Janja Kramer, Renata Jecl, Leopold Skerget

The International Conference on Computational & Experimental Engineering and Sciences, Vol.12, No.4, pp. 147-148, 2009, DOI:10.3970/icces.2009.012.147

Abstract A numerical study of double diffusive natural convection in porous media due to opposing buoyancy forces is reported, using the Boundary Domain Integral Method (BDIM). There have been several reported studies dealing with natural convection in porous media, mainly because of its importance in several industrial and technological applications. Less attention, however, has been dedicated to the so-called double diffusive problems, where density gradients occur due to the effects of combined temperature and concentration buoyancy. The current investigation is focused on the special problem, where the thermal and solutal buoyancy forces are opposing each other.
The mathematical model of fluid… More >

Sang-Hyun Lee¹, Sung-Sik Woo¹, Seung-Ho Cho¹, Lan Chung¹

The International Conference on Computational & Experimental Engineering and Sciences, Vol.8, No.3, pp. 115-120, 2008, DOI:10.3970/icces.2008.008.115

Abstract In this study, based on the results from the sinusoidal base excitation analyses of a single degree of freedom system with a tuned mass damper (TMD), the optimal friction is computed so that the rail friction improve the performance of the TMD. The magnitude of the optimal friction increases with increasing mass ratio of the TMD and decreases with increasing structural damping. Particularly, it is observed that the optimized friction force gives better control performance than the optimized viscous damping of the TMD. However, because the performance of the TMD considerably deteriorates when the friction force increases over the optimal… More >

J. Gajdošík¹, M. Šejnoha¹, J. Zeman¹

The International Conference on Computational & Experimental Engineering and Sciences, Vol.4, No.2, pp. 129-136, 2007, DOI:10.3970/icces.2007.004.129

Abstract Rock masses with relatively high concentration of discontinuities or joints are considered. Being aware of limitations of various averaging techniques such as the self consistent or Mori-Tanaka methods in providing reliable estimates of generally nonlinear macroscopic response of jointed rock masses, the paper introduces a notion of statistically equivalent periodic unit cell (SEPUC). Such a unit cell contains, in order to reduce the problem complexity, of the orders of magnitude less number of joints in comparison with the actual material system. In analogy with two-phase composites, the SEPUC is expected to be found in a statistical sense by matching suitable… More >

Zixin Zhang^1,2,*, Shuaifeng Wang^1,2, Xin Huang^1,2

The International Conference on Computational & Experimental Engineering and Sciences, Vol.21, No.2, pp. 29-29, 2019, DOI:10.32604/icces.2019.04704

Abstract Block theory is widely used in numerical simulation of rock engineering due to its concision and fast-calculation. The paper proposes block theory for TBM (tunnel boring machine) tunnels to extend the traditional block theory applicative for tunnels excavated by TBM. In the proposed method, TBM-block interaction forces are taken into consideration. Subsequently, an index is proposed to estimate the stability of the TBM tunnel based on safety factor at every given chainage of the tunnel. Finally, a real water-conveyance tunnel project is studied with block theory for TBM tunnels. The simulation results include the joint characterization, classification identification of different… More >

Md. Anwar Hossain^1,2, Lee Hwei Voon^1,*

Journal of Renewable Materials, Vol.7, No.8, pp. 731-748, 2019, DOI:10.32604/jrm.2019.04703

Abstract Synthesizing polyol-based ester from biomass feedstocks for the preparation of biolubricant overcomes the dependence on petroleum oil usage. Albeit biomass-derived bio-oil is an alternative for the production of polyol ester, upgrading is essential prior to use as biolubricant. Levulinic acid (LA), obtained from bio-oil was applied for the catalytic esterification with two polyols, e.g., trimethylolpropane (TMP) and pentaerythritol (PE), in the presence of mixed-ligand Ni(II), Co(II), and Fe(II) complexes as catalyst. New mixed-ligand coordination complexes with empirical formula; [Ni(Phe)(Bpy)Cl].H2O, [Co(Phe)(Bpy)Cl].H2O, and [Fe(Phe)(Tyr)Cl].H2O were synthesized by the reaction of ligands [L-phenylalanine (Phe), 4,4'-bipyridine (Bpy), and L-tyrosine (Tyr)] with metal chloride salts… More >

