具振动系数的中立型时滞微分方程解的渐近性

考虑具有振动系数的中立型时滞微分方程 [x(t)+p(t)x(t-τ(t) ) ]′ +Q(t)x(t-σ) =0 ,t≥ 0 ,其中p、Q∈C([0 ,∞ ) ,R) ,τ∈ (0 ,∞ ) ,σ∈ [0 ,+∞ ) ,Q(t)最终不恒为零。记Q+ (t) =max{ 0 ,Q(t) } ,Q-(t) =-min{ 0 ,Q(t) }。获得了该方程的每一个解或者振动或者趋于零的一个新的充分条件。     

一类一阶中立型时滞微分方程解的振动性

考虑一阶中立型时滞微分方程d/dt[x(t) p(t)x(t-τ)] f(t,x(t-σ))=0,其中p∈C([t0,∞),R),q∈C([t0,∞),R ),τ,σ∈R ,f(t,x)是定义在[t0, ∞)×R上的连续函数,讨论了上述方程的解的振动性,得出了该方程的一切解振动的充分条件。     

某类一阶非齐次中立型微分方程的振动性

研究具有正负系数的一阶非线性中立型微分方程d/dt[x（t）-R（t）x（t-r）]＋P（t）x（t-τ）-Q（t）x（t-δ）＋f（t）=0其中P，Q，R∈C（[t0,∞），R^＋）,τ,r,δ∈R^＋,τ≥δ。主要是考虑f（t）〉0时方程的振动性。     

高阶非线性中立型微分方程解的振动性

考虑一类高阶非线型中立型微分方程dndtn[x(t)-p(t)f(x(t-τ))]+Q(t)g(x(t-δ))=0,t≥t0,其中P,Q∈C([t0,∞),R+),τ,δ∈R+,xf(x)>0,xg(x)>0(x≠0),通过讨论,得到了几个保证方程所有解振动的充分条件.     

具有"积分小"系数的中立型方程的振动性

讨论中立型方程d/dt[y(t)-R(t)y(t-r)]+P(t)y(t-τ)-Q(t)y(t-σ)=0(*)其中P,Q,R∈C([t0,∞),R+),r＞0,τ≥σ＞0.在允许R(t)+∫t t-τ+σQ(u)du-1可以变号的情况下,得到了方程(*)所有解振动的一些新的充分条件.     

二阶中立型微分方程振动性的一个比较结果

考虑二阶非线性中立型时滞微分方程（x（t）-p（t）x（t-τ））″＋g（t,x（t-σ））=0其中,p∈L[0,＋∞）,τ,σ∈（0,∞）,g：[0,∞）×R→R是Corothedory函数.建立了方程与一个一阶非线性时滞微分不等式振动性之间的一个比较结果,推广和改进了文献中的相关结果.     

具振动系数的中立型时滞微分方程解的渐近性

考虑具有振动系数的中立型时滞微分方程[x(t) p(t)x(t-τ(t))] Q(t)x(t-σ）＝0，t大 于等于0，其中p,Q属于C（[0,∞),R),τ属于（0，∞），σ属于[0,∞）Q（t)最终不恒为零。记Q＋（t)=max(0,Q(t)},Q-(t)＝－min{0,Q(t)}.获得了该方程的每一个解或者振动或者趋于零的一个新的充分条件。     

具有多时滞变系数一阶中立型微分方程的振动性

考虑一阶多时滞变系数中立型微分方程d/dt[y(t)-p(t)y(t-τ)]+m∑t=1Q1(t)y(t-σi)=0其中,p,Q1∈C([t0,∞),R-),τ,σt∈R+,lim inft→xQ(t)=qi,i=1,2,…,m,得到了方程在p(t)≥1的情形下,所有解振动的两个充分性条件,推广了文献[1]中的相关结论.     

具有多时滞变系数一阶中立型微分方程的振动性

考虑一阶多时滞变系数中立型微分方程ddt[y(t)-p(t)y(t-τ)] ∑mi=1qi(t)y(t-σi)=0,t≥t0,其中p,qi∈C([t0,∞],R ),τ,σi∈R ,i=1,2,…,m,在p(t)≥1的情形下得到了方程所有解振动的充分性条件,推广了Chen MP[J Math Anal Appl,185(1994),288-301]中的相关结论.     

一类具有偏差变元的二阶泛函微分方程周期解

利用重合度理论,研究一类具有偏差变元的二阶微分方程x″+f(t,x′(t))+g(t,x(t-τ(t)))=p(t)的周期解的存在性问题.其中,f,g∈C(R×R,R),且对任意的x∈R,g(t+ω,x)=g(t,x),p∈C(R,R),τ∈C(R,R)是ω-周期的.在不要求对所有的y∈R,函数f(t,y)≤0(f(t,y)≥0),t∈R的情况下,得到该类方程至少存在一个ω-周期解的充分条件.     

Markedness and its Interpretation in Language Use

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.     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

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.     

A computer generator for randomly layered structures

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

低渗透非均质砂岩油藏启动压力梯度研究

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。     

On Tragic Consciousness In The Works By Ernest Hemingway

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.     

海南岛地体及其毗邻陆缘晚中生代—新生代古地磁研究和构造演化

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。     

An Index mechanism for multi-scale view in spatial databases

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.     

《Chinese Science Bulletin》SUBJECT INDEX TO VOLUME 59(2014)

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Achieving Unusual States of Matter Under High Pressure

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     

Exciton Seebeck in Molecular Systems

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