Under biaxial pressure, the microcrack patterns of concrete samples with hard inclusion are as followings: Microcracks generate around the sample at the early pressured period, and gap is formed in the middle part wit...Under biaxial pressure, the microcrack patterns of concrete samples with hard inclusion are as followings: Microcracks generate around the sample at the early pressured period, and gap is formed in the middle part with the increase of σ 1; microcrack gap is becoming smaller gradually with σ 1 increase again; microcracks become active within the original gap, but they in an original active area become small. Approaching the main fracture, microcracks form as a belt and jump back and forth in the belt. The spatial fractal D s of microcracks changes from small to big, but turns decrease when approaching the main fracture. All of the features were seldom mentioned in the past experiment, however, which have some similarities with the long seismicity patterns before strong earthquakes. In this paper, Lancang Gengma earthquake was taken as an example to analyse.〖KH*2D]展开更多
A broadband seismogram may be represented by a convolution of source time function, the propagation operator and the scattering/attenuation operator. As the propagation operator is frequency independent, and the scat...A broadband seismogram may be represented by a convolution of source time function, the propagation operator and the scattering/attenuation operator. As the propagation operator is frequency independent, and the scattering/attenuation effect may be described by a Q factor depending on frequency via Q -1 =Q -1 1+(Q 2ω) -1 , considering a combination of the displacement spectra, the source spectra may directly be estimated, in which the contribution of the Q value may be eliminated automatically. Using this algorithm, the near source broadband seismograms of five aftershocks of the 1988 Lancang Gengma, Yunnan Province, China earthquake were processed. The results for the M L=3.0 and M L=3.5 aftershocks show that for the same earthquake, similar high frequency fall off may be obtained from different recording stations. The result for the M S=6.7 aftershock shows that consistent source parameters may be gotten from different seismic stations. The parameters estimated also agree with the results obtained by empirical Green′s function approach. The high frequency spectra of the aftershocks exhibit a typical f γ fall off. For the M L =3.0 aftershock, γ ≈3;for the M S=6.7 and M L =4.0 aftershocks, γ ≈2; and for the M L=3.5 and M L=3.0 aftershocks, γ ≈2.5. The corner frequency of the M S=6.7 aftershock indicates that it has a small source dimension, implying that it may come from the rupture of a small but strong barrier.展开更多
The empirical Green's function deconvolution technique is applied to the November 6, 1988, Ms=7.6, Yunnan, China earthquake to study the rupture process of this event. An aftershock of Ms=6.3 is taken as the empi...The empirical Green's function deconvolution technique is applied to the November 6, 1988, Ms=7.6, Yunnan, China earthquake to study the rupture process of this event. An aftershock of Ms=6.3 is taken as the empirical Green's function. Recordings of these two events at six stations of China Digital Seismographic Network (CDSN) are employed. Deconvolution results show that this event is a relatively simple event. Directivity analysis indicates that the rupture was initiated at hypocenter and propagated bilaterally and nearly symmetrically towards the northwest and southeast directions with a total length of 70 km and a time duration of 19 s. The rupture velocity is estimated to be about 2.0 km/s.展开更多
