Mechanical properties characterization of different types of masonry infill walls

It is remarkable, the recent advances concerning the development of numerical modeling frameworks to simulate the infill panels’ seismic behavior. However, there is a lack of experimental data of their mechanical properties, which are of full importance to calibrate the numerical models. The primary objective of this paper is to present an extensive experimental campaign of mechanical characterization tests of infill masonry walls made with three different types of masonry units: lightweight vertical hollow concrete blocks and hollow clay bricks. Four different types of experimental tests were carried out, namely: compression strength tests, diagonal tensile strength tests, and flexural strength tests parallel and perpendicular to the horizontal bed joints. A total amount of 80 tests were carried out and are reported in the present paper. The second objective of this study was to compare the mechanical properties of as-built and existing infill walls. The results presented and discussed herein, will be in terms of strain-stress curves and damages observed within the tests. It was observed a fragile behavior in the panels made with hollow clay horizontal bricks, without propagation of cracks. The plaster increased the flexural strength by 57%.     

Stochastic collocation-based nonlinear analysis of concrete bridges with uncertain parameters

This paper focuses on the stochastic response of concrete bridges considering uncertainty in bearing and abutment stiffness. A multi-span simply supported bridge with concrete girders is selected. A 3D-dimensional model is prepared, and nonlinear response history analyses are performed. For the numerical dynamic simulation, the non-sampling stochastic method based on generalized polynomial chaos (gPC) expansion is utilised. The uncertain parameters include the vertical and shear stiffness of bearings and the lateral stiffness of abutments are presented by the truncated gPC expansions. Furthermore, the system response such as base shear, acceleration, velocity and displacement in different columns is presented by gPC expansion with unknown deterministic coefficients. The stochastic Galerkin projection is employed to calculate a set of deterministic equations. A non-intrusive solution, as a set of collocation points, determines the unknown gPC coefficients of the system response and the results are compared with Monte Carlo simulations. The key advantage of spectral discretization is the combination of the mentioned method with the spatial discretization, e.g. finite element model. This study also emphasises the accuracy in results and time efficiency of the proposed non-sampling method for uncertainty quantification of stochastic systems comparing to sampling procedure (e.g. Monte Carlo simulation).     

Polyhedral object recognition by indexing

In computer vision, the indexing problem is the problem of recognizing a few objects in a large database of objects while avoiding the help of the classical image-feature-to-object-feature matching paradigm. In this paper we address the problem of recognizing three-dimensional (3-D) polyhedral objects from 2-D images by indexing. Both the objects to be recognized and the images are represented by weighted graphs. The indexing problem is therefore the problem of determining whether a graph extracted from the image is present or absent in a database of model graphs. We introduce a novel method for performing this graph indexing process which is based both on polynomial characterization of binary and weighted graphs and on hashing. We describe in detail this polynomial characterization and then we show how it can be used in the context of polyhedral object recognition. Next we describe a practical recognition-by-indexing system that includes the organization of the database, the representation of polyhedral objects in terms of 2-D characteristic views, the representation of this views in terms of weighted graphs and the associated image processing. Finally, some experimental results allow the evaluation of the system performance.     

Reports of the childhood home environment in early-onset dysthymia and episodic major depression.

This study addressed 2 questions: (a) is early-onset dysthymia associated with reports of a disturbed childhood home environment; and (b) can adverse early experiences account, at least in part, for the differing clinical presentations of dysthymia and major depression? Participants included 97 outpatients with early-onset dysthymia, 45 outpatients with episodic major depression, and 45 normal controls. The early home environment was assessed blind to diagnosis using both interview and self-report measures. Early-onset dysthymia patients reported significantly more physical and sexual abuse and poorer relationships with both parents than normal controls. In addition, patients with dysthymia reported having received significantly poorer parenting than those with episodic major depression. The results could not be accounted for by mood state effects, comorbidity with borderline and antisocial personality disorder, or comorbid major depression. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Metallization thickness in bilateral and unilateral Finlines

The theory and numerical results are presented to the effective dielectric constant and characteristic impedance of bilateral and unilateral finlines with metallization thickness. The full wave analysis of the transverse transmission line — TTL method is used to determine the electromagnetic fields of the structure in Fourier transform domain — FTD. Applying the suitable boundary conditions and the moment method, a homogeneous matrix system is obtained and the effective dielectric constant is extracted. The characteristic impedance is obtained using the relation between the voltage in slot and the transmitted power. Computational programs are developed to obtain numerical results to the effective dielectric constant and characteristic impedance.     

Similarity measures,penalty functions,and fuzzy entropy from new fuzzy subsethood measures

In this study, we discuss a new class of fuzzy subsethood measures between fuzzy sets. We propose a new definition of fuzzy subsethood measure as an intersection of other axiomatizations and provide two construction methods to obtain them. The advantage of this new approach is that we can construct fuzzy subsethood measures by aggregating fuzzy implication operators which may satisfy some properties widely studied in literature. We also obtain some of the classical measures such as the one defined by Goguen. The relationships with fuzzy distances, penalty functions, and similarity measures are also investigated. Finally, we provide an illustrative example which makes use of a fuzzy entropy defined by means of our fuzzy subsethood measures for choosing the best fuzzy technique for a specific problem.     

