• Title/Summary/Keyword: Deterministic models

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Response transformation factors for deterministic-based and reliability-based seismic design

  • Bojorquez, Eden;Bojorquez, Juan;Ruiz, Sonia E.;Reyes-Salazar, Alfredo;Velazquez-Dimas, Juan
    • Structural Engineering and Mechanics
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    • v.46 no.6
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    • pp.755-773
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    • 2013
  • One of the main requirements of the seismic design codes must be its easy application by structural engineers. The use of practically-applicable models or simplified models as single-degree-of-freedom (SDOF) systems is a good alternative to achieve this condition. In this study, deterministic and probabilistic response transformation factors are obtained to evaluate the response in terms of maximum ductility and maximum interstory drifts of multi-degree-of-freedom (MDOF) systems based on the response of equivalent SDOF systems. For this aim, five steel frames designed with the Mexican City Building Code (MCBC) as well as their corresponding equivalent SDOF systems (which represent the characteristics of the frames) are analyzed. Both structural systems are subjected to ground motions records. For the MDOF and the simplified systems, incremental dynamic analyses IDAs are developed in first place, then, structural demand hazard curves are obtained. The ratio between the IDAs curves corresponding to the MDOF systems and the curves corresponding to the simplified models are used to obtain deterministic response transformation factors. On the other hand, demand hazard curves are used to calculate probabilistic response transformation factors. It was found that both approaches give place to similar results.

Analysis of Consolidation considering Uncertainties of Geotechnical Parameters and Reliability method (지반특성의 불확실성과 신뢰성 기법을 고려한 압밀해석)

  • Lee, Kyu-Hwan
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.11 no.4
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    • pp.138-146
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    • 2007
  • Geotechnical performance at the soft ground is strongly dependent on the properties of the soil beneath and adjacent to the structure of interest. These soil properties can be described using deterministic and/or probabilistic models. Deterministic models typically use a single discrete descriptor for the parameter of interest. Probabilistic models describe parameters by using discrete statistical descriptors or probability distribution density functions. The consolidation process depends on several uncertain parameters including the coefficients of consolidation and coefficients of permeability in vertical and horizontal directions. The implication of this uncertain parameter in the design of prefabricated vertical drains for soil improvement is discussed. A sensitivity analysis of the degree of consolidation and calculation of settlements to these uncertain parameters is presented for clayey deposits.

Recent research towards integrated deterministic-probabilistic safety assessment in Korea

  • Heo, Gyunyoung;Baek, Sejin;Kwon, Dohun;Kim, Hyeonmin;Park, Jinkyun
    • Nuclear Engineering and Technology
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    • v.53 no.11
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    • pp.3465-3473
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    • 2021
  • For a long time, research into integrated deterministic-probabilistic safety assessment has been continuously conducted to point out and overcome the limitations of classical ET (event tree)/FT (fault tree) based PSA (probabilistic safety assessment). The current paper also attempts to assert the reason why a technical transformation from classical PSA is necessary with a re-interpretation of the categories of risk. In this study, residual risk was classified into interpolating- and extrapolating-censored categories, which represent risks that are difficult to identify through an interpolation or extrapolation of representative scenarios due to potential nonlinearity between hardware and human behaviors intertwined in time and space. The authors hypothesize that such risk can be dealt with only if the classical ETs/FTs are freely relocated, entailing large-scale computation associated with physical models. The functional elements that are favorable to find residual risk were inferred from previous studies. The authors then introduce their under-development enabling techniques, namely DICE (Dynamic Integrated Consequence Evaluation) and DeBATE (Deep learning-Based Accident Trend Estimation). This work can be considered as a preliminary initiative to find the bridging points between deterministic and probabilistic assessments on the pillars of big data technology.

Stochastic Fatigue Life Assesment based on Bayesian-inference (베이지언 추론에 기반한 확률론적 피로수명 평가)

  • Park, Myong-Jin;Kim, Yooil
    • Journal of the Society of Naval Architects of Korea
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    • v.56 no.2
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    • pp.161-167
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    • 2019
  • In general, fatigue analysis is performed by using deterministic model to estimate the optimal parameters. However, the deterministic model is difficult to clearly describe the physical phenomena of fatigue failure that contains many uncertainty factors. With regard to this, efforts have been made in this research to compare with the deterministic model and the stochastic models. Firstly, One deterministic S-N curve was derived from ordinary least squares technique and two P-S-N curves were estimated through Bayesian-linear regression model and Markov-Chain Monte Carlo simulation. Secondly, the distribution of Long-term fatigue damage and fatigue life were predicted by using the parameters obtained from the three methodologies and the long-term stress distribution.

