如何抵抗与因子分解相关的私钥获取攻击,是RSA型加密方案的一个重要研究课题.就RSA型加密方案而言,目前普遍采用的抵抗与因子分解相关的私钥获取攻击的方法是优化系统参数,但该方法是被动的.本文分析了现有的针对RSA型加密系统的与因子...如何抵抗与因子分解相关的私钥获取攻击,是RSA型加密方案的一个重要研究课题.就RSA型加密方案而言,目前普遍采用的抵抗与因子分解相关的私钥获取攻击的方法是优化系统参数,但该方法是被动的.本文分析了现有的针对RSA型加密系统的与因子分解相关的私钥获取攻击,找出这些攻击能够成功的关键因素.然后将RSA、Rabin两个加密系统与Diffie-Hellman密钥交换协议融合在一起设计了一个能抗自适应性选择密文攻击的加密方案.此方案具有如下三个属性:(1)该方案不仅能高效地实现加密操作,而且还能避免出已经出现的各种与因子分解相关的私钥获取攻击(量子算法除外);(2)该方案的私钥d的私密性具有信息论意义;(3)该方案在标准模型下,对自适应性选择密文攻击具有不可区分语义安全(indistinguishability under chosen-ciphertext attack,IDN-CCA).展开更多
The automatic seizure detection is significant for epilepsy diagnosis and it can alleviate the work intensity of inspecting prolonged electroencephalogram (EEG). This paper presents and investigates a novel machine ...The automatic seizure detection is significant for epilepsy diagnosis and it can alleviate the work intensity of inspecting prolonged electroencephalogram (EEG). This paper presents and investigates a novel machine learning approach utilizing gradient boosting to detect seizures from long-term EEG. We apply relative fluctuation index to extract features of long-term intracranial EEG data. A classifier trained with the gradient boosting algorithm is adopted to discriminate the seizure and non-seizure EEG signals. Smoothing and collar technique are finally used as post-processing in order to improve the detection accuracy further. The seizure detection method is assessed on Freiburg EEG datasets from 21 patients. The experimental results indicate that the proposed method yields an average sensitivity of 94. 60% with a false detection rate of 0. 18/h.展开更多
The effects of leaf water status in a wheat canopy on the accuracy of estimating leaf area index (LAI) and N were determined in this study using extracted spectral characteristics in the 2 000-2 300 nm region of the s...The effects of leaf water status in a wheat canopy on the accuracy of estimating leaf area index (LAI) and N were determined in this study using extracted spectral characteristics in the 2 000-2 300 nm region of the short wave infrared (SWI) band. A newly defined spectral index, relative adsorptive index in the 2000-2300 nm region (RAI2000-2300), which can be calculated by RAI2000-2300 = (R2224 - R2054) (R2224 + R2054)-1 with R being the reflectance at 2224 or 2054 nm, was utilized. This spectral index, RAI2000-2300, was significantly correlated (P < 0.01) with green LAI and leaf N concentration and proved to be potentially valuable for monitoring plant green LAI and leaf N at the field canopy scale. Moreover, plant LAI could be monitored more easily and more successfully than plant leaf N. The study also showed that leaf water had a strong masking effect on the 2 000-2 300 nm spectral characteristics and both the coefficient between RAI2000-2300 and green LAI and that between RAI2000-2300 and leaf N content decreased as leaf water content increased.展开更多
To improve the detection accuracy of the balise uplink signal transmitted in a strong noise environment,we use chaotic oscillator to detect the balise uplink signal based on the characteristics of the chaotic system t...To improve the detection accuracy of the balise uplink signal transmitted in a strong noise environment,we use chaotic oscillator to detect the balise uplink signal based on the characteristics of the chaotic system that is sensitive to initial conditions and immune to noise.Combining with the principle of Duffing oscillator system used in weak signal detection and uplink signal feature,the methods and steps of using Duffing oscillator to detect the balise signal are presented.Furthermore,the Lyapunov exponent algorithm is used to calculate the critical threshold of the Duffing oscillator detection system.Thus,the output states of the system can be quantitatively judged to achieve demodulation of the balise signal.The simulation results show that the chaotic oscillator detection method for balise signal based on Lyapunov exponent algorithm not only improves the accuracy and efficiency of threshold setting,but also ensures the reliability of balise signal detection.展开更多
AIM:To describe a condition that we define as early graft dysfunction(EGD)which can be identified preoperatively. METHODS:Small-for-size graft dysfunction following living-related liver transplantation(LRLT)is charact...AIM:To describe a condition that we define as early graft dysfunction(EGD)which can be identified preoperatively. METHODS:Small-for-size graft dysfunction following living-related liver transplantation(LRLT)is characterized by EGD when the graft-to-recipient body weight ratio(GRBWR)is below 0.8%.However, patients transplanted with GRBWR above 0.8%can develop dysfunction of the graft.In 73 recipients of LRLT(GRBWR>0.8%),we identified 10 patients who developed EGD.The main measures of outcomes analyzed were overall mortality,number of re-transplants and length of stay in days(LOS).Furthermore we analyzed other clinical pre-transplant variables,intraoperative parameters and post transplant data.RESULTS:A trend in favor of the non-EGD group(3-mo actuarial survival 98%vs 88%,P=0.09;3-mo graft mortality 4.7%vs 20%,P=0.07)was observed as well as shorter LOS(13 d vs 41.5 d;P=0.001)and smaller requirement of peri-operative Units of Plasma (4 vs 14;P=0.036).Univariate analysis of pre- transplant variables identified platelet count,serum bilirubin,INR and Meld-Na score as predictors of EGD. In the multivariate analysis transplant Meld-Na score (P=0.025,OR:1.175)and pretransplant platelet count(P=0.043,OR:0.956)were independently associated with EGD. CONCLUSION:EGD can be identified preoperatively and is associated with increased morbidity after LRLT. A prompt recognition of EGD can trigger a timely treatment.展开更多
