Coupled DEM-LBM method for the free-surface simulation of heterogeneous suspensions

The complexity of the interactions between the constituent granular and liquid phases of a suspension requires an adequate treatment of the constituents themselves. A promising way for numerical simulations of such systems is given by hybrid computational frameworks. This is naturally done, when the Lagrangian description of particle dynamics of the granular phase finds a correspondence in the fluid description. In this work we employ extensions of the Lattice-Boltzmann Method for non-Newtonian rheology, free surfaces, and moving boundaries. The models allows for a full coupling of the phases, but in a simplified way. An experimental validation is given by an example of gravity driven flow of a particle suspension

Simple Tools for Abstraction and Instantiation

A simplified version of tools for abstraction and instantiation [1,2,3] are proposed here. The tools are merely two new attributes applicable to any DS instances. The merit of abstraction and instantiation is the economy of description and clarification of structural commonality. Abstractions allow you to avoid repeating similar descriptions. You write one template to address the shared structure of descriptions and reuse it when you want similar descriptions. Suppose you want to describe many occurrences of a common pattern of events and states of affairs, such as a type of configuration of soccer players in the field. You will describe the positions of eleven or twenty two people to address this configuration. Once you have described this common pattern, you can capture each occurrence of the pattern by just substituting the eleven or twenty-two people to with particular players, without repeating the descriptions of their positions, among others. Although the AbstractionLevel DataType in MPEG-7 FDIS is apparently claimed to address abstraction and instantiation, its usage and semantics have not been clarified enough to actually employ it. What follows should provide a far simpler and practically usable set of tools for abstraction and instantiation

Report of CE on Abstraction and Instantiation

The CE on Abstraction and Instantiation [1] is reported below according to the workplan proposed at the Singapore meeting [2]

Factors Contributing to CO Uptake and Elimination in the Body: A Critical Review

BACKGROUND: Carbon monoxide (CO) poisoning is an important public health issue around the world. Research indicates that many factors may be related to the rate of CO uptake and elimination in the human body. However, some factors related to CO uptake and elimination are considered controversial. Relatively little attention has been devoted to review and synthesis of factors affecting CO uptake and elimination. PURPOSE: This paper provides a critical scoping review of the factors and divides them into four aspects, including environmental, demographic, physiological and treatment factors. METHODS: We searched the scientific databases for research that has proposed a mathematical equation as a synthesis of quantities related to CO poisoning, CO elimination, CO uptake, CO half-life, CO uptake and elimination and their relationships. After excluding the studies that did not meet the study criteria, there were 39 studies included in the review and the search was completed before 16 December 2019. RESULTS AND CONCLUSION: This review discusses most of the factors that impact the rate of CO uptake and elimination. Several factors may be related to CO uptake and elimination, such as CO concentration, the duration of exposure to CO, age, sex, exercise, minute ventilation, alveolar ventilation, total haemoglobin mass and different treatments for CO poisoning. Although some potential factors were not included in the review, the findings are useful by presenting an overview for discussing factors affecting CO uptake and elimination and provide a starting point for further study regarding strategies for CO poisoning and the environmental standard of CO

Early postoperative MRI in detecting hematoma and dural compression after lumbar spinal decompression: prospective study of asymptomatic patients in comparison to patients requiring surgical revision

