An Investigation of the Seismic Behaviour of an Ancient Masonry Bastion Using Non-Destructive and Numerical Methods

Determining the structural behavior of masonry structures is a challenge due to their lack of homogeneity. The seismic behavior of masonry structures is especially complex. The aim of this study was to examine the structural behavior of Za?anos Bastion using both experimental and numerical methods. The Operational Modal Analysis technique, including the Enhanced Frequency Domain Decomposition Method, and the Stochastic Subspace Identification Method were used to illustrate experimentally the dynamic characteristic of the bastion. A finite element model was developed using ANSYS software in order that the dynamic characteristics of the bastion, including natural frequencies and mode shapes, could be calculated numerically. Seismic analysis was carried out using the 1999 Kocaeli earthquake ground motion record to determine the linear and nonlinear seismic behavior of the bastion. The Turkish Earthquake Code and its general technical specifications were used to evaluate the seismic results. The results show that the maximum and minimum principal stresses exerted on the masonry components exceeded the code requirements at some points, but in general the requirements for the stresses were satisfied.     

The prediction of maximum temperature for single chips’ cooling using artificial neural networks

A CFD simulation usually requires extensive computer storage and lengthy computational time. The application of artificial neural network models to thermal management of chips is still limited. In this study, the main objective is to find a neural network solution for obtaining suitable thickness levels and material for a chip subjected to a constant heat power. To achieve this aim a neural network is trained and tested using the results of the CFD program package Fluent. The back-propagation learning algorithm with three different variants, single layer and logistic sigmoid transfer function is employed in the network. By using the weights of the network, various formulations are designed for the output. The network has resulted in R ² values of 0.999, and the mean% errors smaller than 0.8 and 0.7 for the training and test data, respectively. The analysis is extended for different thickness and input power values. Comparison of some randomly selected results obtained by the neural network model and the CFD program has yielded a maximum error of 1.8%, mean absolute percentage error of 0.55% and R ² of 0.99994.     

Experimental and theoretical investigation of the drilling of alumina ceramic using Nd:YAG pulsed laser

Alumina ceramics have found wide range of applications from semiconductors, communication technologies, medical devices, automotive to aerospace industries. Processing of alumina ceramics is rather difficult due to its high degree of brittleness, hardness, low thermal diffusivity and conductivity. Rapid improvements in laser technologies in recent years make the laser among the most convenient processing tools for difficult-to-machine materials such as hardened metals, ceramics and composites. This is particularly evident as lasers have become an inexpensive and controllable alternative to conventional hole drilling methods. This paper reports theoretical and experimental results of drilling the alumina ceramic with thicknesses of 5 mm and 10.5 mm using milisecond pulsed Nd:YAG laser. Effects of the laser peak power, pulse duration, repetition rate and focal plane position have been determined using optical and Scanning Electron Microscopy (SEM) images taken from cross-sections of the drilled alumina ceramic samples. In addition to dimensional analysis of the samples, microstructural investigations have also been examined. It has been observed that, the depth of the crater can be controlled as a function of the peak power and the pulse duration for a single laser pulse application without any defect. Crater depth can be increased by increasing the number of laser pulses with some defects. In addition to experimental work, conditions have been simulated using ANYS FLUENT package providing results, which are in good agreement with the experimental results.     

Thermal and microstructural investigation of Cu–Al–Mn–Mg shape memory alloys

There are many studies to improve the properties of Cu–Al–Mn shape memory alloys, such as high transformation temperatures, ductility and workability. Most of them have been performed by adding a quaternary component to the alloy. In this study, the effect of trace Mg addition on transformation temperatures and microstructures of three different quaternary Cu–Al–Mn–Mg alloys has been investigated using thermal analysis, optical microscopy and XRD techniques. The transformation temperatures are within the range of 120–180 °C, and they have not changed significantly on decreasing the Mn content, replacing with Mg. The fine precipitates have been observed in the alloys with the Mg content up to 1.64 at%. Calculated entropy change and XRD analysis reveal that the alloys with high Al content have mainly 18R-type structure which could be responsible for good ductility and workability.     

Microwave-Induced Synthesis of 2-Aminoimidazolines Under Neat Conditions

2-Aminoimidazolines were synthesized by the nucleophilic substitution reaction of 2-methylmercapto-4,5-dihydroimidazole hydroiodide with various amine compounds under neat conditions.     

A Selective Film Based on Poly(3‐octylthiophene) Doped with Dihydroxyanthraquinone Sulfonate

A stable film of poly(3‐octylthiophene)–dihydroxyanthraquinone sulfonate has been synthesized electrochemically in non‐aqueous solution. The incorporation of dihydroxyanthraquinone sulfonate as an anionic complexing ligand into poly(3‐octylthiophene) film during electropolymerization was achieved and copper ions were accumulated by reduction on the electrode surface. The presence of dihydroxyanthraquinone sulfonate during the electrochemical polymerization of 3‐octylthiophene is shown to impact the sensitivity and the stability of the organic conducting film electrode response. The electroanalysis of copper(II) ions using conducting polymer electrode was achieved by differential pulse anodic stripping voltammetry with remarkable selectivity. The analytical performance was evaluated and linear calibration graphs were obtained in the concentration range of 50–400 ng mL^?1 copper(II) ion for 240 seconds accumulation time and the limit of detection was found to be 7.8 ng mL^?1. To check the selectivity of the proposed stripping voltammetric method for copper(II) ion, various metal ions as potential interferents were tested. The developed method was applied to copper(II) determination in certified reference material, NWRI‐TMDA‐61, trace elements in fortified water.     

Transport of Lead (Pb<Superscript>2+</Superscript>) Ions Through Silty-Clayey Soils Under Acidic Conditions

This study aimed to identify effects of pH on the transport of Pb²⁺ ions through a saturated silty-clayey soil layer by using advection–dispersion equation (ADE). The predictive accuracy of the solution of ADE depends on the proper determination of the retardation by adsorption and, therefore, the adsorption mechanism of lead onto silty-clayey soil was investigated first by performing batch equilibrium experiments. These results showed that the sorption mechanism of lead onto silty-clayey soil depended on pH and could be best described by the Langmuir isotherm. Based on the results of the sequential experiments, it was also concluded that the pH dependent charges in silty-clayey soil were mainly associated with the surfaces of carbonates and the specific adsorption of lead ions. The numerical solutions of the combined form of ADE with the Langmuir isotherm indicated that the migration profiles of lead in silty-clayey soil were a strong function of the parameters of the Langmuir isotherm rather than the infiltration velocity.     

Voltammetric Determination of Mercury(II) at Poly(3‐hexylthiophene) Film Electrode. Effect of Halide Ions

The well‐known method for the determination of mercury(II), which is based on the anodic stripping voltammetry of mercury(II), has been adapted for applications at the thin film poly(3‐hexylthiophene) polymer electrode. Halide ions have been found to increase the sensitivity of the mercury response and shift it more positive potentials. This behavior is explained by formation of mercuric halide which can be easily deposited and stripped from the polymer electrode surface. The procedure was optimized for mercury determination. For 120 s accumulation time, detection limit of 5 ng mL^?1 mercury(II) has been observed. The relative standard deviation is 1.3% at 40 ng mL^?1 mercury(II). The performance of the polymer film studied in this work was evaluated in the presence of surfactants and some potential interfering metal ions such as cadmium, lead, copper and nickel.