Current and Future Directions for Researches on Supply Chain Management (공급사슬경영의 연구 동향 및 향후 연구 과제)

  • Kim, Sook-Han;Lee, Young-Hae
    • Proceedings of the Korean Operations and Management Science Society Conference
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    • 2000.10a
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    • pp.103-106
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    • 2000
  • As the industrial environment becomes more competitive, supply chain management (SCM) has become recognized as a major strategy in the business world. Some of current researches are categorized into review papers, deterministic models, stochastic models, simulation models and discussed in this paper. A hybrid approach combining analytic model and simulation model and the simulation optimization method are proposed as future research areas with other analytical subjects.

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Current Status and Future Research Directions in Supply Chain Management (공급사슬경영 연구의 현황 및 향후 연구 방향)

  • Kim, Sook-Han;Lee, Young-Hee
    • IE interfaces
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    • v.13 no.3
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    • pp.288-295
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    • 2000
  • As the industrial environment becomes more competitive, supply chain management(SCM) has become recognized as a major strategy in the business world. Despite its current widespread popularity, its basic concepts are confused with those of other exiting logistic tools and not clearly understood. This paper introduces the current status of SCM in terms of physical logistics, interrelationship with other logistic tools as well as the general history and definitions of SCM. Researches are categorized into deterministic models, stochastic models, simulation models, and several future research areas are discussed in this paper.

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An Applied Technique of Linear Programming Using Multi-Softwares (다종 S/W 적용에 의한 선형계획법 연구)

  • 한계섭
    • The Journal of Information Systems
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    • v.5
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    • pp.21-41
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    • 1996
  • Linear programming has become an important tool in decision-making of modern business management. This remarkable growth can be traced to the pioneering efforts of many individuals and research organizations. The popular using of personal computers make it very easy to process those complicated linear programming models. Furthermore advanced linear programming software packages assist us to solve L.P. models without any difficult process. Even though the advanced L.P. professional packages, the needs of more detailed deterministic elements for business decisions have forced us to apply dynamic approaches for more resonable solutions. For the purpose of these problems applying to the "Mathematica" packages which is composed of mathematic tools, the simplex processes show us the flexible and dynamic decision elements included to any other professional linear programming tools. Especially we need proper dynamic variables to analyze the shadow prices step by step. And applying SAS(Statistical Analysis System) packages to the L.P. problems, it is also one of the best way to get good solution. On the way trying to the other L.P. packages which are prepared for Spreadsheets i.e., MS-Excel, Lotus-123, Quatro etc. can be applied to linear programming models. But they are not so much useful for the problems. Calculating simplex tableau is an important method to interpret L.P. format for the optimal solution. In this paper we find out that the more detailed and efficient techniques to interpret useful software of mathematica and SAS for business decision making of linear programming. So it needs to apply more dynamic technique of using of Mathematica and SAS multiple software to get more efficient deterministic factors for the sophiscated L.P. solutions.

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Leverage in Regression Models with MA(1) Errors (오차항이 MA(1) 과정을 따르는 회귀모형에서의 Leverage)

  • 이종협
    • Journal of Applied Reliability
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    • v.3 no.2
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    • pp.127-136
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    • 2003
  • This paper investigates the effect of individual observations in regression models with MA(1) errors through the 'hat matrix' It shows that the first observation has the largest hat matrix diagonal component for $\theta$<0 in the regression model with an intercept. This provides additional evidence for retaining the first observation in performing estimation in this setting. When the regression model goes to the origin and the independent variable has a deterministic trend, the last observation has the greatest leverage for │$\theta$│<1 and may have potentially large impact on parameter estimation.

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Corrosion initiation time models in RC coastal structures based on reliability approach

  • Djeddi, Lamine;Amirat, Abdelaziz
    • Advances in concrete construction
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    • v.9 no.2
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    • pp.149-159
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    • 2020
  • The present work proposes new engineering models for determining corrosion initiation time in concrete reinforcing steels in marine environment. The models are based on Fick's second law that is commonly used for chloride diffusion. The latter is based on deterministic analyses involving the most influencing parameters such as distance of the concrete structure from the seaside, depth of steel concrete cover, ambient temperature, relative humidity and the water-cement ratio. However, a realistic corrosion initiation time cannot be estimated because of the uncertainties associated to the different parameters of the models. Therefore a reliability approach using FORM/SORM method has been applied to develop the proposed engineering models integrating a limit state function and a reliability index β. As a result, the corrosion initiation time is expressed by new exponential engineering models where the uncertainties are associated to the model parameters. The main emerging result is a realistic decision tool for corrosion planning inspection.