The face velocities of the high efficiency particulate air filters and the ultra low penetration airfilters in fan filter units (FFUs) have large relative standard deviation and turbulivity. It seriously affects the ...The face velocities of the high efficiency particulate air filters and the ultra low penetration airfilters in fan filter units (FFUs) have large relative standard deviation and turbulivity. It seriously affects the unidirectivity of the flow in the unidirectional flow clean zone and cleanroom. The cross contamination in this kind of unidirectional flow area is hardly controlled. It is significant to find optional method for keeping the face velocity uniformity of FFU and reducing the face velocity turbulivity of FFU, furthermore, to keep the cleanliness level under FFUs. The normal and easy method is to add flow rectifiers under filters. FFUs with various flow rectifiers have been tested. The uniformity and turbulivity of facevelocity under the FFU are presented in this paper. The influence of the facevelocity uniformity and turbulivity on the contamination boundary of the unidirectional flow is studiedas well.展开更多
A method of controllable internal perturbation inside the chaotic map is proposed to solve the problem in chaotic systems caused by finite precision.A chaotic system can produce large amounts of initial-sensitive,non-...A method of controllable internal perturbation inside the chaotic map is proposed to solve the problem in chaotic systems caused by finite precision.A chaotic system can produce large amounts of initial-sensitive,non-cyclical pseudo-random sequences.However,the finite precision brings short period and odd points which obstruct application of chaos theory seriously in digital communication systems.Perturbation in chaotic systems is a possible efficient method for solving finite precision problems,but former researches are limited in uniform distribution maps.The proposed internal perturbation can work on both uniform and non-uniform distribution chaotic maps like Chebyshev map and Logistic map.By simulations,results show that the proposed internal perturbation extends sequence periods and eliminates the odd points,so as to improve chaotic performances of perturbed chaotic sequences.展开更多
文摘The face velocities of the high efficiency particulate air filters and the ultra low penetration airfilters in fan filter units (FFUs) have large relative standard deviation and turbulivity. It seriously affects the unidirectivity of the flow in the unidirectional flow clean zone and cleanroom. The cross contamination in this kind of unidirectional flow area is hardly controlled. It is significant to find optional method for keeping the face velocity uniformity of FFU and reducing the face velocity turbulivity of FFU, furthermore, to keep the cleanliness level under FFUs. The normal and easy method is to add flow rectifiers under filters. FFUs with various flow rectifiers have been tested. The uniformity and turbulivity of facevelocity under the FFU are presented in this paper. The influence of the facevelocity uniformity and turbulivity on the contamination boundary of the unidirectional flow is studiedas well.
基金Supported by the National Basic Research Program of China(No.2007CB310606)
文摘A method of controllable internal perturbation inside the chaotic map is proposed to solve the problem in chaotic systems caused by finite precision.A chaotic system can produce large amounts of initial-sensitive,non-cyclical pseudo-random sequences.However,the finite precision brings short period and odd points which obstruct application of chaos theory seriously in digital communication systems.Perturbation in chaotic systems is a possible efficient method for solving finite precision problems,but former researches are limited in uniform distribution maps.The proposed internal perturbation can work on both uniform and non-uniform distribution chaotic maps like Chebyshev map and Logistic map.By simulations,results show that the proposed internal perturbation extends sequence periods and eliminates the odd points,so as to improve chaotic performances of perturbed chaotic sequences.
