Renyong Zhang

The International Conference on Computational & Experimental Engineering and Sciences, Vol.21, No.2, pp. 22-24, 2019, DOI:10.32604/icces.2019.04656

Abstract This article aims to give a method for the fast numerical computation and continuation of families of periodic orbits in the strong nonlinear circular restricted three-body problem, and we focus our attention on those in the Earth-moon system. This work is primarily motivated by a series of missions and plans that take advantages of the three-body periodic orbits associated with the collinear equilibrium points, L1, L2 and L3 or two gravitational celestial bodies. We describe the method used that allows to follow individual families of periodic orbits by numerical continuation, which based on Jacobi energy surface, of strong nonlinear equations.… More >

Purnendu, Soumitra Satapathi^*

Journal of Renewable Materials, Vol.5, No.2, pp. 96-102, 2017, DOI:10.7569/JRM.2016.634134

Abstract Graphene-based 3D porous xerogel was designed through molecular self-assembly of graphene oxide on chitosan matrix and its application in removal of different heavy metal ions from wastewater was investigated. The synthesized xerogel was characterized through FTIR, SEM, XRD and BET surface area analysis. Heavy metal ions, including Pb(II), Cd(II), and Hg(II), were removed from wastewater using this graphene-chitosan (GO-Cs) xerogel and the removal efficiency was monitored through inductively coupled plasma mass spectrometry (ICP-MS). The effect of GO-Cs composition and pH on adsorption efficiency as well as the kinetics of adsorption was studied in detail. The study exhibited that this xerogel… More >

Abha Dubey^1*, Anuradha Mishra²

Journal of Renewable Materials, Vol.5, No.1, pp. 54-61, 2017, DOI:10.7569/JRM.2016.634127

Abstract Biosorption effectively removes heavy metal ions by using inexpensive biosorbents. In this study, Portulaca oleracea plant waste biomass was used as environmentally friendly biosorbent for the removal of copper ions from aqueous solution. This article includes the study of the effects of various important parameters on the biosorption process. Maximum biosorption was found to occur under slightly acidic conditions (pH 6). Small particle size, moderate agitation speed, and moderate temperature favor the biosorption process. The Langmuir model was most suitable, showing the biosorption capacity to be 85.470 mg/g. Pseudo-secondorder model best described the kinetics of the biosorption process. Thermodynamic studies… More >

Anusha Eldo¹, Balamati Choudhury²

CMC-Computers, Materials & Continua, Vol.52, No.3, pp. 143-157, 2016, DOI:10.3970/cmc.2016.052.142

Abstract The advances in metamaterial science and technology have raised the expectations of camouflage or stealth researchers to one order higher in terms of absorption characteristics. As metamaterial inspired radar absorbing structures are proving themselves as a good candidate with near unity absorption, feasibility towards hardware realization is necessary. Hence an extensive literature survey of metamaterial inspired radar absorbing structure has been carried out and reported in this paper along with the challenges and material issues. The various types of metamaterial structures that can be used as absorber have been provided along with simulation figures. To make the review more useful,… More >

Qianxin Wang^1,2,3, Chao Hu^1,2,*, Ya Mao^1,2

CMES-Computer Modeling in Engineering & Sciences, Vol.117, No.3, pp. 509-525, 2018, DOI:10.31614/cmes.2018.04098

Abstract Designing the optimal distribution of Global Navigation Satellite System (GNSS) ground stations is crucial for determining the satellite orbit, satellite clock and Earth Rotation Parameters (ERP) at a desired precision using a limited number of stations. In this work, a new criterion for the optimal GNSS station distribution for orbit and ERP determination is proposed, named the minimum Orbit and ERP Dilution of Precision Factor (OEDOP) criterion. To quickly identify the specific station locations for the optimal station distribution on a map, a method for the rapid determination of the selected station locations is developed, which is based on the… More >

Xiaoli Bai¹, John L. Junkins²

CMES-Computer Modeling in Engineering & Sciences, Vol.111, No.2, pp. 129-146, 2016, DOI:10.3970/cmes.2016.111.129

Abstract This paper presents Modified Chebyshev-Picard Iteration (MCPI) methods for long-term integration of the coupled orbit and attitude dynamics. Although most orbit predictions for operational satellites have assumed that the attitude dynamics is decoupled from the orbit dynamics, the fully coupled dynamics is required for the solutions of uncontrolled space debris and space objects with high area-to-mass ratio, for which cross sectional area is constantly changing leading to significant change on the solar radiation pressure and atmospheric drag. MCPI is a set of methods for solution of initial value problems and boundary value problems. The methods refine an orthogonal function approximation… More >

J.L. Read¹, A. Bani Younes², J.L. Junkins³

CMES-Computer Modeling in Engineering & Sciences, Vol.111, No.1, pp. 65-81, 2016, DOI:10.3970/cmes.2016.111.065

Abstract This paper focuses on propagating perturbed two-body motion using orbital elements combined with a novel integration technique. While previous studies show that Modified Chebyshev Picard Iteration (MCPI) is a powerful tool used to propagate position and velocity, the present results show that using orbital elements to propagate the state vector reduces the number of MCPI iterations and nodes required, which is especially useful for reducing the computation time when including computationally-intensive calculations such as Spherical Harmonic gravity, and it also converges for > 5.5x as many revolutions using a single segment when compared with cartesian propagation. Results for the Classical… More >

B. Macomber¹, A. B. Probe¹, R. Woollands¹, J. Read¹, J. L. Junkins¹

CMES-Computer Modeling in Engineering & Sciences, Vol.111, No.1, pp. 29-64, 2016, DOI:10.3970/cmes.2016.111.029

Abstract Modified Chebyshev Picard Iteration is an iterative numerical method for solving linear or non-linear ordinary differential equations. In a serial computational environment the method has been shown to compete with, or outperform, current state of practice numerical integrators. This paper presents several improvements to the basic method, designed to further increase the computational efficiency of solving the equations of perturbed orbit propagation. More >

Darin Koblick^1,2,3, Shujing Xu⁴, Joshua Fogel⁵, Praveen Shankar¹

CMES-Computer Modeling in Engineering & Sciences, Vol.111, No.1, pp. 1-27, 2016, DOI:10.3970/cmes.2016.111.001

Abstract The Modified Picard-Chebyshev Method (MPCM) is implemented as an orbit propagation solver for a numerical optimization method that determines minimum time orbit transfer trajectory of a satellite using a series of multiple impulses at intermediate waypoints. The waypoints correspond to instantaneous impulses that are determined using a nonlinear constrained optimization routine, SNOPT with numerical force models for both Two-Body and J2 perturbations. It is found that using the MPCM increases run-time performance of the discretized lowthrust optimization method when compared to other sequential numerical solvers, such as Adams-Bashforth-Moulton and Gauss-Jackson 8th order methods. More >

A. Brancati¹, M. H. Aliabadi¹, A. Milazzo²

CMES-Computer Modeling in Engineering & Sciences, Vol.78, No.1, pp. 1-24, 2011, DOI:10.3970/cmes.2011.078.001

Abstract This paper presents an improved adaptive cross approximation (ACA) approach developed in conjunction with the Hierarchical format matrix and the GMRES solver. A novel scheme to generate the cluster tree (based upon preliminary considerations of the prescribed boundary conditions) and an improved ACA algorithm (approximating the system matrix for mixed Robin conditions) are described. The asymptotic smoothness property of a kernel generated by a linear combination of two asymptotic smooth kernels is demonstrated. Numerical results show the new approach to be up to 50% faster than the conventional ACA approach. More >