On the Practical use of Variable Elimination in Constraint Optimization Problems: 'Still-life' as a Case Study

Variable elimination is a general technique for constraint processing. It is often discarded because of its high space complexity. However, it can be extremely useful when combined with other techniques. In this paper we study the applicability of variable elimination to the challenging problem of finding still-lifes. We illustrate several alternatives: variable elimination as a stand-alone algorithm, interleaved with search, and as a source of good quality lower bounds. We show that these techniques are the best known option both theoretically and empirically. In our experiments we have been able to solve the n=20 instance, which is far beyond reach with alternative approaches

A preliminary evaluation of the use of gun bluing to enhance friction ridge detail on cartridge casings

Friction ridge detail was enhanced on fired and unfired 9mm brass luger ammunition casings using three techniques, two involving Gun Blue reagent at a concentration of 50% v/v. Fingermarks were deposited on a total number of 90 ammunition casings and half were discharged using a Glock 19 semiautomatic pistol. Mark development was achieved using either Superglue Fuming followed by Basic Yellow 40 Fluorescent Dye Staining (SG-BY40), Superglue Fuming followed by Gun Blue (SG-GB), or Gun Blue (GB) as a single process. All three processes developed ridge detail on both fired and unfired casings. The results of this preliminary work show that the use of Gun Blue as a single enhancement technique was able to enhance ridge detail of the highest quality and clarity particularly on fired casings, making it the most effective process

Relation between emotional intelligence and the physical-sportive activity in the extracurricular schedule

La finalidad del presente trabajo es analizar las relaciones existentes entre la práctica y no practica de actividades físicas y deportes en horario extraescolar con la inteligencia emocional en estudiantes de Educación Secundaria Obligatoria. Así mismo, también vamos a analizar si en función del tipo de deporte practicado (individual, adversario y colectivo) existen diferencias entre ellos. En el estudio participaron un total de 126 estudiantes del primer y segundo ciclo de la ESO. El instrumento utilizado fue el cuestionario BarOn EQ-i: YV (S) (2002), y la realización de una pregunta para conocer si practicaban actividad física o deporte y, en caso afirmativo, que indicaran que deporte practicaban. Las técnicas de análisis de datos incluyen una prueba t para muestras independientes y un análisis univariado de covarianza o ANOVA. Los resultados obtenidos indicaron que la práctica de actividades deportivas está asociada a mayores niveles de inteligencia emocional.The purpose of the present paper is to analyse the current connections between the practice and not practice of physical activities or sports in extracurricular schedule with the emotional intelligence in students of Secondary Obligatory Education. Likewise, we also propose to analyse if the type of sports (individual sport, adversary sport, team sport) has influence between them. The participants in our study were 126 students of the first and second cycle of Secondary Obligatory Education. The tools that we have used were the test BarOn EQ-i: YV (S) (2002) and one question to know if the students practice sports or not and if the answer was positive, write what sport they practice. The analysis of information’s techniques include a student’s t-test for independents samples and an analysis of variance or ANOVA. The obtained results indicate that practice physical activities or sports is associated with high levels of emotional intelligence

The use of SE(T) specimen fracture toughness for FFS assessment of defects in low constraint conditions

AbstractDue to the loss of constraint, shallow cracked specimens can ‘absorb’ more energy than deeply cracked specimens commonly used to define the critical value to fracture and therefore exhibit a higher fracture toughness. The increase in energy absorption allows a reduction in the inherent conservatism when assessing components in low constraint conditions. This study addresses the benefit of using shallow cracked SE(T) fracture toughness specimens in fitness for service (FFS) assessment of defects under low constraint conditions, e.g. blunt defects or shallow cracks. Tearing resistance curves (J-R curves) have been constructed by means of a virtual test framework to determine crack initiation and propagation for shallow cracked SE(T) specimens and parametric notched C(T) specimens. The effect of constraint level on J-R curves is compared. It is observed that most of the blunted C(T) specimens analysed exhibit the same or a lower toughness value than that of a shallow cracked SE(T) specimen. The results are used to show how reduced conservatism can be made in defect assessment of blunt defects or in cases in which reduced constraint conditions can be demonstrated

On a moment generalization of some classical second-order differential equations generating classical orthogonal polynomials

