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N. This (n + this)
Selected AbstractsUntersuchungen zum Werkstoffverhalten des Feinkornbaustahls S 460 unter erhöhten TemperaturenBAUTECHNIK, Issue 10 2007Jörg Lange Prof. Dr.-Ing. Die Bestimmung der Tragfähigkeit von Bauteilen aus S 460 im Brandfall auf der Grundlage vereinfachter oder allgemeiner Berechnungsverfahren entsprechend EN 1993-1-2 [1] erfordert die Kenntnis der mechanischen Eigenschaften des hochfesten Feinkornbaustahls unter erhöhten Temperaturen. Hierzu wurden Untersuchungen an Probestäben aus einem normalisierend gewalzten S 460 N und einem thermomechanisch gewalzten S 460 M durchgeführt. Beide Stahlsorten unterscheiden sich sowohl in ihrer chemischen Zusammensetzung als auch in der Temperaturführung beim Walzen. Auf der Grundlage instationärer Warmkriechversuche wurden Werkstoffgesetze für den Temperaturbereich von 20 bis 900 °C hergeleitet. Die Untersuchungen zeigen eine im Vergleich zu S 460 N erhöhte Festigkeit des S 460 M bei hohen Temperaturen. Diese ist zurückzuführen auf die durch das thermomechanische Walzen verursachte Verfestigung und die Verringerung der Kriechgeschwindigkeit durch Niob- und Titanausscheidungen. Beim Vergleich der Ergebnisse mit den in EN 1993-1-2 [1] für S 460 angegebenen Werkstoffgesetzen erkennt man, dass diese sowohl die Festigkeit als auch die Steifigkeit des untersuchten S 460 N überschätzen. Examination of the mechanical properties of the microalloyed grain refined steel S 460 at elevated temperatures. To establish a basis for calculating the load-bearing capacity of steel members made of S 460 in fire, corresponding to EN 1993-1-2 [1], the mechanical properties of the microalloyed grain refined steel S 460 under high temperatures have been examined. Two different kinds of steel have been considered: a normalised rolled S 460 N and a thermomechanically rolled S 460 M, that differ in their chemical composition and the temperature control during the hot-rolling process. On the basis of transient state tensile tests, material laws have been derived for the temperature range from 20 to 900 °C. The test results show an increased strength of S 460 M at elevated temperatures in comparison to S 460 N. This is a result of the strain hardening caused by the thermomechanical deformation and the precipitates formed by niobium and titanium that constrain creep deformations. The data derived from the tests show that the stress-strain relationships given in EN 1993-1-2 [1] for S 460 overestimate both the strength and the stiffness of the examined S 460 N. [source] Families of pairs of graphs with a large number of common cardsJOURNAL OF GRAPH THEORY, Issue 2 2010Andrew Bowler Abstract The vertex-deleted subgraph G,v, obtained from the graph G by deleting the vertex v and all edges incident to v, is called a card of G. The deck of G is the multiset of its unlabelled vertex-deleted subgraphs. The number of common cards of G and H (or between G and H) is the cardinality of the multiset intersection of the decks of G and H. In this article, we present infinite families of pairs of graphs of order n , 4 that have at least common cards; we conjecture that these, along with a small number of other families constructed from them, are the only pairs of graphs having this many common cards, for sufficiently large n. This leads us to propose a new stronger version of the Reconstruction Conjecture. In addition, we present an infinite family of pairs of graphs with the same degree sequence that have common cards, for appropriate values of n, from which we can construct pairs having slightly fewer common cards for all other values of n,10. We also present infinite families of pairs of forests and pairs of trees with and common cards, respectively. We then present new families that have the maximum number of common cards when one graph is connected and the other disconnected. Finally, we present a family with a large number of common cards, where one graph is a tree and the other unicyclic, and discuss how many cards are required to determine whether a graph is a tree. © 2009 Wiley Periodicals, Inc. J Graph Theory 63: 146,163, 2010 [source] Improved lower bounds on the randomized complexity of graph properties,RANDOM STRUCTURES AND ALGORITHMS, Issue 3 2007Amit Chakrabarti Abstract We prove a lower bound of ,(n4/3 log 1/3n) on the randomized decision tree complexity of any nontrivial monotone n -vertex graph property, and of any nontrivial monotone bipartite graph property with bipartitions of size n. This improves the previous best bound of ,(n4/3) due to Hajnal (Combinatorica 11 (1991) 131,143). Our proof works by improving a graph packing lemma used in earlier work, and this improvement in turn stems from a novel probabilistic analysis. Graph packing being a well-studied subject in its own right, our improved packing lemma and the probabilistic technique used to prove it may be of independent interest. © 2007 Wiley Periodicals, Inc. Random Struct. Alg., 2007 [source] Avoiding a giant componentRANDOM STRUCTURES AND ALGORITHMS, Issue 1 2001Tom Bohman Let e1,,e,1; e2,,e,2;,;ei,,e,i;,,, be a sequence of ordered pairs of edges chosen uniformly at random from the edge set of the complete graph Kn (i.e. we sample with replacement). This sequence is used to form a graph by choosing at stage i, i=1,,, one edge from ei,e,i to be an edge in the graph, where the choice at stage i is based only on the observation of the edges that have appeared by stage i. We show that these choices can be made so that whp the size of the largest component of the graph formed at stage 0.535n is polylogarithmic in n. This resolves a question of Achlioptas. © 2001 John Wiley & Sons, Inc. Random Struct. Alg., 19, 75,85, 2001 [source] | ||||||||||