bluuebunny/crossref_metadata_2025 huggingface dataset:
Numerically Modeling the First Peak of the Type IIb SN 2016gkg
Authors: Piro Anthony L. , Muhleisen Marc , Arcavi Iair , Sand David J. , Tartaglia Leonardo , Valenti Stefano
Published: September 2017

Many Type IIb supernovae (SNe) show a prominent additional early peak in their light curves, which is generally thought to be due to the shock cooling of extended hydrogen-rich material surrounding the helium core of the exploding star. The recent SN 2016gkg was a nearby Type IIb SN discovered shortly after explosion, which makes it an excellent candidate for studying this first peak. We numerically explode a large grid of extended envelope models and compare these to SN 2016gkg to investigate what constraints can be derived from its light curve. This includes exploring density profiles for both a convective envelope and an optically thick steady-state wind, the latter of which has not typically been considered for Type IIb SNe models. We find that roughly

of extended material with a radius of

reproduces the photometric light curve data, consistent with pre-explosion imaging. These values are independent of the assumed density profile of this material, although a convective profile provides a somewhat better fit. We infer from our modeling that the explosion must have occurred within ≈2–3 hr of the first observed data point, demonstrating that this event was caught very close to the moment of explosion. Nevertheless, our best-fitting 1D models overpredict the earliest velocity measurements, which suggests that the hydrogen-rich material is not distributed in a spherically symmetric manner. We compare this to the asymmetries that have also been seen in the SN IIb remnant Cas A, and we discuss the implications of this for Type IIb SN progenitors and explosion models.
A Model of the Solar Chromosphere: Structure and Internal Circulation
Authors: Song P.
Published: September 2017

A model of the solar chromosphere that consists of two fundamentally different regions, a lower region and an upper region, is proposed. The lower region is covered mostly by weak locally closed magnetic field and small network areas of extremely strong, locally open field. The field in the upper region is relatively uniform and locally open, connecting to the corona. The chromosphere is heated by strong collisional damping of Alfvén waves, which are driven by turbulent motions below the photosphere. The heating rate depends on the field strength, wave power from the photosphere, and altitude in the chromosphere. The waves in the internetwork area are mostly damped in the lower region, supporting radiation in the lower chromosphere. The waves in the network area, carrying more Poynting flux, are only weakly damped in the lower region. They propagate into the upper region. As the thermal pressure decreases with height, the network field expands to form the magnetic canopy where the damping of the waves from the network area supports radiation in the whole upper region. Because of the vertical stratification and horizontally nonuniform distribution of the magnetic field and heating, one circulation cell is formed in each of the upper and lower regions. The two circulation cells distort the magnetic field and reinforce the funnel-canopy-shaped magnetic geometry. The model is based on classical processes and is semi-quantitative. The estimates are constrained according to observational knowledge. No anomalous process is invoked or needed. Overall, the heating mechanism is able to damp 50% of the total wave energy.
A Millisecond Pulsar Discovery in a Survey of Unidentified Fermi γ-Ray Sources with LOFAR
Authors: Pleunis Z. , Bassa C. G. , Hessels J. W. T. , Kondratiev V. I. , Camilo F. , Cognard I. , Grießmeier J.-M. , Stappers B. W. , Amesfoort A. S. van , Sanidas S.
Published: September 2017

Using LOFAR, we have performed a very-low-frequency (115−155 MHz) radio survey for millisecond pulsars (MSPs). The survey targeted 52 unidentified Fermi γ-ray sources. Employing a combination of coherent and incoherent dedispersion, we have mitigated the dispersive effects of the interstellar medium while maintaining sensitivity to fast-spinning pulsars. Toward 3FGL J1553.1+5437 we have found PSR J1552+5437, the first MSP to be discovered (through its pulsations) at a radio frequency <200 MHz. PSR J1552+5437 is an isolated MSP with a 2.43 ms spin period and a dispersion measure of 22.9 pc cm−3. The pulsar has a very steep radio spectral index (

2.8 ± 0.4). We obtain a phase-connected timing solution combining the 0.74 years of radio observations with γ-ray photon arrival times covering 7.5 years of Fermi observations. We find that the radio and γ-ray pulse profiles of PSR J1552+5437 appear to be nearly aligned. The very steep spectrum of PSR J1552+5437, along with other recent discoveries, hints at a population of radio MSPs that have been missed in surveys using higher observing frequencies. Detecting such steep spectrum sources is important for mapping the population of MSPs down to the shortest spin periods, understanding their emission in comparison to slow pulsars, and quantifying the prospects for future surveys with low-frequency radio telescopes like SKA-Low and its precursors.
3D Model of Crack Propagation in Particulate Ceramic Composite Containing Residual Stresses
Authors: Štegnerová Kateřina , Majer Zdeněk , Hutař Pavel , Náhlík Luboš
Published: September 2017

