Multiple-image Encryption and Multiplexing Using a Modified Gerchberg–Saxton Algorithm in Fresnel-transform Domain and Computational Ghost Imaging

Peiming Zhang,Yahui Su,Yiqiang Zhang,Leihong Zhang,Runchu Xu,Kaimin Wang,Dawei Zhang 한국광학회 2023 Current Optics and Photonics Vol.7 No.4

Optical information processing technology is characterized by high speed and parallelism, and the light features short wavelength and large information capacity; At the same time, it has various attributes including amplitude, phase, wavelength and polarization, and is a carrier of multi-dimensional information. Therefore, optical encryption is of great significance in the field of information security transmission, and is widely used in the field of image encryption. For multi-image encryption, this paper proposes a multi-image encryption algorithm based on a modified Gerchberg–Saxton algorithm (MGSA) in the Fresnel-transform domain and computational ghost imaging. First, MGSA is used to realize “one code, one key”; Second, phase function superposition and normalization are used to reduce the amount of ciphertext transmission; Finally, computational ghost imaging is used to improve the security of the whole encryption system. This method can encrypt multiple images simultaneously with high efficiency, simple calculation, safety and reliability, and less data transmission. The encryption effect of the method is evaluated by using correlation coefficient and structural similarity, and the effectiveness and security of the method are verified by simulation experiments.

Management Strategy Based on Genetic Algorithm Optimization for PHEV

Zhang Yu,Meng Dawei,Zhou Meilan,Lu Dengke 보안공학연구지원센터 2014 International Journal of Control and Automation Vol.7 No.11

Aiming at the refitted HAFEI hybrid electric vehicle (HEV), fuzzy logic energy management strategy is constructed based on genetic algorithm optimization. The difference value D between the total require torque Tr of path and the target required torque Te of engine, the intelligence quotient value with Tr is selected as the first input variable of fuzzy controller, the SOC of battery as the second input variable; torque control coefficient C is selected as output variable, meanwhile two input variable membership function is improved on genetic algorithm. To further evaluate the control strategy, dynamic programming control strategy is used as standard; the simulation experiments show that every kind of gas emission is obviously reduced by 12% to 47% in fuzzy control strategy B based on genetic algorithm optimization compared to strategy A based on determinacy rules. Compared to dynamic programming, fuel economy in strategy A is only 45.09% of standard value which is not ideal, the utilization of fuel is low and the gas emission is serious, while in strategy B fuel economy is 78.89% of standard value and effect is improved obviously.

Study of Spectral Reflectance Reconstruction Based on an Algorithm for Improved Orthogonal Matching Pursuit

Zhang Leihong,Liang Dong,Zhang Dawei,Gao Xiumin,Ma Xiuhua 한국광학회 2016 Current Optics and Photonics Vol.20 No.4

Spectral reflectance is sparse in space, and while the traditional spectral-reconstruction algorithm doesnot make full use of this characteristic sparseness, the compressive sensing algorithm can make full useof it. In this paper, on the basis of analyzing compressive sensing based on the orthogonal matching pursuitalgorithm, a new algorithm based on the Dice matching criterion is proposed. The Dice similarity coefficientis introduced, to calculate the correlation coefficient of the atoms and the residual error, and is used toselect the atoms from a library. The accuracy of Spectral reconstruction based on the pseudo-inversemethod, Wiener estimation method, OMP algorithm, and DOMP algorithm is compared by simulation onthe MATLAB platform and experimental testing. The result is that spectral-reconstruction accuracy basedon the DOMP algorithm is higher than for the other three methods. The root-mean-square error and colordifference decreases with an increasing number of principal components. The reconstruction error decreasesas the number of iterations increases. Spectral reconstruction based on the DOMP algorithm can improvethe accuracy of color-information replication effectively, and high-accuracy color-information reproductioncan be realized.

Coupling reaction of carbon dioxide and epoxides efficiently catalyzed by one-component aluminum–salen complex under solvent-free conditions

Dawei Tian,Binyuan Liu,Li Zhang,Xiaoyang Wang,Wei Zhang,Lina Han,Dae Won Park 한국공업화학회 2012 Journal of Industrial and Engineering Chemistry Vol.18 No.4

Four novel bifunctional aluminum–salen complexes (2a, 2b, 2c, and 2d) containing both Lewis acidic metal center and Lewis base quaternary phosphonium salt sites within one molecule and an aluminum–salen complex with a neutral tert-butyl group (2f) for comparison were synthesized and characterized by UV–vis, IR, 1H, 13C, 27Al NMR spectroscopy and Elemental analysis (EA). Their catalytic efficiencies as single-component catalysts toward the coupling reaction of carbon dioxide and propylene oxide were evaluated. These complexes exhibit catalytic activity in the order 2d > 2a > 2b > 2c 2f. 27Al NMR spectra reveal the existence of five- and six-coordinated metal centers in the aluminum–salen complexes bearing a quaternary phosphonium salt group, whereas only five-coordinate aluminum species were found in the aluminum–salen complex with a neutral tert-butyl group. This indicates the importance of the six-coordinate aluminum center in enhancing the catalytic activity as well as an intramolecular cooperative effect in bifunctional aluminum–salen complexes 2a–d. The effects of reaction variables on the catalytic performance were investigated in detail. These new catalysts are highly stable to moisture and air and robust to impurities in the coupling reaction.

