A generalized flexibility–based objective function utilized for structure damage identification is constructed for solving the constrained nonlinear least squares optimized problem. To begin with, the generalized fle...A generalized flexibility–based objective function utilized for structure damage identification is constructed for solving the constrained nonlinear least squares optimized problem. To begin with, the generalized flexibility matrix (GFM) proposed to solve the damage identification problem is recalled and a modal expansion method is introduced. Next, the objective function for iterative optimization process based on the GFM is formulated, and the Trust-Region algorithm is utilized to obtain the solution of the optimization problem for multiple damage cases. And then for computing the objective function gradient, the sensitivity analysis regarding design variables is derived. In addition, due to the spatial incompleteness, the influence of stiffness reduction and incomplete modal measurement data is discussed by means of two numerical examples with several damage cases. Finally, based on the computational results, it is evident that the presented approach provides good validity and reliability for the large and complicated engineering structures.展开更多
Based on the Morlet wavelet transform and digital data from the Fushun and Beizhen seismic stations, Liaoning Province, we put forward a new method in the paper, called time-frequency energy attenuation factor （α-va...Based on the Morlet wavelet transform and digital data from the Fushun and Beizhen seismic stations, Liaoning Province, we put forward a new method in the paper, called time-frequency energy attenuation factor （α-value）. The characteristics of the α-value and its variation with magnitude of natural and mine earthquakes are studied, and the statistic relations between the α-value and specific earthquake magnitude are obtained. From the results, some conclusions can be drawn as follows： （1） in general, the α-values of mine and natural earthquakes of the same intensity have obvious difference and the ranges of their variation do not overlap each other; （2） the α-value decreases with the increase of earthquake magnitude, and the α-value of mine earthquake decreases faster than that of natural earthquake; （3） based on the earthquake magnitude and on the relations between the α-value and earthquake magnitude, we can distinguish the mine earthquakes from the natural ones; （4） the difference in focal mechanism of mine and natural earthquakes would be the main cause for obvious difference of the α-value; （5） the α-value variation is relatively steady for mine and natural earthquakes that occur in the same region, but it has obvious regional difference. The above results are of inspirational meaning for the study of abnormal change of the α-value before strong earthquakes.展开更多
DNA polymorphism in the cultivar species;Cucumis sativus L., C. melo L. and Benincasa hispida Cogn. of subtribe Cucumerinae (Cucurbitaceae) in the four northeastern provinces of Thailand was examined by using RAPD tec...DNA polymorphism in the cultivar species;Cucumis sativus L., C. melo L. and Benincasa hispida Cogn. of subtribe Cucumerinae (Cucurbitaceae) in the four northeastern provinces of Thailand was examined by using RAPD technique. Twenty 10-mer primers were produced 212 RAPD fragments, ranging from approximately 120 to 2531 bp. The genetic similarities were estimated from banding profiles using a NTSYS* version 2.1 as a basis for dendrogram construction via the UPGMA method. Cluster analysis divided the taxa under study into 2 clades. Moreover, a RAPD marker: Cm (OPJ11700) was specified to C. melo, and this marker was converted into sequence characterized amplified region (SCAR) marker: Cm (SCJ11516). A pair of sequence-specific primer of clones Cm (OPJ11700) amplified a distinct single band of the same size as the RAPD clones. The SCAR marker was developed successfully to identify C. melo genotype.展开更多
