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  • Open Access

    ARTICLE

    The Effects of Gamma Irradiation on Molecular Weight, Morphology and Physical Properties of PHBV/Cloisite 30B Bionanocomposites

    Kahina Iggui1,2,*, Mustapha Kaci1, Mohamed Mahlous3, Nicolas Le Moigne4, Anne Bergeret4

    Journal of Renewable Materials, Vol.7, No.9, pp. 807-820, 2019, DOI:10.32604/jrm.2019.06778

    Abstract In this paper, the effects of gamma irradiation on Cast poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and PHBV/Cloisite 30B (C30B) (3 wt%) bionanocomposite prepared by melt compounding, were evaluated at various doses, i.e., 5, 15, 20, 50 and 100 kGy at room temperature in air. Changes in molecular weight, morphology and physical properties were investigated. The study showed that the main degradation mechanism occurring in gamma irradiation in both Cast PHBV and C-PHBV/3C30B bionanocomposite is chain scission, responsible for the decrease of molecular weight. Differential scanning calorimetry (DSC) data indicated a regular decrease in crystallization temperature, melting temperature and crystallinity index for all irradiated… More >

  • Open Access

    ARTICLE

    Microwave-Assisted Isolation and Acetylation of Inulin from Helianthus Tuberosus L Tubers

    Nadezhda Petkova1,*, Gergana Gencheva1, Dragomir Vassilev2, Milena Koleva2, Albert Krastanov3, Panteley Denev1

    Journal of Renewable Materials, Vol.6, No.7, pp. 671-679, 2018, DOI:10.32604/JRM.2018.00001

    Abstract Jerusalem artichoke (Helianthus tuberosus L.) tubers are industrial crop considered as a promising source for inulin production. “Green” method was performed for accelerated inulin extraction from Helianthus tuberosus L. tubers by the application of microwave irradiation. Further pretreatment of the water extract with acetone and ethanol yielded inulin (20%) with purity 89% and degree of polymerization 18. Jerusalem artichoke inulin was characterized by FTIR and NMR spectroscopy. For the first time eco-friendly synthesis of acetylated Jerusalem artichoke inulin was performed by the reaction with acetic anhydride, without toxic solvent, but only with sodium acetate as catalyst under microwave irradiation for… More >

  • Open Access

    ARTICLE

    On the use of a wave based prediction technique for steady-state structural-acoustic radiation analysis

    B. Pluymers1, W. Desmet1, D. Vandepitte1, P. Sas1

    CMES-Computer Modeling in Engineering & Sciences, Vol.7, No.2, pp. 173-184, 2005, DOI:10.3970/cmes.2005.007.173

    Abstract Conventional element based methods for modelling structural-acoustic radiation problems are limited to low-frequency applications. Recently, a novel prediction technique has been developed based on the indirect Trefftz approach. This new wave based method is computationally more efficient than the element based methods and, as a consequence, can tackle problems also at higher frequencies. This paper discusses the basic principles of the new method and illustrates its performance for the two-dimensional radiation analysis of a bass-reflex loudspeaker. More >

  • Open Access

    ARTICLE

    Radiation Cross Calibration Based on GF-1 Side Swing Angle

    Yong Xie1, Zui Tao2,*, Wen Shao3, John J. Qu4, Hai Huan3, Chuanyang Tian3

    Journal on Internet of Things, Vol.1, No.1, pp. 9-16, 2019, DOI:10.32604/jiot.2019.05859

    Abstract Radiation cross-calibration is an effective method to check and verify the accuracy and stability of sensor measurements. Satellites with high radiation accuracy are used to calibrate satellites with low radiation accuracy. In order to ensure the reliability of the radiation cross-calibration method, we propose to obtain the gain and offset of the GaoFen-1 satellite by linear regression after the radiation cross-calibration of the satellite with low precision and compare with the official coefficient. Finally, we get the relationship between the error in radiation cross-calibration results and side swing angle. The linear correction coefficients of each band are: 0.618, 0.625, 0.512… More >

  • Open Access

    ARTICLE

    Conductive Polymer Composites Synthesized from Diacetylene-Functionalized Linseed Oil and MWCNT: Gamma Irradiation and Organic Vapor Sensing

    A. Ramírez-Jiménez1*, S. Hernández López1, E. Bucio2, E. Vigueras Santiago1

    Journal of Renewable Materials, Vol.5, No.2, pp. 132-144, 2017, DOI:10.7569/JRM.2016.634138

    Abstract Epoxidized linseed oil (ELO) was synthesized and functionalized with propargylamine (PA) or 3-ethynylaniline (EA) and the products were crosslinked to obtain the diacetylene-functionalized epoxidized linseed oil polymers which were used as matrices in the preparation of the composites with multiwalled carbon nanotubes (MWCNTs). Electrical resistance at percentages between 4 and 20 wt/wt% of filler was measured and the percolation threshold was calculated, obtaining 1.2 and 1.7% for the composites with EA and PA respectively. Low critical concentration evidenced a good dispersion of the MWCNTs without necessity of any modification. The final products were used in the sensing of acetone, chloroform… More >

