The main aim of this article was to develop new glaze receipts (NGRs) to build up the acid resistance (AR) of commercial glazes (CGs) used in floor tile production. The glaze is a vitrified material that melts the surface of the ceramic material. Improvements were made during and after the manufacture, based on the glaze samples of the CGs. NGRs were synthesized using different mineral compositions. AR, density, chemical, and physical properties of commercial and new synthesized glazes were determined using X-ray diffraction, scanning electron microscopy/energy-dispersive X-ray spectroscopy, Fourier transform infrared spectrometry, and water contact angle analysis methods. The AR of the obtained samples (standard and developed floor tiles) was examined by treating them with 3% HCl for 3 days. Results showed that synthesized glazes had higher AR than standard glazes (CGs). The NGRs also significantly improved the ceramic surface coating features of the new glazes.
Wavelet coherence of time series provides valuable information about dynamic correlation and its impact on time scales. Here, the authors analyze the wavelet coherence of major real estate markets data, and take the USA, Hong Kong of China, Canada, Japan, and Developed Europe real estate market prices as time series. The wavelet coherence results show relationships among these markets, the correlations between the two and three markets (by multiple wavelet coherence) and how these relationships vary in the time-frequency space. These relationships allow the authors to build VARMA models of real estate data which produce forecasts with small errors.
There has probably never been as big a divergence between markets and economies as there is in the pandemic period. This paper is an attempt to test the ‘time-varying’ and ‘time-scale dependent’ volatilities of major technology stocks, FAANG and Microsoft, for analyzing the possibility of a second technology bubble in the markets. Consistent with the results of DCC-GARCH models, our analysis based on the application of the Wavelet approach also indicates that major technology behave and move as if they were all one stock in the pandemic period which makes us to be cautious about a second dotcom crisis since %26 of S&P 500 market cap is driven by FAANG and Microsoft stocks.
JEL classification numbers: C58, D53, O14.
Keywords: Dot-com crisis, tech bubble, DCC-GARCH, FAANG, Wavelet.
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