Early postoperative MRI after spinal surgery is difficult to interpret because of confounding postoperative mass effects and frequent occurrence of epidural hematomas. Purpose of this prospective study is to evaluate prevalence, extent and significance of hematoma in the first postoperative week in asymptomatic patients after decompression for lumbar stenosis and to determine the degree of clinically significant dura compression by comparing with the patients with postoperative symptoms. MRI was performed in 30 asymptomatic patients (47 levels) in the first week after lumbar spine decompression for degenerative stenosis. Eleven patients requiring surgical revision (16 levels) for symptomatic early postoperative hematoma were used for comparison. In both groups the cross-sectional area of the maximum dural compression (bony stenosis and dural sac expansion) was measured preoperatively and postoperatively by an experienced radiologist. Epidural hematoma was seen in 42.5% in asymptomatic patients (20/47 levels). The median area of postoperative hematoma at the operated level was 176mm2 in asymptomatic patients and 365mm2 in symptomatic patients. The median cross-sectional area of the dural sac at the operated level was 128.5 and 0mm2 in asymptomatic and symptomatic patients, respectively, at the site of maximal compression. In the symptomatic group 75% of the patients had a maximal postoperative dural sac area of 58.5mm2 or less, whereas in the asymptomatic group 75% of patients with epidural hematoma had an area of 75mm2 or more. The size of hematoma and the degree of dural sac compression were significantly larger in patients with symptoms needing surgical revision. Dural sac area of less than 75mm2 in early postoperative MRI was found to be the threshold for clinical significanc

Salt marsh erosion rates and boundary features in a shallow Bay

Author Posting. © American Geophysical Union, 2016. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Earth Surface 121 (2016): 1861–1875, doi:10.1002/2016JF003975.Herein, we investigate the relationship between wind waves, salt marsh erosion rates, and the planar shape of marsh boundaries by using aerial images and the numerical model Coupled-Ocean-Atmosphere-Wave-Sediment-Transport Modeling System (COAWST). Using Barnegat Bay, New Jersey, as a test site, we found that salt marsh erosion rates maintain a similar trend in time. We also found a significant relationship between salt marsh erosion rates and the shape of marsh boundaries which could be used as a geomorphic indicator of the degradation level of the marsh. Slowly eroding salt marshes are irregularly shaped with fractal dimension higher than rapidly deteriorating marshes. Moreover, for low-wave energy conditions, there is a high probability of isolated and significantly larger than average failures of marsh portions causing a long-tailed distribution of localized erosion rates. Finally, we confirm the existence of a significant relationship between salt marsh erosion rate and wind waves exposure. Results suggest that variations in time in the morphology of salt marsh boundaries could be used to infer changes in frequency and magnitude of external agents.Department of the Interior Hurricane Sandy Recovery program Grant Number: GS2-2D; NSF DEB Grant Number: 0621014; OCE Grant Number: 12382122017-04-2

Multiphase debris flow simulations with the discrete element method coupled with a lattice-boltzmann fluid

Debris flows are dangerous natural hazards that occur mainly in mountainous terrains after heavy rainfall, responsible for casualties and damages reported yearly worldwide. Their heterogeneous composition, with a viscoplastic fluid and the presence of a relevant granular solid phase, leads to a non-trivial behaviour making them a challenging problem both for the physical description of the phenomena and for the design of effective protection measures. A numerical model is developed, fully coupling the two phases. A Discrete Element approach is used for the description of the solid phase, with a realistic particle size distribution, while the fluid phase is solved with a Lattice-Boltzmann Method. The effect of shape on the rolling mechanism is included with a simplified model, as well as the effects of non-Newtonian rheology and the presence of a free surface. The numerical results provide insight into complex segregation, transportation and sedimentation phenomena, essential for understanding and predicting the run-out mechanism of debris avalanches and their interaction with obstacles and retaining structures

Towards a Conceptualization of Sociomaterial Entanglement

In knowledge representation, socio-technical systems can be modeled as multiagent systems in which the local knowledge of each individual agent can be seen as a context. In this paper we propose formal ontologies as a means to describe the assumptions driving the construction of contexts as local theories and to enable interoperability among them. In particular, we present two alternative conceptualizations of the notion of sociomateriality (and entanglement), which is central in the recent debates on socio-technical systems in the social sciences, namely critical and agential realism. We thus start by providing a model of entanglement according to the critical realist view, representing it as a property of objects that are essentially dependent on different modules of an already given ontology. We refine then our treatment by proposing a taxonomy of sociomaterial entanglements that distinguishes between ontological and epistemological entanglement. In the final section, we discuss the second perspective, which is more challenging form the point of view of knowledge representation, and we show that the very distinction of information into modules can be at least in principle built out of the assumption of an entangled reality