Seismic reliability of steel structures isolated using the frictional pendulum system bearings and subjected to artificial earthquake ground motions is studied herein. The superstructure is idealised as a linear shear...
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Seismic reliability of steel structures isolated using the frictional pendulum system bearings and subjected to artificial earthquake ground motions is studied herein. The superstructure is idealised as a linear shear-type flexible building as well as the FPS devices are described by adopting a widespread model which considers the variation of the friction coefficient with the velocity. The uncertainty affecting both the seismic inputs, modelled as non stationary random processes within the power spectral density method, and the friction coefficient at large velocity is considered through appropriate probability density functions. Incremental dynamic analyses are developed in order to evaluate the fragility curves related to both superstructure and isolation level. Finally, considering the seismic hazard curve related to a site near Sant'Angelo dei Lombardi (Italy), the seismic reliability of the overall steel system is evaluated.
The contribution presents the results of 3D-stochastic modelling of slab-subsoil interaction. The cooperation between the centric loaded concrete foundation slab (square shape, dimension 2 m x 2 m, thickness 0.1 m) ha...
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ISBN:
(纸本)9786197105322
The contribution presents the results of 3D-stochastic modelling of slab-subsoil interaction. The cooperation between the centric loaded concrete foundation slab (square shape, dimension 2 m x 2 m, thickness 0.1 m) has been modeled as a contact problem using software MIDAS GTS (based on the finite element method). To take into account the stochastic character of the soil characteristics the stochastic simulation latin hypercube sampling method was used. Four input stochastic parameters of soil were considered -elastic modulus, unit weight, friction angle and cohesion. From the contact modelling viewpoint two variants were modelled - first variant neglected the interface elements on the contact, in the second one the interface elements were involved into the model. The contribution presents the 90% confidence interval for the settlement in the centre of the upper surface of the slab and for the contact stresses below the slab also. The results of experimental measurements were used to the calibration of the model.
This study demonstrates an application of uncertainty analysis in evaluating methods of discharge measurement including: the velocity-area, rating curve and efficient methods based on the probabilistic velocity distri...
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This study demonstrates an application of uncertainty analysis in evaluating methods of discharge measurement including: the velocity-area, rating curve and efficient methods based on the probabilistic velocity distribution equation. The measurement of river discharge plays a large part in the distribution of water resources. The conventional methods of discharge measurement are costly, time-consuming, and dangerous. Therefore the efficient method of discharge measurement which bases on the relationship between maximum and mean velocities being constant was employed to justify its alternative for the conventional methods: velocity-area and rating curve methods. Distribution test was applied to investigate the statistical properties of the uncertainties involved in the three methods of discharge measurement. latinhypercubesampling (LHS) method was employed accordingly to assess the discharge features of the three methods of discharge measurement. The main purpose of this study is to quantify the uncertainty involved in several discharge measurement methods and justify the availability and reliability of using the efficient method as an alternative of the conventional methods. Results show that the correlation analysis also validates that the efficient method is a more reliable method than the rating curve method to yield accurate discharge measurements. Moreover, it also yielded comparably accurate measurements as those by the velocity-area method.
Plug-in electric vehicles (PEVs) appear to offer a promising option for mitigating greenhouse emission. However, uncoordinated PEV charging can weaken the reliability of power systems. The proper accommodation of PEVs...
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Plug-in electric vehicles (PEVs) appear to offer a promising option for mitigating greenhouse emission. However, uncoordinated PEV charging can weaken the reliability of power systems. The proper accommodation of PEVs in a power grid imposes many challenges on system planning and operations. This work aims to investigate optimal PEV coordination strategies with cost-benefit analysis. In Part I, we first present a new method to calculate the charging load of PEVs with a modified latinhypercubesampling (LHS) method for handling the stochastic property of PEVs. We then propose a new two-stage optimization model to discover the optimal charging states of PEVs in a given day. Using this model, the peak load with charging load of PEVs is minimized in the first stage and the load fluctuation is minimized in the second-stage with peak load being fixed as the value obtained in the first stage. An algorithm based on linear mixed-integer programming is provided as a suitable solution method with fast computation. Finally, we present a new method to calculate the benefit and cost for a PEV charging and discharging coordination strategy from a social welfare approach. These methods are useful for developing PEV coordination strategies in power system planning and supporting PEV-related policy making.
Stochastic finite element method is the main analysis method of complicated stochastic structure, and it is mainly applied to the Monte Carlo simulation method. Its samplingmethod is commonly called the latin Hypercu...
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Stochastic finite element method is the main analysis method of complicated stochastic structure, and it is mainly applied to the Monte Carlo simulation method. Its samplingmethod is commonly called the latin hypercube sampling method. But for stochastic finite element analysis, and if level numbers for sampling are too many, sampling numbers will be difficult for most engineering purposes. In this paper, uniform samplingmethod is applied. Calculating examples with different factors and levels are compared with calculating examples in which latin hypercube sampling method is applied. Calculating examples show that when sampling numbers by uniform sampling technique is obviously fewer than sampling numbers by latinhypercube, mean values and standard deviations of displacements, stresses of node by the two samplingmethods are almost completely identical. Uniform samplings for stochastic finite element analysis have good computing efficiency, and have certain applied perspectives.
The objective of this paper is to present an efficient computational methodology to obtain the optimal system structure of electronic devices by using either a single or a multiobjective optimization approach, while c...
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The objective of this paper is to present an efficient computational methodology to obtain the optimal system structure of electronic devices by using either a single or a multiobjective optimization approach, while considering the constraints on reliability and cost. The component failure rate uncertainty is taken under consideration and it is modeled with two alternative probability distribution functions. The latin hypercube sampling method is used to simulate the probability distributions. An optimization approach was developed using the simulated annealing algorithm because of its flexibility to be applied in various system types with several constraints and its efficiency in computational time. This optimization approach can handle efficiently either the single or the multiobjective optimization modeling of the system design. The developed methodology was applied to a power electronic device and the results were compared with the results of the complete enumeration of the solution space. The stochastic nature of the best solutions for the single objective optimization modeling of the system design was sampled extensively and the robustness of the developed optimization approach was demonstrated. (C) 2004 Elsevier Ltd. All rights reserved.
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