Effet de la température sur le comportement des sols non saturés sur les chemins de drainage et d’humidification

2007 ◽  
Vol 44 (9) ◽  
pp. 1064-1081 ◽  
Author(s):  
Moulay-Smaïne Ghembaza ◽  
Said Taïbi ◽  
Jean-Marie Fleureau
Keyword(s):  
Unsaturated Soils ◽  
Room Temperature ◽  
Experimental Site ◽  
Initial State ◽  
Thermal Changes ◽  
Temperature Ranges ◽  
Deep Underground ◽  
Hydromechanical Behaviour ◽  
Clay Barriers ◽  
Sols Non Saturés

The behaviour of soils subject to suction on drying and wetting paths depends on the type of material and its initial state. Exposure to heat modifies the state of pore water and therefore the hydromechanical behaviour of the soil. A new experimental device has been developed to study the thermohydric behaviour of unsaturated soils. Salt solution desiccators and polyethylene glycol (PEG) osmotic solutions are dipped in thermostatic baths, whose temperature ranges from room temperature to 80 °C. Tests were carried out on a sandy clay prepared in the laboratory and on a natural undisturbed clay, extracted from an experimental site for deep underground storage of radioactive waste. Results show that temperature plays an important role in the shrinkage of soil, especially when subjected to high levels of suction. The results can be applied to observe the response of confining clay barriers submitted to hydric and thermal changes.

scholarly journals Caloric materials for cooling and heating

Science ◽  
2020 ◽  
Vol 370 (6518) ◽  
pp. 797-803 ◽  
Author(s):  
X. Moya ◽  
N. D. Mathur
Keyword(s):  
Climate Change ◽  
Room Temperature ◽  
Heat Pumps ◽  
Recent Advances ◽  
Thermal Changes ◽  
Magnetocaloric Materials ◽  
Single Field ◽  
Combat Climate Change ◽  
Present Activity

Magnetically driven thermal changes in magnetocaloric materials have, for several decades, been exploited to pump heat near room temperature. By contrast, their electrocaloric and mechanocaloric counterparts have only been intensively studied and exploited for little more than a decade. These different caloric strands have recently been unified to yield a single field of research that could help combat climate change by generating better heat pumps for both cooling and heating. Here we outline the timeliness of the present activity and discuss recent advances in caloric measurements, materials, and prototypes.

scholarly journals Experimental Investigation of Mechanical Properties of PVC Polymer under Different Heating and Cooling Conditions

2016 ◽  
Vol 2016 ◽  
pp. 1-5 ◽  
Author(s):  
Sarkawt Rostam ◽  
Alan Kareem Ali ◽  
Firdaws Haidar AbdalMuhammad
Keyword(s):  
Mechanical Properties ◽  
Experimental Investigation ◽  
Room Temperature ◽  
Heating Temperature ◽  
Industrial Applications ◽  
Standard Samples ◽  
Heating And Cooling ◽  
Working Environments ◽  
Cooling Conditions ◽  
Temperature Ranges

Due to a widely increasing usage of polymers in various industrial applications, there should be a continuous need in doing research investigations for better understanding of their properties. These applications require the usage of the polymer in different working environments subjecting the material to various temperature ranges. In this paper, an experimental investigation of mechanical properties of polyvinyl chloride (PVC) polymer under heating and cooling conditions is presented. For this purpose standard samples are prepared and tested in laboratory using universal material testing apparatus. The samples are tested under different conditions including the room temperature environment, cooling in a refrigerator, and heating at different heating temperatures. It is observed that the strength of the tested samples decreases with the increasing of heating temperature and accordingly the material becomes softer. Meanwhile the cooling environments give a clear increasing to the strength of the material.

Behavior of clayey soils on drying–wetting paths

1993 ◽  
Vol 30 (2) ◽  
pp. 287-296 ◽  
Author(s):  
Jean-Marie Fleureau ◽  
Siba Kheirbek-Saoud ◽  
Ria Soemitro ◽  
Said Taibi
Keyword(s):  
Experimental Research ◽  
Negative Pressure ◽  
Unsaturated Soils ◽  
Liquid Limit ◽  
The Other ◽  
Clayey Soils ◽  
Initial State ◽  
Stress Increase ◽  
Negative Pressures ◽  
Clayey Materials

Experimental research was carried out on 11 different clayey materials to determine the main characteristics of the drying and wetting paths and the influence of initial state and other factors. Normally consolidated paths are shown to have a large saturated domain, in which a negative pressure is equivalent to an isotropic stress increase; such paths can be derived from correlations with the liquid limit. On the other hand, the behavior of overconsolidated or dried samples is largely dependent on the range of stresses and negative pressures. Key words : suction, unsaturated soils, drying, wetting, correlations, models.

