4,258 research outputs found
Pressure-induced phase transitions in AgClO4
AgClO4 has been studied under compression by x-ray diffraction and density
functional theory calculations. Experimental evidence of a structural phase
transition from the tetragonal structure of AgClO4 to an orthorhombic
barite-type structure has been found at 5.1 GPa. The transition is supported by
total-energy calculations. In addition, a second transition to a monoclinic
structure is theoretically proposed to take place beyond 17 GPa. The equation
of state of the different phases is reported as well as the calculated
Raman-active phonons and their pressure evolution. Finally, we provide a
description of all the structures of AgClO4 and discuss their relationships.
The structures are also compared with those of AgCl in order to explain the
structural sequence determined for AgClO4.Comment: 38 pages, 11 figures, 4 table
Quasi-pinning and entanglement in the lithium isoelectronic series
The Pauli exclusion principle gives an upper bound of 1 on the natural
occupation numbers. Recently there has been an intriguing amount of theoretical
evidence that there is a plethora of additional generalized Pauli restrictions
or (in)equalities, of kinematic nature, satisfied by these numbers. Here for
the first time a numerical analysis of the nature of such constraints is
effected in real atoms. The inequalities are nearly saturated, or quasi-pinned.
For rank-six and rank-seven approximations for lithium, the deviation from
saturation is smaller than the lowest occupancy number. For a rank-eight
approximation we find well-defined families of saturation conditions.Comment: 22 pages, 6 figures, minor changes, references adde
Optimización de secciones ortotropas sometidas a torsión mediante el método de los elementos de contorno
El propósito dellpresente trabajo es la: resolución del problema de optimización de forma de secciones ortótropas, simple y simplemente conexas, sometidas a torsión de Saint-Venant, mediante el método de los elementos de contorno. La función objetivo es el área de la sección,
mientras que la única restricción corresponde a una rigidez torsional especificada. Se detalla el algoritmo utilizado para resolver el problema de optimización no lineal resultante, así como los diferentes criterios utilizados para conseguir una redefinición automática de la malla entre dos iteraciones consecutivas. Por último, se incluye una breve descripción del programa desarrollado y varios ejemplos.The aiin of this paper is the solution of the shape optimization problem for simply and
multiply-connected orthotropic sections under Saint-Venant torsion by using the Boundary Element Method. The objective function is the area of the section, while the only constraint corresponds to a given torsional stiffness. The nonlinear optimization algorithm is also discussed, so they are the different criteria used to get a consistent and automatic boundary redefinition looking for a ininimum number of iterations in the optimization process. Finaliy, a brief description of the program and severa1 examples are also included.Peer Reviewe
Optimización de secciones ortotropas sometidas a torsión mediante el método de los elementos de contorno
El propósito dellpresente trabajo es la: resolución del problema de optimización de forma de secciones ortótropas, simple y simplemente conexas, sometidas a torsión de Saint-Venant, mediante el método de los elementos de contorno. La función objetivo es el área de la sección,
mientras que la única restricción corresponde a una rigidez torsional especificada. Se detalla el algoritmo utilizado para resolver el problema de optimización no lineal resultante, así como los diferentes criterios utilizados para conseguir una redefinición automática de la malla entre dos iteraciones consecutivas. Por último, se incluye una breve descripción del programa desarrollado y varios ejemplos.The aiin of this paper is the solution of the shape optimization problem for simply and
multiply-connected orthotropic sections under Saint-Venant torsion by using the Boundary Element Method. The objective function is the area of the section, while the only constraint corresponds to a given torsional stiffness. The nonlinear optimization algorithm is also discussed, so they are the different criteria used to get a consistent and automatic boundary redefinition looking for a ininimum number of iterations in the optimization process. Finaliy, a brief description of the program and severa1 examples are also included.Peer Reviewe
Bipartisanship Breakdown, Functional Networks, and Forensic Analysis in Spanish 2015 and 2016 National Elections
In this paper we present a social network and forensic analysis of the vote
counts of Spanish national elections that took place in December 2015 and their
sequel in June 2016. Vote counts are extracted at the level of municipalities,
yielding an unusually high resolution dataset with over 8000 samples. We
initially consider the phenomenon of Bipartisanship breakdown by analysing
spatial distributions of several Bipartisanship indices. We find that such
breakdown is more prominent close to cosmopolite and largely populated areas
and less important in rural areas where Bipartisanship still prevails, and its
evolution mildly consolidates in the 2016 round, with some evidence of
Bipartisanship reinforcement which we hypothesize to be due to psychological
mechanisms of risk aversion. On a third step we explore to which extent vote
data are faithful by applying forensic techniques to vote statistics. We first
explore the conformance of first digit distributions to Benford's law for each
of the main political parties. The results and interpretations are mixed and
vary across different levels of aggregation, finding a general good
quantitative agreement at the national scale for both municipalities and
precincts but finding systematic nonconformance at the level of individual
precincts. As a complementary metric, we further explore the co-occurring
statistics of voteshare and turnout, finding a mild tendency in the clusters of
the conservative party to smear out towards the area of high turnout and
voteshare, what has been previously interpreted as a possible sign of
incremental fraud. In every case results are qualitatively similar between 2015
and 2016 elections.Comment: 23 pages, 21 figures, accepted for publication in Complexit
Visco-hyperelastic model with damage for simulating cyclic thermoplastic elastomers behavior applied to an industrial component
In this work a nonlinear phenomenological visco-hyperelastic model including damage consideration is developed to simulate the behavior of Santoprene 101-73 material. This type of elastomeric material is widely used in the automotive and aeronautic sectors, as it has multiple advantages. However, there are still challenges in properly analyzing the mechanical phenomena that these materials exhibit. To simulate this kind of material a lot of theories have been exposed, but none of them have been endorsed unanimously. In this paper, a new model is presented based on the literature, and on experimental data. The test samples were extracted from an air intake duct component of an automotive engine. Inelastic phenomena such as hyperelasticity, viscoelasticity and damage are considered singularly in this model, thus modifying and improving some relevant models found in the literature. Optimization algorithms were used to find out the model parameter values that lead to the best fit of the experimental curves from the tests. An adequate fitting was obtained for the experimental results of a cyclic uniaxial loading of Santoprene 101-73
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