Buckling-restrained braces(BRBs)have shown their capability to provide building structures with stiffness,strength,and ductility.Estimating the seismic drifts of buckling-restrained braced frames(BRBFs)is an important...Buckling-restrained braces(BRBs)have shown their capability to provide building structures with stiffness,strength,and ductility.Estimating the seismic drifts of buckling-restrained braced frames(BRBFs)is an important design step to control structural and non-structural damage.In current practice of seismic design,the estimation of seismic drifts of BRBFs is performed by using empirical calculations that are independent upon either the type of the structural system or the design level of seismicity.In these empirical calculations,the seismic drifts are estimated by amplifying the reduced elastic drifts obtained under design lateral loading with a displacement amplification factor(DAF).The value of DAF is considered equal to the product of the response modification factor R and the inelastic displacement ratioρ.The goal of the current research is to assess the value ofρfor low-to mid-rise BRBFs designed under low and high levels of seismicity.This goal has been achieved by conducting a series of elastic and inelastic time-history analyses pertaining to an ensemble of earthquake records on 3-,6-and 9-story BRBFs.The results indicate that theρ-ratio increases with an increase in design seismic intensity and an increase in experienced inelasticity.The range ofρfor low seismicity designs ranges from 0.63 to 0.9,while for high seismicity designs this range stretches from 0.83 to 1.29.It has been found that the consideration of a generalρ-ratio of 1.0 is a reasonable estimation for the design of the BRBFs considered in this study.展开更多
Every application in a smart city environment like the smart grid,health monitoring, security, and surveillance generates non-stationary datastreams. Due to such nature, the statistical properties of data changes over...Every application in a smart city environment like the smart grid,health monitoring, security, and surveillance generates non-stationary datastreams. Due to such nature, the statistical properties of data changes overtime, leading to class imbalance and concept drift issues. Both these issuescause model performance degradation. Most of the current work has beenfocused on developing an ensemble strategy by training a new classifier on thelatest data to resolve the issue. These techniques suffer while training the newclassifier if the data is imbalanced. Also, the class imbalance ratio may changegreatly from one input stream to another, making the problem more complex.The existing solutions proposed for addressing the combined issue of classimbalance and concept drift are lacking in understating of correlation of oneproblem with the other. This work studies the association between conceptdrift and class imbalance ratio and then demonstrates how changes in classimbalance ratio along with concept drift affect the classifier’s performance.We analyzed the effect of both the issues on minority and majority classesindividually. To do this, we conducted experiments on benchmark datasetsusing state-of-the-art classifiers especially designed for data stream classification.Precision, recall, F1 score, and geometric mean were used to measure theperformance. Our findings show that when both class imbalance and conceptdrift problems occur together the performance can decrease up to 15%. Ourresults also show that the increase in the imbalance ratio can cause a 10% to15% decrease in the precision scores of both minority and majority classes.The study findings may help in designing intelligent and adaptive solutionsthat can cope with the challenges of non-stationary data streams like conceptdrift and class imbalance.展开更多
为了研究桥墩结构的震后功能可恢复性,针对附加自复位耗能支撑(self-centering energy dissipation braces,SCEB)双柱式桥墩结构进行基于增量动力分析方法的地震易损性分析,采用最大侧移率和残余侧移率作为性能指标,系统探讨其在近场脉...为了研究桥墩结构的震后功能可恢复性,针对附加自复位耗能支撑(self-centering energy dissipation braces,SCEB)双柱式桥墩结构进行基于增量动力分析方法的地震易损性分析,采用最大侧移率和残余侧移率作为性能指标,系统探讨其在近场脉冲型地震动作用下的失效概率.为了对比分析,同时选取60条远场无脉冲型地震动记录对附加SCEB桥墩结构进行了易损性分析.结果表明:在小震作用下,SCEB仅为桥墩结构提供刚度和承载力,在大震作用下还可提供耗能能力,同时可以提供良好的自复位能力;附加SCEB可有效降低桥墩结构在近场脉冲型地震动作用下的失效概率(最大侧移率和残余侧移率),特别是残余侧移率;附加SCEB桥墩结构在近场脉冲型地震动作用下的失效概率大于远场无脉冲型地震动作用下的失效概率.自复位耗能支撑可有效减小桥墩结构的失效概率,提高桥墩结构的抗震性能.展开更多
