bluuebunny/crossref_metadata_2025 huggingface dataset:
Reading Disabilities in Adolescents and Adults
Authors: Saletta Meredith
Published: November 2018

Purpose

Reading skills continue to develop into adolescence and adulthood. Difficulties in reading have lifelong repercussions. Many speech-language pathologists who work with older individuals in the school setting face significant issues, including those mandated by recent changes in legislation. Theoretical topics related to reading development and disorders include the variety of orthographic systems across languages and the ways in which adults who are literate in an alphabetic orthographic system experience changes to their spoken and written language processing. In addition, older readers with intellectual or developmental disabilities may benefit from the use of leveled books and the inclusion of illustrations or drawings along with text.

Method

I completed a focused literature review regarding typical reading skills, dyslexia in adolescence and adulthood, recent changes in legislation, orthography, and the use of leveled books for adolescents and adults with intellectual or developmental disabilities.

Conclusions

Further study of reading in older individuals may lead to important theoretical and clinical applications. Speech-language pathologists should keep in mind the various components of reading (such as decoding and comprehension), how these factors relate to oral language, and how they may be addressed in therapy.
Investigation of wrapped effects on bow‐tie antenna with and without resistive loading for pulsed radar applications
Authors: Lee D. , Melek W. , Shaker G.
Published: November 2018

The effects of the wrapped bow‐tie antenna with and without resistive loading are explored for pulsed radar applications. The antenna characteristics such as voltage standing wave ratio, input impedance, reflected pulse of the antennas and radiated electric field are investigated by fully wrapping the planar bow‐tie antenna. The antenna characteristics of the loaded antennas are shown to be robust with respect to the deformation of the planar bow‐tie antenna. The peak‐to‐peak antenna reflected voltages of the conventional bow‐tie planar antenna (PA) and bow‐tie wrapped antenna (WA) are 0.24 and 0.49 V, respectively, whereas those of the resistor‐loaded PA (RPA) and the resistor‐loaded WA (RWA) are 0.23 and 0.25 V, respectively. The calculated figure of merit of the PA and WA are −4.58 and −7.92 dB, respectively, whereas those of the RPA and RWA are −20 and −18.42 dB, respectively. On the basis of the performance evaluation, the pulse radiating performance of the resistively loaded antennas is shown to be stable with respect to the deformation of the planar bow‐tie antenna.
Risk assessment‐based long‐term transmission system hardening under prior probabilistic information
Authors: Ding Tao , Li Cheng , Chen Chen , Chen Bo , Yang Yongheng
Published: October 2018

In the long‐term transmission system hardening, critical components in transmission infrastructure should be identified and hardened to reduce the load loss risk in the presence of scheduled and unscheduled outages. Generally, the probabilistic information of assets in power systems can be evaluated via historical statistics. On the basis of the prior probabilistic information, this study proposed a tri‐level optimisation model to deal with the problem of long‐term transmission system hardening, in which the risk assessment is taken into account in the objective function. Furthermore, the problem is formulated as a two‐stage robust optimisation model. To address the non‐linear problem in the inner model, logarithmic transformation and piecewise linearisation are utilised to exactly linearise the non‐linear terms in the model. Finally, the standard column‐and‐constraints generation algorithm is employed to solve the proposed model with a master–sub‐problem framework. The test results on a standard IEEE RTS‐96 system show the effectiveness of the proposed model.
Synthesis of second‐order wide‐passband frequency selective surface using double‐periodic structures
Authors: Ma Xin , Wan Guobin , Zhang Wenwu , Mu Yifei , Tang Xuying
Published: October 2018

A new second‐order wide‐bandpass frequency‐selective surface (FSS) composed of a two‐dimensional periodic array cascading aperture‐type FSS and strip‐type FSS with different periods is proposed and investigated. The cascading structure of two parallel electric sheets is systematically analysed based on boundary conditions formulated in terms of surface impedances. By retrieving equivalent circuits of each cell, the operating principle of the proposed FSS can be qualitatively analysed and discussed. The synthesised FSS can provide not only the wide passband characteristics but also transmission zero at the adjacent resonant frequency. A sample of the square loop array is designed and measured. Good agreement between equivalent circuit analysis, simulation, and measurement results is obtained. The suggested FSS is shown to be a simple structure with a stable wide bandpass response under different incident angles.
PSS design for damping low‐frequency oscillations in a multi‐machine power system with penetration of renewable power generations
Authors: Kahouli Omar , Jebali Mariam , Alshammari Badr , Hadj Abdallah Hsan
Published: October 2018

