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1
Content available remote The Diophantine equation f(x) = g(y)
100%
Bilu Y. F. , Tichy R. F.
Acta Arithmetica
|
2000
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tom 95
|
nr 3
261-288
2
Content available remote Process Engineering in Iron Production
100%
Pustějovská P. , Jursová S.
Chemical and Process Engineering
|
2013
|
tom 34
|
nr 1
63-76
EN
Balance, thermodynamic and mainly kinetic approaches using methods of process engineering enable to determine conditions under which iron technology can actually work in limiting technological states, at the lowest reachable fuel consumption (reducing factor) and the highest reachable productivity accordingly. Kinetic simulation can be also used for variant prognostic calculations. The paper deals with thermodynamics and kinetics of iron making process. It presents a kinetic model of iron oxide reduction in a low temperature area. In the experimental part it deals with testing of iron ore feedstock properties. The theoretical and practical limits determined by heat conditions, feedstock reducibility and kinetics of processes are calculated.
3
Content available On infinite uniquely partitionable graphs and graph properties of finite character
100%
Bucko J. , Mihók P.
Discussiones Mathematicae Graph Theory
|
2009
|
tom 29
|
nr 2
241-251
EN
A graph property is any nonempty isomorphism-closed class of simple (finite or infinite) graphs. A graph property 𝓟 is of finite character if a graph G has a property 𝓟 if and only if every finite induced subgraph of G has a property 𝓟. Let 𝓟₁,𝓟₂,...,𝓟ₙ be graph properties of finite character, a graph G is said to be (uniquely) (𝓟₁, 𝓟₂, ...,𝓟ₙ)-partitionable if there is an (exactly one) partition {V₁, V₂, ..., Vₙ} of V(G) such that $G[V_i] ∈ 𝓟_i$ for i = 1,2,...,n. Let us denote by ℜ = 𝓟₁ ∘ 𝓟₂ ∘ ... ∘ 𝓟ₙ the class of all (𝓟₁,𝓟₂,...,𝓟ₙ)-partitionable graphs. A property ℜ = 𝓟₁ ∘ 𝓟₂ ∘ ... ∘ 𝓟ₙ, n ≥ 2 is said to be reducible. We prove that any reducible additive graph property ℜ of finite character has a uniquely (𝓟₁, 𝓟₂, ...,𝓟ₙ)-partitionable countable generating graph. We also prove that for a reducible additive hereditary graph property ℜ of finite character there exists a weakly universal countable graph if and only if each property $𝓟_i$ has a weakly universal graph.
4
Content available On the factorization of reducible properties of graphs into irreducible factors
100%
Mihók P. , Vasky R.
Discussiones Mathematicae Graph Theory
|
1995
|
tom 15
|
nr 2
195-203
EN
A hereditary property R of graphs is said to be reducible if there exist hereditary properties P₁,P₂ such that G ∈ R if and only if the set of vertices of G can be partitioned into V(G) = V₁∪V₂ so that ⟨V₁⟩ ∈ P₁ and ⟨V₂⟩ ∈ P₂. The problem of the factorization of reducible properties into irreducible factors is investigated.
5
Content available Reducible properties of graphs
100%
Mihók P. , Semanišin G.
Discussiones Mathematicae Graph Theory
|
1995
|
tom 15
|
nr 1
11-18
EN
Let L be the set of all hereditary and additive properties of graphs. For P₁, P₂ ∈ L, the reducible property R = P₁∘P₂ is defined as follows: G ∈ R if and only if there is a partition V(G) = V₁∪ V₂ of the vertex set of G such that $⟨V₁⟩_G ∈ P₁$ and $⟨V₂⟩_G ∈ P₂$. The aim of this paper is to investigate the structure of the reducible properties of graphs with emphasis on the uniqueness of the decomposition of a reducible property into irreducible ones.
6
Content available Uniquely partitionable graphs
100%
Bucko J. , Frick M. , Mihók P. , Vasky R.
Discussiones Mathematicae Graph Theory
|
1997
|
tom 17
|
nr 1
103-113
EN
Let 𝓟₁,...,𝓟ₙ be properties of graphs. A (𝓟₁,...,𝓟ₙ)-partition of a graph G is a partition of the vertex set V(G) into subsets V₁, ...,Vₙ such that the subgraph $G[V_i]$ induced by $V_i$ has property $𝓟_i$; i = 1,...,n. A graph G is said to be uniquely (𝓟₁, ...,𝓟ₙ)-partitionable if G has exactly one (𝓟₁,...,𝓟ₙ)-partition. A property 𝓟 is called hereditary if every subgraph of every graph with property 𝓟 also has property 𝓟. If every graph that is a disjoint union of two graphs that have property 𝓟 also has property 𝓟, then we say that 𝓟 is additive. A property 𝓟 is called degenerate if there exists a bipartite graph that does not have property 𝓟. In this paper, we prove that if 𝓟₁,..., 𝓟ₙ are degenerate, additive, hereditary properties of graphs, then there exists a uniquely (𝓟₁,...,𝓟ₙ)-partitionable graph.
7
Content available Criteria for of the existence of uniquely partitionable graphs with respect to additive induced-hereditary properties
100%
Broere I. , Bucko J. , Mihók P.
