方差估计以及两个方差分量同时估计的可容许性

考虑线性模型 EY_(n×i)=X_(n×)β_(n×i) DY=σ~2V,V≥0,σ~2>0未知 (*)以及方差分量模型 EY_(n×i)=X_(n)β_(n×i) DY=σ_1:V_i+σ_2V_2,V_i≥0,V_2≥0,σ_i,σ_2>O未知 (**)其中γ(X_(n×m)=n,对模型(*)令D={d(A)=Y＇AY,A≥0}损失函数为L~(1)(d(A),σ~2)=σ~(-4)(Y＇AY-σ~2)~2,对模型(**)令D~(2)={d(A_i,A_2)=(Y＇A_iY,Y＇A_2Y),A_i≥0,A_2≥0},损失函数为L~(2)(d(A_i,A_2),(σ_i,σ_2))=σ_i(Y＇A_iY-σ_i)~2+σ_2(Y＇A_2Y-σ_2)~2,本文对模型(*)给出了d(A)为σ~2的D~(1)容许估计的充分条件,对模型(**)给出了在V_i+V_2>0的限制下,d(A_i,A_2)为(σ_i~2,σ_2~2)的D~(2)容许估计的充分条件。分别推广了文[3],[5]中的有关结果。     

一类半线性微分方程组第三边值问题的差分方法

本文旨在证明形如 u_t(x,t)=Auxx(x,t) f(u)微分方程组的第三边值问题近似解的存在唯一性问题。其中: (z,t)∈(0,L)×(0,T)=G_T u(x,t)=(u_1(x,t),u_2(x,t),…,u_m(x,t)) f(u)=(f_1(u),f_2(u),…,f_m(u))其边值条件为“u_x(0,t)=σ_1u(0,t),u_x(L,t)=-σ_2u(L,t) u(x,0)=φ(x),σ_1>0,σ_2>0,φ(x)满足边界条件: φ′(0)=σ_1φ(0),φ′(L)=-σ_2φ(L) [1]的作者解决了上述方程组的第一、二边值问题,本文用与[1]类似的方法解决了第三边值问题。实际上,对A,σ_1,σ_2和f含t变量的同类边值问题也有类似的结论。本文为简明计,仅对条件与[1]相同的情况进行论证。     

高纯铝在范性形变过程中内耗对频率和速率的响应行为

考虑了位错平均速度V=f(σ)随时间或应变的变化之后,导出了金属在范性形变过程中内耗Q～~(-1)与位错动力学关系式V=f(σ),形变速率ε、测量频率ω、测量振幅σ_A 以及切变模量G 等的关系为(?)此处(?)t、(?)p 分别为扭切应力和拉伸应力的平均取向因子,Г(n)为取正值的积分常数,m 为除0,-1以外的整数。可见,形变过程内耗可能出现正比于(ε/ω)~(2/3)、((?)/ω)~(1/2)、((?)/ω)以及((?)/ω)~2等各种对于ω和(?)的响应行为。而且出现随测量振幅σ_A增大而减小的反常振幅效应内耗。高纯铝在拉伸速率(?)=50×10~(-6)/秒时,形变过程内耗Q~(-1)的实验数据与上式中n=-2时的结果符合得很好.此时的内耗可表示为Q~(-1)=0.245(G/σ_A)β_(-2)((?)/ω)~(1/2)/(V_0~′+β_(-2)ε~(-(1/2)).亦即Q~(-1)正比于((?)/ω)~(1/2).还观测到随着σ_A 的增加而减小的反常振幅效应内耗.高纯铝在恒速拉伸时,当ε>0.5%后,位错的平均速度(?)_0。与形变量ε间的关系可表示为(?)_0=V_0~′+βε~(-(1/2));而运动位错的密度ρ可表示为ρ=(?)/ab(V_0~~′+βε~(-(1/2)).     

