Damage detections in nonlinear vibrating thermally loaded plates

In this work, geometrically nonlinear vibrations of fully clamped rectangular plates subjected to thermal changesare used to study the sensitivity of some vibration response parameters to the presence of damage and elevated temperature. The geometrically nonlinear version of the Mindlin plate theory is used to model the plate behaviour.Damage is represented as a stiffness reduction in a small area of the plate. The plates are subjected to harmonicloading leading to large amplitude vibrations and temperature changes. The plate vibration response is obtained by a pseudo-load mode superposition method. The main results are focussed on establishing the influence of damage on the vibration response of the heated and the unheated plates and the change in the time-history diagrams and the Poincaré maps caused by damage and elevated temperature. The damage criterion formulated earlier for nonheated plates, based on analyzing the points in the Poincaré sections of the damaged and healthy plate, is modified and tested for the case of plates additionally subjected to elevated temperatures. The importance of taking into account the actual temperature in the process of damage detection is shown

Tracking the relationship between euro area equities and sovereign bonds

This paper explores the relationship between stocks and sovereign bonds by means of the asymmetric detrended cross-correlation analysis (ADCCA). Drawing on data from 1999.01 to 2018.09 of the first wave of euro area countries, the full sample is divided into three subsets in accordance with economic and financial features. Some findings arise with striking implications for investors and policymakers. Firstly, empirical results show that cross-correlations differ from country to country, depending on the sub-period under analysis and on the time scale. Secondly, likewise within country estimates, cross-country linkages may point to fragmentation in the euro area with agents moving away from financial assets of lower-rated countries to invest in more robust economies in periods of turmoil. Thirdly, there is evidence of asymmetry since 'flight-to-quality' movements seem to be more relevant than 'flight-to-yield' episodes. Finally, while relationships were globally bidirectional until mid-2007, new causality patterns arose with the financial crisis.info:eu-repo/semantics/publishedVersio

Nanometric pitch in modulated structures of twist-bend nematic liquid crystals

The extended Frank elastic energy density is used to investigate the existence of a stable periodically modulate structure that appears as a ground state exhibiting a twist-bend molecular arrangement. For an unbounded sample, we show that the twist-bend nematic phase $N_{TB}$ is characterized by a heliconical structure with a pitch in the nano-metric range, in agreement with experimental results. For a sample of finite thickness, we show that the wave vector of the stable periodic structure depends not only on the elastic parameters but also on the anchoring energy, easy axis direction, and the thickness of the sample.Comment: 11 page

Reflectance spectrometry of rocks from the comstock lode (Virginia City, Nevada, USA) and its comparison with X-ray diffraction

This paper presents the results of mineralogical analysis of hydrothermal altered rocks from the Comstock Lode, near Virginia City, Nevada, USA, using two different techniques: reflectance spectrometry and X-ray diffraction. These results are discussed based on their quickness, accuracy and low costs. The applicability to mineral mapping using high spectral resolution remote sensing images is also briefly discussed. Comparison of the results obtained for both techniques have a good degree of correlation, showing that reflectance spectrometry represents an expedite, simple and relatively inexpensive technique, capable of mapping numerous minerals in the field or in laboratory.Este trabalho apresenta resultados de análises mineralógicas de rochas com alteração hidrotermal do Lode de Comstock, próximo a Virgínia City, Estado de Nevada, EUA, utilizando duas diferentes técnicas: espectrometria de reflexão e difração de raio-X. Os resultados são discutidos em função de sua rapidez e facilidade de obtenção e acuracidade. Discute-se ainda, brevemente, sua aplicabilidade ao mapeamento mineral utilizando imagens de sensoriamento remoto com alta resolução espectral. A título de ilustração, apresenta-se uma imagem TM-Landsat da região de estudo, na qual pode-se observar a característica resposta das áreas alteradas hidrotermalmente. A comparação dos resultados obtidos com as duas técnicas apresentou um razoável grau de correlação, mostrando que a espectrometria é uma ferramenta expedita, simples, relativamente barata e capaz de identificar no campo ou em laboratório minerais de interesse na prospecção de áreas com alteração hidrotermal

Temperature independent band structure of WTe2 as observed from ARPES

Extremely large magnetoresistance (XMR), observed in transition metal dichalcogendies, WTe$_2$, has attracted recently a great deal of research interests as it shows no sign of saturation up to the magnetic field as high as 60 T, in addition to the presence of type-II Weyl fermions. Currently, there has been a lot of discussion on the role of band structure changes on the temperature dependent XMR in this compound. In this contribution, we study the band structure of WTe$_2$ using angle-resolved photoemission spectroscopy (ARPES) and first-principle calculations to demonstrate that the temperature dependent band structure has no substantial effect on the temperature dependent XMR as our measurements do not show band structure changes on increasing the sample temperature between 20 and 130 K. We further observe an electronlike surface state, dispersing in such a way that it connects the top of bulk holelike band to the bottom of bulk electronlike band. Interestingly, similar to bulk states, the surface state is also mostly intact with the sample temperature. Our results provide invaluable information in shaping the mechanism of temperature dependent XMR in WTe$_2$.Comment: 7 pages, 3 figures. arXiv admin note: text overlap with arXiv:1705.0721

Magnetization of undoped 2-leg S = 1/2 spin ladders in La4Sr10Cu24O41

Magnetization data of single crystalline La4Sr10Cu24O41 are presented. In this compound, doped spin chains and undoped spin ladders are realized. The magnetization, at low temperatures, is governed by the chain subsystem with a finite interchain coupling which leads to short range antiferromagnetic spin correlations. At higher temperatures, the response of the chains can be estimated in terms of a Curie-Weiss law. For the ladders, we apply the low-temperature approximation for a S=1/2 2-leg spin ladder by Troyer et al.Comment: 2 pages, 2 figure