Wei Chen, Nan Qiu^*, Xusheng Yang

Energy Engineering, Vol.121, No.4, pp. 987-1005, 2024, DOI:10.32604/ee.2023.045475

Abstract During the operation of a DC microgrid, the nonlinearity and low damping characteristics of the DC bus make it prone to oscillatory instability. In this paper, we first establish a discrete nonlinear system dynamic model of a DC microgrid, study the effects of the converter sag coefficient, input voltage, and load resistance on the microgrid stability, and reveal the oscillation mechanism of a DC microgrid caused by a single source. Then, a DC microgrid stability analysis method based on the combination of bifurcation and strobe is used to analyze how the aforementioned parameters influence the oscillation characteristics of the system.… More >

Diego Angeli^a,*, Arturo Pagano^b, Mauro A. Corticelli^a, Alberto Fichera^b, Giovanni S. Barozzi^a

Frontiers in Heat and Mass Transfer, Vol.2, No.2, pp. 1-9, 2011, DOI:10.5098/hmt.v2.2.3003

Abstract A numerical analysis of transitional natural convection from a confined thermal source is presented. The system considered is an air-filled, square-sectioned 2D enclosure containing a horizontal heated cylinder. The resulting flow is investigated with respect to the variation of the Rayleigh number, for three values of the aspect ratio A. The first bifurcation of the low-Ra fixed-point solution is tracked for each A-value. Chaotic flow features are detailed for the case A = 2.5. The supercritical behaviour of the system is investigated using nonlinear analysis tools and phase-space representations, and the effect of the flow on heat transfer is discussed. More >

Yang Liu^1,*, Luis Dorfmann²

The International Conference on Computational & Experimental Engineering and Sciences, Vol.27, No.4, pp. 1-1, 2023, DOI:10.32604/icces.2023.09499

Abstract In this talk, we present some analytical results concerning localized instabilities in stretched soft cylinders with residual-stress effect. Within the framework of finite elasticity, a bifurcation analysis is carried out based on the incremental theory. It is found that with the residual stress effect taken into consideration additional singularities of the incremental equations appear. To overcome this difficulty we apply the Stroh formulism and an expansion methodology and derive a bifurcation condition. Then we consider three loading scenarios and perform a detailed analysis of the bifurcation behaviors. It turns out that the zero mode, giving rise to localization, is always… More >

Dongmei Huang¹, Dang Hong², Wei Li^1,*, Guidong Yang¹, Vesna Rajic³

CMES-Computer Modeling in Engineering & Sciences, Vol.138, No.1, pp. 509-524, 2024, DOI:10.32604/cmes.2023.029215

Abstract In this paper, the bifurcation properties of the vibro-impact systems with an uncertain parameter under the impulse and harmonic excitations are investigated. Firstly, by means of the orthogonal polynomial approximation (OPA) method, the nonlinear damping and stiffness are expanded into the linear combination of the state variable. The condition for the appearance of the vibro-impact phenomenon is to be transformed based on the calculation of the mean value. Afterwards, the stochastic vibro-impact system can be turned into an equivalent high-dimensional deterministic non-smooth system. Two different Poincaré sections are chosen to analyze the bifurcation properties and the impact numbers are identified… More >

Quanfu Gao^a,b , Kun Zhang^a,b,*, Liang Bi Wang^a,b

Frontiers in Heat and Mass Transfer, Vol.14, pp. 1-10, 2020, DOI:10.5098/hmt.14.29

Abstract Detailed numerical analysis is presented for natural convection heat transfer in internally finned horizontal annuli. Governing equations are discretized using the finite volume method, and solved using SIMPLE algorithm with Quick scheme. The results show that the flow and heat transfer can reach steady state when the Rayleigh number is below 2×10⁴. When the Rayleigh number is greater than 3×10⁴ , two different types of numerical solutions under the same parameters can be obtained for different initial conditions. The critical Rayleigh numbers with two different initial conditions are different from steady to unsteady solutions. The oscillatory flow undergoes several bifurcations… More >

