首先在多分辨四叉树上定义了一个广义多分辨似然比,刻画并且累积了SAR(syntheticaperture radar)图像中目标与背景在不同分辨率上的差异,从而增大了目标与背景之间的区分度。为了达到图像无监督分割目的,提出一个有效的空间变化混合多...首先在多分辨四叉树上定义了一个广义多分辨似然比,刻画并且累积了SAR(syntheticaperture radar)图像中目标与背景在不同分辨率上的差异,从而增大了目标与背景之间的区分度。为了达到图像无监督分割目的,提出一个有效的空间变化混合多尺度自回归(spatially variantm ixture m u ltiscale autoregressive简称SVMMAR)模型方法,利用该模型分别估计出每个分辨率上广义多分辨似然比中一组密度函数的参数。为了考虑被分类象素与周围象素之间的M arkov性,减弱对噪声的敏感性,利用开窗技术来确定中心象素点的类别。实验中与通常的分割技术作了比较,也表明该方法不论从分割的精度,对噪声的敏感度,还是从边缘的光滑度都表明该方法具有较强优势。展开更多
The author＇s proposal is to show how an apparently marginal text by Walter Benjamin, ＂The Destructive Character＂, can be taken as a hermeneutic model for understanding the connection of Benjamin＇s with history and...The author＇s proposal is to show how an apparently marginal text by Walter Benjamin, ＂The Destructive Character＂, can be taken as a hermeneutic model for understanding the connection of Benjamin＇s with history and tradition and for characterizing his thought as philosophy of threshold. It is the author＇s intention to show how the destructive character, on the threshold between destruction and construction, succeeds in remaining in that transition area that announces a change, showing its creative and conservative features; thus it appears as a figure of coexistence between stillness and movement, passage and interruption, and past and future. What the author wants to point out is that, in the description of this figure, Benjamin is driven by a cognitive demand, which tends to focalize the process of destruction itself rather than the result of the destruction process. The space in which the destructive character is acting is the space of the possibility of change and emancipation, and the space where it is possible to keep together past and future, and memory and redemption. Starting from these reflections, an important question arises about the problem of the relation between history and tradition, and culture and its memory： Neither the destruction of memory by a culture nor its canonization is meaningful. The concept of destructive character then represents a preferential point of observation for analyzing the articulations of Benjamin＇s thought. From this perspective, a decisive point of Benjamin＇s reflection seems to emerge on one side, strengthened in the permeation of Hebraic ancestors between destruction and salvation; on the other side, some of the concepts and images of the Berliner philosopher seem to show up in a new light.展开更多
The simulation results of Typhoon Matsa （2005） by using the Weather Research and Forecasting （WRF） model show that pro- nounced stratospheric gravity waves （GWs） are generated in the vicinity of the typhoon. Usi...The simulation results of Typhoon Matsa （2005） by using the Weather Research and Forecasting （WRF） model show that pro- nounced stratospheric gravity waves （GWs） are generated in the vicinity of the typhoon. Using the model output, we investi- gate the spatial structures and the temporal variations of the GWs through a three dimensional （3-d） spectral analysis, i.e. the spectrum with respect to two horizontal wavenumbers and frequency. We further derive the momentum flux carried by the GWs. Spectral investigation results show that the power spectral density （PSD） of the GWs exhibits a single-peaked spectrum, which consists primarily of a distinct spectrum at horizontal wavelength of -1000 km, time period of 12-18 h, and vertical wavelength of 7-9 kin. This spectrum is different from the spectra of GWs generated by deep convections disclosed by the previous researches. Both the PSD and momentum flux spectrum are prominent in positive kh portion, which is consistent with the fact that the GWs propagate in the upstream of mean flow. Large momentum flux is found to be associated with the GWs, and the net zonal momentum flux is 0.7845×10-3 Pa at 20 km height, which can account for -26% of the momentum flux that is required in driving the QBO phenomenon.展开更多
文摘首先在多分辨四叉树上定义了一个广义多分辨似然比,刻画并且累积了SAR(syntheticaperture radar)图像中目标与背景在不同分辨率上的差异,从而增大了目标与背景之间的区分度。为了达到图像无监督分割目的,提出一个有效的空间变化混合多尺度自回归(spatially variantm ixture m u ltiscale autoregressive简称SVMMAR)模型方法,利用该模型分别估计出每个分辨率上广义多分辨似然比中一组密度函数的参数。为了考虑被分类象素与周围象素之间的M arkov性,减弱对噪声的敏感性,利用开窗技术来确定中心象素点的类别。实验中与通常的分割技术作了比较,也表明该方法不论从分割的精度,对噪声的敏感度,还是从边缘的光滑度都表明该方法具有较强优势。
文摘The author＇s proposal is to show how an apparently marginal text by Walter Benjamin, ＂The Destructive Character＂, can be taken as a hermeneutic model for understanding the connection of Benjamin＇s with history and tradition and for characterizing his thought as philosophy of threshold. It is the author＇s intention to show how the destructive character, on the threshold between destruction and construction, succeeds in remaining in that transition area that announces a change, showing its creative and conservative features; thus it appears as a figure of coexistence between stillness and movement, passage and interruption, and past and future. What the author wants to point out is that, in the description of this figure, Benjamin is driven by a cognitive demand, which tends to focalize the process of destruction itself rather than the result of the destruction process. The space in which the destructive character is acting is the space of the possibility of change and emancipation, and the space where it is possible to keep together past and future, and memory and redemption. Starting from these reflections, an important question arises about the problem of the relation between history and tradition, and culture and its memory： Neither the destruction of memory by a culture nor its canonization is meaningful. The concept of destructive character then represents a preferential point of observation for analyzing the articulations of Benjamin＇s thought. From this perspective, a decisive point of Benjamin＇s reflection seems to emerge on one side, strengthened in the permeation of Hebraic ancestors between destruction and salvation; on the other side, some of the concepts and images of the Berliner philosopher seem to show up in a new light.
基金supported by Key Research Program of the Chinese Academy of Sciences (Grant No. KZZD-EW-01-1)National Basic Research Program of China (Grant No. 2010CB428603)National Natural Science Foundation of China (Grant No. 41075028)
文摘The simulation results of Typhoon Matsa （2005） by using the Weather Research and Forecasting （WRF） model show that pro- nounced stratospheric gravity waves （GWs） are generated in the vicinity of the typhoon. Using the model output, we investi- gate the spatial structures and the temporal variations of the GWs through a three dimensional （3-d） spectral analysis, i.e. the spectrum with respect to two horizontal wavenumbers and frequency. We further derive the momentum flux carried by the GWs. Spectral investigation results show that the power spectral density （PSD） of the GWs exhibits a single-peaked spectrum, which consists primarily of a distinct spectrum at horizontal wavelength of -1000 km, time period of 12-18 h, and vertical wavelength of 7-9 kin. This spectrum is different from the spectra of GWs generated by deep convections disclosed by the previous researches. Both the PSD and momentum flux spectrum are prominent in positive kh portion, which is consistent with the fact that the GWs propagate in the upstream of mean flow. Large momentum flux is found to be associated with the GWs, and the net zonal momentum flux is 0.7845×10-3 Pa at 20 km height, which can account for -26% of the momentum flux that is required in driving the QBO phenomenon.
