In Slovakia, a direct disposal of spent nuclear fuel in a deep geological repository within the country after a certain period of interim storage is a preferred option. This paper briefly describes near field model of...In Slovakia, a direct disposal of spent nuclear fuel in a deep geological repository within the country after a certain period of interim storage is a preferred option. This paper briefly describes near field model of radionuclide migration developed in GoldSim simulation code environment and analyses the calculated results on time-dependent release rates of safety relevant radionuclides. Given the fact that GoldSimalso enables to perform probabilistic simulations using the Monte Carlo method, a probabilistic approach was chosen to assess the influence of selected near field parameter uncertainties related to radionuclide migration on the radionuclide release rates from the bentonite buffer to the surrounding host rock. Based on the results, release rates of nuclides which exceed their solubility limits are effectively lowered and many of nuclides are significantly sorbed on the buffer material. It can be seen that the variance of the total release rate in the case of solubility uncertainty is almost two orders of magnitude within a long period of time.展开更多
On September 8, 2018, an M_S 5.9 earthquake struck Mojiang, a county in Yunnan Province, China. We collect near-field seismic recordings(epicentral distances less than 200 km) to relocate the mainshock and the aftersh...On September 8, 2018, an M_S 5.9 earthquake struck Mojiang, a county in Yunnan Province, China. We collect near-field seismic recordings(epicentral distances less than 200 km) to relocate the mainshock and the aftershocks within the first 60 hours to determine the focal mechanism solutions of the mainshock and some of the aftershocks and to invert for the finite-fault model of the mainshock.The focal mechanism solution of the mainshock and the relocation results of the aftershocks constrain the mainshock on a nearly vertical fault plane striking northeast and dipping to the southeast. The inversion of the finite-fault model reveals only a single slip asperity on the fault plane. The major slip is distributed above the initiation point, ～14 km wide along the down-dip direction and ～14 km long along the strike direction, with a maximal slip of ～22 cm at a depth of ～6 km. The focal mechanism solutions of the aftershocks show that most of the aftershocks are of the strike-slip type, a number of them are of the normal-slip type, and only a few of them are of the thrust-slip type.On average, strike-slip is dominant on the fault plane of the mainshock, as the focal mechanism solution of the mainshock suggests, but when examined in detail, slight thrust-slip appears on the southwest of the fault plane while an obvious part of normal-slip appears on the northeast, which is consistent with what the focal mechanism solutions of the aftershocks display. The multiple types of aftershock focal mechanism solutions and the slip details of the mainshock both suggest a complex tectonic setting, stress setting, or both. The intensity contours predicted exhibit a longer axis trending from northeast to southwest and a maximal intensity of Ⅷ around the epicenter and in the northwest.展开更多
