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  • Open Access

    REVIEW

    Toward 6G Communication Networks: Terahertz Frequency Challenges and Open Research Issues

    Mohammed H. Alsharif1, Mahmoud A. M. Albreem2, Ahmad A. A. Solyman3, Sunghwan Kim4,*

    CMC-Computers, Materials & Continua, Vol.66, No.3, pp. 2831-2842, 2021, DOI:10.32604/cmc.2021.013176

    Abstract Future networks communication scenarios by the 2030s will include notable applications are three-dimensional (3D) calls, haptics communications, unmanned mobility, tele-operated driving, bio-internet of things, and the Nano-internet of things. Unlike the current scenario in which megahertz bandwidth are sufficient to drive the audio and video components of user applications, the future networks of the 2030s will require bandwidths in several gigahertzes (GHz) (from tens of gigahertz to 1 terahertz [THz]) to perform optimally. Based on the current radio frequency allocation chart, it is not possible to obtain such a wide contiguous radio spectrum below 90 GHz (0.09 THz). Interestingly, these… More >

  • Open Access

    ARTICLE

    Frequencies Rotation at High Sound Pressure Levels Toward Low Frequencies

    Hadi Negahdari1, Sirus Javadpour2,*, Faramarz Moattar3

    Sound & Vibration, Vol.54, No.4, pp. 237-246, 2020, DOI:10.32604/sv.2020.011086

    Abstract Today, analyzing of sound pressure level and frequency is considered as an important index in human society. Sound experts believe that analyzing of these parameters can help us to better understanding of work environments. Sound measurements and frequency analysis did to fix the harmful frequency in all sections in Shiraz gas power plant with sound analyzer model BSWA 308. The sound pressure levels (LP) and the one and one-third octave band were continuously measured in A and C weighting networks and slow mode for time response. Excel 2013 and Minitab 18.1 software used for statistical calculations. Results analyzed by Minitab… More >

  • Open Access

    ARTICLE

    Comparison of Fuzzy Synthetic Evaluation and Field Measurement of Internal Defects in Assembled Concrete Detected by Ultrasonic Waves

    Hua Yan1,2,3,*, Bo Song1,3, Mansheng Wang4

    Structural Durability & Health Monitoring, Vol.14, No.3, pp. 265-282, 2020, DOI:10.32604/sdhm.2020.06403

    Abstract Analyze and compare the basic principles of ultrasonic detection of voids in concrete, choose ZBL-U520/510 non-metallic ultrasonic detector, and use the opposite detection method to test the void size in the joints of prefabricated concrete structures. The results show that: ultrasonic method by testing the waveform, sound, and speed of sound analysis can effectively determine the position of the defect, and through the conversion formula can estimate the void size. Ultrasonic parameters are used to distinguish the internal defects of Assembly concrete. Sometimes there are different results with different parameters. It is difficult for engineers to directly determine the internal… More >

  • Open Access

    ARTICLE

    Fast Superfine Components and Sound Packets in Phenomena Induced by the Impact of a Drop on a Target Fluid in Quiescent Conditions

    Yuli D. Chashechkin*

    FDMP-Fluid Dynamics & Materials Processing, Vol.16, No.4, pp. 773-800, 2020, DOI:10.32604/fdmp.2020.09001

    Abstract The structure of the flow and the acoustic signals generated by the impact of a freely falling drop of water with an underlying quiescent fluid have been investigated for droplets having diameter 0.5 cm and a contact velocity in the range 1.5 < U < 5 m/s. The experimental study has been supported by high-resolution videos of the flow (as seen from above and from the side). The evolution of ejecta, spikes, droplets spray, cavity, splash, secondary cavity, streamer, secondary droplets and sequence of capillary waves is reported accordingly. In particular, perturbations of the smoothed free surface with transverse dimensions… More >

  • Open Access

    ARTICLE

    Effect of Absorption of Patch Antenna Signals on Increasing the Head Temperature

    Mohamed Abbas1,3,*, Ali Algahtani2,6, Amir Kessentini2,4,7, Hassen Loukil1,5, Muneer Parayangat1, Thafasal Ijyas1, Abdul Wase Mohammed1

    CMES-Computer Modeling in Engineering & Sciences, Vol.124, No.2, pp. 683-701, 2020, DOI:10.32604/cmes.2020.010304

    Abstract Every new generation of antennas is characterized by increased accuracy and faster transmission speeds. However, patch antennas have been known to damage human health. This type of antenna sends out electromagnetic waves that increase the temperature of the human head and prevent nerve strands from functioning properly. This paper examines the effect of the communication between the patch antenna and the brain on the head’s temperature by developing a hypothetical multi-input model that achieves more accurate results. These inputs are an individual’s blood and tissue, and the emission power of the antenna. These forces depend on the permeability and conductivity… More >

