Effects of finite strains in fully coupled 3D geomechanical simulations

Numerical modeling of geomechanical phenomena and geo-engineering problems often involves complex issues related to several variables and corresponding coupling effects. Under certain circumstances, both soil and rock may experience a nonlinear material response caused by, for example, plastic, viscous, or damage behavior or even a nonlinear geometric response due to large deformations or displacements of the solid. Furthermore, the presence of one or more fluids (water, oil, gas, etc.) within the skeleton must be taken into account when evaluating the interaction between the different phases of the continuum body. A multiphase three-dimensional (3D) coupled model of finite strains, suitable for dealing with solid-displacement and fluid-diffusion problems, is described for assumed elastoplastic behavior of the solid phase. Particularly, a 3D mixed finite element was implemented to fulfill stability requirements of the adopted formulation, and a permeability tensor dependent on deformation is introduced. A consolidation scenario induced by silo filling was investigated, and the effects of the adoption of finite strains are discusse

Acasalar bovinos de corte no outono: sim ou não?

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Piano di riqualificazione dell'area di ingresso ovest alla città di Cascina

Il progetto di tesi si svolge su tre diversi livelli: abbiamo una progettazione a livello urbanistico, che riguarda il riassetto dell’area attualmente adibita a produzione di legname per l’edilizia “Bulleri”, in stato di degrado e per la quale è previsto un cambiamento di destinazione d’uso (da produttiva a residenziale-direzionale-commerciale). Abbiamo poi una progettazione a livello infrastrutturale, con la riqualificazione della via Tosco Romagnola nel tratto che va dalla via provinciale Cucigliana-Lorenzana alla frazione di Sant’Anna, la realizzazione di una rotatoria, con due nuovi rami di collegamento (uno verso il Teatro Politeama e l’altro verso la via provinciale Cucigliana-Lorenzana) posta sull’attuale tracciato della via Tosco Romagnola in corrispondenza dell’area di progetto ed infine la realizzazione di nuovi parcheggi con un nuovo ramo di strada che collegherà la via Tosco Romagnola con il tratto terminale della via Sant’Isidoro, per costituire un accesso carrabile all’area di progetto, in posizione collaterale. Infine abbiamo una progettazione a livello architettonico, con la realizzazione di un polo polifunzionale, costituito da un hotel, un ristorante, due esercizi commerciali, un music pub, residenze, uffici, una sala espositiva per i lavori realizzati dagli studenti del vicino Liceo Artistico e, infine, un edificio per laboratorio e piccole rappresentazioni teatrali, in collegamento con le attività del vicino Teatro Politeama, come richiesto dalla normativa di livello comunale (N.T.A. del Comune di Cascina)

Modelo prático para desmamar terneiros precocemente.

Com o objetivo de minimizar o efeito ocasionado pelo desmame abrupto, com as conseqüências ocasionadas pela troca de alimentação, foram avaliadas de forma que a prática de desmamar terneiros precocemente viesse a ser introduzida nas propriedades rurais como uma rotina de manejo.bitstream/item/55799/1/CO66.pd

Experimental muscle pain increases normalized variability of multidirectional forces during isometric contractions

Pain elicits complex adaptations of motor strategy, leading to impairments in the generation and control of steady forces, which depend on muscle architecture. The present study used a cross-over design to assess the effects of muscle pain on the stability of multidirectional (taskrelated and tangential) forces during sustained dorsiflexions, elbow flexions, knee extensions, and plantarflexions. Fifteen healthy subjects performed series of isometric contractions (13-s duration, 2.5, 20, 50, 70% of maximal voluntary force) before, during, and after experimental muscle pain. Three-dimensional force magnitude, angle and variability were measured while the task-related force was provided as feedback to the subjects. Surface electromyography was recorded from agonist and antagonist muscles. Pain was induced in agonist muscles by intramuscular injections of hypertonic (6%) saline with isotonic (0.9%) saline injections as control. The pain intensity was assessed on an electronic visual analogue scale. Experimental muscle pain elicited larger ranges of force angle during knee extensions and plantarflexions (P < 0.03) and higher normalized fluctuations of task-related (P < 0.02) and tangential forces (P < 0.03) compared with control assessments across force levels, while the mean force magnitudes, mean force angle and the level of muscle activity were non-significantly affected by pain. Increased multidirectional force fluctuations probably resulted from multiple mechanisms that, acting together, balanced the mean surface electromyography. Although pain adaptations are believed to aim at the protection of the painful site, the current results show that they result in impairments in steadiness of force

3D modelling of geomaterials accounting for an unconventional plasticity approach

