代数格上形态算子的表示方法

以二值形态运算中平移变换的作用为引导,赋予代数格上的自同构群可交换的特性,使得形态算子的表示更为明确.在此基础上研究了代数格上形态算子的表示定理,并将这种思想运用于Matheron二值形态算子表示定理与极小内核表示定理的证明中.     

关于格论中的密化定理

格论中的密化定理是群论中的Schreier定理在格中的推广。一群G的所有正常子群成一模格,故正常列的密化定理确实为格的密化定理的推论,但所有次不变群不一定成功模格,因此格的密化定理不能统一群的次不变列的密化定理.原因是模性要求过强,并非密化定理所必需。这篇短文提出一种减弱模性的方式,使格中密化定理仍然成立并使群的Schreier定理为其推论,再者群的Jordan—Hōeder定理在格中的推广不需要模性只要“半     

完全分配格是完备集环的刻划定理

利用RaneyGN的完全分配格的次直积表示定理证明了 :完全分配格L是完备集环 L是相对原子格 ;完全分配格L是完备集环 conc(L)同构到一个幂集格 ,这里conc(L)是L的完备同余关系格 .     

可解半单纯群的一个结构定理

本文利用群G(可以是有限群,也可以是无限群)的所有正规子群组成的乘格L(G)的有关性质,得到关于可解半单纯群的一个结构定理。     

格序群扭类与半单类之间的Galois联络

建立了格序群扭类与半单类之间的一种重要联系Galois联络 ,利用这种联系研究了极扭类的存在性并且给出了极扭类的一种表示 ,推广了格序群扭类的基本定理 .     

L不分明单位区间与不分明连通性

在本文中(L,≤,∨,∧,,)表示一个Fuzzy格,即具有逆序对合对应的完全分配格,这个格的最大元与最小元分别用1与0表示,I表示通常的单位区间[0,1],以及I(L)表示L不分明单位区间,在其上总取标准拓扑,记作τ,命L~b={α∈L|若α<β与α<γ,则α<(β∧γ)}S.E.Rodabaugh在[3]中讨论了不分明拓扑学中的连通性,证明了当ο∈L~b时(I(L),τ)是连通的,本文将在这基础上继续这方面的工作,讨论不分明拓扑中     

格的L—fuzzy集表示

[2]提出了一般格的表示论,[3]提出了De—Morgan代数的广义Fuzzy集的表示,本文对一般格的L—fuzzy集表示作了初步探讨,并把[3]中的某些结果推广到一般格上。本文始终假设F_L(x)是论域X上L—fuzzy集全体所作成的格,其中L是一个完全分配格。定义1 一个格R到F_L(X)的子格上的同态φ,称为格R按X的L—集同态表示,特别地,在同构时,称为L—集同构表示(本文以下把L—集同态表示简称为L—表示)。     

否定非对合剩余格的双极值模糊理想格

对否定非对合剩余格的双极值模糊理想问题做进一步深入研究,给出了由一个双极值模糊集生成的双极值模糊理想的定义并建立了其两个表示定理,证明了一个否定非对合剩余格L的全体双极值模糊理想之集BFI(L)在偏序下构成完备Heyting代数,为进一步揭示否定非对合剩余格的结构特征拓展了研究思路。     

格的同态与合同

本文对于格的合同之间的“≥”关系规定为[1]中的对偶。设有两个格L，L’，L'为L的同态像，且以H与H'分别表示L与L’的合同的全体按“≥”关系构成的备格，我们证明了存在θ∈H，使[θ](即备格H的元θ的上闭包)与H'同构。本文中的定理给出了此结果的一个应用。     

格序环的L同态

基本同态定理是代数系中的重要定理之一,文[1](Th1.2)将群的基本同态定理推广到格序群(L-群)中,本文将它推广到格序环(L-环)与格序模(L-模)中.     

Smash积的R－不交理想

本文定义了有限群Ｇ分次环Ｒ与群Ｇ的Ｓｍａｓｈ积Ｒ－不交理想和闭理想，讨论了闭理想的性质及Ｒ＃Ｇ的极大Ｒ－不交理想Ｐ的素性、本原性与Ｒ的ｇｒ－素性，ｇｒ－本原性之间的关系．     

Smash积的R－不交理想

本文定义了有限群Ｇ分次环Ｒ与群Ｇ的Ｓｍａｓｈ积Ｒ－不交理想和闭理想，讨论了闭理想的性质及Ｒ＃Ｇ的极大Ｒ－不交理想Ｐ的素性、本原性与Ｒ的ｇｒ－素性，ｇｒ－本原性之间的关系．     

左乘算子的约化最小模

Banach空间盛上的全体有界线性算子表示为B（X）对算子A∈B（X防）,左乘算子LA定义为LA（X）=AX,X∈B（X）。本文讨论了左乘算子LA厶的约化最小模与算子A的约化最小模的关系,得到γ（LA）≤γ（A）。特别地,对Hilbert空间上的算子A,证明了γ（LA）=γ（A）成立。     

型不变量为(e,3,1)的有限正则非交换p群的分类

该文利用正则p群的型不变量、唯一性基底及L群列等基本概念，给出了型不变量为(e,3,1)的有限正则非交换p群的分类，其中p≠2.     