The aim of the work is to construct new polynomial systems, which are solutions to certain functional equations which generalize the second-order differential equations satisfied by the so called classical orthogonal polynomial families of Jacobi, Laguerre, Hermite and Bessel. These functional equations can be chosen to be of different type: fractional differential equations, q-difference equations, etc, which converge to their respective differential equations of the aforesaid classical orthogonal polynomials. In addition to this, there exists a confluence of both the families of polynomials constructed and the functional equations who approach to the classical families of polynomials and second-order differential equations, respectivel

The influence of temperature on hydrogen environmentally assisted cracking of AA7449-T7651 in moist air

Publisher Copyright: © 2020 Elsevier LtdThe 7xxx series of aluminium alloys are sensitive to intergranular hydrogen environmentally assisted cracking (HEAC) in moist air environments. A new generation of 7xxx alloys used in aircraft components (including AA7449) have been found to be more sensitive to HEAC. This investigation aims to quantify the HEAC crack growth rates of AA7449-T7651 in moist air at different temperatures. Double cantilever beam specimens were loaded at a constant displacement and placed in moist air (80–85% relative humidity) at temperatures between 25 and 80 °C. Regular measurements of crack length permitted the determination of the crack growth rate as a function of the stress intensity factor (KI) during stage I (high KI dependence of growth rate) and stage II (low KI dependence of growth rate). Increasing the temperature was found to increase the crack growth rate during stage II cracking, following Arrhenius kinetics. The activation energy for the stage II crack growth rate at a stress intensity factor of 14.5 MPam was estimated as 84.7 kJ/mol. Additionally, the threshold stress intensity factor for HEAC was found to decrease with increasing temperature. This was attributed to a higher hydrogen solubility at higher temperatures. The crack growth rate of AA7449-T7651 at room temperature was similar to that of overaged AA7050 and AA7075-T7651, ranging between 1.3 and 2.1 × 10−7 mm/s. It was inferred that the alloy temper has more influence than the composition during stage II cracking at room temperature.I would like to acknowledge the Engineering and Physical Sciences Research Council (EPSRC) for providing funding in a Doctoral Training Partnership (DTP). This funding is provided for a PhD in the University of Bristol (UK). I would also like to acknowledge the support of Alvin Chan and Henry Hall during the experimental design stage. I would like to acknowledge the Engineering and Physical Sciences Research Council (EPSRC) for providing funding in a Doctoral Training Partnership (DTP). This funding is provided for a PhD in the University of Bristol (UK). I would also like to acknowledge the support of Alvin Chan and Henry Hall during the experimental design stage.Peer reviewe

Finding robust solutions for constraint satisfaction problems with discrete and ordered domains by coverings

Constraint programming is a paradigm wherein relations between variables are stated in the form of constraints. Many real life problems come from uncertain and dynamic environments, where the initial constraints and domains may change during its execution. Thus, the solution found for the problem may become invalid. The search forrobustsolutions for constraint satisfaction problems (CSPs) has become an important issue in the ¿eld of constraint programming. In some cases, there exists knowledge about the uncertain and dynamic environment. In other cases, this information is unknown or hard to obtain. In this paper, we consider CSPs with discrete and ordered domains where changes only involve restrictions or expansions of domains or constraints. To this end, we model CSPs as weighted CSPs (WCSPs) by assigning weights to each valid tuple of the problem constraints and domains. The weight of each valid tuple is based on its distance from the borders of the space of valid tuples in the corresponding constraint/domain. This distance is estimated by a new concept introduced in this paper: coverings. Thus, the best solution for the modeled WCSP can be considered as a most robust solution for the original CSP according to these assumptionsThis work has been partially supported by the research projects TIN2010-20976-C02-01 (Min. de Ciencia e Innovacion, Spain) and P19/08 (Min. de Fomento, Spain-FEDER), and the fellowship program FPU.Climent Aunés, LI.; Wallace, RJ.; Salido Gregorio, MA.; Barber Sanchís, F. (2013). Finding robust solutions for constraint satisfaction problems with discrete and ordered domains by coverings. Artificial Intelligence Review. 1-26. https://doi.org/10.1007/s10462-013-9420-0S126Climent L, Salido M, Barber F (2011) Reformulating dynamic linear constraint satisfaction problems as weighted csps for searching robust solutions. 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