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1.
研究一阶常微分方程数值解的收敛性和稳定性,利用最优化算法,确定最优化系数,得到强稳定的线性三步四阶公式,经过实际计算,结果优于目前已有的公式。  相似文献   

2.
强稳定二阶Runge-Kutta最优算法   总被引:2,自引:1,他引:2  
研究一阶常微分方程数值解的收敛性与稳定性,利用最优化方法,确定最优系数,导出两个强稳定的单步公式,并加以优化和改进,得到新的算法。经过实际计算,结果优于目前的单步公式,同时也验证了梯形公式。  相似文献   

3.
推导了一个3阶的隐式线性3步法公式,它的绝对稳定区间达到(-9.3333,0),可用于常微分方程初值问题的求解,且具有较好的稳定性。公式的相容性和收敛性在文章中得到验证,并描绘出稳定区域。最后用数值试验证明了此公式对中等刚性问题的有效性。  相似文献   

4.
对层状半空间弹性参数的反演这一具有较强的工程应用价值的问题进行了研究。先通过引入共轭波函数给出了泛函导数的表达式,然后构造一均方误差函娄把反演问题转化为寻求最优解,并通过共轭梯度法导出了非线性迭代公式,最后进行了数值计算。数值计算结果表明,该公式具有较好的收敛性和稳定性。  相似文献   

5.
超热电子输运方程是一个退化的,非局部发展方程,本文建立了一个二阶差分格式,证明了发性,收敛性和稳定性,最后给出一个数值例子。  相似文献   

6.
本文叙述了一个用序列非线性最小二乘解法求解约束最优化问题的方法,该方法采用的控制参数迭代公式具有二次收敛性及数值计算上的稳定性.非线性最小二乘问题的求解采用具有超线性收敛的修正 BFGS 方法.为验正方法的有效性,文末给出了有关数值计算的结果.  相似文献   

7.
提出一种求解Riesz空间分布阶的分数阶扩散方程的数值方法。 利用辛普森数值求积公式,将分布阶微分方程离散为一个多项分数阶导数的微分方程;利用四阶差分格式求解此具有多项分数阶导数的微分方程,并运用能量法分析数值格式的稳定性和收敛性。同时,给出数值例子,说明所建立的数值离散格式的有效性。  相似文献   

8.
本文研究一阶常微分方程数值解的收敛性与稳定性,利用最优化方法,确定最优系数,得到三个强稳定的线性两步公式.经过实际计算,结果优于目前的线性两步公式.  相似文献   

9.
采用Chang方法的混合试验的稳定性和精度   总被引:2,自引:2,他引:0  
推导了采用Chang方法的混合试验的控制公式,并采用MATLAB分析软件建立了基于Chang方法的混合试验数值模拟平台.为研究误差对采用Chang方法混合试验的稳定性和精度所造成的影响,推导了两种时滞误差影响下采用Chang方法的混合试验的收敛性公式,并利用数值模拟平台对收敛性理论结果进行验证.采用上述平台,从周期误差率和幅值误差率的角度研究了误差对采用Chang方法的混合试验精度的影响.  相似文献   

10.
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   

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.
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   

15.
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   

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

19.
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   

20.
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   

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