Vegetation encroachment occurred in bauxite residue disposal area(BRDA)following natural weathering processes,whilst the typical indicators of soil formation are still uncertain.Residue samples were collected from the...Vegetation encroachment occurred in bauxite residue disposal area(BRDA)following natural weathering processes,whilst the typical indicators of soil formation are still uncertain.Residue samples were collected from the BRDA in Central China,and related physical,chemical and biological indicators of bauxite residue with different storage years were determined.The indicators of soil formation in bauxite residue were selected using principal component analysis,factor analysis,and comprehensive evaluation to establish soil quality diagnostic index model on disposal areas.Following natural weathering processes,the texture of bauxite residue changed from silty loam to sandy loam.The pH and EC decreased,whilst porosity,nutrient element content and microbial biomass increased.The identified minimum data set(MDS)included available phosphorus(AP),moisture content(MC),C/N,sand content,total nitrogen(TN),microbial biomass carbon(MBC),and pH.The soil quality index of bauxite residue increased,and the relative soil quality index decreased from 1.89 to 0.15,which indicated that natural weathering had a significant effect on improveing the quality of bauxite residue and forming a new soil-like matrix.The diagnostic model of bauxite residue was established to provide data support for the regeneration on disposal area.展开更多
Daily and ten-day Normalized Difference Vegetation Index( NDVI) of crops were retrieved from meteorological satellite NOAA AVHRR images. The temporal variations of the NDVI were analyzed during the whole growing seaso...Daily and ten-day Normalized Difference Vegetation Index( NDVI) of crops were retrieved from meteorological satellite NOAA AVHRR images. The temporal variations of the NDVI were analyzed during the whole growing season, and thus the principle of the interaction between NDVI profile and the growing status of crops was discussed. As a case in point, the relationship between integral NDVI and winter wheat yield of Henan Province in 1999 had been analyzed. By putting integral NDVI values of 60 sample counties into the winter wheat yield-integral NDVI coordination, scattering map was plotted. It demonstrated that integral NDVI had a close relation with winter wheat yield. These relation could be described with linear, cubic polynomial, and exponential regression, and the cubic polynomial regression was the best way. In general, NDVI reflects growing status of green vegetation, so crop monitoring and crop yield estimation could be realized by using remote sensing technique on the basis of time serial NDVI data together with agriculture calendars.展开更多
The techniques to forecast available parking space(APS) are indispensable components for parking guidance systems(PGS). According to the data collected in Newcastle upon Tyne, England, the changing characteristics of ...The techniques to forecast available parking space(APS) are indispensable components for parking guidance systems(PGS). According to the data collected in Newcastle upon Tyne, England, the changing characteristics of APS were studied. Thereafter, aiming to build up a multi-step APS forecasting model that provides richer information than a conventional one-step model, the largest Lyapunov exponents(largest LEs) method was introduced into PGS. By experimental tests conducted using the same dataset, its prediction performance was compared with traditional wavelet neural network(WNN) method in both one-step and multi-step processes. Based on the results, a new multi-step forecasting model called WNN-LE method was proposed, where WNN, which enjoys a more accurate performance along with a better learning ability in short-term forecasting, was applied in the early forecast steps while the Lyapunov exponent prediction method in the latter steps precisely reflect the chaotic feature in latter forecast period. The MSE of APS forecasting for one hour time period can be reduced from 83.1 to 27.1(in a parking building with 492 berths) by using largest LEs method instead of WNN and further reduced to 19.0 by conducted the new method.展开更多
