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耦合修正分析Al−Fe−Ni合金蠕变机理
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作者 卞泽宇 朱爱林 +6 位作者 肖亚开 李宇罡 马乃恒 卞汉兵 汪明亮 陈哲 王浩伟 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2023年第5期1331-1344,共14页
在引入阈值应力和载荷传递系数后,对Al−Fe−Ni合金的蠕变本构方程进行耦合修正,描述该合金在300和400℃下的位错蠕变。量化结果分析及显微组织表征表明,蠕变过程中位错与共晶相间复杂交互作用是阈值应力的起源。同时,共晶相与基体之间模... 在引入阈值应力和载荷传递系数后,对Al−Fe−Ni合金的蠕变本构方程进行耦合修正,描述该合金在300和400℃下的位错蠕变。量化结果分析及显微组织表征表明,蠕变过程中位错与共晶相间复杂交互作用是阈值应力的起源。同时,共晶相与基体之间模量的差异引起共晶相分担应力作用。此外,温度对基体及共晶相模量产生的影响差异导致高温时合金阈值应力降低,而应力转移系数增大。这些现象通过有限元模型分析得到进一步的论证。总体而言,共晶合金位错蠕变的控制机理得到了更深层次的量化认识。 展开更多
关键词 位错蠕变 铝合金 共晶相 应力转移效果 阈值应力
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改良预崩解炭质泥岩的力学行为及微观机理研究 被引量:8
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作者 曾铃 余慧聪 +1 位作者 高乾丰 卞汉兵 《Journal of Central South University》 SCIE EI CAS CSCD 2020年第7期1992-2002,共11页
预崩解炭质泥岩在中国西南地区常用作路堤填料。为改善预崩解炭质泥岩力学特性,采用粉煤灰、水泥和红黏土对预崩解炭质泥岩进行处理,通过三轴试验分析改良土的应力-应变关系和抗剪强度指标,并利用扫描电镜和X射线衍射表征其微观结构和... 预崩解炭质泥岩在中国西南地区常用作路堤填料。为改善预崩解炭质泥岩力学特性,采用粉煤灰、水泥和红黏土对预崩解炭质泥岩进行处理,通过三轴试验分析改良土的应力-应变关系和抗剪强度指标,并利用扫描电镜和X射线衍射表征其微观结构和矿物成分。结果表明,经水泥改良后预崩解炭质泥岩的应力-应变关系曲线由应变硬化型转变为应变软化型,但粉煤灰和红黏土不改变其应力-应变关系类型。三种添加剂对预崩解炭质泥岩黏聚力影响的大小顺序为:水泥>红黏土>粉煤灰。未加水泥的预崩解炭质泥岩均表现为鼓胀破坏,而经水泥改良的预崩解炭质泥岩均表现为剪切破坏或鼓胀-剪切破坏。由于胶结物能将土颗粒紧密胶结成团,使微观结构更加致密、稳定,因此,改良后预崩解炭质泥岩的力学特性得到显著增强。研究结果可为炭质泥岩在路基工程中的应用提供参考。 展开更多
关键词 路基工程 炭质泥岩 添加剂 力学特性 微观结构
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GIS, Forest Fire Prevention and Risk Matrix in the National Forest of Khoudida, Sidi Bel Abbes, Algeria 被引量:2
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作者 Mayssara El Bouhissi Salah Eddine Bachir Bouidjra +1 位作者 Khé loufi Benabdeli 《Open Journal of Ecology》 2020年第6期356-369,共14页
Forest fires in Algeria are ravaging an average of more than 32,000 hectares annually despite the prevention and control plan put in place. They are the most damaging factor of degradation of the forest and weigh heav... Forest fires in Algeria are ravaging an average of more than 32,000 hectares annually despite the prevention and control plan put in place. They are the most damaging factor of degradation of the forest and weigh heavily on the environment and the local economy. Conventional methods for fire prevention and control are time consuming and are not always reliable in view of the complexity and diversity of forest ecosystems. The main idea behind this study is to use the GIS and remote sensing for the development of a fire risk map of the Khoudida State Forest (Algeria). The approach adopted involves three parameters that control the fire behavior, which are: the top-morphology of the field, the combustibility of the plant cover and hazards. For each factor its correlation with risk was evaluated;the combination of the slope, altitude and exposure parameters in the topo-morphological index and the hazard map made it possible to evaluate the average risk for an area of more than 2132 hectares, 1521 hectares high and only 493 hectares, respectively 51.4%, 36.7% and 11.9%. 展开更多
关键词 FIRE GIS Remote Sensing VULNERABILITY Forest Hazard Khoudida Risk
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基于微观结构的压实二元粉质黏土渗透与持水特性 被引量:1
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作者 高乾丰 史振宁 +1 位作者 罗锦涛 刘杰 《Journal of Central South University》 SCIE EI CAS CSCD 2020年第7期2068-2081,共14页
粉质黏土路堤的耐久性在一定程度上受水分迁移控制,而后者取决于土的水力特性。本文研究了压实二元粉质黏土的水力特性。首先,按不同混合比和干密度制备了的二元粉质黏土试样,并利用扫描电镜和压汞仪分析了粉质黏土的微观结构。然后,通... 粉质黏土路堤的耐久性在一定程度上受水分迁移控制,而后者取决于土的水力特性。本文研究了压实二元粉质黏土的水力特性。首先,按不同混合比和干密度制备了的二元粉质黏土试样,并利用扫描电镜和压汞仪分析了粉质黏土的微观结构。然后,通过变水头渗透试验和持水性试验,研究了粉质黏土的渗透性和持水性。结果表明,当黏土含量为100%时,压实后黏土颗粒分散性良好,并呈现定向排列特征。随着黏土含量降低,黏土颗粒的定向排列逐渐受到粉粒存在的干扰,导致粉粒周围形成许多大孔隙。但粉粒周围孔隙的数量随着干密度的增加明显减小。并且,随着黏土含量和干密度的增加,粉质黏土的渗透性降低而持水性增强。黏土含量和干密度越大,粉质黏土中的孔隙越少,对水体流动的阻碍越强。粉质黏土的渗透与持水特性均可通过孔径分布特征参数进行预测。 展开更多
关键词 粉质黏土 微观结构 渗透性 持水性 扫描电镜
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Effect of the Number and Orientation of Fractures on the P-Wave Velocity Diminution: Application on the Building Stones of the Rabat Area (Morocco) 被引量:2
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作者 Hamid El Azhari Iz-Eddine El Amrani El Hassani 《Geomaterials》 2013年第3期71-81,共11页
