Creep of frozen slopes and ice-filled rock joints under temperature variation

2006 ◽  
Vol 33 (6) ◽  
pp. 719-725 ◽  
Author(s):  
Branko Ladanyi
Keyword(s):  
Creep Behavior ◽  
Large Scale ◽  
Variable Temperature ◽  
Theoretical Models ◽  
Rock Joints ◽  
Interface Problems ◽  
Frozen Ground ◽  
Rock Glaciers ◽  
Rock Interface ◽  
Creep Temperature

Owing to climate warming trends, there has been an increasing interest in recent years in the accelerating creep of rock glaciers and frozen slopes. In the field of glaciology, the creep of glaciers has been extensively studied, observed, and analyzed for more than 100 years. Many valuable and detailed theoretical models have been proposed through the years for simulating the creep behavior of glaciers. This synthesis paper has no intention of proposing another one. Its purpose is only to supply to these models a potential geotechnical background, borrowed from the connected fields of frozen ground mechanics, rock mechanics, and the mechanics of mixtures. In particular, this paper attempts to extend some known models of mechanical behavior of unfrozen soil and rock masses to masses containing ice and to apply these models to large-scale creep of ice–rock mixtures and ice–rock interface problems under variable temperature and stress conditions.Key words: ice, rock, mixture, rock joints, slope stability, creep, temperature.

Opinion Dynamics Optimization by Varying Susceptibility to Persuasion via Non-Convex Local Search

2021 ◽  
Vol 16 (2) ◽  
pp. 1-34
Author(s):  
Rediet Abebe ◽  
T.-H. HUBERT Chan ◽  
Jon Kleinberg ◽  
Zhibin Liang ◽  
David Parkes ◽  
...  
Keyword(s):  
Local Search ◽  
Objective Function ◽  
Iterative Process ◽  
Large Scale ◽  
Opinion Dynamics ◽  
Theoretical Models ◽  
Global Optimum ◽  
Local Optimum ◽  
Opinion Formation ◽  
Long Line

A long line of work in social psychology has studied variations in people’s susceptibility to persuasion—the extent to which they are willing to modify their opinions on a topic. This body of literature suggests an interesting perspective on theoretical models of opinion formation by interacting parties in a network: in addition to considering interventions that directly modify people’s intrinsic opinions, it is also natural to consider interventions that modify people’s susceptibility to persuasion. In this work, motivated by this fact, we propose an influence optimization problem. Specifically, we adopt a popular model for social opinion dynamics, where each agent has some fixed innate opinion, and a resistance that measures the importance it places on its innate opinion; agents influence one another’s opinions through an iterative process. Under certain conditions, this iterative process converges to some equilibrium opinion vector. For the unbudgeted variant of the problem, the goal is to modify the resistance of any number of agents (within some given range) such that the sum of the equilibrium opinions is minimized; for the budgeted variant, in addition the algorithm is given upfront a restriction on the number of agents whose resistance may be modified. We prove that the objective function is in general non-convex. Hence, formulating the problem as a convex program as in an early version of this work (Abebe et al., KDD’18) might have potential correctness issues. We instead analyze the structure of the objective function, and show that any local optimum is also a global optimum, which is somehow surprising as the objective function might not be convex. Furthermore, we combine the iterative process and the local search paradigm to design very efficient algorithms that can solve the unbudgeted variant of the problem optimally on large-scale graphs containing millions of nodes. Finally, we propose and evaluate experimentally a family of heuristics for the budgeted variant of the problem.