This study focused on the use of the non‐dominated sorting genetic algorithm (NSGA‐II) to achieve an optimal power system stabiliser (PSS) parameters for a given operating point with a renewable source of energy so as to increase the system damping and guarantee enough stability margin. The parameters tuning was formulated using an eigenvalue‐based multi‐objective function. In recent years, the changeability and fluctuation of the wind power injected into the network have led to new challenges in small signal stability (SSS). These wind speed change and load demand change perturbations take place routinely and cause the variation of the operating conditions. However, as the conventional PSS is conceived for a fixed operating point in order to obtain the linearised transfer function model, it cannot yield good results when the operating range is too wide. To this end, the adaptive neuro‐fuzzy inference system was proposed to estimate the stabiliser parameters in real time after a learning phase. The nine‐bus Western System Coordinating Council and the obtained simulations results were assessed using Matlab/Simulink package. The validity of the proposed methodology was checked through the PSS parameters evolution simulation for daily load forecast curves and monthly wind speed prediction curves.
Origin of the asymmetry of the wind driven halo observed in high-contrast images
Authors: Cantalloube F. , Por E. H. , Dohlen K. , Sauvage J.-F. , Vigan A. , Kasper M. , Bharmal N. , Henning T. , Brandner W. , Milli J. , Correia C. , Fusco T.
Published: October 2018

The latest generation of high-contrast instruments dedicated to exoplanets and circumstellar disk imaging are equipped with extreme adaptive optics and coronagraphs to reach contrasts of up to 10−4 at a few tenths of arcseconds in the near-infrared. The resulting image shows faint features, only revealed with this combination, such as the wind driven halo. The wind driven halo is due to the lag between the adaptive optics correction and the turbulence speed over the telescope pupil. However, we observe an asymmetry of this wind driven halo that was not expected when the instrument was designed. In this letter, we describe and demonstrate the physical origin of this asymmetry and support our explanation by simulating the asymmetry with an end-to-end approach. From this work, we find that the observed asymmetry is explained by the interference between the AO-lag error and scintillation effects, mainly originating from the fast jet stream layer located at about 12 km in altitude. Now identified and interpreted, this effect can be taken into account for further design of high-contrast imaging simulators, next generation or upgrade of high-contrast instruments, predictive control algorithms for adaptive optics, or image post-processing techniques.
An offshore wind farm energy injection mastering using aerodynamic and kinetic control strategies
Authors: Ikni Djamel , Bagre Ahmed Ousmane , Camara Mamadou Bailo , Dakyo Brayima
Published: October 2018

The injection of wind farm production into a grid, needs optimal strategies for energy transfer management. Usually, the power produced by the wind farms does not fulfil all the grid code requirements. The main problem is generally based on the way to reduce the impacts of power production fluctuations on the grid voltage and its frequency. To solve this problem, some authors suggest the use of an interface such as energy storage devices in order to compensate the wind power fluctuations. In fact, the storage devices installed between the wind farm and the grid can improve the power quality in terms of stability but in other hand the size and the cost of the system can be increased. In this paper, two solutions have been proposed in case the power quality produced by the wind farm is out of the grid code requirements. The improvement of the energy quality of an offshore wind farm without storage and connected to the grid is discussed. The proposed solution is to operate the wind turbines with a reserve of power. To distribute this reserve equitably among wind turbines, a proportional distribution algorithms has been developed. The results obtained show clearly the effectiveness of the strategy.
Comparative study of geometrical configuration at the thermal performances of an agricultural greenhouse
Authors: Djemoui Lalmi , Bensaha Hocine , Benseddik Abdelouahab , Zarrit Ridha , Guermoui Mawloud , Rabehi Abdelaziz , Bouzaher Mohamed Tahar
Published: October 2018

The aims objective of this work consists to study the storage system effects on the thermal performance of a tunnel agricultural greenhouse. The study focus on the use of the data climate analysis to predict the outside needs as comparison with another without storage system. The obtained results indicate that the outside needs are less than the no heated with 3 to 5°c during winter night. The thermal behavior of the greenhouse was study numerically and the results are corroborating with the literature. In addition, we conducted a comparative study designed to identify the optimal form of the greenhouse; two geometrical configuration are considered.
Comparative studies of Cu-Cl Thermochemical Water Decomposition Cyles for Hydrogen Production
Authors: Osuolale Funmilayo , Ogunleye Oladipupo , Fakunle Mary , Busari Abdulfataah , Abolanle Yetunde
Published: October 2018

This research focuses on thermodynamic analysis of the copper chlorine cycles. The cycles were simulated using Aspen Plus software. All thermodynamic data for all the chemical species were defined from literature and the reliability of other compounds in the simulation were ascertained. The 5-step Cu–Cl cycle consist of five steps; hydrolysis, decomposition, electrolysis, drying and hydrogen production. The 4-step cycle combines the hydrolysis and the drying stage of the 5-step cycle to eliminate the intermediate production and handling of copper solids. The 3-step cycle has hydrolysis, electrolysis and hydrogen production stages. Exergy and energy analysis of the cycles were conducted. The results of the exergy analysis were 59.64%, 44.74% and 78.21% while that of the energy analysis were 50%, 49% and 35% for the 5-step cycle, 4-step cycle and 3-step cycle respectively. Parametric studies were conducted and possible exergy efficiency improvement of the cycles were found to be between 59.57-59.67%, 44.32-45.67% and 23.50-82.10% for the 5-step, 4-step and 3-step respectively. The results from the parametric analysis of the simulated process could assist ongoing efforts to understand the thermodynamic losses in the cycle, to improve efficiency, increase the economic viability of the process and to facilitate eventual commercialization of the process.
Nowcasting the Output Power of PV Systems
Authors: Paulescu Marius , Mares Oana , Dughir Ciprian , Paulescu Eugenia
Published: October 2018

