Search results for "Linea"
showing 10 items of 7724 documents
Min-Type Control Strategy of a DC-DC Synchronous Boost Converter
2019
International audience; This paper presents the analysis and design of a min-type strategy to control a synchronous boost converter in continuous conduction mode. The strategy uses a nonlinear switching surface to establish the change of topology in the converter and is analyzed by means of a sliding-mode control approach. Subsequently, the min-type strategy is modified by a hybrid control formulation, which introduces a hysteresis width and a dwell-time to obtain a finite switching frequency in the start-up and steady-state respectively. The hybrid control formulation is implemented digitally by means of a microprocessor which processes the samples of inductor current and capacitor voltage…
Curs d'Econometria: part teòrica
2015
El document conté les transparències usades per il·lustrar i complementar les classes teòriques de l'assignatura Econometria, codi 35.820, que s'imparteix en el Grau d'Administració i Direcció d'Empreses de la Universitat de València. És un curs d'introducció a l'Econometria amb sis unitats temàtiques: 1) Models economètrics i dades econòmiques 2) El model de regressió 3) Propietats i hipòtesis en el model de regressió 4) Contrastament de hipòtesis en el model de regressió múltiple 5) Anàlisi de regressió múltiple amb informació qualitativa 6) Incompliment de les hipòtesis bàsiques
Modelización y resolución de problemas de optimización en economía
2000
La programación matemática es la parte de las matemáticas que se encarga de la elección de la mejor alternativa de entre todas las posibles. El presente texto pretende ser una herramienta para facilitar una formulación matemática adecuada a cada problema económico de optimización, así como servir de guía para interpretar correctamente los resultados que puedan obtenerse mediante un sistema de apoyo a la toma de decisiones mediante ordenador. Los problemas que en este texto se recogen son fundamentalmente de programación matemática, es decir, en su mayoría son problemas estáticos, deterministas, con un solo sujeto decisor y una sola función objetivo. Se advierte, pues, al lector que no esper…
Design and realization of a DC/DC converter with a partially saturated inductor
2017
DC/DC converters, in some types of applications such as portable equipments, can require more space than it is actually available. The inductor is typically the most bulky element and the possibility to reduce its size can save up to 50% of the converter volume and area [1][2], thus increasing the power density. This reduction, however, comes with nonlinear effects caused by the saturation of the ferromagnetic core. An appropriate modelling of the inductor and of the converter circuit is needed for guaranteeing a good output power quality (Fig. 1). A Boost converter with an inductor in the partially saturated roll-off operating zone was designed and realized to study the behaviour of DC/DC …
Non-Linear Inductor Models Comparison for Switched-Mode Power Supplies Applications
2022
The use of non-linear power inductors, intended as devices exploited up to a current at which the inductance is halved, is of great interest in switched-mode power supplies (SMPSs). Indeed, it allows the use of lighter and cheaper inductors improving the power density. On the other hand, the analysis of SMPSs equipped with non-linear inductors requires appropriate modeling of the inductor reproducing the inductance versus current. This paper compares two main analytical models proposed in the literature: the former is based on a polynomial, and the latter exploits the arctangent function to reproduce the non-linearity of the inductance. Performance is compared by considering the effort of r…
El mito aéreo en el futurismo italiano:del periodo heroico a la espiritualidad aérea (1909-1944) The aerial myth of Itanian futurism: from the heroic…
2021
La poética de lo aéreo atravesó transversalmente la historia del futurismo italiano. El undécimo punto de su manifiesto y fundación en 1909, hizo referencia al aeroplano como una máquina esencial para comprender que la vida y el arte se debían someter a un mundo en permanente transformación. Lo aéreo y sus implicaciones compusieron proclamas y manifiestos determinando la creación literaria y artística del periodo heroico. En los años treinta, cuando el futurismo planteaba su supervivencia en el complejo contexto social y político italiano, la aeropintura se convirtió en su línea oficial. Un perfil que, desde ese mismo momento, se bifurcó en dos tendencias complementarias: la dedicada a una …
Lubāna ledus loba veidotās reljefa formas Jersikas līdzenumā
2022
Šulcs. R., 2022. Lubāna ledus loba veidotās reljefa formas Jersikas līdzenumā. Rīga, Latvijas Universitāte, 53 lpp. Bakalaura darbā tika pētītas Jersikas līdzenumā sastopamās ledāja reljefa formas. Darba mērķis ir identificēt un raksturot Lubāna ledus loba veidoto reljefa formu izvietojumu, morfoloģiju, iekšējo uzbūvi, ģenēzi un saprast to saistību ar ledus loba uzvirzīšanās un atkāpšanās gaitu. Ledāja reljefa formas tika identificētas un nokartētas, izmantojot augstas izšķirtspējas digitālo reljefa modeli. Lauka darbos tika pētīti teritorijā esošie atsegumi un veikti urbumi ledāja veidotajās reljefa formās. Pētījumā iegūtie rezultāti ļauj interpretēt Lubāna ledus loba dinamiku un zemledāja…
Shape optimization in contact problems based on penalization of the state inequality
1986
The paper deals with the approximation of optimal shape of elastic bodies, unilaterally supported by a rigid, frictionless foundation. Original state inequality, describing the behaviour of such a body is replaced by a family of penalized state problems. The relation between optimal shapes for the original state inequality and those for penalized state equations is established. peerReviewed
Application of Molecular Topology for the Prediction of Reaction Yields and Anti-Inflammatory Activity of Heterocyclic Amidine Derivatives
2011
Topological-mathematical models based on multiple linear regression analyses have been built to predict the reaction yields and the anti-inflammatory activity of a set of heterocylic amidine derivatives, synthesized under environmental friendly conditions, using microwave irradiation. Two models with three variables each were selected. The models were validated by cross-validation and randomization tests. The final outcome demonstrates a good agreement between the predicted and experimental results, confirming the robustness of the method. These models also enabled the screening of virtual libraries for new amidine derivatives predicted to show higher values of reaction yields and anti-infl…
Study on the Correlation Between Working Capital and Economic Value Added for the Companies Relating to the Hotel and Restaurant Industry Listed on t…
2020
In the present study was determined the influence of the value change of the working capital on the variation of the economic value added indicator on a sample consisting of a number of 26 companies (2007-2017) belonging to the hotel and restaurant industry, listed on the Bucharest Stock Exchange. The correlation between the indicators was achieved by using the multiple linear regression method. The study showed that there is a strong link between the two economic indicators, over 80% of the change in economic value being explained by the change in working capital. It was found that a 1% increase in working capital, for the period 2007-2017, had the effect of increasing the economic value a…