A crack propagation and fracture behaviour of particulate ceramic composite were investigated. Influence of 3D shape of particles on the crack propagation was studied together with influence of the presence of residual stresses, which are developed inside the composite during manufacturing process. Finite element (FE) method was used for numerical simulation of propagating crack in the composite. Basic numerical models of low-temperature co-fired ceramics (LTCC) with alumina particles homogenously dispersed in the glass matrix were developed. Volume fraction of alumina phase was 20vol.%, which is typical amount for LTCC. The results show that existence of residual stresses retards the crack propagating under conditions of sub-critical crack growth (SCG). Presented results contribute to a better understanding of the role of residual stresses in particulate ceramic composites.
Prediction of Fatigue Crack Path Based upon Green’s Function Theory
Authors: Yoshida Kazuki , Arai Masayuki
Published: September 2017

It is known that fatigue crack path has an influence on the fatigue life of the structural components. In this study, a method of predicting the crack path is developed based upon superposition of a stress intensity factor (Green’s function solution) for the crack problem subjecting to a pair of concentrated loads. This method has a benefit to give us a complete closed crack path solution, and it is easy to predict the complex crack path in comparison with a numerical prediction by finite element (FE) analysis.
SEM Study of Fatigue Crack Propagation in Chromium Martensitic Steel after LCF
Authors: Eterashvili Tamaz , Abuladze G. , Kotiashvili L. , Dzigrashvili T. , Vardosanidze M.
Published: September 2017

Crack propagation after low-cycle fatigue (LCF) deformation has been studied in the chromium martensitic structural steel. Although the study of a fundamental mechanism of fatigue crack growth has received much attention over the last decade, it still remains a sufficiently complex problem and needs full understanding. Moreover, the recent studies show that the cracks propagate discontinuously even on the millisecond timescale, and their growth rate significantly depends on a microstructure of the material. In the present work the boundaries of the former austenitic grains were revealed on the polished surfaces of the thermally treated samples, which subsequently were undergone low-cycle fatigue tests. The experimental studies show that fatigue macrocracks mainly grow along the boundaries of the former austenitic grains, and changetheir propagation direction when crossing the grain boundary, however, remain within 45 ̊ interval with regard the cycling axis. In particular cases, when the boundaries of a martensite packets and those of the former austenite grains lay along the length of a packet, the macrocrack is better formed and with regular borders. After a macrocrack reaches a definite length ~30-50μ, a microcrack is nucleated ahead of the macrocrack tip, and is oriented along the substructure element of the steel. Further deformation tests provide an increase in the length of the main crack via aggregation of microcracks initiated ahead of it during the LCF. In the cases when the macrocrack is deviated, slip bands are formed in martensitic structures along the boundaries of martensite packets (laths). A correlation is revealed between the microcrack components and the substructure elements of the steel as well. The same results were obtained by fractography of the tested and fractured samples. However, in the latter case correlation was established between the cleavage facets and the dimensions of packets.
On the Contact Stresses at the Indenting Edge of a Shaft-Hub Interference Fit Subject to Bending and Shear Forces
Authors: Bertocchi Enrico , Mantovani Sara , Strozzi Antonio
Published: September 2017

The contact stress field is addressed that is developed at the indenting edge of a keyless shaft-hub interference fit, in the case that both bending and shear forces are applied, and in the absence of friction. The combined effect of a set of elementary load cases is assessed for the sharp notch case in terms of a generalized stress intensity factor, with the aid of Finite Elements and for a class of shaft-hub geometries. In fact, linearity is preserved in the case of a sharp edged bore up to the incipient detachment condition; such event, which may occur as a result of e.g. excessive bending loads, may be forecast based on the proposed framework. Contact stresses in the case of rounded edge may be subsequently predicted by scaling an appropriate local solution; fatigue analysis may then be performed in the case of rotating or fluctuating loads. An exhaustive design table is finally compiled to assist the designer in dimensioning an interference fit in the presence of an arbitrary combination of time varying bending and shear forces.
Fracture Mechanics Analysis of Size-Dependent Piezoelectric Solids under a Thermal Load
Authors: Sladek Jan , Sladek Vladimir , Wünsche Michael , Tan Choon Lai
Published: September 2017

General 2D boundary value problems of piezoelectric nanosized structures with cracks under a thermal load are analyzed by the finite element method (FEM). The size-effect phenomenon observed in nanosized structures is described by the strain-gradient effect. The strain gradients are considered in the constitutive equations for electric displacement and the high-order stress tensor. For this model, the governing equations are derived with the corresponding boundary conditions using the variational principle. Uncoupled thermoelasticity is considered, thus, the heat conduction problem is analyzed independently of the mechanical fields in the first step. A numerical example is presented and discussed to demonstrate the effects of the strain-gradient.
The Frame Structure Analysis of the Structure with Repaired Part
Authors: Arai Masayuki
Published: September 2017

The requirement of a repairing technique for aged structures such as pipe line systems has increased recently. To ascertain the reliability of such repaired components, the stress and deformation in the structural system, including the repaired part, needs to be analyzed. In this study, a basic theory for the frame structure analysis method, which can be used to analyze the deformation and stress in the structure including inhomogeneous element modeling a repaired part, is formulated. A numerical simulation software is also developed.
A Novel Micro-Mechanical Model for Polycrystalline Inter-Granular and Trans-Granular Fracture
Authors: Gulizzi Vincenzo , Rycroft Chris H. , Benedetti Ivano
Published: September 2017

