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  • Open Access

    ARTICLE

    A Study on the Strength Surplus Coefficient of Cement

    Yuhang Long1, Jingyi Wang2,*

    FDMP-Fluid Dynamics & Materials Processing, Vol.17, No.1, pp. 181-187, 2021, DOI:10.32604/fdmp.2021.011185

    Abstract This study considers P.O42.5 cement from different sources and evaluates the related surplus coefficient (defined as the proportionality factor linking the measured compressive strength value of the cement after 28 days to the “standard” value of cement strength). The needed tests have been conducted using a mixer, a pressure testing machine, a flexural testing machine, a vibrating table a ramming rod, a feeder and a metal ruler. The average value of the measured cement strength surplus coefficient of cement produced by five distinct cement manufacturers has been found to be 1.16. These results can be used as the basis to… More >

  • Open Access

    ARTICLE

    Collision Observation-Based Optimization of Low-Power and Lossy IoT Network Using Reinforcement Learning

    Arslan Musaddiq1, Rashid Ali2, Jin-Ghoo Choi1, Byung-Seo Kim3,*, Sung-Won Kim1

    CMC-Computers, Materials & Continua, Vol.67, No.1, pp. 799-814, 2021, DOI:10.32604/cmc.2021.014751

    Abstract The Internet of Things (IoT) has numerous applications in every domain, e.g., smart cities to provide intelligent services to sustainable cities. The next-generation of IoT networks is expected to be densely deployed in a resource-constrained and lossy environment. The densely deployed nodes producing radically heterogeneous traffic pattern causes congestion and collision in the network. At the medium access control (MAC) layer, mitigating channel collision is still one of the main challenges of future IoT networks. Similarly, the standardized network layer uses a ranking mechanism based on hop-counts and expected transmission counts (ETX), which often does not adapt to the dynamic… More >

  • Open Access

    ARTICLE

    Pseudogamous Apomixis in Maize and Sorghum in Diploid-Tetraploid Crosses

    Marina Tsvetova1, Lev Elkonin1,*, Yulia Italianskaya1

    Phyton-International Journal of Experimental Botany, Vol.88, No.4, pp. 389-401, 2019, DOI:10.32604/phyton.2019.07485

    Abstract Apomictic seed development is a complex process including formation of unreduced embryo sac, parthenogenetic embryo development from the egg cell, and endosperm formation either autonomously, or due to fertilization of polar nuclei by the sperm (under pseudogamous form of apomixis). In the latter case, an obstacle to the normal endosperm development is disturbance of maternal (m) -to-paternal (p) genomic ratio 2m: 1p that occurs in the cases of pollination of unreduced embryo sac with haploid sperms. Usage of tetraploid pollinators can overcome this problem because in such crosses maternal-to-paternal genomic ratio is 4m: 2p that provides formation of kernels with… More >

  • Open Access

    ABSTRACT

    Effect of cross flow on aerodynamics of a commercial airplane

    Yangkyun kim1, Sungcho Kim2, Jongwook Choi2, Jeong Soo Kim2

    The International Conference on Computational & Experimental Engineering and Sciences, Vol.11, No.4, pp. 123-124, 2009, DOI:10.3970/icces.2009.011.123

    Abstract This paper analyzes computationally the flow field for the full geometry model of a commercial passenger airplane, Boeing747-400. The geometric dimension of an airplane was acquired by means of the reverse engineering technique adopting the photo scanning measurement. The steady three-dimensional viscous compressible flow field was calculated when the airplane cruises under side flow. The basic computational conditions were considered as the same to those of Boeing 747-400's cruising state, i.e., the atmospheric condition at 13 km above the sea level and Mach number of 0.85. The boundary conditions are the same that the freestream with side flow approaches to… More >

  • Open Access

    ARTICLE

    Study on the Contact Stress Concentration and the Hyperplasia of the Canine Trachea Granulation Tissue after Stenting

    Molecular & Cellular Biomechanics, Vol.15, No.1, pp. 51-61, 2018, DOI:10.3970/mcb.2018.015.051

    Abstract Tracheal stenosis is a common respiratory disease and is usually treated by stent implantation. However, the implanted stent often causes excessive hyperplasia of trachea granulation tissue, leading to the restenosis. Although surgical removal or chemical suppression can be used to alleviate the restenosis, the efficacy is limited. Thus, restenosis remains a thorny complication. We investigated this issue from the perspective of the “tress-growth”relationship. Firstly, the lower airway of 5 experimental dogs were CT-scanned to reconstruct the 3D numerical models; secondly, the implantations of the Nitinol alloy stents were numerically simulated; thirdly, 45 days after the stenting, the dogs were evaluated… More >

  • Open Access

    ARTICLE

    Numerical Simulations of Pulsatile Flow in an End-to-Side Anastomosis Model

    E. Shaik, K.A. Hoffmann, J-F. Dietiker

    Molecular & Cellular Biomechanics, Vol.4, No.1, pp. 41-54, 2007, DOI:10.3970/mcb.2007.004.041

    Abstract A potential interaction between the local hemodynamics and the artery wall response has been suggested for vascular graft failure by intimal hyperplasia (IH). Among the various hemodynamic factors, wall shear stress has been implicated as the primary factor responsible for the development of IH. In order to explore the role of hemodynamics in the formation of IH in end-to-side anastomosis, computational fluid dynamics is employed. To validate the numerical simulations, comparisons with existing experimental data are performed for both steady and pulsatile flows. Generally, good agreement is observed with the velocity profiles whereas some discrepancies are found in wall shear… More >

  • Open Access

    ARTICLE

    An Explicit Numerical Modeling of Soft Body Impact Damage in Metallic Airplane Structures

    I. Smojver1, D. Ivancevic1, D. Mihaljevic2

    CMES-Computer Modeling in Engineering & Sciences, Vol.70, No.2, pp. 191-216, 2010, DOI:10.3970/cmes.2010.070.191

    Abstract This paper tackles the problem of numerical prediction of bird strike induced damage in real aeronautical structures using highly detailed finite element models and modern numerical approaches. Due to the complexity of today's aeronautical structures, numerical damage prediction methods have to be able to take into account various failure and degradation models of different materials. The work presented in this paper is focused on damage modeling in metallic items of aeronautical structures.
    Abaqus/Explicit has been employed to perform geometrical and material nonlinear transient dynamic analyses. The problem of soft body impacts has been tackled by applying a hybrid Eulerian Lagrangian… More >

  • Open Access

    ARTICLE

    Lateral Plastic Collapse of Cylinders: Experiments and Modeling

    K. Nesnas1, A. Abdul-Latif2

    CMES-Computer Modeling in Engineering & Sciences, Vol.2, No.3, pp. 373-388, 2001, DOI:10.3970/cmes.2001.002.373

    Abstract Large plastic collapse of an identical pair of cylinders of various geometries having the same length and volume is studied under lateral compressive load. Superplastic material is employed as a representative material to simulate the classical engineering material behavior under high strain rate. The effects of the strain rate and the geometry of cylinders on the plastic collapse are taken into account. The experimental study is conducted using a structure in which one cylinder is superplastic and the other is steel (referred to as deformable and non-deformable situation "DND''). The actual structure (DND) and that one investigated experimentally by Abdul-Latif… More >

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