This study is focused on two types of Moroccan rocks, among the most widely used as building stones: the calcarenite of Salé (CS) and the marble of oued Akrech (MA). The two rocks, lithologically different, show ... This study is focused on two types of Moroccan rocks, among the most widely used as building stones: the calcarenite of Salé (CS) and the marble of oued Akrech (MA). The two rocks, lithologically different, show a clear contrast of their P-wave velocities (Vp): 3.90 vs 5.10 km/s at dry state and 4.29 vs 5.64 km/s at saturation. The “Artificial fractures” created in the two rock types reveal that their Vp undergo diminutions which the rates vary depending of the number and the plane orientation of the fractures. In the CS, Vp shows an increasing of cumulative diminution (Dc) according to the number of fractures, but with a variable rate of unitary diminution (Du) from one fracture to the other. This defines a linear regression with a low coefficient of determination (Dc = 10.18NbFr + 10.96;r2 = 0.87). The mode of the Vp evolution would be related to the roughness of fractures surface, which itself depends upon the petrographic nature of the calcarenite (friable structure, high porosity and heterogenous composition). The MA manifested an increasing Dc with a fairly constant rate of Du from a fracture to another, giving a regression line with a high coefficient of determination (Dc = 12.17NbFr – 10.69;r2 = 0.99). This steady diminution of Vp would be related to the granoblastic texture and the monomineral composition of the marble, which engender smoother fracture surfaces. The rates of Vp diminution also depend on the orientation plane of the fractures relative to the direction of wave propagation. The fractures parallel (θ = 0°) amplify slightly the Vp, playing a significant role of “waveguide”. The fractures oriented at 45° lead to a diminution lower than those of fractures oriented at 25° and 90°. The same trend of diminution, but at variable rates, appears on the samples of the two types of stones at dry and saturated state. This can be explained by the compressive nature of P-waves, which obey the physic laws of the transmission of the constraints in the solid mediums. 展开更多
关键词 FRACTURE Diminution P-WAVE VELOCITY Calcarenite MARBLE Morocco
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Ediacarian Volcanic Rocks and Basic Dikes from the Lac Ifni Sector of the Central High Atlas Mountains:Petrographic Studies and Clinopyroxene Chemical Composition
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作者 Sad Belkacim M.Ikenne +3 位作者 S.Arai H.Gahlan A Ahmed Hassan Y.Ishida 《地学前缘》 EI CAS CSCD 北大核心 2009年第S1期198-198,共1页
The Ediacarian volcanic series from the Lac Ifni sector are composed of a large variety of rocks from basalts and rhyolites to intermediates facies such as andesites,rhyodacites and pyroclastites.All these rocks are i... The Ediacarian volcanic series from the Lac Ifni sector are composed of a large variety of rocks from basalts and rhyolites to intermediates facies such as andesites,rhyodacites and pyroclastites.All these rocks are intruded by dolerite dikes.Secondary processes are reflected by total serpentinization of olivine within basic andesite and by albitization 展开更多
关键词 High ATLAS MOUNTAINS Anti ATLAS MOUNTAINS VOLCANISM Ediacarian CLINOPYROXENE ICP-MS Laser orogenic calc-alcaline THOLEIITIC
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Tyrosinase Biosensor Used for the Determination of Catechin Derivatives in Tea: Correlation with HPLC/DAD Method
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作者 Saloua Nadifiyine Carole Calas-Blanchard +1 位作者 Aziz Amine Jean-Louis Marty 《Food and Nutrition Sciences》 2013年第1期108-118,共11页
Tea, one of the most popular consumed worldwide beverages, is known to be rich in polyphenols, more particularly in catechins. An amperometric biosensor based on tyrosinase was developed in order to monitor the phenol... Tea, one of the most popular consumed worldwide beverages, is known to be rich in polyphenols, more particularly in catechins. An amperometric biosensor based on tyrosinase was developed in order to monitor the phenolic content in black and green teas. The enzyme was immobilised by coreticulation with glutaraldehyde on carbon screen-printed electrodes (CSPE). Initially, the performances of the biosensor were evaluated referring to catechol as a model substrate. This analytical tool exhibits a high sensitivity (217 nA/μM), low limit of detection (LOD) = 0.03 μM, good intra-electrode and inter-electrode reproducibilities with RSD lower than 3% (n = 5 injections) and RSD = 8.14% (n = 12 sensors) respectively. The storage stability was also studied;the biosensor retained successively 85% and 70% of its initial response after 34 and 53 days. Subsequently, several catechin derivatives frequently found in teas were tested and classified relatively to their sensitivities. For tea samples, the results obtained with the biosensors were compared to high performance liquid chromatography (HPLC) analysis. A good correlation between the two methods was obtained. The calculated recovery was between 90% and 96%, proving that the proposed tyrosinase biosensor can be an alternative analytical tool for global determination of catechin derivatives in tea. 展开更多
