Sanjay K. Sharma¹, V. R. Kalamkar^{1, *}

CMES-Computer Modeling in Engineering & Sciences, Vol.114, No.3, pp. 295-319, 2018, DOI:10.3970/cmes.2018.114.295

Abstract The three-dimensional numerical investigation of an incompressible flow through rib roughened solar air heater is carried out. A combination of thin transverse and truncated ribs is attached on the absorber plate to study its effect on the heat transfer and friction factor. The parameters in the form of Reynolds number (Re) of 4000-16000, relative roughness pitch (P/e) of 8-18 and relative roughness height (e/Dh) of 0.0366-0.055 is considered for the analysis. The CFD code ANSYS FLUENT is used to solve the governing equations of turbulent flow. The RNG k–ε turbulence model is used to solve the transport equations with enhanced… More >

Haijian Shao^{1, 2}, Xing Deng^{1, 2, *}

CMES-Computer Modeling in Engineering & Sciences, Vol.114, No.3, pp. 277-293, 2018, DOI:10.3970/cmes.2018.114.277

Abstract High accurary in wind speed forcasting remains hard to achieve due to wind’s random distribution nature and its seasonal characteristics. Randomness, intermittent and nonstationary usually cause the portion problem of the wind speed forecasting. Seasonal characteristics of wind speed means that its feature distribution is inconsistent. This typically results that the persistence of excitation for modeling can not be guaranteed, and may severely reduce the possibilities of high precise forecasting model. In this paper, we proposed two effective solutions to solve the problems caused by the randomness and seasonal characteristics of the wind speed. (1) Wavelet analysis is used to… More >

Kuntao Ye^1,*, Yan Luo¹, Yingtao Jiang^2,*

CMES-Computer Modeling in Engineering & Sciences, Vol.114, No.3, pp. 261-276, 2018, DOI:10.3970/cmes.2018.114.261

Abstract Torsional micromirror devices have been widely used in micro displays, RF switches, optical communications, and optical coherence tomography systems. In order to study the stability of electrostatically driven torsional micromirror system with double bottom plates and two voltage sources, a dimensionless, two degrees of freedom (2-DoF) dynamic model was constructed. Governed by the dimensionless phase space model equation, the pull-in and bifurcation phenomena were analyzed using the Hamiltonian method and numerical simulation. In particular, the influence of the damping coefficient and the torsion-bending coupling effect on the phase trajectory was investigated. Furthermore, the conditions that can lead to pull-in were… More >

Longling Fan^1,*, Jing Yao ^{2, *}, Chun Yang³, Di Xu², Dalin Tang^{1, 4, §}

CMES-Computer Modeling in Engineering & Sciences, Vol.114, No.2, pp. 221-237, 2018, DOI:10.3970/cmes.2018.114.221

Abstract Understanding cardiac blood flow behaviors is of importance for cardiovascular research and clinical assessment of ventricle functions. Patient-specific Echo-based left ventricle (LV) fluid-structure interaction (FSI) models were introduced to perform ventricle mechanical analysis, investigate flow behaviors, and evaluate the impact of myocardial infarction (MI) and hypertension on blood flow in the LV. Echo image data were acquired from 3 patients with consent obtained: one healthy volunteer (P1), one hypertension patient (P2), and one patient who had an inferior and posterior myocardial infarction (P3). The nonlinear Mooney-Rivlin model was used for ventricle tissue with material parameter values chosen to match echo-measure… More >

Kaito Watanabe¹, Masaki Izawa¹, Ayumi Takahashi¹, Kazuhito Misaji^1,*

CMES-Computer Modeling in Engineering & Sciences, Vol.114, No.2, pp. 191-207, 2018, DOI:10.3970/cmes.2018.114.191

Abstract Under the aim of finding effective rehabilitation solutions, the difference between the extents of fatigue of each muscle used in different motions are compared. Previous research suggested methods for estimating muscle torque and muscle tension on the basis of a musculoskeletal model. As a result, it has become possible to quantitatively identify the extent of fatigue in each muscle during motion. Therefore, to evaluate muscle fatigue more quantitatively, driving power and angular momentum are focused on. Based on the driving torque of joints and the muscle torque calculated by using a three-dimensional musculoskeletal model, a method for calculating the driving… More >

