Mechanical and radiation attenuation properties of conventional and heavy concrete with diverse aggregate and water/cement ratios

Ovim istraživanjem predstavljaju se rezultati sveobuhvatnog laboratorijskog rada kojemu je cilj ispitati mehanička svojstva i svojstva smanjenja zračenja teških betona u kojima se kao agregat koristio pirit, krom i magnetit te betona normalne težine koji su se proizveli s tri različita vodocementna omjera (v/c = 0,4/0,5/0,6). U laboratoriju su provedena ispitivanja tlačne čvrstoće, brzine prolaska ultrazvuka, eksperimentalni modul elastičnosti te koeficijenta prigušenja mase tih betona. Na temelju provedenih ispitivanja utvrđeno je da betoni normalne težine i teški betoni imaju slično ponašanje u smislu tlačne čvrstoće i modula elastičnosti. U slučaju teških betona (njihovi v/c omjeri povećani su uslijed konstantne količine vode te smanjene količine cementa), gustoća se povećava zbog povećanja količine agregata veće gustoće u odnosu na cement u sastavu betona. To je razlog zašto teški betoni koji su proizvedeni s većim v/c omjerom te koji su manje čvrstoće mogu apsorbirati više rendgenskih zraka. Koeficijenti prigušenja mase konvergiraju pri visokim energetskim razinama kod teških i normalnih betona različitih gustoća.This paper presents the results of comprehensive laboratory work conducted for investigating the mechanical and radiation attenuation characteristics of heavyweight concrete produced with pyrite, chromium, and magnetite aggregates and normal weight concretes produced with three different water/ cement (w/c) ratios. Various experiments were conducted to determine the compressive strengths, ultrasound transmission velocities, experimental elasticity modules, and mass attenuation coefficients of these concretes. Heavy and normal weight concretes exhibited similar behaviour in terms of compressive strength and elasticity modules. In heavyweight concretes, with increased w/c ratios (by keeping the amount of water constant and decreasing the amount of cement), the corresponding density increased due to the increase in the amount of high-density aggregates rather than cement in the composition of concrete. Thus, heavyweight concretes produced with a high w/c ratio and low strength can absorb more X-rays. Mass attenuation coefficients converge in heavy and normal weight concretes with different densities at high energy levels

Structural and Electronic Properties of Ti Doped Aluminum Clusters: Density Functional Theory Calculations

WOS: 000306298900013A systematic study of the titanium doped aluminum clusters with various spin multiplicities have been performed by using Density Functional Theory calculations at the B3LYP/6-311++G(d, p) level. Several properties including equilibrium geometries, electronic states, relative energy, vibrational frequencies, dipole moment, spin densities and charges have been investigated. For pure aluminum clusters up to five atoms, the lowest isomers are planar; the clusters containing six and seven atoms the most stable isomers are three-dimensional structure. For the most stable structures of Titanium doped Aluminum clusters, Al2Ti is planar, the rest of all the models are three-dimensional

Evolution of the electronic structure and properties of charged titanium doped aluminum nanoclusters

WOS: 000324471100077A systematic study of the titanium doped aluminum clusters with various spin multiplicities have been performed by using Density Functional Theory calculations at the B3LYP/6-311++G(d,p) level. The HOMO-LUMO energy gap, ionization potential (IP), electron affinity (EA), Adiabatic Electron Affinity (AEA), Vertical Electron Affinity (VDE) and vertical detachment energy (VDE) are also computed for the most stable isomer of each cluster. (C) 2013 Elsevier B.V. All rights reserved.Ahi Evran UniversityAhi Evran University [FEN. 4003.12.013]Y. Erdogdu would like to thank Ahi Evran University Research Fund for its financial support. Project No. FEN. 4003.12.013. Computing resources used in this work were provided by the National Center for High Performance Computing of Turkey (UYBHM)

Determination of the Pozzolanic Activities of Trachyte and Rhyolite and Comparison of the Test Methods Implemented

