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MESOGRANULATION AND THE SOLAR SURFACE MAGNETIC FIELD DISTRIBUTION
Yelles Chaouche, L.,Moreno-Insertis, F.,Martí,nez Pillet, V.,Wiegelmann, T.,Bonet, J. A.,Knö,lker, M.,Bellot Rubio, L. R.,del Toro Iniesta, J. C.,Barthol, P.,Gandorfer, A.,Schmidt, W.,Solank IOP Publishing 2011 ASTROPHYSICAL JOURNAL LETTERS - Vol.727 No.2
Influence of viscosity modifying admixtures on the rheological behavior of cement and mortar pastes
Bouras, R.,Kaci, A.,Chaouche, M. 한국유변학회 2012 Korea-Australia rheology journal Vol.24 No.1
The influence of Viscosity-modifying admixtures (VMA) dosage rate on the steady state rheological properties, including the yield stress, fluid consistency index and flow behaviour index, of cementitious materials is considered experimentally. The investigation is undertaken both at cement paste and mortar scales. It is found that the rheological behaviour of the material is in general dependent upon shear-rate interval considered. At sufficiently low shear-rates the materials exhibit shear-thinning. This behaviour is attributed to flow-induced defloculation of the solid particles and VMA polymer disentanglement and alignment. At relatively high shear-rates the pastes becomes shear-thickening, due to repulsive interactions among the solid particles. There is a qualitative difference between the influence of VMA dosage at cement and mortar scales: at cement scale we obtain a monotonic increase of the yield stress, while at mortar scale there exists an optimum VMA dosage for which the yield stress is a minimum. The flow behaviour index exhibit a maximum in the case of cement pastes and monotonically decreases in the case of mortars. On the other hand, the fluid consistency index presents a minimum for both cement pastes and mortars.
The March 2017 earthquake sequence along the E-Wtrending Mcid Aïcha-Debbagh Fault, northeast Algeria
Hichem Bendjama,Abelkarim Yelles-Chaouche,Oualid Boulahia,Issam Abacha,Yahia Mohammedi,Hamoud Beldjoudi,Sofiane Taki-Eddine Rahmani,Othmane Belheouane 한국지질과학협의회 2021 Geosciences Journal Vol.25 No.5
In Northeast Algeria, a sequence of 143 small earthquakes (Md ≤ 4.7) occurred near the Mcid Aïcha-Debbagh (MAD) Fault between 4 and 16 March, 2017. During this sequence, 74% of the seismic activity occurred in the first two days. Although the earthquakes were not large, they yielded important new information and have improved our understanding of seismic activity in three distinct regions along the fault. In the Sidi Dris region (western MAD Fault), 106 events (1 ≤ Md ≤ 3.2) were located in an aftershock cluster trending NNE-SSW, highlighting a transverse fault with ~6 km of strike-slip displacement that locally cuts the MAD Fault. In the El Kantour region (central MAD Fault), 31 events were recorded along a 3 km long fault segment, including the Mw 4.7 mainshock. The mainshock had a focal mechanism consistent with predominantly strike-slip motion on a N110°E-striking fault plane, in agreement with the WNW-ESE orientation of the central MAD Fault segment. Finally, six diffuse events occurred in the Hammam Debbagh region (eastern MAD Fault). A significant event (Md 3.0) in this region had a focal mechanism consistent with strike-slip movement and a normal component trending NW-SE. This is consistent with the fault plane orientations of key events in the time period 2003–2014, likely related to the NW-SE-striking Hammam Debbagh Fault. The present-day stress tensor is characterized by a strike-slip tectonic regime and a σ1 orientation (N342°E) that closely matches the maximum regional compressive stress orientation (NNW-SSE).
Asma Khemis,Abdelmadjid Hacene Chaouche,Allaeddine Athmani,Kong Fah Tee 국제구조공학회 2016 Structural Engineering and Mechanics, An Int'l Jou Vol.59 No.4
The failure of civil engineering systems is a consequence of decision making under uncertain conditions. Generally, buried flexible pipes are designed for their transversal behavior to prevent from the important failure mode of buckling. However, the interaction effects between soil and pipe are neglected and the uncertainties in their properties are usually not considered in pipe design. In this regard, the present research paper evaluates the effects of these uncertainties on the uncertainty of the critical buckling hoop force of flexible pipes shallowly buried using the subgrade reaction theory (Winkler model) and First-Order Second-Moment (FOSM) method. The results show that the structural uncertainties of the studied pipes and those of the soil properties have a significant effect on the uncertainty of the critical buckling hoop force, and therefore taking into account these latter in the design of the shallowly flexible pipes for their buckling behavior is required.