螺旋桨空化初生的判定和空化斗的数值分析

摘要：
为了实现空化多相流模拟在螺旋桨空化初生和空化斗预报中的应用,采用改进Sauer空化模型和修正剪切应力输运(SST)湍流模型,对NSRDC4381桨的叶背和叶面片空化初生、梢涡空化初生和空化斗底线特征进行了模拟、校验和分析,提出了“当σ>σi时,叶梢截面压力系数分布不再改变”的空化初生判定准则,并分析了其适用范围. 同时,将空化斗由传统的三区细分为五区,以更准确地描述不同工况点的桨叶空化状态. 结果表明,在设计和非设计进速系数下,预报桨叶叶背和叶面不同叶截面的初生空化数均与实验值吻合较好;模拟梢涡空化初生再现了局部梢涡空化和导边梢涡空化同时存在的现象,证明了分别用叶背07 R截面和叶面04 R截面的片空化初生曲线来表征叶背和叶面可视梢涡空化初生的合理性. 空化初生判定准则适用于空化斗底线上方的叶背和叶面片空化区. 将空化斗底线下方区域进一步细分为叶背03 R至叶梢的片空化区以及叶背与叶面同时片空化区,以更好地在工程中应用空化斗来描述桨叶空化形态和求取空化航态的航速.     

初生空化数的计算模型

从“气核惯性失稳导致空化”这一观点出发,提出了应用于数值模拟的初生空化判别标准及其数学模型,采用Ｍｏｎｔｅ－Ｃａｒｌｏ方法模拟空化现象中的各种随机因素,在可靠度的意义下将气核空化初生与流场空化初生联系起来．以黄河小浪底工程消能泄洪洞为例,对三级串联孔板的初生空化数作了计算．     

一个二阶拟线性椭园型方程定解问题的奇摄动

我们考虑如下含有小参数的二阶拟线性椭园型方程的定解问题:L_ε〔w〕≡ε(■~2w)/(■y~2)+(■~2w)/(■x~2)-a(y)(■w)/(■y)+b(x,y,w)=0(1)〔(■w)/(■x)+λ_i(y)w〕x=σ_i(y)=(?)_i(y),(i=1,2)(2)w丨_(y=0)=(?)_1(x)(3)((?)w)/((?)y)_(y=1)=(?)_2(x)(4)其中0<ε《1,σ_1(y)<α<β<σ_2(y),σ_1(y),σ_2(y)在〔01〕上适当光滑,使得区域Ω={(x,y)丨σ_1≤x≤σ_2,0≤y≤1}在边界σ_1(y),σ_2(y)上每点满足内部球条件〔5〕。(-1)~iλ(y)>0,(?)_i(y)及(?)_i(x)均为它们所定义的那段边界上的连续可微函数,α(y)>0,b(x,     

混合模型及其导出模型下可估函数的最佳线性无偏估计研究

讨论了在混合模型(y,Xβ+Uζ,σ_0~2V_0)及其导出模型下,可估函数的最佳线性无偏估计之间的关系,证明了当可估函数的最佳线性无偏估计存在时,它在混合模型及其导出模型下的一致性。     

二个正态总体方差未知且不等时均值差的假设检验与置信区间

设ξ～N(a_1,σ_1~2),η～N(a_2,σ_2~2),(ξ_1,ξ_2…,ξ_m)为ξ的样本,(η_1,η_2,…,η_n)为η的样本;ξ,η相互独立。当σ_1~2,σ_2~2未知,但σ_1~2=σ_2~2已知(或经检验成立σ_1~2=σ_2~2,均值差a_1-a_2的假设检验与置信区间问题已解决。但当σ_1~2,σ_2~2未知,σ_1~2>σ_2~2(σ_1~2<σ_2~2)已知时,均值差a_1-a_2的假设检验与置信区间问题笔者未见有文讨论。为此,本文将给出一种均值差a_1-a_2=0的检验方法和a_1-a_2的置信区间。(一)σ_1~2,σ_2~2未知,但σ_1~2>σ_2~2已知时,均值差a_1-a_2的假设检验与置信区间。     

一类拟线性退化椭园方程的有限元方法

本文考虑如下形式的拟线性退化椭园方程:(1.1)于Ω内于Γ_1于Γ_0其中σ>0是实数,Ω是 y≥0,xy 平面的有界凸区域,Γ_0是Ω与x—轴相交的一线段,Γ_1=Ω-Γ_0,Γ_0,Γ_1分别称为退化和非退化区域边界,给出两种有限元公式解的 L_σ~2模和 H_σ~1模的误整估计.     

用0.15F_b—0.45F_b标准线法求σ_(0.2)

1 前言 名义屈服应力σ_(0.2)是材料测试中用得最为广泛的一个参数。以前,人们总是用平行线法来确定它。随着高精度材料试验机的出现,材料的载荷一变形曲线几乎都没有明显的初始直线段,平行线法已经不再适用,于是便出现了采用国际标准滞后环法来求σ_(0.2);之后又出现了求σ_(0.2)的近似值方法,如“逐步逼近法”。但由于逐     

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.