This paper presents an innovative procedure for nowcasting the energy production of PV systems. The procedure is relayed on a new version of two-state model for forecasting solar irradiance at ground level and a simplified description of the PV system. The results of testing the proposed procedure against on field measured data are discussed. Generally, the proposed procedure demonstrates a better performance than the main competitor based on ARIMA forecasting of the clearness index.
Status of the NICA project at JINR
Authors: Kovalenko Alexander , Kekelidze Vladimir , Lednicky Richard , Matveev Viktor , Meshkov Igor , Sorin Alexander , Trubnikov Grigory , Tsenov Rumen
Published: October 2018

The NICA (Nuclotron-based Ion Collider fAcility) is the new international research facility under construction at the Joint Institute for Nuclear Research (JINR) in Dubna. The main targets of the facility are the following: 1) study of hot and dense baryonic matter at the energy range of the maximum baryonic density; 2) investigation of nucleon spin structure and polarization phenomena; 3) development of JINR accelerator facility for high energy physics research based on the new collider of relativistic ions from protons to gold and polarized protons and deuterons as well with the maximum collision energy of √SNN ~11GeV (Au79+ +Au79+) and ~ 27 GeV (p+p). Two collider detector setups MPD and SPD are foreseen. The setup BM@N (Baryonic Matter at Nuclotron) is commissioned for data taken at the existing Nuclotron beam fixed target area. The MPD construction is in progress whereas the SPD is still at the beginning design stage. An average luminosity of the collider is expected at the level of 1027 cm-2 s-1 for Au79+ and 1032 cm-2 s-1 for polarized protons at 27 GeV. The status of NICA design and construction work is briefly described below.
Cosmological constraints on matter density perturbations amplitude, neutrino mass and number of relativistic species
Authors: Burenin Rodion
Published: October 2018

It is shown that Planck CMB temperature anisotropy data at high multipoles, ℓ > 1000, produce the measurement of matter density perturbations amplitude that contradict to all other constraints obtained both from remaining Planck CMB anisotropy data and from other cosmological data, at about 3:7σ significance level. With the exception of Planck CMB temperature anisotropy data at high multipoles, all other measurements of density perturbation amplitude are in good agreement between each other and give the following measurements of linear density perturbation amplitude: σ8 = 0:792 ± 0:006, mean density of the Universe: Ωm = 0:287 ± 0:007, and Hubble constant: H0 = 69:4 ± 0:6 km s-1 Mpc-1. Therefore, in this case the tensions in H0 constraints between Planck+BAO data and direct H0 measurements are weaken, and the tensions in σ8 measurements between Planck CMB data and large scale structure data disappear completely. Taking in account the data on baryon acoustic oscillations and (or) direct measurements of the Hubble constant, one can obtain different constraints on sum of neutrino mass and number of relativistic species.
SHiP project as a new facility at intensity frontier
Authors: Shevchenko V. ,   on behalf of the SHiP Collaboration
Published: October 2018

SHiP (Search for Hidden Particles) is a new general purpose fixed target facility suggested for SPS accelerator at CERN. The experiment is currently in Comprehensive Design Report preparation phase, aiming to become a part of European Strategy for Particle Physics update in 2019. In the initial phase of SHiP, the 400 GeV proton beam extracted from the SPS will be dumped on a heavy target producing 2 × 1020 protons on target in 5 years. A dedicated detector, based on a long vacuum tank followed by a spectrometer and particle identification detectors, will allow probing a variety of models with light long-lived exotic particles and masses below O(10) GeV/c2. The main focus will be the physics of the so-called Hidden Portals, i.e. search for Dark Photons, Light scalars and Heavy Neutrinos. The sensitivity to Heavy Neutrinos will allow for the first time to probe, in the mass range between the kaon and the charm meson mass, a coupling range for which Baryogenesis and active neutrino masses could be explained simultaneously. Another dedicated detector will allow the study of tau-neutrino physics.
Oscillations to hidden photon in reactor and accelerator experiments
Authors: Gorbunov Dmitry
Published: October 2018