Comparison of the superelasticity of different nickel–titanium orthodontic archwires and the loss of their properties by heat treatment

The aim of this work is to describe and compare mechanical properties of eight widely used nickel–titanium orthodontic wires under uniform testing conditions and to determine the influence of the heat treatments on the loss of the superelasticity. Ten archwires from two batches from eight different manufacturers were evaluated. A three-point bending test was performed, in accordance with ISO 15841:2006, on 80 round nickel–titanium archwire segments of 0.016?inch. To obtain a load-deflection curve, the centre of each segment was deflected to 3.1?mm and then unloaded until force became zero. On the unloading curve, deflection at the end of the plateau and forces delivered at that point, and at 3, 2, 1 and 0.5?mm of deflection, were recorded. Plateau slopes were calculated from 3 and from 2?mm of deflection. Data obtained were statistically analysed to determine inter-brand, intra-brand and inter-batch differences (P?<?0.05). The results show that at 2?mm of deflection, maximum differential force exerted among brands [Nitinol SuperElastic (1.999N)—Sentalloy M (1.001?N)] was 0.998?N (102?gf). The Nitinol SuperElastic plateau slope (0.353?N/mm) was the only one that was statistically different from 2?mm of deflection, as compared with the other brand values (0.129–0.155?N/mm). Damon Optimal Force described the gentlest slope from 3?mm of deflection (0.230?N/mm) and one of the longest plateaus. Titanol and Orthonol showed the most notable intra-brand differences, whereas inter-batch variability was significant for Nitinol (Henry Schein), Euro Ni–Ti and Orthonol. Superelasticity degree and exerted forces differed significantly among brands. Superelasticity of Nitinol SuperElastic was not observed, while Damon Optimal Force and Proclinic Ni–Ti Superelástico (G&H) showed the most superelastic curves. Intra-brand and inter-batch differences were observed in some brands. In all cases, the heat treatment at 600?°C produces precipitation in the matrix. The precipitates are rich in titanium and this fact produce changes in the chemical composition of the matrix and the loss of the superelasticity. At 400?°C these precipitates are not produced and the forces delivered by the wires are very similar with wires untreated.     

On admissible total orders for typical hesitant fuzzy consensus measures

In this paper, we discussconsensus measures for typical hesitant fuzzy elements (THFE), which are the finite and nonempty fuzzy membership degrees under the scope of typical hesitant fuzzy sets (THFS). In our approach, we present a model that formally constructs consensus measures by means of aggregations functions, fuzzy implication-like functions and fuzzy negations, using admissible orders to compare the THFE, and also providing an analysis of consistency on them. Our theoretical results are applied into a problem of decision making with multicriteria illustrating our methodology to achieve consensus in a group of experts working with THFS.     

Influence of lanthanum carbonate phases of Ni/La0.98Sr0.02O x catalyst over the oxidative transformation of methane

This work combines the advantages of ~2 mol.% Sr/La₂O₃ (i.e. La_0.98Sr_0.02O _x ) for OCM (oxidative coupling of methane) with well-dispersed nickel over metal oxides for POM (partial oxidation of methane) to efficiently transform methane to desirable products. The catalysts were prepared by sequential impregnation and characterized by X-ray diffraction, thermogravimetric analysis, scanning electron microscopy, temperature-programmed reduction, temperature-programmed decomposition of carbonates and BET surface area measurements. The aim of this work is to find out not only the effect of the catalyst compositions over the formation and growth of carbonate phases, but also their influence over the transformation oxidative of methane. The La_0.98Sr_0.02O _x – supported Ni catalyst precursors show a strong nickel oxide–lanthana interaction, involving anionic vacancies or structural defects that induce the formation of island-like structure of La_2-x Sr _x NiO₄-type mixed oxide for 2 mol.% Ni/La_0.98Sr_0.02O _x . Higher nickel composition facilitates the formation of LaNiO₃. Surface lanthanum hydroxycarbonate formation is probably associated with a conjugated effect between lanthanum oxide and oxidized nickel phases. For high-nickel amount containing catalysts, carbonate-enriched La₂(OH)_6-2x (CO₃) _x as intermediate phase in methane reforming reaction is proposed. For low nickel composition (i.e. 2%), partial oxidation of methane could follow predominantly the pyrolysis mechanism. In which, carbon monoxide is the direct product and carbon dioxide is subsequently formed from carbon monoxide oxidation.     

Kinetic study of the effect of poly(phenyl sulfone) on the curing of an epoxy/amine resin by conventional and by temperature‐modulated differential scanning calorimetry

Kinetic studies of the curing reaction of semi‐interpenetrating polymer networks (semi‐IPNs) based on diglycidyl ether of bisphenol‐A (DGEBA) and 4,4′‐diaminodiphenylmethane (DDM), containing poly(phenyl sulfone) (PPSU), were carried out using differential scanning calorimetry (DSC) and temperature‐modulated DSC (TMDSC), under both isothermal and dynamic conditions. The curing kinetics is discussed in the framework of three kinetic models: the Kissinger and the Flynn–Wall–Ozawa models, and the autocatalytic model developed by Kamal. To describe the cured reaction in its latter stage, we used the semi‐empirical relationship proposed by Chern and Poehlein to consider the influence of diffusion on reaction rate. The cure mechanism for the system studied remained broadly autocatalytic regardless of PPSU content, and it became far more diffusion controlled at higher PPSU content and lower cure temperatures. The vitrification time of the resins was obtained with TMDSC by following the changes on the complex modulus of heat capacity, , and exhibited a strong dependence on the PPSU content in the semi‐IPN systems. Copyright © 2005 Society of Chemical Industry