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Influence of specimen-reconstituting method on the undrained response of loose granular soil under static loading

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Acta Mechanica Sinica 2011年第5期27卷 796-802页

作者： Noureddine Della Ahmed Arab mostefa Belkhatir Laboratory of Material Sciences and Environment Civil Engineering DepartmentUniversity of ChlefSendjas Street PO Box 151 Chlef 02000Algeria

This paper describes the results of an experimental study on the undrained shear behaviour of loose sand collected from the location close to the epicenter of the recent Chlef （Algeria） Earthquake （October 10,1980）.The study focuses on the effects of the mode of the soil deposition on the liquefaction resistance of the Chlef *** this purpose,the results of undrained monotonic triaxial compression tests performed on samples with initial density of 0.29 under initial confining pressures ranged from 50 kPa to 200 kPa are *** specimens were prepared by two depositional methods namely dry funnel pluviation and wet *** was found that there was a marked difference in the undrained behaviour of sand in terms of maximal deviatoric stress,peak strength,residual strength and excess pore water pressure,even though the density and stress conditions were *** conclusion was that the soil fabric was responsible for this *** results indicated also that at low confining pressures,the specimens reconstituted by the wet deposition method exhibited complete static liquefaction （zero effective confining pressure and zero stress difference）.

关键词： Liquefaction · Undrained · Dry funnel pluviation · Wet deposition · Residual strength

Economic and Human Loss Empirical Models for Earthquakes in the Mediterranean Region, with Particular Focus on Algeria

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International Journal of Disaster Risk Science 2017年第4期8卷 415-434页

作者： Abdelheq Guettiche Philippe Guguen mostefa Mimoune Centre Universitaire Abdelhafid Boussouf Civil Engineering Department Universitdes Frères Mentouri Institut des Sciences de la Terre (ISTerre) Universitde Grenoble Alpes/CNRSIFSTTAR

In this study, loss estimation models were developed for reasonably accurate assessment of economic and human losses from seismic events in the Mediterranean region, based on damage assessment at an urban *** were compiled from existing worldwide databases,and completed with earthquake information from regional studies. Economic data were converted to a single common currency unit(2015 USD value) and the wealth of the areas affected by 65 earthquakes of the region from 1900 to 2015 was assessed. Reduced-form models were used to determine economic and human losses, with earthquake magnitude and intensity as hazard-related variables, and gross domestic product of the affected area and the affected population as exposure-related variables. Damage to buildings was also used as a hazard-related variable to predict economic and human losses. Finally, site-specific regression models were proposed for economic and human losses due to earthquakes in the Mediterranean region, and more specifically, in Algeria. We show that by introducing the damage variable into the models, prediction error can be reduced, and that accuracy of loss model estimation is site dependent and requires regional data on earthquake losses to improve. A case study for Constantine, Algeria shows the improvements needed for increased accuracy.

关键词： Algeria Earthquake loss estimation Mediterranean region Reduced-form models Seismic intensity Seismic magnitude

Laboratory Study of Geotextiles Performance on Reinforced Sandy Soil

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Journal of Earth Science 2016年第6期27卷 1060-1070页

作者： Brahim Abdelkader Arab Ahmed Belkhatir mostefa Shahrour Isam Laboratory of Materials Sciences and Environment Civil Engineering Department Hassiba Ben Bouali University of ChiefChief 02000Algeria Laboratory of Civil Engineering and Geo-Environment(LGCGE) University of Lille 1Villeneuve d'Ascq 59650France

This paper presents the results of triaxial tests conducted for the investigation of the influence of geotextiles on stress-strain and volumetric change behaviour of reinforced sandy soil. Tests were carried out on loose sandy soil. The experimental program includes drained compression tests on samples reinforced with different values of both geotextiles layers （Ng） and confining pressure （σ′c）. Two methods of preparation were used： air pluviation （AP） and moist tamping （MT）. Test results show that the geotextiles induce a quasi-linear increase in the stress deviator （q） and volume contraction in the reinforced sand. Method of preparation significantly affects the shear strength; samples prepared by the air pluviation method and mobilized deviator stresses are significantly higher than those prepared by moist tamping method. Geotextiles restrict the dilation of reinforced sandy soil and consequently the contraction increases. The mobilized friction angle increases with increasing number of layers and decreases with increasing initial confining pressure. Samples prepared by moist tamping present mobilized friction angles significantly lower than those prepared by air pluviation method. For samples prepared by the air pluviation method, the secant modulus at ε1=1% and 5% decreases with increasing geotextile layers; those prepared by the moist tamping method, secant modulus at ε1=1% and 5% increases with increasing number of geotextile layer sand confining pressure. From 10% axial strain, secant modulus increases with increasing inclusions of geotextile layers.

