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04- International Journal of Thin Films Science and Technology



Time Series Forecasting Using Tree Based Methods

EL Houssainy A. Rady, Haitham Fawzy, Amal Mohmed Abdel Fattah,
Abstract :
This paper aims to use the tree-based methods for time series data forecasting. The main goal of this study is to compare between Decision Tree (DT), Random Forest (RF), Gradient Boosted Trees (GBT) and ARIMA model to predict monthly gold prices. The time series data for the monthly gold prices was used during the period from Nov -1989 to Dec-2019, which represents 362 observations. ARIMA, DT, RF, and GBT models were fitted based on 90% of data as training set, and then their accuracy was compared using the statistical measure RMSE. The results indicated that RF was better than DT, GBT and ARIMA (0,1,1) in predicting future gold prices, based on RMSE= 44.32.


Design and Fabrication of Broadband Dielectric Mirrors in the Visible Range

Ali Jebelli, Hicham Chaoui, Hossein Kazemi, Arezoo Mahabadi, Balbir Dhillon,
Abstract :
—A broadband dielectric mirror in the visible spectrum is made by putting together two quarter- wavelength stacks with two different reference wavelengths and for smoothing the mirror’s spectrum, the gradient algorithm has been used. This mirror consists of 39 layers that have been fabricated by alternative deposition of zinc sulfide and Cryolite, using vacuum thermal evaporation on a glass substrate. The Mirror’s reflectance spectrum was measured and it was found close to ideal state.


Optimization of LDM 3D printing parameters for TiO2 thin film fabrication

Aran Hansuebsai,
Abstract :
With the development of 3D printing technology, the application of liquid deposition modeling (LDM) 3D printing has become more and more widespread. Our study aimed to use this printer type to fabricate TiO2 paste on an electrode for Dye Sensitized Solar Cell (DSSC). As the paste showed a shear-thinning behavior, the printing test was carried out to investigate the effects of printer’s parameters setting on the thin film characteristics. Number of successive layers was also considered to ensure the quality of printing. The critical thickness of TiO2 thin films and relevant sheet resistance in this system were achieved at 6.25 µm and 6.8E+6 Ω/square respectively. Examples of DSSC directly formed upon the obtained thin films were presented, by which the energy conversion efficiency was received at approximately 4%. This approach opens the way to the direct deposition of nano-TiO2 paste by means of a low-cost LDM 3D printer. It includes the product development in different patterns and shapes of printed thin films


On variation of rate of growth of epitaxial layers by variation of substrate heating

Abstract :
In this paper, we estimate the rate of growth of epitaxial layers from the gas phase. We study dependence of the rate on the value of the heating of the substrate. By using the previously introduced approach of mass and heat transfer analysis, analytical de-pendencies of the considered rate on the parameters were obtained. In this paper based on recently introduced approach we analyzed mass and heat transport during growth of epitaxial layers in reactors for epitaxy from gas phase with sloping keeper with account native convection. Based on recently introduced approach we estimate rate of growth of films and analyzed dependences of the rate on physical and technological parameters.

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