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1.
针对人工鱼群算法精度不高,后期收敛速度慢等缺点,文章提出了一种基于文化算法框架的遗传人工鱼群优化算法。该算法利用文化算法框架,建立了遗传算法优化的信仰空间和人工鱼群算法优化的种群空间,两个空间并行演化,同时通过接受函数和影响函数相互促进,克服了人工鱼群算法易陷入局部极值导致后期收敛速度慢和精度不高的缺点。通过对4个基准测试函数进行求解,表明了该算法相比基本鱼群算法在求解过程中精度更高,鲁棒性更强,收敛速度更快。  相似文献   

2.
人工鱼群算法虽然具有不需要了解问题的特殊信息,能够寻找到一定的搜索方向,对初值和目标函数的要求不高等优点,但在人工鱼群算法的后期,有一部分人工鱼会聚集在局部最优周围或者处在漫无目的地随机游动状态,从而影响算法寻优的精度及收敛速度.针对这一不足,引入DNA交叉和DNA变异操作,提出一种基于DNA的改进人工鱼群算法.通过函数测试表明,该算法在搜索精度、可靠性、稳定性和鲁棒性4个性能上相比于基本人工鱼群算法更有效.  相似文献   

3.
针对无人机在复杂海域地貌中的三维路径规划,在人工鱼群算法的基础上提出了一种改进的适应性人工鱼群算法。首先,利用数学模型建立地貌的三维模型,选取路径最短为性能评价函数,保证路径规划的合理性;其次,考虑到传统的人工鱼群算法前期收敛速度慢,后期需要精确搜索提高算法精度,提出自适应步长和自适应视野范围来更新个体的位置。为了避免算法陷入局部最优,在追尾行为中引入鱼群中的社会经验位置进行更新;最后,利用MATLAB对在3个复杂程度不同的地图中与传统的人工鱼群算法与粒子群算法对比,仿真结果表明改进后的人工鱼群算法在三维路径规划问题求解中具有更好的收敛速度和精度。  相似文献   

4.
针对人工鱼群算法(AFSA)存在收敛速度慢和寻优精度低等问题,本文提出了一种改进人工鱼群算法(IAFSA).该算法中的人工鱼能够根据鱼群当前状态调整自身的视野和步长来平衡局部搜索和全局搜索.此外,算法中还加入了引导行为,即人工鱼在觅食行为未发现更优的位置时,当前人工鱼向最优人工鱼移动一步.仿真结果表明,改进人工鱼群算法在收敛速度、寻优精度和克服局部极值等方面有很大优势.本文将改进鱼群算法应用时滞系统的辨识中,辨识结果表明改进算法能获取被控对象的精准数学模型,并具有较强的抗干扰能力.  相似文献   

5.
城市供水时用水量预测精度对城市供水系统具有重要影响.传统的反向传播(back-propaganda,BP)神经网络预测方法容易陷入局部解,并且需要大量的训练数据.人工鱼群算法具有较优的全局收敛能力及较快的寻优速度.为此,利用人工鱼群算法对BP神经网络的初始权值和阈值进行优化,建立了一种新的时用水量预测模型.将该模型应用到华北某市时用水量的预测中,预测结果表明人工鱼群神经网络算法的均方差比BP神经网络算法的均方差小5%.实例证明,人工鱼群神经网络比BP神经网络的预测精度更高,收敛速度更快.人工鱼群神经网络算法可用于短期水量预测.  相似文献   

6.
张艳  许恒迎 《科技信息》2011,(30):282-283
本文首先分析比较了国内外各种已有的PMD补偿算法,其次简要介绍了基本人工鱼群算法。为提高局部搜索能力和寻优精度,重点对基本人工鱼群算法进行了改进,提出了智能视野和步长的概念,并将这种改进型人工鱼群算法应用于自适应PMD补偿中。3个经典测试函数和PMD补偿仿真实验的结果表明:该算法具有更高的寻优精度和克服局部极值的能力,是一种适用于PMD补偿的优秀算法。  相似文献   

7.
一种新的粒子群算法与人工鱼群算法的混合算法   总被引:3,自引:2,他引:1  
通过分析粒子群算法和人工鱼群算法的优缺点,利用粒子群算法收敛速度快及人工鱼群算法能较好地收敛到全局最优解的特点,提出了一种新的混合算法.算法以粒子群为基础进行设计,根据人工鱼群的公告板、群聚和随行策略的模式对粒子群进行速度与位置变更,使原有的粒子群变成具有一定智能的粒子,从而达到提高搜索精度及效率的目的.通过Generalize-Schwefel等3个经典函数进行优化仿真后发现,该混合算法具有搜索精度更高及收敛速度更快的特点,同时该算法在求解高维问题时具有明显优势.  相似文献   

8.
针对人工鱼群算法搜索速度和搜索精度不高,且对高维问题寻优能力较差等缺点,提出了一种改进的人工鱼群算法——分类觅食人工鱼群算法(Assorted Foraging Artificial Fish Swarm Algorithm-AFAFSA)。该算法对执行觅食行为的个体分类进行更新,既保持种群的多样性又通过觅食行为加快算法的搜索速度,同时加入禁忌的思想帮助算法跳出局部最优,提高算法的性能。通过一系列的测试试验,发现改进算法在收敛速度和精度方面都有了明显的提高,对于高维问题有也具有较好的寻优能力。  相似文献   

9.
一种人工鱼群混合智能优化算法   总被引:1,自引:0,他引:1  
针对人工鱼群算法一般在初期拥有较快的收敛性,后期收敛较慢的特性,笔者提出一种改进的人工鱼群算法——GPAFSA.该算法将杂交PSO算法引入到人工鱼群算法中,在人工鱼群算法陷入局部最优时,通过使用杂交PSO算法,克服陷入局部最优的缺陷,实现全局最优.仿真实验表明,该算法在收敛性、全局寻优方面比原始算法有很大提高.  相似文献   

10.
针对人工鱼群算法(AFSA)在函数优化问题中易陷入局部极值和求解精度较低的缺点,提出了一种在基本人工鱼群算法中引入水流作用机制的改进方案。通过水流作用机制中的持续性水流和周期性水流对鱼群施加的有益影响来改进原有算法。持续性水流影响鱼群的体力变化从而控制视野和步长参数的自适应调整以提高求解精度;周期性水流冲击鱼群并改变部分鱼的位置,从而保持鱼群的种群多样性以利于全局收敛。仿真实验结果表明:本文的改进算法具有更高的求解精度和更好的全局搜索性能,并验证了算法的有效性。  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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