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Statistical Study of Relationship between Structural Properties and Mesomorphic Properties of Some Ester Linkage Mesomorphic Compounds 某些酯链亚构化合物结构性质与亚构性质关系的统计研究
IF 0.9 4区 数学 Q2 Mathematics Pub Date : 2021-01-18 DOI: 10.2174/1877946811666210118121319
J. Travadi
A statistical study between ‘Mesophase Lower Transition Temperatures’ (MLTTs) and their structural propertiesis carried out to understand the effect of structural behaviour on mesomorphic property.To establish a “Quantitative Structure and Property Relationship (QSPR) model” a set of randomly selectedthirty-nine mesomorphic compounds is constructed. The backward stepwise regression analysis method is used to find outthe good correlation between the “Mesophase Lower Transition Temperatures (MLTTs)” data set and “physical descriptors”like AMR, bpol, ASP-0, DELS, SdssC, etc. Physical descriptors are selected based on their good r2-values and p-valueswith respective MLTTs. The derived QSPR equation shows a good correlation between structural properties and mesomorphic properties of compounds. Validation of the derived QSPR equation is carried out on the test series of eight compounds. The MLTTs of thesecompounds are predicted through the statistically derived QSPR equation and then compared with experimentally measuredMLTTs. The average percentage error observed between predicted MLTTs and experimentally measured MLTTs is observed 10.95 % for all the thirty-nine compounds of the trial set, and 10.64% for 8 compounds of the test series respectively. A low average percentage error suggests a reasonably acceptable degree of accuracy of the generatedQSPR model to predict MLTTs of the compounds having a similar type of structure.In the present study not only MLTTsare predicted, but an effort also made to predict “Latent Transition Temperatures” (LTTs) of some non-mesomorphic compounds from derived QSPR equation.This computational study gives a sight to develop new QSPR models for the different-different type of liquidcrystals homologous series, through which various types of mesomorphic properties, like mesomorphic thermal stability,mesomorphic upper transition temperature, mesophase length, phase behaviour, etc. can study and predict.
为了了解结构行为对介态性能的影响,对“中相低转变温度”(MLTTs)及其结构性能进行了统计研究。为了建立一个“定量结构与性质关系(QSPR)模型”,我们随机选择了39个介形化合物。采用后向逐步回归分析方法,发现“中间相较低转变温度(MLTTs)”数据集与AMR、bpol、ASP-0、DELS、SdssC等“物理描述符”具有良好的相关性。物理描述符是根据其良好的r2值和p值与各自的mltt来选择的。推导出的QSPR方程显示了化合物的结构性质与介形性质之间良好的相关性。在8个化合物的测试系列上验证了所建立的QSPR方程。通过统计导出的QSPR方程预测了这些化合物的mltt,并与实验测量的mltt进行了比较。在试验集的所有39种化合物中,预测的mltt与实验测量的mltt之间的平均百分比误差分别为10.95%和10.64%。较低的平均百分比误差表明,所生成的qspr模型在预测具有相似结构类型的化合物的mltt时具有合理可接受的精度。在本研究中,我们不仅预测了mlttr,而且还从推导的QSPR方程中预测了一些非介形化合物的“潜在转变温度”(LTTs)。本计算研究为建立不同类型-不同类型液晶同源系列的新的QSPR模型提供了前景,通过该模型可以研究和预测各种类型的亚晶性质,如亚晶热稳定性、亚晶上转变温度、中间相长度、相行为等。
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引用次数: 0
Unusually large components in near-critical Erdős-Rényi graphs via ballot theorems 通过选票定理,在接近临界的Erdős-Rényi图中出现异常大的组件
IF 0.9 4区 数学 Q2 Mathematics Pub Date : 2021-01-13 DOI: 10.1017/s0963548321000584
Umberto De Ambroggio, Matthew I. Roberts
We consider the near-critical Erdős–Rényi random graph G(n, p) and provide a new probabilistic proof of the fact that, when p is of the form $p=p(n)=1/n+lambda/n^{4/3}$ and A is large, begin{equation*}mathbb{P}(|mathcal{C}_{max}|>An^{2/3})asymp A^{-3/2}e^{-frac{A^3}{8}+frac{lambda A^2}{2}-frac{lambda^2A}{2}},end{equation*} where $mathcal{C}_{max}$ is the largest connected component of the graph. Our result allows A and $lambda$ to depend on n. While this result is already known, our proof relies only on conceptual and adaptable tools such as ballot theorems, whereas the existing proof relies on a combinatorial formula specific to Erdős–Rényi graphs, together with analytic estimates.
