Determinants of working capital management

This paper analyzes the determinants of working capital management (WCM) for a sample of Spanish firms during the period 1997-2004. We find that firms have a target investment in working capital and that they take decisions in order to achieve this. The results appear to support the hypothesis that the working capital competes with investment in fixed assets for the funds of the firms when they have financial constraints. Finally, we also find that WCM depends on bargaining power and other financial factors such as the availability of internal finance, cost of financing and financial constraints.Research Agency of the Spanish Government ECO2008-06179/ECO

New trends in education: the use of ICT in different ways

In the 21st century and due to the exponential growth of the Internet and Information and Communication Technologies (ICT), people live in a technological age, in all areas and in all contexts, we have daily contact with technology, with access to Information. This dynamic requires a constant update of the services and technological tools that change the method that we study, work, communicate and socialize on an unprecedented scale. These constant changes force everyone, regardless of age, gender or profession, to possess a range of functional and critical thinking skills, such as information literacy, media literacy and technological literacy. The evolution of technologies, forces the promoters of education, to always be aware of the changes that society is introducing outside the classroom. Today, students don't have the same pattern as before, regardless of age, they are very active and are no longer the same introverted child who studied a few years ago in the classroom. According to this, students are eager for different forms of motivation inside and outside the classroom, they need the learning and teaching process to move along with changes in society and ICT. To ensure the success of today's students, it is important to provide them with the technological skills to make the correct use of ICTs, to perform tasks essential to their learning process, such as researching and selecting information, creating content, information sharing, use of collaboration tools or environment simulation tools. The main objective of this chapter is to show how ICT tools that can be used in educational environments to help students, helping them develop key skills in their training process, is also relevant to show how these tools can help teachers achieve these goals in daily activities with their students

Simulation of gelled propellant doughs isothermal flow through extrusion dies using finite difference method

During the ram extrusion of gelled propellants, the possible flow instabilities can affect the extruded propellant quality. The numerical modelling helps to enhance the geometry of extrusion die, by minimizing the product distortion caused by material flow during this forming process. In the present work, a numerical model based on the finite difference method is proposed to analyze the flow simulation of double-base gelled propellant doughs through annular channels of extrusion dies. The proposed model implements the pseudo-plastic behavior described by these energetic materials. This model will be used to deduce the configuration of spider legs and annular channels that allow optimize the quality of extruded gelled propellant.The researchers acknowledge to the Spanish Ministry of Economy and Competitiveness and the European Commission their support throughout the ERDF (European Regional Development Fund) by the INNPACTO research project “Smart Propellants” (IPT-2011-0712-020000), involving EXPAL Systems S.A. and Universidad Politecnica de Cartagena (UPCT)

Changes in blood pesticide levels in booted eagle (Hieraaetus pennatus) associated with agricultural land practices

©2008 Elsevier Inc. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/ This document is the Published version of a Published Work that appeared in final form in "Ecotoxicology and Environmental Safety". To access the final edited and published work see https://doi.org/10.1016/j.ecoenv.2008.02.012We estimated the degree of exposure to lindane and endosulfan in the blood of booted eagle nestlings (Hieraaetus pennatus) (1999–2003), in order to assess the usefulness of these samples as a unit for monitoring changes in exposure as a result of shifts in agricultural practices and the implementation of legal measures. The highest blood lindane concentrations were obtained 1 year prior to its prohibition by the European Union. Subsequent to that year, the drop in blood concentrations was dramatic. Furthermore, endosulfan blood concentrations follow a progression coinciding with an increase in olive, grape and plum-tree crops. We conclude that concentrations of organochlorine pesticides in the blood of booted eagle nestlings may be used to monitor the use of those pesticides over a particular agricultural region and alert the authorities of possible environmental or health risks

Absorptive capacity from foreign direct investment in Spanish manufacturing firms

This paper deals with the determinants of absorptive capacity from foreign direct investment (FDI) spillovers. We study how firm behavior, capabilities, and structure drive absorptive capacity such as research and development (R&D) activities and expenditures, R&D results, internal organization of innovation, external relationships of innovation, human-capital quality, family management, business complexity, and market concentration. Our results enhance and complement previous evidence of the determinants of absorptive capacity, particularly with different approaches to innovative activities as mediators of the capability