In this work, a novel grain boundary formulation for inter-and trans-granular cracking of polycrystalline materials is presented. The formulation is based on the use of boundary integral equations for anisotropic solids and has the advantage of expressing the considered problem in terms of grain boundary variables only. Inter-granular cracking occurs at the grain boundaries whereas trans-granular cracking is assumed to take place along specific cleavage planes, whose orientation depends on the crystallographic orientation of the grains. The evolution of inter-and trans-granular cracks is then governed by suitably defined cohesive laws, whose parameters characterize the behavior of the two fracture mechanisms. The results show that the model is able to capture the competition between inter-and trans-granular cracking.
Effects of PVD DLC Coating on 7075-T6 Alloy Fatigue Strength
Authors: Baragetti Sergio
Published: September 2017

7075-T6 aluminium alloy is under investigation in the last decades because of its sensitivity to corrosion and its poor surface behaviour. The alloy is widely used in many mechanical, aeronautical and structural engineering appliances because of its high strength-to-weight-ratio. Notwithstanding its strength and light weight advantages, its applications in corrosive environments, with fatigue applied loads, is still under research. The mechanical and chemical driving forces have still to be accurately evaluated and the role of each one identified. Results of tests on rotating bending fatigue (R = -1) 7075-T6 uncoated and PVD DLC coated specimens are reported in this paper under various stress levels and number of cycles to failure. Fracture surfaces were observed via SEM characterization in order to assess the role of the chemical aggressive environment, the residual stress field and the applied load.
Numerical Modelling of a Chevron Notched Bend Specimen - Plane Model
Authors: Sobek Jakub , González Menéndez S. , Seitl Stanislav
Published: September 2017

The paper focuses on a numerical modelling of the initial chevron notch in test specimens subjected to the three-point bending test geometry configuration. The plane model is used with variable thicknesses of the layers with plane stress condition. The number of layers is being investigated and the influence of some input parameters like relative crack length, breadth of initial notch, etc. is evaluated by value of the stress intensity factor for tension loading mode.
The Influence of Prefabricated Crack with Bias Angle on the Material’s Fracture Toughness
Authors: Zou Guang Ping , Zhao Chong , Chang Zhong Liang
Published: September 2017

In this work, the effect of the prefabricated crack offset angle on the fracture toughness of the CT specimen was studied by means of the numerical simulation of tensile fracture. It is found that offset angle has a great influence on the fracture toughness of the CT specimen with a straight crack, and the effect is obvious when the bias angle is greater than 3 degrees. For the CT specimen with an oblique crack tip, with the increase of the bias angle of the crack tip, the J-integral value and the fracture toughness are not significantly changed. At the same time, as the angle increases, the stress applied load has more obvious influence on the crack tip stress field.
A Grain-Scale Model of Inter-Granular Stress Corrosion Cracking in Polycrystals
Authors: Benedetti Ivano , Gulizzi Vincenzo , Milazzo Alberto
Published: September 2017

In this contribution, we propose a cohesive grain-boundary model for hydrogen-assisted inter-granular stress corrosion cracking at the grain-scale in 3D polycrystalline aggregates. The inter-granular strength is degraded by the presence of hydrogen and this is accounted for by employing traction-separation laws directly depending on hydrogen concentration, whose diffusion is represented at this stage through simplified phenomenological relationships. The main feature of the model is that all the relevant mechanical fields are represented in terms of grain-boundary variables only, which couples particularly well with the employment of traction-separation laws.
A Finite Element Based Analysis of Double Strap Bonded Joints with CFRP and Aluminium
Authors: Biscaia Hugo , Cardoso João , Chastre Carlos
Published: September 2017

The bonding between two different materials or between same materials is a quite popular method. Unlike fastener joints, it avoids undesirable stress concentrations and doesn't demand an intrusive application to ensure the good performance of the joint. However, depending on the configuration of the adhesively bonded joint, its performance responds differently and the choice (if possible to make) on the best configuration, i.e. the configuration that originates the highest strength and/or stiffness, may be hard to make. Within this context, several configurations of aluminium-to-aluminium bonded joints unstrengthened and strengthened with fiber reinforced polymers (FRP) were modelled using a commercial finite element code. The linearity and nonlinearity of the FRP composite and the aluminium were considered, respectively, and the adhesively bonded joints were subjected to a regular displacement that intended to simulate a tensioning load. Also, the nonlinearities of the interfaces were considered in the form of nonlinear cohesive adhesive laws. The fracture Modes I and II were defined trough a bond-slip relation with a bi-linear shape and the Mohr-Coulomb failure criterion is used for the coupling of the cohesive adhesive laws of the interface when the debonding process of the bonded joint configuration implies the interaction between both fracture modes, i.e. the joint is under a mixed-mode (Mode I+II) situation. The results are presented and discussed and the configurations of the bonded joints are all compared through bond stress distributions and load-slip responses. The study herein presented is, therefore, a contribution to the analysis of the structural integrity of bonded joints between FRP composites and aluminium substrates, helping also on the choice of the most adequate bonded joint configuration and corresponding reinforcement to be used and applied in practice.
RETRACTED: A Study on the Fatigue Behavior of Hot Dip Galvanized Steel Connections
Authors: Razavi Nima , Peron M. , Mutignani F. , Torgersen J. , Berto F.
Published: September 2017

