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双语推荐：四叉树

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提出了一种自适应多叉树防碰撞算法.新算法在动态二叉树和四叉树搜索算法的基础上,利用曼彻斯特编码可以准确识别碰撞位的特性,通过计算碰撞因子,估计标签数量,从而在标签数较多的分支内选择动态四叉树搜索,反之选择动态二叉树搜索.理论和仿真分析表明:新算法克服了动态二叉树和四叉树搜索算法的缺点,在减少碰撞时隙数的基础上,又减少了空闲时隙数,大幅度地提高了搜索效率和时隙的吞吐率,具有一定的创新性和实用性.
A new adaptive anti-collision algorithm based on multi-tree search is proposed in this paper.Based on the binary tree and quadtree search,the new algorithm taking advantage of the features of Manchester encoding computes the collision factor and estimates the number of the tags.That is to say,when the number of tags in branches is large,the new algorithm uses quadtree search,otherwise,binary tree search is used.Theoretic analysis and computer simulations show that the new anti-collision algorithm overcomes the disadvantages of binary tree and quadtree algorithms.It can decrease timeslots and improve the throughput of timeslots effectively.

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基于四叉树的数字图像压缩算法是一种利用四叉树结构对图像中平滑区域进行压缩编码的技术。而现有的压缩算法由于存在诸多缺陷,使得其效果很难与诸如Jpeg2000的主流压缩算法相比拟。论文基于现有的四叉树分割算法,提出了一种高效的编码方式来记录四叉树的结构信息,同时引入了泰森多边形方法和自然邻点插值法来解决四叉树重构时的平滑问题。实验结果表明,该算法在尽可能小的失真前提下,最大限度地保留了图像的细节信息,且具有较高的压缩比,其整体效果可以与Jpeg2000比拟。
Quadtree‐based image compression technique is a typical method w hich aims to exploit the redundancy in an image such that the smaller number of bits can be used to represent the image while remaining detail information .However , most of existing approaches to this problem do not work well due to its own limitations .Here a new approach to code quad‐tree decomposed Image with a novel codebook and then be reconstructed by voronoi interpolation is described that provides a"satisfying"visual quality comparing with Jpeg2000 .

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提出了一种自适应多叉树防碰撞算法，该算法构建了无碰撞时隙的二叉查询树，通过计算碰撞因子估计标签数量，从而自适应的选择二叉树或四叉树。理论和仿真表明：该算法克服了现有算法数据传输量大的缺点，同时在二叉树分支内实现了无碰撞时隙以减少总时隙，对多标签情况下，通过自适应的选择四叉碰撞树来减少碰撞时隙。算法有效地减少了数据传输量，提高了时隙利用率和系统吞吐率，具有一定的创新性。
An adaptive query multi-tree anti-collision algorithm is proposed. The new algorithm computes the collision factor and estimates the number of the tags so that it can adaptively use the binary-tree or the quad-tree. The theory and simulation show that the new algorithm overcomes big data transmission by constructing collision-tree. It also can reduce total slots by reducing slot-free in the binary-tree and using adaptive binary-tree or the quad-tree in the case of many tags. The new algorithm has certain innovations.

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基于现有的自适应多叉树防碰撞算法，通过引入位编码单元机制，提出了一种新的自适应多叉树防碰撞算法。新算法自适应地选择二叉树或者四叉树对标签编码进行查询。在使用四叉树查询时，读卡器优先对查询前缀参数进行优化，避免了空闲时隙的产生。仿真结果表明，新算法可以有效地减少标签识别过程中的查询次数和通信量，提高了标签识别效率和系统吞吐率。
Based on the existing adaptive multi-tree search anti-collision algorithm ,via the Bits Coding U-nit mechanism , a new adaptive anti-collision algorithm was proposed .The new algorithm automatically choosed binary tree or quad tree to query the label code .When the quad tree was used ,the card reader optimized the parameter of the query prefix to avoid the idle time slot .The simulation results showed that the new algorithm can effectively reduce the times of tag identification and the information transferred in the process of query .The new algorithm improved the efficiency of tags identification and the system throughput .

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八叉树结构是由四叉树结构推广到三维空间而形成的一种3D栅格数据结构，其树型结构在空间分解上具有很强的优势，为了有效地进行大量点云数据的存储和管理，重点讨论了线性八叉树编码技术。
Octree structure is formed by a quad-tree structure which is extended to three-dimensional space of a 3D raster data structure tree and has a strong advantage in spatial resolution, in order to effectively carry out a large number of point cloud data storage and management, this article focuses on the linear octree coding techniques.

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针对随机ALOHA算法效率较低,确定性树型方法要求区域内标签数量不变的问题,提出一种改进的四叉树RFID防碰撞算法。在阅读器阅读范围内的标签根据不同的问询命令修改自身应答概率进行分组。阅读器采用比较碰撞位的四叉树算法识别应答概率为1的标签。通过公式推导证明了算法采用四叉树识别的合理性。实例说明和仿真结果显示,该算法能减少阅读器和标签之间的查询次数和通信量,有效提高阅读器的识别效率。
To address the problem that the efficiency of stochastic ALOHA is very low and deterministic tree searching algorithm has the limitation that the number of the tags in the area doesn’t change, this paper presents an improved quadtree RFID anti-collision algorithm. The tags in reading range of reader modify their responsive probabilities for grouping according to different inquiry commands. Reader uses the quadtree RFID anti-collision algorithm by comparing collision bit to identify a tag whose responsive probability is one. Formula deduction proves the rationality of the algo-rithm using quadtree recognition. Examples and simulation results show the algorithm can reduce the number of queries and the communication volume between readers and tags, the recognition efficiency of reader is effectively promoted.

