基于标准化后的高分辨率气候代用资料,应用高阶矩分析方法检测近2000年来气候极端异常演变特征;同时结合滤波方法进行具有物理背景的层次分离,进而研究了各时间层次气候极端异常变化信息及其贡献.结果表明:1)在100年以上的时间层次上,...基于标准化后的高分辨率气候代用资料,应用高阶矩分析方法检测近2000年来气候极端异常演变特征;同时结合滤波方法进行具有物理背景的层次分离,进而研究了各时间层次气候极端异常变化信息及其贡献.结果表明:1)在100年以上的时间层次上,可能存在千年左右的气候变化振荡周期,而且20世纪是近2000年来气候极端异常现象最为活跃的时段,可能对应于气候极端异常现象活跃期.2)对于20—60年这一时间层次,公元300—1100年间气候极端异常现象比较明显,而公元1100—1980年间相对比较缓和;该层次对20世纪的气候异常没有显著贡献.世纪以上和20—60年时间层次均揭示出在近2000年的气候变化中,公元1100年前后可能是一个气候极端异常现象演变的关键转折时期.3)在年际尺度上(小于20年),北京石花洞石笋微层厚度时间序列中发生气候极端异常现象的年份与出现E1Ni o事件和La Ni a事件的年份有非常好的对应关系(仅讨论公元1960—1980年).4)高阶矩分析方法对于检测气候极端异常分布及演变规律有较好的应用前景.展开更多
The newly observed isomer and ground-state band in the odd-Z neutron-rich rare-earth nucleus 163 Eu are investigated by using the cranked shell model(CSM), with pairing treated by the particle-number conserving(PNC)me...The newly observed isomer and ground-state band in the odd-Z neutron-rich rare-earth nucleus 163 Eu are investigated by using the cranked shell model(CSM), with pairing treated by the particle-number conserving(PNC)method. This is the first time detailed theoretical investigations are performed of the observed 964(1) keV isomer and ground-state rotational band in 163 Eu. The experimental data are reproduced very well by the theoretical results. The configuration of the 964(1) keV isomer is assigned as the three-particle state 13^-/2(v7^+/2 [633]■v1^-/2[521]■π5^+/2[413]).More low-lying multi-particle states are predicted in 163 Eu. Due to its significant effect on the nuclear mean field, the high-order ε6 deformation plays an important role in the energy and configuration assignment of the multi-particle states. Compared to its neighboring even-even nuclei 162 Sm and 164 Gd,there is a 10%15% increase of J(1) of the oneparticle ground-state band in 163 Eu. This is explained by the pairing reduction due to the blocking of the nucleon on the proton π5+/2 [413] orbital in 163 Eu.展开更多
To achieve sparse sampling on a coded ultrasonic signal,the finite rate of innovation(FRI)sparse sampling technique is proposed on a binary frequency-coded(BFC)ultrasonic signal.A framework of FRI-based sparse samplin...To achieve sparse sampling on a coded ultrasonic signal,the finite rate of innovation(FRI)sparse sampling technique is proposed on a binary frequency-coded(BFC)ultrasonic signal.A framework of FRI-based sparse sampling for an ultrasonic signal pulse is presented.Differences between the pulse and the coded ultrasonic signal are analyzed,and a response mathematical model of the coded ultrasonic signal is established.A time-domain transform algorithm,called the high-order moment method,is applied to obtain a pulse stream signal to assist BFC ultrasonic signal sparse sampling.A sampling of the output signal with a uniform interval is then performed after modulating the pulse stream signal by a sampling kernel.FRI-based sparse sampling is performed using a self-made circuit on an aluminum alloy sample.Experimental results show that the sampling rate reduces to 0.5 MHz,which is at least 12.8 MHz in the Nyquist sampling mode.The echo peak amplitude and the time of flight are estimated from the sparse sampling data with maximum errors of 9.324%and 0.031%,respectively.This research can provide a theoretical basis and practical application reference for reducing the sampling rate and data volume in coded ultrasonic testing.展开更多
文摘基于标准化后的高分辨率气候代用资料,应用高阶矩分析方法检测近2000年来气候极端异常演变特征;同时结合滤波方法进行具有物理背景的层次分离,进而研究了各时间层次气候极端异常变化信息及其贡献.结果表明:1)在100年以上的时间层次上,可能存在千年左右的气候变化振荡周期,而且20世纪是近2000年来气候极端异常现象最为活跃的时段,可能对应于气候极端异常现象活跃期.2)对于20—60年这一时间层次,公元300—1100年间气候极端异常现象比较明显,而公元1100—1980年间相对比较缓和;该层次对20世纪的气候异常没有显著贡献.世纪以上和20—60年时间层次均揭示出在近2000年的气候变化中,公元1100年前后可能是一个气候极端异常现象演变的关键转折时期.3)在年际尺度上(小于20年),北京石花洞石笋微层厚度时间序列中发生气候极端异常现象的年份与出现E1Ni o事件和La Ni a事件的年份有非常好的对应关系(仅讨论公元1960—1980年).4)高阶矩分析方法对于检测气候极端异常分布及演变规律有较好的应用前景.
基金Supported by National Natural Science Foundation of China(11775112)the Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘The newly observed isomer and ground-state band in the odd-Z neutron-rich rare-earth nucleus 163 Eu are investigated by using the cranked shell model(CSM), with pairing treated by the particle-number conserving(PNC)method. This is the first time detailed theoretical investigations are performed of the observed 964(1) keV isomer and ground-state rotational band in 163 Eu. The experimental data are reproduced very well by the theoretical results. The configuration of the 964(1) keV isomer is assigned as the three-particle state 13^-/2(v7^+/2 [633]■v1^-/2[521]■π5^+/2[413]).More low-lying multi-particle states are predicted in 163 Eu. Due to its significant effect on the nuclear mean field, the high-order ε6 deformation plays an important role in the energy and configuration assignment of the multi-particle states. Compared to its neighboring even-even nuclei 162 Sm and 164 Gd,there is a 10%15% increase of J(1) of the oneparticle ground-state band in 163 Eu. This is explained by the pairing reduction due to the blocking of the nucleon on the proton π5+/2 [413] orbital in 163 Eu.
基金The National Natural Science Foundation of China (No.51375217)。
文摘To achieve sparse sampling on a coded ultrasonic signal,the finite rate of innovation(FRI)sparse sampling technique is proposed on a binary frequency-coded(BFC)ultrasonic signal.A framework of FRI-based sparse sampling for an ultrasonic signal pulse is presented.Differences between the pulse and the coded ultrasonic signal are analyzed,and a response mathematical model of the coded ultrasonic signal is established.A time-domain transform algorithm,called the high-order moment method,is applied to obtain a pulse stream signal to assist BFC ultrasonic signal sparse sampling.A sampling of the output signal with a uniform interval is then performed after modulating the pulse stream signal by a sampling kernel.FRI-based sparse sampling is performed using a self-made circuit on an aluminum alloy sample.Experimental results show that the sampling rate reduces to 0.5 MHz,which is at least 12.8 MHz in the Nyquist sampling mode.The echo peak amplitude and the time of flight are estimated from the sparse sampling data with maximum errors of 9.324%and 0.031%,respectively.This research can provide a theoretical basis and practical application reference for reducing the sampling rate and data volume in coded ultrasonic testing.
