scholarly journals Internal Instability in Soils: A Critical Review of the Fundamentals and Ramifications

2021 ◽  
pp. 036119812110569
Author(s):  
Sandun M. Dassanayake ◽  
Ahmad A Mousa ◽  
Saman Ilankoon ◽  
Gary J Fowmes
Keyword(s):  
Structural Integrity ◽  
Empirical Studies ◽  
Particle Migration ◽  
Internal Erosion ◽  
Computational Techniques ◽  
Theoretical Understanding ◽  
Soil Matrix ◽  
Internal Instability ◽  
Classical Studies ◽  
Fine Particle Migration

Seepage-induced fine-particle migration that leads to a change in the conductivity of a soil matrix is referred to as internal instability. This could jeopardize the structural integrity of the soil matrix by initiating suffusion (or suffosion), a form of internal erosion. Susceptibility to suffusion has been studied mostly under extreme laboratory conditions to develop empirical design criteria, which are typically based on the particle size distribution. The physics governing the process have not been comprehensively uncovered in the classical studies because of experimental limitations. Mainstream evaluation methods often over-idealize the suffusion process, holding a probabilistic perspective for estimating constriction sizes and fines migration. Prospective studies on constitutive modeling techniques and modern computational techniques have allowed a more representative evaluation and deeper insight into the problem. Recent advances in sensing technologies, visualization, and tracking techniques have equally enriched the quality of the data on suffusion. This paper sets out to present the long-standing knowledge on the internal instability phenomenon in soils. An attempt is made to pinpoint ambiguities and underscore research gaps. The classical empirical studies and modern visualizing techniques are integrated with particle-based numerical simulations to strengthen the theoretical understanding of the phenomenon.

Contribution of the transport of suspended particles to the internal erosion in soils. Particle migration in porous media

2007 ◽  
Vol 11 (4) ◽  
pp. 493-506
Author(s):  
Ahmed Benamar ◽  
Nasr-Dine Ahfir ◽  
Abdellah Alem ◽  
Huaqing Wang
Keyword(s):  
Porous Media ◽  
Suspended Particles ◽  
Particle Migration ◽  
Internal Erosion

scholarly journals Computational-Driven Epitope Verification and Affinity Maturation of TLR4-Targeting Antibodies

2021 ◽  
Vol 22 (11) ◽  
pp. 5989
Author(s):  
Bilal Ahmad ◽  
Maria Batool ◽  
Moon Suk Kim ◽  
Sangdun Choi
Keyword(s):  
Rational Design ◽  
Structural Integrity ◽  
Critical Role ◽  
Autoimmune Encephalitis ◽  
Affinity Maturation ◽  
Antibody Binding ◽  
Computational Techniques ◽  
Multiple Strategies ◽  
Binding Epitope

Toll-like receptor (TLR) signaling plays a critical role in the induction and progression of autoimmune diseases such as rheumatoid arthritis, systemic lupus erythematous, experimental autoimmune encephalitis, type 1 diabetes mellitus and neurodegenerative diseases. Deciphering antigen recognition by antibodies provides insights and defines the mechanism of action into the progression of immune responses. Multiple strategies, including phage display and hybridoma technologies, have been used to enhance the affinity of antibodies for their respective epitopes. Here, we investigate the TLR4 antibody-binding epitope by computational-driven approach. We demonstrate that three important residues, i.e., Y328, N329, and K349 of TLR4 antibody binding epitope identified upon in silico mutagenesis, affect not only the interaction and binding affinity of antibody but also influence the structural integrity of TLR4. Furthermore, we predict a novel epitope at the TLR4-MD2 interface which can be targeted and explored for therapeutic antibodies and small molecules. This technique provides an in-depth insight into antibody–antigen interactions at the resolution and will be beneficial for the development of new monoclonal antibodies. Computational techniques, if coupled with experimental methods, will shorten the duration of rational design and development of antibody therapeutics.

scholarly journals Greek Literature, the Digital Humanities, and the Shifting Technologies of Reading

2016 ◽  
Author(s):  
Elton Barker ◽  
Melissa Terras
Keyword(s):  
Multispectral Imaging ◽  
Digital Tools ◽  
Computational Techniques ◽  
Latin Literature ◽  
Classical Literature ◽  
Greek Literature ◽  
Digital Medium ◽  
Digital Text ◽  
Classical Studies ◽  
Technological Developments