On September 16, 2015, an earthquake with magnitude ofMw 8.3 occurred 46 km offshore from Illapel, Chile, generating a 4.4-m local tsunami measured at Coquimbo. In this study, the characteristics of tsunami are presen...On September 16, 2015, an earthquake with magnitude ofMw 8.3 occurred 46 km offshore from Illapel, Chile, generating a 4.4-m local tsunami measured at Coquimbo. In this study, the characteristics of tsunami are presented by a combination of analysis of observations and numerical simulation based on sources of USGS and NOAA. The records of 16 DART buoys in deep water, ten tidal gauges along coasts of near-field, and ten coastal gauges in the far-field are studied by applying Fourier analyses. The numerical simulation based on nonlinear shallow water equations and nested grids is carried out to provide overall tsunami propagation scenarios, and the results match well with the observations in deep water and but not well in coasts closed to the epicenter. Due to the short distance to the epicenter and the shelf resonance of southern Peru and Chile, the maximum amplitude ranged from 0.1 m to 2 m, except for Coquimbo. In deep water, the maximum amplitude of buoys decayed from 9.8 cm to 0.8 cm, suggesting a centimeter-scale Pacific-wide tsunami, while the governing period was 13-17 min and 32 min. Whereas in the far-field coastal region, the tsunami wave amplified to be around 0.2 m to 0.8 m, mostly as a result of run-up effect and resonance from coast reflection. Although the tsunami was relatively moderate in deep water, it still produced non-negligible tsunami hazards in local region and the coasts of farfield.展开更多
The Mw 9.0 Tohoku-Oki earthquake that hit the mainland Japan on 11 th March, 2011 had resulted a devastating Tsunami due to an active thrusting between the Pacific and the North American Plates. Static and kinematic o...The Mw 9.0 Tohoku-Oki earthquake that hit the mainland Japan on 11 th March, 2011 had resulted a devastating Tsunami due to an active thrusting between the Pacific and the North American Plates. Static and kinematic offsets at the offshore epicentre of the Mw 9.0 event remain unanswered and being investigated along with their near and far field limiting distances from the epicentre. Accordingly, offset measurements from 60 continuously operating IGS and GEONET GNSS stations were radially classified from the epicentre and interpreted with analytical models to find their linear offset decay rates. Co-and post-seismic static positional anomaly offsets of sixty days show almost all near field stations had strong or appreciable eastward or south eastward static shifts. Near stations(<250 km) showed both kinematic and static offsets. GEONET station ’0175’ showed maximum resultant static offset of-4.5 m, which diminishes approximately 1-2 cm at far sites like SMST and AIRA. Characteristic decay duration(’b’) of the mean kinematic co-seismic shift(’a’)of near field stations was 17.28 s during earthquake hours with an EW component shift >1.5 m. Spatial models of projected N-S static and kinematic offsets show their asymmetrical distributions around the epicentre with maximum model offset of-1.84 m displaced towards south at-45 km north of the epicentre. The Tohoku-Oki earthquake produced a resultant kinematic offset of-10.2 m towards East at its offshore epicentre;while the estimated near field static offset is ~9.82 m. However, both estimates are bigger than double the resultant offset measured value(~4.3 m) in the Japanese mainland using GPS. The difference in the kinematic and static near field offsets highlight that the near surface had elastic or in-elastic kinematic strain dissipation as against the lithospheric level viscoelastic static response, which resulted rapid kinematic strain release(1.12 cm/km)within the limiting radius of ~220 km from the Tohoku-Oki epicentre.展开更多