关键词 TEA POLYPHENOL CATECHIN TYROSINASE AMPEROMETRIC BIOSENSOR HPLC
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Interactions between Superplasticizer and Release Agents at the Concrete/Formwork Interface
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作者 Samir Bouharoun Yannick Vanhove +2 位作者 Chafika Djelal Pascale De Caro Isabelle Dubois 《Materials Sciences and Applications》 2012年第6期384-389,共6页
Improving the knowledge of rheological and tribological characteristics of fresh concrete is important to contribute to the progress of construction sites and the final quality of the work. The objective of this study... Improving the knowledge of rheological and tribological characteristics of fresh concrete is important to contribute to the progress of construction sites and the final quality of the work. The objective of this study is to identify the effect of a superplasticizer based on polycarboxylic ether on the tribological behavior of fresh concrete at the concrete/formwork and concrete/oil/formwork interfaces. Friction tests on fresh concrete were carried out using a plan/plan tribometer. In order to study the behavior of the superplasticizer close to the formwork, three concretes with 30% of paste and different dosage of superplasticizer were formulated. The results show that the increase of the dosage of superplasticizer reduces the friction stress. The properties of the superplasticizer generate a deflocculating action of concrete grains and lead to a stabilisation of the soap-oil micellae present in the vicinity of the formwork. Thus, the efficiency of superplasticizer depends on the quantity of fines, on the quantity of soap formed and so, on the release agent formulation. 展开更多
关键词 TRIBOLOGY Concrete/Formwork INTERFACE Concrete/Oil/Formwork INTERFACE SUPERPLASTICIZER Release Agent PHYSICOCHEMICAL
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Impact of Global Warming on Intensity-Duration-Frequency (IDF) Relationship of Precipitation: A Case Study of Toronto, Canada
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作者 Erick Carlier Jamal El Khattabi 《Open Journal of Modern Hydrology》 2016年第1期1-7,共7页
Annual maximum rainfall intensity for several duration and return periods has been analyzed according to the Gumbel distribution. The Intensity-Duration-Frequency (IDF) curves before and after 1980 have been computed ... Annual maximum rainfall intensity for several duration and return periods has been analyzed according to the Gumbel distribution. The Intensity-Duration-Frequency (IDF) curves before and after 1980 have been computed and compared. For the city of Toronto, it is shown that the rainfall intensities after 1980 are lower than those from before this date. This is especially clear for those of short duration. Comparing our results with those of other authors, it appears that, for the moment, no general law on the impact of global warming on the curves intensity duration frequency cannot be made. It appears that the impact of global warming on rainfall varies with geographic location and that it is not possible to draw some general conclusions across the planet. 展开更多
关键词 Climate Change Duration FREQUENCY Intensity RAINFALL
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Thermal Analysis of Concrete Mixtures with Recycled EPS Aggregates
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作者 Aisha Ayoubi Emilio Sassine +3 位作者 Joseph Dgheim Joelle Al Fakhoury Yassine Cherif Emmanuel Antczak 《Journal of Building Material Science》 2022年第2期36-45,共10页