Marziyeh Eftekhari¹, Omid Vahidi^1,*

CMES-Computer Modeling in Engineering & Sciences, Vol.114, No.2, pp. 153-171, 2018, DOI:10.3970/cmes.2018.114.153

Abstract Various drugs are used to maintain normoglycemia in subjects with type 2 diabetes mellitus. The combination of the drugs from different classes in one single tablet may enhance the effectiveness of the anti-diabetic drugs. To investigate the impact of combining drugs on the glucose regulation of subjects with type 2 diabetes, we propose a pharmacokinetic/pharmacodynamics (PK/PD) mathematical modeling approach for a combination of metformin and vildagliptin drugs. In the proposed modeling approach, two separate PK models representing oral administration of metformin and vildagliptin for diabetic subjects are interconnected to a PD model comprising a detailed compartmental physiological model representing the… More >

Dongkai Shen^1,2,+, Qian Zhang¹, Yixuan Wang^1,*, Huiqing Ge^3,*, Zujin Luo^4,+

CMES-Computer Modeling in Engineering & Sciences, Vol.114, No.2, pp. 117-139, 2018, DOI:10.3970/cmes.2018.114.117

Abstract A pressure controlled mechanical ventilator with an automatic secretion clearance function can improve secretion clearance safely and efficiently. Studies on secretion clearance by pressure controlled systems show that these are suited for clinical applications. However, these studies are based on a single lung electric model and neglect the coupling between the two lungs. The research methods applied are too complex for the analysis of a multi-parameter system. In order to understand the functioning of the human respiratory system, this paper develops a dimensionless mathematical model of double-lung mechanical ventilation system with a secretion clearance function. An experiment is designed to… More >

Chengquan Wang¹, Yonggang Shen^2,*, Yun Zou¹, Tianqi Li¹, Xiaoping Feng¹

CMES-Computer Modeling in Engineering & Sciences, Vol.114, No.1, pp. 75-93, 2018, DOI:10.3970/cmes.2018.114.075

Abstract The failure behavior of the precast prestressed concrete T girder was investigated by destructive test and finite-element analysis, and the mid-span deflection, girder stiffness and the variation of the cross section strain in the loading process were obtained, and the mechanical properties, mechanical behavior, elastic and plastic behavior and ultimate bearing capacity of T girder with large span were revealed. Furthermore, the relationship between the beam stiffness degradation, the neutral axis in cross-section, steel yielding and concrete cracking are investigated and analyzed. A method was proposed to predict the residual bearing capacity of a bridge based on the variation of… More >

Qiang Tong¹, Qingwen Ren^{1, *}, Lei Shen ², Linfei Zhang ², Yin Yang³

CMES-Computer Modeling in Engineering & Sciences, Vol.114, No.1, pp. 33-58, 2018, DOI:10.3970/cmes.2018.114.033

Abstract In this article, the post-peak softening stage of the constitutive relation and the elastic stiffness degradation of concrete are investigated, and a highly reasonable constitutive relation curve is proposed. At the material level, the energy change in the concrete failure process is studied based on the different stress-strain curves of concrete under uniaxial tension and compression. The concrete failure criterion based on elastic strain energy density is deemed suitable and consistent with the experimental phenomena. The hysteresis phenomenon (lags behind the peak strength) is also discussed. At the structure level, the strength reduction method is employed for the stability analysis,… More >

Lihua Wang^1,*, Zheng Zhong¹

CMES-Computer Modeling in Engineering & Sciences, Vol.114, No.1, pp. 1-18, 2018, DOI:10.3970/cmes.2018.114.001

Abstract A semi-analytical form of complex modal analysis is proposed for the time-variant dynamical problem of rotating pipe conveying fluid system. The complex mode superposition method is introduced for the dynamic analysis in the time and frequency domains, in which appropriate orthogonality conditions are constructed to decouple the time-variant equation of motion. Consequently, complex frequencies and modes of vibration are analytically formulated and the variations of frequencies and damping of the system are evaluated. Numerical time-variant example of rotating pipe conveying fluid illustrates the effectiveness and accuracy of this method. Furthermore, the proposed solution scheme is also applicable to other similar… More >