Effects of spatial noncommutativity on energy spectrum of a trapped Bose-Einstein condensate

In noncommutative space, we examine the problem of a noninteracting and harmonically trapped Bose-Einstein condensate, and derive a simple analytic expression for the effect of spatial noncommutativity on energy spectrum of the condensate. It indicates that the ground-state energy incorporating the spatial noncommutativity is reduced to a lower level, which depends upon the noncommutativity parameter $\theta$. The appeared gap between the noncommutative space and commutative one for the ground-state level of the condensate should be a signal of spatial noncommutativity.Comment: 7 pages; revtex

Discussion on Effective Approaches of Universities Fixed Assets Management

The universities fixed asset is one of important constituents of the state asset and is the material base for the universities to develop the education and enhance education quality and the scientific research level as well. Strengthening the universities fixed asset management is not only the universitie’s own development request, is also the need of organizational reform of universities education. This article embarks from the analysis of existence problems in currentuniversities fixed asset management, researches and explores the effective approaches to strengthen the universities fixed assets management. Key words: Universities, fixed assets, management, effective approaches Résumé: Les biens immobilisés des universités sont une des composants de l’actif national et la base matérielle pour les universités de développer l’éducation et élever la qualité éducative ainsi que le niveau de recherche scientifique. Le renforcement du management des biens immobilisés des universités est non seulement l’exigence du développement de l’université, mais également la demande de la réforme organisationnelle de l’éducation universitaire. L’article présent, commençant par l’analyse des problèmes existants dans la management actuel des biens immobilisés universitaires, étudie les méthodes effectives de renforcer le management dans ce domaine. Mots-Clés: universités, biens immobilisés, management, méthodes effective

Deciphering a novel image cipher based on mixed transformed Logistic maps

Since John von Neumann suggested utilizing Logistic map as a random number generator in 1947, a great number of encryption schemes based on Logistic map and/or its variants have been proposed. This paper re-evaluates the security of an image cipher based on transformed logistic maps and proves that the image cipher can be deciphered efficiently under two different conditions: 1) two pairs of known plain-images and the corresponding cipher-images with computational complexity of $O(2^{18}+L)$; 2) two pairs of chosen plain-images and the corresponding cipher-images with computational complexity of $O(L)$, where $L$ is the number of pixels in the plain-image. In contrast, the required condition in the previous deciphering method is eighty-seven pairs of chosen plain-images and the corresponding cipher-images with computational complexity of $O(2^{7}+L)$. In addition, three other security flaws existing in most Logistic-map-based ciphers are also reported.Comment: 10 pages, 2 figure

Stochastic modelling of hygrothermal performance of highly insulated wood framed walls

Recent years, the majority of building codes in North America require an energy efficient envelope to improve the building energy efficiency. There are different design strategies to achieve a higher insulation level of the wood framed building envelope, such as increasing the depth of stud cavity to accommodate thicker insulation or adding an exterior insulation while keeping the depth of stud cavity unchanged. However, the highly insulated walls may lead to a higher risk of moisture problems. The deep cavity walls will reduce the temperature of the wood sheathing, which may increase the potential for condensation and mold growth. The exterior insulated walls may result in a low drying capacity of the wood sheathing if the exterior insulation has a low vapour permeance. Although hygrothermal simulations have been widely used to investigate the moisture performance of wood framed walls, the uncertainty of the input parameters may lead to discrepancies between simulation results and real performance of the walls. This paper investigates the hygrothermal performance of highly insulated wood framed walls- deep cavity wall and exterior insulated wall using a stochastic simulation approach. The uncertainties of the input parameters including the material properties, air leakage and rain leakage rates are taken into account in stochastic modelling. The mold growth risks of the walls are evaluated based on the stochastic simulation results