On numerical modeling of couple heat, air and moisture transfer through multilayered walls

This paper reports on numerical modeling of heat, air, and moisture transfer through multilayered walls. Building materials are often subjected to temporal climatic variations, which can induce a transfer of heat and moisture through the walls of the building and the foundation soil. These materials are generally considered as porous media. The coupled heat, air and moisture transfer in building materials is of paramount importance in the construction area. In this way, a mathematical model has been elaborated and validated using a benchmark example. Here, we aim to determine the energy losses. The capillary pressure is considered as potential moisture which represents both the transport of vapor and liquid phases of the water. Basing on basic functions of partial differential equations, one can convert certain measurable properties of porous media as coefficients depending on the temperature and the capillary pressure. The results obtained compare favorably with other available in the literature

Arginine/Nanocellulose membranes for carbon capture applications

The present study investigates the influence of the addition of L-arginine to a matrix of carboxymethylated nanofibrillated cellulose (CMC-NFC), with the aim of fabricating a mobile carrier facilitated transport membrane for the separation of CO2. Self-standing films were prepared by casting an aqueous suspension containing different amounts of amino acid (15\u201330\u201345 wt.%) and CMC-NFC. The permeation properties were assessed in humid conditions (70\u201398% relative humidity (RH)) at 35 \ub0C for CO2 and N2 separately and compared with that of the non-loaded nanocellulose films. Both permeability and ideal selectivity appeared to be improved by the addition of L-arginine, especially when high amino-acid loadings were considered. A seven-fold increment in carbon dioxide permeability was observed between pure CMC-NFC and the 45 wt.% blend (from 29 to 220 Barrer at 94% RH), also paired to a significant increase of ideal selectivity (from 56 to 185). Interestingly, while improving the separation performance, water sorption was not substantially affected by the addition of amino acid, thus confirming that the increased permeability was not related simply to membrane swelling. Overall, the addition of aminated mobile carriers appeared to provide enhanced performances, advancing the state of the art for nanocellulose-based gas separation membranes

From Architectured Materials to Large-Scale Additive Manufacturing

The classical material-by-design approach has been extensively perfected by materials scientists, while engineers have been optimising structures geometrically for centuries. The purpose of architectured materials is to build bridges across themicroscale ofmaterials and themacroscale of engineering structures, to put some geometry in the microstructure. This is a paradigm shift. Materials cannot be considered monolithic anymore. Any set of materials functions, even antagonistic ones, can be envisaged in the future. In this paper, we intend to demonstrate the pertinence of computation for developing architectured materials, and the not-so-incidental outcome which led us to developing large-scale additive manufacturing for architectural applications

CRITICAL UNDRAINED SHEAR STRENGTH OF LOOSE-MEDIUM SAND-SILT MIXTURES UNDER MONOTONIC LOADINGS

Empirical relationships are developed for estimating the undrained critical shear strength based on experimental triaxial tests under monotonic loadings. The effect of fines content on the undrained shear strength is analyzed for different combinations of density states. The parametric study indicates that in terms of the soil void ratio and fines content properties, the undrained critical shear strength may increase, or decrease as the amount of fines content increases, consequently showing vulnerability to liquefaction influenced by the fines content percentage. A series of monotonic undrained triaxial tests have been undertaken on a reconstituted saturated sand-silt mixtures specimen. Beyond 30% of fines content, it is shown that a fraction of silt participates in the soil skeleton chain force. In this context, the concept of the equivalent intergranular void ratio may be an appropriate parameter to express the critical shear strength of the soil under investigation. This parameter is able to control the undrained shear strength of non plastic silt and sand mixtures for different density states

Critical undrained shear strength of loose-medium sand-silt mixtures under monotonic loadings

Empirical relationships are developed for estimating the undrained critical shear strength based on experimental triaxial tests under monotonic loadings. The effect of fines content on the undrained shear strength is analyzed for different combinations of density states. The parametric study indicates that in terms of the soil void ratio and fines content properties, the undrained critical shear strength may increase, or decrease as the amount of fines content increases, consequently showing vulnerability to liquefaction influenced by the fines content percentage. A series of monotonic undrained triaxial tests have been undertaken on a reconstituted saturated sand-silt mixtures specimen. Beyond 30% of fines content, it is shown that a fraction of silt participates in the soil skeleton chain force. In this context, the concept of the equivalent intergranular void ratio may be an appropriate parameter to express the critical shear strength of the soil under investigation. This parameter is able to control the undrained shear strength of non plastic silt and sand mixtures for different density states