检索结果-南通市图书馆

Open Journal of Ecology 2018年第8期8卷 432-446页

作者： Mohamed Sarmoum Rafael Ma Navarro-Cerrillo Frédéric Guibal fatiha abdoun Laboratory of Plant Physiology and Soil Culture Faculty of Nature and Life Sciences Ibn Khaldoun University Tiaret Algeria Department of Forestry Engineering University of Cordoba Cordoba Spain Mediterranean Institute of Biodiversity and Marine and Continental Ecology (IMBE) Aix-Marseille University (AMU) Aix-en-Provence France Laboratory of Plant Ecology and Environment Faculty of Biological Sciences University of Science and Technology Houari Boumediene (USTHB) Alger Algeria

In North Africa, Cedrus atlantica forests are in decline, following decades of anthropogenic pressure and repeated drought events. Mixed C. atlantica-Quercus ilex stands located in the Theniet El Had National Park (northwestern Algeria) were considered in the present study. Based on a stratified sampling, six temporary plots were established to describe structure (species composition, density, total height, diameter and basal area) and radial growth in relation to type of stand (pure and mixed), using a dendroecological approach. The diameter distribution of C. atlantica indicated the presence of few young individuals and a poor regeneration status in all the stands. The density and basal area of C. atlantica were significantly higher in pure stands, which necessitate silvicultural operations. In contrast, Q. ilex showed a progressive dynamic, at moderate altitude. Radial growth showed a significant decline from 1980 to the 2000s. The absence of an appropriate management plan and the increase in anthropogenic effects, without ruling out a role for the current climate conditions marked by drought, seem to be the causes of C. atlantica decline.

关键词： Atlas Cedar Algeria Structure Regeneration Radial Growth Forest Management

Development and characterization of a regional lunar soil simulant for emirates lunar missions

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

International Journal of Mining Science and Technology 2024年第9期34卷 1305-1315页

作者： Bo Peng Prabu Thannasi Waleed El-Sekelly Tarek abdoun Kemal Celik Division of Engineering New York University Abu DhabiAbu Dhabi PO Box 129188United Arab Emirates Structural Engineering Department Faculty of EngineeringMansoura UniversityMansoura 35516Egypt

Lunar soil simulants(LSS)have been pivotal in the success of past and current lunar *** have enhanced the design of lander and rover wheels through interaction studies on the lunar testbed under simulated environmental *** have also been used to evaluate the geotechnical,geomechanical,and dynamic characteristics of the lunar soil(LS),which is vital for future lunar *** most simulants have focused on either the chemical and mineralogical or geotechnical properties,developing a comprehensive LSS that mimics the lunar soil is of paramount importance for lander and rover soft-landing and future lunar *** article presents the significant development and characterization of the new LSS NYUAD-1,the first regional soil simulant tailored for the planned Emirates lunar *** material and geotechnical properties of NYUAD-1,including chemical composition,mineralogy,particle size,morphology,specific gravity,density,shear strength,and compressibility behaviors,were assessed through laboratory tests conducted per ASTM *** analysis with authentic lunar regolith and various regolith simulants confirms the significance and applicability of NYUAD-1 for lunar-based research,offering a promising step toward future lunar habitation.

关键词： LSS Chemical composition Mineralogy Density Shear strength Compressibility

Smart prediction of liquefaction-induced lateral spreading

在线全文

学校读者我要写书评

暂无评论

Journal of Rock Mechanics and Geotechnical Engineering 2024年第6期16卷 2310-2325页

作者： Muhammad Nouman Amjad Raja Tarek abdoun Waleed El-Sekelly New York University(NYU)Abu Dhabi Abu Dhabi129188United Arab Emirates University of Management and Technology Lahore54372Pakistan Department of Civil and Environmental Eng. Rensselaer Polytechnic Institute(RPI)1108th StreetJEC 4049TroyNY12180USA Department of Structural Engineering Mansoura UniversityMansoura35516Egypt

The prediction of liquefaction-induced lateral spreading/displacement(Dh)is a challenging task for civil/geotechnical *** this study,a new approach is proposed to predict Dh using gene expression programming(GEP).Based on statistical reasoning,individual models were developed for two topographies:free-face and gently sloping *** with a comparison with conventional approaches for predicting the Dh,four additional regression-based soft computing models,*** process regression(GPR),relevance vector machine(RVM),sequential minimal optimization regression(SMOR),and M5-tree,were developed and compared with the GEP *** results indicate that the GEP models predict Dh with less bias,as evidenced by the root mean square error(RMSE)and mean absolute error(MAE)for training(i.e.1.092 and 0.815;and 0.643 and 0.526)and for testing(i.e.0.89 and 0.705;and 0.773 and 0.573)in free-face and gently sloping ground topographies,*** overall performance for the free-face topology was ranked as follows:GEP>RVM>M5-tree>GPR>SMOR,with a total score of 40,32,24,15,and 10,*** the gently sloping condition,the performance was ranked as follows:GEP>RVM>GPR>M5-tree>SMOR with a total score of 40,32,21,19,and 8,***,the results of the sensitivity analysis showed that for both free-face and gently sloping ground,the liquefiable layer thickness(T_(15))was the major parameter with percentage deterioration(%D)value of 99.15 and 90.72,respectively.