我们考虑近临界Erdős-Rényi随机图G(n, p),并提供了一个新的概率证明,证明当p的形式为$p=p(n)=1/n+lambda/n^{4/3}$且a很大时,begin{equation*}mathbb{P}(|mathcal{C}_{max}|>An^{2/3})asymp A^{-3/2}e^{-frac{A^3}{8}+frac{lambda A^2}{2}-frac{lambda^2A}{2}},end{equation*}其中$mathcal{C}_{max}$是图的最大连接分量。我们的结果允许A和$lambda$依赖于n。虽然这个结果是已知的,但我们的证明只依赖于概念性和适应性的工具,如选票定理,而现有的证明依赖于Erdős-Rényi图特定的组合公式,以及分析估计。
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引用次数: 7
Triangle-degrees in graphs and tetrahedron coverings in 3-graphs 图中的三角形度和3图中的四面体覆盖
IF 0.9 4区 数学 Q2 Mathematics Pub Date : 2021-01-01 DOI: 10.1017/S0963548320000413
Asaf Ferber, K. Luh, Gweneth McKinley
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引用次数: 2
Получение металлического горючего AlB2 методом самораспространяющегося высокотемпературного синтеза и высокоэнергетические составы на его основе 金属燃料AlB2通过热聚变和高能化合物自我传播的方法获得
IF 0.9 4区 数学 Q2 Mathematics Pub Date : 2020-12-28 DOI: 10.18321/CPC402
С. Х. Акназаров, А. Б. Сейсенова, У.Д. Диканбай, А.Ж. Мутушев, Хуан Мария Гонсалес-Лил
В работе исследована возможность получения диборида алюминия методом самораспространяющегося высокотемпературного синтеза (СВС), рассчитаны термодинамические параметры синтеза, выбран компонентный состав шихты. Экспериментально подобран количественный состав шихты для получения в процессе синтеза диборида алюминия, отвечающего предъявляемыми к нему требованиями, с максимальным выходом.
本文研究了自膨胀高温合成法生产铝二硼的可能性,计算了合成的热力学参数,选择了配料的组分成分。通过实验选择配料的数量,以获得符合要求的二硼铝的合成工艺,并获得最大产量。
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引用次数: 0
Clustered colouring of graph classes with bounded treedepth or pathwidth 具有有界树深或路径宽度的图类的聚类着色
IF 0.9 4区 数学 Q2 Mathematics Pub Date : 2020-12-10 DOI: 10.1017/S0963548322000165
S. Norin, A. Scott, D. Wood
The "clustered chromatic number" of a class of graphs is the minimum integer $k$ such that for some integer $c$ every graph in the class is $k$-colourable with monochromatic components of size at most $c$. We determine the clustered chromatic number of any minor-closed class with bounded treedepth, and prove a best possible upper bound on the clustered chromatic number of any minor-closed class with bounded pathwidth. As a consequence, we determine the fractional clustered chromatic number of every minor-closed class.
一类图的“聚类色数”是最小整数$k$,使得对于某些整数$c$,该类中的每个图都是$k$-可着色的,其单色分量的大小最多为$c$。我们确定了树深有界的任意小闭类的聚类色数,并证明了路径宽度有界的任意小闭类的聚类色数的最佳可能上界。因此,我们确定了每个小闭类的分数簇色数。
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引用次数: 4
Extremal problems for GCDs gcd的极端问题
IF 0.9 4区 数学 Q2 Mathematics Pub Date : 2020-12-03 DOI: 10.1017/S0963548321000092
B. Green, A. Walker
We prove that if $A subseteq [X,,2X]$ and $B subseteq [Y,,2Y]$ are sets of integers such that gcd (a, b) ⩾ D for at least δ|A||B| pairs (a, b) ε A × B then $|A||B|{ ll _{rm{varepsilon }}}{delta ^{ - 2 - varepsilon }}XY/{D^2}$ . This is a new result even when δ = 1. The proof uses ideas of Koukoulopoulos and Maynard and some additional combinatorial arguments.
