首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 531 毫秒
1.
当丢番图方程∑i=1^n∑j=1^naijyiyj=0有一组非平凡的整数解y1^*,y2^*,…,yn^*(yn^*≠0)时,给出了方程∑i=1^n∑j=1^n(aij)/xixj=0满足(x1,x2,…,xn)=1的全部整数解的公式.  相似文献   

2.
带权的排序问题和二次规划   总被引:3,自引:0,他引:3       下载免费PDF全文
把带权的排序问题1‖∑ωjCj表示成一个二次规划,证明这个二次规划最优解的充分必要条件是成立WSPT规则,从而也证明WSPT规则是带权排序问题的充分必要条件。同时还证明了1‖∑ωjCj问题目标函数的最小值是∑i=1^n∑j=1^upπ(j)ωπ(i),为用二次规划研究其他带权的排序问题打下基础。  相似文献   

3.
文章给出不定方程∑j=1 ^h (x j)^n=(x h 1)^n的解的一个改进结果。  相似文献   

4.
时滞细胞神经网络模型的渐近性态分析   总被引:1,自引:0,他引:1  
对具有时滞的神经网络模型xi(t)=-Cixi(t) ∑j=1^n aijfj(xj(t)) ∑j=1^n bijfj(xj(t-τj)) Ii,i=1,2,…,n,在非线性神经元激励函数满足Lipachitz连续的条件下通过构造适当的泛函,研究了这类模型的渐近性态,获得了这类模型全局吸引和平衡点的全局指数稳定易于验证的充分条件.  相似文献   

5.
讨论了一类独立非负随机变量列部分和乘积的渐进结构,在一定条件下给出了一个中心极限定理。假设X1,X2…,Xa,…为二阶矩存在的非负独立随机变量列,证明收敛性[^nПk=1(Sk/μk)^1/γk]^1/√Tnd→e√2N成立,其中N是标准正态随机变量,Sk=^k∑i=1Xi,μk=E(Sk),σk=Var(Sk),γk=σk/μk,且Tn=^n∑k=1k/σk.  相似文献   

6.
利用不动点理论和微分不等式分析等方法,研究了具有变连接权的时滞细胞神经网络dxi(t)/dt=-cixi(t)+∑j=1^nαij(t)fi(xi(t))+∑j=1^nbij(t)fj(xj(t-τ(t)))+li(t)的概周期解的存在性和全局吸引性,推广和改进了相关文献的结果,扩大了神经网络的设计范围.  相似文献   

7.
讨论具有多滞量的一阶中立型微分方程dx/dt[x(t)-^k∑i=t Pi(t)x(t-τi)]+^i∑j=1Qj(t)x(t-σj)=0其中τi,σi∈(0,∞),Pi∈C([t0,∞],R),Qj∈C([t0,∞],R^+),i=1,2,…,k;j=1,2,…,l。给出了上速方程所有的解振动的充分条件,并且推广了单滞量情形的结果。  相似文献   

8.
在权阵列{ani:1≤i≤n,n≥1)满足Aα=lim sup n→∞(1/n∑i=1^n|ani|^α)^1/α〈∞的条件下,得到了高阶矩存在的同分布NA随机变量加权和的强大数律.  相似文献   

9.
本文利用Lyapunov泛函及不等式,研究了一类变时滞线性中立型泛函微分方程[x(t)-m∑i=1aix(t-τi)]'=bx(t)+n∑j=1+cjx(t-δj(t))的稳定性,并得到其零解渐进稳定性的充分条件.  相似文献   

10.
利用辅助信息,针对线性模型yi=βxi xi^yεi,εi i.i.d,Fεi=0,给出了总体分布函数的估计量:F(t)=1/N[∑j∈iΔ(t-yi) ∑j∈,1/n∑j∈Δ(t-β^*xi-xi^yuj)],uj=(yj-β^*xj)/xjy^*,j∈s,改进了Chambers-Dunstan的结果。  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.
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   

13.
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   

14.
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   

15.
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   

16.
AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…  相似文献   

17.
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   

18.
In the 19th century the society was controlled by men, and women were just appendants of them, they had not any rights and freedom. But Jane was an exception, she showed some characteristics of early feminist. Jane showed her characteristics of feminism in three aspects: rebellion, equality, and independence. These characteristics were helpful to her success, and feminism is the only way out for women of that time.  相似文献   

19.
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   

20.
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   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号