Contrary perhaps to expectation, Classical studies is at the vanguard of the latest technological developments for using digital tools and computational techniques in research. This article outlines its pioneering adoption of digital tools and methods, and investigates how the digital medium is helping to transform the study of Greek and Latin literature. It discusses the processes and consequences of digitization, explaining how technologies like multispectral imaging are increasing the textual corpus, while examining how annotation, engagement, and reuse are changing the way we think about “the text”. It also considers how the digital turn is reinvigorating textual analysis, by exploring the broader ecosystem, within which the digital text can now be studied, and which provides enriched contexts for understanding that are constantly shifting and expanding. Classical literature in the digital age has the potential to both challenge dominant modes of thinking about antiquity and disrupt traditional ways of doing research.

scholarly journals The Effect of Suffusion Phenomenon in the Increasing of Land Subsidence Rate

2016 ◽  
Vol 2 (7) ◽  
pp. 316-323 ◽  
Author(s):  
Elmira Khaksar Najafi ◽  
Hadi Faghihmaleki
Keyword(s):  
Land Subsidence ◽  
Alluvial Soil ◽  
Ground Surface ◽  
Seepage Flow ◽  
Internal Erosion ◽  
Alluvial Soils ◽  
Sedimentary Deposits ◽  
Subsidence Rate ◽  
Internal Instability ◽  
Ground Surface Settlement

Land subsidence is defined as gradually ground surface settlement in an aquifer due to the compaction of unconsolidated sedimentary deposits. Since in an aquifer, deposits consist of cohesive or non-cohesive alluvial soil layers. The consolidation theory cannot be explained as the only reason for land subsidence. According to the susceptibility of alluvial soils to suffusion, internal erosion is also considerable to enhance the rate of the local settlement. Suffusion is explained as a process of soil particle movement in the soil body due to the effect of seepage flow on it. The subsidence rate in southwest and south of Tehran in Iran is very considerable whereby some structures have suffered significant damages due to this phenomenon. In this research, the contribution of suffusion and land subsidence was investigated in damaged building located at Ghale Morghi Street in southwest of Tehran, as a case history. Because of the incapability of available methods, in this article, a probability pattern is also proposed using statistical analysis for determination the likelihood of internal instability in alluvial soils in regard to soil cohesiveness.

scholarly journals Determination of the Porosity Distribution during an Erosion Test Using a Coaxial Line Cell

Sensors ◽  
2019 ◽  
Vol 19 (3) ◽  
pp. 611 ◽  
Author(s):  
Tilman Bittner ◽  
Mathieu Bajodek ◽  
Thierry Bore ◽  
Eric Vourc’h ◽  
Alexander Scheuermann
Keyword(s):  
Spatial Distribution ◽  
Dielectric Permittivity ◽  
Transmission Line ◽  
Computational Model ◽  
Coaxial Line ◽  
Optimization Method ◽  
Time Domain Reflectometry ◽  
Internal Erosion ◽  
Inversion Algorithm ◽  
Soil Matrix

The detection of porosity changes within a soil matrix caused by internal erosion is beneficial for a better understanding of the mechanisms that induce and maintain the erosion process. In this paper, an electromagnetic approach using Spatial Time Domain Reflectometry (STDR) and a transmission line model is proposed for this purpose. An original experimental setup consisting of a coaxial cell which acts as an electromagnetic waveguide was developed. It is connected to a transmitter/receiver device both measuring the transmitted and corresponding reflected electromagnetic pulses at the cell entrance. A gradient optimization method based on a computational model for simulating the wave propagation in a transmission line is applied in order to reconstruct the spatial distribution of the soil dielectric permittivity along the cell based on the measured signals and an inversion algorithm. The spatial distribution of the soil porosity is deduced from the dielectric permittivity profile by physically based mixing rules. Experiments were carried out with glass bead mixtures of known dielectric permittivity profiles and subsequently known spatial porosity distributions to validate and to optimize both, the proposed computational model and the inversion algorithm. Erosion experiments were carried out and porosity profiles determined with satisfying spatial resolution were obtained. The RMSE between measured and physically determined porosities varied among less than 3% to 6%. The measurement rate is sufficient to be able to capture the transient process of erosion in the experiments presented here.

scholarly journals Numerical Simulation of the Fluid–Solid Coupling Mechanism of Internal Erosion in Granular Soil