A method to predict near-field strong ground motions for scenario earthquakes on active faults is proposed. First, macro-source parameters characterizing the entire source area, i.e., global source parameters, includi...A method to predict near-field strong ground motions for scenario earthquakes on active faults is proposed. First, macro-source parameters characterizing the entire source area, i.e., global source parameters, including fault length, fault width, rupture area, average slip on the fault plane, etc., are estimated by seismogeology survey, seismicity and seismic scaling laws. Second, slip distributions characterizing heterogeneity or roughness on the fault plane, i.e., local source parameters, are reproduced/evaluated by the hybrid slip model. Finally, the finite fault source model, developed from both the global and local source parameters, is combined with the stochastically synthetic technique of ground motion using the dynamic comer frequency based on seismology. The proposed method is applied to simulate the acceleration time histories on three base-rock stations during the 1994 Northridge earthquake. Comparisons between the predicted and recorded acceleration time histories show that the method is feasible and practicable.展开更多
针对现有无相位近场数据的偶极子建模很难精确对干扰源进行等效的问题,对现有无相位近场数据的干扰源等效建模中所采用的双面迭代方法进行了改进,改进方法主要是采用2个以上不同高度的磁场幅度数据;对双面迭代方法中平面的选择以及改进...针对现有无相位近场数据的偶极子建模很难精确对干扰源进行等效的问题,对现有无相位近场数据的干扰源等效建模中所采用的双面迭代方法进行了改进,改进方法主要是采用2个以上不同高度的磁场幅度数据;对双面迭代方法中平面的选择以及改进方法中平面数量和起始面的选择进行了讨论;以干扰源辐射磁场重构的均方根误差(Root Mean Square Error,RMSE)作为偶极子建模准确度评价依据,与现有双面迭代方法及其他优化方法等效建模出的偶极子模型进行了对比验证,对比结果显示该改进方法具有更高的准确度。展开更多
超大规模天线阵列在近期取得了快速发展并有望在未来无线通信,尤其是在中频和毫米波频段取得广泛应用。随着天线孔径的提升,近场效应变得更为明显和突出,因此传统远场平面波假设不再适用。为更准确地对近场通信进行性能评估,建立准确反...超大规模天线阵列在近期取得了快速发展并有望在未来无线通信,尤其是在中频和毫米波频段取得广泛应用。随着天线孔径的提升,近场效应变得更为明显和突出,因此传统远场平面波假设不再适用。为更准确地对近场通信进行性能评估,建立准确反映近场信道特性的信道模型尤为关键,基于电磁理论和物理光学,建立了一般散射体的散射模型。通过对近场散射体散射特性的研究,分析了非视距(Non-Line of Sight,NLoS)径信道状态的变化特点以及近场场景中的空间非平稳(Spatial Non-Stationary,SNS)特征。基于大规模收发天线阵元间空间一致性特性,结合散射体散射特性,设计了基于空间一致性的近场信道参数生成方法,并提出一种衰减因子计算方法,用以表征空间非平稳特性。在3GPP标准信道建模流程基础上,设计了一种适用于近场电磁波传播的信道模型。提出的信道模型同时建模了球面波和空间非平稳特性对近场通信的影响,可准确评估近场通信性能,为近场码本设计、波束成型等技术的发展打下基础。展开更多
在6G通信系统中,随着天线规模的增大,菲涅尔区逐步扩展,现有的远场通信假设会引入严重的能量扩散,即角度域不再稀疏.近场通信利用球面波前进行建模,其信道模型与用户到达基站的角度和距离相关,在通信的同时可以估计角度和距离,实现通信...在6G通信系统中,随着天线规模的增大,菲涅尔区逐步扩展,现有的远场通信假设会引入严重的能量扩散,即角度域不再稀疏.近场通信利用球面波前进行建模,其信道模型与用户到达基站的角度和距离相关,在通信的同时可以估计角度和距离,实现通信感知一体化(Integrated Sensing And Communication,ISAC).本文针对近场环境下ISAC问题,提出了基于极坐标的近场模型,通过非均匀网格划分将ISAC转化为稀疏估计问题,进而提出基于稀疏贝叶斯学习模型和消息传递算法的ISAC算法,同时完成活跃用户检测、位置感知和通信.此外,所提算法采用差分调制,在通信和感知中无需利用导频,即可实现盲ISAC,有效提升通信系统的频谱效率.仿真结果表明,相对于均匀区域划分和文献现有方法,本文提出的ISAC算法可获得更高的感知精度和误码率性能.展开更多
随着6G技术对数据传输速率的高要求,超大规模多输入多输出(Extremely Large-scale Multiple-Input Multiple-Output,XL-MIMO)系统的应用前景广泛。然而,XL-MIMO系统中的近场球面波前特性使得传统基于平面波前的信道估计方法不再适用,从...随着6G技术对数据传输速率的高要求,超大规模多输入多输出(Extremely Large-scale Multiple-Input Multiple-Output,XL-MIMO)系统的应用前景广泛。然而,XL-MIMO系统中的近场球面波前特性使得传统基于平面波前的信道估计方法不再适用,从而影响信道状态信息(Channel State Information,CSI)的获取。为了解决这一问题,提出了一种新的信道估计方案,分析了XL-MIMO的近场球面波特性,并将其与适用于高速移动场景的正交时频空间(Orthogonal Time Frequency Space,OTFS)调制技术结合,构建了一个考虑球面波特性的XL-MIMO OTFS系统框架。此外,利用模型驱动的思想设计了一种可学习的去噪近似消息传递(Learned Denoising Based Approximate Message Passing,LDAMP)算法,用于有效估计信道状态信息。仿真结果表明,所提出的XL-MIMO OTFS信道估计框架在近场高速移动场景下具有显著的性能提升和良好的鲁棒性。在信噪比为20 dB时,LDAMP算法的归一化均方误差达到10^(-2),相比传统算法提高了多个数量级。展开更多
文摘In Slovakia, a direct disposal of spent nuclear fuel in a deep geological repository within the country after a certain period of interim storage is a preferred option. This paper briefly describes near field model of radionuclide migration developed in GoldSim simulation code environment and analyses the calculated results on time-dependent release rates of safety relevant radionuclides. Given the fact that GoldSimalso enables to perform probabilistic simulations using the Monte Carlo method, a probabilistic approach was chosen to assess the influence of selected near field parameter uncertainties related to radionuclide migration on the radionuclide release rates from the bentonite buffer to the surrounding host rock. Based on the results, release rates of nuclides which exceed their solubility limits are effectively lowered and many of nuclides are significantly sorbed on the buffer material. It can be seen that the variance of the total release rate in the case of solubility uncertainty is almost two orders of magnitude within a long period of time.
