An Efficient Model in Calculating Anharmonic XAFS Debye-Waller Factor of Metal Crystals
Nguyen Thi Ngoc Anh,
Nguyen Ngoc Thang,
Dang Van Trong
Issue:
Volume 7, Issue 2, June 2022
Pages:
21-26
Received:
25 May 2022
Accepted:
9 June 2022
Published:
20 June 2022
DOI:
10.11648/j.aas.20220702.11
Downloads:
Views:
Abstract: The X-ray absorption fine structure (XAFS) is often used effectively to determine many structural parameters and dynamic properties of materials, so calculating the temperature-dependent XAFS Debye-Waller (DW) factor of metal crystals will be a necessary addition to the advanced material technique. In this work, the thermodynamic parameters are derived from the influence of the absorbing and backscattering atoms of all their nearest neighbors in the crystal lattice with thermal vibrations. The anharmonic XAFS DW factor of metal crystals has been obtained in explicit forms using the anharmonic correlated Debye (ACD) model. This calculation model is developed from the correlated Debye model using the anharmonic-effective potential and many-body perturbation approach. The numerical results for the crystalline cadmium are in good agreement with those obtained by the other theoretical model and experimental data at several temperatures. The analytical results show that the ACD model is useful and efficient in calculating the anharmonic XAFS DW factor of metal crystals. This model can be applied to calculate the anharmonic XAFS DW factor for other metals from above absolute zero temperature to just before the melting point.
Abstract: The X-ray absorption fine structure (XAFS) is often used effectively to determine many structural parameters and dynamic properties of materials, so calculating the temperature-dependent XAFS Debye-Waller (DW) factor of metal crystals will be a necessary addition to the advanced material technique. In this work, the thermodynamic parameters are der...
Show More
Signal Steganography Using Different Wavelets and Their Comparisons
Shemanta Kumar Biswas,
Redwanul Islam,
Md. Rafiqul Islam
Issue:
Volume 7, Issue 2, June 2022
Pages:
27-32
Received:
9 May 2022
Accepted:
25 May 2022
Published:
30 June 2022
DOI:
10.11648/j.aas.20220702.12
Downloads:
Views:
Abstract: The process of inserting secret data in any media as pictures, audio, video, text and protocol, also it can be empathy this secret connection is called steganography. At present, the widespread use of internet applications has become a security risk. Steganography is used to overcome this undesirable situation. It shows a significant character in maintaining privacy. Some steganographic techniques modify the image using the spatial domain, transform domain, spread spectrum, statistical method and distortion techniques. This work aims to develop efficient data encryption and decryption technique that provide security of data. In this research exertion, it anticipated an image steganalysis method using various wavelet decomposition, especially using multiwavelet decomposition. First, we decomposed the image using different wavelets and multiwavelets. Then we extracted the more informative parts into wavelet sub-bands as a feature and inserted them into the LL sub-band wavelet decomposed image. The resulting image is sent to the recipient as a signal. The recipient retrieves confidential information through encryption. Finally, by analyzing the actions of different wavelets, we can retrieve the original message through the decryption technique. The multiwavelet technique achieves PSNR of 48.26 - 56.5926 and MSE of 0.1428 - 0.97. The result indicates that multiwavelet provided a good recovery of the secret image quality that led to an increase in the imperceptibility of the system.
Abstract: The process of inserting secret data in any media as pictures, audio, video, text and protocol, also it can be empathy this secret connection is called steganography. At present, the widespread use of internet applications has become a security risk. Steganography is used to overcome this undesirable situation. It shows a significant character in m...
Show More
