993 research outputs found

    Resultados de los esfuerzos innovadores en Venezuela y Colombia: un etudio comparativo

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    ResumenLas patentes son el resultado de los esfuerzos innovadores. Para entender dicho procesoen Colombia y Venezuela, se plantea compararlas durante el período 1990-2006.Se usan las bases de datos de la Red Iberoamericana de Ciencia y Tecnología y de laOficina de Patentes de los Estados Unidos para obtener la información. Los resultadosindican que: (i) Venezuela supera a Colombia hasta por ocho veces durante el período1990-2006, (ii) el tipo de industria al cual Venezuela dirige sus esfuerzos es el sectorde Química y Metalurgia y Colombia al de Necesidades Humanas, (iii) en ambospaíses las empresas que más innovaciones producen pertenecen al sector público (iv)su alcance en Venezuela es más amplio que en Colombia, y (v) existe desigualdad degénero entre los inventores que patentan en ambos países.Palabras Clave: Patentes, Innovación, AméricaPatentes, Innovación, América Latina.

    A comparative study of small area estimators

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    It is known that direct-survey estimators of small area parameters, calculated with the data from the given small area, often present large mean squared errors because of small sample sizes in the small areas. Model-based estimators borrow strength from other related areas to avoid this problem. How small should domain sample sizes be to recommend the use of model-based estimators? How robust small area estimators are with respect to the rate sample size/number of domains? To give answers or recommendations about the questions above, a Monte Carlo simulation experiment is carried out. In this simulation study, model-based estimators for small areas are compared with some standard design-based estimators. The simulation study starts with the construction of an artificial population data file, imitating a census file of an Statistical Office. A stratified random design is used to draw samples from the artificial population. Small area estimators of the mean of a continuous variable are calculated for all small areas and compared by using different performance measures. The evolution of this performance measures is studied when increasing the number of small areas, which means to decrease their sizes

    Value Chain: From iDMU to Shopfloor Documentation of Aeronautical Assemblies

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    Competition in the aerospace manufacturing companies has led them to continuously improve the efficiency of their processes from the conceptual phase to the start of production and during operation phase, providing services to clients. PLM (Product Lifecycle Management) is an end-to-end business solution which aims to provide an environment of information about the product and related processes available to the whole enterprise throughout the product’s lifecycle. Airbus designs and industrializes aircrafts using Concurrent Engineering methods since decades. The introduction of new PLM methods, procedures and tools, and the need to improve processes efficiency and reduce time-to-market, led Airbus to pursue the Collaborative Engineering method. Processes efficiency is also impacted by the variety of systems existing within Airbus. Interoperability rises as a solution to eliminate inefficiencies due to information exchange and transformations and it also provides a way to discover and reuse existing information. The ARIADNE project (Value chain: from iDMU to shopfloor documentation of aeronautical assemblies) was launched to support the industrialization process of an aerostructure by implementing the industrial Digital Mock-Up (iDMU) concept in a Collaborative Engineering framework. Interoperability becomes an important research workpackage in ARIADNE to exploit and reuse the information contained in the iDMU and to create the shop floor documentation. This paper presents the context, the conceptual approach, the methodology adopted and preliminary results of the project

    Extensions of the parametric families of divergences used in statistical inference

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    summary:We propose a simple method of construction of new families of ϕ\phi%-divergences. This method called convex standardization is applicable to convex and concave functions ψ(t)\psi(t) twice continuously differentiable in a neighborhood of t=1t=1 with nonzero second derivative at the point t=1t=1. Using this method we introduce several extensions of the LeCam, power, % \chi^a and Matusita divergences. The extended families are shown to connect smoothly these divergences with the Kullback divergence or they connect various pairs of these particular divergences themselves. We investigate also the metric properties of divergences from these extended families

    Small area estimation of poverty indicators under partitioned area-level time models

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    This paper deals with small area estimation of poverty indicators. Small area estimators of these quantities are derived from partitioned time-dependent area-level linear mixed models. The introduced models are useful for modelling the different behaviour of the target variable by sex or any other dichotomic characteristic. The mean squared errors are estimated by explicit formulas. An application to data from the Spanish Living Conditions Survey is given

    Small area estimation of poverty indicators under partitioned area-level time models

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    This paper deals with small area estimation of poverty indicators. Small area estimators of these quantities are derived from partitioned time-dependent area-level linear mixed models. The introduced models are useful for modelling the different behaviour of the target variable by sex or any other dichotomic characteristic. The mean squared errors are estimated by explicit formulas. An application to data from the Spanish Living Conditions Survey is given

    Small area estimation of poverty indicators under partitioned area-level time models

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    This paper deals with small area estimation of poverty indicators. Small area estimators of these quantities are derived from partitioned time-dependent area-level linear mixed models. The introduced models are useful for modelling the different behaviour of the target variable by sex or any other dichotomic characteristic. The mean squared errors are estimated by explicit formulas. An application to data from the Spanish Living Conditions Survey is given.Peer Reviewe

    Empirical best prediction under area-level Poisson mixed models

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    [Abstract] The paper studies the applicability of area-level Poisson mixed models to estimate small area counting indicators. Among the available procedures for fitting generalized linear models, the method of moments (MM) and the penalised quasi-likelihood (PQL) method are employed. The empirical best predictor (EBP) of the area mean is derived using MM and compared with plug-in alternatives using MM and PQL. The plug-in estimator using PQL is computationally faster and provides competitive performance with respect to EBP that involves high complex integrals. An approximation to the mean squared error (MSE) of the EBP is given and three MSE estimators are proposed. The first two MSE estimators are plug-in estimators without and with bias correction to the second order and the third one is based on parametric bootstrap. Several simulation experiments are carried out for analysing the behaviour of the EBP and for comparing the estimators of the MSE of the EBP. A good choice in practice is the bootstrap alternative since it performs similarly to the analytical versions and is computationally faster. The developed methodology and software are applied to data from the 2008 Spanish living condition survey. The target of the application is the estimation of poverty rates at province level.Xunta de Galicia; CN2012/130Ministerio de Ciencia e Innovación; MTM2013-41383-PMinisterio de Ciencia e Innovación; MTM2014-52876-RMinisterio de Ciencia e Innovación; MTM2011-22392Ministerio de Ciencia e Innovación; MTM2008-03010Ministerio de Ciencia e Innovación; MTM2012-37077-C02-0

    On the study of the single-stage hole-flanging process by SPIF

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    Recent studies show the capability of single-point incremental forming to perform successfully hole-flanging operations using multi-stage strategies. The aim of this work is to investigate the ability of the SPIF process to perform hole-flanges in a single stage, contributing to a better understanding of the formability of the sheet in this demanding situation. To this end, a series of experimental tests in AA7075-O metal sheets are performed in order to evaluate the limiting forming ratio. The physical mechanisms controlling sheet failure during the process are analyzed and discussed. In the test conditions studied this failure is postponed necking followed by ductile fracture in the wall of the flange.Ministerio de Economía y Competitividad DPI2012-3291
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