The Dimension of Phaseless Near-Field Data by Asymptotic Investigation of the Lifting Operator

In this paper, the question of evaluating the dimension of data space in an inverse source problem from near-field phaseless data is addressed. The study is developed for a 2D scalar geometry made up by a magnetic current strip whose square magnitude of the radiated field is observed in near non-reactive zone on multiple lines parallel to the source. With the aim of estimating the dimension of data space, at first, the lifting technique is exploited to recast the quadratic model as a linear one. After, the singular values decomposition of such linear operator is introduced. Finally, the dimension of data space is evaluated by quantifying the number of “relevant” singular values. In the last part of the article, some numerical simulations that corroborate the analytical estimation of data space dimension are shown.

Flame temperature and alkali emission in combustion of sugarcane bagasse and straw

This work presents a numerical and experimental study in a laboratorial rig to measure local flame temperature and alkali emission during the combustion of sugarcane bagasse and straw. Tubular combustion chamber to simulate combustion in grate is used. A spectral analysis method in the visible spectrum was used for measurement of local temperatures in a sugarcane bagasse flame and sugarcane straw flame. The two-color method is used to calculate flame temperature. In flame reactive zone, the bagasse and straw flame temperatures in the range of 1420 to 1510 K and in the range of 1450 to 1550 K respectively are calculated. The intensity of alkali emission during the sugarcane bagasse and straw combustion is calculated using data of the spectrum in visible range. It was found that potassium emission is correlated with the instantaneous bagasse flame temperature in the reactive combustion zone. Emission of potassium and sodium during straw combustion is higher than in bagasse combustion. Temperature and alkali emissions along the flame height are measured.

Structure and Properties of Tantalum Coatings Obtained by Electron Beam Technology on Aluminum Substrates

The paper deals with the study of the structure and properties of tantalum coatings formed by electron beam evaporation and deposition of tantalum powder on 300–450 °C aluminum substrate. The research results of surface morphology, phase and elemental composition show that high activity of an aluminum substrate and specific conditions for vapor-phase technology promote formation of tantalum coatings characterized by a high degree of crystalline grains, with high adhesion and hardness despite the surface cracks. It was observed that the optimum deposition temperature of tantalum on aluminum substrates varies from 300 °C to 350 °C. These coatings demonstrate excellent physical and mechanical properties due to formation of intermetallic phases in the reactive zone.

Physico-chemical Characterization and Zero Valent Iron Treatment of Borehole Water of Maroua-Cameroon

The quality of borehole water of Maroua was evaluated using physico-chemical properties and treated using Fe/sand mixture of different composition and 100% sand in the reactive zone column filtration. While the pH, iron and chloride amounts were generally within WHO standards other measured parameters were generally above these standards. The Fe/sand system improves pH and entirely removes colour than 100% sand system. It also more performant for hardness removal in three days than 100% sand but the latter is more efficient over a longer period. There is a reduction in the flow rate of the Fe/sand mixture. The borehole water of Maroua I council area is not very potable and can be rendered more potable by using a cheap and simple filtration system based on sand and Fe.