Mohamad Afendee Mohamed¹, Talal Bonny², Aceng Sambas³, Sundarapandian Vaidyanathan⁴, Wafaa Al Nassan², Sen Zhang⁵, Khaled Obaideen², Mustafa Mamat¹, Mohd Kamal Mohd Nawawi^6,*

CMC-Computers, Materials & Continua, Vol.75, No.3, pp. 5987-6006, 2023, DOI:10.32604/cmc.2023.035668

Abstract In recent years, there are numerous studies on chaotic systems with special equilibrium curves having various shapes such as circle, butterfly, heart and apple. This paper describes a new 3-D chaotic dynamical system with a capsule-shaped equilibrium curve. The proposed chaotic system has two quadratic, two cubic and two quartic nonlinear terms. It is noted that the proposed chaotic system has a hidden attractor since it has an infinite number of equilibrium points. It is also established that the proposed chaotic system exhibits multi-stability with two coexisting chaotic attractors for the same parameter values but differential initial states. A detailed… More >

Fahad Sameer Alshammari¹, Md Fazlul Hoque², Harun-Or-Roshid², Muhammad Nadeem^3,*

CMES-Computer Modeling in Engineering & Sciences, Vol.135, No.3, pp. 2197-2217, 2023, DOI:10.32604/cmes.2023.022301

Abstract We investigate the bounded travelling wave solutions of the Biswas-Arshed model (BAM) including the low group velocity dispersion and excluding the self-phase modulation. We integrate the nonlinear structure of the model to obtain bounded optical solitons which pass through the optical fibers in the non-Kerr media. The bifurcation technique of the dynamical system is used to achieve the parameter bifurcation sets and split the parameter space into various areas which correspond to different phase portraits. All bounded optical solitons and bounded periodic wave solutions are identified and derived conforming to each region of these phase portraits. We also apply the… More >

S. Hanis^*

Intelligent Automation & Soft Computing, Vol.36, No.1, pp. 865-878, 2023, DOI:10.32604/iasc.2023.030597

Abstract In the recent past, the storage of images and data in the cloud has shown rapid growth due to the tremendous usage of multimedia applications. In this paper, a modulated version of the Ikeda map and key generation algorithm are proposed, which can be used as a chaotic key for securely storing images in the cloud. The distinctive feature of the proposed map is that it is hyperchaotic, highly sensitive to initial conditions, and depicts chaos over a wide range of control parameter variations. These properties prevent the attacker from detecting and extracting the keys easily. The key generation algorithm… More >

Anupam Krishnan¹, Anjana P. Anantharaman^2,*

Molecular & Cellular Biomechanics, Vol.19, No.2, pp. 77-88, 2022, DOI:10.32604/mcb.2022.018369

Abstract Computational Fluid Dynamics has become relevant in the study of hemodynamics, where clinical results are challenging to obtain. This paper discusses a 2-Dimensional transient blood flow analysis through an arterial bifurcation for patients infected with the Coronavirus. The geometry considered is an arterial bifurcation with main stem diameter 3 mm and two outlets. The left outlet (smaller) has a diameter of 1.5 mm and the right outlet (larger), 2 mm. The length of the main stem, left branch and right branch are fixed at 35 mm, 20 mm and 25 mm respectively. Viscosity change that occurs in the blood leads… More >

Haoyu Wan, Heng Zhang, Zhizhu He^*

FDMP-Fluid Dynamics & Materials Processing, Vol.17, No.3, pp. 639-651, 2021, DOI:10.32604/fdmp.2021.012106

Abstract Treating coronary bifurcation stenosis is still a challenging task. Existing procedures still display a relatively small rate of success. This paper aims to investigate numerically the effect of bifurcation lesions with different structures on the dynamics of blood flow and related temperature. The problem geometry is parametrically varied by changing the bifurcation angle and radius. A finite volume method is used to simulate the three-dimensional flow. The effects induced by the structure of the stenosis, the artery bifurcation angle and radius, and the inlet velocity of blood are discussed in terms of flow pattern, pressure distribution, and shear stress at… More >