首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 359 毫秒
1.
基于设计结构矩阵的产品结构模块聚类方法   总被引:4,自引:0,他引:4  
阐述了当前产品结构模块聚类方法中存在的不足,并通过基于设计结构矩阵(DSM)的聚类方法较好地解决了这些不足.给出建立产品结构DSM模型的方法,并基于五点刻度法对产品结构DSM模型进行数字化.在聚类的过程中开发了基于产品结构DSM联系强度的聚类算法和基于联系成本的择优算法.以某摩托车发动机为例进行了实际建模、聚类运算及聚类择优,得出了优化的模块聚类结果.  相似文献   

2.
为了实现系统模块的合理划分和科学评价,采用设计结构矩阵(design structure matrix,DSM)的理论和技术提出了城市基础设施项目集成控制系统模块化评价方法,包括系统功能依赖强度、数量的确定以及传递成本和聚类成本的计算等.针对该类系统的更新提出将遗传算法应用到DSM聚类算法中以寻找最优更新方案.以长春基础设施项目群集成控制系统作为典型案例,比较了更新前后两阶段系统版本的模块化程度,并提出了新一代系统的更新方案,该案例验证了DSM方法在系统模块划分、评价和方案优选方面的可行性和有效性,为同类大型集成控制系统的开发和维护提供了理论和实践参考.  相似文献   

3.
为了解决自组织映射(Self-organization map,SOM)神经网络算法部分神经元过度利用和欠利用的问题,提出基于类内最小相似度的SOM算法(SOM based on intraclass minimun similarity degree,SOM-IMSD),将类内相似度这一评价指标引入SOM神经网络学习过程中,通过调整类内最小相似度来指导SOM神经网络学习,使得平均类内最小相似度最大,提高SOM神经网络的聚类结果质量.将SOM-IMSD算法应用于储层预测,并与基本SOM算法进行对比,实验结果表明,SOM-IMSD算法的聚类结果更为准确.  相似文献   

4.
针对传统生物地理优化算法(bio-geographic optimization algorithm,BBO)的种群随机初始策略会降低聚类算法性能的问题,提出了一种基于自组织映射算法(self-organization feature map,SOM)和BBO的混合聚类算法(improved SOM and bio-geography optimization,ISOMBBO),通过优化初始化神经元权值的方法改进SOM算法,然后以改进的SOM来计算数据聚类的初始簇中心,最后在BBO优化框架下进行数据簇结构的寻优.在4个标准数据集(Iris、Wine、Glass与Diabetes)的实验中,实验结果表明该算法不仅提高聚类的有效性,而且相对于传统的优化算法具有更好的优化能力和收敛度.  相似文献   

5.
基于粒子群优化和SOM网络的聚类算法研究   总被引:2,自引:0,他引:2  
利用改进的粒子群优化算法(PSO)的优化性能,结合SOM网络模型,提出了一种基于粒子群优化算法和SOM网络的聚类算法(PSO/SOM),使用PSO对SOM网络进行训练来代替SOM的启发式训练方法.将PSO/SOM算法用于对Wine和Iris等数据集进行模式聚类识别,可以得到较优的聚类识别效果.相比标准SOM算法能有效提高网络映射的准确程度,降低网络的量化误差和拓扑误差,同时也降低了错聚率,实验结果验证了本算法的有效性.  相似文献   

6.
提出面向产品设计结构的聚类分层分析方法。首先应用矩阵方法实现产品设计结构的聚类分层,然后应用模糊设计结构矩阵对模块内的零部件进行撕裂运算,得到模块内的零部件影响度和零件主次交互关系,从而实现对产品设计结构特性的分析预测,最后,以某型号冰箱产品设计结构为例,对该型号冰箱整体设计结构进行分析,得到该冰箱设计结构层级特征以及模块内零部件间的层级划分。  相似文献   

7.
数据集的质量会极大地影响分类算法的精度,针对一类隐式互斥的数值型数据提出了一致性分类方法.借鉴连续函数的思想,提出了数值型连续数据的分类一致性定义;改进了SOM算法的计算过程,使其满足文中提出的分类一致性最优条件.通过改进的SOM方法得到一个新的聚类数据集,减少了原始数据集中容易出现的隐式分类不一致性问题,从而有效地提高了分类方法的效率和分类精度.通过在一个实际的数据集上的比较,表明提出的算法的预测精度明显优于其他算法.进而还从VC维的角度分析了提出算法的优点.  相似文献   

