Countries to benefit most from early transition to hydrogen fueled transportation: Merit factor analysis

The world consists of many countries having differences in many areas, ranging from size to economic level, from population to education, etc. Consequently, they are not going to convert to hydrogen‐fueled transportation at the same time. Some will have the right conditions to convert to clean hydrogen transportation early, and other countries will have conditions which will result in a delay in conversion to hydrogen‐fueled transportation. In order to find out which countries are the candidates for early conversion to hydrogen fueled transportation and which countries might convert to hydrogen‐fueled transportation later, an analysis has been carried out covering almost all of the countries in the world. Results indicate that the countries with higher income per capita and smaller size could convert to hydrogen‐fueled transportation earlier. Copyright © 2013 John Wiley & Sons, Ltd.     

Simulation of heat transfer for solid–liquid food mixtures in cans and model validation under pasteurization conditions

During processing of canned mixtures of solid–liquid foods, conduction and convection occur simultaneously. The literature lacks in a complete simulation study where a large number of solids are dispersed in the liquid phase, e.g. canned peas. Therefore, the objectives of this study were to determine temperature changes inside a can containing solid–liquid food mixtures. For this purpose, dispersed stationary solids (canned peas in water) in a 2D (axi-symmetrical) configuration were applied. Ansys V11 (Ansys Inc., Canonsburg, PA) was used to solve continuity, energy and momentum equations. For experiments, canned pea samples were prepared in 500 g cans, and heating process was conducted in a retort under pasteurization conditions at ≈98 °C. Temperature changes were measured using needle type thermocouples, and simulation results were validated against experimental data. This study is expected to be a significant contribution to the literature for further optimization studies and to form basis of an industrial project to improve canning process of solid–liquid mixtures.     

Improving the performance of simulated annealing in structural optimization

This study aims at improving the performance of simulated annealing (SA) search technique in real-size structural optimization applications with practical design considerations. It is noted that a standard SA algorithm usually fails to produce acceptable solutions to such problems associated with its poor convergence characteristics and incongruity with theoretical considerations. In the paper novel approaches are developed and incorporated into the standard SA algorithm to eliminate the observed drawbacks of the technique. The performance of the resulting (improved) algorithm is investigated in conjunction with two numerical examples (a 304-member braced planar steel frame, and 132-member unbraced space steel frame) designed according to provisions of the Allowable Stress Design (ASD) specification. In both examples, curves showing the variation of average acceptance probability parameter in standard and improved algorithms are plotted to verify usefulness and robustness of the integrated approaches.     

The effect of long-term ambient aging on the mechanical properties of conducting polysiloxane-polypyrrole graft copolymers

The mechanical behavior of conducting polysiloxane-polypyrrole graft copolymers has been investigated as a function of ambient oxidative aging period. Graft copolymers of N-pyrrolyl-terminated polydimethylsiloxane (SPPy) with pyrrole were synthesized electrochemically at constant potential by using p -toluene sulfonic acid as the supporting electrolyte. Mechanical tests were performed on both unwashed and dichloromethane -washed copolymers after aging. An initial decrease followed by an increase in the tensile strength and strain values was observed with aging. The conductivities and mechanical properties of the films were determined to remain almost unchanged after 6 months of aging at about 46 S/cm.     

Fuzzy associative memories for the computation of the bandwidth of rectangular microstrip antennas with thin and thick substrates

A method based on fuzzy associative memories for calculating the bandwidth of electrically thin and thick rectangular microstrip patch antennas is presented. The design parameters of the fuzzy associative memories are optimally determined by using the classical, modified and improved tabu search algorithms. The theoretical bandwidth results obtained by using the fuzzy associative memories are in very good agreement with the experimental results available in the literature.     