Influence of the ICFF decoupling technique on the stability of the current control loop of a grid-tied VSC

© 2019 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes,creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.The control scheme of grid-tied converters is often implemented in the dq-frame due to simplicity of design. However, with this transformation, there exists an inherent cross-coupling term between the d-and q-channels which is often compensated for by using a feed-forward term in the current-control loop. It is shown, by applying the generalized Nyquist criterion (GNC) to the dq-frame ac impedance of the converter, that the inclusion of this decoupling term, in fact, degrades the stability of the controller when increasing the bandwidth of the synchronous reference frame phase-locked loop (SRF-PLL). Harware-in-the-loop (HIL) experiments are also conducted and verify these results.Peer ReviewedPostprint (author's final draft

Synchronous frequency support of photovoltaic power plants with inertia emulation

©2019 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.Grid stability is one of the main concerns in renewable energies. The lack of inertia and their low capability to provide frequency support has created the need for implementing new control strategies to solve this problem. In current networks, frequency and voltage support are performed through synchronous generators, which provide an inherent grid support due to the inertia presented in their mechanical rotors. Based on the same concept, renewable energies based on power converters have introduced synchronous controllers to emulate the dynamic behavior of synchronous generators and provide voltage and frequency support. However, most synchronous control strategies integrate their controllers as an add-on firmware embedded in each power converter, without presenting a coordinated synchronous performance when several converters operate in a PV power plant. The aggregation of several power converters operating with a coordinated synchronous response would be advantageous in these cases, since they can provide a harmonic response with an automatic power distribution when grid support is required. This paper presents a synchronous control strategy for photovoltaic power plants, which manages several power converters as an aggregated synchronous system.Peer ReviewedPostprint (author's final draft

The Use of Orthogonal Grids in the Design of US Military Bases in Spain

At the beginning of the Cold War, the United States established military bases at various points around the globe to counter Soviet influence. The construction of these bases was an unprecedented undertaking because its scope. In Spain, an extensive network of military installations was built throughout the country in only 5 years. The main nuclei of this network were the bases of Torrejón, Zaragoza, Morón, and Rota. This article aims to show that these bases share a common design project which implements an underlying grid-like system in the organization of their masterplans. After detailed study of the Torrejón air base, we aim to demonstrate that this grid-like system was conceived as a sophisticated and precise graphic tool able to facilitate the design, construction, and maintenance of the bases, as well as to back an ideological project

Una simplificación del método de Laplace y aplicaciones

Multitud de funciones especiales de la física aparecen en problemas de mecánica cuántica como solución de ciertas ecuaciones diferenciales. Muchas de estas funciones admiten una representación integral de la forma F(x) ≡ Z b a e −x f(t) g(t) dt, donde x representa alg´un parámetro físico de la teoría en consideración. La evaluación de estas integrales no resulta sencilla en general, pero en muchas ocasiones, ese parámetro x toma valores elevados. Por ello, resulta interesante disponer de métodos de evaluación aproximada de este tipo de integrales para valores grandes de la variable x. El método más utilizado es el de Laplace. La principal dificultad en dicho método para la obtenci´on de desarrollos asintóticos de este tipo de integrales la origina un cambio de variable. Para suavizar esto, proponemos una factorización del integrando que evita dicho cambio de variable, simplificando enormemente las operaciones. Por un lado, el cálculo de los coeficientes del desarrollo asintótico es muy sencillo. Por otro lado, la secuencia asintótica obtenida con nuestro método es tan sencilla como en el método estándar de Laplace: funciones gamma completas o incompletas. Además, obtenemos una fórmula explícita para los coeficientes de dicho desarrollo, a diferencia de lo que sucede en el método de Laplace, donde rara vez es posible obtener fórmulas explícitas. Más todavía, mediante una reagrupación de términos podemos obtener fórmulas explícitas para los coeficientes del desarrollo de Laplace estándar