Electrocoagulation: an electrochemical process for water clarification

Electrocoagulation is a group of various procedures used for removing contaminants from water by electrochemically dissolving aluminum or iron. The contaminants of the solution may be incorporated in the in situ forming metal hydroxide flocs, which can be filtered as a precipitate or skimmed as a float. The main features of the procedure are highlighted on the example of cleaning of an oily waste-water. Design parameters of a 1 m3/h waste-water cleaning system are calculated from the results of small-scale experiments

On the 2-adic order of Stirling numbers of the second kind and their differences

Let $n$ and $k$ be positive integers, $d(k)$ and $\nu_2(k)$ denote the number of ones in the binary representation of $k$ and the highest power of two dividing $k$, respectively. De Wannemacker recently proved for the Stirling numbers of the second kind that $\nu_2(S(2^n,k))=d(k)-1, 1\leq k \leq 2^n$. Here we prove that $\nu_2(S(c2^n,k))=d(k)-1, 1\leq k \leq 2^n$, for any positive integer $c$. We improve and extend this statement in some special cases. For the difference, we obtain lower bounds on $\nu_2(S(c2^{n+1}+u,k)-S(c2^n+u,k))$ for any nonnegative integer $u$, make a conjecture on the exact order and, for $u=0$, prove part of it when $k \leq 6$, or $k \geq 5$ and $d(k) \leq 2$. The proofs rely on congruential identities for power series and polynomials related to the Stirling numbers and Bell polynomials, and some divisibility properties

Realizing QVT with Graph Rewriting-Based Model Transformation

Model-based development is an increasingly applied method in producing software artifacts that is driven by model transformation. For instance, OMG's Model-Driven Architecture as a model-based approach to software development facilitates the synthesis of application programs from models created using customized, domain-specific model processors. Meta Object Facility 2.0 Query/ Views/ Transformation (QVT) is the OMG's standard for specifying model queries, views, and transformations. Extensive research of graph transformation provides a strong formal background for model transformation. The main contribution of this paper is to show how high-level constraint constructs facilitate to realize transformations specified in QVT with metamodel-based model transformation. As a result we can reuse the graph transformation constructs, and its formal background, which facilitates to make QVT transformations validated

Proppant szemcsék mikromechanikai paramétereinek meghatározása

Munkánk során a hidraulikus rétegrepesztésnél használt kitámasztó anyag (proppant) mikromechanikai paramétereit határoztuk meg a YADE nyílt forrás kódú és az EDEM Academic diszkrét elemes szoftverek segítségével. A paraméter identifikációs technikák közül a siló kifolyást választottuk. A kísérleti vizsgálatok során a silóból kifolyt szemcsehalmaz tömegét mértük az idő függvényben és minden esetben meghatároztuk az átlagos kifolyási tömegáramot. A numerikus és a kísérleti úton kapott tömegáramok összehasonlításánál azt tapasztaltuk, hogy az általunk meghatározott mikromechanikai paraméterek alkalmasak a proppant szemcsék mechanikai viselkedésének leírására