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51.
Narendra Singh 《Optics & Laser Technology》2010,42(5):724-588
We propose a new method for multiple image encryption using linear canonical transforms and chaotic maps. Three linear canonical transforms and three chaotic maps are used in the proposed technique. The three linear canonical transforms that have been used are the fractional Fourier transform, the extended fractional Fourier transform and the Fresnel transform. The three chaotic maps that have been used are the tent map, the Kaplan-Yorke map and the Ikeda map. These chaotic maps are used to generate the random phase masks and these random phase masks are known as chaotic random phase masks. The mean square error and the signal to noise ratio have been calculated. Robustness of the proposed technique to blind decryption has been evaluated. Optical implementation of the technique has been proposed. Experimental and simulations results are presented to verify the validity of the proposed technique. 相似文献
52.
Narendra Singh 《Optik》2010,121(15):1427-1437
We propose a new method for digital image watermarking using gyrator transform and chaotic maps. Four chaotic maps have been used in the proposed technique. The four chaotic maps that have been used are the logistic map, the tent map, the Kaplan-Yorke map and the Ikeda map. These chaotic maps are used to generate the random phase masks and these random phase masks are known as chaotic random phase masks. A new technique has been proposed to generate the single chaotic random phase mask by using two chaotic maps together with different seed values. The watermark encoding method in the proposed technique is based on the double random phase encoding method. The gyrator transform and two chaotic random phase masks are used to encode the input image. The mean square error, the peak signal-to-noise ratio and the bit error rate have been calculated. Robustness of the proposed technique has been evaluated in terms of the chaotic maps, the number of the chaotic maps used to generate the CRPM, the rotation angle of the gyrator transform and the seed values of the chaotic random phase masks. Optical implementation of the technique has been proposed. The computer simulations are presented to verify the validity of the proposed technique. 相似文献
53.
Soumya R. Deo Ajaya K. Singh Lata Deshmukh Narendra Pratap Singh Mariya P. Aleksandrova 《Journal of fluorescence》2016,26(2):459-469
The thin films of CdS1-xSex were successfully deposited over glass substrates by chemical bath deposition technique. Cadmium acetate, thiourea and sodium selenosulfate were used as source materials for Cd2+, S2? and Se2? ions, while 2-mercaptoethanol was used as capping agent. The various deposition conditions such as precursor concentration, deposition temperature, pH and deposition time were optimized for the deposition of CdS1-xSex thin films of good quality and the films were annealed at 200° and 300 °C. The structural, morphological, chemical and optical properties were examined by various characterization techniques and discussed in detail. The optical band gap of CdS1-xSex thin film samples were estimated and found in the range from 2.11 to 1.79 eV for as-deposited and annealed thin films. 相似文献
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57.
D. R. S. Somayajulu Narendra Patel Mukesh Chawda Mitesh Sarkar K. C. Sebastian 《Hyperfine Interactions》2005,160(1-4):241-246
Hyperfine interaction techniques like Mossbauer spectroscopy are very sensitive tools to study the local probe interactions
in dilute magnetic semiconductors. We report here a Mossbauer study on the concentration dependence in Fe0.008Ge1 − x
Te
x
for x = 0, 0.008, 0.016, 0.03 and 0.05. At room temperature magnetic interactions were observed for all concentrations of Te and
the population of magnetic site was found to increase gradually with the Te concentration. A constant magnetic hyperfine field
of 136 KOe was found. A quadrupole doublet due to the FeTe2 compound phase was also seen. 相似文献
58.
Saayak Halder Narendra Nath Jha Soumik Ray Surabhi Mehra Vipin Agarwal Samir K. Maji 《Angewandte Chemie (International ed. in English)》2018,57(19):5262-5266
α‐Synuclein (α‐Syn) aggregation is associated with Parkinson's disease (PD) pathogenesis. In PD, the role of oligomers versus fibrils in neuronal cell death is debatable, but recent studies suggest oligomers are a proximate neurotoxin. Herein, we show that soluble α‐Syn monomers undergo a transformation from a solution to a gel state on incubation at high concentration. Detailed characterization of the gel showed the coexistence of monomers, oligomers, and short fibrils. In vitro, the gel was highly cytotoxic to human neuroblastoma cells. The individual constituents of the gel are short‐lived species but toxic to the cells. They comprise a structurally heterogeneous population of α‐helical and β‐sheet‐rich oligomers and short fibrils with the cross‐β motif. Given the recent evidence of the gel‐like state of the protein associated with neurodegenerative diseases, the gel state of α‐Syn in this study represents a mechanistic and structural model for the in vivo toxicity of α‐Syn in PD. 相似文献
59.
Shifts of the chlorine Kα1,2 X-ray emission line in gaseous molecules and in crystalline NaCl are correlated with effective atomic charges from CNDO/2 molecular orbital calculations made (i) for the neutral atomic ground states. and (ii) within the equivalent core approximation. For the latter case CNDO/2 parameters are derived for argon. The best agreement with experimental chemical shifts is obtained with the equivalent cores approximation. The results for NaCl depend strongly upon the CNDO/2 treatment of sodium. 相似文献
60.
Dr. Rolf Manne 《Theoretical chemistry accounts》1966,6(2):116-121
Projection coefficients for total spin angular momentum of systems of 1 to 20 particles with spin 1/2 have been calculated on a digital computer.
The research reported in this paper was sponsored in part by the Gustaf VI Adolf's 70-Years Fund for Swedish Culture, Knut and Alice Wallenberg's Foundation, and in part by the Aerospace Research Laboratories, (OAR), through the European Office of Aerospace Research, United States Air Force, under Contract AF 61(052)-701. 相似文献
Zusammenfassung Die Projektionskoeffizienten für Eigenzustände des Betrages des Spindrehimpulses sind für Systeme von 1 bis 20 Spin-1/2-Teilchen berechnet worden.
Résumé Les coefficients de projection du moment angulaire de spin total de systèmes de 1 à 20 particules de spin 1/2 ont été calculés sur un ordinateur.
The research reported in this paper was sponsored in part by the Gustaf VI Adolf's 70-Years Fund for Swedish Culture, Knut and Alice Wallenberg's Foundation, and in part by the Aerospace Research Laboratories, (OAR), through the European Office of Aerospace Research, United States Air Force, under Contract AF 61(052)-701. 相似文献