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 78 毫秒
1.
多维O-1背包问题的混合遗传算法   总被引:5,自引:0,他引:5  
将贪婪法和遗传算法相结合,设计了一种价值密度,提出了一种求解多维0-1背包问题的混合遗传算法。经实例证明,该方法能较好地解决多维0-1背包问题并较简单遗传算法有较好的改善。  相似文献   

2.
本文分析了简单遗传算法解决背包问题时候的一些缺陷,并通过适应度函数的计算以及选择方式的改进,给出了一种基于贪心算法的混合遗传算法以解决这些缺陷。实验表明,改进的遗传算法具有一定的优越性。  相似文献   

3.
针对标准遗传算法易早熟收敛以及收敛速度慢的问题,提出一种自适应遗传退火算法用于解决高维约束优化问题.该算法采用轮盘赌和最优保存策略相结合的选择机制,并结合自适应交叉、变异概率,继而引入模拟退火算法,加快迭代后期算法的收敛速度.最后,比较了标准遗传算法和自适应遗传算法的实验结果,证明了自适应遗传退火算法在0/1背包应用中的高效性和精确性.  相似文献   

4.
基于博弈论的背包问题优化算法   总被引:5,自引:0,他引:5  
基于博弈粤论提出了一种背包问题优化算法。将背包问题的搜索空间映射为博弈的策略组合空间,背包问题的目标函数映射为博弈的效用函数,通过理性博弈主体的最优反应动态与均衡的扰动恢复过程达到优化目标。给出了算法的形式定义及描述,证明了算法的全局收敛性。仿真运算及与遗传算法的比较结果验证了算法的有效性。  相似文献   

5.
基于遗传算法的多约束背包问题求解方案   总被引:1,自引:2,他引:1  
采用混合遗传算法求解多约束背包问题.首先构建多约束背包问题的数学模型,然后采用多维实数编码方式的遗传算法,结合附带染色体库技术、局部启发式算子和扰动算子对问题进行求解,并给出了一个实验实例.实验证明文中采用这种混合遗传优化算法解决多约束背包问题切实可行,有较高的搜索效率.  相似文献   

6.
介绍了0-1背包问题的基本贪心算法,借助于启发式算法在求解NP问题中的良好表现,设计了一种基于贪心修正策略的遗传算法。该算法结合了贪心算法和遗传算法各自的优点,利用贪心算法强化了初始最优解,通过对遗传算法的改进,使其在寻求最优的过程中更具有优越性。实际数值计算和结果比较表明,该算法能有效解决0-1背包问题。  相似文献   

7.
一种改进的遗传算法   总被引:1,自引:0,他引:1  
给出一种使适合度函数参数,交叉概率和突变概率随搜索精度自适应调整的遗传算法,并以直接从输入输出数据中提取模糊规则为例与常规遗传算法进行了仿真比较,该算法明显优于常规算法。  相似文献   

8.
求解0-1背包问题的混合遗传算法   总被引:7,自引:0,他引:7  
对于0-1背包问题设计一种价值密度,并在此基础上提出求解0-1背包问题的混合遗传算法.经大量数值实验比较该方法与传统方法及简单遗传算法,结果表明算法能有效求解0-1背包问题.  相似文献   

9.
遗传退火进化算法在背包问题中的应用   总被引:22,自引:1,他引:22  
从增强算法收敛性和减少参数依赖性的角度出发,提出应用遗传退火进化算法求解背包问题,遗传退火进化算法结合了遗传算法和模拟退火算法的优点,并有效地克服了各自的弱点,使其在优化性能、优化效率和可靠性方面具有明显的优越性.阐明了用该算法求解背包问题的具体实现过程,并通过实际数值计算和结果比较表明,该算法优于遗传算法和模拟退火算法.  相似文献   

10.
通过对板材优化下料问题的研究,给出了一种较为实用的具体的模拟遗传算法,该算法融合了遗传算法和模拟退火算法的优点,兼有遗传算法中种群个体、交配、基因、遗传、变异等淘汰劣质解的操作,也有模拟退火算法中冷却进度表和接受概率等寻优控制技术,可以更好地实现板材下料问题的快速求解。  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.
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   

13.
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   

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.
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   

16.
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   

17.
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   

18.
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   

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