Regional lightning protection is a complete theoretical system,mainly including:lightning interception technology(LIPT),lightning strong electromagnetic pulse high-energy absorption technology(MSPD),and regional light...Regional lightning protection is a complete theoretical system,mainly including:lightning interception technology(LIPT),lightning strong electromagnetic pulse high-energy absorption technology(MSPD),and regional lightning activity law analysis technology(RLLA).Lightning interception technology uses dispersive waveguide resonant cavity technology to achieve the functions of 46.55 m longer than upward leader of ordinary lightning rod,significantly reducing lightning strike point current by 40%,optimizing space electromagnetic field environment,and effectively intercepting overhead and side lightning strikes,and overcome the limitations of traditional lightning rod.The lightning strong electromagnetic pulse high-energy absorption technology uses distributed parameter balance technology,special disconnector for short circuit current,and parity pairing technology to achieve stronger surge absorption capacity than traditional single pulse SPD and international advanced technical indicators such as timely breaking under power frequency short circuit current,and good energy and time coordination.The analysis technology of regional lightning activity laws accurately identifies lightning strike points through comprehensive analysis of regional lightning activity laws,physical parameters of ion clouds,and the impact on ground electric fields.The three core technology systems complement each other,achieving all-round protection against direct lightning strike and lightning electromagnetic pulse.Several projects achieved zero lightning damage,effectively ensuring the safety of buildings and electronic and electrical equipment in the protected area.展开更多
基于华南地区176个国家级自动气象站资料以及1981~2020年ECMWF ERA5再分析资料,采用区域性极端事件的客观识别方法(OITREE)、合成分析等方法,本文研究了华南地区区域性极端降水事件的时空分布特征,并分析了事件偏多年及偏少年的大尺度...基于华南地区176个国家级自动气象站资料以及1981~2020年ECMWF ERA5再分析资料,采用区域性极端事件的客观识别方法(OITREE)、合成分析等方法,本文研究了华南地区区域性极端降水事件的时空分布特征,并分析了事件偏多年及偏少年的大尺度环流特征。主要结论如下:区域性极端降水事件的频次在年际尺度上的周期变化较为明显,并具有较明显的月变化特征,高发时段为5~6月;在极端强度及影响范围上,华南地区大部分区域性极端降水事件强度约130 mm d^(-1),较少事件强度超出320 mm d^(-1),且区域性极端降水事件的影响范围呈显著上升趋势(约310 km^(2)a^(-1));在事件的综合强度上,综合指数Z呈现显著的上升趋势[0.05(10 a)^(-1)],表明事件强度呈现显著增加的趋势;在大湾区及广东北部,区域性极端降水事件的累计降水及其对总降水的贡献呈显著上升趋势,而在广西南部地区,两者呈下降趋势;在事件偏多年,华南地区存在显著的西南风水汽输送及整层水汽通量强辐合的特征,而在事件偏少年,华南地区具有整层水汽通量辐合偏弱的特征;一般降水日,850 hPa上华南地区位于弱偏东南风区,区域性极端降水事件降水日,华南地区位于气旋性环流的东南部,受到明显的西南风风速大值带影响。展开更多
文摘A generalized flexibility–based objective function utilized for structure damage identification is constructed for solving the constrained nonlinear least squares optimized problem. To begin with, the generalized flexibility matrix (GFM) proposed to solve the damage identification problem is recalled and a modal expansion method is introduced. Next, the objective function for iterative optimization process based on the GFM is formulated, and the Trust-Region algorithm is utilized to obtain the solution of the optimization problem for multiple damage cases. And then for computing the objective function gradient, the sensitivity analysis regarding design variables is derived. In addition, due to the spatial incompleteness, the influence of stiffness reduction and incomplete modal measurement data is discussed by means of two numerical examples with several damage cases. Finally, based on the computational results, it is evident that the presented approach provides good validity and reliability for the large and complicated engineering structures.
文摘Based on the Morlet wavelet transform and digital data from the Fushun and Beizhen seismic stations, Liaoning Province, we put forward a new method in the paper, called time-frequency energy attenuation factor （α-value）. The characteristics of the α-value and its variation with magnitude of natural and mine earthquakes are studied, and the statistic relations between the α-value and specific earthquake magnitude are obtained. From the results, some conclusions can be drawn as follows： （1） in general, the α-values of mine and natural earthquakes of the same intensity have obvious difference and the ranges of their variation do not overlap each other; （2） the α-value decreases with the increase of earthquake magnitude, and the α-value of mine earthquake decreases faster than that of natural earthquake; （3） based on the earthquake magnitude and on the relations between the α-value and earthquake magnitude, we can distinguish the mine earthquakes from the natural ones; （4） the difference in focal mechanism of mine and natural earthquakes would be the main cause for obvious difference of the α-value; （5） the α-value variation is relatively steady for mine and natural earthquakes that occur in the same region, but it has obvious regional difference. The above results are of inspirational meaning for the study of abnormal change of the α-value before strong earthquakes.