An approach to control the profiles of interstory drift ratios along the height of building structures via topology optimization is proposed herein.The theoretical foundation of the proposed approach involves solving ...An approach to control the profiles of interstory drift ratios along the height of building structures via topology optimization is proposed herein.The theoretical foundation of the proposed approach involves solving a min-max optimization problem to suppress the maximum interstory drift ratio among all stories.Two formulations are suggested:one inherits the bound formulation and the other utilizes a p-norm function to aggregate all individual interstory drift ratios.The proposed methodology can shape the interstory drift ratio profiles into inverted triangular or quadratic patterns because it realizes profile control using a group of shape weight coefficients.The proposed formulations are validated via a series of numerical examples.The disparity between the two formulations is clear.The optimization results show the optimal structural features for controlling the interstory drift ratios under different requirements.展开更多
The plasma catalytic degradation of o-xylene in simulated air was improved by loading low amounts of Pt,Pd,or Au onto Co_(3)O_(4).At room temperature,o-xylene conversion and CO_(x)selectivity using a0.1 wt%Pt/Co_(3)O_...The plasma catalytic degradation of o-xylene in simulated air was improved by loading low amounts of Pt,Pd,or Au onto Co_(3)O_(4).At room temperature,o-xylene conversion and CO_(x)selectivity using a0.1 wt%Pt/Co_(3)O_(4)catalyst reached 98.9%and 80%,and the energy efficiency was at the top level in comparison with values in the literature.A stable o-xylene degradation performance could be obtained by online regenerating the heat-insulated reactor with a high energy density.After characterization,it was found that the loading of nanosized Pt not only increased the Co^(3+)/Co^(2+)ratio,where the Co^(3+)benefitted the formation of reactive oxygen species,but also conduced Pt^(0)to oxygen activation,resulting in effective promotion of complete o-xylene oxidation.Operando plasma diffuse reflectance infrared Fourier transform spectroscopy demonstrated the complete o-xylene oxidation and proved that Pt played a key role in the complete oxidation of o-xylene.展开更多
文摘Buckling-restrained braces(BRBs)have shown their capability to provide building structures with stiffness,strength,and ductility.Estimating the seismic drifts of buckling-restrained braced frames(BRBFs)is an important design step to control structural and non-structural damage.In current practice of seismic design,the estimation of seismic drifts of BRBFs is performed by using empirical calculations that are independent upon either the type of the structural system or the design level of seismicity.In these empirical calculations,the seismic drifts are estimated by amplifying the reduced elastic drifts obtained under design lateral loading with a displacement amplification factor(DAF).The value of DAF is considered equal to the product of the response modification factor R and the inelastic displacement ratioρ.The goal of the current research is to assess the value ofρfor low-to mid-rise BRBFs designed under low and high levels of seismicity.This goal has been achieved by conducting a series of elastic and inelastic time-history analyses pertaining to an ensemble of earthquake records on 3-,6-and 9-story BRBFs.The results indicate that theρ-ratio increases with an increase in design seismic intensity and an increase in experienced inelasticity.The range ofρfor low seismicity designs ranges from 0.63 to 0.9,while for high seismicity designs this range stretches from 0.83 to 1.29.It has been found that the consideration of a generalρ-ratio of 1.0 is a reasonable estimation for the design of the BRBFs considered in this study.
基金The authors would like to extend their gratitude to Universiti Teknologi PETRONAS (Malaysia)for funding this research through grant number (015LA0-037).
