Fatigue characteristics of pulsed MIG-welded Al-Zn-Mg alloy

Pulse-current MIG welding of Al-Zn-Mg alloy was carried out using an extruded section of base material and Al-Mg (5183) filler wire. During welding the pulse parameters such as the mean current and pulse frequency were varied and their effect on the geometry and porosity content of weld deposit as well as the fatigue life of the weldment was studied. The pulse parameters were found to affect significantly the geometry and porosity content of weld deposit and consequently the fatigue life of the weldment. For a comparative study, weldments were also prepared by using conventional continuous current MIG-welding process, where welding currents equivalent to the mean currents of pulsed process were used. The fatigue life of the weldment was correlated with the geometry and porosity content of weld deposit.     

Effect of midblock on the morphology and properties of blends of ABA triblock copolymers of PDLA-mid-block-PDLA with PLLA

A method to overcome the brittleness of poly (l-lactic acid) (PLLA) by kinetically trapping a continuous low T_g amorphous phase is presented. This morphology is accomplished by exploiting the significant difference in the crystallization temperatures of PLLA vs its stereocomplex with the poly (d-lactic acid) (PDLA) isomer. In our studies, the D isomer is the end block of a triblock copolymer with a configuration of the form PDLAn–Soft Blockm–PDLAn. As demonstrated in this study, when blended with PLLA, the obtained morphology, and improvement in the sample toughness and flexibility, strongly depend on the miscibility of the midblock in the triblock copolymer with the matrix PLLA. The difference in the chemical nature of the midblock clearly affected the stereocomplex crystallization between the PDLA end blocks, the PLLA matrix polymer, and the morphology formed. It is found that the miscible midblock gives rise to a soft continuous amorphous phase while in the case of an immiscible midblock, a glassy phase separated amorphous phase is formed. Dramatically different physical properties can be obtained for various PLLA/triblock copolymer blends giving access to tough, yet flexible, semicrystalline PLLA blends.     

Photodegradation of direct yellow-12 using UV/H2O2/Fe2+

A detailed investigation of photodegradation of direct yellow-12 (DY12) using UV/H(2)O(2)/Fe(2+) has been carried out in a photochemical reactor. Experiments studied degradation as a function of concentration, decolorization and reduction in chemical oxygen demand (COD). The effect of operating parameters, such as UV, pH, amount of Fenton's reagent (H(2)O(2) and FeSO(4)), and amount of DY12 dye has also been determined. It has been observed that simultaneous utilization of UV irradiation with Fenton's reagent increases the degradation rate of DY12 dye. The dye quickly losses its color and there is an appreciable decrease in COD value, indicating that the dissolved organic have been oxidized. The kinetics of degradation of the dye in dilute aqueous solutions follows pseudo-first order kinetics. Final products detected at the end of the reaction include NO(3)(-), NO(2)(-), N(2)O, NO(2), SO(2), CO(2) and CO. Results indicate that dye degradation is dependent upon pH, UV-intensity, concentration of Fenton's reagent and dye. Acidic pH has been found to be more suitable in comparison to neutral and alkaline. The optimum concentration of Fenton's reagent (H(2)O(2)/Fe(2+)) was found as 1500/500 mg l(-1) for 50 mg l(-1) DY12 dye in water at pH 4. The results indicate that the treatment of DY12 dye wastewater with UV/Fe(2+)/H(2)O(2) system is efficient.     

Analysis of the wetting behaviour of pigments and the effectiveness of surfactants

A new test method is introduced to analyse the wetting behaviour of pigments and the effectiveness of surfactants. The method involves the study of torque vs time curves obtained during the wetting of pigments by surfactant solutions. These curves provide valuable information regarding the wetting behaviour of pigments and the ability of the surfactant to wet the pigment. To study the wetting behaviour, two pigments which varied widely in their surface character are studied with the same surfactant, while, to study the effectiveness of the surfactant, different surfactants with differing polarity are studied using the same pigment. The results are found to be consistent with the theoretical expectations.     

Apparatus for viscoelastic thermal compression of wood

Viscoelastic Thermal Compression (VTC) of wood is a treatment which greatly improves material properties by means of densification with mechanical compression perpendicular to the grain. VTC is similar to other wood densification processes, but is designed for thin lamina and employs dynamic temperature and steam pressure conditions. A?device was constructed that is capable of producing VTC wood. Details of the construction and operation of the VTC device are presented. The device consists of a pressurized chamber with variable volume. Wood density may be modified from the initial density of the virgin wood up to approximately 1400?kg/m³. Control of steam pressure and temperature insures that the wood cell walls are not fractured during the process. The device is designed for batch operation and may be adapted to a conventional laboratory hot-press. An example operating schedule is described, but other procedures are possible within the design parameters of the device.     

Relationship Based Heuristic for Selecting Friends in Social Internet of Things

Wireless Personal Communications - Internet of Things is the future era of computing, where every conventional object are equipped with sensing and communicating capabilities to co-ordinate with...     

First-Principles Investigation of Electronic Properties of GaAsxSb1 –x Ternary Alloys

Semiconductors - Compositional variations in GaAs based ternary alloys have exhibited wide range alterations in electronic properties. In the present paper, first-principles study of...     

Effect of Fe doping on the photocatalytic activity of ZnO nanoparticles: experimental and theoretical investigations

Pure and Fe doped ZnO nanoparticles were prepared by a facile and cost-effective co-precipitation method. The X-ray diffractograms (XRD) reveal that the grown nanoparticles are hexagonal in structure and the crystallite sizes are in the range of 27–28 nm. The transmission electron microscope (TEM) micrographs confirmed the spherical nature of the grown particles and the Fourier transform-infrared (FT-IR) studies confirmed the presence of Zn–O bonding in the prepared nanoparticles. Additionally, the presence of the constituent elements is confirmed with XPS analysis. The optical bandgap of the prepared nanoparticles are calculated as 3.28, 3.19 and 3.08 eV for ZnO, ZnO–Fe 10 at.% and ZnO–Fe 20 at.%, respectively. The photocatalytic dye degradation efficiency against methylene blue, is 68.52, 73.96, and 87.92, respectively. To validate the photocatalytic activity, a DFT based calculation was performed to measure the band edge positions of the pure and Fe doped ZnO nanostructures, and the obtained results are well supported by the experimental results.     

An integrated fuzzy rough set and real coded genetic algorithm approach for crop identification in smart agriculture

Multimedia Tools and Applications - Digitalization accumulates data in a short period. Smart agriculture for crop identification for cultivation is a common problem in agriculture for agronomists....