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RISS 인기검색어
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- 저자 : Ziyan Wu (검색결과 4 건)
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Ziyan Yang,Xiaoli Yang,Rui Hu,Junfeng Wu 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2019 NANO Vol.14 No.2
Many current sorbents are limited for U(VI) concentration from aqueous solutions due to their inappropriate structures and surface chemistry. Herein, we report the rapid sorption of U(VI) with high capacities and selectivity by amidoxime modified ordered mesoporous SBA-15 with two typical morphologies (i.e., rods and plates) via a post-grafting method. Variables of the geochemical conditions (contact time, pH value, initial concentration, temperature and coexisting metal ions) are investigated. The results show that the mesostructures including morphologies and pore length of SBA-15 perform the dominant function for the fast sorption kinetics (10 min for plates, 20 min for rods), while the modified amidoxime groups make the excellent U(VI) sorption capacities (646.2 mg · g -1 for plates, 499.8 mg · g -1 for rods at pH 5.0 and T 298.15 K) and high selectivity possible. U(VI) adsorbed amidoxime-functionalized SBA can also be effectively regenerated by HCl solutions and reused well after six cycles.
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Multivariate Probabilistic Seismic Demand Model for the Bridge Multidimensional Fragility Analysis
Qi’ang Wang,Ziyan Wu,Shukui Liu 대한토목학회 2018 KSCE Journal of Civil Engineering Vol.22 No.9
Seismic fragility analysis for bridges is an essential issue for risk assessment of transportation networks exposed to seismic hazards. Considering multiple Performance Limit States (PLSs) and seismic demand parameters, the study proposes a multidimensional fragility evaluation methodology for engineering structures, and the objective of the paper is to show that the uncertainty and dependence between seismic demand parameters should be considered for fragility analysis. Thus, a new Probabilistic Seismic Demand Model (PSDM) following multivariate logarithmic normal distribution is addressed. Taking PLS correlation into consideration, multidimensional PLS formula is constructed to identify the structural failure domain. A RC bridge is studied to show the proposed theory. To consider bridge column plastic deformation and bearing nonlinear characteristic, nonlinear dynamic analyses are carried out. The bridge multidimensional fragility curves are derived and compared with fragility curves for an individual component. Results indicate that uncertainty and dependence of demand parameters can be properly dealt with by the multivariate PSDM. The multidimensional fragility is higher than fragility of any individual component, and the bridge as a system is more fragile. The ignorance of multiple components contribution to the system will generate an overestimation for the whole structural performance, which is adverse to engineering structural safety.
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Qi’ang Wang,Ziyan Wu,Lu Liu 대한토목학회 2017 KSCE Journal of Civil Engineering Vol.21 No.4
Considering uncertainty and dependence of performance limit states (PLSs), the study addresses a methodology to evaluate multidimensional fragility. The purpose is to identify the PLS uncertainty quantitatively. The dependence between each PLS parameters is also investigated. The limit state band is firstly proposed to describe the bi-dimensional case. Through interval estimation, the band area with a certain confidence level is determined. A reinforcement concrete bridge is used as example to illustrate the proposed approach for developing fragility curves. PLS threshold samples are obtained to formulate limit state function using incremental dynamic analysis. The study investigates the sensitivity of the method for fragility assessment when different confidence levels are considered. In addition, influence of correlation coefficient between PLSs is evaluated. Results show that a fragility interval is obtained with the introduction of limit state band. The interval length decreases as with the reduction of the confidence level. The probability of failure becomes smaller when the dependence between PLSs is ignored, which will result in overestimation of the structural seismic performance
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Structural System Reliability Analysis Based on Improved Explicit Connectivity BNs
Qi’ang Wang,Ziyan Wu 대한토목학회 2018 KSCE JOURNAL OF CIVIL ENGINEERING Vol.22 No.3
The study proposes an improved Explicit Connectivity Bayesian Networks (ECBNs) for system reliability assessment. The framework combines Analytic Hierarchy Process (AHP) with the traditional ECBNs. AHP is adopted to consider probabilistic dependencies between system components. Judgment matrix is constructed and weight vector, which meets the requirement of a random consistency check, is extracted to describe a conditional probability information of BNs intermediate nodes. The framework is especially suitable for the system with rare damage filed data. In addition, considering the multiple failure modes for the system component, the multi-dimensional Performance Limit State (PLS) function is proposed to estimate the marginal probability for the BNs root nodes. PLSs are properly modeled as interdependent random variables instead of deterministic quantities. Failing to properly account for the dependencies between PLSs, the non-conservative failure probability results will be obtained. Finally, the system reliability can be calculated through the BNs Junction Tree forward inference algorithm, and the most vulnerable components in the system can be identified through backward diagnose inference. The improved ECBNs theory is first applied to the system reliability evaluation for a reinforced concrete bridge to verify its validity.
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