Juan Carlos Torres Lozada*

Journal of Renewable Materials, Vol.7, No.6, pp. 523-525, 2019, DOI:10.32604/jrm.2019.04053

Abstract This paper presents the patent of a new additive for the construction industry, which is obtained from the biomass residues of the wood industry. This additive is biodegradable and has fluidifying, foaming, plasticizing and stabilizing properties. When the additive is mixed with cement binder compositions, cement mortar and concrete, lightweight, flame-retardant cellular materials, thermal and acoustic insulators are obtained. More >

Mehul Barde^1,2, Yusuf Celikbag³, Brian Via³, Sushil Adhikari⁴, Maria L. Auad^1,2,*

Journal of Renewable Materials, Vol.6, No.7, pp. 724-736, 2018, DOI:10.32604/JRM.2018.00116

Abstract Bio-based phenol-formaldehyde polymer (BioNovolac) was developed by reacting molar excess of bio-oil/phenol with formaldehyde in acidic medium. Glycidyl 3,5-diglycidoxybenzoate (GDGB), was prepared by direct glycidylation of α-resorcylic acid (RA), a naturally occurring phenolic monomer. GDGB was crosslinked in the presence of BioNovolac by anionic polymerization. Fourier transform infrared spectroscopy (FTIR) confirmed the formation of semi-interpenetrating polymer networks. The glass transition temperature and moduli of bio-based crosslinked systems were observed to increase with increasing GDGB content. Active chain density and mass retention measured by dynamic mechanical analysis (DMA) and Soxhlet extraction, respectively, indicated a high crosslink density of the cured networks.… More >

Cristiane S. Farinas*, José Manoel Marconcini, Luiz Henrique C. Mattoso

Journal of Renewable Materials, Vol.6, No.2, pp. 203-216, 2018, DOI:10.7569/JRM.2017.6341578

Abstract The conversion of sugarcane lignocellulosic biomass into fuels, chemicals and high-value materials using the biochemical pathway is considered the most sustainable alternative for the implementation of future biorefineries. Actually, the first large-scale cellulosic ethanol plants that have started operating worldwide apply the enzymatic hydrolysis process to convert biomass into simple sugars that are fermented to ethanol by yeasts. However, several technological challenges still need to be addressed in order to obtain commercially competitive products. This review describes current challenges and perspectives regarding the enzymatic hydrolysis step for processing sugarcane lignocellulosic biomass within the biorefinery. Recent developments in terms of process… More >

Reynaldo Palacios-Bereche¹, Adriano Ensinas², Marcelo Modesto¹, Silvia Nebra^1,3,*

Journal of Renewable Materials, Vol.6, No.2, pp. 183-194, 2018, DOI:10.7569/JRM.2017.634175

Abstract The aim of this study is to assess the possibility of increasing ethanol production by introducing the bagasse hydrolysis process into conventional distilleries. Simulations were performed for mass and energy balances using Aspen Plus® software. It was assumed that sugarcane trash and lignin cake—hydrolysis process residues—are available as supplementary fuel. Several cases were evaluated, including: (a) conventional ethanol distillery, (b) conventional plant combined with a hydrolysis process without heat integration, with different solid contents in the hydrolysis reactor, and (c) conventional plant combined with the hydrolysis process applying heat integration by pinch analysis. The highest ethanol yield was achieved in… More >

S.H. Hassan^1,2, Lee Hwei Voon^1*, T.S. Velayutham^2*, Lindong Zhai³, Hyun Chan Kim³, Jaehwan Kim³

Journal of Renewable Materials, Vol.6, No.1, pp. 1-25, 2018, DOI:10.7569/JRM.2017.634173

Abstract Cellulose is a renewable biomass material and natural polymer which is abundantly available on Earth, and includes agricultural wastes, forestry residues, and woody materials. The excellent and smart characteristics of cellulose materials, such as lightweight, biocompatibility, biodegradability, high mechanical strength/stiffness and low thermal expansibility, have made cellulose a high-potential material for various industry applications. Cellulose has recently been discovered as a smart material in the electroactive polymers family which carries the name of cellulose-based electroactive paper (EAPap). The shear piezoelectricity in cellulose polymers is able to induce large displacement output, low actuation voltage, and low power consumption in the application… More >