首页 | 官方网站   微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 78 毫秒
1.
介绍树搜索法、邻接矩阵法、节点标记法三种方法进行电网拓扑分析的原理,指出三种算法中考虑网络中局部支路开关变化时的网络数据模型的修正方法.分别采用三种方法对RBTS和RTS79的输电网络、RBTS-BUS6的配电网络进行电网连通性分析.算例分析表明:树搜索法进行环网拓扑分析时,重复搜索较多;邻接矩阵法的直观性较好,但是数据储存空间开销大,自乘运算的时间随着网络增大而迅速增加,适合小规模网络连通性分析;节点标记算法高效快捷、占用内存少,较适合进行大规模电网的连通性分析.  相似文献   

2.
本文引进带时间的Petri网,给出分布式数据库中并发控制中的时间标记算法(time stemp)的Petri网形式描述,并利用带时间的Petri网理论分析和验证时间标记法的有关性质。  相似文献   

3.
多示例多标记学习在多语义对象处理中克服了多示例学习和多标记学习的缺点,成功应用于文本分类、图像识别标注、基因数据分析等任务中.其中基于退化策略的多示例多标记学习算法,多利用K-Medoids聚类将多示例多标记退化成单示例多标记,但此种退化方式过于简化多语义和复杂语义的对象,并未考虑示例间的相关性,导致退化过程中的信息削弱甚至丢失.针对这一问题,提出了结合均值漂移的多示例多标记学习改进算法(MultiInstance Multi-Label with Mean Shift,MIMLMS),将高斯核函数和权值加入均值漂移中.权值的加入保证了示例之间的相关性得以保留,而将多示例集合加入高斯核函数就可利用核密度估计和梯度下降法求解退化过程最优解,最终以误差平方和为分类目标函数,建立多示例多标记分类模型.算法在基准的多示例多标记测试数据集中的实验结果,验证了算法的良好分类效果及算法的有效性和可靠性.  相似文献   

4.
现有大多数多标记流特征选择算法在进行特征选择时,往往忽略标记间的相关性,易导致算法预测精度的下降。为解决这一问题,提出一种结合邻域信息和标记相关性的在线多标记流特征选择算法;定义自适应邻域关系解决邻域粗糙集的粒度选择问题,将其推广到多标记学习中;利用互信息计算标记间的相关性得到标记权重;通过邻域粗糙集和标记权重评估特征和标记间的相关性,并设计特征在线重要度分析、在线相关性分析和在线冗余度分析3种指标,以实现在线评价动态候选特征。在7组多标记数据集以及5个评价指标上的实验结果表明,所提算法综合性能较优。  相似文献   

5.
为了解决当前图像轮廓识别算法中由于区域标记和轮廓标记性质不同,导致难以将多标记融合识别技术应用于图像轮廓识别中的问题,本文提出了一种基于环绕数约束的能量最小化模型,用以精确识别目标轮廓.在这种模型中,区域标记(如颜色和纹理均匀性)和轮廓标记(如局部对比度和连续性)通过一个目标函数进行描述,实现多标记融合识别.首先,将环绕数作为约束,将其引入到能量最小化模型中,得到区域标记与轮廓标记的线性约束;然后,对区域标记、轮廓标记以及曲率标记进行融合,实现对图像中目标轮廓的识别;最后,将能量最小化模型与标记相结合,通过比率能量函数对算法进行实例应用分析,验证算法的有效性.实验结果表明:与传统轮廓识别算法相比,所提算法具有更高的轮廓识别精度.  相似文献   

6.
从网络拥塞和速率控制面临的困境入手,分析了拥塞定价机制在弹性流速率控制中的应用.针对已有的梯度投影算法收敛速度慢、效率不高的问题,提出了一种基于近似共轭梯度法的链路价格调整算法.分析了基于概率标记的端到端价格传递机制,并将0-1分布的点估计和区间估计结合起来,提出了一种样本量自适应调整的价格估计方法.实验结果表明,近似共轭梯度法链路价格调整算法与样本量自适应的概率标记价格传递机制相结合,可以使速率分配快速收敛到用户总效用最大化的网络优化目标.  相似文献   

7.
XML索引为查询处理提供了高效的帮助,其中F&B索引是已知的处理分枝查询的最小的索引,但快速创建F&B索引和利用F&B索引完成查询处理的算法却很少有人研究.本文提出了一种素数序列标记法,这种标记法不仅有助于快速的建立F&B索引,更可以高效的完成F&B索引上的查询处理.此外,我们还给出了基于素数序列标记法的查询处理算法,即素数整除匹配算法,该算法可以高效的判定某节点是否有某分枝子结构.实验表明基于素数序列标记法的F&B索引创建方法比SAM算法快,在多个数据集F&B索引上素数整除匹配算法优于关联路径连接算法和TwigStack算法.  相似文献   