Reusing recycled waste materials in buildings is gaining more and more attention for what it offers economic,environmental,and energy benefits;and many researchers are nowadays working on producing new sustainable con... Reusing recycled waste materials in buildings is gaining more and more attention for what it offers economic,environmental,and energy benefits;and many researchers are nowadays working on producing new sustainable construction materials incorporating recycled wastes.In this scope,this work uses an experimental approach aiming at understanding the effect of incorporating Expanded Polystyrene(EPS)beads in concrete and proposing thermally improved concrete mixtures for the production of hollow blocks in Lebanese constructions by substituting fine aggregates with recycled products such as EPS in order to promote their insulating properties.Three different diameters of EPS beads(2 mm~3 mm,3 mm~4 mm and 4 mm~5 mm)are studied with different volumetric ratios(20%,40%,60%and 80%)in order to investigate the effect of EPS on the thermal properties of concrete.The results showed that the only the percentage of incorporated EPS beads impacted the thermal performance of the concrete mixtures while the EPS diameters have a negligible effect on the thermal properties of the concrete samples. 展开更多
关键词 Concrete mixtures Hollow blocks EPS beads Thermal properties Thermal insulation Recycled wastes
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Effect of initial gravimetric water content and cyclic wetting-drying on soil-water characteristic curves of disintegrated carbonaceous mudstone 被引量:2
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作者 Ling Zeng Fan Li +2 位作者 Jie Liu Qianfeng Gao Hanbing Bian 《Transportation Safety and Environment》 EI 2019年第3期230-240,共11页
The soil-water characteristic curve(SWCC)is often used to estimate unsaturated soil properties(e.g.strength,permeability,volume change,solute and thermal diffusivity).The SWCC of soil samples is significantly affected... The soil-water characteristic curve(SWCC)is often used to estimate unsaturated soil properties(e.g.strength,permeability,volume change,solute and thermal diffusivity).The SWCC of soil samples is significantly affected by cyclic wetting-drying.To examine how water content and cyclic wetting-drying affect the SWCC of disintegrated carbonaceous mudstone(DCM),SWCC tests were implemented using a pressure-plate apparatus.In addition,SWCC models for DCM considering the initial gravimetric water content and cyclic wetting-drying were developed.The test results showed that the volumetric water content(θ)of the DCM first decreased rapidly and then became stable as matric suction(s)increased.The initial water content affected the SWCC by altering the pore structure of the DCM.For a given number of wetting-drying cycles,the higher the initial water content,the higher the stabilizedθ.At a given s value,θdecreased as the number of wetting-drying cycles increased,which suggests that cyclic wetting-drying reduces the water-holding capacity of DCM.The Gardner model for DCM was constructed considering initial water content and cyclic wetting-drying,and was effective at describing and predicting the SWCC model for DCM. 展开更多
关键词 embankment engineering disintegrated carbonaceous mudstone soil-water characteristic curve initial gravimetric water content cyclic wetting-drying
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Investigation of the fluid flow in an isolated rotor-stator system with a peripheral opening
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作者 DEBUCHY Roger ABDEL NOUR Fadi +1 位作者 NAJI Hassane BOIS Gérard 《Science China(Physics,Mechanics & Astronomy)》 SCIE EI CAS 2013年第4期745-754,共10页
This paper deals with an experimental, theoretical and numerical study of a turbulent flow with separated boundary layers between a rotor and a stator. The system is not subjected to any superimposed radial flow. The ... This paper deals with an experimental, theoretical and numerical study of a turbulent flow with separated boundary layers between a rotor and a stator. The system is not subjected to any superimposed radial flow. The periphery of the cavity is opened to the atmosphere so that the solid body rotation for infinite discs is not always observed. Emphasis was placed on develop- ment of an asymptotic approach and a step-by-step method to compute the radial distribution of the core swirl ratio and the static pressure on the stator side. The theory also includes the radial and axial velocities in the core region. The numerical simulation has been conducted with the commercial CFD code Fluent 6.1. The k- SST turbulence model is used, with the assumption of 2D-axisymmetric and steady flow. CFD validations have been performed by comparison of the numerical results with the corresponding theoretical results. Numerical and experimental results are in good agreement with analytical solutions. 展开更多
关键词 定子系统 流体流动 转子 数值模拟 孤立 计算结果 湍流实验 径向分布
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