A new ROMless twiddle factor generator for radix-2 1024-point FFT is proposed.It consists of several simple logic units and each of them synthesizes some data,which will be used to compose the twiddle factors.The powe...A new ROMless twiddle factor generator for radix-2 1024-point FFT is proposed.It consists of several simple logic units and each of them synthesizes some data,which will be used to compose the twiddle factors.The power analysis with Synopsys Power Compiler shows that it consumes about 2mW with TSMC 0.25μm CMOS process at 50MHz.This twiddle factor generator is designed for the low power applications,especially for the mobile communications and other portable devices...展开更多
Martens proposed a highly efficient and simply formed DFT algorithm——RCFA,whose efficien-cy is comparable with that of WFTA or that of PFA,and whose structure is similar to that of FFT.Theauthors have proved that,in...Martens proposed a highly efficient and simply formed DFT algorithm——RCFA,whose efficien-cy is comparable with that of WFTA or that of PFA,and whose structure is similar to that of FFT.Theauthors have proved that,in the case of radix 2,the RCFA is exactly equivalent to the twiddle factor mergedfrequency-decimal FFT algorithm.The twiddle factor merged time-decimal FFT algorithm is providedin this paper.Thus,in any case,the FFT algorithm used currently can be replaced by the more efficientalgorithm——the twiddle factor merged FFT algorithm,with exactly the same external property and thesimilar internal structure.Also in this paper,the software for implementing the twiddle factor merged FFTalgorithm(TMFFT)is provided.展开更多
Daily precipitation amounts from 1961 to 2005 in 35 observation stations in Liaoning Province were selected in order to study the temporal and spatial distribution of extreme precipitation events.By dint of EOF,REOF,m...Daily precipitation amounts from 1961 to 2005 in 35 observation stations in Liaoning Province were selected in order to study the temporal and spatial distribution of extreme precipitation events.By dint of EOF,REOF,mean-square-error and other ways,the changes in different regions of extreme precipitation and distribution were reflected.The analysis showed that,extreme precipitation in Liaoning Province could be divided into three areas,which were western Liaoning mountains and parts of northern areas,eastern Liaoning mountainous,near-coastal areas of Liaohe River Plain.In the relatively large precipitation areas,extreme precipitation threshold was also higher,and vice versa.The lower frequency of extreme precipitation events had a greater contribution to total precipitation;extreme precipitation,total precipitation and total rain days had the greatest changes in the summer,and the least changes in the winter;number of days of extreme precipitation changes in each season were not great;the change of extreme precipitation was not obvious in the long term.展开更多
文摘A new ROMless twiddle factor generator for radix-2 1024-point FFT is proposed.It consists of several simple logic units and each of them synthesizes some data,which will be used to compose the twiddle factors.The power analysis with Synopsys Power Compiler shows that it consumes about 2mW with TSMC 0.25μm CMOS process at 50MHz.This twiddle factor generator is designed for the low power applications,especially for the mobile communications and other portable devices...
文摘Martens proposed a highly efficient and simply formed DFT algorithm——RCFA,whose efficien-cy is comparable with that of WFTA or that of PFA,and whose structure is similar to that of FFT.Theauthors have proved that,in the case of radix 2,the RCFA is exactly equivalent to the twiddle factor mergedfrequency-decimal FFT algorithm.The twiddle factor merged time-decimal FFT algorithm is providedin this paper.Thus,in any case,the FFT algorithm used currently can be replaced by the more efficientalgorithm——the twiddle factor merged FFT algorithm,with exactly the same external property and thesimilar internal structure.Also in this paper,the software for implementing the twiddle factor merged FFTalgorithm(TMFFT)is provided.
文摘Daily precipitation amounts from 1961 to 2005 in 35 observation stations in Liaoning Province were selected in order to study the temporal and spatial distribution of extreme precipitation events.By dint of EOF,REOF,mean-square-error and other ways,the changes in different regions of extreme precipitation and distribution were reflected.The analysis showed that,extreme precipitation in Liaoning Province could be divided into three areas,which were western Liaoning mountains and parts of northern areas,eastern Liaoning mountainous,near-coastal areas of Liaohe River Plain.In the relatively large precipitation areas,extreme precipitation threshold was also higher,and vice versa.The lower frequency of extreme precipitation events had a greater contribution to total precipitation;extreme precipitation,total precipitation and total rain days had the greatest changes in the summer,and the least changes in the winter;number of days of extreme precipitation changes in each season were not great;the change of extreme precipitation was not obvious in the long term.