8.
 针对采用SOM 网络进行多故障诊断时,要求多故障模式相似且不包含标准故障输出的限制,提出将SOM 网络与可拓理论相结合的多故障诊断方法.首先采用SOM 网络对训练样本进行聚类,得到故障模式及其聚类中心.然后针对每种故障模式的每个特征构造在聚类中心处取得最大值的关联函数,并以各特征的关联函数值为基础,设计多故障评价指标实现多故障诊断.最后采用汽轮发电机组振动信号的频谱数据对算法进行验证,结果表明该方法能够正确识别待诊断样本的单故障和多故障模式,具有可行性.  相似文献   

9.
针对当前数据挖掘中对数值型数据聚类方法的不足,提出了基于特征点选择的聚类算法(clustering algorithm based on Feature Point Selection,CFPS)。CFPS算法可以克服需要输入聚类数量的缺陷, 算法本身可以找到簇的最佳数量,使聚类的精度和效率得到大大提高。实验结果表明该方法对数值型数据聚类方法具有借鉴意义和深入研究的价值。  相似文献   

10.
针对保障任务交互复杂、作业流程刚性较大等问题,提出一种基于设计结构矩阵和遗传算法的飞行保障价值流层次分割优化方法。建立了真实情况下的飞行机务保障价值流传递模型,根据价值流时滞槽蓄特性分析结果,提出了通过价值活动聚类优化改善价值流通能力的思路;设计了遗传算法与DSM组合聚类优化具体步骤,并给出了DSM模型与聚类情况的映射关系;建立了基于聚类权重、聚类规模以及聚类总数的适应度函数和保障活动价值传递增益参数,进行价值活动遗传聚类算法和聚类活动解耦优化算法设计。最后,结合某机务大队保障实例对算法进行验证,结果证明所得飞行保障价值流的优化模式有效可行。  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 Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.  相似文献   

13.
王慧 《科技信息》2008,(10):240-240
Wuthering Heights, Emily Bronte's only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.  相似文献   

14.
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   

15.
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   

16.
Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.  相似文献   

17.
以AC-13级配为基础,将橡胶颗粒代替部分集料掺入混合料中,以低温弯曲试验为评价方法对不同橡胶颗粒掺量下沥青混合料的低温抗裂性进行研究,并引入应变能密度值对混合料的低温抗裂性进行综合评价.试验结果表明:橡胶颗粒沥青混合料试件的破坏微应变均超过2 300,满足冬寒区的技术指标;无论是否掺加橡胶颗粒,随着温度的下降,沥青混合料破坏时的最大弯拉强度增大,弯拉应变降低,劲度模量增大;弯曲应变能密度在胶粒掺量为1%左右时具有较大的弯曲应变能密度值,此时橡胶颗粒沥青混合料具有较好的低温抗裂性.  相似文献   

18.
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   

19.
Quality traits in wheat (Triticum aestirum L.) were studied by quantitative trait locus (QTL) analysis in a recombinant inbred line (RIL) population, a set of 131 lines derived from Chuan 35050 × Shannong 483 cross (ChSh). Grains from RILs were assayed for 21 quality traits related to protein and starch. A total of 35 putative QTLs for 19 traits with a single QTL explaining 7.99-40.52% of phenotypic variations were detected on 10 chromosomes, 1D, 2A, 2D, 3B, 3D, 5A, 6A, 6B, 6D, and 7B. The additive effects of 30 QTLs were positive, contributed by Chuan 35050, the remaining 5 QTLs were negative with the additive effect contributed by Shannong 483. For protein traits, 15 QTLs were obtained and most of them were located on chromosomes 1 D, 3B and 6D, while 20 QTLs for starch traits were detected and most of them were located on chromosomes 3D, 6B and 7B. Only 7 QTLs for protein and starch traits were co-located in three regions on chromosomes 1D, 2A and 2D. These protein and starch trait QTLs showed a distinct distribution pattern in certain regions and chromosomes. Twenty-two QTLs were clustered in 6 regions of 5 chromosomes. Two QTL clusters for protein traits were located on chromosomes 1D and 3B, respectively, three clusters for starch traits on chromosomes 3D, 6B and 7B, and one cluster including protein and starch traits on chromosome 1D.  相似文献   

20.
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   

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