结构信息映射到虚拟数据库中,提供基于SQL语法的访问接口,降低数据访问复杂度,提高软件编程效率。 相似文献
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根据现代物联网对地理空间信息资源的大吞吐量需求,本文运用云计算技术、主从拓扑结构和多副本技术,设计了针对地理空间信息云平台的负载均衡调度算法,该算法通过统一的主服务器进行调度,并运用哈希函数使访问请求趋于均衡化。同时,我们将该算法运行在实际GIS系统中,模拟不同频度的用户访问请求,进行仿真。按照访问请求特征,将请求分为可预测高峰请求、随机高峰请求和系统响应请求三类,并分别统计请求的平均响应时间。结果显示,该算法有效可行,可在访问高峰期大幅减少用户平均响应时间。 相似文献
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红树林的种间结构组成对红树林生态系统的健康和发展至关重要,而红树林种间分类问题一直以来都是基于遥感手段的红树林监测中的难点。针对该问题,以人工种植为特点的广西茅尾海红树林遥感种间分类为例,基于面向对象的分类思想,提出了一种现场样本与分割对象相结合的红树林种间分类方法。利用GF-2 PMS1高分辨率卫星遥感影像数据,开展了广西茅尾海红树林湿地典型植被精细分类和空间分布研究,并将分类结果与基于像素和传统面向对象SVM分类方法进行了对比。结果显示:总体上,面向对象分类方法更适合用于茅尾海红树林湿地典型植被分类;对于局部混生明显的区域使用基于像素SVM分类方法效果会更好;传统面向对象分类方法中将整个影像分割对象单元作为训练样本可能会在某种程度上造成负面影响。因此,使用文中提出的样本选择新方法进行面向对象分类精度最高,总体精度达到了93.13%,Kappa为0.89。 相似文献
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为了解决校园网络升级改造过程中引入DMZ与VPN技术后,导致的内网资源安全性降低与虚拟IP地址碰撞的难题,在传统VPN解决方案基础上,提出虚拟IP地址生成算法与IP地址连接池的思想。异地用户通过VPN访问内网资源时,必需使用IP地址连接池来获取虚拟IP地址,实现虚拟IP地址分配的动态管束,有效控制虚拟IP地址的随意分配,避免因争夺虚拟IP地址资源而产生的碰撞问题。这种方法对于提高VPN网络的安全性和访问效率,遏制黑客通过匹配IP地址的方式入侵内网、保护内网资源安全与解决地址冲突问题非常有效。 相似文献
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Spatio-temporal semantics based on "object views" or "event views" has few abilities to represent and model the continuity and gradual oceanic phenomena or objects, which seriously limits the specific marine applications and knowledge discovery and data mining, so this paper proposes a hi- erarchical abstraction semantics with "marine spatio-temporal process→life span phases→evolution sequences→state units" and process objects included by level with "marine process objects→phase objects→sequence object→state objects" with the oceanic process characteristics into the marine process semantics. In addition, this paper designs the storage and representation of marine process objects using the backus normal forms (BNF) and abstract data type (ADT). Base on El Niño Southern Oscilation (ENSO) index and Chinese rain gauging station data, this paper also gives a case of study. The spatio-temporal analysis between ENSO process and Chinese rainfall anomalies shows that the marine spatio-temporal semantics not only can illustrate the spatial distribution of Chinese rainfall anomalies in different time scales at ENSO process, life span phases and state units, but also analyze the dynamic chan 相似文献
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基于MRF场的侧扫声呐图像分割方法 总被引：1，自引：0，他引：1
为了利用侧扫声呐进行水下目标自动探测和识别,首先必须将声呐图像分为目标高亮区、海底混响区和目标阴影区.由于声呐图像有强背景噪声,传统的图像分割方法显得无能为力,故采用基于MRF场的图像分割方法来准确地分割.根据侧扫声呐目标的成像特点,建立了分割的约束条件;利用阴影与目标的灰度均值比很小这一特点进行初始分割,然后根据分割后目标与阴影的宽度差来剔除虚假目标,由初始分割的结果求得MRF模型初始参数,再采用迭代条件估计得到最终的模型参数和准确的分割结果.由于考虑了相邻像素间的依赖关系,具有抗噪性强、分割效果好的优点,从理论上说是合理的.实测数据分析也证明了这种算法的优越性. 相似文献
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This paper presents an analytical solution for scattering of oblique incident, small amplitude, monochromatic wave trains by a stationary rigid multi-layered objects with rectangular cross-section. The object is infinite long and consists of multilayers, which can be either solid or permeable. This paper extends the previous work by Hu and Liu [1] from normal incident wave condition with a special object configuration to oblique incident waves with multi-layered object. The present model is validated with several existing solutions for normal/oblique waves interacting with a single object; excellent agreement is observed. New numerical results are presented to investigate the effects of incidence angle on reflection, transmission and energy loss coefficients for a combined floating and bottom-mounted permeable breakwater. A new floating board-cage breakwater is developed from the present model and its solutions are discussed in detail. A computer program, AWAS-P, has been updated so that it is applicable for both oblique and normal incident waves, while the object is multi-layered. 相似文献