Possible connection between visible and hidden Worlds of particle physics is provided by the vector portal interaction, that is kinetic mixing between ordinary (visible) and hidden photons. If sufficiently light, the hidden photon can be produced (and absorbed) by ordinary matter in a Compton-like processes, which naively are insensitive to the hidden photon mass. In this talk we study the evolution of the two vector boson system, which exhibits oscillations similar to the well-known neutrino oscillations. We show that, provided by the environment matter, this quantum phenomenon significantly suppresses the hidden photon production in particle collisions. The ordinary photon is effectively massive in the media. The suppression is important for hidden photon lighter than photon in the corresponding media (detector, beam dump material etc) and grows with decrease of the hidden photon mass making all the accelerator and reactor experiments absolutely insensitive to the models with light photons. The dedicated study is required for the case of the degenerate photon and hidden photon, when, on the contrary, the hidden photon production can be amplified with respect to the Compton process.
Rare CP-violated η and η′ meson decays and neutron EDM.
Authors: Zhevlakov Alexey S. , Gorchtein Mikhail , Hiller Blin Astrid N. , Lyubovitskij Valery E.
Published: October 2018

The data for the upper limit on the electric dipole moment of the neutron (nEDM) can be explained by using different mechanisms beyond the Standard Model (SM). The nEDM can be generated by a CP-violating transition of η and η′ mesons into pion pairs. We derive the upper limits for the rates of the CP-violating decays η(η′) → 2π are by orders of magnitude more stringent than those from existing experiments so far.
Generation of baryon asymmetry in the E6CHM
Authors: Nevzorov Roman , Thomas Anthony
Published: October 2018

The strongly interacting sector in theE6inspired composite Higgs model (E6CHM) with baryon number violation possesses an SU(6) ×U(1)Lglobal symmetry. In the weakly-coupled sector of this model theU(1)Lsymmetry associated with lepton number conservation is broken down to aZL2discrete symmetry, which stabilizes the proton. Near the scalef≳ 10 TeV the SU(6) symmetry is broken down to its SU(5) subgroup, giving rise to a set of pseudo- Nambu-Goldstone bosons (pNGBs) that involves the SM-like Higgs doublet, a scalar coloured triplet and a SM singlet boson. Becausefis so high, all baryon number violating operators are sufficiently strongly suppressed. Nevertheless, in this variant of the E6CHM the observed matter-antimatter asymmetry can be induced if CP is violated. The pNGB scalar coloured triplet plays a key role in this process and leads to a distinct signature that may be detected at the LHC in the near future.
The Belle II experiment: status and physics program
Authors: Matvienko Dmitry
Published: October 2018

The Belle II experiment at the SuperKEKB asymmetric-energy e+e- collider in Japan aims to search for new physics in the flavour transitions in the quark and lepton sectors. The SuperKEKB accelerator will operate at the target instantaneous luminosity of 8 × 1035 s-1cm2. It requires a substantial upgrade of the detector subsystems which are expected to record 50 ab-1 of data. Such a huge data sample in clean background environment allows for probing signatures of new physics through suppressed flavour physics reactions and cross checks for deviations from the Standard Model measured at the LHCb experiment. Physics data taking at the Belle II experiment successfully started in April 2018.
Towards a non-perturbative approach to the Hierarchy problem
Authors: Shkerin Andrey
Published: October 2018

In this report, based on [1], we suggest that the hierarchy between the Electroweak (EW) and the Planck scales can emerge due to a nonperturbative effect that relates low-energy and strong-gravity physics. In this mechanism, the EW scale results from an exponential suppression of the Planck scale by an instanton. We illustrate the mechanism in a toy-model example and discuss what features of a theory in the strong-gravity domain would favor its successful implementation.
Geo-neutrino, Earth heat flux, Earth electricity
Authors: Bezrukov L.B. , Kurlovich A.S. , Lubsandorzhiev B.K. , Sinev V.V. , Zavarzina V.P. , Morgalyuk V.P.
Published: October 2018

We discussed the idea of big value of potassium abundance in the Earth. We showed that Borexino single event spectrum permit the potassium abundance up to 2% instead of the CNO neutrino flux contribution. Works [5], [6] introduce the idea that fast α particles are appeared in nuclear processes in solar core plasma. The reactions of these α particles with CNO nuclei can suppress the CNO neutrino flux. We demonstrated the connection between the existence of Earth’s electric field and the big value of 40K geo-neutrino flux because the both phenomena are the sequences from Hydride Earth model.
The linear radial spectrum of scalar mesons from QCD sum rules in the planar limit
Authors: Afonin S.S. , Solomko T.D.
Published: October 2018

We discuss calculations of large-Nc masses of light scalar mesons from the QCD sum rules. Two methods based on the use of linear radial Regge trajectories are presented. We point out the appearance of state near 0.5 GeV in the scalar isoscalar channel which emerges in both methods and presumably corresponds to the lightest scalar particle - the sigma-meson.
News from the NA61/SHINE experiment
Authors: Andronov Evgeny
Published: October 2018

