The sphere is a common object in uncountable engineering problems, which not only appears in structural elements like domes but also in thousands of mechanisms normally used in diverse kinds of machines. To design, ca...The sphere is a common object in uncountable engineering problems, which not only appears in structural elements like domes but also in thousands of mechanisms normally used in diverse kinds of machines. To design, calculate and analyze the behaviour on service of spherical elements, it is essential to have a good method to create an ordered group of discrete points of the spherical surface from the parametric equations commonly used to define the sphere continuously. One of the best known and widely used in high-level programming environment is MATLAB. The programming language has thousands of functions, lots of them specially designed for engineering processes. One of these functions generates a sphere knowing a given radius and shows the result. Nevertheless, this function is really imprecise because it is based on parallels and meridians besides the obtained vertices do not keep a constant distance each other. This causes the fact that it would be appropriate to design a new function to generate accurate discrete approximations of the sphere. The objective of this paper is to create a low-level function in MATLAB to obtain a discrete sphere with high regularity and high approximation in order to provide a good base to solve sphere-based engineering problems. To ensure a perfect symmetry and high regularity platonic bodies, MATLAB will be used as a base to divide the continuous spherical surface in a finite number of regular triangles. The obtained results for the different seed bodies will be represented graphically and compared to each other. The accuracy of each method will be evaluated and compared too.展开更多
The background of Captain Corelli's Mandolin is based on World War II. When the war provoked on the Greek Island, the Greeks fight against the Italian Fascist and live a tough life with their love. This article ma...The background of Captain Corelli's Mandolin is based on World War II. When the war provoked on the Greek Island, the Greeks fight against the Italian Fascist and live a tough life with their love. This article mainly talks about the essence of the Platonic love revealed in the book. By analyzing the description about homosexuality and heterosexuality in the book, this article acclaims the essence of the Platonic love——the noble abstention of lust-based love and the truth, kindness and beauty of love.展开更多
The influence of particle characteristics,such as shape,size,and volume fraction,on the permeability of porous media was investigated by combining the randomly packed beds of Platonic particles with the lattice Boltzm...The influence of particle characteristics,such as shape,size,and volume fraction,on the permeability of porous media was investigated by combining the randomly packed beds of Platonic particles with the lattice Boltzmann method.Quantitative solutions of the permeability as a function of these characteristic parameters in mono-sized particle packing structures were obtained.The D3Q19 model is presented here,which was tested by three simple benchmark tests.A series of packed beds of Platonic particles as well as spherical particles were generated in a random manner.Numerical studies on factors influencing the permeability of materials were carried out to comprehensively study their impacts.The results revealed that the permeability significantly increased with increasing equivalent diameter of the particles(or decreasing volume fraction).At a fixed size and volume fraction of particles,the permeability of the Platonic particle packing structures was also influenced by particle morphology:permeability significantly reduced as the particle sphericity decreased.The permeability of tetrahedral particle packing structures dropped by more than 40%compared with that of corresponding spherical particle systems.展开更多
We investigate the orientably regular non-abelian coverings of regular maps.A complete classification of dihedral coverings of the Platonic maps for branching over faces(or,dually,vertices)is given.As a result,we gene...We investigate the orientably regular non-abelian coverings of regular maps.A complete classification of dihedral coverings of the Platonic maps for branching over faces(or,dually,vertices)is given.As a result,we generalise the results of Jones and Surowski on regular cyclic coverings of the Platonic maps.展开更多
Initiation was one of the most substantial experiences undergone in Antiquity.The term Les rites de passage introduced by Arnold van Gennep,accommodates the multifaceted significance of initiation in the social struct...Initiation was one of the most substantial experiences undergone in Antiquity.The term Les rites de passage introduced by Arnold van Gennep,accommodates the multifaceted significance of initiation in the social structure.The two main aspects of initiation were defined as the social and that which belonged to the religious sphere;or,the profane and the sacred.Initiation or rites of passage in the social realm were intended to delineate the transition from childhood to adult status,while the sacred initiation was intended to promise eternal life and a merging with the divine.As van Gennep has indicated,however,acts of apprenticeship of any kind were enveloped in ceremonies,since no act was entirely free of the sacred.Sacred initiations were intended to remain secret in Antiquity,thus explicit depictions of sacred rituals are rare in ancient art.As this study will demonstrate,however,signifiers of such initiation can nonetheless be found in Roman wall paintings and mosaics depicting mythological protagonists.The point of departure here is that initiation is the main issue manifested metaphorically in the depictions under discussion,with the sacred initiation rather than the social mostly featuring in the visual images.The analysis is based on literary and philosophical sources,and focuses on four personalities:Narcissus,Endymion,and Achilles,who are represented in their mythological context on wall paintings from Pompeii,and Heracles,who is shown in Roman mosaics in a scene familiar as the“Drinking Contest between Heracles and Dionysus”.展开更多