关键词： Lateral spreading Intelligent modeling Gene expression programming(GEP) Closed-form solution Feature importance

Centrifuge modeling of PGD response of buried pipe

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Earthquake Engineering and Engineering Vibration 2005年第1期4卷 69-73页

作者： Michael O'Rourke Vikram Gadicherla Tarek abdoun Department of Civil and Environmental Engineering Rensselaer Polytechnic Institute Troy New York USAProfessorHance Engineering Solutions Hyderabad IndiaEngineerDepartment of Civil and Environmental Engineering Rensselaer Polytechnic Institute Troy New York USA Assistant Professor

A new centrifuge based method for determining the response of continuous buried pipe to PGD is presented. The physical characteristics of the RPI's 100 g-ton geotechnical centrifuge and the current lifeline experiment split-box are described: The split-box contains the model pipeline and surrounding soil and is manufactured such that half can be offset, in flight, simulating PGD. In addition, governing similitude relations which allow one to determine the physical characteristics, (diameter, wall thickness and material modulus of elasticity) of the model pipeline are presented. Finally, recorded strains induced in two buried pipes with prototype diameters of 0.63 m and 0.95 m (24 and 36 inch) subject to 0.6 and 2.0 meters (2 and 6 feet) of full scale fault offsets and presented and compared to corresponding FE results.

关键词： earthquakes buried pipe permanent ground deformation centrifuge models fault crossings lifeline earthquake engineering

Physical modeling and visualization of soil liquefaction under high confining stress

在线全文

学校读者我要写书评

暂无评论

Earthquake Engineering and Engineering Vibration 2005年第1期4卷 47-57页

作者： Lenart González Tarek abdoun Mourad Zeghal Vivian Kallou Michael K.Sharp Dept.of Civil and Environmental Engineering Rensselaer Polytechnic Inst.(RPI)TroyNYUSA Mueser Rutledge Consulting Engineers 225 W 34th StreetNew YorkNYUSA US Army Engineer Research and Development Center VicksburgMSUSA

The mechanisms of seismically-induced liquefaction of granular soils underhigh confining stresses are still not fully *** of these mechanisms is generallybased on extrapolation of observed behavior at shallow *** centrifuge model tests wereconducted at RPI's experimental facility to investigate the effects of confining stresses on thedynamic response of a deep horizontal deposit of saturated *** was observed at highconfining stresses in each of the tests.A system identification procedure was used to estimate theassociated shear strain and stress time *** histories revealed a response marked byshear strength degradation and dilative *** recorded accelerations and pore pressures wereemployed to generate visual animations of the *** visualizations revealed a liquefactionfront traveling downward and leading to large shear strains and isolation of upper soil layers.

关键词： centrifuge modeling high confining stress liquefaction system identification visualization

Identification and imaging of soil and soil-pile deformation in the presence of liquefaction

在线全文

学校读者我要写书评

暂无评论

Earthquake Engineering and Engineering Vibration 2006年第2期5卷 171-182页

作者： M. Zeghal P. V. Kallou C. Oskay T. abdoun M. K. Sharp Dept. of Civ.and Env. Engrg. Rensselar Polytechnic Institute Troy NY l2l80 USA Mueser Rutledge Consulting Engineers 225 W 34th Street New York NY 10122 USA Engineer Dept. of Civ. and Env. Engrg. Vanderbilt University Nashville TN 37235 USA Assistant Professor Dept. of Civ.and Env. Engrg. Rensselar Polytechnic Institute Troy NY l2l80 USA Associate Professor Centrifuge Research & Development Center Vicksburg MS 39180 USA Director

A simple identification technique is developed to visualize the dynamic deformation mechanisms of centrifuge models of saturated soil and soil-pile systems using the measurements provided by sparsely distributed sensors. Crosscorrelation analyses are employed first to assess the variation of shear wave velocity profile with time as soil experiences stiffness reduction and degradation during dynamic excitations. The corresponding time-dependent modal configurations are determined using the finite-element technique. These configurations are used along with recorded motions to evaluate optimal time histories of displacement and strain fields based on a spectral motion reconstruction. Visualizations of the response of infinite slope and soil-pile centrifuge models revealed salient and complex multi-dimensional deformation patterns, especially at high pore pressure ratios. The developed technique provides an effective tool to visualize and analyze the dynamic response of centrifuge, shake-table and field soil systems.

