A comparison of discriminant logistic regression and Item Response Theory Likelihood-Ratio Tests for Differential Item Functioning (IRTLRDIF) in polytomous short tests

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A Homogeneous Set-Theoretical Frame for Clustering Fuzzy Relational Data

Our purpose is to provide a set-theoretical frame to clustering fuzzy relational data basically based on cardinality of the fuzzy subsets that represent objects and their complementaries, without applying any crisp property. From this perspective we define a family of fuzzy similarity indexes which includes a set of fuzzy indexes introduced by Tolias et al, and we analyze under which conditions it is defined a fuzzy proximity relation. Following an original idea due to S. Miyamoto we evaluate the similarity between objects and features by means the same mathematical procedure. Joining these concepts and methods we establish an algorithm to clustering fuzzy relational data. Finally, we present an example to make clear all the process

Effective atomic orbitals for fuzzy atoms

The method of extracting effective atomic orbitals and effective minimal basis sets from molecular wave function characterizing the state of an atom in a molecule is developed in the framework of the "fuzzy" atoms. In all cases studied, there were as many effective orbitals that have considerable occupation numbers as orbitals in the classical minimal basis. That is considered to be of high conceptual importance

Energy partitioning for "fuzzy" atoms

The total energy of molecule in terms of 'fuzzy atoms' presented as sum of one- and two-atomic energy components is described. The divisions of three-dimensional physical space into atomic regions exhibit continuous transition from one to another. The energy components are on chemical energy scale according to proper definitions. The Becke's integration scheme and weight function determines realization of method which permits effective numerical integrations

Fuzzy set Theory and Quantum Chemistry

Es discuteixen breument algunes consideracions sobre l'aplicació de la Teoria dels Conjunts difusos a la Química quàntica. Es demostra aqui que molts conceptes químics associats a la teoria són adequats per ésser connectats amb l'estructura dels Conjunts difusos. També s'explica com algunes descripcions teoriques dels observables quàntics es potencien tractant-les amb les eines associades als esmentats Conjunts difusos. La funció densitat es pren com a exemple de l'ús de distribucions de possibilitat al mateix temps que les distribucions de probabilitat quàntiques

Afectación al ratio de solvencia mínimo requerido, producto de la aplicación del capital por riesgo operativo a los bancos parte del sistema financiero ecuatoriano, bajo el enfoque y metodología de medición planteado por Basilea II

La solvencia para la industria bancaria está medida en función del ratio que relaciona al capital regulatorio con los activos ponderados por riesgo, ésta es una medida que sirve para tener una apreciación de cuan respaldada se encuentra una institución bancaria para hacer frente a los riesgos que está expuesta por la propia inherencia del negocio. Es en este contexto que se vuelve importante el cálculo del ratio de solvencia para los bancos privados del Ecuador y el cambio o afectación que éste sufre como producto de considerar el valor por la exposición al riesgo operativo y que se considera como un requerimiento de capital. El ratio de solvencia está en función del Índice de Basilea, y, el valor de exposición al riesgo operativo está calculado por uno de los métodos que se menciona en el documento Acuerdo de Capitales o Basilea II. El presente estudio partió de comprobar que en el Ecuador es factible aplicar por parte de las entidades bancarias uno de los métodos de medición para riesgo operativo, considerando que en algunos países de Latinoamérica y en España ya lo aplican. Adicionalmente, se presenta una alternativa de aplicación en el ratio de solvencia del valor calculado para el riesgo operativo, para suavizar su resultado.

La “última ratio” del derecho constitucional ecuatoriano a la resistencia

En el año 2008, Ecuador constitucionalizó el derecho a la resistencia, el cual, desde hace varias décadas se considera un tema agotado, o por lo menos, abandonado para la teoría constitucional por considerarlo como un derecho de imposible asimilación dentro de la estructura de los contemporáneos estados de Derecho basados en la primacía de la ley y en los que la sola vigencia de las normas son su parámetro de validez, sin reparar en la justicia o injusticia del resultado obtenido producto de su aplicación. Por lo tanto, el propósito inicial del presente trabajo investigativo es brindar, desde la dogmática jurídica, una comprensión clara sobre la naturaleza del derecho a la resistencia y evidenciar su problemática y posibles alcances dentro de nuestro estado constitucional de derechos y justicia. Un segundo propósito será constatar que la validez, vigencia y eficacia del derecho a la resistencia solo será posible si su contenido se adapta al nuevo paradigma constitucional que abandera el constitucionalismo de derechos, tarea en la que no se podrá desconocer los aportes de nuestra realidad jurídica, política y social. Un propósito final, busca lograr que desde el ámbito constitucional se comprenda el postulado de la última ratio como un elemento importante y que configura el contenido esencial de este derecho que, a más de limitarlo y darle su validez, posibilita su efectiva vigencia como un recurso excepcional frente al Derecho positivo, permitiendo superar parte de la problemática que hoy le aqueja: interpretación y empleo discrecional y arbitrario, proscripción, e ineficacia.