Research on Multiple-image Encryption Scheme Based on Fourier Transform and Ghost Imaging Algorithm

Zhang, Leihong,Yuan, Xiao,Zhang, Dawei,Chen, Jian Optical Society of Korea 2018 Current Optics and Photonics Vol.2 No.4

A new multiple-image encryption scheme that is based on a compressive ghost imaging concept along with a Fourier transform sampling principle has been proposed. This further improves the security of the scheme. The scheme adopts a Fourier transform to sample the original multiple-image information respectively, utilizing the centrosymmetric conjugation property of the spatial spectrum of the images to obtain each Fourier coefficient in the most abundant spatial frequency band. Based on this sampling principle, the multiple images to be encrypted are grouped into a combined image, and then the compressive ghost imaging algorithm is used to improve the security, which reduces the amount of information transmission and improves the information transmission rate. Due to the presence of the compressive sensing algorithm, the scheme improves the accuracy of image reconstruction.

Study of the Key Technology of Ghost Imaging Based on Rosette Scanning

Zhang, Leihong,Kang, Yi,Pan, Zilan,Liang, Dong,Li, Bei,Zhang, Dawei,Ma, Xiuhua Optical Society of Korea 2017 Current Optics and Photonics Vol.1 No.5

Ghost imaging offers great potential, with respect to standard imaging, for imaging objects in optically harsh or noisy environments. It can solve the problems that are difficult to solve by conventional imaging techniques. Recently, it has become a hot topic in quantum optics. In this paper, we propose a scheme for ghost imaging based on rosette scanning, named rosette ghost imaging. Sampling a small area sampling instead of the whole object, the instantaneous field of view of rosette scanning is used as the modulation light field in ghost imaging. This scheme reduces energy loss, the number of samples, and the sampling time, while improving the quality of the reconstructed image.

Simulation Model for the Decision-Making Behavior in Pedestrian Evacuation with Floor Field Cellular Automata Approach

Dawei Zhang,Haitao Zhu,Chong Liu 보안공학연구지원센터 2015 International Journal of Smart Home Vol.9 No.11

In order to simulate pedestrian evacuation from a room with multiple exits, an extended floor field cellular automata (CA) model is proposed to describe the decision-making behavior of pedestrians in a realistic way. The problem of the potential distortion and reciprocating route of pedestrians is solved. Meanwhile, the visual factor and the visual field are introduced to reveal the effect of visual sense on intelligent decision-making behavior of evacuees. To make the simulation more reasonable, human psychological behaviors are considered in the model, such as panic psychology, self-protection awareness, competition awareness, etc. Moreover, the width and the layout of exits are also taken into account and the critical value is obtained by simulation. The results show that the proposed CA model is efficient and realistic in the assessment of both human evacuation and building design.

One-dimensional model of freely decaying two-dimensional turbulence

Zhang Dawei 한국물리학회 2022 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.80 No.10

We construct a discrete shell model for two-dimensional turbulence that takes into account local and nonlocal interactions between velocity modes in Fourier space. In real space, its continuous limit is described by the one-dimensional Burgers equation. We fnd a novel approximate scaling solution of such an equation and show that it well describes the main characteristics of the energy spectrum in fully developed, freely decaying two-dimensional turbulence.

A New FE Modeling Method for Isothermal Local Loading Process of Large-scale Complex Titanium Alloy Components Based on DEFORM-3D

Dawei Zhang,He Yang,Zhichao Sun,Xiaoguang Fan 한국소성가공학회 2010 기타자료 Vol.2010 No.6

Isothermal local loading process provides a new way to form large-scale complex titanium alloy components. The forming process is characterized by an extreme size (large scale in global and compared small size in regional), multi-parameter effects, and complicated loading path. To establish a reasonable finite element model is one of the key problems urgently to be solved in the research and development of isothermal local loading forming process of largescale complex titanium alloy components. In this paper, a new finite element model of the isothermal local loading process is developed under the DEFORM-3D environment based on the solution of some key techniques. The modeling method has the following features: (1) different meshing techniques are used in different loading areas and the number of meshed elements is determined according to the deformation characteristic in different local loading steps in order to improve computational efficiency; (2) the accurate magnitude of the friction factor under titanium alloy hot forming (isothermal forming) condition is adopted instead of the typical value for lubricated hot forming processes; (3) different FEM solvers are chosen at different stages according to the loading characteristic and the contact state; (4) in contrast to the local component model, a full 3D component is modeled to simulate the process. The 3D-FE model is validated by experimental data of a large-scale bulkhead forming under isothermal local loading. The model can describe the quantitative relationships between the forming conditions and the forming results. The results of the present study may provide a basis for studying the local deformation mechanism, selecting the reasonable parameters, optimizing the die design and the process control in isothermal local loading process of large-scale complex titanium alloy components.

Research on Camouflaged Encryption Scheme Based on Hadamard Matrix and Ghost Imaging Algorithm

Zhang Leihong,Wang Yang,Ye Hualong,Xu Runchu,Zhang Dawei 한국광학회 2021 Current Optics and Photonics Vol.5 No.6

A camouflaged encryption scheme based on Hadamard matrix and ghost imaging is proposed. In the process of the encryption, an orthogonal matrix is used as the projection pattern of ghost imaging to improve the definition of the reconstructed images. The ciphertext of the secret image is constrained to the camouflaged image. The key of the camouflaged image is obtained by the method of sparse decomposition by principal component orthogonal basis and the constrained ciphertext. The information of the secret image is hidden into the information of the camouflaged image which can improve the security of the system. In the decryption process, the authorized user needs to extract the key of the secret image according to the obtained random sequences. The real encrypted information can be obtained. Otherwise, the obtained image is the camouflaged image. In order to verify the feasibility, security and robustness of the encryption system, binary images and gray-scale images are selected for simulation and experiment. The results show that the proposed encryption system simplifies the calculation process, and also improves the definition of the reconstructed images and the security of the encryption system.