Search results for "ESA"
showing 10 items of 11914 documents
Compact two-electron wave function for bond dissociation and Van der Waals interactions: A natural amplitude assessment
2014
Electron correlations in molecules can be divided in short range dynamical correlations, long range Van der Waals type interactions and near degeneracy static correlations. In this work we analyze for a one-dimensional model of a two-electron system how these three types of correlations can be incorporated in a simple wave function of restricted functional form consisting of an orbital product multiplied by a single correlation function $f(r_{12})$ depending on the interelectronic distance $r_{12}$. Since the three types of correlations mentioned lead to different signatures in terms of the natural orbital (NO) amplitudes in two-electron systems we make an analysis of the wave function in t…
Long-range interactions and the sign of natural amplitudes in two-electron systems
2013
In singlet two-electron systems the natural occupation numbers of the one-particle reduced density matrix are given as squares of the natural amplitudes which are defined as the expansion coefficients of the two-electron wave function in a natural orbital basis. In this work we relate the sign of the natural amplitudes to the nature of the two-body interaction. We show that long-range Coulomb-type interactions are responsible for the appearance of positive amplitudes and give both analytical and numerical examples that illustrate how the long-distance structure of the wave function affects these amplitudes. We further demonstrate that the amplitudes show an avoided crossing behavior as func…
Investigation by raman spectroscopy of the decomposition process of HKUST-1 upon exposure to air
2016
We report an experimental investigation by Raman spectroscopy of the decomposition process of Metal-Organic Framework (MOF) HKUST-1 upon exposure to air moisture (T=300 K, 70% relative humidity). The data collected here are compared with the indications obtained from a model of the process of decomposition of this material proposed in literature. In agreement with that model, the reported Raman measurements indicate that for exposure times longer than 20 days relevant irreversible processes take place, which are related to the occurrence of the hydrolysis of Cu-O bonds. These processes induce small but detectable variations of the peak positions and intensities of the main Raman bands of th…
FT Raman and DFT Study on a Series of All-antiOligothienoacenes End-Capped with Triisopropylsilyl Groups
2009
minal a positions. These substituents aid in purification and solution processability, and can be removed under mild chemical conditions. For the first time, we have the opportunity to analyze a series of oligothienoacenes to gain insight into the fundamental structure–property relationships with respect to the addition of each ring. Furthermore, this series of compounds can be directly compared to other well-studied series of closely related oligomers, such as nonfused oligothiophenes and fully fused all-syn oligothienoacenes. [7] To gain precise insight into relationships between the structure and properties of a wide range of p-conjugated molecular Herein, we study the p-conjugational pr…
Enseñanza de las ciencias : revista de investigación y experiencias didácticas
2003
Se discuten algunas de las conclusiones de varios trabajos históricos recientes sobre Amedeo Avogadro y la teoría atómica del siglo XIX. A través de pequeños extractos de publicaciones famosas de Avogadro, se analizan las características principales de sus aportaciones a la teoría atómica del siglo XIX. También se analizan los principales métodos de cálculo de pesos atómicos de esos años y se discute el papel de las ideas de Avogadro en este tema. Estas conclusiones se contrastan con la imagen que actualmente los libros de texto dan acerca de este autor. Finalmente, esta última comparación conduce a una discusión sobre el papel de la historia de la ciencia en los libros de texto. This paper…
The Theories of Helmholtz in the Work of Varèse
2011
In 1905 Varese discovered the French edition of Die Lehre von den Tonempfindungen als physiologische Grundlage fur die Theorie der Musik [On the Sensations of Tone as a Physiological Basis for the Theory of Music] of Hermann von Helmholtz (1863), the explicit intention of which was to bring together the common frontiers of science and music. This discovery was a revelation for the 22-year-old composer that went on to condition his whole philosophy of sound. The experiences of the German scientist, achieved with the aid of sirens, resonators or tuning forks, caught the imagination of the young composer. This article investigates the importance of the theories of Helmholtz for the Varesian ae…
Doppler Estimation and Correction for JANUS Underwater Communications
2020
In recent years, underwater communications have seen a growing interest pushed by marine research, oceanography, marine commercial operations, offshore oil industry and defense applications. Generally, underwater communications employ audio signals which can propagate relatively far but are also significantly affected by Doppler distortions. In fact, physical properties of the water and spatial changes due to tides, currents and waves can cause channel variations or unwanted movements of the transmitter or receiver. This study shows how to compensate for the Doppler effect in transmission employing the JANUS standard, a popular modulation scheme for underwater communication. Differently for…
Dance to your own drum: Identification of musical genre and individual dancer from motion capture using machine learning
2020
Machine learning has been used to accurately classify musical genre using features derived from audio signals. Musical genre, as well as lower-level audio features of music, have also been shown to...
Pasolini e la forma della città
2008
Auditoria de la Funció de Recursos Humans (II)
2015
El document forma part dels materials docents en valencià programats mitjançant l'ajut del Servei de Política Lingüística de la Universitat de València La fase d'avaluació i control del procés estratègic és de les menys tractades en el marc teòric de la Direcció Estratègica. Aquesta és la raó per la qual una primera aproximació de caràcter més conceptual feta en una primera part (publicada també ací), és ampliada amb la presentació de quatre auditories (clima, cultura, comunicació i coneixement) nomenades "transversals" perquè afecten directament o indirecta a tot el procés estratègic. És a dir que es tracta d'auditories de direcció i cal considerar-les en la formulació de l'estratègia orga…