Land/sea warming ratio in response to climate change: IPCC AR4 model results and comparison with observations

Climate model simulations consistently show that in response to greenhouse gas forcing surface temperatures over land increase more rapidly than over sea. The enhanced warming over land is not simply a transient effect, since it is also present in equilibrium conditions. We examine 20 models from the IPCC AR4 database. The global land/sea warming ratio varies in the range 1.36–1.84, independent of global mean temperature change. In the presence of increasing radiative forcing, the warming ratio for a single model is fairly constant in time, implying that the land/sea temperature difference increases with time. The warming ratio varies with latitude, with a minimum in equatorial latitudes, and maxima in the subtropics. A simple explanation for these findings is provided, and comparisons are made with observations. For the low-latitude (40°S–40°N) mean, the models suggest a warming ratio of 1.51 ± 0.13, while recent observations suggest a ratio of 1.54 ± 0.09.

A genetic algorithm for the design of a fuzzy controller for active queue management

Active queue management (AQM) policies are those policies of router queue management that allow for the detection of network congestion, the notification of such occurrences to the hosts on the network borders, and the adoption of a suitable control policy. This paper proposes the adoption of a fuzzy proportional integral (FPI) controller as an active queue manager for Internet routers. The analytical design of the proposed FPI controller is carried out in analogy with a proportional integral (PI) controller, which recently has been proposed for AQM. A genetic algorithm is proposed for tuning of the FPI controller parameters with respect to optimal disturbance rejection. In the paper the FPI controller design metodology is described and the results of the comparison with random early detection (RED), tail drop, and PI controller are presented.

A fuzzy approach for the network congestion problem

In the recent years, the unpredictable growth of the Internet has moreover pointed out the congestion problem, one of the problems that historicallyha ve affected the network. This paper deals with the design and the evaluation of a congestion control algorithm which adopts a FuzzyCon troller. The analogyb etween Proportional Integral (PI) regulators and Fuzzycon trollers is discussed and a method to determine the scaling factors of the Fuzzycon troller is presented. It is shown that the Fuzzycon troller outperforms the PI under traffic conditions which are different from those related to the operating point considered in the design.

Parallel genetic algorithms for the tuning of a fuzzy AQM controller

This paper presents the results of the application of a parallel Genetic Algorithm (GA) in order to design a Fuzzy Proportional Integral (FPI) controller for active queue management on Internet routers. The Active Queue Management (AQM) policies are those policies of router queue management that allow the detection of network congestion, the notification of such occurrences to the hosts on the network borders, and the adoption of a suitable control policy. Two different parallel implementations of the genetic algorithm are adopted to determine an optimal configuration of the FPI controller parameters. Finally, the results of several experiments carried out on a forty nodes cluster of workstations are presented.

On logarithmic ratio quantities and their units

The use of special units for logarithmic ratio quantities is reviewed. The neper is used with a natural logarithm (logarithm to the base e) to express the logarithm of the amplitude ratio of two pure sinusoidal signals, particularly in the context of linear systems where it is desired to represent the gain or loss in amplitude of a single-frequency signal between the input and output. The bel, and its more commonly used submultiple, the decibel, are used with a decadic logarithm (logarithm to the base 10) to measure the ratio of two power-like quantities, such as a mean square signal or a mean square sound pressure in acoustics. Thus two distinctly different quantities are involved. In this review we define the quantities first, without reference to the units, as is standard practice in any system of quantities and units. We show that two different definitions of the quantity power level, or logarithmic power ratio, are possible. We show that this leads to two different interpretations for the meaning and numerical values of the units bel and decibel. We review the question of which of these alternative definitions is actually used, or is used by implication, by workers in the field. Finally, we discuss the relative advantages of the alternative definitions.

Determination of the vibrational transition moment ratio for the Coriolis interacting v9 and v10 fundamentals of allene

Comparison between observed and calculated infrared band contours has been made to determine the vibrational transition moment ratio |M10/M9| for the Coriolis interacting ν9 and ν10 perpendicular fundamentals of allene-h4. The ratio obtained is appreciably lower than that of a previous estimate and the result obtained by integrated band intensity measurements of Overend and Crawford. From the best estimate of the ratio, the dipole moment derivatives of the two bands are determined; the value for the weaker band ν9 is subject to a large uncertainty.