理想反应器的时空特性和内在联系

以理想反应器时间和空间特性为出发点,探讨了间歇操作釜式反应器(BR)、平推流反应器(PFR)和全混流反应器(CSTR)等理想反应器之间的内在联系,推导了循环操作PFR反应器的停留时间分布函数,分析了多段串联全混流反应器和循环操作PFR反应器在各理想反应器之间的桥梁和纽带作用。在此基础上,简要归纳了各理想反应器之间的联系。     

聚合物流动方程教学剖析及其流变本构关系自然哲理探讨

阐述了流体流动过程中三大守恒方程的原理及其各项表达式的物理含义,分析了三大守恒方程联立流体流变本构方程的必要性并进行了数字求解;对材料流变本构关系原理从自然哲理角度进行了探讨,深化教学内容,启发学生思维,达到更好的教学效果。     

Bi53+‐Polykationen in geordneten und plastischen Kristallen von Bi5[AlI4]3 und Bi5[AlBr4]3

Bi₅³⁺ Polycations in Ordered and Plastic Crystals of Bi₅[AlI₄]₃ and Bi₅[AlBr₄]₃ Dark‐red air‐sensitive crystals of pentabismuth‐tris(tetrabromoaluminate) Bi₅[AlBr₄]₃ and black crystals of Bi₅[AlI₄]₃ have been crystallized from melts of Bi, BiX₃ and AlX₃ (X = Br, I). X‐ray diffraction on a single crystal of Bi₅[AlI₄]₃ (T = 293(2) K; space group Pnma; a = 2143.6(3) pm, b = 1889.1(1) pm, c = 811.74(5) pm) revealed an ordered packing of Bi₅³⁺ trigonal bipyramids and [AlI₄]^? tetrahedra that corresponds to the PuBr₃ structure type. Contrary to the so far known Bi₅³⁺ polycations with accurate D_3h symmetry, the bismuth cluster found in Bi₅[AlI₄]₃ holds only C_s symmetry. The room temperature structure of the tetrabromoaluminate Bi₅[AlBr₄]₃, which is related to the AuCu₃ type, shows a dynamic disorder of the Bi₅³⁺ polycations (T = 293(2) K; space group ; a = 1766.2(3) pm). Slight cooling induces the transition into an ordered rhombohedral phase isostructural to Bi₅[AlCl₄]₃ (T = 260(2) K; space group a = 1241.5(8) pm, c = 3041(2) pm).     

Cl–改性对Ag/Al2O3催化剂结构及其催化C3H6-SCR和H2/C3H6-SCR反应性能的影响

以烯烃为还原剂的NOx选择性催化还原(HC-SCR)是重要的环境催化反应之一.Ag/Al2O3催化剂(SA)因在HC-SCR反应中表现高活性、高N2选择性及中等H2O和SO2耐受性等优点,而被广泛研究.SA催化剂中存在不同的Ag物种,包括孤立Ag+离子,带部分正电荷Agnδ+团簇和金属态Agn0团簇.文献研究结果表明,SA催化剂中Agnδ+团簇是催化HC-SCR反应的活性Ag物种,而Ag物种类型与Ag的负载量密切相关.因此文献中研究SA催化HC-SCR反应的结构-性能关系主要是通过改变Ag负载量来开展的,最优Ag负载量约为1％～2％.本文以Cl–改性的γ-Al2O3作为载体,采用传统的浸渍法制备了Ag/Al2O3-Cl催化剂(SA-Cl),通过XRD、TEM、H2-TPR、UV-Vis DRS以及XPS对催化剂进行了结构表征,并结合C3H6-SCR和H2/C3H6-SCR活性测试,建立催化剂结构-催化性能关系;同时利用原位傅里叶变换红外光谱(DRIFTS)和在线同步辐射单光子电离质谱(SVUV-PIMS)研究了SA催化HC-SCR的反应机理.结构表征结果表明,在SA催化剂中,Ag负载量的提高主要是增加了Agn0物种,而在SA-Cl催化剂中,Ag负载量的提高主要是增加了Agnδ+物种,因此Cl?改性能促进SA催化剂中Agnδ+物种的形成.活性测试结果表明,在相同Ag负载量下,SA-Cl催化剂表现出比SA催化剂更好的HC-SCR催化性能.Cl?改性对SA催化剂中Ag物种的调控作用和HC-SCR催化性能的促进作用随Ag负载量的增加变得更为明显.原位DRIFTS结果表明,γ-Al2O3载体(Al位点)是NO氧化形成硝酸盐物种的主要活性位点;Agnδ+物种催化丙烯适度氧化主要生成乙酸盐类物种,可以还原表面硝酸盐物种;而Agn0催化丙烯过度氧化主要生成羧酸盐类物种,进而生成CO2,不能还原表面硝酸盐物种.由此可见,Agnδ+是催化HC-SCR反应的活性Ag物种,而Agn0是催化烃类完全氧化反应的活性Ag物种;Cl–改性能有效促进Agnδ+的形成,进而提高HC-SCR催化反应活性.在线SVUV-PIMS结果检测到H2/C3H6-SCR反应中存在气态中间物种丙烯腈(CH2=CHCN).–CN和–NCO物种被认为是HC-SCR反应的关键中间物种,能够直接与气相NO+O2反应生成N2.因此,CH2=CHCN的存在说明HC-SCR反应涉及到气相反应机理.基于SA和SA-Cl催化剂,进一步研究了H2对C3H6-SCR低温活性的促进作用.结果表明,H2的促进作用是通过作用于Agnδ+物种,而不是通过Agn0物种来实现的;H2的引入有利于低温下强吸附硝酸盐物种的脱附或分解以及中间体向–NCO和–CN物种的转化,从而提高HC-SCR低温催化活性.综上,基于Cl–改性的Ag/Al2O3-Cl催化剂,本文成功证实了Agnδ+物种是催化HC-SCR反应的活性Ag物种,并结合原位DRIFTS在线SVUV-PIMS谱分别鉴定了催化反应表面中间物种和气相中间物种.这些结果加深了对SA催化HC-SCR反应构-效关系和反应机理的基础理解.     

