Wear Behavior of Biodegradable Mg–5Zn–1Y–(0–1)Ca Magnesium Alloy in Simulated Body Fluid

Metals and Materials International - In this study, wear behavior of biodegradable Mg–5Zn–1Y–(0–1)Ca alloys is investigated in simulated body fluid. Wear test is performed...     

Crystallization behavior of polypropylene in polypropylene/nylon 6 blend

This article describes the crystallization behavior of polypropylene (PP) in the presence of a crystallizable polymer, namely, nylon 6, in the binary blend of PP/nylon 6 in the composition range from 0 to 30 wt % of nylon 6 content in the blend. The crystallization behavior was studied through variation of the crystallinity with the blend composition and changes in the crystallization exotherms were recorded by differential scanning calorimetry (DSC) and the spherulite morphology was observed via polarized light microscopy (PLM). Comparison of the crystallization exotherms and melting endotherms revealed some differences which are attributed to the role of a sufficiently high thermal energy of the nylon 6 crystals on the melting of PP. The crystallinity of PP decreased in the presence of nylon 6, whereas the crystallinity of nylon 6 increased considerably in the presence of PP. The rate of nucleation of PP on addition of nylon 6 decreased rapidly in the region 0–10 wt % nylon 6 content, and, thereafter, at a higher nylon 6 content, decrease of the nucleation rate was relatively slow. PLM observation revealed the presence of composite spherulites with PP spherulites grown on the surface of the already‐formed nylon 6 spherulites. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 1153–1161, 1999     

Numerical Solution of Fuzzy Equations with Z-numbers Using Neural Networks

In this paper, the uncertainty property is represented by the Z-number as the coefficients of the fuzzy equation. This modification for the fuzzy equation is suitable for nonlinear system modeling with uncertain parameters. We also extend the fuzzy equation into dual type, which is natural for linearin-parameter nonlinear systems. The solutions of these fuzzy equations are the controllers when the desired references are regarded as the outputs. The existence conditions of the solutions (controllability) are proposed. Two types of neural networks are implemented to approximate solutions of the fuzzy equations with Z-number coefficients.     

Heat Transfer Enhancement in Thermal Processing of Tomato Juice by Application of Nanofluids

In this research, our chief aim was to survey possible improvements in thermophysical properties of nanofluids when they are used as heating mediums for time reduction and energy saving in food industries for the first time. Accordingly, three different variables of temperature (70, 80, and 90 °C), alumina nanoparticle concentration (0, 2, and 4 %), and time (30, 60, and 90 s) were selected for thermal processing of tomato juice by a shell and tube heat exchanger. Our results revealed that incorporation of nanoparticles could raise density, viscosity, and thermal conductivity and decrease heat capacity, but this increasing/decreasing trend was linear or non-linear depending on the diameter of the nanoparticles. Four percent Al₂O₃–water, compared with 2 % nanofluid and pure water (0 % nanofluid), had the highest overall heat transfer coefficients for all Re numbers. Incorporating nanoparticles into the base heating fluid of water could augment the effectiveness of the heat exchanger by 49 %. Thermal processing time of tomato juice was shorter for 2 and 4 % nanofluids, compared with water, by 22.23 and 46.29 %, respectively; this time reduction caused energy saving rates for 2 and 4 % nanofluids to be improved by 22.3 and 48.76 %, respectively.     

Phase Stability in Mechanically Alloyed Mg–Ni System Studied by Experiments and Thermodynamic Calculations

In this study, microstructural evolution of Mg–Ni alloy during mechanical alloying(MA) was investigated.Also, a thermodynamic approach was utilized to predict the most stable phases formed in Mg–Ni alloy after MA. The phase composition and microstructural properties of Mg–Ni alloy were assessed by X-ray diffractometry, high-resolution field emission scanning electron microscopy and high-resolution transmission electron microscopy. The results showed that ball milling of magnesium and nickel powder mixture for 70 h yields nanostructural Mg2Ni compound with an average grain size of ~20 nm. Thermodynamic calculations revealed that in the composition ranges of 0.0 \ XMg\ 0.03(at.%)and 0.97 \ XMg\ 1, there is no driving force for amorphous phase formation. In the composition range of 0.07 \ XMg\ 0.93, the change of Gibbs free energy for amorphous phase formation was more negative than solid solution.While for XMg= 0.66(nominal composition of Mg2Ni intermetallic phase), the change of Gibbs free energy for intermetallic phase was found to be more negative than both amorphous and solid solution phases indicating that Mg2Ni intermetallic compound is the most stable phase, in agreement with the experimental observations.     

A new mathematical modeling and a genetic algorithm search for milk run problem (an auto industry supply chain case study)

The idea of Milk Run has been used in the context of logistic and supply chain problems in order to manage the transportation of materials. In this paper, we propose a new Milk Run method, as a mixed integer approach, to manage supply chain problems. Since the resulted problem formulation is NP-Hard, we use some meta-heuristic and compare the results with the optimal solutions of the proposed Milk Run method. The mathematical modeling of this paper is purposely customized for a special case of an auto industry. We implement the mathematical formulation and the meta-heuristic using some actual data and compare the results with the current strategy. The preliminary results indicate that the proposed method could provide a practical tool to significantly reduce the cost of logistic.     