Retracted article: The effect of a galvanizing coating on the fatigue strength of S355 structural steel is analyzed in detail showing that the decrease of the fatigue life is very limited if compared with that of uncoated joints and the results are in good agreement with Eurocode detail category, without substantial reductions. The procedure for the preparation of the specimens is systematically described in this note providing a useful tool for engineers involved in similar practical applications. The results are compared with previous data from notched galvanized specimens weakened by a central hole and not treated specimens characterized by the same geometry.
RETRACTED: Fatigue Strength of Hot-Dip Galvanized Welded Steel Connections
Authors: Razavi Nima , Peron M. , Mutignani F. , Torgersen J. , Berto F.
Published: September 2017

Retracted article: This paper investigates the effect of a galvanizing coating on the fatigue strength of S355 structural steel. The aim of the present paper is to partially fill this lack of knowledge. A comparison is carried out, between hot dip galvanized fillet welded cruciform joints made by S355 structural steel and not treated welded joints characterized by the same geometry, subjected to a load cycle R = 0. Thirty four new experimental data are summarized in the present contribution, in terms of stress range Δσ and averaged strain energy density range in a control volume of radius R0 = 0.28 mm.
Experimental Investigation of Metallic Fiber-Reinforced Adhesively Bonded Joints under Bending
Authors: Razavi Nima , Berto F.
Published: September 2017

In the current paper, the geometric and material parameters of metal fibers utilized for strengthening adhesively bonded single lap joints under flexural loading were investigated by using experimental investigations. According to the test results, incorporating metal fibers in the adhesive layer of a bonded joint can have a significant impact on the flexural load bearing of the joint. The distance between the fibers and also the fibers orientation were considered as the key parameters in this research. It was concluded that the load bearing of the joint can be improved by reducing the distance between the fibers and the highest failure loads were obtained for the joints reinforced by fibers in the longitudinal direction.
Evaluation of Residual Stresses in Butt Welded Joint of Dissimilar Material by FEM
Authors: Sepe Raffaele , Laiso M. , de Luca A. , Caputo Francesco
Published: September 2017

The study proposed within this paper deals with an application of finite element techniques to the thermo-structural analysis of a dissimilar butt-welded joint. Residual stresses induced by the fusion arc-welding of steel joints in power generation plants are a concern to the industry. Nowadays, the application of finite element method appears to be a very efficient method for the prediction and the investigation of the weld-induced residual stresses, nevertheless the detailed modelling of all phenomena involved in such process is still challenging. The structural integrity assessment of welded structures strongly requires a deep investigation of weld-induced residual stresses in order to be compliant with safety requirement of power plant. The longitudinal and transversal residual stresses in dissimilar material butt joints of 8 mm thick for V-groove shape were studied. The developed thermo-mechanical FE model as well as the simulation procedures are detailed and results are discussed. As a result of such work, it has been found out that residual stresses in the two dissimilar plates are characterized by very different magnitudes and distribution.
Fatigue Crack Initiation in Nickel-Based Superalloy MAR-M247 at High Temperature
Authors: Šulák Ivo , Obrtlík Karel
Published: September 2017

The present work is focused on the study of crack initiation during low cycle fatigue (LCF) loading of the second generation nickel-based superalloy MAR-M247 treated with hot isostatic pressing. LCF tests were conducted on cylindrical specimens in symmetrical push-pull cycle under strain control with constant total strain amplitude and strain rate at 800 °C in air atmosphere. Selected specimens were electrolytically polished to facilitate surface relief observations. Crack initiation sites were studied by means of scanning electron microscopy (SEM) in dual beam microscope TESCAN LYRA 3 XMU FESEM equipped with focus ion beam (FIB). The microstructure of the material is characterised by coarse dendritic grains with numerous carbides and small casting defects. The average grain size was 2.1 ± 0.3 mm. Fractographic analysis revealed the fatigue crack initiation sites and their relation to the casting defects and material microstructure. Casting defects, carbide inclusions and interdendritic areas were found to be important crack nucleation sites. Specimens’ surface observations revealed the formation of pronounced surface relief with short worm-like markings. Fatigue crack initiation in these places is documented and discussed.
Mechanical Analysis of a Hexagonal Joint
Authors: Mantovani Sara
Published: September 2017

A hexagonal joint is mechanically analysed. A cross section of the receding contact between the male and female components is modelled as a plane strain problem. Particular attention is paid to the effect of the presence of fillets in the hexagonal male. Finite Element (FE) results show that, for each side of the hexagonal contact, the contact zone constitutes a small portion of the length of the hexagonal side, and separation occurs elsewhere. The normalized peak contact pressure and the contact length along the male sides are numerically evaluated.
Investigation on the Unconfined Compression Strength of Rocks by Experimental Tests and Advanced Numerical Modelling Technique
Authors: Mardalizad Aria , Manes Andrea , Giglio Marco
Published: September 2017