Effect of cesium salt of tungstophosphoric acid (Cs-TPA) on the properties of sulfonated polyether ether ketone (SPEEK) composite membranes for fuel cell applications

We have prepared composite membranes for fuel cell applications. Cesium salt of tungstophosphoric acid (Cs-TPA) particles was synthesized by aqueous solutions of tungstophosphoric acid and cesium hydroxide and, Cs-TPA particles and sulfonated (polyether ether ketone) (SPEEK) with two sulfonation degrees (DS), 60 and 70%have been used. We examined both the effects of Cs-TPA in SPEEK membranes as functions of sulfonation degrees of SPEEK and the content of Cs-TPA. The performance of the composite membranes was evaluated in terms of water uptake, ion exchange capacity, proton conductivity, chemical stability, hydrolytic stability, thermal stability and methanol permeability. The morphology of the membranes was investigated with SEM micrographs. Increasing sulfonation degree of SPEEK from 60 to 70 caused agglomeration of the Cs-TPA particles. The methanol permeability was reduced to 4.7 × 10⁻⁷ cm²/s for SPEEK (DS: 60%)/Cs-TPA membrane with 10 wt.% Cs-TPA concentration, and acceptable proton conductivity of 1.3 × 10⁻¹ S/cm was achieved at 80 °C under 100% RH. The weight loss at 900 °C increased with the addition of inorganic particles, as expected. The hydrolytic stability of the SPEEK/Cs-TPA based composite membranes was improved with the incorporation of the Cs-TPA particles into the matrix. We also noted that SPEEK60/Cs-TPA composite membranes were hydrolytically more stable than SPEEK70/Cs-TPA composite membranes. On the other hand, Methanol, water vapor, and hydrogen permeability values of SPEEK60 composite membranes were found to be lower than that of Nafion^®.     

Antibacterial activities of essential oils and extracts of Turkish Achillea,Satureja and Thymus species against plant pathogenic bacteria

BACKGROUND: The aims of this study were to examine the chemical composition of the essential oils and hexane extracts of the aerial parts of Satureja spicigera (C. Koch) Boiss., Thymus fallax Fisch. & CA Mey, Achillea biebersteinii Afan, and Achillea millefolium L. by GC and GC–MS, and to test antibacterial efficacy of essential oils and n‐hexane, chloroform, acetone and methanol extracts as an antibacterial and seed disinfectant against 25 agricultural plant pathogens. RESULTS: Thymol, carvacrol, p‐cymene, thymol methyl ether and γ‐terpinene were the main constituents of S. spicigera and T. fallax oils and hexane extracts. The main components of the oil of Achillea millefolium were 1,8‐cineole, δ‐cadinol and caryophyllene oxide, whereas the hexane extract of this species contained mainly n‐hexacosane, n‐tricosane and n‐heneicosane. The oils and hexane extracts of S. spicigera and T. fallax exhibited potent antibacterial activity over a broad spectrum against 25 phytopathogenic bacterial strains. Carvacrol and thymol, the major constituents of S. spicigera and T. fallax oils, also showed potent antibacterial effect against the bacteria tested. The oils of Achillea species showed weak antibacterial activity. Our results also revealed that the essential oil of S. spicigera, thymol and carvacrol could be used as potential disinfection agents against seed‐borne bacteria. CONCLUSION: Our results demonstrate that S. spicigera, T. fallax oils, carvacrol and thymol could become potentials for controlling certain important agricultural plant pathogenic bacteria and seed disinfectant. Copyright © 2009 Society of Chemical Industry     

Elevated-Temperature Corrosion of CoCrCuFeNiAl0.5Bx High-Entropy Alloys in Simulated Syngas Containing H2S

High-entropy alloys are formed by synthesizing five or more principal elements in equimolar or near equimolar concentrations. Microstructure of the CoCrCuFeNiAl_0.5B_x (x = 0, 0.2, 0.6, 1) high-entropy alloys under investigation is composed of a mixture of disordered bcc and fcc phases and borides. These alloys were tested gravimetrically for their corrosion resistance in simulated syngas containing 0, 0.01, 0.1, and 1 % H₂S at 500 °C. The exposed coupons were characterized using XRD and SEM. No significant corrosion was detected at 500 °C in syngas containing 0 and 0.01 % H₂S while significant corrosion was observed in syngas containing 0.1 and 1 % H₂S. Cu_1.96S was the primary sulfide in the external corrosion scale on the low-boron high-entropy alloys, whereas FeCo₄Ni₄S₈ on the high-boron high-entropy alloys. Multi-phase Cu-rich regions in the low-B high-entropy alloys were vulnerable to corrosive attack.