scholarly journals Surface Nuclear Magnetic Resonance Monitoring Reveals Karst Unsaturated Zone Recharge Dynamics during a Rain Event

Water ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 3183
Author(s):  
Naomi Mazzilli ◽  
Konstantinos Chalikakis ◽  
Simon D. Carrière ◽  
Anatoly Legchenko
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Unsaturated Zone ◽  
Low Noise ◽  
Water Dynamics ◽  
Rain Event ◽  
Experimental Site ◽  
Initial State ◽  
Before And After ◽  
Nuclear Magnetic

Understanding karst unsaturated zone (UZ) recharge dynamics is crucial for achieving sustainable management of karst hydrosystems. In this paper, we provide the first report of the application of surface nuclear magnetic resonance (SNMR) monitoring of a karst UZ during a typical Mediterranean rain event. This 79 days’ SNMR monitoring is a part of a more than 2 years of SNMR monitoring at the Low Noise Underground Laboratory (LSBB) experimental site located within the Fontaine de Vaucluse karst hydrosystem (southeastern France). We present eight SNMR soundings conducted before and after the rain event that accumulated 168 mm in 5 days. The obtained results demonstrate the applicability and the efficiency of SNMR for investigating infiltration dynamics in karst UZs at the time scale of a few days. We present the SNMR amplitudes that highlight strong signal variations related to water dynamics in the karst UZ. Infiltrated water cause increased SNMR signal during 5 days after the rain event. A significant draining process of the medium starts 15 days after the main event. Finally, after 42 days, the SNMR signal returns close to the initial state.

Temperature dependence of the AV3O7 (A = Ca, Sr) structure

2007 ◽  
Vol 63 (6) ◽  
pp. 836-842 ◽  
Author(s):  
Sebastian Prinz ◽  
Karine M. Sparta ◽  
Georg Roth
Keyword(s):  
Single Crystal ◽  
Temperature Dependence ◽  
Crystal Structures ◽  
Room Temperature ◽  
X Ray Diffraction ◽  
X Ray ◽  
Space Groups ◽  
Temperature Ranges ◽  
First Time

The V4+ (spin ½) oxovanadates AV3O7 (A = Ca, Sr) were synthesized and studied by means of single-crystal X-ray diffraction. The room-temperature structures of both compounds are orthorhombic and their respective space groups are Pnma and Pmmn. The previously assumed structure of SrV3O7 has been revised and the temperature dependence of both crystal structures in the temperature ranges 297–100 K and 315–100 K, respectively, is discussed for the first time.

High-Temperature Absorption of the 3.39 μm He-Ne Laser Line by Acetylene, Ethylene, and Propylene

1980 ◽  
Vol 34 (1) ◽  
pp. 81-84 ◽  
Author(s):  
T. Koike ◽  
W. C. Gardiner
Keyword(s):  
Room Temperature ◽  
Spectroscopic Analysis ◽  
Laser Line ◽  
Absorption Process ◽  
Line Broadening ◽  
Chemical Behavior ◽  
Time Resolved ◽  
Temperature Ranges ◽  
Increasing Temperature ◽  
Line Positions

Absorptivity measurements for the 3.39 μm He-Ne laser line are reported for acetylene, ethylene, and propylene over the temperature ranges 1500 to 3000 K (acetylene), 1000 to 2000 K (ethylene), and 700 to 2300 K (propylene). In contrast to the behavior of other hydrocarbons, the absorptivities of acetylene and ethylene increase with increasing temperature. The conventional spectroscopic analysis of line positions based upon high-resolution infrared spectroscopy at room temperature and approximate line-broadening theory indicate that no absorption at all would be expected for acetylene or ethylene. The time-resolved absorption profiles and computer models of the chemical behavior expected for shock-heated test gas confirm that the absorption is really due to these molecules, but must be attributed to some heretofore unidentified absorption process.

Vibration Analysis of Linear Magnetostrictive Actuator

2011 ◽  
Vol 243-249 ◽  
pp. 6036-6039 ◽  
Author(s):  
Li Ping Qin ◽  
Yuan Jun Yan
Keyword(s):  
Vibration Analysis ◽  
Room Temperature ◽  
Large Strain ◽  
High Energy ◽  
High Energy Density ◽  
Initial State ◽  
Giant Magnetostrictive Materials ◽  
Magnetostrictive Actuator ◽  
Hysteretic Loss ◽  
Great Development

Giant magnetostrictive materials, such as Terfenol-D, have been used to make a principal driving element in actuator, owing to its fine characteristic that is large strain, high energy density, small hysteretic loss and less performance degradation in room temperature. With the discovery and refining of Terfenol-D, the magnetostrictive actuator has gotten great development for recent twenty years. The free vibration and forced vibratin of linear magnetostrictive actuator is analyzed. The initial state of rod is at rest. The computational results show that the displacement response is synchronous with the current.

