Home / Journals / CMES / Vol.123, No.2, 2020
Table of Content
  • Open Access

    ARTICLE

    Addition Formulas of Leaf Functions and Hyperbolic Leaf Functions

    Kazunori Shinohara*
    CMES-Computer Modeling in Engineering & Sciences, Vol.123, No.2, pp. 441-473, 2020, DOI:10.32604/cmes.2020.08656
    Abstract Addition formulas exist in trigonometric functions. Double-angle and half-angle formulas can be derived from these formulas. Moreover, the relation equation between the trigonometric function and the hyperbolic function can be derived using an imaginary number. The inverse hyperbolic function is similar to the inverse trigonometric function , such as the second degree of a polynomial and the constant term 1, except for the sign − and +. Such an analogy holds not only when the degree of the polynomial is 2, but also for higher degrees. As such, a function exists with respect… More >

  • Open Access

    ARTICLE

    Determination of Time-Dependent Coefficients for a Weakly Degenerate Heat Equation

    M. J. Huntul1, D. Lesnic2, *
    CMES-Computer Modeling in Engineering & Sciences, Vol.123, No.2, pp. 475-494, 2020, DOI:10.32604/cmes.2020.08791
    Abstract In this paper, we consider solving numerically for the first time inverse problems of determining the time-dependent thermal diffusivity coefficient for a weakly degenerate heat equation, which vanishes at the initial moment of time, and/or the convection coefficient along with the temperature for a one-dimensional parabolic equation, from some additional information about the process (the so-called over-determination conditions). Although uniquely solvable these inverse problems are still ill-posed since small changes in the input data can result in enormous changes in the output solution. The finite difference method with the Crank-Nicolson scheme combined with the nonlinear Tikhonov regularization are employed. The… More >

  • Open Access

    ARTICLE

    Innovative Design and Additive Manufacturing of Regenerative Cooling Thermal Protection System Based on the Triply Periodic Minimal Surface Porous Structure

    Xinglong Wang1,2, Cheng Wang1,2, Xin Zhou1,*, Mingkang Zhang3, Peiyu Zhang1, Lei Wang2
    CMES-Computer Modeling in Engineering & Sciences, Vol.123, No.2, pp. 495-508, 2020, DOI:10.32604/cmes.2020.09778
    (This article belongs to this Special Issue: Design & simulation in Additive Manufacturing)
    Abstract The new regenerative cooling thermal protection system exhibits the multifunctional characteristics of load-carrying and heat exchange cooling, which are fundamental for the lightweight design and thermal protection of hypersonic vehicles. Triply periodic minimal surface (TPMS) is especially suitable for the structural design of the internal cavity of regenerative cooling structures owing to its excellent structural characteristics. In this study, test pieces were manufactured using Ti6Al4V lightweight material. We designed three types of porous test pieces, and the interior was filled with a TPMS lattice (Gyroid, Primitive, I-WP) with a porosity of 30%. All porous test pieces were manufactured via selective… More >

  • Open Access

    ARTICLE

    A Staggered Grid Method for Solving Incompressible Flow on Unstructured Meshes

    Huawen Shu, Minghai Xu, Xinyue Duan*, Yongtong Li, Yu Sun, Ruitian Li, Peng Ding
    CMES-Computer Modeling in Engineering & Sciences, Vol.123, No.2, pp. 509-523, 2020, DOI:10.32604/cmes.2020.08806
    (This article belongs to this Special Issue: Advances in Modeling and Simulation of Complex Heat Transfer and Fluid Flow)
    Abstract A finite volume method based unstructured grid is presented to solve the two dimensional viscous and incompressible flow. The method is based on the pressure-correction concept and solved by using a semi-staggered grid technique. The computational procedure can handle cells of arbitrary shapes, although solutions presented in this paper were only involved with triangular and quadrilateral cells. The pressure or pressure-correction value was stored on the vertex of cells. The mass conservation equation was discretized on the dual cells surrounding the vertex of primary cells, while the velocity components and other scale variables were saved on the central of primary… More >