The mechanical response of a middle strength rock, namely Pietra sandstone, is assessed both numerically and experimentally under unconfined compressive loading condition. Two experimental approaches, based on different specimens’ arrangements, have been conducted on Pietra Serena sandstone to determine its unconfined compressive strength (UCS). This parameter greatly influences the boreability of rocks and a precise method for obtaining this parameter is thus always required. The experimental tests have been replicated in LS-DYNA in conjunction with an advanced material model, called the Karagozian and Case Concrete (KCC) model, to benchmark the results and, therefore, to conclude which experimental approaches yield the most reliable results.
Punching Shear Design Method of Voided Slabs
Authors: Chung Joo Hong , Choi Hyun Ki , Choi Chang Sik , Jung Hyung Suk
Published: September 2017

This study presents punching shear design method of voided slab in accordance with arrangement of voids around columns. According to previous studies, the slab-column connection of voided slabs is weaker than that of the solid slab due to the lack of cross-sectional area of concrete by voids. In this study, it is assumed that the arrangement of voids exert influence on the punching shear strength of voided slabs. To verify the assumption, finite element analysis was conducted related with previous test results. The variable of FE analysis was a distance between voids and column face. Based on FE analysis and test results including previous studies, punching shear design method is suggested which can consider the arrangement of voids around columns. The suggested design method is based on the punching shear design method in ACI-318. As a result, it can predict the punching shear strength of voided slabs according to arrangement of voids around column.
Damage Detection in Composite Skin Stiffener with Hybrid PZT-FO SHM System
Authors: Lambinet Florian , Sharif Khodaei Zahra
Published: September 2017

A hybrid piezoelectric (PZT)/fibre optic diagnostic system has been developed for damage detection in built up composite structures. The hybrid system uses PZT transducers to actuate the structure and fibre optic (FO) sensors to capture the propagating wave. The diagnostic system will then have the advantages of both PZT and FO sensors. The applicability of the system is then tested for detecting an artificial damage at a skin/stiffener interface of a thick composite structure. The response of the FO sensors is then compared to PZT sensors and presented.
Measurement of Weld Mechanical Properties Using an Instrumented Indentation Technique
Authors: Song Kee Nam
Published: September 2017

Different microstructures in the weld zone of a metal structure including a fusion zone and a heat affected zone, are formed as compared to the base material. Consequently, the mechanical properties in the weld zone are different from those in the base material to a certain degree owing to different microstructures and residual welding stresses. When a welded structure is loaded, the mechanical behavior of the welded structure might be different from the case of a structure with homogeneous mechanical properties. It is known that obtaining the mechanical properties in the weld is generally difficult owing to the narrow regions of the weld and interfaces. As an alternative way to obtain the weld mechanical properties, the weld mechanical properties of Alloy800HT, SUS316L, and Alloy617, were recently measured using an instrumented indentation technique, and the representative weld mechanical properties of these materials were estimated with a 95% lower confidence level for later structural analyses of the welded structures.
Influence of Texture and Environmental Effects on Fatigue Behavior of Ti-6Al-4V Alloy
Authors: Baragetti Sergio , Srinivasan Nedunchezhian , Kumar Ravi
Published: September 2017

Ti-6Al-4V alloy in solutionized and aged condition was subjected to axial fatigue testing in air and corrosive environments respectively. Severity of the methanol damage as evidenced through fractographic studies, corroborates loss in fatigue strength of samples tested in methanol environment in contrast to samples tested in air. Samples subjected to fatigue loading in NaCl environment revealed extensive secondary cracks along alpha grain boundaries.
Residual Stress Measurement in Innovative Friction Stir Welding Processes
Authors: Campanella D. , Casavola C. , Cazzato A. , Fratini Livan , Moramarco V. , Pappalettere C.
Published: September 2017

In recent years, important innovations have been introduced in Friction Stir Welding (FSW) technology such as, for example, the Laser assisted Friction Stir Welding (LFSW) and in-process Cooled Friction Stir Welding (CFSW). Residual stresses have a fundamental role in welded structures because they affect the way to design the structures, fatigue life, corrosion resistance and many other material properties. Consequently, it is important to investigate the residual stress distribution in FSW where, though the heat input is lower compared to traditional welding techniques, the constraints applied to the parts to weld are more severe. The aim of the present work is to verify the capabilities of both FSW techniques in reduction of the residual stress in aluminium butt joints.
Fracture Evaluation of the Falling Weight Impact Behaviour of a Basalt/Vinylester Composite Plate through a Multiphase Finite Element Model
Authors: Vannucchi de Camargo Felipe , Pavlovic Ana
Published: September 2017

