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1.
给出了多步Runge-Kutta法(MIRK)解延时微分方程(DDEs)的Pm-稳定性.着重研究此法用于下列具有m个延时量的线性试验方程时的稳定性态。u’(t)=au(t)+(t-τj),t≥0.u(t)=(t),t≤0.其中a,bj(j=1,2,…,m) ∈C,τm≥τ(m-1)≥…≥τ>0,(t)给定.证明了m=2时,MIRK法是P2-稳定的.对于m>2,得到同样的结果(Pm-稳定).  相似文献   

2.
研究Runge-Kutta方法的GPmL-稳定性,着重研究用隐式Runge-Kutta方法去解如下方程时的数值稳定性,y’=(t)=Ly(t)+M1y(t-τ1)+…+Mmy(t-τm),t≥0,y(t)=Φ(t),t<0,其中L,Mi(i=1,…,m)是N×N复矩阵,0<τ1≤τ2≤…≤τm,Φ(t)是一个已知向量函数,证明隐式RK方法是GPmL-稳定的当且仅当它是L-稳定的.  相似文献   

3.
本文将Runge-Kutta法应用于解多个滞时的微分方程.主要研究该方法数值解线性试验方程y'(t)=ay(t)十b1y(t—τ1)十b2y(t—τ2)(其中τ2≥,τ1>0,a,b1,b2为复数)的稳定性态.我们证明满足条件det(I—xA)=0det[I—A十xebT」≠0(x∈C)的Runge-Kutta法是GP-稳定的当且仅当该方法是A-稳定的.  相似文献   

4.
用多步Runse-Kutta方法去解如下形式的试验方程其中y(t)=(y1(t),y2(t),…,yN(t))T,L和M是复N×N矩阵,τ>0,Φ(t)是一个已知向量函数,当t≥0时y(t)是未知的.主要解决了延时微分方程多步Runge-Kutta方法的P-稳定性.  相似文献   

5.
介绍了延时微分方程组的Pm L稳定性⒚用隐式RungeKutta 方法去解如下形式的含有m 个延时量的线性试验方程组:y′(t) = ay(t) + mj= 1djy t- τj , t≥0y(t) = φ(t) ,         t≤0其中a,bj(j = 1,2,…,m ) ∈C,τm ≥τm - 1 ≥…≥τ1 > 0⒀φ(t) 是已知函数⒚当m = 2 时,证明隐式RungeKutta 方法是P2L稳定的充要条件是它为L稳定的⒚当m > 2 时,此结论也成立⒚  相似文献   

6.
本文主要利用H( t,s)型函数和广义Riccati变换技巧,建立二阶中立型时滞拟线性微分方程[r(t)|x′(t)|γ-1x′(t)]′+q0(t)|y(t -σ)|γ-1y(t -σ)+q1(t)|y(t -σ1)|α-1y(t -σ1)+q2(t)|y(t -σ2)|β-1y(t -σ2)=0.其中x(t)=y(t)+p(t)y(t-τ),在0≤p(t)≤1的新的振动准则.  相似文献   

7.
利用二阶徽商的四阶精度紧致差分逼近公式,给出解抛物型方程精度为O[1-20)t,t2+x4]的一种新的加权差分格式,并通过Fourier方法讨论格式的稳定性.证明了当1/2≤θ≤1时,格式是无条件稳定的;当0≤θ<1/2时,只有r≤1/3(1-2θ),格式才是稳定的,其中θ是加权参数(因子),t,x分别为时空方向的网格长度,r=(D是二阶导数项系数).  相似文献   

8.
研究单参数方法解中立型微分方程组x'(t)=Ax(L-τ)+Bx(l)+Cx'(l-τ)的数值稳定性性态,其中A,B,C是实对称矩阵及τ>0.并且,我们研究了稳定域的特征.  相似文献   

9.
研究了随机系统dx(t)=〖A+^-A(t)x(t)+(B+^-B(t-τ1(t))x(t-τ1(t)〗dt+g(t,x(t),x(t-τ2(t)dω(t)的指数稳定性,引入对应的稳定性系统(无不确定性、随机扰动与时滞)x(t)=(A+B)x(t)并设定是指数稳定的,应用Razumikhin定理证明了当不确定性^-A与^-B、随机扰动g及时滞τi(i=1,2)充分小时,原随机系统仍指数稳定。  相似文献   

10.
引入复合二项Kantorovich-Stieltjes算子(S_rv)(x)=S_(k,τ)(x)(τ>0,0≤x≤1),证明了当τ→+∞时,(S_τv)(x)在(0,1]上几乎处处收敛于v关于Lebegue测度的绝对连续部份的Radan-Nikodym导数f(x).同时也证明了PoissonK-S算子(S_τv)(x)=(τdv)在[a,b](0,+∞)上也有类似的结论.  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.
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   

15.
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   

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.
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   

19.
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   

20.
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   

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