Effect of salt crystallization on stones of historical buildings and monuments,Konya, Central Turkey

In this study, we investigated the chemical and physical properties of the volcanic rocks used as building stones in historical places and monuments. The chemical weathering effect of salt crystallization on these stones was measured on the laboratory conditions (in most cases, used samples were very small). For this purpose, the dry weight loss (DWL) test was conducted. The rocks of dacite, andesite and tuffs of volcanic origin have different durability against salt crystallization. The most stable rocks are dacites (DWL 2.06%) which were used in the construction of Hittite monuments at Eflatun. The durability of the stones is closely related to their chemical, mineralogical, petrographical and mechanical properties. The stones used in the historical buildings are generally much more stable than present-day building stones.     

Multiple adaptive‐network‐based fuzzy inference system for the synthesis of rectangular microstrip antennas with thin and thick substrates

A method based on multiple adaptive‐network‐based fuzzy inference system (MANFIS) is presented for the synthesis of electrically thin and thick rectangular microstrip antennas (MSAs). MANFIS is an extension of a single‐output adaptive‐network‐based fuzzy inference system to produce multiple outputs. Six optimization algorithms, least‐squares, nelder‐mead, genetic, hybrid learning, differential evolution and particle swarm, are used to identify the parameters of MANFIS. The synthesis results of MANFIS are in very good agreement with the experimental results available in the literature. When the performances of MANFIS models are compared with each other, the best result is obtained from the MANFIS model optimized by the least‐squares algorithm. © 2008 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2008.     

The Effect of Gd Concentration on the Physical and Magnetic Properties of Bi1.7Pb0.3-xGdxSr2Ca3Cu4O12+y Superconductors

Bi–Pb–Gd–Sr–Ca–Cu–O bulk samples with nominal composition Bi_1.7Pb _0.3-xGd_xSr₂Ca₃Cu₄O_12+y (x=0.01, 0.05, 0.075, 0.10) were prepared by the melt-quenching method. The effects of different Gd doping on the structure have been investigated by electrical resistance, scanning electron micrographs, XRD, magnetization and magnetic hysteresis loop measurements. The magnetization measurements have been carried out as a function of magnetic field for fields up to 5 kOe at temperatures well below the zero resistance temperatures of the annealed samples. It has been found that the high-T_c superconducting phase, (2 2 2 3), is formed in the sample A with concentration x = 0.01, annealed at 840°C for 120 h. However, with increasing Gd³⁺ doping for Pb²⁺ the (2 2 2 3) phase gradually transforms into the (2 2 1 2) phase. The magnitudes of magnetization and initial susceptibility, | M | and | dM/dH|, and the hysteresis loop areas decrease with increasing Gd concentration x and/or temperature T. The fast decreases in | M|, | dM/dH |, and the hysteresis loop areas related to the superconducting volume, with increasing x and/or T seem to imply an existence of flux pinning centres in our samples. In order to support this implication the critical current densities J_c, of the samples, have been estimated at two fixed temperatures, 9 and 30 K. Our data have indicated that J_c decreases with increasing temperature and/or Gd concentration, as expected.     

Design and implementation of a random neural network routing engine

Random neural network (RNN) is an analytically tractable spiked neural network model that has been implemented in software for a wide range of applications for over a decade. This paper presents the hardware implementation of the RNN model. Recently, cognitive packet networks (CPN) is proposed as an alternative packet network architecture where there is no routing table, instead the RNN based reinforcement learning is used to route packets. Particularly, we describe implementation details for the RNN based routing engine of a CPN network processor chip: the smart packet processor (SPP). The SPP is a dual port device that stores, modifies, and interprets the defining characteristics of multiple RNN models. In addition to hardware design improvements over the software implementation such as the dual access memory, output calculation step, and reduced output calculation module, this paper introduces a major modification to the reinforcement learning algorithm used in the original CPN specification such that the number of weight terms are reduced from 2n/sup 2/ to 2n. This not only yields significant memory savings, but it also simplifies the calculations for the steady state probabilities (neuron outputs in RNN). Simulations have been conducted to confirm the proper functionality for the isolated SPP design as well as for the multiple SPP's in a networked environment.     

