Connection between electrical conductivity and diffusion coefficient of a conductive porous material filled with electrolyte

The paper focuses on the cross-property connection between the effective electrical conductivity and the overall mass transfer coefficient of a two phase material. The two properties are expressed in terms of the tortuosity parameter which generalized to the case of a material with two conductive phases. Elimination of this parameter yields the cross-property connection. The theoretical derivation is verified by comparison with computer simulation

LHCb trigger streams optimization

The LHCb experiment stores around $10^{11}$ collision events per year. A typical physics analysis deals with a final sample of up to $10^7$ events. Event preselection algorithms (lines) are used for data reduction. Since the data are stored in a format that requires sequential access, the lines are grouped into several output file streams, in order to increase the efficiency of user analysis jobs that read these data. The scheme efficiency heavily depends on the stream composition. By putting similar lines together and balancing the stream sizes it is possible to reduce the overhead. We present a method for finding an optimal stream composition. The method is applied to a part of the LHCb data (Turbo stream) on the stage where it is prepared for user physics analysis. This results in an expected improvement of 15% in the speed of user analysis jobs, and will be applied on data to be recorded in 2017.Comment: Submitted to CHEP-2016 proceeding

Quantitative modeling of \textit{in situ} x-ray reflectivity during organic molecule thin film growth

Synchrotron-based x-ray reflectivity is increasingly employed as an \textit{in situ} probe of surface morphology during thin film growth, but complete interpretation of the results requires modeling the growth process. Many models have been developed and employed for this purpose, yet no detailed, comparative studies of their scope and accuracy exists in the literature. Using experimental data obtained from hyperthermal deposition of pentane and diindenoperylene (DIP) on SiO$_2$, we compare and contrast three such models, both with each other and with detailed characterization of the surface morphology using ex-situ atomic force microscopy (AFM). These two systems each exhibit particular phenomena of broader interest: pentacene/SiO$_2$ exhibits a rapid transition from rough to smooth growth. DIP/SiO$_2$, under the conditions employed here, exhibits growth rate acceleration due to a different sticking probability between the substrate and film. In general, \textit{independent of which model is used}, we find good agreement between the surface morphology obtained from fits to the \insitu x-ray data with the actual morphology at early times. This agreement deteriorates at later time, once the root-mean squared (rms) film roughness exceeds about 1 ML. A second observation is that, because layer coverages are under-determined by the evolution of a single point on the reflectivity curve, we find that the best fits to reflectivity data --- corresponding to the lowest values of $\chi_\nu^2$ --- do not necessarily yield the best agreement between simulated and measured surface morphologies. Instead, it appears critical that the model reproduce all local extrema in the data. In addition to showing that layer morphologies can be extracted from a minimal set of data, the methodology established here provides a basis for improving models of multilayer growth by comparison to real systems.Comment: 34 pages (double-spaced, including figures and references), 10 figures, 3 appendice

Анализ влияния авиационного транспорта на загрязнение атмосферы

Розглянуто проблему забруднення атмосфери авіаційним транспортом України та узагальнено шляхи її вирішення. Досліджено вплив емісії авіаційних двигунів на екологічний стан України. Проаналізовано напрямки зменшення забруднення атмосфери літаками, виявлено їх переваги та недоліки. Запропоновано розглянуту проблему вирішувати одночасно у таких чотирьох напрямках: хімічному, конструкційному, економічному та впровадження на авіаційному транспорті альтернативних видів енергії.The problem of atmosphere contamination by air transport of Ukraine and generalized ways of it solution is a main question in this article. The primary purpose of the work was an analysis of jet engines emissions impact on the state of atmosphere in Ukraine, and also generalization of the ways for problem solving. Directions of atmosphere contamination diminishing are analyzed, their advantages and disadvantages are found out. It is stated that decision of the problem of atmospheric air contamination by air transport must be complex. Existed methods minimizing pollution of atmosphere are analyzed. However they can solve some certain task only and do not provide diminishing of harmful influence from all factors. The decision for investigated problem is offered via simultaneous restriction of four ecological indexes of jet engines emissions: chemical, construction, economic and introduction of alternative types of energy in aviation. The results of researches can be applied in sphere of ecology and environmental protection. The results of the work can be applied by experts-environmentalists, and also power engineering specialists as well as chematologists in area of rational use of aviation fuels.Рассмотрена проблема загрязнения атмосферы авиационным транспортом Украины и обобщенно пути ее решения. Исследовано влияние эмиссии авиационных двигателей на экологическое состояние Украины. Проанализированы направления уменьшения загрязнения атмосферы самолетами, обнаружены их преимущества и недостатки. Предложено рассмотренную проблему решать одновременно в таких четырех направлениях: химическому, конструкционному, экономическому и внедрение на авиационном транспорте альтернативных видов энергии

On adjacency operators of locally finite graphs

A graph $\Gamma$ is called locally finite if, for each vertex $v$ of $\Gamma$, the set $\Gamma(v)$ of all neighbors of $v$ in $\Gamma$ is finite. For any locally finite graph $\Gamma$ with vertex set $V(\Gamma)$ and for any field $F$, let $F^{V(\Gamma)}$ be the vector space over $F$ of all functions $V(\Gamma) \to F$ (with natural componentwise operations) and let $A^{({\rm alg})}_{\Gamma,F}$ be the linear operator $F^{V(\Gamma)} \to F^{V(\Gamma)}$ defined by $(A^{({\rm alg})}_{\Gamma,F}(f))(v) = \sum_{u \in \Gamma(v)}f(u)$ for all $f \in F^{V(\Gamma)}$, $v \in V(\Gamma)$. In the case of finite graph $\Gamma$ the mapping $A^{({\rm alg})}_{\Gamma,F}$ is the well known operator defined by the adjacency matrix of $\Gamma$ (over $F$), and the theory of eigenvalues and eigenfunctions of such operator is a well-developed (at least in the case $F = \mathbb{C}$) part of the theory of finite graphs. In this paper we develope a theory of eigenvalues and eigenfunctions of $A^{({\rm alg})}_{\Gamma,F}$ for arbitrary infinite locally finite graphs $\Gamma$ (although a few results may be of interest for finite graphs) and fields $F$ with a special emphasis on the case when $\Gamma$ is connected with uniformly bounded vertex degrees and $F = \mathbb{C}$. By the author opinion, previous attempts in this direction were not quite satisfactory since were limited by consideration of rather special eigenfunctions and corresponding eigenvalues.Comment: in Russia

О пределах вершинно-симметрических графов и их автоморфизмах

Using a simple but rather general method of constructing Cayley graphs with trivial vertex stabilizers, we give an example of an infinite locally finite Cayley graph (and, hence, an example of an infinite connected locally finite vertex-symmetric unimodular graph) which is isolated in the space of connected locally finite vertex-symmetric graphs. We also give examples of Cayley graphs which are not isolated in this space but are isolated from the set of connected vertex-symmetric finite graphs. © 2019 Krasovskii Institute of Mathematics and Mechanics. All right reserved