Search results for "Abstract data type"
showing 10 items of 1140 documents
On the use of a metric-space search algorithm (AESA) for fast DTW-based recognition of isolated words
1988
The approximating and eliminating search algorithm (AESA) presented was recently introduced for finding nearest neighbors in metric spaces. Although the AESA was originally developed for reducing the time complexity of dynamic time-warping isolated word recognition (DTW-IWR), only rather limited experiments had been previously carried out to check its performance in this task. A set of experiments aimed at filling this gap is reported. The main results show that the important features reflected in previous simulation experiments are also true for real speech samples. With single-speaker dictionaries of up to 200 words, and for most of the different speech parameterizations, local metrics, a…
Regression with imputed covariates: A generalized missing-indicator approach
2011
A common problem in applied regression analysis is that covariate values may be missing for some observations but imputed values may be available. This situation generates a trade-off between bias and precision: the complete cases are often disarmingly few, but replacing the missing observations with the imputed values to gain precision may lead to bias. In this paper, we formalize this trade-off by showing that one can augment the regression model with a set of auxiliary variables so as to obtain, under weak assumptions about the imputations, the same unbiased estimator of the parameters of interest as complete-case analysis. Given this augmented model, the bias-precision trade-off may the…
Strategic sharing of a costly network
2012
We study minimum cost spanning tree problems for a set of users connected to a source. Prim’s algorithm provides a way of finding the minimum cost tree mm. This has led to several definitions in the literature, regarding how to distribute the cost. These rules propose different cost allocations, which can be understood as compensations and/or payments between players, with respect to the status quo point: each user pays for the connection she uses to be linked to the source. In this paper we analyze the rationale behind a distribution of the minimum cost by defining an a priori transfer structure. Our first result states the existence of a transfer structure such that no user is willing to …
Empirical definition of social types in the analysis of inequality of opportunity: a latent classes approach
2014
The empirical analysis of inequality of opportunity centres on disparities between social types, defined by the exposure to circumstances beyond individual control. Despite this, its main theoretical foundation—the Roemer model—does not indicate how to carry out, in practice, the required partition of the population into such types. This paper operationalises this definition of social types using a latent classes approach. Our specification is embedded in a probabilistic extension of the canonical Roemer model, which assumes that the relevant population consists of a finite number of latent types, from which each individual can be treated as a random draw. This makes possible the use of the…
Stochastic monotonicity in intergenerational mobility tables
2010
SUMMARY The aim of this paper is to test for stochastic monotonicity in intergenerational socio-economic mobility tables. In other words, we question whether having a parent from a high socio-economic status is never worse than having one with a lower status. Using existing inferential procedures for testing unconditional stochastic monotonicity, we first test a set of 149 intergenerational mobility tables in 35 different countries and find that monotonicity cannot be rejected in hardly any table. In addition, we propose new testing procedures for testing conditional stochastic monotonicity and investigate whether monotonicity still holds after conditioning on a number of covariates such as…
Efficient Graph Models for Retrieving Top-k News Feeds from Ego Networks
2012
A key challenge of web platforms like social networking sites and services for news feed aggregation is the efficient and targeted distribution of new content items to users. This can be formulated as the problem of retrieving the top-k news items out of the d-degree ego network of each given user, where the set of all users producing feeds is of size n, with n >> d >> k and typically k
A Contribution to Tests Standardization for Inverter-Fed Asynchronous Machines
1986
Losses of inverter-fed asynchronous motors and their experimental evaluation are considered. The formal expressions of iron and copper losses are first recalled, and it is shown as they are influenced by the harmonic content of inverter output voltages. Theoretical and experimental values of these losses are then given together with the presentation of the experimental tests used for their determination. A suitable set of tests is then suggested for the determination of the conventional efficiency of inverter-fed asynchronous motors. The content cannot be considered exhaustive on the matter. It represents only a first contributive approach to the standardization of inverter-fed asynchronous…
Eco-sustainable energy and environmental strategies in design for recycling: the software “ENDLESS”
2003
Abstract This paper describes a model, named “ENDLESS”, useful to address the design process towards more eco-compatible solutions. In particular, this tool can support the designer in the choice of the product with an higher recyclability potential from a set of different alternatives. The model takes into consideration a Multi-Attribute Decision-Making method and allows calculating a “Global Recycling Index” (GRI) starting from a set of energy, environmental, technical and economic indicators. A weight is assigned to each parameter following the experience of the designer; a sensitivity analysis is then performed to state how the different assumptions can affect the final results. The mod…
Performance comparison of mono-polar and bi-polar configurations of alkaline electrolysis stack through 3-D modelling and experimental fabrication
2020
Abstract Generation of hydrogen using electrolysis process with integrated renewable energy sources is highly important especially in environmental aspects. In this paper, we demonstrate that the enhancement of electrolysis performance of alkaline electrolysis stacks by diminishing the distance between electrodes, while changing the properties of the Membrane Electrode Assembly (MEA). Prior to that, the performances of mono-polar and bi-polar configurations of alkaline electrolysis stack are compared through 3-D modelling and experimental fabrication. At first, two different single cell alkaline electrolysers are designed using SolidWorks as a design software and the designed cell has been …
Approximation of Pore Space with Ellipsoids: A Comparison of a Geometrical Method with a Statistical one
2018
We work with tomographic images of pore space in soil. The images have large dimensions and so in order to speed-up biological simulations (as drainage or diffusion process in soil), we want to describe the pore space with a number of geometrical primitives significantly smaller than the number of voxels in pore space. In this paper, we use the curve skeleton of a volume to segment it into some regions. We describe the method to compute the curve skeleton and to segment it with a simple segment approximation. We approximate each obtained region with an ellipsoid. The set of final ellipsoids represents the geometry of pore space and will be used in future simulations. We compare this method …