Experimental and numerical studies of the hydromechanical behaviour of a natural unsaturated swelling soil

2009 ◽  
Vol 46 (4) ◽  
pp. 393-410 ◽  
Author(s):  
H. Nowamooz ◽  
M. Mrad ◽  
A. Abdallah ◽  
F. Masrouri
Keyword(s):  
Unsaturated Soils ◽  
Mercury Porosimetry ◽  
Experimental Studies ◽  
Shallow Foundation ◽  
Water Retention Curve ◽  
Elastic Behaviour ◽  
Wetting And Drying ◽  
Numerical Studies ◽  
Swelling Soil ◽  
Hydromechanical Behaviour

This paper presents experimental studies performed on a natural swelling soil. Initially, the soil fabric was studied by a mercury porosimetry test, revealing a clear bimodal pore distribution that corresponds to micro- and macrostructural levels. The water-retention curve of the soil was then determined using two suction-imposition techniques: the osmotic and the vapour equilibrium methods. During the main testing program, three successive wetting and drying cycles were applied in a suction range between 0 and 2 MPa under different values of constant vertical net stress using osmotic oedometers. The test samples showed cumulative swelling strains during the cycles. The volumetric strains reached an equilibrium stage, indicating an elastic behaviour of the samples at the end of the suction cycles. Based on these results, the parameters of an elastoplastic model for swelling unsaturated soils (BExM) were derived. This model, implemented in a finite element code (Code_Bright), was applied to a practical problem of a shallow foundation based on a swelling soil. This application studies the effects of hydraulic solicitations on settlements of this foundation. The results show the capacity of the model to solve complex hydromechanically coupled problems.

Solvolysis of sulphonyl halides. VIII. Reaction of methane and ethane sulphony1 chlorides with methanol, ethanol, and mixed solvent systems

1971 ◽  
Vol 24 (4) ◽  
pp. 713 ◽  
Author(s):  
R Foon ◽  
AN Hambly
Keyword(s):  
Carbon Tetrachloride ◽  
Room Temperature ◽  
Reaction Rate ◽  
Mixed Solvent ◽  
Aprotic Solvent ◽  
Excess Enthalpies ◽  
Initial State ◽  
Polar Aprotic Solvent ◽  
Rate Of Reaction ◽  
Solvent Systems

At room temperature methanesulphonyl chloride reacts more rapidly than ethanesulphonyl chloride in solvolysis by ethanol. Their rates of reaction with methanol are approximately equal while ethanesulphonyl chloride is the more reactive in hydrolysis. The enthalpies and entropies of activation have been determined for the solvolysis of ethanesulphonyl chloride in mixtures of ethanol with benzene, carbon tetrachloride, or 2,2,4-trimethylpentane. A comparison of the excess enthalpies and entropies of mixing in the formation of these solvents with the corresponding parameters for reaction shows that the effects on reaction rate are not due merely to the modification of the initial state of the system. The effect of the polar aprotic solvent nitrobenzene on the rate of reaction with methanol is attributed to an increase in the nucleophilic tendency of the methanol rather than to solvation of the reactive centre in the transition state.

scholarly journals The kinetics of mutarotation in solution

1940 ◽  
Vol 176 (966) ◽  
pp. 352-367 ◽  
Keyword(s):  
Aqueous Solution ◽  
Room Temperature ◽  
Reducing Sugars ◽  
Arrhenius Equation ◽  
Energy Of Activation ◽  
A Value ◽  
Temperature Ranges ◽  
Velocity Coefficient ◽  
Kinetics Of ◽  
True Energy

The kinetics of the mutarotation of representative reducing sugars from the pentose, hexose and disaccharide series have been investigated polarimetrically over wide temperature ranges in aqueous solution. The dependence of the velocity coefficient, k , upon temperature is fairly well reproduced by an equation of the form ln k = C + ( J/R ) ln T - E/RT . The true energy of activation, E , is found to be some 6000 calories greater than the apparent value afforded by the Arrhenius equation at room temperature. J/R has a value of — 10, which is identified as the number of oscillators contributing to the activation. The constants C, J and E of this equation are discussed, with reference to many reactions, in terms of a theory of unimolecular reactions in solution.

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