Influence of copper addition on corrosion properties and hardness of Al–Cu/Al two-layered-structure composites

An experimental investigation has been observed on hardness, sintered density and corrosion behaviour of two-layered structured Al-xCu/Al sample through powder metallurgical route under hot compaction condition. The samples were prepared with different percentages of Cu content (x: 5 wt. %, 10 wt. % and 15 wt. %) in the aluminium matrix with a constant pressure of 400 MPa with different hot-pressed temperatures (500 °C, 550 °C and 600 °C) at a dwelling time of 3 h. The developed two-layered samples microstructure was analysed using the optical and scanning electron microscope. The highest value of micro-hardness (100.6 HV) was obtained at interface region of 15% of copper at 550 °C. The corrosion rate of Al-Cu/Al two-layered samples at the interface were analyzed through the potentiodynamic polarization test and found that with addition of copper content the susceptibility of corrosion increases. The Electrochemical Impedance Spectroscopy (EIS) test was conducted to know the equivalent circuit model, which provides a minimum chi-square value and that circuit model taken as best-fit circuit model. From the EIS results, it was found that 10 wt. %Cu sample circuit provides minimum chi-square value.

Magneto-impedance Effects in Electrodeposited Multi-layer [NiFe/Cu]3 on Cu Wire Substrates for kHz-order Frequency Measurements

The magneto-impedance effect (MI) in an electrodeposited multi-layered system of [NiFe/Cu]N on a Cu wire was modified by varying the thickness of the Cu spacer layer. The multi-layered samples of [NiFe/Cu]N were deposited by the electrodeposition using a platinum electrode. The MI ratio rapidly increased with a frequency of up to 100 kHz where it saturated. Conversely, the MI ratio of the multi-layered system [NiFe (800 nm)/Cu(y nm)]3 was a decreasing function of Cu layer thickness. The decreased MI ratio may be attributed to the lowered saturation magnetization in the multi-layered system with thicker spacer layers.

Numerical Simulation on Spatial-Frequency Domain Imaging for Estimating Optical Absorption and Scattering Properties of Two-Layered Horticultural Products

Spatial-frequency domain imaging (SFDI) is a wide-field, noncontact, and label-free imaging modality that is currently being explored as a new means for estimating optical absorption and scattering properties of two-layered turbid materials. The accuracy of SFDI for optical property estimation, however, depends on light transfer model and inverse algorithm. This study was therefore aimed at providing theoretical analyses of the diffusion model and inverse algorithm through numerical simulation, so as to evaluate the potential for estimating optical absorption and reduced scattering coefficients of two-layered horticultural products. The effect of varying optical properties on reflectance prediction was first simulated, which indicated that there is good separation in diffuse reflectance over a large range of spatial frequencies for different reduced scattering values in the top layer, whereas there is less separation in diffuse reflectance for different values of absorption in the top layer, and even less separation for optical properties in the bottom layer. To implement the nonlinear least-square method for extracting the optical properties of two-layered samples from Monte Carlo-generated reflectance, five curve fitting strategies with different constrained parameters were conducted and compared. The results confirmed that estimation accuracy improved as fewer variables were to be estimated each time. A stepwise method was thus suggested for estimating optical properties of two-layered samples. Four factors influencing optical property estimation of the top layer, which is the basis for accurately implementing the stepwise method, were investigated by generating absolute error contour maps. Finally, the relationship between light penetration depth and spatial frequency was studied. The results showed that penetration depth decreased with the increased spatial frequency and also optical properties, suggesting that appropriate selection of spatial frequencies for a stepwise method to estimate optical properties from two-layered samples provides potential for estimation accuracy improvement. This work lays a foundation for improving optical property estimation of two-layered horticultural products using SFDI.

A home on the floor: The musical expression of a DJ in a queer place

Existing studies about DJ learning and experience hint at the importance of place and music in the development of DJ musicianship. An exploration of the experiences of a queer DJ performing electronic dance music in a queer place might broaden our understanding of how musical expression and identity intermingle with musical places. I sought to understand how the monthly queer event Bronco functioned as a place for musical expression for an electronic dance music DJ named Greg. Using the remix as a methodological framework, I layered samples from interviews and field texts to depict Greg’s experiences alongside my own at Bronco. Findings illuminate the role of place in Greg’s musical development, performances and expression of musical and sexual identity. The resonance of Greg’s experiences with my experience as a queer music educator is discussed as well as considerations for music educators who may seek to include electronic dance music in classroom settings.

Electromagnetic interference shielding and mechanical properties of multi-layered polyvinyl chloride/multiwall carbon nanotubes nanocomposite

Electromagnetic shielding is one of the promising research areas that attract the interest of many researchers, especially researchers interested in polymer nanocomposite. In this work, the shielding efficiency and dynamic mechanical analysis for multi-layered samples are reviewed and analyzed. The multi-layered samples were prepared using two sheets of polyvinyl chloride (PVC) polymer loaded with multiwall carbon nanotubes over the electrical percolation threshold, and a MWCNTs buckypaper (MWCNTs BP) sheet between them. The three sheets were collected together by hot-press technique to form a multi-layered nanocomposite sample. The shielding efficiency of single and double layers of PVC/MWCNTs sheets loaded by 5 wt.% MWCNTs, was very weak. The new structured (3 layered/multilayered) nanocomposite samples were prepared with different weight percent of MWCNTs BP sheet (0, 1, 2, 3 and 4 wt.%). The SE values over all the frequency range (450 MHz to about 2.0 GHz) are strongly depends on the weight percent of the MWCNTs BP. Shielding efficiency increased as the MWCNTs BP weight percent increased. Decreases the elastic modulus, storage modulus and the coefficient of complex viscosity were found for a new set of samples contains 0.14, 0.27, 0.28 and 0.44 wt.% MWCNTs BP layers. This is due to the diffused MWCNTs from the mesh to polymer layers making the composite more brittle. The glass transition temperature determined from tanδ(f) increased as MWCNTs BP content increases.