关键词： soil dynamics liquefaction visualization centrifuge model

Data Recovering Problem Using a New KMF Algorithm for Annular Domain

在线全文

学校读者我要写书评

暂无评论

American Journal of Computational Mathematics 2012年第2期2卷 88-94页

作者： Chakir Tajani Jaafar Abouchabaka Otman abdoun LaRIT Faculty of SciencesIbn Tofail UniversityKenitraMorroco

This paper is interested at the Cauchy problem for Laplace’s equation, which is to recover both Dirichlet and Neumann conditions on the inaccessible part of the boundary (inner part) of an annular domain from the over specified conditions on the accessible one (outer part). This work is an extension of the proposed algorithm for a unit circle [1] to annular domain, where, we describe an alternating formulation of the KMF algorithm proposed by Kozlov, Mazya and Fomin, and its relationship with the standard formulation. The new KMF algorithm ameliorates the accuracy of the solution and reduces the number of iterations required to achieve convergence. In the last part, the discussion of the error estimation of solution is presented and some numerical tests, using the software Freefem are given to show the efficiency of the proposed method.

关键词： Inverse Problem Annular Domain Laplace Equation Iterative Method Freefem

Assessing the bioactivity,cytotoxicity,and rheological properties of pectin recovered from citrus peels

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Food Bioscience 2022年第2期46卷 366-374页

作者： Marie Carene Nancy Picot-Allain Atefeh Amiri-Rigi Khalida abdoun-Ouallouche Lila Aberkane Assia Djefal-Kerrar Mohamad Fawzi Mahomoodally Mohammad Naushad Emmambux Department of Consumer and Food Sciences University of PretoriaPrivate Bag X20HatfieldPretoria0028South Africa Future Africa University of PretoriaSouth Africa Medical Applications Department Nuclear Research Center of AlgiersAlgeria Department of Health Sciences Faculty of ScienceUniversity of Mauritius230R´eduitMauritius

The recovery of pectin from citrus peel waste for application in the food,nutraceutical,pharmaceutical,and medical industries has attracted much *** has been postulated that the presence of polyphenols,sometimes regarded as an impurity,in extracted pectin might confer enhanced biological *** research study aimed at investigating the physicochemical and biological properties(antioxidant,enzyme inhibitory,and cytotoxic properties)of pectin extracted from the alcohol insoluble residues of the peel waste of grapefruit,lime,and lemon as well as the pectin recovered from untreated peel *** rheological behavior of the pectin samples was also *** methoxyl pectin with galacturonic acid content greater that 60%was recovered from the different raw *** obtained from untreated material possessed high phenolic content(19.83-5.94 mg gallic acid equivalent/g sample)and showed higher antioxidant *** against pancreatic cholesterol esterase,pancreatic lipase,andα-glucosidase was observed and pectin enriched with polyphenol showed higher *** of pectin samples to healthy Vero cells enhanced proliferation and did not show cytotoxic *** solutions extracted from untreated lime and untreated grapefruit presented highest viscosity and elastic modulus,which were comparable to those obtained for commercial high-methoxyl *** extracted from lime,lemon,and grapefruit peels possessed interesting biological and viscoelastic properties,which can be exploited for development of novel bioproducts.

关键词： Citrus peel waste Pectin Bioactivity Polyphenols Viscosity

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

磁场第六感

新发现 2012年第8期 68-77页

作者： Elsa abdoun

长久以来，科学家都忽视了生物能够感知磁场的可能性。可是通过大量的观察和各种令人瞠目结舌的实验，最近50年来。人们倾向于认为对于磁场感知能力真实存在，而且存在于数量繁多的生命形式中!

关键词：磁场感知能力真实存在生命形式可能性生物能科学家

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

虚拟世界：莫雷阿岛2．0

新发现 2017年第6期 66-69页

作者： Elsa abdoun 王师

郁郁葱葱的棕榈树、白色的沙滩、“鱼”头攒动的巨大珊瑚礁……何其令人向往的多彩生活。毗邻塔希提的莫雷阿岛，无疑是旅游者心目中的天堂。但你能想象这个岛会成为一项重大科研项目的主角吗？城市、人口、气候、动植物群落乃至周边洋... 详细信息

郁郁葱葱的棕榈树、白色的沙滩、“鱼”头攒动的巨大珊瑚礁……何其令人向往的多彩生活。毗邻塔希提的莫雷阿岛，无疑是旅游者心目中的天堂。但你能想象这个岛会成为一项重大科研项目的主角吗？城市、人口、气候、动植物群落乃至周边洋流的发展，凡是与该岛有关，哪怕再微不足道的细节也会得到研究，以便让整个岛屿在计算机上重生，从而模拟出来来的演变。

关键词：虚拟世界科研项目植物群落棕榈树珊瑚礁旅游者计算机