The macrobenthic community of the Xiaoqing River Estuary and the adjacent sea waters was investigated in May and November 2008,August 2009,and May and September 2010,respectively.A total of 95 species of macrobenthos ...The macrobenthic community of the Xiaoqing River Estuary and the adjacent sea waters was investigated in May and November 2008,August 2009,and May and September 2010,respectively.A total of 95 species of macrobenthos were identified in the five cruises and most of them were polychaetes(46.39%),mollusks(28.86%) and crustaceans(20.62%).The Shannon-Wiener index of macrobenthos was lower than 2 in 67% sites.Along the stream channel,estuary and the coastal waters,the species of polychaetes reduced gradually,while the abundance increased at first and then decreased.The abundance was the biggest at regions with salinity of 5 20 in the estuary.The species and abundance of mollusks and crustaceans increased gradually.As for seasonal distribution,the species,abundance and biomass were higher in spring and lower in summer and autumn.Contemporaneously compared with Laizhou Bay and Yellow River Estuary,the species of macrobenthos appeared in the Xiaoqing River Estuary were much less,while the percentage of polychaetes was higher.Abundance and biomass were higher in Xiaoqing River estuary,then consequently followed by Laizhou Bay and Yellow River Estuary.The dominant species in Xiaoqing River Estuary was polychaete,and Layzhou Bay mollusk.The community structure characteristics of macrobenthos in the Xiaoqing River Estuary revealed a significant pollution status in this region.展开更多
A number of recent studies have examined trends in extreme temperature indices using a linear regression model based on ordinary least-squares. In this study, quantile regression was, for the first time, applied to ex...A number of recent studies have examined trends in extreme temperature indices using a linear regression model based on ordinary least-squares. In this study, quantile regression was, for the first time, applied to examine the trends not only in the mean but also in all parts of the distribution of several extreme temperature indices in China for the period 1960–2008. For China as a whole, the slopes in almost all the quantiles of the distribution showed a notable increase in the numbers of warm days and warm nights, and a significant decrease in the number of cool nights. These changes became much faster as the quantile increased. However, although the number of cool days exhibited a significant decrease in the mean trend estimated by classical linear regression, there was no obvious trend in the upper and lower quantiles. This finding suggests that examining the trends in different parts of the distribution of the time-series is of great importance. The spatial distribution of the trend in the 90 th quantile indicated that there was a pronounced increase in the numbers of warm days and warm nights, and a decrease in the number of cool nights for most of China, but especially in the northern and western parts of China, while there was no significant change for the number of cool days at almost all the stations.展开更多
This works examine the responses of housing prices to the monetary policies in various Chinese cities. Thirty-five large and medium sized Chinese cities are classified into six clusters applying the minimum variance c...This works examine the responses of housing prices to the monetary policies in various Chinese cities. Thirty-five large and medium sized Chinese cities are classified into six clusters applying the minimum variance clustering method according to the calculated correlation coefficients between the housing price indices of every two cities.Time difference correlation analysis is then employed to quantify the relations between the housing price indices of the six clusters and the monetary policies.It is suggested that the housing prices of various cities evolved at different paces and their responses to the monetary policies are heterogeneous,and local economic features are more important than geographic distances in determining the housing price trends.展开更多
Based on the Gauss linear frequency modulated wavelet transform, a new characteristic index is presented, namely time frequency energy attenuation factor which can reflect the difference features of waveform in earthq...Based on the Gauss linear frequency modulated wavelet transform, a new characteristic index is presented, namely time frequency energy attenuation factor which can reflect the difference features of waveform in earthquake focus mechanism, wave traveling path and its attenuation characteristics in focal area or near field. In order to test its validity, we select the natural earthquakes and explosion or collapse events whose focus mechanisms vary obviously,and some natural earthquakes located at the same site or in a very small area. The study indicates that the time frequency energy attenuation factors of the natural earthquakes are obviously different with that of explosion or collapse events, and the change of the time frequency energy attenuation factors is relatively stable for the earthquakes under the normal seismicity background. Using the above mentioned method, it is expected to offer a useful criterion for strong earthquake prediction by continuous earthquake observation.展开更多
文摘如何抵抗与因子分解相关的私钥获取攻击,是RSA型加密方案的一个重要研究课题.就RSA型加密方案而言,目前普遍采用的抵抗与因子分解相关的私钥获取攻击的方法是优化系统参数,但该方法是被动的.本文分析了现有的针对RSA型加密系统的与因子分解相关的私钥获取攻击,找出这些攻击能够成功的关键因素.然后将RSA、Rabin两个加密系统与Diffie-Hellman密钥交换协议融合在一起设计了一个能抗自适应性选择密文攻击的加密方案.此方案具有如下三个属性:(1)该方案不仅能高效地实现加密操作,而且还能避免出已经出现的各种与因子分解相关的私钥获取攻击(量子算法除外);(2)该方案的私钥d的私密性具有信息论意义;(3)该方案在标准模型下,对自适应性选择密文攻击具有不可区分语义安全(indistinguishability under chosen-ciphertext attack,IDN-CCA).