Water ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 137 ◽  
Author(s):  
Yu Wang ◽  
Junrui Chai ◽  
Zengguang Xu ◽  
Yuan Qin ◽  
Xin Wang
Keyword(s):  
Numerical Model ◽  
Information Exchange ◽  
Stokes Equations ◽  
Exchange Process ◽  
Hydraulic Gradient ◽  
Solid Particles ◽  
Particle Migration ◽  
Internal Erosion ◽  
Particle Flow Code ◽  
Coupling Mechanism

Internal erosion involves migration and loss of soil particles due to seepage. The process of fluid–solid interaction is a complex multiphase, coupled nonlinear dynamic problem. In this study, we used Particle Flow Code (PFC3D, three-dimensional PFC) software to model solid particles, and we applied computational fluid dynamics (CFD) and the coarse mesh element method to solve the local Navier–Stokes equations. An information-exchange process for the PFC3D and CFD calculations was used to achieve fluid–solid coupling. We developed a numerical model for internal erosion of the soil and conducted relevant experiments to verify the usability of the numerical model. The mechanism of internal erosion was observed by analyzing the evolution of model particle migration, contact force, porosity, particle velocity, and mass-loss measurement. Moreover, we provide some ideas for improving the calculation efficiency of the model. This model can be used to predict the initiation hydraulic gradient and skeleton-deformation hydraulic gradient, which can be used for the design of internal erosion control.

CFD Analysis of Effects of Damage Due to Bird Strike on Fan Performance

2010 ◽  
Author(s):  
Baizura Bohari ◽  
Abdulnaser Sayma
Keyword(s):  
Experimental Data ◽  
Boundary Conditions ◽  
Structural Integrity ◽  
Operating Point ◽  
Computational Techniques ◽  
Test Case ◽  
Base Line ◽  
Bird Strike ◽  
Stall Margin ◽  
Speed Characteristic

Bird ingestion has been a hazard that affects the structural integrity and survivability of turbofan engines. It can result in deformation of one or more fan blades, in which case, the engine is likely to surge and not recover. Numerical studies and simulations of bird strikes have become essential to optimize the design of engine components simultaneously to increase the engine capabilities for acceptable damage tolerance. Good understanding of these phenomena and the implications on the behaviour of the flow field with respect to the damage affecting the fan blades are usually investigated using computational techniques and/or experimental methods. The purpose of this paper is to present a Computational Fluid Dynamics (CFD) method for the analysis of the aerodynamic behaviour of an aero-engine fan affected by a bird strike. NASA rotor 67 was used as a test case because of the availability of experimental data that can be used to calibrate the model for the undamaged fan. The undamaged fan characteristic was mapped using a modification to the methodology developed by Sayma (2007). In this method a downstream variable throttle is added which allows changing the operating point on the speed characteristic without having to change downstream boundary conditions. This approach allows for changes in fan operating point to come out of the calculation as opposed to those dictated by the downstream static pressure boundary conditions used in typical computations. The methodology is automated allowing for a sweep along a speed characteristic or along a working line in one calculation in the same way as a rig test is conducted. Agreement with experimental data when available was excellent. This provided the base line for the undamaged blades. A damaged blade was inserted among undamaged blades in the fan assembly and the fan characteristic was mapped for a range of rotational speeds. Two different degrees of damage were analysed in an attempt to establish a correlation between the extent of the damage and the locus of the stall boundary. It was found that small increments on the damage lead to significant reduction in stall margin particularly at higher rotational speeds.

scholarly journals Conceptualising Primary-Secondary School Transitions: A Systematic Mapping Review of Worldviews, Theories and Frameworks

2021 ◽  
Vol 6 ◽  
Author(s):  
Divya Jindal-Snape ◽  
Jennifer E. Symonds ◽  
Elizabeth F. S. Hannah ◽  
William Barlow
Keyword(s):  
Secondary School ◽  
Empirical Studies ◽  
School Transitions ◽  
Policy And Practice ◽  
Theoretical Frameworks ◽  
Systematic Mapping ◽  
Theoretical Understanding ◽  
Secondary School Transition ◽  
Mapping Review ◽  
Systematic Mapping Review