  • Open Access

    ARTICLE

    Toward a More Accurate Web Service Selection Using Modified Interval DEA Models with Undesirable Outputs

    Alireza Poordavoodi1, Mohammad Reza Moazami Goudarzi2,*, Hamid Haj Seyyed Javadi3, Amir Masoud Rahmani4, Mohammad Izadikhah5
    CMES-Computer Modeling in Engineering & Sciences, Vol.123, No.2, pp. 525-570, 2020, DOI:10.32604/cmes.2020.08854
    Abstract With the growing number of Web services on the internet, there is a challenge to select the best Web service which can offer more quality-of-service (QoS) values at the lowest price. Another challenge is the uncertainty of QoS values over time due to the unpredictable nature of the internet. In this paper, we modify the interval data envelopment analysis (DEA) models [Wang, Greatbanks and Yang (2005)] for QoS-aware Web service selection considering the uncertainty of QoS attributes in the presence of desirable and undesirable factors. We conduct a set of experiments using a synthesized dataset to show the capabilities of… More >

  • Open Access

    ARTICLE

    Numerical Study of the Distribution of Temperatures and Relative Humidity in a Ventilated Room Located in Warm Weather

    J. Serrano-Arellano1, J. M. Belman-Flores2,*, I. Hernández-Pérez3, K. M. Aguilar-Castro3, E. V. Macías-Melo3, F. Elizalde-Blancas2, J. M. Riesco-Ávila2, F. J. García-Rodríguez4
    CMES-Computer Modeling in Engineering & Sciences, Vol.123, No.2, pp. 571-602, 2020, DOI:10.32604/cmes.2020.08677
    Abstract In the present study, an analysis of the heat and mass transfer in a ventilated cavity in a warm climate zone was carried out to analyze, among others, the temperatures and percentage of relative humidity (RH). The governing equations of the mathematical model were solved through the finite volume method. We used the k-ε turbulence mode to find the results of the variables of interest in seven climate records on a given day. The velocity of the inlet flow of the air-H2O mixture was varied through the Reynolds number (Re) from 500 to 10000. The outdoor weather conditions considered were… More >

  • Open Access

    ARTICLE

    Terminal Sliding Mode Controllers for Hydraulic Turbine Governing System with Bifurcated Penstocks under Input Saturation

    Ji Liang1, Zhihuan Chen2,*, Xiaohui Yuan1,3,*, Binqiao Zhang3, Yanbin Yuan4
    CMES-Computer Modeling in Engineering & Sciences, Vol.123, No.2, pp. 603-629, 2020, DOI:10.32604/cmes.2020.09328
    Abstract Terminal sliding mode controller method is introduced to enhance the regulation performance of the hydraulic turbine governing system (HTGS). For the purpose of describing the characteristics of controlled system and deducing the control rule, a nonlinear mathematic model of hydraulic turbine governing system with bifurcated penstocks (HTGSBF) under control input saturation is established, and the input/output state linearization feedback approach is used to obtain the relationship between turbine speed and controller output. To address the control input saturation problem, an adaptive assistant system is designed to compensate for controller truncation. Numerical simulations have been conducted under fixed point stabilization and… More >

  • Open Access

    ARTICLE

    Machine Learning Model Comparison for Automatic Segmentation of Intracoronary Optical Coherence Tomography and Plaque Cap Thickness Quantification

    Caining Zhang1, Xiaopeng Guo2, Xiaoya Guo3, David Molony4, Huaguang Li2, Habib Samady4, Don P. Giddens4,5, Lambros Athanasiou6, Dalin Tang1*,7, Rencan Nie2,*, Jinde Cao8
    CMES-Computer Modeling in Engineering & Sciences, Vol.123, No.2, pp. 631-646, 2020, DOI:10.32604/cmes.2020.09718
    Abstract Optical coherence tomography (OCT) is a new intravascular imaging technique with high resolution and could provide accurate morphological infor￾mation for plaques in coronary arteries. However, its segmentation is still com￾monly performed manually by experts which is time-consuming. The aim of this study was to develop automatic techniques to characterize plaque components and quantify plaque cap thickness using 3 machine learning methods including convolutional neural network (CNN) with U-Net architecture, CNN with Fully convolutional DenseNet (FC-DenseNet) architecture and support vector machine (SVM). In vivo OCT and intravascular ultrasound (IVUS) images were acquired from two patients at Emory University with informed consent… More >