NA61/SHINE is a fixed target experiment operating at the CERN SPS. Its main goals are to search for the critical point of strongly interacting matter and to study the onset of deconfinement. For these goals a scan of the two dimensional phase diagram (T-μB) is being performed at the SPS by measurements of hadron production in proton-proton, proton-nucleus and nucleusnucleus interactions as a function of collision energy. In this paper the status of the NA61/SHINE strong interaction physics programme is presented including recent results on proton intermittency, strongly intensive fluctuation observables of multiplicity and transverse momentum fluctuations. These measurements are expected to be sensitive to the correlation length in the produced matter and, therefore, have the ability to reveal the existence of the critical point via possible non-monotonic behavior. The NA61/SHINE results are compared to the model predictions.
Relaxation to equilibrium and EOS in ultra-relativistic heavy-ion collisions
Authors: Zabrodin E. , Bravina L.
Published: October 2018

We study relaxation to equilibrium of hot and dense hadron-string matter produced in the central zone of central heavy-ion collisions at energies 11:6AGeV ≤ Elab ≤ 160AGeV. Two microscopic transport models, UrQMD and QGSM, are employed. The analysis is performed for the central cubic cell with volume V = 125 fm3. To check how close the system is to the equilibrium, its hadron yields and hadron energy spectra are compared with those of the statistical model of ideal hadron gas. For all collision energies it was found that the matter in the cell was approaching the equilibrium state, which lasted about 10 - 20 fm/c. After that the matter became very dilute and the thermal contact between the hadrons was lost. Equation of state is well fitted to linear dependence P/ε = a = c2s, where the square of the sonic velocity c2s increases from 0.12 at Elab = 11:6AGeV to 0.145 at Elab = 160AGeV. These results are valid also for very early times of the system evolution when the matter is still out of equilibrium. Together with the isentropic expansion, the linear dependence of P on ε supports the application of hydrodynamic description to early stages of heavy-ion collisions.
Mobility edge and Black Hole Horizon
Authors: Gorsky Alexander
Published: October 2018

We conjecture that the mobility edge in the 4D Euclidean Dirac operator spectrum in QCD in the deconfined phase found in the lattice studies corresponds to the near black hole (BH) horizon region in the holographic dual. We present some evidences both from the field theory side and from the worldsheet theory of long open string.
New deformations of N = 4 and N = 8 supersymmetric mechanics
Authors: Ivanov Evgeny
Published: October 2018

This is a review of two different types of the deformed N = 4 and N = 8 supersymmetric mechanics. The first type is associated with the worldline realizations of the supergroups SU(2|1) (four supercharges), as well as of SU(2|2) and SU(4|1) (eight supercharges). The second type is the quaternion- Kähler (QK) deformation of the hyper-Kähler (HK) N = 4 mechanics models. The basic distinguishing feature of the QK models is a local N = 4 supersymmetry realized in d = 1 harmonic superspace.
On 1/N diagrammatics in the SYK model beyond the conformal limit
Authors: Aref’eva Irina , Khramtsov Mikhail , Tikhanovskaya Maria
Published: October 2018

In the present work we discuss aspects of the 1/N expansion in the SYK model, formulated in terms of the semiclassical expansion of the bilocal field path integral. We derive cutting rules, which are applicable for all planar vertices in the bilocal field diagrams. We show that these cutting rules lead to novel identities on higher-point correlators, which could be used to constrain their form beyond the solvable conformal limit. We also demonstrate how the cutting rules can simplify the computation of amplitudes on an example of the six-point function.
Inhomogeneous perturbations in the pseudo-Hermitian quantum cosmology
Authors: Novikov Oleg
Published: October 2018

We consider the quantum cosmology of the phantom fields within the Wheeler-DeWitt approach using the classically equivalent model with complex potential. The Born-Oppenheimer approximation is used to study the behaviour of the inhomogeneous perturbations over the minisuperspace background. The evolution Hamiltonian is treated as a pseudo-Hermitian one and the conserved inner product is constructed within WKB approximation of the homogeneous wavefunction.
On a Probable Anisotropy of the Unruh Radiation: the Case of a Massless Scalar Field in (1+1)D Space-Time
Authors: Kholupenko Evgeny
Published: October 2018

The Unruh effect is considered for the case of a massless scalar field in an (1+1)D space-time. It is shown that under some natural assumptions like finitness of the integration volume or finitness of the interaction propagation speed the effect should be anisotropic.
Modifying the theory of gravity by changing independent variables
Authors: Kharuk N.V. , Manida S.N. , Paston S.A. , Sheykin A.A.
Published: October 2018

We study some particular modifications of gravity in search for a natural way to unify the gravitational and electromagnetic interaction. The certain components of connection in the appearing variants of the theory can be identified with electromagnetic potential. The methods of adding matter in the form of scalar and spinor fields are studied. In particular, the expansion of the local symmetry group up to GL(2,C) is explored, in which equations of Einstein, Maxwell and Dirac are reproduced for the theory with Weyl spinor.
Restrictions on Extended Gravity at Galaxy Clusters Scales
Authors: Alexeyev Stanislav , Latosh Boris , Echeistov Vsevolod
Published: October 2018