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Rongxin Li Haihao Li Weihong Zou Smith R.G. Curran T.A. 《Oceanic Engineering, IEEE Journal of》1997,22(2):364-375
This paper presents a photogrammetric model for digital underwater video imagery, which has been mostly applied to qualitative analysis in the marine environment. With this model, quantitative analysis of underwater images is possible, e.g., to locate positions, calculate sizes, and measure shapes of objects from image features. The underwater photogrammetric model is based on a three-dimensional optical ray tracing technique which rigorously models imaging systems with multilens configurations and multiple refractions. The calibration procedure with two independent phases has been proven to be efficient in simplifying the computation and improving the calibration accuracy. With the current imaging system configuration and photogrammetric model, an accuracy of 0.8 cm in lateral directions and 1.2 cm along the depth direction for objects located about 2-3 m from the camera system in the object space is attainable. A PC-based digital underwater photogrammetric prototype system has been developed to implement the underwater photogrammetric model 相似文献
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We present a study of scattering from objects in a free unbounded ocean and for objects near an interface and in a waveguide. Major emphasis is on results and discussion of theoretical development is limited to the essentials. An examination of backscattered echoes is presented for elastic targets. Angular distributions are examined for all target types, as well as environments, with the exception of objects in a waveguide. In a waveguide, beamforming techniques are most appropriate for detection of objects. We also examine rigid, soft, and elastic objects that are either spheroidal or cylindrical. Aspect ratios studied range from 3:1 to 24:1, andkL/2 ranges (k is wavenumber andL is the length of the object) are from 3 to 120. 相似文献
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为了实现产品全生命周期中的物料清单(BOM)数据的一致性和协同性，在阐述了企业中BOM数据的主要使用部门的基础上，分析了企业BOM的主要使用类型、功能需求和技术特点。提出了BOM视图和BOM视图空间的基本定义，讨论了BOM视图空间的主要类型。基于单一数据源的思想，采用面向对象的建模方法，定义了BOM对象模型和BOM对象的主要视图类型及其关键属性。该技术的应用对于实现CIMS环境下的BOM信息集成具有重要的意义。 相似文献
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Water waves induce a slow drift of an object floating on the water surface. In this study, we examined, by a series of laboratory experiments, the drift motion of small rigid floating objects driven by regular waves in deep water. Different shapes of planar objects, including square, circular and elliptical, were investigated for two different submergences, and their drift motions in waves were determined using an infrared motion monitoring system. The corresponding measurements enabled the quantification of the drift characteristics with respect to the wave characteristics and object shapes. Numerical simulations based on an existing theory were presented and comparisons between the experimental data and the predictions by the existing theory were performed. 相似文献