多元正态线性模型中的最优非负二次估计

考虑多元线性模型:nYp=X_1BX'_2+U=(ε_(1)…ε_(r))′ε_(r),…,ε_(r)N_p(O∑)。给出了tr(C∑)的一致最小方差非负二次无偏估计存在的一些充分条件,并在该估计存在的条件下,求出了它的具体表达式。     

二维系统的渐近解法

研究方程组(dx)/(dt)=y+εP(x,y,ε),(dy)/(dt)=-g(x)+εQ(x,y,ε), (1)其中ε为小参数。令V(x)=integral from 0 to x g(u)du。假设g(x),V(x),P(x,y,ε)和Q(x,y,ε)满足下列条件:(i)g(x)、P(x,y,ε)和Q(x,y,ε)有所需的各阶导数,g(0)=P(0,0,ε)=Q(0,0,ε)=0;(ii)存在四个数,β_2<β_1≤0≤α_1<α_2,使V(α_1)=V(β_1),V(α_2)=V(β_2);当x∈(α_1,α_2)     

高分子链构象与纳米颗粒尺寸的关系

用蒙特卡罗方法研究了吸附在纳米颗粒表面的高分子链,计算了高分子链的均方回转半径R_G~2,研究了R_G~2与高分子链-纳米颗粒相互作用强度ε_(pn)、纳米颗粒直径σn的关系,结果发现R_G~2严重地依赖于σ_n和ε_(pn),并且存在一个临界高分子链-纳米颗粒相互作用强度ε_(pn)*.当ε_(pn)ε_(pn)*时,R_G~2几乎不受纳米颗粒的影响;当ε_(pn)ε_(pn)*时,R_G~2随εpn的增加而减小并趋于稳定;当ε_(pn)足够大时,R_G~2随σ_n的增加先减后增.     

许定理的一个推广

§1 引言考虑线性模型y=Xβ+U_1ε_1+…+U_kε_k (1)其中 X,U_1,…,U_K 分别是已知的 n×p,n×n_1,…,n×n_k 矩阵,秩 X相似文献   

平面定常系统有无闭轨的判别法

本文首先给出平面定常系统(1.1)有无闭轨的一种判别法,特别当Q(x,y)=-g(x)时,给出了判定有元闭轨及奇点稳定性的若干准则,然后将这些方法用于研究二次系统与三次系统极限环的存在性与不存在性。本文分两节,§1给出判别平面定常系统有无闭轨的若干基本定理,§2把这些定理用于研究二次系统与三次系统的极限环的存在性问题。     

一类时滞互惠模型的稳定性及Hopf分支研究

本文研究一类带有时滞的互惠种群模型.首先利用比较定理证明了在ε_1ε_2≠0时解的有界性,通过构造Lyapunov函数,给出了正平衡解具有全局稳定性的充分条件.利用特征值理论且以时滞为参数,研究系统hopf分支的存在性,并给出了分支值存在的充分条件.最后用Matlab绘制出模型数值解的图像,验证所得结论的正确性.     

可数S(2)-θ-闭空间

引入了可数S(2 ) -θ_闭空间与强可数的S(2 ) -θ_闭空间 ,运用集合论方法给出了这两类空间的一些乘积性质     

粉末压制功与不完全Γ函数的关系

本文导出了粉体从应变为0(ε=0)到应变无穷大(ε=∞)时的压制总功: α_总=MW(1/d_o-1/d_m)Γ(m+1)式中,M是粉末压制模量,W是粉末的重量,d_o是粉末的原始密度,d_m是致密金属的理论密度,Γ(m+1)是m+1的Γ函数, Γ(m+1)=∫_0~ ∞e~(-ε)ε~mdεε是压制应变, ε=ln(d_m-d_o)d/(d_m-d)d_od是压坯密度,m是非线性指数。还导出了应变从ε_1到ε_2时实际的粉末压制功, α=∫_(ε_1)~(ε_2)e~(-ε)ε~mdε式中,∫_(ε_1)~(ε_2)e~(-ε)ε~mdε是m+1的不完全Γ函数,其函数值可由电子计算机近似求得。文中列表给出了钨粉压制功的计算实例。     

多元线性模型中一个协差阵函数的二次估计问题

考虑多元线性模型Y=X_1HX′_2+■,其中■=(ε_((1)),…,ε_((n)))′满足ε_((i)),i=1,…,n独立,ε_((i))～EC_p(0,Σ,φ)即ε_((i))服从椭球等高分布,Eε_((i))=0,Eε_((i))ε′_((i))=(ER~2/p)Σ,其中Σ≥0未知,φ已知且φ(?)Φ_p={φ(·)|φ(t_1~2+…+t_p~2)是一个特征函数},随机变量R≥0,R■φ.在α=ER~4/p(p+2)-(ER~2/p)~2≠0的条件下,对给定的矩阵C=C＇,得出了tr(CΣ)一致(关于Σ≥0)最小方差不变二次无偏估计(简称最优估计)存在的充要条件以及其具体形式.     

在热库中二次哈密顿系统的压缩态

研究了二次型哈密顿系统H=ω_0aa~++g(a~2+a~(+2))的压缩效应,并比较了在2个不同参数条件下(g>ω_0/2和g<ω_0/2)系统的行为.在g<ω_0/2时系统的物理基态是压缩态.还分析了在系统与热库相互作用时耗散和温度对压缩效应的影响.     

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.     

Lower Paleozoic oil relationships within Williston Basin, Canada

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.     

An Analysis of Catherine＇s Character——Wuthering Heights

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.     

Features of Women's language

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.     

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.     

Design and analysis of generic LBS application developing platform

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.     

橡胶颗粒沥青混合料低温抗裂性试验研究

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.     

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.     

Quantitative trait loci （QTLs） for quality traits related to protein and starch in wheat

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.