3,713 research outputs found
Distribution functions for a family of axially symmetric galaxy models
We present the derivation of distribution functions for the first four
members of a family of disks, previously obtained in (MNRAS, 371, 1873, 2006),
which represent a family of axially symmetric galaxy models with finite radius
and well behaved surface mass density. In order to do this we employ several
approaches that have been developed starting from the potential-density pair
and, essentially using the method introduced by Kalnajs (Ap. J., 205, 751,
1976) we obtain some distribution functions that depend on the Jacobi integral.
Now, as this method demands that the mass density can be properly expressed as
a function of the gravitational potential, we can do this only for the first
four discs of the family. We also find another kind of distribution functions
by starting with the even part of the previous distribution functions and using
the maximum entropy principle in order to find the odd part and so a new
distribution function, as it was pointed out by Dejonghe (Phys. Rep., 133, 217,
1986). The result is a wide variety of equilibrium states corresponding to
several self-consistent finite flat galaxy models.Comment: 12 pages, 7 figures, updated version, accepted for publication in
Rev. Acad. Colomb. Cienc. Ex. Fis. Na
A Bayesian Solution to the Behrens-Fisher problem
A simple solution to the Behrens–Fisher problem based on Bayes factors is presented, and its relation with the Behrens–Fisher distribution is explored. The construction of the Bayes factor is based on a simple hierarchical model, and has a closed form based on the densities of general Behrens–Fisher distributions. Simple asymptotic approximations of the Bayes factor, which are functions of the Kullback–Leibler divergence between normal distributions, are given, and it is also proved to be consistent. Some examples and comparisons are also presented.Open access funding provided by Universidad de Málaga/CBUA
The architectural culture of the Eurasian Mediterranean region: a testimony of satisfactory design for urban infrastructures (May 2014)
The purpose of this paper is to expose the importance of observing cultural systems present in a territory as a reference for the design of urban infrastructures in the new cities and regions of rapid development. If we accept the idea that architecture is an instrument or cultural system developed by man to act as an intermediary to the environment, it is necessary to understand the elemental interaction between man and his environment to meet a satisfactory design.To illustrate this purpose, we present the case of the Eurasian Mediterranean region, where the architectural culture acts as a cultural system of adaptation to the environment and it is formed by an ancient process of selection. From simple observation of architectural types, construction systems and environmental mechanisms treasured in mediterranean historical heritage we can extract crucial information about this elemental interaction.Mediterranean architectural culture has environmental mechanisms responding to the needs of basics habitability, ethnics and passive conditioning. These mechanisms can be basis of an innovative design without compromising the diversity and lifestyles of human groups in the region. The main fundament of our investigation is the determination of the historical heritage of domestic architecture as holder of the formation process of these mechanisms.The result allows us to affirm that the successful introduction of new urban infrastructures in an area need a reliable reference and it must be a cultural system that entailing in essence the environmental conditioning of human existence. The urban infrastructures must be sustainable, understood and accepted by the inhabitants. The last condition is more important when the urban infrastructures are implemented in areas that are developing rapidly or when there is no architectural culture
A bayesian approach for one-way ANOVA under unequal variances
In this report a Bayesian solution to the problem of testing the equality of the means of k independent normal populations with unknown and arbitrary variances is provided. An important issue in the solution of this problem is the determination of groups with equal means, often solved by multiple comparisons, which can lead to results that are difficult to interpret. In order to avoid this drawback, we propose to treat all possible alternatives existing in the alternative hypothesis by considering the set of all possible configurations of the set of k means. This idea is closely related to the statistical pro-blem of cluster analysis. This allows us to reformulate the testing problem in terms of model selection. A hierarchical model is proposed to compute the Bayes factor of all models, as well as the posterior probability of all the possible configurations. Some illustrative examples of the goodness of the proposed solution are presented.Universidad de Málaga. Campus de Excelencia Internacional AndalucĂa Tech
Does the Pulvinar-Lp Complex Contribute to Motor Programming?
[Abstract] Extracellular unit recording studies in the pulvinar lateral posterior complex (Pui-LP) of behaving monkeys have shown a response property not previously reported. In monkeys performing aimed arm reaching movements towards frontally located targets some cells showed a change in activity beginning 495 ± 84 ms before the onset of the reaching movement. This change in frequency precedes that observed in primary motor and parietal posterior cortex for reaching movements. These findings seem to indicate the involvement of the Pul-LP in motor functions and suggest its possible contribution to motor programming.Comisión Asesora de Investigacion Cientifica y Tecnica (España); PR83-210
Optimal energy management for a residential microgrid including a vehicle-to-grid system
An optimization model is proposed to manage a
residential microgrid including a charging spot with a vehicle-togrid
system and renewable energy sources. In order to achieve a
realistic and convenient management, we take into account: (1)
the household load split into three different profiles depending
on the characteristics of the elements considered; (2) a realistic
approach to owner behavior by introducing the novel concept of
range anxiety; (3) the vehicle battery management considering
the mobility profile of the owner and (4) different domestic
renewable energy sources. We consider the microgrid operated
in grid-connected mode. The model is executed one-day-ahead
and generates a schedule for all components of the microgrid.
The results obtained show daily costs in the range of 2.82eto
3.33e; the proximity of these values to the actual energy costs
for Spanish households validate the modeling. The experimental
results of applying the designed managing strategies show daily
costs savings of nearly 10%.Postprint (author’s final draft
A new clustering algorithm applying a hierarchical method neural network.
[EN]Clustering is a branch of multivariate analysis that is used to create groups of data. Most of the existing clustering techniques require defining additional information, including the actual number of clusters, before they can be carried out. This article presents a novel neural network that is capable of creating groups by using a combination of hierarchical clustering and self-organizing maps, without requiring the number of existing clusters to be specified beforehand. The self-organized cluster automatic detection neural network is described in detail, focusing on the density, the average distance, the division algorithm, the update algorithm and the training phase. Three case studies have been carried out in this research in order to evaluate the performance of the neural network, and the results obtained are presented within this article
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