With the widespread use of the internet,there is an increasing need to ensure the security and privacy of transmitted data.This has led to an intensified focus on the study of video steganography,which is a technique ...With the widespread use of the internet,there is an increasing need to ensure the security and privacy of transmitted data.This has led to an intensified focus on the study of video steganography,which is a technique that hides data within a video cover to avoid detection.The effectiveness of any steganography method depends on its ability to embed data without altering the original video’s quality while maintaining high efficiency.This paper proposes a new method to video steganography,which involves utilizing a Genetic Algorithm(GA)for identifying the Region of Interest(ROI)in the cover video.The ROI is the area in the video that is the most suitable for data embedding.The secret data is encrypted using the Advanced Encryption Standard(AES),which is a widely accepted encryption standard,before being embedded into the cover video,utilizing up to 10%of the cover video.This process ensures the security and confidentiality of the embedded data.The performance metrics for assessing the proposed method are the Peak Signalto-Noise Ratio(PSNR)and the encoding and decoding time.The results show that the proposed method has a high embedding capacity and efficiency,with a PSNR ranging between 64 and 75 dBs,which indicates that the embedded data is almost indistinguishable from the original video.Additionally,the method can encode and decode data quickly,making it efficient for real-time applications.展开更多
Electrical properties of C/Ni films are studied using four mosaic targets made of pure graphite and stripes of nickel with the surface areas of 1.78,3.21,3.92 and 4.64%.The conductivity data in the temperature range o...Electrical properties of C/Ni films are studied using four mosaic targets made of pure graphite and stripes of nickel with the surface areas of 1.78,3.21,3.92 and 4.64%.The conductivity data in the temperature range of400-500 K shows the extended state conduction.The conductivity data in the temperature range of 150-300 K shows the multi-phonon hopping conduction.The Berthelot-type conduction dominates in the temperature range of 50-150 K.The conductivity of the films in the temperature range about 〈 50 K is described in terms of variable-range hopping conduction.In low temperatures,the localized density of state around Fermi level（F）for the film deposition with 3.92% nickel has a maximum value of about 56.2×10^（17）cm^（-3）eV^（-1） with the minimum average hopping distance of about 3.43 × 10^（-6） cm.展开更多
The rivet joints have been widely applied in aerospace and vehicle fields.During the joining process of the carbon fiber reinforced plastic(CFRP)laminates,the pre-tightening force of pulling-rivet was the key factor t...The rivet joints have been widely applied in aerospace and vehicle fields.During the joining process of the carbon fiber reinforced plastic(CFRP)laminates,the pre-tightening force of pulling-rivet was the key factor to ensure the connection performance.To predict the impact of clamping loads on stress and failure of laminates,the value of stress and damage evolution of the wall of a hole under the pre-tightening force were simulated by the finite element method.The results of the simulation showed that excessive clamping force led to the damage and failure of CFRP in the hole edge.Connection performance together with progressive failure process and failure modes of CFRP laminates with various pre-tightening forces were investigated.A kind of metal embedded parts embedded in the laminates was designed to reduce the damage by the simulation study.Simulation results showed that embedment reduced the failure and damage efficiently.The embedment reduced about 64%of the maximum stress.展开更多
In this study,alumina/A380 composite coatings were fabricated by cold spray.The influence of alumina particulates,morphology(spherical and irregular)and content on the deposition behavior of the coatings(including sur...In this study,alumina/A380 composite coatings were fabricated by cold spray.The influence of alumina particulates,morphology(spherical and irregular)and content on the deposition behavior of the coatings(including surface roughness,surface residual stress,cross-sectional microstructure and microhardness)was investigated.Results revealed that the spherical alumina mainly shows micro-tamping effect during deposition,which result in remarkable low surface roughness and porosity of the coatings.In addition,very low deposition efficiency and good interfacial bonding between the coating and the substrate were achieved.For irregular alumina particles,the embedding of ceramic particulates in the coating was dominant during deposition process,resulting in high retention in the final deposit.However,it showed limited influence on porosity,surface roughness and interfacial bonding of the deposit.The coatings containing irregular alumina particulates exhibited much higher microhardness than those containing spherical alumina due to the higher load-bearing capacity of deposited alumina.展开更多
