Empirical Equation For Tunnel Inflow Assessment: Application to a Case History

Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchiv

A hybridizable discontinuous Galerkin method for both thin and 3D nonlinear elastic structures

We present a 3D hybridizable discontinuous Galerkin (HDG) method for nonlinear elasticity which can be efficiently used for thin structures with large deformation. The HDG method is developed for a three-field formulation of nonlinear elasticity and is endowed with a number of attractive features that make it ideally suited for thin structures. Regarding robustness, the method avoids a variety of locking phenomena such as membrane locking, shear locking, and volumetric locking. Regarding accuracy, the method yields optimal convergence for the displacements, which can be further improved by an inexpensive postprocessing. And finally, regarding efficiency, the only globally coupled unknowns are the degrees of freedom of the numerical trace on the interior faces, resulting in substantial savings in computational time and memory storage. This last feature is particularly advantageous for thin structures because the number of interior faces is typically small. In addition, we discuss the implementation of the HDG method with arc-length algorithms for phenomena such as snapthrough, where the standard load incrementation algorithm becomes unstable. Numerical results are presented to verify the convergence and demonstrate the performance of the HDG method through simple analytical and popular benchmark problems in the literature

Investigation of tectonically affected groundwater systems through a multidisciplinary approach

This study uses a multidisciplinary approach to obtain a complete picture of the groundwater system of complex mountain aquifers. An Alpine region (the north-western area of Lake Como, Italy), characterized by two regional fault systems (The Breglia and Grona fault systems) containing different lithologies, was investigated using the multidisciplinary approach described here. The use of Principal Components Analysis (PCA), classical geochemical bivariate and trivariate diagrams of major and trace elements, and geostructural data, including remote sensing, permitted the identification of three principal groups of water. The first group, characterized by an enrichment of Ca2+ and HCO3-, flow in limestone. The second group is enriched in HCO3-, Ca2+ and Mg2+ and circulates through dolomite rocks. The third group, characterized by a decrease of Ca2+ and Mg2+, an increase of Na++K+ and a high Si/electrical conductivity (EC) ratio, flow in the basement rocks. Nevertheless, some peculiarities were evident. The matching of PCA, hydrochemical and geostructural information explains the role played by faults in water circulation. In particular, the Breglia fault permits the rise of deep water from crystalline basement and dolomite. Similarly, the Grona fault plays a role on drainage in proximity to the contact between the crystalline basement and the sedimentary cover. The springs located near the Grona fault rise into the crystalline basement but reflect a dolomite water chemistry. The multidisciplinary approach allowed understanding of the groundwater system and identification of fault systems not detectable with a geostructural survey

Intra-Articular Hybrid Hyaluronic Acid Injection Treatment in Overweight Patients with Knee Osteoarthritis: A Single-Center, Open-Label, Prospective Study

Abstract: Background: A BMI > 25 is the most decisive, albeit modifiable, risk factor for knee osteoarthritis (KOA). This study aimed at assessing the efficacy of intra-articular injections of hybrid hyaluronic acid (HA) complexes (Sinovial® H-L) for the treatment of KOA in overweight patients in terms of disease severity, cardiocirculatory capacity, and quality of life. Materials: In this single-site, open-label, prospective trial, 37 patients with symptomatic knee OA were assessed at baseline and 3 months after ultrasound-guided intra-articular injection of hybrid HA complexes (Sinovial® H-L). Results: Primary variables displaying a statistically significant improvement after treatment were pain (VAS), disease severity (WOMAC), and cardiopulmonary capacity (6 min walk test). Among secondary variables, quality of life (SF-12) improved significantly, as did analgesic intake for pain control. No statistically significant difference was observed in body fat and muscle mass percentage measured by bioelectrical impedance analysis. Conclusions: Intra-articular hybrid HA injections are significantly effective in improving OA-related disease severity, cardiopulmonary function, and analgesic intake. This supports the role of hybrid HA viscosupplementation as a nonpharmacological treatment to relieve pain, reduce disability, improve quality of life, and limit the risk of polypharmacy in overweight patients with knee OA

Twenty years of experience in juvenile nasopharyngeal angiofibroma (JNA) preoperative endovascular embolization: An effective procedure with a low complications rate