Parenteral administration of glutamine modulates acute phase response in postparturient dairy cows

The objective of this study was to investigate whether administration of l-Gln would affect mediators of acute phase response in postparturient dairy cows. Twenty-four multiparous Holstein cows were blocked by the expected day of calving and randomly assigned to 1 of the 3 treatment groups (n = 8/group): 1) i.v. infusion of 10 L of 0.85% NaCl (control), 2) i.v. infusion of 106, or 3) 212 g/d of l-Gln mixed with 10 L of 0.85% NaCl solution; each treatment was given 8 h/d for each of 7 consecutive days starting on d 1 after calving. Blood samples were collected 1 wk before the expected day of parturition as well as on d 0, 7, 14, and 21 after parturition; plasma concentrations of serum amyloid A (SAA), haptoglobin, and lipopolysaccharide-binding protein were measured by ELISA, and α₁-acid glycoprotein was assessed by radial immunodiffusion. Concentrations of SAA, haptoglobin, and α₁-acid glycoprotein increased in control cows after parturition, reaching peak values on d 0 or 7 postpartum (60, 1,093, and 963 μg/mL, respectively). Cows infused with 106 g/d of l-Gln had greater concentrations of SAA in plasma on d 14 and 21 compared with controls (62.8 vs. 30.2 and 71.1 vs. 34.5 μg/mL, respectively). Cows infused with 212 g/d of l-Gln had greater concentrations of SAA on d 7 (82.5 vs. 53.9 μg/mL) and lower concentrations of haptoglobin on d 14 and 21 postpartum compared with controls (264 vs. 621 and 175 vs. 587 μg/mL, respectively). Cows treated with 106 and 212 g/d of l-Gln had greater plasma lipopolysaccharide-binding protein concentrations on d 7 compared with control group (50.0 and 35.6 vs. 10.8 μg/mL, respectively). There were no treatment differences with respect to milk yield and DM intake during the experimental period. In conclusion, our data indicate that i.v. administration of l-Gln modulated acute phase mediators in dairy cows after parturition and warrants further research into the mechanisms behind these effects.     

The quantitative risk assessment of a hydrogen generation unit

The safety of hydrogen generation process is a major concern. This paper discusses the quantitative analyzes of the risk imposed on neighborhood from the operation of a hydrogen generator using natural gas reforming process. For this purpose, after hazard identification, the frequency of scenarios was estimated using generic data. Quantitative risk assessment was applied for consequence modeling and risk estimation. The results revealed that, jet fire caused by a full bore rupture in Desulphurization reactor has the highest fatality (26person) and affects the largest area of 5102 m². The lethality radius, maximum radiation and safe distance of this incident were 140 m, 370 kW/m² and 225 m respectively. A full bore rupture in Reformer can lead to the most dangerous flash fire. In this incident the concentration of released material in LFL zone (area of 1483.17 m²) and ½ LEL zone (area of 1970.74 m²) were 61,125 ppm and 40,000 ppm respectively. QRA is a credible method to assess the risks of hydrogen generation process.     

Influence of Gating System,Sand Grain Size,and Mould Coating on Microstructure and Mechanical Properties of Thin-Wall Ductile Iron

 In this study, the effect of gating systems, mould coating and sand grain size on metallurgical and mechanical properties of TWDI casting were investigated. Two different gating systems; stepped and tapered runners, were used to cast strip samples. The thicknesses of the samples cast were 2.3, 3.3, 4.5, 5.4, 6.5, 7.5 and 8.5 mm. The samples were cast in CO2/silicate process moulds of two different sand grain sizes of 151 and 171 according to the AFS standard. To assess the effect of mould coat on the properties of TWDI, half of the moulds were coated with graphite-based zircon whilst the rest were left uncoated. The carbon equivalent (CE) of the molten metal prepared was 4.29% and poured at the temperatures of 1450°C. The microstructure of the cast specimens was analyzed by optical and scanning electron microscopes. Clemex Image Analyzer (CIA) was used to evaluate graphite nodule count, graphite nodules area fraction, roundness and diameter of the nodules of the TWDI cast samples. Brinell hardness and tensile tests were also conducted on all the samples. The results show that by using stepped runner gating system with uncoated and coarse sand grain size mould, roundness and graphite nodule counts decrease. However, graphite nodules diameter and area fraction increase. The results also show that finer sand grain size and coated mould produce longer distance of molten metal travel.     

Pumped-storage unit commitment with considerations for energy demand,economics, and environmental constraints

Aside from their zero fuel costs, the pumped-storage units can reduce emissions of thermal generating units. The objective of this study is to investigate (a) thermal unit commitment with considerations for environmental constraints (ECUC), and (b) pumped-storage and thermal unit commitment with considerations for environmental constraints (PSECUC) based on a new optimization methodology. The PSECUC determines the start-up and shut-down schedules of pumped-storage and thermal generating units that meet the required demand so that the costs for fuel, start-up, and emissions (TC) are minimized. For the ECUC (thermal generating units only), the results show improvements of 0.03 and 0.50% in TC and excess emissions (EXEM), respectively. For the PSECUC, it is determined that 2-pumped-storage units can simultaneously decrease the TC and EXEM by 1.20 and 60%, respectively.