文摘With the widespread use of the internet,there is an increasing need to ensure the security and privacy of transmitted data.This has led to an intensified focus on the study of video steganography,which is a technique that hides data within a video cover to avoid detection.The effectiveness of any steganography method depends on its ability to embed data without altering the original video’s quality while maintaining high efficiency.This paper proposes a new method to video steganography,which involves utilizing a Genetic Algorithm(GA)for identifying the Region of Interest(ROI)in the cover video.The ROI is the area in the video that is the most suitable for data embedding.The secret data is encrypted using the Advanced Encryption Standard(AES),which is a widely accepted encryption standard,before being embedded into the cover video,utilizing up to 10%of the cover video.This process ensures the security and confidentiality of the embedded data.The performance metrics for assessing the proposed method are the Peak Signalto-Noise Ratio(PSNR)and the encoding and decoding time.The results show that the proposed method has a high embedding capacity and efficiency,with a PSNR ranging between 64 and 75 dBs,which indicates that the embedded data is almost indistinguishable from the original video.Additionally,the method can encode and decode data quickly,making it efficient for real-time applications.
文摘Electrical properties of C/Ni films are studied using four mosaic targets made of pure graphite and stripes of nickel with the surface areas of 1.78,3.21,3.92 and 4.64%.The conductivity data in the temperature range of400-500 K shows the extended state conduction.The conductivity data in the temperature range of 150-300 K shows the multi-phonon hopping conduction.The Berthelot-type conduction dominates in the temperature range of 50-150 K.The conductivity of the films in the temperature range about 〈 50 K is described in terms of variable-range hopping conduction.In low temperatures,the localized density of state around Fermi level（F）for the film deposition with 3.92% nickel has a maximum value of about 56.2×10^（17）cm^（-3）eV^（-1） with the minimum average hopping distance of about 3.43 × 10^（-6） cm.
文摘The rivet joints have been widely applied in aerospace and vehicle fields.During the joining process of the carbon fiber reinforced plastic(CFRP)laminates,the pre-tightening force of pulling-rivet was the key factor to ensure the connection performance.To predict the impact of clamping loads on stress and failure of laminates,the value of stress and damage evolution of the wall of a hole under the pre-tightening force were simulated by the finite element method.The results of the simulation showed that excessive clamping force led to the damage and failure of CFRP in the hole edge.Connection performance together with progressive failure process and failure modes of CFRP laminates with various pre-tightening forces were investigated.A kind of metal embedded parts embedded in the laminates was designed to reduce the damage by the simulation study.Simulation results showed that embedment reduced the failure and damage efficiently.The embedment reduced about 64%of the maximum stress.
基金financially supported by the National Natural Science Foundation of China (Nos.51671205 and 51801217)
文摘In this study,alumina/A380 composite coatings were fabricated by cold spray.The influence of alumina particulates,morphology(spherical and irregular)and content on the deposition behavior of the coatings(including surface roughness,surface residual stress,cross-sectional microstructure and microhardness)was investigated.Results revealed that the spherical alumina mainly shows micro-tamping effect during deposition,which result in remarkable low surface roughness and porosity of the coatings.In addition,very low deposition efficiency and good interfacial bonding between the coating and the substrate were achieved.For irregular alumina particles,the embedding of ceramic particulates in the coating was dominant during deposition process,resulting in high retention in the final deposit.However,it showed limited influence on porosity,surface roughness and interfacial bonding of the deposit.The coatings containing irregular alumina particulates exhibited much higher microhardness than those containing spherical alumina due to the higher load-bearing capacity of deposited alumina.