Following [1] we discuss the predictions of Starobinsky model of f(R)-gravity with vanishing cosmological constant at galaxy and galaxy clusters scales. As a result we demonstrate that at the current observational accuracy level there is no significant difference in cut-off radius values for Starobinsky model and general relativity (GR) in the mass range from 109MS un till galaxy clusters ones (1018MS un) that shows the good applicability of GR at these ranges.
The post-Newtonian limit of hybrid f(R)-gravity
Authors: Dyadina Polina , Labazova Sofya
Published: October 2018

The post-Newtonian formalism is developed for hybrid f(R)-gravity. The model is tested in the weak field regime of the Solar System. Using scalartensor representation of hybrid f(R)-gravity we impose restrictions on the parameters of the theory and show that hybrid f(R)-gravity is not ruled out by the observations in the weak field limit.
A simple UV completion for Higgs and Higgs-dilaton inflation
Authors: Gorbunov Dmitry , Tokareva Anna
Published: October 2018

In this work, we present a UV completion for the Higgs and Higgsdilaton inflation which can be reached by adding only one extra R2 term in the gravity sector. We show that, in this case, the strong coupling scale is lifted up to the Planck scale.
Ultra-high-energy cosmic rays mass composition studies with the Telescope Array Surface Detector data
Authors: Zhezher Yana
Published: October 2018

The results on ultra-high energy cosmic rays’ chemical composition based on the data from the Telescope Array surface detector are reported. The analysis is based the boosted decision tree (BDT) multivariate analysis built upon 14 observables related to both the properties of the shower front and the lateral distribution function. The multivariate classifier is trained with Monte-Carlo sets: proton-induced, which is considered as background events, and ironinduced, considered as signal events. The classifier results in a single variable ξ for data and Monte-Carlo sets, available for one-dimensional analysis. The data to Monte-Carlo comparison results in an average atomic mass of UHECR for energy range 1018:0 - 1020:0 eV. The average atomic mass of primary particles corresponds to 〈ln A〉 = 1:52± 0:08(stat.)± 0:1(syst.). The comparison with TA hybrid composition results and the other experiments is presented.
Mass composition of cosmic rays with energies from [1017.2]eV to [1020]eV using surface and fluorescence detectors of the Pierre Auger Observatory
Authors: Kukec Mezek Gašper
Published: October 2018

Ultra-high-energy cosmic rays (UHECRs) are highly energetic particles with []EeV energies, exceeding the capabilities of man-made colliders. They hold information on extreme astrophysical processes that create them and the medium they traverse on their way towards Earth. However, their mass composition at such energies is still unclear, because data interpretation depends on our choice of high energy hadronic interaction models. With its hybrid detection method, the Pierre Auger Observatory has the possibility to detect extensive air showers with an array of surface water-Cherenkov stations (SD) and fluorescence telescopes (FD). We present recent mass composition results from the Pierre Auger Collaboration using observational parameters from SD and FD measurements. Using the full dataset of the Pierre Auger Observatory, implications on composition can be made for energies above [1017.2]eV.
Forensic engineering - fib MC 2020 and existing structures
Authors: Matthews Stuart , Mancini Giuseppe
Published: October 2018

The fib (Fédération Internationale du Béton) is developing a new fib Model Code for Concrete Structures, under a working title of Model Code 2020 (MC2020). Numerous aspirational goals have been identified for MC2020. It will be a single code dealing with both new and existing concrete structures, which is both the design of new structures and all the activities relating to the assessment, interventions and the through-life management and care of existing concrete structures, including matters relating to durability and service life design. MC2020 will incorporate many improvements and extensions to the guidance available in the current fib Model Code for Concrete Structures fib Model Code 2010 (MC2010). The new and extended models, in association with the other aspects of the updated guidance, will provide improved technical capabilities for undertaking forensic engineering studies of existing concrete structures. These concepts are illustrated by a number of case studies of existing concrete structures subject to damage / deterioration / other inadequacies, as well as associated intervention works. Improved technical guidance provisions will allow forensic engineers to gain a better understanding of the behaviour of existing concrete structures, enabling better judgements to be made of how they behave in-service & what measures / interventions are most appropriate to extend their useful life.
Modelling of chloride ingress in concrete based on benchmarking field results
Authors: Koenders E.A.B.
Published: October 2018

Modelling the ingress of chloride ions into the cover of a concrete structure is a phenomenon that is gaining an increasing attention of the research community, but even more, from the engineering practice. As the mechanism that drives the ingress of chlorides is implicitly responsible for the service-life of concrete structures, its input parameters are a major issue whenever predicting the service-life of new concrete structures. In this paper most relevant parameters involved in the evaluation of chloride ingress models are discussed and related to the benchmark activities that currently run in RILEM TC 270-CIM on benchmarking Chloride Ingress Models. The results provide an overview of the models used in the structural design stage, mostly analytical models, and in the rehabilitation stage, mostly numerical models.
Sustainable, durable concrete – are specifications always fit for purpose – a case study
Authors: Grantham Michael G
Published: October 2018