我们证明,如果$A subseteq [X,,2X]$和$B subseteq [Y,,2Y]$是整数集,使得gcd (a, b)小于或等于D至少δ| a || b |对(a, b) ε a × b,那么$|A||B|{ ll _{rm{varepsilon }}}{delta ^{ - 2 - varepsilon }}XY/{D^2}$。即使δ = 1,这也是一个新结果。这个证明使用了Koukoulopoulos和Maynard的思想以及一些额外的组合论证。
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引用次数: 2
On tripartite common graphs 在三边公图上
IF 0.9 4区 数学 Q2 Mathematics Pub Date : 2020-12-03 DOI: 10.1017/s0963548322000074
Andrzej Grzesik, Joonkyung Lee, Bernard Lidick'y, Jan Volec
A graph $H$ is common if the number of monochromatic copies of $H$ in a 2-edge-colouring of the complete graph $K_n$ is asymptotically minimised by the random colouring. Burr and Rosta, extending a famous conjecture of Erdős, conjectured that every graph is common. The conjectures of Erdős and of Burr and Rosta were disproved by Thomason and by Sidorenko, respectively, in the late 1980s. Collecting new examples of common graphs had not seen much progress since then, although very recently a few more graphs were verified to be common by the flag algebra method or the recent progress on Sidorenko’s conjecture. Our contribution here is to provide several new classes of tripartite common graphs. The first example is the class of so-called triangle trees, which generalises two theorems by Sidorenko and answers a question of Jagger, Šťovíček, and Thomason from 1996. We also prove that, somewhat surprisingly, given any tree $T$ , there exists a triangle tree such that the graph obtained by adding $T$ as a pendant tree is still common. Furthermore, we show that adding arbitrarily many apex vertices to any connected bipartite graph on at most $5$ vertices yields a common graph.
如果完全图$K_n$的2边着色中$H$的单色副本的数目被随机着色渐近地最小化,则图$H$是常见的。Burr和Rosta,扩展了Erdős的一个著名猜想,推测每个图都是共同的。Erdős以及Burr和Rosta的猜想分别在20世纪80年代末被Thomason和Sidorenko推翻。从那以后,收集普通图的新例子并没有取得太大进展,尽管最近又有一些图被标志代数方法或西多连科猜想的最新进展证实为普通图。我们在这里的贡献是提供了几类新的三边公共图。第一个例子是所谓的三角树,它推广了Sidorenko的两个定理,并回答了Jagger, Šťovíček和Thomason在1996年提出的一个问题。令人惊讶的是,我们还证明了,给定任意树$T$,存在一棵三角形树,使得将$T$作为垂坠树添加得到的图仍然是常见的。进一步,我们证明了在任何连通的二部图上添加任意多个顶点,在最多$5$顶点上可以得到一个公共图。
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引用次数: 15
Lower bound on the size of a quasirandom forcing set of permutations 准随机强迫排列集大小的下界
IF 0.9 4区 数学 Q2 Mathematics Pub Date : 2020-11-18 DOI: 10.1017/S0963548321000298
Martin Kurečka
A set S of permutations is forcing if for any sequence ${Pi_i}_{i in mathbb{N}}$ of permutations where the density $d(pi,Pi_i)$ converges to $frac{1}{|pi|!}$ for every permutation $pi in S$ , it holds that ${Pi_i}_{i in mathbb{N}}$ is quasirandom. Graham asked whether there exists an integer k such that the set of all permutations of order k is forcing; this has been shown to be true for any $kge 4$ . In particular, the set of all 24 permutations of order 4 is forcing. We provide the first non-trivial lower bound on the size of a forcing set of permutations: every forcing set of permutations (with arbitrary orders) contains at least four permutations.
