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1.
为提高可降解高分子材料降解模型仿真的准确程度,结合高分子材料降解的实际原则和所要考虑的各种因素,建立了适合优化的参数优化模型,并将粒子群优化算法(PSO)用于模型的求解.针对标准粒子群算法存在的一些不足,提出了一种改进的粒子群优化算法来求解最优值,改进的算法引入了动态自适应惯性权重和异步时变学习因子.采用5个标准测试函数对改进的粒子群算法进行了测试,并将算法应用于参数优化模型的求解.测试与试验结果表明:新算法有效地避免了过早陷入局部最优,提高了收敛速度和收敛精度,并且采用优化所得参数显著地提高了高分子材料降解模型仿真的精准度,有利于揭示降解机理的科学意义和指导实际医用器件的设计与生产.  相似文献   

2.
基于非线性逆透视变换的摄像机畸变参数标定   总被引:2,自引:1,他引:1  
李颢  杨明 《上海交通大学学报》2008,42(10):1736-1739
为实现摄像机畸变参数标定,提出了一种基于非线性逆透视变换模型的标定新方法.根据线性透视变换模型和畸变模型推导出非线性逆透视变换模型,以及逆透视变换参数与畸变参数之间的关系;在此基础上,建立以畸变参数为最优解的泛函,然后进行优化搜索求解.在优化搜索中,采用改进牛顿法确定搜索方向,然后,采用试探法沿搜索方向进行一维搜索.该方法仅需对数目较少的畸变参数进行优化搜索,可大幅降低优化搜索的维度和复杂度.仿真和实验结果表明:该方法正确有效,求解精度较高.  相似文献   

3.
为了深入探究Logistic模型的统计推断问题,联合半参数混合效应模型和Logistic模型建立了纵向数据半参数混合效应的Logistic模型,进一步求出该模型的极大似然函数、Fisher信息阵,利用QLB(quadratic lower-bound)算法求解参数的极大似然估计.最后进行数值模拟,结果表明在此模型的求解问题上QLB算法是Newton-Raphson算法的合理替代.  相似文献   

4.
Logistic回归健康评估模型是一种重要的健康状况评估模型,其参数选择对模型的质量有着重大影响。本文提出了一种混沌自适应粒子群算法求解Logistic回归健康评估模型参数。该算法引入惯性权重自适应策略和混沌优化策略加强算法的局部搜索能力、采用适应度方差来解决算法的早熟问题。为了验证所提出算法,本文建立了基于心率、体温、血压等健康评价指标的Logistic回归流行性感冒评估模型。仿真实验表明,本文算法能获得较优的Logistic回归流行性感冒评估模型的参数;采用该参数的Logistic回归流行性感冒评估模型的评估准确率为83.09%,能起到较好的辅助评估作用。  相似文献   

5.
一种广义Logistic模型的参数估计方法   总被引:1,自引:0,他引:1  
讨论了Logistic曲线模型结构上的缺陷,分析了广义Logistic曲线的解析性质及拟合预测的优势,提出了一种求解广义Logistic模型参数的方法.并通过预测实例,说明了该模型具有高于Logistic曲线模型的预测精度.  相似文献   

6.
为了寻找较优的铣削参数,利用改进的帝王蝶优化算法(monarch butterfly optimization,MBO)对铣削加工模型求解,得到优化后的铣削参数.通过建立铣削加工的数学模型,将实际加工时的约束条件引入到模型中.为了对模型求解,在传统的MBO算法中加入粒子群算法(particle swarm optimi...  相似文献   

7.
:为尽可能提高结构模型修正的准确性和有效性,提出一种基于模态参数和改进萤火虫算法的有限元模型修正方法. 该方法基于结构模态参数构造目标函数,使用本文提出的改进萤火虫算法进行优化求解,并通过桁架模型数值仿真将改进算法同原始萤火虫算法、遗传算法和粒子群算法进行对比,结果显示:使用改进的萤火虫算法得到的最优解更接近实际值,且离散性低,验证了改进算法求解的准确性和优越性. 最后通过六自由度剪切框架损伤识别模型试验验证了该方法在求解结构有限元模型修正问题上的准确性和有效性.  相似文献   

8.
RV减速器是机器人的核心部件,其传动精度对机器人性能起着重要作用.为提高其传动精度,建立了RV减速器的传动误差的等效模型,并利用刚度经验公式对模型的参数进行求解,得到减速器的理论传动误差.在动力学模型的基础上,采用改进遗传算法对模型中的经验公式参数进行了优化.将优化得到的误差模型与通过经验公式计算出的误差模型进行对比,...  相似文献   

9.
通过氧化锆车削试验测得切削力和刀具磨损量,以工件材料去除量与刀具磨损量的比值作为刀具利用率的量化指标.采用粒子群算法改进BP神经网络,并以此对单因素试验值进行训练预测.采用最小二乘拟合,建立刀具利用率和切削力关于各刀具几何参数的一元模型,以相关系数检验模型的可靠性.基于一元模型,分别提出了刀具利用率和切削力关于刀具几何参数的多元模型.利用粒子群算法结合正交试验值对多元模型进行优化求解,并通过验证试验证明了多元模型具有较高的精度.将多元模型作为目标函数,以刀具利用率最大和切削力最小为优化目标,基于粒子群算法进行了刀具几何参数的多目标优化,验证试验结果表明优化得到的刀具几何参数是合理的.  相似文献   

10.
针对带有有界随机扰动和概率约束的非线性模型预测控制的优化控律求解问题.采用引入粒子滤波重采样步骤改进的粒子群算法,并与粒子的变异操作相结合来求解非线性模型预测控制优化控制律的方法,提高了算法的收敛速度和控制效果.对概率约束的处理,采用对不满足约束的粒子进行有效替代的方法,进而得到满足概率约束条件的优化控制律.仿真结果表明了提出的改进粒子群算法用于优化求解非线性模型预测控制的优化控制律的可行性和有效性.  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.
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.
AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…  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.
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   

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.
19.
The elongation method,originally proposed by Imamura was further developed for many years in our group.As a method towards O(N)with high efficiency and high accuracy for any dimensional systems.This treatment designed for one-dimensional(ID)polymers is now available for three-dimensional(3D)systems,but geometry optimization is now possible only for 1D-systems.As an approach toward post-Hartree-Fock,it was also extended to  相似文献   

20.
Various applications relevant to the exciton dynamics,such as the organic solar cell,the large-area organic light-emitting diodes and the thermoelectricity,are operating under temperature gradient.The potential abnormal behavior of the exicton dynamics driven by the temperature difference may affect the efficiency and performance of the corresponding devices.In the above situations,the exciton dynamics under temperature difference is mixed with  相似文献   

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