关键词： sand triaxial geotextile drained method of preparation strength.

Hydrogeochemical processes and multivariate analysis for groundwater quality in the arid Maadher region of Hodna,northern Algeria

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Acta Geochimica 2022年第5期41卷 893-909页

作者： Tahar Selmane mostefa Dougha Mahmoud Hasbaia Ahmed Ferhati Ali Redjem VESDD Laboratory University of M’sila28000 M’silaAlgeria

This study focused on water quality and hydrogeochemical processes(evolution,origin)in the Maadher region,central Hodna in *** recent decades,the excessive exploitation of this resource due to urbanization,irrigation,and the effect of climate change reaching the countries of northern Africa have caused a decline in water levels and hydrochemical changes in the *** sampling campaign in 2019 based on 13 physicochemical parameters was carried out on the water from 32 boreholes in the study area,compared to data archives of both sampling campaigns in 1967 and *** result revealed that the groundwater as a whole has moderate freshwater quality,due to its total dissolved solids(TDS)content and other dissolved ions of concern(nitrate NO),which exceed WHO *** addition,Piper diagram indicates that the hydrochemical facies of sulfate–chloride–nitrate–calcium(SO–Cl–NO–Catype),which globally characterizes the study area and these elements are the dominant dissolved *** component analysis and hierarchical cluster analysis(HCA)methodologies are applied in order to define the major control factors that affect the hydrochemistry of Maadher *** distinct water groups were found,illustrating a different evolution of salinity(EC and TDS).The HCA indicated an interesting cluster with a distinct contamination signature and most likely with significantly higher sulfate,chloride,and nitrate *** processes also play an important role in the study *** water resource comes from Bousaada Wadi,the exchange at the aquifer depth and the agricultural practices contribute to the deterioration of the quality.

关键词： Groundwater quality Hydrogeochemical processes Multivariate analysis Salinity Mio-Plio-Quaternary aquifer

Elaboration of AlSi10Mg casting alloys using directional solidification processing

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International Journal of Minerals,Metallurgy and Materials 2015年第5期22卷 509-515页

作者： Khadoudja Ghedjati Eric Fleury Mohamed Seghir Hamani mostefa Benchiheub Khaider Bouacha Bernard Bolle Systems and Advanced Materials Laboratory (LASMA) Department of Physics Faculty of Science Badji Mokhtar University of Annaba Microstructure Investigation and Material Mechanic Laboratory (LEM3) CNRS Lorraine-Metz University Faculty of Science Souk Ahras University Foundry Research Laboratory (LRF) Department of Physics Faculty of Science Badji Mokhtar University of Annaba

The effects of pulling velocity on the solidification behavior and microstructural parameters of A1Sil0Mg alloys prepared in a Bridgman-type directional solidification furnace were investigated. The microstructure, particularly the secondary dendritic arm spacing （SDAS）, and the Brinell hardness （BH） of the solidified A1Sil0Mg alloys were characterized for samples with cylindrical shapes and differ- ent conicities （θ = 0°, 5°, and 10°）. Microstructural studies revealed an increased density of ct-A1 phase dendrites and a decreased interden- dritic distance with increasing pulling velocity. The dendrites were found to be preferentially oriented along the pulling direction for low pulling velocities. For larger pulling velocities, the dendrites grew first in the cooling direction but then broke as others nucleated and coars- ened. The HB values of the solidified samples increased as the pulling velocity increased. In regard to sample conicity, smaller dendrites were observed for an apex angle of θ = 5°, resulting in the largest HB value. This result was interpreted in terms of the favorable orientation of the dendrite along the pulling direction.

关键词： aluminum-silicon-magnesium alloys directional solidification Bridgman technique mierostructure hardness heat flow growth

Does melanin-based plumage coloration reflect health status of free-living birds in urban environments?

