A new method for efficient convolution in frequency domain by nonuniform partitioning for adaptive filtering

1996 ◽  
Vol 44 (12) ◽  
pp. 3123-3129 ◽  
Author(s):  
G.P.M. Egelmeers ◽  
P.C.W. Sommen
Keyword(s):  
Frequency Domain ◽  
Adaptive Filtering ◽  
New Method

Global Image Dehazing via Frequency Perception Filtering

2019 ◽  
Vol 28 (09) ◽  
pp. 1950142
Author(s):  
Linli Xu ◽  
Jing Han ◽  
Tian Wang ◽  
Lianfa Bai
Keyword(s):  
Frequency Domain ◽  
Adaptive Filtering ◽  
Low Frequency ◽  
Intermediate Frequency ◽  
Human Visual Perception ◽  
Image Dehazing ◽  
Weighting Factors ◽  
Outdoor Scenes ◽  
Frequency Domain Filtering ◽  
Three Components

In outdoor scenes, haze limits the visibility of images, and degrades people’s judgement of the objects. In this paper, based on an assumption of human visual perception in frequency domain, a novel image haze removal filtering is proposed. Combining this assumption with the theory of frequency domain filtering, we first estimate the cut-off frequency to divide the frequency domain of the hazy image into three components — low-frequency domain, intermediate-frequency domain and high-frequency domain. Then, by introducing the weighting factors, the three components are recombined together. After the theoretical deduction of frequency domain, the establishment of the actual model and adjusting the cut-off frequency and weighting factors, we finally acquire a global and adaptive filtering. This filtering can restore the details and the contours of the images, which have less noise, and improve the visibility of the objects in hazy images. Moreover, our method is simple in structure and strongly applicable, and rarely affected by parameters. Our algorithm is stable and performs well in heavy fog and the scene changes.

New Method for Assessment Ageing Condition of Oil Impregnated Insulation Pressboard Based on Frequency Domain Spectroscopy

2014 ◽  
Vol 513-517 ◽  
pp. 323-327 ◽  
Author(s):  
Jian Hao ◽  
Jin Fu ◽  
Pei Guo ◽  
Gao Lin Wu ◽  
Qian Wang ◽  
...  
Keyword(s):  
Dielectric Loss ◽  
Moisture Content ◽  
Frequency Domain ◽  
Condition Assessment ◽  
New Method ◽  
Time Saving ◽  
Interpolation Curve ◽  
Ageing Condition ◽  
Cellulose Insulation

It is important to assess the condition of the cellulose insulation in transformer. However, taking paper samples from a transformer is both impractical and destructive. In this paper, a new method for assessment ageing condition of oil impregnated insulation pressboard based on frequency domain spectroscopy (FDS) was proposed. The FDS measurements were taken on oil impregnated insulation pressboards with five ageing levels at moisture content of 1.22%, 2.06%, 3.02% and 3.87%. The dielectric loss of all the samples were calculated bytanδ (f)interpolationandthe ageing condition assessment database which contains data of five ageing levels and 1%-4% moisture content was built. It is found that thetanδ (f)interpolation is more sencentive to ageing and moisture. It could realize the ageing condition assessment by comparing thetanδ (f)interpolation curve with the curves in the database.The assessing result of the middle-low main insulation life of a 220kV transformer valided that it is effective and time saving to use the new method for ageing condition assessment.

On: “Correction of topographic distortions in potential‐field data: A fast and accurate approach” by Jianghai Xia, Donald R. Sprowl, and Dana Adkins‐Heljeson (April 1993 GEOPHYSICS, p. 515–523).

Geophysics ◽  
1993 ◽  
Vol 58 (12) ◽  
pp. 1874-1874
Author(s):  
David A. Chapin
Keyword(s):  
Point Source ◽  
Frequency Domain ◽  
Potential Field ◽  
Field Data ◽  
New Method ◽  
Potential Fields ◽  
Potential Field Data ◽  
Source Method ◽  
Equivalent Point ◽  
Breakthrough Technology

Xia et al. do an excellent job developing a new method for using the equivalent point source method in the frequency domain. The transformation from a varying datum to flat datum has always been a major problem in potential fields data. This is because the existing methods to perform this transformation have tended to be cumbersome, time‐consuming, and expensive. I congratulate the authors for this breakthrough technology.

Aerodynamic Forces Approximations Calculated With a New Analytical Formulation

2006 ◽  
Author(s):  
Djallel Eddine Biskri ◽  
Ruxandra Mihaela Botez
Keyword(s):  
Least Squares ◽  
Frequency Domain ◽  
Approximation Method ◽  
Unsteady Aerodynamics ◽  
Analytical Form ◽  
New Method ◽  
Aerodynamic Forces ◽  
Laplace Domain ◽  
Analytical Formulation ◽  
Multidisciplinary Study

Aeroservoelasticity is a multidisciplinary study of three main disciplines: unsteady aerodynamics, aeroelasticity and servo-controls. Two classical methods are used in the literature to approximate the unsteady generalized forces from the frequency domain Q (k) to the Laplace domain Q(s) and these methods are: the Least Squares LS and the Minimum State MS. In the present paper, we present a new method, called Corrected Minimum State (CMS), based on the Standard MS approximation method. This new CMS method uses an analytical form of the error as function of Laplace variable similar to the analytical form of the aerodynamic forces calculated with the MS method. We applied this new method to an F/A-18 aircraft and we found that the CMS method brings improvements in the approximation results in comparison with the standard MS method. It is shown that use of the CMS method on an F/A-18 aircraft will give better results in terms of convergence speeds and precision than the MS method.

Sign in / Sign up

Export Citation Format

Share Document