In Situ Tests on Creep Behavior of Rock Mass with Joint or Shearing Zone in Foundation of Large-Scale Hydroelectric Projects

2004 ◽  
Vol 261-263 ◽  
pp. 1097-1102 ◽  
Author(s):  
Jian Liu ◽  
Xia Ting Feng ◽  
Xiu Li Ding ◽  
Huo Ming Zhou
Keyword(s):  
Rock Mass ◽  
Creep Behavior ◽  
Large Scale ◽  
Time Dependent ◽  
Three Gorges Project ◽  
Three Gorges ◽  
The Three Gorges ◽  
The Three Gorges Project

The time-dependent behavior of rock mass, which is generally governed by joints and shearing zones, is of great significance for engineering design and prediction of long-term deformation and stability. In situ creep test is a more effective method than laboratory test in characterizing the creep behavior of rock mass with joint or shearing zone due to the complexity of field conditions. A series of in situ creep tests on granite with joint at the shiplock area of the Three-Gorges Project and basalt with shearing zone at the right abutment of the Xiluodu Project were performed in this study. Based on the test results, the stress-displacement-time responses of the joints and basalt are analyzed, and their time-dependent constitutive model and model coefficients are given, which is crucial for the design to prevent the creep deformations of rock masses from causing the failure of the operation of the shiplock gate at the Three-Gorges Project and long-term stability of the Xiluodu arc dam.

Rock glaciers, protalus ramparts and related phenomena, Rondane, Norway: a continuum of large-scale talus-derived landforms

Boreas ◽  
2008 ◽  
Vol 16 (3) ◽  
pp. 305-317 ◽  
Author(s):  
RICHARD A. SHAKESBY ◽  
ALASTAIR G. DAWSON ◽  
JOHN A. MATTHEWS
Keyword(s):  
Large Scale ◽  
Rock Glaciers

MobiDB-lite 3.0: fast consensus annotation of intrinsic disorder flavors in proteins

2020 ◽  
Author(s):  
Marco Necci ◽  
Damiano Piovesan ◽  
Damiano Clementel ◽  
Zsuzsanna Dosztányi ◽  
Silvio C E Tosatto
Keyword(s):  
Large Scale ◽  
Theoretical Models ◽  
Intrinsic Disorder ◽  
Low Complexity ◽  
Compositional Bias ◽  
Intrinsically Disordered ◽  
Intrinsically Disordered Regions ◽  
Proteome Level ◽  
And Performance

Abstract Motivation The earlier version of MobiDB-lite is currently used in large-scale proteome annotation platforms to detect intrinsic disorder. However, new theoretical models allow for the classification of intrinsically disordered regions into subtypes from sequence features associated with specific polymeric properties or compositional bias. Results MobiDB-lite 3.0 maintains its previous speed and performance but also provides a finer classification of disorder by identifying regions with characteristics of polyolyampholytes, positive or negative polyelectrolytes, low-complexity regions or enriched in cysteine, proline or glycine or polar residues. Subregions are abundantly detected in IDRs of the human proteome. The new version of MobiDB-lite represents a new step for the proteome level analysis of protein disorder. Availability and implementation Both the MobiDB-lite 3.0 source code and a docker container are available from the GitHub repository:https://github.com/BioComputingUP/MobiDB-lite

scholarly journals High resolution parameter study of the vertical shear instability

2020 ◽  
Vol 499 (2) ◽  
pp. 1841-1853
Author(s):  
Natascha Manger ◽  
Hubert Klahr ◽  
Wilhelm Kley ◽  
Mario Flock
Keyword(s):  
Aspect Ratio ◽  
Large Scale ◽  
Dead Zone ◽  
Pressure Ratio ◽  
Theoretical Models ◽  
Shear Instability ◽  
Vertical Shear ◽  
Parameter Study ◽  
Aspect Ratios ◽  
Strong Scaling

ABSTRACT Theoretical models of protoplanetary discs have shown the vertical shear instability (VSI) to be a prime candidate to explain turbulence in the dead zone of the disc. However, simulations of the VSI have yet to show consistent levels of key disc turbulence parameters like the stress-to-pressure ratio α. We aim to reconcile these different values by performing a parameter study on the VSI with focus on the disc density gradient p and aspect ratio h = H/R. We use full 2π 3D simulations of the disc for chosen set of both parameters. All simulations are evolved for 1000 reference orbits, at a resolution of 18 cells per h. We find that the saturated stress-to-pressure ratio in our simulations is dependent on the disc aspect ratio with a strong scaling of α∝h2.6, in contrast to the traditional α model, where viscosity scales as ν∝αh2 with a constant α. We also observe consistent formation of large scale vortices across all investigated parameters. The vortices show uniformly aspect ratios of χ ≈ 10 and radial widths of approximately 1.5H. With our findings we can reconcile the different values reported for the stress-to-pressure ratio from both isothermal and full radiation hydrodynamics models, and show long-term evolution effects of the VSI that could aide in the formation of planetesimals.

