The Rheology of Frozen Soils

2007 ◽  
Vol 17 (1) ◽  
pp. 12147-1-12147-14 ◽  
Author(s):  
Lukas U. Arenson ◽  
Sarah M. Springman ◽  
Dave C. Sego
Keyword(s):  
Mechanical Response ◽  
Soil Mechanics ◽  
Rheological Behaviour ◽  
Theoretical Models ◽  
Complex Stress ◽  
Frozen Soil ◽  
Future Research ◽  
Frozen Soils ◽  
Current State ◽  
Number Of Factors

Abstract The rheological behaviour of frozen soils depends on a number of factors and is complex. Stress and temperature histories as well as the actual composition of the frozen soil are only some aspects that have to be considered when analysing the mechanical response. Recent improvements in measuring methods for laboratory investigations as well as new theoretical models have assisted in developing an improved understanding of the thermo-mechanical processes at play within frozen soils and representation of their response to a range of perturbations. This review summarises earlier work and the current state of knowledge in the field of frozen soil research. Further, it presents basic concepts as well as current research gaps. Suggestions for future research in the field of frozen soil mechanics are also made. The goal of the review is to heighten awareness of the complexity of processes interacting within frozen soils and the need to understand this complexity when developing models for representing this behaviour.

scholarly journals Bereavement in Times of COVID-19: A Review and Theoretical Framework

2020 ◽  
Vol 82 (3) ◽  
pp. 500-522
Author(s):  
Margaret Stroebe ◽  
Henk Schut
Keyword(s):  
Process Model ◽  
Theoretical Perspective ◽  
Theoretical Models ◽  
Dual Process ◽  
Future Research ◽  
Negative Consequences ◽  
Systematic Assessment ◽  
Current State ◽  
Expert Assessments

A review of the literature on adaptation to bereavement during the COVID-19 pandemic was conducted to assess the current state of knowledge. Scopus, Web of Science and Google Scholar databases were searched for studies published during the first 6 months of the COVID-19 outbreak. 44 articles were included in the review. Narrative synthesis showed that knowledge was largely based on expert assessments of prior bereavement research and professional experience; there is so far absence of empirical evidence linking features of COVID-19 bereavement situations to health outcomes. Severe negative consequences have been consistently predicted by authors. There is still relatively little consideration of positive or compensatory processes or the possibility that these could alleviate the effect of the shocking, traumatic circumstances. With two notable exceptions, there has been lack of attention to the role of theoretical models for guiding research and practice. A theoretical perspective (the Dual Process Model, DPM) was applied to the information derived from the available articles. Two features of the DPM framework illustrated its relevance: 1. It enables systematic assessment of the range of loss- and restoration-related challenges for the bereaved; 2. It speaks for extension of psychotherapeutic intervention to manage secondary, restoration- as well as primary, loss-oriented stressors; studies have demonstrated that this may increase the effectiveness of intervention. Directions for future research and DPM application are suggested.

Continuum Models for the Mechanical Response of Paper and Paper Composites: Past, Present, and Future

1990 ◽  
Vol 197 ◽  
Author(s):  
Jeffrey C. Suhling
Keyword(s):  
Mechanical Response ◽  
Constitutive Relations ◽  
Paper Industry ◽  
Theoretical Models ◽  
Material Behavior ◽  
Continuum Models ◽  
Future Research ◽  
Fiber Network ◽  
Structural Configurations ◽  
Paper Composites

ABSTRACTPaper and paper composites are utilized in applications where they are subjected to multiaxial stress states and changing environmental conditions. Such materials exhibit nonlinear anisotropic material behavior which is time dependent and affected adversely by slight changes in moisture content and temperature. At present, lack of adequate theoretical models often hampers the design and development of structurally optimized paper products. Therefore, it has been common practice in the pulp and paper industry to use trial and error, and empirical approaches. Accurate continuum models for the mechanical behavior of paper and paper composites are needed to guide the paper product design process.In this work, a limited review of the existing methods for modeling the mechanical response of paper and paper composites is given. At first, a brief overview of the goals of current modeling techniques based on hydrogen bond, fiber network, and continuum approaches is presented. The governing equations and capabilities of current continuum models are then discussed in greater detail. Theories which include linear elastic (generalized Hooke's Law), nonlinear elastic (hyperelastic), linear viscoelastic, nonlinear viscoelastic, and inelastic constitutive relations are addressed. Finally, applications of existing continuum theories to the analysis of paper materials in structural configurations are presented. After these discussions, the limitations of the available continuum models are assessed and future research needs are suggested.

Mathematical descriptions for the behaviour of ice-rich frozen soils at temperatures close to 0 °C

2005 ◽  
Vol 42 (2) ◽  
pp. 431-442 ◽  
Author(s):  
Lukas U Arenson ◽  
Sarah M Springman
Keyword(s):  
Strain Rate ◽  
Creep Strain ◽  
Mechanical Response ◽  
Constant Strain Rate ◽  
Frozen Soil ◽  
Unfrozen Water ◽  
Strain Rates ◽  
Frozen Soils ◽  
Apparent Cohesion ◽  
Thermomechanical Behaviour

With the use of creep and constant strain rate (CSR) tests, mathematical formulations were found that describe the thermomechanical behaviour of ice-rich frozen soils. A Glen-type relationship was chosen for the formulation of minimum creep strain rates at temperatures between –4 °C and –1 °C. The shear strength of the material could be described by a Mohr–Coulomb failure criterion. Furthermore, it was possible to compare the creep behaviour with the strength of similar soils under constant strain rates. The minimum creep strain rate increases proportionally as the temperature approaches the melting point of the ice, which can be attributed to the increasing amount of unfrozen water, which strongly influences the mechanical response. Even though only a few tests could be used for the determination of the angle of friction and the apparent cohesion, the trend showed that the volumetric ice content influences both parameters, but only the latter seems to be influenced by the temperature and the applied compression strain rate.Key words: permafrost, frozen soil, creep, strength.