Effect of trace boron on microstructural evolution and high temperature creep performance in Re-contianing single crystal superalloys

The effect of trace B on the microstructure and creep properties under 1100 °C/130 MPa in three single crystal superalloys with various levels of B(0, 0.01 and 0.02 wt %) additions was investigated. Compared with the boron-free alloy, the creep rupture life decreased slightly for the alloy with 0.01 wt % B, but dropped obviously for the 0.02 wt% B contained alloy. The low B addition had a slight effect on the main element compositions ofγ/γ′ by the high precision atom probe tomography(APT) analysis and no significant change of γ/γ′ misfit was observed. However, the contents of Re, Mo, Cr in γ phase were decreased with the high B addition, resulting in the decrease of γ/γ′ misfit and increase of the spacing of γ/γ′ interfacial dislocation networks. Meanwhile, the residual(γ+γ′) eutectics and borides with a large volume fraction obviously decreased the creep rupture properties in the high B addition alloy. This study is helpful for understanding the boron's role of strengthening mechanism in high temperature creep of Ni-base single crystal superalloys.     

Cloning and analysis of a γ-tocopherol methyltransferase gene from Brassica oleracea and the function of its recombinant protein

The full-length cDNA (BoTMT) of γ-TMT is obtained from Brassica oleracea by 3′- and 5′-RACE methods. The 1265 bp cDNA contains an open reading frame of 1044 bp, which encodes a protein of 347 amino acids with a predicted chloroplast transit peptide and two S-adenosylmethionine (SAM)-binding domains. Sequence analysis shows that the deduced protein shares 41.8%～86.5% similarity to known γ-TMTs. Semi-quantitative RT-PCR reveals that BoTMT is expressed preferentially in flowers and leaves of B. oleracea. The recombinant γ-TMT protein is obtained by cloning its encoding region into the prokaryotic expression vector pET30a. The protein expressed in E. coli accounts for 22% of total bacterial protein. The enzyme activity assay indicates that the recombinant protein has relatively high activity to convert γ-tocopherol to α-tocopherol in vitro.     

Effects of minor B additions on tensile strength,fracture toughness and oxidation resistance of Nb–Si based alloys

The effects of minor additions of B on microstructure, ambient tensile strength, fracture toughness and high-temperature oxidation resistance of Nb–Si based alloys were investigated. The added contents were designed as 0.05, 0.10 and 0.20 ?at.%. The results show constituent phases in 0.05B and 0.20B alloys were Nbss, α-Nb₅Si₃; while only 0.10B alloy consisted of γ-Nb₅Si₃. Minor B was prioritized into Nbss and redundant one dissolved into silicide enhanced volume fraction of the silicide. With increasing concentrations of boron, the microstructure was refined at first and then coarsened, while the tensile strength was enhanced remarkably. Compared with other two alloys, the 0.10B alloy containing γ-Nb₅Si₃ shows both the best fracture toughness and oxidation resistance. The important roles of γ-Nb₅Si₃ in balancing overall properties are emphasized.     

Effect of cold rolling and first precipitates on the coarsening behavior of γ″-phases in Inconel 718 alloy

The coarsening behaviors of γ″-phase particles in Inconel 718 alloy aged at 750, 800, and 850°C were investigated by scanning electron microscopy (SEM). Detailed observations and quantitative measurements were conducted to characterize the coarsening behavior of the γ″-phase under various aging conditions. The experimental results indicate that the existence of the δ-phase retards the formation and coarsening of the γ″-phase, without influencing its final particle size or amount. Moreover, when cold rolled with a reduction of 50%, the dimensions of the γ″ particles in Inconel 718 alloy decrease with increasing aging time. Furthermore, the coarsening behavior of the γ″-phase in the Inconel 718 alloy after a normal aging treatment (sample A) and that of the primary δ-phase (sample B) follow the Lifshitz–Slyozov–Wagner (LSW) diffusion-controlled growth theory; the thus-obtained activation energies for the γ″-phase are 292 kJ·mol-1 and 302 kJ·mol-1, respectively.     

合金元素对新型镍基粉末高温合金的热力学平衡相析出行为的影响

通过热力学平衡相计算方法,系统研究了某新型镍基粉末高温合金时效温度下合金元素对热力学平衡相析出行为的影响.计算结果表明:René104合金析出的主要平衡相为γ′、MC、M23C6、M3B2和TCP相.Cr和Co含量主要影响TCP相的析出行为及γ′相的析出温度,Cr含量对M23C6和M3B2的析出行为有一定的影响,Cr的建议质量分数为13%;Mo和W含量影响TCP相和M3B2的析出行为.质量比Al/Ti和Nb/Ta影响γ′相的析出行为,建议控制Al/Ti和Nb/Ta比平衡,以使γ′相起到理想的强化效果.C和B含量显著影响碳化物和硼化物的析出量,还可间接抑制TCP相析出;Zr含量对MC和M23C6碳化物的析出有影响;增Co降Cr和调节合金元素含量以获得小的点阵错配度是第3代涡轮盘用粉末冶金高温合金成分优化设计的趋势.     

Dynamic recrystallization and phase transformation behavior of a wrought β-γ TiAl alloy during hot compression

The dynamic recrystallization (DRX) and phase transformation (PT) behavior of a wrought β-γ TiAl alloy during hot compression under various deformation temperatures were investigated. The typical work hardening and flow softening features indicated that DRX was the dominating softening mechanism. Both γ-DRX and β-DRX took place during the hot compression. γ-DRX was triggered at all compression temperatures, while the β-DRX was induced when the compression temperature was above 1000 °C. The hot deformation kinetics was calculated, which showed that DRX behavior existed in the whole hot compression process, and the DRX volume fraction increased with the increase of the compression temperature. Combined with the microstructure observation, it concluded that the β/B2+α₂→γ PT occurred at 850 °C and 1000 °C, while the γ→β/B2 PT happened at 1050 °C during hot compression, which is important to optimize microstructure. Moreover, the hot compression mechanism changed from dislocation gliding to grain-boundary sliding was discussed.