Several investigations regarding the mechanical behaviour of composites reinforced by natural fibers under impact have been realized recently, aiming at achieve a low-weight and resistant design. At the same time, progressively accurate results on numerical simulations have been reached powered by modern Finite Element Method (FEM) approaches for composites; however, demonstrating a faithful indentation pattern is still a challenge. The present work aims at building an impact numerical simulation that exhibits a fracture mechanism exactly like the one seen in experimental tests, also carried in this work, on a Basalt Reinforced Composite Polymer (BRFP) plate subjected to low-velocity falling weight impact (IFW). The FEM simulation describes a multiphase model considering each ply and their inter-layer interactions.
Investigating the Degradation Phenomena of Teflon Exposed to Acidic Environment
Authors: Zattini Giorgio , Mazzocchetti Laura
Published: September 2017

This study provides an overview of the effects of prolonged acid attack on the surface of PTFE gaskets, assessed using Fourier Transform Infrared Spectroscopy (FT-IR), Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC). The PTFE analysed originates from two manufacturers in form of Teflon adhesive tapes, used as gaskets in an ultrasonic tyre moulds cleaning plant (UMCS). The gaskets were exposed to various acid baths, temperature and ultrasonic waves, and shown anomalous damage and surface degradation in a relatively short operation time. The analyses here reported have been aimed at investigating this unusual behaviour. PTFE samples have been treated with different acid mixes to evaluate possible different aging effects. Both surface and core have been analysed after aging, providing evidence of the degradation phenomena. In particular, different acid treatments have highlighted different response of PTFE and differences among manufacturers.
Cytokine-Mediated Regulation of Human Lymphocyte Development and Function: Insights from Primary Immunodeficiencies
Authors: Tangye Stuart G. , Pelham Simon J. , Deenick Elissa K. , Ma Cindy S.
Published: September 2017

Cytokine-mediated intracellular signaling pathways are fundamental for the development, activation, and differentiation of lymphocytes. These distinct processes underlie protection against infectious diseases after natural infection with pathogens or immunization, thereby providing the host with long-lived immunological memory. In contrast, aberrant cytokine signaling can also result in conditions of immune dysregulation, such as early-onset autoimmunity. Thus, balanced signals provided by distinct cytokines, and delivered to specific cell subsets, are critical for immune homeostasis. The essential roles of cytokines in human immunity have been elegantly and repeatedly revealed by the discovery of individuals with mutations in cytokine ligands, receptors, and downstream transcription factors that cause primary immunodeficiency or autoimmune conditions. In this article, we review how the discovery and characterization of such individuals has identified nonredundant, and often highly specialized, functions of specific cytokines and immune cell subsets in human lymphocyte biology, host defense against infections, and immune regulation.
Rainfall retrieval with commercial microwave links in São Paulo, Brazil
Authors: Rios Gaona Manuel F. , Overeem Aart , Raupach Tim H. , Leijnse Hidde , Uijlenhoet Remko
Published: September 2017

Abstract. In the last decade there has been a growing interest from the hydrometeorological community regarding rainfall estimation from commercial microwave link (CML) networks. Path-averaged rainfall intensities can be retrieved from the signal attenuation between cell phone towers. Although this technique is still in development, it offers great opportunities for the retrieval of rainfall rates at high spatiotemporal resolutions very close to the Earth's surface. Rainfall measurements at high spatiotemporal resolutions are highly valued in urban hydrology, for instance, given the large impact that flash floods exert on society. Flash floods are triggered by intense rainfall events that develop over short time scales. Here, we present one of the first evaluations of this measurement technique for a subtropical climate. Rainfall estimation for subtropical climates is highly relevant, since many countries with few surface rainfall observations are located in such areas. The test bed of the current study is the Brazilian city of São Paulo. The open-source algorithm RAINLINK was applied to retrieve rainfall intensities from (power) attenuation measurements. The performance of RAINLINK estimates was evaluated for 5 of the 250 CML in the São Paulo metropolitan area for which we received data, for 81 days between October 2014 and January 2015. We evaluated the retrieved rainfall intensities and accumulations from CML against those from a dense automatic gauge network. Results were found to be promising and encouraging, especially for short links, for which high correlations (> 0.9) and low biases (~ 30 % and lower) were obtained.
Molecular fingerprinting of particulate organic matter as a new tool for its source apportionment: changes along a headwater drainage in coarse, medium and fine particles as a function of rainfalls
Authors: Jeanneau Laurent , Rowland Richard , Inamdar Shreeram
Published: September 2017