文摘Every application in a smart city environment like the smart grid,health monitoring, security, and surveillance generates non-stationary datastreams. Due to such nature, the statistical properties of data changes overtime, leading to class imbalance and concept drift issues. Both these issuescause model performance degradation. Most of the current work has beenfocused on developing an ensemble strategy by training a new classifier on thelatest data to resolve the issue. These techniques suffer while training the newclassifier if the data is imbalanced. Also, the class imbalance ratio may changegreatly from one input stream to another, making the problem more complex.The existing solutions proposed for addressing the combined issue of classimbalance and concept drift are lacking in understating of correlation of oneproblem with the other. This work studies the association between conceptdrift and class imbalance ratio and then demonstrates how changes in classimbalance ratio along with concept drift affect the classifier’s performance.We analyzed the effect of both the issues on minority and majority classesindividually. To do this, we conducted experiments on benchmark datasetsusing state-of-the-art classifiers especially designed for data stream classification.Precision, recall, F1 score, and geometric mean were used to measure theperformance. Our findings show that when both class imbalance and conceptdrift problems occur together the performance can decrease up to 15%. Ourresults also show that the increase in the imbalance ratio can cause a 10% to15% decrease in the precision scores of both minority and majority classes.The study findings may help in designing intelligent and adaptive solutionsthat can cope with the challenges of non-stationary data streams like conceptdrift and class imbalance.
文摘为了研究桥墩结构的震后功能可恢复性,针对附加自复位耗能支撑(self-centering energy dissipation braces,SCEB)双柱式桥墩结构进行基于增量动力分析方法的地震易损性分析,采用最大侧移率和残余侧移率作为性能指标,系统探讨其在近场脉冲型地震动作用下的失效概率.为了对比分析,同时选取60条远场无脉冲型地震动记录对附加SCEB桥墩结构进行了易损性分析.结果表明:在小震作用下,SCEB仅为桥墩结构提供刚度和承载力,在大震作用下还可提供耗能能力,同时可以提供良好的自复位能力;附加SCEB可有效降低桥墩结构在近场脉冲型地震动作用下的失效概率(最大侧移率和残余侧移率),特别是残余侧移率;附加SCEB桥墩结构在近场脉冲型地震动作用下的失效概率大于远场无脉冲型地震动作用下的失效概率.自复位耗能支撑可有效减小桥墩结构的失效概率,提高桥墩结构的抗震性能.
基金supported by the National Natural Science Foundation of China(Grant No.51638012)。
文摘An approach to control the profiles of interstory drift ratios along the height of building structures via topology optimization is proposed herein.The theoretical foundation of the proposed approach involves solving a min-max optimization problem to suppress the maximum interstory drift ratio among all stories.Two formulations are suggested:one inherits the bound formulation and the other utilizes a p-norm function to aggregate all individual interstory drift ratios.The proposed methodology can shape the interstory drift ratio profiles into inverted triangular or quadratic patterns because it realizes profile control using a group of shape weight coefficients.The proposed formulations are validated via a series of numerical examples.The disparity between the two formulations is clear.The optimization results show the optimal structural features for controlling the interstory drift ratios under different requirements.
基金supported by National Natural Science Foundation of China(No.12075037)Research and Application Service Platform Project of API Manufacturing Environmental Protection and Safety Technology in China(No.2020-0107-3-1)。
文摘The plasma catalytic degradation of o-xylene in simulated air was improved by loading low amounts of Pt,Pd,or Au onto Co_(3)O_(4).At room temperature,o-xylene conversion and CO_(x)selectivity using a0.1 wt%Pt/Co_(3)O_(4)catalyst reached 98.9%and 80%,and the energy efficiency was at the top level in comparison with values in the literature.A stable o-xylene degradation performance could be obtained by online regenerating the heat-insulated reactor with a high energy density.After characterization,it was found that the loading of nanosized Pt not only increased the Co^(3+)/Co^(2+)ratio,where the Co^(3+)benefitted the formation of reactive oxygen species,but also conduced Pt^(0)to oxygen activation,resulting in effective promotion of complete o-xylene oxidation.Operando plasma diffuse reflectance infrared Fourier transform spectroscopy demonstrated the complete o-xylene oxidation and proved that Pt played a key role in the complete oxidation of o-xylene.
