A large displacement structural analysis of a pipeline subjected to gravity and bouyancy forces

p. 489-508A nonlinear analysis of an elastic tube subjected to gravity forces and buoyancy pressure is carried out. An update lagrangian formulation is used. The structural analysis efficiency in terms of computer time and accuracy, has been improved when load stiffness matrices have been introduced. In this way the follower forces characteristics such as their intensity and direction changes can be well represented. A sensitivity study of different involved variables on the final deformed pipeline shape is carried out.Mosquera, JC.; Garcia-Palacios, J.; Samartin, A. (2009). A large displacement structural analysis of a pipeline subjected to gravity and bouyancy forces. Editorial Universitat Politècnica de València. http://hdl.handle.net/10251/654

Optimal boundary geometry in an elasticity problem: a systematic adjoint approach

p. 509-524In different problems of Elasticity the definition of the optimal geometry of the boundary, according to a given objective function, is an issue of great interest. Finding the shape of a hole in the middle of a plate subjected to an arbitrary loading such that the stresses along the hole minimizes some functional or the optimal middle curved concrete vault for a tunnel along which a uniform minimum compression are two typical examples. In these two examples the objective functional depends on the geometry of the boundary that can be either a curve (in case of 2D problems) or a surface boundary (in 3D problems). Typically, optimization is achieved by means of an iterative process which requires the computation of gradients of the objective function with respect to design variables. Gradients can by computed in a variety of ways, although adjoint methods either continuous or discrete ones are the more efficient ones when they are applied in different technical branches. In this paper the adjoint continuous method is introduced in a systematic way to this type of problems and an illustrative simple example, namely the finding of an optimal shape tunnel vault immersed in a linearly elastic terrain, is presented.Garcia-Palacios, J.; Castro, C.; Samartin, A. (2009). Optimal boundary geometry in an elasticity problem: a systematic adjoint approach. Editorial Universitat Politècnica de València. http://hdl.handle.net/10251/654

DO BANKING RELATIONSHIPS IMPROVE CREDIT CONDITIONS FOR SPANISH SMES?

Small and medium-sized companies are extremely important for the Spanish economy. However, they face difficulties when trying to obtain financing (credit rationing). As a result, and given their limited possibilities to obtain finance in the capital market, they turn to the credit market, which is the main provider of funds for such companies. The main aim of this study is to provide an insight into the banking relationships that are developed in this market and their impact on credit rationing. Previous literature has studied this situation by focusing on price rationing and quantity rationing. This study furthers research into banking relationships by examining the effects that these relationships may have on compensation demanded for debt and the relationship with long-term credit rationing. After studying 386 SMEs listed in the Spanish Guide of Exporting Companies, the main conclusions drawn were as follows: i) SMEs working with larger numbers of financial entities and with longer relationships with these entities enjoy better access to credit; ii) SMEs that develop banking relationships by contracting financial products manage to reduce their credit costs; iii) SMEs that have longer banking relationships with banking entities benefit from better long-term credit conditions; and iv) the maintenance of banking relationships through the rendering of services reduces bank requirements in terms of guarantees in credit applications.

Financial Intermediaries and Transaction Costs

We present an overlapping generations model with spatial separation and agents who face unsystematic liquidity risk. In a pure exchange economy, agents engage in life cycle portfolio rebalancing. In an intermediated economy, intergenerational banks or mutual funds cater to diversified clienteles so as to avoid rebalancing transactions. In equilibrium, these intermediaries pay redemptions with portfolio income and never sell secondary assets. We also find that the pure exchange economy has a downward sloping yield curve and is inherently cyclical.Financial Intermediation, Overlapping Generations, Liquidity.

Vaporization Interface Propagation Through a One-Dimensional Porous Slab

Mechanical Engineerin

Impacts of changing climate and land use on vegetation dynamics in a Mediterranean ecosystem: insights from paleoecology and dynamic modeling

Forests near the Mediterranean coast have been shaped by millennia of human disturbance. Consequently, ecological studies relying on modern observations or historical records may have difficulty assessing natural vegetation dynamics under current and future climate. We combined a sedimentary pollen record from Lago di Massacciucoli, Tuscany, Italy with simulations from the LandClim dynamic vegetation model to determine what vegetation preceded intense human disturbance, how past changes in vegetation relate to fire and browsing, and the potential of an extinct vegetation type under present climate. We simulated vegetation dynamics near Lago di Massaciucoli for the last 7,000years using a local chironomid-inferred temperature reconstruction with combinations of three fire regimes (small infrequent, large infrequent, small frequent) and three browsing intensities (no browsing, light browsing, and moderate browsing), and compared model output to pollen data. Simulations with low disturbance support pollen-inferred evidence for a mixed forest dominated by Quercus ilex (a Mediterranean species) and Abies alba (a montane species). Whereas pollen data record the collapse of A. alba after 6000calyr bp, simulated populations expanded with declining summer temperatures during the late Holocene. Simulations with increased fire and browsing are consistent with evidence for expansion by deciduous species after A. alba collapsed. According to our combined paleo-environmental and modeling evidence, mixed Q. ilex and A. alba forests remain possible with current climate and limited disturbance, and provide a viable management objective for ecosystems near the Mediterranean coast and in regions that are expected to experience a mediterranean-type climate in the futur

Neural correlates of cognitive dysfunction in fibromyalgia patients: Reduced brain electrical activity during the execution of a cognitive control task

Fibromyalgia (FM) is a generalized chronic pain syndrome of unknown aetiology. Although FM patients frequently complain of cognitive dysfunction, this is one of the least studied symptoms. Research on brain activity associated with the perceived cognitive impairment is particularly scarce. To address this gap, we recorded the brain electrical activity in participants during a cognitive control task.This study was supported by funding from from the Spanish Government (Ministerio de Economia y Competitividad; grant number PSI2013-45818-R] and from the Galician Government (Conselleria de Cultura, Educacion e Ordenacion Universitaria; axudas para a consolidacion e Estruturacion de unidades de investigacion competitivas do Sistema universitario de Galicia; grant number GPC 2014/047). A.G.V. was supported by a grant from Xunta de Galicia (Axudas de apoio a etapa de formacion posdoutoral 2018)