Clew-like hierarchical ZnO nanostructure assembled by nanosheets as an efficient photocatalyst for degradation of azure B

In this study, hierarchical ZnO nanostructure assembled by nanosheets was synthesized via a facile and rapid ultrasound assisted route without any surfactant or template. The phase structure, morphology and optical property of the ZnO sample were investigated by XRD, FT-IR, SEM, and UV–Vis spectroscopy. Nitrogen sorption was also studied to determine the specific surface area and the pore size distribution. The ZnO sample was hexagonal pure phase of hierarchical clew-like microspheres consisting of nanosheets with average thickness and specific surface area of 50 nm and 41 m² g^?1, respectively. Synthesized ZnO was applied for the photocatalytic degradation of an organic dye, azure B as a pollutant model under UV irradiation. The effects of several parameters including dye concentration, catalyst dosage, pH, and irradiation time on photocatalytic degradation have been studied. The results indicated hierarchical ZnO has potential application for degrading of organic pollutants. Hydroxyl radicals were found to be main reactive species in this photodegradation process.     

Low-density parity-check codes for volume holographic memory systems

We investigate the application of low-density parity-check (LDPC) codes in volume holographic memory (VHM) systems. We show that a carefully designed irregular LDPC code has a very good performance in VHM systems. We optimize high-rate LDPC codes for the nonuniform error pattern in holographic memories to reduce the bit error rate extensively. The prior knowledge of noise distribution is used for designing as well as decoding the LDPC codes. We show that these codes have a superior performance to that of Reed-Solomon (RS) codes and regular LDPC counterparts. Our simulation shows that we can increase the maximum storage capacity of holographic memories by more than 50 percent if we use irregular LDPC codes with soft-decision decoding instead of conventionally employed RS codes with hard-decision decoding. The performance of these LDPC codes is close to the information theoretic capacity.     

Optimization in solving inventory control problem using nature inspired Emperor Penguins Colony algorithm

Journal of Intelligent Manufacturing - In the present day markets, it is essential for organizations that manage their supply chain efficiency to sustain their market share and improve...     

The local discontinuous Galerkin method for 2D nonlinear time-fractional advection–diffusion equations

This paper presents a numerical solution of time-fractional nonlinear advection–diffusion equations (TFADEs) based on the local discontinuous Galerkin method. The trapezoidal quadrature scheme (TQS) for the fractional order part of TFADEs is investigated. In TQS, the fractional derivative is replaced by the Volterra integral equation which is computed by the trapezoidal quadrature formula. Then the local discontinuous Galerkin method has been applied for space-discretization in this scheme. Additionally, the stability and convergence analysis of the proposed method has been discussed. Finally some test problems have been investigated to confirm the validity and convergence of the proposed method.

     

Biodegradation evaluation of poly (lactic acid) for stent application: Role of mechanical tension and temperature

In this study, an experimental investigation is conducted on mechanical characteristics of poly(lactic acid) (PLA), before, and during degradation for stent application. A bioreactor is designed and fabricated to mimic in-vivo environment of the body for studying degradation behavior of PLA fibers manufactured by melt spinning method. Beside PLA fibers, the degradation of PLA braided stents is investigated as control samples. To measure stress–strain and stress relaxation properties of PLA fibers, tensile, and relaxation tests are conducted. The decreasing trend of Young's modulus, variations in residual stress value after relaxation and pattern of stress relaxation are found during degradation. The influence of effective parameters, that is, temperature and stress, on PLA degradation is also studied. Moreover, the PLA degradation is analyzed by gel permeation chromatography (GPC), differential scanning calorimetry (DSC), Thermogravimetric analysis (TGA) and microscopic images. GPC results indicate the molecular weight decreases from 196,000 to 80,000 due to degradation while DSC analysis confirmed that the degradation promote an increase in PLA degree of crystallinity (from 43.3% to 59.8%). In addition, TGA results show that the PLA thermal stability decreases during degradation. This study provides useful information on PLA properties during degradation to assess the material in context of degradable stents.     

Effect of shot peening process on fatigue behavior of an alloyed austempered ductile iron

Shot peening is one of the most common surface treatments to improve the fatigue behavior of metallic parts. In this study the effect of shot peening process on the fatigue behavior of an alloyed austempered ductile iron (ADI) has been studied. Austempering heat treatment consisted of austenitizing at 875℃ for 90 min followed by austempering at three different temperatures of 320, 365 and 400℃. Rotating-bending fatigue test was carried out on samples after shot peening by 0.4-0.6 mm shots. XRD and SEM analysis, micro hardness and roughness tests were carried out to study the fatigue behavior of the samples. Results indicate that the fatigue strengths of samples austempered at 320, 365 and 400℃ are increased by 27.3%, 33.3% and 48.4%, respectively, after shot peening process.