scholarly journals Ice Segregation as an Origin for Lenses of Non-Glacial Ice in “Ice-Cemented” Rock Glaciers

1981 ◽  
Vol 27 (97) ◽  
pp. 506-510 ◽  
Author(s):  
William J. Wayne
Keyword(s):  
Groundwater Flow ◽  
Large Scale ◽  
Water Pressure ◽  
Snow Melt ◽  
Total Thickness ◽  
Rock Glacier ◽  
Glacial Ice ◽  
Substantial Loss ◽  
Rock Glaciers ◽  
Ice Segregation

AbstractIn order to flow with the gradients observed (10° to 15°) rock glaciers cannot be simply ice-cemented rock debris, but probably contain masses or lenses of debris-free ice. The nature and origin of the ice in rock glaciers that are in no way connected to ice glaciers has not been adequately explained. Rock glaciers and talus above them are permeable. Water from snow-melt and rain flows through the lower part of the debris on top of the bedrock floor. In the headward part of a rock glacier, where the total thickness is not great, if this groundwater flow is able to maintain water pressure against the base of an aggrading permafrost, segregation of ice lenses should take place. Ice segregation on a large scale would produce lenses of clear ice of sufficient size to permit the streams or lobes of rock debris to flow with gradients comparable to those of glaciers. It would also account for the substantial loss in volume that takes place when a rock glacier stabilizes and collapses.

Public–Private Partnerships in the health sector: the Danish experience

2008 ◽  
Vol 3 (2) ◽  
pp. 141-163 ◽  
Author(s):  
KARSTEN VRANGBÆK*
Keyword(s):  
Health Care ◽  
Large Scale ◽  
Health Sector ◽  
Theoretical Models ◽  
Public Private Partnerships ◽  
Public And Private ◽  
Theoretical Approaches ◽  
General Terms ◽  
Danish Health ◽  
Private And Public

AbstractThis article investigates the current use of Public–Private Partnerships (PPP) in the Danish health sector based on an initial discussion of theoretical approaches that analyze PPP. The empirical analysis concludes that PPP has been used very sparsely in the Danish health sector. There are few examples of large-scale partnership projects with joint investment and risk taking, but a number of smaller partnerships such as jointly owned companies at the regional level. When defining PPP more broadly, we can identify a long tradition for various types of collaboration between public and private actors in health care in Denmark. An analysis of the regulatory environment is offered as an explanation for the limited use of PPPs in Denmark. Major political and institutional actors at the central level differ in their enthusiasm for the PPP concept, and the regulatory framework is somewhat uncertain. A number of general issues and concerns related to PPPs are also discussed. It is suggested that a risk-based framework can be useful for mapping the potential and challenges for both private and public partners. Such a framework can be used to feed into game theoretical models of pros and cons for PPP projects. In general terms, it is concluded that more empirical research is needed for the assessment of the various risk factors involved in using PPPs in health care. Most PPPs are still very young, and the evidence on performance and broader governance issues is only just emerging. Ideally, such assessments should include comparisons with a purely public alternative.

scholarly journals Biogenic gradients in algal density affect the emergent properties of spatially self-organized mussel beds

2014 ◽  
Vol 11 (96) ◽  
pp. 20140089 ◽  
Author(s):  
Quan-Xing Liu ◽  
Ellen J. Weerman ◽  
Rohit Gupta ◽  
Peter M. J. Herman ◽  
Han Olff ◽  
...  
Keyword(s):  
Large Scale ◽  
Scale Effects ◽  
Water Layer ◽  
Theoretical Models ◽  
Emergent Properties ◽  
Stable States ◽  
Mussel Beds ◽  
Self Organized ◽  
Proposed Model ◽  
Secondary Productivity