基金Key Program of Natural Science Foundation of Shandong Province(No.ZR2013FZ002)The Program of Science and Technology of Suzhou(No.ZXY2013030)Independent Innovation Foundation of Shandong University(No.11170074611102)
文摘The automatic seizure detection is significant for epilepsy diagnosis and it can alleviate the work intensity of inspecting prolonged electroencephalogram (EEG). This paper presents and investigates a novel machine learning approach utilizing gradient boosting to detect seizures from long-term EEG. We apply relative fluctuation index to extract features of long-term intracranial EEG data. A classifier trained with the gradient boosting algorithm is adopted to discriminate the seizure and non-seizure EEG signals. Smoothing and collar technique are finally used as post-processing in order to improve the detection accuracy further. The seizure detection method is assessed on Freiburg EEG datasets from 21 patients. The experimental results indicate that the proposed method yields an average sensitivity of 94. 60% with a false detection rate of 0. 18/h.
基金Project supported by the National High Technology Research and Development Program of China (863 Program)(No. 2002AA243011)the National Key Basic Research Support Foundation of China (No. G2000077907)
文摘The effects of leaf water status in a wheat canopy on the accuracy of estimating leaf area index (LAI) and N were determined in this study using extracted spectral characteristics in the 2 000-2 300 nm region of the short wave infrared (SWI) band. A newly defined spectral index, relative adsorptive index in the 2000-2300 nm region (RAI2000-2300), which can be calculated by RAI2000-2300 = (R2224 - R2054) (R2224 + R2054)-1 with R being the reflectance at 2224 or 2054 nm, was utilized. This spectral index, RAI2000-2300, was significantly correlated (P < 0.01) with green LAI and leaf N concentration and proved to be potentially valuable for monitoring plant green LAI and leaf N at the field canopy scale. Moreover, plant LAI could be monitored more easily and more successfully than plant leaf N. The study also showed that leaf water had a strong masking effect on the 2 000-2 300 nm spectral characteristics and both the coefficient between RAI2000-2300 and green LAI and that between RAI2000-2300 and leaf N content decreased as leaf water content increased.
基金National Natural Science Foundation of China(No.61763025)。
文摘To improve the detection accuracy of the balise uplink signal transmitted in a strong noise environment,we use chaotic oscillator to detect the balise uplink signal based on the characteristics of the chaotic system that is sensitive to initial conditions and immune to noise.Combining with the principle of Duffing oscillator system used in weak signal detection and uplink signal feature,the methods and steps of using Duffing oscillator to detect the balise signal are presented.Furthermore,the Lyapunov exponent algorithm is used to calculate the critical threshold of the Duffing oscillator detection system.Thus,the output states of the system can be quantitatively judged to achieve demodulation of the balise signal.The simulation results show that the chaotic oscillator detection method for balise signal based on Lyapunov exponent algorithm not only improves the accuracy and efficiency of threshold setting,but also ensures the reliability of balise signal detection.
