共查询到20条相似文献,搜索用时 890 毫秒
1.
利用打靶法讨论奇异非线性n阶常微分方程边值问题u(n)(t)+f(t,u)=0,t∈(0,1),u(k)(0)=0,0≤k≤n-2,u′(1)=c正解的存在唯一性,其中c是非负实数,函数f(t,u)在(0,1)×(0,∞)上非负连续,并且关于u单调不增 相似文献
2.
陈传淡 《厦门大学学报(自然科学版)》1999,38(6)
1 一维守恒双曲型标量方程的初边值问题解法讨论一维标量守恒双曲型方程 ut+f(u)x=0(1)的纯初值问题 u(x,0)=φ1(x)(-∞<x<∞)(2)及初边值问题 u(x,0)=φ1(x),(0≤x<∞) u(0,t)=φ2(t)(0≤t<∞)(3)并得到如下结果:1)问题(1),(2)当1+f″φ1′t≠0时的隐式解为 u(x,t)=φ1(x-f′(u(x,t))t)(4)2)问题(1),(3)当1+φ′1f″t≠0,1-φ2′xf″/(f′)2≠0时的解为 u(x,t)=φ1(x-f′… 相似文献
3.
利用R^1中两点边值问题的Green函数,给出了Banach空间中两点边值问题(-u″=f(t,u,u′),u(0)=u(1)=0t∈I的解的存在性,推广了已有的结果。 相似文献
4.
四阶泛函微分方程边值问题的上下解方法 总被引:2,自引:0,他引:2
翁佩萱 《华南师范大学学报(自然科学版)》2000,(3):1-6
利用和发展微分方程边值问题上下解方法,讨论了四阶泛函数分方程边值问题u^(4)(t)=f(t,u(w(t))m,u^″(t),0〈t〈1;u(s)=ψ(s),s∈「-τ,0,ψ(0)=0,u(1)=u″(0)=u″(1)=0 解的存在性定理。 相似文献
5.
丁勇 《江西师范大学学报(自然科学版)》1996,(4)
该文给出了如下定义乘积空间Rn×Rm上一类带粗糙核的Marcinkiewicz积分算子μΩ,b(f)的L2(Rn×Rm)有界性:μΩ,b(f)(x,y)=(∫∞0∫∞0|Fb,t,s(x,y)|2dtdst3s3)1/2,这里,Fb,t,s(x,y)=|x-u|≤t|y-v|≤sΩ(x-u,y-v)b(|x-u|,|y-v|)|x-u|n-1|y-v|m-1f(u,v)dudv,且Ω为原子Hardy空间H1a(Sn-1×Sm-1)中的函数,b为空间l∞(Lq(R+×R+)中的径向函数 相似文献
6.
康庆德 《河北师范学院学报》1996,(4):1-4
设n=2^λ-1+t,λ〉2,0≤t〈2^λ-1。反馈函数xn=f(x0,x1,…,xn-1)=1+x0+Σi∈It(xi+xn-i)产生n阶de Bruijn-Good图Gn的一个完全因子PFλ(2^λ-1+t)其中It={t;(ti)是奇整数,1≤i≤t}。 相似文献
7.
讨论一维 p Laplacian 奇异非线性边值问题(g(u′))′= - K (t)f (u), 0 < t < 1,u(0) = 0, u′(1) = c正解的存在唯一性, 其中 g (s)= |s|p- 2s, p > 1, f (u )在(0,+ ∞)上是非负、非增的右连续函数. 相似文献
8.
关于有理系数微分方程的复振荡理论 总被引:1,自引:1,他引:0
证明了:如果Bk-j(j=1,…,k)为有理函数,在。点有nk-j(>0)阶极点,存在某个Bk-s(1≤ s ≤ k)满足:当j≠ s时,有nk-j/j<nk-s/s.假设F(z)0为亚纯函数,且λ(1/F)<σ(F)=β=(nk-s+s)/s.如果微分方程f(k)+ Bk-1f(k-1)+…+ B0f= F的所有解为亚纯函数,则每个解/满足σ(f)=(nk-s+s)/s. 相似文献
9.
张俊祖 《陕西师范大学学报(自然科学版)》1999,27(3)
研究了具有时滞的非线性积分方程振动性问题, 给出了方程 x (t)+∫t0k(t- s) G(s,x(s),x (s- τ(s)))ds= f (t)在非线性项 G(t,u,v)关于 u,v 为增函数时,其解振动的充分条件及当强迫项 f(t)为振动函数时,其无界解振动的充分条件 相似文献
10.
黄永亨 《福州大学学报(自然科学版)》1963,(2)
极值原理是椭圆型方程和抛物型方程解的最基本性质之一,在线性及非线性方程各种定解问题的研究中起着重要的作用。本文对如下的拟线性抛物型方程在有界域和无界域中建立起相应的极值原理并解决第一、第二边值问题和Cauchy问题解的唯一性,这里而ξ是n维欧氏空间中的实向量,h(x,t,u,p)是正的半连续函救。设u(x,t)∈ C2(G)∩ C(G)和我们有: 定理1。设f(x,t,u,0)≥0当u≥0和f(x,t,u,p)这里α=α(M1,M2).若(u,t)在G的某内点P0(x0,t0)取得非负最大值M,则在G的子域s(P0)中有u(x,t)≡M,这里s(P0)中每一点可用一简单曲线联结到P0,沿此曲线的t坐标是不减的。 定理2。设定理1的条件成立,又设G的边界点P0处可作内切球,在P0点的法线方向不平行于轴。若u(x,t)在P0处取到正的最大值 M且u(x,t) Const,则 snl这里l为过P0点与内法线n交于锐角的任一方向且自然假设存在。 对于条形域G:中考虑的Cauchy问题我们有定理5。设 且则 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.
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
13.
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 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
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.
Miao Maosheng 《华南师范大学学报(自然科学版)》2014,(6)
正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula- 相似文献
18.
Yang Weitao 《华南师范大学学报(自然科学版)》2014,46(6):137-138
We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re- 相似文献
19.
Bernard Kirtman 《华南师范大学学报(自然科学版)》2014,(6)
正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that 相似文献
20.
《上海师范大学学报(自然科学版)》2014,(5):550
<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with 相似文献