  • Open Access

    ARTICLE

    Building Information Modeling-Based Secondary Development System for 3D Modeling of Underground Pipelines

    Jun Chen1, *, Rao Hu2, Xianfeng Guo3, Feng Wu2
    CMES-Computer Modeling in Engineering & Sciences, Vol.123, No.2, pp. 647-660, 2020, DOI:10.32604/cmes.2020.09180
    (This article belongs to this Special Issue: Security Enhancement of Image Recognition System in IoT based Smart Cities)
    Abstract Underground pipeline networks constitute a major component of urban infrastructure, and thus, it is imperative to have an efficient mechanism to manage them. This study introduces a secondary development system to efficiently model underground pipeline networks, using the building information modeling (BIM)-based software Revit. The system comprises separate pipe point and tubulation models. Using a Revit application programming interface (API), the spatial position and attribute data of the pipe points are extracted from a pipeline database, and the corresponding tubulation data are extracted from a tubulation database. Using the Family class in Revit API, the cluster in the self-built library… More >

  • Open Access

    ARTICLE

    Comparison between the Seismic Performance of Buried Pipes and Pipes in a Utility Tunnel

    Wei Liu1, 2, *, Qianxiang Wu2
    CMES-Computer Modeling in Engineering & Sciences, Vol.123, No.2, pp. 661-690, 2020, DOI:10.32604/cmes.2020.07764
    (This article belongs to this Special Issue: Numerical Modeling and Simulation for Structural Safety and Disaster Mitigation)
    Abstract A utility tunnel system consists of pipes and ancillary facilities. In this paper, a finite element model of a concrete utility tunnel with pipes inside is established. Several tunnel segments were built to simulate a real utility tunnel, while the pipe was fixed by springs on the brackets in the utility tunnel. Using the discrete soil spring element to simulate the soil-structure interaction, actual earthquake records were adopted as excitation to analyze the seismic responses of pipes in a utility tunnel. Moreover, the influences of different parameters, including soil type, earthquake records, and field apparent wave velocity on the seismic… More >

  • Open Access

    ARTICLE

    Collapse Simulation and Response Assessment of a Large Cooling Tower Subjected to Strong Earthquake Ground Motions

    Tiancan Huang1, Hao Zhou2,*, Hamid Beiraghi3
    CMES-Computer Modeling in Engineering & Sciences, Vol.123, No.2, pp. 691-715, 2020, DOI:10.32604/cmes.2020.09046
    (This article belongs to this Special Issue: Numerical Modeling and Simulation for Structural Safety and Disaster Mitigation)
    Abstract Large cooling towers in thermal power plants and nuclear power plants are likely to suffer from strong earthquakes during service periods. The resulting destructions of the cooling towers would endanger the power plants and threaten the security of the related areas. It is important to use effective means to evaluate the safety status of the cooling towers and guide further precautions as well as retrofitting efforts. This paper is therefore focused on an elaborate numerical investigation to the earthquake-induced collapses of a large cooling tower structure. A complete numerical work for simulation of material failure, component fracture, structural buckling and… More >

  • Open Access

    ARTICLE

    Identification of the Discrete Element Model Parameters for Rock-Like Brittle Materials