The coupled hydro-mechanical state in geomaterials undergoing plasticity phenomena is here evaluated by means of the subloading surface model . The most important feature of this theory is the abolition of the distinction between the elastic and plastic domain, as it happens in conventional elastoplastic models. This means that plastic deformations are generated whenever there is a change in stress and a smoother elasto-plastic transition is produced. The subloading surface takes the role of a loading surface which always passes through the current stress point σ and keeps a shape similar to that of the normal yield surface and a similar orientation with respect to the origin of stress space. Additionally, the model allows for giving a smooth response in a smooth monotonic loading process and the stress is automatically drawn back to the normal-yield surface even if it goes out from that surface, leading to a more stable and robust calculation even for large loading steps. The plasticity algorithm has been implemented within the FE PLASCON3D research code, coupling hydro-(thermo)-mechanical fields within a saturated porous medium (locally partially saturated) subjected to external loads. Applications to soils allow e.g. for assessing subsidence evolution at regional scale

Anti-HIV drugs and the mitochondria

AbstractSeveral drugs are currently used that can significantly prolong the course of the infection with the human immunodeficiency virus (HIV), the cause of the acquired immunodeficiency syndrome (AIDS). Among these drugs, the nucleosidic inhibitors of viral reverse transcriptase can alter mitochondrial (mt) function by inhibiting the mitochondrial DNA polymerase gamma (the enzyme responsible for the replication of mtDNA). Decreased mtDNA content provokes a diminished synthesis of respiratory chain enzymes, leading to alterations in mt function. These are in turn responsible for a variety of side effects frequently observed in HIV+ patients, that range from hyperlactatemia and lactic acidosis to lipodystrophy, a pathology characterized by accumulation of visceral fat, breast adiposity, cervical fat-pads, hyperlipidemia, insulin resistance and fat wasting in face and limbs. In this paper, data concerning the effects of different compounds on mitochondria, their role in the pathogenesis of lipodystrophy, and problems related to studies on the mt toxicity of antiviral drugs are reviewed and thoroughly discussed

Very short course of triple therapy including telaprevir for chronic hepatitis C: a possible strategy in selected patients

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Finite strains fully coupled analysis of a horizontal wellbore drilled through a porous rock formation

Wellbore instability, in particular in deep perforations, continues to be one of the major problem in the oil and gas industry, that can dramatically increase production costs. Eventual instabilities may be prevented supporting temporarily the wellbore with mud circulation. If instability may occur, the value of the mud pressure needs to be sufficiently high to prevent compressional failure, but it should also be lower than a critical value that would cause tensile failure and unintentional hydraulic fracturing. Predicting faithfully the stress distribution around a borehole, and moreover the yielding and failure zones, is a challenging but fundamental task, essential to estimate the correct mud pressure and hence to prevent instabilities and sand production. This study focuses on quantifying the pressure distribution, stress field and plastic zones around a horizontal borehole drilled at great depth through a highly porous rock formation. The perforation of a wellbore in a saturated porous material is a coupled problem, which involves deformations of the solid phase and simultaneous diffusion of the fluid phase. A fully coupled finite element method is adopted, considering both material non linearity (elastoplasticity) and geometric nonlinearity (finite deformations) in the solid matrix, resulting in a so called u−p formulation. The variation of porosity and permeability, as consequence of the finite deformations of the solid matrix, is taken into account. The model adopts an elastoplastic constitutive law characterized by two yield surfaces, that is able to capture the dilatant and compactant plastic mechanism. The simulations investigate the quasi-static transient phenomenon associated with the perforation, until the steady state condition is reached. The model describes the evolution of the stress and pressure distribution, and moreover the propagation of the plastic zones around the borehole. The work demonstrates the capability of the finite deformations coupled approach to simulate the whole process, giving an instrument to determine the stability and sand production of the wellbore

Measuring performances of linux hypervisors

Virtualization is a now proven software technology that is rapidly transforming the IT landscape and fundamentally changing the way people make computations and implement services. Recently, all major software producers (e.g., Microsoft and RedHat) developed or acquired virtualization technologies. Our institute (http://www.cnaf.infn.it) is a Tier1 for experiments carried on at the Large Hadron Collider at CERN (http://lhc.web.cern.ch/lhc/) and is experiencing several benefits from virtualization technologies, like improving fault tolerance, providing efficient hardware resource usage and increasing security. Currently, the virtualization solution we adopted is xen, which is well supported by the Scientific Linux distribution, widely used by the High-Energy Physics (HEP) community. Since Scientific Linux is based on RedHat ES, we felt the need to investigate performances and usability differences with the new kvm technology, recently acquired by RedHat. The case study of this work is the Tier2 site for the LHCb experiment hosted at our institute; all major grid elements for this Tier2 run on xen virtual machines smoothly. We will investigate the impact on performance and stability that a migration to kvm would entail on the Tier2 site, as well as the effort required by a system administrator to deploy the migration