Beyond-5G(B5G)aims to meet the growing demands of mobile traffic and expand the communication space.Considering that intelligent applications to B5G wireless communications will involve security issues regarding user ...Beyond-5G(B5G)aims to meet the growing demands of mobile traffic and expand the communication space.Considering that intelligent applications to B5G wireless communications will involve security issues regarding user data and operational data,this paper analyzes the maximum capacity of the multi-watermarking method for multimedia signal hiding as a means of alleviating the information security problem of B5G.The multiwatermarking process employs spread transform dither modulation.During the watermarking procedure,Gram-Schmidt orthogonalization is used to obtain the multiple spreading vectors.Consequently,multiple watermarks can be simultaneously embedded into the same position of a multimedia signal.Moreover,the multiple watermarks can be extracted without affecting one another during the extraction process.We analyze the effect of the size of the spreading vector on the unit maximum capacity,and consequently derive the theoretical relationship between the size of the spreading vector and the unit maximum capacity.A number of experiments are conducted to determine the optimal parameter values for maximum robustness on the premise of high capacity and good imperceptibility.展开更多
In all countries the political decisions aim to achieve an almost stable configuration with a small number of new infected individuals per day due to Covid-19.When such a condition is reached,the containment effort is...In all countries the political decisions aim to achieve an almost stable configuration with a small number of new infected individuals per day due to Covid-19.When such a condition is reached,the containment effort is usually reduced in favor of a gradual reopening of the social life and of the various economical sectors.However,in this new phase,the infection spread restarts and,moreover,possible mutations of the virus give rise to a large specific growth rate of the infected people.Therefore,a quantitative analysis of the regrowth pattern is very useful.We discuss a macroscopic approach which,on the basis of the collected data in the first lockdown,after few days from the beginning of the new phase,outlines different scenarios of the Covid-19 diffusion for longer time.The purpose of this paper is a demonstration-of-concept:one takes simple growth models,considers the available data and shows how the future trend of the spread can be obtained.The method applies a time dependent carrying capacity,analogously to many macroscopic growth laws in biology,economics and population dynamics.The illustrative cases of France,Italy and United Kingdom are analyzed.展开更多
随着人们对通信容量需求的不断增长,设计具有互相关旁瓣小,数目众多的扩频序列成为研究的热点。将混沌映射引入扩频序列的设计,具有保密能力强,序列数目众多等优点。设计一种新型的基于T an t映射量化的二值混沌序列,给定不同的初值,就...随着人们对通信容量需求的不断增长,设计具有互相关旁瓣小,数目众多的扩频序列成为研究的热点。将混沌映射引入扩频序列的设计,具有保密能力强,序列数目众多等优点。设计一种新型的基于T an t映射量化的二值混沌序列,给定不同的初值,就可以产生不同的扩频序列,它具有良好的负自相关特性,相对于高斯白序列可以提高14.3%的系统容量。仿真结果显示,仿真结果与理论值接近,非常适合作系统的扩频码。展开更多
This study presents various approaches to calculating the bearing capacity of spread footings applied to the rock mass of the western corniche at the tip of the Dakar peninsula. The bearing capacity was estimated usin...This study presents various approaches to calculating the bearing capacity of spread footings applied to the rock mass of the western corniche at the tip of the Dakar peninsula. The bearing capacity was estimated using empirical, analytical and numerical approaches based on the parameters of the rock mass and the foundation. Laboratory tests were carried out on basanite, as well as on the other facies detected. The results of these studies give a range of allowable bearing capacity values varying between 1.92 and 11.39 MPa for the empirical methods and from 7.13 to 25.50 MPa for the analytical methods. A wide dispersion of results was observed according to the different approaches. This dispersion of results is explained by the use of different rock parameters depending on the method used. The allowable bearing capacity results obtained with varying approaches of calculation remain admissible to support the loads. On the other hand, the foundation calculations show acceptable settlement of the order of a millimeter for all the layers, especially in the thin clay layers resting on the bedrock at shallow depths, where the rigidity of the rock reduces settlement.展开更多
基金funded by The National Natural Science Foundation of China under Grant(No.62273108,62306081)The Youth Project of Guangdong Artificial Intelligence and Digital Economy Laboratory(Guangzhou)(PZL2022KF0006)+3 种基金The National Key Research and Development Program of China(2022YFB3604502)Special Fund Project of GuangzhouScience and Technology Innovation Development(202201011307)Guangdong Province Industrial Internet Identity Analysis and Construction Guidance Fund Secondary Node Project(1746312)Special Projects in Key Fields of General Colleges and Universities in Guangdong Province(2021ZDZX1016).
