1,327 research outputs found
Fire prevention technical rule for gaseous hydrogen transport in pipelines
No full textThis paper presents the current results of the theoretical and experimental activity carried out by the Italian Working Group on the previous termhydrogennext termprevious termfirenext termprevious termpreventionnext term safety issues in the field of the previous termhydrogennext termprevious termtransportnext term in previous termpipelinesnext term [Grasso N, Ciannelli N, Pilo F, Carcassi M, Ceccherini F. previous termFirenext termprevious termpreventionnext termprevious termtechnicalnext termprevious termrulenext term for previous termgaseousnext termprevious termhydrogennext term refuelling stations. Proceedings of the International Conference on previous termHydrogennext term Safety, 8–10 September 2005, Pisa, Paper 420064]. From the theoretical point of view a draft document has been produced beginning from the Italian regulations in force on the natural gas previous termpipelinesnext term; these have been reviewed, corrected and integrated with instructions suitable to use with previous termhydrogennext term gas. From the experimental point of view a suitable apparatus has been designed and installed at the University of Pisa; this apparatus will allow simulations of previous termhydrogennext term releases from a previous termpipelinenext term with or without ignition of the previous termhydrogennext term–air mixture. The experimental data will help the completion of the above-mentioned draft document with the instructions about the safety distances. However, in the opinion of the Group, the work on the text contents is concluded and the document is ready to be discussed with the Italian stakeholders involved in the previous termhydrogennext term applications
Abelian extensions
No full textThis chapter is based on (Canad J Math 23:857–865, 1971; Canad J Math 25:1113–1119, 1973) by R. L. Roth. Previous papers with some results on this subject include (J. Fac. Sci. Univ. Tokyo Sec. I 10:129–146, 1964) (Pacific J Math 32:119–129, 1970) by N. Iwahori – H. Matsumoto and G. J. Janusz, respectively. See also Sect. 2.4, where the more general case when G∕IG(σ) is Abelian was studied
Hecke algebras
No full textSia G un gruppo finito e K un sottogruppo. Dalla similarità tra rappresentazioni indotte e rappresentazioni permutazionali abbiamo un isomorfismo tra l'algebra delle funzioni bi-K-invarianti su G e il commutante della rappresentazione ottenuta inducendo la banale da K a G.Let G be a finite group and K ≤ G a subgroup. Recalling the equality between the induced representation (IndKGιK,IndKGC) and the permutation representation (λ, L(G)K), (1.11) yields a ∗-algebra isomorphism between the algebra of bi-K-invariant functions on G and the commutant of the representation obtained by inducing to G the trivial representation of K
Central Extensions and the Orbit Method
No full textIn this chapter we treat central extensions of groups, a particular case of the construction in Sect. 1.5, and we give a complete cohomological characterization of these. Following Mihailovs (The orbit method for finite groups of nilpotency class two of odd order. Preprint: arXiv.org: math.RT/0001092) and Kokhas (J Math Sci (NY) 131(2):5508–5555, 2004) with a 2-step nilpotent group with 2-divisible center we associate a 2-step nilpotent Lie ring. This is a key construction for the definition and application of the orbit method
Clifford Theory for Projective Representations
No full textIn this chapter, we establish some basic facts on Clifford theory for induced projective representations. We follow quite closely the exposition for the case of ordinary representations in Chap. 2 and we give the first applications of the theory. Another fundamental application is in Sect. 10.2 on irreducible projective representations of finite Abelian groups
Representations of Finite Group Extensions via Projective Representations
No full textIn this chapter we give a formulation of the little group method (cf. Theorem 2.26 ) for arbitrary group extensions, that is, we do not assume existence of an extension of σ∈ N^ to its inertia group IG(σ). We also give a sufficient condition for the existence of such an extension. All these facts require a suitable cohomological machinery. It is due to Mackey (who actually proved more general results for topological groups), but some aspects of it were anticipated by Schur and others within the theory of projective representations; see Berkovich and Zhmud (Characters of finite groups. Part 1, Translations of Mathematical Monographs, vol 172. American Mathematical Society, Providence, 1998), Huppert (Character Theory of Finite Groups, De Gruyter Expositions in Mathematics, vol 25. Walter de Gruyter, 1998), and Isaacs (Character theory of finite groups, Corrected reprint of the 1976 original [Academic Press, New York]. Dover Publications, New York, 1994). Actually, we follow Mackey’s approach as described in Fell and Doran (Pure and Applied Mathematics, vol. 126. Academic Press, Boston, 1988); see also Tucker (Am J Math 84:400–420)
Clifford Theory
No full textIn this chapter, we establish some basic facts on Clifford theory for induced representations from a normal subgroup and we give the first applications of the theory
Examples and Applications
No full textThe purpose of this chapter is to present some examples and applications of the little group method for Abelian extensions
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