The role of ground improvement in bridging the gap between a discontinuous reality and a continuous model

2021 ◽  
pp. 223-235
Author(s):  
S. Xu ◽  
P. Grasso ◽  
M. Bohlouli
Keyword(s):  
Ground Improvement ◽  
Continuous Model

scholarly journals Geosynthetic reinforced column supported embankments and the role of ground improvement installation effects

2018 ◽  
Vol 55 (6) ◽  
pp. 792-809 ◽  
Author(s):  
Daniel J. King ◽  
Abdelmalek Bouazza ◽  
Joel R. Gniel ◽  
R. Kerry Rowe ◽  
Ha H. Bui
Keyword(s):  
Soil Structure ◽  
Ground Improvement ◽  
Three Dimensional ◽  
Installation Effects ◽  
Lateral Forces ◽  
Lateral Resistance ◽  
Embankment Stability ◽  
Numerical Approaches

For geosynthetic reinforced column supported embankments (GRCSE) supporting a high embankment, lateral forces associated with lateral sliding and embankment stability often govern the acceptability of a given design under serviceability conditions. Frequently, the complex soil–structure–geosynthetic interaction, the size, and the three-dimensional nature of a GRCSE necessitate the use of numerical analysis to assess embankment performance relative to serviceability criteria. However, traditional finite element method techniques used to model serviceability behaviour are limited in their ability to model the geotechnical mechanisms associated with column installation, equilibration, and group installation effects. These installation effects are examined herein based on a GRCSE field case study located in Melbourne, Australia, that has been extensively instrumented. The role that these installation effects have on the performance of the GRCSE is highlighted and the behaviour of the columns supporting the embankment is emphasized. It is shown that cracking of the unreinforced columns supporting the embankment is likely inevitable and that the reduction of lateral resistance provided by the columns should be accounted for in design. The suitability of various numerical approaches currently used in design to model the columns supporting the GRCSE, and the embankment itself, are discussed and recommendations are made.

INSTANTANEOUS INFORMATION ALWAYS STABILIZES?

2011 ◽  
Vol 56 (02) ◽  
pp. 239-253
Author(s):  
YANG ZHANG ◽  
WEIHONG HUANG
Keyword(s):  
Local Stability ◽  
Continuous Model ◽  
Stability Loss ◽  
Cost Structure ◽  
Bertrand Competition ◽  
Two Dimensional ◽  
Additional Stability ◽  
The Impact ◽  
Cournot And Bertrand Competition

The impact of information improvement on local stability is examined for continuous dynamics. It is conventionally believed that removal of uncertainty always brings additional stability to an existing equilibrium. This paper shows that the relation between information and equilibrium stability may not be monotonic. Removal of information lag may sometimes destabilize the otherwise stable continuous model. Economic applications to Cournot and Bertrand competition are examined where the role of improved information on stability is shown to be cost-structure specific. Elimination of lags may cause stability loss. The conclusion drawn on two-dimensional continuous dynamics is briefly generalized to multidimensional system.

scholarly journals A General Discrete Time Model of Population Dynamics in the Presence of an Infection

2009 ◽  
Vol 2009 ◽  
pp. 1-15 ◽  
Author(s):  
Giuseppe Izzo ◽  
Yoshiaki Muroya ◽  
Antonia Vecchio
Keyword(s):  
Discrete Model ◽  
Reproduction Number ◽  
Continuous Model ◽  
Host Population ◽  
Threshold Parameter ◽  
Time Model ◽  
Limiting Behavior ◽  
Discrete Time Model ◽  
Discrete Counterpart

We present a set of difference equations which generalizes that proposed in the work of G. Izzo and A. Vecchio (2007) and represents the discrete counterpart of a larger class of continuous model concerning the dynamics of an infection in an organism or in a host population. The limiting behavior of this new discrete model is studied and a threshold parameter playing the role of the basic reproduction number is derived.

scholarly journals Predicting size effects in nickel-base single crystal superalloys with the Discrete-Continuous Model

2010 ◽  
pp. 65-76
Author(s):  
Aurélien Vattré ◽  
Benoit Devincre ◽  
Arjen Roos ◽  
Frédéric Feyel
Keyword(s):  
Mechanical Properties ◽  
Flow Stress ◽  
Finite Elements ◽  
Single Crystal ◽  
Size Effects ◽  
Continuous Model ◽  
Dislocation Dynamics ◽  
Formation And Evolution ◽  
Nickel Base

The Discrete-Continuous Model, a coupling between dislocation dynamics and finite elements simulations, is used for modelling size effects in the mechanical properties of single-crystal superalloys. Both formation and evolution of the dislocation microstructures are analysed, and the crucial role of the storage of signed dislocations at the interfaces is discussed. The onset of plasticity is found to scale as the inverse of the channel width, and polarised dislocation networks at the interfaces significantly increase the flow stress with respect to a bulk crystal.

scholarly journals A quantitative network modeling approach to evaluate the role of cytokine combinations on CD4+ T cell differentiation, partial polarization, and plasticity