Abstract. Tracking the sources of particulate organic matter (POM) exported from catchments is important to understand the transfer of energy from soils to oceans. The suitability of investigating the molecular composition of POM by thermally assisted hydrolysis and methylation using tetramethylammonium hydroxide directly coupled to gas chromatography and mass spectrometry is presented. The results of this molecular fingerprint approach were compared with previously published elemental (%C, %N) and isotopic data (δ13C, δ15N) acquired in a nested headwater catchment in Piedmont region, Eastern United States of America (12 and 79 ha). The concordance between these results highlights this molecular tool as a valuable method for source fingerprinting of POM. It emphasizes litter as the main source of exported POM at the upstream location (80 ± 14 %) with an increasing proportion of stream bed (SBed) sediments remobilization downstream (42 ± 29 %), specifically during events characterized by high rainfall amounts. At the upstream location, the source of POM seems to be controlled by the maximum and median hourly rainfall intensity. An added-value of this method is to directly investigate chemical biomarkers and to mine their distributions in term of biogeochemical functioning of an ecosystem. In this catchement, the distribution of plant-derived biomarkers characterizing lignin, cutin, and suberin inputs were similar in SBed and litter, while the proportion of microbial markers was 4 times higher in SBed than in litter. These results indicate that SBed OM was largely from plant litter that has been processed by the aquatic microbial community.
Earthquake static stress transfer in the 2013 Gulf of Valencia (Spain) seismic sequence
Authors: Saló Lluís , Frontera Tànit , Goula Xavier , Pujades Luis G. , Ledesma Alberto
Published: September 2017

Abstract. On 24 September 2013, an Ml 3.6 earthquake struck in the Gulf of Valencia (Spain) near the Mediterranean coast of Castelló, roughly 1 week after gas injections conducted in the area to develop underground gas storage had been halted. The event, felt by the nearby population, led to a sequence build-up of felt events which reached a maximum of Ml 4.3 on 2 October.Here, we study the role of static stress transfer as an earthquake-triggering mechanism during the main phase of the sequence, as expressed by the eight felt events. By means of the Coulomb failure function, cumulative static stress changes are quantified on fault planes derived from focal mechanism solutions (which act as both source and receiver faults) and on the previously mapped structures in the area (acting only as stress receivers in our modeling). Results suggest that static stress transfer played a destabilizing role and point towards an SE-dipping structure underlying the reservoir (or various with analogous geometry) that was most likely activated during the sequence. One of the previously mapped faults could be geometrically compatible, yet our study supports deeper sources. Based on this approach, the influence of the main events in the occurrence of future and potentially damaging earthquakes in the area would not be significant.
Potential permafrost distribution and ground temperatures based on surface state obtained from microwave satellite data
Authors: Kroisleitner Christine , Bartsch Annett , Bergstedt Helena
Published: September 2017

Abstract. A threshold of half a year frozen conditions has been previously suggested for the determination of potential permafrost extent from a passive microwave sensor using 37 GHz (SSM/I). We argue that this value should be higher and needs to be refined. Further on, data using lower frequencies such as from Metop ASCAT (5.3 GHz) might be more suitable. We used borehole temperature records from across the Arctic for the assessment. The comparison to mean annual ground temperature (MAGT) at coldest sensor depth revealed that temperature can be directly obtained from ASCAT surface state with a residual error of 2.5 °C compared to 3 °C in case of SSM/I. The optimum threshold of frozen days to estimate permafrost extent is 190 days for SSM/I, as determined in comparison to borehole data (Kendall's τ test), and 196 days from modelled MAGT. Thresholds for Metop ASCAT are 204 and 212 frozen days per year respectively. Data sets are comparably coarse (12.5 km–25 km nominal resolution) and the accuracy of the modelled MAGT varies regionally but the approach does not require gap filling or spatial interpolation as in the case of conventional frozen ground modelling from temperature measurements.
The maximal subgroups of Sylow subgroups and the structure of finite groups
Authors: Li Changwen , Zhang Xuemei , Huang Jianhong
Published: September 2017

In this paper we investigate the influence of some subgroups of Sylow subgroups with semi cover-avoiding property and $E$-supplementation on the structure of finite groups. Some recent results are generalized and unified.
Some generating functions and properties of extended second Appell function
Authors: Parmar Rakesh K. , Purohit Sunil Dutt
Published: September 2017

Various families of generating functions have been established by a number of authors in many different ways. In this paper, we aim at establishing (presumably new) a generating function for the extended second Appell hypergeometric function $F_{2} (a, b, b'; c, c'; x, y; p)$. Further we derive a relation in terms of the Laguerre polynomials and differentiation formulas. We also present special cases of the main results of this paper.
Numerical investigation of nanofluid turbulent flow in a wavy channel with different wavelengths, amplitudes & phase lag
Authors: Tavangar Toran , Ramiar Abbas , Arya Amir , Mohammadyari Reza , Rahimi-Esbo Mazaher
Published: September 2017

Two dimensional incompressible turbulent nanofluid flow in a sinusoidal wavy channel is numerically investigated. Finite volume method and Rhie and Chow interpolation in a collocated grid arrangement are used for solving governing equations. The effects of the volume fraction of nanoparticles, Reynolds number, phase lag, frequency and amplitude of the wavy walls on the heat transfer rate are studied. The present work showed good agreement with existing experimental and numerical results. Increasing the frequency and amplitude of the wave and nanoparticles volume fraction has great effect on heat transfer rate.
A note on mathematical structures
Authors: Modak Shyamapada , Noiri Takashi
Published: September 2017

In this paper we shall discuss the interrelations between generalizations of topology and mathematical structures. We also discuss the algebraic nature of generalizations of topology and mathematical structures.
Common fixed point theorems for generalized G- η-χ–contractive type mappings with applications
Authors: Kumar Manoj , Araci Serkan
Published: September 2017