    Rui Chen1, 2, Yong Wang1, 2, Ruitao Peng1, 2, *, Shengqiang Jiang1, 2, Congfang Hu1, 2, Ziheng Zhao1, 2
    CMES-Computer Modeling in Engineering & Sciences, Vol.123, No.2, pp. 717-737, 2020, DOI:10.32604/cmes.2020.07438
    (This article belongs to this Special Issue: Numerical Modeling and Simulation for Structural Safety and Disaster Mitigation)
    Abstract An inverse method for parameters identification of discrete element model combined with experiment is proposed. The inverse problem of parameter identification is transmitted to solve an optimization problem by minimizing the distance between the numerical calculations and experiment responses. In this method, the discrete element method is employed as numerical calculator for the forward problem. Then, the orthogonal experiment design with range analysis was used to carry out parameters sensitivity analysis. In addition, to improve the computational efficiency, the approximate model technique is used to replace the actual computational model. The intergeneration projection genetic algorithm (IP-GA) is employed as the… More >

  • Open Access

    ARTICLE

    An ADI Finite Volume Element Method for a Viscous Wave Equation with Variable Coefficients

    Mengya Su1, Zhihao Ren1, Zhiyue Zhang1, *
    CMES-Computer Modeling in Engineering & Sciences, Vol.123, No.2, pp. 739-776, 2020, DOI:10.32604/cmes.2020.08563
    (This article belongs to this Special Issue: Numerical Methods for Differential and Integral Equations)
    Abstract Based on rectangular partition and bilinear interpolation, we construct an alternating-direction implicit (ADI) finite volume element method, which combined the merits of finite volume element method and alternating direction implicit method to solve a viscous wave equation with variable coefficients. This paper presents a general procedure to construct the alternating-direction implicit finite volume element method and gives computational schemes. Optimal error estimate in L2 norm is obtained for the schemes. Compared with the finite volume element method of the same convergence order, our method is more effective in terms of running time with the increasing of the computing scale. Numerical… More >

  • Open Access

    ARTICLE

    A Discrete Model of TB Dynamics in Khyber Pakhtunkhwa-Pakistan

    Muhammad Altaf Khan1,*, Khanadan Khan2, Mohammad A. Safi3, Mahmoud H. DarAssi4
    CMES-Computer Modeling in Engineering & Sciences, Vol.123, No.2, pp. 777-795, 2020, DOI:10.32604/cmes.2020.08208
    (This article belongs to this Special Issue: Numerical Methods for Differential and Integral Equations)
    Abstract The present paper investigates the theoretical analysis of the tuberculosis (TB) model in the discrete-time case. The model is parameterized by the TB infection cases in the Pakistani province of Khyber Pakhtunkhwa between 2002 and 2017. The model is parameterized and the basic reproduction number is obtained and it is found R0 ¼ 1:5853. The stability analysis for the model is presented and it is shown that the discrete-time tuberculosis model is stable at the disease-free equilibrium whenever R0 < 1 and further we establish the results for the endemic equilibria and prove that the model is globally asymptotically stable… More >

  • Open Access

    ARTICLE

    RBF-FD Method for Some Dispersive Wave Equations and Their Eventual Periodicity

    Marjan Uddin1,*, Hameed Ullah Jan1,*, Muhammad Usman2
    CMES-Computer Modeling in Engineering & Sciences, Vol.123, No.2, pp. 797-819, 2020, DOI:10.32604/cmes.2020.08717
    (This article belongs to this Special Issue: Numerical Methods for Differential and Integral Equations)
    Abstract In this paper, we approximate the solution and also discuss the periodic behavior termed as eventual periodicity of solutions of (IBVPs) for some dispersive wave equations on a bounded domain corresponding to periodic forcing. The constructed numerical scheme is based on radial kernels and local in nature like finite difference method. The temporal variable is executed through RK4 scheme. Due to the local nature and sparse differentiation matrices our numerical scheme efficiently recovers the solution. The results achieved are validated and examined with other methods accessible in the literature. More >

