Gravitational instability in suspension flow

The gravity-driven flow of non-neutrally buoyant suspensions is shown to be unstable to spanwise perturbations when the shearing motion generates a density profile that increases with height. The instability is simply due to having heavier material over light – a Rayleigh–Taylor-like instability. The wavelength of the fastest growing disturbance is on the order of the thickness of the suspension layer. The parameters important to the problem are the angle of inclination of the layer relative to gravity, the relative density difference between the particles and the fluid, the ratio of the particle size to the thickness of the layer and the bulk volume fraction of particles. The instability is illustrated for a range of these parameters and shown to be most pronounced at intermediate values thereof. This instability mechanism may play an important role in pattern formation in multiphase flows

Cumulative Impact of Repeated Wildfire Displacement Events on Migration in the Western United States

Climate migration has been identified as an urgent issue that will likely add greater complexity to existing climate change planning efforts (Black, 2011; Ahsan, 2011). Existing climate migration literature has primarily focused on international migration and the Global South, offering limited applicability to internal conditions in developed countries due to the issue’s high context dependency (Hoffman, 2020). Local and municipal planners have a responsibility to pursue evidence-based climate adaptation strategies (Mitchell, 2020). Yet, planners lack reliable data to forecast potential changes to regional migration based on repeated exposure to climate stressors. To date, research has been primarily qualitative in nature, leaving a need for quantitative, spatial studies to detect larger patterns in comparison to survey and interview-based findings (Piguet et al., 2018). Within developed countries, research that integrates environmental factors into typical migration estimation methods used by community development and economic planners is needed to determine the extent that rapid environment change may alter existing migration trends. In beginning to address this gap, this study tests the relationship between wildfire displacement events (i.e. evacuation events) and household out-migration rates amid a host of competing socioeconomic factors for all vii western US counties during years 2016-2019. Wildfire displacement data from the Internal Displacement Monitoring Centre (IDMC) is combined with out-migration estimates from the IRS SOI program in a times series, then joined to cross-sectional census data on county demographics to form a panel dataset for investigation. Modeling results show an expected 1.5% decrease in household out-migration rates for county years experiencing repeated wildfire displacement events in comparison to non treatment county-years. These results suggest a potential lowering of mobility capacity or desire within impacted communities for areas experiencing repeated wildfire. Whether this is linked to impacts on economic resources, i.e. exaggeration of underlying vulnerabilities, or suppressed desire to move is unclear. Direct implications for planners depend on greater understanding of causality. The study suggests that climate-related wildfire migration in the US warrants continued research, especially with focus on equity implications of unequal access to migration as a method of climate adaptation

Cumulative Impact of Repeated Wildfire Displacement Events on Migration in the Western United States

Climate migration has been identified as an urgent issue that will likely add greater complexity to existing climate change planning efforts (Black, 2011; Ahsan, 2011). Existing climate migration literature has primarily focused on international migration and the Global South, offering limited applicability to internal conditions in developed countries due to the issue’s high context dependency (Hoffman, 2020). Local and municipal planners have a responsibility to pursue evidence-based climate adaptation strategies (Mitchell, 2020). Yet, planners lack reliable data to forecast potential changes to regional migration based on repeated exposure to climate stressors. To date, research has been primarily qualitative in nature, leaving a need for quantitative, spatial studies to detect larger patterns in comparison to survey and interview-based findings (Piguet et al., 2018). Within developed countries, research that integrates environmental factors into typical migration estimation methods used by community development and economic planners is needed to determine the extent that rapid environment change may alter existing migration trends. In beginning to address this gap, this study tests the relationship between wildfire displacement events (i.e. evacuation events) and household out-migration rates amid a host of competing socioeconomic factors for all western US counties during years 2016-2019. Wildfire displacement data from the Internal Displacement Monitoring Centre (IDMC) is combined with out-migration estimates from the IRS SOI program in a times series, then joined to cross-sectional census data on county demographics to form a panel dataset for investigation. Modeling results show an expected 1.5% decrease in household out-migration rates for county-years experiencing repeated wildfire displacement events in comparison to non-treatment county-years. These results suggest a potential lowering of mobility capacity or desire within impacted communities for areas experiencing repeated wildfire. Whether this is linked to impacts on economic resources, i.e. exaggeration of underlying vulnerabilities, or suppressed desire to move is unclear. Direct implications for planners depend on greater understanding of causality. The study suggests that climate-related wildfire migration in the US warrants continued research, especially with focus on equity implications of unequal access to migration as a method of climate adaptation

Enabling Large-Scale Testing of IaaS Cloud Platforms on the Grid'5000 Testbed

International audienceAlmost ten years after its premises, the Grid'5000 platform has become one of the most complete testbeds for designing or evaluating large-scale distributed systems. Initially dedicated to the study of High Performance Computing, the infrastructure has evolved to address wider concerns related to Desktop Computing, the Internet of Services and more recently the Cloud Computing paradigm. In this paper, we present the latest mechanisms we designed to enable the automated deployment of the major open-source IaaS cloudkits (i.e., Nimbus, OpenNebula, CloudStack, and OpenStack) on Grid'5000. Providing automatic, isolated and reproducible deployments of cloud environments lets end-users study and compare each solution or simply leverage one of them to perform higher-level cloud experiments (such as investigating Map/Reduce frameworks or applications)

An Algorithm for File Transfer Scheduling in Grid Environments

This paper addresses the data transfer scheduling problem for Grid environments, presenting a centralized scheduler developed with dynamic and adaptive features. The algorithm offers a reservation system for user transfer requests that allocates them transfer times and bandwidth, according to the network topology and the constraints the user specified for the requests. This paper presents the projects related to the data transfer field, the design of the framework for which the scheduler was built, the main features of the scheduler, the steps for transfer requests rescheduling and two tests that illustrate the system's behavior for different types of transfer requests.Comment: Proceedings of the International Workshop on High Performance Grid Middleware (HiPerGrid), pp. 33-40, Bucharest, Romania, 21-22 November, 2008. (ISSN: 2065-0701