Juvenile nasopharyngeal angiofibroma (JNA) is a benign tumor of the nasal cavity that predominantly affects young boys. Surgical removal remains the gold standard for the management of this disease. Preoperative intra-arterial embolization (PIAE) is useful for reductions in intraoperative blood loss and surgical complications. In our series of 79 patients who underwent preoperative embolization from 1999 to 2020, demographics, procedural aspects, surgical management and follow-up outcome were analyzed. Embolization was performed in a similar fashion for all patients, with a superselective microcatheterization of external carotid artery (ECA) feeders and an injection of polyvinyl alcohol (PVA) particles, followed, in some cases, by the deployment of coils. Procedural success was reached in 100% of cases, with no complications such as bleeding or thromboembolic occlusion, and surgical intraoperative blood loss was significantly decreased. In conclusion, PIAE is a safe and effective technique in JNA treatment, minimizing intraoperative bleeding

A database of the coseismic effects following the 30 October 2016 Norcia earthquake in Central Italy

We provide a database of the coseismic geological surface effects following the Mw 6.5 Norcia earthquake that hit central Italy on 30 October 2016. This was one of the strongest seismic events to occur in Europe in the past thirty years, causing complex surface ruptures over an area of >400 km 2. The database originated from the collaboration of several European teams (Open EMERGEO Working Group; about 130 researchers) coordinated by the Istituto Nazionale di Geofisica e Vulcanologia. The observations were collected by performing detailed field surveys in the epicentral region in order to describe the geometry and kinematics of surface faulting, and subsequently of landslides and other secondary coseismic effects. The resulting database consists of homogeneous georeferenced records identifying 7323 observation points, each of which contains 18 numeric and string fields of relevant information. This database will impact future earthquake studies focused on modelling of the seismic processes in active extensional settings, updating probabilistic estimates of slip distribution, and assessing the hazard of surface faulting

Empirical equation for tunnel inflow assessment: application to a case history.

Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchiv

A spectral hybridizable discontinuous Galerkin method for elastic-acoustic wave propagation

International audienceWe introduce a time-domain, high-order in space, hybridizable discontinuous Galerkin (DG) spectral element method (HDG-SEM) for wave equations in coupled elastic-acoustic media. The method is based on a first-order hyperbolic velocity-strain formulation of the wave equations written in conservative form. This method follows the HDG approach by introducing a hybrid unknown, which is the approximation of the velocity on the elements boundaries, as the only globally (i.e. interelement) coupled degrees of freedom. In this paper, we first present a hybridized formulation of the exact Riemann solver at the element boundaries, taking into account elastic-elastic, acoustic-acoustic and elastic-acoustic interfaces. We then use this Riemann solver to derive an explicit construction of the HDG stabilization function τ for all the above-mentioned interfaces. We thus obtain an HDG scheme for coupled elastic-acoustic problems. This scheme is then discretized in space on quadrangular/hexahedral meshes using arbitrary high-order polynomial basis for both volumetric and hybrid fields, using an approach similar to the spectral element methods. This leads to a semi-discrete system of algebraic differential equations (ADEs), which thanks to the structure of the global conservativity condition can be reformulated easily as a classical system of first-order ordinary differential equations in time, allowing the use of classical explicit or implicit time integration schemes. When an explicit time scheme is used, the HDG method can be seen as a reformulation of a DG with upwind fluxes. The introduction of the velocity hybrid unknown leads to relatively simple computations at the element boundaries which, in turn, makes the HDG approach competitive with the DG-upwind methods. Extensive numerical results are provided to illustrate and assess the accuracy and convergence properties of this HDG-SEM. The approximate velocity is shown to converge with the optimal order of k + 1 in the L2-norm, when element polynomials of order k are used, and to exhibit the classical spectral convergence of SEM. Additional inexpensive local post-processing in both the elastic and the acoustic case allow to achieve higher convergence orders. The HDG scheme provides a natural framework for coupling classical, continuous Galerkin SEM with HDG-SEM in the same simulation, and it is shown numerically in this paper. As such, the proposed HDG-SEM can combine the efficiency of the continuous SEM with the flexibility of the HDG approaches. Finally, more complex numerical results, inspired from real geophysical applications, are presented to illustrate the capabilities of the method for wave propagation in heterogeneous elastic-acoustic media with complex geometries