Predicting Unfrozen Water Contents in Frozen Soils

1966 ◽  
Vol 3 (2) ◽  
pp. 53-60 ◽  
Author(s):  
Howard B Dillon ◽  
O B Andersland
Keyword(s):  
Water Content ◽  
Freezing Point ◽  
Soil Mechanics ◽  
Frozen Soil ◽  
Unfrozen Water ◽  
Silty Clay ◽  
Frozen Soils ◽  
Unfrozen Water Content ◽  
Experimental Values ◽  
Water Contents

A relationship between temperature and certain soil properties including specific surface area, activity ratio, and the expandable clay lattice, is presented for predicting the unfrozen water content of frozen soils. Data on experimental calorimetric determinations for ice content of two frozen clays and a frozen silty clay are given. Predicted unfrozen water contents are compared with experimental values for eleven soils with good agreement in all cases. Temperatures close to and above the freezing point depression of the soil are excluded. Knowledge of the unfrozen water content in frozen soils permits a more realistic approach to a variety of problems in frozen soil mechanics.

Self-leadership Training Review

2019 ◽  
Author(s):  
Andrew Sidwell ◽  
Michael Perry
Keyword(s):  
Leadership Training ◽  
Future Research ◽  
Training Methods ◽  
Current State ◽  
A Current

The purpose of this article was to examine the current state of self-leadership training. The authors analyzed all published, publicly available studies (in English) pertaining to self-leadership training methods, offering a current state of self-leadership training, and implications for future research.

The Social Neuroscience of Cooperation

2018 ◽  
Author(s):  
Jay Joseph Van Bavel
Keyword(s):  
Theoretical Models ◽  
Brain Regions ◽  
Review Literature ◽  
Social Neuroscience ◽  
Future Research ◽  
A Value ◽  
Group Cooperation ◽  
Neural Processes ◽  
The Social ◽  
Cooperative Decision Making

We review literature from several fields to describe common experimental tasks used to measure human cooperation as well as the theoretical models that have been used to characterize cooperative decision-making, as well as brain regions implicated in cooperation. Building on work in neuroeconomics, we suggest a value-based account may provide the most powerful understanding the psychology and neuroscience of group cooperation. We also review the role of individual differences and social context in shaping the mental processes that underlie cooperation and consider gaps in the literature and potential directions for future research on the social neuroscience of cooperation. We suggest that this multi-level approach provides a more comprehensive understanding of the mental and neural processes that underlie the decision to cooperate with others.

Cancer and Cancer Treatment-Related Cognitive Impairment

2019 ◽  
pp. 60-83
Author(s):  
James C.  Root ◽  
Elizabeth Ryan ◽  
Tim A. Ahles
Keyword(s):  
Cancer Survivors ◽  
Cancer Treatment ◽  
Clinical Presentation ◽  
Functional Neuroimaging ◽  
Theoretical Models ◽  
Future Research ◽  
Cognitive Changes ◽  
Central Nervous System Cancer ◽  
Pharmacologic Treatments

As the population of cancer survivors has grown into the millions, there is increasing emphasis on understanding how late effects of treatment impact survivors’ ability return to work/school, ability to function and live independently, and overall quality of life. Cognitive changes are one of the most feared problems among cancer survivors. This chapter describes the growing literature examining cognitive changes associated with non-central nervous system cancer and cancer treatment. Typical elements of cancer treatment are discussed, followed by a description of clinical presentation, self-reported and objectively assessed cognitive findings, and results of structural and functional neuroimaging research. Genetic and other risk factors for cognitive decline following treatment are identified and discussed, together with biomarkers and animal models of treatment-related effects. This is followed by a discussion of behavioral and pharmacologic treatments. Finally, challenges and recommendations for future research are provided to help guide subsequent research and theoretical models.

Emerging Syndromes

2017 ◽  
Author(s):  
Kelly C. Allison ◽  
Jennifer D. Lundgren
Keyword(s):  
Empirical Studies ◽  
Theoretical Models ◽  
Future Research ◽  
Night Eating Syndrome ◽  
Statistical Manual ◽  
Night Eating ◽  
Diagnostic And Statistical Manual ◽  
Impairment In Functioning ◽  
Atypical Anorexia Nervosa ◽  
Comorbid Psychopathology

The Diagnostic and Statistical Manual, fifth edition, of the American Psychiatric Association (2013) has designated several disorders under the diagnosis of otherwise specified feeding and eating disorder (OSFED). This chapter evaluates three of these, night eating syndrome (NES), purging disorder (PD), and atypical anorexia nervosa (atypical AN). It also reviews orthorexia nervosa, which has been discussed in the clinical realm as well as the popular press. The history and definition for each is reviewed, relevant theoretical models are presented and compared, and evidence for the usefulness of the models is described. Empirical studies examining the disorders’ independence from other disorders, comorbid psychopathology, and, when available, medical comorbidities, are discussed. Distress and impairment in functioning seem comparable between at least three of these emerging disorders and threshold eating disorders. Finally, remaining questions for future research are summarized.

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