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262 results on '"Ahmad, Nafis"'

11. Transitioning Universe with hybrid scalar field in Bianchi I space-time

Author

Yadav, Anil Kumar, Alshehri, A. M., Ahmad, Nafis, Goswami, G. K., and Kumar, Mukesh

Subjects
General Relativity and Quantum Cosmology
Abstract

In this paper we investigate a Bianchi type I transitioning Universe in Brans-Dicke theory. To get an explicit solution of the field equations, we assume scalar field as $\phi = \phi_{0}\left[t^{\alpha}exp(\beta t)\right]^{\delta}$ with $\phi_{0}$, $\alpha$, $\beta$ and $\delta$ as constants. The values of $\alpha$ and $\beta$ are obtained by probing the proposed model with recent observational Hubble data (OHD) points. The interacting and non-interacting scenarios between dark matter and dark energy of the derived Universe within the framework of Brans-Dicke gravity are investigated. The $om(z)$ analysis of the Universe in derived model shows that the Universe is filled with dynamical dark energy with its equation of state parameter $\omega_{de} > -1$. Hence the Universe behaves like a quintessence model at present epoch. Some physical properties of the Universe are also discussed., Comment: 11 pages, 9 figures

Published
2020
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12. Interacting Dark Sectors in Anisotropic Universe: Observational Constraints and $H_{0}$ Tension

Author

Amirhashchi, Hassan, Yadav, Anil Kumar, Ahmad, Nafis, and Yadav, Vikrant

Subjects
Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

The present study reveals observational constraints on the coupling between dark components of anisotropic Bianchi type I universe. We assume interaction between dark matter and dark energy and split the continuity equation with inclusion of interaction term $\Gamma$. Two scenarios have been considered (i) when coupling between dark components is constant and (ii) when it is a function of redshift ($z$). Metropolis-Hasting algorithm has been used to perform Monte Carlo Markov Chain (MCMC) analysis by using observational Hubble data obtained from cosmic chronometric (CC) technique, cosmic microwave background (CMB) baryon acoustic oscillation (BAO), Pantheon compilation of Supernovae type Ia (SNIa), their joint combination and a Gaussian prior on the Hubble parameter $H_{0}$. It is obtained that the combination of all databases plus $H_{0}$ prior marginalized over a present dark energy density gives stringent constraints on the current value of coupling as $-0.001<\delta<0.041$ in constant coupling model and $-0.042<\delta<0.053$ in varying coupling model at 68\% confident level. In general, for both models, we found $\omega^{X}\approx -1$ and $\delta(\delta_{0})\approx 0$ which indicate that still recent data favor uncoupled $\Lambda$CDM model. Our estimations show that in constant coupling model $(H_{0}=73.9^{+1.5}_{-0.95}, \delta=0.023^{+0.017}_{-0.024})$ which naturally leads to consistent value of the Hubble constant. This result is interesting because the previous works show that such a high value of Hubble constant requires the significant value of coupling parameter $\delta$. It has been also observed that in the constant coupling model, we do not find any disagreement between the estimated $H_{0}$ and those reported by Hubble space telescope (HST) and large scale structure (LSS) experiments., Comment: 11 pages, 21 figures

Published
2020

37. EFFECTIVENESS STUDIES OF THE LEARNING BASIC MATHEMATICAL OPERATIONS ON USERS USING EDUCATION GAMES WITH ESCALATING DIFFICULTY LEVEL IN SEVERAL TYPES OF GAMES

