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- Cao, Zi-Jun, et al.
(författare)
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State-of-the-art review of inherent variability and uncertainty in geotechnical properties and models : Chapter 6: Determining characteristic values of geotechnical parameters and resistance: an overview
- 2021
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- CEN committee TC250 is currently working on an update of the Eurocodes. Subcommittee SC10,in charge of updating EN 1990 (Basis of structural and geotechnical design has installed aworking group to produce a background document with the working title ‘Reliability Backgrounds of the Eurocodes’, with the intention to document and explain the reliability framework underlying all Eurocodes and the implementation of reliability aspects in them. As part of that effort, quantitative information on the inherent variability and uncertainty in loads, material properties and models is compiled. ISSMGE TC304 identified this as an opportunity to provide an overview of the relevant information available in the geotechnical literature such as the statistics of soil/rock properties. The EPRI TR 105000 report (Phoon et al. 1995) provided an overview of the statistics of inherent soil properties and measurement errors, but these statistics have not yet been updated systematically since 1995. Also, rock properties were not covered by the TR 105000 report. Other than soil/rock properties and measurement errors, there are also other important statistics, such as the statistics of transformation uncertainties and model factors.The current technical report has the following features:1. It serves as an update for the TR 105000 report on the statistics of inherent soil properties. Chapter 1 compiles the site specific statistics for univariate soil properties. Chapter 3 compiles the random field parameters (e.g., the scales of fluctuation) for spatial variability of soils. Many of the statistics are new.2. It contains statistics that are not covered by the TR 105000 report. Chapter 1 compiles the site specific statistics for some rock and rock mass properties. Chapter 2 compiles the site specific correlations between soil/rock properties. Chapter 5 compiles the statistics for transformation uncertainties.3. Chapter 4 compiles the statistics of geotechnical design model factors . Chapter 6 reviews methods that determine the characteristic value defined by the Eurocode 7. Chapter 7 reviews some numerical evidences for the worst case scale of fluctuation.
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| 2. |
- Guo, Lei, et al.
(författare)
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Necessary and Sufficient Conditions for Stability of LMS
- 1996
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- In a recent work (7), some general results on exponential stability of random linear equations are established which can be applied directly to the performance analysis of a wide class of adaptive algorithms including the basic LMS ones without requiring stationarity independency and boundedness assumptions of the system signals The current paper attempts to give a complete characterization of the exponential stability of the LMS algorithms by providing a necessary and sucient condition for such a stability in the case of possibly unbounded nonstationary and non ?mixing signals The results of this paper can be applied to a very large class of signals including those generated fromeg a Gaussian process via a timevarying linear lter As an application several novel and extended results on convergence and tracking performance of LMS are derived under various assumptions Neither stationarity nor Markov chain assumptions are necessarily required in the paper
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| 3. |
- Guo, Lei, et al.
(författare)
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Necessary and Sufficient Conditions for Stability of LMS
- 1995
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Guo and Ljung (1995) established some general results on exponential stability of random linear equations, which can be applied directly to the performance analysis of a wide class of adaptive algorithms, including the basic LMS ones, without requiring stationarity, independency, and boundedness assumptions of the system signals. The current paper attempts to give a complete characterization of the exponential stability of the LMS algorithms by providing a necessary and sufficient condition for such a stability in the case of possibly unbounded, nonstationary, and non-φ-mixing signals. The results of this paper can be applied to a very large class of signals, including those generated from, e.g., a Gaussian process via a time-varying linear filter. As an application, several novel and extended results on convergence and the tracking performance of LMS are derived under various assumptions. Neither stationarity nor Markov-chain assumptions are necessarily required in the paper.
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