A novel image encryption scheme based on parallel compressive sensing and edge detection embedding technology is proposed to improve visual security. Firstly, the plain image is sparsely represented using the discrete...A novel image encryption scheme based on parallel compressive sensing and edge detection embedding technology is proposed to improve visual security. Firstly, the plain image is sparsely represented using the discrete wavelet transform.Then, the coefficient matrix is scrambled and compressed to obtain a size-reduced image using the Fisher–Yates shuffle and parallel compressive sensing. Subsequently, to increase the security of the proposed algorithm, the compressed image is re-encrypted through permutation and diffusion to obtain a noise-like secret image. Finally, an adaptive embedding method based on edge detection for different carrier images is proposed to generate a visually meaningful cipher image. To improve the plaintext sensitivity of the algorithm, the counter mode is combined with the hash function to generate keys for chaotic systems. Additionally, an effective permutation method is designed to scramble the pixels of the compressed image in the re-encryption stage. The simulation results and analyses demonstrate that the proposed algorithm performs well in terms of visual security and decryption quality.展开更多
为解决海洋温差能发电中换热器的计算问题,基于MATLAB软件,提出一种应用于海洋温差能发电(ocean thermal energy conversion, OTEC)满液式换热器沸腾传热与凝结传热的传热计算方法,并建立海洋温差能满液式换热器数学模型。在此模型的基...为解决海洋温差能发电中换热器的计算问题,基于MATLAB软件,提出一种应用于海洋温差能发电(ocean thermal energy conversion, OTEC)满液式换热器沸腾传热与凝结传热的传热计算方法,并建立海洋温差能满液式换热器数学模型。在此模型的基础上,针对表层25~30℃温海水、深层4~6℃冷海水的OTEC循环工况,分析不同循环工况下换热器传热系数的变化情况;针对进水温度、进水流量、壳程压力对换热效率的影响进行数值计算,得出OTEC循环工况下不同因素对满液式换热器传热系数的影响。研究表明,OTEC循环工况下蒸发器传热系数与温海水的进水温度、流量、壳程压力呈正相关;冷凝器传热系数与冷海水的流量呈正相关,与进水温度、壳程压力呈负相关。通过海洋温差循环试验平台进行试验,将试验结果与数学模型相对比,验证了数学模型的准确性。展开更多
基金supported by the Key Area R&D Program of Guangdong Province (Grant No.2022B0701180001)the National Natural Science Foundation of China (Grant No.61801127)+1 种基金the Science Technology Planning Project of Guangdong Province,China (Grant Nos.2019B010140002 and 2020B111110002)the Guangdong-Hong Kong-Macao Joint Innovation Field Project (Grant No.2021A0505080006)。
文摘A novel image encryption scheme based on parallel compressive sensing and edge detection embedding technology is proposed to improve visual security. Firstly, the plain image is sparsely represented using the discrete wavelet transform.Then, the coefficient matrix is scrambled and compressed to obtain a size-reduced image using the Fisher–Yates shuffle and parallel compressive sensing. Subsequently, to increase the security of the proposed algorithm, the compressed image is re-encrypted through permutation and diffusion to obtain a noise-like secret image. Finally, an adaptive embedding method based on edge detection for different carrier images is proposed to generate a visually meaningful cipher image. To improve the plaintext sensitivity of the algorithm, the counter mode is combined with the hash function to generate keys for chaotic systems. Additionally, an effective permutation method is designed to scramble the pixels of the compressed image in the re-encryption stage. The simulation results and analyses demonstrate that the proposed algorithm performs well in terms of visual security and decryption quality.
文摘为解决海洋温差能发电中换热器的计算问题,基于MATLAB软件,提出一种应用于海洋温差能发电(ocean thermal energy conversion, OTEC)满液式换热器沸腾传热与凝结传热的传热计算方法,并建立海洋温差能满液式换热器数学模型。在此模型的基础上,针对表层25~30℃温海水、深层4~6℃冷海水的OTEC循环工况,分析不同循环工况下换热器传热系数的变化情况;针对进水温度、进水流量、壳程压力对换热效率的影响进行数值计算,得出OTEC循环工况下不同因素对满液式换热器传热系数的影响。研究表明,OTEC循环工况下蒸发器传热系数与温海水的进水温度、流量、壳程压力呈正相关;冷凝器传热系数与冷海水的流量呈正相关,与进水温度、壳程压力呈负相关。通过海洋温差循环试验平台进行试验,将试验结果与数学模型相对比,验证了数学模型的准确性。