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Avian Research 2021年第4期12卷 553-568页

作者： Hani Amir Aouissi mostefa Ababsa Aissam Gaagai Zihad Bouslama Yassine Farhi Haroun Chenchouni Scientific and Technical Research Center on Arid Regions(CRSTRA) 07000 BiskraAlgeria Faculty of Sciences Department of BiologyBadji-Mokhtar Annaba University23000 AnnabaAlgeria Environmental Research Center(CRE) Badji-Mokhtar Annaba University23000 AnnabaAlgeria Department of Nature and Life Sciences Faculty of Exact Sciences and Nature and Life SciencesUniversity of Larbi Tebessi12002 TebessaAlgeria Labora-tory of Natural Resources and Management of Sensitive Environments‘RNAMS’ University of Larbi Ben M’hidi04000 Oum-El-BouaghiAlgeria

Background:Ecological functions and processes in urban ecosystems are governed by various human ***-adapted and city-exploiting animal species are expected to present certain specific behavioral and physiological traits in comparison to city-avoiders or conspecific individual frequenting less urbanized or rural environments.A trait of high importance,the plumage color polymorphism has been selected as the main study model and was correlated with different morphological and physiological parameters to highlight its importance in determining the possible health status of urban Feral Pigeons(Columba livia)in North African urban ***:Different body morphometrics,hematological and hemoparasitic parameters were quantified on freeliving Feral Pigeons in urban environments of northern ***,plumage melanin-based coloration(MBC)was measured and the data collected at the individual scale was correlated with the previous parameters using linear and non-linear modeling ***:Plumage MBC scores of the sampled Feral Pigeons ranged between 0.3%and 74.8%.Among the 12 morphological traits measured,body weight,tail length and total length were deemed to be positively correlated with *** morphs appeared to have more hemoparasites compared to lighter *** the same observation goes with the immunity but with non-linear *** number of monocytes and granulocytes increased with the increase in MBC levels in lighter morphs,while pigeons with high MBC scores exhibited negative relationships between MBC levels and the number of white blood ***:Despite the existence of a number of studies demonstrating phenotypic directional selection,further studies are undoubtedly necessary to understand in detail the underlying mechanisms in species life-history strategies between differently colored *** of this correlative study open exciting perspectives revealing that MBC can be considered a good indicato

关键词： Columba livia Feather color polymorphism Feral birds Hematological indicators Hemoparasitism Immune ecophysiology Urbanization Urban ornithology

Rainfall patterns of Algerian steppes and the impacts on natural vegetation in the 20^th century

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Journal of Arid Land 2018年第4期10卷 561-573页

作者： Fahima BELALA Azziz HIRCHE Serge D MULLER Mahmoud TOURKI mostefa SALAMANI Mohamed GRANDI TaharAIT HAMOUDA Madjid BOUGHANI Laboratory of Plant Ecology Faculty of Biological SciencesUniversity of Sciences and Technology Houari BoumedieneWilaya 16000Algeria Scientific and Technical Research Center on Arid Regions Biskra 7000Algeria Institute of Evolutionary Sciences University of Montpellier-CNRSMontpellier 34095France Department of Hydraulics University of Badji MokhtarAnnaba 23000Algeria Faculty of Nature Sciences University of Saad DahlabBlida 9000Algeria Faculty of Sciences University of Yahia FaresWilaya 26000Algeria

Since 1960, the steppe regions of North Africa have been subject to an increasing desertification, including the degradation of traditional pastures. The initially dominant species （Artemisia herba-alba, Lygeum spartum and Slipa tenacissima） declined and were progressively replaced by other species （Atractylis serratuloides and Salsola vermiculata） that are more tolerant to the new conditions. It is not clear whether these changes are due to anthropogenic reasons or climatic determinism. We have carried out a statistical analysis of the climate to detect putative rainfall changes during the 20th century in the Algerian steppes based on data from 9 meteorological stations, including 2 Saharan stations （El Oued and Touggourt）, 3 pre-Saharan stations （Biskra, Laghouat and Ain Sefra） and 4 steppe stations （Djelfa, Saida, M6ch6ria and E1-Bayadh） located in the arid high plains, which represent the bioclimate diversities of the region. Previous studies suggested that significant rainfall changes for the 20th century only had records in the south of the Oran region. Most of the studies, however, looked at restricted territories over limited periods, and did not integrate the rainiest period 2004-2014. Our work is designed to integrate all the longest time series of meteorological data available for the steppe regions of Algeria. Our results confirm the spatial rainfall distribution （significant rainfall changes only recorded in the southwestern region） evidenced by previous studies, and reveal a decreasing rainfall gradient from northeastern to southwestern Algeria. Moreover, the results reveal a trend of significant decrease of rainfall in the southern Oran region, marked by two drought periods in 1980- 1985 and 1999-2003. However, with the exception of the southwestern region, rainfall overall has not declined since the beginning of the 20th century. While less marked in other regions, the drought appear to have affected all territories of the Algerian steppe. Consequent