2017 ◽  
Author(s):  
Mariana E. Martinez-Sanchez ◽  
Leonor Huerta ◽  
Elena R. Alvarez-Buylla ◽  
Carlos Villarreal
Keyword(s):  
T Cells ◽  
Transcription Factors ◽  
T Cell ◽  
Continuous Model ◽  
Cd4 T Cell ◽  
System Level ◽  
Exogenous Factors ◽  
Plastic Changes ◽  
Cellular Polarization

AbstractDiverse cellular polarization states with different phenotypes and functions are derived from the differentiation of activated CD4+ T naïve lymphocytes in the presence of particular cytokines. In addition, conversion of polarized cells to phenotypes different from that originally induced has been documented, highlighting the capacity of the immune response for adaptation to changing circumstances. In a recent study, we proposed a minimal Boolean regulatory network of CD4+ T differentiation that incorporates transcription factors, signaling pathways, and autocrine and exogenous cytokines. The qualitative model effectively reproduced the main polarized phenotypes of CD4+ T cells and several of the plasticity events reported in the literature. Yet, the amount and the expression of cytokines relative to expression of other factors influence CD4+ T cell transitions. In this paper, we have extended the Boolean network to a continuous model that allows us to assess the effect of quantitative differences in the concentrations and combinations of exogenous and endogenous cytokines, as well as diverse levels of transcription factors expression, in order to assess the role of intracellular and extracellular components in CD4+ T differentiation and plasticity. Interestingly, the model predicts either abrupt or gradual differentiation patterns between observed phenotypes depending on critical concentrations of single or multiple environmental cytokines. Plastic changes induced by environmental cytokines were observed in conditions of partial phenotype polarization in the Th1/Th2 transition. On the other hand, the Th17/iTreg transition was highly dependent on cytokine concentrations in the environment. Thus, modeling shows how the concentration of exogenous factors, the degree of initial polarization, and cell heterogeneity, may determine the differentiation and plasticity capacity of CD4+ T cells. The model and results presented here are useful to further understand system-level mechanisms underlying observed patterns of CD4+ T differentiation and plasticity.

Planning and geotechnical considerations for redevelopment of derelict industrial land in London docklands

1987 ◽  
Vol 4 (1) ◽  
pp. 429-438
Author(s):  
J. S. Gahir ◽  
A. R. Clark ◽  
P. L. Martin ◽  
A. F. Howland
Keyword(s):  
Development Strategy ◽  
Ground Improvement ◽  
Infrastructure Development ◽  
Shopping Centre ◽  
Geotechnical Investigations ◽  
The Development Strategy ◽  
Improvement Programme ◽  
London Docklands

AbstractThe redevelopment of former docklands, with docks frequently backfilled by end tipping through water, requires careful planning and a proper understanding of the geotechnical properties of the materials involved. An overall scheme for development of part of the former Surrey Commercial Docks Southwark, disused since 1960s, was formulated by London Docklands Development Corporation to provide a new environment encompassing housing, schooling, a shopping centre, social and recreation facilities and light industrial units.This paper presents a review of the development strategy and planning aspects of the development of Surrey Quays with particular reference to the assessment of the former wharf areas and the quality of the dockfill. Planning considerations, along with the role of geotechnics within the infrastructure development plan, are presented. The results of geotechnical investigations which included an extensive phase of field and laboratory testing, led to a ground improvement programme consisting of surcharge loading and vibro-replacement.

The Barents-Kara Ice Sheet response to the CMIP6-PMIP4 simulations for the LGM climate

2021 ◽  
Author(s):  
Victor van Aalderen ◽  
Sylvie Charbit ◽  
Christophe Dumas ◽  
Masa Kageyama
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Ice Sheets ◽  
Ice Sheet ◽  
Continuous Model ◽  
Last Deglaciation ◽  
Future Evolution ◽  
West Antarctic ◽  
The Last Deglaciation

<p>Recent observations show an acceleration of the glacier outflow in the West Antarctic ice sheet (WAIS) since the mid-1990s and an increase in calving events. Compared to the 1979-1990 period, mass loss from WAIS has been increased by a factor six between 2009 and 2017. The reduced buttressing effect from ice-shelf breakup may favour the ice flow from outlet glaciers and in turn the sea-level rise with potential noticeable consequences on human societies. However, despite continuous model improvements, large uncertainties are still present on the representation future evolution of the WAIS. The large panel of different results in the projections of the future sea-level rise stands, in part, to our misunderstanding of the process responsible for the marine ice sheet evolution. A possible approach to better constrain these processes, is to investigate past marine ice sheets, such as the Barents-Kara ice sheet (BKIS) at the Last Glacial Maximum (LGM), which can be considered, to a certain extent, as an analogue of the WAIS. Our objective is to study the processes responsible for the collapse of the BKIS during the last deglaciation. To simulate the evolution of the BKIS, we use the GRISLI ice-sheet model (20 km x 20 km) forced by different CMIP5/PMIP3 and CMIP6/PMIP4 models. We will present the response of the ice sheet to different types of atmospheric and oceanic forcing at the LGM coming from the PMIP models. This study represents a first step before studying more in depth the respective role of each climatic field but also the role of sea level rise coming from other LGM ice sheets in triggering the retreat of the BKIS at the beginning of the last deglaciation and the impacts of the dynamical processes.</p>

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