Page 444 - Mathematical Techniques of Fractional Order Systems

Applications of Continuous-time Fractional Order Chapter | 14 429

FIGURE 14.10 Image encryption and decryption examples based on the algorithm in
Dasgupta et al. (2014). (A) The original image, (B) the encrypted version and (C) the decrypted
version.

(LSB) extractor that extracts the LSB from the x and y state variables and
then gives it results to a 3 3 1 multiplexer which choses the state variable to
be used in the Xor process. Another switching scheme was proposed by Hou
et al. (2017) where the switching between the three state variables of the FO
Chen system is made based on the color level of the pixel as:
8
x 1 ; 0 # m , 85;
<
fðxÞ 5 x 2 ; 85 # m , 170; ð14:57Þ
x 3 ; 170 # m # 255;
:
where m is integer value at the pixel and the Xor operation is made as:
m encrypted 5 m"fðxÞ. Other notable trials include encryption based on
improper FOCS (Zhao et al., 2015) and image encryption using coupled-map
lattices (CML) and a FOCS (Wu et al., 2015).

14.6 BIOMEDICAL
14.6.1 Evaluation of Arteriovenous Stenosis in
Hemodialysis Patients
A noninvasive strategy was developed by Chen et al. (2013a,b) to evaluate
the stage of arteriovenous access (AVA) stenosis and arteriovenous shunt
(AVS) stenosis in hemodialysis patients. The authors used a FOCS to
monitor the difference in frequency response between the healthy and
unhealthy cases.
For AVA, the Burg method was used to estimate the frequency spectra of
phonographic signals recorded from the patient and it was found the spectra
differed between normal and stenosis cases. Forty-two patients with AVA
had received percutaneous transluminal angioplasty (PTA) and participated