520 research outputs found
Difference-expansion based reversible data hiding and its steganalysis
A novel reversible data embedding method was reported in a recent IEEE journal article. The method was based on difference expansion (DE) technique. It used redundancy in digital images to achieve a high embedding capacity, while keeping visual distortion of the stego-image low. In this thesis, this technique was studied and experimentally evaluated. An effective steganalysis scheme for this DE-based reversible data embedding method was proposed, which used 12-dimensional feature vectors and a Bayes Classifier. The proposed steganalysis scheme steadily achieved a correct classification rate of 99%
Effect of lead oxide on concrete density for radiation shielding purposes
Selection of suitable shielding materials depends on the type, intensity and energy of
radiation source, as well as the shielding properties such as mechanical strength, economic
preparation and resistance to radiation damage. When compared to ordinary concrete, the addition
of some materials with various fractions in the composition of concrete has provided concrete forms
more efficient for gamma ray shielding. Concrete has proven to be an tremendous and adaptable
shielding material with a well-established linear attenuation coefficient for gamma rays and
neutrons. The objectives of this study is to determine the exact composition of concrete constituents
and its density. Concrete samples were prepared by mixing cement, water, aggregate and additive
with different composition and densities. Density was increases by decreasing the aggregates
percent and increasing the additives such as lead oxide. Sample will be compacting to forming a
solid material through pelleting and sintering process. Finally, it will undergo for radiation
attenuation test. It was found that, substitution of lead oxide by aggregate causes increasing in the
specific density and compressive strength of the concrete
A Chaotic IP Watermarking in Physical Layout Level Based on FPGA
A new chaotic map based IP (Intellectual Property) watermarking scheme at physical design level is presented. An encrypted watermark is embedded into the physical layout of a circuit by configuring LUT (Lookup Table) as specific functions when it is placed and routed onto the FPGA (Field-Programmable Gate Array). The main contribution is the use of multiple chaotic maps in the processes of watermark design and embedding, which efficiently improves the security of watermark. A hashed chaotic sequence is used to scramble the watermark. Secondly, two pseudo-random sequences are generated by using chaotic maps. One is used to determine unused LUT locations, and the other divides the watermark into groups. The watermark identifies original owner and is difficult to detect. This scheme was tested on a Xilinx Virtex XCV600-6bg432 FPGA. The experimental results show that our method has low impact on functionality, short path delay and high robustness in comparison with other methods
Research on digital image watermark encryption based on hyperchaos
The digital watermarking technique embeds meaningful information into one or more watermark images hidden in one image, in which it is known as a secret carrier. It is difficult for a hacker to extract or remove any hidden watermark from an image, and especially to crack so called digital watermark. The combination of digital watermarking technique and traditional image encryption technique is able to greatly improve anti-hacking capability, which suggests it is a good method for keeping the integrity of the original image. The research works contained in this thesis include: (1)A literature review the hyperchaotic watermarking technique is relatively more advantageous, and becomes the main subject in this programme. (2)The theoretical foundation of watermarking technologies, including the human visual system (HVS), the colour space transform, discrete wavelet transform (DWT), the main watermark embedding algorithms, and the mainstream methods for improving watermark robustness and for evaluating watermark embedding performance. (3) The devised hyperchaotic scrambling technique it has been applied to colour image watermark that helps to improve the image encryption and anti-cracking capabilities. The experiments in this research prove the robustness and some other advantages of the invented technique. This thesis focuses on combining the chaotic scrambling and wavelet watermark embedding to achieve a hyperchaotic digital watermark to encrypt digital products, with the human visual system (HVS) and other factors taken into account. This research is of significant importance and has industrial application value
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