基金supported by the National Natural Science Foundation of China(project 41804088)the Special Fund of the Institute of Geophysics,China Earthquake Administration(project DQJB19B08)
文摘On September 8, 2018, an M_S 5.9 earthquake struck Mojiang, a county in Yunnan Province, China. We collect near-field seismic recordings(epicentral distances less than 200 km) to relocate the mainshock and the aftershocks within the first 60 hours to determine the focal mechanism solutions of the mainshock and some of the aftershocks and to invert for the finite-fault model of the mainshock.The focal mechanism solution of the mainshock and the relocation results of the aftershocks constrain the mainshock on a nearly vertical fault plane striking northeast and dipping to the southeast. The inversion of the finite-fault model reveals only a single slip asperity on the fault plane. The major slip is distributed above the initiation point, ～14 km wide along the down-dip direction and ～14 km long along the strike direction, with a maximal slip of ～22 cm at a depth of ～6 km. The focal mechanism solutions of the aftershocks show that most of the aftershocks are of the strike-slip type, a number of them are of the normal-slip type, and only a few of them are of the thrust-slip type.On average, strike-slip is dominant on the fault plane of the mainshock, as the focal mechanism solution of the mainshock suggests, but when examined in detail, slight thrust-slip appears on the southwest of the fault plane while an obvious part of normal-slip appears on the northeast, which is consistent with what the focal mechanism solutions of the aftershocks display. The multiple types of aftershock focal mechanism solutions and the slip details of the mainshock both suggest a complex tectonic setting, stress setting, or both. The intensity contours predicted exhibit a longer axis trending from northeast to southwest and a maximal intensity of Ⅷ around the epicenter and in the northwest.
基金The Public Science and Technology Research Funds Projects of Ocean under contract No.201405026the National Key Research and Development Program of China under contract No.2016YFC1401500the Opening Fund of State Key Laboratory of Ocean Engineering under contract No.1604
文摘On September 16, 2015, an earthquake with magnitude ofMw 8.3 occurred 46 km offshore from Illapel, Chile, generating a 4.4-m local tsunami measured at Coquimbo. In this study, the characteristics of tsunami are presented by a combination of analysis of observations and numerical simulation based on sources of USGS and NOAA. The records of 16 DART buoys in deep water, ten tidal gauges along coasts of near-field, and ten coastal gauges in the far-field are studied by applying Fourier analyses. The numerical simulation based on nonlinear shallow water equations and nested grids is carried out to provide overall tsunami propagation scenarios, and the results match well with the observations in deep water and but not well in coasts closed to the epicenter. Due to the short distance to the epicenter and the shelf resonance of southern Peru and Chile, the maximum amplitude ranged from 0.1 m to 2 m, except for Coquimbo. In deep water, the maximum amplitude of buoys decayed from 9.8 cm to 0.8 cm, suggesting a centimeter-scale Pacific-wide tsunami, while the governing period was 13-17 min and 32 min. Whereas in the far-field coastal region, the tsunami wave amplified to be around 0.2 m to 0.8 m, mostly as a result of run-up effect and resonance from coast reflection. Although the tsunami was relatively moderate in deep water, it still produced non-negligible tsunami hazards in local region and the coasts of farfield.
文摘The Mw 9.0 Tohoku-Oki earthquake that hit the mainland Japan on 11 th March, 2011 had resulted a devastating Tsunami due to an active thrusting between the Pacific and the North American Plates. Static and kinematic offsets at the offshore epicentre of the Mw 9.0 event remain unanswered and being investigated along with their near and far field limiting distances from the epicentre. Accordingly, offset measurements from 60 continuously operating IGS and GEONET GNSS stations were radially classified from the epicentre and interpreted with analytical models to find their linear offset decay rates. Co-and post-seismic static positional anomaly offsets of sixty days show almost all near field stations had strong or appreciable eastward or south eastward static shifts. Near stations(<250 km) showed both kinematic and static offsets. GEONET station ’0175’ showed maximum resultant static offset of-4.5 m, which diminishes approximately 1-2 cm at far sites like SMST and AIRA. Characteristic decay duration(’b’) of the mean kinematic co-seismic shift(’a’)of near field stations was 17.28 s during earthquake hours with an EW component shift >1.5 m. Spatial models of projected N-S static and kinematic offsets show their asymmetrical distributions around the epicentre with maximum model offset of-1.84 m displaced towards south at-45 km north of the epicentre. The Tohoku-Oki earthquake produced a resultant kinematic offset of-10.2 m towards East at its offshore epicentre;while the estimated near field static offset is ~9.82 m. However, both estimates are bigger than double the resultant offset measured value(~4.3 m) in the Japanese mainland using GPS. The difference in the kinematic and static near field offsets highlight that the near surface had elastic or in-elastic kinematic strain dissipation as against the lithospheric level viscoelastic static response, which resulted rapid kinematic strain release(1.12 cm/km)within the limiting radius of ~220 km from the Tohoku-Oki epicentre.
