排序方式： 共有61条查询结果，搜索用时 15 毫秒
41.
提出了一种基于模板匹配的图像修复方法。该算法在所有的待修复区域边缘寻找优先权最高的待修复块,在规定的样本区域寻找与上一步所得的具有最高优先权的待修复块最为匹配的样本块,用所得的最佳样本块填充所受损的图像区域,直到图像整体修复完成。试验仿真表明该方法在大面积图像受损的条件下,实现了图像的纹理信息保护,整幅图像有较好的修复视觉效果。 相似文献
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The aggregation index (AI) is a classical ecology calculation method, which has been widely used for measuring the aggregation level of spatial patterns within a landscape scale in landscape ecological studies. However, it has certain limitions. For instance, identical results can be obtained by AI even when the shape and number of landscape patches are totally different in two landscape units. Furthermore, the value of AI approaches to 1 if the landscape patch is large enough. To solve these problems, a logical limitation of the original AI equation was revised firstly. Secondly, an improved AI-J was developed based on the awareness of the effects of spatial distribution characteristics of patches and changing spatial scale on AI operation. Finally, the accuracy of AI and AI-J results were evaluated through a case study of city green patches in Chengdu, P. R. China. The results show that the calculated result of AI-J is more precise than that of AI and AI-J can be used to compare a certain landscape class under different spatial scales. 相似文献
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为满足卫星导航系统的要求,采用单点馈电叠层贴片技术,设计了一种双频圆极化宽波束天线;采用隐式的时域有限差分方法,对天线进行全波仿真,分析了影响匹配性能的结构参数,并通过在贴片的一组对边上开矩形缝隙,微调天线谐振频率,同时实现了阻抗带宽和轴比带宽相吻合;总结出改善天线双频匹配特性的方法,解决了双频段同时达到最佳匹配的问题。 相似文献
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依据通信电源标准,设计了一款36W/12V的DC/DC辅助电源.该电源选取带有RCD吸收回路的反激拓扑结构,适应40-60V的宽电压输入.控制芯片采用具有跳频功能的OB2269C,以降低带载量小时的损耗.文章最后给出了理论损耗值和测试结果 . 相似文献
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建模是三维制作的基础.NURBS曲线建模是目前比较流行的建模方式,它能产生平滑连续的曲面,使用数学函数来定义曲线和曲面,可在不改变外形的前提下自由控制曲面的精细程度.本文结合具体实例,阐释NURBS建模技术的主要思路及其流程. 相似文献
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王瑞涛 《兰州石化职业技术学院学报》2006,6(4):9-11
介绍了数控加工中的补偿概念，讨论了刀具补偿、夹具补偿和程序补偿三种补偿方法及其原理，并进行了对比分析。 相似文献
48.
罗晓曙 《广西师范大学学报(哲学社会科学版)》1994,(Z1)
对北京牌CC511型遥控彩电的主电源控制电路工作原理进行了分析,指出它电路设计的一个缺陷,并给出了改进电路,提高了该机在低电压供电下的工作可靠性。 相似文献
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张育 《江苏广播电视大学学报》2003,14(3):37-39
普通机械、液压夹紧装置针对确定形状、特性的工件，施加压紧力固定工件。随着柔性加工技术的发展，生产线上的夹紧装置将面对不同形状、特性的工件，一般夹紧装置难以适应。在实际操作过程中，应以目标(工件)为中心，在分析机械手指与目标物体表面接触形式和状态的基础上，应用雅各宾、牛顿-欧拉方程确定主动力的大小和方向，从而进一步探讨机械夹紧装置(机械手)灵巧抓控运动学、动力学机理。 相似文献
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Passive worms can passively propagate through embedding themselves into some sharing files, which can result in significant damage to unstructured P2P networks. To study the passive worm behaviors, this paper firstly analyzes and obtains the average delay for all peers in the whole transmitting process due to the limitation of network throughput, and then proposes a mathematical model for the propagation of passive worms over the unstructured P2P networks. The model mainly takes the effect of the network throughput into account, and applies a new healthy files dissemination-based defense strategy according to the file popularity which follows the Zipf distribution. The simulation results show that the propagation of passive worms is mainly governed by the number of hops, initially infected files and uninfected files. The larger the number of hops, the more rapidly the passive worms propagate. If the number of the initially infected files is increased by the attackers, the propagation speed of passive worms increases obviously. A larger size of the uninfected file results in a better attack performance. However, the number of files generated by passive worms is not an important factor governing the propagation of passive worms. The effectiveness of healthy files dissemination strategy is verified. This model can provide a guideline in the control of unstructured P2P networks as well as passive worm defense. 相似文献