Jin Zhao¹, Zubair Ahmad^2,*, Zahra Almaspoor²

CMC-Computers, Materials & Continua, Vol.67, No.2, pp. 2111-2122, 2021, DOI:10.32604/cmc.2021.014259

Abstract The epidemic outbreak COVID-19 was first detected in the Wuhan city of China and then spread worldwide. It is of great interest to the researchers for its high rate of infection spread and its significant number of fatalities. A detailed scientific analysis of this phenomenon is yet to come. However, it is of interest of governments and other responsible institutions to have the right facts and figures to take every possible necessary action such as an arrangement of the appropriate quarantine activities, estimation of the required number of places in hospitals, assessment of the level of personal protection, and calculating… More >

Jin Zhao¹, Zubair Ahmad^2,*, Zahra Almaspoor², M. El-Morshedy^3,4, Ahmed Z. Afify⁵

CMC-Computers, Materials & Continua, Vol.67, No.1, pp. 965-977, 2021, DOI:10.32604/cmc.2021.014553

Abstract The current epidemic outbreak COVID-19 first took place in the Wuhan city of China and then spread worldwide. This deadly disease affected millions of people and compelled the governments and other concerned institutions to take serious actions. Around 0.28 million people have died from the COVID-19 outbreak as of May 11, 2020, 05:41 GMT, and the number is still increasing exponentially. The results of any scientific investigation of this phenomenon are still to come. However, now it is urgently needed to evaluate and compare the disease dynamics to improve the quarantine activities and the level of individual protection, to at… More >

Hamdy A. Ziedan¹, Hegazy Rezk^2,3, Mujahed Al-Dhaifallah^4,*

CMC-Computers, Materials & Continua, Vol.67, No.1, pp. 491-518, 2021, DOI:10.32604/cmc.2021.014493

Abstract A new accurate algorithms based on mathematical modeling of two parallel transmissions lines system (TPTLS) as influenced by the mutual effect to determine the fault location is discussed in this work. The distance relay measures the impedance to the fault location which is the positive-sequence. The principle of summation the positive-, negative-, and zero-sequence voltages which equal zero is used to determine the fault location on the TPTLS. Also, the impedance of the transmission line to the fault location is determined. These algorithms are applied to single-line-to-ground (SLG) and double-line-to-ground (DLG) faults. To detect the fault location along the transmission… More >

Tongjing Liu^{1, 2, *}, Weixia Liu³, Pengxiang Diwu⁴, Gaixing Hu^{5, 6}, Ting Xu^{1, 7}, Yuqi Li², Zhenjiang You⁸, Runwei Qiao², Jia Wang²

CMES-Computer Modeling in Engineering & Sciences, Vol.123, No.3, pp. 1205-1222, 2020, DOI:10.32604/cmes.2020.08961

Abstract Structure of porous media and fluid distribution in rocks can significantly affect the transport characteristics during the process of microscale tracer flow. To clarify the effect of micro heterogeneity on aqueous tracer transport, this paper demonstrates microscopic experiments at pore level and proposes an improved mathematical model for tracer transport. The visualization results show a faster tracer movement into movable water than it into bound water, and quicker occupancy in flowing pores than in storage pores caused by the difference of tracer velocity. Moreover, the proposed mathematical model includes the effects of bound water and flowing porosity by applying interstitial… 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 >

G. Prater, Jr.¹

CMES-Computer Modeling in Engineering & Sciences, Vol.3, No.3, pp. 299-312, 2002, DOI:10.3970/cmes.2002.003.299

Abstract A vapor compressor's performance is affected by pressure and mass flow fluctuations resulting from acoustic effects in the suction and discharge manifolds. Through proper geometric design of the manifolds, these pulsations can be modified to increase efficiency and reduce noise. This paper documents the development of a computer simulation program used to tune stationary-vane refrigeration compressors. The program models the mechanical, fluid, thermodynamic, kinematic, and acoustical processes occurring in such compressors, and calculates suction and discharge chamber pressures, mass flow rates, valve displacements, and acoustic input and transfer impedances. Experimental acoustic pressure measurements from a refrigerator test stand provide validation… More >

Chein-Shan Liu¹

CMES-Computer Modeling in Engineering & Sciences, Vol.38, No.1, pp. 25-38, 2008, DOI:10.3970/cmes.2008.038.025

Abstract In this paper a complex matrix operator and a complex field are used to express the Maxwell equations, of which the complex field embraces all field variables and the matrix operator embraces the time and space differential operators. By left applying the operator on the complex field one can get all the four Maxwell equations, which are usually expressed by the vector form. The new formulation matches the Lorenz gauge condition, and its mathematical advantage is that it can incorporate the Maxwell equations into a single equation. The introduction of four-potential is possible only under the Lorenz gauge. In terms… More >

Shishir Sinha¹, Praveen Ch.

CMES-Computer Modeling in Engineering & Sciences, Vol.32, No.2, pp. 85-102, 2008, DOI:10.3970/cmes.2008.032.085

Abstract Fluid catalytic cracking (FCC) unit plays most important role in the economy of a modern refinery that it is use for value addition to the refinery products. Because of the importance of FCC unit in refining, considerable effort has been done on the modeling of this unit for better understanding and improved productivity. The process is characterized by complex interactions among feed quality, catalyst properties, unit hardware parameters and process conditions. \newline The traditional and global approach of cracking kinetics is lumping. In the present paper, five lump kinetic scheme is considered, where gas oil crack to give lighter fractions… More >

D. Kourounis¹, L.N. Gergidis¹, A. Charalambopoulos¹

CMES-Computer Modeling in Engineering & Sciences, Vol.28, No.3, pp. 185-202, 2008, DOI:10.3970/cmes.2008.028.185

Abstract The sensitivity of analytical solutions of the direct acoustic scattering problem in prolate spheroidal geometry on the wavenumber and shape, is extensively investigated in this work. Using the well known Vekua transformation and the complete set of radiating "outwards'' eigensolutions of the Helmholtz equation, introduced in our previous work ([Charalambopoulos and Dassios(2002)], [Gergidis, Kourounis, Mavratzas, and Charalambopoulos (2007)]), the scattered field is expanded in terms of it, detouring so the standard spheroidal wave functions along with their inherent numerical deficiencies. An approach is employed for the determination of the expansion coefficients, which is optimal in the sense, that minimizes the… More >

L.N. Gergidis, D. Kourounis, S. Mavratzas, A. Charalambopoulos¹

CMES-Computer Modeling in Engineering & Sciences, Vol.21, No.2, pp. 157-176, 2007, DOI:10.3970/cmes.2007.021.157

Abstract A new complete set of scattering eigensolutions of Helmholtz equation in spheroidal geometry is constructed in this paper. It is based on the extension to exterior boundary value problems of the well known Vekua transformation pair, which connects the kernels of Laplace and Helmholtz operators. The derivation of this set is purely analytic. It avoids the implication of the spheroidal wave functions along with their accompanying numerical deficiencies. Using this novel set of eigensolutions, we solve the acoustic scattering problem from a soft acoustic spheroidal scatterer, by expanding the scattered field in terms of it. Two approaches concerning the determination… More >