文摘Beyond-5G(B5G)aims to meet the growing demands of mobile traffic and expand the communication space.Considering that intelligent applications to B5G wireless communications will involve security issues regarding user data and operational data,this paper analyzes the maximum capacity of the multi-watermarking method for multimedia signal hiding as a means of alleviating the information security problem of B5G.The multiwatermarking process employs spread transform dither modulation.During the watermarking procedure,Gram-Schmidt orthogonalization is used to obtain the multiple spreading vectors.Consequently,multiple watermarks can be simultaneously embedded into the same position of a multimedia signal.Moreover,the multiple watermarks can be extracted without affecting one another during the extraction process.We analyze the effect of the size of the spreading vector on the unit maximum capacity,and consequently derive the theoretical relationship between the size of the spreading vector and the unit maximum capacity.A number of experiments are conducted to determine the optimal parameter values for maximum robustness on the premise of high capacity and good imperceptibility.
文摘In all countries the political decisions aim to achieve an almost stable configuration with a small number of new infected individuals per day due to Covid-19.When such a condition is reached,the containment effort is usually reduced in favor of a gradual reopening of the social life and of the various economical sectors.However,in this new phase,the infection spread restarts and,moreover,possible mutations of the virus give rise to a large specific growth rate of the infected people.Therefore,a quantitative analysis of the regrowth pattern is very useful.We discuss a macroscopic approach which,on the basis of the collected data in the first lockdown,after few days from the beginning of the new phase,outlines different scenarios of the Covid-19 diffusion for longer time.The purpose of this paper is a demonstration-of-concept:one takes simple growth models,considers the available data and shows how the future trend of the spread can be obtained.The method applies a time dependent carrying capacity,analogously to many macroscopic growth laws in biology,economics and population dynamics.The illustrative cases of France,Italy and United Kingdom are analyzed.
文摘随着人们对通信容量需求的不断增长,设计具有互相关旁瓣小,数目众多的扩频序列成为研究的热点。将混沌映射引入扩频序列的设计,具有保密能力强,序列数目众多等优点。设计一种新型的基于T an t映射量化的二值混沌序列,给定不同的初值,就可以产生不同的扩频序列,它具有良好的负自相关特性,相对于高斯白序列可以提高14.3%的系统容量。仿真结果显示,仿真结果与理论值接近,非常适合作系统的扩频码。
文摘This study presents various approaches to calculating the bearing capacity of spread footings applied to the rock mass of the western corniche at the tip of the Dakar peninsula. The bearing capacity was estimated using empirical, analytical and numerical approaches based on the parameters of the rock mass and the foundation. Laboratory tests were carried out on basanite, as well as on the other facies detected. The results of these studies give a range of allowable bearing capacity values varying between 1.92 and 11.39 MPa for the empirical methods and from 7.13 to 25.50 MPa for the analytical methods. A wide dispersion of results was observed according to the different approaches. This dispersion of results is explained by the use of different rock parameters depending on the method used. The allowable bearing capacity results obtained with varying approaches of calculation remain admissible to support the loads. On the other hand, the foundation calculations show acceptable settlement of the order of a millimeter for all the layers, especially in the thin clay layers resting on the bedrock at shallow depths, where the rigidity of the rock reduces settlement.
