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Bio-inspired chameleon technique in MAC protocol for energy efficient wireless sensor networks
No full textDoctor of Philosophy in Computer EngineeringWireless Sensor Networks (WSN) is gaining the interest of researchers due to numerous applications. WSN consists of sensor nodes connected with wireless technology to form a network. The sensor devices powered by the battery and collect the data from the environment and send to a base station. In the wireless sensor network, the topology changes frequently due to sensor nodes. The aforementioned behavior emphasis the impact of the MAC protocol mechanism in the performances of WSN. In recent years, the analysis of WSN MAC protocols and their impact on the performances of the network
with different network scenarios has significantly developed a precise understanding of
the requirements and goals for designing a MAC protocol. In the literature, many MAC
protocol mechanisms are proposed to deal with WSN requirements. Nonetheless,
proposed MAC mechanisms in the literature considered a single network scenario in
WSN. However, the sensor nodes face some problems like the failure, addition, energy
depletion, and movement which leads to different scenarios. The adhered behavior of
WSN nodes results in a need for a MAC mechanism that addresses the requirement of
more than one network scenarios. This problem is less considered in the literature. Hence,
this thesis proposes a chameleon mechanism for MAC protocol to tackle topology
changes in WSN. The proposed mechanism defines the performances of a MAC protocol
in different network scenarios as a single and multiple objectives optimization problems.
The single objective problem is solved by Taguchi method, while the multi-objective
optimization problem is solved by differential evolution algorithm. The proposed
mechanism is integrated with Berkeley MAC (B-MAC). Extensive simulation results are
presented by comparing the performances of optimized and non-optimized Berkeley-
MAC mechanisms. The mechanism is evaluated under varying number of nodes,
simulation time, traffic generation, and message length for two network topologies;
partial of farm1 and partial of farm2 scenarios. The results show that the proposed
Chameleon mechanism B-MAC improves the performance of multiple WSN scenarios
in-terms of packet delivery ratio, throughput, end-to-end delay, and minimize the power
consumption
Adaptive image watermarking algorithm based on an efficient perceptual mapping model with FPGA implementation
No full textDoctor of Philosophy in Computer EngineeringWatermark imperceptibility is a significant factor for keeping watermarked images looking perceptually similar to the original ones. Effective watermark imperceptibility requires the creation of a perceptual model that simulates the human visual system to
efficiently hide the watermark bits in places where the human eye cannot observe it. Current perceptual-based watermarking models use complex computations that are difficult to implement in embedded systems or in real time applications. In this thesis, a low-complexity, integer-based Lifting Wavelet Transform (LWT) was utilized to create a perceptual mapping model that is mainly relied on a new texture mapping model called Accumulative Lifting Difference (ALD). The ALD is combined with a simplified edge detection and luminance masking models to obtain a comprehensive perceptual mapping model that has high noise tolerance and it is based on low complexity calculations. The proposed model was 7% faster than the fastest pixel-based compared model, with an enhanced average PSNR gain of 2.75 dB. In comparison to the largest noise tolerance sub-band compared model, the proposed JND model had a PSNR gain of 1.78 dB and an execution speed that was up to 90% faster. The perceptual model is utilized in a proposed image watermarking algorithm to determine the maximum watermark embedding intensity that is not visible to the human eye. The experimental results show that the proposed algorithm produced high quality watermarked images with SSIM value larger than 0.95 for all tested images and it was robust against different geometric and non-geometric attacks. For real time response, the presented watermarking algorithm was designed, implemented and tested on Altera® Cyclone-II FPGA device using VHDL. The parallel structure of the design allowed the system to be executed at a clock speed of 101.02 MHz, which make it suitable for emerging realtime
applications
Surface modification, characterization and properties of regenerated cellulose NYPA fructicans filled microcrystalline cellulose biocomposite films
No full textDoctor of Philosophy in Materials Engineering.
Confidential item (contains confidential information under the Official Secret Act 1972*)The regenerated cellulose (RC) biocomposite films from nypa fruticans (NF) and microcrystalline cellulose (MCC) were prepared via solvent casting method using ionic liquid. The solvent system of N, N Dimethylacetamide (DMAc) and Lithium Chloride
(LiCl) were used to dissolve cellulose at room temperature. In this study, the biocomposite films containing MCC and NF were varied from 1, 2, 3 and 4 wt%. The effect of MCC, NF content and different chemical modifications such as acrylic acid
(AA), methacrylate acid (MAA), butyl methacrylate acid (BMA), maleic acid (MA), adipic acid (ADA), acetic acid (AAc) and 3-aminopropyltriethoxy silane (APTES) on the tensile properties, morphology, X- ray diffraction (XRD), thermogravimetry
analysis (TGA), fourier transform infrared (FTIR), moisture content and enzymatic biodegradation of RC biocomposite films were investigated. The result showed that the RC films at 3 wt% of MCC content and NF RC biocomposite films at 3 wt% NF
content had highest tensile strength, Young’s modulus and crystallinity index (CrI). The morphology study of NF RC biocomposite films indicated better dispersion of filler in matrix at 3 wt% of NF content. Meanwhile, the thermal stability of both RC films and
NF RC biocomposite films increased with increasing of MCC or NF content. The moisture content and weight loss for enzymatic biodegradation of both RC films and NF RC biocomposite films increased with increasing of MCC and NF content, respectively.
The chemical modifications of NF using AA, MAA, BMA, MA, ADA, AAc and
APTES showed improvement in the properties of treated NF RC biocomposite films.
The FTIR spectra showed the changes of functional group of treated NF RC
biocomposite films. The tensile properties and crystallinity index of treated RC
biocomposite films with AA, MAA, BMA, MA, ADA, AAc and APTES were higher
than the untreated NF RC biocomposite films. The improvement of interfacial
interaction of treated NF RC biocomposite films was proven by the SEM. Furthermore,
the treated NF RC biocomposite films showed higher thermal stability compared to the
untreated NF RC biocomposite films. Moreover, the moisture content and weight loss
of enzymatic biodegradation of treated NF RC biocomposite films were lower than that
of untreated NF RC biocomposite films. Results showed that the treated NF RC
biocomposite films with AAc exhibited the highest tensile properties, thermal stability
and resistance towards moisture and enzymatic attack among the others treated NF RC
biocomposite films