This paper examines the drive in the construction industry to source materials for new construction sustainably. It examines the key drivers that sustainable construction entails but also looks at the crucial impact that over-specifying can have on the performance of concrete in the field. Sustainability is, however, just one concern to the modern Engineer, and ensuring the concrete can be placed and compacted adequately is also a very real concern, especially where visual concrete is concerned. The paper examines some of the issues around sustainability and also looks at several case studies where concrete has not performed as expected and has caused very real problems in the field, when using secondary cementitious materials (SCMs) in conjunction with superplasticiser. The paper concludes with some guidance on how to achieve the best of both aims sustainability and durability, while avoiding some of the pitfalls that can occur.
Microbial induced acid corrosion from a field perspective - Advances in process understanding and construction material development
Authors: Grengg Cyrill , Mittermayr Florian , Ukrainczyk Neven , Koenders Eddie , Koraimann Günther , Kienesberger Sabine , Dietzel Martin
Published: October 2018

Microbial induced acid corrosion is accounted for ~40 % of the degradation of subsurface wastewater infrastructure globally. While fundamental process understanding has increased significantly within the last decades, to date no sustainable building material exists, which meets the long-term requirements in such aggressive and corrosive environments. This work describes a novel model based on field studies, conducted in various Austrian sewer networks, intertwining biological, mineralogical and hydro-chemical factors. Additionally, an extensive field testing campaign over the duration of 18 months, conducted on different geopolymer concretes (GPC), particularly designed for the latter environments will be presented. Innovative GPCs were tested regarding their microstructural behavior, microbial accessibility and hydro-chemical alterations over time and compared to commercially produced cement based products, including OPC and CAC concretes. Additionally, the system specific environmental parameters, such as relevant gas concentrations (H2S, CO2, CH4), relative humidity and temperature were constantly monitored.
Sulfate Resistance of Rice Husk Ash Concrete
Authors: Kamau John , Ahmed Ash , Ngong Killian
Published: October 2018

Durability of concrete is defined as its ability to resist deterioration after exposure to the environment of its use. This work investigates the performance of Rice Husk Ash (RHA) concrete in sodium sulfate (Na2SO4), magnesium sulfate (MgSO4) and combined Na2SO4 and MgSO4 solutions. Concrete bar specimens and cubes were prepared for expansion and strength deterioration tests respectively using RHA replacement at the 7.5% replacement by volume, which had achieved the highest compressive strength, as well as at the 30% replacement by volume, which was the highest replacement for the study. Strength deterioration tests were performed on the 7.5% replacement by the weight of cement. From the expansion test findings, it was concluded that at the 7.5% replacement, RHA could be used with an advantage over 100% cement concrete in MgSO4 environments, whereas at the 30% replacement, RHA could be used with an advantage over 100% cement concrete in both the Na2SO4 and mixed sulfate environments. RHA was also found to be more effective in resisting surface deterioration in all the sulfate solutions. The RHA specimens also exhibited superior strength deterioration resistance in comparison to the 100% cement specimens.
Assessment of the effect of nanosilica on the mechanical performance and durability of cementitious materials
Authors: Lefever Gerlinde , Aggelis Dimitrios G. , De Belie Nele , Snoeck Didier , Van Hemelrijck Danny
Published: October 2018

Over the last years, nanotechnology is getting more attractive and nanomaterials are being used more commonly in construction industry. One of these materials is nanosilica: the nano-sized, engineered form of silica fume. The replacement of cement by these nanoparticles is said to enhance both the mechanical performance and the durability of the concrete material. In this paper colloidal silica will be used, which is nanosilica in solution. A characterization of mortar mixtures containing different amounts of silica is done and a comparison is made with respect to a reference mixture.
Lucas-Washburn vs Richards equation for the modelling of water absorption in cementitious materials
Authors: Villagrán Zaccardi Yury , Alderete Natalia , De Belie Nele
Published: October 2018

The Lucas-Washburn equation is still being applied by a significant number of researchers for the modelling of water absorption in cementitious materials. A modern approach considers the extended Darcy’s law leading to the Richards equation instead. Three main assumptions are implied by the application of the Lucas-Washburn equation: the flow occurs in one direction only, the material is separated into one fully wet and one fully dry region, and pores are modelled as an assembly of parallel tubes of a particular radius. Its application to analyse experimental results allows defining these three assumptions as mere simplifications. Therefore, all the parameters comprised in the Lucas-Washburn model are apparent. Consequently, a very limited description of the transport properties of the material can be achieved. For many engineering purposes this would not be an issue, but for an intrinsic description of the material a more realistic model is required. This paper discusses the limitations of the Lucas-Washburn equation, and the advantages of the Richards equation regarding the modelling of water absorption in cementitious materials. The comparative analysis reveals the versatility of the Richards equation, with an approach that considers the material as a continuum and describes it through measurable parameters.
Coal gasification ash and Weathered fly ash, as partial replacement of Portland cement – effect on selected durability properties of concrete
Authors: Maboea Dikeledi , Otieno Mike
Published: October 2018