基金China Postdoctoral Science Foundation UnderGrant No. 2005037650 Heilongjiang Province PostdoctoralScience Foundation China EarthquakeAdministration’s Tenth"Five Year Plans" Project
文摘A method to predict near-field strong ground motions for scenario earthquakes on active faults is proposed. First, macro-source parameters characterizing the entire source area, i.e., global source parameters, including fault length, fault width, rupture area, average slip on the fault plane, etc., are estimated by seismogeology survey, seismicity and seismic scaling laws. Second, slip distributions characterizing heterogeneity or roughness on the fault plane, i.e., local source parameters, are reproduced/evaluated by the hybrid slip model. Finally, the finite fault source model, developed from both the global and local source parameters, is combined with the stochastically synthetic technique of ground motion using the dynamic comer frequency based on seismology. The proposed method is applied to simulate the acceleration time histories on three base-rock stations during the 1994 Northridge earthquake. Comparisons between the predicted and recorded acceleration time histories show that the method is feasible and practicable.
文摘针对现有无相位近场数据的偶极子建模很难精确对干扰源进行等效的问题,对现有无相位近场数据的干扰源等效建模中所采用的双面迭代方法进行了改进,改进方法主要是采用2个以上不同高度的磁场幅度数据;对双面迭代方法中平面的选择以及改进方法中平面数量和起始面的选择进行了讨论;以干扰源辐射磁场重构的均方根误差(Root Mean Square Error,RMSE)作为偶极子建模准确度评价依据,与现有双面迭代方法及其他优化方法等效建模出的偶极子模型进行了对比验证,对比结果显示该改进方法具有更高的准确度。
文摘超大规模天线阵列在近期取得了快速发展并有望在未来无线通信,尤其是在中频和毫米波频段取得广泛应用。随着天线孔径的提升,近场效应变得更为明显和突出,因此传统远场平面波假设不再适用。为更准确地对近场通信进行性能评估,建立准确反映近场信道特性的信道模型尤为关键,基于电磁理论和物理光学,建立了一般散射体的散射模型。通过对近场散射体散射特性的研究,分析了非视距(Non-Line of Sight,NLoS)径信道状态的变化特点以及近场场景中的空间非平稳(Spatial Non-Stationary,SNS)特征。基于大规模收发天线阵元间空间一致性特性,结合散射体散射特性,设计了基于空间一致性的近场信道参数生成方法,并提出一种衰减因子计算方法,用以表征空间非平稳特性。在3GPP标准信道建模流程基础上,设计了一种适用于近场电磁波传播的信道模型。提出的信道模型同时建模了球面波和空间非平稳特性对近场通信的影响,可准确评估近场通信性能,为近场码本设计、波束成型等技术的发展打下基础。
文摘在6G通信系统中,随着天线规模的增大,菲涅尔区逐步扩展,现有的远场通信假设会引入严重的能量扩散,即角度域不再稀疏.近场通信利用球面波前进行建模,其信道模型与用户到达基站的角度和距离相关,在通信的同时可以估计角度和距离,实现通信感知一体化(Integrated Sensing And Communication,ISAC).本文针对近场环境下ISAC问题,提出了基于极坐标的近场模型,通过非均匀网格划分将ISAC转化为稀疏估计问题,进而提出基于稀疏贝叶斯学习模型和消息传递算法的ISAC算法,同时完成活跃用户检测、位置感知和通信.此外,所提算法采用差分调制,在通信和感知中无需利用导频,即可实现盲ISAC,有效提升通信系统的频谱效率.仿真结果表明,相对于均匀区域划分和文献现有方法,本文提出的ISAC算法可获得更高的感知精度和误码率性能.
文摘随着6G技术对数据传输速率的高要求,超大规模多输入多输出(Extremely Large-scale Multiple-Input Multiple-Output,XL-MIMO)系统的应用前景广泛。然而,XL-MIMO系统中的近场球面波前特性使得传统基于平面波前的信道估计方法不再适用,从而影响信道状态信息(Channel State Information,CSI)的获取。为了解决这一问题,提出了一种新的信道估计方案,分析了XL-MIMO的近场球面波特性,并将其与适用于高速移动场景的正交时频空间(Orthogonal Time Frequency Space,OTFS)调制技术结合,构建了一个考虑球面波特性的XL-MIMO OTFS系统框架。此外,利用模型驱动的思想设计了一种可学习的去噪近似消息传递(Learned Denoising Based Approximate Message Passing,LDAMP)算法,用于有效估计信道状态信息。仿真结果表明,所提出的XL-MIMO OTFS信道估计框架在近场高速移动场景下具有显著的性能提升和良好的鲁棒性。在信噪比为20 dB时,LDAMP算法的归一化均方误差达到10^(-2),相比传统算法提高了多个数量级。