Theoretical models highlight that spatially self-organized patterns can have important emergent effects on the functioning of ecosystems, for instance by increasing productivity and affecting the vulnerability to catastrophic shifts. However, most theoretical studies presume idealized homogeneous conditions, which are rarely met in real ecosystems. Using self-organized mussel beds as a case study, we reveal that spatial heterogeneity, resulting from the large-scale effects of mussel beds on their environment, significantly alters the emergent properties predicted by idealized self-organization models that assume homogeneous conditions. The proposed model explicitly considers that the suspended algae, the prime food for the mussels, are supplied by water flow from the seaward boundary of the bed, which causes in combination with consumption a gradual depletion of algae over the simulated domain. Predictions of the model are consistent with properties of natural mussel patterns observed in the field, featuring a decline in mussel biomass and a change in patterning. Model analyses reveal a fundamental change in ecosystem functioning when this self-induced algal depletion gradient is included in the model. First, no enhancement of secondary productivity of the mussels comparing with non-patterns states is predicted, irrespective of parameter setting; the equilibrium amount of mussels is entirely set by the input of algae. Second, alternate stable states, potentially present in the original (no algal gradient) model, are absent when gradual depletion of algae in the overflowing water layer is allowed. Our findings stress the importance of including sufficiently realistic environmental conditions when assessing the emergent properties of self-organized ecosystems.

scholarly journals Attenuation of sound in a low Mach Number nozzle flow

1979 ◽  
Vol 91 (2) ◽  
pp. 209-229 ◽  
Author(s):  
M. S. Howe
Keyword(s):  
Mach Number ◽  
Large Scale ◽  
Low Frequency ◽  
Theoretical Models ◽  
Vortex Sheet ◽  
Acoustic Energy ◽  
Nozzle Flow ◽  
Finite Width ◽  
Low Mach Number ◽  
Contraction Ratio

This paper examines the energy conversion mechanisms which govern the emission of low frequency sound from an axisymmetric jet pipe of arbitrary nozzle contraction ratio in the case of low Mach number nozzle flow. The incident acoustic energy which escapes from the nozzle is partitioned between two distinct disturbances in the exterior fluid. The first of these is the free-space radiation, whose directivity is equivalent to that produced by monopole and dipole sources. Second, essentially incompressible vortex waves are excited by the shedding of vorticity from the nozzle lip, and may be associated with the large-scale instabilities of the jet. Two linearized theoretical models are discussed. One of these is an exact linear theory in which the boundary of the jet is treated as an unstable vortex sheet. The second assumes that the finite width of the mean shear layer of the real jet cannot be neglected. The analytical results are shown to compare favourably with recent attenuation measurements.

scholarly journals Abell 1763 and its Cluster Feeding Filament: Constraints on the Intra-filament Medium

2010 ◽  
Vol 6 (S277) ◽  
pp. 309-312
Author(s):  
Louise O. V. Edwards ◽  
Dario Fadda
Keyword(s):  
Star Formation ◽  
Radio Source ◽  
Large Scale ◽  
Theoretical Models ◽  
Observational Constraints ◽  
Cosmological Simulations ◽  
Large Scale Structures ◽  
Scale Structures ◽  
Intermediate Density

AbstractGalaxies are found to inhabit a variety of environments. They are often found in pairs, groups, or clusters. Cosmological simulations predict that these clusters are connected on a larger scale by filaments, but because these large scale structures are so vast, and because they are of intermediate density, observational constraints on their properties are difficult to achieve. We find a large-scale filament in the Abell 1763-Abell 1770 superstructure, determine that the star-formation therein is enhanced, and uncover a bent double lobe radio source midway across the filament. From the bend of this AGN'a jets, we probe the density of the surrounding intra-filament medium (IFM), constrained to be between 1-20x10−29 gm/cm3. This density is consistent with direct probes of the IFM as well as theoretical models.

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