  • Open Access

    ARTICLE

    A Statistical Model for Phase Difference Spectrum of Ground-Motion and Its Application in Generating Non-Stationary Seismic Waves

    Dongsheng Du1,*, Sheng Shi1, Weizhi Xu1, Chen Kong2, Shuguang Wang1, Weiwei Li1

    CMES-Computer Modeling in Engineering & Sciences, Vol.124, No.1, pp. 265-285, 2020, DOI:10.32604/cmes.2020.09151

    Abstract The intensity non-stationarity is one of the most important features of earthquake records. Modeling of this feature is significant to the generation of arti- ficial earthquake waves. Based on the theory of phase difference spectrum, an intensity non-stationary envelope function with log-normal form is proposed. Through a tremendous amount of earthquake records downloaded on Kik-net, a parameter fitting procedure using the genetic algorithm is conducted to obtain the value of model parameters under different magnitudes, epicenter distances and site conditions. A numerical example is presented to describe the procedure of generating fully non-stationary ground motions via spectral representation, and the… More >

  • Open Access

    ARTICLE

    Bifid T waves on the ECG and genetic variation in calcium channel voltage‐dependent beta 2 subunit gene (CACNB2) in acute Kawasaki disease

    Jun Oyamada1, Chisato Shimizu1, Jihoon Kim2, Matthew R. Williams1,3, Eileen Png4, Martin L. Hibberd4, Adriana H. Tremoulet1,3, James C. Perry1,3, Jane C. Burns1,3

    Congenital Heart Disease, Vol.14, No.2, pp. 213-220, 2019, DOI:10.1111/chd.12696

    Abstract Background: We previously described the association of genetic variants in calcium channel genes and susceptibility to Kawasaki disease (KD), an acute, self‐limited vas‐ culitis, and the most common cause of acquired cardiac disease in children. Abnormal repolarization of cardiomyocytes and changes in T wave morphology have been re‐ ported in KD but have not been studied systematically.
    Methods: We analyzed acute and convalescent ECG T wave morphology in two inde‐ pendent cohorts of KD subjects and studied the association between bifid T waves and genetic variants in previously reported genes with SNVs associated with cardiac repolarization.
    Results: Bifid T waves… More >

  • Open Access

    ARTICLE

    Analytical and Numerical Investigation for the DMBBM Equation

    Abdulghani Alharbi1, Mahmoud A. E. Abdelrahman1, 2, *, M. B. Almatrafi1

    CMES-Computer Modeling in Engineering & Sciences, Vol.122, No.2, pp. 743-756, 2020, DOI:10.32604/cmes.2020.07996

    Abstract The nonlinear dispersive modified Benjamin-Bona-Mahony (DMBBM) equation is solved numerically using adaptive moving mesh PDEs (MMPDEs) method. Indeed, the exact solution of the DMBBM equation is obtained by using the extended Jacobian elliptic function expansion method. The current methods give a wider applicability for handling nonlinear wave equations in engineering and mathematical physics. The adaptive moving mesh method is compared with exact solution by numerical examples, where the explicit solutions are known. The numerical results verify the accuracy of the proposed method. More >

  • Open Access

    ARTICLE

    On the Onset of Cracks in Arteries1

    P. Mythravaruni, K.Y. Volokh*

    Molecular & Cellular Biomechanics, Vol.17, No.1, pp. 1-17, 2020, DOI:10.32604/mcb.2019.07606

    Abstract We present a theoretical approach to study the onset of failure localization into cracks in arterial wall. The arterial wall is a soft composite comprising hydrated ground matrix of proteoglycans reinforced by spatially dispersed elastin and collagen fibers. As any material, the arterial tissue cannot accumulate and dissipate strain energy beyond a critical value. This critical value is enforced in the constitutive theory via energy limiters. The limiters automatically bound reachable stresses and allow examining the mathematical condition of strong ellipticity. Loss of the strong ellipticity physically means inability of material to propagate superimposed waves. The waves cannot propagate because… More >

  • Open Access

    ARTICLE

    The Frequency Selection of SH0 Waves for Total Transmission and Its Application in the Damage Detection of Aircrafts

    Yanchao Yue1, *, Tangbing Chen1, Lingling Zhang1, Moustafa Abdelsalam1, Josephine Musanyufu1

    CMES-Computer Modeling in Engineering & Sciences, Vol.122, No.1, pp. 259-272, 2020, DOI:10.32604/cmes.2020.07218

    Abstract Based on wave interference, a methodology to realize the total transmission phenomenon of SH0 waves is proposed in this paper. After a systematical theoretical investigation, an exact frequency of a flat plate consisting of another medium with finite length, is obtained, which is furthermore exemplified by the finite element method. This frequency is the same as the classical Fabry-Perot condition and dependent on the thickness of the material. It has been revealed that an SH0 wave, with its wavelength equal to twice of the length of another medium, can totally transmit across the medium without reflection. Especially when the impedance… More >

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