There is continued interest internationally in primary-secondary school transitions. Fourteen literature reviews of primary-secondary transitions have been published over the last 20 years, however none of them have systematically analysed primary-secondary school transition ontology, i.e., researchers’ worldviews, theories/models and frameworks. This is a major gap in these reviews and the papers published in this area; this is of concern as it is difficult to trust the robustness of a study if its foundation, such as researchers’ conceptualisation of transitions, is not visible. Therefore, using the Evidence for Policy and Practice Information and Co-ordinating Centre (EPPI-Centre) approach, we undertook a systematic mapping review, of empirical studies published internationally between 2008 and 2018. Our objectives were to explore researchers’ and research participants’ conceptualisation of transitions, the conceptual framework used by the researchers and their discourse about transitions. Of the 96 studies included in this systematic mapping review, most had not clearly defined transition, and even when conceptualisation was explicit, it did not underline the research design or frame the findings. Most researchers adopted previously used theoretical frameworks.These theoretical frameworks can be beneficial; however, as the researchers did not adapt or develop them in the context of transitions research, it limits a meta-theoretical understanding of transitions. Further, the majority did not report study participants’conceptualisation of transitions. Similarly, a large number of researchers adopted a negative discourse about primary-secondary school transitions, with some using a mixed discourse and only two papers had a primarily positive discourse. This systematic mapping review is original and significant as it is the first study to provide a review of school transitions ontology and offers unique insights into the conceptual and methodological gaps that international transitions researchers should address.

Empirical Analyses of Deterrence

2017 ◽  
Author(s):  
Stephen L. Quackenbush
Keyword(s):  
Empirical Studies ◽  
Empirical Support ◽  
Empirical Literature ◽  
Deterrence Theory ◽  
Theoretical Understanding ◽  
Quantitative Studies ◽  
Early Case ◽  
The Subject ◽  
Empirical Analyses

Deterrence is an important subject, and its study has spanned more than seven decades. Much research on deterrence has focused on a theoretical understanding of the subject. Particularly important is the distinction between classical deterrence theory and perfect deterrence theory. Other studies have employed empirical analyses. The empirical literature on deterrence developed at different times and took different approaches. The early empirical deterrence literature was highly limited for varying reasons. Much of the early case study literature did not seek to test deterrence theory. Early quantitative studies did seek to do so, but they were hampered by rudimentary methods, poor research design, and/or a disconnect between quantitative studies and formal theories of deterrence. Modern empirical research on deterrence has made great strides toward bridging the formal-quantitative divide in the study of deterrence and conducting theoretically driven case studies. Further, researchers have explored the effect of specific variables on deterrence, such as alliances, reputations and credibility, and nuclear weapons. Future empirical studies of deterrence should build on these modern developments. In addition, they should build on perfect deterrence theory, given its logical consistency and empirical support.

Investigating the Earth Fill Embankment of the Lotsane Dam for Internal Defects Using Time-lapse Resistivity Imaging and Frequency Domain Electromagnetics

2020 ◽  
Vol 25 (3) ◽  
pp. 325-339
Author(s):  
Bokani Nthaba ◽  
Elisha M. Shemang ◽  
Eliot A. Atekwana ◽  
Ame T. Selepeng
Keyword(s):  
Frequency Domain ◽  
Structural Integrity ◽  
Time Lapse ◽  
Internal Erosion ◽  
Conductive Layer ◽  
Dam Foundation ◽  
Resistivity Imaging ◽  
Resistivity Variation ◽  
Earth Fill

We investigated the internal structure of the Lotsane Dam for zones that may be prone to seepage and internal erosion using the electrical resistivity imaging (ERI) and the frequency domain electromagnetic (FDEM) methods. Time-lapse ERI measurements were also made for a period of 8 months in order to monitor the temporal evolution of defective zones. Results from both the FDEM and ERI measurements show two main layers. The first is an upper conductive layer varying in thickness from 10 to 25 m which is related to the clay core embankment. Situated beneath this upper conductive layer is a highly resistive crystalline basement on which the dam was founded. Furthermore, the ERI and FDEM measurements revealed the presence of fractures and possible zones of weakness within the dam foundation. Time-lapse ERI measurements revealed resistivity increases in the observed possible defective zones, including proximal to the spillway and at the embankment-foundation interface. The long-term resistivity variation may be indicating change in material properties in those portions of the dam, and may evolve to destabilize the structural integrity of the dam and or develop into preferential seepage pathways with time. The identified anomalous zones are good indicators that the embankment integrity is at risk and we suggest continuous geophysical monitoring of Lotsane Dam structure in order to ensure dam safety and integrity on the long term.

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