文摘DNA polymorphism in the cultivar species;Cucumis sativus L., C. melo L. and Benincasa hispida Cogn. of subtribe Cucumerinae (Cucurbitaceae) in the four northeastern provinces of Thailand was examined by using RAPD technique. Twenty 10-mer primers were produced 212 RAPD fragments, ranging from approximately 120 to 2531 bp. The genetic similarities were estimated from banding profiles using a NTSYS* version 2.1 as a basis for dendrogram construction via the UPGMA method. Cluster analysis divided the taxa under study into 2 clades. Moreover, a RAPD marker: Cm (OPJ11700) was specified to C. melo, and this marker was converted into sequence characterized amplified region (SCAR) marker: Cm (SCJ11516). A pair of sequence-specific primer of clones Cm (OPJ11700) amplified a distinct single band of the same size as the RAPD clones. The SCAR marker was developed successfully to identify C. melo genotype.
基金Supported by Lightning Multi-pulse Intelligent Monitoring System Optimization Technology Project of Guangdong Yuedian Dianbai Hot Water Wind Farm(SFC/DBW-Z-FW-23-006).
文摘Regional lightning protection is a complete theoretical system,mainly including:lightning interception technology(LIPT),lightning strong electromagnetic pulse high-energy absorption technology(MSPD),and regional lightning activity law analysis technology(RLLA).Lightning interception technology uses dispersive waveguide resonant cavity technology to achieve the functions of 46.55 m longer than upward leader of ordinary lightning rod,significantly reducing lightning strike point current by 40%,optimizing space electromagnetic field environment,and effectively intercepting overhead and side lightning strikes,and overcome the limitations of traditional lightning rod.The lightning strong electromagnetic pulse high-energy absorption technology uses distributed parameter balance technology,special disconnector for short circuit current,and parity pairing technology to achieve stronger surge absorption capacity than traditional single pulse SPD and international advanced technical indicators such as timely breaking under power frequency short circuit current,and good energy and time coordination.The analysis technology of regional lightning activity laws accurately identifies lightning strike points through comprehensive analysis of regional lightning activity laws,physical parameters of ion clouds,and the impact on ground electric fields.The three core technology systems complement each other,achieving all-round protection against direct lightning strike and lightning electromagnetic pulse.Several projects achieved zero lightning damage,effectively ensuring the safety of buildings and electronic and electrical equipment in the protected area.
文摘基于华南地区176个国家级自动气象站资料以及1981~2020年ECMWF ERA5再分析资料,采用区域性极端事件的客观识别方法(OITREE)、合成分析等方法,本文研究了华南地区区域性极端降水事件的时空分布特征,并分析了事件偏多年及偏少年的大尺度环流特征。主要结论如下:区域性极端降水事件的频次在年际尺度上的周期变化较为明显,并具有较明显的月变化特征,高发时段为5~6月;在极端强度及影响范围上,华南地区大部分区域性极端降水事件强度约130 mm d^(-1),较少事件强度超出320 mm d^(-1),且区域性极端降水事件的影响范围呈显著上升趋势(约310 km^(2)a^(-1));在事件的综合强度上,综合指数Z呈现显著的上升趋势[0.05(10 a)^(-1)],表明事件强度呈现显著增加的趋势;在大湾区及广东北部,区域性极端降水事件的累计降水及其对总降水的贡献呈显著上升趋势,而在广西南部地区,两者呈下降趋势;在事件偏多年,华南地区存在显著的西南风水汽输送及整层水汽通量强辐合的特征,而在事件偏少年,华南地区具有整层水汽通量辐合偏弱的特征;一般降水日,850 hPa上华南地区位于弱偏东南风区,区域性极端降水事件降水日,华南地区位于气旋性环流的东南部,受到明显的西南风风速大值带影响。
