Alphabetical satisfiability problem for trace equations

It is known that the satisfiability problem for equations over free partially commutative monoids is decidable but computationally hard. In this paper we consider the satisfiability problem for equations over free partially commutative monoids under the constraint that the solution is a subset of the alphabet. We prove that this problem is NP-complete for quadratic equations and that its uniform version is NP-complete for linear equations

Guest editors' introduction: special section on fault diagnosis and tolerance in cryptography

The objective of this special section is to present some of the state-of-the-art developments in the analysis of fault attacks and the techniques to protect crypto-systems from such attacks

Formal Languages and Compilation

This textbook describes the essential principles and methods used for defining the syntax of artificial languages, and for designing efficient parsing algorithms and syntax-directed translators with semantic attributes. A comprehensive selection of topics is presented within a rigorous, unified framework, illustrated by numerous practical examples. Features and topics: presents a novel conceptual approach to parsing algorithms that applies to extended BNF grammars, together with a parallel parsing algorithm; supplies supplementary teaching tools, including course slides and exercises with solutions, at an associated website; unifies the concepts and notations used in different approaches, enabling an extended coverage of methods with a reduced number of definitions; systematically discusses ambiguous forms, allowing readers to avoid pitfalls when designing grammars; describes all algorithms in pseudocode, so that detailed knowledge of a specific programming language is not necessary; makes extensive usage of theoretical models of automata, transducers and formal grammars; includes concise coverage of algorithms for processing regular expressions and finite automata; and introduces static program analysis based on flow equations. This clearly-written, classroom-tested textbook is an ideal guide to the fundamentals of this field for advanced undergraduate and graduate students in computer science and computer engineering. Some background in programming is required, and readers should also be familiar with basic set theory, algebra and logic

Shear strengthening of reinforced concrete beams strengthened using embedded through section steel bars

A new shear strengthening technique, designated as embedded through section (ETS), has been developed to retrofit existing reinforced concrete (RC) elements. This technique calls for holes to be drilled through the beam section; then bars of steel or FRP materials are introduced into these holes and bonded with adhesives to the surrounding concrete. When concrete cover has not the bond and strength requisites to guarantee a strengthening effectiveness for the Externally Bonded and Near Surface Mounted techniques, ETS strategy can be a competitive alternative since it mobilizes the beam’s concrete core which is, generally, free of damage. To explore the potentialities of the ETS technique for the shear strengthening of RC beams, an experimental program was carried out, composed of RC T-cross section beams shear strengthened by using steel bars. The influence on the shear strengthening efficiency of the inclination and shear strengthening ratio of ETS configurations was evaluated; the study also examined the interaction of ETS bars and existing steel stirrups. An increase of shear capacity up to 109% and 136% in the beams with and without internal stirrups, respectively, was obtained. Inclined ETS bars provided higher increase of shear resistance than vertical ones.The authors wish to acknowledge Elletipi S.r.l. (Ferrara, Italy) for supporting the experimental program, Interbau S.r.l. (Milano, Italy) for applying the ETS strengthening system and the ENDIF Geomatic Group (University of Ferrara, Italy) for monitoring the experimental program. The authors also wish to acknowledge the Engineering Department of the University of Ferrara for its financial support

RC beams strengthened in shear using the Embedded Through-Section technique: experimental results and analytical formulation

The Embedded Through-Section (ETS) is a recent strengthening technique that has been developed to retrofit existing reinforced concrete (RC) elements with shear reinforcement deficiencies. This technique is based on the execution of holes drilled through the element cross section, in which steel or fiber reinforced polymer (FRP) bars are inserted and bonded to the surrounding concrete with an epoxy adhesive. An experimental program was carried out with RC T-cross section beams strengthened in shear using steel ETS bars. The influence of the inclination and shear strengthening ratio of ETS on the shear strengthening efficiency was evaluated, as well as the interaction of ETS bars with existing steel stirrups. Two different analytical models are presented in this paper in order to calculate the contribution of ETS to shear resistance. The first model follows an empirical approach (experimental-based approach), while the second model takes into account the physical and mechanical principles of the technique (mechanical-based approach). The predictive performance of both models is assessed by using the experimental results.The authors wish to acknowledge the support provided by the CutInov project QREN n. 38780 supported by ADI, and by the Engineering Department of the University of Ferrara