Search results for "rete"

MP-07.13

2006

On the lattice of prefix codes

2002

AbstractThe natural correspondence between prefix codes and trees is explored, generalizing the results obtained in Giammarresi et al. (Theoret. Comput. Sci. 205 (1998) 1459) for the lattice of finite trees under division and the lattice of finite maximal prefix codes. Joins and meets of prefix codes are studied in this light in connection with such concepts as finiteness, maximality and varieties of rational languages. Decidability results are obtained for several problems involving rational prefix codes, including the solution to the primeness problem.

On the decomposition of prefix codes

2017

Abstract In this paper we focus on the decomposition of rational and maximal prefix codes. We present an effective procedure that allows us to decide whether such a code is decomposable. In this case, the procedure also produces the factors of some of its decompositions. We also give partial results on the problem of deciding whether a rational maximal prefix code decomposes over a finite prefix code.

The mechanically-based approach to 3D non-local linear elasticity theory: Long-range central interactions

2010

Abstract This paper presents the generalization to a three-dimensional (3D) case of a mechanically-based approach to non-local elasticity theory, recently proposed by the authors in a one-dimensional (1D) case. The proposed model assumes that the equilibrium of a volume element is attained by contact forces between adjacent elements and by long-range forces exerted by non-adjacent elements. Specifically, the long-range forces are modelled as central body forces depending on the relative displacement between the centroids of the volume elements, measured along the line connecting the centroids. Further, the long-range forces are assumed to be proportional to a proper, material-dependent, dis…

Convolution-based ensemble learning algorithms to estimate the bond strength of the corroded reinforced concrete

2022

Reinforced concrete bond strength deterioration is one of the most serious problems in the construction industry. It is one of the most common factors impacting structural deterioration and the major cause of premature decadence of reinforced concrete structures. Therefore, developing an accurate model with the lowest variance and high reliability for the bond strength of corroded reinforced concrete is very important. The current work evaluates the efficiency of convolution-based ensemble learning algorithms. To address these issues, convolution-based ensemble learning models are developed using a database collected from the previous experimental studies of relative bond strength for corro…

Steel-concrete bond in lightweight fiber reinforced concrete under monotonic and cyclic actions

2005

Experimental results of the local bond stress-slip relationship of reinforcing bars embedded in lightweight fiber reinforced concrete with expanded clay aggregates are presented. The effect of the following parameters were investigated: - dimension of specimens; - anchorage length; - percentages of hooked steel fibers; - geometrical ratio of transverse reinforcement; - confinement external transverse pressure. Prismatic specimens with deformed steel bars embedded for a fixed length equal to five and eight equivalent diameters were tested under both monotonic and cyclic reversal imposed displacements at the tip of the bars, in controlled displacement tests. The influence of the above mention…

Uniqueness of diffusion on domains with rough boundaries

2016

Let $\Omega$ be a domain in $\mathbf R^d$ and $h(\varphi)=\sum^d_{k,l=1}(\partial_k\varphi, c_{kl}\partial_l\varphi)$ a quadratic form on $L_2(\Omega)$ with domain $C_c^\infty(\Omega)$ where the $c_{kl}$ are real symmetric $L_\infty(\Omega)$-functions with $C(x)=(c_{kl}(x))>0$ for almost all $x\in \Omega$. Further assume there are $a, \delta>0$ such that $a^{-1}d_\Gamma^{\delta}\,I\le C\le a\,d_\Gamma^{\delta}\,I$ for $d_\Gamma\le 1$ where $d_\Gamma$ is the Euclidean distance to the boundary $\Gamma$ of $\Omega$. We assume that $\Gamma$ is Ahlfors $s$-regular and if $s$, the Hausdorff dimension of $\Gamma$, is larger or equal to $d-1$ we also assume a mild uniformity property for $\Omega$ i…

Time-dependent asymmetric traveling salesman problem with time windows: Properties and an exact algorithm

2019

Abstract In this paper, we deal with the Time-Dependent Asymmetric Traveling Salesman Problem with Time Windows. First, we prove that under special conditions the problem can be solved as an Asymmetric Traveling Salesman Problem with Time Windows, with suitable-defined time windows and (constant) travel times. Second, we show that, if the special conditions do not hold, the time-independent optimal solution provides both a lower bound and (eventually) an upper bound with a worst-case guarantee for the Time-Dependent Asymmetric Traveling Salesman Problem with Time Windows. Finally, a branch-and-bound algorithm is presented and tested on a set of 4800 instances. The results have been compared…

A branch-and-price framework for decomposing graphs into relaxed cliques

2021

We study the family of problems of partitioning and covering a graph into/with a minimum number of relaxed cliques. Relaxed cliques are subsets of vertices of a graph for which a clique-defining property—for example, the degree of the vertices, the distance between the vertices, the density of the edges, or the connectivity between the vertices—is relaxed. These graph partitioning and covering problems have important applications in many areas such as social network analysis, biology, and disease-spread prevention. We propose a unified framework based on branch-and-price techniques to compute optimal decompositions. For this purpose, new, effective pricing algorithms are developed, and new…

Case-studies of corroded reinforced concrete bridges in Southern Italy

2020

On Italian roads, a lot of reinforced concrete bridges were built in the 1950’s and 1960’s for short spans, before the advent of prefabricated structures. Many of these bridges, sited on principal or secondary roadways, show the effects of corrosion of reinforcements and high levels of damage, leading to the likelihood of achievement of the Ultimate Limit State, below the required performances of serviceability, especially in the case of Gerber saddles having strongly corroded reinforcements. Different case studies of bridges sited in Southern Italy (Sicily) are shown, allowing engineers to classify the main effects of damage in corroded structures with the Gerber static scheme (cantilever …