Search results for "Names"

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…

Design of measurement-based correlation models for shadow fading

2010

This paper deals with the design of measurement-based correlation models for shadow fading. Based on the correlation model, we design a simulation model using the sumof-sinusoids (SOS) method to enable the simulation of spatial lognormal processes characterizing real-world shadow fading scenarios. The model parameters of the simulation model are computed by applying the L p -norm method (LPNM). This method facilitates an excellent fitting of the simulation model's autocorrelation function (ACF) to that of measured channels. Our study includes an evaluation of all important statistical quantities of the proposed measurement-based simulation model, such as the probability density function (PD…

Baltu filoloģija, 23. sēj., Nr.2

2015

Stochastic differential calculus for wind-exposed structures with autoregressive continuous (ARC) filters

2008

In this paper, an alternative method to represent Gaussian stationary processes describing wind velocity fluctuations is introduced. The technique may be considered the extension to a time continuous description of the well-known discrete-time autoregressive model to generate Gaussian processes. Digital simulation of Gaussian random processes with assigned auto-correlation function is provided by means of a stochastic differential equation with time delayed terms forced by Gaussian white noise. Solution of the differential equation is a specific sample of the target Gaussian wind process, and in this paper it describes a digitally obtained record of the wind turbolence. The representation o…

On the instability of an axially moving elastic plate

2010

Problems of stability of an axially moving elastic band travelling at constant velocity between two supports and experiencing small transverse vibrations are considered in a 2D formulation. The model of a thin elastic plate subjected to bending and tension is used to describe the bending moment and the distribution of membrane forces. The stability of the plate is investigated with the help of an analytical approach. In the frame of a general dynamic analysis, it is shown that the onset of instability takes place in the form of divergence (buckling). Then the static forms of instability are investigated, and critical regimes are studied as functions of geometric and mechanical problem param…

1994

Liquid crystalline side chain polymers containing photoreactive azobenzene chromophores in the dark-adapted trans form and phenylbenzoate groups as co-mesogens have been prepared and investigated as monomolecular layers at the water/air interface and as multilayer assemblies deposited onto solid supports by the Langmuir–Blodgett–Kuhn (LBK) technique. Pressure area isotherms at variable temperatures together with reflection absorption spectra and Brewster angle microscopic pictures have been taken and analyzed (i) to derive information about the structural order and the packing properties of the mesogenic side groups within the monolayers of different homo- and co-polymeric systems and ii) t…