This study uses Sasol ashes as cement extenders to contribute to the technology of partially replacing Portland cement by mass. There are two types of Sasol ashes; coal gasification ash (CGA) and weathered fly ash (WFA) produced from low grade coal. These ashes are disposed of by Sasol with no specific utilisation. In this investigation, PC will be partially replaced by mass with WFA, CGA and FA at 10%, 15% and 30% proportions for each type of ash. The durability indices will be measured and compared for all blended specimen (PC/WFA, PC/CGA and PC/FA). A 100% Portland cement specimen will be used as a control. The durability properties will be used to determine the potential of Sasol ashes being used as a cement extender.
Concrete quality on-site vs separately manufactured specimens
Authors: Jacobs Frank
Published: October 2018

In most cases insufficient durability is the reason for concrete damages and not insufficient strength. Therefore, the Swiss concrete standard SN EN 206 set up requirements on the concrete composition and the testing of separately manufactured concrete samples. It is well known that the properties of concrete in structural members can deviate from that determined on separately manufactured samples. A research project was launched to determine this difference. Based on the results an appropriate testing regime should be proposed and the limiting values for the durability properties should be verified.
Modelling of Alkali Silica Reaction in concrete structures for rehabilitation intervention
Authors: Pourbehi Mohammad S. , van Zijl G.P.A.G. , Strasheim J.A.v.B.
Published: October 2018

A number of hydraulic structures such as dams and hydro-power plants in the world and in particular, in South Africa which have been designed and built during the last decades, have been subjected to material deterioration due to Alkali Silica Reaction (ASR). ASR is a deleterious chemical reaction between the alkalis in Portland cement paste and certain amorphous silica found in various types of natural aggregates which usually results in material degradation and structural distress such as expansion of the structure, cracking, presence of gel, discoloration and pop outs of the reacting particles near the surface of the concrete. Also, suitable environmental conditions (temperature and relative humidity) play a vital role in the initiation and advancement of ASR. In this study a chemo-thermo-mechanical model is developed to predict the structural expansion, degradation of mechanical properties, cracks and damage in concrete structures affected by ASR. Parameters such as temperature, kinetics of the reaction, confining stresses and material degradation are included in the model. The finite element based model can simulate the temperature field in the structure and the kinetics of the chemical reaction to predict the long-term effects of the ASR on concrete structures including displacement, cracking and damage development. The model is applied to an actual concrete dam subjected to ASR. The results are interpreted, and support the management and evaluation of the remedial measures for repair and maintenance programmes for the affected dams.
Macrocell corrosion between crossed steel rebars embedded in concrete under chloride environments
Authors: Gu Xianglin , Dong Zheng , Jin Zhihao
Published: October 2018

Steel reinforcement corrosion is found to be more severe at stirrups or some intersection zones of steel rebar mesh in concrete structures subjected to chloride penetration. This can be caused by macrocell corrosion formed between steel rebars with different potentials. Such potential differences are usually contributed by 1) chloride concentration gradients during the penetration process and 2) material differences between crossed steel rebars. With the forming of macrocell corrosion, the anodic current of steel with more negative potential will increase. The present study aims to deal with the macrocell corrosion between crossed steel macro-couples by dividing the steel rebar into intersected zone (IZ) and non-intersected zone (NIZ). The distribution of macrocell current on the surfaces of NIZ was obtained by means of a transmission line model. Based on the calculated macrocell current, the influence of the macrocell corrosion on the service life of reinforced concrete (RC) structures was analyzed. The results showed that the coupled micro- and macro-cell corrosion of stirrups could accelerate the change of the failure mode of a beam from bending to shear failure when the macrocell corrosion rate was no less than the microcell corrosion rate.
Effect of the degree of corrosion on bond performance of Cement Polymer Composite (CPC) Coated steel rebars
Authors: Kamde Deepak K. , Pillai Radhakrishna G.
Published: October 2018

Currently, large infrastructures (bridges, highways, etc.) are designed for more than 100 years. To achieve long service life, coated rebars (mostly, cement polymer composite (CPC) coated rebars) are being used to enhance the corrosion resistance. However, inadequately coated rebars can lead to premature corrosion. This can also affect the bond between the rebar and the concrete. To assess the effect of CPC coating on bond strength, pull-out specimens of (150×150×100) mm with 12 mm diameter rebar with 100 mm embedded length were cast and tested. For this, three replica specimens with two types of reinforcement namely, i) Uncoated steel ii) CPC coated steel were cast. To induce corrosion, additional five specimens with CPC coated steel rebars were cast with premixed chloride and cured for 28 days. During the curing period, continuous monitoring of corrosion potential and rate was done and degree of corrosion was assessed. The effect of degree of corrosion on bond of steel-concrete-coating interface was quantified. The CPC coated rebars without corrosion exhibited 10% bond reduction. CPC coated rebars with corrosion exhibited 30-70% reduction in bond strength. Also, the corrosion is found to adversely influence the stiffness of the bond.