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1.
提出热传导方程的修正C—N显格式,x2^(n+1),z(J-1)^(n+1)的差分格式的处理方法,对算法进行了稳定性及收敛性证明,得到了修正显武热传导方程的稳定性条件为r≤3.数值实验表明,该方法稳定性好,宜于直接在计算机上使用.  相似文献   

2.
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   

3.
提出了一种数值求解一维定常对流扩散反应方程的指数型四阶差分格式.首先,由常数变易法求得模型方程的通解并应用到xi-1,xi,xi+13点上,得到模型方程的指数型差分格式.然后,利用源项f(x)在点xi处的二阶泰勒展开,得到定常对流扩散反应方程的指数型四阶差分格式.最后,用数值算例验证了该格式的高阶精度和可靠性.  相似文献   

4.
首先给出了判别f(x)的极小值点x0∈D是否为f(x)的最优解的充分必要条件(D为Rn中的闭区域);在此基础上,给出了求一元函数及多元函数全局最优解的方法.此外,还给出了求一元函数极值的一个迭代算法.  相似文献   

5.
研究了麦克斯韦方程无条件稳定的有限差分格式US—FDTD(见MicrowaveOptTechnolLett38,2003),证明了该格式是耗散和一阶精度的.在此基础上,利用减少摄动误差的技巧,我们提出了二维麦克斯韦方程改进的无条件稳定的有限差分方法(IUS—FDTD),应用傅里叶方法证明了新格式IUS—FDTD是无条件稳定的和非耗散的.误差分析表明IUS—FDTD是二阶精度的,比原格式US—FDTD的精度高一阶.数值试验比较了这两种格式的模拟效果,计算结果证实:改进的格式IUS—FDTD比原格式uS—FDTD误差小、稳定性好、精度高.  相似文献   

6.
用定性分析的方法对一类Kolmogorov系统dx/dt=x(α0-α1x+α2x^n-1-α3x^n+α4x^n-1y^m),dy/dt=y(b1x^n-b2)进行了研究.分析了该系统平衡点的性态,并得到了系统在正平衡点外围极限环的不存在性与存在唯一性的相关条件.  相似文献   

7.
对最优化方法中的梯度算法进行了改进.当2f/x2=≠0时,将二阶导数与梯度方向相结合,构造出一种新的下降方向d=[1+δ/(2f/x2)](f/x),其中δ=1或-1.用新的下降方向设计了一种算法,使梯度法得到改进.新的算法比梯度法的收敛速度快,而且比牛顿法计算量小.  相似文献   

8.
参政文献[1]的一道数列极限证明题lim n→∞ n√a1^n+…+am^n=max{a1,a2,…am}引入,将此命题推广到函数极限上,用其结论将近年来一些名校乃至全国高数考研名题轻松解决,并引入了以下几具命题: (1)lim x→+∞(f1^(x)+f2^(x)+…+fm^x(x))^x/1=max{a1,a2,…,am}。 (2)lim x→x0 (f1^φ(x)(x)+f2^φ(x)(x)+…+fm^φ(x)(x))^φ(x)/1=max{a1,a2,…,am}。并对即型的极限计算以及lim x→x0 (f1(x)+f2(x)+…+f,(x))^φ(x)/1即lim(∞+∞+…+∞)∞/1型的极限计算作了探讨。  相似文献   

9.
用MMOCAA格式(调整对流的特征线修正方法)处理半导体器件模拟的对流占优扩散问题,通过对对流项进行调整,仅增加少童计算量,使该问题既保持了全局质量守恒性质,又具有MMOC格式(特征线修正技术)的所有优点.进行了理论分析,得到了最优阶L^2模误差估计结果.  相似文献   

10.
《今日科技》2005,(7):48-48
韩国大宇目前发布了一款名为Pinno的功能强大的PMP播放器。这款Pinno PMP内置20GB和30GB的4.572cm(1.8英寸)硬盘,屏幕采用8.89cm(3.5英寸)的超大26万色TFT显示屏。Pinno除了支持MP3/WMA/WAV/OGG格式的音频播放之外,还支持MPEG4、DivX 3x,4x,5x,5.0pro、XviD、ASF等格式的视频播放,图片浏览功能则支持JPEG(Exif2.2)、BMP、GIF、TIFF格式。传输接口采用USB2.0,内置锂电池设计,可以支持长达12h的音频播放和5h的视频播放。  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.
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   

16.
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   

17.
AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…  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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