Discussiones Mathematicae Graph Theory
|
2002
|
tom 22
|
nr 1
31-37
EN
Let 𝓟₁,𝓟₂,...,𝓟ₙ be graph properties, a graph G is said to be uniquely (𝓟₁,𝓟₂, ...,𝓟ₙ)-partitionable if there is exactly one (unordered) partition {V₁,V₂,...,Vₙ} of V(G) such that $G[V_i] ∈ 𝓟_i$ for i = 1,2,...,n. We prove that for additive and induced-hereditary properties uniquely (𝓟₁,𝓟₂,...,𝓟ₙ)-partitionable graphs exist if and only if $𝓟_i$ and $𝓟_j$ are either coprime or equal irreducible properties of graphs for every i ≠ j, i,j ∈ {1,2,...,n}.
8
Content available remote The Role of CeO₂-Doping of γ-Al₂O₃ on its Structural and Superficial Area
88%
Aribi K. , Ghelamallah M. , Bellifa A. , Bousehaba F.
Acta Physica Polonica A
|
2017
|
tom 132
|
nr 3
445-447
EN
A series of samples, noted Al_xCe_{1-x} has been prepared by hydrolysis, from γ-Al₂O₃ and CeO₂. These samples were calcined under air at 450, 900 and 1200°C, and then characterized by specific surface area, X-ray diffraction and thermoreduction programmed under H₂. Obtained results show that after calcination at 450 and 900°C, the cerium decreases the surface of alumina. Results of X-ray diffraction and thermoreduction programmed under H₂ experiments showed that the samples are constituted of: γ-Al₂O₃ and CeO₂. The global consumption of hydrogen increase with rate of CeO₂ added. At 1200°C, the sintering of the samples is very important and γ-Al₂O₃ is transformed into the α-phase. The decrease in specific surface area is more accentuated for Al₁Ce₀ sample, since sintering occurs due to the growth in crystallite size. Thermoreduction programmed under H₂ experiments show that reduction of CeO₂ much more accentuated for ceria samples or its decrease can reflect some alterations of the nature of interactions between Al₂O₃ and CeO₂.
9
Content available Cardinality of a minimal forbidden graph family for reducible additive hereditary graph properties
88%
Drgas-Burchardt E.
Discussiones Mathematicae Graph Theory
|
2009
|
tom 29
|
nr 2
263-274
EN
An additive hereditary graph property is any class of simple graphs, which is closed under isomorphisms unions and taking subgraphs. Let $L^a$ denote a class of all such properties. In the paper, we consider H-reducible over $L^a$ properties with H being a fixed graph. The finiteness of the sets of all minimal forbidden graphs is analyzed for such properties.
10
Content available Generalized ramsey theory and decomposable properties of graphs
75%
Burr S. , Jacobson M. , Mihók P. , Semanišin G.
Discussiones Mathematicae Graph Theory
|
1999
|
tom 19
|
nr 2
199-217
EN
In this paper we translate Ramsey-type problems into the language of decomposable hereditary properties of graphs. We prove a distributive law for reducible and decomposable properties of graphs. Using it we establish some values of graph theoretical invariants of decomposable properties and show their correspondence to generalized Ramsey numbers.
11
Content available On generating sets of induced-hereditary properties
75%
Semanišin G.
Discussiones Mathematicae Graph Theory
|
2002
|
tom 22
|
nr 1
183-192
EN
A natural generalization of the fundamental graph vertex-colouring problem leads to the class of problems known as generalized or improper colourings. These problems can be very well described in the language of reducible (induced) hereditary properties of graphs. It turned out that a very useful tool for the unique determination of these properties are generating sets. In this paper we focus on the structure of specific generating sets which provide the base for the proof of The Unique Factorization Theorem for induced-hereditary properties of graphs.
12
Zaawansowany system nadzoru atmosfery roboczej w urządzeniu do oznaczania redukcyjności rud żelaza
63%
Ryciak S. , Grotkowski Ł. , Kiełczewski R.
|
2010
|
tom Vol. 51, nr 7
211-214
PL
Artykuł opisuje zaawansowany system nadzoru atmosfery roboczej wchodzący w skład urządzenia do badania redukcyjności rud żelaza. Normy jakościowe i wymagania technologiczne narzucają zastosowanie zaawansowanych rozwiązań dystrybucji gazów (w tym toksycznego tlenku węgla) oraz niezawodnej ochrony zdrowia personelu. Układy rozproszone oraz użycie sterownika PLC umożliwiają realizację tych zadań.
EN
The article describes advenced system of working atmosphere surveillance in ironstone reducibility determination unit - one of devicesinvented in Tele & Radio Researcg Institute. Quality standards and technological requirements impose application of advenced solutions for gas distribution. Distributed system and use of PLC controller allow accomplishment of these problems.
13
Badania wpływu składu chemicznego katalizatorów Cu-Zn-Al do parowego reformingu metanolu na przebieg ich aktywacji termicznej
63%
Próchniak W. , Kowalik P. , Borowiecki T.
|
2009
|
tom Nr 1
45-48
PL
Przedstawiono wyniki badań nad wpływem składu chemicznego współstrącanych katalizatorów Cu-Zn-Al przeznaczonych do reakcji parowego reformingu metanolu na ich kalcynację i redukcję. Dokonano oceny właściwości fizykochemicznych modelowych próbek badając skład fazowy i przebieg kalcynacji prekursorów oraz redukowalność katalizatorów. Ustalono optymalne warunki obróbki termicznej prekursorów i katalizatorów.
EN
The paper presents investigation results of chemical composition effect of coprecipitated Cu-Zn-Al catalysts for steam reforming of methanol on their calcination and reduction. Physico-chemical properties of model samples were evaluated by analysis of phase composition, precursors' calcination and catalyst reducibility. Optional conditions of precursor and catalyst thermal processing were determined.
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