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1.
曲梁剪应力的积分方程解   总被引:1,自引:0,他引:1  
直接对曲梁剪应力的积分方程求解 ,导出了曲梁剪应力和径向应力的计算公式 .这些公式不仅满足平衡方程 ,而且满足曲梁上、下表面处力的边界条件 .将该理论用于研究悬臂曲梁在自由端受集中力作用的情况 ,计算结果表明 ,与其他采用附加假设的近似解相比 ,据此得到的应力解具有很高精度 ,同弹性理论解和有限元解非常接近 .  相似文献   

2.
讨论了椭圆型方程边值问题在球形域上径向解的存在性问题,证明了在满足一定条件下,方程至少存在1个正的径向解,还得到与边值有关的三重正径向解的存在性.  相似文献   

3.
利用函数不变集理论,讨论了径向对称的N维拟线性热方程的演化不变集和精确解,给出了径向对称的拟线性热方程在伸缩群上不变时满足的约束条件,求解约束条件得到了上述方程的一些精确解.  相似文献   

4.
为了考察双马达驱动系统输出力矩同步性对弹性负载变形与应力分布的影响,研究了简化的双力矩驱动弹性圆柱负载模型.基于连续弹性体的振动理论,建立双力矩驱动弹性圆柱负载的一维扭转振动方程,给出了弹性圆柱负载变形与剪应力的解析解.对解析解的分析表明,当输入力矩完全同步时,变形与剪应力中的奇数阶模态响应将被抑制;数值计算结果表明,当输入不相同的阶跃转矩时,负载的最大剪应力水平将显著增加.  相似文献   

5.
屈改珠 《河南科学》2014,(9):1683-1684
利用函数不变集方法,讨论了径向对称的N维拟线性热方程的旋转不变集和精确解,给出了径向对称的拟线性热方程在旋转群上不变时满足的约束条件,进一步求解约束条件得到了上述方程的一些精确解,文中的结果推广了Galaktionov关于非线性演化方程的结论.  相似文献   

6.
研究了径向空间中带有Sobolev临界指数的Schr?dinger方程,不要求方程临界项带有的位势满足周期或渐近周期的相关条件.主要利用Nehari流形和Ekeland变分原理找到相应流形上的极小化序列,进而证明基态径向解的存在性.最后运用强极大值原理证明方程的解是正解,从而得到方程的正基态径向解.  相似文献   

7.
探讨了地球自转产生的离心力对地壳中应力分布的影响。分析中,将岩石圈分离出来单独对待。利用弹性力学中的轴对称回转面型薄壳理论对其进行处理。通过建立理论方程进行求解后得出地壳中应力分布规律为:径向以挤压力为主,在赤道一线最大,极地最小,且有很小一部分为引张应力。而纬向全为引张应力,从两极赤道逐渐增大,径向剪应力则为45°为最大,赤道和两极均为零。  相似文献   

8.
研究了满足一组热力学关系的粘滞电磁流体学的流体的场方程,显示出Einstein-de Sitter模型是这组场方程的精确解。这解是径向流动流体的解,满足所有必需的物理条件。  相似文献   

9.
在机械设计与应用中,为了计算扇形截面杆在外力偶作用下,杆的扭转角和横截面上的剪应力,提出了一种数值计算方法.柱体扭转的基本方程为非齐次偏微分方程,在极坐标系下,利用分离变量法及特解法,求出扭转应力函数,再由边界配置法计算出满足扭转问题边界条件的待定常数,得到了扭转应力函数的近似数值解,进一步即可计算横截面上的剪应力.给出了几种不同顶角的扇形截面杆的剪应力与扭转刚度,计算结果表明,这种方法具有足够的精确度,有一定实用价值.分离变量法与边界配置法的结合,简化了计算过程,适宜于工程设计应用.  相似文献   

10.
离心钢管混凝土结构弹性扭转应力分析   总被引:2,自引:0,他引:2  
采用弹性力学的基本分析方法,建立了离心钢管混凝土构件扭转作用的基本方程。假定应力函数的基本模式,令其满足平衡方程及力的边界条件;通过对层合材料扭转余能的变分使协调条件得到近似满足,确定了离心钢管混凝土构件在扭矩作用下的横截面及层间剪应力的具体计算公式。  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.
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   

14.
AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…  相似文献   

15.
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   

16.
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   

17.
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   

18.
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   

19.
20.
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   

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