Samet et. al. (Nonlinear Anal. 75, 2012, 2154-2165) introduced the concept of alpha-psi-contractive type mappings in metric spaces. In 2013, Alghamdi et. al. [2] introduced the concept of G-β--contractive type mappings in G-metric spaces. Our aim is to introduce new concept of generalized G-η-χ-contractive pair of mappings. Further, we study some fixed point theorems for such mappings in complete G-metric spaces. As an application, we further establish common fixed point theorems for G-metric spaces for cyclic contractive mappings.
Intervenções de enfermagem para pacientes oncológicos com odor fétido em ferida tumoral
Authors: Freitas de Castro María Cristina , Santos William Alves dos , Fuly Patricia dos Santos Claro , Caldeira dos Santos Mauro Leonardo Salvador , Ribeiro Garcia Telma
Published: September 2017

Objetivo: identificar intervenciones de enfermería para el diagnóstico de olor fétido en herida tumoral. Métodos: revisión integradora de la literatura a partir de las bases de datos MEDLINE, CINAHL, LILACS e Cochrane, que resultó en la selección de 48 artículos científicos acerca de la temática investigada. Resultados: con base en las evidencias empíricas identificadas en los artículos incluidos en el estudio, se elaboraron 24 intervenciones de enfermería para el control y la reducción del olor fétido en heridas tumorales. Conclusiones: las intervenciones de enfermería presentadas en el estudio posibilitan la promoción de la calidad de vida al paciente con herida tumoral en cuidado paliativo. Como sugerencia posterior al Consejo Internacional de Enfermeros, se deben validar clínicamente para que su inserción se realice en el subconjunto terminológico cuidados paliativos para una muerte digna, de la Clasificación Internacional para la Práctica de Enfermería (CIPE®).
Diagnósticos de enfermagem e modelo adaptativo de roy: análise em pacientes críticos
Authors: Dantas Anna Lívia de Medeiros , Nogueira Isadora Lorenna Alves , Vitorino Ana Beatriz Ferreira , Tinôco Jéssica Dantas de Sá , Frazão Cecília Maria Farias de Queiroz , Lira Ana Luisa Brandão de Carvalho
Published: September 2017

Objetivo: establecer relación de los diagnósticos de enfermería presentes en el dominio seguridad y protección de NANDA Internacional con los problemas adaptativos del modelo de Roy para pacientes en unidad de cuidados intensivos (UCI). Métodos: estudio transversal, llevado a cabo en la UCI de un hospital universitario en una capital del noreste brasileño. La muestra fue de 86 individuos. Los datos, recolectados entre octubre del 2013 y mayo del 2014, mediante formato de entrevista y prueba física, se analizaron por medio de estadística descriptiva e inferencial. Resultados: entre los diagnósticos de enfermería del dominio seguridad y protección, 29 estuvieron presentes con frecuencias variables. En cuanto a los relacionados con los problemas adaptativos propuestos por Roy, se evidenciaron 12 problemas adaptativos en cuanto al modo adaptativo fisiológico, que abarca las categorías de sentidos, protección, oxigenación, actividad y reposo y nutrición. Conclusiones: se encontró relación entre los diagnósticos de enfermería del dominio seguridad y protección y los problemas adaptativos del modelo de Roy para pacientes en cuidados intensivos.
Using Twitter as an ELT Tool in the Saudi EFL Context
Authors: Allam Madawi , Elyas Tariq , Bajnaid Ayman , Rajab Hussam
Published: September 2017

The present study aims at investigating English as a Foreign Language (EFL) Saudi students’ adaption of Twitter and utilizing it as an English language learning tool and the different characteristics of each adopter category using Roger’s Diffusion of Innovation Theory (DOI). It targets both the foundation year Saudi female university students studying EFL at the English Language Institute (ELI) at King Abdul Aziz University (KAU) as well as the male and female Saudi students studying English at English language institutes abroad. The sample will consist of 50 female preparatory year students (PYS) studying EFL at the ELI. Their ages will range between the ages of 18 and 21 years old and will all be likely to come from an Arab origin. Furthermore, the study will include 50 male and female English learners who are studying abroad. This quantitative study uses a three parts questionnaire. The first part will request demographic information from participants such as age, years of experiences, academic ranking, and the level they are studying in the students' case. In the second section, participants were asked to choose the response that describes the degree to which they use the innovation (Twitter). In the last section, participants were asked to read 23 statements that measure the different characteristics of each adopter category which influence the user intention and behavior. The 23 statements were based on the five perceived attributes of innovations derived by Rogers (2003). A five-point Likert-type scale ranging from strongly agrees to strongly disagree was applied to assess the perceived attributes of Twitter. The researcher aims at identifying valuable insights on how much the social network website Twitter is accepted and used as a learning tool for Saudi language learners. Therefore, based on the findings of this study, researchers in the same field may expand the study by moving to further experimental research that maybe carried out to investigate the effectiveness of Twitter as a teaching tool in the ELI classroom at KAU and other language institutes outside the Kingdom.