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1.
共轭方向算法中搜索方向依赖于对参数β^(k)的选取s^(1)=-g^(1),s^k+1)=-g^(k+1)+β^(k)s^(k),k≥1。本文给β^(k)适当条件以保证算法的下降性,并在广义Armijo步长搜索下,给出了算法的收敛性证明。  相似文献   

2.
研究共轭梯度算法的整体收敛性,在放宽了的强Wolfe搜索(18)、(19)下证明了[1]中提出的修正HS共轭梯度算法的收敛性,在充分下降性条件下,βk=maxβHSk,0{}时也具有整体收敛性,同时,βk=max0,βPRk{}时,利用Armijo搜索和Goldstein搜索的共轭梯度法也具有整体收敛性.  相似文献   

3.
具有充分下降性的修正PRP算法及其收敛性   总被引:2,自引:0,他引:2  
共轭梯度法因其算法简单、存储需求小,非常适合于求解大规模优化问题。在所有的共轭梯度法中,PRP方法被认为是数值表现最好的方法之一。然而,对一般非凸函数,PRP方法即使采用精确线搜索也不能保证全局收敛。本文基于一个修正的PRP公式,提出了一类无需线搜索而具有充分下降性的共轭梯度算法。在一定条件下,建立了该算法的全局收敛性结果。数值试验表明这种改进是有效的。  相似文献   

4.
给出了求解无约束优化问题的一类下降算法,该算法具有充分下降性的共轭梯度公式.并且在较为温和的条件下利用宽松的非精确线搜索条件,给出了全局收敛性定理。  相似文献   

5.
文章给出了一个改进的共轭梯度公式及新公式的相关性质,新公式和DY公式结合得到一个混合共轭梯度法,新算法在Wolf线搜索下产生一个下降方向;并证明了算法的全局收敛性,给出了数值例子.  相似文献   

6.
文章给出了一个改进的共轭梯度公式及新公式的相关性质,新公式和DY公式结合得到一个混合共轭梯度法,新算法在Wolf线搜索下产生一个下降方向;并证明了算法的全局收敛性,给出了数值例子.  相似文献   

7.
给出一类求解非线性无约束优化问题修正的共轭梯度类型公式和算法,并证明该公式在广义Wolfe线搜索下具有充分下降性和全局收敛性。  相似文献   

8.
一类下降算法及其全局收敛性   总被引:3,自引:0,他引:3  
提出一类无约束优化下降算法,证明了Amijo搜索和Wolfe搜索下的全局收敛性。算法类似于共轭梯度法,但与其不同,它具有更宽的βk选取范围。  相似文献   

9.
给出一类求解非线性无约束优化问题的共轭梯度新算法。 在强Wolfe-Powell线搜索下所给公式具有充分下降性, 所给该新算法具有全局收敛性。  相似文献   

10.
对共轭下降法中参数βk的取值进行了拓广,得到了一类共轭下降法,并证明了在一种新的Armijo线搜索下这一类共轭下降法的全局收敛性.  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.
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   

16.
AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…  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.
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   

19.
正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-  相似文献   

20.
We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-  相似文献   

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