Performance analysis of the tracking of the global extreme on multimodal patterns using the Asymptotic Perturbed Extremum Seeking Control scheme

This paper presents the capability of the Asymptotic Perturbed Extremum Seeking Control (aPESC) scheme to track the Global Extreme on multimodal patterns. The multimodal patterns are simulated based on power characteristics generated by a photovoltaic (PV) array under Partial Shading Conditions (PSCs). The aPESC scheme is tested to evaluate the performance of locating, searching and tracking of the Global Maximum Power Point (GMPP). The following performance indicators such as the searching resolution, tracking accuracy, tracking efficiency, and tracking speed are used to compare the performance of the GMPP tracking (GMPPT) algorithms. The aPESCH1 scheme proposed has been implemented in MATLAB/Simulink package to evaluate the performance indicators mentioned above. The results prove that the proposed aPESCH1 scheme is effective and simple to be implemented.     

Electrosynthesis of hierarchical Cu2O–Cu(OH)2 nanodendrites supported on carbon nanofibers/poly(para-phenylenediamine) nanocomposite as high-efficiency catalysts for methanol electrooxidation

The development of highly efficient catalysts using inexpensive and earth-abundant metals is a crucial factor in a large-scale commercialization of direct methanol fuel cells (DMFCs). In this study, we explored a new catalyst based on copper nanodendrites (CuNDs) supported on carbon nanofibers/poly (para-phenylenediamine) (CNF/PpPD) nanocomposite for methanol oxidation reaction (MOR). The catalyst support was prepared on a carbon paste electrode by electropolymerization of para-phenylenediamine monomer on a drop-cast carbon nanofibers network. Afterwards, CuNDs were electrodeposited on the nanocomposite through a potentiostatic method. The morphology and the structure of the prepared nanomaterials were characterized by transmission electron microscope, scanning electron microscope, energy dispersive X-ray, X-ray diffraction, and X-ray photoelectron spectroscope. The results suggested that a three-dimensional nanodendritic structure consisting of Cu₂O and Cu(OH)₂ formed on the hybrid CNF/PpPD nanocomposite. The catalytic performance of CuNDs supported on CNF, PpPD and CNF/PpPD was evaluated for MOR under alkaline conditions. The CNF/PpPD/CuNDs exhibits a highest activity (50 mA cm^?2) and stability toward MOR over 6 h, with respect to CNF/CuNDs (40 mA cm^?2) and PpPD/CuNDs (36 mA cm^?2). This inexpensive catalyst with high catalytic activity and stability is a promising anode catalyst for alkaline DMFC applications.     

Furnace smelting and extractive metallurgy of red mud: Recovery of TiO2, Al2O3 and pig iron

Turkish red mud (bauxite waste) has been mixed with dolomite and coke, pelletized and sintered at 1100°C, and finally smelted at 1550°C to produce pig iron and a slag. The slag was leached with 30% H₂SO₄ at 90°C. The leachate was diluted, ferric iron was reduced with SO₂, and extracted with 5% D2EHPA solution in kerosene. Silica and Al₂O₃ were recovered from the remaining aqueous solution, while the organic extract was stripped with 10% Na₂CO₃ solution, finally hydrolysed and calcined to produce pigment-grade TiO₂. The titanium recovery efficiency on the basis of slag weight was 84·7%. The extractive separation of titanium from both valencies of iron was investigated as a function of pH and time. A stoichiometric flowsheet for the whole process has been developed. ©1997 SCI     

Pore memory of macroporous styrene–divinylbenzene copolymers

The variation of the pore structure of styrene–divinylbenzene (S–DVB) copolymer beads with the drying conditions was investigated. Macroporous S–DVB copolymer beads with various DVB contents were prepared in the presence of toluene‐cyclohexanol mixtures as a diluent. It was found that the pores of 10¹‐nm radius, corresponding to the interstices between the microspheres, collapse upon drying of the copolymers from toluene. The collapsed pores reexpand if the copolymers were dried from methanol. The collapse–reexpansion process of the pores was found to be reversible, indicating that the actual pore structure formed during the crosslinking copolymerization is memorized by the copolymer network. The magnitude of the pore structure variation increased on worsening the polymer–diluent interactions during the gel formation process due to the simultaneous increase in crosslink density distribution. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 1055–1062, 1999     

Swelling behavior of polystyrene networks in some aliphatic esters and linear polystyrene solutions