文摘The sphere is a common object in uncountable engineering problems, which not only appears in structural elements like domes but also in thousands of mechanisms normally used in diverse kinds of machines. To design, calculate and analyze the behaviour on service of spherical elements, it is essential to have a good method to create an ordered group of discrete points of the spherical surface from the parametric equations commonly used to define the sphere continuously. One of the best known and widely used in high-level programming environment is MATLAB. The programming language has thousands of functions, lots of them specially designed for engineering processes. One of these functions generates a sphere knowing a given radius and shows the result. Nevertheless, this function is really imprecise because it is based on parallels and meridians besides the obtained vertices do not keep a constant distance each other. This causes the fact that it would be appropriate to design a new function to generate accurate discrete approximations of the sphere. The objective of this paper is to create a low-level function in MATLAB to obtain a discrete sphere with high regularity and high approximation in order to provide a good base to solve sphere-based engineering problems. To ensure a perfect symmetry and high regularity platonic bodies, MATLAB will be used as a base to divide the continuous spherical surface in a finite number of regular triangles. The obtained results for the different seed bodies will be represented graphically and compared to each other. The accuracy of each method will be evaluated and compared too.
文摘The background of Captain Corelli's Mandolin is based on World War II. When the war provoked on the Greek Island, the Greeks fight against the Italian Fascist and live a tough life with their love. This article mainly talks about the essence of the Platonic love revealed in the book. By analyzing the description about homosexuality and heterosexuality in the book, this article acclaims the essence of the Platonic love——the noble abstention of lust-based love and the truth, kindness and beauty of love.
基金The authors gratefully acknowledge financial support from the National Natural Science Foundation of Chinavia GrantNos.51461135001,51878152 and the Ministry of Science and Technology of China 973 Plan via Grant No.2015CB655102.
文摘The influence of particle characteristics,such as shape,size,and volume fraction,on the permeability of porous media was investigated by combining the randomly packed beds of Platonic particles with the lattice Boltzmann method.Quantitative solutions of the permeability as a function of these characteristic parameters in mono-sized particle packing structures were obtained.The D3Q19 model is presented here,which was tested by three simple benchmark tests.A series of packed beds of Platonic particles as well as spherical particles were generated in a random manner.Numerical studies on factors influencing the permeability of materials were carried out to comprehensively study their impacts.The results revealed that the permeability significantly increased with increasing equivalent diameter of the particles(or decreasing volume fraction).At a fixed size and volume fraction of particles,the permeability of the Platonic particle packing structures was also influenced by particle morphology:permeability significantly reduced as the particle sphericity decreased.The permeability of tetrahedral particle packing structures dropped by more than 40%compared with that of corresponding spherical particle systems.
文摘We investigate the orientably regular non-abelian coverings of regular maps.A complete classification of dihedral coverings of the Platonic maps for branching over faces(or,dually,vertices)is given.As a result,we generalise the results of Jones and Surowski on regular cyclic coverings of the Platonic maps.
文摘Initiation was one of the most substantial experiences undergone in Antiquity.The term Les rites de passage introduced by Arnold van Gennep,accommodates the multifaceted significance of initiation in the social structure.The two main aspects of initiation were defined as the social and that which belonged to the religious sphere;or,the profane and the sacred.Initiation or rites of passage in the social realm were intended to delineate the transition from childhood to adult status,while the sacred initiation was intended to promise eternal life and a merging with the divine.As van Gennep has indicated,however,acts of apprenticeship of any kind were enveloped in ceremonies,since no act was entirely free of the sacred.Sacred initiations were intended to remain secret in Antiquity,thus explicit depictions of sacred rituals are rare in ancient art.As this study will demonstrate,however,signifiers of such initiation can nonetheless be found in Roman wall paintings and mosaics depicting mythological protagonists.The point of departure here is that initiation is the main issue manifested metaphorically in the depictions under discussion,with the sacred initiation rather than the social mostly featuring in the visual images.The analysis is based on literary and philosophical sources,and focuses on four personalities:Narcissus,Endymion,and Achilles,who are represented in their mythological context on wall paintings from Pompeii,and Heracles,who is shown in Roman mosaics in a scene familiar as the“Drinking Contest between Heracles and Dionysus”.
