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Hybrid simulation is a powerful test method for evaluating the seismic performance of structural systems. This method makes it feasible that only critical components of a structure be experimentally tested. This paper presents a newly proposed integration algorithm for seismic hybrid simulation which is aimed to extend its capabilities to a wide range of systems where existing methods encounter some limitations. In the proposed method, which is termed the variable time step (VTS) integration method, an implicit scheme is employed for hybrid simulation by eliminating the iterative phase on experimental element, the phase which is necessary in regular implicit applications. In order to study the effectiveness of the VTS method, a series of numerical investigations are conducted which show the successfulness of the VTS method in obtaining accurate, stable and converged responses. Then, in a comparative approach, the improved accuracy of the VTS method over commonly used integration methods is demonstrated. The stability of the VTS method is also studied and the results show that it provides conditional stability; however, its stability limit is well beyond the accuracy limit. The effect of time delay on the VTS method results is also investigated and it is shown that the VTS method is quite successful in handling this experimental error. 相似文献
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Maedeh Galehdar Habibollah Younesi Mojtaba Hadavifar Ali Akbar Zinatizadeh 《洁净——土壤、空气、水》2009,37(8):629-637
In the present study, the effects of initial COD (chemical oxygen demand), initial pH, Fe2+/H2O2 molar ratio and UV contact time on COD removal from medium density fiberboard (MDF) wastewater using photo‐assisted Fenton oxidation treatment were investigated. In order to optimize the removal efficiency, batch operations were carried out. The influence of the aforementioned parameters on COD removal efficiency was studied using response surface methodology (RSM). The optimal conditions for maximum COD removal efficiency from MDF wastewater under experimental conditions were obtained at initial COD of 4000 mg/L, Fe2+/H2O2 molar ratio of 0.11, initial solution pH of 6.5 and UV contact time of 70 min. The obtained results for maximum COD removal efficiency of 96% revealed that photo‐assisted Fenton oxidation is very effective for treating MDF wastewater. 相似文献
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The hydrochemical characteristics of groundwater in the southern parts of Tehran Province are considered. Twenty-three sampling stations were selected and major anions/cations, electrical conductivity and pH were detected. Sulfate and chloride were found as major anions, while no specific dominant cation was determined. More than half of the samples were found to be unsuitable for drinking purposes, due to high concentrations of anions/cations. Regarding agricultural use, almost all samples were classified as having high-risk levels of salinity, while for alkali hazard considerable risks were observed in most cases. Generally, an increasing trend of salinity is observed from northwest to southeast of the study area. Such increase may be justified by the adjacency of the Iran central desert and salt lake to the southern boundaries of the study area. Extended use of sulfate-containing fertilizers may also play a key role in justifying the high sulfate concentration in comparison to other anions. 相似文献
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Sadeghi Maedeh Jandaghi Alaee Farshid Akbarzadeh Bengar Habib Jafari Abouzar 《Bulletin of Earthquake Engineering》2022,20(11):6075-6107
Bulletin of Earthquake Engineering - Although self-centering rocking walls have shown acceptable performance in decreasing downtime, repair cost, and continuous serviceability, their energy... 相似文献
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T. Nasrabadi P. Abbasi Maedeh 《International Journal of Environmental Science and Technology》2014,11(2):293-302
Groundwater quality of Tehran city is considered in this study. Nine sampling stations were selected, and composite sampling campaign was performed in summer 2012. Groundwater sampled from northern stations appeared to have acceptable characteristics for agricultural and drinking uses. The southern station samples did not meet the required guidelines. Concentration of SO4 2?, Na+ and Cl? obey a sharp ascending trend southwards. Accordingly, the electrical conductivity of the last station at the very southern areas is more than fifteen times greater than that of the first northern station. Tehran city is located in a semi-arid climate and experiences long hot summers. High rates of evapo-transpiration within urban green spaces and agricultural lands facilitate the salinization phenomenon in root zones. As a result, excess irrigation water eases the consequent percolation into aquifers. Furthermore, saline water intrusion from salt marshes located down south of the city is an expected consequence of wells overpumping. Such case is especially remarkable in hot seasons when an increased urban water demand is observed. Remarkable sulfate concentrations in saline water are mainly justified by percolation of sulfate containing fertilizers which are broadly used by local farmers in an uncontrolled manner. Surface run-offs and municipal wastewater leakage may also trigger the salinization process. 相似文献
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