2,012 research outputs found
C*-algebras of separated graphs
The construction of the C*-algebra associated to a directed graph is
extended to incorporate a family consisting of partitions of the sets of
edges emanating from the vertices of . These C*-algebras are
analyzed in terms of their ideal theory and K-theory, mainly in the case of
partitions by finite sets. The groups and are
completely described via a map built from an adjacency matrix associated to
. One application determines the K-theory of the C*-algebras
, confirming a conjecture of McClanahan. A reduced
C*-algebra \Cstred(E,C) is also introduced and studied. A key tool in its
construction is the existence of canonical faithful conditional expectations
from the C*-algebra of any row-finite graph to the C*-subalgebra generated by
its vertices. Differences between \Cstred(E,C) and , such as
simplicity versus non-simplicity, are exhibited in various examples, related to
some algebras studied by McClanahan.Comment: 29 pages. Revised version, to appear in J. Functional Analysi
Restrained Shrinkage of Fly Ash Based Geopolymer Concrete and Analysis of Long Term Shrinkage Prediction Models
The research presented in this manuscript describes the procedure to quantify the restrained shrinkage of geopolymer concrete (GPC) using ring specimen. Massive concrete structures are susceptible to shrinkage and thermal cracking. This cracking can increase the concrete permeability and decrease the strength and design life. This test is comprised of evaluating geopolymer concrete of six different mix designs including different activator solution to fly ash ratio and subjected to both restrained and free shrinkage. Test results obtained from this experimental setup was plotted along with the available empirical equation to observe the shrinkage strain of GPC and a model was suggested to predict the shrinkage strain of GPC. It was found from this study that along with activator solution to fly ash ratio the final compressive strength of GPC plays an important role on shrinkage strai
The almost isomorphism relation for simple regular rings
A longstanding open problem in the theory of von Neumann regular rings is the question of whether every directly finite simple regular ring must be unit-regular. Recent work on this problem has been done by P. Menal, K.C . O'Meara, and the authors. To clarify some aspects of these new developments, we introduce and study the notion of almost isomorphism between finitely generated projective modules over a simple regular ring
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