WOS: 000530823000001Natural pozzolanas should be evaluated in terms of sustainability as well as their contribution to concrete durability. Therefore, the use of such materials in the production of cement as well as concrete industry has been gaining importance recently. in this study, the pozzolanic activities of ground trachyte and rhyolite, known as volcanic tuffs, were investigated in accordance with TS 25 standard. Pozzolanic properties of such materials, along with their pozzolanic activity indices, are investigated comparatively by the Frattini method, strength activity index, X-ray diffraction and thermogravimetric analysis. the morphologies of ground trachyte and rhyolite were also studied using SEM analysis. Based on the results obtained, the mortar samples containing blast furnace slag (BFS), fly ash (FA), trachyte and rhyolite were met the acceptable pozzolanic activity index at the end of 28 days with values of 90, 87, 89, 87, respectively. on the other hand at the end of 90 days, while the mortar samples containing BFS, FA and trachyte were met the acceptable pozzolanic activity index, that of containing rhyolite did not meet the acceptable pozzolanic activity index, with values of 93, 85, 87, 80, respectively. the pozzolanic activity index of the rhyolite was found to be quite close to that of the FA; however, the trachyte had a pozzolanic activity index close to the BFS. Comparisons of the methods implemented in the analyses were also conducted. According to the statistical evaluation of the test methods, it has been found that the relationships obtained using the direct methods as well as the indirect methods independently are highly correlated. Overall, it can be concluded that the ground trachyte may be utilized as a pozzolanas in the cement industry; however, the ground rhyolite does not meet some limits prescribed by the related standard

Structural Performance Evaluation of 90 RC Buildings Collapsed during the 2011 Van, Turkey, Earthquakes

Professor Alemdar BAYRAKTAR, BSc/0000-0002-8973-9228; ALTUNISIK, Ahmet Can/0000-0002-2638-2903WOS: 000365127900002The structural performance evaluation is presented of 90 reinforced concrete (RC) buildings that collapsed during the October 23 (Ercis) and November 9 (Edremit), 2011, earthquakes in Van, Turkey. A total of 35,000 buildings are damaged or collapsed in the city center and surrounding villages after the Ercis and Edremit earthquakes. Almost all the RC buildings are affected in the region. To evaluate the structural performance of the collapsed buildings, the buildings are evaluated according to structural system properties, specification properties, material properties (concrete and reinforcement steel properties), and soil properties. The results showed that a large proportion of nonengineering RC buildings completely collapsed or were damaged heavily. Most of the RC buildings in the affected area are not designed and constructed in accordance with Turkish code. Also, it was found that 26% of the buildings do not have a building license, 66% of the buildings' ground floors were used as a commercial or retail space, 36% of the buildings lacked any structural design, 57% of the buildings were not constructed in accordance with their structural drawings, 74% of the structural drawings did not have any detail drawings and beam/column confined zones, the concrete used in many buildings did not have adequate compressive strength, aggregate dimensions were larger than the maximum aggregate diameter for concrete, 60% of the buildings were constructed with unribbed reinforcement steel, and the majority of the buildings (85%) did not have any geotechnical report. (C) 2014 American Society of Civil Engineers

Collection and Analysis of a Parkinson Speech Dataset With Multiple Types of Sound Recordings

There has been an increased interest in speech pattern analysis applications of Parkinsonism for building predictive telediagnosis and telemonitoring models. For this purpose, we have collected a wide variety of voice samples, including sustained vowels, words, and sentences compiled from a set of speaking exercises for people with Parkinson's disease. There are two main issues in learning from such a dataset that consists of multiple speech recordings per subject: 1) How predictive these various types, e. g., sustained vowels versus words, of voice samples are in Parkinson's disease (PD) diagnosis? 2) How well the central tendency and dispersion metrics serve as representatives of all sample recordings of a subject? In this paper, investigating our Parkinson dataset using well-known machine learning tools, as reported in the literature, sustained vowels are found to carry more PD-discriminative information. We have also found that rather than using each voice recording of each subject as an independent data sample, representing the samples of a subject with central tendency and dispersion metrics improves generalization of the predictive model