  • Open Access

    ARTICLE

    T-Splines for Isogeometric Analysis of Two-Dimensional Nonlinear Problems

    Mayi Guo, Gang Zhao, Wei Wang*, Xiaoxiao Du, Ran Zhang, Jiaming Yang
    CMES-Computer Modeling in Engineering & Sciences, Vol.123, No.2, pp. 821-843, 2020, DOI:10.32604/cmes.2020.09898
    (This article belongs to this Special Issue: Recent Developments of Isogeometric Analysis and its Applications in Structural Optimization)
    Abstract Nonlinear behaviors are commonplace in many complex engineering applications, e.g., metal forming, vehicle crash test and so on. This paper focuses on the T-spline based isogeometric analysis of two-dimensional nonlinear problems including general large deformation hyperelastic problems and small deformation elastoplastic problems, to reveal the advantages of local refinement property of T-splines in describing nonlinear behavior of materials. By applying the adaptive refinement capability of T-splines during the iteration process of analysis, the numerical simulation accuracy of the nonlinear model could be increased dramatically. The Bézier extraction of the T-splines provides an element structure for isogeometric analysis that can be… More >

  • Open Access

    ARTICLE

    Extracting Sub-Networks from Brain Functional Network Using Graph Regularized Nonnegative Matrix Factorization

    Zhuqing Jiao1, *, Yixin Ji1, Tingxuan Jiao1, Shuihua Wang2, *
    CMES-Computer Modeling in Engineering & Sciences, Vol.123, No.2, pp. 845-871, 2020, DOI:10.32604/cmes.2020.08999
    (This article belongs to this Special Issue: Recent Advances on Deep Learning for Medical Signal Analysis (RADLMSA))
    Abstract Currently, functional connectomes constructed from neuroimaging data have emerged as a powerful tool in identifying brain disorders. If one brain disease just manifests as some cognitive dysfunction, it means that the disease may affect some local connectivity in the brain functional network. That is, there are functional abnormalities in the sub-network. Therefore, it is crucial to accurately identify them in pathological diagnosis. To solve these problems, we proposed a sub-network extraction method based on graph regularization nonnegative matrix factorization (GNMF). The dynamic functional networks of normal subjects and early mild cognitive impairment (eMCI) subjects were vectorized and the functional connection… More >

  • Open Access

    ARTICLE

    Geophysical and Production Data History Matching Based on Ensemble Smoother with Multiple Data Assimilation

    Zelong Wang1, 2, 3, *, Xiangui Liu1, 2, 3, Haifa Tang3, Zhikai Lv3, Qunming Liu3
    CMES-Computer Modeling in Engineering & Sciences, Vol.123, No.2, pp. 873-893, 2020, DOI:10.32604/cmes.2020.08993
    (This article belongs to this Special Issue: Advances in Modeling and Simulation of Complex Heat Transfer and Fluid Flow)
    Abstract The Ensemble Kalman Filter (EnKF), as the most popular sequential data assimilation algorithm for history matching, has the intrinsic problem of high computational cost and the potential inconsistency of state variables updated at each loop of data assimilation and its corresponding reservoir simulated result. This problem forbids the reservoir engineers to make the best use of the 4D seismic data, which provides valuable information about the fluid change inside the reservoir. Moreover, only matching the production data in the past is not enough to accurately forecast the future, and the development plan based on the false forecast is very likely… More >

  • Open Access

    ARTICLE

    Thermal Modeling and Analysis of Metal Foam Heat Sink with Thermal Equilibrium and Non-Equilibrium Models

    Yongtong Li1, Liang Gong1, *, Hui Lu1, Dexin Zhang1, Bin Ding1
    CMES-Computer Modeling in Engineering & Sciences, Vol.123, No.2, pp. 895-912, 2020, DOI:10.32604/cmes.2020.09009
    (This article belongs to this Special Issue: Advances in Modeling and Simulation of Complex Heat Transfer and Fluid Flow)
    Abstract In the present study, the thermal performance of metal foam heat sink was numerically investigated by adopting the local thermal non-equilibrium (LTNE) model and local thermal equilibrium (LTE) model. Temperature field distributions and temperature difference field distributions of solid and fluid phases were presented. Detailed thermal performance comparisons based on the LTE and LTNE models were evaluated by considering the effects of the relevant metal foam morphological and channel geometrical parameters. Results indicate that a distinct temperature difference exists between the solid and fluid phases when the LTNE effect is pronounced. The average Nusselt numbers predicted by both the LTE… More >

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