甘蔗白叶病(sugarcane white leaf,SCWL)是由植原体引起的甘蔗毁灭性病害,对甘蔗生产危害极大。为明确不同品种不同植期SCWL的发病规律,2018年对我国SCWL发病最为严重的耿马芒翁和贺派蔗区进行了SCWL田间发病情况调查和巢式PCR检测分析...甘蔗白叶病(sugarcane white leaf,SCWL)是由植原体引起的甘蔗毁灭性病害,对甘蔗生产危害极大。为明确不同品种不同植期SCWL的发病规律,2018年对我国SCWL发病最为严重的耿马芒翁和贺派蔗区进行了SCWL田间发病情况调查和巢式PCR检测分析。田间调查结果表明,不同品种田间自然发病率不同,其中粤糖60号平均发病率最高,为73.50%,柳城05-136平均发病率最低,为13.67%;不同植期田间自然发病率也有差异,新植蔗田间发病率最低,为32.38%,3年宿根蔗的田间发病率最高,为64.33%。病原检测结果表明,所有品种的阳性检出率均在90%以上,其中盈育91-59阳性检出率最低,为90.95%,柳城05-136阳性检出率最高,为96.67%,无白叶症状样品的阳性检出率为81.53%,2年和3年宿根的阳性检出率最高,均为96.67%。本研究结果表明SCWL发病率随宿根年限增加而升高,依据白叶症状进行的田间病害调查不能准确反映SCWL的真实发生情况。展开更多
文摘Under biaxial pressure, the microcrack patterns of concrete samples with hard inclusion are as followings: Microcracks generate around the sample at the early pressured period, and gap is formed in the middle part with the increase of σ 1; microcrack gap is becoming smaller gradually with σ 1 increase again; microcracks become active within the original gap, but they in an original active area become small. Approaching the main fracture, microcracks form as a belt and jump back and forth in the belt. The spatial fractal D s of microcracks changes from small to big, but turns decrease when approaching the main fracture. All of the features were seldom mentioned in the past experiment, however, which have some similarities with the long seismicity patterns before strong earthquakes. In this paper, Lancang Gengma earthquake was taken as an example to analyse.〖KH*2D]
文摘A broadband seismogram may be represented by a convolution of source time function, the propagation operator and the scattering/attenuation operator. As the propagation operator is frequency independent, and the scattering/attenuation effect may be described by a Q factor depending on frequency via Q -1 =Q -1 1+(Q 2ω) -1 , considering a combination of the displacement spectra, the source spectra may directly be estimated, in which the contribution of the Q value may be eliminated automatically. Using this algorithm, the near source broadband seismograms of five aftershocks of the 1988 Lancang Gengma, Yunnan Province, China earthquake were processed. The results for the M L=3.0 and M L=3.5 aftershocks show that for the same earthquake, similar high frequency fall off may be obtained from different recording stations. The result for the M S=6.7 aftershock shows that consistent source parameters may be gotten from different seismic stations. The parameters estimated also agree with the results obtained by empirical Green′s function approach. The high frequency spectra of the aftershocks exhibit a typical f γ fall off. For the M L =3.0 aftershock, γ ≈3;for the M S=6.7 and M L =4.0 aftershocks, γ ≈2; and for the M L=3.5 and M L=3.0 aftershocks, γ ≈2.5. The corner frequency of the M S=6.7 aftershock indicates that it has a small source dimension, implying that it may come from the rupture of a small but strong barrier.
文摘The empirical Green's function deconvolution technique is applied to the November 6, 1988, Ms=7.6, Yunnan, China earthquake to study the rupture process of this event. An aftershock of Ms=6.3 is taken as the empirical Green's function. Recordings of these two events at six stations of China Digital Seismographic Network (CDSN) are employed. Deconvolution results show that this event is a relatively simple event. Directivity analysis indicates that the rupture was initiated at hypocenter and propagated bilaterally and nearly symmetrically towards the northwest and southeast directions with a total length of 70 km and a time duration of 19 s. The rupture velocity is estimated to be about 2.0 km/s.
文摘甘蔗白叶病(sugarcane white leaf,SCWL)是由植原体引起的甘蔗毁灭性病害,对甘蔗生产危害极大。为明确不同品种不同植期SCWL的发病规律,2018年对我国SCWL发病最为严重的耿马芒翁和贺派蔗区进行了SCWL田间发病情况调查和巢式PCR检测分析。田间调查结果表明,不同品种田间自然发病率不同,其中粤糖60号平均发病率最高,为73.50%,柳城05-136平均发病率最低,为13.67%;不同植期田间自然发病率也有差异,新植蔗田间发病率最低,为32.38%,3年宿根蔗的田间发病率最高,为64.33%。病原检测结果表明,所有品种的阳性检出率均在90%以上,其中盈育91-59阳性检出率最低,为90.95%,柳城05-136阳性检出率最高,为96.67%,无白叶症状样品的阳性检出率为81.53%,2年和3年宿根的阳性检出率最高,均为96.67%。本研究结果表明SCWL发病率随宿根年限增加而升高,依据白叶症状进行的田间病害调查不能准确反映SCWL的真实发生情况。