Interface evolution of TiAl／Ti6242 transient liquid phase joint using Ti, Cu foils as insert metals

The interface evolution of TiAl/Ti6242 joint produced by transient liquid phase(TLP) bonding with Ti,Cu foils as insert metals was investigated. The results show that the surface oxide layer on TiAI plays a very important role in the formation process of the joint. A ‘bridge‘ effect is observed because of the presence of the oxide layer on the surface of TiAl. The diffusion behavior of Cu atoms in TiAl is strongly controlled by the vacancies beneath the surface of TiAl. Based on the interface diffusion and interface wettability, a mechanism for the effect of bonding pressure, bonding temperature, holding time and stacking sequence of the insert foils on the joint formation process were proposed.     

Preparation and catalytic properties of modified PGMA-based pH-responsive hydrogel films as a novel template for in situ synthesis of Au,Ag, and Au:Ag nanoparticles

Metal-nanoparticle (M-NP)-modified glycidyl methacrylate (GMA)-based hydrogel film composites were synthesized and assessed for their catalytic activities by reducing para-nitrophenol (p-NP) to para-aminophenol (p-AP) with sodium borohydride. Poly(ethylene glycol)methyl ether-block-poly(glycidyl methacrylate)-block-poly(methyl methacrylate) (MPEG-b-PGMA-b-PMMA) triblock copolymer was synthesized via atom transfer-radical polymerization. The epoxy ring of the PGMA blocks was opened by the addition of 1-methylpiperazine. The resulting bifunctional polymer containing 2-hydroxy-3-methyl piperazinepropyl methacrylate units was used to synthesize novel crosslinked hydrogel films by quaternization of the tertiary amine (methylpiperazine) with 1,2-bis(2-iodoethoxy)ethane. The synthesized hydrogel film swelled in aqueous solution when the pH was changed from basic to acidic. The prepared MPEG-b-PHMPPMA-b-PMMA hydrogel film was used as an immobilizing matrix to form monometallic silver (Ag) and gold (Au) and bimetallic alloy gold:silver (Au:Ag) nanoparticles. The M-NP/hydrogel film composites were characterized by transmission electron microscopy, scanning electron microscopy, thermogravimetric analysis, and ultraviolet–visible spectrophotometry. The synthesized M-NP/hydrogel film composites showed good catalytic activity to reduce p-NP to p-AP. The composites were also found to be reusable as their activity only slightly dropped after 10 consecutive uses. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48360.     

Computation of the resonant frequency of electrically thin and thick rectangular microstrip antennas with the use of fuzzy inference systems

A new method for calculating the resonant frequency of electrically thin and thick rectangular microstrip antennas, based on the fuzzy inference systems, is presented. The optimum design parameters of the fuzzy inference systems are determined by using the classical, modified, and improved tabu search algorithms. The calculated resonant frequency results are in very good agreement with the experimental results reported elsewhere. © 2000 John Wiley & Sons, Inc. Int J RF and Microwave CAE 10: 108–119, 2000.     

The microwave-assisted synthesis and structural characterization of novel,dithia-bridged polymeric phthalocyanines containing a substituted thiophenylamine Schiff base

Novel polymeric metal-free and metallo(Cu(II), Co(II), Ni(II), Zn(II) and Pb(II))–phthalocyanine complexes were synthesized using microwave irradiation and the products were purified by several (crystallization and preparative thin layer) techniques. The newly prepared compounds were characterized by a combination of elemental analyses, IR, ¹H/¹³C NMR, ¹H–¹H COSY, MS and UV–Vis spectroscopy. In order to better understand the spectroscopy data (especially for ¹H/¹³C NMR and ¹H–¹H COSY techniques), computational calculations were used for characterization at DFT/6-31G(d) level. The electronic spectra exhibited an intense π → π* transition with characteristic Q and B bands of the phthalocyanine core.