关键词： climate arid and semi-arid regions drought rangeland degradation human impact North Africa

卫星遥感图像非监督变化检测及其在洪涝区域的应用研究

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卫星遥感图像非监督变化检测及其在洪涝区域的应用研究

作者： REZKI mostefa 哈尔滨工业大学

学位级别：硕士

目前通过遥感获取的图像的常见用途是对地球表面发生的变化进行详细监测。这些变化(如洪水)会产生光谱差异,可通过遥感图像分析进行区分。无论图像的来源和表面变化的类型如何,这些数据的正确处理意味着采用灵活,稳健且可能非线性的方... 详细信息

目前通过遥感获取的图像的常见用途是对地球表面发生的变化进行详细监测。这些变化(如洪水)会产生光谱差异,可通过遥感图像分析进行区分。无论图像的来源和表面变化的类型如何,这些数据的正确处理意味着采用灵活,稳健且可能非线性的方法来计算正确表征图像像素的复杂统计关系。在变化检测领域已经建立了许多方法。实际上,检测变化是一个过程,需要谨慎考虑许多功能,如检测变化问题的性质,图像处理预设,选择合适的变量和算法来解决CD问题。传统的变化检测方法消耗更多的时间,与手动调节有关,并且受到区域内噪声或复杂光谱类别的影响。通过这些方法获得的变化地图通常会出现孤立变化的像素并且呈现低精度。因此,无监督变化检测是一种完全自动且无监督的方法,用于对变化进行准确的二进制检测。该技术允许在没有任何用户干预的情况下进行精确的映射,这导致当待机和系统响应时间是确定在不同时间获取的两个或多个配准的遥感图像变化的关键障碍时特别有用。核心k均值聚类过程用于将两组像素相关联到“变化”和“无变化”类。我们提供了一种有效的方法来区分这两类变化:这种方法依赖于三个不同的步骤:(A)初始化聚类,(B)核函数参数估计和聚类,以及(C)最终分配像素到他们的类。为了评估Kkm技术对多种遥感图像和应用的有效性,通过Landsat TM获得两个不同的数据集。结果显示了这种自动CD方法用于环境变化监测的灵活性和有效性。

关键词：遥感非线性方法变化检测变化图精度无监督变化检测核k-均值聚类

Acoustic Emission Characterization of Matrix Damage Initiation in Woven CFRP Composites

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Materials Sciences and Applications 2013年第9期4卷 509-515页

作者： mostefa Bourchak Adnan Khan Salah A. Badr Wail Harasani Aeronautical Engineering Department King Abdulaziz University Jeddah Saudi Arabia Mining Engineering Department King Abdulaziz University Jeddah Saudi Arabia

In this paper, an experimental investigation is performed using acoustic emission (AE) technique to study the behaviour of crack initiation and propagation of woven carbon fibre reinforced plastic (CFRP) composites under static tensile loading. Three laminates with three plies each were manufactured and tested under tensile static loading. Damage was being monitored using AE technique with instantaneous AE hits energies being used as the damage parameter. Results showed that angle ply laminates experienced crack initiations at about 50% of ultimate tensile strength whereas cross ply laminates and non-conventional angle ply laminates having one cross ply laminate experienced initiation of cracks at about a third of ultimate tensile strength. This early cracks initiation is believed to be caused by the presence of 90° plies that cannot take much load transversely.

关键词： CRFP Ply Angle Effect Static Tensile Test Acoustic Emission Crack Initiation