An evaluation of urban consolidation centers through continuous analysis with non-equal market share companies

This paper analyzes the logistic cost savings caused by the implementation of Urban Consolidation Centers (UCC) in a dense area of a city. In these urban terminals, freight flows from interurban carriers are consolidated and transferred to a neutral last-mile carrier to perform final deliveries. This operation would reduce both last-mile fleet size and average distance cost. Our UCC modeling approach is focused on continuous analytic models for the general case of carriers with different market shares. Savings are highly sensitive to the design of the system: the increment of capacity in interurban vehicles and the proximity of the UCC terminal to the area in relation to current distribution centers. An exhaustive collection of possible market shares distributions are discussed. Results show that market shares distribution does not affect cost savings significantly. The analysis of the proposed model also highlights the trade-off between savings in the system and a minimum market share per company when the consolidation center is established.Postprint (published version

Bidimensional scattering of tm and te polarized waves by dielectric

In the study of electromagnetic radiation effects over dielectric bodies, effective numerical methods are needed. At present, there is a lack of tools for measuring this effects and due to the huge growth of microwave devices, like cellular radio telephones working close to the human body, it is necessary to develop accurate numerical methods for evaluating those effects. One of the most efficient and extensively used method is the FFT-CGM (Fast-Fourier-Transform Conjugate Gradient Method). In this paper, algorithms for solving the two-dimensional scattering of transversal magnetic (TM) and transversal electric (TE) polarized waves by a lossy dielectric and metallic objects are presented. At the same time, the SAR (Specific Absorption Rate) of tissues and the modified radiation diagrams when the body is present are obtained from the diffracted fields.Peer ReviewedPostprint (published version

Stakeholder’s profitability of carrier-led consolidation strategies in urban goods distribution

This paper presents the necessary conditions to ensure a minimal profitability of carrier-led consolidation strategies in urban distribution. These conditions are shown by compact formulas obtained by continuous approximations representing the cost of the stakeholders involved: society, regular carriers, consolidation facility operator and environment. The domain of the retailer density variable that always produces negative effects on each stakeholder has been identified. The envelope of this domain does not depend on vehicle costs and other site-related parameters. On the other hand, there is a critical density of receivers that makes the carrier cost savings higher than the CF operator costs.Postprint (author's final draft

Localised damage model applied to the analysis of masonry structures

La simulación de fisuras localizadas en materiales cuasifrágiles mediante la mecánica computacional es un tema de investigación que aún se encuentra abierto. En este trabajo se plantea un modelo continuo para estudiar la fisuración en estructuras de obra de fábrica. El modelo propuesto, llamado modelo de daño localizado, combina el modelo de daño distribuido tracción/compresión, ampliamente aplicado en el estudio del hormigón, con un algoritmo de rastreo de fisuras. La capacidad del modelo se hace patente al aplicarlo al estudio de un arco semicircular de obra de fábrica con carga asimétrica, cuyos resultados son mucho más realistas que los que se obtienen con el modelo de daño distribuido en su forma original.Peer Reviewe

An enhanced finite element macro-model for the realistic simulation of localized cracks in masonry structures: A large-scale application

Finite element macro-modeling approaches are widely used for the analysis of large-scale masonry structures. Despite their efficiency, they still face two important challenges: the realistic representation of damage and a reasonable independency of the numerical results to the used discretization. In this work, the classical smeared crack approach is enhanced with a crack-tracking algorithm, originating from the analysis of localized cracking in quasi-brittle materials. The proposed algorithm is for the first time applied to a large-scale wall exhibiting multiple shear and flexural cracking. Discussion covers structural aspects, as the response of the structure under different assumptions regarding the floor rigidity, but also numerical issues, commonly overlooked in the simulation of large structures, such the mesh-dependency of the numerical results

Structural Analysis of Masonry Historical Constructions. Classical and Advanced Approaches

A review of methods applicable to the study of masonry historical construction, encompassing both classical and advanced ones, is presented. Firstly, the paper offers a discussion on the main challenges posed by historical structures and the desirable conditions that approaches oriented to the modeling and analysis of this type of structures should accomplish. Secondly, the main available methods which are actually used for study masonry historical structures are referred to and discussed. The main available strategies, including limit analysis, simplified methods, FEM macro- or micro-modeling and discrete element methods (DEM) are considered with regard to their realism, computer efficiency, data availability and real applicability to large structures. A set of final considerations are offered on the real possibility of carrying out realistic analysis of complex historic masonry structures. In spite of the modern developments, the study of historical buildings is still facing significant difficulties linked to computational effort, possibility of input data acquisition and limited realism of methods