文摘AIM:To describe a condition that we define as early graft dysfunction(EGD)which can be identified preoperatively. METHODS:Small-for-size graft dysfunction following living-related liver transplantation(LRLT)is characterized by EGD when the graft-to-recipient body weight ratio(GRBWR)is below 0.8%.However, patients transplanted with GRBWR above 0.8%can develop dysfunction of the graft.In 73 recipients of LRLT(GRBWR>0.8%),we identified 10 patients who developed EGD.The main measures of outcomes analyzed were overall mortality,number of re-transplants and length of stay in days(LOS).Furthermore we analyzed other clinical pre-transplant variables,intraoperative parameters and post transplant data.RESULTS:A trend in favor of the non-EGD group(3-mo actuarial survival 98%vs 88%,P=0.09;3-mo graft mortality 4.7%vs 20%,P=0.07)was observed as well as shorter LOS(13 d vs 41.5 d;P=0.001)and smaller requirement of peri-operative Units of Plasma (4 vs 14;P=0.036).Univariate analysis of pre- transplant variables identified platelet count,serum bilirubin,INR and Meld-Na score as predictors of EGD. In the multivariate analysis transplant Meld-Na score (P=0.025,OR:1.175)and pretransplant platelet count(P=0.043,OR:0.956)were independently associated with EGD. CONCLUSION:EGD can be identified preoperatively and is associated with increased morbidity after LRLT. A prompt recognition of EGD can trigger a timely treatment.
基金Projects(41877551,41842020)supported by the National Natural Science Foundation of China
文摘Vegetation encroachment occurred in bauxite residue disposal area(BRDA)following natural weathering processes,whilst the typical indicators of soil formation are still uncertain.Residue samples were collected from the BRDA in Central China,and related physical,chemical and biological indicators of bauxite residue with different storage years were determined.The indicators of soil formation in bauxite residue were selected using principal component analysis,factor analysis,and comprehensive evaluation to establish soil quality diagnostic index model on disposal areas.Following natural weathering processes,the texture of bauxite residue changed from silty loam to sandy loam.The pH and EC decreased,whilst porosity,nutrient element content and microbial biomass increased.The identified minimum data set(MDS)included available phosphorus(AP),moisture content(MC),C/N,sand content,total nitrogen(TN),microbial biomass carbon(MBC),and pH.The soil quality index of bauxite residue increased,and the relative soil quality index decreased from 1.89 to 0.15,which indicated that natural weathering had a significant effect on improveing the quality of bauxite residue and forming a new soil-like matrix.The diagnostic model of bauxite residue was established to provide data support for the regeneration on disposal area.
基金Under the auspices of Beijing Precision Agriculture Project of the State Development Planning Commission(A00300100584-RS02).
文摘Daily and ten-day Normalized Difference Vegetation Index( NDVI) of crops were retrieved from meteorological satellite NOAA AVHRR images. The temporal variations of the NDVI were analyzed during the whole growing season, and thus the principle of the interaction between NDVI profile and the growing status of crops was discussed. As a case in point, the relationship between integral NDVI and winter wheat yield of Henan Province in 1999 had been analyzed. By putting integral NDVI values of 60 sample counties into the winter wheat yield-integral NDVI coordination, scattering map was plotted. It demonstrated that integral NDVI had a close relation with winter wheat yield. These relation could be described with linear, cubic polynomial, and exponential regression, and the cubic polynomial regression was the best way. In general, NDVI reflects growing status of green vegetation, so crop monitoring and crop yield estimation could be realized by using remote sensing technique on the basis of time serial NDVI data together with agriculture calendars.
基金Project(2012CB725402)supported by the National Key Basic Research Program of ChinaProjects(51338003,50908051)supported by the National Natural Science Foundation of China
文摘The techniques to forecast available parking space(APS) are indispensable components for parking guidance systems(PGS). According to the data collected in Newcastle upon Tyne, England, the changing characteristics of APS were studied. Thereafter, aiming to build up a multi-step APS forecasting model that provides richer information than a conventional one-step model, the largest Lyapunov exponents(largest LEs) method was introduced into PGS. By experimental tests conducted using the same dataset, its prediction performance was compared with traditional wavelet neural network(WNN) method in both one-step and multi-step processes. Based on the results, a new multi-step forecasting model called WNN-LE method was proposed, where WNN, which enjoys a more accurate performance along with a better learning ability in short-term forecasting, was applied in the early forecast steps while the Lyapunov exponent prediction method in the latter steps precisely reflect the chaotic feature in latter forecast period. The MSE of APS forecasting for one hour time period can be reduced from 83.1 to 27.1(in a parking building with 492 berths) by using largest LEs method instead of WNN and further reduced to 19.0 by conducted the new method.
