A PDE-constrained optimization formulation for discrete fracture network flows

We investigate a new numerical approach for the computation of the 3D flow in a discrete fracture network that does not require a conforming discretization of partial differential equations on complex 3D systems of planar fractures. The discretization within each fracture is performed independently of the discretization of the other fractures and of their intersections. Independent meshing process within each fracture is a very important issue for practical large scale simulations making easier mesh generation. Some numerical simulations are given to show the viability of the method. The resulting approach can be naturally parallelized for dealing with systems with a huge number of fractures

Early warning monitoring of natural and engineered slopes with Ground-Based Synthetic Aperture Radar

The first application of ground-based interferometric synthetic-aperture radar (GBInSAR) for slope monitoring dates back 13 years. Today, GBInSAR is used internationally as a leading-edge tool for near-real-time monitoring of surface slope movements in landslides and open pit mines. The success of the technology relies mainly on its ability to measure slope movements rapidly with sub- millimetric accuracy over wide areas and in almost any weather conditions. In recent years, GBInSAR has experienced significant improvements, due to the development of more advanced radar techniques in terms of both data processing and sensor performance. These improvements have led to widespread diffusion of the technology for early warning monitoring of slopes in both civil and mining applications. The main technical features of modern SAR technology for slope monitoring are discussed in this paper. A comparative analysis with other monitoring technologies is also presented along with some recent examples of successful slope monitorin

A valence bond description of the bromine halogen bond

A theoretical investigation on the nature of the halogen bond through a valence-bond approach has been carried out with two main goals: (a) finding further confirmations of already existing explanations on the physical origins of the halogen bond and (b) possibly enriching the current models with new details. To achieve these goals we have exploited the spin-coupled method and we have performed computations on RBr efNH3 dimers characterized by a different electron withdrawing power of substituent \uf8ffR to the bromine atom. The analysis of typical spin-coupled descriptors (eg, shapes and overlaps of the spin-coupled orbitals, weights of the spin-coupled structures) in the different cases and in function of the distance between the monomers allowed us to draw qualitative conclusions about the formation and the strength of the halogen bonds. In particular, the investigation not only confirmed the validity of already existing models (ie, \u3c3-hole and lump-hole models) but also highlighted interesting new features, such as the fact that the depletion of electron density around the bromine atom does not extend only toward the acceptor of the halogen bond, but also in the opposite direction (toward the substituent of the halogen), thus forming a sort of \u3c3-tunnel, rather than a simple \u3c3-hole

Halogen bonding in the framework of classical force fields: The case of chlorine

Halogen bonding is nowadays a consolidated tool in chemistry. Only recently, the importance of halogen bonding has been demonstrated also in biological systems, owing to the presence of halogens in drugs. This interaction is due to the anisotropy of the electron density around the halogen that leads to the formation of the \u2018\u3c3-hole\u2019, which is responsible for the interaction with a nucleophile site. Unfortunately, classical force fields used in the study of ligand-receptor systems are not able to describe the \u2018\u3c3-hole\u2019. Here, we propose a pseudo-atom based methodology able to correctly describe halogen bonding involving chlorine using classical force field

Coupling traffic models on networks and urban dispersion models for simulating sustainable mobility strategies

The aim of the present paper is to investigate the viability of macroscopic traffic models for modeling and testing different traffic scenarios, in order to define the impact on air quality of different strategies for the reduction of traffic emissions. To this aim, we complement a well assessed traffic model on networks (Garavello, Piccoli, 2006) with a strategy for estimating data needed from the model and we couple it with the urban dispersion model Sirane (Soulhac, 2000)

A hybrid mortar virtual element method for discrete fracture network simulations

The most challenging issue in performing underground flow simulations in Discrete Fracture Networks (DFN), is to effectively tackle the geometrical difficulties of the problem. In this work we put forward a new application of the Virtual Element Method combined with the Mortar method for domain decomposition: we exploit the flexibility of the VEM in handling polygonal meshes in order to easily construct meshes conforming to the traces on each fracture, and we resort to the mortar approach in order to ``weakly'' impose continuity of the solution on intersecting fractures. The resulting method replaces the need for matching grids between fractures, so that the meshing process can be performed independently for each fracture. Numerical results show optimal convergence and robustness in handling very complex geometries

The Origin of the σ-Hole in Halogen Atoms: a Valence Bond Perspective

A detailed Valence Bond-Spin Coupled analysis of a series of halogenated molecules is here reported, allowing to get a rigorous ab initio demonstration of the qualitative models previously proposed to explain the origin of halogen bonding. The concepts of σ-hole and negative belt observed around the halogen atoms in the electrostatic potential maps are here interpreted by analysis of the relevant Spin Coupled orbitals