Summary Polystyrene networks were synthesized by free radical polymerization of styrene in the presence of dibenzoyl peroxide as an initiator, divinylbenzene as a crosslinker at 50 °C in toluene under nitrogen atmosphere. The swelling behavior of the synthesized polystyrene networks were studied at different temperatures in methyl acetate, ethyl acetate, propyl acetate, isopropyl acetate, butyl acetate, isobutyl acetate, tert-butyl acetate, and isopentyl acetate. Equations were given for the variation of the polymer-solvent interaction parameter, χ₁₂, as a function of reciprocal absolute temperature in the temperature range from 25 to 75 °C. Polystyrene networks were swollen in linear polystyrene solutions in toluene of different concentrations. Linear polystyrene samples were almost monodisperse and of high molecular weight. The equilibrium swelling degrees were evaluated using the Flory-Rehner theory. The relation of volume swelling ratio, q_v, to the volume fraction of the linear polymer in solution, φ, was evaluated and characterized by interaction parameter of crosslinked polystyrene with linear polystyrene, χ₂₃. The parameter χ₂₃ was found around zero as expected from mixtures of similar chemical structures by extrapolating the values of χ₂₃ at tested concentrations to zero solvent concentration.     

Shear strength of calabrian pine (Pinus brutia Ten.) bonded with polyurethane and polyvinyl acetate adhesives

In this study, the change in shear strength on radial and tangential surfaces of Calabrian pine (Pinus brutia Ten.) wood having different roughness values as the result of sawing with a circular ripsaw, planning, and sanding, and bonded with polyurethane (PU) and polyvinyl acetate (PVAc) adhesives at the pressure levels of 3, 6, and 9 kg f/cm² were studied. A total of 360 specimens of each, prepared with the objective of being able to determine the effect of the variables on bond performance, were subjected to the shear test in the universal test machine in accordance with the ASTM D 905–98 standard. The values obtained were analyzed statistically and the results were interpreted. The highest shear strength (11.83 N/mm²) for plane of cut was obtained on the tangential surface after sanding and applying PVAc adhesive with a pressing pressure of 9 kg f/cm². The lowest shear strength (6.01 N/mm²) was obtained in the joinings made on the planed surfaces by using PU adhesive and a pressing pressure of 3 kg f/cm². The highest shear strength (9.10 N/mm²) on the radial surface was obtained after sanding and applying PVAc adhesive and pressing with a pressure of 6 kg f/cm². The lowest shear strength (3.76 N/mm²) was obtained in the specimens whose surfaces were sanded and by using PU adhesive and with a pressing pressure of 3 kg f/cm². In general, in the radial surfaces, just like in the tangential surfaces, the specimens bonded with PVAc produced a higher shear strength compared to those glued with PU. According to these results, it is definitely necessary to sand the surfaces prior to the bonding process to have a higher shear strength. The bonding process should be made on the tangential surfaces with higher pressures. The PVAc adhesive should be preferred instead of the PU adhesive. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4856–4867, 2006     

Seismic vulnerability, behavior and design of tunnel form building structures

Multi-story reinforced concrete tunnel form buildings are one of the common structural types in regions prone to high seismic risk due to the buildings inherent earthquake resistance and ease of construction. Despite their good performance during earthquakes in 1999 in Turkey, and abundance of such structures scattered worldwide, current seismic codes and design provisions provide insufficient guidelines for their seismic design. As a compensatory measure, a series of modal and nonlinear static analyses are conducted by emphasizing the characteristic dynamic behavior of tunnel form buildings including impacts of wall-to-wall and wall-to-slab interaction and effects of torsion and wall-openings on the load transfer mechanism and seismic performance. A new formula for explicit determination of their fundamental period is developed in addition to a recommended response reduction factor and reinforcement detailing around shear-wall openings.     

Micro‐ and nanoscale structures of mesiodens dentin: Combined study of FTIR and SAXS/WAXS techniques

A mesiodens is the most common type of supernumerary tooth present in conjunction to normal dentition. A mesiodens may commonly occur in the central region of the upper or lower jaw. A mesiodens is different from normal teeth in terms of structure and shape. The aim of this study is to evaluate the micro‐ and nanoscale structural properties of mesiodens dentin by combined small‐ and wide‐angle X‐ray scattering (SAXS/WAXS) and Fourier transform infrared (FTIR) spectroscopy. Five freshly extracted, noncarious mesiodens and five normal dentin disks prepared from human incisor teeth were compared. Using FTIR, the phosphate‐to‐amide I, carbonate‐to‐phosphate, and carbonate‐to‐amide I band area ratios and the crystallinity index were quantified. SAXS/WAXS were used to study the nanostructure of mesiodens. An increase in the mineral content in the mesiodens dentin with respect to the normal group was found. Crystallinity was also significantly increased and the protein content decreased in the mesiodens dentin compared with that of normal dentin. SAXS/WAXS results revealed that mesiodens dentin has a more calcified tissue. Further, SAXS analysis revealed a nonuniform distribution of dentin fibrils in mesiodens. Microsc. Res. Tech., 78:52–58, 2015. © 2014 Wiley Periodicals, Inc.