A Novel Scheme for Image Encryption Based on Piecewise Linear Chaotic Map

Abstract-Recently, the chaos based cryptographic algorithms have suggested some meaningful techniques to develop efficient image encryption schemes. In this paper, we propose a new digital image encryption scheme based on the piecewise linear chaotic map (PWLCM) in order to meet the requirements of the secure encryption. The proposed scheme is described in detail, along with the security analyses including key space analysis, sensitivity analysis, information entropy analysis and differential attack analysis. The results show that the suggested image encryption scheme has some properties desirable in a good security cryptosystem

Spectroscopic super-resolution fluorescence cell imaging using ultra-small Ge quantum dots

QMUL/CSC scholarship (2011611045); BBSRC grant (BB/J001473/1)

Comprehensive Influence Model of Preschool Children’s Personality Development Based on the Bayesian Network

It is crucial to ascertain the comprehensive influence factors on personality for making effective cultivating plan. However, most existing literatures focus on the effect of individual factor on the personality. In order to comprehensively investigate the causal influences of preschool children’s temperament, school factors (teacher expectation and peer acceptance), and family factors (parental coparenting style, parental education value, and parental parenting style) on the personality and the probability of the dependencies among these influence factors, we constructed the influencing factor model of personality development based on the Bayesian network. The models not only reflect the influence on personality development as a whole, but also obtain the probability relationships among the factors. Compared with other influence factors including family and school factors, temperament has more effect on the personality. In addition, teacher expectation also has an important influence on the personality. The experimental results show that it is a valuable exploration to construct the Bayesian network for comprehensively investigating the causal relationships between preschool children’s personality and related influence factors. Further, these results will be helpful to the cultivation of healthy personality

Green's function and Pointwise Behavior of the One-Dimensional Vlasov-Maxwell-Boltzmann System

The pointwise space-time behavior of the Green's function of the one-dimensional Vlasov-Maxwell-Boltzmann (VMB) system is studied in this paper. It is shown that the Green's function consists of the macroscopic diffusive waves and Huygens waves with the speed $\pm \sqrt{5/3}$ at low-frequency, the hyperbolic waves with the speed $\pm 1$ at high-frequency, the singular kinetic and leading short waves, and the remaining term decaying exponentially in space and time. Note that these high-frequency hyperbolic waves are completely new and can not be observed for the Boltzmann equation and the Vlasov-Poisson-Boltzmann system. In addition, we establish the pointwise space-time estimate of the global solution to the nonlinear VMB system based on the Green's function. Compared to the Boltzmann equation and the Vlasov-Poisson-Boltzmann system, some new ideas are introduced to overcome the difficulties caused by the coupling effects of the transport of particles and the rotating of electro-magnetic fields, and investigate the new hyperbolic waves and singular leading short waves

Selecting ecologically appropriate scales to assess landscape ecological risk in megacity Beijing, China

Assessing the landscape ecological risk (LER) will facilitate optimal planning of land-use patterns and mitigating regional ecological risks, especially in megacities under rapid urbanization. And selecting the appropriate spatial analysis scales is the prerequisite for accurate assessment of the LER. In this study, we demonstrate the spatio-temporal dynamics of LER by determining the appropriate spatial scales in Beijing, China from 2000 to 2020. The results indicate that a granularity of 50 m and a magnitude of 5 km are optimal for regional LER assessment. The study area had predominantly medium risks, with medium, high and higher risks accounting for approximately 70% that revealed LER was at high level. Fortunately, the high and higher risks decreased by 14.64% while low and lower risks increased by 16.62% over the past two decades, which indicated LER was on a general downward trend. The LER pattern varies from east to west, with high and higher risks clustered in the northeast and southeast of the city center, and gradually dispersing elsewhere. In contrast, low and lower risks were predominantly in the city center and western regions, expanding outward from the city center. The LER was low in built-up land and cropland in the central city, but relatively high in areas away from it. The urban fringe areas dominated by woodland and grassland exhibited a high LER. The regional LER differentiation is spatially correlated with urban expressways and significant changes in LER were predominantly observed in areas adjacent to urban expressways. Specifically, the expansion of low and lower risks occurred outward along the ring roads of Beijing, and a typical case was that the lower risks were primarily enclosed by the fifth ring road in 2000 and gradually expanded towards the areas near the sixth ring road by 2020. Moreover, the LER manifests obvious spatial agglomeration influenced by human disturbance, with apparent high-high and low-low agglomerations. It is suggested to implement landscape optimization by enhancing the landscape diversity and connectivity to effectively mitigate ecological risks. These findings will provide scientific reference for researches aimed at mitigating ecological risks and fostering high-quality sustainable development in metropolitan areas