8.
数据规模的不断增加,使得为数据库中全部样本做标记变得尤为困难,数据集也因此呈现出了明显的弱标记性.为此,针对大规模少数标记数据集的特征选择问题,基于经典的Relief-F算法,通过综合考虑有标记样本与无标记样本对数据样本近邻的影响,重新定义样本近邻的搜索策略,提出了一种面向符号数据的半监督特征选择算法.为进一步分析新算法的有效性,仿真实验中选取了5组UCI数据集,并引入机器学习中3个常用分类器对新算法和对比算法的特征选择结果的分类性能作了分析和比较,实验结果很好地验证了本文中提出的新算法的有效性和可行性.  相似文献   

9.
【目的】针对在标准协同训练中不具有充分冗余的视图分割,致使分类器错误累计过多,以及一对基分类器标记样本类别不一致的问题,提出了基尼指数结合K均值聚类的协同训练算法。【方法】该算法首先计算已标记样本中各特征的基尼指数,将该指数升序排列后均等划分到两个视图,然后在基分类器所标记的样本中,运用K均值聚类确定标记不一致样本的类别后加入标记样本。【结果】通过9个UCI数据集在3组实验上的结果表明,所提算法相较于对比算法提升了分类效果。【结论】运用基尼指数均等划分关键特征于两个视图,有利于改善视图分割不充分冗余的缺陷;K均值聚类法对分类不一致样本进行重新标记,降低了协同训练算法中的误标记率。  相似文献   

10.
为实现特钢棒材生产信息的全流程可追溯,分析特钢棒材生产环境及形状特点,采用基于双标志点的标记方案进行标记并利用机器视觉技术实现成捆特钢端面字符的识别。首先,采用Hough变换将成捆特钢棒材端面图像分割成单根;其次,采用基于小波变换的图像增强算法完成单根特钢棒材端面图像的增强;再次,将MSER算法和边缘检测算法相结合完成单根特钢棒材字符区域的检测,并基于投影法完成字符的分割;最后,通过创建和训练SVM分类器完成每一根特钢棒材端面字符识别,并将成捆特钢棒材端面字符识别结果输出保存。结果表明,新算法可以满足成捆特钢棒材生产过程中字符识别要求,字符识别准确率可达到97.35%。新算法将Hough变换、基于小波变换的图像增强算法、MSER算法、边缘检测算法、投影法及SVM分类器等算法融合到特钢棒材端面字符识别过程中,为特钢棒材生产过程中的信息获取、信息传递及信息追溯的技术实现提供了参考。  相似文献   

11.
Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.  相似文献   

12.
The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3~4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰~ -7.8‰, PDB) and matrix dolomites (-6.6‰~ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084~0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078~0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.  相似文献   

13.
何延凌 《科技信息》2008,(4):258-258
Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women's language from these perspectives: pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women's language, more attention should be paid to language use in social context. What's more, the linguistic phenomena in a speaking community can be understood more thoroughly.  相似文献   

14.
理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。  相似文献   

15.
AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…  相似文献   

16.
As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.  相似文献   

17.
本文叙述了对海南岛及其毗邻大陆边缘白垩纪到第四纪地层岩石进行古地磁研究的全部工作过程。通过分析岩石中剩余磁矢量的磁偏角及磁倾角的变化,提出海南岛白垩纪以来经历的构造演化模式如下:早期伴随顺时针旋转而向南迁移,后期伴随逆时针转动并向北运移。联系该地区及邻区的地质、地球物理资料,对海南岛上述的构造地体运动提出以下认识:北部湾内早期有一拉张作用,主要是该作用使湾内地壳显著伸长减薄,形成北部湾盆地。从而导致了海南岛的早期构造运动,而海南岛后期的构造运动则主要是受南海海底扩张的影响。海南地体运动规律的阐明对于了解北部湾油气盆地的形成演化有重要的理论和实际意义。  相似文献   

18.
There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.  相似文献   

19.
In the 19th century the society was controlled by men, and women were just appendants of them, they had not any rights and freedom. But Jane was an exception, she showed some characteristics of early feminist. Jane showed her characteristics of feminism in three aspects: rebellion, equality, and independence. These characteristics were helpful to her success, and feminism is the only way out for women of that time.  相似文献   

20.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司    京ICP备09084417号-23

京公网安备 11010802026262号