In-vitro antioxidant and antimicrobial activities of some varieties citrus grown in Algeria
Nacera Haraoui,Rachida Allem,Tarik Mohammed Chaouche,Ahmed Belouazni 경희대학교 융합한의과학연구소 2020 Oriental Pharmacy and Experimental Medicine Vol.20 No.1
Polyphenols are scientifically researched molecules because of their multiple biological activities. This study aims to compare the phenolic content and estimate the antioxidant and anti-microbial activities of leaf extracts and juice of ten varieties Citrus fruits grown in Algeria. Antioxidant properties were evaluated by DPPH radical scavenging activity, β-carotene-linoleic acid system and ferric reducing antioxidant capacity. Antimicrobial activity was carried out using agar well diffusion method. The results showed the highest levels of phenolic compounds in juice and leaves of different part and varieties of plant (*P < 0.05). Among all the varieties, C. maxima and C. aurantium presents the highest activity for the three methods cited previously (94.44–91.66% and 95.41–83.84%). On the other hand, antibacterial activity present on the plates was indicated by an inhibition zone surrounding the well containing the juice. The C. Limon and C. aurantium varieties exhibited the highest antimicrobial activity, with inhibition zone ranging from (27.66 ± 0.58, 24.66 ± 1.53 mm) followed by grapefruit and mandarin with areas between (23.00 ± 1.00, 17.66 ± 0.58 mm) on the isolates used. In this study, whatever the parts of citrus (juice and leaves) have been found to contain higher amounts of phenolics and their efficiency as potent antioxidants and antimicrobial properties was confirmed.
Influence of viscosity modifying admixtures on the rheologicalbehavior of cement and mortar pastes
R. Bouras,A. Kaci,M. Chaouche 한국유변학회 2012 Korea-Australia rheology journal Vol.24 No.1
The influence of Viscosity-modifying admixtures (VMA) dosage rate on the steady state rheological properties, including the yield stress, fluid consistency index and flow behaviour index, of cementitious materials is considered experimentally. The investigation is undertaken both at cement paste and mortar scales. It is found that the rheological behaviour of the material is in general dependent upon shear-rate interval considered. At sufficiently low shear-rates the materials exhibit shear-thinning. This behaviour is attributed to flow-induced defloculation of the solid particles and VMA polymer disentanglement and alignment. At relatively high shear-rates the pastes becomes shear-thickening, due to repulsive interactions among the solid particles. There is a qualitative difference between the influence of VMA dosage at cement and mortar scales: at cement scale we obtain a monotonic increase of the yield stress, while at mortar scale there exists an optimum VMA dosage for which the yield stress is a minimum. The flow behaviour index exhibit a maximum in the case of cement pastes and monotonically decreases in the case of mortars. On the other hand, the fluid consistency index presents a minimum for both cement pastes and mortars.
Buckling Uncertainty Analysis for Steel Pipelines Buried in Elastic Soil Using FOSM and MCS Methods
Allaeddine Athmani,Asma Khemis,Abdelmadjid Hacene Chaouche,Kong Fah Tee,Tiago Miguel Ferreira,Romeu Vicente 한국강구조학회 2019 International Journal of Steel Structures Vol.19 No.2
Generally, buried steel pipes are designed for good transverse behavior by neglecting soil–structure interaction eff ect. Steel pipelines are also usually designed to prevent from the important failure mode of buckling. However, the design of this type of structures does not normally consider the uncertainties in soil and structural properties. To address the above issues, the paper estimates the uncertainties in terms of the coeffi cient of variation of critical buckling displacement, CV w using subgrade reaction theory (Winkler model) and fi rst-order second-moment (FOSM) method. Two cases of boundary conditions have been considered in this study. In the fi rst case, CV w is calculated within an infi nitely thick soil as a function of uncertainty of subgrade reaction modulus ( K s ). In the second case, CV w is calculated in a thick soil cylinder as a function of the uncertainty of the eff ective subgrade reaction modulus ( K′ S ). Furthermore, the uncertainty of pipe fl exibility ( S f ) is also taken into account in the two cases. Uncertainty calculations by the FOSM method are then validated with those obtained from traditional Monte Carlo simulations.