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针对高效视频编码（ HEVC）中编码单元（ CU）进行四叉树递归遍历时间较长的问题，提出一种基于纹理四叉树的快速HEVC帧内编码算法。采用Sobel算子对当前视频图像提取边缘，利用最大类间方差法剔除弱边缘并保留强边缘。通过递归方式对边缘图中的每个64＆#215;64单元建立纹理四叉树，使用视频图像的纹理四叉树结构对CU最优分割组合进行预测。对于不同大小的分割单元，无需完全递归遍历所有的CU深度，从而缩小CU搜索范围，节省编码时间。实验结果表明，与HEVC标准算法相比，该算法亮度分量的码率平均增加了0.50%，信噪比和编码时间分别减少了0.03 dB和28.70%。
Aiming at high computing complexity of recursive quadtree partitioning of a large Coding Unit( CU) in High Efficiency Video Coding( HEVC) ,a fast intra coding algorithm of HEVC based on texture quadtree is proposed in this paper. The edges of the whole frame are extracted by Sobel operator. The weak edges are removed and the edge map is formed using maximum between-cluster variance method. Then,the texture quadtree is recursively built for each 64 × 64 of edge map. The texture quad-tree is applied to predict the CU partition combination. For different partition size, full searching all CU depth is avoided. Hence,CU search range is narrowed and the encoding time is reduced. Experimental result shows that the proposed algorithm saves 28. 70% of the encoding time on average,while it only leads to increase 0 . 50% Bjontegaard Delta Bit Rate ( BDBR ) and decrease 0 . 03 dB Bjontegaard Delta Peak Signal-to-Noise Ratio ( BDPSNR) for luminance component.

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对传统的历遍要素变化捕捉方法进行改进,提出了基于四叉树的矢量数据变化捕捉方法。该方法利用四叉树的空间索引原理,对新旧图层进行四叉树分割,计算分割区域内新旧要素的"点-弧段"变化特征,以此确定分割区域的变化情况,并进行迭代运算,从而过滤出不变区域,快速定位至变化区域。实验结果表明:该方法计算速率较高,能够准确快速地识别出变化信息,与传统历遍要素变化捕捉的方法相比,更有助于提高GIS数据库更新的效率。
Incremental updating is one of the most frequently used methods in spatial databases updating and the detection of changed objects is the crucial technology.Change detection is of great significance for improving the efficiency of spatial database updating.This paper refines the object-traversing method and proposes a new change detection method based on quad-tree.Considering the principle of spatial in-dex,this method divides the region of the corresponding layers based on quad-tree.By calculating the vertex-edge changed index of the objects in the region,this method can evaluate the changed situation of the region.The method can filter out the unchanged areas and rapidly locate the change areas in an itera-tive way.The experimental result showed that this method can reach high computational efficiency and properly recognize the change information.Comparing with the traditional change detection algorithm, this method can improve the efficiency of GIS database updating significantly.

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RFID技术是一种非接触式的自动识别技术。随着RFID标签的大规模应用，标签的碰撞问题严重影响了RFID系统的性能，而防碰撞算法是解决该问题的关键。基于查询树防碰撞算法查询次数多的特点，文中提出了一种混合查询树防碰撞算法( HQT)。该算法结合动态二叉查询树和四叉查询树的优点，根据标签返回的碰撞信息动态地选择二叉查询树和四叉查询树的询问机制，提高了标签的识别效率，同时减少了阅读器识别标签所需的通信量。仿真结果表明，其吞吐率提高到59%左右。该算法能够提高系统的整体性能，特别是当标签数目多、标签ID位数长时，优势更加明显。
RFID is a non-contactless automatic identification technology. With the large-scale application of RFID,tag collision problems affect the performance of RFID systems seriously,and the anti-collision algorithm is the key to solve the problem. Based on the binary-tree search algorithm which requires more times to indentify all tags,an Hybrid Query Tree ( HQT) anti-collision algorithm for RFID system is presented in this paper. The algorithm combines the advantages of binary query tree with 4-ary query tree,according to the in-formation return from label to choose different query mechanism between binary query tree and 4-ary query tree dynamically. So it can quickly identify all tags by reducing the number of query-responses,and improves the efficiency of the identification. The simulation re-sults show that throughput of the algorithm is increased to 59%. Moreover. This algorithm can improve the overall performance of the system,especially when the number of labels is large,the

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该文给出了一种基于颜色分布直方图借助四叉树图像分割进行图像检索的方法,该方法使用与人类视觉感知相符合的HSV颜色模型,通过构造四叉树借助MeanShift算法对图像进行分割,提取出特征颜色,得到颜色分布的直方图。最后利用EMD算法衡量图像与图像之间的距离,实现图像的搜索。
The paper presents a method for image retrieval with the aid of image segmentation. This method is based on color distribution histogram and uses the HSV color model which is consistent with human visual. With the help of MeanShift Algo-rithm,we use quadtree to divide the image and extract the main color,which is helpful for us to get the distribution of color his-togram. Last but not least we use the EMD algorithm to measure the distance between images ,so that we can implement the im-age search.

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