RAJEEV KUMAR

Journal of Polymer Materials, Vol.37, No.3-4, pp. 131-142, 2020, DOI:10.32381/JPM.2020.37.3-4.2

Abstract The optical, electrical and acoustical properties of a polymer solution based on polyvinyl pyrrolidone (PVP) doped with different concentration of cupric sulphate (CuSO₄ ) were studied.UVVIS spectroscopy results reflected that absorption increases in asymmetric manner and the absorption peak showed red shift with increasing Cu ions concentration. The optical band gap (direct and indirect) was found to decrease with increase in Cu ions concentration in the polymer due to increase in the density of localized states in the band-gap.The value of Urbach energy is also evaluated from the transmission spectra and the activation energies are also evaluated from the conductivity… More >

Ehsan Alibagheri¹, Bohayra Mortazavi², Timon Rabczuk^3,4,*

CMC-Computers, Materials & Continua, Vol.67, No.1, pp. 1287-1300, 2021, DOI:10.32604/cmc.2021.013564

Abstract Machine-learning (ML) models are novel and robust tools to establish structure-to-property connection on the basis of computationally expensive ab-initio datasets. For advanced technologies, predicting novel materials and identifying their specification are critical issues. Two-dimensional (2D) materials are currently a rapidly growing class which show highly desirable properties for diverse advanced technologies. In this work, our objective is to search for desirable properties, such as the electronic band gap and total energy, among others, for which the accelerated prediction is highly appealing, prior to conducting accurate theoretical and experimental investigations. Among all available componential methods, gradient-boosted (GB) ML algorithms are known… More >

A.L. Chen, Y.S. Wang¹

The International Conference on Computational & Experimental Engineering and Sciences, Vol.5, No.4, pp. 239-244, 2008, DOI:10.3970/icces.2008.005.239

Abstract Band gaps and localization phenomenon for both in-plane and anti-plane elastic waves propagating in 2D ordered and disordered phononic crystals are studied in this paper. The localization of wave propagation due to random disorder is discussed by introducing the concept of the localization factor which is calculated by the plane-wave-based transfer-matrix method. More >

Mao Liu^1,2, Jiawei Xiang¹, Haifeng Gao¹, Yongying Jiang¹, Yuqing Zhou¹, Fengping Li¹

CMES-Computer Modeling in Engineering & Sciences, Vol.97, No.5, pp. 425-436, 2014, DOI:10.3970/cmes.2014.097.425

Abstract A wavelet finite element method (WFEM) is developed to analyze the dispersion relation for one-dimensional phononic crystals (1DPCs). In order to calculate the band gaps (BGs) of 1DPCs, the wavelet finite element model is constructed using a slender beam element based on B-spline wavelet on the interval (BSWI). Combining with the Bloch-Floquet theorem and ω(k) technique, the model will be simplified as a simple eigenproblem. The performance of the proposed method has been numerically verified by one numerical example. More >

Che-Wun Hong^1,2, Chia-Yun Tsai¹

CMES-Computer Modeling in Engineering & Sciences, Vol.67, No.2, pp. 79-94, 2010, DOI:10.3970/cmes.2010.067.079

Abstract This paper describes the quantum mechanical simulation on the photonic properties of group-III nitride clusters, whose bulk types are common materials for light emitting diodes (LEDs). In order to emit different colors of light using the same semiconductor materials, it is possible to vary the band gap by controlling the quantum dot sizes or doping a third atom theoretically. Density functional theory (DFT) calculations are performed to analyze a set of binary (GaN)_n (3≤n≤32) and ternary In_xGa_1-xN (0≤x≤0.375) clusters to study their photonic characteristics. The ground state structures are optimized to calculate the binding energies using the time-independent DFT. Then… More >