Effect of Melt Cleanliness on the Mechanical Properties and Microstructure on AZ91E Mg Alloy Castings

The current study examines various filter configurations, argon bubbling, and degasser addition to improve melt cleanliness of AZ91E permanent mold castings. The unfiltered castings had an average yield strength, ultimate tensile strength, and elongation of 93.3, 153.3 MPa, and 2.2% respectively. Using a fine mesh filter within the well of the mold, the ultimate tensile strength and elongation increased by 9 and 41%, respectively, compared to the unfiltered samples. A combination of a fine filter and argon bubbling resulted in an average increase in ultimate tensile strength and elongation of 29 and 123%, respectively, that matched the performance of the C₂Cl₆-based degassed castings with 95.8, 194.3, and 4.9% for yield strength, ultimate tensile strength, and elongation, respectively. The addition of the C₂Cl₆-based degasser released harmful vapors that can be avoided using the fine filter with argon bubbling. In all cases, the removal of MgO-based inclusions improved mechanical properties.     

Measurement and targeting of thermophysical properties of carrot and meat based alginate particles for thermal processing applications

The objective of the study was to investigate the thermo-physical properties of meat and carrot based alginate particles as influenced by the formulation variables. A response surface methodology (RSM) was used to study the effect of sodium alginate concentration, calcium chloride concentration and dipping time in the calcium chloride solution, at five levels each, on the thermo-physical properties of the fabricated particles (9 mm in diameter and 9 mm in height). Density was similar for all conditions. Increasing sodium alginate concentration resulted in a significant decrease in the heat capacity and thermal conductivity values. These changes were primarily attributed to the lowering of moisture content of the particles resulting from the treatment. Using RSM, optimum conditions for fabricating particles having similar thermo-physical properties to real foods were obtained as 5.3% and 4.9% sodium alginate, 2.2% calcium chloride and 14.2 and 36.0 h immersion in the calcium chloride solution for meat and carrot alginate particles, respectively.     

A 1.44-mW, 1-MHz bandwidth continuous-time Σ∆ modulator with 10-bit ENOB in 130-nm CMOS

A low-power, low-pass continuous-time sigma-delta A/D modulator with 1-MHz bandwidth is implemented in a 130-nm CMOS process. The circuit is targeted for an IEEE 802.15.4 direct conversion receiver operating in the 2.4-GHz band. It has a third-order feedforward single-loop filter and a 1-bit quantizer to minimize power consumption. Non-return-to-zero DAC pulse shaping is used to reduce sensitivity to clock jitter. Clocked at 64 MHz, the prototype chip achieves 62-dB peak SNR, −70-dB peak THD, 63-dB dynamic range with an oversampling ratio of 32. The built-in anti-alias filter provides alias attenuation greater than 57 dB, which improves coexistence of the receiver with other devices that operate in the 2.4-GHz band. The circuit dissipates 1.44 mW from the 1.2-V supply and the active die area is 0.1 mm².     

A fully automatic one-scan adaptive zooming algorithm for color images

We present an interpolation algorithm for adaptive color image zooming. The algorithm produces the magnified image in one scan of the input image, and is fully automatic since does not involve any a priori fixed threshold. Given any integer zooming factor n, each pixel of the input image generates an n×n block of pixels in the zoomed image. For the currently visited pixel of the input image, the pixels of its associated block are first assigned tentative values, which are then adaptively updated before building the next block. The method is suggested for RGB images, but can equally be employed in other color spaces. Peak signal to noise ratio (PSNR) and Structural SIMilarity (SSIM) are used to evaluate the performance of the algorithm.     

Detection of debonding in composite-aluminum joints using gamma-ray Compton scattering

Gamma-ray Compton scattering is used for the detection of debonding in adhesively bonded composite-aluminum joints. A collimated narrow beam of monochromatic photons, generated by a ¹³⁷CS source, is directed towards the joint and scattered photons are recorded, using a detector located on the same side as the source. The energy of the scattered radiation is measured and related to the angle of scattering. The occurrence of debonding is indicated by a change in the count rate at an energy corresponding to its location. The performance of the technique is successfully demonstrated experimentally for joints of different adhesive-bonding thicknesses and for artificially induced debonds.     

Privacy preserving broadcast message authentication protocol for VANETs

Vehicular Ad-hoc Networks (VANETs) will start becoming deployed within the next decade. Among other benefits, it is expected that VANETs will support applications and services targeting the increase of safety on the road, and assist in improving the efficiency of the road transportation network. However, several serious challenges remain to be solved before efficient and secure VANET technology becomes available, one of them been efficient authentication of messages in a VANET. There is a significant body of research work addressing this issue, however, while progress has been made, the challenge is still far from having been resolved and reliable and secure systems ready for deployment becoming available. In this paper, we propose the Privacy Preserving Broadcast Message Authentication (PPBMA) scheme, which, instead of performing asymmetric verification, uses Message Authentication Code (MAC) functionality and HASH operations to authenticate messages. Moreover, we use two-level key hash chain, which assists avoiding message losses. Simulation results demonstrate that PPBMA has superior performances in terms of packet loss rate and message delivery latency when compared to existing solutions. Due to this advantage, it can support emergency and routine messages alike, while existing solutions can only support routine messages.     

Facile green synthesis, optical and photocatalytic properties of zinc oxide nanosheets via microwave assisted hydrothermal technique

Novel hexagonal two dimensional ZnO nanosheets were successfully and economically synthesized using zinc acetate and urea based on a facile microwave hydrothermal method. The structure, morphology and size of the ZnO nanosheets were investigated by X-ray diffraction (X-ray), field emission scanning electron microscopy (FESEM), energy dispersive analysis of x-ray (EDS), transmission electron microscopy (TEM), selected area electron diffraction (SAED) and Fourier transform infrared spectroscopy (FTIR). X-ray analysis showed that the obtained ZnO nanosheets are crystalline corresponding to the pure ZnO phase with an average particle size of 12 nm. Optical properties of ZnO nanosheets were investigated by UV-Vis absorption and photoluminescence (PL) techniques. The band gap energy of ZnO nanosheets was found to be 3.29 eV. The photoluminescence (PL) measurement shows a strong UV emission, blue emission and blue-green emission bands. ZnO nano sheets possess a higher photocatalytic activity leading to the degradation of methylene blue (MB). The ZnO nanosheets are expected to have new opportunities in vast research areas and for application in catalysts and optoelectronic devices.     

Volatile and semi-volatile components of oak wood chips analysed by Accelerated Solvent Extraction (ASE) coupled to gas chromatography–mass spectrometry (GC–MS)

Volatile and semi-volatile compounds of French and American oak wood used in wine and spirits ageing were extracted by an Accelerated Solvent Extractor (ASE) and analysed by gas chromatography–mass spectrometry. More than 90 compounds were isolated, characterised and quantified after being separated on two chromatographic columns with distinct polarity. The main oak wood components were quantitatively determined by using standard reference compounds. In addition, a number of compounds, mainly guaiacol and syringol derivatives, were detected and characterised. In particular, 10 compounds were tentatively identified as lignin dimers derivatives, whose presence in oak wood chips or barrels for wine and spirits ageing had not been previously described. Several of the characterised compounds enabled a distinction to be drawn between medium and high toasted wood chips, independently of their geographical origin.