一组S的排列是强制的,如果对于任意排列序列${Pi_i}_{i in mathbb{N}}$,其中密度$d(pi,Pi_i)$收敛于$frac{1}{|pi|!}$对于每个排列$pi in S$,则认为${Pi_i}_{i in mathbb{N}}$是准随机的。Graham问是否存在一个整数k使得所有k阶排列的集合是强制的;这已被证明对任何$kge 4$都是正确的。特别地,所有24个4阶排列的集合是强制的。我们提供了排列强迫集大小的第一个非平凡下界:每个排列强迫集(任意顺序)至少包含四个排列。
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引用次数: 6
Triangles in randomly perturbed graphs 随机摄动图中的三角形
IF 0.9 4区 数学 Q2 Mathematics Pub Date : 2020-11-15 DOI: 10.1017/S0963548322000153
Julia Böttcher, Olaf Parczyk, Amedeo Sgueglia, J. Skokan
We study the problem of finding pairwise vertex-disjoint triangles in the randomly perturbed graph model, which is the union of any $n$-vertex graph $G$ with linear minimum degree and the binomial random graph $G(n,p)$. We prove that asymptotically almost surely $G cup G(n,p)$ contains $min {delta(G), lfloor n/3 rfloor }$ pairwise vertex-disjoint triangles, provided $p ge C log n/n$, where $C$ is a large enough constant. This is a perturbed version of an old result of Dirac. Our result is asymptotically optimal and answers a question of Han, Morris, and Treglown [RSA, to appear] in the case of triangle-factors. Together with a result of Balogh, Treglown, and Wagner [CPC, 2019, no. 2, 159-176] this fully resolves the existence of triangle-factors in randomly perturbed graphs. We also prove a stability version of our result. Finally, we discuss further generalisations to larger clique-factors, larger cycle-factors, and $2$-universality.
研究了任意具有线性最小度的$n$ -顶点图$G$与二项随机图$G(n,p)$的并集的随机摄动图模型中寻找两两顶点不相交三角形的问题。我们渐近地几乎肯定地证明$G cup G(n,p)$包含$min {delta(G), lfloor n/3 rfloor }$对顶点不相交三角形,假设$p ge C log n/n$,其中$C$是一个足够大的常数。这是狄拉克旧结果的扰动版本。我们的结果是渐近最优的,并回答了Han, Morris和Treglown [RSA,出现]在三角形因子的情况下的问题。连同Balogh, treglon和Wagner的结果[CPC, 2019, no. 5]。[2,159 -176]这完全解决了随机摄动图中三角形因子的存在性。我们还证明了结果的稳定性版本。最后,我们讨论了进一步推广到更大的团因子、更大的循环因子和$2$ -普遍性。
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引用次数: 10
Refined universality for critical KCM: lower bounds 临界KCM的改进通用性:下界
IF 0.9 4区 数学 Q2 Mathematics Pub Date : 2020-11-13 DOI: 10.1017/S0963548322000025
Ivailo Hartarsky, Laure Marech'e
We study a general class of interacting particle systems called kinetically constrained models (KCM) in two dimensions tightly linked to the monotone cellular automata called bootstrap percolation. There are three classes of such models, the most studied being the critical one. In a recent series of works by Martinelli, Morris, Toninelli and the authors, it was shown that the KCM counterparts of critical bootstrap percolation models with the same properties split into two classes with different behaviour. Together with the companion paper by the first author, our work determines the logarithm of the infection time up to a constant factor for all critical KCM, which were previously known only up to logarithmic corrections. This improves all previous results except for the Duarte-KCM, for which we give a new proof of the best result known. We establish that on this level of precision critical KCM have to be classified into seven categories instead of the two in bootstrap percolation. In the present work, we establish lower bounds for critical KCM in a unified way, also recovering the universality result of Toninelli and the authors and the Duarte model result of Martinelli, Toninelli and the second author.
我们研究了一类相互作用的粒子系统,称为动力学约束模型(KCM),它在二维中与称为自举渗透的单调元胞自动机紧密相连。这类模型有三类,研究最多的是关键模型。Martinelli、Morris、Toninelli等人最近的一系列研究表明,具有相同性质的临界自举渗流模型的KCM对应体分为两个具有不同行为的类。与第一作者的论文一起,我们的工作确定了感染时间的对数,直到所有关键KCM的常数因子,这在以前只知道对数修正。这改进了除了Duarte-KCM之外的所有先前的结果,对于Duarte-KCM,我们给出了已知最佳结果的新证明。我们建立了在这个精度水平上临界KCM必须分为7类,而不是自举渗透中的2类。本文统一建立了临界KCM的下界,恢复了Toninelli和作者的普适性结果以及Martinelli、Toninelli和第二作者的Duarte模型结果。
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引用次数: 9
期刊
Combinatorics, Probability & Computing
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