Author

Ari Mahardika Ahmad Nafis and Darlis Herumurti

Subjects
Information technology, T58.5-58.64
Abstract

Mathematic is basic but fundamental knowledge, but in fact many students do not have the motivation to learn it because they think mathematic is boring. Therefore, an innovation is needed to motivate students, one of them is by using an educational game. Racing, shooting and fighting games are the most popular types of games in 2019 according to InvisionCommunity. Shooting game is a genre that used a lot in the educational games for learning math, while racing game and fighting game are not used much for educational games. This research aims to develop and measure the effectiveness of the games from these three genre of games as a means of learning elementary arithmetic at the elementary school level. The effectiveness of an educational game can be observed from the increment in learning outcomes obtained after conducting an experiment. We can know the most effective type of game in this experiment by compare the improvement in learning outcomes after playing all three games. The comparative analysis will be carried out using ANOVA. In this research, we used data from 60 participant with elementary level of education between grade 1 to 3. The results were obtained by calculating the difference in the participants' initial scores obtained from before playing the game and participants’ final scores obtained after playing the educational game. The results show that educational racing games have the highest increase of 6.3% compared to shooter games with 3% increase or fighting games with increase of 4.3%.

Published
2020
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41. Exploring the Capabilities of Pristine B84 Nanocluster for Selective NO and N2O Gases Detection Involved to COVID-19: A DFT Analysis.

Author

Abbas, Faheem, Yadav, Anupam, Alaziz, Karam Myaser Abd, Khalid, Maria, Ahmad, Nafis, Sabugaa, Michael M., and Kamalinahad, Saeedeh

Subjects
CHEMICAL detectors, ELECTRONIC structure, GASES, BAND gaps, COVID-19
Abstract

To assess the potential of a pristine B84 nanocluster as a chemical sensor, DFT studies were conducted to investigate the interaction between NO and N2O gases and the surface of B84. The optimized structure and electronic characteristics of pristine B84, NO, and N2O gas indicated that B84 could detect NO gas effectively, while being a poor candidate for sensing N2O gas. Further optimization using the PBE/6-31G(d) level of theory revealed that NO gas chemisorbed onto B84 through favorable configurations S1 and S2, with Eads values of − 25.45 and − 25.10 kcal/mol, respectively. The adsorption of NO significantly altered the electronic properties of B84, resulting in a decrease in the energy gap between HOMO and LUMO orbitals of S1 and S2 configurations by approximately − 68.29% and − 63.41%, respectively, which could be used as a chemical signal. In contrast, the electrical properties of B84 changed insignificantly after N2O adsorption. Overall, the study suggests that B84 could potentially serve as a sensor for detecting NO gas in the presence of N2O. [ABSTRACT FROM AUTHOR]

Published
2024
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45. Molecular dynamics study of the effects of the porosity and initial pressure on phase transition of porous phase change materials

Author

Wang, Huanlei, primary, Musa, Duaa Abdul Rida, additional, Ahmad, Nafis, additional, Altalbawy, Farag M.A., additional, Salman, Nawras Ali, additional, Khazaal, Waleed Mohammed, additional, Salman, Noor Abd Alkhudhur, additional, Abosaooda, Munther, additional, Nasajpour-Esfahani, Navid, additional, Hekmatifar, Maboud, additional, and Toghraie, Davood, additional

Published
2023
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50. MENGAPA TERJADI GROWTH WITHOUT DEVELOPMENT DI PROVINSI KALIMANTAN TIMUR?

Author

Mudrajad Kuncoro and Ahmad Nafis Idris

Subjects
regional typology, location quotient, leading sector, structural transformation, Economics as a science, HB71-74
Abstract

This study attempts to examine to what extent growth without development has occured in East Kalimantan (Kaltim)? It will use several analyses, in particular regional typology based on economic growth and Gross Regional Domestic Product (GRDP), leading sectors and subsectors, location pattern of those leading sectors and subsectors, and the structural transformation. To analyse the effects of regional autonomy on Kaltim, the data used in this research are divided into two periods: before (1993-2000) and after regional autonomy (2001-2007). By using quantitative-descriptive analyses, our findings find that: first, miningexcavation has persisted to be the major leading sector in Kaltim. Second, leading subsectors in Kaltim comprise forestry, oil and gas, nonoil and gas industry, and wholesale-retail commerce. Third, the leading subsectors tend to despecialize in Kaltim during the implementation of regional autonomy. Fourth, structural transformation does not occur in all kabupaten/kota of Kaltim confirming that Kaltim is a good provincial example for growth without development.

Published
2015

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