Deep learning method for testing the cosmic distance duality relation

The cosmic distance duality relation (DDR) is constrained by a combination of type-Ia supernovae (SNe Ia) and strong gravitational lensing (SGL) systems using the deep learning method. To make use of the full SGL data, we reconstruct the luminosity distance from SNe Ia up to the highest redshift of SGL using deep learning, and then, this luminosity distance is compared with the angular diameter distance obtained from SGL. Considering the influence of the lens mass profile, we constrain the possible violation of the DDR in three lens mass models. The results show that, in the singular isothermal sphere and extended power-law models, the DDR is violated at a high confidence level, with the violation parameter \begin{document}$ \eta_0=-0.193^{+0.021}_{-0.019} $\end{document} and \begin{document}$ \eta_0=-0.247^{+0.014}_{-0.013} $\end{document}, respectively. In the power-law model, however, the DDR is verified within a 1σ confidence level, with the violation parameter \begin{document}$ \eta_0=-0.014^{+0.053}_{-0.045} $\end{document}. Our results demonstrate that the constraints on the DDR strongly depend on the lens mass models. Given a specific lens mass model, the DDR can be constrained at a precision of \begin{document}$O(10^{-2}) $\end{document} using deep learning.     

New concepts for completely regular semigroups

Let 𝒞? denotes the variety of completely regular semigroups considered with the unary operation of inversion. The global study of the lattice of subvarieties of 𝒞? depends heavily on various decompositions. Some of the most fruitful among these are induced by the kernel and the trace relations. In their turn, these relations are induced by the kernel and the trace relations on the lattice of congruences on regular semigroups. These latter admit the concepts of kernel and trace of a congruence. The kernel and the trace relations for congruences were transferred to kernel and trace relations on varieties but the kernel and trace got no analogue for varieties.

We supply here the kernel and the trace of a variety which induce the relations of their namesake. For the local and core relations, we also define the local and core of a variety. All the new concepts are certain subclasses of 𝒞?. In this way, we achieve considerable similarity of the new concepts with those for congruences. We also correct errors in two published papers.     

Constructing G-algebras

In this article we define G-algebras, that is, graded algebras on which a reductive group G, acts as gradation preserving automorphisms. Starting from a finite dimensional G-module V and the polynomial ring ?[V], it is shown how one constructs a sequence of projective varieties V_k such that each point of V_k corresponds to a graded algebra with the same decomposition up to degree k as a G-module. After some general theory, we apply this to the case that V is the n+1-dimensional permutation representation of S_n+1, the permutation group on n+1 letters.     

On additively completely regular seminearrings

In an attempt to investigate the situation arising out of replacing additive regularity by additive complete regularity in our previous study on additively regular seminearrings, we introduce the notions of left (right) completely regular seminearrings and characterize left (right) completely regular seminearrings as bi-semilattices of left (resp., right) completely simple seminearrings. We also define left (right) Clifford seminearrings and show that they are precisely bi-semilattices of near-rings (resp., zero-symmetric near-rings).     

A new formula for the decycling number of regular graphs

The decycling number $?\left(G\right)$ of a graph $G$ is the smallest number of vertices which can be removed from $G$ so that the resultant graph contains no cycle. A decycling set containing exactly $?\left(G\right)$ vertices of $G$ is called a $?$-set. For any decycling set $S$ of a $k$-regular graph $G$, we show that $\left|S\right|=\frac{\beta \left(G\right)+m\left(S\right)}{k?1}$, where $\beta \left(G\right)$ is the cycle rank of $G$, $m\left(S\right)=c+\left|E\left(S\right)\right|?1$ is the margin number of $S$, $c$ and $\left|E\left(S\right)\right|$ are, respectively, the number of components of $G?S$ and the number of edges in $G\left[S\right]$. In particular, for any $?$-set $S$ of a 3-regular graph $G$, we prove that $m\left(S\right)=\xi \left(G\right)$, where $\xi \left(G\right)$ is the Betti deficiency of $G$. This implies that the decycling number of a 3-regular graph $G$ is $\frac{\beta \left(G\right)+\xi \left(G\right)}{2}$. Hence $?\left(G\right)=?\frac{\beta \left(G\right)}{2}?$ for a 3-regular upper-embeddable graph $G$, which concludes the results in [Gao et al., 2015, Wei and Li, 2013] and solves two open problems posed by Bau and Beineke (2002). Considering an algorithm by Furst et al., (1988), there exists a polynomial time algorithm to compute $Z\left(G\right)$, the cardinality of a maximum nonseparating independent set in a $3$-regular graph $G$, which solves an open problem raised by Speckenmeyer (1988). As for a 4-regular graph $G$, we show that for any $?$-set $S$ of $G$, there exists a spanning tree $T$ of $G$ such that the elements of $S$ are simply the leaves of $T$ with at most two exceptions providing $?\left(G\right)=?\frac{\beta \left(G\right)}{3}?$. On the other hand, if $G$ is a loopless graph on $n$ vertices with maximum degree at most $4$, then

The above two upper bounds are tight, and this makes an extension of a result due to Punnim (2006).