  • Open Access

    ARTICLE

    Transient Bioheat Simulation of the Laser-Tissue Interaction in Human Skin Using Hybrid Finite Element Formulation

    Ze-Wei Zhang*, Hui Wang, Qing-Hua Qin∗,‡

    Molecular & Cellular Biomechanics, Vol.9, No.1, pp. 31-54, 2012, DOI:10.3970/mcb.2012.009.031

    Abstract This paper presents a hybrid finite element model for describing quantitatively the thermal responses of skin tissue under laser irradiation. The model is based on the boundary integral-based finite element method and the Pennes bioheat transfer equation. In this study, temporal discretization of the bioheat system is first performed and leads to the well-known modified Helmholtz equation. A radial basis function approach and the boundary integral based finite element method are employed to obtain particular and homogeneous solutions of the laser-tissue interaction problem. In the boundary integral based finite element formulation, two independent fields are assumed: intra-element field and frame… More >

  • Open Access

    ARTICLE

    Theoretical Analysis of Thermal Damage in Biological Tissues Caused by Laser Irradiation

    Jianhua Zhou, J. K. Chen, Yuwen Zhang

    Molecular & Cellular Biomechanics, Vol.4, No.1, pp. 27-40, 2007, DOI:10.3970/mcb.2007.004.027

    Abstract A bioheat transfer approach is proposed to study thermal damage in biological tissues caused by laser radiation. The laser light propagation in the tissue is first solved by using a robust seven-flux model in cylindrical coordinate system. The resulting spatial distribution of the absorbed laser energy is incorporated into the bioheat transfer equation for solving temperature response. Thermal damage to the tissue is assessed by the extent of denatured protein using a rate process equation. It is found that for the tissue studied, a significant protein denaturation process would take place when temperature exceeds about 53oC. The effects of laser… More >

  • Open Access

    ARTICLE

    Applying a Step Approach Method in Solving the Multi-Frequency Radiation From a Complex Obstacle

    Jui-Hsiang Kao1

    CMES-Computer Modeling in Engineering & Sciences, Vol.112, No.1, pp. 59-73, 2016, DOI:10.3970/cmes.2016.112.059

    Abstract In this paper, a step approach method in the time domain is developed to calculate the radiated waves from an arbitrary obstacle pulsating with multiple frequencies. The computing scheme is based on the Boundary Integral Equation and derived in the time domain; thus, the time-harmonic Neumann boundary condition can be imposed. By the present method, the values of the initial conditions are set to zero, and the approach process is carried forward in a loop from the first time step to the last. At each time step, the radiated pressure on each element is updated. After several loops, the correct… More >

  • Open Access

    ARTICLE

    Singular Boundary Method: Three Regularization Approaches and Exterior Wave Applications

    Zhuo-Jia Fu1, Wen Chen1,2, Jeng-Tzong Chen3, Wen-Zhen Qu1

    CMES-Computer Modeling in Engineering & Sciences, Vol.99, No.5, pp. 417-443, 2014, DOI:10.3970/cmes.2014.099.417

    Abstract This study investigates the singular boundary method (SBM) with three regularization approaches for solving 2D and 3D exterior wave problems. The singular boundary method is a recent meshless boundary collocation method, which introduces the concept of source intensity factors to eliminate the singularity of the fundamental solutions. Recently, three approaches, the inverse interpolation technique (IIT), the semi-analytical technique with boundary IIT (SAT1) and the semi-analytical technique with integral mean value (SAT2), have been proposed to determine the source intensity factors for removing the singularities of Helmholtz fundamental solutions at origin. This study compares numerical accuracy and stability of these three… More >

  • Open Access

    ARTICLE

    Sound Power Radiation Sensitivity and Variability Using a 'Hybrid' Numerical Model

    Max de Castro Magalhaes1

    CMES-Computer Modeling in Engineering & Sciences, Vol.89, No.4, pp. 263-281, 2012, DOI:10.3970/cmes.2012.089.263

    Abstract The main objective is to develop a 'hybrid' numerical method for predicting sound power radiated from honey-comb panels and analyze the sensitivity and variability of it to different boundary conditions. The honey-comb panels are mainly used on the aerospace, mechanical and civil engineering design. The method used herein is a combination of the Finite Element Method and the Jinc Function Approach. The original contribution of this paper is therefore to show the sensitivity of sound power radiated from a honey-comb panel using a 'hybrid' method which is simple and efficient on tackling sound radiation problems for complex orthotropic panels, especially… More >

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