基金the Open Fund of Sandong Provincial Key Laboratory of Marine Ecology and Environment & Disaster Prevention and Mitigation(Grant No.2011007)the Major Programs of Marine Public Welfare(Grant No.201105005)
文摘The macrobenthic community of the Xiaoqing River Estuary and the adjacent sea waters was investigated in May and November 2008,August 2009,and May and September 2010,respectively.A total of 95 species of macrobenthos were identified in the five cruises and most of them were polychaetes(46.39%),mollusks(28.86%) and crustaceans(20.62%).The Shannon-Wiener index of macrobenthos was lower than 2 in 67% sites.Along the stream channel,estuary and the coastal waters,the species of polychaetes reduced gradually,while the abundance increased at first and then decreased.The abundance was the biggest at regions with salinity of 5 20 in the estuary.The species and abundance of mollusks and crustaceans increased gradually.As for seasonal distribution,the species,abundance and biomass were higher in spring and lower in summer and autumn.Contemporaneously compared with Laizhou Bay and Yellow River Estuary,the species of macrobenthos appeared in the Xiaoqing River Estuary were much less,while the percentage of polychaetes was higher.Abundance and biomass were higher in Xiaoqing River estuary,then consequently followed by Laizhou Bay and Yellow River Estuary.The dominant species in Xiaoqing River Estuary was polychaete,and Layzhou Bay mollusk.The community structure characteristics of macrobenthos in the Xiaoqing River Estuary revealed a significant pollution status in this region.
基金sponsored by the National Basic Research Program of China (973 Program, Grant No. 2012CB956203)the Knowledge Innovation Project of the Chinese Academy of Sciences (Grant No. KZCX2-EW-202)the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No. XDA05090100)
文摘A number of recent studies have examined trends in extreme temperature indices using a linear regression model based on ordinary least-squares. In this study, quantile regression was, for the first time, applied to examine the trends not only in the mean but also in all parts of the distribution of several extreme temperature indices in China for the period 1960–2008. For China as a whole, the slopes in almost all the quantiles of the distribution showed a notable increase in the numbers of warm days and warm nights, and a significant decrease in the number of cool nights. These changes became much faster as the quantile increased. However, although the number of cool days exhibited a significant decrease in the mean trend estimated by classical linear regression, there was no obvious trend in the upper and lower quantiles. This finding suggests that examining the trends in different parts of the distribution of the time-series is of great importance. The spatial distribution of the trend in the 90 th quantile indicated that there was a pronounced increase in the numbers of warm days and warm nights, and a decrease in the number of cool nights for most of China, but especially in the northern and western parts of China, while there was no significant change for the number of cool days at almost all the stations.
基金Supported by the Hundred Talent Program of the Chinese Academy of Sciences,the National Natural Science Foundation of China under Grant Nos.71103179 and 71102129Program for Young Innovative Research Team in China University of Political Science and Law, 2010 Fund Project under the Ministry of Education of China for Youth Who are Devoted to Humanities and Social Sciences Research 10YJC630425
文摘This works examine the responses of housing prices to the monetary policies in various Chinese cities. Thirty-five large and medium sized Chinese cities are classified into six clusters applying the minimum variance clustering method according to the calculated correlation coefficients between the housing price indices of every two cities.Time difference correlation analysis is then employed to quantify the relations between the housing price indices of the six clusters and the monetary policies.It is suggested that the housing prices of various cities evolved at different paces and their responses to the monetary policies are heterogeneous,and local economic features are more important than geographic distances in determining the housing price trends.
文摘Based on the Gauss linear frequency modulated wavelet transform, a new characteristic index is presented, namely time frequency energy attenuation factor which can reflect the difference features of waveform in earthquake focus mechanism, wave traveling path and its attenuation characteristics in focal area or near field. In order to test its validity, we select the natural earthquakes and explosion or collapse events whose focus mechanisms vary obviously,and some natural earthquakes located at the same site or in a very small area. The study indicates that the time frequency energy attenuation factors of the natural earthquakes are obviously different with that of explosion or collapse events, and the change of the time frequency energy attenuation factors is relatively stable for the earthquakes under the normal seismicity background. Using the above mentioned method, it is expected to offer a useful criterion for strong earthquake prediction by continuous earthquake observation.